A power take-off control system and control method for an electro-hydraulic AMT

Abstract

This invention relates to a power take-off (PTO) control system and method for an electro-hydraulic automatic transmission (AMT), solving the technical problems of existing electro-hydraulic AMTs where the PTO relies on an air source and the system is complex and costly. The invention includes a PTO request button, a TCU (Transmission Control Unit), a PTO, an electro-hydraulic clutch disengagement mechanism, an electromagnetic hydraulic valve, and a clutch hydraulic release bearing. The electro-hydraulic clutch disengagement mechanism includes an ECU (Electronic Control Unit), a motor connected to the ECU, a ball screw, and a release hydraulic cylinder. The input end of the electromagnetic hydraulic valve is connected to the hydraulic chamber of the release hydraulic cylinder, and the two output ends are connected to the hydraulic chambers of the PTO hydraulic cylinder and the clutch hydraulic release bearing, respectively. The control end is connected to the ECU. The output ends can be switched by controlling the movement of the electromagnetic hydraulic valve spool via the ECU. The ECU controls the motor to operate, which drives the ball screw to push the piston rod of the release hydraulic cylinder, ultimately causing the PTO shift fork shaft to move under the action of hydraulic oil, thus achieving control of the PTO.

Description

Technical Field

[0001] This invention belongs to the field of power take-off control technology, specifically relating to a power take-off control system and control method for an electro-hydraulic AMT. Background Technology

[0002] An electro-hydraulic AMT (Automated Manual Transmission) is an automatic mechanical transmission based on a mechanical gearbox body, employing an electric shift actuator and an electro-hydraulic clutch disengagement mechanism. It is primarily used in light and medium-duty trucks and special-purpose vehicles. Some customers require power take-off from the transmission due to the need to drive external equipment such as pumps or motors.

[0003] Currently, the power take-off (PTO) commonly used in commercial vehicle AMTs is the electro-pneumatic PTO. For example, Chinese patent CN108087540A discloses an AMT PTO control system and method. This system introduces an air source into the PTO solenoid valve and controls the solenoid valve's operation through the AMT controller TCU, allowing compressed air to enter the PTO cylinder and achieve power take-off. However, this control method is highly dependent on the air source and must be connected to the vehicle's air supply to operate.

[0004] For traditional commercial vehicle AMTs, both the shift actuator and clutch disengagement mechanism use electro-pneumatic solutions, requiring an air supply from the vehicle to realize the transmission function. However, for electro-hydraulic AMTs, both the shift actuator and clutch disengagement mechanism use electro- or electro-hydraulic solutions. Shifting is achieved by a shift motor driving related components, and the motor actuates the hydraulic cylinder piston rod to control clutch disengagement and engagement. It does not require an air supply from the vehicle itself. If an electro-hydraulic AMT still uses an electro-pneumatic power take-off (PTO), it requires an additional air supply from the vehicle. Furthermore, the solenoid valve itself has certain requirements for air pressure and air quality, necessitating the addition of a pressure regulating valve and filter in the air circuit, increasing the system complexity. In addition, the air pipes need to be arranged according to the vehicle space and transmission housing; long-term use may lead to bending and leakage risks, causing PTO failure. Summary of the Invention

[0005] The purpose of this invention is to solve the technical problems of existing electro-hydraulic AMTs, such as the power take-off unit relying on an air source, and the system being complex and costly. The invention provides a power take-off control system and control method for electro-hydraulic AMTs.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] A power take-off (PTO) control system for an electro-hydraulic automatic transmission (AMT) includes a PTO request button, a TCU (Transmission Control Unit), and a PTO; its distinctive feature is that:

[0008] It also includes an electro-hydraulic clutch release mechanism, an electromagnetic hydraulic valve, and a clutch hydraulic release bearing;

[0009] The power take-off (PTO) request button is located in the cab and is connected to the TCU via a hardwire; the TCU is located on the electro-hydraulic AMT; the PTO includes a pressure switch connected to the TCU, which is used to monitor the status of the PTO.

[0010] The electro-hydraulic clutch release mechanism includes an ECU that communicates with the TCU via CAN, a drive assembly connected to the ECU, and a release hydraulic cylinder connected to the drive assembly. The ECU controls the drive assembly to make the release hydraulic cylinder move.

[0011] The input end of the electromagnetic hydraulic valve is connected to the hydraulic chamber of the release hydraulic cylinder, and the two output ends are connected to the hydraulic chamber of the power take-off hydraulic cylinder and the hydraulic chamber of the clutch hydraulic release bearing, respectively. The control end is connected to the ECU.

[0012] The electromagnetic hydraulic valve is controlled by the ECU to move the valve core to switch between two outputs, forming either the power take-off (PTO) working mode or the clutch working mode. In the PTO working mode, the electromagnetic hydraulic valve is connected to the PTO hydraulic cylinder and disconnected from the clutch hydraulic release bearing, forming a PTO hydraulic circuit to enable the PTO to open and close. In the clutch working mode, the electromagnetic hydraulic valve is connected to the clutch hydraulic release bearing and disconnected from the PTO hydraulic cylinder, forming a clutch hydraulic circuit to enable the clutch to disengage and engage.

