Hydrostatically driven vehicle electro-hydraulic system, control method and engineering machine

Abstract

The present application relates to the technical field of hydrostatic drive vehicle gear shifting control, and particularly relates to a hydrostatic drive vehicle electro-hydraulic system, a control method and an engineering machinery. The system comprises a variable motor, a forward rotation oil port and a reverse rotation oil port connected with a variable pump through a forward rotation oil path and a reverse rotation oil path, and the variable motor is further connected with a displacement control mechanism; a bypass valve group is connected between the forward rotation oil path and the reverse rotation oil path, and the bypass valve group comprises a bypass control mechanism for controlling the on-off between the forward rotation oil path and the reverse rotation oil path; an input end of a gearbox is connected with an output shaft of the variable motor, an output end is connected with a wheel transmission mechanism, and a synchronizer is connected with a gear shifting control mechanism; the displacement control mechanism can realize zero displacement control of the motor, and on the basis of realizing the zero displacement control of the motor, the bypass control mechanism can prevent the gear shifting control mechanism from damaging the gearbox due to heavy load sliding wear when performing gear shifting through unloading, so as to realize safe control in the gear shifting process.

Description

Technical Field

[0001] This invention relates to the field of hydrostatic drive vehicle gear shifting control technology, specifically to an electro-hydraulic system, control method, and engineering machinery for hydrostatic drive vehicles. Background Technology

[0002] Hydrostatic drives are widely used in engineering vehicles. By combining variable pumps and variable motors, stepless speed regulation can be achieved. Typically, a combination of variable pump, variable motor, and gearbox is used to achieve low-speed high traction (large transmission ratio) and high-speed driving requirements (small transmission ratio). If a fixed-ratio gearbox is used, it can only achieve relatively low-speed driving requirements to meet traction requirements, and the speed range is limited. To meet the needs of high-speed site transfer, an adjustable-ratio gearbox is usually integrated. A two-speed gearbox is usually sufficient. In the low gear, high traction is achieved for working conditions such as digging and climbing, while in the high gear, high-speed driving is achieved. The gearbox used can be a stop-shift gearbox or a driving-shift gearbox during gear shifting. The driving-shift gearbox can shift gears without stopping, which can better meet the requirements of efficient operation.

[0003] Existing technologies include power shifting systems using clutches, which require clutches for both upshifting and downshifting. These gearboxes are typically bulky and expensive, and under heavy loads, frequent shifting can lead to significant clutch slippage. Other existing technologies employ differential pressure control, but controlling the pressure difference between the motor inlet and outlet is difficult, and external loads can easily cause pressure changes, leading to control misalignment and resulting in shifting under load and significant shift shock. Therefore, there is an urgent need for a hydrostatic drive system with minimal shift shock and shift slippage. Summary of the Invention

[0004] The purpose of this invention is to provide an electro-hydraulic system, control method, and engineering machinery for hydrostatic drive vehicles. The displacement control mechanism enables zero-displacement control of the motor. Based on achieving zero-displacement control of the motor, the bypass control mechanism can prevent heavy-load slippage damage to the gearbox when the gear shifting control mechanism performs gear shifting by unloading, thereby achieving safe control of the gear shifting process.

[0005] In a first aspect, the present invention provides an electro-hydraulic system for a hydrostatically driven vehicle, comprising: The variable motor has forward and reverse oil ports connected to the first and second oil ports of the variable pump via forward and reverse oil circuits, respectively. The variable motor is also connected to a displacement control mechanism, which enables the variable motor to achieve zero displacement. A bypass valve assembly is connected between the forward and reverse oil circuits, and the bypass valve assembly includes a bypass control mechanism for controlling the connection and disconnection between the forward and reverse oil circuits. The gearbox has an input end connected to the output shaft of the variable motor and an output end connected to the wheel transmission mechanism. A transmission gear and a synchronizer are provided between the input and output ends of the gearbox. The synchronizer is connected to a gear shifting control mechanism for switching the synchronizer in conjunction with the transmission gear to adjust the gearbox gear. The vehicle controller communicates with the displacement control mechanism, bypass control mechanism, and gear shifting control mechanism.

[0006] Optionally, the displacement control mechanism includes a motor electromechanical module; the control terminal of the motor electromechanical module is connected to the whole machine controller, the motor electromechanical module is used to control the displacement of the variable motor, and the motor electromechanical module is also used to feed back the stroke position corresponding to the actual displacement of the motor to the whole machine controller. The motor electromechanical module includes a drive motor module, a mechanical transmission module, and a stroke detection module. The drive motor module is used to drive the mechanical transmission module connected to the variable displacement motor for displacement control. The stroke detection module is used to detect the stroke information of the mechanical transmission module corresponding to the motor displacement position, and to feed back the position signal of the motor displacement position to the vehicle controller.

[0007] Optionally, the displacement control mechanism includes: A variable displacement cylinder for motors, with a cylinder rod connected to a variable displacement motor control device, allows the displacement of the variable motor to be controlled by adjusting the cylinder rod stroke. A motor displacement control valve is located between the motor displacement variable cylinder and the variable motor. The control end of the motor displacement control valve is connected to the vehicle controller. By controlling the position of the valve core of the motor displacement control valve, the high-pressure side oil port of the variable motor can be controlled to supply oil to the rodless chamber of the motor displacement variable cylinder, so as to adjust the cylinder rod stroke of the motor displacement variable cylinder. An angle sensor is used to detect the tilt position of the displacement control device to detect whether the variable displacement motor has reached the zero displacement position and to feed back to the vehicle controller.

[0008] Optionally, the bypass valve assembly includes: The reversing valve has its inlet connected in parallel to the forward and reverse ports of the variable motor, and its outlet connected in parallel to the first and second ports of the variable pump via a relief valve. The reversing valve is a proportional reversing valve or an on / off reversing valve. The first check valve has its inlet side connected to the forward rotation port of the variable motor and its outlet side connected to the inlet of the directional valve. The second check valve has its inlet side connected to the reverse oil port of the variable motor and its outlet side connected to the inlet of the directional valve. The third check valve is connected to the outlet of the directional valve on the inlet side and to the second port of the variable pump on the outlet side. The fourth check valve is connected to the outlet of the directional valve on the inlet side and to the first port of the variable pump on the outlet side.

