A skid steer hydraulic system and method of providing a control oil supply and a makeup oil supply

Abstract

This invention discloses a hydraulic system for a skid steer loader and a method for providing control oil and replenishment oil. The hydraulic system includes a working pump, a single-channel flow stabilizing valve, a solenoid directional valve, an electro-hydraulic multi-way valve, and a return oil combination valve. The working pump's suction port is connected to a hydraulic oil tank, and its outlet port is connected to the single-channel flow stabilizing valve. The single-channel flow stabilizing valve is connected to the solenoid directional valve and the electro-hydraulic multi-way valve. The solenoid directional valve is connected to the skid steer loader's motor brake and the electro-hydraulic multi-way valve, providing control oil to both. The return oil port of the electro-hydraulic multi-way valve is connected to the inlet of the return oil combination valve, and the replenishment oil source G port of the return oil combination valve is connected to the skid steer loader's travel pump assembly, providing replenishment oil to the travel pump assembly. This invention uses a single working pump to simultaneously supply oil to the working oil circuit, the motor brake oil circuit, and the electro-hydraulic multi-way valve's control oil circuit, while also providing replenishment oil to the travel pump, achieving oil source sharing and reducing operating costs.

Description

Technical Field

[0001] This invention relates to a hydraulic system for a skid steer loader and a method for providing control oil and replenishment oil, belonging to the technical field of engineering machinery and industrial vehicles. Background Technology

[0002] The skid steer loader's travel system is achieved through a closed hydrostatic system consisting of two piston pumps and two fixed displacement piston motors. In this case, a replenishing pump is necessary to replenish and flush the closed piston pumps and piston motors.

[0003] In addition, the hydraulic system of a skid steer loader needs to provide control oil to the working multi-way valve, motor brake, etc., which requires the addition of a control oil source pump.

[0004] Skid steer loaders are inherently compact. If configured according to the above requirements, adding a make-up oil pump and a control oil pump would not only increase costs but also require additional pump take-off ports, making the overall vehicle structure more complex. This not only increases the overall cost but also adds to the difficulty of layout. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a hydraulic system for a skid steer loader and a method for providing control oil and replenishment oil. A single-channel flow stabilizing valve is added after the working pump, allowing the working pump to provide control oil to the electro-hydraulic multi-way valve and the travel motor brake. By eliminating the need for a replenishment pump, the replenishment function is achieved by increasing the back pressure of the return oil from the working pump.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] This invention provides a hydraulic system for a skid steer loader, including a working pump, a single-channel flow stabilizing valve, a solenoid directional valve, an electro-hydraulic multi-way valve, and a return oil combination valve;

[0008] The suction port of the working pump is connected to the hydraulic oil tank, the outlet port of the working pump is connected to the inlet of the single-channel flow stabilizing valve, and the outlet of the single-channel flow stabilizing valve is connected to the solenoid directional valve and the electro-hydraulic multi-way valve.

[0009] The single-channel flow stabilizing valve is used to output a stable control oil source, supply oil to the solenoid directional valve, and provide oil to the inlet of the electro-hydraulic multi-channel valve.

[0010] The electromagnetic reversing valve is connected to the motor brake and electro-hydraulic multi-way valve of the skid steer loader.

[0011] The electromagnetic reversing valve is used to provide control oil to the motor brake and the electro-hydraulic multi-way valve, control the on / off state of the motor brake, and control the reversing of each action of the electro-hydraulic multi-way valve.

[0012] The working port of the electro-hydraulic multi-way valve is connected to the actuator of the skid steer loader and is used to control the operation of the actuator.

[0013] The return port of the electro-hydraulic multi-way valve is connected to the inlet of the return combination valve, the outlet of the return combination valve is connected back to the hydraulic oil tank, and the replenishment oil source port of the return combination valve is connected to the replenishment oil inlet of the travel pump assembly of the skid steer loader.

[0014] Furthermore, the single-channel flow stabilizing valve includes a sequence valve and a relief valve;

[0015] The oil outlet of the working pump is connected to the inlet E port of the single-channel flow stabilizing valve, and the outlet F port of the single-channel flow stabilizing valve is connected to the oil inlet P1 port of the electromagnetic reversing valve.

[0016] The C port of the sequence valve is connected to the P port of the electro-hydraulic multi-way valve, and the D port of the relief valve is connected to the hydraulic oil tank.

[0017] Furthermore, the relief valve is set to a pressure of 2.1 MPa.

