Method and system for controlling oil pressure of clutch of power shifting transmission

Abstract

The invention discloses an oil pressure control method and system for a clutch of a power gear shifting transmission, and belongs to the technical field of automatic transmissions.The method comprises the steps that the rotating speed of an engine is obtained, and corrected turbine torque is calculated by combining preset hydraulic torque converter parameters and torque converter dynamic characteristics; the current accelerator pedal position is obtained, a turbine angular acceleration target value is calculated and dynamically corrected, and the corrected dynamic turbine angular acceleration target value is obtained; according to the turbine torque and the dynamic turbine angular acceleration target value obtained through calculation, feedforward target oil pressure is calculated; calculating feedback target oil pressure according to the actual value of the turbine angular acceleration and the corrected target value of the dynamic turbine angular acceleration; according to the feedforward target oil pressure and the feedback target oil pressure, the target oil pressure of the clutch is calculated and converted into a control signal to be sent to an electromagnetic valve, the gear shifting time can be controlled, the gear shifting impact degree is reduced, the driving comfort is improved, and meanwhile the working efficiency of a hydraulic system in the gear shifting process is improved.

Description

Technical Field

[0001] The invention relates to a power shift transmission clutch oil pressure control method and system, belonging to the technical field of automatic transmissions. Background Art

[0002] The wet multi-plate clutch is an important component of the power shift transmission. Through the cooperation of multiple clutches in the transmission, the starting, shifting and reversing functions of the engineering vehicle can be realized. The engagement and disengagement of the clutch are realized by the electronically controlled hydraulic system of the transmission. When engaged, the hydraulic oil enters the cylinder through the oil filling oil channel, pushing the piston to press the master and slave plates of the clutch to achieve torque transmission; when disengaged, the hydraulic oil returns to the main oil tank, the cylinder pressure drops, and the piston returns to the starting position under the push of the return spring, and the torque transmission is interrupted.

[0003] The existing power shift transmission clutch oil pressure control method usually adopts a segmented oil pressure control strategy, which divides the power shift process into four stages: original gear, torque phase, inertia phase and new gear. Whether this control method can achieve a good balance between shift time, shift impact and sliding friction work, but whether the oil pressure strategy in each stage is reasonable depends largely on engineering experience. In addition, the existing method has poor adaptability to different working conditions, different vehicle models, and after the transmission system parts are worn, and cannot be adjusted according to the actual condition of the vehicle. Engineers need to debug according to engineering experience, which increases the consumption of manpower and material resources. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a power shift transmission clutch oil pressure control method and system, which can control the shift time, reduce the shift shock, improve driving comfort, and improve the working efficiency of the hydraulic system during the shift process.

[0005] To achieve the above object, the present invention is implemented by adopting the following technical solutions:

[0006] In a first aspect, the present invention provides a power shift transmission clutch oil pressure control method, comprising:

[0007] Obtain the engine speed and calculate the corrected turbine torque in combination with the preset torque converter parameters and the torque converter dynamic characteristics;

[0008] Obtain the current accelerator pedal position, calculate the turbine angular acceleration target value, and perform dynamic correction to obtain the corrected dynamic turbine angular acceleration target value;

[0009] Calculate the feedforward target oil pressure based on the calculated turbine torque and dynamic turbine angular acceleration target values;

[0010] Calculating the feedback target oil pressure according to the actual value of the turbine angular acceleration acquired in advance and the corrected dynamic turbine angular acceleration target value;

[0011] The clutch target oil pressure is calculated based on the feedforward target oil pressure and the feedback target oil pressure, and converted into a control signal and sent to the solenoid valve. The clutch oil pressure is controlled by the solenoid valve to realize the gear shifting action of the transmission.

[0012] Furthermore, the engine speed is obtained, and the corrected turbine torque is calculated in combination with the preset torque converter parameters and the torque converter dynamic characteristics, and the formula is as follows:

[0013] (1);

[0014] in, is the engine speed, is the pump impeller speed, is the pump impeller speed, is the turbine torque, is the pump wheel torque, is the corrected impeller torque, is the torque converter speed ratio, is the torque ratio of the torque converter, is the working medium oil density, is the acceleration due to gravity, is the effective diameter of the circulation circle, is the impeller torque coefficient.

