the flex engine - scholarworks

Capstone Project – Written Report 04/14/15 Instructor: Michael Strange

ME 494 – PROJECT DESIGN II

The Flex Engine

Spring 2015

Team Members: Tyler Smith, Zachary Hayman, Eduardo Castaneda, Cameron Kiani, Scott Gibes

Faculty Advisor: Professor Tony Snell

The Flex Engine Team: Spring 2015 Report Page 1

Legal Disclaimer The technology we are developing is part of a suite of patents, both issued and pending, for one

of Murray Tech Law’s clients. In order to protect the client’s intellectual property rights, it is

important that elements of the projects are not publicly disclosed accidentally or ahead of

schedule. Therefore, while the students and faculty are free to exchange information regarding

the project as academically necessary, Murray Tech Law asks that they refrain from discussing

the technology with anyone outside of Cal Maritime. Murray Tech Law is aware that the

project will eventually be publicized, both in the form of a final report and presentation. If

there is any necessary publication of project material before the final report and presentation,

Murray Tech Law requests that they are informed of the expected date of first publication as

soon as possible.


Abstract Since the first internal combustion engine was built the design has required a rotating camshaft

to mechanically actuate the valve timing. The problem with actuating the valves on an engine

with a camshaft is there are many added losses. Turning the camshaft consumes energy from

the crankshaft which takes away from the overall power output; also the springs used to close

the valves create a large amount of parasitic losses which take away from the engine

performance. Some types of camshafts use a rocker arm assembly that requires many extra

parts and adds a considerable amount of weight to the engine. Clearly, mechanical valve timing

that uses a rotating camshaft has serious flaws; a new design that gets rid of the camshaft and

its accessories could revolutionize the internal combustion engine.

There are many companies competing to invent camless valve timing for engines, and all of

which are at the basic R&D and prototyping stage. There are no camless four stroke engines

being produced and sold on the market today. The objective of this project is to enter the

camless actuation race and create a camless valve actuator that is driven by the forces from a

piezoelectric crystal. Piezoelectric crystals expand when high voltage is applied to them. The

expansion displacement is minimal, but the forces produced are impressive, making it

undoubtedly possible to actuate the valves of an engine.

Designing a new valve actuator that does not use a camshaft is greatly beneficial for many

reasons. By eliminating the camshaft and the associated components, the engine design will be

less complex, the overall timing components on the engine will weigh less, and the removed

spring will reduce parasitic loss. Utilizing piezoelectric crystals and an electronic controller to

actuate the valves and control the timing has the potential to increase the engine efficiency up

to 20%, increase the potential horsepower up to 20%, and reduce exhaust emissions up to 50%.

This technology has the potential to change the industry, and this project summarizes how the

Cal Maritime senior capstone Flex Engine team is attempting to break into the camless internal

combustion engine market.


Photos of Project

This picture displays the main

components of the Flex Engine

project. Depicted is hand crank,

valve, legs, compression blocks,

wedge angles and main housing for

project.

This picture displays the

mechanism used to displace the

valve. In this picture is the hand

crank, cam shaft, cam lobes and

push pins used to actuate the

valve.


Gratitude and Acknowledgements A special thank you for all of the support to Ken Murray, David Smith, and Murry Tech Law for

the privilege to of being able to work on a revolutionary concept and all of the support along

the way. We would also like to thank our project faculty advisor, Anthony Snell, for all of his

guidance, knowledge and support with educational concepts needed for our project. Lastly,

we’d like to thank DSM (Dynamic Structure and Materials) for loaning the piezo crystals and

supplying the amplifier used for collecting and analyzing data on piezo crystals and their

performances.


Assembled Drawing of Project

Figure 0.1: Piezoelectric Valve Actuator Assembly


Figure 0.2: Force Transmitting Bearing


Contents Legal Disclaimer ............................................................................................................................................ 1

Abstract ......................................................................................................................................................... 2

Photos of Project ........................................................................................................................................... 3

Gratitude and Acknowledgements ............................................................................................................... 4

Assembled Drawing of Project ...................................................................................................................... 5

Contents ........................................................................................................................................................ 7

Table of Tables .............................................................................................................................................. 9

Table of Figures ........................................................................................................................................... 10

1.0 Introduction .......................................................................................................................................... 11

2.0 Literature Survey/Benchmarking .......................................................................................................... 11

3.0 Schedule ................................................................................................................................................ 13

4.0 Problem Definition Phase ..................................................................................................................... 14

4.1 Establishing User Requirements/ Clarifying Design Objectives ........................................................ 14

4.2 Identifying the Constraints................................................................................................................ 14

4.3 Identifying Functions ......................................................................................................................... 16

4.4 Establishing Design Specification ...................................................................................................... 17

5.0 Conceptual Design Phase ...................................................................................................................... 19

5.1 Generating Designs ........................................................................................................................... 19

5.2 Wedge Evolution ............................................................................................................................... 24

6.0 Preliminary Design Phase ...................................................................................................................... 26

6.1 Product Architecture ......................................................................................................................... 26

6.2 Material Selection ............................................................................................................................. 27

7.0 Final Design Phase................................................................................................................................. 29

7.1 Product Architecture ......................................................................................................................... 29

7.2 Material Selection ............................................................................................................................. 30

8.0 Engineering Design & Analysis .............................................................................................................. 31

8.1 Valve Wedge Transformation ........................................................................................................... 31

8.2 Dynamic Modeling ............................................................................................................................ 33

9.0 Fabrication Process ............................................................................................................................... 38

9.1 Design for Reliability ......................................................................................................................... 38

9.2 Design for Manufacturing ................................................................................................................. 38


9.3 Design for Assembly .......................................................................................................................... 39

10.0 Prototype Testing ................................................................................................................................ 39

11.0 Final Design Testing ............................................................................................................................ 40

12.0 Preliminary Summary .......................................................................................................................... 41

13.0 Preliminary Conclusion ....................................................................................................................... 41

14.0 Preliminary Recommendations ........................................................................................................... 42

15.0 Final Modeling, Simulation, Analysis and Testing Results .................................................................. 42

16.0 Discussion of the Final Results ............................................................................................................ 44

Piezo Design ............................................................................................................................................ 44

Valve Design ............................................................................................................................................ 45

17.0 Conclusions and Recommendations about the Project ...................................................................... 47

Piezo Design ............................................................................................................................................ 47

Valve Design ............................................................................................................................................ 47

18.0 Appendices .......................................................................................................................................... 50

18.1 Detailed Drawings ........................................................................................................................... 50

18.1.1 Overall Assembly Drawing ..................................................................................................... 50

18.1.2 Sub Assembly Drawings ........................................................................................................... 51

18.1.3 Detailed Drawings .................................................................................................................... 52

18.1.4 Bill of Materials ........................................................................................................................ 76

18.2 Computer Programs ........................................................................................................................ 79

18.5 Supporting Background Information .............................................................................................. 82

18.6 Other Relevant Information ............................................................................................................ 84

18.7 Cost Analysis ................................................................................................................................... 85

18.8 Final Project Virtual Realizations .................................................................................................... 86

18.9: Final Project Detailed Photos ......................................................................................................... 91


