Method and system for active diagnosis of a main oil pressure system of a continuously variable transmission

Abstract

The application provides a kind of active diagnosis method and system for continuously variable transmission main oil pressure system, method includes: when engine idle speed is in stable threshold range, vehicle current gear is in parking gear or neutral gear, then active diagnosis step is activated, including: control pressure control valve current and oil pump switching control valve current to maximum value, measure oil pressure;Again, ramp control oil pump switching control valve current to minimum value, measure oil pressure;Again, ramp control pressure control valve current to minimum value, measure oil pressure;Again, ramp control pressure control valve current to maximum value, measure oil pressure;Again, ramp control oil pump switching control valve current to maximum value, measure oil pressure;Every time according to whether oil pressure reaches corresponding threshold to judge whether error is generated, no error is normal.The application utilizes main oil pressure system hydraulic principle, combines main oil pressure sensor, realizes active diagnosis test to hydraulic system, according to test result, can be intervened in advance, to carry out protection to avoid further damage.

Description

Technical Field

[0001] This invention relates to automotive main hydraulic systems, and particularly to an active diagnostic method and corresponding active diagnostic system for continuously variable transmission (CVT) main hydraulic systems. Background Technology

[0002] Continuously variable transmissions (CVTs) are widely used in automobiles. Among existing CVTs, one design features a dual-pump main oil pressure control system. This system uses a pump switching valve to switch the operating modes of the two pumps and a pressure regulating valve to adjust the main oil flow.

[0003] Current main hydraulic system control methods lack the ability to proactively diagnose and test faults. Therefore, faults in the main hydraulic system cannot be confirmed in advance. Only when abnormal pressure is detected during actual control can measures be taken. By this time, insufficient pressure or other abnormalities may have already occurred, causing abnormalities in the next level of the system, or even further damaging the transmission. Summary of the Invention

[0004] The purpose of this invention is to solve the problem that existing main hydraulic system control methods lack the ability to proactively diagnose the main hydraulic system in advance, and that abnormal main hydraulic pressure may cause abnormal operation of the next level system, or even further damage the transmission.

[0005] To address the aforementioned technical problems, this invention provides an active diagnostic method for the main hydraulic system of a continuously variable transmission (CVT), characterized in that the active diagnostic method includes the following steps:

[0006] Determine if the engine idle speed is within a stable threshold range and if the vehicle's current gear is in park or neutral. If yes, activate the active diagnostic step; otherwise, continue the assessment.

[0007] Active diagnostic steps include:

[0008] S1: Control the pressure control valve current to the maximum value to request the minimum main oil pressure; control the oil pump switching control valve current to the maximum value to request the minimum main oil flow rate, and check whether the main oil pressure reaches the minimum threshold; if the minimum threshold cannot be reached, it is determined that error 1 has occurred; if the minimum threshold can be reached, proceed to step S2.

[0009] S2: The ramp control oil pump switches the control valve current to the minimum value to request the maximum main oil flow rate; check whether the main oil pressure is within the intermediate threshold range; if it is not within the intermediate threshold range, it is determined that error 2 has occurred; if it is within the intermediate threshold range, proceed to step S3.

[0010] S3: The ramp control pressure control valve current is reduced to the minimum value to request the maximum main oil pressure; the main oil pressure is checked to see if it reaches the highest threshold; if it cannot reach the highest threshold, error 3 is determined to have occurred; if it can reach the highest threshold, proceed to step S4.

[0011] S4: The ramp control pressure control valve current is increased to the maximum value to request the minimum main oil pressure. The main oil pressure is checked to see if it is within the intermediate threshold range. If it is not within the intermediate threshold range, error 4 is determined to have occurred; if it is within the intermediate threshold range, proceed to step S5.

[0012] S5: The ramp control oil pump switches the control valve current to the maximum value to request the minimum main oil flow rate and detects whether the main oil pressure reaches the minimum threshold. If the minimum threshold cannot be reached, it is determined that error 5 has occurred; if the minimum threshold is reached, it is determined that the oil pressure of the CVT main oil pressure system is normal.

