Electro-hydraulic steering hydraulic system

Abstract

The present invention provides an electro-hydraulic steering hydraulic system, which relates to the technical field of vehicle chassis equipment. Specifically, it includes a pressure source, a first pair of alignment reversing valves, a first hydraulic control reversing valve, a first proportional direction valve, a second proportional direction valve, a booster cylinder, an alignment cylinder and a control unit. The P port of the first pair of alignment reversing valves is connected to the pressure source, the B port is connected to the D1 interface and D2 interface of the booster alignment cylinder, and the T port is connected to the hydraulic oil recovery device. The K port of the first hydraulic control reversing valve is connected to the B port of the first pair of alignment reversing valves, the A port is communicated with the A chamber of the booster alignment cylinder, and the B port is communicated with the B chamber of the booster alignment cylinder. The A chamber and B chamber of the booster alignment cylinder are also connected to the control unit. The P port of the second pair of alignment reversing valves is connected to the pressure source, the B port is connected to the D1 and D2 interfaces of the alignment cylinder, and the T port is connected to the hydraulic oil recovery device. The present invention can improve the steering reliability of the vehicle, achieve miniaturization and light weight, and has higher safety.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle chassis equipment, and particularly to an electro-hydraulic steering hydraulic system. Background Art

[0002] With the development of vehicle technology, special vehicle chassis have put forward higher and higher requirements for high mobility and high passability, requiring the vehicle to be able to select different steering modes according to different vehicle speeds, thus putting forward higher requirements for the miniaturization and light weight of the electro-hydraulic steering system and components of multi-axle heavy special vehicles. The components of the original electro-hydraulic steering system are large in volume and heavy in weight, and there are many pipelines, which is not conducive to the overall layout.

[0003] In the original electro-hydraulic steering system, the on-off of the two chambers A and B of the boost cylinder is realized by using 2 plate-type one-way hydraulic locks or 2 electromagnetic directional valves. There are problems such as large valve group volume and inability to meet the installation space requirements. The electromagnetic directional valve will increase the system control points, and there is a possibility of spool jamming in the electromagnetic directional valve, so the system reliability is poor. Summary of the Invention

[0004] The problem solved by the present invention is to provide an electro-hydraulic steering hydraulic system that improves the steering reliability of the vehicle, realizes miniaturization and light weight of the steering proportional valve group, and has higher safety.

[0005] To solve the above problems, the present invention provides an electro-hydraulic steering hydraulic system, including a pressure source, a first alignment reversing valve, a first pilot-operated reversing valve, a first proportional direction valve, a second proportional direction valve, a boost cylinder, an alignment cylinder and a control unit. The P port of the first alignment reversing valve is connected to the pressure source, the B port is connected to the D1 interface and D2 interface of the boost alignment cylinder, and the T port is connected to the hydraulic oil recovery device. The K port of the first pilot-operated reversing valve is connected to the B port of the first alignment reversing valve, the A port is communicated with the A chamber of the boost alignment cylinder, and the B port is communicated with the B chamber of the boost alignment cylinder. The A chamber and B chamber of the boost alignment cylinder are also connected to the control unit. The P port of the second alignment reversing valve is connected to the pressure source, the B port is connected to the D1 and D2 interfaces of the alignment cylinder, and the T port is connected to the hydraulic oil recovery device. The K port of the second pilot-operated reversing valve is connected to the B port of the second alignment reversing valve, the A port is communicated with the A chamber of the boost cylinder, and the B port is communicated with the B chamber of the boost cylinder. The A chamber and B chamber of the boost cylinder are also connected to the control unit.

[0006] Further, the control unit includes a first proportional direction valve, a second proportional direction valve and a controller. The controller is connected to the first proportional direction valve, the second proportional direction valve, the first alignment reversing valve and the second alignment reversing valve. The A port and B port of the first proportional direction valve are respectively connected to the A chamber and B chamber of the boosting alignment cylinder. The controller controls the first proportional direction valve to communicate with the A chamber or B chamber of the boosting alignment cylinder. The A port and B port of the second proportional direction valve are respectively connected to the A chamber and B chamber of the boosting oil cylinder. The controller controls the A port and B port of the second proportional direction valve to communicate with the A chamber or B chamber of the boosting oil cylinder. The controller controls the first alignment reversing valve and the second alignment reversing valve to be energized or de-energized.