Tables Table 6.2.1: Possible Materials of Construction 23

Table 7.2.1: Material Selection 30

Table 15.1: Test 1 42




Figures Figure 0.1: Piezoelectric Valve Actuator Assembly 3

Figure 0.2: Force Transmitting Bearing 4

Figure 3.0.1: Gantt Chart 11

Figure 4.3.1: Black Box 14

Figure 4.3.2: Function Chart 14

Figure 4.4.1: Quality Function Diagram 15

Figure 5.1.1: Shower Head Valve 16

Figure 5.1.2: Slider Valve 17

Figure 5.1.3: Slider Valve Implemented into Manifold 18

Figure 5.1.4: Slider Valve Implemented into Manifold 18

Figure 5.1.5: Rotating Slider Valve 19

Figure 5.1.6: Modified Standard Annular Valve 20

Figure 5.2.1: First Wedge Design 21

Figure 5.2.2: Current Wedge Design 22

Figure 6.1.1: Wedge Actuator Dimensions 23

Figure 7.1.1: Wedge Concept FBD 25

Figure 7.1.2: Wedge FBD 27

Figure 7.1.3: 0.4in Vertical Valve Maximum Displacement 27

Figure 7.2.1: Intake Valve Lift vs. Camshaft Angle 30

Figure 7.2.3: 480 RPM Dynamic Model Force Requirement of Piezo 30

Figure 7.2.4: 6000 RPM (60HZ) Pure Cosine 31

Figure 7.2.5: 6000 RPM (60HZ) Pure Cosine 32

Figure 13.1.1: Roller Bearing used in CAD model 35


1.0 Introduction This projects primary focus is designing a new method of intake and exhaust valve

actuation for the automotive industry that removes the necessity of camshafts, timing chains,

and timing gears. This is a revolutionizing concept that could, potentially, forever change the

automotive industry. The Flex Engine Valve project is an innovative method for intake and

exhaust valve actuation with a wide range of engine applications on a multitude of engine sizes.

The objective of this concept incorporates piezoelectric crystals to actuate the intake and

exhaust valves. Initially, it was expected to use a typical rocker-arm valve assembly with the

piezoelectric crystals replacing the cam lobe, which would essentially create a camless engine.

In the automotive industry this is practically unheard of, and would be a major leap in

technology if actually completed. The typical engine consists of a camshaft that rotates a cam

lobe, which in turn rotates and actuates the intake and exhaust valves. This severely limits

ability of the engine to acquire an ideal square cam profile since the lobes have more of a

curvature shape to them to prevent the valve from breaking. Also, the timing of this process is

completely dependent on the timing belt which synchronizes the crankshaft and camshaft

rotations, this causes a parasitic load to the engine. The principal of the piezoelectric crystal is

to acquire more of a square cam profile where the valve is instantly opened and closed when

desired. This is acquired by supplying a low current, high voltage to the piezoelectric crystal,

which causes it to almost instantly expand, actuate the valve, and then close the valve upon

cutting off the power supply. Another positive aspect to the Flex Engine Valve project is that a

parasitic timing belt is no longer needed since the piezoelectric crystal does not require a

mechanical system to actuate it, instead it will be using electricity. Our goal for the Flex Engine

Valve project is to create a model and have a proof of concept for this innovative idea. This

includes a complete conceptual analysis using all tools available to us, such as Creo Parametric,

Creo Mechanism, and fundamentals of course work we have completed to this date.

2.0 Literature Survey/Benchmarking Our project is relatively new technology; piezoelectric crystals have been used for

actuators, but never to acquire the displacement required by our Flex Engine Valve design.

There have been two other companies that have developed camless engines, but have used

either pneumatics or hydraulics. Both have their set of drawbacks with complicated systems

and parasitic loads that take away from the engine, but regardless both companies have seen

an increase in engine efficiency by 20%, horsepower by 20% and exhaust emissions by 50%.

Several companies are focusing on various designs to improve upon the camshaft

system or remove the camshaft entirely. These companies are in the basic R&D and prototype

stages. These companies are: Valeo, Launchpoint Technology, NGV Global, Mainstream

Engineering, and Koenigsegg. Specifically, the Koenigsegg’s “Free Valve Actuators” remove the


camshaft and the timing belt, and control the valves electronically via pneumatic actuators.

Koenigsegg has already demonstrated improvements in engine efficiency, horsepower, and

exhaust emissions. All of these systems have serious drawbacks or fall short of the industry

target. The designs are highly complex yet provide only minimal control improvement. The

valves are still all operated synchronously, with no ability to change a single valve profile

independent of the others. The valve profiles are hard-coded into the engine design, usually

optimized for only one of a wide range of operating conditions. Finally, each camless

configuration cannot optimize the engine profile to take a specific fuel type. For example, the

valves cannot change to optimally accommodate higher octane or richer fuels, ethanol

mixtures, natural gas, etc.

Another competitor is Sturman Industries, a company based out of Woodland Park,

Colorado. They have taken an alternative approach to camless engine design and developed an

innovative design involving electro-hydraulic valve timing. Their design system is fast, precise,

electronically controlled and can be used on reciprocating piston engines or gas compressors. It

can also be used for engine operation for any fuel (gas, diesel, ethanol, propane, natural gas,

etc.) This electro-hydraulic valve also closely acquired the desired square profile.


3.0 Schedule The project has stayed on schedule as far as the research and development of the actuator design. Displayed below in figure 3.1.1 is

the design team gantt chart that has been closely followed throughout the semester.

Figure 3.0.1: Gantt Chart


4.0 Problem Definition Phase

4.1 Establishing User Requirements/ Clarifying Design Objectives

In order for this piezoelectric crystal valve actuator to be successful, above all else it

must be reliable and safe when operating at higher engine rpms. This is extremely critical to the

design. Since engines deal with high compression and combustion, creating an unreliable and

unsafe product would be detrimental to the process and development of our Flex Engine Valve.

Ideally, our valve should be able to operate at a maximum engine revolution per minute of

6000 (for a four stroke this equal’s 3000rmps or 50Hz cycle speed for piezo actuation). Also,

another key component when dealing with engines is heat factor. Our valve design needs to

take into consideration heating conditions expected for the duration of engine operation so we

do not experience distortion in the tight tolerances, which could lead to critical failure. Our

valve will eliminate the necessity for cam lobes, shafts and timing belts, create a less complex

system than the current mechanical system, have a quieter engine operation, significant weight

reduction to the engine, and reduce parasitic losses to engine.

4.2 Identifying the Constraints

We are constrained by strengths and weaknesses of our teams. This is displayed below.

Strengths: Team is balanced between mechanical and energy stem students so a

majority of bases are covered. The Project is a mostly mechanically oriented with relatively no

coding. Zach is comfortable with dynamic and material property analysis. Tyler is experienced

with PTC Creo Parametric and dynamic analysis. Scott and Cameron are experience with project

management, fluid mechanics and thermodynamics. Eddie is proficient with PTC Creo

Parametric, thermodynamics and dynamics. Excellent resources will be provided to us through

Weidlinger once we are approved by the company. Their resourced will be at our disposal along

with prior research.

Weakness: It has taken a long time to acquire the necessary funding due to CMA legality

issues. Our largest weakness is our teams’ lack of experience with piezoelectric crystals, let

alone the awareness of the manufacturers of single-cell crystals. This information will be

necessary in order to procure the piezoelectric stacks needed to achieve sufficient lift.

Furthermore, very few of us have dealt with modeling airflow and analyzing valve efficiencies.

While our hands-on experience will permit us to make valuable design models, we will need to

continue our research. As far as valve controller, we are not experienced with the coding used

but we do have excellent resources provided through a partnership with Weidlinger Associates

Inc. (WAI).

