A loader steering hydraulic system, control method, and loader

Abstract

The present application belongs to the technical field of hydraulic control, and particularly relates to a loader steering hydraulic system, a control method and a loader. The loader steering hydraulic system comprises a steering gear, a steering cylinder and a steering pump connected with an oil tank, and further comprises a flow amplification valve, a pilot oil source valve, a cut-off valve and a proportional solenoid valve. The oil outlet of the steering pump is connected with the P port of the flow amplification valve and the P port of the pilot oil source valve. The L port and the R port of the steering gear are connected with the a port and the b port of the flow amplification valve respectively, and the L port and the R port of the proportional solenoid valve are connected with the a port and the b port of the flow amplification valve respectively. The present application can control the steering cylinder when the steering gear is stuck, so as to ensure the steering reliability and safety of the loader.

Description

Technical Field

[0001] This invention belongs to the field of hydraulic control technology, specifically relating to a loader steering hydraulic system, control method, and loader. Background Technology

[0002] Loaders are traditional engineering machinery widely used in industries such as construction and forestry. Currently, most loader steering hydraulic systems use steering gears for steering. However, these steering gears often experience malfunctions such as jamming during operation, affecting the reliability and safety of the loader's steering. Summary of the Invention

[0003] The purpose of this invention is to provide a loader steering hydraulic system, control method, and loader. By setting a pilot oil source valve, a shut-off valve, and a proportional solenoid valve, the steering cylinder can still be controlled when the steering gear jams, thereby ensuring the reliability and safety of the loader steering.

[0004] The present invention provides a solution using the following technical method:

[0005] In a first aspect, the present invention provides a loader steering hydraulic system, including a steering gear, a steering cylinder, and a steering pump connected to an oil tank, characterized in that it further includes a flow amplification valve, a pilot oil source valve, a shut-off valve, and a proportional solenoid valve; the oil outlet of the steering pump is connected to both the P port of the flow amplification valve and the P port of the pilot oil source valve; the P port of the shut-off valve is connected to the U port of the pilot oil source valve; the A port and B port of the shut-off valve are respectively connected to the P port of the proportional solenoid valve and the P port of the steering gear; the L port and R port of the steering gear are respectively connected to the a port and b port of the flow amplification valve; the T port of the steering gear is connected to the oil tank; the L port and R port of the proportional solenoid valve are respectively connected to the a port and b port of the flow amplification valve; and the T port of the flow amplification valve is connected to the oil tank.

[0006] When the flow amplification valve is acted upon by hydraulic oil at port a, the flow amplification valve outputs hydraulic oil to the steering cylinder to achieve left steering; when the flow amplification valve is acted upon by hydraulic oil at port b, the flow amplification valve outputs hydraulic oil to the steering cylinder to achieve right steering; the shut-off valve includes a left position and a right position. When the shut-off valve is in the right position, its port P is connected to its port B; when the shut-off valve is in the left position, its port P is connected to both its ports A and B.

[0007] Optionally, the switching of the shut-off valve is controlled by a solenoid valve.

[0008] Optionally, the proportional solenoid valve includes a left position, a middle position, and a right position; the switching of the proportional solenoid valve is controlled by a solenoid valve; when the proportional solenoid valve is in the left position, the P port and L port of the proportional solenoid valve are connected, and the R port and T port of the proportional solenoid valve are connected; when the proportional solenoid valve is in the middle position, the P port of the proportional solenoid valve is cut off; when the proportional solenoid valve is in the right position, the P port and R port of the proportional solenoid valve are connected, and the L port and T port of the proportional solenoid valve are connected.

[0009] Optionally, the flow amplification valve includes a flow divider valve core and a flow amplification valve core; the flow divider valve core includes a first oil port, a second oil port and a third oil port, and the flow amplification valve core includes a first oil inlet, a first oil return port, a first working oil port and a second working oil port;

[0010] The flow divider valve core has a first oil port connected to the steering pump, a second oil port connected to the first oil inlet of the flow amplification valve core, and a third oil port for connecting to other external systems; the flow divider valve core includes a left position, a middle position, and a right position.

[0011] The flow amplification valve core has a first return port connected to the oil tank, a first working port connected to port A of the flow amplification valve through a first oil circuit, and a second working port connected to port B of the flow amplification valve through a second oil circuit.