[0013] By adopting the above scheme, specific currents are set for the oil pump switching control valve and pressure control valve of the main hydraulic system. Combined with the detection of the main hydraulic pressure change pattern, the system can diagnose and test the highest and lowest pressures of the main hydraulic system and whether the oil pump switching control valve has switched directions. Based on the diagnostic results, the control system can be intervened in advance to protect the gearbox hardware from further damage. In addition, the oil pump switching control valve and pressure control valve are repeatedly reciprocated during the testing process to eliminate occasional jamming of the oil pump switching control valve and pressure control valve.

[0014] According to another specific embodiment of the present invention, the active diagnosis method disclosed in the embodiment of the present invention includes the following active diagnosis steps: when it is determined that at least one of error 1, error 2, error 3, error 4, and error 5 has occurred, then the process repeats step S1.

[0015] By adopting the above approach, the diagnostic steps are repeated to further identify errors, thereby eliminating occasional diagnostic inaccuracies and improving the accuracy of the proactive diagnostic process.

[0016] According to another specific embodiment of the present invention, the active diagnostic method disclosed in the embodiment of the present invention repeats step S1 less than 3 times.

[0017] According to another specific embodiment of the present invention, the active diagnosis method disclosed in the embodiment of the present invention further includes the active diagnosis step as follows:

[0018] When error 1 or error 5 occurs, record error 1 or error 5;

[0019] When error 2 or error 4 occurs, request the continuously variable transmission pulley system to control the speed ratio change rate to be less than the change rate threshold in order to avoid requesting the maximum main oil flow rate.

[0020] When error 3 occurs, a request is made to control the engine torque to be less than the torque threshold, which is the maximum torque that can provide clamping force during torque transmission.

[0021] Using the above approach, based on the diagnostic results, a request is made to the transmission system to perform appropriate processing, thereby protecting the transmission hardware from further damage.

[0022] According to another specific embodiment of the present invention, the active diagnostic method disclosed in the embodiment of the present invention has a maximum current value of 1000mA and a minimum current value of 0mA for the pressure control valve; the maximum current value of the oil pump switching control valve is 1000mA and the minimum current value of the oil pump switching control valve is 0mA.

[0023] According to another specific embodiment of the present invention, the active diagnostic method disclosed in the present invention has a minimum threshold of 2 bar ± 0.5 bar for main hydraulic pressure; a maximum threshold of 60 bar for main hydraulic pressure; and an intermediate threshold range of 8 to 14 bar for main hydraulic pressure.

[0024] The present invention also provides an active diagnostic system for a continuously variable transmission (CVT) main hydraulic system, used to execute the active diagnostic method provided by the present invention. The active diagnostic system includes:

[0025] Two oil pumps, both connected to the main oil circuit;

[0026] Oil pump switching control valve, which is connected to two oil pumps, is used to control the switching of the working modes of the two oil pumps;

[0027] Pressure control valve, which is connected to the main oil circuit, is used to control the main oil flow rate in the main oil circuit;

[0028] Pressure sensor, connected to the main oil circuit, is used to detect the main oil pressure;

[0029] The control unit activates the active diagnostic system to perform active diagnostic steps. The control unit is connected to the oil pump switching control valve and the pressure control valve to control their current. The control unit is also connected to a pressure sensor to collect the main oil pressure. The control unit controls the current of the oil pump switching control valve and the pressure control valve, and determines whether there is an error in the system oil pressure based on the main oil pressure.

[0030] The pressure control valve current is set to its maximum value to request the minimum main oil pressure; the oil pump switching control valve current is set to its maximum value to request the minimum main oil flow rate; if the main oil pressure cannot reach the minimum threshold, error 1 or error 5 is determined to have occurred.

[0031] The pressure control valve current is set to its maximum value to request the minimum main oil pressure; the oil pump switching control valve current is set to its minimum value to request the maximum main oil flow rate; if the main oil pressure is not within the intermediate threshold range, error 2 or error 4 is determined to have occurred.

[0032] The pressure control valve current is set to the minimum value to request the maximum main oil pressure; the oil pump switching control valve current is set to the minimum value to request the maximum main oil flow rate; if the main oil pressure cannot reach the highest threshold, error 3 is determined to have occurred.

[0033] If none of errors 1, 2, 3, 4, or 5 occur, the oil pressure of the continuously variable transmission (CVT) main hydraulic system is considered normal.

[0034] By adopting the above scheme, the active diagnostic method provided by the present invention is implemented through the system, which utilizes the hydraulic principle of the main hydraulic system and combines it with the main hydraulic sensor to realize active diagnostic testing of the hydraulic system composed of the main hydraulic pressure control valve and the oil pump switching control valve.

