Method for diagnosing failure of continuously variable transmission

Abstract

The application discloses a kind of continuously variable transmission fault diagnosis method, this method can be according to preliminary judgment, primary test strategy, secondary test strategy to the reason of active wheel sensor signal anomaly accurately diagnosed under the condition that vehicle starts and each index is normal, and after diagnosis, it can be according to the diagnosis result to carry out fault handling;For example, when the judgment result is that active wheel speed sensor fails, D / R gear uses turbine speed signal to replace active wheel speed;When the judgment result is that D / R clutch oil pressure is insufficient, the torque of clutch input end is less than 30NM, which can reduce the risk of misjudgment leading to long time slip of clutch and burnout.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of automobile transmission system, and particularly relates to a fault diagnosis method of a continuously variable transmission. BACKGROUND

[0002] In the process of vehicle driving, when the lock clutch of the hydraulic torque converter and the D / R clutch are combined, the engine speed, the turbine speed and the driving wheel speed are compared in pairs, and the speed difference should be very small. If the speed difference between the engine speed and the turbine speed is very small, and the speed difference between the driving wheel speed and the engine speed is large, and the speed difference between the driving wheel speed and the turbine speed is also large, it is determined that the driving wheel speed sensor is invalid. There is no actual pressure sensor in the oil circuit of the D / R clutch, and when the clutch oil pressure is insufficient, the driving wheel and the turbine are not fully engaged, and the speed difference between the driving wheel speed and the turbine speed and the engine speed is large. If it is misjudged as a speed sensor fault at this time, the insufficient clutch oil pressure cannot be found in time and processed, which may cause the clutch to slide for a long time and burn out.

[0003] Therefore, the fault diagnosis method of the continuously variable transmission in the prior art has the problem of low accuracy. SUMMARY

[0004] The present application aims to solve the problem of low accuracy of the fault diagnosis method of the continuously variable transmission in the prior art.

[0005] To solve the above technical problems, one embodiment of the present application provides a fault diagnosis method of a continuously variable transmission, comprising the following steps:

[0006] S1, obtaining the running state information of the vehicle, and determining whether the entering judgment condition is met according to the running state information; if yes, entering step S2;

[0007] S2, obtaining the engine speed information and the driving wheel speed information, and determining whether there is a speed difference between the engine speed and the driving wheel speed according to the engine speed information and the driving wheel speed information; if yes, entering step S3;

[0008] S3, obtaining the turbine speed information, and determining whether the speed difference between the engine speed and the turbine speed is less than a first speed threshold value, and the speed difference between the turbine speed and the driving wheel speed is greater than a second speed threshold value according to the engine speed information, the turbine speed information and the driving wheel speed information;

[0009] If yes, it is determined that the driving wheel sensor signal is abnormal, and entering step S4; if no, entering step S2;

[0010] S4, executing step S3 multiple times to determine whether the driving wheel sensor signal is abnormal more than 3 times.

[0011] If yes, it is determined that the clutch oil pressure is insufficient; if no, a primary test strategy is executed.

[0012] With the technical solution, the continuously variable transmission fault diagnosis method provided by the embodiment can further verify the judgment result of the test strategy when determining the abnormality of the driving wheel sensor signal, thereby ensuring the accuracy of the final judgment result and reducing the risk of misjudgment leading to long-time slip and burnout of the clutch. Therefore, the diagnosis method has the advantage of high accuracy.

[0013] Further, an embodiment of the present application provides a continuously variable transmission fault diagnosis method, wherein the primary test strategy comprises the following steps:

[0014] After limiting the input torque of the clutch to be lower than the torque threshold value for 0.5S, it is determined whether the driving wheel sensor signal is abnormal;

[0015] If yes, a secondary test strategy is executed;

[0016] If no, the clutch torque limitation is stopped, and step S3 is entered.

