AMT intermediate shaft brake control method

Abstract

The application discloses an AMT intermediate shaft brake control method. When the clutch is separated and the gear shifting is completed, the estimated gear-in speed difference at a certain set time after the current time is calculated after a period of time, and the current time is determined to be open brake valve for intermediate shaft brake or close brake valve for gear shifting according to the estimated gear-in speed difference. The application compares the estimated gear-in speed difference at the set time with the set speed threshold, opens or closes the valve in advance at the set time after the comparison, ensures that the valve action corresponds to the system response time, controls the continuous reduction of the speed, realizes the accurate brake, and avoids the problems of impact and tooth collision.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of AMT shift control, and particularly relates to an AMT intermediate shaft brake control method. BACKGROUND

[0002] The sliding sleeve shift mode is widely used in automatic transmissions. In the upshift process of the automatic transmission using the sliding sleeve shift mode, the intermediate shaft speed is reduced to enable the sliding sleeve to complete the shift action at a suitable speed difference. When the shift speed difference is not suitable, the sliding sleeve shift may have problems such as large shift impact, shift failure, and even sliding sleeve damage. In order to shorten the shift time and quickly reduce the intermediate shaft speed, an intermediate shaft brake is widely used in the automatic transmission using the sliding sleeve shift mode, which has a wet friction plate as a brake element and a cylinder as an execution element. The brake of the intermediate shaft brake quickly reduces the intermediate shaft speed to the target speed to meet the sliding sleeve shift requirement.

[0003] Due to the strong time lag of pneumatic control and the complex friction characteristics of the wet friction plate, when the intermediate shaft speed is controlled, the pneumatic control valve may be controlled unreasonably, which may cause problems such as over-braking, long braking time, and inaccurate intermediate shaft speed difference control. When the over-braking problem occurs, the intermediate shaft speed is reduced too quickly during the sliding sleeve shift process, which makes the shift speed difference unsuitable, resulting in shift failure or large shift impact. When the long over-braking time problem occurs, it will cause a long shift power interruption time of the automatic transmission.

[0004] The patent CN114382808 discloses an intermediate shaft brake control method. By opening the inlet electromagnetic valve and closing the exhaust electromagnetic valve, the intermediate shaft brake is inflated to establish the intermediate shaft braking capacity. After a period of time, by closing the inlet electromagnetic valve and closing the exhaust electromagnetic valve, the intermediate shaft brake pressure is maintained to stabilize the braking torque for intermediate shaft braking. Before the intermediate shaft speed reaches the intermediate shaft speed control target value, the exhaust electromagnetic valve is opened to deflate the intermediate shaft brake and release the intermediate shaft braking. If the intermediate shaft speed does not reach the intermediate shaft speed control target value and the intermediate shaft braking is released, the above process is repeated until the intermediate shaft speed reaches the intermediate shaft speed control target value. This strategy goes to the shift after the intermediate shaft braking is released to the target speed difference. In fact, the response time of the shift system is not considered, which may cause the difference between the actual shift speed difference and the speed difference when the braking is released, resulting in shift impact or gear tooth damage. SUMMARY

[0005] The present application aims to solve the problems in the background art and provide an AMT intermediate shaft brake control method to achieve accurate shift without shift gear tooth damage or impact.

[0006] The technical solution adopted in this invention is: an AMT intermediate shaft braking control method, which, when the clutch is disengaged and the gear is engaged, calculates the estimated gear shift speed difference at a set time after the current time after a delay of one cycle, and determines whether to open the brake valve to brake the intermediate shaft or close the brake valve to engage the gear based on the estimated gear shift speed difference.

[0007] Furthermore, the set time Δt between the current time and the set time is Δt = i * ti, where i is the set number of calculation cycles and ti is the cycle.

[0008] Furthermore, the value of i is 50-100.

[0009] Furthermore, the estimated shift point speed difference is determined by the following formula:

[0010] △n = n * target gear ratio - spindle speed, where △n is the estimated shift speed difference and n is the estimated shift speed at the set time.