[0015] Furthermore, the current accelerator pedal position is obtained, the turbine angular acceleration target value is calculated, and dynamic correction is performed. The dynamic correction formula is as follows:

[0016] (2);

[0017] in, is the corrected dynamic turbine angular acceleration target value, is the target value of turbine angular acceleration, is the period of the trigonometric function, is the current shift time, It is the time when the corrected dynamic turbine angular acceleration target value starts to decrease.

[0018] Furthermore, during the oil pressure control process, the oil pressure increases from 0. The target value is reached at Start to decline at The speed difference between the master and slave disks has been eliminated at this moment.

[0019] Furthermore, the change process of the dynamic turbine angular acceleration target value is fitted according to formula (2), and when the preset conditions are met, the dynamic turbine angular acceleration target value smoothly transitions from a preset initial value to 0.

[0020] Furthermore, the preset condition is: a speed difference between a theoretical value of the turbine speed for engaging the target gear at the current vehicle speed calculated based on the current transmission output shaft speed, the target gear and the preset gear ratios of each gear and the current turbine speed is equal to or less than a preset target speed difference.

[0021] Furthermore, the preset target speed difference is calculated by formula (3):

[0022] (3)

[0023] in, is the speed difference between the current turbine speed and the target turbine speed, is the current turbine speed, is the transmission output shaft speed, is the target gear ratio.

[0024] Furthermore, the feedforward target oil pressure is calculated according to the calculated turbine torque and dynamic turbine angular acceleration target value, and the formula is as follows:

[0025] (4);

[0026] in, is the feedforward target oil pressure, is the moment of inertia of the transmission input, is the number of clutch friction pairs, is the friction coefficient of the friction pair, is the clutch torque transmission radius, is the piston action area, is the return spring force.

[0027] In a second aspect, the present invention provides a power shift transmission clutch oil pressure control system, which adopts any of the above-mentioned power shift transmission clutch oil pressure control methods, the system includes: an engine, a torque converter, a transmission, a drive wheel, a clutch, a solenoid valve, a throttle position sensor, a first speed sensor, a second speed sensor, an engine control unit, and a transmission control unit, wherein the first speed sensor is installed on the torque converter, and the second speed sensor is installed on the output shaft of the transmission, wherein:

[0028] The engine control unit receives the engine speed and sends it to the transmission control unit. The first speed sensor sends the measured pump wheel speed and turbine speed to the transmission control unit. The second speed sensor sends the measured transmission output shaft speed to the transmission control unit. After receiving the data from the engine control unit, the first speed sensor and the second speed sensor, the transmission control unit calculates the clutch target oil pressure according to the internal preset parameters and sends the control signal to the solenoid valve. The solenoid valve controls the clutch oil pressure to realize the gear shifting action of the transmission.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The present invention provides a power shift transmission clutch oil pressure control method and system, which calculates the clutch target oil pressure and sends a control signal to a solenoid valve to control the clutch oil pressure, thereby realizing the shifting action of the vehicle transmission, controlling the shifting time, reducing the shifting shock, improving driving comfort, and improving the working efficiency of the hydraulic system during the shifting process. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A flow chart of a clutch oil pressure control method provided by one embodiment of the present invention;

[0032] Figure 2 A schematic diagram of a clutch oil pressure control method provided by an embodiment of the present invention;

[0033] Figure 3 A structural block diagram of a transmission electronically controlled hydraulic system provided by an embodiment of the present invention;

[0034] Figure 4 A curve diagram of a dynamic turbine angular acceleration target value provided by one embodiment of the present invention. DETAILED DESCRIPTION

[0035] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0036] Embodiment 1, as Figure 1 , Figure 2 As shown, this embodiment introduces a power shift transmission clutch oil pressure control method, including:

[0037] Obtain the engine speed and calculate the corrected turbine torque in combination with the preset torque converter parameters and the torque converter dynamic characteristics;

[0038] Obtain the current accelerator pedal position, calculate the turbine angular acceleration target value, and perform dynamic correction to obtain the corrected dynamic turbine angular acceleration target value;

[0039] Calculate the feedforward target oil pressure based on the calculated turbine torque and dynamic turbine angular acceleration target values;

[0040] According to the actual value of turbine angular acceleration acquired in advance and the corrected dynamic turbine angular acceleration target value;

[0041] The clutch target oil pressure is calculated based on the feedforward target oil pressure and the feedback target oil pressure, and converted into a control signal and sent to the solenoid valve. The clutch oil pressure is controlled by the solenoid valve to realize the gear shifting action of the transmission.

[0042] The power shift transmission clutch oil pressure control method provided in this embodiment is applied to the transmission electro-hydraulic control system, and its structure is shown in Figure 3 , which consists of an engine 1, a torque converter 2, a transmission 3, a drive wheel 4, a clutch 5, a solenoid valve 6, an accelerator position sensor 7, speed sensors 8 and 9, an engine control unit (ECU) 10, a transmission control unit (TCU) 11 and other signals 12.

[0043] The ECU receives the engine speed and sends it to the TCU; the speed sensor installed on the torque converter sends the measured pump and turbine speeds to the TCU; the speed sensor installed on the transmission output shaft sends the measured transmission output shaft speed to the TCU. After receiving the above data and signals, the TCU calculates the clutch target oil pressure based on the internal preset parameters and sends the control signal to the solenoid valve, thereby controlling the clutch oil pressure and achieving the shifting action of the vehicle transmission.

[0044] The following parameters and corresponding relationships are stored in the TCU: preset clutch torque transmission action radius, friction pair number, piston action area, friction pair friction coefficient, return spring force;

[0045] The correspondence between the preset pump wheel torque correction value and the actual value of the turbine angular acceleration;

[0046] The correspondence between the preset turbine angular acceleration target value and the throttle opening;

[0047] The correspondence between the preset trigonometric function period T and the throttle opening;

[0048] Preset transmission ratios for each gear.

[0049] The TCU receives the current engine speed from the ECU, the pump wheel speed and the turbine speed from the speed sensor, and calculates the theoretical value of the turbine torque based on the torque converter parameters, torque ratio and torque converter speed ratio preset in the TCU.

[0050] Specifically calculated by formula (1):

[0051] (1);

[0052] in, is the engine speed, is the pump impeller speed, is the pump impeller speed, is the turbine torque, is the pump wheel torque, is the corrected impeller torque, is the torque converter speed ratio, is the torque ratio of the torque converter, is the density of the working medium oil, is the acceleration due to gravity, is the effective diameter of the circulation circle, is the impeller torque coefficient.

[0053] Due to the harsh working conditions of construction machinery and large load fluctuations, the turbine speed fluctuation will cause the pump wheel torque fluctuation, making the calculation result of the static characteristic expression of the torque converter inaccurate. Therefore, the dynamic output torque of the pump wheel is corrected.

[0054] Dynamic output torque of pump wheel The corresponding relationship with the actual value of the turbine angular acceleration is stored in the TCU in the form of Table 1. The corresponding relationship is shown in Table 1:

[0055] Table 1 Correspondence between actual value of turbine angular acceleration and corrected value of pump output torque

[0056]

[0057] Next, the throttle position is obtained, and the turbine angular acceleration target value is obtained according to the correspondence between the preset throttle opening and the turbine angular acceleration target value. The correspondence between the preset turbine angular acceleration target value and the throttle opening is shown in Table 2:

[0058] Table 2 Correspondence between preset turbine angular acceleration target value and throttle opening

[0059]

[0060] At the same time, in order to avoid the sudden change of clutch target oil pressure and turbine angular acceleration target value at the beginning and end of starting or shifting, which may cause the transmission system to be impacted, the dynamic turbine angular acceleration target value is calculated. The calculation results are as follows: Figure 4 shown.