[0007] Further, it further includes a solenoid reversing valve, a first relief valve, a hydraulic oil pump and a check valve. The pressure source is an accumulator. A first pressure sensor is provided on the accumulator. The first pressure sensor is connected to the controller. The controller is connected to the solenoid reversing valve. The controller controls the solenoid reversing valve to be energized or de-energized. The hydraulic oil pump is connected to the accumulator to provide pressure oil for the accumulator. The inlet port of the first relief valve is connected to the hydraulic oil pump and the accumulator. The check valve is arranged between the accumulator and the inlet port of the first relief valve. The outlet port of the first relief valve is connected to the hydraulic oil recovery device. The P port of the solenoid reversing valve is communicated with the hydraulic oil pump. The T port of the solenoid reversing valve is connected to the control port of the first relief valve.

[0008] Further, it further includes a first shuttle valve, a second shuttle valve, a third shuttle valve and a fourth shuttle valve. The first inlet port and the second inlet port of the first shuttle valve are respectively communicated with the A chamber and B chamber of the boosting alignment cylinder. The first inlet port and the second inlet port of the second shuttle valve are respectively communicated with the A chamber and B chamber of the boosting oil cylinder. The first inlet port of the third shuttle valve is communicated with the outlet port of the first shuttle valve. The second inlet port of the third shuttle valve is communicated with the outlet port of the second shuttle valve. The first inlet port of the fourth shuttle valve is communicated with the T port of the solenoid reversing valve. The second inlet port of the fourth shuttle valve is communicated with the outlet port of the third shuttle valve. The outlet port of the fourth shuttle valve is communicated with the control port of the first relief valve.

[0009] Further, it further includes a first balance valve and a second balance valve. The first balance valve is connected between the A chamber and B chamber of the boosting alignment cylinder. The second balance valve is connected between the A chamber and B chamber of the boosting oil cylinder.

[0010] Further, the first hydraulic control reversing valve and the second hydraulic control reversing valve have the same structure. The first hydraulic control reversing valve includes a valve body, a main spool, a main spring and a plug.

[0011] The valve body is provided with a port A and a port B. A first boss is provided on the inner wall of the valve body near the port B.

[0012] A central through hole is provided in the main spool. The central through hole extends along the length direction of the main spool. One end of the main spool is provided with a conical surface. An annular groove is formed in the outer wall of the main spool near the conical surface. The main spool is arranged in the valve body. The outer wall of the middle part of the main spool is matched with the inner wall of the valve body. The position of the annular groove corresponds to the position of the port B. The conical surface abuts against the first boss. The plug is connected to the first end of the valve body. The conical surface is located between the plug and the first boss. One end of the main spring is connected to the inner wall of the plug, and the other end of the main spring is connected to the end of the main spool with the conical surface. The port A is located between the plug and the conical surface.

[0013] Further, a spring mounting boss is provided on the end surface of the conical surface corresponding to the plug. One end of the main spring connected to the conical surface is sleeved on the spring mounting boss.

