A wet clutch thermal characteristic evaluation method

Abstract

The application discloses a kind of wet clutch thermal characteristic evaluation methods, comprising: (a), the design check and thermal stress evaluation of wet clutch, temperature sensor is installed at the position of each clutch plate of wet clutch maximum stress, to simulate the real stress condition of clutch plate;(b), the cooling characteristics and the consistency of temperature deviation between different clutch plate groups of wet clutch are evaluated;(c), the heat capacity evaluation of wet clutch: check the peak temperature reached by clutch plate under different conditions and the highest temperature difference in each piece appears.The application can effectively reduce the overheat failure of wet clutch in subsequent application process.

Description

Technical Field

[0001] This invention relates to the field of hydraulic wet clutch control in transmission systems, specifically to a method for evaluating the thermal characteristics of a wet clutch. Background Technology

[0002] Due to their stable torque transmission characteristics and reliable durability, hydraulic wet clutches are widely used in the field of transmission technology, especially in the field of automotive automatic transmissions, including traditional AT, CVT, DCT, hybrid and new energy transmissions.

[0003] In the operation of wet clutches, whether used for braking, starting, or shifting, the principle is to dissipate energy through friction, generating a significant amount of heat inside the clutch. Verifying whether the clutch product's heat-bearing capacity meets the requirements of actual use while ensuring that the design dimensions are within a reasonable range is crucial. For wet multi-plate clutches, the uniformity of temperature distribution across each plate and the rationality of lubrication and cooling distribution determine the quality of the wet clutch design. Therefore, evaluating the thermal characteristics of wet clutches is of paramount importance in product development. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by providing a method for evaluating the thermal characteristics of wet clutches, which can effectively reduce the occurrence of wet clutch overheating failures during subsequent applications.

[0005] The objective of this invention is achieved through the following solution:

[0006] A method for evaluating the thermal characteristics of a wet clutch includes:

[0007] (a) Design inspection and thermal stress assessment of wet clutches: Temperature sensors are installed at the locations of the greatest stress on each clutch disc in the wet clutch to simulate the actual stress conditions of the clutch discs.

[0008] (b) The cooling characteristics of wet clutches and the consistency of temperature deviations between different clutch plate groups are evaluated.

[0009] (c) Evaluation of the heat resistance of wet clutches: check the peak temperature reached by the clutch plates under different conditions and the highest temperature difference among the plates.

[0010] Furthermore, the design inspection and thermal stress assessment include: using finite element simulation software to establish finite element models of the main components in the wet clutch module, setting boundary conditions according to material parameters and motion parameters, simulating the mechanical properties of the main components, simulating the stress distribution of the clutch plate under pressure, and detecting the uniformity of stress distribution through simulation results, and arranging temperature sensors according to the positions indicated by the simulation results.

[0011] By using the temperature balance method, the balance of the cooling effect inside the wet clutch is detected based on the difference in temperature test results from temperature sensors at different locations, and the balance of heat generated by stress inside the wet clutch is also checked.

[0012] Furthermore, the cooling characteristics and the consistency of temperature deviation between different clutch plates are evaluated: a thermal balance method is used, that is, the total input energy = temperature rise between clutch plates + heat carried away by cooling flow. By using different combinations of cooling flow and total input energy, the peak temperature reached by the wet clutch under different combinations and the temperature difference between each clutch plate group are used to determine the internal cooling characteristics of the wet clutch and the temperature consistency between different clutch plate groups under various conditions.

[0013] Furthermore, the heat resistance of the wet clutch is evaluated: the actual application conditions are analyzed, and the test conditions are divided into speed difference level, torque level, wet clutch active side speed, wet clutch driven side speed and cooling flow rate. The conditions are combined according to the rationality of the application, and the peak temperature reached under different combinations is viewed using the thermal balance method to judge the heat resistance of the wet clutch.

[0014] This invention evaluates the heat resistance of wet clutch products in thermal design, testing, and practical applications. It effectively reduces clutch overheating failures during subsequent applications, ensuring product reliability. It is applicable to various scenarios including wet clutch R&D, transmission assembly development, and vehicle applications. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the temperature sensor's mounting position on the wet clutch plate.

