A closed-loop hydraulic system for mobile machinery and its control method

Abstract

This invention relates to a closed-loop hydraulic system for a mobile machine, comprising a hydraulic oil tank, a power source, a closed-loop pump, a pedal control valve 8, a left-side motor, a right-side motor, a remote control valve, and a shuttle valve assembly. The pedal control valve can control the output of hydraulic oil through its working ports A and B. The remote control valve can remotely control the output of hydraulic oil through its working ports A and B. The working port A of the closed-loop pump is connected to the working port B of the left-side motor and the working port A of the right-side motor. The working port B of the closed-loop pump is connected to the working port A of the left-side motor and the working port B of the right-side motor. When both the working ports B and A of the left-side motor are filled with oil, the left-side motor and the right-side motor rotate and drive the mobile machine forward. When both the working ports A and B of the left-side motor are filled with oil, the left-side motor and the right-side motor rotate and drive the mobile machine backward.

Description

Technical Field

[0001] This invention relates to the field of hydraulic systems for mobile machinery, and more specifically to a closed-loop hydraulic system for mobile machinery and its control method. Background Technology

[0002] Hydraulic systems in mobile machinery are generally closed systems. Traditionally, a diesel engine drives a closed-loop pump, which in turn drives a hydraulic motor. This hydraulic motor can either directly rotate the tires to move the vehicle, or it can drive a speed reducer to rotate the tires and move the vehicle. The same pedal is used for both forward and reverse movement, controlled by manually shifting gears. Braking is achieved using a separate brake pedal.

[0003] Traditional solutions are widely used due to their advantages such as compact structure, high efficiency, smooth transmission, and light weight. However, they still have many limitations in practical use, such as: 1. The same pedal is used for both forward and reverse movement, requiring additional manual gear shifting to switch between forward and reverse. Furthermore, a separate brake pedal is needed for braking, making the operation cumbersome and unsuitable for scenarios requiring frequent switching between forward, reverse, and braking. 2. When the vehicle breaks down and needs to be towed, the hydraulic oil in the closed system has a braking effect on the motor, making it difficult to drive the motor during towing. Therefore, the pipelines in the closed system need to be disconnected to complete the towing, wasting time and polluting the environment. 3. The drive wheels for walking and the steering wheels for steering are separate wheel sets, occupying a large space and making them difficult to apply in vehicles with limited space. 4. Remote driving functionality is lacking; operators can only operate from the driver's cab, posing significant safety hazards in a hazardous working environment. 5. Using a diesel engine as the power source causes serious environmental pollution when used indoors. Summary of the Invention

[0004] In view of the above-mentioned deficiencies of the prior art, the technical problem to be solved by the present invention is to provide a closed hydraulic system for walking machinery and its control method, which eliminates the need for gear shifting and allows switching between forward and backward movement simply by stepping on different pedals, resulting in high operating efficiency and remote control capability.

[0005] To achieve the above objectives, the present invention provides a closed-loop hydraulic system for mobile machinery, used to control the movement of the mobile machinery, including a hydraulic oil tank, a power source device, a closed-loop pump, a pedal control valve, a left-side motor, a right-side motor, a remote control valve, and a shuttle valve assembly; the pedal control valve includes a forward control unit and a backward control unit, which can respectively control the output of hydraulic oil from working ports A and B of the pedal control valve; the remote control valve includes a forward remote control unit and a backward remote control unit, both of which can receive remote control commands and can respectively control the output of hydraulic oil from working ports A and B of the remote control valve; the closed-loop pump has working ports A and B, a control port Y1, and a control port Y2; when oil enters the control port Y1, it controls the output of hydraulic oil from working port A; when oil enters the control port Y2, it controls the output of hydraulic oil from working port B; the shuttle valve assembly includes several... A shuttle valve is used to connect the working oil port A of the pedal control valve and the working oil port B of the remote control valve to the control oil port Y1 of the closed pump. The working oil ports A and B of the pedal control valve are not connected to each other. The working oil ports B of the left motor and A of the right motor are both connected to the working oil port A of the closed pump. The working oil ports B and A of the pedal control valve and the remote control valve are both connected to the control oil port Y2 of the closed pump via a shuttle valve. The working oil ports B and A of the pedal control valve are not connected to each other. The working oil ports A and B of the left motor and the right motor are both connected to the working oil port B of the closed pump. When oil is flowing into both the working oil ports B and A of the left and right motors, the left and right motors rotate and drive the traveling mechanism forward. When oil is flowing into both the working oil ports A and B of the left and right motors, the left and right motors rotate and drive the traveling mechanism backward.

[0006] Furthermore, it also includes a parking brake control device, which includes a warning pressure switch and a brake pressure switch; the warning pressure switch is connected to the control port Y2 of the closed pump and can sense the inlet pressure of the control port Y2; the brake pressure switch is connected to the control ports Y1 and Y2 of the closed pump through a shuttle valve and can sense the inlet pressure of the control ports Y1 and Y2.