[0018] Furthermore, the working oil port A of the electromagnetic directional valve is connected to the brake control port of the motor brake of the skid steer loader and the control oil source inlet of the electro-hydraulic multi-way valve, and the return oil port of the electromagnetic directional valve is connected to the hydraulic oil tank.

[0019] The motor brake of the skid steer loader is connected to the travel motor, and the oil inlet and outlet of the travel motor are connected to the travel pump to form a closed loop. The travel pump and the working pump are connected in series through a connecting shaft and directly connected to the power source of the skid steer loader.

[0020] Furthermore, the control oil return port L of the electro-hydraulic multi-way valve is connected to the hydraulic oil tank, and the working oil port of the electro-hydraulic multi-way valve is connected to the sliding loading actuator.

[0021] Furthermore, the hydraulic system also includes a radiator.

[0022] The return port T of the electro-hydraulic multi-way valve is connected to the inlet M of the radiator, the outlet K of the radiator is connected to the inlet X of the return combination valve, the outlet Y of the return combination valve is connected to the hydraulic oil tank, and the replenishment oil source port G of the return combination valve is connected to the replenishment oil inlet U of the travel pump.

[0023] Furthermore, the return oil combination valve includes a return oil filter, a return oil filter bypass valve, and a return oil back pressure valve, wherein the return oil filter and the return oil filter bypass valve are connected in parallel.

[0024] Furthermore, the back pressure valve is set to 0.8 MPa.

[0025] The present invention also provides a method for providing control oil and replenishment oil based on the hydraulic system of a skid steer loader, comprising:

[0026] Start the vehicle engine;

[0027] Oil is drawn from the hydraulic tank by the working pump and introduced into the inlet E port of the single-way flow stabilizing valve; one oil source passes through the sequence valve and the relief valve to output stable control oil to the outlet F port of the single-way flow stabilizing valve and supply oil to the solenoid directional valve; another oil source provides oil to the inlet P port of the electro-hydraulic multi-way valve through the C port of the sequence valve.

[0028] The inlet P1 of the electromagnetic directional valve is connected to the working port A, and the electromagnetic directional valve provides control oil to the motor brake and the electro-hydraulic multi-way valve.

[0029] Oil is supplied to the return oil combination valve through the return oil port T of the electro-hydraulic multi-way valve, and replenishment oil is supplied to the travel pump assembly through the replenishment oil source port G of the return oil combination valve.

[0030] Furthermore, the method also includes,

[0031] The return oil from the T-port of the electro-hydraulic multi-way valve is cooled by the radiator and then enters the inlet X-port of the return oil combination valve.

[0032] The returned oil, after being filtered by the return oil filter, overflows through the return oil back pressure valve and returns to the hydraulic oil tank through the outlet Y port of the return oil combination valve.

[0033] The beneficial effects achieved by this invention are as follows:

[0034] 1. This invention, through the control of a working pump and a single-path flow stabilizing valve, enables the working pump to simultaneously supply oil to the working oil circuit, the motor braking oil circuit, and the electro-hydraulic multi-path valve control oil circuit, achieving three-path oil source sharing. This fully utilizes the hydraulic oil source, reduces unnecessary power waste, saves energy, and lowers operating costs.

[0035] 2. This invention provides replenishment oil to the closed-loop travel system through a multi-way valve return oil circuit, optimizes the suction oil return pipeline, and allows the return oil to directly enter the replenishment oil suction pipeline, thus simplifying the hydraulic pipeline.

[0036] 3. This invention features an integrated oil suction and return design, where the return oil is directly sucked away by the replenishment pipeline, which can effectively reduce the volume of the hydraulic oil tank, save layout space, and reduce costs.

[0037] 4. The system of the present invention eliminates the separate oil replenishment pump and control oil source pump of the closed walking system, which reduces costs and simplifies the pump layout. Attached Figure Description

[0038] Figure 1 This is a structural diagram of a skid steer loader hydraulic system provided by the present invention;

[0039] In the diagram: 1-Working pump; 2-Single-way flow stabilizing valve; 21-Sequence valve; 22-Relief valve; 3-Travel pump assembly; 31-Travel pump I; 32-Travel pump II; 4-Travel motor assembly I; 41-Travel motor I; 42-Motor brake I; 5-Travel motor assembly II; 51-Travel motor II; 52-Motor brake II; 6-Solenoid directional valve; 7-Electro-hydraulic multi-way valve; 8-Radiator; 9-Return oil combination valve; 91-Return oil filter; 92-Return oil filter bypass valve; 93-Return oil back pressure valve; 10-Hydraulic oil tank; 11-Actuator. Detailed Implementation

[0040] 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.