[0017] With the technical solution, the continuously variable transmission fault diagnosis method provided by the embodiment can further verify the judgment result of the test strategy when determining the abnormality of the driving wheel sensor signal, thereby ensuring the accuracy of the final judgment result and reducing the risk of misjudgment leading to long-time slip and burnout of the clutch. Therefore, the diagnosis method has the advantage of high accuracy.

[0018] Further, an embodiment of the present application provides a continuously variable transmission fault diagnosis method, wherein the secondary test strategy comprises the following steps:

[0019] It is determined whether the difference between the turbine speed and the driving wheel speed is greater than a second speed threshold value;

[0020] If yes, it is determined that the driving wheel sensor is invalid after 1S;

[0021] If no, the clutch torque limitation is stopped, and step S3 is entered.

[0022] Further, an embodiment of the present application provides a continuously variable transmission fault diagnosis method, wherein the torque threshold value is 30NM.

[0023] Further, an embodiment of the present application provides a continuously variable transmission fault diagnosis method, wherein in step S4:

[0024] When it is determined that the clutch oil pressure is insufficient, the input torque of the clutch is limited to be lower than the torque threshold value.

[0025] Further, one embodiment of the present application provides a continuously variable transmission fault diagnosis method, wherein in step S4:

[0026] When the primary wheel sensor signal is abnormal for more than 300 ms, the first level test strategy is executed.

[0027] Further, one embodiment of the present application provides a continuously variable transmission fault diagnosis method, wherein the first rotation speed threshold is 25 rpm and the second rotation speed threshold is 250 rpm.

[0028] Further, one embodiment of the present application provides a continuously variable transmission fault diagnosis method, wherein the running state information comprises engine state information, primary wheel rotation speed sensor state information, vehicle body power supply information, vehicle body network information, electromagnetic valve state information, hydraulic torque converter pressure information, clutch pressure information and gear position information.

[0029] Further, one embodiment of the present application provides a continuously variable transmission fault diagnosis method, wherein the entry judgment condition comprises:

[0030] The engine is in a starting state, and the gear position is in D or R;

[0031] The primary wheel rotation speed sensor, the vehicle body power supply, the vehicle body network and the electromagnetic valve state are normal;

[0032] The hydraulic torque converter pressure is greater than a first pressure threshold, and the target pressure of the clutch is greater than a second pressure threshold.

[0033] Further, one embodiment of the present application provides a continuously variable transmission fault diagnosis method, wherein the first pressure threshold is 5.8 bar and the second pressure threshold is 7 bar.

[0034] Other features and corresponding advantages of the present application are set forth in the remainder of the specification, and will be better understood by reference to the specification, which describes in detail various embodiments of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 A schematic diagram of a transmission with a continuously variable transmission;

[0036] Figure 2 A flowchart of a continuously variable transmission fault diagnosis method provided by an embodiment of the present application;

[0037] Figure 3 A data change diagram of a clutch oil pressure insufficient control process;

[0038] Figure 4 A data change diagram of a primary wheel rotation speed sensor failure control process.

[0039] Reference numerals:

[0040] 10 engine

[0041] 20 torque converter

[0042] 210 turbine speed sensor

[0043] 30 clutch

[0044] 40 drive pulley

[0045] 410 drive pulley speed sensor DETAILED DESCRIPTION

[0046] The advantages and effects of the present application can be easily understood by those skilled in the art from the content disclosed in the specification. Although the description of the present application will be introduced in combination with the preferred embodiments, it does not mean that the features of the present application are limited to the embodiments. On the contrary, the purpose of introducing the present application in combination with the embodiments is to cover other options or modifications which can be extended based on the claims of the present application. In order to provide a deep understanding of the present application, many specific details will be included in the following description. The present application can also be implemented without using these details. In addition, in order to avoid confusion or obscure the focus of the present application, some specific details will be omitted in the description. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0047] It should be noted that in the specification, similar reference numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

[0048] The technical solutions of the present application will be described clearly and completely in combination with the drawings below. Obviously, the described embodiments are part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor belong to the scope of protection of the present application.

