A method for predicting the slip rate of a silicone oil fan clutch

Abstract

The present application relates to a kind of silicon oil fan clutch slip rate prediction method, belong to vehicle thermal management and clutch state prediction technical field.The method obtains driving end speed, fan speed, target fan speed, silicon oil temperature and ambient temperature;According to silicon oil temperature, calculate silicon oil viscosity correction coefficient, calculate target slip rate and actual slip rate;Establish transmission torque estimation model, and solve balanced fan speed in combination with fan load curve;According to balanced fan speed output prediction slip rate;Again, the error correction model parameter between actual slip rate and prediction slip rate is utilized.The method can couple silicon oil viscosity-temperature characteristic, fan load curve and driving end-from driving end speed relationship, improve the accuracy and adaptability of slip rate prediction under different conditions.

Description

Technical Field

[0001] This invention belongs to the fields of vehicle thermal management, silicone oil fan clutch state prediction and electromechanical control technology, and specifically relates to a method for predicting the slip rate of a silicone oil fan clutch. Background Technology

[0002] Silicone oil fan clutches are widely used in vehicle engine cooling systems. They transmit torque between the driving and driven ends via silicone oil, allowing the fan speed to change according to the engine's cooling requirements. Slip ratio is an important parameter characterizing the transmission state of a silicone oil fan clutch; its magnitude directly reflects the degree of coupling between the driving end speed and the fan end speed.

[0003] In actual operation, the slip ratio of the silicone oil fan clutch is affected by factors such as the driving end speed, fan load, silicone oil temperature, ambient temperature, and silicone oil viscosity. Specifically, silicone oil viscosity decreases with increasing temperature, thus altering the clutch's torque transmission capability; the fan load torque, in turn, varies with fan speed and air density. Therefore, under different thermal and speed conditions, the clutch slip ratio exhibits significant nonlinearity and condition-dependent characteristics.

[0004] In existing technologies, the slip state of silicone oil fan clutches is typically estimated using lookup tables, empirical coefficients, or single speed difference calculations. While these methods are simple to implement, they usually do not fully consider the influence of silicone oil viscosity-temperature characteristics on transmitted torque, nor do they combine the fan load curve with the torque balance relationship. This results in significant errors in the prediction results under conditions of large temperature variations or significant fan load variations.

[0005] Furthermore, while some methods can calculate the current slip ratio using measured fan speeds, they only reflect the current operating state and cannot obtain the equilibrium fan speed and corresponding slip ratio in advance for control strategy calculations or performance predictions. Existing methods typically lack a self-correction mechanism for model parameters based on measured slip ratio errors, making it difficult to adapt to model drift caused by factors such as silicone oil aging, assembly differences, fan load deviations, and sensor biases.

[0006] Therefore, there is an urgent need to provide a method for predicting the slip rate of a silicone oil fan clutch, which combines silicone oil viscosity-temperature compensation, transmission torque estimation, fan load curve and equilibrium speed solution, and corrects the model parameters by measuring the slip rate, so as to improve the accuracy and adaptability of the slip rate prediction of the silicone oil fan clutch under different operating conditions. Summary of the Invention

[0007] To address the issues that existing methods for estimating the slip ratio of silicone oil fan clutches do not adequately couple the viscosity-temperature characteristics of silicone oil, the fan load curve, and the speed relationship between the driving and driven ends, and lack model self-correction capabilities, this invention provides a method for predicting the slip ratio of silicone oil fan clutches.

[0008] The technical solution adopted by this invention to solve the above-mentioned technical problems is as follows: Obtain the active end speed, fan speed, target fan speed, silicone oil temperature, and ambient temperature; calculate the silicone oil viscosity correction coefficient based on the silicone oil temperature; calculate the target slip ratio based on the active end speed and target fan speed; calculate the actual slip ratio based on the active end speed and fan speed; establish a transmission torque estimation model based on the active end speed, silicone oil viscosity correction coefficient, and the fan speed to be solved; solve for the balance fan speed by combining the fan load curve; calculate the predicted slip ratio based on the balance fan speed; and correct the model parameters using the error between the actual slip ratio and the predicted slip ratio. The model parameters include the transmission torque coefficient, fan load coefficient, and viscosity-temperature compensation parameters.

