Correction method of clutch torque transmission in commercial vehicles

Abstract

The present invention relates to a method for correcting the torque transmission of a clutch of a commercial vehicle: collecting the movement distance of the first clutch, the stable speed of a first transmission shaft, and the first clutch displacement-torque point; the clutch is completely separated; the transmission gear is engaged; the clutch is moved in the engagement direction again; the first clutch displacement-engine output net torque is obtained; the second clutch displacement-engine output net torque is obtained; the first clutch displacement-engine output net torque point is corrected to obtain the second clutch displacement-engine output net torque point; the first clutch displacement-torque point is corrected; and the method is repeated until all gears are corrected. The present invention corrects a torque transmission curve in the power system of a commercial vehicle that represents the actual situation of the current vehicle clutch.

Description

Technical Field

[0001] The invention relates to the technical field of commercial vehicle powertrain systems, and in particular to a method for correcting clutch torque transmission of a commercial vehicle. Background Art

[0002] The individual differences and wear of the clutch will cause the torque transmission characteristics to attenuate or shift. Inaccurate torque transmission will lead to reduced vehicle starting and shifting performance. Therefore, it is necessary to correct the torque transmission characteristics of the clutch in use for use by the TCU so that the vehicle can obtain good torque transmission during operation.

[0003] In order to solve the above problems, the prior art generally controls the clutch target position based on the transmission twist curve set at the factory;

[0004] The most typical prior art is a Chinese patent application filed by Wabco Vehicle Control Systems (China) Co., Ltd., with Teng Yutang as the inventor, entitled “A clutch target position control method based on a clutch torsion curve”, with application number 201611011131.5, which discloses a clutch target position control method based on a clutch torsion curve, comprising the following steps:

[0005] The target torque calculation module calculates the driver's target clutch torque according to the accelerator pedal position; the engine speed controller calculates the corresponding engine target speed according to the driver's target clutch torque; the change rate limiting module calculates the allowable clutch torque change rate according to the difference between the calculated engine target speed and the current engine speed, and limits the currently calculated driver's target clutch torque to obtain the clutch target torque after limitation. The transmission controller calculates the clutch target position according to the clutch torque curve interpolation based on the limited clutch target torque. The control method described in this invention estimates the clutch target position according to the torque required by the driver, taking into account the difference in torque transmission sensitivity of the clutch at different positions, and ensuring the driver's linear and stable vehicle control sense.

[0006] The defects of the prior art represented by the above invention application are as follows:

[0007] Although the existing technology takes into account the difference in torque transmission sensitivity of the clutch at different positions, its method of controlling the target position of the clutch is based on the clutch transmission twist curve, which is the factory setting of the clutch. During the operation of the powertrain system, the friction plate gradually wears and even burns; the deformation of the flywheel and the pressure plate will also affect the completeness of clutch separation and the torque transmission capacity; therefore, when the above situation occurs, the torque transmission performance of the clutch changes, and ultimately leads to a change in the transmission twist curve. At this time, control based on the factory setting transmission twist curve will lead to inaccurate control results. Summary of the invention

[0008] In view of the above problems, the present invention provides a method for correcting clutch torque transmission of commercial vehicles, the purpose of which is to finally correct a torque transmission curve representing the actual situation of the current vehicle clutch in the power system of the commercial vehicle.

[0009] To solve the above problems, the technical solution provided by the present invention is:

[0010] A method for correcting clutch torque transmission of a commercial vehicle comprises the following steps:

[0011] S100. Collect the first clutch movement distance, the first transmission shaft stable speed, and the first clutch displacement-torque point; the first clutch movement distance is the distance between the clutch friction plates at the time of collection; the abscissa of the first clutch displacement-torque point is the first clutch movement distance, and the ordinate is 0;

[0012] S200. Disengage the clutch completely; then shift the transmission into the current gear;

[0013] S300. After the gearbox has completed the gear shift, the clutch is moved toward the engagement direction again;