[0049] The following detailed description of the application will be made with reference to the accompanying drawings, in which: Although the description of the application will be in the context of preferred embodiments, the application is not limited to the preferred embodiments. Rather, the description is intended to cover all alternatives, modifications and equivalents of the application falling within the scope of the application as defined by the appended claims. In order to provide a thorough understanding of the application, numerous specific details about the application are described in the following description. However, the application can be practiced without these specific details. In some instances, well-known structures and components are not described in detail in order to avoid obscuring the application. Also, in the following description and in the claims, the terms "include" and "have", as well as derivatives thereof, should not be taken to exclude the presence of other elements or limit them to the particular ones stated in such a statement. When an element is referred to as being "connected to" or "coupled to" another element, it can be directly connected or coupled to the other element or connected or coupled to the other element with intervening elements present therebetween.

[0050] It should be noted that in this specification, similar reference numbers and letters in the following drawings represent similar items, and therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0051] In the description of the embodiments, it should be noted that the terms "upper", "lower", "inner", "bottom", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the application is usually placed, and are only for the convenience of describing the application and simplifying the description, and therefore cannot be understood as indicating or implying that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the application.

[0052] The terms "first", "second", etc. are only used for differentiation in description and cannot be understood as indicating or implying relative importance.

[0053] In the description of the embodiments, it should also be noted that, unless otherwise explicitly specified and limited, the terms "provided", "connected", "connected" should be broadly understood, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be connected inside two elements. For those skilled in the art, the specific meaning of the above terms in the embodiments can be understood according to the specific circumstances.

[0054] In order to make the purpose, technical solutions and advantages of the application more clear, the embodiments of the application will be further described in detail below with reference to the drawings.

[0055] The continuously variable transmission fault diagnosis method provided by the embodiments is applicable to Figure 1The transmission system is shown, in which the power output by the engine 10 is transmitted to the driving wheel 40 through the hydraulic torque converter 20 and the clutch 30. The turbine speed sensor 210 is used to detect the speed of the output end of the hydraulic torque converter 20, and the driving wheel speed sensor 410 is used to detect the speed of the driving wheel 40. The method realizes decoupling diagnosis when the driving wheel speed sensor 410 fails or the clutch oil pressure is insufficient. When the clutch 30 is in the engaged state, if there is a certain speed difference between the turbine and the driving wheel 40, the input end torque of the clutch 30 is reduced, and whether the speed difference between the turbine and the driving wheel 40 is eliminated or not, the speed difference caused by the failure of the driving wheel speed sensor 410 or the insufficient oil pressure of the clutch 30 is more accurately judged.

[0056] The specific method is as shown in Figures 2-4 The specific method is as shown in

[0057] S1, obtaining the running state information of the automobile, and judging whether the entering judgment condition is met according to the running state information; if yes, entering step S2;

[0058] S2, obtaining the engine speed information and the driving wheel speed information, and judging whether there is a difference between the engine speed and the driving wheel speed according to the engine speed information and the driving wheel speed information; if yes, entering step S3;

[0059] S3, obtaining the turbine speed information, and judging whether the difference between the engine speed and the turbine speed is less than the first speed threshold value, and whether the difference between the turbine speed and the driving wheel speed is greater than the second speed threshold value according to the engine speed information, the turbine speed information and the driving wheel speed information;

[0060] If yes, it is determined that the driving wheel sensor signal is abnormal, and step S4 is entered; if no, step S2 is entered;

[0061] S4, executing step S3 multiple times to judge whether the driving wheel sensor signal abnormality is more than 3 times;

[0062] If yes, it is determined that the clutch oil pressure is insufficient; if no, the first test strategy is executed.

