A vehicle hydraulic four-wheel drive system

Abstract

This invention relates to the field of hydraulic drive technology, specifically to a vehicle hydraulic four-wheel drive system, including a travel pump, a travel motor, a rear drive motor, a front drive control valve group, and a rear drive control valve group. The travel pump is connected to the rear drive motor via the rear drive control valve group, and the travel pump is also connected to the travel motor via the front drive control valve group. The rear drive control valve group includes rear drive control valve group I and rear drive control valve group II, each consisting of a check valve and a speed control valve connected in parallel. Rear drive control valve group I and rear drive control valve group II are respectively installed at two oil ports of the rear drive motor. The front drive control valve group is installed between the travel pump and the travel motor, used to ensure the oil circuit between the travel pump and the travel motor is open during normal vehicle operation, and to limit the flow rate into the travel motor when the load on the front wheels decreases. This invention can limit the input or output flow rate of the corresponding motor when the wheel load decreases, preventing slippage.

Description

Technical Field

[0001] This invention relates to the field of hydraulic drive technology, and more specifically to a vehicle hydraulic four-wheel drive system. Background Technology

[0002] With the rapid development of agricultural machinery towards larger scale and greater intelligence, hydraulic four-wheel drive systems have become an indispensable core component of intelligent agricultural equipment. Hydraulic four-wheel drive systems can significantly improve a vehicle's passability and traction in complex field conditions. However, existing hydraulic four-wheel drive systems generally suffer from the following technical defects: when the loads on the four wheels of a vehicle are different, the system cannot effectively limit the flow of hydraulic fluid to the motor of the wheel with the smaller load. This causes the wheel with the smaller load (such as the wheel stuck in a shallow pit or in soft soil) to rotate too quickly due to low resistance during field operations. This results in a large amount of hydraulic oil flowing to the motor of that wheel, causing insufficient driving force for the other, heavier drive wheels. Consequently, the vehicle's walking system struggles to adapt to complex and changing field conditions, leading to slippage, getting stuck, and other problems, severely impacting operational efficiency and the stability of automatic driving control.

[0003] Most existing anti-slip solutions are complex in structure, expensive, and have complicated control logic, making them unsuitable for large-scale application in agricultural machinery. Summary of the Invention

[0004] To address the above problems, this invention proposes a vehicle hydraulic four-wheel drive system, the specific technical solution of which is as follows: A vehicle hydraulic four-wheel drive system includes a travel pump, a travel motor, a rear drive motor, a front drive control valve group, and a rear drive control valve group. The travel pump is connected to the rear drive motor via the rear drive control valve group, and the travel pump is also connected to the travel motor via the front drive control valve group. The rear drive control valve group includes rear drive control valve group I and rear drive control valve group II, each consisting of a check valve and a speed control valve connected in parallel. Rear drive control valve group I and rear drive control valve group II are respectively installed at two oil ports of the rear drive motor. The front drive control valve group is installed between the travel pump and the travel motor, used to connect the oil circuit between the travel pump and the travel motor during normal vehicle operation, and to limit the flow rate into the travel motor when the load on the front wheels of the vehicle decreases.

[0005] In one embodiment of the present invention, a front drive control valve group is installed between the forward oil inlet of the travel pump and the travel motor. The front drive control valve group includes a reversing valve, a one-way speed control valve group I, and a one-way speed control valve group II. Both one-way speed control valve group I and one-way speed control valve group II are composed of a one-way valve and a speed control valve connected in parallel. One-way speed control valve group I and one-way speed control valve group II are connected in series and then connected in parallel with the reversing valve. The reversing valve is normally in the conducting state so that the forward oil inlet of the travel pump and the travel motor are connected through the reversing valve. When the load on the front wheel corresponding to the travel motor decreases, the reversing valve switches to the closed state, so that the forward oil inlet of the travel pump and the travel motor are connected through the one-way speed control valve group I to limit the flow rate through the travel motor. The forward return oil inlet of the travel pump and the travel motor are directly connected through an oil circuit.