[0009] Optionally, the bypass control mechanism includes a bypass electromechanical module connected to the control terminal of the reversing valve; the bypass electromechanical module is used to control the valve core position of the reversing valve. The bypass electromechanical module includes a drive motor module, a mechanical transmission module, and a stroke detection module; The drive motor module is used to drive the mechanical transmission module to move the valve core of the reversing valve. The drive motor module is connected to the control terminal of the vehicle controller. The stroke detection module is used to detect the stroke information of the mechanical transmission module corresponding to the valve core position of the reversing valve. The stroke detection module is used to feed back the valve core position of the reversing valve to the vehicle controller. When the reversing valve is switched to the through position, the forward oil circuit and the reverse oil circuit are connected.

[0010] Optionally, the bypass control mechanism includes a solenoid valve connected to the control end of the reversing valve. The vehicle controller is communicatively connected to the solenoid valve and controls the valve core position of the reversing valve by controlling the solenoid valve. When the reversing valve is switched to the through position, the forward oil circuit and the reverse oil circuit are connected.

[0011] Optionally, the bypass valve assembly includes: The electro-proportional relief valve has its inlet connected in parallel to the forward and reverse ports of the variable motor, and its outlet connected in parallel to the first and second ports of the variable pump. The first check valve has its inlet side connected to the forward rotation port of the variable motor and its outlet side connected to the inlet of the electro-proportional relief valve. The second check valve has its inlet side connected to the reverse oil port of the variable motor and its outlet side connected to the inlet of the electro-proportional relief valve. The third check valve is connected to the oil outlet of the electro-proportional relief valve on the oil inlet side and to the second oil outlet of the variable pump on the oil outlet side. The fourth check valve is connected to the outlet of the electro-proportional relief valve on the inlet side and to the first port of the variable pump on the outlet side. The electro-proportional relief valve is communicatively connected to the vehicle controller; the relief pressure value of the electro-proportional relief valve can be controlled by controlling the current; when shifting gears is required, the electro-proportional relief valve is energized, the relief pressure value is reduced to a preset low value, and the forward and reverse oil circuits are connected; after shifting gears, the vehicle controller de-energizes the electro-proportional relief valve, and the relief pressure value is restored to a preset high value.

[0012] Optionally, the bypass valve assembly includes: The proportional directional valve has its first and second ports connected to the forward and reverse oil circuits, respectively.

[0013] Optionally, the gear shifting control mechanism includes a gear shifting electromechanical module, which includes a drive motor module, a mechanical transmission module, and a stroke detection module. The drive motor module drives the mechanical transmission module connected to the synchronizer via a shift fork. The stroke detection module detects the stroke information of the mechanical transmission module corresponding to the synchronizer position. When the stroke information of the mechanical transmission module reaches a preset stroke, the stroke detection module feeds back a gear signal to the vehicle controller.

[0014] Optionally, the gear shifting control mechanism includes: The shift control cylinder has a cylinder rod connected to a synchronizer via a shift fork; a high-speed gear position sensor and a low-speed gear position sensor are provided on the extension and retraction path of the cylinder rod. The shift control valve has its control terminal connected in communication with the vehicle controller. By controlling the position of the valve core of the shift control valve, the external high-pressure oil port can supply oil to the rod chamber or rodless chamber of the shift control cylinder to adjust the position of the cylinder rod. When the cylinder rod position reaches the position of the high-speed position sensor, the high-speed position sensor feeds back a high-speed gear signal to the vehicle controller. When the cylinder rod position reaches the position of the low-speed position sensor, the low-speed position sensor feeds back a low-speed gear signal to the vehicle controller.

[0015] Optionally, the transmission gear includes a low-speed gear and a high-speed gear; When the synchronizer engages with the low-speed gear, the gearbox is in low-speed gear to transmit power; when the synchronizer engages with the high-speed gear, the gearbox is in high-speed gear to transmit power.

[0016] Optionally, it also includes: A variable pump control valve is connected to the variable pump to control the displacement of the variable pump; A motor speed sensor is located at the output shaft of the variable motor; The transmission speed sensor is located at the output end of the transmission; The variable pump control valve, motor speed sensor, and gearbox speed sensor are all communicatively connected to the vehicle controller.

[0017] Secondly, the present invention provides a control method for an electro-hydraulic system of a hydrostatically driven vehicle, based on the aforementioned electro-hydraulic system. The control method includes: when a variable pump drives a variable motor to rotate and, through a gearbox, drives the drive wheel to rotate: If the vehicle controller receives a shift signal, the vehicle controller controls the displacement control mechanism to adjust to the zero displacement position corresponding to the variable motor. After the displacement control mechanism returns to the zero displacement position, it sends a position signal to the vehicle controller. After receiving the position signal, the vehicle controller controls the bypass control mechanism to open so that the forward and reverse oil circuits are connected. After the bypass control mechanism is opened, the vehicle controller controls the gear shifting control mechanism to disengage the synchronizer from the currently engaged transmission gear and synchronize and engage with the transmission gear corresponding to the shift signal. After the synchronizer completes synchronization and engagement, the gear shifting control mechanism feeds back the gear signal to the vehicle controller. Upon receiving the gear signal, the vehicle controller controls the displacement control mechanism to adjust to the displacement position corresponding to the current vehicle speed, and simultaneously controls the bypass control mechanism to close so that the forward and reverse oil circuits are disconnected.

[0018] Thirdly, the present invention provides an engineering machinery comprising the aforementioned hydrostatic drive vehicle electro-hydraulic system.

