Steering hydraulic system and engineering machinery
By introducing buffer valves and steering valves into the steering hydraulic system of the loader, the pressure shock and oscillation problems during the steering process of the loader are solved, and the pressure loss in the working circuit is reduced, achieving more stable steering and more efficient hydraulic system performance.
Patent Information
- Application Number
- CN202411968429.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-30
- Publication Date
- 2025-03-14
AI Technical Summary
The loader has pressure shock and oscillation during steering, resulting in poor stability during rapid start and stop, and there is a large pressure loss in the existing steering system.
A steering hydraulic system is designed, including a buffer valve and a steering valve. A buffer valve is used to unload pressure shock in the steering circuit, while a steering valve is used to reduce pressure loss in the working circuit. The output flow of the hydraulic pump flows directly to the multi-channel valve, and steering priority is achieved through the steering valve.
The pressure shock during the steering process of the damping unload of the buffer valve improves the stability of the steering; by canceling the priority valve, it flows directly to the multiple valves, reducing the pressure loss in the working circuit, and achieving steering priority.
Smart Images
Figure CN119611502A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of engineering machinery, and in particular relates to a steering hydraulic system and engineering machinery. Background Art
[0002] The loader has pressure shock and oscillation during the steering process, resulting in poor stability during rapid start and stop. The higher the steering wheel speed, the more obvious the shaking of the front frame. At the same time, the steering system is generally equipped with a priority valve. The pump output flow first passes through the priority valve and then the multi-way valve, resulting in a large pressure loss. Summary of the invention
[0003] In order to solve the deficiencies in the prior art, the present invention provides a steering hydraulic system and engineering machinery, which can not only unload the pressure impact during the rapid steering process, but also reduce the pressure loss in the working circuit.
[0004] In order to achieve the above object, the technical solution adopted by the present invention is: In the first aspect, a steering hydraulic system is provided, comprising: a buffer valve for unloading the pressure shock in the steering circuit during steering; a steering valve for reducing the pressure loss in the working circuit; the outlet of the hydraulic pump is connected to the inlet P of the steering valve in the steering circuit and the inlet of the multi-way valve in the working circuit; the outlet A of the steering valve is connected to the inlet of the steering gear, the oil port LS1 of the steering valve is connected to the inlet of the one-way valve and one end of the damper, and the other end of the damper is connected to the oil port LS of the steering gear, the oil port LS2 of the steering valve is connected to the outlet of the one-way valve, the oil port LS of the hydraulic pump, and the oil port LS of the multi-way valve; the oil port L of the steering gear is connected to the oil port A of the buffer valve, the rod chamber of the left steering cylinder, and the rodless chamber of the right steering cylinder; the oil port R of the steering gear is connected to the oil port B of the buffer valve, the rod chamber of the right steering cylinder, and the rodless chamber of the left steering cylinder; the oil port a of the buffer valve is connected to the oil port T of the steering gear and the inlet of the flow valve through the one-way damper, and the outlet of the flow valve is connected to the hydraulic oil tank; the oil port b of the buffer valve is connected to the hydraulic oil tank.
[0005] Further, the steering valve includes a pressure control valve, a pressure replica valve and a damper 2; the inlet of the pressure control valve, the inlet of the pressure replica valve and the non-spring chamber of the pressure replica valve are respectively connected to the inlet P of the steering valve; the non-spring chamber of the pressure control valve, the outlet of the pressure control valve and one end of the damper 2 are respectively connected to the outlet A of the steering valve; the other end of the damper 2, the spring chamber of the pressure control valve and the spring chamber of the pressure replica valve are respectively connected to the oil port LS1 of the steering valve; the outlet of the pressure replica valve is connected to the oil port LS2 of the steering valve.
[0006] Furthermore, the buffer valve includes valve core 1, valve core 2, check valve 2 and check valve 3. The left position of valve core 1, the left spring chamber of valve core 1 and the outlet of check valve 2 are respectively connected to the oil port A of the buffer valve; the right position of valve core 1, the right spring chamber of valve core 1 and the outlet of check valve 3 are respectively connected to the oil port B of the buffer valve; the middle position of valve core 1 is closed, the middle position outlet of valve core 1 is connected to the inlet of valve core 2, and the outlet of valve core 2 is connected to the inlet of check valve 2 and the inlet of check valve 3; the non-spring chamber of valve core 2 is connected to the oil port a of the buffer valve, and the spring chamber of valve core 2 is connected to the oil port b of the buffer valve.