[0014] S400. Obtain the first clutch displacement-engine output net torque; then adjust the distance between the clutch friction plates to obtain the second clutch displacement-engine output net torque; then correct the first clutch displacement-engine output net torque point according to the first clutch displacement-engine output net torque and the second clutch displacement-engine output net torque to obtain the second clutch displacement-engine output net torque point; the value of the abscissa of the first clutch displacement-engine output net torque point is the second clutch movement distance, and the value of the ordinate is the first clutch displacement-engine output net torque; the value of the abscissa of the second clutch displacement-engine output net torque point is the second clutch movement distance, and the value of the ordinate is the second clutch displacement-engine output net torque;

[0015] S500. Correcting the first clutch displacement-torque point;

[0016] S600. Compare the second clutch displacement-engine output net torque with the manually preset target clutch torque upper limit threshold; then perform the following operations according to the comparison result:

[0017] If the second clutch displacement-engine output net torque is less than the target clutch torque upper limit threshold, then the manually preset output net torque interval is added to the second clutch displacement-engine output net torque as the new first clutch displacement-engine output net torque, and then the process returns to and executes S100 again;

[0018] If the second clutch displacement-engine output net torque is not less than the target clutch torque upper limit threshold, the correction process for the current gear is completed and exited.

[0019] Preferably, the method further comprises the following steps:

[0020] S700. Repeat S100 to S600 until all gears are corrected, then exit the process of this correction method.

[0021] Preferably, S100 specifically includes the following steps:

[0022] S110. Maintain the engine at idle speed and put the transmission in neutral;

[0023] S120. Move the clutch in the engagement direction until the first shaft of the transmission starts to move and then stop the clutch from moving;

[0024] S130. Maintain the above state until the duration reaches the first manually preset stable time;

[0025] S140. Collect the movement distance of the first clutch and the stable speed of the first transmission shaft at this time; the abscissa of the first clutch displacement-torque point is the movement distance of the first clutch, and the ordinate is 0.

[0026] Preferably, S400 specifically includes the following steps: S400 specifically includes the following steps:

[0027] S410. Obtaining the first clutch displacement-engine output net torque;

[0028] S420. Obtain the second clutch displacement-engine output net torque;

[0029] S430. Replace the value of the ordinate of the first clutch displacement-engine output net torque point with the second clutch displacement-engine output net torque to obtain the second clutch displacement-engine output net torque point;

[0030] S440. Output the second clutch displacement-engine output net torque point, and complete the correction of the first clutch displacement-engine output net torque point.

[0031] Preferably, S420 specifically includes the following steps:

[0032] S421. Keep the clutch moving in the engagement direction since S300 unchanged until the clutch reaches the torque corresponding to the factory transmission distortion line of the first clutch displacement minus the net torque output by the engine, and then stop the movement of the clutch;

[0033] S422. Record the distance between the clutch friction plates at this time as the second clutch movement distance; then compare the magnitude relationship between the second clutch movement distance and the first clutch movement distance, and perform the following operations based on the comparison result:

[0034] If the second clutch movement distance is not greater than the first clutch movement distance, saving the second clutch movement distance;

[0035] If the second clutch movement distance is greater than the first clutch movement distance, gradually reduce the distance between the clutch friction plates until the distance between the clutch friction plates is no greater than the first clutch movement distance; then record the distance between the clutch friction plates at this time again as the second clutch movement distance;

[0036] S423. Collect the stable speed of the first shaft of the second transmission and maintain the above state until the duration reaches the second stable time preset manually;

[0037] S425. Read the net torque output by the engine at this time as the second clutch displacement-net torque output by the engine; and then output the second clutch displacement-net torque output by the engine.

