AMT intermediate shaft brake control method

Abstract

The present invention discloses an AMT intermediate shaft brake control method, the process is: judging whether to turn on the intermediate shaft brake according to the dog tooth speed difference, if the intermediate shaft brake is turned on, entering the first stage intermediate shaft braking state, the intake valve is opened, the exhaust valve is closed, judging whether the current speed regulation percentage is greater than the brake release percentage threshold, if so, the first stage intermediate shaft braking ends, the intake valve is closed, the exhaust valve is opened, and the exhaust hysteresis braking state is entered; judging whether to turn on the intermediate shaft brake again according to the dog tooth speed difference, if so, entering the second stage intermediate shaft braking state, the intake valve is opened, the exhaust valve is closed; judging whether the dog tooth speed difference is less than the dog tooth speed difference gear-in window upper limit value. The present invention can make the intermediate shaft speed and angular acceleration be accurately controlled, reduce the calibration amount under the premise of avoiding over-braking, and improve the adaptability and consistency of the control strategy.

Description

Technical Field

[0001] The invention belongs to the technical field of AMT shift control, and in particular relates to an AMT intermediate shaft brake control method. Background Art

[0002] For the sake of cost control and maintenance convenience, the main gearbox non-synchronizer shifting technology solution is widely used in the field of commercial vehicle AMT. Compared with synchronizer shifting, non-synchronizer shifting places higher requirements on the rapidity, stability and accuracy of the transmission speed response. When shifting up, since the target gear speed is higher than the main shaft speed, the input shaft must be decelerated. The current mainstream technical solution is to use a pneumatic intermediate shaft brake to decelerate the intermediate shaft. The principle is to use a cylinder to push the wet friction plate to brake the intermediate shaft. When the intermediate shaft speed is reduced to the target speed, the speed difference between the sliding gear sleeve and the target gear ring dog teeth reaches the gear entry threshold, and the gear engagement action is executed.

[0003] During the braking speed regulation process, the TCU monitors the intermediate shaft speed in real time and controls the intake and exhaust actions of the brake solenoid valve. However, due to the hysteresis of pneumatic control, the complexity of the friction braking mechanism and the diversity of road conditions, the intermediate shaft braking is prone to over-braking, causing excessive gear speed difference, increased gear shifting noise and even gear shifting shock.

[0004] In view of the above problems, there are two existing solutions in terms of control strategy: the first method is to close the intermediate shaft brake solenoid valve in advance and continue to brake and adjust the speed by using the residual braking energy when the cylinder is exhausted. The defect of this method is that the timing of closing the solenoid valve is difficult to calculate accurately, and it can only be calibrated on a bench or a whole vehicle for different working conditions. The calibration amount is too much and the adaptability of the strategy is poor. The second method (CN 110985655 A) is to monitor the intermediate shaft speed and the intermediate shaft angular acceleration at the same time, and control the intermediate shaft speed to reduce the speed according to the specified slope during the speed regulation process, so as to improve the accuracy of the speed regulation. The defect of this method is that it is too dependent on the calibrated speed reduction slope. If the slope is too high, it is easy to cause over-braking. If the slope is too low, the speed regulation time is extended. In addition, due to the short braking speed regulation time and the large brake inertia, this method has limited effect on the speed regulation and poor adaptability to the speed regulation changes caused by changes in road conditions. Summary of the invention

[0005] The purpose of the present invention is to solve the shortcomings of the above-mentioned background technology and to provide an AMT intermediate shaft brake control method so that the intermediate shaft speed and angular acceleration can be accurately controlled, the calibration amount can be reduced while avoiding over-braking, and the adaptability and consistency of the control strategy can be improved.

