Walking anti-deviation valve group of skid loader, hydraulic system and skid loader

Abstract

The invention discloses a walking anti-deviation valve group of a skid loader, a hydraulic system and the skid loader. The walking anti-deviation valve group comprises an oil port x1-x4 used for detecting the walking state of the whole machine; the oil ports A1, B1, A2 and B2 are used for balancing the output pressure of the walking pump; an inlet of the shuttle valve I is connected with the oil ports x1 and x2, and an outlet of the shuttle valve I is connected with an oil port I of the reversing valve I; an inlet of the shuttle valve II is connected with the oil ports x3 and x4, and an outlet of the shuttle valve II is connected with a control oil port of the reversing valve I; an inlet of the shuttle valve III is connected with the oil ports A2 and B2, and an outlet of the shuttle valve III is connected with the oil port I of the reversing valve II; an inlet of the shuttle valve IV is connected with the oil ports A1 and B1, and an outlet of the shuttle valve IV is connected with an oil port II of the reversing valve II; a control oil port of the second reversing valve is connected with a third oil port of the first reversing valve. Under the condition that the original operation mode is not changed, the running working condition is automatically recognized, the pressure of the left and right walking motors is balanced, and the problem of linear running deviation caused by the load difference of the left and right wheel sides is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of small loading machinery, and particularly relates to a skid steer loader running anti-deviation valve group, a hydraulic system and a skid steer loader. Background Art

[0002] A skid steer loader is a small multi-functional construction machinery, which realizes the running and steering of the whole machine by the wheels or tracks on the left and right sides rotating at different speeds and directions. With its flexibility and versatility, the skid steer loader has become an indispensable equipment in modern construction machinery.

[0003] Generally, the running system of a skid steer loader adopts a hydrostatic running drive scheme of two pumps and two motors, and the hydraulically controlled variable pump with DA control (speed sensing control) is most widely used. A remarkable feature of the DA pump is that the swash plate will automatically swing back after the system pressure rises to perform power control and prevent the engine from stalling.

[0004] Based on the above skid steer running system principle, when the whole machine is running straight, due to factors such as the distribution of the whole machine's center of gravity, tire tire pressure, track tension difference and ground difference, the loads on the left and right motors are different. Furthermore, the system pressures of the left and right motors are different during straight running. Further, the swash plate swing-back angles of the DA pump are different, resulting in a difference in the instantaneous displacement of the DA pump, and finally the rotational speeds of the left and right running motors are inconsistent, resulting in a running deviation problem and affecting the operation efficiency. Summary of the Invention

[0005] In order to solve the deficiencies in the prior art, the invention provides a skid steer loader running anti-deviation valve group, a hydraulic system and a skid steer loader, which can automatically identify the forward or backward straight running working conditions without changing the original operation mode, and balance the running pressures of the left and right running motors, so as to solve the straight running deviation problem caused by the difference in the loads on the left and right wheel ends.

[0006] The technical solution adopted by the invention to achieve the above purpose is as follows: In a first aspect, a skid steer loader travel anti-deviation valve group is provided, including: oil ports x1, x2, x3, and x4 for detecting the travel state of the whole machine; oil ports A1, B1, A2, and B2 for balancing the output pressures of the left travel pump and the right travel pump; two inlets of shuttle valve 1 are respectively connected to oil ports x1 and x2, and the outlet of shuttle valve 1 is connected to oil port 1 of directional valve 1; two inlets of shuttle valve 2 are respectively connected to oil ports x3 and x4, and the outlet of shuttle valve 2 is connected to the control oil port of directional valve 1; two inlets of shuttle valve 3 are respectively connected to oil ports A2 and B2, and the outlet of shuttle valve 3 is connected to oil port 1 of directional valve 2; two inlets of shuttle valve 4 are respectively connected to oil ports A1 and B1, and the outlet of shuttle valve 4 is connected to oil port 2 of directional valve 2; the control oil port of directional valve 2 is connected to oil port 3 of directional valve 1.

[0007] Further, oil port 2 of directional valve 1 is connected to the return oil port T1.