[0007] Further, when the steering wheel is turned left at a speed greater than or equal to the first steering speed, the hydraulic oil in the rodless chamber of the left steering cylinder, the rod chamber of the right steering cylinder, and the oil port B of the buffer valve flows to the oil port R of the steering gear, flows to the flow valve through the oil port T of the steering gear, and then flows to the hydraulic oil tank; the hydraulic oil flowing from the oil port T of the steering gear to the flow valve establishes oil pressure between the inlet of the flow valve and the oil port T of the steering gear, and acts on the non-spring chamber of the valve core two, the valve core two switches to the left position, and the inlet and outlet of the valve core two are connected; the hydraulic oil in the oil port L of the steering gear acts on the oil port A of the buffer valve, so that the valve core one switches to the left position, and the inlet of the valve core one is connected to the outlet of the valve core one; the hydraulic oil in the oil port L of the steering gear flows to the oil port B of the buffer valve through the oil port A of the buffer valve, the left position of the valve core one, the left position damping oil channel of the valve core two, and the one-way valve three, and then flows to the hydraulic oil tank through the steering gear and the flow valve.
[0008] Further, when the steering wheel is turned right at a speed greater than or equal to the first steering speed, the hydraulic oil in the rodless chamber of the right steering cylinder, the rod chamber of the left steering cylinder, and the oil port A of the buffer valve flows to the oil port L of the steering gear, flows to the flow valve through the oil port T of the steering gear, and then flows to the hydraulic oil tank; the hydraulic oil flowing from the oil port T of the steering gear to the flow valve establishes oil pressure between the inlet of the flow valve and the oil port T of the steering gear, and acts on the non-spring chamber of the valve core two, the valve core two switches to the left position, and the inlet and outlet of the valve core two are connected; the hydraulic oil in the oil port R of the steering gear acts on the oil port A of the buffer valve, so that the valve core one switches to the right position, and the inlet of the valve core one is connected to the outlet of the valve core one; the hydraulic oil in the oil port R of the steering gear flows to the oil port A of the buffer valve through the oil port B of the buffer valve, the right position of the valve core one, the left position damping oil channel of the valve core two, and the one-way valve two, and then flows to the hydraulic oil tank through the steering gear and the flow valve.
[0009] Furthermore, when the steering wheel is turned at a speed less than the first steering speed, the flow of the steering gear's oil port T is insufficient to build up pressure to drive the valve core 2 to switch direction, and the valve core 2 is in the right cut-off state; the hydraulic oil in the steering gear's oil port R or oil port L does not pass through the buffer valve.
[0010] Furthermore, the working circuit also includes a working device, which is connected to the outlet of the multi-way valve. The hydraulic oil output by the hydraulic pump enters the steering circuit and the working circuit at the same time, and directly enters the working device through the multi-way valve in the working circuit.
[0011] Furthermore, when the steering and working devices act simultaneously and the steering load pressure is greater than the working load pressure, during the steering process, the oil port LS of the steering gear outputs a pressure signal to the oil port LS1 of the steering valve, and then passes through the internal oil channel of the steering valve to the spring chamber of the pressure replication valve. At the same time, the hydraulic oil in the inlet P of the steering valve flows to the non-spring chamber of the pressure replication valve and the inlet of the pressure replication valve through the internal oil channel of the steering valve, and then outputs a pressure signal to the oil port LS2 of the steering valve at the outlet of the pressure replication valve. The pressure signal oil in the oil port LS2 of the steering valve enters the oil port Ls of the multi-way valve, and passes through the internal oil channel of the multi-way valve to the spring chamber of the multi-way valve compensator. Since the steering load pressure is greater than the working load pressure, the valve core of the multi-way valve compensator moves, which reduces the flow area of the multi-way valve compensator, thereby reducing the flow rate of the hydraulic oil output by the hydraulic pump through the multi-way valve, and the hydraulic oil output by the hydraulic pump flows to the steering valve first, thereby realizing steering priority.