[0014] Further, it further includes a valve sleeve, a one-way valve seat, a valve ball, a control spool, and a one-way valve spring. The valve sleeve is provided with a port O. A second annular boss is provided on the inner wall of the valve sleeve. The second annular boss is arranged near the port O. The other end of the valve body corresponding to the plug is the second end. The valve sleeve is connected to the second end of the valve body. The one-way valve seat is arranged in the valve sleeve. The one-way valve seat is arranged between the other end of the main spool corresponding to the conical surface and the second annular boss. A groove is formed in the one-way valve seat. The valve ball is arranged in the groove. The outer wall of the one-way valve seat protrudes out of the outer wall of the main spool and there is a gap between the outer wall of the one-way valve seat and the inner wall of the valve sleeve. The valve ball is adapted to abut against the second annular boss. There is an accommodation space between the outer wall of the other end of the main spool corresponding to the conical surface and the inner wall of the valve body. A radial through hole is provided on the main spool and is communicated with the accommodation space. The one-way valve spring is sleeved on the main spool and is located in the accommodation space. Two ends of the one-way valve spring are respectively connected between the one-way valve seat and the valve body. The control spool includes a top end and a mobile end which are connected to each other. The outer diameter of the top end is smaller than the inner diameter of the valve sleeve. The control spool is arranged in the valve sleeve. The top end is arranged near the valve ball. The mobile end is matched with the inner wall of the valve sleeve. The top end is used to push the one-way valve seat to move leftward through the valve ball, so as to make the main spool move leftward. One end of the control spool away from the valve ball is the port K.

[0015] Further, the valve sleeve is threadedly connected to the inner wall of the valve body. A third annular boss is provided on the outer wall of the valve sleeve, and the valve body abuts against the third annular boss.

[0016] Further, an axially protruding mounting boss is provided at one end of the one-way valve seat close to the main spool valve. The mounting boss is arranged in the inner cavity of the main spool valve. A retaining ring is provided on the inner wall of one end of the valve sleeve away from the valve body. The inner diameter of the retaining ring is smaller than the inner diameter of the control spool valve, and the control spool valve abuts against the retaining ring.

[0017] In an electro-hydraulic steering hydraulic system of the present invention, since it includes a pressure source, a boosting alignment cylinder, a boosting oil cylinder, an alignment cylinder, a control unit and a steering proportional valve group, and the steering proportional valve group is an independent electro-hydraulic proportional steering solution, using a first hydraulic control reversing valve and a second hydraulic control reversing valve as the on-off switching elements for the A chambers and B chambers of the boosting alignment cylinder and the alignment cylinder, it can ensure the synchronous on-off of the A chambers and B chambers of the boosting alignment cylinder and the alignment cylinder, improve the steering reliability of the vehicle, simplify the system, miniaturize and lighten the steering proportional valve group, and control the switching between the single-axle rear axle locking mode and the steering mode by energizing or de-energizing the first alignment reversing valve and the second alignment reversing valve ', realizing the functional interlock between the rear axle locking mode and the steering mode, making the entire hydraulic system safer. Description of the Drawings

[0018] Figure 1 is a schematic structural diagram of the electro-hydraulic steering hydraulic system of the present invention;

[0019] Figure 2 is a structural diagram of the first hydraulic control reversing valve in the electro-hydraulic steering hydraulic system of the present invention. Detailed Embodiments

[0020] To make the above objects, features and advantages of the present invention more obvious and understandable, the following detailed description of the specific embodiments of the present invention will be given with reference to the accompanying drawings.

[0021] In the embodiments of the present invention, the terms "upper", "lower", "front", "rear", "left" and "right" and other directions or positional relationships indicated are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be construed as a limitation of the present invention.

[0022] In the description of the present invention, it should be noted that, unless otherwise clearly specified and defined, the terms "set", "installed", "connected", and "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection; it may be directly connected, or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0023] If there are descriptions involving "first", "second", etc. in the embodiments of the present invention, such descriptions of "first", "second", etc. are only for descriptive purposes and should not be construed as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features.