[0009] The present invention provides a method for predicting the slip rate of a silicone oil fan clutch, comprising the following steps:

[0010] Step 1: Obtain operating condition data.

[0011] The system acquires the driving end speed, fan speed, target fan speed, silicone oil temperature, and ambient temperature of the silicone oil fan clutch. The driving end speed can be the clutch driving disc speed or the engine input speed; the fan speed is the clutch driven end speed; and the silicone oil temperature can be obtained directly from the silicone oil chamber temperature sensor or calculated from the clutch housing temperature.

[0012] Step 2: Preprocess the operating condition data.

[0013] Outlier removal, filtering, and smoothing are performed on the active end speed, fan speed, target fan speed, silicone oil temperature, and ambient temperature to obtain operating condition input data for slip rate prediction. Outlier removal can be performed based on speed range, temperature range, and rate of change threshold; filtering can be performed using moving average filtering, median filtering, or low-pass filtering.

[0014] Step 3: Calculate the silicone oil viscosity correction factor, target slip ratio, and actual slip ratio.

[0015] Calculate the silicone oil viscosity correction factor based on the silicone oil temperature and the silicone oil viscosity at the reference temperature. Calculate the target slip ratio based on the active end speed and the target fan speed, and calculate the actual slip ratio based on the active end speed and the measured fan speed.

[0016] Step 4: Establish a torque transmission estimation model.

[0017] Based on the active end speed, the fan speed to be solved, the silicone oil viscosity correction coefficient, and the transmission torque coefficient, a torque estimation model for the silicone oil fan clutch is established. This model is used to describe the torque that the clutch can transmit to the fan end under different speed differences and silicone oil temperatures.

[0018] Step 5: Solve for the balanced fan speed by combining the fan load curve.

[0019] The fan load torque is calculated based on the fan speed and ambient temperature. The estimated transmitted torque is then compared with the estimated fan load torque. When the difference between the two meets a preset balance threshold, the corresponding fan speed is determined as the balanced fan speed.

[0020] Step 6: Calculate and output the predicted slip rate.

[0021] The predicted slip ratio is calculated based on the speed of the driving end and the speed of the balancing fan, and the predicted slip ratio, target slip ratio, and actual slip ratio are output. Furthermore, reference information for clutch control or condition monitoring can be generated based on the deviation between the predicted slip ratio and the target slip ratio.

[0022] Step 7: Correct the model parameters based on the measured slip error.

[0023] Based on the error between the actual slip rate and the predicted slip rate, the transmission torque coefficient, fan load coefficient, and viscosity-temperature compensation parameters are corrected. When the actual slip rate is greater than the predicted slip rate, at least one of the following actions is taken: decreasing the transmission torque coefficient or increasing the fan load coefficient. When the actual slip rate is less than the predicted slip rate, at least one of the following actions is taken: increasing the transmission torque coefficient or decreasing the fan load coefficient.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] First, by introducing a silicone oil viscosity correction coefficient, this invention incorporates the influence of silicone oil temperature changes on torque transmission capability into the slip ratio prediction process, thereby improving the prediction accuracy during high temperature, low temperature, and temperature rise processes.

[0026] Secondly, this invention combines the clutch transmission torque estimation model with the fan load curve, and solves the balanced fan speed through the torque balance relationship, which can avoid the prediction deviation caused by relying solely on empirical speed difference or static table lookup.

[0027] Third, this invention simultaneously outputs the target slip rate, the actual slip rate, and the predicted slip rate, which can provide a data foundation for optimizing the control strategy, monitoring the condition, and evaluating the performance of the silicone oil fan clutch.

[0028] Fourth, this invention uses the actual slip rate error to self-correct the model parameters, which can reduce the impact of silicone oil aging, assembly differences, fan load changes and sensor deviations on the prediction results, and improve the adaptability of the method under different vehicles and different working conditions. Attached Figure Description

[0029] Figure 1This is a schematic diagram of the silicone oil fan clutch slip rate prediction system architecture of the present invention.

