Transmission oil temperature estimation method, device, vehicle and storage medium

Abstract

The application provides a gearbox oil temperature estimation method, device, vehicle and storage medium, which are applied to the field of vehicles, and the method comprises the following steps: acquiring the gearbox orifice size, average clutch pressure and average oil pump rotating speed of a current hydraulic system; based on the gearbox orifice size and the average clutch pressure, the first and second oil temperature estimation values are determined from a preset pressure-oil temperature-rotating speed relationship table corresponding to multiple orifice diameters according to the average oil pump rotating speed; and based on the gearbox orifice size, the first and second oil temperature estimation values are subjected to linear interpolation calculation to obtain the transmission oil temperature. According to the method, the relationship among the measurable physical quantities such as the clutch pressure in the clutch oil circuit, the oil pump rotating speed and the transmission oil temperature can be used to estimate the gearbox oil temperature after the temperature sensor fails, the accuracy of the oil temperature estimation is ensured through the identification of the orifice size, and the control of the clutch pressure can still be normally operated.

Description

Technical Field

[0001] This application relates to the field of vehicles, and more specifically, to a method, apparatus, vehicle, and storage medium for estimating transmission oil temperature in the field of vehicles. Background Technology

[0002] In transmission designs with fewer clutches, an increasing number of manufacturers are opting for hydraulic systems that directly control clutch pressure via an electric pump. Compared to traditional hydraulic systems that control clutch pressure through solenoid valves, this reduces the need for complex and costly solenoid valves and hydraulic valve plates. In hydraulic systems where the electric pump directly controls clutch pressure, oil temperature affects oil viscosity, which in turn affects pressure. Therefore, the oil temperature signal obtained from the oil pan temperature sensor is crucial for the pressure control strategy and algorithm in the transmission controller. If this sensor malfunctions, pressure control will struggle to operate properly.

[0003] In related technologies, a transmission control method is proposed. During the development and testing phase, a relatively accurate current-speed-oil temperature correspondence table can be established by setting a preset electric oil pump motor speed at different oil temperatures, and then written into the electric oil pump system. When the oil temperature sensor malfunctions, the control system periodically switches between an oil temperature estimation mode and a normal operating mode. In the oil temperature estimation mode, the electric pump is controlled to a preset speed, and after stabilizing for a period of time, the stable current of the BLDC (Brushless Direct Current Motor) is obtained. By consulting the current-speed-oil temperature correspondence table, the current oil temperature is estimated.

[0004] However, this method does not take into account the influence of the orifice diameter on oil temperature estimation, which leads to deviations in oil temperature estimation and fails to guarantee the accuracy of oil temperature estimation, and this problem urgently needs to be solved. Summary of the Invention

[0005] This application provides a method, device, vehicle, and storage medium for estimating transmission oil temperature. The method can estimate the transmission oil temperature even after a temperature sensor fails by using the relationship between measurable physical quantities such as clutch pressure, oil pump speed, and transmission oil temperature in the clutch oil circuit. Furthermore, by identifying the throttle orifice size, the accuracy of the oil temperature estimation is ensured, and the clutch pressure control can still operate normally.

[0006] Firstly, a method for estimating transmission oil temperature is provided, the method comprising the following steps:

[0007] Obtain the current gearbox throttle orifice size, average clutch pressure, and average oil pump speed of the hydraulic system;

[0008] Based on the gearbox throttle orifice size and the average clutch pressure, a first oil temperature estimate and a second oil temperature estimate are determined from a preset table of pressure-oil temperature-speed relationships corresponding to multiple throttle orifice diameters, according to the average oil pump speed; and

[0009] Based on the size of the transmission throttle orifice, the transmission oil temperature is calculated by linear interpolation of the first oil temperature estimate and the second oil temperature estimate.

[0010] The above technical solution enables the estimation of transmission oil temperature even after the temperature sensor fails, by using the relationship between measurable physical quantities such as clutch pressure, oil pump speed, and transmission oil temperature in the clutch oil circuit. Furthermore, by identifying the throttle orifice size, the accuracy of the oil temperature estimation is ensured, thus guaranteeing that clutch pressure control can still operate normally.

[0011] In conjunction with the first aspect, in some possible implementations, determining the first and second oil temperature estimates based on the gearbox throttle orifice size and the average clutch pressure, according to the average oil pump speed, from a preset table of pressure-oil temperature-speed relationships corresponding to multiple throttle orifice diameters, includes:

[0012] The first throttle orifice size cutoff point and the second throttle orifice size cutoff point are determined based on the gearbox throttle orifice size, and the first pressure cutoff point and the second pressure cutoff point are determined based on the average clutch pressure.

[0013] Based on the first throttle orifice size breakpoint, a first pressure-oil temperature-speed reference table and a second pressure-oil temperature-speed reference table are determined from the preset multiple throttle orifice diameter corresponding pressure-oil temperature-speed relationship reference tables. Based on the first pressure-oil temperature-speed reference table and the second pressure-oil temperature-speed reference table, a first initial oil temperature estimate and a second initial oil temperature estimate are obtained according to the first pressure breakpoint, the second pressure breakpoint and the average oil pump speed.

[0014] Based on the absolute value of the difference between the average clutch pressure and the first pressure breakpoint, and the absolute value of the difference between the average clutch pressure and the second pressure breakpoint, the first initial oil temperature estimate is obtained by linear interpolation of the first initial oil temperature estimate and the second initial oil temperature estimate.

[0015] In combination with the first aspect and the above implementation, in some possible implementations, after determining the first pressure breakpoint and the second pressure breakpoint based on the average clutch pressure, the method further includes:

[0016] Based on the second throttle orifice size breakpoint, a third pressure-oil temperature-speed comparison table and a fourth pressure-oil temperature-speed comparison table are determined from the preset multiple throttle orifice diameter corresponding pressure-oil temperature-speed relationship comparison tables. Based on the third pressure-oil temperature-speed comparison table and the fourth pressure-oil temperature-speed comparison table, a third initial oil temperature estimate and a fourth initial oil temperature estimate are obtained according to the first pressure breakpoint, the second pressure breakpoint and the average oil pump speed.