[0012] When the flow divider valve core is in the left position, the first oil port and the second oil port of the flow divider valve core are connected.

[0013] The flow divider valve core is in the neutral position, and the first oil port of the flow divider valve core is connected to both the second and third oil ports; a damper is provided in the oil passage between the first and third oil ports.

[0014] When the diversion valve core is in the right position, the first oil port of the diversion valve core is connected to the second oil port and the third oil port; a damper is provided in the oil line between the first oil port and the second oil port.

[0015] Optionally, it also includes:

[0016] The shuttle valve has two inlets connected to the first oil circuit and the second oil circuit respectively; the outlet of the shuttle valve is connected to the return oil circuit between the first return port and the oil tank via a third oil circuit.

[0017] An overflow valve is located on the third oil line;

[0018] The left end of the diverter valve core is connected to the third oil line and is located upstream of the overflow valve. The left end of the diverter valve core is also provided with a reset spring. The right end of the diverter valve core is connected between the second oil port of the diverter valve core and the first oil port of the flow amplification valve core.

[0019] Optionally, the flow amplification valve core includes a left position, a middle position, and a right position, with the left end of the flow amplification valve core connected to port a of the flow amplification valve and the right end of the flow amplification valve core connected to port b of the flow amplification valve.

[0020] When the flow amplification valve core is in the left position, the first oil inlet and the first oil return port of the flow amplification valve core are connected to the first working oil port and the second working oil port, respectively.

[0021] When the flow amplification valve core is in the neutral position, the first oil inlet and the first oil return port of the flow amplification valve core are cut off.

[0022] When the flow amplification valve core is in the right position, the first oil inlet and the first oil return port of the flow amplification valve core are connected to the second working oil port and the first working oil port, respectively.

[0023] Optionally, it also includes:

[0024] The buffer valve includes a left relief valve, a right relief valve, a left check valve, a right check valve, and a control valve;

[0025] A fourth and a fifth oil circuit are connected in parallel between the first and second oil circuits; the left and right relief valves are arranged in opposite flow directions on the fourth oil circuit, and the left and right check valves are arranged in opposite flow directions on the fifth oil circuit; the inlet of the control valve is connected between the left and right relief valves, and the outlet of the control valve is connected between the left and right check valves; the left end of the control valve is connected to the connecting oil circuit between the left relief valve and the left check valve, and the right end of the control valve is connected to the connecting oil circuit between the right relief valve and the right check valve.

[0026] Secondly, the present invention provides a control method for a loader steering hydraulic system, which is based on the aforementioned loader steering hydraulic system and includes:

[0027] In response to the right turn control signal:

[0028] If the R port output pressure of the steering gear is greater than a preset threshold, the P port of the shut-off valve is controlled to be connected only to the B port, and the P port of the proportional solenoid valve is cut off; the hydraulic oil output from the R port of the steering gear acts on the b port of the flow amplification valve, so that the hydraulic oil output from the B port of the flow amplification valve is connected to the steering cylinder to realize right turn.

[0029] If the output pressure at port R of the steering gear is less than a preset threshold, the P port, A port, and B port of the shut-off valve are all connected, and the P port and R port of the proportional solenoid valve are connected; the hydraulic oil output from port R of the proportional solenoid valve acts on port b of the flow amplification valve, so that the hydraulic oil output from port B of the flow amplification valve is connected to the steering cylinder to achieve right steering.

[0030] In response to the left turn control signal,

[0031] If the output pressure at port L of the steering gear is greater than a preset threshold, the P port of the shut-off valve is controlled to connect only to port B, and the P port of the proportional solenoid valve is shut off; the hydraulic oil output from port L of the steering gear acts on port a of the flow amplification valve, so that the hydraulic oil output from port A of the flow amplification valve is sent to the steering cylinder to achieve left steering;

[0032] If the output pressure at port L of the steering gear is less than a preset threshold, the P port, A port, and B port of the shut-off valve are all connected, and the P port and L port of the proportional solenoid valve are connected. The hydraulic oil output from port L of the proportional solenoid valve acts on port a of the flow amplification valve, so that the hydraulic oil output from port A of the flow amplification valve is connected to the steering cylinder to achieve right steering.

[0033] Optionally, a pressure sensor is provided at the L port of the steering gear, and a pressure sensor is provided at the R port of the steering gear.