The Flex Engine Team: Fall 2014 Report Page 15

Opportunities: WAI holds ownership to the prior intellectual property (IP), and have

extensive knowledge of piezoelectric technologies. Not only do they have engineers in which

we can defer some of our technical questions to and hold design reviews with, WAI also

possesses patented industry leading multi-physic software that models piezoelectric crystals.

Based on the patents involved in our project, our group stands a respectable chance of learning

key details regarding the relationship between law and engineering from Murray Tech Law

(MTL) – another industry partner for our project. This project also provides us with the amazing

opportunity to gain experience with new technology that is constantly expanding in the

engineering world. We are taking something relatively new and trying to create something that

is revolutionary, that has otherwise never been attempted and thought of as a possible

application of piezoelectric crystals.

Threats: Following along the lines projected in this report, there is a possibility that our

valve design(s) will not provide enough flow for internal combustion engine (ICE) intake and

exhaust valves without mechanical amplification. While a failed concept design would be an

extreme disappointment, it will still serve as a learning experience for WAI and our group that it

is definitely not possible to use PZ crystals for ICE camless valve timing. A failure in the ICE valve

design may fork into a success story in another industry, for our valve design(s). Another

difficult aspect of the project is the difference in class schedules as about half the team is

mechanical stem while the other is energy stem. Since the workloads very, it is fairly difficult to

get together and have the appropriate amount of time to get things done. This is a fairly

ambitious project where not many teachers have experience with what we are trying to do,

with this taken into consideration our resources are relatively limited. Also, since this project is

dealing with new technology and precise tolerances it will be, perhaps, one of the more

expensive senior projects this year.

Our valve is constrained by typical engine operation with rpms and heat generated from

friction and combustion processes. With our current valve design we are battling friction due to

tight tolerances, metal-to-metal contact and high forces. This severely limits the revolution per

minute operating range of our valve. We will have to continually develop our valve model to

significantly lower coefficients of friction in order to achieve the desired operating range of our

valve.

Along with high friction forces generated, heat is produced. We have yet to complete an

analysis on the amount of heat generated, but we plan on using high heat resistant metals to

account for the heat generated, still the analysis will need to be completed in order for our

project to meet the design requirements.

Another constraint is our desired application for the valve actuation on engines.

Typically the valve assembly is not very big on most generic car engines. With this taken into


consideration, we have to keep the size down for our Flex Engine Valve and ideally want the

valve to be no more than 6 inches tall off of the engine block with a width of 4 inches. With

these design specifications achieved, the project will be considered a success and be applicable

for real world engine modifications. Along with these ideal design constraints we also have to

deal with tolerance. Since we are relatively inexperienced with this, it is a possibility to over

constrain the design. We must be cautions when designing the valve actuation method.

Once we acquire some piezoelectric crystals, we can begin to gain experience with their

functionalities prior to the application in our valve design. We will need to become familiar with

how much voltage and current are required by the piezoelectric actuator, and how to safely

operate them. Some tests will need to be completed to see approximately how much expansion

can be expected from them, and if they will function with our valve design.

4.3 Identifying Functions

The primary function of the Flex Engine Valve is to actuate a valve using piezoelectric

crystal technology. This will be acquired by applying electricity at a set voltage and current that

will cause the crystal to expand and contract, moving an intake and exhaust valve. A broad view

of what is occurring for the system is displayed below in Figure 4.3.1: Black Box. A more

detailed description for what occurs is displayed in Figure 4.3.2: Functions Chart.

Figure 4.3.1: Black Box


Figure 4.3.2: Function Chart

The primary function of this project is to build a valve actuating assembly that can

effectively open and close a valve similar to that on an internal combustion engine. The valve

actuating assembly will utilize a piezoelectric crystal to act as the primary driving force to open

and close the valve.

The secondary function required to perform the primary function is for the valve

actuating assembly to be universal enough to be installed on any automotive internal

combustion engine. The valve actuator relies on an electronic voltage pulse sent from a

controller that is linked up with a camshaft angle sensor. The valve must be able to open and

close at the required rate to for an engine to operate; for example, if an engine needs to spin at

6,000 rpm then the valve needs to operate at 50Hz.

4.4 Establishing Design Specification

The concept for piezoelectric valve actuation is cutting edge technology that has never

been implemented or thought possible for this type of application. The following figure displays

our QFD (Quality Function Deployment) and engine characteristics that we believe are most

important to design our valve around. As show below, we determined that reaching our goal

revolution per minute operating range for the Flex Engine Valve has the highest priority, with

the necessary valve lift coming in second. The reason RPMs is ranked highest is because our

project is first and foremost a proof of concept; if our valve can reach the desired RPM’s, then

clearly the application of piezoelectric crystals in automotive vales is possible.


Figure 4.4.1: Quality Function Diagram


5.0 Conceptual Design Phase Certain constraint criteria had to be met in order to accomplish the goals that the team had

previously set. In order to remove parasitic loads involved with the cam assembly, as well as

achieving variable valve timing, many designs were formulated using piezoelectric crystals as

actuator means. Early on in the design phase, designs were oriented around changing the valve

to obtain the required flow with no mechanical amplification; in other words, the piezo

displacement would be the same as the displacement of the valve during actuation. Along these

lines, many design iterations were made resulting in plausible designs. Eventually designs

utilizing mechanical amplification were a better deign alternative for this project. Displayed

below are the different designs as they evolved.

5.1 Generating Designs

Design 1

Figure 5.1.1: Shower Head Valve


Showerhead design

This design consists of two flat plate cylinders, one stationary and one moving. Vertical

movement of the top cylinder creates a small gap between the two cylinder plates. Large

arrays of circular holes are drilled into both plates. In order to attain no flow in the closed

state, never are any of the holes of both plates oriented to allow flow. All holes are offset and

never overlap. Once a gap is made between the surfaces, air can flow through the top cylinder

into the gap. Next, the air turns and flows into any one of the holes of the below cylinder. This

design can be utilized as either an intake or an exhaust valve: flow can be in either direction.

Design 2

Figure 5.1.2: Slider Valve

Slider Valve

Similar to the showerhead design, the slider design utilizes to flat plate cylinder, one stationary

and one moving. Instead of vertical movement, displacement of the valve is seen in the

direction perpendicular to the piston’s vertical axis. The slider valve has a repeating pattern of

lines, either with material or the absence of material. For example; to obstruct flow, a region of

the top cylinder containing material would be aligned with a region of the bottom cylinder


containing no material. The small spacing is used to satisfy the small displacements seen by

piezoelectric crystals. Conceptually, but not practically, this type of design could see 50% flow

area of the swept area of the valve. Although it reduces spacing between gaps, a simplified

design was formulated to use a single piezoelectric stack as means of opening and closing both

the intake and exhaust valves. This can be done by having a neutral position about the

displacement of the piezoelectric stack. For example; assuming steady state, 0%, 50%, and

100% valve displacement would translate to [1 0],[0 0], and [0 1], respectively ([intake valve;

exhaust valve], 0=closed, 1=open).

Figure 5.1.3: Slider Valve Implemented into Manifold


Figure 5.1.4: Slider Valve Implemented into Manifold


Design 3

Figure 5.1.5: Rotating Slider Valve

Rotating Slider Valve

This valve is very similar to the slider valve, but instead of linear motion of the valve, the valve

will be rotated. Because the movement of a piezoelectric crystal stack is linear, this linear force

and displacement will be translated to torque and rotation using a rack and pinion. This

translation also has the ability to utilize a gear ratio to achieve a desired mechanical

amplification.