[0006] The technical solution adopted by the present invention is: an AMT intermediate shaft brake control method, comprising the following steps:

[0007] S0: Get the dog gear speed difference in real time;

[0008] S1: judging whether to open the intermediate shaft brake according to the dog gear speed difference, if the intermediate shaft brake is opened, executing step S2; if the intermediate shaft brake is not opened, the intermediate shaft is free to decelerate, executing step S7;

[0009] S2: Entering the first-stage intermediate shaft braking state, the intake valve is opened and the exhaust valve is closed, and step S3 is executed;

[0010] S3: Determine whether the current speed adjustment percentage is greater than the brake release percentage threshold, if so, execute step S4, if not, return to step S2;

[0011] S4: The first-stage intermediate shaft braking is completed, the intake valve is closed, the exhaust valve is opened, and the exhaust hysteresis braking state is entered, and step S5 is executed;

[0012] S5: judging whether to open the intermediate shaft brake again according to the dog gear speed difference, if yes, executing step S6; if no, executing step S7;

[0013] S6: Entering the second stage intermediate shaft braking state, the intake valve is opened and the exhaust valve is closed, and step S7 is executed;

[0014] S7: Determine whether the dog gear speed difference is less than the upper limit of the dog gear speed difference shift window. If yes and the current intermediate shaft is in a controlled state, execute step S8; if yes and the current intermediate shaft is in a free state, execute step S9; if no and the current intermediate shaft is in a controlled state, return to step S4; if no and the current intermediate shaft is in a free state, return to step S1;

[0015] S8: The intermediate shaft braking is completed, the intake valve is closed, the exhaust valve is opened, and step S9 is executed;

[0016] S9: The main box executes the gear shifting.

[0017] Furthermore, if the dog tooth speed difference is greater than the first-stage braking window threshold, it is determined that the intermediate shaft braking is turned on; if the dog tooth speed difference is less than or equal to the first-stage braking window threshold, it is determined that the intermediate shaft braking is not turned on; the first-stage braking window threshold is the sum of the dog tooth speed difference gear shift window upper limit value and the first-stage biased speed.

[0018] Furthermore, the current speed adjustment percentage=(intermediate shaft speed in the initial braking state-current intermediate shaft speed) / target intermediate shaft speed difference.

[0019] Further, the brake release percentage threshold is determined by looking up a target intermediate shaft speed difference and a transmission oil temperature table.

[0020] Further, the target intermediate shaft speed difference=intermediate shaft speed in the initial braking state-target intermediate shaft speed; the target intermediate shaft speed=(output shaft speed+dog gear speed difference shift window upper limit)*requested gear dog gear ratio.

[0021] Furthermore, after the gear is engaged, it is determined whether to update the current brake release percentage threshold and the requested gear braking coefficient according to the instantaneous dog tooth speed difference and the braking time of the gear engagement.

[0022] Further, if the instantaneous dog tooth speed difference of the gear entry is greater than the first threshold value, and the braking time is less than the upper limit value of the braking time, the brake release percentage threshold corresponding to the oil temperature level and the target intermediate shaft speed speed difference level is increased, and the requested gear braking coefficient is increased and updated;

[0023] If the instantaneous dog tooth speed difference of the gear entry is less than the second threshold value, and the braking time is greater than the upper limit of the braking time, the brake release percentage threshold corresponding to the oil temperature level and the target intermediate shaft speed speed difference level is reduced, and the requested gear braking coefficient is reduced and updated;

[0024] The first threshold is greater than the second threshold.

[0025] Furthermore, the process of determining whether to start the intermediate shaft brake again according to the dog gear speed difference and the current intermediate shaft deceleration rate is as follows:

[0026] If the dog tooth speed difference is greater than the second-stage braking window threshold, it is determined whether the current intermediate shaft deceleration rate is greater than the second-stage braking rate threshold; if the dog tooth speed difference is less than or equal to the second-stage braking window threshold, the intermediate shaft braking is not turned on;

[0027] If the current intermediate shaft deceleration rate is greater than the second-stage braking rate threshold, the intermediate shaft braking is turned on; if the current intermediate shaft deceleration rate is less than or equal to the second-stage braking rate threshold, the intermediate shaft braking is not turned on.

[0028] Furthermore, the second-stage braking window threshold is the sum of the dog-tooth speed difference shift window upper limit value and the second-stage biased speed.

[0029] Furthermore, the second-stage braking rate threshold=reference rate*requested gear braking coefficient.

[0030] The beneficial effects of the present invention are:

[0031] 1) The present invention enables the intermediate shaft speed and angular acceleration to be precisely controlled, and can effectively avoid over-braking.