[0007] Furthermore, the closed-loop pump is equipped with an oil replenishment component, which can draw oil from the hydraulic oil tank and replenish the closed-loop pump.

[0008] Furthermore, it also includes a heat dissipation device, which comprises a radiator and a heat dissipation valve. The heat dissipation valve has an oil inlet A, an oil inlet B, and an oil outlet T. When the oil inlet pressure of oil inlet A is greater than the oil inlet pressure of oil inlet B, oil inlet A is disconnected from oil outlet T, and oil inlet B is connected to oil outlet T. When the oil inlet pressure of oil inlet A is less than the oil inlet pressure of oil inlet B, oil inlet A is connected to oil outlet T, and oil inlet B is disconnected from oil outlet T. The oil outlet T of the heat dissipation valve is connected to the inlet of the radiator. The working oil port A of the heat dissipation valve is connected to the working oil port A of the closed-loop pump, and the working oil port B of the heat dissipation valve is connected to the working oil port B of the closed-loop pump. The outlet of the radiator is connected to the hydraulic oil tank.

[0009] Furthermore, the heat dissipation device also includes a one-way valve, the two ends of which are connected to the inlet and outlet of the radiator, respectively.

[0010] Furthermore, it also includes a trailer control device, which includes a connecting pipe and a switching valve. The two ends of the connecting pipe are respectively connected to the working oil port B and the working oil port A of the closed pump, and the switching valve is installed on the connecting pipe.

[0011] Furthermore, it also includes a central rotary joint, which includes an oil collecting end and an oil distributing end. The oil collecting end has an oil collecting port A connected to the working oil port A of the closed-loop pump, and an oil collecting port B connected to the working oil port B of the closed-loop pump. The oil distributing end includes an oil distributing port group A and an oil distributing port group B. The oil distributing port group A includes several oil distributing ports connected to the oil collecting port A. The oil collecting port A is connected to the working oil port A of the left motor and the working oil port B of the right motor through the oil distributing port group A. The oil distributing port group B includes several oil distributing ports connected to the oil collecting port B. The oil collecting port B is connected to the working oil port B of the left motor and the working oil port A of the right motor through the oil distributing port group B.

[0012] Furthermore, the power source device includes an electric motor and a coupling, wherein the electric motor is connected to a closed pump via the coupling.

[0013] Furthermore, it also includes a confluence block, which can bring together the dispersed hydraulic oil circuits. The working oil port A and working oil port B of the closed pump are both connected to the confluence block. The working oil port A and working oil port B of the left motor are both connected to the confluence block. The working oil port A and working oil port B of the right motor are both connected to the confluence block.

[0014] This invention also discloses a control method for a closed hydraulic system of a mobile machine, the control method comprising the following steps:

[0015] S1, Parking Mode: Neither the pedal control valve nor the remote control valve outputs hydraulic control oil to the closed-loop pump, and the closed-loop pump does not output hydraulic oil to the motor. The closed-loop hydraulic system is in parking mode.

[0016] S2, Forward Mode:

[0017] S21. On-site control: When the remote control valve is not working, the forward control unit of the pedal control valve controls the working port A of the pedal control valve to output hydraulic control oil to the working port Y1 of the closed pump. The working port A of the closed pump outputs high-pressure hydraulic oil to the working port B of the left motor and the working port A of the right motor. The left motor and the right motor rotate and drive the walking machinery forward. The closed hydraulic system is in forward mode.

[0018] S22. Remote control: When the pedal control valve is not working, the remote control valve's forward control unit controls the working port B of the remote control valve to output hydraulic control oil to the working port Y1 of the closed pump. The working port A of the closed pump outputs high-pressure hydraulic oil to the working port B of the left motor and the working port A of the right motor. The left motor and the right motor rotate and drive the walking machinery forward. The closed hydraulic system is in forward mode.

[0019] S3, Back Mode:

[0020] S31. On-site control: When the remote control valve is not working, the reversing control unit of the pedal control valve controls the working port B of the pedal control valve to output hydraulic control oil to the working port Y2 of the closed pump. The working port B of the closed pump outputs high-pressure hydraulic oil to the working port A of the left motor and the working port B of the right motor. The left motor and the right motor rotate and drive the walking machinery to move backward. The closed hydraulic system is in the reversing mode.

[0021] S32. Remote control: When the pedal control valve is not working, the remote control valve's reversing remote control unit controls the working port A of the remote control valve to output hydraulic control oil to the working port Y2 of the closed pump. The working port B of the closed pump outputs high-pressure hydraulic oil to the working port A of the left motor and the working port B of the right motor. The left motor and the right motor rotate and drive the walking machinery to move backward. The closed hydraulic system is in reversing mode.