[0034] Thirdly, the present invention provides a loader that includes the aforementioned loader steering hydraulic system.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] 1. Compared with conventional loader steering hydraulic systems, the steering hydraulic system and control method proposed in this invention can improve the reliability and safety of the loader steering hydraulic system by switching the cut-off valve so that the pilot oil source valve can still control the flow amplification valve through the proportional solenoid valve when the steering gear fails due to jamming.

[0037] 2. The auxiliary valve arranged inside the flow amplification valve of this invention can relieve pressure to the low-pressure side when the oil outlet of the flow amplification valve is high due to steering load, so as to effectively reduce the steering impact when the loader suddenly changes direction and improve the steering stability of the loader. At the same time, the shuttle valve, together with the relief valve, can also switch the flow amplification valve core when the oil outlet of the flow amplification valve is high, so as to reduce the oil pressure by returning oil, and divert the hydraulic oil output by the hydraulic pump to other systems through the third oil port of the flow amplification valve core to protect the oil circuit. Attached Figure Description

[0038] Figure 1This is a schematic diagram of the hydraulic system in Example 1.

[0039] The diagram labels are as follows: 1. Steering pump; 2. Steering gear; 3. Flow amplification valve; 31. Relief valve; 31. Divider valve core; 33. Flow amplification valve core; 34. Shuttle valve; 35. Buffer valve; 351. Left relief valve; 352. Right relief valve; 353. Control valve; 354. Left check valve; 355. Right check valve; 356. Left damper; 357. Right damper; 4. Shut-off valve; 5. Proportional solenoid valve; 6. Steering cylinder; 7. Electric control lever; 8. Pilot oil supply valve; 81. Pressure reducing valve core; 82. Filter element; 91. Pressure sensor one; 92. Pressure sensor two; 10. Controller. Detailed Implementation

[0040] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are used only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more. In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0041] 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. Example

[0042] from Figure 1This embodiment provides a loader steering hydraulic system, including a steering gear 2, a steering cylinder 6, and a steering pump 1 connected to an oil tank. It also includes a flow amplification valve 3, a pilot oil source valve 8, a shut-off valve 4, and a proportional solenoid valve 5. The oil outlet of the steering pump 1 is connected to both the P port of the flow amplification valve 3 and the P port of the pilot oil source valve 8. The P port of the shut-off valve 4 is connected to the U port of the pilot oil source valve 8. The A and B ports of the shut-off valve 4 are respectively connected to the P port of the proportional solenoid valve 5 and the P port of the steering gear 2. The L and R ports of the steering gear 2 are respectively connected to the a and b ports of the flow amplification valve 3. The T port of the steering gear 2 is connected to the oil tank. The L and R ports of the proportional solenoid valve 5 are respectively connected to the a and b ports of the flow amplification valve 3.

[0043] When the flow amplification valve 3 is acted upon by hydraulic oil, the flow amplification valve 3 outputs hydraulic oil to the steering cylinder 6 to achieve left steering; when the flow amplification valve 3 is acted upon by hydraulic oil, the flow amplification valve 3 outputs hydraulic oil to the steering cylinder 6 to achieve right steering; the hydraulic oil driving the steering cylinder 6 to turn is common knowledge in the art and will not be described in detail here.

[0044] The shut-off valve 4 includes a left position and a right position. When the shut-off valve 4 is in the right position, its P port is connected to its B port. When turning left, in response to the L port pressure value of the steering gear 2 being 0, or when turning right, in response to the R port pressure value of the steering gear 2 being 0, the shut-off valve 4 switches to the left position, and its P port is connected to both its A port and B port.

[0045] To explain the working principle, when the machine turns right, the steering wheel is turned to the right to send a right turn signal. The steering pump 1 draws hydraulic oil from the oil tank, and the hydraulic oil enters the inlet P of the pilot oil source valve 8. In a specific embodiment, the pilot oil source valve 8 is equipped with a pressure reducing valve core 81 and a filter element 82. The hydraulic oil is reduced in pressure by the pressure reducing valve core 81 and filtered by the filter element 82. The hydraulic oil enters the inlet P of the shut-off valve 4 through the outlet U of the pilot oil source valve 8 and passes through the B port of the shut-off valve 4 via the steering column below the steering wheel. The valve core of the steering gear 2 (not shown in the figure) enters the P port of the steering gear 2. The hydraulic oil passes through the inside of the steering gear 2 and enters the oil outlet R port of the steering gear 2, which is then output to the b port of the flow amplification valve 3. This allows the flow amplification valve 3 to output hydraulic oil through the B port to the steering cylinder 6 to achieve right turn. In a specific embodiment, after the hydraulic oil enters the b port of the flow amplification valve 3, it passes through the internal channel of the valve core, through the damping or throttling orifice, and reaches the steering oil port a port at the other end of the valve core. Then, it flows back to the hydraulic oil tank through the T port of the steering gear 2.