[0038] Preferably, the correction of the first clutch displacement-torque point in S500 specifically includes the following steps:

[0039] S510. The clutch is moved again from the second clutch displacement-engine output net torque point in the separation direction until the speed of one shaft of the gearbox starts to decrease, that is, the movement of the clutch is stopped;

[0040] S520. Record the distance between the clutch friction plates at this time as the third clutch movement distance;

[0041] S530. Obtain a second clutch displacement-torque point according to the third clutch movement distance; the abscissa of the second clutch displacement-torque point is the third clutch movement distance, and the ordinate is 0;

[0042] S540. Calculate a fourth clutch movement distance according to the first clutch movement distance and the third clutch movement distance;

[0043] S550. Obtain a third clutch displacement-torque point according to the fourth clutch movement distance; the abscissa of the third clutch displacement-torque point is the fourth clutch movement distance, and the ordinate is 0;

[0044] S560. Replace the first clutch displacement-torque point with the third clutch displacement-torque point as the new first clutch displacement-torque point, ie, complete the correction of the first clutch displacement-torque point.

[0045] Preferably, in S540, the fourth clutch movement distance is calculated according to the first clutch movement distance and the third clutch movement distance, which is expressed as follows:

[0046]

[0047] Wherein: x4 is the movement distance of the fourth clutch; x1 is the movement distance of the first clutch; x3 is the movement distance of the third clutch.

[0048] Preferably, the output net torque interval is 100, and the unit is N﹒ m;

[0049] The target clutch torque upper limit threshold is 4000, in Nm.

[0050] Preferably, the rule for obtaining the first clutch displacement-engine output net torque in S410 is:

[0051] If it is the first time of the cycle for the gear being modified, the first clutch displacement-engine output net torque is manually preset;

[0052] If the gear to be corrected is the second time in the cycle, or any time after the second time, the first clutch displacement-engine output net torque is calculated according to S600, and the manually preset output net torque interval is added to the second clutch displacement-engine output net torque as the new first clutch displacement-engine output net torque.

[0053] Preferably, the first stabilization time is 0.3, in seconds;

[0054] The second stabilization time is 0.3, in seconds.

[0055] Compared with the prior art, the present invention has the following advantages:

[0056] 1. Since the present invention adopts the successive iterative correction of the Pn point and the kp point, a transmission distortion curve representing the actual situation of the current vehicle clutch can be corrected in the power system of the commercial vehicle;

[0057] 2. Since the correction basis of the present invention is the real value approximated by the current clutch working condition, the accuracy is very high;

[0058] 3. Since the present invention does not require complex algorithms and installation of various special detection equipment, it can save costs and maintain the efficiency of the correction process. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 A schematic diagram of a method flow chart of a specific embodiment of the present invention;

[0060] Figure 2 It is a schematic diagram of the factory transmission twist line of a specific embodiment of the present invention;

[0061] Figure 3 It is a schematic diagram of calibrating kp1 according to a specific embodiment of the present invention;

[0062] Figure 4 Schematic diagram of correcting Pn1 according to a specific embodiment of the present invention. DETAILED DESCRIPTION

[0063] The present invention is further explained below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. After reading the present invention, various equivalent forms of modifications to the present invention by those skilled in the art all fall within the scope defined by the claims attached to this application.

[0064] It should be noted in advance that, in order to facilitate reading and understanding of the technical solution of the present invention, the correspondence between the nouns and symbols used in this specific embodiment is shown in Table 1 as follows:

[0065] Table 1. Noun-symbol correspondence table of this embodiment

[0066]

[0067] It should be noted in advance that although the method of the present invention is aimed at commercial vehicle clutches, in fact, in hybrid vehicles, the torque can also be output by an electric motor instead of an internal combustion engine, that is, the process of correcting the transmission distortion line can be controlled by the motor, thereby applying the method of the present invention to hybrid vehicles.

[0068] like Figure 1 As shown, a method for correcting clutch torque transmission of a commercial vehicle comprises the following steps:

[0069] S100. Collect the first clutch movement distance x1, the first transmission shaft stable speed n1, and the first clutch displacement-torque point kp1 (x1, 0); the first clutch movement distance x1 is the distance between the clutch friction plates at the time of collection.