[0035] According to another specific embodiment of the present invention, the active diagnostic method disclosed in this embodiment includes a control unit comprising a recording module; the control unit is connected to a continuously variable transmission (CVT) pulley system to send requests to control the speed ratio change rate of the CVT pulley system; the control unit is also connected to an engine control system to send requests to control the engine torque; wherein,

[0036] When error 1 or error 5 occurs, the logging module records error 1 or error 5.

[0037] When error 2 or error 4 occurs, the control unit requests the continuously variable transmission pulley system to control the speed ratio change rate to be less than the change rate threshold in order to avoid requesting the maximum main oil flow rate.

[0038] When error 3 occurs, the control unit requests the engine control system to control the engine torque to be less than the torque threshold, which is the maximum torque that can provide clamping force during torque transmission.

[0039] Using the above approach, the system also requests the transmission system to perform corresponding processing based on the diagnostic results, thereby protecting the transmission hardware from further damage.

[0040] According to another specific embodiment of the present invention, the active diagnostic method disclosed in the embodiment of the present invention uses a constant-height solenoid valve as the oil pump switching control valve, which is connected to two oil pumps through the switching valve; and a constant-height solenoid valve as the pressure control valve, which is connected to the main oil circuit through a pressure regulating valve.

[0041] The beneficial effects of this invention are:

[0042] This invention provides an active diagnostic method and system for the main hydraulic system of a continuously variable transmission (CVT). Through multi-stage testing, it achieves active diagnostic testing of the CVT's main hydraulic system. Utilizing the hydraulic principle of the main hydraulic system and combining it with a main hydraulic pressure sensor, it performs active diagnostic testing on the hydraulic system composed of the main hydraulic pressure control valve and the oil pump switching control valve. Specifically, by setting specific currents for the oil pump switching control valve and the pressure control valve of the main hydraulic system, and combining this with the detection of changes in the main hydraulic pressure, it diagnoses and tests the highest and lowest pressures of the main hydraulic system, as well as whether the oil pump switching control valve has switched directions. Based on the diagnostic results, measures can be taken to intervene in the control system in advance to protect the transmission hardware from further damage, thus improving system reliability. Furthermore, during the testing process, the oil pump switching control valve and the pressure control valve are repeatedly actuated to eliminate occasional jamming phenomena in these valves and to further confirm any faults that have occurred. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the power transmission of the main hydraulic system of a continuously variable transmission (CVT).

[0044] Figure 2 This is a flowchart of the active diagnosis method of Embodiment 1 of the present invention;

[0045] Figure 3 This is a schematic diagram of the current change of the pressure control valve in the active diagnostic method of Embodiment 1 of the present invention;

[0046] Figure 4 This is a schematic diagram of the current change of the oil pump switching control valve in the active diagnostic method of Embodiment 1 of the present invention;

[0047] Figure 5 This is a schematic diagram illustrating the change in main oil pressure under normal conditions in the active diagnostic method of Embodiment 1 of the present invention;

[0048] Figure 6 This is a schematic diagram of the active diagnostic system according to Embodiment 1 of the present invention.

[0049] Explanation of reference numerals in the attached figures:

[0050] 1: Engine; 2: Hydraulic torque converter; 3: D / R clutch; 4: Continuously variable transmission pulley system; 5: Wheel end;

[0051] 10: First oil pump; 20: Second oil pump; 30: Oil pump switching control valve; 40: Pressure control valve; 50: Pressure sensor; 60: Main oil circuit; 70: Switching valve; 80: Pressure regulating valve; 90: Pressure reducing valve. Detailed Implementation

[0052] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Although the description of the present invention is presented in conjunction with preferred embodiments, this does not mean that the features of the invention are limited to these embodiments. On the contrary, the purpose of describing the invention in conjunction with embodiments is to cover other options or modifications that may be derived based on the claims of the present invention. To provide a deep understanding of the invention, many specific details will be included in the following description. The invention may also be implemented without using these details. Furthermore, to avoid confusion or obscuring the focus of the invention, some specific details will be omitted in the description. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0053] It should be noted that in this specification, similar reference numerals and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0054] In the description of this embodiment, 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 accompanying drawings, or the orientation or positional relationship that the product of the invention is usually placed in during use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the present invention.