[0032] 2) The second-stage braking rate threshold of the present invention depends on the deceleration rate at the end of the first-stage braking, but not on the calibration value, thereby enhancing the adaptability of the strategy.

[0033] 3) The intermediate shaft braking control parameters (brake release percentage threshold and requested gear braking coefficient) of the present invention can be updated through learning, screening and updating, which enhances the adaptability of the strategy under different road conditions and the consistency of speed control. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a control flow chart of the present invention. DETAILED DESCRIPTION

[0035] The specific embodiments of the present invention are further described below in conjunction with the accompanying drawings. It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0036] like Figure 1 As shown, the present invention provides an AMT intermediate shaft brake control method, and the control process is as follows:

[0037] S0: Enter the intermediate shaft braking state, obtain the requested gear, intermediate shaft speed, intermediate shaft speed rate, output shaft speed, transmission oil temperature, dog gear speed difference, and requested gear braking coefficient;

[0038] S1: Determine whether the dog gear speed difference is greater than the first-stage braking window threshold: if so, turn on the intermediate shaft braking and execute S2; if not, do not turn on the braking, let the intermediate shaft decelerate freely, and jump to execute S8; the first-stage braking window threshold is the sum of the dog gear speed difference gear window upper limit value and the first-stage bias speed;

[0039] S2: Entering the first-stage intermediate shaft braking state, the intake valve opens and the exhaust valve closes;

[0040] S3: Mark the intermediate shaft speed in the initial state of braking, calculate the target intermediate shaft speed and the target intermediate shaft speed difference; the target intermediate shaft speed = (output shaft speed + dog gear speed difference gear window upper limit) * requested gear dog gear ratio, the target intermediate shaft speed difference = intermediate shaft speed in the initial state of braking - target intermediate shaft speed;

[0041] S4: Determine the brake release percentage threshold value by looking up the table according to the target intermediate shaft speed difference and the transmission oil temperature. The initial value of the percentage threshold value is calculated according to the intermediate shaft braking performance bench test data, and the dynamic value is updated according to S10;

[0042] S5: Determine whether the current speed adjustment percentage is greater than the brake release percentage threshold: if so, end the first stage of braking, open the exhaust valve, close the intake valve, enter the exhaust hysteresis braking state, and mark the current intermediate shaft deceleration rate as the reference rate; if not, return to S2; the current speed adjustment percentage = (intermediate shaft speed in the initial state of braking - current intermediate shaft speed) / target intermediate shaft speed difference;

[0043] S6: Determine whether the dog gear speed difference is greater than the second-stage braking window threshold: if so, execute S7; if not, end the intermediate shaft braking and execute S8; the second-stage braking window threshold refers to the sum of the dog gear speed difference gear window upper limit value and the second-stage bias speed;

[0044] S7: Entering the second-stage intermediate shaft braking state, determining whether the current intermediate shaft deceleration rate is greater than the second-stage braking rate threshold: if so, turning on the intermediate shaft braking, opening the intake valve, closing the exhaust valve, and executing S8; if not, directly executing S8; the second-stage braking rate threshold refers to the reference rate * the requested gear braking coefficient;

[0045] S8: Determine whether the current dog gear speed difference is less than the upper limit of the dog gear speed difference shift window: if so, and the current intermediate shaft is in a controlled state, then the intermediate shaft braking control is terminated, the brake exhaust valve is opened, the intake valve is closed, and S9 is executed; if so, and the current intermediate shaft is in a free state, then the intermediate shaft free deceleration is terminated and S9 is executed; if not, and the current intermediate shaft is in a controlled state, then return to S6; if not, and the current intermediate shaft is in a free state, then return to S1;

[0046] S9: main box executes gear shifting;

[0047] S10: Determine whether to update the brake release percentage threshold and the requested gear brake coefficient. The determination rules are as follows:

[0048] 1) If the instantaneous dog tooth speed difference of the gear entry is greater than the first threshold value, which is generally 60rpm, and the braking time is less than the upper limit of the braking time, the brake release percentage threshold corresponding to the oil temperature level and the target intermediate shaft speed speed difference level is increased, and the requested gear braking coefficient is increased and updated;