[0017] Based on the absolute value of the difference between the average clutch pressure and the first pressure breakpoint, and the absolute value of the difference between the average clutch pressure and the second pressure breakpoint, the second oil temperature estimate is obtained by linear interpolation of the third initial oil temperature estimate and the fourth initial oil temperature estimate.

[0018] In combination with the first aspect and the above-described implementations, in some possible implementations, obtaining the current hydraulic system's gearbox throttle orifice size, average clutch pressure, and average oil pump speed includes:

[0019] Determine the target oil temperature, target clutch pressure, and target oil pump speed;

[0020] Based on the target oil temperature and the target clutch pressure, the throttle orifice size of the gearbox is obtained by looking up a table of pressure-oil temperature-speed relationships corresponding to multiple preset throttle orifice diameters according to the target oil pump speed.

[0021] In combination with the first aspect and the above implementation methods, in some possible implementation methods, before obtaining the throttle orifice size of the transmission from a preset table of pressure-oil temperature-speed relationships corresponding to multiple throttle orifice diameters based on the target oil temperature and the target clutch pressure, according to the target oil pump speed, the method further includes:

[0022] Determine the diameters of multiple throttling orifices;

[0023] Based on the diameter of each throttle orifice, the oil temperature was recorded at different clutch pressures and different oil pump speeds.

[0024] Based on the multiple throttle orifice diameters, the different clutch pressures corresponding to each throttle orifice diameter, and the oil temperatures at different oil pump speeds, a pressure-oil temperature-speed relationship table corresponding to the multiple preset throttle orifice diameters is obtained.

[0025] In combination with the first aspect and the above implementation methods, in some possible implementation methods, before obtaining the gearbox throttle orifice size, the average clutch pressure, and the average oil pump speed of the current hydraulic system, the following method is further included:

[0026] Determine whether the current hydraulic system is in a preset steady-state state;

[0027] If the current hydraulic system is not in the preset steady state, then the acquisition of the gearbox throttle orifice size, the average clutch pressure, and the average oil pump speed of the current hydraulic system will be stopped.

[0028] The above technical solution allows for the determination of whether the current hydraulic system is in a preset steady-state state before updating the transmission oil temperature. Only when the current hydraulic system is in a preset steady-state state will the transmission oil temperature be updated, thus achieving effective estimation of the transmission oil temperature.

[0029] In combination with the first aspect and the above implementation methods, in some possible implementation methods, after obtaining the transmission oil temperature by linear interpolation of the first oil temperature estimate and the second oil temperature estimate, the method further includes:

[0030] Determine if the current oil pan stability sensor is in a malfunctioning state;

[0031] If the current oil pan stability sensor is not in the failed state, then the value of the current oil pan stability sensor is taken as the transmission oil temperature.

[0032] Secondly, a transmission oil temperature estimation device is provided, the device comprising:

[0033] The acquisition module is used to acquire the current hydraulic system's gearbox throttle orifice size, average clutch pressure, and average oil pump speed.

[0034] The first determining module is used to determine a first oil temperature estimate and a second oil temperature estimate based on the gearbox throttle orifice size and the average clutch pressure, according to the average oil pump speed, from a preset table of pressure-oil temperature-speed relationships corresponding to multiple throttle orifice diameters; and

[0035] The calculation module is used to perform linear interpolation calculation on the first oil temperature estimate and the second oil temperature estimate based on the size of the transmission throttle orifice to obtain the transmission oil temperature.

[0036] Further, the first determining module includes:

[0037] The first determining unit is used to determine the first throttle orifice size cutoff point and the second throttle orifice size cutoff point based on the size of the gearbox throttle orifice, and to determine the first pressure cutoff point and the second pressure cutoff point based on the average clutch pressure.

[0038] The second determining unit is used to determine a first pressure-oil temperature-speed comparison table and a second pressure-oil temperature-speed comparison table from the preset multiple pressure-oil temperature-speed comparison tables corresponding to the diameters of the first throttle orifice based on the first pressure-oil temperature-speed comparison table and the second pressure-oil temperature-speed comparison table, and to obtain a first initial oil temperature estimate and a second initial oil temperature estimate based on the first pressure breakpoint, the second pressure breakpoint and the average oil pump speed.

[0039] The calculation unit is used to perform linear interpolation calculation on the first initial oil temperature estimate and the second initial oil temperature estimate based on the absolute value of the difference between the average clutch pressure and the first pressure breakpoint and the absolute value of the difference between the average clutch pressure and the second pressure breakpoint to obtain the first oil temperature estimate.

[0040] Furthermore, after determining the first pressure breakpoint and the second pressure breakpoint based on the average clutch pressure, the first determining unit is further configured to:

[0041] Based on the second throttle orifice size breakpoint, a third pressure-oil temperature-speed comparison table and a fourth pressure-oil temperature-speed comparison table are determined from the preset multiple throttle orifice diameter corresponding pressure-oil temperature-speed relationship comparison tables. Based on the third pressure-oil temperature-speed comparison table and the fourth pressure-oil temperature-speed comparison table, a third initial oil temperature estimate and a fourth initial oil temperature estimate are obtained according to the first pressure breakpoint, the second pressure breakpoint and the average oil pump speed.

[0042] Based on the absolute value of the difference between the average clutch pressure and the first pressure breakpoint, and the absolute value of the difference between the average clutch pressure and the second pressure breakpoint, the second oil temperature estimate is obtained by linear interpolation of the third initial oil temperature estimate and the fourth initial oil temperature estimate.

