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Research Papers

Modeling and Design of Air Vane Motors for Minimal Torque Ripples

[+] Author and Article Information
Cheng-Wei Cheng

Department of Mechanical Engineering,  National Cheng Kung University,No. 1, University Road, Tainan City 701, Taiwan, R.O.C.hm1795@gmail.com

Chao-Chieh Lan1

Department of Mechanical Engineering,  National Cheng Kung University,No. 1, University Road, Tainan City 701, Taiwan, R.O.C.cclan@mail.ncku.edu.tw

Chun-Yi Tseng

Department of Mechanical Engineering,  National Cheng Kung University,No. 1, University Road, Tainan City 701, Taiwan, R.O.C.chunyi.tseng@gmail.com

1

Corresponding author.

J. Mech. Des 134(5), 051003 (Apr 12, 2012) (10 pages) doi:10.1115/1.4006437 History: Received February 11, 2011; Revised March 05, 2012; Published April 11, 2012; Online April 12, 2012

This paper presents the analysis and design of a novel air vane motor. Air motors have a very high specific power. They require compressed air rather than electricity to produce motion; thus, they avoid sparks and can be used in demanding environments. Similar to other types of rotary machines, air vane motors exhibit torque fluctuations. The varying torque curve is a result of unmatched torques generated by the vanes in one revolution. Accompanying the torque fluctuations are dynamic speed ripples that produce undesirable vibration on the load side. Rather than using auxiliary flywheels or dampers to smoothen the fluctuation, we propose a new motor with noncircular stator profile so as to increase the flexibility of balancing vane torques. Through numerical optimization of the parametric noncircular profile, a nearly constant torque curve can be achieved. Experiments validate that the speed ripples are greatly suppressed without compromising performance, when compared with traditional air vane motors that employ circular stator profiles. We expect that the noncircular stator profile design can be applied to air vane motors of various sizes to minimize torque and speed ripples.

Copyright © 2012 by American Society of Mechanical Engineers
Topics: Torque , Engines , Design , Stators , Motors
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References

Figures

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Figure 12

Torque curve (θin  = −100 deg, θout  = 45 deg)

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Figure 13

Vane length (θin  = −100 deg, θout  = 45 deg)

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Figure 14

Torque curve of Case II (θin  = −100 deg, θout  = 45 deg)

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Figure 15

Stator profile of Case II (θin  = −100 deg, θout  = 45 deg)

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Figure 16

Vane length (θin  = −100 deg, θout  = 80 deg)

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Figure 17

Torque curve of Case V (θin  = −100 deg, θout  = 80 deg)

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Figure 18

Stator profile of Case V (θin  = −100 deg, θout  = 80 deg)

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Figure 19

Disassembled view of CV2

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Figure 20

Noncircular stator prototypes

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Figure 21

Experiment setup

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Figure 22

High-frequency and low-frequency harmonics

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Figure 23

Low speed response of NV2 (P0  = 239.22 kPa)

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Figure 24

High speed response of NV2 (P0  = 239.22 kPa)

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Figure 25

Low speed response of ANV2 (P0  = 239.22 kPa)

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Figure 26

High speed response of ANV2 (P0  = 239.22 kPa)

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Figure 27

Clearance-induced air leakage

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Figure 2

Air flow of a vane motor

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Figure 1

Schematic of an air vane motor

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Figure 11

(a) Asymmetric stator diagram and (b) stator profile parameterization

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Figure 10

Torque curve (θin  = −70 deg)

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Figure 9

Vane length (θin  = −70 deg)

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Figure 8

Noncircular stator profile of NV2 (θin  = −70 deg)

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Figure 7

Effects of inertia and damping on the speed ripple amplitude

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Figure 6

(a) Speed response of a four-vane motor and (b) speed response of a six-vane motor (7 Nm load, θin  = − 95 deg)

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Figure 5

Effect of inlet angle on the ideal efficiency and expansion ratio

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Figure 4

Effect of inlet angle and rotor size on torque fluctuation

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Figure 3

(a) Torque curves of a four-vane motor and (b) torque curves of a six-vane motor (θin  = −95 deg)

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