[0022] As described above, the closed-loop hydraulic system and control method for the walking machinery involved in this invention have the following beneficial effects:

[0023] 1. By setting up a pedal control valve, the operator can control the forward or backward movement of the walking machine by controlling the forward control unit and the backward control unit of the pedal control valve. When switching the forward or backward movement of the walking machine, only two control units need to be controlled, and no additional manual gear shifting operation is required. The operation is simple and suitable for usage scenarios where forward or backward movement is frequently switched.

[0024] 2. By setting up a remote control valve that can be controlled remotely, the operator can remotely control the forward or backward movement of the traveling machinery by controlling the forward and backward remote control units of the remote control valve. This allows the traveling machinery to be operated from the cab and also has the function of remote driving. It enables the operator to operate the traveling machinery remotely in hazardous working environments, avoiding potential safety hazards, and is suitable for use in hazardous working environments.

[0025] 3. By setting up a closed-loop pump, the speed of the motor can be controlled by adjusting the flow rate of the hydraulic oil output by the closed-loop pump, thereby controlling the acceleration, deceleration and braking of the traveling machinery. There is no need to set up a separate brake pedal, which further simplifies the operation and greatly improves the operating efficiency. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the closed hydraulic system of the present invention.

[0027] Explanation of icon numbers

[0028] 1. Hydraulic oil tank; 2. Check valve; 3. Radiator; 4. Electric motor; 5. Coupling; 6. Closed-loop pump; 601. Flow control valve; 7. Shuttle valve; 8. Pedal control valve; 9. Cooling valve; 10. Merging block; 11. Trailer control device; 12. Central rotary joint; 13. Left motor; 14. Right motor; 15. Parking brake control device; 151. Indication pressure switch; 152. Brake pressure switch; 16. Remote control valve. Detailed Implementation

[0029] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0030] In the description of this invention, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the system or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0031] 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 can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0032] Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0033] See Figure 1This invention provides a closed-loop hydraulic system for mobile machinery, used to control the movement of the mobile machinery. It includes a hydraulic oil tank 1, a power source device, a closed-loop pump 6, a pedal control valve 8, a left-side motor 13, a right-side motor 14, a remote control valve 16, and a shuttle valve assembly. The closed-loop pump 6, pedal control valve 8, and remote control valve 16 are respectively connected to the hydraulic oil tank 1. The power source device, pedal control valve 8, left-side motor 13, right-side motor 14, and remote control valve 16 are respectively connected to the closed-loop pump 6. The pedal control valve 8 includes a forward control unit and a backward control unit, which can respectively control the pedal control valve 8. The working ports A and B output hydraulic oil. The remote control valve 16 includes a forward remote control unit and a reverse remote control unit. Both the forward and reverse remote control units can receive remote control commands and can control the output of hydraulic oil from the working ports A and B of the remote control valve 16, respectively. The closed-loop pump 6 has a working port A, a working port B, a control port Y1, and a control port Y2. When oil enters the control port Y1, it controls the output of hydraulic oil from the working port A. When oil enters the control port Y2, it controls the output of hydraulic oil from the working port B. The closed-loop pump 6 is an existing structure, and its specific structural principle will not be described in detail. The shuttle valve assembly includes several shuttle valves 7. The working port A of the pedal control valve 8 and the working port B of the remote control valve 16 are both connected to the control port Y1 of the closed-loop pump 6 through a shuttle valve 7. The working port A of the pedal control valve 8 and the working port B of the remote control valve 16 are not interconnected. The working port B of the left motor 13 and the working port A of the right motor 14 are both connected to the working port A of the closed-loop pump 6. The working port B of the pedal control valve 8 and the working port A of the remote control valve 16 are both connected to the control port Y2 of the closed-loop pump 6 through a shuttle valve 7. The working port B of the pedal control valve 8 and the working port A of the remote control valve 16 are not interconnected. Oil ports A are not interconnected. The working oil port A of the left motor 13 and the working oil port B of the right motor 14 are both connected to the working oil port B of the closed pump 6. When oil is flowing into both the working oil port B of the left motor 13 and the working oil port A of the right motor 14, the left motor 13 and the right motor 14 rotate and drive the traveling machinery forward. When oil is flowing into both the working oil port A of the left motor 13 and the working oil port B of the right motor 14, the left motor 13 and the right motor 14 rotate and drive the traveling machinery backward. Preferably, the forward control unit of the pedal control valve 8 is set as a forward pedal, and the backward control unit of the pedal control valve 8 is set as a backward pedal.