[0070] like Figure 3 As shown, the abscissa of the first clutch displacement-torque point kp1 (x1, 0) is the first clutch movement distance x1, and the ordinate is 0.

[0071] In this specific embodiment, S100 specifically includes the following steps:

[0072] S110. Keep the engine at idle speed and shift the transmission into neutral.

[0073] S120. Move the clutch in the engagement direction until the first shaft of the transmission starts to move and then stop the clutch from moving;

[0074] S130. Maintain the above state until the duration reaches the manually preset first stabilization time t1.

[0075] In this specific embodiment, the first stabilization time t1 is 0.3, in seconds.

[0076] S140. Collect the first clutch movement distance x1 and the first transmission first shaft stable speed n1 at this time; the abscissa of the first clutch displacement-torque point kp1 (x1, 0) is the first clutch movement distance x1, and the ordinate is 0.

[0077] S200. Disengage the clutch completely; then shift the transmission into the current gear.

[0078] S300. When the transmission has completed the gear shift, move the clutch toward the engagement direction again.

[0079] S400. Obtain the first clutch displacement-engine output net torque T1; then adjust the distance between the clutch friction plates to obtain the second clutch displacement-engine output net torque T2; then correct the first clutch displacement-engine output net torque point Pn1 (x2, T1) according to the first clutch displacement-engine output net torque T1 and the second clutch displacement-engine output net torque T2 to obtain the second clutch displacement-engine output net torque point Pn2 (x2, T2); the value of the horizontal coordinate of the first clutch displacement-engine output net torque point Pn1 (x2, T1) is the second clutch movement distance x2, and the value of the vertical coordinate is the first clutch displacement-engine output net torque T1; the value of the horizontal coordinate of the second clutch displacement-engine output net torque point Pn2 (x2, T2) is the second clutch movement distance x2, and the value of the vertical coordinate is the second clutch displacement-engine output net torque T2.

[0080] In this specific embodiment, S400 specifically includes the following steps: S400 specifically includes the following steps:

[0081] S410. Obtain the first clutch displacement-engine output net torque T1.

[0082] In this specific embodiment, the rule for obtaining the first clutch displacement-engine output net torque T1 in S410 is:

[0083] If it is the first time of the cycle for the gear being modified, the first clutch displacement-engine output net torque T1 is manually preset.

[0084] If the gear to be corrected is the second time in the cycle, or any time after the second time, the first clutch displacement-engine output net torque T1 is calculated according to S600, and the manually preset output net torque interval △T is added to the second clutch displacement-engine output net torque T2 as the new first clutch displacement-engine output net torque T1.

[0085] S420. Obtain the second clutch displacement-engine output net torque T2.

[0086] In this specific embodiment, S420 specifically includes the following steps:

[0087] S421. Keep the clutch moving in the engagement direction since S300 unchanged until the clutch reaches the torque corresponding to the first clutch displacement minus the engine output net torque T1 in the factory transmission distortion curve, and then stop the movement of the clutch.

[0088] It should be noted that if Figure 2 As shown, the factory transmission distortion curve is the transmission distortion curve drawn by the manufacturer and delivered together with the equipment; the factory transmission distortion curve is the transmission distortion curve of the clutch at the time of leaving the factory. This curve will change due to the wear and tear of the clutch in the later period. This is the technical problem to be solved by the present invention, namely, to correct this curve.

[0089] S422. Record the distance between the clutch friction plates at this time as the second clutch movement distance x2; then compare the second clutch movement distance x2 with the first clutch movement distance x1, and perform the following operations based on the comparison result:

[0090] If the second clutch movement distance x2 is not greater than the first clutch movement distance x1, the second clutch movement distance x2 is saved.

[0091] If the second clutch movement distance x2 is greater than the first clutch movement distance x1, gradually reduce the distance between the clutch friction plates until the distance between the clutch friction plates is no greater than the first clutch movement distance x1; then record the distance between the clutch friction plates at this time again as the second clutch movement distance x2.