Design 4

Figure 5.1.6: Modified Standard Annular Valve

Modified Standard Annular Valve

This type of valve is similar to the design of current vehicular engines. Because the

displacements of piezos are so small, it was deemed that an off-the-shelf poppet valve would

not attain proper flow effective area without mechanical amplification. This design repeats the

annular valve with a pattern and extrudes it in a longitudinal direction. With vertical

displacement between the top and bottom valve bodies, flow is allowed with the gaps created.

See Figure 5.1.6.

5.2 Wedge Evolution

Typically a lever is used in applications for mechanical amplification. Instead, a wedge

design was used as a means of mechanical amplification. Never has a wedge been used in this

way, in order to achieve displacement amplification. As discussed before, piezoelectric crystals

have extremely high force and reaction characteristics, but have extremely low displacements.

The wedge design utilizes the high force and speed of the piezoelectric crystal, and converts it

into very large displacements at even higher speeds, but only after force has been sacrificed.

This concept will be discussed further in section 7.0. Not only can the wedge design be used to

justify the constraints of automotive camless valve operation, this design will be patented as an

actuator with far more uses.


After analyzing and minor testing the standard poppet valve was determined to be the

best valve type. This was mostly due to the implementation of the valve to an engine head,

since the poppet valve is already used in car engines in this manner it was determined that it

would be the easiest transition to get the actuator into the head of an engine with this design.

Displayed below in figure 5.2.1 is the first poppet vale design that was created. The design was

not used because the actuator required 4 piezoelectric crystals and it also would be

unnecessarily tall. The wedge design was refined and eventually changed into what is shown in

figure 5.2.2.

Figure 5.2.1: First Wedge Design


Figure 5.2.2: Current Wedge Design

6.0 Preliminary Design Phase

6.1 Product Architecture

Our assembly is comprised of eleven main parts: two steel roller bearings, two pins to

hold the bearings in place, two piezoelectric crystal stack actuators, two compression blocks for

the actuators to push against, a poppet valve, a two-faced wedge, and a fixed body surrounding

all of these components to hold them in place. The piezoelectric actuators will rest against the

back wall of the device, which will be tightened to a specified pre-load condition to maintain

compression forces at every stage of the combustion cycle. This is due to the fact that

piezoelectric crystals easily break when not kept in compression.

The crystals will rest horizontally against the compression blocks, which will be free-

floating from one another and contain the roller bearings and pins for the bearings. The pins

will be permanently attached so that there is no possibility for them to loosen at any time and

become a hazard. The bearings attached to the compression blocks will be in constant contact

with the wedge, which will have two equivalent, oppositely facing angles from vertical. One

angle will be sloped away from the roller bearings and cause the wedge to vertically lower

(opening the valve for the intake or exhaust cycle), and the other will point towards the roller

bearings and cause the wedge to rise and reseat itself (closing the valve for the aforementioned


cycle). The poppet valve will be screwed into the wedge, completing the product architecture.

Displayed below in figure 6.1.1 are the wedge actuator dimensions.

Figure 6.1.1: Wedge Actuator Dimensions

6.2 Material Selection

Selecting the materials of construction for the valve actuator assembly is an important

step in the design of the actuator. Displayed below in table 6.2.1

Table 6.2.1: Possible Materials of Construction

We chose to make the wedge out of titanium because it is used in many high

performance engine parts. Titanium has a tremendous impact on the longevity and

performance, compared to other metals such as aluminum alloy and alloy steel, because of its

various material properties as can be seen in table 6.2.1 Titanium is lighter than steel (has a

smaller density) and is significantly stronger (has a higher yield strength). These factors give

titanium an advantage over the other two listed metals, which is why we choose it for our

Yield Strength Density Specific Stress Ranking

MPa kg*m^3 Pa/(kg*m^3) 0-10

1 Titanium (TI-6AI-4V) 882.53 4430 199216.7043 10

2 Aluminum Alloy (775) 95 2811 33795.80221 2

3 ASTM Alloy Steel 689.5 7850 87834.3949 4

Material Selection


material. For instance, if our valve were composed of titanium it would have a smoother

acceleration, which will allow better control over the valve train. The down side to titanium is

its higher cost; however, you get what you pay for: a better quality material.


7.0 Final Design Phase

7.1 Product Architecture


Our final assembly is comprised of the following main parts: top housing part, bottom

housing part, wall slider rear wall part, two wall compression block parts, two compression

blocks, two push pin shafts, two side wall cam holders, cam shaft, cams, poppet valve, linear

bearing, crank handle and two-faced wedge fixture. We designed this wedge valve actuator to

operate off of cams to actuate the valve and display the ingenuity behind the concept. The

project was designed to allow for removal of the camshaft and substituting piezo crystals for

the two push pin shafts that displace the two compression blocks and actuate the valve using

the wedge principal design.

By comparing the preliminary design product with the final design product, it should be

noted the significant design improvements and alterations. Nearly everything was changed in

the overall end product. Only the original wedge actuation concept from the Preliminary Design

phase was kept as observed by looking at the final design above.

The final design still operates on the same principles as the initial design. The crank

handle is rotated, which causes the cams to come in contact with the push pins. From here the

pushpins come into contact with the compression blocks and move them forward. The

compression block bearing applies a force on the wedges and either pushes the poppet valve

up or down. Another key component that allows the valve to move is the linear bearing located

on the back wall of the housing. This provides smooth, near frictionless linear track movement

for the valve to follow along. As previously stated, if the push pins were replaced with piezo

crystals then the design principles would still function based on the concept would still operate

the same.

7.2 Material Selection

Table 7.2.1: Material Selection

Material Selection

Density Brinell Hardness Ultimate Strength

Yield Strength

Modulus of Elasticity

Shear Strength

Fatigue Strength

Aluminum 6061 2.7 g/cc 95 310 MPa 276 MPa 68.9 GPa 207 MPa 96.5 MPa

304 Stainless Steel

8 g/cc 123 505 MPa 215 MPa 193-200

GPa N/A N/A

We used Stainless Steel 308 for the cam shaft surfaces and push pins while everything else was

made from Aluminum 6061 due to its light weight and durability. The cam shaft surfaces and push pins


were made from stainless steel 308 because we did not want any gouging effects to occur since the cam

surfaces are critical elements to the function of the final design.

8.0 Engineering Design & Analysis

8.1 Valve Wedge Transformation

Our initial design began with a simple wedge profile valve design. It operated on the

principles of having a wedge with a very small angle sloped away from vertical that would be

constrained to move horizontally. As this wedge moves towards the valve, it would come in

contact with the valve wedge surface and actuate the valve by forcing it to move in the upward

direction. By having a very small angled wedge, small x-displacement would cause a much

larger y-displacement. Essentially, a small horizontal movement of the wedge would amplify

the vertical movement of the valve; this concept is shown in figure 7.1.1 below. This is exactly

what was needed for a piezoelectric valve design. Since the piezeo’s have a relatively small

displacement, we could achieve a much greater valve displacement through the amplification.