[0043] Furthermore, the acquisition module is specifically used for:

[0044] Determine the target oil temperature, target clutch pressure, and target oil pump speed;

[0045] Based on the target oil temperature and the target clutch pressure, the throttle orifice size of the gearbox is obtained by looking up a table of pressure-oil temperature-speed relationships corresponding to multiple preset throttle orifice diameters according to the target oil pump speed.

[0046] Furthermore, before determining the throttle orifice size of the transmission by looking up a preset table of pressure-oil temperature-speed relationships corresponding to multiple throttle orifice diameters based on the target oil temperature and the target clutch pressure, and according to the target oil pump speed, the process further includes:

[0047] The second determining module is used to determine the diameters of multiple throttling orifices;

[0048] The recording module is used to record the oil temperature at different clutch pressures and different oil pump speeds based on the diameter of each throttle orifice.

[0049] The tabulation module is used to obtain a preset table of pressure-oil temperature-speed relationships for the multiple throttle orifice diameters, the different clutch pressures corresponding to each throttle orifice diameter, and the oil temperature at different oil pump speeds.

[0050] Furthermore, before obtaining the gearbox throttle orifice size, the average clutch pressure, and the average oil pump speed of the current hydraulic system, the method further includes:

[0051] The judgment module is used to determine whether the current hydraulic system is in a preset steady-state state;

[0052] The control module is used to stop acquiring the gearbox throttle orifice size, the average clutch pressure, and the average oil pump speed of the current hydraulic system when the current hydraulic system is not in the preset steady-state state.

[0053] Furthermore, after obtaining the transmission oil temperature by linear interpolation of the first oil temperature estimate and the second oil temperature estimate, the calculation module is further configured to:

[0054] Determine if the current oil pan stability sensor is in a malfunctioning state;

[0055] If the current oil pan stability sensor is not in the failed state, then the value of the current oil pan stability sensor is taken as the transmission oil temperature.

[0056] Thirdly, a vehicle is provided, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, the processor executing the program to implement the method as described in the first aspect or any possible implementation thereof.

[0057] Fourthly, a computer-readable storage medium is provided that stores computer program code, which, when executed on a computer, causes the computer to perform the methods described in the first aspect or any possible implementation thereof. Attached Figure Description

[0058] Figure 1 This is a pressure control method in a traditional gearbox controller provided by relevant technologies;

[0059] Figure 2This is a flowchart of a transmission oil temperature estimation method provided according to an embodiment of this application;

[0060] Figure 3 This is a simplified schematic diagram of a hydraulic system provided according to an embodiment of this application;

[0061] Figure 4 This is a schematic diagram illustrating the relationship between pressure, oil temperature, and BLDC rotational speed under different orifice diameters according to embodiments of this application.

[0062] Figure 5 This is a block diagram of a transmission oil temperature estimation device provided according to an embodiment of this application;

[0063] Figure 6 This is a structural schematic diagram of a vehicle provided according to an embodiment of this application. Detailed Implementation

[0064] The technical solutions in this application will be clearly and thoroughly described below with reference to the accompanying drawings. In the description of the embodiments of this application, unless otherwise stated, " / " means "or," for example, A / B can mean A or B. "And / or" in the text is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Furthermore, in the description of the embodiments of this application, "multiple" refers to two or more than two.

[0065] Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as implying or suggesting relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.

[0066] In hydraulic systems where an electric pump directly controls clutch pressure, the electric pump is driven by a brushless DC motor. The pump's rotation fills the oil circuit and clutch chamber with hydraulic fluid. A fixed-size drain port is located in the oil circuit between the pump and the clutch chamber. A portion of the pumped fluid enters the clutch chamber, while the remainder is discharged through the drain port. The drain port's diameter is much smaller than the oil circuit's diameter, and can be considered a throttling orifice. As the fluid flows through this orifice, a pressure difference is created across it. This pressure difference is primarily determined by the flow rate, fluid viscosity, and orifice diameter. Fluid viscosity is closely related to oil temperature; lower temperatures result in higher viscosity and a greater pressure difference across the orifice. Since the pressure outside the oil circuit is atmospheric pressure, which can be considered constant, the pressure inside the circuit increases. Higher pressure within the circuit increases the load on the BLDC motor driving the electric pump, resulting in a greater current. In this type of hydraulic system, oil temperature affects fluid viscosity, which in turn affects pressure. Therefore, the oil temperature signal obtained by the oil pan temperature sensor is crucial for the pressure control strategy and algorithm in the transmission controller. If the temperature sensor fails, the pressure control will be difficult to operate normally.

[0067] Currently in the industry, the traditional pressure control logic diagram is as follows: Figure 1 As shown, based on the target oil pressure (prs_tar) and the actual oil temperature (Tmp_sensor), the BLDC feedforward target duty cycle (duty_ff) is obtained by looking up the MAP table. Based on the pressure control deviation, the feedback target duty cycle (duty_fb) is calculated using the PID (Proportional Integral Derivative) controller. The two are then added together to obtain the final target duty cycle (duty_tar). Here, the MCU (Microcontroller Unit) is the controller of the BLDC motor, Gp represents the hydraulic system, spd_actl represents the actual speed of the BLDC motor, and prs_actl represents the actual pressure of the hydraulic system.

[0068] A related technology provides an alternative method for oil temperature sensors. During the development and testing phase, this method establishes a relatively accurate current-speed-oil temperature correspondence table by setting a preset electric oil pump motor speed at different oil temperatures, and then writes this table into the electric oil pump system. When the oil temperature sensor malfunctions, the control system periodically switches between an oil temperature estimation mode and a normal operating mode. In the oil temperature estimation mode, the electric pump is controlled to a preset speed, and after stabilizing for a period of time, a stable current from the BLDC motor is obtained. By consulting the current-speed-oil temperature correspondence table, the current oil temperature is estimated.