[0019] Compared with the prior art, the present invention has the following beneficial effects: In this invention, when the variable pump drives the variable motor to rotate and the transmission drives the drive wheel to rotate, if the vehicle controller receives a shift signal, the vehicle controller controls the displacement control mechanism to adjust to the zero displacement position corresponding to the variable motor, so that the variable motor does not output torque after the motor is controlled to zero displacement. After the displacement control mechanism returns to the zero displacement position, it feeds back a position signal to the vehicle controller. After receiving the position signal, the vehicle controller controls the bypass control mechanism to open so that the forward and reverse oil circuits are connected. The oil on the high-pressure side of the forward and reverse oil circuits will flow to the low-pressure side to complete the unloading and prevent the hydrostatic drive system from pressure buildup. After the bypass control mechanism opens, it feeds back an opening signal to the vehicle controller, and the vehicle controller... After receiving the open signal, the controller controls the gear shifting control mechanism to disengage the synchronizer from the currently engaged transmission gear and synchronize it with the transmission gear corresponding to the shift signal. Under the premise of zero motor displacement and unloading of the bypass control mechanism, the shifting process has zero torque input. The synchronizer performs speed synchronization under light load to prevent slippage under heavy load, thus achieving safe control during upshifting and downshifting. After the synchronizer completes synchronization and engagement, the gear shifting control mechanism feeds back the gear signal to the vehicle controller. After receiving the gear signal, the vehicle controller controls the displacement control mechanism to adjust to the displacement position corresponding to the current vehicle speed, and at the same time controls the bypass control mechanism to close so that the forward and reverse oil circuits are disconnected, and the system re-pressures and resumes normal driving.

[0020] The bypass valve assembly employs an electro-proportional directional valve for direct bypass, an electro-proportional relief valve for bypass, or a combination of a switching valve and a relief valve. Different pressure values ​​can be set according to vehicle speed to achieve a smooth pressure transition during gear shifts, ensuring a seamless speed transition during upshifts and downshifts and avoiding shift shocks. Furthermore, when the shift control, motor zero-discharge control, and bypass unloading of this invention all utilize electromechanical modules, real-time monitoring of stroke information is possible, unaffected by oil source pressure, and precise control is achieved. Attached Figure Description

[0021] Figure 1 Hydraulic schematic diagram of the electro-hydraulic system for a hydrostatic drive vehicle provided in an embodiment of the present invention; Figure 2 for Figure 1 A schematic diagram of the electromechanical module used in the displacement control mechanism, bypass control mechanism and gear shifting control mechanism; Figure 3 A hydraulic schematic diagram of another form of electro-hydraulic system for a hydrostatic drive vehicle provided in an embodiment of the present invention; Figure 4 Hydraulic schematic diagram of another form of electro-hydraulic system for hydrostatic drive vehicles provided in this embodiment of the invention; Figure 5 A hydraulic schematic diagram of another form of electro-hydraulic system for a hydrostatic drive vehicle provided in an embodiment of the present invention.

[0022] The diagram labels are as follows: 1. Variable displacement pump; 1.1. Variable displacement pump control valve; 2. Engine; 3. Vehicle controller; 4. Bypass valve assembly; 4.1 Bypass electromechanical module; 4.2. Directional control valve; 4.3. Relief valve; 4.4. First check valve; 4.5. Second check valve; 4.6. Third check valve; 4.7. Fourth check valve; 4.8. Electro-proportional relief valve; 5. Variable displacement motor; 5.1. Motor electromechanical module; 5.2. Angle sensor; 5.3. Motor rotation... 5.4 Speed ​​sensor; 5.5 Motor displacement control valve; 6.6 Motor displacement control cylinder; 6.7 Gearbox; 6.1 Synchronizer; 6.2 Shift electromechanical module; 6.3 Gearbox speed sensor; 6.4 Low gear gear; 6.5 High gear gear; 6.6 Shift control cylinder; 6.7 High gear position sensor; 6.8 Low gear position sensor; 8. Accelerator pedal; 9. Shift button; 10. Engine controller; 11. Shift control valve. Detailed Implementation

[0023] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are used only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more. In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0024] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0025] To make the purpose, technical solution and advantages of this invention patent clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0026] This embodiment provides a hydrostatic drive vehicle electro-hydraulic system, which includes a variable displacement motor 5, a bypass valve assembly 4, a transmission 6, and a vehicle controller 3. The forward and reverse oil ports of the variable displacement motor 5 are connected to the first and second oil ports of the variable displacement pump 1 via forward and reverse oil circuits, respectively. The variable displacement motor 5 is also connected to a displacement control mechanism (in this embodiment, a motor electromechanical module 5.1). The bypass valve assembly 4 is connected between the forward and reverse oil circuits, and the bypass valve assembly 4 includes a bypass control mechanism for controlling the connection and disconnection between the forward and reverse oil circuits of the variable displacement motor 5. The transmission 6 is equipped with a bypass electromechanical module 4.1 in this embodiment. The input end of the transmission 6 is connected to the output shaft of the variable motor 5, and the output end is connected to the drive shaft (the drive shaft connects to the drive axle and transmits power to the wheels). A synchronizer 6.1 is provided between the input and output ends of the transmission 6. The synchronizer 6.1 is connected to a gear shifting control mechanism (shifting electromechanical module 6.2 in this embodiment) for switching the gears engaged by the synchronizer 6.1 to adjust the gear position of the transmission 6. The vehicle controller 3 is communicatively connected to the displacement control mechanism, the bypass control mechanism, and the gear shifting control mechanism.