[0055] The terms “first”, “second”, etc., are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0056] In the description of this embodiment, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set up," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this embodiment based on the specific circumstances.

[0057] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0058] Example 1

[0059] This invention provides an active diagnostic method for the main hydraulic system of a continuously variable transmission (CVT), wherein... Figure 1The diagram illustrates the power transmission process of a continuously variable transmission (CVT), where arrows indicate the direction of power transmission. Power is output from engine 1 to the hydraulic torque converter 2 (which has a lock-up clutch function), then to the forward / reverse control D / R clutch 3, and finally reaches the wheels 5 via the CVT pulley system 4 for torque and speed changes. The following section details the active diagnostic method used for the CVT's main hydraulic system, which includes the following steps:

[0060] Based on driving-related data, determine whether the engine idle speed is within the stable threshold range and whether the vehicle's current gear is in Park (P) or Neutral (N). If yes, activate the active diagnostic step; otherwise, continue the assessment. The stable threshold range refers to the range of idle speeds within which the engine can operate stably. Generally, the stable threshold range for gasoline engine idle speed is 750±100 rpm.

[0061] Figure 2 This is a flowchart of the pressure control valve in the active diagnostic method of the present invention. Figure 3 This is a schematic diagram showing the current change of the pressure control valve in the active diagnostic method of the present invention. Figure 4 This is a schematic diagram showing the current change in the oil pump switching control valve. Figure 5 This is a schematic diagram showing the change in main hydraulic pressure under normal conditions. The following is in conjunction with... Figures 2-5 The active diagnostic steps after activation are explained. The active diagnostic steps include:

[0062] S1: i.e. Figures 3-5 The first stage, in which, for example Figure 3 The control pressure valve current is set to its maximum value to request the minimum main oil pressure; as shown. Figure 4 The control valve current of the control oil pump is set to its maximum value to request the minimum main oil flow rate. If the maximum value remains stable, the main oil pressure is checked to see if it reaches the minimum threshold. If the minimum threshold is not reached, error 1 is identified. Figure 5 If the minimum threshold can be reached, proceed to step S2.

[0063] S2: that is Figures 3-5 The second and third stages are defined as follows: stage 2 is the control stage, and stage 3 is the detection stage; where, for example... Figure 3 The pressure control valve current shown remains constant at its maximum value in order to request the minimum main oil pressure; as Figure 4 The ramp control oil pump switches the control valve current to the minimum value to request the maximum main oil flow rate; at this time, the main oil pressure should increase, and it is checked whether the main oil pressure increases to the intermediate threshold range; if it is not within the intermediate threshold range, error 2 is determined to have occurred; if it is... Figure 5 If the value is within the intermediate threshold range, proceed to step S3.

[0064] S3: That is Figures 3-5The fourth and fifth stages are defined as follows: stage 4 is the control stage, and stage 5 is the detection stage; (e.g., ...) Figure 3 The ramp control pressure control valve current is set to the minimum value to request the maximum main oil pressure; as shown. Figure 4 The pump switching control valve current is kept at its minimum value to request the maximum main oil flow rate; at this time, the main oil pressure should increase to its maximum, and the system checks whether the main oil pressure reaches the maximum threshold; if it does not reach the maximum threshold, error 3 is determined to have occurred; if it does... Figure 5 If the highest threshold can be reached, proceed to step S4.

[0065] S4: That is Figures 3-5 Stages 6 and 7 are defined, with stage 6 being the control stage and stage 7 being the detection stage; where, for example... Figure 3 The ramp control pressure control valve current is increased to its maximum value to request the minimum main oil pressure; as shown Figure 4 The oil pump switching control valve current is kept at its minimum value to request the maximum main oil flow rate; at this time, the main oil pressure should decrease. It is checked whether the main oil pressure decreases to the intermediate threshold range. If it does not decrease to the intermediate threshold range, error 4 is determined to have occurred; if it does... Figure 5 If the threshold value reaches the intermediate range, proceed to step S5.

[0066] S5: That is Figures 3-5 Stages ⑧ and ⑨ are involved, with stage ⑧ being the control stage and stage ⑨ being the detection stage; (e.g., ...) Figure 3 The pressure control valve current shown remains constant at its maximum value in order to request the minimum main oil pressure; as Figure 4 The ramp control oil pump switches the control valve current to its maximum value to request the minimum main oil flow. At this time, the main oil pressure should decrease to its minimum. The system checks whether the main oil pressure reaches the minimum threshold. If it does not reach the minimum threshold, error 5 is determined to have occurred. Figure 5 If the minimum threshold is reached, the oil pressure of the continuously variable transmission (CVT) main hydraulic system is considered to be normal.

