Method for testing gear shifting performance of automatic transmission

Abstract

The present application relates to the field of automatic gearbox, and particularly relates to a gear shifting performance test method for automatic gearbox, in the gear shifting process corresponding to each gear of the automatic gearbox, the information collected by various sensors of the automatic gearbox is used to determine whether the gear shifting time and synchronization time of each target gear meet the requirements, whether the automatic gearbox has gear shifting jam is judged through the gear shifting time, and whether the automatic gearbox has synchronizer jam is judged through the synchronization time, the accuracy of the bench gear shifting performance test is improved, the gear shifting performance of the automatic gearbox does not need to be repeatedly verified through vehicle test, and the test cost is greatly reduced.

Description

Technical Field

[0001] This invention relates to the field of automatic transmissions, and more specifically to a method for testing the shifting performance of automatic transmissions. Background Technology

[0002] Automatic transmissions, as a power transmission device capable of automatic gear shifting, are widely used in the automotive industry, compared to manual transmissions. Their shifting performance directly affects the smoothness of gear changes, thus impacting passenger comfort and the likelihood of traffic accidents. Therefore, automatic transmissions typically undergo a series of shifting performance tests before leaving the factory to ensure they meet factory requirements.

[0003] Currently, the shift performance testing of automatic transmissions before they leave the factory is divided into two stages: bench testing and vehicle testing. Bench testing for shift performance is not very accurate, so automatic transmissions that fail the bench test stage need to be installed in a vehicle for vehicle testing to re-verify whether their shift performance meets factory requirements.

[0004] It is evident that traditional shift performance testing is time-consuming and labor-intensive. Improving the accuracy of bench shift performance testing and reducing testing costs has always been an urgent problem to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing a method for testing the shifting performance of automatic transmissions. During the shifting process of each gear, information collected by various sensors built into the automatic transmission is used to determine whether there is shifting sticking by using shifting time and whether there is synchronizer sticking by using synchronization time. This improves the accuracy of bench shifting performance testing, eliminates the need for repeated vehicle testing to verify the shifting performance of the automatic transmission, and greatly reduces testing costs.

[0006] The objective of this invention is achieved through the following approach:

[0007] A method for testing the shift performance of an automatic transmission, wherein during the shifting process of each gear in the automatic transmission, the shift time of each gear is determined sequentially according to the following method to determine whether it meets the requirements:

[0008] The time required for the shift fork to move from the neutral position to the position corresponding to the target gear is taken as the shift time of the target gear, and this shift time is compared with the shift time threshold corresponding to the target gear.

[0009] Preferably, the shift time is obtained according to the following steps:

[0010] 1-1) If the real-time displacement value of the shift fork at a certain moment satisfies the following shift start judgment formula, then that moment shall be taken as the shift start moment:

[0011] |Real-time displacement value of shift fork - Standard value of neutral position| ≥ Shift start judgment error threshold;

[0012] 1-2) After the start of the gear shift, if the real-time displacement value of the shift fork at a certain moment satisfies the following formula for determining the end of the gear shift, that moment shall be taken as the end of the gear shift:

[0013] |Real-time displacement value of shift fork - Standard value of position corresponding to target gear| ≤ Shift end judgment error threshold;

[0014] 1-3) The time interval between the start and end of the gear shift is taken as the shift time for the target gear.

[0015] Preferably, the synchronization time of the target gear is determined in the same gear shifting process in the following manner to determine whether the requirements are met:

[0016] 2-1) If the rate of change of the input shaft speed is within the threshold range at a certain moment, that moment shall be taken as the synchronization start moment;

[0017] 2-2) After the synchronization start time, if the input shaft speed satisfies the following speed synchronization judgment formula, that time shall be taken as the synchronization end time:

[0018] |Input shaft speed - Output shaft speed × Speed ​​ratio corresponding to the target gear| ≤ Synchronization error threshold;

[0019] 2-3) The interval between the start and end times of synchronization is taken as the synchronization time of the target gear, and the synchronization time is compared with the synchronization time threshold corresponding to the target gear.

[0020] Preferably, the real-time displacement value of the shift fork is less than or equal to the shift fork displacement threshold during a single gear shift.