[0063] Specifically, the continuously variable transmission fault diagnosis method provided by the embodiment can further verify the judgment result of the driving wheel sensor signal abnormality through the test strategy, thereby ensuring the accuracy of the final judgment result and reducing the risk of misjudgment leading to long-time slip and burnout of the clutch. Therefore, the diagnosis method in the embodiment has the advantage of high accuracy.

[0064] Further, one embodiment of the embodiment provides a continuously variable transmission fault diagnosis method, and the first test strategy includes the following steps:

[0065] If the input torque of the limiting clutch is less than the torque threshold 0.5S, it is determined whether the driving wheel sensor signal is abnormal, and if so, a secondary test strategy is executed.

[0066] If not, the clutch torque limitation is stopped, and step S3 is entered.

[0067] If not, the clutch torque limitation is stopped, and step S3 is entered.

[0068] Specifically, the continuously variable transmission fault diagnosis method provided by the embodiment continues to determine whether the driving wheel sensor signal is abnormal after the input torque of the limiting clutch is less than the torque threshold 0.5S, and if so, a secondary test strategy is executed. Through two levels of testing, the accuracy of the final judgment result can be further improved.

[0069] Further, one embodiment of the embodiment provides a continuously variable transmission fault diagnosis method, and the secondary test strategy includes the following steps:

[0070] It is determined whether the difference between the turbine speed and the driving wheel speed is greater than a second speed threshold;

[0071] If so, it is determined that the driving wheel sensor is invalid after 1S;

[0072] If not, the clutch torque limitation is stopped, and step S3 is entered.

[0073] Further, one embodiment of the embodiment provides a continuously variable transmission fault diagnosis method, and the torque threshold is 30NM.

[0074] Further, one embodiment of the embodiment provides a continuously variable transmission fault diagnosis method, in step S4:

[0075] When the clutch oil pressure is determined to be insufficient, the input torque of the limiting clutch is limited to be less than the torque threshold.

[0076] Further, one embodiment of the embodiment provides a continuously variable transmission fault diagnosis method, in step S4:

[0077] When the driving wheel sensor signal is abnormal for more than 300ms, a primary test strategy is executed.

[0078] Further, one embodiment of the embodiment provides a continuously variable transmission fault diagnosis method, and the first speed threshold is 25rpm and the second speed threshold is 250rpm.

[0079] Further, one embodiment of the embodiment provides a continuously variable transmission fault diagnosis method, and the operating state information includes engine state information, driving wheel speed sensor state information, vehicle body power supply information, vehicle body network information, solenoid valve state information, hydraulic torque converter pressure information, clutch pressure information, and gear information.

[0080] Further, one embodiment of the embodiment provides a continuously variable transmission fault diagnosis method, the entering judgment condition comprises:

[0081] The engine is in a starting state, the gear is in a D gear or an R gear;

[0082] The driven wheel rotation speed sensor, the vehicle body power supply, the vehicle body network and the electromagnetic valve state are normal;

[0083] The hydraulic torque converter pressure is greater than a first pressure threshold, and the target pressure of the clutch is greater than a second pressure threshold.

[0084] Further, one embodiment of the embodiment provides a continuously variable transmission fault diagnosis method, the first pressure threshold is 5.8 bar, and the second pressure threshold is 7 bar.

[0085] Figure 3 The abscissa of the graph is described as follows:

[0086] t0: The vehicle is normally driven, and the pressure and the rotation speed are normal;

[0087] t1: The actual pressure of the D / R clutch is less than the target pressure;

[0088] t2: The driven wheel rotation speed and the turbine rotation speed are separated;

[0089] t3: The torque limiting the input end of the D / R clutch is less than 30 NM;

[0090] t4: The D / R clutch is combined, and the difference between the driven wheel rotation speed and the turbine rotation speed is small;

[0091] t5: The torque limiting the input end of the D / R clutch is exited;

[0092] t6: The driven wheel rotation speed and the turbine rotation speed are separated for the second time;

[0093] t7: The torque limiting the input end of the D / R clutch for the second time is less than 30 NM;

[0094] t8: The driven wheel rotation speed and the turbine rotation speed are separated for the third time;

[0095] t9: The torque limiting the input end of the D / R clutch for the third time is less than 30 NM;

[0096] t10: It is confirmed that the clutch oil pressure is insufficient, and the torque limiting the input end of the D / R clutch in the current cycle is less than 30 NM.

