Radial Compressor

Example of a Slider CrankBy,

Yee Meng Yap, Corey Shipman, and Nicole Cannon

Abstract

Our mechanism is comprised of a series of three redundant slider-crank assemblies. The function of this mechanism is to force a gas into a tank in which pressure can be built up and stored for later use. It is able to perform this function by having a motor driven shaft which controls the linear stroke motion and drives the three pistons. This causes the gas to be pulled into the tank. The pressurized gas can then be utilized as a means of energy to perform work such as powering an air tool or filling a tire. From our evaluation of the radial compressor, the results were that our numbers correspond with the numbers generated by the computer model. Our results also support the function of the mechanism.

Introduction

The radial compressor in question will be used to perform duties of a typical air compressor, such as: Powering pneumatic systems on an aircraft Operation of pneumatic tooling Tire inflation Pressurized paint sprayers Tank systems Beverage Dispensing

Picture of a Compressor

Drawing of Radial Compressor

Analytical DrawingWith Instant Centers

Analysis

Degrees of Freedom: Links=8 Type 1 Joints=10 Type 2 Joints=0 Ground=1 m=3(L1-1)-2(L2)= 1 Degree of Freedom

Grashof? L = 6.08 S = 0 P = 6 (Changes) Q = 1 S+L<P+Q Yes, Grashof

AnalysisPosition

AnalysisPosition

AnalysisVelocity

AnalysisVelocity

AnalysisAcceleration

AnalysisAcceleration

Results (Computer Model) Velocity of Piston

Results (Computer Model)Acceleration of Piston

Results (Calculated)Velocity of Piston

Velocity of Piston

-150

-100

-50

0

50

100

150

0 1 2 3 4 5 6 7

Theta 2 (Radians)

Vel

oci

ty (

in/s

ec)

Results (Calculated)Acceleration of Piston

Acceleration of Piston

-20000

-15000

-10000

-5000

0

5000

10000

15000

0 1 2 3 4 5 6 7

Theta 2 (Radians)

Acc

eler

atio

n (

in/s

ec^

2)

Results

We have found that our rotary compressor has one degree of freedom controlled by our input angle of theta two.

Because we have found that it is a Grashof mechanism it will not seize. This has also been proven with our working model.

The velocity of the piston graph follows a negative sine function while the acceleration of the piston graph properly shows a negative cosine function, proving differentiation.

Results

After carefully examining our charted data we found that between the working model and calculated values we have less than one percent error. We found this by comparing our maximum piston velocities from both charts: Working Model: 127 in/sec Theoretical: 126 in/sec

Critical Parameters

The critical parameters consist of: Stroke length Frictionless Velocity of the input crank Cylinder and head diameter Size of intake and exhaust valves Material composition of the compressorAll of these factors contribute to the proper

functioning of the compressor.

Animation

Animation of Slider

Our working model animation is included on the project CD and is saved as “Model_1”.

Sorry for the inconvenience, we could not get our working model to work with power point.

Conclusion

Once again our mechanism is successful in completing a full rotation, it is controlled by one degree of freedom, and has a maximum piston velocity of approximately 127 in/sec. Also, our maximum piston acceleration is approximately 13,194 in/sec^2.

Our sources of error could be caused by conversions, significant figures, and other areas of human error. This could be improved by minimizing conversions such as carrying through one system of measurement, using more significant figures, and performing extended cross checking of calculations.

We could improve our mechanism by following industry standards of a shorter stroke and shorter piston length. This will allow us to increase speed and efficiency by decreasing friction.

Resources

Norton, R.L., Design of Machinery, Third Edition, McGraw-Hill, New York, 2004.