[0034] The basic working principle of the closed-loop hydraulic system of the traveling machinery involved in this invention is as follows: The pedal control valve 8 is used for on-site control of the traveling machinery. The forward control unit of the pedal control valve 8 controls the pedal control valve 8 to output hydraulic oil through its working port A to the control port Y1 of the closed-loop pump 6. The closed-loop pump 6 can output high-pressure hydraulic oil through its working port A to the working port B of the left motor 13 and the working port A of the right motor 14. The left motor 13 and the right motor 14 drive the wheels to rotate forward, enabling the traveling machinery to move forward. Simultaneously, hydraulic oil exits from the low-pressure working ports of the left motor 13 and the right motor 14, that is, the hydraulic oil flows back from the working port A of the left motor 13 and the working port B of the right motor 14 to the closed-loop pump 6. The working port B of the closed-loop pump 6; the reversing control unit of the pedal control valve 8 can control the pedal control valve 8 to output hydraulic oil to the control port Y2 of the closed-loop pump 6 through its working port B. The closed-loop pump 6 can output high-pressure hydraulic oil to the working port A of the left motor 13 and the working port B of the right motor 14 through its working port B. The left motor 13 and the right motor 14 drive the wheels to rotate backward, and the traveling machinery can move backward. At the same time, the hydraulic oil comes out from the low-pressure working ports of the left motor 13 and the right motor 14, that is, the hydraulic oil flows back from the working port B of the left motor 13 and the working port A of the right motor 14 to the working port A of the closed-loop pump 6; the remote control valve 16 is used to realize remote control, which can be controlled by an external remote control. The remote controller sends control commands to the remote control valve 16 to control the actions of the forward and reverse remote control units. By controlling the forward remote control unit of the remote control valve 16, the remote control valve 16 outputs hydraulic control oil through its working port B to the control port Y1 of the closed-loop pump 6. The closed-loop pump 6 can output high-pressure hydraulic oil through its working port A to the working port B of the left motor 13 and the working port A of the right motor 14. The motor 13 drives the wheels forward, enabling remote control of the vehicle's forward movement. By controlling the reverse remote control unit of the remote control valve 16, the remote control valve 16 can output hydraulic oil through its working port A to the control port Y2 of the closed-loop pump 6. The closed-loop pump 6 can output high-pressure hydraulic oil through its working port B to the working port A of the left motor 13 and the working port B of the right motor 14. The motor 13 drives the wheel to rotate backward, enabling remote control of the walking machinery to move backward. Furthermore, by adjusting the hydraulic control oil pressure output to the closed-loop pump 6 through the pedal control valve 8 and the remote control valve 16, the closed-loop pump 6 can adjust the hydraulic oil flow rate according to the different hydraulic control oil pressures it receives. When the flow rate output by the closed-loop pump 6 increases, the speed of the left motor 13 and the right motor 14 will also increase; when the flow rate output by the closed-loop pump 6 decreases, the speed of the left motor 13 and the right motor 14 will also decrease.Therefore, operators do not need to shift gears; they only need to control different control units or remote control units to switch between forward and reverse directions, as well as to accelerate or decelerate and brake the walking machinery. This results in high operational efficiency and remote control capabilities, thus avoiding potential safety hazards in hazardous working environments. It is suitable for use in dangerous work environments.

[0035] See Figure 1 The present invention will be further described below with reference to a specific embodiment:

[0036] In this embodiment, see Figure 1 As a preferred design, the system also includes a parking brake control device 15, which includes a warning pressure switch 151 and a brake pressure switch 152. The warning pressure switch 151 is connected to the control port Y2 of the closed-loop pump 6 and can sense the inlet pressure of the control port Y2. When the pressure of the warning pressure switch 151 is greater than 5 bar, that is, when the pressure of the control port Y2 is greater than 5 bar, the warning pressure switch 151 can output a signal to enable the traveling machinery to perform operations such as turning on the reversing lights or activating the reversing voice. The brake pressure switch 152 is connected to the control ports Y1 and Y2 of the closed-loop pump 6 through a shuttle valve and can sense the inlet pressure of the control ports Y1 and Y2. When the pressure of the brake pressure switch 152 is greater than 5 bar, that is, when the pressure of either the control port Y1 or the control port Y2 of the closed-loop pump 6 is greater than 5 bar, the brake pressure switch 152 can output a signal to close the brake of the traveling machinery, enabling the traveling machinery to perform forward or reverse operations. In this embodiment, specifically, a shuttle valve 7 is provided to simultaneously connect the control port Y1 and the control port Y2 of the closed pump 6, and the control ports Y1 and Y2 are not interconnected. The brake pressure switch 152 is connected to the shuttle valve 7, thereby connecting to both the control ports Y1 and Y2.

[0037] In this embodiment, see Figure 1 As a preferred design, the closed pump 6 is equipped with an oil replenishment component inside. The oil replenishment component can draw oil from the hydraulic oil tank 1 and replenish the closed pump 6. The oil replenishment component is connected to the hydraulic oil tank 1 through the working oil port S of the closed pump 6.