[0030] Figure 2 This is a schematic diagram of the process for predicting the slip rate of a silicone oil fan clutch according to the present invention.

[0031] Figure 3 This is a schematic diagram illustrating the solution for balancing the transmitted torque and the fan load torque in this invention.

[0032] Figure 4 This is a schematic diagram of the self-calibration process of model parameters based on measured slip error in this invention. Detailed Implementation

[0033] The present invention will now be described in detail with reference to the accompanying drawings. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0034] like Figure 1 As shown, the slip rate prediction system of this embodiment includes a data acquisition unit 101, a data preprocessing unit 102, a viscosity-temperature compensation unit 103, a slip rate calculation unit 104, a transmission torque estimation unit 105, a fan load calculation unit 106, a balance speed solution unit 107, a prediction result output unit 108, and a parameter self-correction unit 109.

[0035] The data acquisition unit 101 acquires the active end speed, fan speed, target fan speed, silicone oil temperature, and ambient temperature. The data preprocessing unit 102 performs outlier removal, filtering, and smoothing on the acquired data. The viscosity-temperature compensation unit 103 calculates the silicone oil viscosity correction coefficient. The slip ratio calculation unit 104 calculates the target slip ratio, actual slip ratio, and predicted slip ratio. The transmission torque estimation unit 105 establishes a clutch transmission torque estimation model. The fan load calculation unit 106 calculates the fan load torque based on the fan load curve. The balance speed solution unit 107 solves for the fan speed when the transmission torque and load torque are balanced. The prediction result output unit 108 outputs the predicted slip ratio. The parameter self-calibration unit 109 corrects the model parameters based on the actual slip ratio error.

[0036] like Figure 2 As shown, the method flow of this embodiment includes: acquiring operating condition data, performing data preprocessing, calculating the silicone oil viscosity correction coefficient, calculating the target slip rate and the actual slip rate, establishing a transmission torque estimation model, solving the balanced fan speed by combining the fan load curve, calculating the predicted slip rate, and correcting the model parameters based on the measured slip rate error.

[0037] In one embodiment, the viscosity of silicone oil at the silicone oil temperature can be expressed as:

[0038] (1)

[0039] in, This indicates the dynamic viscosity of the silicone oil at the current silicone oil temperature; Indicates the dynamic viscosity of silicone oil at the reference temperature; Indicates viscosity-temperature compensation parameters; Indicates the current silicone oil temperature; Indicates reference temperature; Represented by natural constant An exponential function with base 0; Used to convert Celsius temperature to thermodynamic temperature.

[0040] In one embodiment, the silicone oil viscosity correction factor can be expressed as:

[0041] (2)

[0042] in, This represents the silicone oil viscosity correction factor, used to characterize the proportion of change in silicone oil viscosity at the current temperature relative to the silicone oil viscosity at the reference temperature; This indicates the dynamic viscosity of the silicone oil at the current silicone oil temperature; This indicates the dynamic viscosity of silicone oil at the reference temperature.

[0043] In one embodiment, the target slip ratio can be expressed as:

[0044] (3)

[0045] in, Indicates the target slip ratio; Indicates the rotational speed of the active end; Indicates the target fan speed; This represents the speed protection constant, used to prevent the denominator from being zero when the speed of the active end approaches zero.

[0046] In one embodiment, the actual slip ratio can be expressed as:

[0047] (4)

[0048] in, This represents the actual slip ratio; Indicates the rotational speed of the active end; This indicates the measured fan speed; This represents the speed protection constant.

[0049] In one embodiment, the candidate slip ratio corresponding to the fan speed to be solved can be expressed as:

[0050] (5)

[0051] in, This indicates the fan speed to be solved. The corresponding candidate slip ratio; Indicates the rotational speed of the active end; This represents the fan speed to be determined; This represents the speed protection constant.

[0052] In one embodiment, the torque estimation model for the silicone oil fan clutch can be expressed as:

[0053] (6)

[0054] in, This indicates the fan speed to be solved. The corresponding estimated value of clutch transmission torque; Indicates the transmitted torque coefficient; Indicates the viscosity correction factor for silicone oil; Indicates the rotational speed of the active end; This represents the fan speed to be determined; Indicates the speed difference index; This represents the basic resistance torque or residual transmitted torque. In actual implementation, It can be calibrated based on bench test data.