[0046] However, when the steering gear 2 valve core is stuck, causing the steering gear 2 to fail, the output pressure at the R port of the steering gear 2 is lower than a preset threshold when the steering wheel is turned. In a specific embodiment, the pressure at the R port of the steering gear 2 outlet is detected by a pressure sensor 91. Normally, when the steering gear 2 valve core is stuck, causing the steering gear 2 to fail, the pressure sensor 91 will not give a pressure signal. At this time, the controller 10 will issue an alarm signal and control the P port, B port, and A port of the shut-off valve 4 to be connected. The hydraulic oil flowing out of the U port of the pilot oil source valve 8 flows into the P port of the proportional solenoid valve 5 through the A port of the shut-off valve 4. The R port of the proportional solenoid valve 5 outputs hydraulic oil and acts on the b port of the flow amplification valve 3, so that the B port of the flow amplification valve 3 outputs hydraulic oil to the steering cylinder 6 to achieve right steering, thereby enabling reliable and stable steering even when the steering gear 2 valve core is stuck and causes the steering gear 2 to fail.

[0047] In one specific embodiment, the shut-off valve 4 includes a left position and a right position, and the switching of the shut-off valve 4 is controlled by a solenoid valve. When the shut-off valve 4 is in the left position, its P port is connected to both its A port and its B port. When the shut-off valve 4 is in the right position, its P port is connected to its B port. The proportional solenoid valve 5 includes a left position, a middle position, and a right position. The switching of the proportional solenoid valve 5 is controlled by a solenoid valve. When the proportional solenoid valve 5 is in the left position, its P port and L port are connected, and its R port and T port are connected. When the proportional solenoid valve 5 is in the middle position, its P port is closed. When the proportional solenoid valve 5 is in the right position, its P port and R port are connected, and its L port and T port are connected.

[0048] In actual operation, the controller 10 receives pressure signals from the L and R ports of the steering gear 2. Based on the pressure signals, the controller 10 controls the operating positions of the shut-off valve 4 and the proportional solenoid valve 5 via the solenoid valve. The working principle is the same as above and will not be elaborated here. Of course, in addition to solenoid valve control, other hydraulic controls with the same function can also be used, as long as the hydraulic oil flow direction is the same.

[0049] The above explanation uses right turns as an example. In the case of left turns, the L port of steering gear 2 or the L port of proportional solenoid valve 5 outputs hydraulic oil, which ultimately acts on port a of flow amplification valve 3. This causes port A of flow amplification valve 3 to output hydraulic oil to steering cylinder 6, thus achieving left turn. After entering port a of flow amplification valve 3, the hydraulic oil passes through the internal channel of the valve core to the steering oil port b at the other end of the valve core, and then flows back to the hydraulic oil tank through port T of steering gear 2. The working principle is the same as for right turns and will not be repeated here.

[0050] Further, the flow amplification valve 3 is described above. Ports a and b of the flow amplification valve 3 are used as control oil ports. The flow amplification valve 3 includes a flow divider valve core 32 and a flow amplification valve core 33. The flow divider valve core 32 includes a first oil port, a second oil port, and a third oil port. The flow amplification valve core 33 includes a first oil inlet, a first oil return port, a first working oil port, and a second working oil port. The first oil return port of the flow amplification valve core 33 is connected to the oil tank. The first working oil port is connected to port A of the flow amplification valve 3 through a first oil circuit. The second working oil port is connected to port B of the flow amplification valve 3 through a second oil circuit.