Figure 7.1.1: Wedge Concept FBD

Of all the other designs, this one was a very simplistic proposal that seemed to offer the

best results. Initially we wanted to have the wedge angle between one and two degrees, but

some of the group members believed that due to the near flat surface, binding would definitely

occur due to the friction forces that will be created by metal on metal friction. Upon completing

some dynamic analysis, this idea was quickly proven correct; binding would occur with any less

than eight degrees from vertical for our design unless we figured designed another way to


lower the coefficient of friction on the two critical surfaces. A formula was created to relate the

minimum angle to the coefficients of friction, this formulas creation is show in figure 7.1.2 and

the formula is displayed in Equation 1.

Figure 7.1.2: Wedge FBD

Once this relationship was created, we were able to create other solutions to lower the

coefficient of friction. We researched different coatings for metal surfaces, different oils, and

even the possibility of an electromagnetic frictionless surface (this was determined too much


work though). Lastly we went back to basic physical modifications and came up with an

addition of roller bearings, which have a very low coefficient of friction compared to our initial

design of metal-on-metal surfaces. We plugged in the necessary coefficients of friction

expected from the valve design into Equation 1 and determined that the minimal angle

dropped down to 2.92 degrees with a static coefficient of friction for metal-metal surfaces (with

lube) at 0.05 and roller static friction at 0.001. This is much more desirable for our project,

which still produces the necessary amplification of the valve displacement required to actuate

the valve. This is currently our design, but it is still up for refinement. Figure 7.1.3 shows the

required piezo displacements over a range of wedge angles in order to attain a common

maximum valve displacement of 0.4in.

Figure 7.1.3: 0.4in Vertical Valve Maximum Displacement

8.2 Dynamic Modeling

Dynamic modeling analysis was carried out using Creo Mechanism within Creo 3.0

Parametric. In order to attain valve displacements over a range of RPMs, a 4-cylinder engine

was downloaded via GrabCAD. Next, the engine was simulated with a kinematic motion analysis


in Autodesk. Valve displacements relative to the crankshaft’s rotation were found at the

completion of the simulation. In order to attain the timing for the opening and closing of valves,

current engines utilize a mechanically bound link between the crankshaft and the camshaft.

Because the goal of this project is to attain camless valve actuation, there will be no

measurement of the camshaft’s rotation to base valve displacement on. For 4-stroke operation,

both the intake and exhaust valves open and close a single time over 720 degrees rotation of

the crankshaft. See Figure 7.2.1.

Next, an excel spreadsheet was formulated to convert crankshaft angle to time based on

a desired RPM of the engine. Next, a conversion from the valves vertical displacement is

converted to the displacement seen by the piezoelectric crystal using trigonometric math. This

creates a matrix with piezos displacement over time which is then imported into Creo. A servo

motor is created on Creo which drives the mechanism using the piezo’s displacement over time.

The result is the vertical movement of the wedge valve and rotation of the needle bearing

assemblies. A measure of the required force needed to obtain the desired displacement over

time is calculated by Creo. Static and Dynamic frictions were assumed to be 0.09 and 0.07,

respectively. This assumes friction to be that of lubricated metal-on-metal contact. Gravity was

also accounted for.

A simulation of actual valve displacement at 480RPM was carried out. See Figures 7.2.2

and 7.2.3. The displacement is very similar to a cosine wave with a vertical shifted resulting in a

minimum displacement of zero. There are relatively sizeable gaps in time where there is zero

displacement in between consecutive cosine curves. This can be explained by the timing of a 4-

stroke internal combustion engine. There were complexities associated with trying to make two

driving forces (piezos) for both the up and down vertical movements. By improvising, a single

horizontal slider was assumed to be the driving force of the model (both up and down driving

forces). This was done by not allowing lift-off of the cam connection between the needle valves’

circumferential surfaces and the wedges’ contact planes. A final simulation portraying a 6000

RPM redlined engine was made. See Figures 7.2.4 and 7.2.5. This time, a pure cosine wave, with

the same amplitude as before, was used for the analysis. A maximum of ~4500lbf was attained.

By optimizing the design for weight and the reduction of friction, this number will be greatly

reduced. Weight can be reduced by downsizing the parts, particularly any parts with the large

vertical accelerations. Friction can be reduced by adding linear needle bearings to the wall

which supports the backside of the wedge valve. Another way to reduce friction would be to

use Tungsten Disulfide dry lubricant coating. Even in high temperature and stress

environments, this durable coating, of only ½ micron, has the ability to reduce the dynamic

friction coefficient to as low as 0.03.


Figure 7.2.1: Intake Valve Lift vs. Camshaft Angle


Figure 7.2.2: 480 RPM Vertical Displacement

Figure 7.2.3: 480 RPM Dynamic Model Force Requirement of Piezo


Figure 7.2.4: 6000 RPM (60HZ) Pure Cosine

Figure 7.2.5: 6000 RPM (60HZ) Pure Cosine


9.0 Fabrication Process Taking into account manufacturing, assembly, and reliability aspects during the design

process is critical for a successful final product. Due to the fact that medium-scale piezoelectric

valves have not been created before, we had to start our design from scratch and were more

focused on trying to simply create a working design. After settling on the wedge-shape for the

mechanical advantage, we considered the following ways to: strengthen components to

lengthen product life, simplify the design to decrease manufacturing time, and modify element

relations to increase ease of assembly.

9.1 Design for Reliability

Design for Reliability (DFR) is incredibly important because warranty costs and customer

satisfaction with final designs can make or break a company. Both reliability and quality must

be taken into consideration when determining reliability of design. Typical quality control will

guarantee that our valve will work as intended after manufacturing and assembly, whereas

reliability deals specifically with average lifecycle of each device.

By keeping the total number of parts to a minimum, quality control can be more easily

carried out. Making any changes to the design to prevent potential failures will therefore be

significantly easier due to the simplicity of the component shapes; whether it be changing

material selection, component geometry, or manipulating the dimensions. All of these changes

could be made to reduce stresses that might be found to cause critical failures. Besides this, we

increased the strength of our device by choosing very robust parts. Piezoelectric crystals have

an extremely long life cycle when they are only used in compression, and should outlast the

other components of the engine. Other than that, selecting sturdy metals such as lightweight

titanium for the wedge and steel for the needle bearings will keep fatigue failures to a

minimum for the longest amount of time possible.

The major downfall to the piezoelectric stacks is that a flaw such as an edge crack from a

bad actuator could lead to a high chance of brittle fracture; a stress failure that occurs without

warning due to a lack of plastic deformation. To prevent this, we will simply have to purchase

our piezoelectric stacks from the most reliable manufacturer possible.

9.2 Design for Manufacturing

The goal for both Design for Manufacturing (DFM) and Design for Assembly (DFA) of our

model is to create a valve that is easily and economically produced. Reducing the number of

parts not only helps with simplifying adjustments to increase reliability and lessen the time for

quality control checks, but it also is a major step towards reducing the manufacturing costs.

Unfortunately, almost none of the components involved are standard parts commonly found,

but the dual wedge setup allows the main part of our assembly to be multi-use – opening and

closing the valve, which further decreases the number of parts. Because almost all of the


components can be fabricated using two-dimensional cuts, the only difficulty from fabrication

will be the tight tolerance of the wedge angles.

9.3 Design for Assembly

Three main aspects were considered when dealing with DFA: minimizing assembly

directions, maximizing compliance, and minimizing handling. Because of the rectangular shape

of the valve assembly, it is easy to describe the instructions for constructing it from one

direction. The rigid exterior surrounding the moving components also helps with keeping errors

during insertion phases to a minimum, which may otherwise cause damage to the finished

surfaces. Additionally, the dual piezoelectric actuators equally preload each other, so individual

torques for each does not have to be applied. During assembly, the housing will engage both

actuators simultaneously to a predetermined amount. Lastly, creating a round top to the

horizontally moving block that exaggerates asymmetry will help assemblers quickly orient and

insert the component.