[0013] Furthermore, the drive components of the electro-hydraulic clutch disengagement mechanism include a motor and a ball screw;

[0014] The ECU is located on the motor;

[0015] The ball screw is connected to the output end of the motor, and the nut is connected to the piston rod of the separation hydraulic cylinder, which is used to convert the rotational motion of the motor into the linear motion of the piston rod of the separation hydraulic cylinder.

[0016] Furthermore, an oil reservoir is provided at one end of the piston rod on the separating hydraulic cylinder for depressurizing or replenishing the hydraulic circuit connected to the separating hydraulic cylinder;

[0017] The separating hydraulic cylinder is equipped with a pressure sensor that is connected to its hydraulic chamber. The pressure sensor is connected to the ECU and is used to monitor the oil pressure in the hydraulic chamber of the separating hydraulic cylinder.

[0018] Furthermore, the control terminal of the electromagnetic hydraulic valve is hardwired to the ECU;

[0019] The pressure sensor is hardwired to the ECU.

[0020] Furthermore, the power take-off includes a self-returning spring, a shift fork shaft, a shift fork, an output shaft, an output gear, a flange, an input gear, and an input shaft;

[0021] A self-returning spring is provided on one side of the piston rod of the power take-off hydraulic cylinder, and the piston rod forms the shift fork shaft;

[0022] The pressure switch is installed at the end of the shift fork shaft with a gap. When the shift fork shaft moves under hydraulic pressure and abuts the pressure switch contact, the power take-off opens, and the circuit between the pressure switch and the TCU is connected. When the shift fork shaft moves away from the pressure switch contact under the action of the self-returning spring, the power take-off closes, and the circuit between the pressure switch and the TCU is disconnected.

[0023] The shift fork is interference-fitted onto the shift fork shaft; the output gear is movably fitted onto the output shaft, and the output gear has a shift fork groove, into which the shift fork is inserted; the flange is located at one end of the output shaft.

[0024] The input shaft and output shaft are set parallel to each other, and the input gear is set on the input shaft to engage or disengage with the output gear when the shift fork is in motion.

[0025] Furthermore, the pressure switch is hardwired to the TCU.

[0026] This invention also provides a power take-off control method for an electro-hydraulic AMT, implemented through the aforementioned power take-off control system for an electro-hydraulic AMT, characterized by the following steps:

[0027] S1, Press the PTO request button, the circuit connected between the PTO request button and the TCU is connected, and a PTO open signal is generated;

[0028] S2, the TCU receives the power take-off (PTO) open signal and determines whether the PTO conditions are met based on the vehicle and transmission operating conditions;

[0029] If the power take-off determination condition is met, the TCU generates a control command to open the power take-off and sends it to the ECU. The ECU controls the solenoid hydraulic valve to open and switches the solenoid hydraulic valve to the power take-off working mode.

[0030] If the force-taking condition is not met, proceed to step S6.

[0031] S3, the ECU controls the piston rod movement of the separation hydraulic cylinder through the drive component, thereby controlling the power take-off to open;

[0032] S4, TCU determines whether it has received an open signal from the pressure switch;

[0033] When the power take-off is fully engaged, the pressure switch opens; otherwise, the pressure switch closes, and the ECU continues to control the piston rod movement of the disengagement hydraulic cylinder via the drive assembly.

[0034] S5, after the TCU receives the open signal of the pressure switch, it sends a control command to the ECU that the power take-off has been opened;

[0035] S6, the ECU controls the solenoid hydraulic valve to close, the solenoid hydraulic valve switches to the clutch working mode, and the ECU controls the drive components according to the clutch control command of the TCU.

[0036] At this time, the hydraulic circuit between the electromagnetic hydraulic valve and the power take-off hydraulic cylinder is in a pressure-holding state, and the power take-off remains open.

[0037] S7: When the power take-off (PTO) is turned off, pressing the PTO request button again will reset the PTO request button.

[0038] The circuit connected to the TCU is disconnected, generating a power take-off (PTO) shutdown signal;

[0039] S8, the TCU receives the power take-off shutdown signal and determines whether the power take-off shutdown conditions are met based on the vehicle and transmission operating conditions;

[0040] If the conditions for power take-off shutdown are met, the TCU generates a control command to shut down the power take-off and sends it to the ECU. The ECU then controls the piston rod of the separation hydraulic cylinder to move in the opposite direction through the drive assembly.

[0041] If the power take-off shutdown condition is not met, proceed to step S12;

[0042] S9, the ECU makes a judgment based on the pressure value of the pressure sensor;

[0043] When the pressure value is less than the set threshold, the ECU controls the solenoid hydraulic valve to open and switches the solenoid hydraulic valve to the power take-off mode; otherwise, the ECU continues to control the piston rod of the separation hydraulic cylinder to move in the reverse direction through the drive component.

[0044] S10, the TCU determines whether it has received a pressure switch shutdown signal;

[0045] When the power take-off (PTO) is closed, the pressure switch is closed; otherwise, the pressure switch is open, and the ECU maintains the solenoid hydraulic valve in the PTO operating mode.

