Method for evaluating heat dissipation capacity of wet friction plate oil groove

Abstract

The application discloses a kind of wet friction plate oil tank heat dissipation capacity evaluation method, the method is: step 1, determine the oil tank simulation scheme of m kinds of friction plate;Step 2, in the flow field analysis software, respectively build the friction plate oil tank flow field analysis model corresponding to m kinds of oil tank simulation scheme;Step 3, by changing the heat dissipation rotation speed, cooling flow, obtain the heat dissipation power and oil film shear torque of the oil tank inner surface of the friction plate surface in n kinds of typical heat dissipation rotation speed, p kind of typical cooling flow in m kinds of oil tank simulation scheme, and calculate the heat dissipation coefficient of the friction plate oil tank in the i kind of oil tank simulation scheme;Step 4, compare the oil tank heat dissipation coefficient calculated from m kinds of oil tank simulation scheme, the greatest numerical value of oil tank heat dissipation coefficient is the oil tank simulation scheme with optimal comprehensive heat dissipation performance;The application can meet the design requirement of the fine design of friction plate heat dissipation.

Description

Technical Field

[0001] This invention belongs to the field of structural design technology, specifically relating to a method for evaluating the heat dissipation capacity of a wet friction plate oil groove. Background Technology

[0002] Friction plates are widely used in vehicle transmission systems, as well as in wet brakes and wet clutches, to achieve functions such as gear shifting, torque transmission, and braking. During operation, the friction plates generate a large amount of heat through sliding friction with their mating plates. Excessive heat causes a significant increase in the surface temperature of the friction plates and mating plates, potentially leading to problems such as ablation, adhesion, and warping, severely affecting their performance and even causing malfunctions. To reduce the temperature of the friction plates, coolant is typically used to cool them. The cooling effect is related to the coolant flow rate, quality, and velocity. To further improve the cooling effect, oil grooves are often created on the surface of the friction plates. These grooves increase the heat exchange area of ​​the coolant and also significantly affect the flow state of the coolant, thereby altering the heat dissipation effect of the friction plates.

[0003] Common oil groove types include spiral grooves, radial grooves, waffle grooves, double circular arc grooves, wedge grooves, and circumferential grooves. Various oil grooves can be combined to obtain different heat dissipation effects.

[0004] How to quickly select the oil groove solution with the best heat dissipation capacity from many oil groove types based on the application conditions of the friction plate has long been a problem that has troubled friction plate designers and friction plate manufacturers.

[0005] Current methods for designing friction plate oil grooves mainly include empirical design, experimental comparison, and simulation comparison. Empirical design involves using existing design schemes with slight modifications to create new oil groove schemes, as shown in the attached figure. Figure 1 As shown in the attached diagram; the experimental comparison method involves manufacturing friction plates with different oil groove shapes, comparing their heat dissipation under the same working conditions on a test bench, and evaluating the superiority or inferiority of the heat dissipation capabilities of various oil grooves based on the highest temperature or heat resistance performance of the friction plates. Figure 2 As shown in the attached figure; simulation analysis involves constructing flow field analysis models for oil tanks of different forms, and evaluating the heat dissipation capacity of the oil tank based on the convective heat transfer coefficient of the surface under given working conditions obtained from the simulation analysis. Figure 3 As shown.

[0006] However, empirical design methods for oil tanks are not accurate enough, and sometimes blindly following existing designs can lead to unintended consequences, with heat dissipation effects far below expectations. Experimental comparison methods typically involve fabricating test specimens for comparative testing and optimization, requiring significant upfront investment and lengthy processing and testing cycles, thus hindering the improvement of oil tank design technology. Simulation analysis is a newly emerging method for calculating oil tank heat dissipation in recent years. Based on flow field simulation analysis, it analyzes the heat dissipation of different oil tank designs and compares the heat dissipation effects based on the convective heat transfer coefficient. Simulation calculation significantly reduces the design cycle and economic investment of oil tanks, showing good prospects for widespread application. However, since friction plate oil tanks affect heat dissipation while also causing idling oil churning losses during friction plate idling, it is not advisable to unilaterally pursue the highest possible surface heat dissipation power of the oil tank; idling oil churning losses should also be compared. Furthermore, the quality of an oil tank should be evaluated based on its operating conditions and requirements. Oil tank design schemes may exhibit different trends under different rotational speeds and flow rates; good heat dissipation under condition A may result in poor heat dissipation under condition B. Therefore, comparing different schemes based solely on simulation results such as convective heat transfer coefficients without considering the operating conditions and the oil churning loss in the oil tank is somewhat one-sided. There is an urgent need to develop a comprehensive, effective, and feasible evaluation method to fully evaluate and screen friction plate oil tank design schemes. Summary of the Invention