[0038] In this embodiment, see Figure 1As a preferred design, a heat dissipation device is also included, which includes a radiator 3 and a heat dissipation valve 9. The heat dissipation valve 9 has an oil inlet A, an oil inlet B, and an oil outlet T. When the oil inlet pressure of the oil inlet A is greater than the oil inlet pressure of the oil inlet B, the oil inlet A is disconnected from the oil outlet T, and the oil inlet B is connected to the oil outlet T. When the oil inlet pressure of the oil inlet A is less than the oil inlet pressure of the oil inlet B, the oil inlet A is connected to the oil outlet T, and the oil inlet B is disconnected from the oil outlet T. The specific structural principle of the heat dissipation valve 9 is existing and will not be described in detail. The drain port T of the cooling valve 9 is connected to the inlet of the radiator. Specifically, the drain port T of the cooling valve 9 is connected to the drain port T1 of the closed-loop pump 6, the drain port T1 of the closed-loop pump 6 is connected to the drain port T2 of the closed-loop pump 6, and the drain port T2 of the closed-loop pump 6 is connected to the inlet of the radiator 3. The working port A of the cooling valve 9 is connected to the working port A of the closed-loop pump 6, and the working port B of the cooling valve 9 is connected to the working port B of the closed-loop pump 6. With this design, regardless of whether the motor 13 rotates forward or backward, the hydraulic oil on its low-pressure side will be delivered to the radiator 3 through the cooling valve 9. The outlet of the radiator 3 is connected to the hydraulic oil tank 1. The cooling valve 9 increases the fluidity of the hydraulic oil in the housing of the closed-loop pump 6, improving the heat dissipation efficiency of the closed-loop pump 6. The radiator 3 improves the cooling efficiency of the closed-loop hydraulic system.

[0039] In this embodiment, see Figure 1 As a preferred design, the heat dissipation device also includes a one-way valve 2, the two ends of which are connected to the inlet and outlet of the radiator 3, respectively. When the radiator 3 is blocked, the hydraulic oil of the closed pump 6 flows back to the oil tank through the one-way valve 2, which can prevent the housing pressure of the closed pump 6 from being too high and avoid damage to the oil seal of the closed pump 6.

[0040] In this embodiment, see Figure 1 As a preferred design, a trailer control device 11 is also included. The trailer control device 11 includes a connecting pipe and a switching valve. The two ends of the connecting pipe are respectively connected to the working oil port B and the working oil port A of the closed pump 6. The switching valve is installed on the connecting pipe. When the switching valve is opened, the hydraulic oil output by the closed pump 6 to the working oil port B of the left motor 13 and the working oil port A of the right motor 14 can enter the working oil port A of the left motor 13 and the working oil port B of the right motor 14 through the connecting pipe and the switching valve. Alternatively, the hydraulic oil output by the closed pump 6 to the working oil port A of the left motor 13 and the working oil port B of the right motor 14 can enter the working oil port B of the left motor 13 and the working oil port A of the right motor 14 through the connecting pipe and the switching valve, so that the interior of the left motor 13 and the right motor 14 forms a floating circuit. Under the inertial force of its own weight or load and the action of external force, the traveling machinery can still move, thereby facilitating the traveling machinery to complete the trailer operation. In addition, the left motor 13 is connected to the hydraulic oil tank 1 through its working oil port L for oil draining, and the right motor 14 is also connected to the hydraulic oil tank 1 through its working oil port L for oil draining.

[0041] In this embodiment, see Figure 1 As a preferred design, a central rotary joint 12 is also included. The central rotary joint 12 includes an oil collecting end and an oil distributing end. The oil collecting port A of the oil collecting end is connected to the working oil port A of the closed-loop pump 6, and the oil collecting port B of the oil collecting end is connected to the working oil port B of the closed-loop pump 6. The oil distributing end includes an oil distributing port group A and an oil distributing port group B. The oil distributing port group A includes two oil distributing ports A1 and A2 that are connected to the oil collecting port A. The oil collecting port A is connected to the working oil port A of the left motor 13 and the right motor 14 respectively through the oil distributing ports A1 and A2 of the oil distributing port group A. The working port B and the oil distribution port group B include two oil distribution ports B1 and B2 connected to the oil collection port B. The oil collection port B is connected to the working port B of the left motor 13 and the working port A of the right motor 14 through the oil distribution port group B's oil distribution ports B1 and B2. By setting the central rotary joint 12, the pipelines in the closed hydraulic system can be prevented from getting tangled. Therefore, the traveling wheels of the traveling machinery can be set as steering wheels, making the overall structure of the closed hydraulic system more compact, occupying less space, and suitable for traveling machinery in confined spaces.