[0024] An electro-hydraulic steering hydraulic system of the present invention, such as Figure 1As shown in the figure, it includes a pressure source, a boosting alignment cylinder 65, a boosting oil cylinder 67, an alignment cylinder 66, a control unit and a steering proportional valve group. The steering proportional valve group includes a first alignment reversing valve 30, a first hydraulically controlled reversing valve 39, a first proportional direction valve 35, a second alignment reversing valve 30', a second hydraulically controlled reversing valve 39', and a second proportional direction valve 35'. The pressure source provides hydraulic oil for each hydraulic valve of the steering proportional valve group. The P port of the first alignment reversing valve 30 is connected to the pressure source, the B port is connected to the D1 interface and D2 interface of the boosting alignment cylinder 65, and the T port is connected to the hydraulic oil recovery device. The K port of the first hydraulically controlled reversing valve 39 is connected to the B port of the first alignment reversing valve 30, the A port is communicated with the A chamber of the boosting alignment cylinder 65, and the B port is communicated with the B chamber of the boosting alignment cylinder 65. The A chamber and B chamber of the boosting alignment cylinder 65 are also connected to the control unit. The P port of the second alignment reversing valve 30' is connected to the pressure source, the B port is connected to the D1 interface and D2 interface of the alignment cylinder 66, and the T port is connected to the hydraulic oil recovery device. The K port of the second hydraulically controlled reversing valve 39' is connected to the B port of the second alignment reversing valve 30', the A port is communicated with the A chamber of the boosting oil cylinder 67, and the B port is communicated with the B chamber of the boosting oil cylinder 67. The A chamber and B chamber of the boosting oil cylinder 67 are also connected to the control unit. The boosting alignment cylinder 65 is an actuator that provides steering assistance or alignment force for the steering axle. The alignment cylinder 66 is an actuator that provides alignment force for the steering axle. The boosting oil cylinder 67 is an actuator that provides steering assistance for the steering axle. An electro-hydraulic steering hydraulic system of the present invention can achieve a steering mode and a locking mode, and perform steering actions according to the steering conditions of the front axle or actual usage during actual steering. In the steering mode, the control unit controls the first alignment reversing valve 30 and the second alignment reversing valve 30' to be energized. The D1 port and D2 port of the boosting alignment cylinder 65 are connected to the system return oil through the first alignment reversing valve 30, and the D1 port and D2 port of the alignment cylinder 66 are connected to the system return oil through the second alignment reversing valve 30'. The boosting alignment cylinder 65 and the alignment cylinder 66 are both in a pressure-relieved floating state. The control unit controls the hydraulic oil to enter the A chamber or B chamber of the boosting oil cylinder 67 to move the cylinder piston, realizing the steering assistance function. In the locking mode, the control unit controls the first alignment reversing valve 30 and the second alignment reversing valve 30' to be de-energized. The pressure oil in the pressure source enters the D1 chamber and D2 chamber of the boosting alignment cylinder 65 and the D1 chamber and D2 chamber of the alignment cylinder 66, pushing the pistons of the boosting alignment cylinder 65 and the alignment cylinder 66 to the middle position. At the same time, the pressure oil in the alignment circuit enters the K port of the first hydraulically controlled reversing valve 39 and the K port of the second hydraulically controlled reversing valve 39'. When the alignment pressure rises to a certain pressure, it pushes the first hydraulically controlled reversing valve 39 and the second hydraulically controlled reversing valve 39' to change direction, making the A chamber and B chamber of the boosting oil cylinder 67 communicate with each other and connected to the system return oil, unloading the boosting oil cylinder 67. After the boosting oil cylinder 67 is unloaded, the boosting alignment cylinder 65 and the alignment cylinder 66 can quickly return the steering axle to the correct position under the action of the alignment pressure, maintaining the stability of the vehicle during high-speed driving.An electro-hydraulic steering hydraulic system of the present invention includes a pressure source, a power-assisted alignment cylinder 65, a power-assisted oil cylinder 67, an alignment cylinder 66, a control unit and a steering proportional valve group. The steering proportional valve group is an independent electro-hydraulic proportional steering solution. The first hydraulic control reversing valve 39 and the second hydraulic control reversing valve 39' are used as the on-off switching elements for the A chambers and B chambers of the power-assisted alignment cylinder 65 and the alignment cylinder 67, which can ensure the synchronous on-off of the A chambers and B chambers of the power-assisted alignment cylinder 65 and the alignment cylinder 67, improve the steering reliability of the vehicle, simplify the system, miniaturize and lighten the steering proportional valve group, and control the switching between the single-axle rear axle locking mode and the steering mode by energizing or de-energizing the first alignment reversing valve 30 and the second alignment reversing valve 30', realizing the functional interlock between the rear axle locking mode and the steering mode, making the entire hydraulic system safer.