[0006] In another embodiment of the present invention, the front drive control valve group includes a flow limiting unit I and a flow limiting unit II. The flow limiting unit I is installed between the forward oil inlet of the travel pump and the travel motor. The flow limiting unit I includes a reversing valve and a one-way speed regulating valve group III. The reversing valve and the one-way speed regulating valve group III are connected in parallel. The one-way speed regulating valve group III is composed of a one-way valve and a speed regulating valve connected in parallel. The flow limiting unit II is installed between the reverse oil inlet of the travel pump and the travel motor. The flow limiting unit II includes a reversing valve and a one-way speed regulating valve group IV. The reversing valve and the one-way speed regulating valve group IV are connected in parallel. The one-way speed regulating valve group IV is composed of a one-way valve and a speed regulating valve connected in parallel. The reversing valve is normally in the conducting state. When the load on the front wheel corresponding to the travel motor decreases, the reversing valve on the corresponding oil inlet path switches to the closed state, so that the travel pump and the travel motor are connected through the one-way speed regulating valve group on the corresponding oil inlet path, thereby limiting the flow through the travel motor.

[0007] Furthermore, the maximum flow rate set for each speed control valve in the front drive control valve group and the rear drive control valve group is greater than the flow rate required by the corresponding motor when the vehicle is traveling at its highest speed. When the load on the front or rear wheels of the vehicle decreases and the actual flow rate provided by the travel pump is greater than the maximum flow rate set for the corresponding speed control valve, the corresponding speed control valve supplies oil to the motor corresponding to the wheel with reduced load according to its maximum flow rate set, and the remaining flow rate provided by the travel pump is supplied to the motor of the other drive axle.

[0008] The beneficial effects of this invention are as follows: 1. By arranging a control valve group consisting of a check valve and a speed regulating valve in the hydraulic circuit, the input or output flow of the wheel motor can be automatically and effectively limited when the wheel load decreases, thereby limiting its speed, preventing slippage, and distributing excess flow to other drive wheels, ensuring the vehicle's driving force and passability on complex field roads. Furthermore, by using standard hydraulic valve components, there is no need for a complex electronic control unit, resulting in high system reliability and lower manufacturing and maintenance costs. Attached Figure Description

[0009] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0010] Figure 1 This is the hydraulic schematic diagram from Example 1; Figure 2 This is the hydraulic schematic diagram in Example 2.

[0011] In the diagram: 1. Travel pump; 2. Rear drive control valve group I; 3. Rear drive control valve group II; 4. Rear drive motor; 5. Travel motor; 6. Flow limiting unit I; 7. Flow limiting unit II; 8. One-way speed control valve group I; 9. One-way speed control valve group II. Detailed Implementation

[0012] Example 1:

[0013] like Figure 1 As shown, the present invention provides a vehicle hydraulic four-wheel drive system, including a travel pump 1, a travel motor 5, a rear drive motor 4, a front drive control valve group and a rear drive control valve group. The travel pump 1 is connected to the rear drive motor 4 through the rear drive control valve group, and the travel pump 1 is connected to the travel motor 5 through the front drive control valve group.

[0014] The rear drive control valve group includes rear drive control valve group I2 and rear drive control valve group II3. Both rear drive control valve group I2 and rear drive control valve group II3 are composed of a check valve and a speed control valve connected in parallel. Rear drive control valve group I2 is installed between port A1 of the travel pump 1 and port A1 (forward oil inlet) of the rear drive motor 4, and rear drive control valve group II3 is installed between port B1 of the travel pump 1 and port B1 (forward oil return) of the rear drive motor 4.

[0015] The front drive control valve assembly is installed between port A1 of the travel pump 1 and port A1 (forward oil inlet) of the travel motor 5. The front drive control valve assembly includes a directional control valve, a one-way speed control valve assembly I8, and a one-way speed control valve assembly II9. Both one-way speed control valve assemblies I8 and II9 are composed of a check valve and a speed control valve connected in parallel. The same valves in one-way speed control valve assemblies I8 and II9 have opposite directions. One-way speed control valve assemblies I8 and II9 are connected in series and then in parallel with the directional control valve. The directional control valve is... Under normal conditions, the system is in a conducting state so that the forward oil inlet of the travel pump 1 and the travel motor 5 are connected via a reversing valve. When the load on the front wheel corresponding to the travel motor 5 decreases, the reversing valve switches to the closed state, so that the forward oil inlet of the travel pump 1 and the travel motor 5 are connected via a one-way speed control valve group I8 and a one-way speed control valve group II9 to limit the flow rate through the travel motor 5. The B1 port of the travel pump 1 and the B1 port (forward return oil port) of the travel motor 5 are directly connected via an oil circuit.