[0042] In this embodiment, see Figure 1 As a preferred design, the power source device includes an electric motor 4 and a coupling 5. The electric motor 4 is connected to the closed pump 6 through the coupling 5. Using the electric motor 4 as the power source will not pollute the environment when used indoors, and it can also save energy.

[0043] In this embodiment, see Figure 1 As a preferred design, it also includes a confluence block 10, which can bring together the dispersed hydraulic oil circuits. The working oil port A and working oil port B of the closed pump 6 are both connected to the confluence block 10. The working oil port A and working oil port B of the left motor 13 are both connected to the confluence block 10. The working oil port A and working oil port B of the right motor 14 are both connected to the confluence block 10. At the same time, the trailer control device 11, including the connecting pipe and the cooling valve 9, is also connected to the confluence block 10.

[0044] In this embodiment, see Figure 1 As a preferred design, the closed-loop pump 6 is also equipped with a flow control valve 601. The working port a of the flow control valve 601 is connected to the control port Y1 of the closed-loop pump 6, and the working port b of the flow control valve 601 is connected to the control port Y2 of the closed-loop pump 6. The flow control valve 601 can control the flow rate of the hydraulic oil output by the closed-loop pump 6 according to the pressure received by its working port a or working port b. The greater the pressure received by the flow control valve 601, the greater the flow rate output by the closed-loop pump 6 and the faster the speed of the left motor 13 and the right motor 14. The lower the pressure received by the flow control valve 601, the smaller the flow rate output by the closed-loop pump 6 and the slower the speed of the left motor 13 and the right motor 14.

[0045] See Figure 1 The present invention also discloses a control method for a closed hydraulic system of a mobile machine, the control method comprising the following steps:

[0046] S1, Parking mode: Neither pedal control valve 8 nor remote control valve 16 outputs hydraulic control oil to closed pump 6, and closed pump 6 does not output hydraulic oil to motor 13. The closed hydraulic system is in parking mode.

[0047] S2, Forward Mode:

[0048] S21. On-site control: When the remote control valve 16 is not working, the forward control unit of the pedal control valve 8 controls the working port A of the pedal control valve 8 to output hydraulic oil to the control port Y1 of the closed pump 6. The working port A of the closed pump 6 outputs high-pressure hydraulic oil to the working port B of the left motor 13 and the working port A of the right motor 14. The working port A of the left motor 13 and the working port B of the right motor 14 output low-pressure hydraulic oil to the working port B of the closed pump 6, causing the left motor 13 and the right motor 14 to rotate and drive the walking machinery forward. The closed hydraulic system is in forward mode. Furthermore, the output pressure of the working port A of the pedal control valve 8 is controlled by the forward control unit to control the output flow of the working port A of the closed pump 6, thereby realizing acceleration or deceleration during forward movement.

[0049] S22. Remote Control: When the pedal control valve 8 is not working, the forward remote control unit of the remote control valve 16 controls the working port B of the remote control valve 16 to output hydraulic oil to the control port Y1 of the closed pump 6. The working port A of the closed pump 6 outputs high-pressure hydraulic oil to the working port B of the left motor 13 and the working port A of the right motor 13. The working ports A of the left motor 13 and B of the right motor 13 output low-pressure hydraulic oil to the working port B of the closed pump 6, causing the left motor 13 and the right motor 14 to rotate and drive the walking machinery forward. The closed hydraulic system is in forward mode. Furthermore, the output pressure of the working port A of the pedal control valve 8 is controlled by the forward remote control unit to control the output flow of the working port A of the closed pump 6, thereby realizing acceleration or deceleration during forward movement.

[0050] S3, Back Mode:

[0051] S31. On-site control: When the remote control valve 16 is not working, the reversing control unit of the pedal control valve 8 controls the working port B of the pedal control valve 8 to output hydraulic oil to the control port Y2 of the closed pump 6. The working port B of the closed pump 6 outputs high-pressure hydraulic oil to the working port A of the left motor 13 and the working port B of the right motor 13. The working port B of the left motor 13 and the working port A of the right motor 13 output low-pressure hydraulic oil to the working port A of the closed pump 6, causing the left motor 13 and the right motor 14 to rotate and drive the walking machinery to move backward. The closed hydraulic system is in reversing mode. Furthermore, the output pressure of the working port B of the pedal control valve 8 is controlled by the reversing control unit to control the output flow of the working port B of the closed pump 6, thereby realizing acceleration or deceleration during reversing.

[0052] S32. Remote Control: When the pedal control valve 8 is not working, the remote control unit of the remote control valve 16 controls the working port A of the remote control valve 16 to output hydraulic oil to the control port Y2 of the closed pump 6. The working port B of the closed pump 6 outputs high-pressure hydraulic oil to the working port A of the left motor 13 and the working port B of the right motor (13). The working ports B of the left motor 13 and A of the right motor 13 output low-pressure hydraulic oil to the working port A of the closed pump 6, causing the left motor 13 and the right motor 14 to rotate and drive the walking machinery to move backward. The closed hydraulic system is in the backward mode. In addition, the output pressure of the working port B of the pedal control valve 8 is controlled by the backward control unit to control the output flow of the working port B of the closed pump 6, thereby realizing acceleration or deceleration during backward movement.