[0067] It should be noted that throughout the entire active diagnostic process, the engine idle speed must be kept within a stable threshold range, and the engine speed must be monitored within the corresponding range. The above diagnostic steps can be repeatedly verified; that is, after confirming any error, the diagnostic steps can be repeated for further confirmation. After each error is detected, you can return to the starting step for re-diagnosis and confirmation, perform corresponding processing to eliminate the error, or continue to the next step of diagnosis, recording the type of error. The maximum and minimum values ​​of the pressure control valve current and the oil pump switching control valve current are determined based on the specific device model of the continuously variable transmission's main hydraulic system, and correspondingly, the highest and lowest threshold values ​​of the main hydraulic pressure are determined. The common maximum current is around 1000mA, and the minimum is generally 0mA. The highest threshold value of the main hydraulic pressure is 60 bar or a pressure value greater than 60 bar, such as 65 bar or 70 bar; the lowest threshold value is close to 0, such as 2 bar; the intermediate threshold is a number between the highest and lowest threshold values, which can be calibrated and determined, such as 12 bar.

[0068] The above-described scheme achieves active diagnostic testing of the main hydraulic system of a continuously variable transmission (CVT) through multi-stage testing. Utilizing the hydraulic principles of the main hydraulic system and combining it with a main hydraulic pressure sensor, active diagnostic testing is performed on the hydraulic system composed of the main hydraulic pressure control valve and the oil pump switching control valve. Specifically, by setting specific currents for the oil pump switching control valve and pressure control valve of the main hydraulic system, and by detecting changes in the main hydraulic pressure, the system's highest and lowest pressures, as well as whether the oil pump switching control valve has switched directions, are diagnosed and tested. Based on the diagnostic results, measures can be taken to intervene in the control system in advance to protect the transmission hardware from further damage, thus improving system reliability. Furthermore, the testing process involves repeatedly reciprocating the oil pump switching control valve and pressure control valve to eliminate occasional jamming phenomena and further confirm any faults that may occur. The active diagnostic testing method provided by this invention is applicable to any conventional gasoline or hybrid vehicle equipped with a CVT.

[0069] According to another specific embodiment of the present invention, the active diagnosis step includes: when it is determined that at least one of error 1, error 2, error 3, error 4, and error 5 has occurred, then the process repeats step S1.

[0070] Specifically, after discovering a certain error, a request can be made to repeat diagnostic step S1; alternatively, after completing steps S1-S5, a request can be made to repeat diagnostic step S1 after discovering one or more errors. The maximum number of repeated diagnostic attempts can be determined based on the actual situation, for example, 1-5 times. Furthermore, before each request to repeat the diagnostic process, it is necessary to determine whether the vehicle condition meets the requirements, i.e., whether the engine idle speed is within the stable threshold range and whether the vehicle's current gear is in Park (P) or Neutral (N).

[0071] By adopting the above approach, the diagnostic steps are repeated to further identify errors, thereby eliminating occasional diagnostic inaccuracies and improving the accuracy of the proactive diagnostic process.

[0072] According to another specific embodiment of the present invention, the number of times step S1 is repeated is less than 3. That is, the number of times step S1 is repeated is 1 or 2, and the diagnosis is performed a maximum of 3 times in total, including the first diagnostic step.

[0073] According to another specific embodiment of the present invention, the active diagnostic step further includes: when error 1 or error 5 occurs, it indicates that the pressure control valve is stuck and cannot be controlled to the minimum main oil pressure, and this is simply recorded as error 1 or error 5.

[0074] When error 2 or error 4 occurs, it indicates that the oil pump switching control valve cannot switch normally, meaning that the dual oil pumps cannot operate normally. In this case, the continuously variable transmission pulley system flow control module is requested to control the speed ratio change rate to be less than the change rate threshold to avoid requesting the maximum main oil flow rate. That is, the change rate threshold corresponds to the speed ratio change rate when requesting the maximum main oil flow rate. Of course, a larger main oil flow rate can also be limited, and the set change rate threshold corresponds to the speed ratio change rate when requesting the larger main oil flow rate.