[0016] Figure 2 A schematic diagram showing the distribution of lubricating oil between the wet clutch plates.

[0017] Figure 3 This is a schematic diagram illustrating the proper distribution of lubricating oil between the clutch plates.

[0018] Figure 4 This is a schematic diagram illustrating poor distribution of lubricating oil between the clutch plates. Detailed Implementation

[0019] like Figure 1 As shown, a method for evaluating the thermal characteristics of a wet clutch includes the following evaluation process:

[0020] (a) Design inspection and thermal stress assessment of wet clutches: Temperature sensors are installed at the locations of the greatest stress on each clutch disc in the wet clutch to simulate the actual stress conditions of the clutch discs.

[0021] The design inspection and thermal stress assessment include: using finite element simulation software to establish finite element models of the main components in the wet clutch module, and setting boundary conditions according to material parameters and motion parameters, simulating the mechanical properties of the main components (including friction plates, steel plates, pistons, circlips, and gear hubs), simulating the stress distribution of the clutch plates under pressure, and detecting the uniformity of stress distribution through simulation results, and placing temperature sensors according to the positions indicated by the simulation results; using the temperature balance method, detecting the balance of the cooling effect inside the wet clutch based on the difference in temperature test results from temperature sensors at different positions, and checking the balance of heat generated by stress inside the wet clutch.

[0022] (b) The cooling characteristics of the wet clutch and the consistency of temperature deviation between different clutch plate groups were evaluated.

[0023] The cooling characteristics and the consistency of temperature deviation between different clutch plates are evaluated using a thermal balance method, i.e., total input energy = temperature rise between clutch plates + heat carried away by cooling flow. By using different combinations of cooling flow (e.g., lubricating oil) and total input energy, the characteristics of internal cooling of the wet clutch and the temperature consistency between different clutch plates under various conditions are judged by the peak temperature reached by the wet clutch under different combinations and the temperature difference between each clutch plate group.

[0024] (c) Assessment of the clutch’s heat resistance: Check the peak temperature reached by the clutch plates under different conditions and the highest temperature difference among the plates.

[0025] The heat resistance of the wet clutch is evaluated by analyzing the actual application conditions and dividing the test conditions into speed difference level, torque level, wet clutch active side speed, wet clutch driven side speed and cooling flow rate. The conditions are combined according to the rationality of the application, and the peak temperature reached under different combinations is viewed using the thermal balance method to judge the heat resistance of the wet clutch.

[0026] The speed difference level and torque level determine the level of input energy. The higher the speed difference level and torque level, the higher the input energy, the more severe the corresponding operating conditions, and consequently, the higher the peak temperature of the clutch. Classifying the test conditions according to different speed difference levels and torque levels is equivalent to categorizing the severity of the test conditions.

[0027] The heat resistance of a clutch is characterized by the highest permissible temperature of the friction plate material; the higher the permissible maximum temperature, the stronger the heat resistance of the product. Different materials have different definitions; for paper-based friction materials, 350℃ is used.

[0028] like Figure 1 As shown, this is a simulation analysis of a wet clutch with 4 friction plates. Based on the results of the stress distribution of the clutch plates confirmed in (a) above, the uniformity of the stress distribution and the location of the maximum stress on each plate are confirmed. According to the principle of heat generation by clutch friction, the location of the maximum stress is likely to be the location of the highest heat. The magnitude of the stress value at this location determines the possible temperature deviation during temperature testing. The temperature sensor (preferably a thermocouple) is placed in the corresponding position.

[0029] like Figure 2 As shown, to confirm the cooling effect, under the condition that the wet clutch is not damaged (below the allowable operating temperature of the wet clutch), under the same total input energy, adjust the input cooling flow rate (e.g., lubricating oil) until the temperature difference on different clutch plates increases or no longer decreases. Use the temperature change trend between each plate to determine the quality of the clutch flow distribution.