[0007] In view of this, and in view of the shortcomings of existing methods for evaluating the heat dissipation capacity of friction plate oil grooves, which are detached from specific usage requirements and have a one-sided evaluation, this invention provides a wet friction plate oil groove heat dissipation capacity evaluation method that can meet the refined design requirements of friction plate heat dissipation design.

[0008] This invention is achieved through the following technical solution:

[0009] A method for evaluating the heat dissipation capacity of a wet friction plate oil groove, the specific steps of which are as follows:

[0010] Step 1: Determine the oil groove simulation scheme for m types of friction plates. The oil groove simulation scheme for each type of friction plate can perform calculations for n typical heat dissipation speeds and p typical cooling flow rates under operating conditions.

[0011] Step 2: Construct flow field analysis models of the friction plate oil grooves corresponding to the m oil groove simulation schemes in the flow field analysis software;

[0012] Step 3: By changing the heat dissipation speed and cooling flow rate, obtain the heat dissipation power and oil film shear torque of the friction plate surface containing the inner surface of the oil groove at n typical heat dissipation speeds and p typical cooling flow rates in m oil groove simulation schemes.

[0013] The heat dissipation coefficient K of the friction plate oil groove in the i-th oil groove simulation scheme is calculated based on the heat dissipation power and oil film shear torque. Qi, i = 1, 2, ..., m;

[0014] Step 4: Compare the heat dissipation coefficients of the oil tanks calculated by the m oil tank simulation schemes. The oil tank simulation scheme with the largest heat dissipation coefficient is the one with the best overall heat dissipation performance.

[0015] Step 5, based on the known heat dissipation energy value Q required by the friction plate and the corresponding heat dissipation time t, according to... The ratio is used to evaluate whether the heat dissipation capacity of the oil tank in each simulation scheme meets the heat dissipation requirements;

[0016] like It is assumed that the friction plate meets the heat dissipation requirements using the i-th oil groove simulation scheme. It is then concluded that the i-th oil groove simulation scheme for the friction plate does not meet the heat dissipation requirements.

[0017] Furthermore, in step 1, the specific process for determining the oil groove simulation scheme for the m types of friction plates is as follows:

[0018] Step 1-1: Determine the operating conditions of the friction plate, including n typical heat dissipation speeds and p typical cooling flow rates. At the same time, determine the speed weighting coefficient for each typical heat dissipation speed and the flow weighting coefficient for each typical cooling flow rate.

[0019] Steps 1-2: Based on experience, preliminary simulation schemes for oil grooves of friction plates are determined by adjusting the groove type, groove cross-sectional dimension parameters, and oil groove distribution dimension parameters of the oil grooves. Then, three-dimensional modeling is completed based on the groove type, groove cross-sectional dimension parameters, and oil groove distribution dimension parameters of the friction plate oil grooves for each simulation scheme.

[0020] Furthermore, in step 2, after constructing the friction plate oil groove flow field analysis model corresponding to the m oil groove simulation schemes in the flow field analysis software, the flow domain boundary is set for each friction plate oil groove flow field analysis model. The flow domain boundary includes the heat dissipation speed and cooling flow rate.