[0069] However, while this method doesn't explicitly specify whether it refers to an electric pump controlling cooling flow or clutch pressure, it's actually only suitable for electric pumps used to cool oil circuits. This is because estimating oil temperature requires adjusting the electric pump speed to a preset value. Under steady-state conditions at different oil temperatures, speed and pressure are directly correlated, thus altering clutch pressure. Clutch pressure, determined by the required lock-up torque, cannot be easily changed. If this method is applied to electric pumps used to cool oil circuits, the load on the cooling oil circuit remains relatively low at both normal and high temperatures, making it difficult for the BLDC motor current to change significantly. Therefore, the accuracy of oil temperature estimation will be affected.

[0070] Furthermore, the diameter of the throttle orifice in the oil circuit has a significant impact on the control parameters of the hydraulic system. Under steady-state conditions, at the same oil temperature and pressure, different throttle orifice diameters will result in different oil pump speeds, BLDC duty cycles, and currents. There are certain tolerances in the machining of the throttle orifice. During the development and testing phase, the above method established a relatively accurate current-speed-oil temperature correspondence table by giving a preset electronic oil pump motor speed at different oil temperatures. However, it did not reflect the influence of the throttle orifice diameter tolerance. Therefore, this table usually selects an average value. Individual differences in the throttle orifice can lead to deviations in oil temperature estimation.

[0071] Based on the aforementioned problems, this application provides a method for estimating transmission oil temperature. By utilizing the influence of oil temperature on oil viscosity and the relationship between pressure, pump speed, and oil temperature in the clutch oil circuit, the method can effectively estimate the oil pan temperature sensor signal after the transmission oil pan temperature sensor fails by comparing the relationship between measurable physical quantities (i.e., pressure, pump speed, and oil temperature) in the hydraulic system. Furthermore, by identifying the throttle orifice size, the accuracy of oil temperature estimation is ensured within the throttle orifice design tolerance, thus solving the problem of clutch pressure control failing to operate normally after the oil pan temperature sensor fails. In addition, this method can also estimate oil temperature while the clutch pump is operating normally, allowing oil temperature estimation and clutch pressure control to proceed in parallel without the need to set a separate oil temperature estimation mode. It also controls the electric pump to enter a preset operating condition, avoiding conflicts with the normal clutch pressure control requirements.

[0072] Figure 2 This is a flowchart of a transmission oil temperature estimation method provided in an embodiment of this application.

[0073] For example, such as Figure 2 As shown, the transmission oil temperature estimation method includes the following steps:

[0074] In step S201, the gearbox throttle orifice size, average clutch pressure, and average oil pump speed of the current hydraulic system are obtained.

[0075] It should be noted that hydraulic systems can utilize the orifice effect to control different pressures. A simplified diagram of a hydraulic system is shown below. Figure 3 As shown, the relationships between physical quantities in the system are as shown in equation (1). The formation of pressure is closely related to the flow rate, oil density, and orifice diameter. Since the oil is directly discharged into the housing through the orifice and the back pressure is atmospheric pressure, the pressure difference is equal to the pressure in the clutch oil circuit.

[0076]

[0077] Where Q is the flow rate (L / min), Δp is the pressure difference across the orifice (bar), p1 is the pressure at the orifice inlet (bar), d is the orifice diameter (mm), and ρ is the cooling oil density (g / cm³). 3 ), where α is the flow coefficient, which is related to the shape of the orifice.

[0078] In addition, the viscosity of the oil changes significantly with the oil temperature, which affects the extension resistance between the oil pump and the throttle orifice, as well as the volumetric efficiency of the oil pump. Under the same clutch pressure, the oil temperature and the size of the throttle orifice will affect the oil pump speed under steady-state pressure.

[0079] Understandably, the most important physical quantities in the current hydraulic system include: oil temperature in the oil pan, clutch pressure, BLDC motor duty cycle, current, and oil pump speed, as well as the diameter of the transmission throttle orifice. Except for the orifice diameter, the other physical quantities can be obtained directly or indirectly through sensors. These physical quantities are strongly coupled; when the oil temperature sensor fails, the transmission oil temperature can be estimated using these measurable physical quantities.

[0080] The following details how to obtain the current hydraulic system's gearbox throttle orifice size, average clutch pressure, and average oil pump speed.

[0081] As one possible approach, in some embodiments, obtaining the gearbox orifice size, average clutch pressure, and average oil pump speed of the current hydraulic system includes: determining the target oil temperature, target clutch pressure, and target oil pump speed; and based on the target oil temperature and target clutch pressure, looking up the gearbox orifice size from a preset table of pressure-oil temperature-speed relationships corresponding to multiple orifice diameters according to the target oil pump speed.

[0082] Specifically, during the end-of-life (EOL) test, the target oil temperature and target clutch pressure are determined. At the target oil temperature, the clutch is controlled to reach the target pressure value. Based on the target oil temperature and target clutch pressure, the target oil pump speed is obtained by looking up a table of pressure-oil temperature-speed relationships corresponding to multiple preset orifice diameters. Based on the relationship between the target oil pump speed and the orifice diameter, the orifice size of the transmission can be obtained and stored in the transmission controller's NVM (Non-Volatile Memory). The relationship between the target oil pump speed and the orifice diameter is shown in Table 1.

[0083] Table 1

[0084]

[0085] The average clutch pressure and average pump speed of the current hydraulic system can be calculated by averaging when the hydraulic system pressure is stable. In actual operation, the clutch pressure and pump speed fluctuate slightly. To determine whether the hydraulic system pressure is stable, a certain time period (e.g., 3 seconds) can be selected. If the difference between the maximum and minimum threshold values ​​of the clutch BLDC duty cycle is less than a certain range (e.g., 1%), and the difference between the maximum and minimum threshold values ​​of the actual clutch pressure is also less than a certain range (e.g., 0.2 bar), then the hydraulic system pressure can be determined to be stable. At this time, the average clutch pressure and average pump speed of the current hydraulic system when the pressure is stable can be calculated.