[0097] Figure 4 The abscissa of the graph is described as follows:

[0098] t0: The vehicle is normally driven, and the pressure and the rotation speed are normal;

[0099] t1: the driven wheel rotation speed sensor signal is abnormal, and the driven wheel rotation speed and the turbine rotation speed are separated;

[0100] t2: the torque input end of the D / R clutch is limited to less than 30 NM;

[0101] t3: the driven wheel rotation speed sensor signal is still abnormal, and the actual speed ratio signal is abnormal;

[0102] t4: it is confirmed that the driven wheel rotation speed sensor fails, and the torque input end of the D / R clutch is exited from being limited.

[0103] The step-by-step implementation of the continuously variable transmission fault diagnosis method provided in the embodiment is as follows:

[0104] First step, start the engine, and engage the D or R gear, and confirm that the automobile network, electromagnetic valve, hydraulic torque converter pressure, and clutch pressure are normal. That is, Figure 3 and Figure 4 the state shown at t0 in FIG. 1.

[0105] Second step, preliminary judgment: when the rotation speed difference between the engine rotation speed and the turbine rotation speed is less than 25 rpm, the difference between the driven wheel rotation speed and the engine rotation speed is greater than 250 rpm, the difference between the driven wheel rotation speed and the turbine rotation speed is greater than 250 rpm, and the state duration is more than 300 ms, it is preliminarily determined that the driven wheel rotation speed sensor signal is abnormal. That is, Figure 3 at t2 in FIG. 2, and Figure 4 at t1 in FIG. 1.

[0106] Third step, test phase: execute the first-level test strategy, that is, when the driven wheel rotation speed sensor signal is abnormal, the torque input end of the D / R clutch is limited to less than 30 NM, as shown in Figure 3 at t3 in FIG. 2, and Figure 4 at t2 in FIG. 1.

[0107] Fourth step, confirmation phase: execute the second-level test strategy,

[0108] If the torque input end of the D / R clutch is limited to less than 30 NM for more than 1 s, the driven wheel rotation speed sensor signal is still abnormal, and the difference between the target speed ratio and the actual speed ratio is more than 0.4, it is determined that the driven wheel rotation speed sensor fails, and the torque limit of 30 NM is exited, as shown in Figure 4 at t2-t4 in FIG. 2;

[0109] If the torque of the input end of the D / R clutch is limited to less than 30 NM, the difference between the actual speed ratio and the target speed ratio is less than 0.4, the difference between the rotation speed of the driving wheel and the rotation speed of the engine is less than 250 rpm, the difference between the rotation speed of the driving wheel and the rotation speed of the turbine is less than 250 rpm, and the difference between the rotation speed of the engine and the rotation speed of the turbine is less than 25 rpm, the limitation of the torque of the input end of the D / R clutch is exited. If the above conditions are met for three times, it is determined that the oil pressure of the D / R clutch is insufficient, and the D / R clutch is controlled to be in the D / R gear. Figure 3 The state at time t3-t10 is shown in FIG. 3.

[0110] Step 5, fault handling stage:

[0111] When the determination result is that the rotation speed sensor of the driving wheel is invalid, the rotation speed signal of the turbine is used to replace the rotation speed signal of the driving wheel when the vehicle is in the D / R gear. Figure 4 The state at time t4 is shown in FIG. 4.

[0112] When the determination result is that the oil pressure of the D / R clutch is insufficient, the torque of the input end of the clutch is continuously limited to be less than 30 NM to protect the hardware of the clutch from being excessively worn. Figure 3 The state at time t10 is shown in FIG. 10.

