Hydrodynamic Lubricant Film Separation During Codirectional and Counter-Directional Rotations of Disengaged Wet Clutch Packs

Morris, Nicholas J.; Patel, Rishi; Rahnejat, Homer

doi:10.1115/1.4044443

Cited by 4 publications

(4 citation statements)

References 27 publications

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“…Dowson [7] provides an equation (Eq.8) for the radial volumetric flow rate through the fluid film. When the effects of cavitation [14] and separation [15] are ignored it can be assumed a coherent fluid film extends between the inner and outer radius. This assumption is most applicable during the axial approach of the discs.…”

Section: Hydrodynamicsmentioning

confidence: 99%

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A Time Efficient Thermal and Hydrodynamic Model for Multi Disc Wet Clutches

Morris¹,

Morris²,

Leighton³

2022

SAE Technical Paper Series

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Wet Clutches are used in automotive powertrains to enable compact designs and efficient gear shifting. During the slip phase of engagement, significant flash temperatures arise at the friction disc to separator interface because of dissipative frictional losses. An important aspect of the design process is to ensure the interface temperature does not exceed the material temperature threshold at which accelerated wear behavior and/or thermal degradation occurs. During the early stages of a design process, it is advantageous to evaluate numerous system and component design iterations exposed to plethora of possible drive cycles. A simulation tool is needed which can determine the critical operational conditions the system must survive for performance and durability to be assured. This paper describes a time-efficient multiphysics model developed to predict clutch disc temperatures with a runtime in the order of minutes. It consists of a simplified 1D numerical model of heat conduction and storage within the clutch pack. A novel analytical interfacial model considers the effects of hydrodynamics and frictional heat generation at the sliding interface, including radial groove and squeeze flows, to calculate the heat transfer between the clutch surfaces and the fluid. The model has been validated against experiments. The assumptions made are demonstrated to be prudent as the presented model is shown to closely predict the disc and interface temperatures. Finally, the model is exercised to examine the effect of varying clutch plate number on temperature during an urban drive cycle.

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Section: Hydrodynamicsmentioning

confidence: 99%

“…The radial velocity components on the two surfaces can be described as: z = 0, u = 0 & z = h, u = 0. For the condition when both discs are rotating additional terms can be found as described by Morris et al [15].…”

Section: Hydrodynamicsmentioning

confidence: 99%

A Time Efficient Thermal and Hydrodynamic Model for Multi Disc Wet Clutches

Morris¹,

Morris²,

Leighton³

2022

SAE Technical Paper Series

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show abstract

“…and (20) the equivalent clearance, h eq can be used to calculate the drag torque of grooved wet clutch in disengagement phase applying equation (14).…”

Section: Average Drag Torque Relationmentioning

confidence: 99%

“…An analytical model and implicit solution have been introduced to determine radial location of lubricant film rupture and to calculate the drag losses for various disengaged wet clutch operating conditions 20 . Groetsch et al 21 presented the results of drag losses calculation under open stage of multi-plate clutches, using Singhal cavitation model and the volume of fluid method taking into account the effects of operating conditions, groove design, speed ratio and feeding oil temperature.…”

Section: Introductionmentioning

confidence: 99%

Analytical simulation of influential parameters affecting grooved wet clutches performance underdisengagement condition

Nasiri

Delprete

Brusa

et al. 2021

Proceedings of the Institution of Mechanical Engineers, Part J:

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Innovating new approaches and effective methods to improve the efficiency of mechanical systems in terms of energy losses and environmental effects serve as an attractive domain for researchers and industries. Wet clutches are widely used in power transmission systems in automotive and other tribological mechanisms. The wet clutch has two functional modes; under the engaged state, in which two disks come into contact to each other, and under disengagement the plates are located at a very short distance from each other, and oil flows between them. In disengaged state, the differential speed of driving and driven units causes oil shearing within the clearance which leads to transmission of certain amount of drag torque from the driving to the output shaft. This transferred drag torque is distinguished as power loss in form of heat. The governing physical relation based on continuity equation and Navier–Stokes equations reveals that in a certain rotational velocity, the pressure gradient at the outer radius of the clutch becomes null, and, in this circumstance, aeration occurs that is known as critical rotation speed. Experimental findings provide evidence that geometry manipulation and considering grooves over the frictional disk, reduces the critical rotational speed. But there is a shortage of physical analytical relations to predict the pressure gradient in grooved wet clutches. Therefore, this article is aimed to introduce analytical model to evaluate grooved wet clutches performance in terms of drag torque and critical rotational speed under single-phase flow condition.

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Study on drag torque characteristics of wet multiplate clutch under high-speed operating condition

Li,

Ma,

Wang

et al. 2023

Proceedings of the Institution of Mechanical Engineers, Part D:

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In order to study the characteristics of the drag torque of wet multi-plate clutches at high speed, a mathematic model of the drag torque considering oil-gas two-phase flow was established. Based on the VOF two-phase flow model, the oil-film fluid simulation of the flow field was finished, and the distribution law of the volume fraction of the oil-gas phase changing with the speed was analyzed. The analysis results of the model and simulation show that under high speed condition, the oil and gas two-phase flow occupies most of the area in the flow field gap, and leads to the rebound trend of the high speed drag torque. Finally, the variation of the drag torque under different working conditions is studied through experiments, and the influence of lubricant temperature, flow rate, friction plate speed and clearance of friction pairs on the drag torque is analyzed. The improved drag torque model was compared with the experimental results. When the speed is greater than 2000 r/min, the average relative error of the drag torque is less than 15%, which significantly improves the accuracy of the drag torque prediction model, and lays a theoretical foundation for further research on the structure design and optimization of wet multi-plate clutch.

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Hydrodynamic Lubricant Film Separation During Codirectional and Counter-Directional Rotations of Disengaged Wet Clutch Packs

Cited by 4 publications

References 27 publications

A Time Efficient Thermal and Hydrodynamic Model for Multi Disc Wet Clutches

A Time Efficient Thermal and Hydrodynamic Model for Multi Disc Wet Clutches

Analytical simulation of influential parameters affecting grooved wet clutches performance underdisengagement condition

Study on drag torque characteristics of wet multiplate clutch under high-speed operating condition

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