Temperature estimation method and device, equipment, storage medium and computer program product
By acquiring vehicle data in real time to calculate differential temperature, the problem of increased hardware costs is solved, and accurate estimation and safety monitoring of differential temperature are achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-19
- Publication Date
- 2026-04-03
AI Technical Summary
Existing technologies require additional hardware costs to obtain differential temperature, which is not well accepted by users and cannot effectively monitor differential temperature, thus posing a driving safety risk.
By acquiring the difference in angular velocity between the left and right wheels of the vehicle, the output torque of the motor, and the oil temperature of the reducer in real time, the influence of lubricating oil temperature on gear friction heat generation is corrected using a correction factor, the gear friction heat power is calculated, and the differential temperature is estimated by combining the heat loss.
Without increasing additional hardware costs, the accuracy and reliability of differential temperature estimation have been improved, reducing driving safety risks.
Smart Images
Figure CN121783379A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of vehicle hardware monitoring technology, and in particular to a temperature estimation method, device, equipment, storage medium, and computer program product. Background Technology
[0002] Open differentials are widely used in both gasoline and new energy passenger vehicles due to their simple structure, low cost, and high reliability. However, in scenarios such as continuous slippage on one side of a split-wheel road, high-torque cornering at large steering angles, and 0-100 km / h acceleration, the differential's temperature may rise rapidly due to internal gear friction. This can lead to problems such as lubrication failure, severe gear wear and seizure, broken slotted shafts, abnormal noises, and reduced lifespan and reliability, seriously affecting driving safety. Therefore, monitoring the differential temperature is crucial for driving safety.
[0003] Currently, the traditional method for obtaining differential temperature involves adding a sensor to the differential. While this method is straightforward, it involves disassembling and reassembling vehicle components and adding the sensor hardware, resulting in high installation costs and poor user acceptance. Therefore, there is an urgent need for a method to obtain differential temperature without increasing additional hardware costs. Summary of the Invention
[0004] In view of the above problems, embodiments of the present invention provide a temperature estimation method, apparatus, device, storage medium, and computer program product to solve the technical problem that traditional methods cannot obtain differential temperature without increasing additional hardware costs.
[0005] According to one aspect of the present invention, a temperature estimation method is provided, the method comprising: Real-time acquisition of the difference in angular velocity between the left and right wheels of the vehicle, the output torque of the motor, and the oil temperature of the reducer; A correction factor is determined based on the reducer oil temperature. The correction factor is used to correct the effect of the lubricating oil temperature in the differential of the vehicle on the frictional heat generated by the gears. The gear friction heat power of the differential is calculated based on the difference in angular velocity between the left and right wheels, the output torque of the motor, and the correction factor. The differential temperature is estimated based on the frictional heat power of the gears and the heat loss of the differential.
[0006] In one alternative approach, the step of determining the correction factor based on the reducer oil temperature includes: When the reducer oil temperature is lower than the first preset temperature, a correction factor is determined based on the temperature difference between the reducer oil temperature and the first preset temperature; When the reducer oil temperature is greater than the second preset temperature, a correction factor is determined based on the temperature difference between the reducer oil temperature and the second preset temperature; When the reducer oil temperature is greater than or equal to the first preset temperature and less than or equal to the second preset temperature, the correction factor is set to a preset constant.
[0007] In one alternative approach, the step of calculating the gear friction heat power of the differential based on the difference in angular velocity between the left and right wheels, the output torque of the motor, and the correction factor includes: Obtain the bench calibration coefficients and reducer ratio of the vehicle, wherein the bench calibration coefficients represent the reference heating gain caused by the inherent physical characteristics of the differential under the target lubrication condition; The differential gear friction heat power is obtained by multiplying the test bench calibration coefficient, the reducer speed ratio, the difference in angular velocity between the left and right wheels, the motor output torque, and the correction factor.
[0008] In one alternative embodiment, prior to the step of estimating the differential temperature based on the gear frictional heat power and the differential's heat loss, the method further includes: Determine the thermal resistance between the gears and the lubricating oil in the differential, as well as the gear temperature and reducer oil temperature at the previous moment. The heat loss of the differential is calculated based on the thermal resistance, the gear temperature at the previous moment, and the reducer oil temperature at the previous moment.
[0009] In one alternative approach, the step of estimating the differential temperature based on the gear frictional heat power and the differential's heat loss includes: Determine the time interval between the previous moment and the current moment, and the equivalent heat capacity of the gears in the differential; The differential temperature is estimated based on the gear temperature at the previous moment, the interval time, the equivalent heat capacity, the gear frictional heat power, and the heat loss.
[0010] In an alternative embodiment, after the step of estimating the differential temperature based on the gear frictional heat power and the differential's heat loss, the method further includes: The real-time operating conditions of the vehicle are determined based on the vehicle steering angle, the difference in angular velocity between the left and right wheels, and the output torque of the motor. A target strategy corresponding to the real-time operating conditions and the differential temperature is determined, and the target strategy is executed to protect the differential.
[0011] According to another aspect of the present invention, a temperature estimation device is provided, comprising: The real-time signal acquisition module is used to acquire the difference in angular velocity between the left and right wheels of the vehicle, the output torque of the motor, and the oil temperature of the reducer in real time. The correction factor determination module is used to determine a correction factor based on the reducer oil temperature. The correction factor is used to correct the effect of the lubricating oil temperature in the differential of the vehicle on the frictional heat generated by the gears. The power calculation module is used to calculate the gear friction heat power of the differential based on the difference in angular velocity between the left and right wheels, the output torque of the motor, and the correction factor. The temperature estimation module is used to estimate the differential temperature based on the frictional heat power of the gears and the heat loss of the differential.