[0021] Furthermore, in step 3, under the condition of a fixed cooling flow rate, when only the heat dissipation speed is changed, the heat dissipation coefficient K of the friction plate oil groove in the i-th oil groove simulation scheme is calculated. Qi The specific formula is as follows:

[0022]

[0023] Among them, K Qi Let K be the heat dissipation coefficient of the oil tank structure in the i-th simulation scheme, where i = 1, 2, ..., m; ωj Let be the speed weighting coefficient for the j-th typical heat dissipation speed, j = 1, 2, ..., n, and W i,jN represents the surface heat dissipation power at the i-th oil tank simulation scheme and the j-th typical heat dissipation speed; i,j Let ω be the oil film shear torque at the i-th oil tank simulation scheme and the j-th typical heat dissipation speed; j ω is the angular velocity at the j-th typical heat dissipation rotation speed.

[0024] Furthermore, in step 3, by changing the heat dissipation speed and cooling flow rate, the heat dissipation power and oil film shear torque of the friction plate surface containing the oil groove inner surface under m oil groove simulation schemes, n typical heat dissipation speeds, and p typical cooling flow rates are obtained.

[0025] And calculate the heat dissipation coefficient of the friction plate oil groove in the i-th oil groove simulation scheme according to formula (2);

[0026]

[0027] Among them, K hx Let x be the flow weighting coefficient for the x-th typical cooling flow rate, where x = 1, 2, ..., p, and W i,j,x N represents the surface heat dissipation power under the i-th oil tank simulation scheme, the j-th typical heat dissipation speed, and the x-th typical cooling flow rate; i,j,x The oil film shear torque is given by the i-th oil tank simulation scheme, the j-th typical heat dissipation speed, and the x-th typical cooling flow rate; ω jx ω represents the angular velocity at the j-th typical heat dissipation rotation speed and the x-th typical cooling flow rate.

[0028] Beneficial effects:

[0029] (1) The evaluation of the heat dissipation capacity of the oil groove in this invention examines both the heat dissipation power generated when the cooling oil flows over the surface of the oil groove during the use of the friction plate and the oil churning loss caused by the oil groove. The heat generated by the oil churning process is detrimental to the heat dissipation of the friction plate and should be removed. In addition, since the heat dissipation effect of the oil groove is closely related to the rotational speed of the friction plate and the flow rate of the coolant, the typical heat dissipation rotational speed and cooling flow rate of the friction plate are analyzed, and the concept of the comprehensive heat dissipation coefficient of the oil groove is proposed to more comprehensively evaluate the heat dissipation effect of various oil groove simulation schemes for the friction plate. When the heat dissipation requirements and heat dissipation time requirements of the friction plate are known, it is also possible to evaluate whether different oil groove schemes of the friction plate meet the design requirements. Therefore, this invention can quickly and accurately complete the selection of multiple oil groove schemes for the friction plate, while significantly reducing the oil groove design cycle and economic investment. It plays an important role in promoting the refined design level of friction plate heat dissipation. It can be used for the analysis of the heat dissipation capacity of wet friction plates in wet brakes, wet clutches and other assemblies. It can be used to guide the theoretical analysis of oil groove heat dissipation and provide evaluation reference for the experimental analysis of friction plate oil groove heat dissipation, and has good adaptability.

[0030] (2) When determining the oil groove simulation scheme of m friction plates, this invention considers the working conditions of the friction plates and introduces the speed weight coefficient corresponding to each typical heat dissipation speed and the flow weight coefficient corresponding to each typical cooling flow rate according to the usage requirements to evaluate the heat dissipation capacity of the oil groove. This can more comprehensively evaluate the heat dissipation effect of various oil groove simulation schemes of friction plates.

[0031] (3) This invention obtains the heat dissipation power and oil film shear torque of the friction plate surface containing the oil groove inner surface under m oil groove simulation schemes, n typical heat dissipation speeds, and p typical cooling flow rates; and according to The heat dissipation coefficient of the friction plate oil tank in the i-th oil tank simulation scheme is calculated. The evaluation method of this invention considers the heat dissipation speed and cooling flow rate, and refines the working conditions during the evaluation. It also considers the heat generated by oil churning in the oil tank, and subtracts the power of oil churning from the convective cooling power of the oil when calculating the heat dissipation power of the oil tank, thus refining the evaluation method of oil tank heat dissipation. Compared with the commonly used method of evaluating the heat dissipation capacity of the oil tank using the heat dissipation power of the oil tank under a single working condition, this invention is more consistent with the actual heat dissipation process. Therefore, the calculation method of the friction plate oil tank heat dissipation coefficient proposed in this invention, through weighted quantitative evaluation of factors such as heat dissipation speed and cooling flow rate, can complete the comprehensive evaluation of the heat dissipation capacity of various friction plate oil tank schemes, and can be expanded by introducing weight coefficients of other heat dissipation influencing factors according to the different usage requirements of different friction plates. Attached Figure Description