[0021] Preferably, the shift fork displacement threshold corresponding to the target gear of the automatic transmission is obtained according to the following formula:

[0022] |Standard value of neutral position - Standard value of target gear position| = |Shift fork displacement threshold|.

[0023] Preferably, the standard value of the target gear position and the standard value of the neutral position are both determined by the shift fork in gear position through self-learning.

[0024] Preferably, the standard values ​​for the target gear position and the neutral position are obtained through calibration tests.

[0025] Preferably, the real-time displacement value of the shift fork is acquired by the shift fork displacement sensor integrated into the automatic transmission, and the signal acquisition frequency of the shift fork displacement sensor is 100Hz.

[0026] Preferably, the input shaft speed and output shaft speed are acquired by corresponding input shaft speed sensors and output shaft speed sensors, respectively, and the signal acquisition frequency of the input shaft speed sensors and output shaft speed sensors is 100Hz.

[0027] Preferably, the rate of change of the input shaft speed is calculated according to the following formula:

[0028] Input shaft speed change rate = (current input shaft speed - previous input shaft speed) / (current time - previous time).

[0029] The beneficial effects of this invention are as follows:

[0030] The time required for the shift fork to move from the neutral position to the position corresponding to the target gear is taken as the shift time of the target gear. This makes the collected shift time consistent with the actual driving conditions of a car, improves the accuracy of bench shift performance testing, and eliminates the need for full vehicle testing, saving time and effort.

[0031] The shift time is obtained according to the following steps:

[0032] 1-1) If the real-time displacement value of the shift fork at a certain moment satisfies the following shift start judgment formula, then that moment shall be taken as the shift start moment:

[0033] |Real-time displacement value of shift fork - Standard value of neutral position| ≥ Shift start judgment error threshold;

[0034] 1-2) After the start of the gear shift, if the real-time displacement value of the shift fork at a certain moment satisfies the following formula for determining the end of the gear shift, that moment shall be taken as the end of the gear shift:

[0035] |Real-time displacement value of shift fork - Standard value of position corresponding to target gear| ≤ Shift end judgment error threshold;

[0036] 1-3) The time interval between the start and end of the gear shift is taken as the shift time for the target gear.

[0037] The real-time displacement value of the shift fork is acquired by the shift fork displacement sensor integrated into the automatic transmission, and the signal acquisition frequency of the shift fork displacement sensor is 100Hz.

[0038] The shift time is calculated by using information collected by various high-precision sensors built into the automatic transmission. No additional sensors are needed, which saves time and effort and greatly improves the accuracy of the test.

[0039] Since the standard values ​​for the positions of each gear in different automatic transmissions are not exactly the same, the standard values ​​for the target gear position and the neutral position should be determined by self-learning of the shift fork in the gear position or by calibration test. By using the shift fork in the gear position to self-learn in advance, the standard values ​​for the positions of each gear in the automatic transmission to be tested can be determined, which further ensures that the final test results are consistent with the real working conditions and improves the test accuracy of bench shifting performance testing.

[0040] To comprehensively consider the factors affecting the shifting performance of the automatic transmission under real-world vehicle operating conditions, the synchronization time of the target gear is determined during the shifting process for each gear using the following method to ensure it meets the requirements:

[0041] 2-1) If the rate of change of the input shaft speed is within the threshold range at a certain moment, that moment shall be taken as the synchronization start moment;

[0042] 2-2) After the synchronization start time, if the input shaft speed satisfies the following speed synchronization judgment formula, that time shall be taken as the synchronization end time:

[0043] |Input shaft speed - Output shaft speed × Speed ​​ratio corresponding to the target gear| ≤ Synchronization error threshold;

[0044] 2-3) The interval between the start and end times of synchronization is taken as the synchronization time of the target gear, and the synchronization time is compared with the synchronization time threshold corresponding to the target gear.

[0045] Preferably, the real-time displacement value of the shift fork is less than or equal to the shift fork displacement threshold during a single gear shift.

[0046] Preferably, the shift fork displacement threshold corresponding to the target gear of the automatic transmission is obtained according to the following formula:

[0047] |Standard value of neutral position - Standard value of target gear position| = |Shift fork displacement threshold|.