[0025] Optionally, the control unit includes a first proportional direction valve 35, a second proportional direction valve 35' and a controller. The controller is connected to the first proportional direction valve 35, the second proportional direction valve 35', the first alignment reversing valve 30 and the second alignment reversing valve 30'. The A port and B port of the first proportional direction valve 35 are respectively connected to the A chamber and B chamber of the power-assisted alignment cylinder 65. The controller controls the first proportional direction valve 35 to connect the first proportional direction valve 35 with the A chamber or B chamber of the power-assisted alignment cylinder 65. In this embodiment, both the first proportional direction valve 35 and the second proportional direction valve 35' are proportional direction valves with Y-type functions. The first proportional direction valve 35 is controlled by two proportional coils to control the direction and opening size of the spool. When the coil on the 4ADT side of the first proportional direction valve 35 is energized, the left side of the spool works, and the control pressure oil enters the B port of the first proportional direction valve 35 from the P port of the first proportional direction valve 35, and then enters the B chamber of the power-assisted alignment cylinder 65, causing the piston rod of the power-assisted alignment cylinder 65 to contract and drive the wheel to turn; at the same time, the oil in the A chamber of the power-assisted alignment cylinder 65 is communicated with the system return oil through the A port and O port of the first proportional direction valve 35. Similarly, when the 4BDT of the first proportional direction valve 35 is energized, the steering in the other direction is completed. The A port and B port of the second proportional direction valve 35' are respectively connected to the A chamber and B chamber of the power-assisted oil cylinder 67. The controller controls the A port and B port of the second proportional direction valve 35' to connect with the A chamber or B chamber of the power-assisted oil cylinder 67. The controller controls the first alignment reversing valve 30 and the second alignment reversing valve 30' to be energized or de-energized. The first proportional direction valve 35 and the second proportional direction valve 35' receive the steering instructions issued by the controller, and control the direction and opening amount of the spools of the first proportional direction valve 35 and the second proportional direction valve 35' to make the hydraulic oil enter the A chamber or B chamber of the power-assisted alignment cylinder 65 and the A chamber or B chamber of the power-assisted oil cylinder 67, realizing the steering assistance function.

