Effect of Facing Groove Design on Drag Torque of Automatic Transmission Wet Clutches

Asai, Kazunari; Ito, Takanobu

doi:10.4271/2018-01-0400

Cited by 8 publications

(3 citation statements)

References 1 publication

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“…Basically, existing models are either based on analytical or numerical calculation methods. The numerical CFD simulation represents a modern tool to calculate the drag torque and has therefore been used in various research studies [9,11,20,[27][28][29][30][31][32][33]. CFD simulations can be performed in the early development phase, do not require prototype parts or even series parts, and enable targeted optimization of the clutch design and the operating parameters.…”

Section: Calculation Methodsmentioning

confidence: 99%

“…In these experimental and theoretical studies, various parameters influencing the drag torque were identified. The main influencing parameters are the plate size, number of gaps, oil viscosity, feeding flow rate in the case of injection lubrication, oil level in the case of dip lubrication, clearance, groove pattern, differential speed, and operating mode [4][5][6][13][14][15][16][17][18][19][20]. However, the design of the carriers also has a crucial influence on the drag losses [13].…”

Section: Drag Loss Behaviormentioning

confidence: 99%

“…For drag torque measurements, the SAE No. 2 component test rig [49] was already applied in various investigations [3,5,14,20,39,50]. Further investigations applied test rigs with a similar set-up and function principle [6,[51][52][53].…”

Section: Step 1: Data Generationmentioning

confidence: 99%

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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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Section: Calculation Methodsmentioning

confidence: 99%

Section: Drag Loss Behaviormentioning

confidence: 99%

See 1 more Smart Citation

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

Pointner-Gabriel

Voelkel

Pflaum

et al. 2023

Forsch Ingenieurwes

View full text Add to dashboard Cite

show abstract

Research on high-speed drag torque characteristics of wet clutches based on mechanism and data-driven approach

Zhang,

Zhou,

Zhang

et al. 2024

Nonlinear Dyn

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Experimental analysis of oil flow and drag torque generation in disengaged wet clutches

Pointner-Gabriel,

Schermer,

Schneider

et al. 2023

Sci Rep

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Fundamental knowledge of the oil flow in a disengaged wet clutch is essential for optimizing the cooling performance and the drag losses. However, no fundamental information on the oil flow and drag torque generation is available for dip-lubricated wet clutches. Therefore, the oil flow and drag torque generation in the sub-millimeter gap of a dip-lubricated wet clutch was experimentally investigated for three practically relevant oil levels. To enable optical access to the gap, transparent components were used. Further, a high-speed camera was used to capture the oil flow in the gap and grooving. Independent of the set oil level, the gap is oil-filled at low differential speeds, resulting in a single-phase flow. The drag torque increases approximately linearly with increasing differential speed due to the fluid shearing. In certain regions of the waffle grooving, air bubbles form locally. The air bubbles preferably occur in the grooves oriented in the radial direction, while the grooves oriented in the peripheral direction are filled with oil. Above a certain differential speed, the oil is continuously displaced from the gap, starting from the inside, due to the increasing centrifugal force. Consequently, the drag torque increases in a degressive manner until a maximum value is finally reached. The ongoing displacement of oil from the gap eventually results in a decrease in the drag torque. A steady drag torque is generated only when the oil is almost entirely displaced from the gap. Since the oil displacement from the gap already commences at a low differential speed, the cooling performance is limited for dip-lubricated wet clutches. The continuous displacement of oil from the gap can be held up, among other things, by increasing the oil level.

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Effect of Facing Groove Design on Drag Torque of Automatic Transmission Wet Clutches

Cited by 8 publications

References 1 publication

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

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

Research on high-speed drag torque characteristics of wet clutches based on mechanism and data-driven approach

Experimental analysis of oil flow and drag torque generation in disengaged wet clutches

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