[0048] The input shaft speed and output shaft speed are acquired by the corresponding input shaft speed sensor and output shaft speed sensor respectively, and the signal acquisition frequency of the input shaft speed sensor and output shaft speed sensor is 100Hz.

[0049] The synchronization time is the time required for the synchronizer to synchronize the speeds of the input and output shafts. This invention also uses information collected by various high-precision sensors built into the automatic transmission to calculate the shift time. No additional sensors are required, which saves time and effort and greatly improves the accuracy of the test. It fully considers the factors that affect the shift performance of the automatic transmission in the actual working conditions of the vehicle and avoids the drawback of low accuracy in traditional bench shift performance tests.

[0050] In summary, the advantages of this invention are as follows:

[0051] (1) Traditional bench shift performance testing simply reads the shift signal from the TCU and uses the moment the TCU sends the signal as the shift start time. However, using the moment the shift fork actually begins to move as the shift start time is more in line with real-world operating conditions. The moment the TCU sends the shift signal differs from the moment the shift fork actually begins to move, which does not reflect real-world conditions. Traditional bench shift performance testing ignores practical factors that are highly prone to error, such as the transmission time of electrical signals. Therefore, the test results from the traditional bench shift performance testing phase often differ significantly from the verification results from the whole-vehicle shift performance verification testing phase.

[0052] This invention aims to avoid the shortcomings of traditional bench shifting performance testing. It not only uses the moment when the shift fork actually begins to move as the shift start moment, but also accurately determines the position standard value corresponding to each gear in advance through the shift fork's self-learning in the gear position. This eliminates various error factors to the greatest extent, making the entire test process as close as possible to the real working conditions and greatly improving the test accuracy.

[0053] (2) Traditional bench shift performance testing typically only uses shift time to determine whether there is any sticking during automatic transmission shifting, without considering that the quality of shift performance also affects synchronization time. Therefore, the test results often do not reflect the actual operating conditions of the automatic transmission in a vehicle. Research has shown that "shifting sticking" is also related to the synchronization process. It is not sufficient to quantify the shift performance of an automatic transmission solely by testing "shift time." The time required for the synchronizer to synchronize the input and output shaft speeds should also be recorded during the synchronization process. Incorporating synchronization time into the shift performance testing system is crucial to accurately reflect the shift performance of the transmission under test and further improve the accuracy of the test. Attached Figure Description

[0054] Figure 1 This is a flowchart of the present invention;

[0055] Figure 2 This is the process for obtaining the shift time described in this invention;

[0056] Figure 3 This describes the process for obtaining the synchronization time as described in this invention. Detailed Implementation

[0057] like Figures 1 to 3 As shown, a method for testing the shift performance of an automatic transmission involves determining whether the shift time of each gear meets the requirements during the shifting process of each gear in the automatic transmission, in the following manner:

[0058] The time required to move the shift fork from the neutral position to the position corresponding to the target gear is taken as the shift time of the target gear, and this shift time is compared with the shift time threshold corresponding to the target gear.

[0059] Moreover, during the shift process corresponding to each gear of the automatic transmission, the synchronizing time of the target gear is determined in sequence in the shift process corresponding to each gear in the following manner:

[0060] ① If the change rate of the input shaft speed at a certain moment is within the range of the change rate threshold, this moment is taken as the starting moment of synchronization;

[0061] In this embodiment, the change rate of the input shaft speed is calculated according to the following formula:

[0062] Change rate of input shaft speed = (current input shaft speed - input shaft speed at the previous moment) / (current moment - previous moment).

[0063] Of course, the change rate of the input shaft speed can also adopt the instantaneous change rate of the input shaft speed:

[0064] In a two-dimensional coordinate system with time as the horizontal axis and the input shaft speed as the vertical axis, for the relationship curve representing the change of the input shaft speed with time, a tangent is made to the curve at the point corresponding to the current moment on the curve, and the slope of this tangent is the instantaneous change rate of the input shaft speed at the current moment.

[0065] ② After the starting moment of synchronization, if the input shaft speed satisfies the following speed synchronization judgment formula, this moment is taken as the ending moment of synchronization:

[0066] |input shaft speed - output shaft speed × speed ratio corresponding to the target gear| ≤ synchronization error threshold;

[0067] ③ The interval time between the starting moment of synchronization and the ending moment of synchronization is taken as the synchronizing time of the target gear, and this synchronizing time is compared with the synchronizing time threshold corresponding to the target gear.