[0016] Furthermore, the maximum flow rate set for each speed control valve in both the front-drive and rear-drive control valve assemblies is greater than the flow rate required by the corresponding motor when the vehicle is traveling at its maximum speed. When the load on the front or rear wheels of the vehicle decreases and the actual flow rate provided by the travel pump 1 exceeds the maximum flow rate set for the corresponding speed control valve, the corresponding speed control valve supplies oil to the motor corresponding to the wheel with the reduced load according to its maximum flow rate set. The remaining flow rate provided by the travel pump 1 is then supplied to the motor of the other drive axle. In addition, each speed control valve is flow rate adjustable.

[0017] Under forward operating conditions, the travel pump 1 outputs pressurized oil from port A1. During normal driving, one path of the pressurized oil passes through the directional valve in the front drive control valve group (which is in the open state) directly to port A1 of the travel motor 5, driving the front wheels; the other path passes through the speed control valve in the rear drive control valve group I2 to port A1 of the rear drive motor 4, driving the rear wheels. The return oil from port B1 of the rear drive motor 4 flows back to port B1 of the travel pump 1 via the check valve in the rear drive control valve group II3, achieving four-wheel drive.

[0018] When the load on the front wheel (left or right) suddenly decreases (e.g., entering a soft area), the reversing valve is switched in control, cutting off its internal passage. At this time, the oil at port A1 of the travel pump 1 can only enter port A1 of the travel motor 5 through the check valve of the one-way speed control valve group I8 and the speed control valve of the one-way speed control valve group II9. Due to the limiting effect of the speed control valve, the flow rate entering the travel motor 5 is limited to the set value, and the front wheel speed is effectively limited to prevent slippage. The remaining flow rate of the travel pump 1 is supplied to the rear drive motor 4 to ensure the driving force of the rear wheels.

[0019] When the load on the rear wheel (left or right) decreases, the speed control valve in the rear drive control valve group I2 automatically limits the flow into the rear drive motor 4, thereby limiting the rear wheel speed and preferentially distributing the flow to the travel motor 5 to ensure the driving force of the front wheels.

[0020] In reverse operation, the forward oil inlet becomes the reverse return oil inlet, and the B1 port of the travel pump 1 outputs pressurized oil. The pressurized oil directly enters the B1 port of the travel motor 5, and simultaneously enters the B1 port of the rear drive motor 4 through the speed control valve in the rear drive control valve group II 3, driving the vehicle to reverse. The return oil from the A1 port of the travel motor 5 flows back to the A1 port of the travel pump 1 through the reversing valve in the front drive control valve group which is in the conducting state; the return oil from the A1 port of the rear drive motor 4 flows back to the A1 port of the travel pump 1 through the check valve in the rear drive control valve group I 2.

[0021] When the load on the front wheels decreases, the reversing valve closes. The return oil path to port A1 of the travel motor 5 is cut off, and the oil can only flow back to port A1 of the travel pump 1 via the check valve of the one-way speed control valve group II9 and the speed control valve of the one-way speed control valve group I8. The speed control valve of the one-way speed control valve group I8 restricts the return oil flow. Since the inlet and outlet flow of the motor is balanced, it is equivalent to restricting the amount of oil supplied to the travel motor 5, thereby limiting the front wheel speed and preventing slippage. The rear wheel anti-slip principle is the same as in the forward working condition, which is achieved by the flow restriction of the speed control valve in the rear drive control valve group II3.

[0022] Example 2:

[0023] like Figure 2 As shown, the present invention provides a vehicle hydraulic four-wheel drive system, including a travel pump 1, a travel motor 5, a rear drive motor 4, a front drive control valve group and a rear drive control valve group. The travel pump 1 is connected to the rear drive motor 4 through the rear drive control valve group, and the travel pump 1 is connected to the travel motor 5 through the front drive control valve group.