[0027] In this embodiment, when the variable pump 1 drives the variable motor 5 to rotate and the transmission 6 drives the drive wheel to rotate, if the vehicle controller 3 receives a shift signal from the shift button 9, the vehicle controller 3 controls the displacement control mechanism to adjust to the zero displacement position corresponding to the variable motor 5, so that the variable motor 5 does not output torque after the motor is controlled to zero displacement. After the displacement control mechanism returns to the zero displacement position, it feeds back a zero displacement position signal to the vehicle controller 3. After receiving the zero displacement position signal, the vehicle controller 3 controls the bypass control mechanism to open so that the forward and reverse oil circuits are connected. The oil on the high-pressure side of the forward and reverse oil circuits will flow to the low-pressure side to complete the unloading and prevent the system from being pressurized. After the bypass control mechanism is opened, it feeds back a zero displacement position signal to the vehicle controller 3. The controller 3 sends an open signal. Upon receiving the open signal, the vehicle controller 3 controls the gear shifting control mechanism to disengage the synchronizer 6.1 from the currently engaged transmission gear and synchronize it with the transmission gear corresponding to the shift signal. Under the premise of zero motor displacement and unloading of high and low pressure tests, the synchronizer 6.1 then performs gear shifting, resulting in less shift shock and less shift slip. After the synchronizer completes synchronization and engagement, the gear shifting control mechanism sends a gear signal to the vehicle controller 3. Upon receiving the gear signal, the vehicle controller 3 controls the displacement control mechanism to adjust to the displacement position corresponding to the current vehicle speed, and simultaneously controls the bypass control mechanism to close, thereby disconnecting the forward and reverse oil circuits and restoring normal driving.

[0028] This will be explained in detail using hydraulic principles. Figure 1The input shaft of variable pump 1 is directly connected to the output shaft of engine 2. Variable pump control valve 1.1 is used to control the displacement of variable pump 1. The solenoid valve control terminal of variable pump control valve 1.1 is connected to the output terminal of vehicle controller 3. Vehicle controller 3 controls the displacement of variable pump 1 by setting different control currents for the solenoid valve control terminal of variable pump control valve 1.1. The first and second oil ports of variable pump 1 are connected to the forward and reverse oil ports of variable motor 5 through forward and reverse oil circuits, respectively. A motor speed sensor 5.3 is set on the output shaft of variable motor 5 to detect the speed of variable motor 5 (corresponding to the input shaft speed of gearbox 6) and is connected to the input terminal of vehicle controller 3. The displacement control of variable motor 5 is controlled by motor electromechanical module 5.1. The displacement control is not affected by load pressure and can effectively avoid the situation where the displacement cannot return to zero or the displacement returns to zero for a long time due to low load pressure, resulting in failure to shift gears or long shift gear times. Simultaneously, the control input terminal of the motor electromechanical module 5.1 is connected to the output terminal of the vehicle controller 3. The motor electromechanical module 5.1 includes a drive motor module, a mechanical rotation module (as an example, a gear and rack module, a lead screw module, or other mechanical transmission modules with the same function can be selected), and a stroke detection module. The drive motor module is used to drive the mechanical transmission module connected to the variable displacement motor 5 for displacement control. The stroke detection module is used to detect the stroke information of the mechanical transmission module corresponding to the motor displacement position. The motor electromechanical module 5.1 feeds back the stroke information (corresponding to the motor displacement) to the vehicle controller 3, so that the vehicle controller 3 can determine the actual displacement information of the variable displacement motor 5 (including the zero displacement position of the motor) based on the feedback stroke information. This embodiment uses an electromechanical module solution that can monitor the stroke information of the mechanical transmission module corresponding to the motor displacement position in real time (the bypass electromechanical module 4.1 and the shift electromechanical module 6.2 are similar), determine the actual stroke position of the control process, and determine whether process jamming occurs, and perform fault diagnosis. This is a significant advantage of the electromechanical solution compared to the hydraulic control solution.

[0029] In this embodiment, a bypass valve assembly 4 is installed between the forward and reverse oil circuits connecting the variable pump 1 and the variable motor 5. This bypass valve assembly 4 allows for direct connection and unloading between the variable pump 1 and the variable motor 5 during gear shifting. The bypass electromechanical module 4.1 controls the opening of the directional valve 4.2. The bypass valve assembly 4 uses an electromechanical module, whose opening is unaffected by oil source pressure and can monitor whether a shift has actually occurred, preventing valve core jamming and ensuring safe gear shifting under load. The bypass electromechanical module 4.1 controls the directional valve 4.2. The bypass electromechanical module 4.1 includes a drive motor module, a mechanical transmission module, and a stroke detection module. The drive motor module drives the mechanical transmission module to move the valve core of the directional valve 4.2. The stroke detection module detects the stroke information of the mechanical transmission module corresponding to the valve core position of the directional valve 4.2. When the stroke information of the mechanical transmission module reaches the preset stroke, the stroke detection module sends an opening signal to the vehicle controller 3, and the directional valve 4.2 switches to the through position, connecting the forward and reverse oil circuits.

[0030] The inlet of the directional valve 4.2 is connected in parallel to the forward and reverse ports of the variable motor 5, and the outlet is connected in parallel to the first and second ports of the variable pump 1 via the relief valve 4.3. The control input of the bypass electromechanical module 4.1 is connected to the output of the vehicle controller 3. The bypass electromechanical module 4.1 is used to output stroke information (corresponding to the valve core displacement of the directional valve 4.2) to the vehicle controller 3. The bypass valve group 4 includes a first check valve 4.4, a second check valve 4.5, a third check valve 4.6, and a fourth check valve. 4.7 The inlet side of the first check valve 4.4 is connected to the forward rotation port of the variable motor 5, and the outlet side is connected to the inlet of the directional valve 4.2; the inlet side of the second check valve 4.5 is connected to the reverse rotation port of the variable motor 5, and the outlet side is connected to the inlet of the directional valve 4.2; the inlet side of the third check valve 4.6 is connected to the outlet of the directional valve 4.2, and the outlet side is connected to the second port of the variable pump 1; the inlet side of the fourth check valve 4.7 is connected to the outlet of the directional valve 4.2, and the outlet side is connected to the first port of the variable pump 1.

[0031] The output of the variable displacement motor 5 is connected to the input of the gearbox 6. The output shaft of the gearbox 6 is connected to the front and rear axles and wheels via a drive shaft. The gearbox 6 is equipped with a synchronizer 6.1 and a shift electromechanical module 6.2. The shift electromechanical module 6.2 is connected to the synchronizer 6.1 via a shift fork. The shift control adopts the electromechanical module, which is not affected by the pilot oil pressure and provides real-time feedback on the shift control position to achieve safe shift control. The shift electromechanical module 6.2 includes a drive motor module, a mechanical transmission module, and a stroke detection module. The drive motor module is used to drive the mechanical transmission module connected to the synchronizer 6.1 via the shift fork. The stroke detection module is used to detect the stroke information of the mechanical transmission module corresponding to the synchronizer position. When the stroke information of the mechanical transmission module reaches the preset stroke, the stroke detection module feeds back the gear signal to the vehicle controller 3. The synchronizer 6.1 switches the engagement transmission gear, and the shift is completed.