[0026] Optionally, it further includes an electromagnetic directional control valve 33, a first overflow valve 32, a hydraulic oil pump 61, a check valve 310. The pressure source is an accumulator 64. The first overflow valve 32 is a fixed-differential overflow valve. A first pressure sensor 311 is provided on the accumulator 64. The first pressure sensor 311 is connected to the controller. The controller is connected to the electromagnetic directional control valve 33. The controller controls the electromagnetic directional control valve 33 to be energized or de-energized. The hydraulic oil pump 61 can specifically be a gear pump. A filter 31 is also provided on the output pipeline of the hydraulic oil pump 61 to perform secondary filtration on the hydraulic oil to prevent foreign matters from entering the steering proportional valve group and causing valve jamming. The hydraulic oil pump 61 is connected to the accumulator 64 to provide pressure oil for the accumulator 64. The oil inlet of the first overflow valve 32 is connected to the hydraulic oil pump 61. The oil inlet of the first overflow valve 32 is connected to the accumulator 64. The check valve 310 is arranged between the accumulator 64 and the oil inlet of the first overflow valve 32. The oil return port of the first overflow valve 32 is connected to the hydraulic oil recovery device. The P port of the electromagnetic directional control valve 33 is communicated with the hydraulic oil pump 61. The T port of the electromagnetic directional control valve 33 is connected to the control port of the first overflow valve 32. The pressure value measured by the first pressure sensor 311 is the pressure value of the alignment circuit. When the pressure value of the alignment circuit is lower than a certain set value, the alignment circuit needs to be replenished with fluid. At this time, the controller controls the electromagnetic directional control valve 33 to be energized. The system pressure provided by the hydraulic oil pump 61 acts on the control port of the first overflow valve 32 after passing through the electromagnetic directional control valve 33. At this time, the pressure of the oil inlet and the control port of the first overflow valve 32 are equal, and the overflow function of the first overflow valve 32 is turned off. The system pressure provided by the hydraulic oil pump 61 is maintained within the system safety pressure range. The oil fluid enters the accumulator 64 through the check valve 310. When the pressure value of the alignment circuit is equal to the system safety pressure, the replenishment of the accumulator 64 is completed, and the electromagnetic directional control valve 33 is de-energized, and the load sensing function is restored. Since the pressure source uses an accumulator, a first pressure sensor 311 is provided on the accumulator 64. The first pressure sensor 311 is connected to the controller. The controller is connected to the electromagnetic directional control valve 33. The controller controls the electromagnetic directional control valve 33 to be energized or de-energized. The system pressure is adaptively changed through the accumulator 64, the first pressure sensor 311, the electromagnetic directional control valve 33 and the first overflow valve 32. On the premise of ensuring the reliable operation of the system, the system heat generation is reduced. The alignment circuit is provided with an alignment power source by the accumulator 64, solving the problems of intense vibration under high-pressure conditions, high requirements for the cleanliness of the oil fluid, shortened service life caused by the pump running at high pressure for a long time in the locked mode and large system heat generation when using a load sensing pump such as the hydraulic oil pump 61 as the alignment power source. The check valve 310 can also prevent the oil fluid of the alignment circuit from entering the pressure system provided by the hydraulic oil pump 61, so that the pressure of the alignment circuit can be maintained for a long time.

[0027] Optionally, it further includes a first shuttle valve 34, a second shuttle valve 34', a third shuttle valve 71, and a fourth shuttle valve 71'. The first oil inlet and the second oil inlet of the first shuttle valve 34 are respectively communicated with the A chamber and the B chamber of the power alignment cylinder 65. The first oil inlet and the second oil inlet of the second shuttle valve 34' are respectively communicated with the A chamber and the B chamber of the power cylinder 67. The first oil inlet of the third shuttle valve 71 is communicated with the oil outlet of the first shuttle valve 34. The second oil inlet of the third shuttle valve 71 is communicated with the oil outlet of the second shuttle valve 34'. The first oil inlet of the fourth shuttle valve 71' is communicated with the T port of the electromagnetic directional valve 33. The second oil inlet of the fourth shuttle valve 71' is communicated with the oil outlet of the third shuttle valve 71. The oil outlet of the fourth shuttle valve 71' is communicated with the control port of the first relief valve 32. This system has a load-sensing function. By using the first shuttle valve 34 and the second shuttle valve 34', the larger steering working pressure in each steering axle is taken. After the higher pressures of the two steering axles are compared again by the third shuttle valve 71, the maximum steering working pressure acts on the control port of the first relief valve 32, so that the system pressure is always X MPa higher than the maximum steering working pressure. In the rear axle locking mode, the maximum steering working pressure of the rear axle is zero, so the oil in the rear axle overflows at X MPa. The value of X is small, realizing the load-sensing function of the system and effectively reducing the heat generation of the system.

[0028] Specifically, the third shuttle valve 71 is also connected with a second pressure sensor, which is convenient for fault diagnosis of the system, timely discovery of system faults, and ensuring the safety of the hydraulic system.

[0029] Optionally, it further includes a first balance valve 38 and a second balance valve 38'. The first balance valve 38 is connected between the A chamber and the B chamber of the power alignment cylinder 65. The second balance valve 38' is connected between the A chamber and the B chamber of the power cylinder 67. The first balance valve 38 and the second balance valve 38' can prevent the rear axle from shaking caused by the elastic deformation of the vehicle tires on bumpy roads and improve the steering stability of the vehicle.

[0030] Specifically, the first hydraulic control directional valve 39 and the second hydraulic control directional valve 39' have the same structure. As Figure 2 shown, the first hydraulic control directional valve 39 includes a valve body 1, a main spool 2, a main spring 8, and a plug 6.