[0011] Furthermore, the estimated gear shift speed n at the set time is determined by the following formula:

[0012] n = n0 + k1*△n1 + k2*△n2 + k3*△n3 + ... + ki*△ni, where n0 is the initial speed during gear shifting, k1, k2, ..., ki are the response coefficients of the 1st, 2nd, ..., ith cycles before the current time, respectively; △n1, △n1, ..., △ni are the speed reduction amounts of the 1st, 2nd, ..., ith cycles before the current time, respectively, and the ith cycle is the cycle closest to the current time.

[0013] Furthermore, the amount of speed reduction in each cycle prior to the current moment is measured by a speed sensor.

[0014] Furthermore, if the number of cycles before the current moment is less than the set number of calculation cycles, then the number of calculation cycles is increased to the set number of calculation cycles based on the cycle closest to the current moment.

[0015] Furthermore, if the estimated shift speed difference Δn satisfies Δn>n2, the brake valve is opened to brake the intermediate shaft; if the estimated shift speed difference Δn satisfies n1≤Δn≤n2, the brake valve is closed to engage the gear, where n1 and n2 are the set lower and upper threshold limits, respectively.

[0016] Furthermore, the value of n1 is -300rpm to -100rpm.

[0017] Furthermore, the value of n2 is between 100 rpm and 300 rpm.

[0018] The beneficial effects of this invention are:

[0019] This invention compares the difference in gear shift speed after a predetermined time with a set speed threshold. After the comparison, the valve is opened or closed at a predetermined time in advance to ensure that the valve action corresponds to the system response time. This controls the speed to decrease continuously, achieving more precise braking and avoiding problems such as impact and gear grinding.

[0020] Since the braking capacity of the intermediate shaft brake will not change significantly in a short period of time, the method estimates the speed difference after a set time Δt by using the speed difference of the previous i cycles at the current moment. This method avoids the influence of factors such as oil temperature, air pressure, and component dispersion, making the strategy more intelligent and adaptable.

[0021] This invention calculates the rotational speed after considering the system response time Δt based on the rotational speed change of the i cycles prior to the current time using the formula n=n0+k1*△n1+k2*△n2+k3*△n3+……+ki*△ni. As time passes, the rotational speed prediction is iterated forward step by step with each cycle. This scheme can ensure a relatively smooth change in the rotational speed difference, without abrupt changes due to changes in the value of k, and has higher accuracy. Attached Figure Description

[0022] Figure 1 This is a flowchart of the present invention.

[0023] Figure 2 This is a schematic diagram illustrating the estimated rotational speed of the present invention. Detailed Implementation

[0024] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, 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.

[0025] like Figure 1 As shown, the present invention provides an AMT intermediate shaft braking control method. When the clutch disengages and the gear is disengaged, after a delay of one cycle (the communication cycle for issuing commands by a general system), the method begins to perform real-time estimation of the shift speed difference. That is, it calculates the estimated shift speed difference at a set time after the current time. Based on the estimated shift speed difference, it determines whether to issue a command to open the brake valve to brake the intermediate shaft or to issue a command to close the brake valve to engage the gear.

[0026] This invention compares the difference in gear shift speed after a predetermined time with a set speed threshold. After the comparison, the valve is opened or closed at a predetermined time in advance to ensure that the valve action corresponds to the system response time. This controls the speed to decrease continuously, achieving more precise braking and avoiding problems such as impact and gear grinding.

[0027] The system response mainly includes the response of the solenoid valve, the air passage, and the cylinder's action. Since the solenoid valve voltage build-up has almost no delay, it begins to operate simultaneously with the command. Next, after the solenoid valve starts operating, compressed gas enters the shift cylinder through the solenoid valve and air passage. Then, when the pressure in the shift cylinder builds up to a certain level and overcomes the system resistance, the cylinder begins to move. Finally, the cylinder drives the shift fork and gear sleeve via the shift shaft to shift gears. The actual shifting only begins when the gear sleeve reaches the engagement teeth. Therefore, the system response time is the time from the issuance of the valve opening command to the completion of the shifting.