[0012] According to another aspect of the present invention, a temperature estimation device is provided, comprising: a processor, a memory, a communication interface, and a communication bus, wherein the processor, the memory, and the communication interface communicate with each other through the communication bus; The memory is used to store at least one executable instruction that causes the processor to perform the temperature estimation method described above.
[0013] According to another aspect of the present invention, a storage medium is provided, wherein at least one executable instruction is stored therein, which, when executed on a temperature estimation device / apparatus, causes the temperature estimation device / apparatus to perform the operation of the temperature estimation method as described above.
[0014] According to another aspect of the present invention, a computer program product is provided, the computer program product including a temperature estimation program, which, when executed by a processor, implements the operation of the temperature estimation method as described above.
[0015] The temperature estimation method provided in this invention acquires the angular velocity difference between the left and right wheels of a vehicle, the output torque of the motor, and the reducer oil temperature in real time. A correction factor is determined based on the reducer oil temperature, which corrects for the influence of the lubricating oil temperature in the vehicle's differential on gear friction heating. The gear friction heat power of the differential is calculated based on the left and right wheel angular velocity difference, the motor output torque, and the correction factor. The differential temperature is estimated based on the gear friction heat power and the differential's heat loss. This method improves the physical accuracy of temperature estimation by correcting the influence of the lubricating oil temperature in the vehicle's differential on gear friction heating through a correction factor. It also determines the gear friction heat power and heat loss of the differential by combining the thermal balance relationship between differential heating and cooling. Therefore, without increasing additional hardware costs, a reliable estimation of the differential temperature is achieved based on the gear friction heat power and heat loss.
[0016] The above description is merely an overview of the technical solutions of the embodiments of the present invention. In order to better understand the technical means of the embodiments of the present invention and to implement them in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the embodiments of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description
[0017] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 A flowchart illustrating a first embodiment of the temperature estimation method provided by the present invention is shown; Figure 2 A flowchart illustrating a second embodiment of the temperature estimation method provided by the present invention is shown; Figure 3 This diagram illustrates the piecewise function of the correction factor in the temperature estimation method provided by the present invention. Figure 4 A flowchart illustrating a third embodiment of the temperature estimation method provided by the present invention is shown; Figure 5 A schematic diagram of the structure of a first embodiment of the temperature estimation device provided by the present invention is shown; Figure 6 A schematic diagram of an embodiment of the temperature estimation device provided by the present invention is shown.
[0018] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation
[0019] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein.
[0020] refer to Figure 1 , Figure 1 A flowchart illustrating a first embodiment of the temperature estimation method provided by the present invention is shown, the method being executed by a temperature estimation device. Figure 1 As shown, this temperature estimation method includes the following steps: Step S10: Real-time acquisition of the difference in angular velocity between the left and right wheels of the vehicle, the output torque of the motor, and the oil temperature of the reducer.
[0021] It should be noted that the execution subject of the method in this embodiment can be a terminal device with data processing, temperature estimation, and program execution functions, or it can be an electronic device with the same or similar functions, such as the temperature estimation device mentioned above. The following uses a temperature estimation device as an example to specifically describe the temperature estimation methods provided in this embodiment and the following embodiments.
[0022] It should be noted that the aforementioned difference in left and right wheel angular velocities represents the difference in rotational angular velocity between the left and right tires at the front / rear of the vehicle, which can be written as |Δω|, in rad / s (radians per second). Further, assuming the left and right wheel speed sensor signals are WhlSpdRiFrntData and WhlSpdLeFrntData respectively, and the vehicle's tire radius is r, the aforementioned difference in left and right wheel angular velocities can be calculated as |Δω| = |WhlSpdRiFrntData - WhlSpdLeFrntData| / r. The aforementioned motor output torque can be obtained by acquiring the actual torque signal output by the vehicle's motor control, which can be written as T_motor, in N·m (Newton-meter). The aforementioned reducer oil temperature can be obtained by acquiring the signal output by the oil temperature sensor, which can be written as T_oil, in ℃ (degrees Celsius); additionally, if the vehicle is not equipped with an oil temperature sensor, the estimated value modeled by the NTC (Negative Temperature Coefficient) temperature sensor on the stator winding of the electric drive system can be used.
[0023] Step S20: Determine a correction factor based on the reducer oil temperature. The correction factor is used to correct the effect of the lubricating oil temperature in the differential of the vehicle on the frictional heat generated by the gears.
[0024] It should be understood that the above correction factor f_μ(T_oil) is a dimensionless gain factor used to correct the effect of lubricating oil temperature on the friction coefficient μ of the gears inside the differential (μ can affect the frictional heat generation of the gears) and varies with the reducer oil temperature T_oil.
[0025] In one alternative approach, correction factors can be pre-calibrated on a test bench, ranging from the lowest oil temperature (e.g., -20℃) to the highest oil temperature (e.g., 140℃), with increments of 1℃. Linear interpolation is then performed between the calibration points to create a one-dimensional table. After obtaining the aforementioned reducer oil temperature, a lookup is performed in the one-dimensional table based on the reducer oil temperature to obtain the correction factor corresponding to that temperature.