[0086] To facilitate understanding, the following describes how to obtain a table showing the pressure-oil temperature-speed relationship corresponding to multiple preset orifice diameters.

[0087] Furthermore, in some embodiments, before obtaining the gearbox orifice size by looking up a table of pressure-oil temperature-speed relationships corresponding to multiple orifice diameters based on the target oil temperature and target clutch pressure and the target oil pump speed, the method further includes: determining multiple orifice diameters; recording the oil temperature at different clutch pressures and different oil pump speeds based on each orifice diameter; and obtaining a preset table of pressure-oil temperature-speed relationships corresponding to multiple orifice diameters based on the multiple orifice diameters, the different clutch pressures corresponding to each orifice diameter, and the oil temperature at different oil pump speeds.

[0088] Specifically, during the gearbox development process, multiple clutch oil circuit throttle orifices with different diameters within the tolerance range are selected. Based on the diameter of each throttle orifice, the oil temperature at different clutch pressures and oil pump speeds is recorded. This establishes a pre-defined table of pressure-oil temperature-speed relationships corresponding to multiple throttle orifice diameters. The relationships are as follows: Figure 4As shown. The breakpoints in the relationship lookup table can be selected as follows: select 3 to 5 sizes for the orifice diameter, with the spacing between sizes as uniform as possible, and use the actual machining size as the breakpoint; the pressure breakpoints are 1 to 14 bar, with a 1 bar interval; the oil temperature breakpoints are -40℃ to 140℃, with a 10℃ interval.

[0089] In step S202, based on the gearbox throttle orifice size and average clutch pressure, the first oil temperature estimate and the second oil temperature estimate are determined from a preset table of pressure-oil temperature-speed relationships corresponding to multiple throttle orifice diameters according to the average oil pump speed.

[0090] In other words, after obtaining the current gearbox throttle orifice size, average clutch pressure, and average oil pump speed of the hydraulic system, the system can, under normal operating conditions, look up a preset table of pressure-oil temperature-speed relationships corresponding to multiple throttle orifice diameters based on the gearbox throttle orifice size, average clutch pressure, and average oil pump speed, thereby determining the current first and second oil temperature estimates.

[0091] The following details how to determine the first and second oil temperature estimates based on the gearbox throttle orifice size and average clutch pressure, according to the average oil pump speed, from a preset table of pressure-oil temperature-speed relationships corresponding to multiple throttle orifice diameters.

[0092] In one possible implementation, in some embodiments, based on the gearbox orifice size and average clutch pressure, a first oil temperature estimate and a second oil temperature estimate are determined from a preset table of pressure-oil temperature-speed relationships corresponding to multiple orifice diameters, based on the average oil pump speed. This includes: determining a first orifice size breakpoint and a second orifice size breakpoint based on the gearbox orifice size, and determining a first pressure breakpoint and a second pressure breakpoint based on the average clutch pressure; determining a first pressure-oil temperature-speed reference table and a second pressure-oil temperature-speed reference table from the preset table of pressure-oil temperature-speed relationships corresponding to multiple orifice diameters based on the first orifice size breakpoint, and obtaining a first initial oil temperature estimate and a second initial oil temperature estimate based on the first pressure breakpoint, the second pressure breakpoint, and the average oil pump speed; and performing linear interpolation on the first initial oil temperature estimate and the second initial oil temperature estimate based on the absolute value of the difference between the average clutch pressure and the first pressure breakpoint, and the absolute value of the difference between the average clutch pressure and the second pressure breakpoint, to obtain the first oil temperature estimate.

[0093] For example, assuming the current transmission throttle orifice size is 0.805mm, the first throttle orifice size cutoff point can be determined to be 0.8mm and the second throttle orifice size cutoff point to be 0.82mm. Assuming the current average clutch pressure is 8.3bar, the first pressure cutoff point can be determined to be 8bar and the second pressure cutoff point to be 9bar. Based on the first throttle orifice size breakpoint of 0.8mm, and the first pressure breakpoint of 8bar and the second pressure breakpoint of 9bar, the first pressure-oil temperature-speed reference table and the second pressure-oil temperature-speed reference table (Table 1 and Table 2) can be determined from the preset reference tables of pressure-oil temperature-speed corresponding to multiple throttle orifice diameters. Based on the first pressure-oil temperature-speed reference table and the second pressure-oil temperature-speed reference table, the first initial oil temperature estimate T1 and the second initial oil temperature estimate T2 can be obtained by looking up the tables according to the first pressure breakpoint of 8bar, the second pressure breakpoint of 9bar and the average oil pump speed. Based on the absolute value of the difference between the current average clutch pressure and the first pressure breakpoint (i.e., |8.3-8|=0.3) and the absolute value of the difference between the average clutch pressure and the second pressure breakpoint (i.e., |8.3-9|=0.7), the first initial oil temperature estimate T1 and the second initial oil temperature estimate T2 can be obtained by linear interpolation calculation.

[0094] Furthermore, in some other embodiments, after determining the first pressure breakpoint and the second pressure breakpoint based on the average clutch pressure, the method further includes: determining a third pressure-oil temperature-speed reference table and a fourth pressure-oil temperature-speed reference table from a preset reference table of pressure-oil temperature-speed corresponding to multiple throttle orifice diameters based on the second throttle orifice size breakpoint; obtaining a third initial oil temperature estimate and a fourth initial oil temperature estimate based on the third pressure-oil temperature-speed reference table and the fourth pressure-oil temperature-speed reference table, according to the first pressure breakpoint, the second pressure breakpoint, and the average oil pump speed; and performing linear interpolation calculation on the third initial oil temperature estimate and the fourth initial oil temperature estimate to obtain a second oil temperature estimate based on the absolute value of the difference between the average clutch pressure and the first pressure breakpoint, and the absolute value of the difference between the average clutch pressure and the second pressure breakpoint.