[0028] Therefore, without considering system response, there is a difference between the current speed difference and the actual speed difference at the gear shift. Only by considering the system response time and accurately predicting the speed difference at the time of gear shift can gear grinding be avoided. That is, this invention predicts the speed difference and issues a command in advance, ensuring that the time from the system response after the command is issued to the completion of gear shifting is consistent with the time when the speed difference reaches the threshold range, thereby achieving more accurate gear shifting and avoiding gear grinding.

[0029] In the above scheme, if the estimated gear shift speed difference Δn satisfies n1≤Δn≤n2, the brake valve is closed and gear engagement is performed; if the estimated gear shift speed difference Δn satisfies Δn<n1, the process of secondary clutch acceleration is entered, which is not within the protection scope of this invention; if the estimated gear shift speed difference Δn satisfies Δn>n2, the brake valve is opened to brake the intermediate shaft. As braking proceeds, the algorithm for estimating the speed difference continues to run until n1≤Δn≤n2 is satisfied, at which point gear engagement is performed directly; n1 and n2 are the set lower and upper limits of the speed threshold, respectively.

[0030] In the above scheme, the set time Δt between the current time t0 and the set time t1 is Δt = i * ti, where i is the set number of calculation cycles, which is determined according to the system response time and is generally taken as 50-100, and ti is the cycle. The Δt calculated in this way corresponds to the system response time, thereby ensuring that the valve action corresponds to the system response time.

[0031] In the above scheme, the estimated gear shift speed difference Δn is determined by the following formula:

[0032] △n = n * target gear ratio - spindle speed, where △n is the estimated shift speed difference and n is the estimated shift speed at the set time.

[0033] like Figure 2 As shown, the estimated gear shift speed n at the set time is determined by the following formula:

[0034] n = n0 + k1*△n1 + k2*△n2 + k3*△n3 + ... + ki*△ni, where n0 is the initial speed at the time of gear shift, k1, k2, ..., ki are the response coefficients of the 1st, 2nd, ..., ith cycles before the current time, respectively. The k value for each cycle is pre-calibrated, and the k values ​​may be the same or different for different cycles; △n1, △n1, ..., △ni are the speed reduction amounts of the 1st, 2nd, ..., ith cycles before the current time, respectively, with the i-th cycle being the cycle closest to the current time. The speed reduction amount of each cycle before the current time is measured by a speed sensor. If the number of cycles before the current moment is less than the set number of calculation cycles, then the cycle closest to the current moment is used as the basis to fill up to the set number of calculation cycles. For example, if i is set to 50, and only 20 cycles have been running before the current moment, then n = n0 + k1*△n1 + k2*△n2 + k3*△n3 + ... + k20*△n20 + k20*△n20*30.

[0035] Throughout the intermediate shaft braking process, the speed difference prediction method continues to run. As time goes by, the new k*△n replaces the first cycle. For example, the predicted shift speed n after one cycle is n0 + k2*△n2 + k3*△n3 + k4*△n4 + ... + k(i+1)*△n(i+1). This scheme can ensure a smoother change in speed difference and higher accuracy.

[0036] Example 1:

[0037] Assume the vehicle is accelerating from 4th to 6th gear. The initial speed during the upshift is n0 = 1500 rpm, the threshold is n1 = -200 rpm, n2 = +200 rpm, and the initial Δn = 500 rpm.

[0038] Upon clutch disengagement and gear shift completion, the shift speed difference is estimated after a one-cycle delay. Since the speed difference between 4th and 6th gear is large (Δn ≥ n2), the brake valve is opened to apply intermediate shaft braking. Assuming the total number of calculation cycles for the estimation method is i = 100, and one calculation cycle is 0.01s, the response time for shifting from 4th to 6th gear is Δt = i * 0.01s = 1s. As braking proceeds, the estimated speed difference is calculated using the algorithm Δn = n * target gear ratio - main shaft speed, and n = n0 + k1 * Δn1 + k2 * Δn2 + k3 * Δn3 + ... + ki * Δni = 1500 + k1 * Δn1 + ...