[0032] Figure 1 The following is a flowchart of the empirical design method for friction plate oil grooves in the background technology;

[0033] Figure 2 Here is a flowchart of the comparative design method for friction plate oil groove tests in the background technology;

[0034] Figure 3 The flowchart below shows the simulation comparison design method for friction plate oil grooves in the background technology.

[0035] Figure 4 This is a flowchart for evaluating the heat dissipation capacity of the oil tank according to the present invention. Detailed Implementation

[0036] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0037] Example 1:

[0038] This embodiment provides a method for evaluating the heat dissipation capacity of wet friction plate oil grooves. See Appendix. Figure 4 The specific steps of this method are as follows:

[0039] Step 1: Determine the operating conditions of the friction plates, including n typical heat dissipation speeds and p typical cooling flow rates, and simultaneously determine the simulation parameters such as fluid material parameters, as well as the speed weighting coefficient K corresponding to each typical heat dissipation speed. ωj The flow weighting coefficient K corresponding to each typical cooling flow rate hx ;

[0040] Step 2: Based on experience, preliminarily determine m simulation schemes for the oil grooves of the friction plates by adjusting the groove type, groove cross-sectional dimensions, and oil groove distribution dimensions. Each simulation scheme can perform calculations for n typical heat dissipation speeds and p typical cooling flow rates under operating conditions. Then, complete the 3D modeling based on the groove type, groove cross-sectional dimensions, and oil groove distribution dimensions of each simulation scheme.

[0041] Step 3: Construct flow field analysis models of friction plate oil grooves corresponding to m oil groove simulation schemes in the flow field analysis software, determine their fluid material parameters and friction surface temperature, and set flow domain boundaries for each friction plate oil groove flow field analysis model. The flow domain boundaries include heat dissipation speed, cooling flow rate, etc.

[0042] Step 4: Under a fixed cooling flow rate, by changing the cooling rotation speed, obtain the heat dissipation power W of the friction plate surface containing the inner surface of the oil groove at n typical cooling rotation speeds in m oil groove simulation schemes. i,j and oil film shear torque N i,j ;

[0043] The heat dissipation coefficient of the friction plate oil groove in the i-th oil groove simulation scheme is calculated according to formula (1);

[0044]

[0045] Among them, K Qi K represents the heat dissipation coefficient of the oil tank structure in the i-th simulation scheme, in watts, i = 1, 2, ..., m; ωj The speed weighting coefficient for the j-th typical heat dissipation speed is determined by the designer based on usage requirements, where j = 1, 2, ..., n. W i,j N represents the surface heat dissipation power at the i-th oil tank simulation scheme and the j-th typical heat dissipation speed, in watts. i,j ω represents the oil film shear torque at the i-th oil tank simulation scheme and the j-th typical cooling speed, in Newtons; j ω represents the angular velocity at the j-th typical heat dissipation rotation speed, in radians per second;

[0046] Step 5: According to the design requirements, as an optimal option, the cooling flow rate can be further changed to analyze the heat dissipation of the oil tank and obtain the heat dissipation power W of the friction plate surface including the inner surface of the oil tank under m oil tank simulation schemes, n typical heat dissipation speeds, and p typical cooling flow rates. i,j,x and oil film shear torque N i,j,x ;

[0047] And calculate the heat dissipation coefficient of the friction plate oil groove in the i-th oil groove simulation scheme according to formula (2);

[0048]