[0061] Specifically calculated by formula (2):

[0062] (2);

[0063] in, is the corrected dynamic turbine angular acceleration target value, is the target value of turbine angular acceleration, is the period of the trigonometric function, is the current shift time, It is the time when the corrected dynamic turbine angular acceleration target value starts to decrease.

[0064] The oil pressure starts to increase from 0. The target value is reached at Start to decline at The speed difference between the master and slave disks has been eliminated at this moment. The value of can be set according to engineering experience or preset The corresponding relationship between the preset trigonometric function period T and the throttle opening is shown in Table 3:

[0065] Table 3 Correspondence between the preset trigonometric function period T and the throttle opening

[0066]

[0067] The calculation is performed as follows: The TCU calculates the theoretical value of the turbine speed at the target gear under the current vehicle speed based on the current transmission output shaft speed, the target gear and the preset transmission ratios of each gear, and calculates the speed difference between the current turbine speed and the theoretical value of the turbine speed at the target gear, and compares it with the preset target speed difference.

[0068] The preset target speed difference is calculated by formula (3):

[0069] (3);

[0070] in, is the speed difference between the current turbine speed and the target turbine speed, is the current turbine speed, is the transmission output shaft speed, is the target gear ratio.

[0071] The speed difference between the current turbine speed and the turbine speed at the target gear is equal to or less than When the dynamic turbine angular acceleration target value starts to smoothly transition from the preset turbine angular acceleration target value to 0 according to the dynamic turbine angular acceleration target value fitted by the trigonometric function of formula (2). The corrected dynamic turbine angular acceleration target value is as follows: Figure 4 shown.

[0072] Afterwards, the TCU calculates the turbine torque based on the above calculation. , Corrected dynamic turbine angular acceleration target value , as well as the preset clutch transmission torque action radius, friction pair logarithm, piston action area, friction pair friction coefficient, and return spring force, calculate the feedforward target oil pressure.

[0073] The feedforward target oil pressure is calculated by formula (4):

[0074] (4);

[0075] in, is the feedforward target oil pressure, is the moment of inertia of the transmission input, is the number of clutch friction pairs, is the friction coefficient of the friction pair, is the clutch torque transmission radius, is the piston action area, is the return spring force.

[0076] According to the difference between the target turbine speed change rate and the actual turbine speed change rate, PID adjustment is performed to obtain the feedback target oil pressure. The proportional coefficient, integral coefficient, and differential coefficient of the PID adjustment coefficient need to be determined according to the specific parameters and performance of the transmission.

[0077] Embodiment 2, the present invention provides a power shift transmission clutch oil pressure control system, adopting the power shift transmission clutch oil pressure control method described in any one of Embodiment 1, the system comprises: an engine, a torque converter, a transmission, a driving wheel, a clutch, a solenoid valve, a throttle position sensor, a first speed sensor, a second speed sensor, an engine control unit, and a transmission control unit, wherein the first speed sensor is installed on the torque converter, and the second speed sensor is installed on the output shaft of the transmission, wherein:

[0078] The engine control unit receives the engine speed and sends it to the transmission control unit. The first speed sensor sends the measured pump wheel speed and turbine speed to the transmission control unit. The second speed sensor sends the measured transmission output shaft speed to the transmission control unit. After receiving the data from the engine control unit, the first speed sensor and the second speed sensor, the transmission control unit calculates the clutch target oil pressure according to the internal preset parameters and sends the control signal to the solenoid valve. The solenoid valve controls the clutch oil pressure to realize the gear shifting action of the transmission.

[0079] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A power shift transmission clutch oil pressure control method, characterized in that: include: Obtain the engine speed and calculate the corrected turbine torque in combination with the preset torque converter parameters and the torque converter dynamic characteristics; Obtain the current accelerator pedal position, calculate the turbine angular acceleration target value, and perform dynamic correction to obtain the corrected dynamic turbine angular acceleration target value; Calculate the feedforward target oil pressure based on the calculated turbine torque and dynamic turbine angular acceleration target values; Calculating the feedback target oil pressure according to the actual value of the turbine angular acceleration acquired in advance and the corrected dynamic turbine angular acceleration target value; The clutch target oil pressure is calculated based on the feedforward target oil pressure and the feedback target oil pressure, and converted into a control signal and sent to the solenoid valve. The clutch oil pressure is controlled by the solenoid valve to realize the gear shifting action of the transmission.