[0095] For example, based on the second throttle orifice size cutoff of 0.82mm, and the first pressure cutoff of 8bar and the second pressure cutoff of 9bar, a third pressure-oil temperature-speed reference table and a fourth pressure-oil temperature-speed reference table (Table 3 and Table 4) can be determined from a preset reference table of pressure-oil temperature-speed relationships corresponding to multiple throttle orifice diameters. Based on the third and fourth pressure-oil temperature-speed reference tables, the third initial oil temperature estimate T3 and the fourth initial oil temperature estimate T4 can be obtained by looking up the tables according to the first pressure cutoff of 8bar, the second pressure cutoff of 9bar, and the average oil pump speed. Based on the absolute value of the difference between the current average clutch pressure and the first pressure cutoff (i.e., |8.3-8|=0.3) and the absolute value of the difference between the average clutch pressure and the second pressure cutoff (i.e., |8.3-9|=0.7), the third initial oil temperature estimate T3 and the fourth initial oil temperature estimate T4 can be linearly interpolated to obtain the second oil temperature estimate T2_est.

[0096] In step S203, the transmission oil temperature is obtained by linear interpolation of the first oil temperature estimate and the second oil temperature estimate based on the size of the transmission throttle orifice.

[0097] In other words, after obtaining the first and second oil temperature estimates, the transmission oil temperature can be calculated by linear interpolation based on the transmission orifice size. Specifically, the transmission oil temperature T_est can be obtained by linear interpolation based on the absolute value of the difference between the current transmission orifice size and the first orifice size breakpoint, and the absolute value of the difference between the current transmission orifice size and the second orifice size breakpoint.

[0098] Furthermore, in some embodiments, after obtaining the transmission oil temperature by linear interpolation of the first oil temperature estimate and the second oil temperature estimate, the method further includes: determining whether the current oil pan stability sensor is in a malfunctioning state; if the current oil pan stability sensor is not in a malfunctioning state, then the current value of the oil pan stability sensor is used as the transmission oil temperature.

[0099] In other words, after linearly interpolating the first and second oil temperature estimates to obtain the transmission oil temperature, the current state of the oil pan stability sensor can be determined. If the current oil pan stability sensor is detected to be in a failed state, the oil temperature is switched from the current resolved value of the oil pan temperature sensor to the most recently valid estimated transmission oil temperature value. If the current oil pan stability sensor is not in a failed state, the current value of the oil pan stability sensor is directly used as the transmission oil temperature.

[0100] In addition, in some embodiments, before acquiring the gearbox throttle orifice size, average clutch pressure, and average oil pump speed of the current hydraulic system, the method further includes: determining whether the current hydraulic system is in a preset steady-state state; if the current hydraulic system is not in a preset steady-state state, then acquiring the gearbox throttle orifice size, average clutch pressure, and average oil pump speed of the current hydraulic system is stopped.

[0101] It should be noted that before obtaining the current transmission throttle orifice size, average clutch pressure, and average oil pump speed of the hydraulic system, it is necessary to determine whether the current hydraulic system is in a preset steady-state state, i.e., whether the pressure is stable. If the current hydraulic system is in a preset steady-state state, the transmission oil temperature can be updated by obtaining the current transmission throttle orifice size, average clutch pressure, and average oil pump speed of the hydraulic system. If the current hydraulic system is not in a preset steady-state state, the acquisition of the current transmission throttle orifice size, average clutch pressure, and average oil pump speed of the hydraulic system is stopped, and the current transmission oil temperature is determined to be invalid. The most recent valid transmission oil temperature is taken as the current transmission oil temperature.

[0102] In summary, this application, by obtaining the current hydraulic system's transmission orifice size, average clutch pressure, and average oil pump speed, can determine first and second oil temperature estimates based on the transmission orifice size and average clutch pressure, and according to the average oil pump speed, from a preset table of pressure-oil temperature-speed relationships corresponding to multiple orifice diameters. Then, based on the transmission orifice size, linear interpolation is performed on the first and second oil temperature estimates to calculate the transmission oil temperature. This method, by utilizing the relationship between measurable physical quantities such as clutch pressure, oil pump speed, and transmission oil temperature in the clutch circuit, can still estimate the transmission oil temperature even after a temperature sensor fails. Furthermore, by identifying the orifice size, the accuracy of the oil temperature estimation is ensured, guaranteeing that clutch pressure control can still operate normally.

[0103] Figure 5 This is a block diagram of a transmission oil temperature estimation device provided in an embodiment of this application.

[0104] like Figure 5 As shown, the transmission oil temperature estimation device 10 includes: an acquisition module 100, a first determination module 200, and a calculation module 300.

[0105] Among them, the acquisition module 100 is used to acquire the current hydraulic system's gearbox throttle orifice size, average clutch pressure, and average oil pump speed.

[0106] The first determining module 200 is used to determine a first oil temperature estimate and a second oil temperature estimate based on the gearbox throttle orifice size and average clutch pressure, according to the average oil pump speed, from a preset table of pressure-oil temperature-speed relationships corresponding to multiple throttle orifice diameters; and

[0107] The calculation module 300 is used to perform linear interpolation calculation on the first oil temperature estimate and the second oil temperature estimate based on the size of the transmission throttle orifice to obtain the transmission oil temperature.

[0108] Furthermore, in some embodiments, the first determining module 200 includes:

[0109] The first determining unit is used to determine the first throttle orifice size cutoff point and the second throttle orifice size cutoff point based on the gearbox throttle orifice size, and to determine the first pressure cutoff point and the second pressure cutoff point based on the average clutch pressure.

[0110] The second determining unit is used to determine a first pressure-oil temperature-speed comparison table and a second pressure-oil temperature-speed comparison table from a preset comparison table of pressure-oil temperature-speed corresponding to multiple throttle orifice diameters based on the first throttle orifice size breakpoint, and to obtain a first initial oil temperature estimate and a second initial oil temperature estimate based on the first pressure breakpoint, the second pressure breakpoint, and the average oil pump speed.