[0068] The shift time threshold and the synchronizing time threshold are usually obtained in advance by the automatic transmission manufacturer through calibration tests, and the shift time threshold and the synchronizing time threshold meet the national and industrial standard regulations. When conducting a bench shift performance test on the automatic transmission according to the above method, the shift time and the synchronizing time corresponding to each gear can be tested simultaneously during the shift process corresponding to that gear. Whether the shift time and the synchronizing time of this automatic transmission are qualified depends on whether the shift time is greater than the shift time threshold and whether the synchronizing time is greater than the synchronizing time threshold. If it is greater, it is unqualified; if it is less than or equal to, it meets the requirements.

[0069] In this embodiment, the shift time is obtained according to the following steps:

[0070] ① If the real-time displacement value of the shift fork at a certain moment satisfies the following shift start judgment formula, then that moment shall be taken as the shift start moment:

[0071] |Real-time displacement value of shift fork - Standard value of neutral position| ≥ Shift start judgment error threshold;

[0072] ② After the start of the gear shift, if the real-time displacement value of the shift fork at a certain moment satisfies the following formula for determining the end of the gear shift, that moment shall be taken as the end of the gear shift:

[0073] |Real-time displacement value of shift fork - Standard value of position corresponding to target gear| ≤ Shift end judgment error threshold;

[0074] ③ The time interval between the start and end of the gear shift is taken as the shift time for the target gear.

[0075] The real-time displacement value of the shift fork is less than or equal to the shift fork displacement threshold during a single gear shift. The shift fork displacement threshold corresponding to the target gear of the automatic transmission is obtained according to the following formula:

[0076] |Standard value of neutral position - Standard value of target gear position| = |Shift fork displacement threshold|.

[0077] Typically, the standard values ​​for the target gear position and the neutral position can be determined by the shift fork's self-learning in gear position, or they can be obtained through calibration tests. In this embodiment, the standard values ​​for the target gear position and the neutral position are both determined by the shift fork's self-learning in gear position.

[0078] In this embodiment, the input shaft speed and output shaft speed are acquired by corresponding input shaft speed sensors and output shaft speed sensors, respectively. The signal acquisition frequency of the input shaft speed sensors and output shaft speed sensors is 100Hz. The real-time displacement value of the shift fork is acquired by the shift fork displacement sensor built into the automatic transmission. The signal acquisition frequency of this shift fork displacement sensor is 100Hz, which can detect the slight movement of the shift fork with extremely high accuracy. During the shifting process, the real-time displacement value of the shift fork, as well as the input shaft speed and output shaft speed, are continuously and cyclically judged, which greatly improves the test accuracy and avoids the problem of "the shift fork has started to move, but the sensor has not detected the movement of the shift fork, resulting in a large error in the calculated shifting time".

[0079] It is worth noting that the shift start judgment error threshold, shift end judgment error threshold, synchronization error threshold, and change rate threshold mentioned above are all empirical values. Before conducting bench shift performance tests on the automatic transmission using the above method, the shift start judgment error threshold, shift end judgment error threshold, synchronization error threshold, and change rate threshold should be set according to calibration tests or the testing experience of technicians. Then, the shift performance of each gear of the automatic transmission should be tested using the above method.

[0080] In this embodiment, the shift start judgment error threshold is set to 1.5mm, the shift end judgment error threshold is set to 0.5mm, the synchronization error threshold is set to 3RPM, and the change rate threshold is set to 5rpm / 0.1s.

[0081] In addition to the above thresholds, in order to ensure the smooth progress of automatic transmission bench performance testing, it is also necessary to set a synchronizer de-loop failure alarm threshold. When the input shaft speed and output shaft speed of the automatic transmission cannot reach a synchronized state for a long time during the shifting process, an alarm will be set to remind the staff to troubleshoot the fault and ensure test safety.

[0082] In addition to setting the synchronizer loop-breaking failure alarm threshold, it is also necessary to set the gear jamming alarm threshold. If a prolonged gear jamming occurs during gear shifting, an alarm will be triggered to remind staff to troubleshoot the problem and ensure test safety.