[0026] Step S30: Calculate the gear friction heat power of the differential based on the difference in angular velocity between the left and right wheels, the output torque of the motor, and the correction factor.
[0027] It should be understood that the above-mentioned gear frictional heat power can be written as P_heat, with the unit being W (watts).
[0028] In practical applications, the instantaneous heat power generated by meshing friction of the gears inside the differential can be analyzed based on the difference in angular velocity between the left and right wheels, the output torque of the motor, and the correction factor, thereby obtaining the gear friction heat power of the differential.
[0029] Step S40: Estimate the differential temperature based on the frictional heat power of the gears and the heat loss of the differential.
[0030] It should be understood that the heat dissipation of the differential housing is almost negligible; cooling is primarily achieved through internal lubricating oil churning and splashing or active oil injection. Specifically, although the metal housing itself is thermally conductive, its heat exchange area with the outside is limited, and it is usually in contact with air (air has very poor thermal conductivity). Therefore, the efficiency of heat dissipation through natural convection and radiation from the housing is very low and can be ignored in dynamic thermal balance calculations. Churning and splashing refers to the agitation of the oil as the gears rotate, causing it to splash and cover the gears and the inner walls of the housing. This is equivalent to forced convective heat exchange between the oil and the heat source (gears) and the intermediate heat dissipation surface (the inner walls of the housing). Active oil injection means that cooled oil can be directly sprayed onto high-temperature areas such as gear meshing via an oil pump for directional forced cooling. The lubricating oil first absorbs the frictional heat from the gears, then transfers the heat to the housing through its flow and contact with the relatively large inner walls of the housing, ultimately dissipating it into the outside air. Therefore, the heat dissipation capacity mainly depends on the thermal properties of the lubricating oil, its flow rate, and its heat exchange efficiency with the gears and housing.
[0031] The temperature estimation method provided in this embodiment acquires the angular velocity difference between the left and right wheels of the vehicle, the motor output torque, and the reducer oil temperature in real time. A correction factor is determined based on the reducer oil temperature, which corrects for the impact of the lubricating oil temperature in the vehicle's differential on gear friction heating. The gear friction heat power of the differential is calculated based on the left and right wheel angular velocity difference, the motor output torque, and the correction factor. The differential temperature is estimated based on the gear friction heat power and the differential's heat loss. This embodiment improves the physical accuracy of temperature estimation by correcting the impact of the lubricating oil temperature in the vehicle's differential on gear friction heating through a correction factor. Furthermore, it determines the gear friction heat power and heat loss of the differential by combining the thermal balance relationship between differential heating and cooling. Thus, without increasing additional hardware costs, a reliable estimation of the differential temperature is achieved based on the gear friction heat power and heat loss.
[0032] refer to Figure 2 , Figure 2 A flowchart illustrating a second embodiment of the temperature estimation method of the present invention is shown, the method being executed by a temperature estimation device. Figure 2As shown, in this embodiment, step S20 includes: Step S201: When the reducer oil temperature is lower than the first preset temperature, a correction factor is determined based on the temperature difference between the reducer oil temperature and the first preset temperature.
[0033] It should be noted that the aforementioned first preset temperature can be written as T_low, which represents the lower threshold of the ideal lubrication temperature range for the differential. The ideal lubrication temperature range refers to the operating temperature range within which the reducer lubricating oil can form a stable and effective lubricating film, thereby maintaining the friction coefficient of the gears inside the differential at its lowest and most stable level.
[0034] It should be understood that when the reducer oil temperature is lower than the first preset temperature, it indicates that the lubricating oil temperature in the differential is too low, its viscosity increases, its fluidity decreases, and it is difficult to form a uniform and effective lubricating oil film. This causes the gears to be in a boundary lubrication state, and the coefficient of friction will increase. Therefore, the correction factor can be determined based on the following formula: f_μ(T_oil) = A * exp{(T_low - T_oil) / τ1}; Where f_μ(T_oil) represents the correction factor, A represents the friction correction amplitude coefficient in the low-temperature zone, T_low represents the first preset temperature, T_oil represents the reducer oil temperature, and τ1 represents the temperature sensitivity coefficient in the low-temperature zone. Further, A represents the degree of basic friction deterioration caused by poor lubrication at the starting point of the low-temperature zone (i.e., when T_oil is just below T_low). This can be understood as a benchmark multiple by which the friction coefficient needs to be amplified relative to the ideal lubrication state at the low-temperature boundary. The larger A is, the higher the benchmark level of friction coefficient increase due to lubrication deterioration under the same low-temperature conditions, resulting in a larger calculated frictional heat power. τ1 quantifies the rate or sensitivity of friction coefficient deterioration as oil temperature further decreases. It reflects the response characteristics of lubricating oil viscosity to temperature changes: the smaller τ1 is, the more sensitive the lubricating oil viscosity is to temperature; as temperature decreases, viscosity increases more easily, resulting in a larger calculated frictional heat power.
[0035] Step S202: When the reducer oil temperature is greater than the second preset temperature, a correction factor is determined based on the temperature difference between the reducer oil temperature and the second preset temperature.
[0036] It should be noted that the second preset temperature mentioned above can be written as T_high, which represents the upper threshold of the ideal lubrication temperature range of the differential.