[0053] As described above, the control method for the closed hydraulic system of the mobile machinery of the present invention has the following beneficial effects:

[0054] 1. By setting up pedal control valve 8, the operator can control the forward or backward movement of the walking machine by controlling the forward control unit and the backward control unit of pedal control valve 8. When switching the forward or backward movement of the walking machine, only two control units need to be controlled, and no additional manual gear shifting operation is required. The operation is simple and suitable for use scenarios where forward or backward movement is frequently switched.

[0055] 2. By setting a remote control valve 16 that can be controlled remotely, the operator can remotely control the forward or backward movement of the traveling machinery by controlling the forward remote control unit and the backward remote control unit of the remote control valve 16. This allows the traveling machinery to be operated from the cab and also has the function of remote driving. It enables the operator to operate the traveling machinery remotely in a dangerous working environment, avoiding potential safety hazards. It is suitable for use in dangerous working environments.

[0056] 3. By setting up a closed-loop pump 6, the speed of motor 13 can be controlled by adjusting the hydraulic oil flow rate output by the closed-loop pump 6, thereby controlling the acceleration, deceleration and braking of the traveling machinery. There is no need to set up a separate brake pedal, which further simplifies the operation and greatly improves the operating efficiency.

[0057] In summary, this invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0058] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A closed-loop hydraulic system for mobile machinery, used to control the movement of the mobile machinery, characterized in that: The system includes a hydraulic oil tank (1), a power source, a closed-loop pump (6), a pedal control valve (8), a left-side motor (13), a right-side motor (14), a remote control valve (16), and a shuttle valve assembly. The pedal control valve (8) includes a forward control unit and a backward control unit, which can respectively control the output of hydraulic oil from the working port A and working port B of the pedal control valve (8). The remote control valve (16) includes a forward remote control unit and a backward remote control unit. All can receive remote control commands and can respectively control the output of hydraulic oil from working port A and working port B of the remote control valve (16); the closed pump (6) has working port A, working port B, control port Y1 and control port Y2. When oil enters the control port Y1, it controls the output of hydraulic oil from working port A. When oil enters the control port Y2, it controls the output of hydraulic oil from working port B; the shuttle valve group includes several shuttle valves (7). The working port A of the pedal control valve (8) and the working port B of the remote control valve (16) are both connected through a shuttle valve (7). The control port Y1 of the closed-loop pump (6) is connected, and the working port A of the pedal control valve (8) and the working port B of the remote control valve (16) are not connected. The working port B of the left motor (13) and the working port A of the right motor (14) are both connected to the working port A of the closed-loop pump (6). The working port B of the pedal control valve (8) and the working port A of the remote control valve (16) are both connected to the control port Y2 of the closed-loop pump (6) through a shuttle valve (7). The working port B of the pedal control valve (8) and the working port A of the remote control valve (16) are connected. The working ports A are not connected to each other. The working ports A of the left motor (13) and B of the right motor (14) are both connected to the working port B of the closed pump (6). When oil enters the working ports B of the left motor (13) and A of the right motor (14), the left motor (13) and the right motor (14) rotate and drive the traveling machinery forward. When oil enters the working ports A of the left motor (13) and B of the right motor (14), the left motor (13) and the right motor (14) rotate and drive the traveling machinery backward.

2. The closed-loop hydraulic system of the mobile machinery according to claim 1, characterized in that: It also includes a parking brake control device (15), which includes a warning pressure switch (151) and a brake pressure switch (152); the warning pressure switch (151) is connected to the control port Y2 of the closed pump (6) and can sense the inlet pressure of the control port Y2; the brake pressure switch (152) is connected to the control ports Y1 and Y2 of the closed pump (6) through a shuttle valve (7) and can sense the inlet pressure of the control ports Y1 and Y2.

3. The closed-loop hydraulic system of the mobile machinery according to claim 1, characterized in that: The closed-loop pump (6) is equipped with an oil replenishment component, which can draw oil from the hydraulic oil tank (1) and replenish the closed-loop pump (6).