[0032] Synchronizer 6.1 can be combined with low-speed gear 6.4 or high-speed gear 6.5 to form low-gear or high-gear transmission. The input and output terminals of shift electromechanical module 6.2 are connected to the output and input terminals of vehicle controller 3, respectively, to perform shift control and feed back the actual gear information to vehicle controller 3. At the same time, a gearbox speed sensor 6.3 is installed on the output shaft of gearbox 6. The gearbox speed sensor 6.3 is connected to the input terminal of the controller to feed back the output speed of the output shaft of gearbox 6.

[0033] Meanwhile, the input terminal of the vehicle controller 3 is connected to the accelerator pedal signal 8 and the shift button signal 9. The vehicle controller receives the actual engine speed of the engine controller 10 through CAN communication. The vehicle controller 3 and the engine controller 10 achieve engine speed control through CAN communication.

[0034] Combination Figure 2 The motor electromechanical module 5.1, bypass electromechanical module 4.1, and shift electromechanical module 6.2 all include an electromechanical control module. Shift control, motor displacement control, and bypass unloading all utilize the electromechanical module, which can monitor stroke information in real time, is unaffected by oil pressure, and achieves precise control. The electromechanical control module includes a drive motor module, a mechanical transmission module, and a stroke detection module. The drive motor module drives the mechanical transmission module, and the stroke detection module determines the stroke information of the mechanical transmission module. The electromechanical control module receives control signal input from the vehicle controller 3 and outputs the actual position information after the final actual action is executed.

[0035] Combination Figure 3 In another specific embodiment, a hydrostatic drive vehicle electro-hydraulic system is provided, compared to Figure 1The difference between the electro-hydraulic systems of the hydrostatic drive vehicle and the variable displacement motor 5 is that the displacement of the variable displacement motor 5 is controlled by the motor displacement control valve 5.4 and the motor displacement variable cylinder 5.5. The cylinder rod of the motor displacement variable cylinder 5.5 is connected to the displacement control device of the variable displacement motor 5 (e.g., a variable displacement control swashplate or swashplate motor). By adjusting the stroke of the cylinder rod of the motor displacement variable cylinder 5.5, the displacement of the variable displacement motor can be controlled. The motor displacement control valve 5.4 is located between the motor displacement variable cylinder 5.5 and the variable displacement motor 5. The control end of the motor displacement control valve 5.4... Connected to the vehicle controller 3, the valve core position of the motor displacement control valve 5.4 can be controlled to supply oil to the rodless chamber of the motor displacement variable cylinder 5.5 via the high-pressure side oil port of the variable motor 5, thereby adjusting the rod stroke of the motor displacement variable cylinder 5.5. Simultaneously, an angle sensor or zero-position sensor 5.2 is installed at the displacement change point of the variable motor 5. The angle sensor or zero-position sensor 5.2 is used to detect the tilt angle or tilt position of the variable motor to determine whether the variable motor has reached the zero displacement position, and is connected to the input terminal of the vehicle controller 3. When the angle sensor or zero-position sensor 5.2 detects that the variable motor 5 has reached the zero displacement position, it feeds back the zero displacement position signal to the vehicle controller 3.

[0036] The solenoid valve is connected to the electronic control input terminal of the reversing valve 4.2 of the bypass valve group 4. The solenoid valve is connected to the output terminal of the vehicle controller 3 to control the opening and closing of the reversing valve 4.2.

[0037] The transmission 6 is equipped with a synchronizer 6.1, which is connected to the shift control cylinder 6.6 via a shift fork. A high-speed position sensor 6.7 and a low-speed position sensor 6.8 are located on the extension path of the cylinder rod of the shift control cylinder 6.6. The shift control valve 11 controls the synchronizer 6.1 to switch the engagement gears by controlling the shift control cylinder 6.6. The control terminal of the shift control valve 11 is communicatively connected to the vehicle controller 3. By controlling the valve position of the shift control valve 11, the external high-pressure oil port can be controlled to supply oil to the rod chamber or rodless chamber of the shift control cylinder 6.6 to adjust the position of the cylinder rod. When the cylinder rod reaches the position of the high-speed position sensor 6.7, the high-speed position sensor 6.7 feeds back a high-speed gear signal to the vehicle controller 3; when the cylinder rod reaches the position of the low-speed position sensor 6.8, the low-speed position sensor 6.8 feeds back a low-speed gear signal to the vehicle controller. Meanwhile, a gearbox speed sensor 6.3 is installed on the output shaft of gearbox 6. The gearbox speed sensor 6.3 is connected to the input terminal of the controller to provide feedback on the output shaft speed of gearbox 6.