[0008] Further, oil ports x1, x2, x3, and x4 are respectively used to connect to the outlets of the rear, front, left, and right pressure reducing valves in the travel pilot valve; when the whole machine is only moving forward in a straight line, the front pressure reducing valve in the travel pilot valve outputs a pressure oil signal, and there is a pressure oil signal input to oil port x2; when the whole machine is only moving backward in a straight line, the rear pressure reducing valve in the travel pilot valve outputs a pressure oil signal, and there is a pressure oil signal input to oil port x1; when the whole machine is only turning left in place, the left pressure reducing valve in the travel pilot valve outputs a pressure oil signal, and there is a pressure oil signal input to oil port x3; when the whole machine is only turning right in place, the right pressure reducing valve in the travel pilot valve outputs a pressure oil signal, and there is a pressure oil signal input to oil port x4; when the whole machine is turning during travel, the front, rear pressure reducing valves and the left, right pressure reducing valves in the travel pilot valve will output pressure oil signals in combination.

[0009] Further, when there is a pressure oil signal input to oil port x3 or oil port x4, directional valve 1 works in the right position, and oil port 2 and oil port 3 of directional valve 1 are connected; otherwise, directional valve 1 works in the left position, and oil port 1 and oil port 3 of directional valve 1 are connected.

[0010] Further, oil ports A1, B1, A2, and B2 are respectively used to connect to the oil ports P - A1, P - B1 of the left travel pump and the oil ports P - A2, P - B2 of the right travel pump.

[0011] In a second aspect, a skid steer loader hydraulic system is provided, and the skid steer loader hydraulic system is configured with the skid steer loader travel anti-deviation valve group described in the first aspect.

[0012] Further, when the whole machine is performing a straight-line driving condition, pressure oil is input into one of the oil ports x1 and x2, and no pressure oil is input into the oil ports x3 and x4. The first reversing valve works in the left position; the pressure oil in the oil port x1 or x2 enters the control oil port of the second reversing valve through the first reversing valve, and the second reversing valve works in the upper position. The left travel pump and the right travel pump are connected through the damping passage in the second reversing valve to balance the output pressures of the left travel pump and the right travel pump.

[0013] Further, when the whole machine is performing a turning condition, pressure oil is input into one of the oil ports x3 and x4, and the first reversing valve works in the right position; the control oil port of the second reversing valve is connected to the oil return port T1 through the first reversing valve, and the second reversing valve works in the lower position. The left travel pump and the right travel pump are cut off at the second reversing valve and are not connected.

[0014] In a third aspect, a skid steer loader is provided, and the skid steer loader is configured with the skid steer loader hydraulic system described in the second aspect.

[0015] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: (1) The walking anti-deviation valve group of the present invention adopts a full hydraulic control scheme. By setting shuttle valves 1 to 4 and reversing valves 1 to 2, and automatically detecting the walking state of the whole machine through the oil ports x1 to x4, and balancing the output pressures of the left and right travel pumps through the oil ports A1, B1, A2, and B2, the problem of straight-line driving deviation caused by inconsistent loads of the left and right walking systems is solved without changing the structure and function of the existing components. (2) The steering of the skid steer loader is achieved by the difference in the wheel linear velocities. Without changing the existing operating habits, the present invention not only realizes the steering control at any time but also realizes the straight-line walking control. (3) Compared with the scheme of using a speed sensor, a pressure sensor, and a controller for electric control walking, the anti-deviation valve group proposed by the present invention has a lower cost and better system compatibility, and has a cost advantage. Description of the Drawings

[0016] Figure 1 is a schematic diagram of the working principle of a walking anti-deviation valve group of a skid steer loader provided by an embodiment of the present invention; Figure 2 is a schematic diagram of the working principle of a skid steer loader hydraulic system provided by an embodiment of the present invention; In the figure: 1. Walking anti-deviation valve group; 2. Walking pilot valve; 3. Pilot oil source; 4. Travel pump; 5. Left travel motor; 6. Right travel motor; 7. Fuel tank; 11. First reversing valve; 12. Second reversing valve; 13. First shuttle valve; 14. Second shuttle valve; 15. Third shuttle valve; 16. Fourth shuttle valve. Detailed Embodiments

[0017] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention and cannot be used to limit the protection scope of the present invention.

[0018] Embodiment 1 As Figure 1 shown, a skid steer loader anti-deviation valve group for walking includes: oil ports x1, x2, x3, and x4 for detecting the walking state of the whole machine; oil ports A1, B1, A2, and B2 for balancing the output pressures of the left and right walking pumps; two inlets of shuttle valve 13 are respectively connected to oil ports x1 and x2, and the outlet of shuttle valve 13 is connected to oil port 1 of directional valve 11; two inlets of shuttle valve 14 are respectively connected to oil ports x3 and x4, and the outlet of shuttle valve 14 is connected to the control oil port of directional valve 11; two inlets of shuttle valve 15 are respectively connected to oil ports A2 and B2, and the outlet of shuttle valve 15 is connected to oil port 1 of directional valve 12; two inlets of shuttle valve 16 are respectively connected to oil ports A1 and B1, and the outlet of shuttle valve 16 is connected to oil port 2 of directional valve 12; the control oil port of directional valve 12 is connected to oil port 3 of directional valve 11; oil port 2 of directional valve 11 is connected to return oil port T1. Directional valve 11 is a two-position three-way directional valve; directional valve 12 is a two-position two-way directional valve.