[0024] The rear drive control valve group includes rear drive control valve group I2 and rear drive control valve group II3. Both rear drive control valve group I2 and rear drive control valve group II3 are composed of a check valve and a speed control valve connected in parallel. Rear drive control valve group I2 is installed between port A1 of the travel pump 1 and port A1 (forward oil inlet) of the rear drive motor 4, and rear drive control valve group II3 is installed between port B1 of the travel pump 1 and port B1 (forward oil return) of the rear drive motor 4.

[0025] The front drive control valve group includes a flow limiting unit I6 and a flow limiting unit II7. Flow limiting unit I6 is installed between the forward oil inlet of the travel pump 1 and the travel motor 5. Flow limiting unit I6 includes a reversing valve and a one-way speed control valve group III. The reversing valve and the one-way speed control valve group III are connected in parallel. The one-way speed control valve group III is composed of a one-way valve and a speed control valve connected in parallel. Flow limiting unit II7 is installed between the backward oil inlet of the travel pump 1 and the travel motor 5. Flow limiting unit II7 includes a reversing valve and a one-way speed control valve group IV. The reversing valve and the one-way speed control valve group IV are connected in parallel. The one-way speed control valve group IV is composed of a one-way valve and a speed control valve connected in parallel. Under normal conditions, both reversing valves are in the open state. When the load on the front wheel corresponding to the travel motor decreases, the reversing valve on the corresponding oil inlet line switches to the closed state, while the reversing valve on the corresponding oil return line remains open, so that the travel pump 1 and the travel motor 5 are connected through the one-way speed control valve group on the corresponding oil inlet line to limit the flow through the travel motor.

[0026] Furthermore, the maximum flow rate set for each speed control valve in the front drive control valve group and the rear drive control valve group is greater than the flow rate required by the corresponding motor when the vehicle is traveling at its highest speed. When the load on the front or rear wheels of the vehicle decreases and the actual flow rate provided by the travel pump 1 is greater than the maximum flow rate set for the corresponding speed control valve, the corresponding speed control valve supplies oil to the motor corresponding to the wheel with reduced load according to its maximum flow rate set, and the remaining flow rate provided by the travel pump 1 is supplied to the motor of the other drive axle.

[0027] In forward operating mode, the oil from port A1 of the travel pump 1 enters port A1 of the travel motor 5 through the directional valve activated in the flow limiting unit I6, and simultaneously enters port A1 of the rear drive motor 4 through the speed regulating valve of the rear drive control valve group I2. The return oil from port B1 of the rear drive motor 4 flows back through the check valve of the rear drive control valve group II3; the return oil from port B1 of the travel motor 5 flows back through the directional valve activated in the flow limiting unit II7, forming a four-wheel drive circuit.

[0028] When the load on the front wheels decreases, the reversing valve in the flow limiting unit I6 reverses and closes. The oil from port A1 of the travel pump 1 enters port A1 of the travel motor 5 through the one-way speed regulating valve group III in the flow limiting unit I6. The one-way speed regulating valve group III limits the flow into the front motor, limits the front wheel speed, and preferentially distributes the flow to the rear drive motor 4.

[0029] When the load on the rear wheels decreases, the speed control valve in the rear drive control valve group I2 limits the flow into the rear drive motor 4, and the flow is preferentially distributed to the front drive to limit rear wheel slippage.

[0030] In reverse operation, the oil from port B1 of the travel pump 1 enters port B1 of the travel motor 5 through the directional valve activated in the flow limiting unit II7, and simultaneously enters port B1 of the rear drive motor 4 through the speed regulating valve of the rear drive control valve group II3. The return oil from port A1 of the travel motor 5 flows back through the directional valve activated in the flow limiting unit I6; the return oil from port A1 of the rear drive motor 4 flows back through the check valve of the rear drive control valve group I2, forming a four-wheel drive circuit.

[0031] When the load on the front wheels decreases, the reversing valve in the flow limiting unit II7 switches off and closes. The oil from port B1 of the travel pump 1 enters port B1 of the travel motor 5 through the one-way speed regulating valve group IV in the flow limiting unit II7. The one-way speed regulating valve group IV limits the flow into the front motor and limits the front wheel speed.