[0111] The calculation unit is used to perform linear interpolation calculation on the first initial oil temperature estimate and the second initial oil temperature estimate based on the absolute value of the difference between the average clutch pressure and the first pressure breakpoint, and the absolute value of the difference between the average clutch pressure and the second pressure breakpoint, to obtain the first oil temperature estimate.

[0112] Furthermore, in some embodiments, after determining the first pressure breakpoint and the second pressure breakpoint based on the average clutch pressure, the first determining unit is further configured to:

[0113] Based on the second throttle orifice size breakpoint, a third pressure-oil temperature-speed comparison table and a fourth pressure-oil temperature-speed comparison table are determined from a preset comparison table of pressure-oil temperature-speed corresponding to multiple throttle orifice diameters. Based on the third pressure-oil temperature-speed comparison table and the fourth pressure-oil temperature-speed comparison table, the third initial oil temperature estimate and the fourth initial oil temperature estimate are obtained according to the first pressure breakpoint, the second pressure breakpoint and the average oil pump speed.

[0114] Based on the absolute value of the difference between the average clutch pressure and the first pressure breakpoint, and the absolute value of the difference between the average clutch pressure and the second pressure breakpoint, the second oil temperature estimate is obtained by linear interpolation of the third and fourth initial oil temperature estimates.

[0115] Furthermore, in some embodiments, the acquisition module 100 is specifically used for:

[0116] Determine the target oil temperature, target clutch pressure, and target oil pump speed;

[0117] Based on the target oil temperature and target clutch pressure, the throttle orifice size of the gearbox is obtained by looking up a table of pressure-oil temperature-speed relationships corresponding to multiple preset throttle orifice diameters, according to the target oil pump speed.

[0118] Furthermore, in some embodiments, before determining the gearbox orifice size by looking up a preset table of pressure-oil temperature-speed relationships corresponding to multiple orifice diameters based on the target oil temperature and target clutch pressure, and according to the target oil pump speed, the method further includes:

[0119] The second determining module is used to determine the diameters of multiple throttling orifices;

[0120] The recording module is used to record the oil temperature at different clutch pressures and different oil pump speeds based on the diameter of each throttle orifice.

[0121] The tabulation module is used to generate a preset table of pressure-oil temperature-speed relationships for multiple throttle orifice diameters, different clutch pressures corresponding to each throttle orifice diameter, and oil temperatures at different oil pump speeds.

[0122] Furthermore, in some embodiments, before obtaining the current hydraulic system's gearbox throttle orifice size, average clutch pressure, and average oil pump speed, the method further includes:

[0123] The judgment module is used to determine whether the current hydraulic system is in a preset steady-state state;

[0124] The control module is used to stop acquiring the gearbox throttle orifice size, average clutch pressure, and average oil pump speed of the current hydraulic system when the current hydraulic system is not in a preset steady-state state.

[0125] Furthermore, in some embodiments, after obtaining the transmission oil temperature by linear interpolation of the first oil temperature estimate and the second oil temperature estimate, the calculation module 300 is further configured to:

[0126] Determine if the current oil pan stability sensor is in a malfunctioning state;

[0127] If the current oil pan stability sensor is not in a faulty state, the current value of the oil pan stability sensor will be used as the transmission oil temperature.

[0128] It should be noted that the foregoing explanation of the transmission oil temperature estimation method embodiment also applies to the transmission oil temperature estimation device of this embodiment, and will not be repeated here.

[0129] In summary, this application, by obtaining the current hydraulic system's transmission orifice size, average clutch pressure, and average oil pump speed, can determine first and second oil temperature estimates based on the transmission orifice size and average clutch pressure, and according to the average oil pump speed, from a preset table of pressure-oil temperature-speed relationships corresponding to multiple orifice diameters. Then, based on the transmission orifice size, linear interpolation is performed on the first and second oil temperature estimates to calculate the transmission oil temperature. This method, by utilizing the relationship between measurable physical quantities such as clutch pressure, oil pump speed, and transmission oil temperature in the clutch circuit, can still estimate the transmission oil temperature even after a temperature sensor fails. Furthermore, by identifying the orifice size, the accuracy of the oil temperature estimation is ensured, guaranteeing that clutch pressure control can still operate normally.

[0130] Figure 6 This is a schematic diagram of a vehicle provided in an embodiment of the present invention. The vehicle may include:

[0131] The memory 601, the processor 602, and the computer program stored on the memory 601 and capable of running on the processor 602.

[0132] When the processor 602 executes the program, it implements the transmission oil temperature estimation method provided in the above embodiments.

[0133] Furthermore, the vehicle also includes:

[0134] Communication interface 603 is used for communication between memory 601 and processor 602.

[0135] The memory 601 is used to store computer programs that can run on the processor 602.

[0136] The memory 601 may include high-speed RAM (Random Access Memory) memory, and may also include non-volatile memory, such as at least one disk storage.

[0137] If the memory 601, processor 602, and communication interface 603 are implemented independently, then the communication interface 603, memory 601, and processor 602 can be interconnected via a bus to complete communication between them. The bus can be an ISA (Industry Standard Architecture) bus, a PCI (Peripheral Component Interconnect) bus, or an EISA (Extended Industry Standard Architecture) bus, etc. The bus can be divided into address bus, data bus, control bus, etc. For ease of representation, Figure 6The bus is represented by a single thick line, but this does not mean that there is only one bus or one type of bus.

[0138] Optionally, in a specific implementation, if the memory 601, processor 602, and communication interface 603 are integrated on a single chip, then the memory 601, processor 602, and communication interface 603 can communicate with each other through an internal interface.

[0139] The processor 602 may be a CPU (Central Processing Unit), an ASIC (Application Specific Integrated Circuit), or one or more integrated circuits configured to implement embodiments of the present invention.