[0075] When error 3 occurs, it indicates that the system cannot reach the maximum pressure, which may prevent the clamping force from reaching the control target. Therefore, it requests that the engine torque be controlled to be less than the torque threshold. The torque threshold is the maximum torque that can provide clamping force during torque transmission, in order to prevent excessive torque transmission that would result in insufficient clamping force and slippage.

[0076] Using the above approach, based on the diagnostic results, a request is made to the transmission system to perform appropriate processing, thereby protecting the transmission hardware from further damage.

[0077] According to another specific embodiment of the present invention, the maximum value of the pressure control valve current is 1000mA, and the minimum value of the pressure control valve current is 0mA; the maximum value of the oil pump switching control valve current is 1000mA, and the minimum value of the oil pump switching control valve current is 0mA.

[0078] According to another specific embodiment of the present invention, the minimum threshold of the main hydraulic pressure is 2 bar ± 0.5 bar; the maximum threshold of the main hydraulic pressure is 60 bar; and the intermediate threshold range of the main hydraulic pressure is 8 to 14 bar.

[0079] Example 2

[0080] The present invention also provides an active diagnostic system for the main hydraulic system of a continuously variable transmission (CVT), used to execute the active diagnostic method of Embodiment 1, such as... Figure 6 As shown, the active diagnostic system includes two oil pumps 10 and 20, an oil pump switching control valve 30, a pressure control valve 40, a pressure sensor 50, and a control unit (not shown in the attached figure).

[0081] The system includes two hydraulic pumps: a first pump 10 and a second pump 20. Both pumps are connected to the main hydraulic circuit 60, as well as to the engine and fuel tank, to provide hydraulic oil via engine drive. A pump switching control valve 30 is connected to the first pump 10 and the second pump 20 to control the switching of their operating modes. The operating modes of the first pump 10 and the second pump 20 include: only the first pump 10 operating, only the second pump 20 operating, and both pumps operating simultaneously. A pressure sensor 50 is connected to the main hydraulic circuit 60 to detect the main hydraulic pressure.

[0082] The control unit can obtain driving-related data from vehicle control devices such as the Electronic Control Unit (ECU) to determine whether the engine idle speed is within a stable threshold range and whether the vehicle's current gear is in park or neutral. If so, it activates the active diagnostic system to perform active diagnostic steps; otherwise, it continues to acquire data and make judgments. Specifically, the control unit can be the automatic transmission control unit (TCU).

[0083] The control unit is connected to the oil pump switching control valve 30 and the pressure control valve 40 respectively to control the current of the oil pump switching control valve 30 and the pressure control valve 40; the control unit is also connected to the pressure sensor 50 to collect the main oil pressure; the control unit controls the current of the oil pump switching control valve 30 and the pressure control valve 40, and determines whether the system oil pressure is erroneous based on the main oil pressure.

[0084] In the active diagnostic steps of Example 1, the control unit controls the pressure control valve 40 to have the maximum current to request the minimum main oil pressure; it also controls the oil pump switching control valve 30 to have the maximum current to request the minimum main oil flow rate. If the main oil pressure cannot reach the minimum threshold, error 1 or error 5 is determined to have occurred. The control unit then controls the pressure control valve 40 to have the maximum current to request the minimum main oil pressure; it also controls the oil pump switching control valve 30 to have the minimum current to request the maximum main oil flow rate. If the main oil pressure is not within the intermediate threshold range, error 2 or error 4 is determined to have occurred. Finally, the control unit controls the pressure control valve 40 to have the minimum current to request the maximum main oil pressure; it also controls the oil pump switching control valve 30 to have the minimum current to request the maximum main oil flow rate. If the main oil pressure cannot reach the maximum threshold, error 3 is determined to have occurred. When errors 1, 2, 3, 4, and 5 do not occur, the oil pressure of the continuously variable transmission (CVT) main oil pressure system is determined to be normal.

[0085] By adopting the above scheme, the active diagnostic method provided by the present invention is implemented through the system, which utilizes the hydraulic principle of the main hydraulic system and combines it with the main hydraulic sensor to realize active diagnostic testing of the hydraulic system composed of the main hydraulic pressure control valve and the oil pump switching control valve.