[0092] It should be noted that the clutch stops moving when the corresponding torque in the factory transmission twist curve reaches T1, and the distance between the friction plates is x2. If x2>x1, it can be seen from the previous S100 that because the torque is only transmitted at the x1 position, no torque is transmitted to the gearbox at the x2 position because the friction plates may not be in contact or the torque transmission is insufficient.

[0093] At this time, reduce x2 until x2<x1, because the clutch has been used and worn by customers, so the torque transmission function is weakened; in this way, under the same vehicle operating conditions and the same friction plate position, the transmitted torque is smaller. When the speed of one shaft reaches a stable speed, that is, n1, and stabilizes for a period of time, that is, t1, read the net torque output by the engine at this time, that is, T2, and record the clutch displacement-engine output net torque point as Pn2(x2, T2), and then use Pn2 instead of Pn1, which completes the correction of the target torque of point Pn1; in simple terms, T1 is replaced by T2.

[0094] S423. Collect the stable rotation speed n2 of the first shaft of the second transmission, and maintain the above state until the duration reaches the manually preset second stable time t2.

[0095] In this specific embodiment, the second stabilization time t2 is 0.3, in seconds.

[0096] S425. Read the net torque output by the engine at this time as the second clutch displacement-net torque output by the engine T2; then output the second clutch displacement-net torque output by the engine T2.

[0097] S430. Replace the value of the ordinate of the first clutch displacement-engine output net torque point Pn1 (x2, T1) with the second clutch displacement-engine output net torque T2 to obtain the second clutch displacement-engine output net torque point Pn2 (x2, T2).

[0098] S440. Figure 4 As shown, the second clutch displacement-engine output net torque point Pn2 (x2, T2) is output to complete the correction of the first clutch displacement-engine output net torque point Pn1 (x2, T1).

[0099] S500. Correct the first clutch displacement-torque point kp1 (x1, 0).

[0100] In this specific embodiment, the first clutch displacement-torque point kp1(x1,0) is corrected in S500, which specifically includes the following steps:

[0101] S510. Move the clutch again from the second clutch displacement-engine output net torque point Pn2 (x2, T2) in the separation direction until the speed of one shaft of the gearbox starts to decrease, that is, stop the movement of the clutch.

[0102] S520. Record the distance between the clutch friction plates at this time as the third clutch movement distance x3.

[0103] S530. According to the third clutch movement distance x3, obtain the second clutch displacement-torque point kp2 (x2, 0); the horizontal coordinate of the second clutch displacement-torque point kp2 (x2, 0) is the third clutch movement distance x3, and the vertical coordinate is 0.

[0104] S540. Calculate the fourth clutch movement distance x4 according to the first clutch movement distance x1 and the third clutch movement distance x3.

[0105] In this specific embodiment, in S540, the fourth clutch movement distance x4 is calculated according to the first clutch movement distance x1 and the third clutch movement distance x3, which is expressed as follows:

[0106]

[0107] Wherein: x4 is the movement distance of the fourth clutch; x1 is the movement distance of the first clutch; x3 is the movement distance of the third clutch.

[0108] S550. According to the fourth clutch movement distance x4, obtain the third clutch displacement-torque point kp3 (x3, 0); the abscissa of the third clutch displacement-torque point kp3 (x3, 0) is the fourth clutch movement distance x4, and the ordinate is 0.

[0109] S560. Replace the first clutch displacement-torque point kp1 (x1, 0) with the third clutch displacement-torque point kp3 (x3, 0) as the new first clutch displacement-torque point kp1 (x1, 0), thereby completing the correction of the first clutch displacement-torque point kp1 (x1, 0).

[0110] It should be noted that the purpose of S500 is to test at which position the clutch friction plate can be defined as a disengaged state.