[0049] Among them, K hx The flow weighting coefficient for the x-th typical cooling flow rate is determined by the designer based on usage requirements, where x = 1, 2, ..., p. W i,j,x N represents the surface heat dissipation power under the i-th oil tank simulation scheme, the j-th typical heat dissipation speed, and the x-th typical cooling flow rate, in watts. i,j,x ω represents the oil film shear torque under the i-th oil tank simulation scheme, the j-th typical heat dissipation speed, and the x-th typical cooling flow rate, in Newtons; jx ω represents the angular velocity at the j-th typical heat dissipation speed and the x-th typical cooling flow rate, in radians per second;

[0050] Step 6: After completing all calculations, compare the heat dissipation coefficients of the oil tanks calculated by the m oil tank simulation schemes. The oil tank simulation scheme with the largest heat dissipation coefficient is the one with the best overall heat dissipation performance.

[0051] Step 7: Based on the known heat dissipation energy Q required by the friction plate and the corresponding heat dissipation time t (i.e., the time required for the friction plate to dissipate heat Q), further calculations can be performed according to... The ratio is used to evaluate whether the heat dissipation capacity of the oil tank in each simulation scheme meets the heat dissipation requirements;

[0052] like Then it can be considered that the i-th oil groove simulation scheme can meet the heat dissipation requirements for the friction plate. Therefore, it can be concluded that the i-th oil groove simulation scheme for the friction plate does not meet the heat dissipation requirements.

[0053] Example 2:

[0054] Based on Example 1, this embodiment provides a specific implementation process for a method to evaluate the heat dissipation capacity of a wet friction plate oil groove:

[0055] Step 1: Determine the operating conditions of the friction plates, including three typical heat dissipation speeds: 400 r / min, 1700 r / min, and 2300 r / min; and two typical cooling flow rates: 2 L / min and 4 L / min. Based on the probability of occurrence of each condition and heat dissipation requirements, determine the speed weighting coefficients for the typical heat dissipation speeds of 400 r / min, 1700 r / min, and 2300 r / min to be 0.1, 0.2, and 0.7, respectively; and the flow rate weighting coefficients for the typical cooling flow rates of 2 L / min and 4 L / min to be 0.6 and 0.4, respectively.

[0056] Step 2: Based on experience, determine three simulation schemes for the oil grooves of the friction plates, and complete the three-dimensional modeling based on the groove type, groove cross-sectional dimension parameters, and oil groove distribution dimension parameters of each simulation scheme.

[0057] Step 3: Construct flow field analysis models of the friction plate oil groove corresponding to the three oil groove simulation schemes in the flow field analysis software, determine the fluid material parameters and friction surface temperature, and set the flow domain boundary for each friction plate oil groove flow field analysis model. The flow domain boundary includes heat dissipation speed, cooling flow rate, etc.

[0058] Step 4: By changing the heat dissipation speed and cooling flow rate, obtain the heat dissipation power and oil film shear torque of the friction plate surface containing the oil groove inner surface at three typical heat dissipation speeds and two coolant flow rates in the three oil groove simulation schemes.

[0059] The heat dissipation coefficients of the friction plate oil groove in the three oil groove simulation schemes were calculated according to formula (2) in Example 1, and were 126.7W, 166.7W and 112.8W respectively;

[0060] Step 5: After completing all calculations, compare the heat dissipation coefficients of the oil tanks calculated by the three oil tank simulation schemes, and determine that the second oil tank simulation scheme has the best overall heat dissipation performance.

[0061] Step 6, based on the known heat dissipation energy required by the friction plate is 14500J and the corresponding heat dissipation time is 100s, according to... The ratio is used to evaluate whether the heat dissipation capacity of the oil tank meets the heat dissipation requirements;

[0062] The first and third oil tank simulation schemes The heat dissipation requirements are not met; the second oil tank simulation scheme To meet heat dissipation requirements.