10.0 Prototype Testing We are currently lacking a sufficient prototype, but we have modeled our design using

PTC Creo. Our plan for creating the prototype is to send the three-dimensional model to a

machine shop in San Leandro called Machine Logics, which would be able to create it within the

tight specifications required. Originally, we planned on creating a model using a 3-D printer due

to the fast prototyping speed possible, but a continued lack of funding from hang-ups within

the CSU system made the purchase of one impossible. We did not know this would occur, so we

researched and selected the most affordable and advanced printer within our budget. By the

time November came around, we became much more aware that obtaining the printer was not

possible, and we likely would not need it because we had already chosen a final design to

proceed with. With further research in piezoelectric manufacturers, we were able to find a local

distributor called Kinetic Ceramics, Inc. that is located in Hayward, California. We plan on

purchasing two piezoelectric stack actuators from them to use in our prototype assembly.

Upon procuring all of the components, we will construct the valve assembly and create

a MatLab code to control the charges applied to the piezoelectric actuator stacks. We will begin

testing with extremely low cycling rates until we are confident that our design and setup can

overcome the friction between components and withstand the forces applied to each. Once we

are confident with the tests at low cycling rates, we will gradually increase it and see how the

components withstand continuous actuation over longer periods of time.


11.0 Final Design Testing

Initial Testing of System with Small Linear Piezo

Continued Testing with Small Linear Piezo

Unloaded Piezo Test Setup

Loaded Piezo Test Setup

Replacing the Small Linear Piezo with the Large Linear Piezo Large Piezo Testing in Unloaded Case


12.0 Preliminary Summary During the beginning of the semester, the idea of what our final project would be was a

cam-less engine. This entailed a fully running 1 or 2 piston engine with no cam shaft, with the

valves controlled by an actuator. With this being the first piezoelectric-controlled valve, it was

necessary for us to design the actuator from scratch. The initial actuator designs were similar to

rocker arms, but we would incorporate piezoelectric crystals as the device exerting force on the

air intake and exhaust valves. After a few meetings and delegations, we trimmed down our idea

to an actuated valve assembly that we could quickly and easily mount on a redesigned engine

block. We would acquire a 3-D printer in order to duplicate various valve models and have two

prints of each design to test in case we broke or destroyed a model during testing. These valves

would replace the typical poppet-valve with horizontally sliding cylinders with varying inlet

shapes that would require less movement from the piezoelectric stack. The models would be

tested to see which had optimal airflow.

Unfortunately, we had tremendous delays due to issues with funding, which halted any

progress with acquiring a 3-D printer and eventually led to the decision not to purchase one at

all. Due to this, we were unable to create the new valve designs for testing, and agreed that it

would be best to keep the standard poppet found in almost every car engine. Some sort of

mechanical advantage was still required to greatly increase the displacement obtained from the

piezoelectric stack actuators. Various initial designs were taken into consideration, with the

team concluding on a wedge design which would actuate the valve up and down without the

use of any springs. From dynamic modeling calculations and a 3-D CAD model simulation, we

determined that friction between many of the surfaces would lead to force requirements

impossible to obtain with any piezoelectric actuator on the market. Therefore, we added a steel

roller bearing that could handle the large pressures from the piezoelectric crystals to decrease

the amount of area contributing to friction forces.

13.0 Preliminary Conclusion Based on where we stand at this halfway point in our senior project we have had to

reevaluate our end goals. Initially we were hoping to achieve installing a piezo valve actuator

and have one running by the end of spring 2015, but the 3D model still needs improvements

before we are able to actually start manufacturing it. Another issue that we have run into is

funding for the actual piezos to be used in the valve design. It was discovered that the piezo

required would cost around $10,000 to be created and we need two. This cost greatly exceeds

our budget for the senior project and thus this route is no longer possible. Instead we have

concluded to finalize the valve design and incorporate cams to actuate the design as a proof of

concept. As far as the piezo crystals go, we plan on purchasing the piezos and setting up a

display with some analysis to demonstrate the capabilities they are capable of achieving. With


these two goals met we can successfully conclude that by replacing the cams inside of the

wedge valve design with piezos the design should still function as intended.

14.0 Preliminary Recommendations In order to improve manufacturability, simplification of the valve assembly is critical in

the spring semester. With simpler parts, the cost of manufacturing at a local machine shop will

be drastically reduced, along with the production time. With limited time before project

presentations, meeting with representatives that Murray Tech knows of from a machine shop

in Stockton is essential. Researching cheaper piezoelectric crystals will also be required in order

to keep the team’s budget more reasonable. We concluded on a few companies that might

offer actuators at a reduced rate compared to that of the local manufacturer. These companies

include APC and Dynamic Structures and Materials (DSM). More importantly, the actuators that

the new companies sell are stock parts which could quickly be shipped upon payment. In order

to further reduce the price of these expensive devices, we plan on requesting the actuator on

loan so that we could complete tests and have it during our presentation for a physical model

but return it immediately following graduation.

15.0 Final Modeling, Simulation, Analysis and Testing Results

Figure Error! Use the Home tab to apply 0 to the text that you want to appear here..15.1: Test 1

Sig.Gen.Volt.(pk-pk) OutputVoltage DisplacementMin DisplacementMax DisplacementTotal Displacement

V V in. in. in. mm0.5 20 -0.0005 0.0015 0.002 0.05080.75 30 -0.003 0.0025 0.0055 0.13971.02 40.8 -0.005 0.0045 0.0095 0.2413

1.26 50.4 -0.007 0.006 0.013 0.33021.5 60 -0.004 0.015 0.019 0.48261.76 70.4 -0.006 0.018 0.024 0.6096

2 80 -0.003 0.028 0.031 0.7874

2.28 91.2 -0.005 0.031 0.036 0.91442.52 100.8 -0.007 0.0335 0.0405 1.02872.72 108.8 -0.001 0.045 0.046 1.1684

3 120 -0.003 0.047 0.05 1.273.25 130 -0.002 0.054 0.056 1.42243.45 138 -0.003 0.056 0.059 1.49863.78 151.2 0 0.064 0.064 1.62563.97 158.8 -0.002 0.065 0.067 1.70184.25 170 0 0.069 0.069 1.75264.46 178.4 -0.005 0.069 0.074 1.8796

Displacementvs.VoltageTest


Table 15.2: Test 2

Table 15.Error! Use the Home tab to apply 0 to the text that you want to appear here..2: Test 3

Sig.Gen.Volt.(pk-pk) OutputVoltage Frequency DisplacementMin DisplacementMax DisplacementTotal DisplacementV V Hz in. in. in. mm

4.4 176 0.1226 -0.01 0.066 0.076 1.9304

4.4 176 0.2447 -0.009 0.066 0.075 1.905

4.4 176 0.3124 -0.009 0.066 0.075 1.9054.4 176 0.4278 -0.009 0.066 0.075 1.9054.4 176 0.5152 -0.0085 0.066 0.0745 1.8923

4.4 176 0.6457 -0.008 0.066 0.074 1.87964.4 176 0.7794 -0.007 0.066 0.073 1.85424.36 174.4 0.8435 -0.007 0.0655 0.0725 1.8415