2. The power shift transmission clutch oil pressure control method according to claim 1, characterized in that: The engine speed is obtained, and the corrected turbine torque is calculated in combination with the preset torque converter parameters and the torque converter dynamic characteristics. The formula is as follows: (1)； in, is the engine speed, is the pump impeller speed, is the pump impeller speed, is the turbine torque, is the pump wheel torque, is the corrected impeller torque, is the torque converter speed ratio, is the torque ratio of the torque converter, is the density of the working medium oil, is the acceleration due to gravity, is the effective diameter of the circulation circle, is the impeller torque coefficient.

3. The power shift transmission clutch oil pressure control method according to claim 1, characterized in that: The current accelerator pedal position is obtained, the turbine angular acceleration target value is calculated, and dynamic correction is performed. The dynamic correction formula is as follows: (2)； in, is the corrected dynamic turbine angular acceleration target value, is the target value of turbine angular acceleration, is the period of the trigonometric function, is the current shift time, It is the time when the corrected dynamic turbine angular acceleration target value starts to decrease.

4. The power shift transmission clutch oil pressure control method according to claim 3, characterized in that: During the oil pressure control process, the oil pressure starts to increase from 0. The target value is reached at Start to decline at The speed difference between the master and slave disks has been eliminated at this moment.

5. The power shift transmission clutch oil pressure control method according to claim 3, characterized in that: The change process of the dynamic turbine angular acceleration target value is fitted according to formula (2), and when the preset conditions are met, the dynamic turbine angular acceleration target value smoothly transitions from a preset initial value to 0.

6. The power shift transmission clutch oil pressure control method according to claim 5, characterized in that: The preset condition is: the speed difference between the theoretical value of the turbine speed for engaging the target gear at the current vehicle speed, which is calculated based on the current transmission output shaft speed, the target gear and the preset gear ratios of each gear, and the current turbine speed is equal to or less than the preset target speed difference.

7. The power shift transmission clutch oil pressure control method according to claim 6, characterized in that: The preset target speed difference is calculated by formula (3): (3) in, is the speed difference between the current turbine speed and the target turbine speed, is the current turbine speed, is the transmission output shaft speed, is the target gear ratio.

8. The power shift transmission clutch oil pressure control method according to claim 1, characterized in that: The feedforward target oil pressure is calculated based on the calculated turbine torque and dynamic turbine angular acceleration target value, and the formula is as follows: (4)； in, is the feedforward target oil pressure, is the moment of inertia of the transmission input, is the number of clutch friction pairs, is the friction coefficient of the friction pair, is the clutch torque transmission radius, is the piston action area, is the return spring force.

9. A power shift transmission clutch oil pressure control system, using the power shift transmission clutch oil pressure control method according to any one of claims 1 to 8, the system comprising: An engine, a torque converter, a transmission, a driving wheel, a clutch, a solenoid valve, a throttle position sensor, a first speed sensor, a second speed sensor, an engine control unit, and a transmission control unit, wherein the first speed sensor is mounted on the torque converter, and the second speed sensor is mounted on the output shaft of the transmission, wherein: The engine control unit receives the engine speed and sends it to the transmission control unit. The first speed sensor sends the measured pump wheel speed and turbine speed to the transmission control unit. The second speed sensor sends the measured transmission output shaft speed to the transmission control unit. After receiving the data from the engine control unit, the first speed sensor and the second speed sensor, the transmission control unit calculates the clutch target oil pressure according to the internal preset parameters and sends the control signal to the solenoid valve. The clutch oil pressure is controlled by the solenoid valve to realize the gear shifting action of the transmission.

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