[0039] The process continues until Δn is between n1 and n2, such as 50 rpm (this value can be calibrated), at which point the intermediate shaft braking ends, and gear engagement is initiated. From the issuance of the gear engagement command to the actual execution of the gear engagement, there is a delay of approximately 1 second in the physical system. During actual gear engagement, the speed difference is generally within the threshold range (-200 rpm, +200 rpm), thus achieving relatively precise gear shifting without gear grinding or impact.

[0040] 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 may be rearranged without departing from the scope of this disclosure. The appended method claims provide elements of various steps in an exemplary order and are not intended to limit the scope to the specific order or hierarchy described.

[0041] To make the description of this disclosure more detailed and complete, illustrative descriptions of the embodiments and specific examples of the present invention have been provided above; however, this is not the only form of implementing or utilizing the specific examples of the present invention. The embodiments cover the features of multiple specific examples and the method steps and their order for constructing and operating these specific examples. However, other specific examples may also be used to achieve the same or equivalent functions and order of steps.

[0042] In the above detailed description, various features are combined together in a single embodiment to simplify this disclosure. This approach to disclosure should not be construed as reflecting an intention that embodiments of the claimed subject matter require more features than are explicitly stated in each claim. Rather, as reflected in the appended claims, the invention is presented with fewer features than all of the features of the single disclosed embodiment. Therefore, the appended claims are hereby explicitly incorporated into the detailed description, wherein each claim stands alone as a preferred embodiment of the invention.

[0043] The disclosed embodiments have been described above to enable any person skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be applied to other embodiments without departing from the spirit and scope of this disclosure. Therefore, this 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.

[0044] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Contents not described in detail in this specification belong to prior art known to those skilled in the art.

Claims

1. A braking control method for an AMT intermediate shaft, characterized in that: When the clutch disengages and the gear is engaged, after a delay of one cycle, the estimated gear shift speed difference at a set time after the current time is calculated in real time. Based on the estimated gear shift speed difference, it is determined whether to open the brake valve to brake the intermediate shaft or close the brake valve to engage the gear at the current time. The estimated gear shift speed difference is determined by the following formula: △n = n * target gear ratio - spindle speed, where △n is the estimated gear shift speed difference and n is the estimated gear shift speed at the set time; The estimated gear shift speed n at the set time is determined by the following formula: n = n0 + k1*△n1 + k2*△n2 + k3*△n3 + ... + ki*△ni, where n0 is the initial speed during gear shifting, k1, k2, ..., ki are the response coefficients of the 1st, 2nd, ..., ith cycles before the current time, respectively; △n1, △n1, ..., △ni are the speed reduction amounts of the 1st, 2nd, ..., ith cycles before the current time, respectively, and the ith cycle is the cycle closest to the current time.

2. The AMT intermediate shaft braking control method according to claim 1, characterized in that: The set time interval Δt between the current time and the set time is Δt = i * ti, where i is the set number of calculation cycles and ti is the cycle.

3. The AMT intermediate shaft braking control method according to claim 2, characterized in that: The value of i is 50-100.

4. The AMT intermediate shaft braking control method according to claim 1, characterized in that: The amount of speed reduction in each cycle before the current moment is measured by a speed sensor.

5. The AMT intermediate shaft braking control method according to claim 1, characterized in that: If the number of cycles before the current time is less than the set number of calculation cycles, then the set number of calculation cycles will be filled by using the cycle closest to the current time as the reference.

6. The AMT intermediate shaft braking control method according to claim 1, characterized in that: If the estimated gear shift speed difference Δn satisfies Δn>n2, then the brake valve is opened to brake the intermediate shaft; if the estimated gear shift speed difference Δn satisfies n1≤Δn≤n2, then the brake valve is closed to engage the gear, where n1 and n2 are the set lower and upper threshold limits, respectively.

7. The AMT intermediate shaft braking control method according to claim 6, characterized in that: The value of n1 is -300rpm to -100rpm.

8. The AMT intermediate shaft braking control method according to claim 6, characterized in that: The value of n2 is between 100 rpm and 300 rpm.

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