[0063] The specific evaluation data for this embodiment is shown in the table below:

[0064]

[0065]

[0066] In summary, the above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for evaluating the heat dissipation capacity of a wet friction plate oil groove, characterized in that, The specific steps of this method are as follows: Step 1: Determine the oil groove simulation scheme for m types of friction plates. The oil groove simulation scheme for each type of friction plate can perform calculations for n typical heat dissipation speeds and p typical cooling flow rates under operating conditions. Step 2: Construct flow field analysis models of the friction plate oil grooves corresponding to the m oil groove simulation schemes in the flow field analysis software; Step 3: By changing the heat dissipation speed and cooling flow rate, obtain the heat dissipation power and oil film shear torque of the friction plate surface containing the inner surface of the oil groove at n typical heat dissipation speeds and p typical cooling flow rates in m oil groove simulation schemes. The heat dissipation coefficient of the friction plate oil groove in the i-th oil groove simulation scheme is calculated based on the heat dissipation power and oil film shear torque. , i=1,2,…,m; With a fixed cooling flow rate, and only the cooling rotation speed being changed, the heat dissipation coefficient of the friction plate oil groove in the i-th oil groove simulation scheme is calculated. The specific formula is as follows: Official (1) in, Let be the heat dissipation coefficient of the oil tank structure in the i-th simulation scheme, i=1,2,…,m; Let be the speed weighting coefficient for the j-th typical heat dissipation speed, j=1,2,…,n, and ; Let be the surface heat dissipation power at the i-th oil tank simulation scheme and the j-th typical heat dissipation speed. For the i-th oil tank simulation scheme, the oil film shear torque is at the j-th typical heat dissipation speed. ω is the angular velocity at the j-th typical heat dissipation rotation speed; By changing the heat dissipation speed and cooling flow rate, the heat dissipation power and oil film shear torque of the inner surface of the oil groove on the friction plate surface are obtained under m oil groove simulation schemes, n typical heat dissipation speeds, and p typical cooling flow rates. And calculate the heat dissipation coefficient of the friction plate oil groove in the i-th oil groove simulation scheme according to formula (2); Official (2) in, Let x be the flow weighting coefficient for the x-th typical cooling flow rate, where x = 1, 2, ..., p, and ; The surface heat dissipation power is given by the i-th oil tank simulation scheme, the j-th typical heat dissipation speed, and the x-th typical cooling flow rate. The oil film shear torque is given by the i-th oil tank simulation scheme, the j-th typical heat dissipation speed, and the x-th typical cooling flow rate. Angular velocity at the j-th typical heat dissipation rotation speed and the x-th typical cooling flow rate; Step 4: Compare the heat dissipation coefficients of the oil tanks calculated by the m oil tank simulation schemes. The oil tank simulation scheme with the largest heat dissipation coefficient is the one with the best overall heat dissipation performance. Step 5, based on the known heat dissipation energy value Q required by the friction plate and the corresponding heat dissipation time t, according to... The ratio is used to evaluate whether the heat dissipation capacity of the oil tank in each simulation scheme meets the heat dissipation requirements; like If the friction plate meets the heat dissipation requirements using the i-th oil groove simulation scheme, then... If the i-th oil groove simulation scheme is used for the friction plate, it is considered that the heat dissipation requirement is not met.

2. The method for evaluating the heat dissipation capacity of a wet friction plate oil groove as described in claim 1, characterized in that, In step 1, the specific process for determining the oil groove simulation scheme for m types of friction plates is as follows: Step 1-1: Determine the operating conditions of the friction plate, including n typical heat dissipation speeds and p typical cooling flow rates. At the same time, determine the speed weighting coefficient for each typical heat dissipation speed and the flow weighting coefficient for each typical cooling flow rate. Steps 1-2: Based on experience, preliminary simulation schemes for oil grooves of friction plates are determined by adjusting the groove type, groove cross-sectional dimension parameters, and oil groove distribution dimension parameters of the oil grooves. Then, three-dimensional modeling is completed based on the groove type, groove cross-sectional dimension parameters, and oil groove distribution dimension parameters of the friction plate oil grooves for each simulation scheme.

3. The method for evaluating the heat dissipation capacity of a wet friction plate oil groove as described in claim 1, characterized in that, In step 2, after constructing the friction plate oil groove flow field analysis model corresponding to m oil groove simulation schemes in the flow field analysis software, the flow domain boundary is set for each friction plate oil groove flow field analysis model. The flow domain boundary includes the heat dissipation speed and cooling flow rate.

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