[0037] It should be understood that when the reducer oil temperature exceeds the second preset temperature, it indicates that the lubricating oil temperature in the differential is too high, its viscosity decreases, the oil film thins and its strength reduces, and oxidation or decomposition may even occur, leading to lubrication failure and an increase in the coefficient of friction. Therefore, the correction factor can be determined based on the following formula: f_μ(T_oil)=B * exp{ (T_oil-T_high) / τ2}; Where f_μ(T_oil) represents the correction factor, B represents the friction correction amplitude coefficient in the high-temperature zone, T_high represents the second preset temperature, T_oil represents the reducer oil temperature, and τ2 represents the temperature sensitivity coefficient in the high-temperature zone. Further, B represents the degree of basic friction amplification caused by lubrication deterioration at the starting point of the high-temperature zone (i.e., when T_oil just exceeds T_high). This can be understood as a benchmark multiple by which the friction coefficient needs to be amplified relative to the ideal lubrication state at the high-temperature boundary. The larger B is, the higher the benchmark level of friction coefficient amplification due to the thinning or deterioration of the oil film when entering the high-temperature zone, resulting in a correspondingly larger calculated frictional heat power. τ2 quantifies the rate or sensitivity of friction coefficient deterioration as oil temperature further increases, reflecting the characteristics of lubricant performance degradation at high temperatures: the smaller τ2 is, the more sensitive the lubricant's oil film strength or shear resistance is to temperature; as temperature increases, lubrication performance decreases, leading to a larger calculated frictional heat power.
[0038] Step S203: When the reducer oil temperature is greater than or equal to the first preset temperature and less than or equal to the second preset temperature, the correction factor is set to a preset constant.
[0039] It should be understood that when the reducer oil temperature is greater than or equal to the first preset temperature and less than or equal to the second preset temperature, it indicates that the lubricating oil in the differential is in its optimal operating temperature range, with moderate viscosity, capable of forming a stable and effective hydrodynamic lubrication film, and exhibiting a low and relatively stable coefficient of friction. Therefore, the correction factor can be set to a preset constant (which can be represented by C), for example, C=1.
[0040] Specifically, A, B, C, T_low, T_high, τ1, and τ2 can all be obtained through data fitting from bench tests. Please refer to [reference needed]. Figure 3 , Figure 3 A schematic diagram of the piecewise function of the correction factor in the temperature estimation method provided by this invention is shown. Figure 3 In the diagram, the horizontal axis represents the lubricating oil temperature (i.e., the reducer oil temperature mentioned above), and the vertical axis represents the friction coefficient correction factor (i.e., the correction factor mentioned above). For example, Figure 3The following values are given: A=2.5, B=1.8, C=1.0, T_low=40℃, T_high=100℃, τ1=20, τ2=30. In this example, the range where the reducer oil temperature is less than 40℃ is the low-temperature oil film rupture zone (i.e., the low-temperature zone), the range where the reducer oil temperature is greater than 100℃ is the high-temperature oil film rupture zone (i.e., the high-temperature zone), and the range where the reducer oil temperature is greater than or equal to 40℃ and less than or equal to 100℃ is the ideal lubrication zone (i.e., within this range, the differential is in an ideal lubrication state).
[0041] In an alternative approach, step S30 may include: Step S301: Obtain the bench calibration coefficient and reducer ratio of the vehicle. The bench calibration coefficient represents the reference heating gain caused by the inherent physical characteristics of the differential under the target lubrication condition.
[0042] It should be noted that the above-mentioned test bench calibration coefficient can be represented by β; the above-mentioned reducer speed ratio, i.e., the transmission ratio of the reducer, can be represented by α.
[0043] It should be understood that, theoretically, frictional work can be calculated based on torque and speed difference, but not all frictional work is 100% converted into heat energy that raises the temperature of the gears. Actual heat generation is also affected by factors inherent to the differential itself, such as gear efficiency (mechanical losses during gear meshing), geometric and surface characteristics (gear tooth profile, machining accuracy, surface roughness), and assembly and preload (additional friction caused by bearing preload, gear backlash, etc.). These inherent factors collectively constitute the inherent physical characteristics of a specific differential model, independent of lubrication conditions. β is the quantification of the baseline heat generation level caused by these complex and theoretically difficult-to-calculate inherent physical characteristics.
[0044] Specifically, the aforementioned target lubrication state is the ideal lubrication state. This means that when calibrating β in bench tests, the lubricating oil temperature needs to be controlled within the range of greater than or equal to T_low and less than or equal to T_high, where the correction factor is 1. Under these conditions, the differences in heat generation data primarily stem from the inherent physical characteristics of the differential itself, rather than changes in lubrication conditions. By fitting the data, the β value for that specific differential can be obtained.
[0045] Step S302: Multiply the test bench calibration coefficient, the reducer speed ratio, the difference in angular velocity between the left and right wheels, the motor output torque, and the correction factor to obtain the gear friction heat power of the differential.
[0046] It should be understood that the above-mentioned gear frictional heat power can be calculated based on the following formula: P_heat=β*α*T_motor*|Δω|*f_μ(T_oil); Where P_heat represents the gear friction heat power, β represents the bench calibration coefficient, α represents the reducer speed ratio, T_motor represents the motor output torque, |Δω| represents the difference in angular velocity between the left and right wheels, and f_μ(T_oil) represents the correction factor.