[0113] Through the above steps, it can be accurately determined whether the abnormal driving wheel sensor signal is caused by the invalid driving wheel sensor or the insufficient oil pressure of the D / R clutch. When the determination result is obtained, the fault can be handled, and the hardware of the clutch can be effectively protected.

[0114] Although the present application has been illustrated and described with reference to certain preferred embodiments thereof, it should be understood by those skilled in the art that the foregoing is a further detailed description of the application and is not intended to limit the application to the specific embodiments described. Various changes in form and detail can be made thereto without departing from the spirit and scope of the application.

Claims

1. A method for diagnosing faults in a continuously variable transmission (CVT), characterized in that, Includes the following steps: S1. Obtain the vehicle's operating status information, and determine whether the entry judgment condition is met based on the operating status information; If so, proceed to step S2; S2. Obtain engine speed information and drive wheel speed information, and determine whether there is a difference between the engine speed and the drive wheel speed based on the engine speed information and the drive wheel speed information. If so, proceed to step S3. S3. Obtain turbine speed information, and determine based on the engine speed information, the turbine speed information, and the drive wheel speed information: whether the difference between the engine speed and the turbine speed is less than a first speed threshold, and whether the difference between the turbine speed and the drive wheel speed is greater than a second speed threshold; If yes, determine that the drive wheel sensor signal is abnormal and proceed to step S4; otherwise, proceed to step S2. S4. Repeat step S3 multiple times to determine if the drive wheel sensor signal abnormality exceeds 3 times. If yes, then the clutch oil pressure is insufficient; if no, execute the first-level test strategy. The first-level testing strategy includes the following steps: After the input torque of the limiting clutch is lower than the torque threshold by 0.5 seconds, the system continues to determine whether the signal from the drive wheel sensor is abnormal. If so, execute the level 2 testing strategy; If not, stop the clutch torque limiting and proceed to step S3.

2. The continuously variable transmission (CVT) fault diagnosis method as described in claim 1, characterized in that, The secondary testing strategy includes the following steps: Determine whether the difference between the turbine speed and the drive wheel speed is greater than a second speed threshold; If so, the active wheel sensor is determined to be faulty after 1 second; If not, stop the clutch torque limiting and proceed to step S3.

3. The continuously variable transmission (CVT) fault diagnosis method as described in claim 1, characterized in that, The torque threshold is 30 NM.

4. The continuously variable transmission (CVT) fault diagnosis method as described in claim 1, characterized in that, In step S4: When the clutch oil pressure is determined to be insufficient, the clutch input torque is limited to be lower than the torque threshold.

5. The continuously variable transmission (CVT) fault diagnosis method as described in claim 1, characterized in that, In step S4: When the abnormal signal of the drive wheel sensor exceeds 300ms, the first-level test strategy is executed.

6. The continuously variable transmission (CVT) fault diagnosis method as described in claim 1, characterized in that, The first speed threshold is 25 rpm, and the second speed threshold is 250 rpm.

7. The continuously variable transmission (CVT) fault diagnosis method according to any one of claims 1-6, characterized in that, The operating status information includes engine status information, drive wheel speed sensor status information, vehicle body power supply information, vehicle body network information, solenoid valve status information, hydraulic torque converter pressure information, clutch pressure information, and gear information.

8. The continuously variable transmission (CVT) fault diagnosis method as described in claim 7, characterized in that, The entry determination conditions include: The engine is running and the gear is in D or R. The drive wheel speed sensor, body power supply, body network, and solenoid valves are all functioning normally. The hydraulic torque converter pressure is greater than the first pressure threshold, and the clutch target pressure is greater than the second pressure threshold.

9. The continuously variable transmission (CVT) fault diagnosis method as described in claim 8, characterized in that, The first pressure threshold is 5.8 bar, and the second pressure threshold is 7 bar.

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