[0051] The first port of the flow divider valve core 32 is connected to the steering pump 1, the second port is connected to the first inlet of the flow amplification valve core 33, and the third port is used to connect to other external systems. A return spring is provided at the left end of the flow divider valve core 32. When the flow divider valve core 32 is in the left position, the first and second ports are connected. When the flow divider valve core is in the middle position, the first port is connected to both the second and third ports. A damper is provided in the oil path between the first and third ports. When the flow divider valve core is in the right position, the first port is connected to both the second and third ports. A damper is provided in the oil path between the first and second ports. In this embodiment, the flow rate entering the steering system can be controlled by the position of the valve core. When the flow divider valve core is in the middle position, when the flow rate required for steering is met, excess hydraulic oil is merged into other systems through the PF. When the flow divider valve core is in the right position, all hydraulic oil passing through the flow divider valve core goes to other systems through the PF.

[0052] In actual operation, when the engine drives the steering pump 1 to rotate, the steering pump 1 starts to work and draws oil from the oil tank. When the steering wheel and the electric control handle 7, which are steering control elements, do not have any steering action, the first oil inlet of the flow amplification valve core 33 is cut off. The hydraulic oil output by the steering pump 1 acts on the right end of the flow divider valve core 32, pushing the flow divider valve core 32 to switch directions, so that the hydraulic oil flows through the third oil port in the flow divider valve core 32 to other systems.

[0053] Furthermore, the flow amplification valve core 33 includes a left position, a middle position and a right position. The left end of the flow amplification valve core 33 is connected to port a of the flow amplification valve 3, and the right end of the flow amplification valve core 33 is connected to port b of the flow amplification valve 3.

[0054] When the flow amplification valve core 33 is in the left position, the first oil inlet and the first oil return port of the flow amplification valve core 33 are connected to the first working oil port and the second working oil port, respectively.

[0055] When the flow amplification valve core 33 is in the neutral position, the first oil inlet and the first oil return port of the flow amplification valve core 33 are cut off.

[0056] When the flow amplification valve core 33 is in the right position, the first oil inlet and the first oil return port of the flow amplification valve core 33 are connected to the second working oil port and the first working oil port, respectively.

[0057] In this embodiment, the flow amplification valve core 33 is hydraulically controlled for reversing: when there is no steering control signal, the flow amplification valve core 33 remains in the neutral position; when a left turn is required, hydraulic oil acts on the left end of the flow amplification valve core 33 through port a of the flow amplification valve 3, driving the flow amplification valve core 33 to the left position. The hydraulic oil passes through the first inlet port and the first working port, so that the flow amplification valve 3 outputs hydraulic oil through port A to the steering cylinder 6 to achieve left steering; when a right turn is required, hydraulic oil acts on the right end of the flow amplification valve core 33 through port b of the flow amplification valve 3, driving the flow amplification valve core 33 to the right position. The hydraulic oil passes through the first inlet port and the second working port, so that the flow amplification valve 3 outputs hydraulic oil through port B to the steering cylinder 6 to achieve right steering.

[0058] Furthermore, to protect the oil circuit, the flow amplification valve 3 also includes a shuttle valve 34 and an overflow valve 31. The two oil inlets of the shuttle valve 34 are respectively connected to the first oil circuit and the second oil circuit. The oil outlet of the shuttle valve 34 is connected to the return oil circuit between the first return oil port and the oil tank through a third oil circuit. The overflow valve 31 is located on the third oil circuit. The left end of the diverter valve core 32 is connected to the third oil circuit and is located upstream of the overflow valve 31. The right end of the diverter valve core 32 is connected between the second oil port of the diverter valve core 32 and the first oil inlet of the flow amplification valve core 33.

[0059] Specifically, as pressurized oil flows into port A or B of the flow amplification valve 3, hydraulic oil from the first or second oil circuit is output to the inlet of the relief valve 31 via the outlet of the shuttle valve 34. If the pressure in the first or second oil circuit rises above the set pressure of the relief valve 31, the relief valve 31 will open, and its outlet will be directly connected to port T of the flow amplification valve 3 for return oil. At this time, the pressure acting on the left end of the flow divider valve core 32 disappears, and the hydraulic oil flows out through the third port of the flow divider valve core 32 and the PF port of the flow amplification valve 3 to other systems, thus protecting the oil circuit through the return oil passage. After the steering load is removed, the pressure in the first or second oil circuit decreases, the relief valve 31 closes, and the flow divider valve core 32 returns to its normal position.

[0060] Furthermore, to provide buffering, the hydraulic system in this embodiment also includes a buffer valve 35, which includes a left relief valve 351, a right relief valve 352, a left check valve 354, a right check valve 355, and a control valve 353.