[0047] The temperature estimation method provided in this embodiment determines a correction factor based on the temperature difference between the reducer oil temperature and the first preset temperature when the reducer oil temperature is lower than the first preset temperature; it also determines a correction factor based on the temperature difference between the reducer oil temperature and the second preset temperature when the reducer oil temperature is higher than the second preset temperature; and it sets the correction factor to a preset constant when the reducer oil temperature is greater than or equal to the first preset temperature and less than or equal to the second preset temperature. The method obtains the vehicle's bench calibration coefficient and reducer ratio, where the bench calibration coefficient represents the reference heating gain caused by the inherent physical characteristics of the differential under the target lubrication state. The method multiplies the bench calibration coefficient, the reducer ratio, the difference in angular velocity between the left and right wheels, the motor output torque, and the correction factor to obtain the gear friction heat power of the differential. This embodiment determines the correction factor based on the magnitude of the reducer oil temperature, ensuring the accuracy of the correction factor at different temperatures, thereby providing reliable compensation parameters for calculating gear friction heat power. Meanwhile, this embodiment introduces the following variables: the motor output torque and wheel speed difference together constitute the basis of frictional work; the reducer speed ratio reflects the amplification effect of the transmission system on torque; the bench calibration coefficient introduces the inherent thermal characteristics of the differential itself under ideal lubrication conditions; and the correction factor modulates the influence of lubrication conditions. Therefore, based on the above variables, the gear frictional heat power of the differential can be accurately calculated.
[0048] refer to Figure 4 , Figure 4 A flowchart illustrating a third embodiment of the temperature estimation method provided by the present invention is shown, the method being executed by a temperature estimation device. Figure 4 As shown, in this embodiment, before step S40, the following steps are also included: Step S31: Determine the thermal resistance between the gear and the lubricating oil in the differential, as well as the gear temperature and reducer oil temperature at the previous moment.
[0049] It's important to note that the thermal resistance between the gears and the lubricating oil can be expressed as R_gearo, with units of °C / W (degrees Celsius per watt). This represents the temperature difference in degrees Celsius that needs to be overcome to transfer 1 watt of heat power between the gears and the lubricating oil. Therefore, a higher thermal resistance means a larger temperature difference is required to transfer the same amount of heat, making heat dissipation more difficult; conversely, a lower thermal resistance makes heat dissipation easier. Thermal resistance can be obtained through bench calibration or by consulting the differential's product performance parameters.
[0050] Step S32: Calculate the heat loss of the differential based on the thermal resistance, the gear temperature at the previous moment, and the reducer oil temperature at the previous moment.
[0051] In practical implementation, the above heat loss can be calculated based on the following formula: P_cool(k)=[T_gear_(k-1)-T_oil(k-1)] / R_gearo; Where P_cool(k) represents the heat loss of the differential at time k (i.e., the current time), T_gear_(k-1) represents the gear temperature at the previous time, T_oil(k-1) represents the reducer oil temperature at the previous time, and R_gearo represents the thermal resistance between the gear and the lubricating oil in the differential.
[0052] In an alternative embodiment, step S40 includes: Step S401: Determine the time interval between the previous moment and the current moment, and the equivalent heat capacity of the gears in the differential.
[0053] It should be understood that the equivalent heat capacity of the gears in a differential can be expressed as C_gear, with units of J / ℃ (joules per degree Celsius). This represents the amount of heat absorbed by the differential gears to raise their temperature by 1°C. The equivalent heat capacity can be obtained through bench calibration or by consulting the differential's product performance parameters.
[0054] Step S402: Estimate the differential temperature based on the gear temperature at the previous moment, the interval time, the equivalent heat capacity, the gear frictional heat power, and the heat loss.
[0055] In practical implementation, since the gear meshing temperature is generally the highest within the differential, and differential malfunctions are usually caused by gear-related issues, the gear meshing temperature can be used as the differential temperature in this embodiment. Specifically, the differential temperature can be calculated based on the following formula: T_gear_(k)=T_gear_(k-1)+Δt*[P_heat(k)-P_cool(k)] / C_gear; Where T_gear_(k) represents the gear meshing temperature (i.e., differential temperature) at time k (i.e., the current time), T_gear_(k-1) represents the gear meshing temperature (i.e., gear temperature) at time k-1 (i.e., the previous time), Δt represents the interval time (i.e., the time difference between k and k-1), P_heat(k) represents the gear friction heat power at time k, P_cool(k) represents the heat loss at time k, and C_gear represents the equivalent heat capacity of the gears in the differential.
[0056] In an alternative embodiment, after step S40, the method further includes: Step S50: Determine the real-time operating conditions of the vehicle based on the vehicle steering angle, the difference in angular velocity between the left and right wheels, and the output torque of the motor.
[0057] It should be noted that the above-mentioned vehicle steering angle can be obtained by collecting the steering angle signal output by the vehicle's ESP (Electronic Stability Program), which can be written as δ and the unit is ° (degree).
[0058] It should be understood that the following examples provide three real-time operating conditions. More relevant operating conditions can be set according to actual conditions, and this embodiment does not impose any limitations. When the steering angle δ is extremely small and |Δω| is relatively large, it indicates that the vehicle's real-time operating condition is Condition 1: almost straight driving but one side of the wheel is slipping severely, the differential temperature rise rate will be high, and there is a risk of overheating. When δ is extremely large, |Δω| is extremely large, and T_motor is extremely large, it indicates that the vehicle's real-time operating condition is Condition 2: the vehicle is in extreme operating conditions such as sharp bends and hill climbs, extreme extrication, etc., and is very likely to overheat. When δ is relatively large, |Δω| is relatively small, and T_motor is moderate, it indicates that the vehicle's real-time operating condition is Condition 3: the vehicle is in a normal cornering condition, and the risk of overheating is relatively small.
