Modeling and Parametric Study of Torque in Open Clutch Plates

[+] Author and Article Information
Chinar R. Aphale

Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48105caphale@umich.edu

Jinhyun Cho

Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48105jinhyunc@umich.edu

William W. Schultz

Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48105schultz@umich.edu

Steven L. Ceccio

Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48105ceccio@umich.edu

Takao Yoshioka

 Dynax Corporation, Hokkaido, Japanyoshioka-t@mail.dxj.co.jp

Henry Hiraki

 Dynax Corporation, Hokkaido, Japanhiraki-h@mail.dxj.co.jp

J. Tribol 128(2), 422-430 (Sep 19, 2005) (9 pages) doi:10.1115/1.2162553 History: Received February 25, 2004; Revised September 19, 2005

The relative motion of the friction and separator plates in wet clutches during the disengaged mode causes viscous shear stresses in the fluid passing through the 100microns gap. This results in a drag torque on both the disks that wastes energy and decreases fuel economy. The objective of the study is to develop an accurate mathematical model for the above problem with verification using FLUENT and experiments. Initially we two consider flat disks. The mathematical model calculates the drag torque on the disks and the 2D axisymmetric solver verifies the solution. The surface pressure distribution on the plates is also verified. Then, 3D models of one grooved and one flat disk are tested using CFD, experiments and an approximate 3D mathematical model. The number of grooves, depth of groove and clearance between the disks are studied to understand their effect on the torque. The study determines the pressure field that eventually affects aeration incipience (not studied here). The results of the model, computations and experiments corroborate well in the single-phase regime.

Copyright © 2006 by American Society of Mechanical Engineers
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Figure 1

Schematic diagram of the apparatus, showing oil entering axially from the center of rotating plate and exiting radially at r=Ro due to centrifugal action. The origin of the coordinate system is on the symmetry axis halfway between the two plates. The relevant dimensions are shown.

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Figure 2

Pressure distribution vs radial coordinate. The case where pressures at both the inner and outer radii are zero corresponds to the natural flow rate of the system. Pressure is normalized with ρνs2 and radius with Rm.

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Figure 3

Axial derivative of pressure at the inlet for different boundary conditions. The natural boundary condition shows that ∂p∕∂z≈0, in agreement with the asymptotics. Derivative of pressure is normalized with ρνs2∕h and axial coordinate by h.

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Figure 4

Radial velocity versus axial coordinate. Radial velocity normalized with ω2Rmh2ρ∕μ and axial coordinates by h.

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Figure 5

Axial velocity versus axial coordinate. These are normalized by ω2h3ρ∕μ and h, respectively.

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Figure 6

Block diagram of overall system configuration. The circulation pump helps to maintain a steady oil temperature throughout. The syringe pump is used whenever a fixed flow rate of oil is to be prescribed. St. P: Stationary plate, RP: Rotating Plate, TA: Torque arm, T: Thermocouple, M: Motor, PG: Pressure gauge, SG: Strain gauge, DB: Driving belt, SP; Syringe pump, OS: Oil sump, CP: Circulation pump.

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Figure 7

Photograph of the assembly and the relevant components. The view is taken from the rotating plate side.

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Figure 8

Photograph of the circulation system. The oil sump is heated if required. The circulation pump maintains the oil temperature while the motor rotates one plate.

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Figure 9

Repeatability study experiments for 80 grooves, 100micron clearance

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Figure 10

Pressure contour for the 40 grooved plate and the modeled geometry. The top plate moves in anticlockwise direction. Pressure is high near the downstream notch.

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Figure 11

Fluid path lines as viewed from the top. The fluid in the notch goes radially outward while the fluid in between the two plates moves predominantly in the tangential direction.

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Figure 12

Fluid path lines as seen from the inner radius. The spiraling motion of the fluid can be seen in the notch. The fluid moves in almost horizontal planes between the two disks.

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Figure 13

Tangential component of shear stress. The rotating plate has a very large value of shear stress throughout. The grooved plate shows less tangential shear stress in the region of the notch due to predominant radial motion of fluid.

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Figure 14

Pressure comparison of FLUENT with model for three different flow rates. Pressure is normalized with ρνs2 and radius with Rm. The solid line is FLUENT , dotted line is the exact model and dashed line is the approximate model.

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Figure 15

Radial velocity comparison of FLUENT with models. The three curves correspond to FLUENT , exact and approximate models lie almost on top of each other.

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Figure 16

Shear stress versus radius. FLUENT predicts shear stress on the stationary and rotating wall to be slightly different to give increasing angular acceleration to the fluid.

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Figure 17

Drag torque versus rotation rate at 100microns clearance. The comparisons show that the simulation and model are in close agreement with each other.

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Figure 18

Drag torque versus rotation rate at 200microns clearance. The discrepancy between experiments and simulation is much lower than that of Fig. 1 because sensitivity of error in setting the clearance is less at higher separations.

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Figure 19

Drag torque versus rotation rate for the 40 grooves per plate. The 3D single-phase simulation show excellent agreement with the experiments.

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Figure 20

Drag torque versus clearance for the 80 grooves plate. On average, the 80 groove plate shows less torque than 40 groove plate. The approximate model is valid only in the single-phase region.

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Figure 21

Drag torque versus the number of grooves for the 200microns clearance




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