[0032] When the load on the rear wheels decreases, the speed control valve in the rear drive control valve group II3 restricts the flow into the rear drive motor 4, and the flow is preferentially distributed to the front drive to limit rear wheel slippage.

[0033] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A vehicle hydraulic four-wheel drive system, comprising a travel pump, a travel motor, a rear drive motor, a front drive control valve group, and a rear drive control valve group, wherein the travel pump is connected to the rear drive motor via the rear drive control valve group, and the travel pump is connected to the travel motor via the front drive control valve group, characterized in that: The rear drive control valve assembly includes rear drive control valve assembly I and rear drive control valve assembly II. Both rear drive control valve assembly I and rear drive control valve assembly II are composed of a check valve and a speed control valve connected in parallel. Rear drive control valve assembly I and rear drive control valve assembly II are respectively installed at the two oil ports of the rear drive motor. The front drive control valve assembly is installed between the travel pump and the forward oil inlet of the travel motor. The front drive control valve assembly includes a directional valve, a one-way speed control valve assembly I, and a one-way speed control valve assembly II. Both one-way speed control valve assembly I and one-way speed control valve assembly II are composed of a check valve and a speed control valve connected in parallel. Group II is connected in series and then in parallel with the reversing valve. The same valves in the one-way speed control valve group I and the one-way speed control valve group II have opposite directions. Under normal conditions, the reversing valve is in the conducting state so that the travel pump and the forward oil inlet of the travel motor are connected through the reversing valve. When the load on the front wheel corresponding to the travel motor decreases, the reversing valve switches to the closed state, so that the travel pump and the forward oil inlet of the travel motor are connected through the one-way speed control valve group I and the one-way speed control valve group II to limit the flow rate through the travel motor. The travel pump and the forward return oil inlet of the travel motor are directly connected through the oil circuit.

2. A vehicle hydraulic four-wheel drive system, comprising a travel pump, a travel motor, a rear drive motor, a front drive control valve group, and a rear drive control valve group, wherein the travel pump is connected to the rear drive motor via the rear drive control valve group, and the travel pump is connected to the travel motor via the front drive control valve group, characterized in that: The rear drive control valve assembly includes rear drive control valve assembly I and rear drive control valve assembly II. Both rear drive control valve assembly I and rear drive control valve assembly II are composed of a check valve and a speed control valve connected in parallel. Rear drive control valve assembly I and rear drive control valve assembly II are respectively installed at the two oil ports of the rear drive motor. The front drive control valve assembly includes flow limiting unit I and flow limiting unit II. Flow limiting unit I is installed between the travel pump and the forward oil inlet of the travel motor. Flow limiting unit I includes a reversing valve and a one-way speed control valve assembly III. The reversing valve and the one-way speed control valve assembly III are connected in parallel. The one-way speed control valve assembly III consists of a check valve and a speed control valve assembly III. The flow limiting unit II is installed between the travel pump and the reverse oil inlet of the travel motor. The flow limiting unit II includes a reversing valve and a one-way speed control valve group IV. The reversing valve and the one-way speed control valve group IV are connected in parallel. The one-way speed control valve group IV is composed of a one-way valve and a speed control valve connected in parallel. The reversing valve is normally in the open state. When the load on the front wheel corresponding to the travel motor decreases, the reversing valve on the corresponding oil inlet line switches to the closed state, so that the travel pump and the travel motor are connected through the one-way speed control valve group on the corresponding oil inlet line, thereby limiting the flow rate through the travel motor.

3. A vehicle hydraulic four-wheel drive system according to claim 1 or 2, characterized in that: The maximum flow rate set for each speed control valve in the front drive control valve group and the rear drive control valve group is greater than the flow rate required by the corresponding motor when the vehicle is traveling at its highest speed. When the load on the front or rear wheels of the vehicle decreases and the actual flow rate provided by the travel pump is greater than the maximum flow rate set for the corresponding speed control valve, the corresponding speed control valve supplies oil to the motor corresponding to the wheel with reduced load according to its maximum flow rate set, and the remaining flow rate provided by the travel pump is supplied to the motor of the other drive axle.

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