[0059] Specifically, |δ| < 10° is considered "minimum", 10° ≤ |δ| ≤ 30° is considered "relatively large", and |δ| > 30° is considered "extremely large". The maximum steering angle is determined based on the vehicle's actual design parameters, and currently, the vast majority of vehicles do not exceed 40°. |Δω| < 1.5 rad / s is considered "minimum", 1.5 rad / s ≤ |Δω| < 16 rad / s is considered "relatively small", 16 rad / s ≤ |Δω| < 31 rad / s is considered "relatively large", and |Δω| ≥ 31 rad / s is considered "extremely large". The driving torque |T_motor| < 0.3 × T_max is considered "relatively small", 0.3 × T_max ≤ |T_motor| ≤ 0.7 × T_max is considered "moderate", |T_motor| > 0.7 × T_max is considered "relatively large", and |T_motor| > 0.9 × T_max is considered "extremely large". T_max represents the maximum torque that the vehicle's motor can output.
[0060] Step S60: Determine a target strategy corresponding to the real-time operating conditions and the differential temperature, and execute the target strategy to protect the differential.
[0061] In one alternative approach, the estimated differential temperature T can be set to three thresholds: T < 110℃ is considered normal temperature, 110℃ ≤ T < 140℃ is considered high temperature, and T ≥ 140℃ is considered overheating temperature. Then, a combination of pattern recognition and real-time temperature estimation is applied to take different measures for different differential temperatures under different real-time operating conditions. A time hysteresis loop is set to avoid malfunctions. The protection strategy can only be activated after temperature risks are detected in multiple consecutive detection cycles, and an instrument alert will be issued. Specifically, the target strategy corresponding to the real-time operating conditions and differential temperature can be determined by referring to Table 1 below.
[0062]
[0063] Table 1 For example, assuming that the real-time operating condition is condition 1 for three consecutive cycles and the differential temperature T is relatively high, the corresponding target strategy can be determined as moderate torque reduction, which means reducing the output torque of the vehicle's motor.
[0064] The temperature estimation method provided in this embodiment determines the thermal resistance between the gears and lubricating oil in the differential, as well as the gear temperature and reducer oil temperature at the previous moment; calculates the heat loss of the differential based on the thermal resistance, the previous gear temperature, and the previous reducer oil temperature; determines the interval between the previous moment and the current moment, as well as the equivalent heat capacity of the gears in the differential; estimates the differential temperature based on the previous gear temperature, the interval, the equivalent heat capacity, the gear frictional heat power, and the heat loss; determines the real-time operating condition of the vehicle based on the vehicle steering angle, the difference in angular velocity between the left and right wheels, and the motor output torque; determines a target strategy corresponding to the real-time operating condition and the differential temperature, and executes the target strategy to protect the differential. This embodiment accurately calculates the differential heat loss by determining the thermal resistance between the gears and lubricating oil and the previous gear and oil temperatures, thereby dynamically evaluating the heat dissipation status and accurately reflecting the current heat dissipation efficiency of the differential. Meanwhile, this embodiment also achieves dynamic estimation of the differential's current temperature by determining the time interval and the equivalent heat capacity of the gears, combined with the gear temperature, frictional heat power, and heat loss at the previous moment. The time interval ensures the temporal continuity of temperature changes, and the equivalent heat capacity reflects the physical characteristics of the gear material's heat absorption / dissipation. These two factors, together with frictional heat power (characterizing the rate of heat generation) and heat loss (characterizing the rate of heat dissipation), constitute energy conservation, thus eliminating the need for additional sensors to estimate the differential temperature. Furthermore, this embodiment combines the vehicle's steering angle, the difference in angular velocity between the left and right wheels, and the motor's output torque to accurately identify the vehicle's real-time operating conditions. Based on these operating parameters and the real-time estimated differential temperature, the system can dynamically match corresponding protection strategies to achieve graded protection, thereby improving the differential's reliability in complex scenarios.
[0065] Reference Figure 5 , Figure 5 A schematic diagram of the structure of a first embodiment of the temperature estimation device provided by the present invention is shown.
[0066] like Figure 5 As shown, the temperature estimation device 500 proposed in this embodiment of the invention includes: The real-time signal acquisition module 501 is used to acquire the difference in angular velocity between the left and right wheels of the vehicle, the output torque of the motor, and the oil temperature of the reducer in real time. The correction factor determination module 502 is used to determine a correction factor based on the reducer oil temperature. The correction factor is used to correct the effect of the lubricating oil temperature in the differential of the vehicle on the frictional heating of the gears. The power calculation module 503 is used to calculate the gear friction heat power of the differential based on the difference in angular velocity between the left and right wheels, the output torque of the motor, and the correction factor. Temperature estimation module 504 is used to estimate the temperature of the differential based on the frictional heat power of the gear and the heat loss of the differential.
[0067] In an optional embodiment, the correction factor determination module 502 is further configured to: determine a correction factor based on the temperature difference between the reducer oil temperature and the first preset temperature when the reducer oil temperature is lower than the first preset temperature; determine a correction factor based on the temperature difference between the reducer oil temperature and the second preset temperature when the reducer oil temperature is higher than the second preset temperature; and set the correction factor to a preset constant when the reducer oil temperature is greater than or equal to the first preset temperature and less than or equal to the second preset temperature.