[0046] S11, after the TCU receives the pressure switch's closing signal, it sends a control command to the ECU that the power take-off has been closed;

[0047] S12, the ECU controls the solenoid hydraulic valve to close, the solenoid hydraulic valve switches to the clutch working mode, and the ECU controls the drive components according to the clutch control command of the TCU.

[0048] At this time, the hydraulic oil in the power take-off (PTO) hydraulic circuit has been squeezed into the separation hydraulic cylinder under the action of the self-returning spring, and the solenoid hydraulic valve is closed, the PTO is in the closed state, the power take-off ends, and the PTO control of the electro-hydraulic AMT is realized.

[0049] Further, step S3 specifically involves the ECU controlling the motor to rotate forward, the ball screw pushing the piston rod of the separation hydraulic cylinder to move, and the hydraulic oil in the separation hydraulic cylinder being squeezed into the hydraulic chamber of the power take-off hydraulic cylinder through the electromagnetic hydraulic valve. Under the action of hydraulic pressure, the piston rod of the power take-off hydraulic cylinder, i.e. the shift fork shaft, moves, and the shift fork on the shift fork shaft drives the output gear to mesh with the input gear, thereby opening the power take-off.

[0050] In step S8, if the power take-off shut-off condition is met, the ECU controls the motor to reverse, which drives the piston rod of the separation hydraulic cylinder to move in the opposite direction via the ball screw, and the oil pressure in the separation hydraulic cylinder decreases.

[0051] In step S9, when the oil pressure is lower than the set threshold, the ECU controls the solenoid hydraulic valve to open. When the hydraulic pressure acting on the piston surface of the power take-off hydraulic cylinder is less than the force of the self-returning spring, the shift fork moves in the opposite direction. The shift fork on the shift fork shaft drives the output gear to separate from the input gear, thereby closing the power take-off.

[0052] Further, in step S4, the power take-off is opened specifically as follows: the shift fork shaft moves, and after its end abuts against the contact of the pressure switch, the circuit between the pressure switch and the TCU is connected, generating a pressure switch open signal.

[0053] In step S10, the power take-off is closed specifically by the shift fork shaft moving in the reverse direction. After its end separates from the contact of the pressure switch, the circuit between the pressure switch and the TCU is broken, generating a pressure switch closing signal.

[0054] The advantages of this invention compared to the prior art are:

[0055] This invention provides a power take-off (PTO) control system for an electro-hydraulic automatic transmission (AMT). An electromagnetic hydraulic valve is installed in the oil circuit between the release hydraulic cylinder and the clutch hydraulic release bearing of the electro-hydraulic clutch release mechanism. Therefore, the hydraulic oil in the electro-hydraulic clutch release mechanism must first enter the electromagnetic hydraulic valve before entering the clutch hydraulic release bearing. This allows the ECU to control the movement of the electromagnetic hydraulic valve spool, thereby controlling the electro-hydraulic clutch release mechanism to switch between the hydraulic circuit with the clutch and the hydraulic circuit with the PTO. The ECU also controls the piston rod movement of the release hydraulic cylinder of the electro-hydraulic clutch release mechanism to open and close the PTO. This invention directly utilizes the hydraulic system and ECU of the electro-hydraulic clutch actuator within the electro-hydraulic AMT itself, avoiding the introduction of too many components, simplifying the system structure, effectively reducing the complexity of using the PTO in an electro-hydraulic AMT, and eliminating the need to rely on the vehicle's air supply. Attached Figure Description

[0056] Figure 1 This is a schematic diagram of the structure of a power take-off control system embodiment of an electro-hydraulic AMT according to the present invention;

[0057] Figure 2 This is a schematic diagram of the power take-off structure in an embodiment of the power take-off control system of an electro-hydraulic AMT according to the present invention;

[0058] Figure 3 This is a flowchart illustrating the process of controlling the opening of the power take-off in an embodiment of the electro-hydraulic AMT power take-off control method of the present invention;

[0059] Figure 4 This is a flowchart illustrating the control method for shutting down the power take-off unit in an embodiment of the electro-hydraulic AMT of the present invention.

[0060] The symbols in the attached image are explained as follows:

[0061] 1-Power Take-Off Request Button; 2-TCU;

[0062] 3-ECU; 4-Motor; 5-Ball screw; 6-Separation hydraulic cylinder; 7-Oil reservoir; 8-Pressure sensor;

[0063] 9-Electromagnetic hydraulic valve;

[0064] 10-Power take-off hydraulic cylinder; 11-Self-returning spring; 12-Shift fork shaft; 13-Shift fork; 14-Pressure switch; 15-Output shaft; 16-Output gear; 17-Flange; 18-Input gear; 19-Input shaft;

[0065] 20 - Power take-off; 21 - Clutch hydraulic release bearing; 22 - Electro-hydraulic clutch release mechanism. Detailed Implementation

[0066] The specific technical solutions in the embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0067] Figure 1 An electro-hydraulic AMT power take-off control system provided in this embodiment of the invention includes a power take-off request button 1, a TCU 2, an electro-hydraulic clutch disengagement mechanism 22, an electromagnetic hydraulic valve 9, a power take-off 20, and a clutch hydraulic release bearing 21.