[0030] like Figure 3 As shown, after the temperature of each clutch plate reaches thermal equilibrium, increasing the input flow rate, if the temperature difference between different plates changes in a consistent trend as the temperature decreases, indicates that the clutch lubrication flow is well distributed between the plates; for example... Figure 4 As shown, if the temperature difference trend between the plates is inconsistent or the temperature change rate is significantly lower than that of other plates, it indicates that the lubrication flow is less distributed at that plate location, resulting in poor cooling effect.

[0031] The assessment of heat dissipation capacity involves a comprehensive evaluation. Under the product's permissible temperature, different combinations of energy input and lubrication are used (based on the actual application conditions to evaluate the clutch's heat-bearing capacity). This combination is considered reasonable in the application process. The peak temperature reached under different combinations and the temperature differences between them are then examined for evaluation.

[0032] Identifying typical operating condition elements and formulating combined operating conditions are essential for analyzing basic application operating conditions. The basic elements of these conditions mainly include:

[0033] Clutch driving side speed: generally the speed of the engine side;

[0034] Clutch driven side speed: generally the speed at which the gears connect to the transmission gears;

[0035] Friction torque: The torque that occurs when friction occurs; the friction torque generated by the clutch due to driving pressure.

[0036] Cooling flow rate: The flow rate of lubrication actively controlled when heat is generated;

[0037] Friction time factor: derived from statistics based on actual applications.

[0038] The actual application combinations are evaluated or tested in the manner described in Table 1. The judgment method is to confirm the highest temperature that occurs under the current conditions and the largest temperature difference between different clutch plates. If the highest temperature or temperature difference is higher than that of conventional clutch products, the results need to be returned to the designer for evaluation.

[0039] Table 1. Operating Condition Identification and Test Results

[0040]

[0041] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications made to the present invention by those skilled in the art without departing from the spirit of the present invention shall fall within the protection scope of the present invention.

Claims

1. A wet clutch thermal characteristic evaluation method, characterized by, include: (a) Design inspection and thermal stress assessment of wet clutches: Temperature sensors are installed at the locations of the greatest stress on each clutch disc in the wet clutch to simulate the actual stress conditions of the clutch discs. The design review and thermal stress assessment include: using finite element simulation software to establish finite element models of the main components in the wet clutch module. Boundary conditions are set according to material parameters and motion parameters, and the mechanical properties of the main parts are simulated and calculated to simulate the stress distribution of the clutch plate after being compressed. At the same time, the uniformity of stress distribution is detected by simulation results, and temperature sensors are placed according to the positions indicated by the simulation results. By using the temperature balance method, the balance of the cooling effect inside the wet clutch is detected based on the difference in temperature test results from temperature sensors at different locations, and the balance of the heat generated by stress inside the wet clutch is also checked. (b) The cooling characteristics of wet clutches and the consistency of temperature deviations between different clutch plate groups are evaluated. (c) Evaluation of the heat resistance of wet clutches: check the peak temperature reached by the clutch plates under different conditions and the highest temperature difference among the plates.

2. A wet clutch thermal characteristic evaluation method according to claim 1, characterized in that, Evaluation of cooling characteristics and temperature deviation consistency between different clutch plate groups: The thermal balance method is adopted, that is, the total input energy = temperature rise between clutch plates + heat carried away by cooling flow. By using different combinations of cooling flow and total input energy, the peak temperature reached by the wet clutch under different combinations and the temperature difference between each clutch plate group are used to determine the internal cooling characteristics of the wet clutch and the temperature consistency between different clutch plate groups under various conditions.

3. The wet clutch thermal characteristic evaluation method of claim 1, wherein The heat resistance capacity of wet clutches is evaluated by analyzing actual application conditions and dividing the test conditions into speed difference level, torque level, wet clutch driving side speed, wet clutch driven side speed and cooling flow rate. The conditions are combined according to the rationality of the application, and the peak temperature reached under different combinations is viewed using the thermal balance method to judge the heat resistance capacity of the wet clutch.

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