[0068] In an optional manner, the power calculation module 503 is further configured to obtain the test calibration coefficient and reducer ratio of the vehicle, wherein the test calibration coefficient represents the reference heating gain caused by the inherent physical characteristics of the differential under the target lubrication state; and to obtain the gear friction heat power of the differential by multiplying the test calibration coefficient, the reducer ratio, the difference in angular velocity between the left and right wheels, the output torque of the motor and the correction factor.
[0069] In an alternative embodiment, the temperature estimation module 504 is further configured to determine the thermal resistance between the gear and the lubricating oil in the differential, as well as the gear temperature and the reducer oil temperature at the previous moment; and to calculate the heat loss of the differential based on the thermal resistance, the gear temperature at the previous moment, and the reducer oil temperature at the previous moment.
[0070] In an alternative embodiment, the temperature estimation module 504 is further configured to determine the interval between the previous moment and the current moment, and the equivalent heat capacity of the gears in the differential; and to estimate the differential temperature based on the gear temperature at the previous moment, the interval, the equivalent heat capacity, the gear frictional heat power, and the heat loss.
[0071] In an alternative embodiment, the temperature estimation module 504 is further configured to determine the real-time operating condition of the vehicle based on the vehicle steering angle, the difference in angular velocity between the left and right wheels, and the output torque of the motor; determine a target strategy corresponding to the real-time operating condition and the differential temperature; and execute the target strategy to protect the differential.
[0072] As described above, the temperature estimation method provided in this embodiment acquires the angular velocity difference between the left and right wheels of the vehicle, the motor output torque, and the reducer oil temperature in real time; determines a correction factor based on the reducer oil temperature, which is used to correct the influence of the lubricating oil temperature in the vehicle's differential on gear friction heating; calculates the gear friction heat power of the differential based on the left and right wheel angular velocity difference, the motor output torque, and the correction factor; and estimates the differential temperature based on the gear friction heat power and the differential's heat loss. This embodiment improves the physical accuracy of temperature estimation by correcting the influence of the lubricating oil temperature in the vehicle's differential on gear friction heating through a correction factor. It also determines the gear friction heat power and heat loss of the differential by combining the thermal balance relationship between differential heating and cooling, thereby achieving reliable estimation of the differential temperature based on gear friction heat power and heat loss without increasing additional hardware costs.
[0073] Reference Figure 6 , Figure 6 The diagram shows a structural schematic of an embodiment of the temperature estimation device provided by the present invention. The specific embodiments of the present invention do not limit the specific implementation of the temperature estimation device.
[0074] like Figure 6 As shown, the temperature estimation device may include: a processor 1001, a communications interface 1002, a memory 1003, and a communications bus 1004.
[0075] The processor 1001, communication interface 1002, and memory 1003 communicate with each other via communication bus 1004. Communication interface 1002 is used to communicate with other network elements such as clients or other servers. The processor 1001 executes program 1005, specifically performing the relevant steps described above in the temperature estimation method embodiment.
[0076] Specifically, program 1005 may include program code, which includes computer-executable instructions.
[0077] The processor 1001 may be a central processing unit (CPU), an application-specific integrated circuit (ASIC), or one or more integrated circuits configured to implement embodiments of the present invention. The temperature estimation device includes one or more processors, which may be processors of the same type, such as one or more CPUs; or processors of different types, such as one or more CPUs and one or more ASICs.
[0078] Memory 1003 is used to store program 1005. Memory 1003 may include high-speed RAM memory, and may also include non-volatile memory, such as at least one disk storage device.
[0079] Specifically, program 1005 can be called by processor 1001 to cause the temperature estimation device to perform the following operations: The system acquires the angular velocity difference between the left and right wheels of the vehicle, the output torque of the motor, and the oil temperature of the reducer in real time; it determines a correction factor based on the reducer oil temperature, which is used to correct the effect of the lubricating oil temperature in the differential of the vehicle on the frictional heat generation of the gears; it calculates the gear frictional heat power of the differential based on the angular velocity difference between the left and right wheels, the output torque of the motor, and the correction factor; and it estimates the differential temperature based on the gear frictional heat power and the heat loss of the differential.
[0080] As can be seen from the above, the temperature estimation device corrects the influence of the lubricating oil temperature in the vehicle's differential on the gear friction heat generation by using a correction factor, thereby improving the physical accuracy of the temperature estimation. It also determines the gear friction heat power and heat loss of the differential by combining the heat balance relationship between differential heat generation and heat dissipation. Thus, without increasing the additional hardware cost, it can reliably estimate the differential temperature based on the gear friction heat power and heat loss.
[0081] This invention also provides a computer-readable storage medium storing at least one executable instruction that, when executed on a temperature estimation device / apparatus, causes the temperature estimation device / apparatus to perform the temperature estimation method described in any of the above method embodiments.
[0082] The algorithms or displays provided herein are not inherently related to any particular computer, virtual system, or other device. Furthermore, the embodiments of this invention are not directed to any particular programming language.
[0083] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of the invention may be practiced without these specific details. Similarly, for the sake of brevity and to aid in understanding one or more aspects of the invention, in the description of exemplary embodiments of the invention above, various features of the embodiments are sometimes grouped together in a single embodiment, figure, or description thereof. The claims, which follow the detailed description, are hereby expressly incorporated into that detailed description, wherein each claim itself is a separate embodiment of the invention.