[0019] As Figure 1 、 Figure 2 shown, oil ports x1, x2, x3, and x4 are respectively connected to the output ports of the rear, front, left, and right pressure reducing valves in the walking pilot valve 2 for detecting the walking state of the whole machine. Oil ports A1, B1, A2, and B2 are respectively connected to the pump oil ports P-A1, P-B1 of the left walking system and the pump oil ports P-A2, P-B2 of the right walking system, and are also connected to the motor oil ports M-A1, M-B1 of the left walking system and the motor oil ports M-A2, M-B2 of the right walking system. Return oil port T1 is connected to the fuel tank 7.

[0020] The first reversing valve 11 is connected to the outlet of the first shuttle valve 13 through the first oil port, connected to the oil return port T1 through the second oil port, and connected to the upper end of the second reversing valve 12 through the third oil port; a spring is provided at the left end of the first reversing valve 11, and a control oil port is provided at the right end, which is connected to the outlet of the second shuttle valve 14; the first reversing valve 11 is provided with a left working position and a right working position. When there is no pressure signal at the right end of the first reversing valve 11, under the action of the spring force, the first reversing valve 11 works in the left position. At this time, the outlet of the first shuttle valve 13 is communicated with the third oil port through the first oil port of the first reversing valve 11 and acts on the upper end of the second reversing valve 12, and the oil return port T1 is cut off at the second oil port of the first reversing valve 11; when there is a pressure signal at the right end of the first reversing valve 11, the first reversing valve 11 works in the right position. At this time, the outlet of the first shuttle valve 13 is cut off at the first oil port of the reversing valve, and the control oil signal at the upper end of the second reversing valve 12 is communicated with the second oil port through the third oil port of the first reversing valve 11 and is communicated with the oil return port T1 of the first reversing valve 11.

[0021] The second reversing valve 12 is connected to the outlet of the third shuttle valve 15 through the first oil port and connected to the outlet of the fourth shuttle valve 16 through the second oil port; a spring is provided below the second reversing valve 12, and a control oil port is provided above, which is connected to the third oil port of the first reversing valve 11; the second reversing valve 12 is provided with an upper working position and a lower working position. When there is no pressure signal at the upper end of the second reversing valve 12, under the action of the spring force, the second reversing valve 12 works in the lower position, the outlet of the third shuttle valve 15 is cut off at the first oil port of the second reversing valve 12, and the outlet of the fourth shuttle valve 16 is cut off at the second oil port of the second reversing valve 12; when there is a pressure signal at the upper end of the second reversing valve 12, the second reversing valve 12 works in the upper position, the outlet of the third shuttle valve 15 is communicated with the first oil port of the second reversing valve 12 and is communicated with the second oil port through the damping channel in the upper position of the second reversing valve 12, and the second oil port is communicated with the outlet of the fourth shuttle valve 16.

[0022] Embodiment 2 Based on the anti-deviation valve group for the walking of a skid steer loader described in Embodiment 1, this embodiment provides a hydraulic system for a skid steer loader, as Figure 2 shown, which includes the anti-deviation valve group 1 for walking described in Embodiment 1, and also includes: a walking pilot valve 2, a pilot oil source 3, a walking pump 4 (including a left walking pump and a right walking pump), a left walking motor 5, a right walking motor 6, and a hydraulic oil tank 7.