[0086] According to another specific embodiment of the present invention, the control unit includes a recording module; the control unit is connected to the continuously variable transmission pulley system to send a request to control the speed ratio change rate of the continuously variable transmission pulley system, specifically by controlling the speed ratio change rate through flow rate; the control unit is also connected to the engine control system and sends a request to control the torque of the engine.

[0087] Specifically, when error 1 or error 5 occurs, the recording module records error 1 or error 5; when error 2 or error 4 occurs, the control unit requests the continuously variable transmission pulley system to control the speed ratio change rate to be less than the change rate threshold in order to avoid requesting the maximum main oil flow; when error 3 occurs, the control unit requests the engine control system to control the engine torque to be less than the torque threshold, which is the maximum torque that can provide clamping force during torque transmission.

[0088] Using the above approach, the system also requests the transmission system to perform corresponding processing based on the diagnostic results, thereby protecting the transmission hardware from further damage.

[0089] According to another specific embodiment of the present invention, such as Figure 6 As shown, the oil pump switching control valve 30 is a constant-height solenoid valve and is connected to two oil pumps 10 and 20 through the switching valve 70; the pressure control valve 40 is a constant-height solenoid valve and is connected to the main oil circuit through the pressure regulating valve 80.

[0090] Specifically, such as Figure 6As shown, one end of the switching valve 70 is connected to the output end of the oil pump switching control valve 30, and the other end is connected to the drain port of the pressure regulating valve 80. The oil pump switching control valve 30 controls the switching of the switching valve 70 through current changes. One end of the pressure regulating valve 80 is connected to the output end of the pressure control valve 40, and the other end is connected to the main oil circuit 60. The pressure control valve 40 controls the pressure regulating valve 80 to adjust the pressure of the main oil circuit 60 through current changes. The pressure regulating valve 80 is connected to the main oil circuit 60. When the main oil circuit 60 reaches the set pressure, excess hydraulic oil can be discharged through the pressure regulating valve 80.

[0091] It should be noted that the main oil circuit 60 may also be equipped with a pressure reducing valve 90, an oil pump switching control valve 30 and a pressure control valve 40 connected to a pressure regulating valve 80, and the pressure regulating valve 80 can provide a stable input pressure for the oil pump switching control valve 30 and the pressure control valve 40.

[0092] While the present invention has been illustrated and described with reference to certain preferred embodiments, those skilled in the art should understand that the above description is a further detailed explanation of the invention in conjunction with specific embodiments, and should not be construed as limiting the specific implementation of the invention to these descriptions. Various changes in form and detail can be made by those skilled in the art, including several simple deductions or substitutions, without departing from the spirit and scope of the invention.

Claims

1. An active diagnostic method for the main hydraulic system of a continuously variable transmission (CVT), characterized in that, The active diagnostic method includes the following steps: Determine if the engine idle speed is within a stable threshold range and if the vehicle's current gear is in park or neutral. If yes, activate the active diagnostic step; otherwise, continue the assessment. The active diagnostic steps include: S1: Control the pressure control valve current to the maximum value to request the minimum main oil pressure; control the oil pump switching control valve current to the maximum value to request the minimum main oil flow rate, and detect whether the main oil pressure reaches the minimum threshold; if the minimum threshold cannot be reached, it is determined that error 1 has occurred; if the minimum threshold can be reached, proceed to step S2. S2: The ramp control switches the oil pump switching control valve current to the minimum value to request the maximum main oil flow rate; detect whether the main oil pressure is within the intermediate threshold range; if it is not within the intermediate threshold range, it is determined that error 2 has occurred; if it is within the intermediate threshold range, proceed to step S3. S3: The ramp control current of the pressure control valve is reduced to the minimum value to request the maximum main oil pressure; the main oil pressure is checked to see if it reaches the highest threshold; if it cannot reach the highest threshold, an error 3 is determined to have occurred; if it can reach the highest threshold, proceed to step S4. S4: The ramp control current of the pressure control valve is brought to its maximum value to request the minimum main oil pressure. The main oil pressure is checked to see if it is within the intermediate threshold range. If it is not within the intermediate threshold range, error 4 is determined to have occurred. If it is within the intermediate threshold range, proceed to step S5. S5: The ramp control switches the oil pump switching control valve current to the maximum value to request the minimum main oil flow rate, and detects whether the main oil pressure reaches the minimum threshold. If the minimum threshold cannot be reached, it is determined that error 5 has occurred; if the minimum threshold is reached, it is determined that the oil pressure of the continuously variable transmission main oil pressure system is normal.