[0061] The first and second oil circuits mentioned above are connected by a fourth and a fifth oil circuit in parallel; the left relief valve 351 and the right relief valve 352 are arranged in opposite flow directions on the fourth oil circuit. As is common knowledge in the art, the oil inlet ends of the left relief valve 351 and the right relief valve 352 are respectively connected to the second oil circuit and the first oil circuit; the left check valve 354 and the right check valve 355 are arranged in opposite flow directions on the fifth oil circuit; the control valve 353... The oil inlet is connected between the left relief valve 351 and the right relief valve 352, and the oil outlet of the control valve 353 is connected between the left check valve 354 and the right check valve 355; the left end of the control valve 353 is connected to the connecting oil line between the left relief valve 351 and the left check valve 354 through the left damper 356, and the right end of the control valve 353 is connected to the connecting oil line between the right relief valve 352 and the right check valve 355 through the right damper 357.

[0062] To explain the specific working principle, due to the load effect of steering resistance, the A port (corresponding to the left turn condition) or B port (corresponding to the right turn condition) of the flow amplification valve 3 will have instantaneous high pressure.

[0063] Taking the right turn as an example, the same applies to the left turn. If a momentary high pressure occurs at port B, the overflow pressure of the bidirectional buffer valve 35 is set relatively low. At this time, the left overflow valve 351 is opened, and the oil flows through the control valve 353 and the right check valve 355 into port A, turning towards the low-pressure side, thereby reducing the pressure surge during startup. At this time, the right side of the control valve 353 is affected by the oil pressure at port B, pushing the valve core to the left and closing the control valve 353. This prevents the oil pressure at port B from continuously depressurizing to the low-pressure side. This process is short in actual operation but can achieve a good buffering effect. Example

[0064] Based on the same inventive concept as Embodiment 1, this embodiment provides a control method for a loader steering hydraulic system, which includes:

[0065] In response to the right turn control signal:

[0066] If the R port output pressure of the steering gear 2 is greater than the preset threshold, the P port of the shut-off valve 4 is controlled to be connected only to the B port, and the P port of the proportional solenoid valve 5 is cut off; the hydraulic oil output from the R port of the steering gear 2 acts on the b port of the flow amplification valve 3, so that the hydraulic oil output from the B port of the flow amplification valve 3 is connected to the steering cylinder 6 to realize right turn.

[0067] If the output pressure of the R port of the steering gear 2 is less than a preset threshold, the P port, A port, and B port of the shut-off valve 4 are all connected, and the P port and R port of the proportional solenoid valve 5 are connected; the hydraulic oil output from the R port of the proportional solenoid valve 5 acts on the b port of the flow amplification valve 3, so that the hydraulic oil output from the B port of the flow amplification valve 3 is connected to the steering cylinder 6 to realize right steering.

[0068] In response to the left turn control signal:

[0069] If the output pressure at port L of the steering gear 2 is greater than a preset threshold, the P port of the shut-off valve 4 is controlled to be connected only to port B, and the P port of the proportional solenoid valve 5 is shut off; the hydraulic oil output from port L of the steering gear 2 acts on port a of the flow amplification valve 3, so that the hydraulic oil output from port A of the flow amplification valve 3 is sent to the steering cylinder 6 to achieve left turn.

[0070] If the output pressure at port L of the steering gear 2 is less than a preset threshold, the P port, A port, and B port of the shut-off valve 4 are all connected, and the P port and L port of the proportional solenoid valve 5 are connected. The hydraulic oil output from port L of the proportional solenoid valve 5 acts on port a of the flow amplification valve 3, so that the hydraulic oil output from port A of the flow amplification valve 3 is connected to the steering cylinder 6 to achieve right steering.

[0071] In one specific embodiment, a pressure sensor 91 is provided at the L port of the steering gear 2, and a pressure sensor 92 is provided at the R port of the steering gear 2. Example

[0072] Based on the same inventive concept as Embodiment 1, this embodiment provides a loader that includes the loader steering hydraulic system described in Embodiment 1.