[0023] The oil ports x1, x2, x3, and x4 are respectively connected to the outlets of the four pressure reducing valves at the rear, front, left, and right in the travel pilot valve 2, and are used to detect the travel state of the whole machine. When the whole machine is moving forward in a straight line, the front pressure reducing valve in the travel pilot valve 2 outputs a pressure oil signal, and there is a pressure oil signal input at the oil port x2 of the travel anti-deviation valve group 1. When the whole machine is moving backward in a straight line, the rear pressure reducing valve in the travel pilot valve 2 outputs a pressure oil signal, and there is a pressure oil signal input at the oil port x1 of the travel anti-deviation valve group 1. When the whole machine is turning left in place, the left pressure reducing valve in the travel pilot valve 2 outputs a pressure oil signal, and there is a pressure oil signal input at the oil port x3 of the travel anti-deviation valve group 1. When the whole machine is turning right in place, the right pressure reducing valve in the travel pilot valve 2 outputs a pressure oil signal, and there is a pressure oil signal input at the oil port x4 of the travel anti-deviation valve group 1. When the whole machine is turning during travel, the front and rear pressure reducing valves and the left and right pressure reducing valves in the travel pilot valve 2 will output pressure oil signals simultaneously. For example, when turning left during travel, the front and left pressure reducing valves in the travel pilot valve 2 will output pressure oil signals simultaneously, and there are pressure oil signal inputs at the oil ports x2 and x3 of the travel anti-deviation valve group 1.

[0024] The inlet P of the travel pilot valve 2 is connected to the pilot oil source 3, and the oil return port T of the travel pilot valve 2 and the oil return port T1 of the travel anti-deviation valve group 1 are both connected to the fuel tank 7. The four oil outlets of the travel pilot valve 2 are connected to the control oil ports c1, c2, c3, and c4 of the travel pump 4, corresponding to the left travel motor backward, the right travel motor forward, the right travel motor backward, and the left travel motor forward respectively.

[0025] When the whole machine is performing a straight-line travel working condition, only the front and rear two pressure reducing valves in the travel pilot valve 2 have pressure output, and it is impossible to have pressure output simultaneously (that is, there is pressure oil input at one of the oil ports x1 and x2), and the left and right two pressure reducing valves in the travel pilot valve 2 have no pressure output (that is, there is no pressure oil input at both the oil ports x3 and x4). Correspondingly, at this time, the shuttle valve 13 in the travel anti-deviation valve group 1 has pressure oil output, and the shuttle valve 14 has no pressure oil output. Correspondingly, at this time, the directional valve 11 in the travel anti-deviation valve group 1 works in the left position, and the forward or backward pressure oil signal of the travel pilot valve 2 acts on the upper part of the directional valve 12 through the directional valve 11. Correspondingly, at this time, the directional valve 12 in the travel anti-deviation valve group 1 works in the upper position, and the pressures of the left travel system and the right travel system are connected through the damping channels in the directional valve 12 for pressure balance to ensure that the pressures of the left and right travel systems are the same. Correspondingly, the displacement of the travel pump 4 will not be different due to load differences, and the output flow rates of the left and right travel systems can be ensured to be the same, so that the rotational speeds of the left and right travel motors are the same, avoiding straight-line deviation.

[0026] When the whole machine is in the turning condition, there must be pressure output from either the left or right pressure reducing valve in the travel pilot valve 2, and it is impossible to have pressure output simultaneously (i.e., pressure oil is input into one of the oil ports x3 and x4). Correspondingly, at this time, there is pressure oil output from the shuttle valve II 14 in the travel anti-deviation valve group 1; Correspondingly, at this time, the first reversing valve 11 in the travel anti-deviation valve group 1 works in the right position, and the forward or reverse pressure oil signal of the travel pilot valve 2 is cut off at the first reversing valve 11; Correspondingly, at this time, the control oil signal at the upper position of the second reversing valve 12 in the travel anti-deviation valve group 1 is connected to the oil return port T1 through the first reversing valve 11. Under the action of the spring force, the second reversing valve 12 works in the lower position, the pressure of the left travel system is cut off at the second oil port of the second reversing valve 12, the pressure of the right travel system is cut off at the first oil port of the second reversing valve 12, and the pressures of the left and right travel systems are not connected, so it will not affect the normal steering function of the skid steer loader.

[0027] In summary, for the hydrostatic travel system of the skid steer loader, the present invention adopts a fully hydraulic control travel anti-deviation valve group to automatically detect the travel state for pressure balance without changing the structure and function of the existing components. It can solve the problem of straight-line travel deviation caused by inconsistent loads of the left and right travel systems. Without changing the existing operation habits, the present invention not only realizes the steering control at any time but also realizes the straight-line travel control.

[0028] Embodiment III Based on the travel anti-deviation valve group of a skid steer loader described in Embodiment I and the hydraulic system of a skid steer loader described in Embodiment II, this embodiment provides a skid steer loader, which is configured with the hydraulic system of a skid steer loader described in Embodiment II or the travel anti-deviation valve group of a skid steer loader described in Embodiment I.

[0029] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and deformations can be made, and these improvements and deformations should also be regarded as the protection scope of the present invention.