[0012] Furthermore, when the steering and working devices are actuated simultaneously and the steering load pressure is lower than the working load pressure, the flow rate output by the hydraulic pump flows preferentially to the steering system with lower load pressure, thereby achieving steering priority.
[0013] In a second aspect, a construction machine is provided, wherein the construction machine is equipped with the steering hydraulic system described in the first aspect.
[0014] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: the present invention provides a buffer valve for unloading the pressure shock in the steering circuit during steering. When the steering wheel is turned quickly, the buffer valve damps the pressure shock in the unloading steering process, thereby improving the steering stability; the steering valve is provided for reducing the pressure loss in the working circuit, the priority valve is cancelled in the steering circuit, the flow output by the hydraulic pump directly flows to the multi-way valve in the working circuit, the pressure loss in the working circuit is reduced, and the steering circuit realizes the steering priority through the steering valve. The steering valve only needs to match the steering flow, and the steering valve structure is smaller than the priority valve. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Figure 1 Schematic diagram of the principle of the steering valve in the embodiment of the present invention; Figure 2 Schematic diagram of the principle of the buffer valve in the embodiment of the present invention; Figure 3 is a schematic diagram of the principle of a steering hydraulic system provided by an embodiment of the present invention; In the figure: 1. Hydraulic oil tank; 2. Hydraulic pump; 3. Steering valve; 31. Pressure control valve; 32. Pressure duplication valve; 33. Damping 2; 4. Flow valve; 5. Steering gear; 6. One-way damping; 7. Left steering cylinder; 8. Right steering cylinder; 9. Buffer valve; 91. Valve core 1; 92. Valve core 2; 93. One-way valve 2; 94. One-way valve 3; 10. One-way valve 1; 11. Damping 1; 12. Multi-way valve; 121. Multi-way valve compensator; 13. Return oil filter element. DETAILED DESCRIPTION
[0016] 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.
[0017] Embodiment 1 like Figure 1~Figure 3 As shown, a steering hydraulic system comprises: a buffer valve 9 for unloading the pressure impact in the steering circuit during steering and a steering valve 3 for reducing the pressure loss in the working circuit.
[0018] like Figure 1 As shown, the steering valve 3 includes an inlet P, an outlet A, an oil port LS1, an oil port LS2, a pressure control valve 31, a pressure duplication valve 32 and a damper 33. The inlet of the pressure control valve 31, the inlet of the pressure duplication valve 32 and the non-spring chamber of the pressure duplication valve 32 are respectively connected to the inlet P of the steering valve 3; the non-spring chamber of the pressure control valve 31, the outlet of the pressure control valve 31 and one end of the damper 33 are respectively connected to the outlet A of the steering valve 3; the other end of the damper 33, the spring chamber of the pressure control valve 31 and the spring chamber of the pressure duplication valve 32 are respectively connected to the oil port LS1 of the steering valve 3; the outlet of the pressure duplication valve 32 is connected to the oil port LS2 of the steering valve 3.
[0019] like Figure 2 As shown, the buffer valve 9 includes oil port A, oil port a, oil port B, oil port b, valve core 1 91, valve core 2 92, check valve 2 93 and check valve 3 94. Valve core 1 91 is a three-position two-way valve, and the middle position is closed. Valve core 2 92 is a two-position two-way valve, and its left position oil passage is damped. The left position of valve core 1 91, the left spring chamber of valve core 1 91, and the outlet of check valve 2 93 are respectively connected to the oil port A of buffer valve 9; the right position of valve core 1 91, the right spring chamber of valve core 1 91, and the outlet of check valve 3 94 are respectively connected to the oil port B of buffer valve 9; the middle position of valve core 1 91 is closed, the middle position outlet of valve core 1 91 is connected to the inlet of valve core 2 92, and the outlet of valve core 2 92 is connected to the inlet of check valve 2 93 and the inlet of check valve 3 94; the non-spring chamber of valve core 2 92 is connected to the oil port a of buffer valve 9, and the spring chamber of valve core 2 92 is connected to the oil port b of buffer valve 9.