[0073] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A loader steering hydraulic system, comprising a steering gear (2), a steering cylinder (6), and a steering pump (1) connected to an oil tank, characterized in that, It also includes a flow amplification valve (3), a pilot oil source valve (8), a shut-off valve (4), and a proportional solenoid valve (5); the oil outlet of the steering pump (1) is connected to the P port of the flow amplification valve (3) and the P port of the pilot oil source valve (8); the P port of the shut-off valve (4) is connected to the U port of the pilot oil source valve (8); the A port and B port of the shut-off valve (4) are respectively connected to the P port of the proportional solenoid valve (5) and the P port of the steering gear (2); the L port and R port of the steering gear (2) are respectively connected to the a port and b port of the flow amplification valve (3); the T port of the steering gear (2) is connected to the oil tank; the L port and R port of the proportional solenoid valve (5) are respectively connected to the a port and b port of the flow amplification valve (3); and the T port of the flow amplification valve (3) is connected to the oil tank. When the a port of the flow amplification valve (3) is acted upon by hydraulic oil, the A port of the flow amplification valve (3) outputs hydraulic oil to the steering cylinder (6) to achieve left steering; when the b port of the flow amplification valve (3) is acted upon by hydraulic oil, the B port of the flow amplification valve (3) outputs hydraulic oil to the steering cylinder (6) to achieve right steering; the shut-off valve (4) includes a left position and a right position. When the shut-off valve (4) is in the right position, the P port of the shut-off valve (4) is connected to its B port; when the shut-off valve (4) is in the left position, the P port of the shut-off valve (4) is connected to both its A port and its B port; The proportional solenoid valve (5) includes a left position, a middle position, and a right position; the switching of the proportional solenoid valve (5) is controlled by a solenoid valve; when the proportional solenoid valve (5) is in the left position, the P port and L port of the proportional solenoid valve (5) are connected, and the R port and T port of the proportional solenoid valve (5) are connected; when the proportional solenoid valve (5) is in the middle position, the P port of the proportional solenoid valve (5) is closed; when the proportional solenoid valve (5) is in the right position, the P port and R port of the proportional solenoid valve (5) are connected, and the L port and T port of the proportional solenoid valve (5) are connected. In response to the right turn control signal: if the R port output pressure of the steering gear (2) is greater than the preset threshold, the P port of the shut-off valve (4) is controlled to be connected only to the B port, and the P port of the proportional solenoid valve (5) is shut off; if the R port output pressure of the steering gear (2) is less than the preset threshold, the P port of the shut-off valve (4) is controlled to be connected to both the A port and the B port, and the P port and the R port of the proportional solenoid valve (5) are connected. In response to the left turn control signal, if the output pressure of the L port of the steering gear (2) is greater than the preset threshold, the P port of the shut-off valve (4) is controlled to be connected only to the B port, and the P port of the proportional solenoid valve (5) is cut off; if the output pressure of the L port of the steering gear (2) is less than the preset threshold, the P port of the shut-off valve (4) is controlled to be connected to both the A port and the B port, and the P port and the L port of the proportional solenoid valve (5) are connected.

2. The loader steering hydraulic system according to claim 1, characterized in that: The switching of the shut-off valve (4) is controlled by a solenoid valve.

3. The loader steering hydraulic system according to claim 1, characterized in that: The flow amplification valve (3) includes a flow divider valve core (32) and a flow amplification valve core (33); the flow divider valve core (32) includes a first oil port, a second oil port and a third oil port, and the flow amplification valve core (33) includes a first oil inlet, a first oil return port, a first working oil port and a second working oil port; The flow divider valve core (32) has a first oil port connected to the steering pump (1), a second oil port connected to the first oil inlet of the flow amplification valve core (33), and a third oil port for connecting to other external systems; the flow divider valve core (32) includes a left position, a middle position, and a right position; The flow amplification valve core (33) has a first return port connected to the oil tank, a first working port connected to port A of the flow amplification valve (3) through a first oil circuit, and a second working port connected to port B of the flow amplification valve (3) through a second oil circuit. When the flow divider valve core (32) is in the left position, the first oil port and the second oil port of the flow divider valve core (32) are connected. When the diversion valve core (32) is in the neutral position, the first oil port of the diversion valve core (32) is connected to the second oil port and the third oil port; a damper is provided in the oil passage between the first oil port and the third oil port; When the diversion valve core (32) is in the right position, the first oil port of the diversion valve core (32) is connected to the second oil port and the third oil port; a damper is provided in the oil line between the first oil port and the second oil port.