[0041] This invention provides a hydraulic system for a skid steer loader, including a working pump, a single-channel flow stabilizing valve, a solenoid directional valve, and an electro-hydraulic multi-way valve;

[0042] The working pump's suction port is connected to the hydraulic oil tank, the working pump's outlet port is connected to the inlet of the single-way flow stabilizing valve, and the single-way flow stabilizing valve's outlet is connected to the solenoid directional valve and the electro-hydraulic multi-way valve.

[0043] A single-way flow stabilizing valve is used to output a stable control oil source, supply oil to a solenoid directional valve, and provide control oil to the inlet of an electro-hydraulic multi-way valve.

[0044] The electromagnetic directional valve is connected to motor brake I, motor brake II, and electro-hydraulic multi-way valve. The electromagnetic directional valve is used to provide control oil to motor brake I, motor brake II, and electro-hydraulic multi-way valve, control the on / off state of motor brake I and motor brake II, and control the directional switching of each action of the electro-hydraulic multi-way valve.

[0045] The working port of the electro-hydraulic multi-way valve is connected to the actuator to control the actuator's movement.

[0046] See Figure 1 In one embodiment of the present invention, the oil suction port of the working pump 1 is connected to the hydraulic oil tank 10, and oil is drawn through the hydraulic oil tank 10. The oil outlet of the working pump 1 is connected to the inlet E port of the single-path flow stabilizing valve 2, and the outlet F port of the single-path flow stabilizing valve 2 is connected to the inlet P1 port of the electromagnetic reversing valve 6.

[0047] In this embodiment, the single-way flow stabilizing valve 2 includes a sequence valve 21 and a relief valve 22; wherein, the C port of the sequence valve 21 is connected to the oil inlet P port of the electro-hydraulic multi-way valve 7, and the D port of the relief valve 22 is connected to the hydraulic oil tank.

[0048] In this embodiment, the relief valve 22 is set to a pressure of 2.1 MPa. The working pump 1 draws oil from the hydraulic oil tank 10 and introduces the oil source into the inlet E port of the single-channel flow stabilizing valve 2. After passing through the sequence valve 21 and the relief valve 22, a stable pilot oil source of 2.1 MPa is output to the outlet F port of the single-channel flow stabilizing valve 2, supplying oil to the inlet P port of the solenoid directional valve 6. Another oil source supplies oil to the inlet P port of the electro-hydraulic multi-way valve 7 through the C port of the sequence valve.

[0049] See Figure 1 In this embodiment, the working oil port A of the electromagnetic reversing valve 6 is connected to the brake control port Z1 of the motor brake I 42, the brake control port Z2 of the motor brake II 52, and the control oil source inlet V of the electro-hydraulic multi-way valve 7. The return oil port T1 of the electromagnetic reversing valve 6 is connected to the hydraulic oil tank 10.

[0050] The electromagnetic directional valve 6 provides control oil to the motor brake I 42, motor brake II 52, and electro-hydraulic multi-way valve 7, controls the on / off state of the motor brakes I 42 and II 52, and controls the directional switching of each component of the electro-hydraulic multi-way valve 7. It should be noted that the directional switching technology of the electro-hydraulic multi-way valve is well-known in the art and will not be described further here.

[0051] See Figure 1 Motor brake I42 is connected to travel motor I41, and motor brake I42 and travel motor I41 together constitute travel motor assembly I4; motor brake II52 is connected to travel motor II51, and motor brake II52 and travel motor II51 together constitute travel motor assembly II5.

[0052] The oil inlet and outlet ports of travel motor I 41 are connected to travel pump I 31 to form a closed loop, and the oil inlet and outlet ports of travel motor II 51 are connected to travel pump II 32 to form a closed loop; travel pump I 31 and travel pump II 32 constitute travel pump assembly 3.

[0053] The traveling pump I 31 and traveling pump II 32 are connected in series with the working pump 1 via a connecting shaft and then directly connected to the engine.

[0054] In this embodiment, the control oil return port L of the electro-hydraulic multi-way valve 7 is connected to the hydraulic oil tank 10, and the working oil port is connected to the actuator 11, which is used to control the action of the actuator 11.

[0055] In this embodiment, the hydraulic system also includes a radiator 8 and a return oil combination valve 9.

[0056] The return port T of the electro-hydraulic multi-way valve 7 is connected to the inlet port M of the radiator 8, the outlet port K of the radiator 8 is connected to the inlet port X of the return combination valve 9, the outlet port Y of the return combination valve 9 is connected to the hydraulic oil tank, and the replenishment oil source port G of the return combination valve 9 is connected to the replenishment oil inlet U of the travel pump assembly 4.