[0020] like Figure 3As shown, the outlet of the hydraulic pump 2 is connected to the inlet P of the steering valve 3 in the steering circuit and the inlet of the multi-way valve 12 in the working circuit. The hydraulic pump 2 is a load-sensitive plunger pump. Outlet A of the steering valve 3 is connected to the inlet of the steering gear 5, the oil port LS1 of the steering valve 3 is connected to the inlet of the one-way valve 10 and one end of the damper 11, and the other end of the damper 11 is connected to the oil port LS of the steering gear 5, the oil port LS2 of the steering valve 3 is connected to the outlet of the one-way valve 10, the oil port LS of the hydraulic pump 2, and the oil port LS of the multi-way valve 12; the oil port L of the steering gear 5 is connected to the oil port A of the buffer valve 9, the rod chamber of the left steering cylinder 7, and the rodless chamber of the right steering cylinder 8; the oil port R of the steering gear 5 is connected to the oil port B of the buffer valve 9, the rod chamber of the right steering cylinder 8, and the rodless chamber of the left steering cylinder 7; the oil port a of the buffer valve 9 is connected to the oil port T of the steering gear 5 and the inlet of the flow valve 4 through the one-way damper 6, and the outlet of the flow valve 4 is connected to the hydraulic oil tank 1; the oil port b of the buffer valve 9 is connected to the hydraulic oil tank 1.
[0021] When the steering wheel is turned left quickly, that is, when the steering wheel is turned left at a speed greater than or equal to the first steering speed (the set speed threshold), the hydraulic oil in the rodless chamber of the left steering cylinder 7, the rod chamber of the right steering cylinder 8, and the oil port B of the buffer valve 9 flows to the oil port R of the steering gear 5, flows to the flow valve 4 through the oil port T of the steering gear 5, and then flows to the hydraulic oil tank 1. The hydraulic oil flowing from the oil port T of the steering gear 5 to the flow valve 4 establishes oil pressure between the inlet of the flow valve 4 and the oil port T of the steering gear 5. Since the inlet P of the flow valve 4 is connected to the oil port a of the buffer valve 9 through the one-way damper 6, and the outlet T of the flow valve 4 is connected to the oil port b of the buffer valve 9, oil pressure is established between the inlet P of the flow valve 4 and the oil port T of the steering gear 5 and acts on the non-spring chamber of the valve core 2 92, the valve core 2 92 is switched to the left position, and the inlet and outlet of the valve core 2 92 are connected. When the steering wheel turns left, the hydraulic oil in the oil port L of the steering gear 5 acts on the oil port A of the buffer valve 9, so that the valve core 1 91 is switched to the left position, and the inlet of the valve core 1 91 is connected with the outlet of the valve core 1 91. As mentioned above, after the valve core 1 91 is switched to the left position and the valve core 2 92 is switched to the left position, the hydraulic oil in the oil port L of the steering gear 5 flows to the oil port B of the buffer valve 9 through the oil port A of the buffer valve 9, the left position of the valve core 1 91, the left position damping oil passage of the valve core 2 92, and the one-way valve 3 94, and then flows to the hydraulic oil tank 1 through the steering gear 5 and the flow valve 4. That is to say, when turning left quickly, the hydraulic oil in the oil port L of the steering gear 5 can be connected to the return oil passage through the left position damping oil passage of the valve core 2 92 of the buffer valve 9, thereby unloading the pressure impact during the steering process, achieving a buffering effect, and improving the stability of the steering.