[0068] The electro-hydraulic clutch disengagement mechanism 22 includes an ECU 3, a motor 4, a ball screw 5, a disengagement hydraulic cylinder 6, an oil reservoir 7, and a pressure sensor 8. The ECU 3 is mounted on the motor 4. The screw of the ball screw 5 is connected to the motor 4, and the nut is connected to the disengagement hydraulic cylinder 6. The disengagement hydraulic cylinder 6 is equipped with the oil reservoir 7 and the pressure sensor 8. The ECU 3 controls the rotation of the motor 4, and the ball screw 5 converts the rotational motion of the motor 4 into the linear motion of the piston rod of the disengagement hydraulic cylinder 6. The pressure sensor 8 is connected to the ECU 3 via a hard wire and is used to monitor the oil pressure in the hydraulic chamber of the disengagement hydraulic cylinder 6. The oil reservoir 7 is located at one end of the piston rod of the disengagement hydraulic cylinder 6 and has a certain back pressure, used to depressurize or replenish the hydraulic circuit connected to the hydraulic chamber of the disengagement hydraulic cylinder 6. Under normal circumstances, the oil reservoir 7 is not connected to the hydraulic chamber of the disengagement hydraulic cylinder 6. Only when the oil pressure received by the ECU 3 exceeds the set range will it control the motor 4 to continuously reverse until the oil reservoir 7 connects to the hydraulic chamber of the disengagement hydraulic cylinder 6, and the hydraulic oil is depressurized or replenished under the action of the pressure difference. At the same time, the oil pressure measured by pressure sensor 8 is also used to provide ECU 3 with the timing for controlling solenoid hydraulic valve 9.

[0069] The power take-off (PTO) request button 1 is located in the cab, and the TCU2 is located on the electro-hydraulic AMT mechanical body. The TCU2 is connected to the PTO request button 1 via a hard wire, and the ECU3 communicates with the TCU2 via a CAN bus. The TCU2 obtains the PTO open or closed signal by checking the circuit connection with the PTO request button 1, and generates control commands based on the vehicle and transmission operating conditions, sending them to the ECU3 via the CAN bus.

[0070] See Figure 2 The power take-off (PTO) 20 includes a PTO hydraulic cylinder 10, a self-returning spring 11, a shift fork shaft 12, a shift fork 13, a pressure switch 14, an output shaft 15, an output gear 16, a flange 17, an input gear 18, and an input shaft 19.

[0071] A self-returning spring 11 is provided on one side of the piston rod of the power take-off hydraulic cylinder 10, and the piston rod is the shift fork shaft 12. A pressure switch 14 is located at a certain interval at the end of the shift fork shaft 12 and is connected to the TCU2 via a hard wire. The TCU2 determines the state of the power take-off 20 based on the continuity of the circuit with the pressure switch 14. When the end of the shift fork shaft 12 abuts against the contact of the pressure switch 14, the power take-off 20 is opened, and the circuit between the pressure switch 14 and the TCU2 is connected; otherwise, the circuit between the pressure switch 14 and the TCU2 is disconnected. The movement of the shift fork shaft 12 is equivalent to the extension and retraction of the piston rod of the power take-off hydraulic cylinder 10. When the hydraulic pressure acting on the piston of the power take-off hydraulic cylinder 10 is greater than the elastic force of the self-returning spring, the shift fork shaft 12 extends; conversely, the shift fork shaft 12 retracts.

[0072] The shift fork 13 is interference-fitted onto the shift fork shaft 12; the output gear 16 is a sliding gear with its own shift fork groove, and the output gear 16 is splined to the output shaft 15, with the shift fork 13 inserted into the shift fork groove of the output gear 16; one end of the output shaft 15 is provided with a flange 17 for connecting external equipment; the input shaft 19 is arranged parallel to the output shaft 15, and the input gear 18 is interference-fitted to the input shaft 19. The input gear 18 is a double gear, one of which is constantly meshed with the gearbox gear, and the other gear meshes with the output gear 16 when the shift fork 13 is in motion.

[0073] When the power take-off (PTO) 20 is open, the shift fork shaft 12 extends under hydraulic pressure. When the output gear 16 engages with the input gear 18, the end of the shift fork shaft 12 abuts against the contact of the pressure switch 14, turning on the pressure switch 14. The TCU2 receives an open signal from the pressure switch 14 (PTO open signal). When the PTO 20 is closed, the shift fork shaft 12 retracts under the action of the self-returning spring 11. When the output gear 16 and the input gear 18 are not engaged, the end of the shift fork shaft 12 has moved away from the contact of the pressure switch 14, and the TCU2 receives an open signal from the pressure switch 14 (PTO closed signal).

[0074] The electromagnetic hydraulic valve 9 is a two-position three-way valve, with the two positions corresponding to the power take-off (PTO) working mode and the clutch working mode, respectively. Its input end is connected to the hydraulic chamber of the release hydraulic cylinder 6, and its two output ends are connected to the hydraulic chambers of the PTO hydraulic cylinder 10 and the clutch hydraulic release bearing 21, respectively. The control end is connected to the ECU 3 via a hardwired connection. The electromagnetic hydraulic valve 9 is mounted on the electro-hydraulic AMT mechanical body.