2. The active diagnostic method as described in claim 1, characterized in that, The active diagnostic steps include: If at least one of the following errors occurs, step S1 is repeated.

3. The active diagnostic method as described in claim 2, characterized in that, The number of times step S1 is repeated is less than 3.

4. The active diagnostic method according to any one of claims 1-3, characterized in that, The active diagnostic steps also include: When error 1 or error 5 occurs, record error 1 or error 5. When error 2 or error 4 occurs, the continuously variable transmission pulley system is requested to control the speed ratio change rate to be less than the change rate threshold in order to avoid requesting the maximum main oil flow rate. When error 3 occurs, a request is made to control the engine torque to be less than a torque threshold, which is the maximum torque that can provide clamping force during torque transmission.

5. The active diagnostic method as described in claim 4, characterized in that, The maximum value of the pressure control valve current is 1000mA, and the minimum value of the pressure control valve current is 0mA. The maximum current of the oil pump switching control valve is 1000mA, and the minimum current of the oil pump switching control valve is 0mA.

6. The active diagnostic method as described in claim 5, characterized in that, The minimum threshold of the main hydraulic pressure is 2 bar ± 0.5 bar; the maximum threshold of the main hydraulic pressure is 60 bar; and the intermediate threshold range of the main hydraulic pressure is 8 to 14 bar.

7. An active diagnostic system for the main hydraulic system of a continuously variable transmission (CVT), characterized in that, For performing the active diagnostic method according to any one of claims 1-6, the active diagnostic system comprises: Two oil pumps, both of which are connected to the main oil circuit; An oil pump switching control valve is connected to the two oil pumps and is used to control the switching of the operating modes of the two oil pumps. A pressure control valve, which is connected to the main oil circuit, is used to control the main oil flow rate of the main oil circuit; A pressure sensor, which is connected to the main oil circuit, is used to detect the main oil pressure. The control unit activates the active diagnostic system to perform active diagnostic steps. The control unit is connected to the oil pump switching control valve and the pressure control valve to control their current. The control unit is also connected to the pressure sensor to collect the main oil pressure. The control unit controls the current of the oil pump switching control valve and the pressure control valve, and determines whether a system oil pressure error has occurred based on the main oil pressure. The pressure control valve current is controlled to the maximum value to request the minimum main oil pressure; the oil pump switching control valve current is controlled to the maximum value to request the minimum main oil flow rate; if the main oil pressure cannot reach the minimum threshold, error 1 or error 5 is determined to have occurred. The pressure control valve current is controlled to the maximum value to request the minimum main oil pressure; the oil pump switching control valve current is controlled to the minimum value to request the maximum main oil flow rate; when the main oil pressure is not within the intermediate threshold range, error 2 or error 4 is determined to have occurred. The pressure control valve current is controlled to the minimum value to request the maximum main oil pressure; the oil pump switching control valve current is controlled to the minimum value to request the maximum main oil flow rate; if the main oil pressure cannot reach the maximum threshold, an error 3 is determined to have occurred. If none of the above errors 1, 2, 3, 4, and 5 occur, the oil pressure of the continuously variable transmission (CVT) main hydraulic system is considered normal.

8. The active diagnostic system as described in claim 7, characterized in that, The control unit includes a recording module; the control unit is connected to the continuously variable transmission (CVT) pulley system to send requests to control the speed ratio change rate of the CVT pulley system; the control unit is also connected to the engine control system and sends requests to control the torque of the engine; wherein, When error 1 or error 5 occurs, the recording module records error 1 or error 5. When error 2 or error 4 occurs, the control unit requests the continuously variable transmission pulley system to control the speed ratio change rate to be less than the change rate threshold in order to avoid requesting the maximum main oil flow rate; When error 3 occurs, the control unit requests the engine control system to control the engine torque to be less than a torque threshold, which is the maximum torque that can provide clamping force during torque transmission.

9. The active diagnostic system as described in claim 8, characterized in that, The oil pump switching control valve is a constant-pressure type solenoid valve and is connected to the two oil pumps through the switching valve; the pressure control valve is a constant-pressure type solenoid valve and is connected to the main oil circuit through the pressure regulating valve.

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