[0140] This invention also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described transmission oil temperature estimation method.

[0141] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0142] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0143] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A method for estimating transmission oil temperature, characterized in that, Includes the following steps: Obtain the current gearbox throttle orifice size, average clutch pressure, and average oil pump speed of the hydraulic system; Based on the gearbox throttle orifice size and the average clutch pressure, the first oil temperature estimate and the second oil temperature estimate are determined from a preset table of pressure-oil temperature-speed relationships corresponding to multiple throttle orifice diameters, according to the average oil pump speed. as well as Based on the size of the transmission throttle orifice, the transmission oil temperature is calculated by linear interpolation of the first oil temperature estimate and the second oil temperature estimate; The step of determining a first oil temperature estimate and a second oil temperature estimate based on the gearbox throttle orifice size and the average clutch pressure, according to the average oil pump speed, from a preset table of pressure-oil temperature-speed relationships corresponding to multiple throttle orifice diameters includes: The first throttle orifice size cutoff point and the second throttle orifice size cutoff point are determined based on the gearbox throttle orifice size, and the first pressure cutoff point and the second pressure cutoff point are determined based on the average clutch pressure. Based on the first throttle orifice size breakpoint, a first pressure-oil temperature-speed reference table and a second pressure-oil temperature-speed reference table are determined from the preset multiple throttle orifice diameter corresponding pressure-oil temperature-speed relationship reference tables. Based on the first pressure-oil temperature-speed reference table and the second pressure-oil temperature-speed reference table, a first initial oil temperature estimate and a second initial oil temperature estimate are obtained according to the first pressure breakpoint, the second pressure breakpoint and the average oil pump speed. Based on the absolute value of the difference between the average clutch pressure and the first pressure breakpoint, and the absolute value of the difference between the average clutch pressure and the second pressure breakpoint, the first initial oil temperature estimate is obtained by linear interpolation of the first initial oil temperature estimate and the second initial oil temperature estimate.

2. The method according to claim 1, characterized in that, After determining the first pressure cutoff point and the second pressure cutoff point based on the average clutch pressure, the method further includes: Based on the second throttle orifice size breakpoint, a third pressure-oil temperature-speed comparison table and a fourth pressure-oil temperature-speed comparison table are determined from the preset multiple throttle orifice diameter corresponding pressure-oil temperature-speed relationship comparison tables. Based on the third pressure-oil temperature-speed comparison table and the fourth pressure-oil temperature-speed comparison table, a third initial oil temperature estimate and a fourth initial oil temperature estimate are obtained according to the first pressure breakpoint, the second pressure breakpoint and the average oil pump speed. Based on the absolute value of the difference between the average clutch pressure and the first pressure breakpoint, and the absolute value of the difference between the average clutch pressure and the second pressure breakpoint, the second oil temperature estimate is obtained by linear interpolation of the third initial oil temperature estimate and the fourth initial oil temperature estimate.

3. The method according to claim 1, characterized in that, The acquisition of the current hydraulic system's gearbox throttle orifice size, average clutch pressure, and average oil pump speed includes: Determine the target oil temperature, target clutch pressure, and target oil pump speed; Based on the target oil temperature and the target clutch pressure, the throttle orifice size of the gearbox is obtained by looking up a table of pressure-oil temperature-speed relationships corresponding to multiple preset throttle orifice diameters according to the target oil pump speed.

4. The method according to claim 3, characterized in that, Before determining the throttle orifice size of the transmission by looking up a table corresponding to the pressure-oil temperature-speed relationship between multiple preset throttle orifice diameters based on the target oil temperature and the target clutch pressure, and according to the target oil pump speed, the process further includes: Determine the diameters of multiple throttling orifices; Based on the diameter of each throttle orifice, the oil temperature was recorded at different clutch pressures and different oil pump speeds. Based on the multiple throttle orifice diameters, the different clutch pressures corresponding to each throttle orifice diameter, and the oil temperatures at different oil pump speeds, a pressure-oil temperature-speed relationship table corresponding to the multiple preset throttle orifice diameters is obtained.

5. The method according to claim 1, characterized in that, Before obtaining the gearbox throttle orifice size, the average clutch pressure, and the average oil pump speed of the current hydraulic system, the following steps are also included: Determine whether the current hydraulic system is in a preset steady-state state; If the current hydraulic system is not in the preset steady state, then the acquisition of the gearbox throttle orifice size, the average clutch pressure, and the average oil pump speed of the current hydraulic system will be stopped.

6. The method according to claim 1, characterized in that, After obtaining the transmission oil temperature by linear interpolation of the first and second oil temperature estimates, the method further includes: Determine if the current oil pan stability sensor is in a malfunctioning state; If the current oil pan stability sensor is not in the failed state, then the value of the current oil pan stability sensor is taken as the transmission oil temperature.

7. A transmission oil temperature estimation device, characterized in that, For implementing the transmission oil temperature estimation method as described in any one of claims 1-6, the apparatus comprises: The acquisition module is used to acquire the current hydraulic system's gearbox throttle orifice size, average clutch pressure, and average oil pump speed. The first determining module is used to determine a first oil temperature estimate and a second oil temperature estimate based on the gearbox throttle orifice size and the average clutch pressure, according to the average oil pump speed, from a preset table of pressure-oil temperature-speed relationships corresponding to multiple throttle orifice diameters; and The calculation module is used to perform linear interpolation calculation on the first oil temperature estimate and the second oil temperature estimate based on the size of the transmission throttle orifice to obtain the transmission oil temperature.

8. A vehicle, characterized in that, include: A memory, a processor, and a computer program stored in the memory and executable on the processor, the processor executing the program to implement the transmission oil temperature estimation method as described in any one of claims 1-6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, The program is executed by the processor to implement the transmission oil temperature estimation method as described in any one of claims 1-6.

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