[0083] In summary, if the shifting performance of an automatic transmission does not meet the requirements, the main issues are as follows:

[0084] ① Gear shifting stuck: The gear shifting time exceeds the gear shifting time threshold, or the synchronization time exceeds the synchronization time threshold;

[0085] ② Synchronizer loop unblocking failure, that is, the input shaft speed and the output shaft speed cannot be synchronized, and the synchronization time exceeds the synchronizer loop unblocking failure alarm threshold;

[0086] ③ Gear jamming, meaning the shift fork cannot reach the target position and the shifting time exceeds the gear jamming alarm threshold;

[0087] Experiments have shown that after bench testing the automatic transmission using this invention, and then using a full vehicle test to repeatedly verify the automatic transmission's shifting performance, the test accuracy rate is as high as 99.9%, which is far more accurate than the traditional bench test, which has an accuracy rate of only 90% at most.

[0088] Therefore, compared with traditional bench shift performance testing, this invention completely eliminates the need for subsequent vehicle testing to repeatedly verify the shift performance of the automatic transmission, greatly saving testing costs.

[0089] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications made to the present invention by those skilled in the art without departing from the spirit of the present invention shall fall within the protection scope of the present invention.

Claims

1. A shift performance test method for an automatic transmission, characterized by, Includes the following steps: 1) During the shifting process of each gear in an automatic transmission, determine whether the shift time of each gear meets the requirements in the following manner: The time required for the shift fork to move from the neutral position to the position corresponding to the target gear is taken as the shift time, and this shift time is compared with a shift time threshold. The shift time is obtained according to the following steps: 1-1) If the real-time displacement value of the shift fork at a certain moment satisfies the following shift start judgment formula, then that moment shall be taken as the shift start moment: |Real-time displacement value of shift fork - Standard value of neutral position| ≥ Shift start judgment error threshold; 1-2) After the start of the gear shift, if the real-time displacement value of the shift fork at a certain moment satisfies the following formula for determining the end of the gear shift, that moment shall be taken as the end of the gear shift: |Real-time displacement value of shift fork - Standard value of position corresponding to target gear| ≤ Shift end judgment error threshold; The real-time displacement value of the shift fork is less than or equal to the shift fork displacement threshold during a single gear shift. The shift fork displacement threshold corresponding to the target gear of the automatic transmission is obtained according to the following formula: |Standard value of neutral position - Standard value of target gear position| = |Shift fork displacement threshold|; The target gear position standard value and the neutral position standard value are both determined by self-learning or calibration test of the shift fork in gear position. 1-3) The time interval between the start and end of the gear shift is taken as the shift time for the target gear; 2) Determine whether the synchronization time of the target gear meets the requirements during the same gear shift process using the following methods: 2-1) If the rate of change of the input shaft speed is within the threshold range at a certain moment, that moment shall be taken as the synchronization start moment; 2-2) After the synchronization start time, if the input shaft speed satisfies the following speed synchronization judgment formula, that time shall be taken as the synchronization end time: |Input shaft speed - Output shaft speed × Speed ​​ratio corresponding to the target gear| ≤ Synchronization error threshold; 2-3) The interval between the synchronization start time and the synchronization end time is taken as the synchronization time, and this synchronization time is compared with the synchronization time threshold.

2. The method for testing the shifting performance of an automatic transmission according to claim 1, characterized in that, The real-time displacement value of the shift fork is acquired by the shift fork displacement sensor integrated into the automatic transmission, and the signal acquisition frequency of the shift fork displacement sensor is 100Hz.

3. The method for testing the shifting performance of an automatic transmission according to claim 1, characterized in that, The input shaft speed and output shaft speed are acquired by the corresponding input shaft speed sensor and output shaft speed sensor respectively, and the signal acquisition frequency of the input shaft speed sensor and output shaft speed sensor is 100Hz.

4. The method for testing the shifting performance of an automatic transmission according to claim 1, characterized in that, The rate of change of the input shaft speed is calculated according to the following formula: Input shaft speed change rate = (current input shaft speed - previous input shaft speed) / (current time - previous time).

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