4. A loader steering hydraulic system according to claim 3, characterized in that: Also includes: The shuttle valve (34) has two inlets connected to the first oil circuit and the second oil circuit respectively; the outlet of the shuttle valve (34) is connected to the return oil circuit between the first return oil port and the oil tank through the third oil circuit. The overflow valve (31) is located on the third oil line; The left end of the diversion valve core (32) is connected to the third oil line and is located upstream of the overflow valve (31). The left end of the diversion valve core (32) is also provided with a reset spring. The right end of the diversion valve core (32) is connected between the second oil port of the diversion valve core (32) and the first oil inlet of the flow amplification valve core (33).

5. A loader steering hydraulic system according to claim 3, characterized in that: The flow amplification valve core (33) includes a left position, a middle position and a right position. The left end of the flow amplification valve core (33) is connected to port a of the flow amplification valve (3), and the right end of the flow amplification valve core (33) is connected to port b of the flow amplification valve (3). When the flow amplification valve core (33) is in the left position, the first oil inlet and the first oil return port of the flow amplification valve core (33) are connected to the first working oil port and the second working oil port, respectively. When the flow amplification valve core (33) is in the neutral position, the first oil inlet and the first oil return port of the flow amplification valve core (33) are cut off; When the flow amplification valve core (33) is in the right position, the first oil inlet and the first oil return port of the flow amplification valve core (33) are connected to the second working oil port and the first working oil port, respectively.

6. A loader steering hydraulic system according to claim 3, characterized in that: Also includes: The buffer valve (35) includes a left relief valve (351), a right relief valve (352), a left check valve (354), a right check valve (355), and a control valve (353). A fourth and a fifth oil circuit are connected in parallel between the first and second oil circuits; the left overflow valve (351) and the right overflow valve (352) are arranged in opposite flow directions on the fourth oil circuit, and the left check valve (354) and the right check valve (355) are arranged in opposite flow directions on the fifth oil circuit; the inlet of the control valve (353) is connected between the left overflow valve (351) and the right overflow valve (352), and the outlet of the control valve (353) is connected between the left check valve (354) and the right check valve (355); the left end of the control valve (353) is connected to the connecting oil circuit between the left overflow valve (351) and the left check valve (354), and the right end of the control valve (353) is connected to the connecting oil circuit between the right overflow valve (352) and the right check valve (355).

7. A control method for a loader steering hydraulic system, characterized in that, A loader steering hydraulic system according to any one of claims 1-6 is used to perform the following: In response to the right turn control signal: If the R port output pressure of the steering gear (2) is greater than the preset threshold, the P port of the shut-off valve (4) is controlled to be connected only to the B port, and the P port of the proportional solenoid valve (5) is cut off; the hydraulic oil output from the R port of the steering gear (2) acts on the b port of the flow amplification valve (3) so that the hydraulic oil output from the B port of the flow amplification valve (3) is connected to the steering cylinder (6) to realize right turn. If the R port output pressure of the steering gear (2) is less than the preset threshold, the P port, A port and B port of the shut-off valve (4) are connected, and the P port and R port of the proportional solenoid valve (5) are connected; the hydraulic oil output from the R port of the proportional solenoid valve (5) acts on the b port of the flow amplification valve (3) so that the hydraulic oil output from the B port of the flow amplification valve (3) is connected to the steering cylinder (6) to realize right turn; In response to the left turn control signal, If the L port output pressure of the steering gear (2) is greater than the preset threshold, the P port of the shut-off valve (4) is controlled to be connected only to the B port, and the P port of the proportional solenoid valve (5) is cut off; the hydraulic oil output from the L port of the steering gear (2) acts on the a port of the flow amplification valve (3) so that the A port of the flow amplification valve (3) outputs hydraulic oil to the steering cylinder (6) to achieve left turn; If the output pressure at port L of the steering gear (2) is less than a preset threshold, the P port, A port, and B port of the shut-off valve (4) are all connected, and the P port and L port of the proportional solenoid valve (5) are connected. The hydraulic oil output from port L of the proportional solenoid valve (5) acts on port a of the flow amplification valve (3) so that the hydraulic oil output from port A of the flow amplification valve (3) is connected to the steering cylinder (6) to achieve right turn.

8. The control method for a loader steering hydraulic system according to claim 7, characterized in that, Pressure sensor 1 (91) is provided at the L port of the steering gear (2), and pressure sensor 2 (92) is provided at the R port of the steering gear (2).

9. A loader, characterized in that, Includes a loader steering hydraulic system as described in any one of claims 1-6.

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