[0075] The electromagnetic hydraulic valve 9 is controlled by the ECU3 to move the valve core and switch between the two outputs, thus forming either the power take-off (PTO) working mode or the clutch working mode. Specifically, the hydraulic oil in the electro-hydraulic clutch release mechanism 22 must first enter the electromagnetic hydraulic valve 9. By controlling the electromagnetic hydraulic valve 9, the switching between the hydraulic circuit from the electro-hydraulic clutch release mechanism 22 to the clutch hydraulic release bearing 21 and the hydraulic circuit from the electro-hydraulic clutch release mechanism 22 to the PTO 20 is achieved.

[0076] In this configuration, the power take-off (PTO) operates in a mode where the hydraulic cylinder 6 and the solenoid hydraulic valve 9 are connected to the PTO hydraulic cylinder 10 (also considered as the solenoid hydraulic valve 9 being open), while simultaneously disconnected from the clutch hydraulic release bearing 21, thereby driving the PTO 20 to open and close. Similarly, in the clutch operating mode, the hydraulic cylinder 6 and the solenoid hydraulic valve 9 are connected to the clutch hydraulic release bearing 21, while simultaneously disconnected from the PTO hydraulic cylinder 10 (also considered as the solenoid hydraulic valve 9 being closed), thereby driving the clutch to operate and controlling its disengagement or engagement. The solenoid hydraulic valve 9 is in clutch operating mode by default, ensuring that the electro-hydraulic clutch actuator 22 can continuously control clutch action when the PTO is used during driving.

[0077] In the electro-hydraulic clutch disengagement mechanism 22, when the motor 4 rotates forward, the piston forces the hydraulic oil in the disengagement hydraulic cylinder 6 into the hydraulic circuit of the power take-off 20 or the clutch hydraulic disengagement bearing 21, thereby opening the power take-off or disengaging the clutch. When the motor 4 rotates in reverse, the piston rod moves in the opposite direction, and the hydraulic oil in the hydraulic circuit flows back to the disengagement hydraulic cylinder 6 under the action of the self-returning spring 11 of the power take-off hydraulic cylinder 10 or the clutch diaphragm spring, thereby closing the power take-off or engaging the clutch.

[0078] See Figures 3-4 The specific steps of the power take-off control method according to this embodiment of the invention are as follows:

[0079] S1, the driver presses the power take-off request button 1, the circuit connected to the power take-off request button 1 and TCU2 is connected, generating a power take-off open signal;

[0080] S2, TCU2 obtains the power take-off (PTO) open signal and determines whether the PTO determination conditions are met based on the vehicle and transmission operating conditions;

[0081] If the power take-off determination condition is met, TCU2 generates a control command to open the power take-off unit and sends it to ECU3 via CAN line. ECU3 controls the solenoid hydraulic valve 9 to open and switches the solenoid hydraulic valve 9 to the power take-off unit working mode.

[0082] If the force-taking condition is not met, proceed to step S6.

[0083] S3, after the electromagnetic hydraulic valve 9 is opened, the ECU3 controls the motor 4 to rotate forward, the ball screw 5 pushes the piston rod of the separation hydraulic cylinder 6 to move, and the hydraulic oil in the separation hydraulic cylinder 6 is squeezed into the hydraulic chamber of the power take-off hydraulic cylinder 10 through the electromagnetic hydraulic valve 9. Under the action of hydraulic pressure, the shift fork shaft 12 moves, and the shift fork 13 on the shift fork shaft 12 drives the output gear 16 to mesh with the input gear 18, so as to open the power take-off 20.

[0084] S4, TCU2 determines whether it has received an open signal from pressure switch 14;

[0085] When the power take-off 20 is opened, the end of the shift fork shaft 12 abuts against the contact of the pressure switch 14, and the circuit of the pressure switch 14 and TCU2 is connected, generating an open signal of the pressure switch 14; if the TCU2 does not receive the open signal of the pressure switch 14, the TCU2 continues to send the control command of the power take-off to the ECU3, and the ECU3 continues to control the motor 4 to rotate forward.

[0086] S5, after TCU2 receives the open signal of pressure switch 14, it generates a control command that the power take-off is open and sends it to ECU3 via CAN line;

[0087] S6, ECU3 controls the solenoid hydraulic valve 9 to close, the solenoid hydraulic valve 9 switches to the clutch working mode, and ECU3 controls the motor to run according to the clutch control command of TCU2.

[0088] At this time, the hydraulic circuit between the electromagnetic hydraulic valve 9 and the power take-off hydraulic cylinder 10 is in a pressure-holding state, and the power take-off 20 remains open.

[0089] S7, when the power take-off 20 is turned off, press the power take-off request button 1 again, the power take-off request button 1 is reset, the circuit connecting the power take-off request button 1 and TCU2 is disconnected, and a power take-off off signal is generated.

[0090] S8, TCU2 receives the power take-off shutdown signal and determines whether the power take-off shutdown conditions are met based on the vehicle and transmission operating conditions;

[0091] If the conditions for power take-off shutdown are met, TCU2 generates a control command to shut down the power take-off unit and sends it to ECU3 via the CAN line. ECU3 controls motor 4 to reverse, which drives the piston rod of the separation hydraulic cylinder 6 to move in the opposite direction via ball screw 5.