4.36 174.4 1.052 -0.006 0.0655 0.0715 1.81614.36 174.4 1.31 -0.006 0.0655 0.0715 1.81614.36 174.4 1.828 -0.006 0.0655 0.0715 1.81614.36 174.4 2.114 -0.006 0.0655 0.0715 1.8161

Displacementvs.FrequencyTest(NoLoadMass)

Sig.Gen.Volt.(pk-pk) OutputVoltage Frequency DisplacementMin DisplacementMax DisplacementTotal Displacement

V V Hz in. in. in. mm

4.36 174.4 0.505 0.003 0.055 0.052 1.3208

4.36 174.4 1.002 0.003 0.055 0.052 1.3208

4.36 174.4 1.493 0.003 0.055 0.052 1.32084.36 174.4 2.004 0.002 0.055 0.053 1.3462

4.36 174.4 2.272 0.001 0.054 0.053 1.3462

4.4 176 2.525 0.002 0.053 0.051 1.2954

4.4 176 2.947 0.003 0.053 0.05 1.274.4 176 3.167 0.003 0.053 0.05 1.27

4.4 176 3.527 0.004 0.052 0.048 1.2192

4.4 176 4.003 0.003 0.052 0.049 1.2446

Displacementvs.FrequencyTest(4.9kgLoadMass)


16.0 Discussion of the Final Results

Piezo Design

Figure.3: Displacement vs. Voltage

In the primary test of the FPA-2000E piezoelectric actuator, displacement as a function of the

peak-to-peak voltage from the signal generator was measured. This test proves proportionality between

actuator travel and the voltage applied to it. In different applications of piezoelectric actuators, this can

be taken advantage of for extremely precise and repetitive linear displacements.

In the secondary test, the piezoelectric actuator was unloaded while frequency was gradually

increased. At minimal cycles per second, the crystal was able to fully expand with the supplied current

under both the positive and negative output voltages. As frequency increased, the displacement

y = 0.0121x - 0.2123 R² = 0.9942

0

0.5

1

1.5

2

2.5

0 50 100 150 200

Dis

pla

cem

en

t (m

m)

Differential of Amplified Output Voltage (V)

1.8

1.82

1.84

1.86

1.88

1.9

1.92

1.94

0 0.5 1 1.5 2 2.5

Dis

pla

cem

en

t (m

m)

Frequency (Hz)


decreased and settled out to a constant amount. Having a constant displacement would be ideal for

precisely actuating a valve through rapid frequencies.

In the third test of the piezoelectric actuator, a 4.9-kilogram load was applied on the top of the

actuator to model the maximum expected force to overcome a measured 48-newton static friction load

in the cam-less assembly. The graph shows the how the displacement stays constant as the frequency

increases. This repeatability is ideal in a valve control application because it can be displaced at a desired

distance through all engine speeds. This will all us to independently actuate the valve and give the

correct air ratio needed for peak performance.

It is important to note that the maximum frequency attainable under a 4.9-kilogram load with

the VF-90 voltage follower/linear amplifier was approximately 3.2 hertz.

Valve Design

For our wedge valve design we were content to know that the overall design worked

seamlessly as far as turning the cams to actuate the valve. It was also noticed that relatively

little forces was required to turn the crank by hand to make the valve move up and down as

expected. Initially there were some issues putting the wedge valve actuator together due to our

inexperience with designing around tolerances. Many of the components were designed to fit

together perfectly without any room for error so many of the parts had to be sanded on certain

surfaces in order to construct it. Once the actuator was constructed and successfully rotated

with the cams we began to do some testing with the various wedge angles that were

manufactured. We decided to work our way down from the greatest angles to the lowest

angles just to avoid any gouging on the surfaces of the cams or binding that may occur. The 10

degree wedge worked perfectly with relatively no difficulty, the same results were observed

from the 7.5 and 5 degree wedges. The last wedge to test was the 3.5 degree angle, which is

1

1.05

1.1

1.15

1.2

1.25

1.3

1.35

1.4

1.45

1.5

1.55

1.6

0 1 2 3 4 5

Dis

pla

cem

en

t (m

m)

Frequency (Hz)


also our minimum expected angle to work. We installed the angle and to our pleasure again the

wedge valve actuator worked but slightly more force was required to actuate the valve by

hand, but it still did not require much.

With the angle test accomplished, we then moved on to testing the displacement

acquired from the 3.5 degree wedge. It was expected to acquire a theoretical 0.49 inch

displacement with a 3.5 degree angle. For some reason we were only achieving a displacement

of 0.353 inches with this angle. After completing some simple trig analysis we were able to

conclude that this may have been due to human error when using the dial indicator for valve

displacement measurements. It was calculated that with the dial indicator at an angle of 1.3

degrees, could throw off our displacement measurements by 0.137 inches. This is definitely a

possibility since our design critically relies on very small angles to acquire a greater valve

displacement.

It is desired to obtain the required force necessary to overcome static friction of the

valve assembly with negligible acceleration values. There were two experiments carried out to

obtain the desired values: torsion applied to the cam assembly and linear force applied to the

cam followers without the cam installed.

First, a measured torque was applied to the cam assembly. A measured weight of

1.9130 N (195g or 0.43 lbf) was applied to a .178m (7 inch) lever arm, producing a 0.0347 Nm

torque. In order to obtain the normal force the cams submit to the cam followers, torsional

force must be translated. Because a frictionless cam would apply zero force on the cam

followers, a frictional coefficient must be obtained in order to translate to a normal force. With

an estimated frictional coefficient of 0.01 between the cam surface and follower, an 1190.28 N

force is applied to the valve assembly with the applied torque on the cam. It is very possible

that the frictional efficiency is actually much worse which would increase the amount of force

associated with friction, but decrease the overall amount of force needed to actuate the cam

followers. This high force is associated with the large inefficiencies associated with the cam.

Because the cam assembly was only used to simulate the displacement of the piezos, a second

test must be done to isolate the forces required to actuate the valve assembly minus the cam

components. This second test will more closely follow the actual force required to overcome

friction when piezo crystals are installed in a future design phase.

The second means of obtaining the required force to overcome friction was carried out by

applying a linear force to the cam followers without the cam installed. The entire assembly was

placed on its side with the actuation direction of the valve in the horizontal direction. Weights

were slowly added to a single cam follower. At the first sign of actuation of the valve assembly,

this weight was recorded to be 48.069 N (4900g or 10.81 lbf). The vertical linear bearing is

specified by the manufacturer to have a worst case frictional coefficient of 0.015. The frictional


coefficient of a steel roller bearing applied to an aluminum surface is defined to be 0.001. The

static sliding friction between a well lubricated steel and aluminum surface is 0.01 (linear

horizontal slider bearings). With the applied mass of 4.9kg, a 0.4kg slider assembly, and a

0.04kg cam follower, 52.38 N is applied to the wedge assembly at the circular roller bearing.

The weight of the wedge/valve assembly is 56.87 N. A 3.2 N horizontal force is resisted at the

3.5 degree wedge surface. An approximate combined coefficient of friction of the entire system

is 0.05865. A numerical solution for the actual coefficient of rolling friction on the wedge

surface is 0.00101, as well as a 0.05541 coefficient of friction on the vertical bearing supporting

the wedge. The numerical solutions provide a means of estimating the bind angle of the

system, or the angle at which no amount of force will cause the assembly to actuate. During the

fall semester, it was calculated the estimated binding force would be 2.92 with an estimated

0.05 coefficient of friction between a well lubricated metal on metal surface and a rolling

coefficient of friction of 0.001. It was then agreed that a 3.5 degree wedge would satisfy the

amplification needs as well as actuate at a non-binding angle. With the frictional coefficient

obtained in this term, the actual estimated binding angle would be 3.23 degrees. In conclusion,

the results obtained were very similar to the estimations made before the physical construction

and experimentation of the project.