[0057] See Figure 1 The return oil combination valve 9 includes a return oil filter 91, a return oil filter bypass valve 92, and a return oil back pressure valve 93. The return oil filter 91 and the return oil filter bypass valve 92 are connected in parallel to prevent the return oil filter 91 from becoming clogged.

[0058] In this embodiment, the back pressure valve 93 is set to a pressure of 0.8 MPa.

[0059] In this embodiment, the return oil from the return port T of the electro-hydraulic multi-way valve 7, after being cooled by the radiator 8, enters the inlet X of the return oil combination valve 9 and then enters the return oil filter 91 for filtration. Simultaneously, the return oil passing through the return oil filter 91 overflows through the return oil back pressure valve 93 and returns to the hydraulic oil tank via the outlet Y of the return oil combination valve 9. At the same time, the oil supply port G of the return oil combination valve 9 is connected to the oil supply inlet U of the travel pump assembly 4, providing an oil supply source with a back pressure of 0.8 MPa, thus achieving the purpose of replenishing oil to travel pump I 31, travel pump II 32, travel motor I 41, and travel motor II 51.

[0060] Based on the above-described skid steer loader hydraulic system, the present invention also provides a method for providing control oil and replenishment oil in the skid steer loader hydraulic system, as follows:

[0061] Start the vehicle engine;

[0062] Oil is drawn from the hydraulic oil tank 10 by the working pump 1 and introduced into the inlet E port of the single-way flow stabilizing valve 2. One oil source passes through the sequence valve 21 and the relief valve 22 to output stable control oil to the outlet F port of the single-way flow stabilizing valve 2 and supply oil to the solenoid directional valve. The other oil source provides oil to the inlet P port of the electro-hydraulic multi-way valve 7 through the C port of the sequence valve 21.

[0063] In the initial state, the oil inlet P1 port of the electromagnetic reversing valve is closed to the working oil port A. After energization, the oil inlet P1 port and the working oil port A are connected, so that the electromagnetic reversing valve can provide control oil to the control oil source inlet V port of motor brake I 42, motor brake II 52 and electro-hydraulic multi-way valve 7. The control oil source controls the opening and closing of motor brake I 42 and motor brake II 52 and the reversing control of each linkage of electro-hydraulic multi-way valve 7.

[0064] The oil supply source G of the return oil combination valve 9 provides oil supply to the oil supply inlet U of the travel pump assembly 4, thereby achieving the purpose of replenishing oil to travel pump I 31, travel pump II 32, travel motor I 41 and travel motor II 42.

[0065] Meanwhile, the return oil from port T of the electro-hydraulic multi-way valve 7, after being cooled by the radiator 8, enters port X of the return oil combination valve 9. After passing through port X, it enters the return oil filter 91 for filtration. At the same time, the return oil filter 91 is connected in parallel with the return oil filter bypass valve 92 to prevent the return oil filter from becoming clogged. The return oil after passing through the return oil filter 91 overflows through the return oil back pressure valve 93 and returns to the hydraulic oil tank 10.

[0066] 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 principle of the present invention, such as integrating the single-channel flow stabilizing valve on the working pump, or integrating the single-channel flow stabilizing valve with the solenoid directional valve, etc. These improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A hydraulic system for a skid steer loader, characterized in that, This includes a working pump, a single-channel flow stabilizing valve, a solenoid directional valve, an electro-hydraulic multi-way valve, and a return oil combination valve; The suction port of the working pump is connected to the hydraulic oil tank, the outlet port of the working pump is connected to the inlet of the single-channel flow stabilizing valve, and the outlet of the single-channel flow stabilizing valve is connected to the solenoid directional valve and the electro-hydraulic multi-way valve. The single-channel flow stabilizing valve is used to output a stable control oil source, supply oil to the solenoid directional valve, and provide oil to the inlet of the electro-hydraulic multi-way valve; the single-channel flow stabilizing valve includes a sequence valve and a relief valve; the outlet of the working pump is connected to the inlet E port of the single-channel flow stabilizing valve, the outlet F port of the single-channel flow stabilizing valve is connected to the inlet P1 port of the solenoid directional valve; the C port of the sequence valve is connected to the inlet P port of the electro-hydraulic multi-way valve, and the D port of the relief valve is connected to the hydraulic oil tank; The electromagnetic reversing valve is connected to the motor brake and electro-hydraulic multi-way valve of the skid steer loader. The electromagnetic reversing valve is used to provide control oil to the motor brake and the electro-hydraulic multi-way valve, control the on / off state of the motor brake, and control the reversing of each action of the electro-hydraulic multi-way valve. The working port of the electro-hydraulic multi-way valve is connected to the actuator of the skid steer loader and is used to control the operation of the actuator. The return port of the electro-hydraulic multi-way valve is connected to the inlet of the return combination valve, the outlet of the return combination valve is connected back to the hydraulic oil tank, and the replenishment oil source port of the return combination valve is connected to the replenishment oil inlet of the travel pump assembly of the skid steer loader.

