Experimental and Theoretical Analysis of the Drag Torque in Wet Clutches

Pan, Haojie; Zhou, Xiaojun

doi:10.32604/fdmp.2019.07808

Cited by 5 publications

(4 citation statements)

References 14 publications

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“…The proposed concept of analysis of one pair of discs appears to be easier in implementation, compared to the multidisc clutch configuration reported elsewhere [5,8,9]. In multidisc conception, the layout of oil flow rates and slippage between specific disc pairs can be noticeably different which makes the research more complex.…”

Section: Resultsmentioning

confidence: 98%

“…Then, between 6000 and 6500 rpm, it achieves the maximum and drops about 10% at the highest speed of 7000 rpm. Pan and Zhou [5] explain this run by the change of oil flow mode between the discs: from one-phase at low speed to two-phase with gas bubbles at high speed. In Figure 4, the results for the same gap between the discs and oil temperature of 80 • C but various oil flow rates are presented.…”

Section: Resultsmentioning

confidence: 99%

“…Pan and Zhou [5], based on their research, have made the following conclusion: the rotating discs of the disengaged wet clutch create drag torque which is changing with relative rotational speed. Three stages from the operating range of such a clutch can be distinguished: (a) low speed, the clearance between the discs is fully filled with singlephase fluid, drag torque increases linearly with increasing the relative speed; (b) medium speed, the fluid film becomes discontinuous, the clearance between the discs is filled with two-phase fluid, drag torque decreases with increasing speed; (c) high speed, the rotating discs are getting closer to each other due to the negative value of fluid pressure in the gap, drag torque increases again with increasing speed.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Experimental Study of Drag Torque between Wet Clutch Discs

et al. 2022

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The development of automatic gearbox control systems contributes to their increasing popularity. By raising the number of gears and sophisticated algorithms, the reduction of fuel consumption is feasible regarding traditional manual transmissions. The continuously variable transmissions (CVT) are also growing their share of the market. Wet clutches are employed in all types of automatic transmissions, but because of oil viscosity, when such a type of clutch is disengaged, the drag torque phenomenon occurs. This deteriorates the global efficiency of the transmission system. To recognize the nature of this drag torque and how it is influenced by the main parameters (distance between plates, value of oil flow rate lubricating clutch, oil temperature, rotational speed between plates), a new test stand has been designed and assembled. The value of rotational speed has been studied up to 7000 rpm which is novel in literature. Due to strongly nonlinear dependences, the achieved results can contribute to designing more efficient clutch systems due to the strongly nonlinear nature of observed phenomena.

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Section: Resultsmentioning

confidence: 98%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Experimental Study of Drag Torque between Wet Clutch Discs

et al. 2022

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“…For the experimental determination of the steady drag torque, the stepwise adjustment of the differential speed has proven to be reliable [4,6,11,17,58] and is therefore used in the presented methodology.…”

Section: Test Proceduresmentioning

confidence: 99%

A methodology for data-driven modeling and prediction of the drag losses of wet clutches

Pointner-Gabriel

Voelkel

Pflaum

et al. 2023

Forsch Ingenieurwes

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In wet clutches, load-independent drag losses occur in the disengaged state and under differential speed due to fluid shearing. The drag torque of a wet clutch can be determined accurately and reliably by means of costly and time-consuming measurements. As an alternative, the drag losses can already be precisely calculated in the early development phase using computing-intensive CFD models. In contrast, simple analytical calculation models allow a rough but non-time-consuming estimation. Therefore, the aim of this study was to develop a methodology that can be used to build a data-driven model for the prediction of the drag losses of wet clutches with low computational effort and, at the same time, sufficient accuracy under consideration of a high number of influencing parameters. For building the model, we use supervised machine learning algorithms. The methodology covers all relevant steps, from data generation to the validated prediction model as well as its usage. The methodology comprises six main steps. In Step 1, the data is generated on a suitable test rig. In Step 2, characteristic values of each measurement are evaluated to quantify the drag loss behavior. The characteristic values serve as target values to train the model. In Step 3, the structure and quality of the dataset are analyzed and, subsequently, the model input parameters are defined. In Step 4, the relationships between the investigated influencing parameters (model input) and the characteristic values (model output) are determined. Symbolic regression and Gaussian process regression have both been proven to be suitable for this task. Lastly, the model is used in Step 5 to predict the characteristic values. Based on the predictions, the drag torque can be predicted as a function of differential speed in Step 6, using an approximation function. The model allows a user-oriented prediction of the drag torque even for a high number of parameters with low computational effort and sufficient accuracy at the same time.

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