17.0 Conclusions and Recommendations about the Project

Piezo Design Although the maximum frequency obtained before reaching attenuation cannot be applied to

high-performance engines, the technology could be applied to slow speed diesel engines. With a

frequency of 4 hertz, or 480 RPM, the actuator was easily able to displace approximately 1.25

millimeters (nearly 0.050 in.) with the 90-milliamp voltage amplifier. In order to apply this to a high

performance engine, we would need to use an amplifier with a higher operating current in order to fully

displace the piezoelectric crystal at higher frequencies. This would be an easy part in the system to

upgrade during further design development.

To achieve better results, a DAQ should be used with a LabVIEW program to generate precise

voltages (-0.75 V to 3.75 V), and the DAQ could also be set up with a more precise displacement

measurement tool. This improved setup would guarantee maximum (-30 V to 150 V) output to the

actuator, and the electronic displacement device would measure the true displacement during high

performance testing.

Valve Design

Lastly, a dynamic force model was carried out on Microsoft Excel. Accounting for the force of

acceleration created by the moving masses, as well as the frictional forces from above, required

force over time was calculated for at 4 Hz or a 480 RPM operating 4-stroke engine. Although

this is a relatively low RPM, it was never expected that the piezo amplifier purchased for this


project would be able to run at much higher frequencies. It was proven that the piezo crystal

could successfully actuate and displace enough distance and force to overcome frictional forces

within the camless valve assembly as a whole. It is recommended that further tests are carried

out to increase the force outputted by the piezo using a higher quality electrical amplifier.


18.0 Appendices

18.1 Detailed Drawings

18.1.1 Overall Assembly Drawing

Final Assembly


18.1.2 Sub Assembly Drawings

Linear Bearing Fixture

Compression Block Component


Wedge Fixture

18.1.3 Detailed Drawings

Cam Axle


Cam

Compression Block Bottom and Top


Side Cam Housing

Slider Back Housing


Top and Bottom Housing


McMaster-Carr Parts

Bearing Rail

Part Number: 6382K750


Linear Bearing



Bolt

Part Number: 93070A105


Cap Screw



Key Stock



Cap Screw



Washer



C Clip



Cam Follower



Washer



Cap Screw



Ball Bearing



Spring Pin



Shaft Collar



Hank Crank



Cap Screw



18.1.4 Bill of Materials

Machined Parts


18.2 Computer Programs %FLEX Engine Design Work Dynamic Model of Wedge clear all close all clc RPM=5000 %Revolutions per minute (4 stroke assumpition) degreespersecond=RPM.*(1/60)*(360) %[deg/s], RPM*(1min/60s)*(360 deg crank/1revolution) time=.1 if RPM < 60 step=1/(RPM.*10) else step=1/(RPM) end t=0:step:time degreestraveled=degreespersecond*t deg=((degreestraveled./720)-floor(degreestraveled./720))*720 %find degrees in 0-720 deg xlift=camprofile(deg, time, step); for(i=1:time/step+1) if (deg(i) > 382.32) & (deg(i) < 609.84) x(i)=xlift(i) else x(i)=0 end end x=x/1000; %meters xin=x*3.28084*12 %inches PZlength=2 %[in] length of combined Piezos PZpercentstrain=0.005 % 1% or 0.01 @ 100% excitation, 0.5% or 0.005 @ 50% excitation PZstrain=PZlength.*PZpercentstrain.*(1/12)*(1/3.28084) %meters theta=2 % angle of amplification [degrees] amplength=PZstrain./(sind(theta)) r=amplength./PZlength %amplification ratio wallin=xin./r; g=9.81 %acc grav [m/s^2] m1=0.5*(4.448)*(1/g) %mass of wall [kg], eq to 0.5 lbf %m2=0.75*(1/4.448)*(1/g) %mass of valve [kg], eq to 0.25 lbf m2=77.0/1000 %[kg], 77grams = 0.169lbf; LS7 intake valve http://ls1tech.com/forums/generation-iv-internal-engine/881646-ls7-l92-valve-weight-ls7-springs.html


if t==0 mu=0.09 %static friction coefficient, metal on metal (lubricated) else mu=0.07 %kinetic friction coefficient, metal on metal (lubricated) end for i=(1:(time/step-1)) v(i+1)=(x(i+1)-x(i))./(step) a(i+1)=(v(i+1)-v(i))./(step) end for(i=1:(time/step-1)) if v(i)<0 sgn(i+1)=-1 else if v(i)>0 sgn(i+1)=1 else if v(i)==0 sgn(i+1)=0 end end end end FPZ=((m1+(m2./sind(theta))).*a)+mu.*m1.*g.*(sgn)./(mu.*cosd(theta).*r.*sgn+1); FPZlbf=FPZ./4.448; %converst force of PZ from Newtons to lbF figure(1) plot(t,xin,t,wallin) hold on xlabel('time (s)') ylabel('valve displacement (in)') grid on axis tight hold off t=linspace(0,step,length(FPZlbf)) figure(2) plot(t,FPZlbf) hold on xlabel('time (s)') ylabel('PZ force (lbf)') grid on axis tight hold off


figure(3) plot(deg, xin) hold on xlabel('crankshaft position (deg)') ylabel('valve displacement (in)') grid on axis tight hold off t=linspace(0,step,length(v)) figure(4) plot(t,v) hold on xlabel('time (s)') ylabel('velocity (m/s)') grid on axis tight hold off t=linspace(0,step,length(a)) figure(5) plot(t,a) hold on xlabel('time (s)') ylabel('acceleration (m/s^2)') grid on axis tight hold off


18.5 Supporting Background Information

This is a spreadsheet we created to compare different specs from different manufactures vehicles. It was especially

important to look at the vehicles BMEP (Break Mean Effective Pressure) to find out what types of pressures the inside of the cylinder

would be experiencing.

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Autodesk 4 cylinder engine model: Valve displacement referenced


18.6 Other Relevant Information

While searching for 3-D printers to buy before the funding issues came up, our team created this spreadsheet to help put a

value to the printers and choose the best printer for our project.


18.7 Cost Analysis

Flex Engine Team Cost Analysis

Company Description Items Price

DSM Piezo Amplifier 1 1000.00

DSM Piezo actuator 1 275.00

America Piezo Piezo cystals 2 217.40

Proto Lab Machined Parts 26 6909.33

Total 30 8401.73


18.8 Final Project Virtual Realizations

Figure Error! Use the Home tab to apply 0 to the text that you want to appear here..48.8.1: Final

Design

Figure 18.8.2: Linear Bearing Fixture


Figure 18.8.3: Top and Bottom Housing

Figure 18.8.4: Wall Compression Block

Figure 18.8.5: Compression Block


Figure 18.8.6: Side Wall Cam Holder (x2)

Figure 18.8.7: Cam Axle


Figure 18.8.8: Cam

Figure 18.8.9: Wedge Fixture and Poppet Valve


Figure 18.8.10: Push Pins (x2)

Figure 18.8.11: Hand Crank


18.9: Final Project Detailed Photos

the flex engine - scholarworks

Documents