[0084] Those skilled in the art will understand that the modules in the device of the embodiment can be adaptively changed and placed in one or more devices different from that embodiment. Modules, units, or components in the embodiment can be combined into a single module, unit, or component, and further, they can be divided into multiple sub-modules, sub-units, or sub-components, except that at least some of such features and / or processes or units are mutually exclusive.
[0085] It should be noted that the above embodiments are illustrative of the invention and not restrictive, and that those skilled in the art can devise alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses should not be construed as limiting the claims. The word "comprising" does not exclude the presence of elements or steps not listed in the claims. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention can be implemented by means of hardware comprising several different elements and by means of a suitably programmed computer. In the unit claims enumerating several means, several of these means may be embodied by the same item of hardware. The use of the words first, second, and third, etc., does not indicate any order. These words can be interpreted as names. The steps in the above embodiments, unless otherwise specified, should not be construed as limiting the order of execution.
Claims
1. A temperature estimation method, characterized in that, The method includes the following steps: Real-time acquisition of the difference in angular velocity between the left and right wheels of the vehicle, the output torque of the motor, and the oil temperature of the reducer; A correction factor is determined based on the reducer oil temperature. The correction factor is used to correct the effect of the lubricating oil temperature in the differential of the vehicle on the frictional heat generated by the gears. The gear friction heat power of the differential is calculated based on the difference in angular velocity between the left and right wheels, the output torque of the motor, and the correction factor. The differential temperature is estimated based on the frictional heat power of the gears and the heat loss of the differential.
2. The temperature estimation method as described in claim 1, characterized in that, The step of determining the correction factor based on the reducer oil temperature includes: When the reducer oil temperature is lower than the first preset temperature, a correction factor is determined based on the temperature difference between the reducer oil temperature and the first preset temperature; When the reducer oil temperature is greater than the second preset temperature, a correction factor is determined based on the temperature difference between the reducer oil temperature and the second preset temperature; When the reducer oil temperature is greater than or equal to the first preset temperature and less than or equal to the second preset temperature, the correction factor is set to a preset constant.
3. The temperature estimation method as described in claim 1, characterized in that, The step of calculating the gear friction heat power of the differential based on the difference in angular velocity between the left and right wheels, the output torque of the motor, and the correction factor includes: Obtain the bench calibration coefficients and reducer ratio of the vehicle, wherein the bench calibration coefficients represent the reference heating gain caused by the inherent physical characteristics of the differential under the target lubrication condition; The differential gear friction heat power is obtained by multiplying the test bench calibration coefficient, the reducer speed ratio, the difference in angular velocity between the left and right wheels, the motor output torque, and the correction factor.
4. The temperature estimation method as described in claim 1, characterized in that, Before the step of estimating the differential temperature based on the gear frictional heat power and the differential heat loss, the method further includes: Determine the thermal resistance between the gears and the lubricating oil in the differential, as well as the gear temperature and reducer oil temperature at the previous moment. The heat loss of the differential is calculated based on the thermal resistance, the gear temperature at the previous moment, and the reducer oil temperature at the previous moment.
5. The temperature estimation method as described in claim 4, characterized in that, The step of estimating the differential temperature based on the frictional heat power of the gears and the heat loss of the differential includes: Determine the time interval between the previous moment and the current moment, and the equivalent heat capacity of the gears in the differential; The differential temperature is estimated based on the gear temperature at the previous moment, the interval time, the equivalent heat capacity, the gear frictional heat power, and the heat loss.
6. The temperature estimation method as described in claim 1, characterized in that, After the step of estimating the differential temperature based on the frictional heat power of the gears and the heat loss of the differential, the method further includes: The real-time operating conditions of the vehicle are determined based on the vehicle steering angle, the difference in angular velocity between the left and right wheels, and the output torque of the motor. A target strategy corresponding to the real-time operating conditions and the differential temperature is determined, and the target strategy is executed to protect the differential.
7. A temperature estimation device, characterized in that, The temperature estimation device includes: The real-time signal acquisition module is used to acquire the difference in angular velocity between the left and right wheels of the vehicle, the output torque of the motor, and the oil temperature of the reducer in real time. The correction factor determination module is used to determine a correction factor based on the reducer oil temperature. The correction factor is used to correct the effect of the lubricating oil temperature in the differential of the vehicle on the frictional heat generated by the gears. The power calculation module is used to calculate the gear friction heat power of the differential based on the difference in angular velocity between the left and right wheels, the output torque of the motor, and the correction factor. The temperature estimation module is used to estimate the differential temperature based on the frictional heat power of the gears and the heat loss of the differential.
8. A temperature estimation device, characterized in that, The device includes: a memory, a processor, and a temperature estimation program stored in the memory and executable on the processor, the temperature estimation program being configured to implement the steps of the temperature estimation method as described in any one of claims 1 to 6.
9. A storage medium, characterized in that, The storage medium is a computer-readable storage medium, and the storage medium stores a temperature estimation program, which, when executed by a processor, implements the steps of the temperature estimation method as described in any one of claims 1 to 6.
10. A computer program product, characterized in that, The computer program product includes a temperature estimation program, which, when executed by a processor, implements the steps of the temperature estimation method as described in any one of claims 1 to 6.