[0022] When the steering wheel is turned right quickly, that is, when the steering wheel is turned right at a speed greater than or equal to the first steering speed, the hydraulic oil in the rodless chamber of the right steering cylinder 8, the rod chamber of the left steering cylinder 7, and the oil port A of the buffer valve 9 flows to the oil port L of the steering gear 5, flows to the flow valve 4 through the oil port T of the steering gear 5, and then flows to the hydraulic oil tank 1; the hydraulic oil flowing from the oil port T of the steering gear 5 to the flow valve 4 establishes oil pressure between the inlet of the flow valve 4 and the oil port T of the steering gear 5, and acts on the non-spring chamber of the valve core 2 92, the valve core 2 92 is switched to the left position, and the inlet and outlet of the valve core 2 92 are connected. When the steering wheel turns right, the hydraulic oil in the oil port R of the steering gear 5 acts on the oil port A of the buffer valve 9, so that the valve core 1 91 is switched to the right position, at which time, the inlet of the valve core 1 91 is connected to the outlet of the valve core 1 91. As described above, after the valve core 1 91 is switched to the right position and the valve core 2 92 is switched to the right position, the hydraulic oil in the oil port R of the steering gear 5 passes through the oil port B of the buffer valve 9, the right position of the valve core 1 91, the left position damping oil passage of the valve core 2 92, and the one-way valve 2 93 to flow to the oil port A of the buffer valve 9, and then passes through the steering gear 5 and the flow valve 4 to flow to the hydraulic oil tank 1. That is to say, when turning right quickly, the hydraulic oil in the oil port R of the steering gear 5 can be connected to the return oil passage through the left position damping oil passage of the valve core 2 92 of the buffer valve 9, thereby unloading the pressure impact during the steering process, achieving a buffering effect, and improving the stability of the steering.
[0023] When the steering wheel is turned slowly, that is, the steering wheel is turned at a speed lower than the first steering speed, the flow rate of the T port of the steering gear 5 is small, and the flow rate of the oil port T of the steering gear 5 is insufficient to establish the pressure to drive the valve core 2 92 to switch, and the valve core 2 92 is in the right position cut-off state; when the steering wheel is turned slowly, the hydraulic oil in the oil port R or oil port L of the steering gear 5 is the same as the return oil pipeline without passing through the buffer valve 9. At the same time, when the direction is turned slowly, the steering impact is generally small.
[0024] The working circuit also includes a working device, which is connected to the outlet of the multi-way valve 12. The hydraulic oil output by the hydraulic pump 2 enters the steering circuit and the working circuit at the same time, and directly enters the working device through the multi-way valve 12 in the working circuit. The return oil port of the multi-way valve 12 is connected to the inlet of the return oil filter 13, and the outlet of the return oil filter 13 is connected to the hydraulic oil tank 1.
[0025] When steering alone, the hydraulic oil output by the hydraulic pump 2 passes through the steering valve 3 and enters the left steering cylinder 7 and the right steering cylinder 8 through the steering gear 5.
[0026] When the steering circuit and the working circuit operate simultaneously, there are two working conditions. In one condition, the steering load pressure is greater than the working load pressure, and in the other condition, the steering load pressure is less than the working load pressure.
[0027] When the steering and working device are in action at the same time, and the steering load pressure is greater than the working load pressure, during the steering process, the oil port LS of the steering gear 5 outputs a pressure signal to the oil port LS1 of the steering valve 3, and then passes through the internal oil channel of the steering valve 3 to the spring chamber of the pressure duplication valve 32. At the same time, the hydraulic oil in the inlet P of the steering valve 3 flows through the internal oil channel of the steering valve 3 to the non-spring chamber of the pressure duplication valve 32 and the inlet of the pressure duplication valve 32, and then outputs a pressure signal to the oil port LS2 of the steering valve 3 at the outlet of the pressure duplication valve 32. The pressure signal oil in the oil port LS2 of the steering valve 3 enters the oil port Ls of the multi-way valve 12, and passes through the internal oil channel of the multi-way valve 12 to the spring chamber of the multi-way valve compensator 121. Since the steering load pressure is greater than the working load pressure, the multi-way valve compensator 121 moves to the right, so that the flow area of the multi-way valve compensator 121 is reduced, thereby making the hydraulic pump 2 The flow rate of the output hydraulic oil is reduced after passing through the multi-way valve 12, and the hydraulic oil output by the hydraulic pump 2 flows to the steering valve 3 first, and then flows to the steering cylinder after passing through the steering gear 5, so as to realize steering priority.
[0028] When the steering and working devices are actuated simultaneously, and the steering load pressure is lower than the working load pressure, the flow rate output by the hydraulic pump 2 flows preferentially to the steering system with lower load pressure, thereby achieving steering priority.
[0029] Embodiment 2 Based on the steering hydraulic system described in the first embodiment, this embodiment provides a construction machinery, wherein the construction machinery is equipped with the steering hydraulic system described in the first embodiment, and the construction machinery includes a loader.
[0030] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.