[0049] 2) If the instantaneous dog tooth speed difference of the gear entry is less than the second threshold value, which is generally 30 rpm, and the braking time is greater than the upper limit of the braking time, then the brake release percentage threshold corresponding to the oil temperature level and the target intermediate shaft speed speed difference level is reduced, and the requested gear braking coefficient is reduced and updated;

[0050] 3) If both of the above conditions are not met, the brake release percentage threshold and the initial value of the requested gear brake coefficient are maintained. The brake release percentage threshold update value is increased or decreased by 5%, and the requested gear brake coefficient is increased or decreased by 0.1.

[0051] In this implementation example:

[0052] Step S0 enters the intermediate shaft braking state, the requested gear is 5th gear, the intermediate shaft speed is 731 rpm, the transmission oil temperature is 34°C, and the dog gear speed difference is 313 rpm;

[0053] Step S1: the first stage braking window threshold is 75 rpm, and the intermediate shaft braking is judged to be turned on;

[0054] Step S3: the target intermediate shaft speed difference is 218 rpm; Step S4: the brake release percentage threshold of the current oil temperature and the target intermediate shaft speed difference level is 35%; when the intermediate shaft speed drops to 647 rpm, the brake inlet valve is closed and the exhaust valve is opened; Step S5: the intermediate shaft deceleration rate at the end of the first stage of braking is -800 rpm / s;

[0055] In step S6, the dog gear speed difference is 213rpm, and the second-stage braking window threshold is 75rpm; in step S7, the initial requested gear braking coefficient is 0.5, and the second-stage braking rate threshold is -400rpm / s. In this example, from the end of the first-stage braking to the transfer of the transmission execution state to the gear-engaging state, the intermediate shaft speed reduction rate is maintained below -400rpm / s, and the second-stage braking is not turned on. The brake continues to brake using residual energy until step S8 determines that the current dog gear speed difference of 48rpm is less than the 5th gear dog gear speed difference gear-engaging window upper limit of 55rpm, and the intermediate shaft braking control is ended, and the gear-engaging action S9 is executed.

[0056] Step S10 determines that the instantaneous dog tooth speed difference of the gear entry is 29rpm, and the braking time is less than the upper limit value. The oil temperature level of 40℃ and the speed difference level of 200rpm corresponding to the transmission oil temperature of 34℃ and the target intermediate shaft speed difference of 218rpm remain unchanged, and the 5th gear braking coefficient of 0.5 remains unchanged.

[0057] It should be understood that the specific order or hierarchy of steps in the disclosed process is an example of an exemplary method. Based on design preferences, it should be understood that the specific order or hierarchy of steps in the process can be rearranged without departing from the scope of protection of the present disclosure. The attached method claims present the elements of the various steps in an exemplary order and are not intended to be limited to the specific order or hierarchy described.

[0058] In order to make the description of the present disclosure more detailed and complete, the above description is provided for the implementation and specific embodiments of the present invention; however, this is not the only form of implementing or using the specific embodiments of the present invention. The implementation covers the features of multiple specific embodiments and the method steps and sequences used to construct and operate these specific embodiments. However, other specific embodiments can also be used to achieve the same or equivalent functions and step sequences.

[0059] 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.

[0060] 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.

[0061] The above description includes examples of one or more embodiments. Of course, it is impossible 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".

[0062] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in the field.