[0092] If the power take-off shutdown condition is not met, proceed to step S12;

[0093] S9, ECU3 makes a judgment based on the pressure value of pressure sensor 8;

[0094] When the pressure value is less than the set threshold, ECU3 controls the solenoid hydraulic valve 9 to open and switches the solenoid hydraulic valve 9 to the power take-off working mode; otherwise, ECU3 continues to control the motor 4 to reverse.

[0095] When the electromagnetic hydraulic valve 9 is opened, under the action of pressure difference, the hydraulic oil in the power take-off hydraulic cylinder 10 flows back to the hydraulic chamber of the separation hydraulic cylinder 6 through the electromagnetic hydraulic valve 9, and the oil pressure in the power take-off hydraulic cylinder 10 decreases. When the hydraulic pressure is less than the spring force of the self-returning spring 11, the shift fork shaft 12 moves in the opposite direction, and the shift fork 13 on the shift fork shaft 12 drives the output gear 16 to separate from the input gear 18, thereby closing the power take-off 20.

[0096] S10, TCU2 determines whether it has received a closing signal from pressure switch 14;

[0097] When the power take-off 20 is closed, that is, after the end of the shift fork shaft 12 separates from the contact of the pressure switch 14, the circuit between the TCU2 and the pressure switch 14 is disconnected, generating a pressure switch 14 closing signal; if the TCU2 does not receive the pressure switch 14 closing signal, the TCU2 continues to send the power take-off closing control command to the ECU3, and the ECU3 maintains the electromagnetic hydraulic valve 9 in the power take-off working mode.

[0098] S11, after TCU2 receives the closing signal of pressure switch 14, it generates a control command that the power take-off is closed and sends it to ECU3 via CAN line;

[0099] S12, ECU3 controls the solenoid hydraulic valve 9 to close, the solenoid hydraulic valve 9 switches to the clutch working mode, and ECU3 controls the motor to run according to the clutch control command of TCU2.

[0100] At this time, the hydraulic oil in the power take-off hydraulic circuit has been squeezed into the separation hydraulic cylinder 6 under the action of the self-returning spring 11, and the electromagnetic hydraulic valve 9 is closed, the power take-off 20 is in the closed state, the power take-off ends, and the power take-off control of the electro-hydraulic AMT is realized.

[0101] The working principle of this invention embodiment is as follows:

[0102] During parking or driving, when there is a need for power take-off, the driver presses the power take-off request button 1 in the cab. The TCU2 receives the power take-off opening signal and determines whether the power take-off judgment conditions are met based on the overall vehicle and transmission operating conditions. If they are met, the TCU2 sends a control command to the ECU 3 to open the power take-off. After the ECU 3 opens the solenoid hydraulic valve 9, the drive motor 4 rotates forward. The ball screw 5 converts the rotational motion of the motor 4 into the linear motion of the piston rod of the release hydraulic cylinder 6. The hydraulic oil in the release hydraulic cylinder 6 is squeezed to the power take-off hydraulic cylinder 10 through the solenoid hydraulic valve 9 and the hydraulic circuit, pushing the shift fork shaft 12 to drive the power take-off shift fork 13 to realize the meshing of the power take-off output gear 16 and the input gear 18. During engagement, the end of the power take-off fork shaft 12 abuts against the contact of the pressure switch 14. After receiving the open signal from the power take-off pressure switch 14, the TCU 2 sends a control command to the ECU 3 that the power take-off is open. The ECU 3 closes the solenoid hydraulic valve 9. At this time, the hydraulic circuit from the solenoid hydraulic valve 9 to the power take-off hydraulic cylinder 10 is in a pressure-holding state, and the power take-off 20 remains open to allow the pump or motor and other peripheral equipment to continue to operate.

[0103] During parking or driving, if it is necessary to terminate the power take-off (PTO), the driver presses the PTO request button 1 again. The PTO request button 1 resets, and the TCU 2 receives the PTO shutdown signal. Based on the vehicle and transmission operating conditions, it determines whether the PTO shutdown conditions are met. If met, it sends a PTO shutdown control command to the ECU 3. The ECU 3 drives the motor 4 in reverse. When the pressure value received by the pressure sensor 8 is less than the set threshold, the ECU 3 opens the solenoid hydraulic valve 9, reducing the oil pressure in the PTO hydraulic cylinder 10. When the hydraulic pressure acting on the piston of the PTO hydraulic cylinder 10 is less than the spring force of the self-returning spring 11, the shift fork shaft 12 drives the shift fork 13 to move in the opposite direction, separating the output gear 16 from the input gear 18. The end of the PTO shift fork shaft 12 does not press against the contact of the pressure switch 14. When the TCU 2 receives the shutdown signal from the PTO pressure switch 14, it sends a PTO shutdown control command to the ECU 3. The ECU 3 closes the solenoid hydraulic valve 9, and the PTO 20 terminates power take-off. The default state of the control system is PTO shutdown.

[0104] The above description is merely one embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any equivalent structural transformations made based on the description and drawings of the present invention, or direct or indirect applications in other related technical fields, are included within the scope of patent protection of the present invention.