[0038] Combination Figure 4 In another specific embodiment, a hydrostatic drive vehicle electro-hydraulic system is provided, compared to Figure 3The difference between the electro-hydraulic system of the hydrostatic drive vehicle is that the bypass valve group 4 uses a combination of check valves (first check valve 4.4, second check valve 4.5, third check valve 4.6 and fourth check valve 4.7) and electro-proportional relief valve 4.8 to realize the connection and disconnection between the forward and reverse oil circuits. The inlet of the electro-proportional relief valve 4.8 is connected in parallel to the forward and reverse ports of the variable motor 5, and its outlet is connected in parallel to the first and second ports of the variable pump 1; the inlet of the first check valve 4.4 is connected to the forward port of the variable motor 5, and its outlet is connected to the inlet of the electro-proportional relief valve 4.8; the inlet of the second check valve 4.5 is connected to the reverse port of the variable motor 5, and its outlet is connected to the inlet of the electro-proportional relief valve 4.8; the inlet of the third check valve 4.6 is connected to the outlet of the electro-proportional relief valve 4.8, and its outlet is connected to the second port of the variable pump 1; the inlet of the fourth check valve 4.7 is connected to the outlet of the electro-proportional relief valve 4.8, and its outlet is connected to the first port of the variable pump 1. The control terminal of the electro-proportional relief valve 4.8 is communicatively connected to the vehicle controller 3. The relief pressure value of the electro-proportional relief valve 4.8 can be controlled by controlling the current. When shifting gears, the solenoid valve of the electro-proportional relief valve 4.8 is energized, reducing the relief pressure value to a preset low value, and connecting the forward and reverse oil circuits. After shifting gears, the solenoid valve of the electro-proportional relief valve 4.8 is de-energized, and the relief pressure value returns to a preset high value. The electro-proportional relief valve 4.8 can achieve high and low pressure control, quickly build up pressure after shifting gears, achieve smooth shifting, and avoid shifting shock.

[0039] Combination Figure 5 In another specific embodiment, a hydrostatic drive vehicle electro-hydraulic system is provided, compared to Figure 3 The difference between the electro-hydraulic system of the hydrostatic drive vehicle and the bypass module 4 is that the bypass module 4 uses a proportional directional valve to directly realize the connection and disconnection between the forward and reverse oil circuits. The first and second oil ports of the proportional directional valve are connected to the forward and reverse oil circuits, respectively; the control terminal of the proportional directional valve is communicatively connected to the vehicle controller 3; by controlling the control current of the proportional directional valve, the valve core position of the proportional directional valve can be controlled, and when the proportional directional valve is switched to the through position, the forward and reverse oil circuits are connected.

[0040] Please provide specific details regarding the working methods, such as... Figure 1 and Figure 2 The operating method of the electro-hydraulic system of the hydrostatic drive vehicle shown includes: The accelerator pedal 8 corresponds to the requested engine speed. The pedal signal from the accelerator pedal 8 is parsed by the vehicle controller 3 and sent to the engine controller 10 via the CAN bus. The engine controller 10 controls the engine 2 to set the requested speed and feeds back the actual speed to the vehicle controller 3 via the CAN bus. The vehicle controller 3 outputs a corresponding control current to the variable control valve 1.1 of the variable pump 1 based on the actual speed feedback to achieve the corresponding displacement control of the variable pump 1. Simultaneously, the vehicle controller 3 controls the motor electromechanical module 5.1 used to control the motor displacement based on the vehicle speed. By controlling the stroke of the motor electromechanical module 5.1, the corresponding motor displacement control can be achieved. The motor speed sensor 5.3 located on the output shaft of the variable motor 5 collects the motor speed, and this speed value is also input to the transmission 6. Shaft speed; the input shaft of gearbox 6 corresponds to the low-speed gear 6.4 or the high-speed gear 6.5 respectively. When synchronizer 6.1 is engaged with low-speed gear 6.4, it is driving in low gear; when synchronizer 6.1 is engaged with high-speed gear 6.5, it is driving in high gear. The output shaft of gearbox 6 is equipped with a gearbox speed sensor 6.3 to test the output shaft speed in real time. The ratio between the output shaft speed of gearbox 6 (measured in real time by gearbox speed sensor 6.3) and the input shaft speed (measured in real time by motor speed sensor 5.3) is determined according to the gear. Therefore, before shifting, it is necessary to calculate the shift engagement speed difference. Shifting can only be performed after the output shaft and input shaft meet the shift engagement speed difference to protect synchronizer 6.1. The output shaft of gearbox 6 transmits power to the wheels through the drive shaft, drive axle, etc., to enable the vehicle to move.

[0041] When the shifting conditions are met during driving (meaning the shifting speed difference is met and the current operating conditions allow for shifting) and the shift button 9 is triggered, taking forward upshifting as an example, downshifting works similarly. The vehicle controller 3 controls the motor electromechanical module 5.1, the bypass electromechanical module 4.1, and the shift electromechanical module 6.2. The vehicle controller 3 first controls the motor electromechanical module 5.1 to make the displacement of the variable motor 5 zero. The motor electromechanical module 5.1 feeds back the position information of the variable motor 5 returning to the zero displacement position to the vehicle controller 3. After receiving the position information of the variable motor 5 returning to the zero displacement position, the vehicle controller 3 controls the bypass electromechanical module 4.1 to open. After the bypass electromechanical module 4.1 opens, it feeds back an opening signal to the vehicle controller, connecting the forward and reverse oil circuits. The high-pressure hydraulic oil in the forward and reverse oil circuits passes through the first check valve 4.4, then through the reversing valve 4.2 and the relief valve 4.3, and finally through the third check valve 4.6. To prevent system pressure buildup, the vehicle controller, upon receiving the opening signal, controls the shift electromechanical module 6.2. Once the shifting conditions are met (meeting the shifting engagement speed difference and allowing shifting under current operating conditions), the synchronizer 6.1 disengages from the low-speed gear 6.4 and continues to push it to synchronize and engage with the high-speed gear 6.5. This entire process is a continuous control process. The shift electromechanical module 6.2 feeds back the position information (actual gear position) to the vehicle controller 3 to confirm the upshift action. Then, the vehicle controller 3 controls the motor electromechanical module 5.1 to return the motor displacement to the set displacement corresponding to the vehicle speed. Simultaneously, it controls the bypass electromechanical module 4.1 to decouple the high and low voltage sides, establishing pressure for driving. The vehicle controller 3 performs corresponding stroke control according to the control logic. The stroke information represents different physical information depending on the control carrier, and the actual stroke information is fed back to the vehicle controller for monitoring the current state.