[0111] S600. Compare the second clutch displacement-engine output net torque T2 with the manually preset target clutch torque upper limit threshold; then perform the following operations according to the comparison result:

[0112] If the second clutch displacement-engine output net torque T2 is less than the target clutch torque upper limit threshold, the manually preset output net torque interval △T is added to the second clutch displacement-engine output net torque T2 as the new first clutch displacement-engine output net torque T1, and then return and execute S100 again.

[0113] In this specific embodiment, the output net torque interval ΔT is 100, and the unit is N m.

[0114] The target clutch torque upper limit threshold is 4000, in N﹒m.

[0115] If the second clutch displacement-engine output net torque T2 is not less than the target clutch torque upper limit threshold, the correction process for the current gear is completed and exited.

[0116] In this specific embodiment, the following steps are also included:

[0117] S700. Repeat S100 to S600 until all gears are corrected, then exit the process of this correction method.

[0118] It should be further explained that in S100 to S500, point Pn is used to replace point kp in the previous correction as the right end point of the correction, and point kp is no longer repeatedly corrected, and the correction of the entire curve can be completed.

[0119] In order to further illustrate and demonstrate the principle and creativity of the method of the present invention, this specific embodiment discloses the following simulation experiments and data:

[0120] like Figure 2 As shown in the figure, the clutch transmission distortion line is the factory torque curve when the vehicle leaves the factory. After a period of use, due to wear, the actual transmission distortion line moves to the torque curve after wear. At this time, the reference curve provided to the TCU operation is still the factory torque curve, so it needs to be corrected to the torque curve after wear. The steps are as follows:

[0121] Step 1. The engine maintains idle speed, the transmission is in neutral gear, and the clutch moves in the engagement direction. When the first shaft of the transmission starts to move, the clutch stops moving and stabilizes at t1 = 0.3S. At this time, the clutch movement distance x1 = 11mm, and the first shaft speed of the transmission stabilizes at n1 = 100r / min. The coordinates of point kp1 are (11, 0). Figure 3 shown.

[0122] Step 2. The clutch is completely disengaged and the transmission is shifted into first gear.

[0123] Step 3. After the transmission completes the gear shift, the clutch moves in the engagement direction.

[0124] Step 4. Figure 4 As shown, the clutch reaches the displacement x2 = 12.5mm corresponding to the torque T1 = 100N﹒ m of the Pn1 point in the factory transmission distortion curve. At this time, x1 < x2, and the clutch continues to move in the engagement direction until T2 = 300N﹒ m, x2 < x1, and stops moving. At this time, x2 = 10mm, and the speed of one shaft reaches a stable speed of 200r / min and stabilizes for 0.3S. The net torque output of the engine is read as 150N﹒ m. The coordinates of Pn2 are recorded as (10, 150). Pn2 is used instead of Pn1 to complete the correction of the target torque of point Pn1.

[0125] Simply put, the △T of each cycle is 100N﹒ m, and so on, until the entire curve is completed.

[0126] At this point, for the current gear, the curve as a whole sinks by about 20% of the vertical coordinate value. This gap is very large in the clutch position target adjustment; the existing technology does not take this into consideration and directly performs target calculation, which will inevitably cause inaccuracy.

[0127] Step 5. The clutch moves from point Pn2 to the disengagement direction and stops moving when the speed of the gearbox shaft starts to decrease. At this time, the clutch movement distance x3 = 10.8 mm, and this point is recorded as Kp2 (10.8, 0). Let x3 = 1 / 2*(x1+x2) = 10.9 mm, and get Kp3 (10.9 mm, 0), and use Kp3 to replace Kp1. The correction of the target torque at point Kp1 is completed.

[0128] Step 6. Repeat the above steps until the target clutch upper limit value is reached, thus completing the correction of the entire torque curve.