Claims

1. A power take-off control system for an electro-hydraulic AMT, comprising a power take-off request button (1), a TCU (2), and a power take-off (20); Its features are: It also includes an electro-hydraulic clutch release mechanism (22), an electromagnetic hydraulic valve (9), and a clutch hydraulic release bearing (21); The power take-off (PTO) request button (1) is located in the cab and is connected to the TCU (2) via a hard wire; the TCU (2) is located on the electro-hydraulic AMT; the PTO (20) includes a pressure switch (14) connected to the TCU (2), and the pressure switch (14) is used to monitor the status of the PTO (20); The electro-hydraulic clutch release mechanism (22) includes an ECU (3) that communicates with the TCU (2) via CAN, a drive assembly connected to the ECU (3), and a release hydraulic cylinder (6) connected to the drive assembly. The ECU (3) controls the drive assembly to make the release hydraulic cylinder (6) move. The input end of the electromagnetic hydraulic valve (9) is connected to the hydraulic chamber of the separation hydraulic cylinder (6), and the two output ends are connected to the hydraulic chamber of the power take-off hydraulic cylinder (10) and the hydraulic chamber of the clutch hydraulic separation bearing (21), respectively. The control end is connected to the ECU (3). The electromagnetic hydraulic valve (9) is controlled by the ECU (3) to move the valve core to switch between two output ends, forming either the power take-off (PTO) working mode or the clutch working mode. In the PTO working mode, the electromagnetic hydraulic valve (9) is connected to the PTO hydraulic cylinder (10) and disconnected from the clutch hydraulic release bearing (21) to form a PTO hydraulic circuit to realize the opening and closing of the PTO (20). In the clutch working mode, the electromagnetic hydraulic valve (9) is connected to the clutch hydraulic release bearing (21) and disconnected from the PTO hydraulic cylinder (10) to form a clutch hydraulic circuit to realize the clutch disengagement and engagement.

2. The power take-off control system for an electro-hydraulic AMT according to claim 1, characterized in that: The drive components of the electro-hydraulic clutch disengagement mechanism (22) include a motor (4) and a ball screw (5); The ECU (3) is mounted on the motor (4); The screw of the ball screw (5) is connected to the output end of the motor (4), and the nut is connected to the piston rod of the separation hydraulic cylinder (6) to convert the rotational motion of the motor (4) into the linear motion of the piston rod of the separation hydraulic cylinder (6).

3. The power take-off control system for an electro-hydraulic AMT according to claim 2, characterized in that: An oil reservoir (7) is provided at one end of the piston rod on the separating hydraulic cylinder (6) for depressurizing or replenishing the hydraulic circuit connected to the separating hydraulic cylinder (6); The separating hydraulic cylinder (6) is equipped with a pressure sensor (8) that communicates with its hydraulic chamber. The pressure sensor (8) is connected to the ECU (3) and is used to monitor the oil pressure in the hydraulic chamber of the separating hydraulic cylinder (6).

4. The power take-off control system for an electro-hydraulic AMT according to claim 3, characterized in that: The control terminal of the electromagnetic hydraulic valve (9) is hardwired to the ECU (3); The pressure sensor (8) is hardwired to the ECU (3).

5. The power take-off control system for an electro-hydraulic AMT according to claim 1, characterized in that: The power take-off (20) includes a self-returning spring (11), a shift fork shaft (12), a shift fork (13), an output shaft (15), an output gear (16), a flange (17), an input gear (18), and an input shaft (19); The piston rod of the power take-off hydraulic cylinder (10) is provided with a self-returning spring (11) on one side, and the piston rod constitutes the shift fork shaft (12); The pressure switch (14) is installed at the end of the shift fork shaft (12) with a gap. When the shift fork shaft (12) moves under hydraulic pressure and abuts against the contact of the pressure switch (14), the power take-off (20) is opened. At this time, the circuit between the pressure switch (14) and the TCU (2) is connected. When the shift fork shaft (12) moves away from the contact of the pressure switch (14) under the action of the self-returning spring (11), the power take-off (20) is closed. At this time, the circuit between the pressure switch (14) and the TCU (2) is disconnected. The shift fork (13) is interference-fitted onto the shift fork shaft (12); the output gear (16) is movably fitted onto the output shaft (15), and the output gear (16) is provided with a shift fork groove, into which the shift fork (13) is inserted; the flange (17) is located at one end of the output shaft (15); The input shaft (19) is arranged parallel to the output shaft (15), and the input gear (18) is arranged on the input shaft (19) for engaging or disengaging with the output gear (16) when the shift fork (13) is activated.

6. The power take-off control system of an electro-hydraulic AMT according to claim 5, characterized in that: The pressure switch (14) is hardwired to the TCU (2).