Claims
1. A steering hydraulic system, characterized in that: include: A buffer valve (9) for relieving pressure surges in the steering circuit during steering; A steering valve (3) for reducing pressure losses in the working circuit; The outlet of the hydraulic pump (2) is connected to the inlet P of the steering valve (3) in the steering circuit and the inlet of the multi-way valve (12) in the working circuit; The outlet A of the steering valve (3) is connected to the inlet of the steering gear (5); the oil port LS1 of the steering valve (3) is connected to the inlet of the check valve (10) and one end of the damper (11); the other end of the damper (11) is connected to the oil port LS of the steering gear (5); the oil port LS2 of the steering valve (3) is connected to the outlet of the check valve (10), the oil port LS of the hydraulic pump (2), and the oil port LS of the multi-way valve (12); The oil port L of the steering gear (5) is connected to the oil port A of the buffer valve (9), the rod chamber of the left steering cylinder (7), and the rodless chamber of the right steering cylinder (8); the oil port R of the steering gear (5) is connected to the oil port B of the buffer valve (9), the rod chamber of the right steering cylinder (8), and the rodless chamber of the left steering cylinder (7); the oil port a of the buffer valve (9) is connected to the oil port T of the steering gear (5) and the inlet of the flow valve (4) through the one-way damper (6), and the outlet of the flow valve (4) is connected to the hydraulic oil tank (1); the oil port b of the buffer valve (9) is connected to the hydraulic oil tank (1).
2. The steering hydraulic system according to claim 1, characterized in that: The steering valve (3) comprises a pressure control valve (31), a pressure duplication valve (32) and a damper (33); the inlet of the pressure control valve (31), the inlet of the pressure duplication valve (32) and the non-spring chamber of the pressure duplication valve (32) are respectively connected to the inlet P of the steering valve (3); the non-spring chamber of the pressure control valve (31), the outlet of the pressure control valve (31) and one end of the damper (33) are respectively connected to the outlet A of the steering valve (3); the other end of the damper (33), the spring chamber of the pressure control valve (31) and the spring chamber of the pressure duplication valve (32) are respectively connected to the oil port LS1 of the steering valve (3); and the outlet of the pressure duplication valve (32) is connected to the oil port LS2 of the steering valve (3).
3. The steering hydraulic system according to claim 2, characterized in that: The buffer valve (9) comprises a valve core 1 (91), a valve core 2 (92), a check valve 2 (93) and a check valve 3 (94); the left position of the valve core 1 (91), the left spring chamber of the valve core 1 (91) and the outlet of the check valve 2 (93) are respectively connected to the oil port A of the buffer valve (9); the right position of the valve core 1 (91), the right spring chamber of the valve core 1 (91) and the outlet of the check valve 3 (94) are respectively connected to the oil port B of the buffer valve (9); the middle position of the valve core 1 (91) is closed, the middle position outlet of the valve core 1 (91) is connected to the inlet of the valve core 2 (92), the outlet of the valve core 2 (92) is connected to the inlet of the check valve 2 (93) and the inlet of the check valve 3 (94); the non-spring chamber of the valve core 2 (92) is connected to the oil port a of the buffer valve (9), and the spring chamber of the valve core 2 (92) is connected to the oil port b of the buffer valve (9).
4. The steering hydraulic system according to claim 3, characterized in that: When the steering wheel is turned to the left at a speed greater than or equal to the first steering speed, the hydraulic oil in the rodless chamber of the left steering cylinder (7), the rod chamber of the right steering cylinder (8), and the oil port B of the buffer valve (9) flows to the oil port R of the steering gear (5), flows to the flow valve (4) through the oil port T of the steering gear (5), and then flows to the hydraulic oil tank (1); the hydraulic oil flowing from the oil port T of the steering gear (5) to the flow valve (4) establishes oil pressure between the inlet of the flow valve (4) and the oil port T of the steering gear (5), and acts on the non-return valve of the valve core 2 (92). The spring chamber, the valve core 2 (92) is switched to the left position, and the inlet and outlet of the valve core 2 (92) are connected; the hydraulic oil in the oil port L of the steering gear (5) acts on the oil port A of the buffer valve (9), so that the valve core 1 (91) is switched to the left position, and the inlet and outlet of the valve core 1 (91) are connected; the hydraulic oil in the oil port L of the steering gear (5) flows through the oil port A of the buffer valve (9), the left position of the valve core 1 (91), the left position damping oil passage of the valve core 2 (92), and the one-way valve 3 (94) to the oil port B of the buffer valve (9), and then flows through the steering gear (5) and the flow valve (4) to the hydraulic oil tank (1).