Claims

1. A skid loader anti-slip valve assembly, characterized in that: include: Oil ports x1, x2, x3 and x4 for detecting the running status of the whole machine; Oil ports A1, B1, A2 and B2 for balancing the output pressure of the left travel pump and the right travel pump; The two inlets of shuttle valve 1 (13) are connected to oil port x1 and oil port x2 respectively, and the outlet of shuttle valve 1 (13) is connected to oil port 1 of reversing valve 1 (11); The two inlets of shuttle valve 2 (14) are connected to oil port x3 and oil port x4 respectively, and the outlet of shuttle valve 2 (14) is connected to the control oil port of reversing valve 1 (11); The two inlets of shuttle valve 3 (15) are connected to oil port A2 and oil port B2 respectively, and the outlet of shuttle valve 3 (15) is connected to oil port 1 of reversing valve 2 (12); The two inlets of shuttle valve 4 (16) are connected to oil port A1 and oil port B1 respectively, and the outlet of shuttle valve 4 (16) is connected to oil port 2 of reversing valve 2 (12); The control oil port of the second reversing valve (12) is connected to the oil port 3 of the first reversing valve (11).

2. The anti-slip valve assembly for skid loader according to claim 1, characterized in that: The oil port 2 of the reversing valve 1 (11) is connected to the oil return port T1.

3. The anti-slip valve assembly for skid loader according to claim 1, characterized in that: Oil port x1, oil port x2, oil port x3 and oil port x4 are used to connect the outlets of the four pressure reducing valves at the rear, front, left and right of the travel pilot valve (2) respectively; When the whole machine is only moving forward in a straight line, the front pressure reducing valve in the travel pilot valve (2) outputs a pressure oil signal, and the oil port x2 has a pressure oil signal input; when the whole machine is only moving backward in a straight line, the rear pressure reducing valve in the travel pilot valve (2) outputs a pressure oil signal, and the oil port x1 has a pressure oil signal input; When the whole machine only turns left on the spot, the left pressure reducing valve in the travel pilot valve (2) outputs a pressure oil signal, and the oil port x3 has a pressure oil signal input; when the whole machine only turns right on the spot, the right pressure reducing valve in the travel pilot valve (2) outputs a pressure oil signal, and the oil port x4 has a pressure oil signal input; When the machine turns while traveling, the front and rear pressure reducing valves and the left and right pressure reducing valves in the travel pilot valve (2) will combine to output pressure oil signals simultaneously.

4. The anti-slip valve assembly for skid loader according to claim 1, characterized in that: When a pressure oil signal is input to the oil port x3 or the oil port x4, the reversing valve 1 (11) works in the right position, and the oil port 2 of the reversing valve 1 (11) is connected to the oil port 3; otherwise, the reversing valve 1 (11) works in the left position, and the oil port 1 of the reversing valve 1 (11) is connected to the oil port 3.

5. The anti-slip valve assembly for skid loader according to claim 1, characterized in that: Oil port A1, oil port B1, oil port A2 and oil port B2 are used to connect the oil port P-A1, oil port P-B1 of the left travel pump and the oil port P-A2, oil port P-B2 of the right travel pump respectively.

6. A hydraulic system for a skid loader, characterized in that: The skid loader hydraulic system is equipped with a skid loader anti-drifting valve group according to any one of claims 1 to 5.

7. The anti-slip valve assembly for skid loader according to claim 6, characterized in that: When the whole machine is in a straight-line driving condition, one of the oil ports x1 and x2 has pressure oil input, and neither the oil port x3 nor the oil port x4 has pressure oil input, and the reversing valve 1 (11) works in the left position; the pressure oil in the oil port x1 or the oil port x2 enters the control oil port of the reversing valve 2 (12) through the reversing valve 1 (11), and the reversing valve 2 (12) works in the upper position. The left travel pump and the right travel pump are connected through the damping channel in the reversing valve 2 (12) to balance the output pressures of the left travel pump and the right travel pump.

8. The anti-slip valve assembly for skid loader according to claim 6, characterized in that: When the whole machine is performing a turning operation, pressure oil is input to one of the oil ports x3 and x4, and the reversing valve 1 (11) works in the right position; the control oil port of the reversing valve 2 (12) is connected to the oil return port T1 through the reversing valve 1 (11), and the reversing valve 2 (12) works in the lower position. The left travel pump and the right travel pump are cut off at the reversing valve 2 (12) and are not connected.

9. A skid steer loader, characterized in that: The skid steer loader is equipped with the skid steer loader hydraulic system according to any one of claims 6 to 8.

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