7. A power take-off control method for an electro-hydraulic AMT, based on the power take-off control system of an electro-hydraulic AMT according to any one of claims 1-6, characterized in that, Includes the following steps: S1, press the power take-off request button (1), the circuit connected to the power take-off request button (1) and the TCU (2) is connected, and a power take-off open signal is generated; S2, TCU(2) obtains the power take-off opening signal and determines whether the power take-off condition is met based on the vehicle and transmission operating conditions; If the power take-off determination condition is met, the TCU (2) generates a control command to open the power take-off and sends it to the ECU (3). The ECU (3) controls the electromagnetic hydraulic valve (9) to open and switches the electromagnetic hydraulic valve (9) to the power take-off working mode. If the force determination condition is not met, proceed to step S6; S3, ECU (3) controls the piston rod movement of the separation hydraulic cylinder (6) through the drive assembly, thereby controlling the power take-off (20) to open; S4, TCU(2) determines whether it has received an open signal from the pressure switch (14); When the power take-off (20) is fully opened, the pressure switch (14) is opened; otherwise, the pressure switch (14) is closed, and the ECU (3) continues to control the piston rod movement of the separation hydraulic cylinder (6) through the drive assembly. S5, after TCU(2) receives the open signal of pressure switch (14), it sends a control command that the power take-off is open to ECU(3); S6, ECU(3) controls the solenoid hydraulic valve (9) to close, the solenoid hydraulic valve (9) switches to the clutch working mode, and ECU(3) controls the drive components according to the clutch control command of TCU(2); At this time, the hydraulic circuit between the electromagnetic hydraulic valve (9) and the power take-off hydraulic cylinder (10) is in a pressure-holding state, and the power take-off (20) remains open. S7, when the power take-off (20) is turned off, press the power take-off request button (1) again, the power take-off request button (1) is reset, the circuit connected to the TCU (2) is disconnected, and a power take-off turn-off signal is generated; S8, TCU(2) obtains the power take-off shutdown signal and determines whether the power take-off shutdown condition is met based on the vehicle and transmission operating conditions; If the power take-off shutdown condition is met, the TCU (2) generates a power take-off shutdown control command and sends it to the ECU (3). The ECU (3) controls the piston rod of the separation hydraulic cylinder (6) to move in the opposite direction through the drive component. If the power take-off shutdown condition is not met, proceed to step S12; S9, ECU(3) makes a judgment based on the pressure value of pressure sensor(8); When the pressure value is less than the set threshold, the ECU (3) controls the solenoid hydraulic valve (9) to open and the solenoid hydraulic valve (9) switches to the power take-off working mode; otherwise, the ECU (3) continues to control the piston rod of the separation hydraulic cylinder (6) to move in the opposite direction through the drive component. S10, TCU(2) determines whether it has received a closing signal from pressure switch(14); When the power take-off (20) is closed, the pressure switch (14) is closed; otherwise, the pressure switch (14) is opened and the ECU (3) maintains the solenoid hydraulic valve (9) in the power take-off working mode. S11, after TCU(2) receives the closing signal from pressure switch(14), it sends a control command to ECU(3) that the power take-off is closed; S12, ECU(3) controls the solenoid hydraulic valve (9) to close, the solenoid hydraulic valve (9) switches to the clutch working mode, and ECU(3) controls the drive component according to the clutch control command of TCU(2); At this time, the hydraulic oil in the power take-off hydraulic circuit has been squeezed into the separation hydraulic cylinder (6) under the action of the self-returning spring (11), and the electromagnetic hydraulic valve (9) is closed, the power take-off (20) is in the closed state, the power take-off ends, and the power take-off control of the electro-hydraulic AMT is realized.

8. The power take-off control method for an electro-hydraulic AMT according to claim 7, characterized in that: Step S3 is as follows: the ECU (3) controls the motor (4) to rotate forward, the ball screw (5) pushes the piston rod of the separation hydraulic cylinder (6) to move, and the hydraulic oil in the separation hydraulic cylinder (6) is squeezed into the hydraulic chamber of the power take-off hydraulic cylinder (10) through the electromagnetic hydraulic valve (9). Under the action of hydraulic pressure, the piston rod of the power take-off hydraulic cylinder (10), i.e. the shift fork shaft (12), moves, and the shift fork (13) on the shift fork shaft (12) drives the output gear (16) to mesh with the input gear (18), so that the power take-off (20) is opened. In step S8, if the power take-off closing condition is met, the ECU (3) controls the motor (4) to reverse, and drives the piston rod of the separation hydraulic cylinder (6) to move in the opposite direction via the ball screw (5), and the oil pressure in the separation hydraulic cylinder (6) decreases. In step S9, when the oil pressure is lower than the set threshold, the ECU (3) controls the electromagnetic hydraulic valve (9) to open. When the hydraulic pressure acting on the piston surface of the power take-off hydraulic cylinder (10) is less than the force of the self-returning spring (11), the shift fork (13) moves in the opposite direction. The shift fork (13) on the shift fork shaft (12) drives the output gear (16) to separate from the input gear (18), thereby closing the power take-off (20).

9. The power take-off control method for an electro-hydraulic AMT according to claim 8, characterized in that: In step S4, the power take-off (20) is opened specifically when the shift fork shaft (12) moves and its end abuts against the contact of the pressure switch (14), the circuit between the pressure switch (14) and the TCU (2) is connected, and a pressure switch (14) opening signal is generated. In step S10, the power take-off (20) is closed specifically when the shift fork shaft (12) moves in the opposite direction and its end separates from the contact of the pressure switch (14), the circuit between the pressure switch (14) and the TCU (2) is disconnected, and a pressure switch (14) closing signal is generated.

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