[0042] Please provide specific details regarding the working methods, such as... Figure 3 The operating method of the electro-hydraulic system of the hydrostatic drive vehicle shown includes: When performing a forward upshift operation, the vehicle controller controls the motor displacement control valve 5.4, bypass valve group 4, and shift control valve 11. Specifically, the vehicle controller 3 controls the current of the motor displacement control valve 5.4 to control the motor displacement to zero. The angle sensor (or zero-position sensor) 5.2 provides feedback on whether the actual displacement of the variable motor 5 is zero. At the same time, the vehicle controller 3 directly controls the reversing valve 4.2 of the bypass valve group 4 to open. The high-pressure oil on the high-pressure side of the forward and reverse oil circuits directly enters the low-pressure side after passing through the first check valve 4.4, reversing valve 4.2, overflow valve 4.3, and third check valve 4.6. When the upshifting conditions are met... Subsequently, the vehicle controller 3 energizes the shift control valve 11, causing it to activate in the left position. Control oil enters the rodless chamber of the shift control cylinder 66. The cylinder rod of the shift control cylinder 66 pushes the shift fork to move. The shift fork drives the synchronizer 61 to disengage from the low-speed gear 64 and engage with the high-speed gear 65. The high-speed position sensor 67 feeds back the high-speed position signal to the vehicle controller 3 for actual gear position feedback. After the shift is completed, the vehicle controller 3 controls the bypass valve group 4 to close, preventing direct connection between the forward and reverse oil circuits. At the same time, it controls the motor displacement control valve 5.4 to control the displacement of the variable motor 5 from zero to the corresponding displacement for driving.

[0043] Please provide specific details regarding the working methods, such as... Figure 4 The working method of the electro-hydraulic system of the hydrostatic drive vehicle shown includes: During the gear shifting process, in the control process of the bypass valve group 4, an electro-proportional relief valve 4.8 is used. The electro-proportional relief valve 4.8 is inversely proportionally controlled. Under normal conditions, the electro-proportional relief valve 4.8 is not energized. A higher relief pressure is set for the electro-proportional relief valve 4.8 to meet the pressure requirements of heavy-load conditions. During the gear shifting process, the electro-proportional relief valve 4.8 can be set with different relief pressure values ​​according to the actual speed of the vehicle. After the new gear is switched, the variable motor 5 is driven based on the set pressure, making the acceleration and deceleration of driving more continuous and the response faster, avoiding slow acceleration after gear shifting or acceleration after deceleration. After the gear shift is completed, the electro-proportional relief valve 4.8 is de-energized.

[0044] Please provide specific details regarding the working methods, such as... Figure 5 The working method of the electro-hydraulic system of the hydrostatic drive vehicle shown includes: during the gear shifting process, the bypass valve group 4, including the proportional directional valve, performs bypass control. During the gear shifting process, the proportional directional valve is opened to achieve high and low pressure side connection. At the same time, the vehicle controller 3 determines the opening size of the proportional directional valve according to the vehicle speed, etc., to achieve control of the pressure difference between the high and low pressure points during the gear shifting process. After the gear shifting is completed, the electro-proportional directional valve is de-energized, enabling the system to build up pressure for drive.

[0045] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A hydrostatic drive vehicle electro-hydraulic system, characterized in that, include: The variable motor has forward and reverse oil ports connected to the first and second oil ports of the variable pump via forward and reverse oil circuits, respectively. The variable motor is also connected to a displacement control mechanism, which enables the variable motor to achieve zero displacement. A bypass valve assembly is connected between the forward and reverse oil circuits, and the bypass valve assembly includes a bypass control mechanism for controlling the connection and disconnection between the forward and reverse oil circuits. The gearbox has an input end connected to the output shaft of the variable motor and an output end connected to the wheel transmission mechanism. A transmission gear and a synchronizer are provided between the input and output ends of the gearbox. The synchronizer is connected to a gear shifting control mechanism for switching the transmission gear engaged with the synchronizer to adjust the gearbox gear position. The vehicle controller communicates with the displacement control mechanism, bypass control mechanism, and gear shifting control mechanism. The displacement control mechanism includes a motor electromechanical module; The motor electromechanical module control terminal is connected to the whole machine controller. The motor electromechanical module is used to control the displacement of the variable motor. The motor electromechanical module is also used to feed back the control stroke position corresponding to the actual displacement of the motor to the whole machine controller. The motor electromechanical module includes a drive motor module, a mechanical transmission module, and a stroke detection module. The drive motor module is used to drive the mechanical transmission module connected to the variable displacement motor for displacement control. The stroke detection module is used to detect the stroke information of the mechanical transmission module corresponding to the motor displacement position, and to feed back the position signal of the motor displacement position to the vehicle controller; The displacement control mechanism includes: A variable displacement cylinder for motors, with a cylinder rod connected to a variable displacement motor control device, allows the displacement of the variable motor to be controlled by adjusting the cylinder rod stroke. A motor displacement control valve is located between the motor displacement variable cylinder and the variable motor. The control end of the motor displacement control valve is connected to the vehicle controller. By controlling the position of the valve core of the motor displacement control valve, the high-pressure side oil port of the variable motor can be controlled to supply oil to the rodless chamber of the motor displacement variable cylinder, so as to adjust the cylinder rod stroke of the motor displacement variable cylinder. An angle sensor is used to detect the tilt position of the displacement control device to detect whether the variable displacement motor has reached the zero displacement position and to feed back to the vehicle controller.

2. The electro-hydraulic system for a hydrostatically driven vehicle according to claim 1, characterized in that, The bypass valve assembly includes: The reversing valve has its inlet connected in parallel to the forward and reverse ports of the variable motor, and its outlet connected in parallel to the first and second ports of the variable pump via a relief valve. The reversing valve is a proportional reversing valve or an on / off reversing valve. The first check valve has its inlet side connected to the forward rotation port of the variable motor and its outlet side connected to the inlet of the directional valve. The second check valve has its inlet side connected to the reverse oil port of the variable motor and its outlet side connected to the inlet of the directional valve. The third check valve is connected to the outlet of the directional valve on the inlet side and to the second port of the variable pump on the outlet side. The fourth check valve is connected to the outlet of the directional valve on the inlet side and to the first port of the variable pump on the outlet side.