[0129] In the above detailed description, various features are grouped together in a single embodiment to simplify the disclosure. This method of disclosure should not be interpreted as reflecting an intention that the embodiments of the claimed subject matter require more features than are clearly stated in each claim. On the contrary, as reflected in the appended claims, the invention is in a state of having less than all the features of the disclosed individual embodiments. Therefore, the appended claims are hereby expressly incorporated into the detailed description, with each claim standing on its own as a separate preferred embodiment of the invention.

[0130] The disclosed embodiments are described above to enable any person skilled in the art to implement or use the present invention. Various modifications of these embodiments are obvious to those skilled in the art, and the general principles defined herein may also be applied to other embodiments without departing from the spirit and scope of the present disclosure. Therefore, the present disclosure is not limited to the embodiments given herein, but is consistent with the broadest scope of the principles and novel features disclosed in this application.

[0131] The above description includes examples of one or more embodiments. Of course, it is not possible to describe all possible combinations of components or methods for the purpose of describing the above embodiments, but it should be recognized by those skilled in the art that the various embodiments may be further combined and arranged. Therefore, the embodiments described herein are intended to cover all such changes, modifications and variations that fall within the scope of protection of the appended claims. In addition, with respect to the term "comprising" used in the specification or claims, the word is covered in a manner similar to the term "including", just as "including," is explained as a transitional word in the claims. In addition, any term "or" used in the specification of the claims is intended to mean "non-exclusive or".

[0132] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for correcting clutch torque transmission of a commercial vehicle, characterized in that: The following steps are involved: S100. Collect the first clutch movement distance, the first transmission shaft stable speed, and the first clutch displacement-torque point; the first clutch movement distance is the distance between the clutch friction plates at the time of collection; the abscissa of the first clutch displacement-torque point is the first clutch movement distance, and the ordinate is 0; S200. Disengage the clutch completely; then shift the transmission into the current gear; S300. After the gearbox has completed the gear shift, the clutch is moved toward the engagement direction again; S400. Obtain the first clutch displacement-engine output net torque; then adjust the distance between the clutch friction plates to obtain the second clutch displacement-engine output net torque; then correct the first clutch displacement-engine output net torque point according to the first clutch displacement-engine output net torque and the second clutch displacement-engine output net torque to obtain the second clutch displacement-engine output net torque point; the value of the abscissa of the first clutch displacement-engine output net torque point is the second clutch movement distance, and the value of the ordinate is the first clutch displacement-engine output net torque; the value of the abscissa of the second clutch displacement-engine output net torque point is the second clutch movement distance, and the value of the ordinate is the second clutch displacement-engine output net torque; S500. Correcting the first clutch displacement-torque point; S600. Compare the second clutch displacement-engine output net torque with the manually preset target clutch torque upper limit threshold; then perform the following operations according to the comparison result: If the second clutch displacement-engine output net torque is less than the target clutch torque upper limit threshold, then the manually preset output net torque interval is added to the second clutch displacement-engine output net torque as the new first clutch displacement-engine output net torque, and then the process returns to and executes S100 again; If the second clutch displacement-engine output net torque is not less than the target clutch torque upper limit threshold, the correction process for the current gear is completed and exited.

2. The method for correcting clutch torque of a commercial vehicle according to claim 1, characterized in that: It also includes the following steps: S700. Repeat S100 to S600 until all gears are corrected, then exit the process of this correction method.

3. The method for correcting clutch torque of a commercial vehicle according to claim 2, characterized in that: S100 specifically includes the following steps: S110. Maintain the engine at idle speed and put the transmission in neutral; S120. Move the clutch in the engagement direction until the first shaft of the transmission starts to move and then stop the clutch from moving; S130. Maintain the above state until the duration reaches the first manually preset stable time; S140. Collect the movement distance of the first clutch and the stable speed of the first transmission shaft at this time; the abscissa of the first clutch displacement-torque point is the movement distance of the first clutch, and the ordinate is 0.