Claims

1. A method for controlling an AMT intermediate shaft brake, characterized in that: The following steps are involved: S0: Get the dog gear speed difference in real time; S1: judging whether to open the intermediate shaft brake according to the dog gear speed difference, if the intermediate shaft brake is opened, executing step S2; if the intermediate shaft brake is not opened, the intermediate shaft is free to decelerate, executing step S7; S2: Entering the first-stage intermediate shaft braking state, the intake valve is opened and the exhaust valve is closed, and step S3 is executed; S3: Determine whether the current speed adjustment percentage is greater than the brake release percentage threshold, if so, execute step S4, if not, return to step S2; S4: The first-stage intermediate shaft braking is completed, the intake valve is closed, the exhaust valve is opened, and the exhaust hysteresis braking state is entered, and step S5 is executed; S5: judging whether to start the intermediate shaft brake again according to the dog gear speed difference and the current intermediate shaft deceleration rate, if yes, executing step S6; if no, executing step S7; S6: Entering the second stage intermediate shaft braking state, the intake valve is opened and the exhaust valve is closed, and step S7 is executed; S7: Determine whether the dog gear speed difference is less than the upper limit of the dog gear speed difference shift window. If yes and the current intermediate shaft is in a controlled state, execute step S8; if yes and the current intermediate shaft is in a free state, execute step S9; if no and the current intermediate shaft is in a controlled state, return to step S4; if no and the current intermediate shaft is in a free state, return to step S1; S8: The intermediate shaft braking is completed, the intake valve is closed, the exhaust valve is opened, and step S9 is executed; S9: The main box executes the gear shifting.

2. The AMT intermediate shaft brake control method according to claim 1, characterized in that: If the dog tooth speed difference is greater than the first-stage braking window threshold, it is determined that the intermediate shaft braking is turned on; if the dog tooth speed difference is less than or equal to the first-stage braking window threshold, it is determined that the intermediate shaft braking is not turned on; the first-stage braking window threshold is the sum of the dog tooth speed difference gear window upper limit value and the first-stage biased speed.

3. The AMT intermediate shaft brake control method according to claim 1, characterized in that: The current speed adjustment percentage=(intermediate shaft speed in the initial braking state-current intermediate shaft speed) / target intermediate shaft speed difference.

4. The AMT intermediate shaft brake control method according to claim 1, characterized in that: The brake release percentage threshold is determined by looking up a target intermediate shaft speed difference and a transmission oil temperature table.

5. The AMT intermediate shaft brake control method according to claim 4, characterized in that: The target intermediate shaft speed difference=the intermediate shaft speed in the initial braking state-the target intermediate shaft speed; the target intermediate shaft speed=(the output shaft speed+the upper limit of the dog gear speed difference shift window)*the requested gear dog gear ratio.

6. The AMT intermediate shaft brake control method according to claim 1, characterized in that: After the gear is engaged, it is determined whether to update the current brake release percentage threshold and the requested gear brake coefficient according to the instantaneous dog tooth speed difference and the braking time.

7. The AMT intermediate shaft brake control method according to claim 6, characterized in that: If the instantaneous dog tooth speed difference of the gear entry is greater than the first threshold value, and the braking time is less than the upper limit of the braking time, the brake release percentage threshold corresponding to the oil temperature level and the target intermediate shaft speed speed difference level is increased, and the requested gear braking coefficient is increased and updated; If the instantaneous dog tooth speed difference of the gear entry is less than the second threshold value, and the braking time is greater than the upper limit of the braking time, the brake release percentage threshold corresponding to the oil temperature level and the target intermediate shaft speed speed difference level is reduced, and the requested gear braking coefficient is reduced and updated; The first threshold is greater than the second threshold.

8. The AMT intermediate shaft brake control method according to claim 1, characterized in that: The process of judging whether to open the intermediate shaft brake again according to the dog gear speed difference and the current intermediate shaft deceleration rate is as follows: If the dog tooth speed difference is greater than the second-stage braking window threshold, it is determined whether the current intermediate shaft deceleration rate is greater than the second-stage braking rate threshold; if the dog tooth speed difference is less than or equal to the second-stage braking window threshold, the intermediate shaft braking is not turned on; If the current intermediate shaft deceleration rate is greater than the second-stage braking rate threshold, the intermediate shaft braking is turned on; if the current intermediate shaft deceleration rate is less than or equal to the second-stage braking rate threshold, the intermediate shaft braking is not turned on.

9. The AMT intermediate shaft brake control method according to claim 8, characterized in that: The second-stage braking window threshold is the sum of the dog-tooth speed difference shift window upper limit value and the second-stage bias speed.

10. The AMT intermediate shaft brake control method according to claim 8, characterized in that: The second-stage braking speed threshold=reference speed*requested gear braking coefficient.

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