2. The hydraulic system for a skid steer loader according to claim 1, characterized in that, The overflow valve is set to a pressure of 2.1 MPa.

3. The hydraulic system for a skid steer loader according to claim 1, characterized in that, The working oil port A of the electromagnetic reversing valve is connected to the brake control port of the motor brake of the skid steer loader and the control oil source inlet of the electro-hydraulic multi-way valve, and the return oil port of the electromagnetic reversing valve is connected to the hydraulic oil tank. The motor brake of the skid steer loader is connected to the travel motor, and the oil inlet and outlet of the travel motor are connected to the travel pump to form a closed loop. The travel pump and the working pump are connected in series through a connecting shaft and directly connected to the power source of the skid steer loader.

4. The hydraulic system for a skid steer loader according to claim 1, characterized in that, The control oil return port L of the electro-hydraulic multi-way valve is connected to the hydraulic oil tank, and the working oil port of the electro-hydraulic multi-way valve is connected to the sliding loading actuator.

5. A skid steer loader hydraulic system according to claim 3, characterized in that, The hydraulic system also includes a radiator. The return port T of the electro-hydraulic multi-way valve is connected to the inlet M of the radiator, the outlet K of the radiator is connected to the inlet X of the return combination valve, the outlet Y of the return combination valve is connected to the hydraulic oil tank, and the replenishment oil source port G of the return combination valve is connected to the replenishment oil inlet U of the travel pump.

6. A skid steer loader hydraulic system according to claim 5, characterized in that, The oil return combination valve includes an oil return filter, an oil return filter bypass valve, and an oil return back pressure valve, wherein the oil return filter and the oil return filter bypass valve are connected in parallel.

7. A skid steer loader hydraulic system according to claim 6, characterized in that, The back pressure valve for oil return is set at 0.8 MPa.

8. A method for providing a control oil source and a replenishment oil source for a skid steer loader hydraulic system according to any one of claims 1 to 7, characterized in that, include: Start the vehicle engine; Oil is drawn from the hydraulic tank by the working pump and introduced into the inlet E port of the single-channel flow stabilizing valve; One oil source passes through a sequence valve and a relief valve, outputting a stable control oil source to the outlet F port of the single-flow stabilizing valve, and supplying oil to the solenoid directional valve; another oil source provides oil to the inlet P port of the electro-hydraulic multi-way valve through the C port of the sequence valve. The inlet P1 of the electromagnetic directional valve is connected to the working port A, and the electromagnetic directional valve provides control oil to the motor brake and the electro-hydraulic multi-way valve. Oil is supplied to the return oil combination valve through the return oil port T of the electro-hydraulic multi-way valve, and replenishment oil is supplied to the travel pump assembly through the replenishment oil source port G of the return oil combination valve.

9. A method for providing control oil source and replenishment oil source for a skid steer loader hydraulic system based on claim 6, characterized in that, include: Start the vehicle engine; Oil is drawn from the hydraulic tank by the working pump and introduced into the inlet E port of the single-channel flow stabilizing valve; One oil source passes through a sequence valve and a relief valve, outputting a stable control oil source to the outlet F port of the single-flow stabilizing valve, and supplying oil to the solenoid directional valve; another oil source provides oil to the inlet P port of the electro-hydraulic multi-way valve through the C port of the sequence valve. The inlet P1 of the electromagnetic directional valve is connected to the working port A, and the electromagnetic directional valve provides control oil to the motor brake and the electro-hydraulic multi-way valve. Oil is supplied to the return oil combination valve through the return oil port T of the electro-hydraulic multi-way valve, and replenishment oil is supplied to the travel pump assembly through the replenishment oil source port G of the return oil combination valve. The return oil from the T-port of the electro-hydraulic multi-way valve is cooled by the radiator and then enters the inlet X-port of the return oil combination valve. The returned oil, after being filtered by the return oil filter, overflows through the return oil back pressure valve and returns to the hydraulic oil tank through the outlet Y port of the return oil combination valve.

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