4. The method for correcting clutch torque of a commercial vehicle according to claim 3, characterized in that: S400 specifically includes the following steps: S400 specifically includes the following steps: S410. Obtaining the first clutch displacement-engine output net torque; S420. Obtain the second clutch displacement-engine output net torque; S430. Replace the value of the ordinate of the first clutch displacement-engine output net torque point with the second clutch displacement-engine output net torque to obtain the second clutch displacement-engine output net torque point; S440. Output the second clutch displacement-engine output net torque point, and complete the correction of the first clutch displacement-engine output net torque point.

5. The method for correcting clutch torque of a commercial vehicle according to claim 4, characterized in that: S420 specifically includes the following steps: S421. Keep the clutch moving in the engagement direction since S300 unchanged until the clutch reaches the torque corresponding to the factory transmission distortion line of the first clutch displacement minus the net torque output by the engine, and then stop the movement of the clutch; S422. Record the distance between the clutch friction plates at this time as the second clutch movement distance; then compare the magnitude relationship between the second clutch movement distance and the first clutch movement distance, and perform the following operations based on the comparison result: If the second clutch movement distance is not greater than the first clutch movement distance, saving the second clutch movement distance; If the second clutch movement distance is greater than the first clutch movement distance, gradually reduce the distance between the clutch friction plates until the distance between the clutch friction plates is no greater than the first clutch movement distance; then record the distance between the clutch friction plates at this time again as the second clutch movement distance; S423. Collect the stable speed of the first shaft of the second transmission and maintain the above state until the duration reaches the second stable time preset manually; S425. Read the net torque output by the engine at this time as the second clutch displacement-net torque output by the engine; and then output the second clutch displacement-net torque output by the engine.

6. The method for correcting clutch torque of a commercial vehicle according to claim 5, characterized in that: S500 corrects the first clutch displacement-torque point, which specifically includes the following steps: S510. The clutch is moved again from the second clutch displacement-engine output net torque point in the separation direction until the speed of one shaft of the gearbox starts to decrease, that is, the movement of the clutch is stopped; S520. Record the distance between the clutch friction plates at this time as the third clutch movement distance; S530. Obtain a second clutch displacement-torque point according to the third clutch movement distance; the abscissa of the second clutch displacement-torque point is the third clutch movement distance, and the ordinate is 0; S540. Calculate a fourth clutch movement distance according to the first clutch movement distance and the third clutch movement distance; S550. Obtain a third clutch displacement-torque point according to the fourth clutch movement distance; the abscissa of the third clutch displacement-torque point is the fourth clutch movement distance, and the ordinate is 0; S560. Replace the first clutch displacement-torque point with the third clutch displacement-torque point as the new first clutch displacement-torque point, ie, complete the correction of the first clutch displacement-torque point.

7. The method for correcting clutch torque of a commercial vehicle according to claim 6, characterized in that: In S540, the fourth clutch movement distance is calculated according to the first clutch movement distance and the third clutch movement distance, which is expressed as follows: Wherein: x4 is the movement distance of the fourth clutch; x1 is the movement distance of the first clutch; x3 is the movement distance of the third clutch.

8. The method for correcting clutch torque of a commercial vehicle according to claim 7, characterized in that: The output net torque interval is 100, and the unit is N﹒m; The target clutch torque upper limit threshold is 4000, in Nm.

9. The method for correcting clutch torque of a commercial vehicle according to claim 8, characterized in that: The rule for obtaining the first clutch displacement-engine output net torque in S410 is: If it is the first time of the cycle for the gear being modified, the first clutch displacement-engine output net torque is manually preset; If the gear to be corrected is the second time in the cycle, or any time thereafter, the first clutch displacement-engine output net torque is calculated according to S600, and the manually preset output net torque interval is added to the second clutch displacement-engine output net torque as the new first clutch displacement-engine output net torque.

10. The method for correcting clutch torque of a commercial vehicle according to claim 9, characterized in that: The first stabilization time is 0.3, in seconds; The second stabilization time is 0.3, in seconds.

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