4. The closed-loop hydraulic system of the mobile machinery according to claim 1, characterized in that: It also includes a heat dissipation device, which includes a radiator (3) and a heat dissipation valve (9). The heat dissipation valve (9) has an oil inlet A, an oil inlet B and an oil drain T. When the oil inlet pressure of the oil inlet A is greater than the oil inlet pressure of the oil inlet B, the oil inlet A is disconnected from the oil drain T and the oil inlet B is connected to the oil drain T. When the oil inlet pressure of the oil inlet A is less than the oil inlet pressure of the oil inlet B, the oil inlet A is connected to the oil drain T and the oil inlet B is disconnected from the oil drain T. The oil drain T of the heat dissipation valve (9) is connected to the inlet of the radiator (3). The working oil port A of the heat dissipation valve (9) is connected to the working oil port A of the closed pump (6). The working oil port B of the heat dissipation valve (9) is connected to the working oil port B of the closed pump (6). The outlet of the radiator (3) is connected to the hydraulic oil tank (1).

5. The closed-loop hydraulic system of the mobile machinery according to claim 4, characterized in that: The heat dissipation device also includes a one-way valve (2), the two ends of which are connected to the inlet and outlet of the radiator (3), respectively.

6. The closed-loop hydraulic system of the mobile machinery according to claim 1, characterized in that: It also includes a trailer control device (11), which includes a connecting pipe and a switching valve. The two ends of the connecting pipe are respectively connected to the working oil port B and the working oil port A of the closed pump (6), and the switching valve is installed on the connecting pipe.

7. The closed-loop hydraulic system of the mobile machinery according to claim 1, characterized in that: It also includes a central rotary joint (12), which includes an oil collecting end and an oil distributing end. The oil collecting port A of the oil collecting end is connected to the working oil port A of the closed pump (6), and the oil collecting port B of the oil collecting end is connected to the working oil port B of the closed pump (6). The oil distributing end includes an oil distributing port group A and an oil distributing port group B. The oil distributing port group A includes several oil distributing ports connected to the oil collecting port A. The oil collecting port A is connected to the working oil port A of the left motor (13) and the working oil port B of the right motor (14) through the oil distributing port group A. The oil distributing port group B includes several oil distributing ports connected to the oil collecting port B. The oil collecting port B is connected to the working oil port B of the left motor (13) and the working oil port A of the right motor (14) through the oil distributing port group B.

8. The closed-loop hydraulic system of the mobile machinery according to claim 1, characterized in that: The power source device includes an electric motor (4) and a coupling (5), wherein the electric motor (4) is connected to a closed pump (6) via the coupling (5).

9. The closed-loop hydraulic system of the mobile machinery according to claim 1, characterized in that: It also includes a confluence block (10), which can bring together the dispersed hydraulic oil circuits. The working oil port A and working oil port B of the closed pump (6) are both connected to the confluence block (10). The working oil port A and working oil port B of the left motor (13) are both connected to the confluence block (10). The working oil port A and working oil port B of the right motor (14) are both connected to the confluence block (10).

10. A control method for a closed-loop hydraulic system of a mobile machine as described in any one of claims 1-9, characterized in that: Includes the following steps: S1, Parking mode: Neither the pedal control valve (8) nor the remote control valve (16) outputs hydraulic control oil to the closed pump (6), and the closed pump (6) does not output hydraulic oil to the motor (13). The closed hydraulic system is in parking mode. S2, Forward Mode: S21, On-site control: When the remote control valve (16) is not working, the forward control unit of the pedal control valve (8) controls the working port A of the pedal control valve (8) to output hydraulic oil to the control port Y1 of the closed pump (6). The working port A of the closed pump (6) outputs high-pressure hydraulic oil to the working port B of the left motor (13) and the working port A of the right motor (14). The left motor (13) and the right motor (14) rotate and drive the walking machinery forward. The closed hydraulic system is in forward mode. S22, Remote control: When the pedal control valve (8) is not working, the forward remote control unit of the remote control valve (16) controls the working port B of the remote control valve (16) to output hydraulic oil to the control port Y1 of the closed pump (6), and the working port A of the closed pump (6) outputs high pressure hydraulic oil to the working port B of the left motor (13) and the working port A of the right motor (14). The left motor (13) and the right motor (14) rotate and drive the walking machinery forward. The closed hydraulic system is in forward mode. S3, Back Mode: S31, On-site control: When the remote control valve (16) is not working, the reversing control unit of the pedal control valve (8) controls the working port B of the pedal control valve (8) to output hydraulic oil to the control port Y2 of the closed pump (6). The working port B of the closed pump (6) outputs high-pressure hydraulic oil to the working port A of the left motor (13) and the working port B of the right motor (14). The left motor (13) and the right motor (14) rotate and drive the walking machinery to move backward. The closed hydraulic system is in the reversing mode. S32, Remote control: When the pedal control valve (8) is not working, the remote control control unit controls the remote control valve (16) to output hydraulic oil from the working port A of the remote control valve (16) to the control port Y2 of the closed pump (6), and output high-pressure hydraulic oil from the working port B of the closed pump (6) to the working port A of the left motor (13) and the working port B of the right motor (14). The left motor (13) and the right motor (14) rotate and drive the walking machinery to move backward. The closed hydraulic system is in the backward mode.

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