[0055] In one embodiment, the air density after ambient temperature correction can be expressed as:

[0056] (7)

[0057] in, This represents an estimated value of air density at the current ambient temperature. This indicates the air density at a reference ambient temperature. Indicates the reference ambient temperature; Indicates the current ambient temperature; Used to convert Celsius temperature to thermodynamic temperature.

[0058] In one embodiment, the fan load torque can be expressed as:

[0059] (8)

[0060] in, This indicates the fan speed to be solved. The corresponding estimated fan load torque; Indicates the fan load factor; This represents an estimated value of air density at the current ambient temperature. This represents the fan speed to be determined; Indicates the fan load index; This represents the base load torque. In actual implementation, It can be calibrated based on the fan load test curve.

[0061] like Figure 3 As shown, the balancing fan speed is determined by the balance relationship between the transmitted torque and the fan load torque. In one embodiment, the balancing fan speed can be expressed as:

[0062] (9)

[0063] in, Indicates the balance fan speed; This represents the value of the variable that minimizes the objective function; This represents the fan speed to be determined; This represents the search interval for determining the fan speed. Indicates the rotational speed of the active end; This represents the estimated value of the clutch transmitted torque; This represents the estimated value of the fan load torque.

[0064] In one embodiment, the predicted slip ratio can be expressed as:

[0065] (10)

[0066] in, Indicates the predicted slip ratio; Indicates the rotational speed of the active end; Indicates the balance fan speed; This represents the speed protection constant.

[0067] In one embodiment, the error between the actual slip rate and the predicted slip rate can be expressed as:

[0068] (11)

[0069] in, This indicates the error in slip ratio prediction; This represents the actual slip ratio; This indicates the predicted slip ratio. When... A value greater than zero indicates that the actual slip rate is greater than the predicted slip rate; when A value less than zero indicates that the actual slip rate is less than the predicted slip rate.

[0070] like Figure 4 As shown, the parameter self-correction unit 109 corrects the model parameters based on the slip ratio prediction error. In one embodiment, the update of the transmission torque coefficient can be expressed as:

[0071] (12)

[0072] in, Indicates the first The transmitted torque coefficient after the next update; Indicates the first Transmitted torque coefficient before the last update; Indicates the step size for correcting the transmitted torque coefficient; Indicates the first The slip ratio prediction error obtained from the first calculation; Indicates the lower limit of the transmitted torque coefficient; Indicates the upper limit of the transmitted torque coefficient; This represents a limiting function, used to restrict updated parameters within a preset range.

[0073] In one embodiment, the update of the fan load factor can be expressed as:

[0074] (13)

[0075] in, Indicates the first Fan load factor after the latest update; Indicates the first Fan load factor before the update; Indicates the fan load factor correction step size; Indicates the first The slip ratio prediction error obtained from the first calculation; Indicates the lower limit of the fan load factor; Indicates the upper limit of the fan load factor; This represents a limiting function, used to restrict updated parameters within a preset range.

[0076] In one embodiment, the update of the viscosity-temperature compensation parameter can be expressed as:

[0077] (14)

[0078] in, Indicates the first The updated viscosity-temperature compensation parameters; Indicates the first Viscosity-temperature compensation parameters before the last update; Indicates the step size for viscosity-temperature compensation parameter correction; Indicates the first The slip ratio prediction error obtained from the first calculation; Indicates the first Silicone oil temperature at the time of the next calculation; Indicates reference temperature; Indicates the lower limit of the viscosity-temperature compensation parameter; Indicates the upper limit of the viscosity-temperature compensation parameter; This represents a limiting function, used to restrict the updated parameters within a preset range; Used to convert Celsius temperature to thermodynamic temperature.

[0079] In one embodiment, to avoid excessive correction of model parameters due to single measurement errors, an error dead zone can be set, and the preset error threshold is a value greater than zero. When the absolute value of the slip prediction error is less than the preset error threshold, parameter updates are not performed; when the absolute value of the slip prediction error is greater than or equal to the preset error threshold, parameter updates are performed.