5. The steering hydraulic system according to claim 4, characterized in that: When the steering wheel is turned right at a speed greater than or equal to the first steering speed, the hydraulic oil in the rodless chamber of the right steering cylinder (8), the rod chamber of the left steering cylinder (7), and the oil port A of the buffer valve (9) flows to the oil port L of the steering gear (5), flows to the flow valve (4) through the oil port T of the steering gear (5), and then flows to the hydraulic oil tank (1); the hydraulic oil from the oil port T of the steering gear (5) flows to the flow valve (4), and establishes oil pressure between the inlet of the flow valve (4) and the oil port T of the steering gear (5), and acts on the non-return valve of the valve core 2 (92). The spring chamber, the valve core 2 (92) is switched to the left position, and the inlet and outlet of the valve core 2 (92) are connected; the hydraulic oil in the oil port R of the steering gear (5) acts on the oil port A of the buffer valve (9), so that the valve core 1 (91) is switched to the right position, and the inlet and outlet of the valve core 1 (91) are connected; the hydraulic oil in the oil port R of the steering gear (5) flows through the oil port B of the buffer valve (9), the right position of the valve core 1 (91), the damping oil passage of the left position of the valve core 2 (92), and the check valve 2 (93) to the oil port A of the buffer valve (9), and then flows through the steering gear (5) and the flow valve (4) to the hydraulic oil tank (1).
6. The steering hydraulic system according to claim 4, characterized in that: When the steering wheel is turned at a speed lower than the first steering speed, the flow rate of the oil port T of the steering gear (5) is insufficient to build up pressure to drive the second valve core (92) to switch direction, and the second valve core (92) is in the right position cut-off state; the hydraulic oil in the oil port R or the oil port L of the steering gear (5) does not pass through the buffer valve (9).
7. The steering hydraulic system according to claim 4, characterized in that: The working circuit also includes a working device, which is connected to the outlet of the multi-way valve (12). The hydraulic oil output by the hydraulic pump (2) enters the steering circuit and the working circuit at the same time, and directly enters the working device through the multi-way valve (12) in the working circuit.
8. The steering hydraulic system according to claim 7, characterized in that: When the steering and working device are actuated simultaneously, and the steering load pressure is greater than the working load pressure, during the steering process, the oil port LS of the steering gear (5) outputs a pressure signal to the oil port LS1 of the steering valve (3), and then passes through the internal oil passage of the steering valve (3) to the spring chamber of the pressure duplication valve (32). At the same time, the hydraulic oil in the inlet P of the steering valve (3) flows through the internal oil passage of the steering valve (3) to the non-spring chamber of the pressure duplication valve (32) and the inlet of the pressure duplication valve (32), and then outputs a pressure signal to the oil port LS2 of the steering valve (3) at the outlet of the pressure duplication valve (32). The pressure signal oil in the oil port LS2 of the steering valve (3) enters the oil port Ls of the multi-way valve (12), and passes through the internal oil passage of the multi-way valve (12) to the spring chamber of the multi-way valve compensator (121). Since the steering load pressure is greater than the working load pressure, the valve core of the multi-way valve compensator (121) moves, so that the flow area of the multi-way valve compensator (121) is reduced, thereby causing the hydraulic pump (2) to The flow rate of the output hydraulic oil is reduced after passing through the multi-way valve (12), and the hydraulic oil output by the hydraulic pump (2) flows preferentially to the steering valve (3), thereby achieving steering priority.
9. The steering hydraulic system according to claim 7, characterized in that: When the steering and working devices are actuated simultaneously and the steering load pressure is lower than the working load pressure, the flow output by the hydraulic pump (2) flows preferentially to the steering system with lower load pressure, thereby achieving steering priority.
10. An engineering machine, characterized in that: The engineering machinery is equipped with a steering hydraulic system according to any one of claims 1 to 9.