3. The electro-hydraulic system for a hydrostatically driven vehicle according to claim 2, characterized in that, The bypass control mechanism includes a bypass electromechanical module connected to the control terminal of the reversing valve; the bypass electromechanical module is used to control the valve core position of the reversing valve. The bypass electromechanical module includes a drive motor module, a mechanical transmission module, and a stroke detection module; The drive motor module is used to drive the mechanical transmission module to move the valve core of the reversing valve. The drive motor module is connected to the control terminal of the vehicle controller. The stroke detection module is used to detect the stroke information of the mechanical transmission module corresponding to the valve core position of the reversing valve. The stroke detection module is used to feed back the valve core position of the reversing valve to the vehicle controller. When the reversing valve is switched to the through position, the forward oil circuit and the reverse oil circuit are connected.

4. The electro-hydraulic system for a hydrostatically driven vehicle according to claim 2, characterized in that, The bypass control mechanism includes a solenoid valve connected to the control end of the reversing valve. The vehicle controller is communicatively connected to the solenoid valve and controls the valve core position of the reversing valve by controlling the solenoid valve. When the reversing valve is switched to the through position, the forward oil circuit and the reverse oil circuit are connected.

5. The electro-hydraulic system for a hydrostatically driven vehicle according to claim 1, characterized in that, The bypass valve assembly includes: The electro-proportional relief valve has its inlet connected in parallel to the forward and reverse ports of the variable motor, and its outlet connected in parallel to the first and second ports of the variable pump. The first check valve has its inlet side connected to the forward rotation port of the variable motor and its outlet side connected to the inlet of the electro-proportional relief valve. The second check valve has its inlet side connected to the reverse oil port of the variable motor and its outlet side connected to the inlet of the electro-proportional relief valve. The third check valve is connected to the oil outlet of the electro-proportional relief valve on the oil inlet side and to the second oil outlet of the variable pump on the oil outlet side. The fourth check valve is connected to the outlet of the electro-proportional relief valve on the inlet side and to the first port of the variable pump on the outlet side. The electro-proportional relief valve is communicatively connected to the vehicle controller; the relief pressure value of the electro-proportional relief valve can be controlled by controlling the current; when shifting gears is required, the electro-proportional relief valve is energized, the relief pressure value is reduced to a preset low value, and the forward and reverse oil circuits are connected; after shifting gears, the vehicle controller de-energizes the electro-proportional relief valve, and the relief pressure value is restored to a preset high value.

6. The electro-hydraulic system for a hydrostatically driven vehicle according to claim 1, characterized in that, The bypass valve assembly includes: The proportional directional valve has its first and second ports connected to the forward and reverse oil circuits, respectively.

7. The electro-hydraulic system for a hydrostatically driven vehicle according to claim 1, characterized in that, The gear shifting control mechanism includes a gear shifting electromechanical module, which includes a drive motor module, a mechanical transmission module, and a stroke detection module. The drive motor module drives the mechanical transmission module, which is connected to the synchronizer via a shift fork. The stroke detection module detects the stroke information of the mechanical transmission module corresponding to the synchronizer position. When the stroke information of the mechanical transmission module reaches a preset stroke, the stroke detection module feeds back a gear signal to the vehicle controller.

8. The electro-hydraulic system for a hydrostatically driven vehicle according to claim 1, characterized in that, The gear shifting control mechanism includes: The shift control cylinder has a cylinder rod connected to a synchronizer via a shift fork; a high-speed gear position sensor and a low-speed gear position sensor are provided on the extension and retraction path of the cylinder rod. The shift control valve has its control terminal connected in communication with the vehicle controller. By controlling the position of the valve core of the shift control valve, the external high-pressure oil port can supply oil to the rod chamber or rodless chamber of the shift control cylinder to adjust the position of the cylinder rod. When the cylinder rod position reaches the position of the high-speed position sensor, the high-speed position sensor feeds back a high-speed gear signal to the vehicle controller. When the cylinder rod position reaches the position of the low-speed position sensor, the low-speed position sensor feeds back a low-speed gear signal to the vehicle controller.

9. The electro-hydraulic system for a hydrostatically driven vehicle according to claim 1, characterized in that, The transmission gears include low-speed gears and high-speed gears; When the synchronizer engages with the low-speed gear, the gearbox is in low-speed gear to transmit power; when the synchronizer engages with the high-speed gear, the gearbox is in high-speed gear to transmit power.

10. The electro-hydraulic system for a hydrostatically driven vehicle according to claim 1, characterized in that, Also includes: A variable pump control valve is connected to the variable pump to control the displacement of the variable pump; A motor speed sensor is located at the output shaft of the variable motor; The transmission speed sensor is located at the output end of the transmission; The variable pump control valve, motor speed sensor, and gearbox speed sensor are all communicatively connected to the vehicle controller.

11. A control method for an electro-hydraulic system of a hydrostatically driven vehicle, characterized in that, Based on the electro-hydraulic system for a hydrostatic drive vehicle according to any one of claims 1-10, the control method includes: when the variable pump drives the variable motor to rotate and drives the drive wheel to rotate through the gearbox: If the vehicle controller receives a shift signal, the vehicle controller controls the displacement control mechanism to adjust to the zero displacement position corresponding to the variable motor. After the displacement control mechanism returns to the zero displacement position, it sends a position signal to the vehicle controller. After receiving the position signal, the vehicle controller controls the bypass control mechanism to open so that the forward and reverse oil circuits are connected. After the bypass control mechanism is opened, the vehicle controller controls the gear shifting control mechanism to disengage the synchronizer from the currently engaged transmission gear and synchronize and engage with the transmission gear corresponding to the shift signal. After the synchronizer completes synchronization and engagement, the gear shifting control mechanism feeds back the gear signal to the vehicle controller. Upon receiving the gear signal, the vehicle controller controls the displacement control mechanism to adjust to the displacement position corresponding to the current vehicle speed, and simultaneously controls the bypass control mechanism to close so that the forward and reverse oil circuits are disconnected.

12. An engineering machinery, characterized in that, Includes the electro-hydraulic system for hydrostatic drive vehicles as described in any one of claims 1-10.

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