[0080] In one embodiment, the prediction result output unit 108 outputs the predicted slip ratio, target slip ratio, actual slip ratio, balance fan speed, slip ratio prediction error, and model parameter correction status. These output results can be used for clutch performance evaluation, fan speed control, engine cooling system matching, and fault diagnosis assistance.

[0081] This invention is not limited to the embodiments described above. Without departing from the principles of this invention, those skilled in the art can make equivalent substitutions or improvements to the transmission torque estimation model, the fan load curve form, the parameter update method, and the filtering method, and such substitutions and improvements should all be considered within the scope of protection of this invention.

Claims

1. A method for predicting the slip rate of a silicone oil fan clutch, characterized in that, Performed by electronic equipment, the method for predicting the fan end slip ratio based on the operating conditions of the silicone oil fan clutch includes the following steps: S1. Obtain the active end speed, fan speed, target fan speed, silicone oil temperature, and ambient temperature; S2. Perform outlier removal, filtering, and smoothing on the active end speed, fan speed, target fan speed, silicone oil temperature, and ambient temperature to obtain the operating condition input data. S3. Calculate the silicone oil viscosity correction coefficient based on the silicone oil temperature, calculate the target slip ratio based on the active end speed and the target fan speed, and calculate the actual slip ratio based on the active end speed and the fan speed. S4. Establish a transmission torque estimation model based on the active end speed, silicone oil viscosity correction coefficient, and fan speed to be solved; S5. Call the fan load curve and solve for the balanced fan speed based on the transmitted torque estimation model and the fan load curve; S6. Calculate the predicted slip ratio based on the active end speed and the balance fan speed, and output the predicted slip ratio, the target slip ratio and the actual slip ratio; S7. Based on the error between the actual slip rate and the predicted slip rate, correct the model parameters used for calculating the transmission torque estimation model, fan load curve, and silicone oil viscosity correction coefficient.

2. The method according to claim 1, characterized in that, In step S1, the active end speed is the clutch active plate speed or the engine input speed, the fan speed is the clutch driven end speed, and the silicone oil temperature is the silicone oil cavity temperature or the equivalent silicone oil temperature calculated from the clutch housing temperature.

3. The method according to claim 1, characterized in that, In step S2, the outlier removal includes removing data that exceeds a preset speed range, a preset temperature range, or a preset rate of change range; the filtering and smoothing process includes at least one of moving average filtering, median filtering, or low-pass filtering.

4. The method according to claim 1, characterized in that, In step S3, the silicone oil viscosity correction coefficient is calculated based on the silicone oil viscosity at the reference temperature, the current silicone oil temperature, and the viscosity-temperature compensation parameter. It is used to characterize the degree of change in the silicone oil's torque transmission capability at the current temperature relative to its torque transmission capability at the reference temperature.

5. The method according to claim 1, characterized in that, In step S4, the transmission torque estimation model takes the speed difference between the active end speed and the fan speed to be solved, the silicone oil viscosity correction coefficient, and the transmission torque coefficient as inputs, and outputs the estimated value of the clutch transmission torque under the current working condition.

6. The method according to claim 1, characterized in that, In step S5, the fan load curve takes the fan speed to be solved and the ambient temperature as input and outputs the estimated value of the fan load torque; when the difference between the estimated value of the clutch transmission torque and the estimated value of the fan load torque meets the preset balance threshold, the corresponding fan speed to be solved is determined as the balanced fan speed.

7. The method according to claim 1, characterized in that, In step S7, the model parameters include the transmission torque coefficient, the fan load coefficient, and the viscosity-temperature compensation parameter; when the actual slip rate is greater than the predicted slip rate, at least one of the transmission torque coefficient is reduced and the fan load coefficient is increased; when the actual slip rate is less than the predicted slip rate, at least one of the transmission torque coefficient is increased and the fan load coefficient is decreased.

8. An electronic device, characterized in that, It includes a processor and a memory, wherein the memory stores a computer program, which, when executed by the processor, implements the method according to any one of claims 1 to 7.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the method described in any one of claims 1 to 7.

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