[0031] The valve body 1 is provided with an A port and a B port. Both the A port and the B port are radial through holes provided on the valve body 1. A first boss 11 is provided on the inner wall of the valve body 1 near the B port.

[0032] A central through hole 26 is provided inside the main spool valve 2. The central through hole 26 extends along the length direction of the main spool valve 2. A conical surface 22 is provided at one end of the main spool valve 2. An annular groove 23 is formed on the outer wall of the main spool valve 2 near the conical surface 22. The main spool valve 2 is arranged inside the valve body 1. The outer wall of the middle part of the main spool valve 2 is matched with the inner wall of the valve body 1. A sealing ring 16 is arranged between the middle part of the main spool valve 2 and the inner wall of the valve body 1. Multiple sealing rings are arranged on the outer wall of the valve body 1. The position of the annular groove 23 corresponds to the position of the port B. The conical surface 22 is used to abut against the first boss 11. The plug 6 is connected to the first end of the valve body 1. The conical surface 22 is located between the plug 6 and the first boss 11. One end of the main spring 8 is connected to the inner wall of the plug 6, and the other end of the main spring 8 is connected to the end of the main spool valve 2 with the conical surface 22. The port A is located between the plug 6 and the conical surface 22. An O-ring 18 and an ED ring 21 are arranged on the outer wall of the plug 6 to form a double seal. When the main spool valve 2 is not subjected to the pressure of hydraulic oil, the conical surface 22 of the main spool valve 2 fits with the first boss 11 to form a pair of sealing pairs, realizing the internal isolation between the port A and the port B. When the main spool valve 2 is subjected to the pressure of hydraulic oil, the port A and the port B are communicated. Since the main spool valve 2 is provided with the conical surface 22 for fitting with the first boss 11, and the conical surface 22 is arranged between the port A and the port B, no matter whether the pressures of the port A and the port B are high or low, the main spool valve 2 will not move and the port A and the port B will not be communicated. Therefore, when the cartridge-type hydraulic control switching valve is used in the electro-hydraulic steering system of a multi-axle heavy-duty special vehicle, no matter whether the pressures of the A chamber and the B chamber of the booster cylinder 67 are high or low, the main spool valve 2 will not move, ensuring the reliable isolation between the A chamber and the B chamber of the booster cylinder.

[0033] Optionally, a spring installation boss 25 is provided on the end surface of the conical surface 22 corresponding to the plug 6. One end of the main spring 8 connected to the conical surface 22 is sleeved on the spring installation boss 25. The spring installation boss 25 plays a guiding role for the main spring 8.

[0034] Optionally, it further includes a valve sleeve 4, a check valve seat 3, a valve ball 14, a control valve core 5, and a check valve spring 9. The valve sleeve 4 is provided with an O port. Multiple groups of sealing rings 17 and 20 are arranged on the outer wall of the valve sleeve 4. A second annular boss 41 is arranged on the inner wall of the valve sleeve 4. The second annular boss 41 is arranged close to the O port. The other end of the valve body 1 corresponding to the plug 6 is the second end. The valve sleeve 4 is connected to the second end of the valve body 1. The check valve seat 3 is arranged in the valve sleeve 4. The check valve seat 3 is arranged between the other end of the main valve core 2 corresponding to the conical surface 22 and the second annular boss 41. A groove is formed in the check valve seat 3. The valve ball 14 is arranged in the groove. The outer wall of the check valve seat 3 protrudes beyond the outer wall of the main valve core 2 and there is a gap between the outer wall of the check valve seat 3 and the inner wall of the valve sleeve 4. The valve ball 14 is adapted to abut against the second annular boss 41. There is an accommodation space between the outer wall of the other end of the main valve core 2 corresponding to the conical surface 22 and the inner wall of the valve body 1. The main valve core 2 is provided with a radial through hole communicating with the accommodation space. The check valve spring 9 is sleeved on the main valve core 2 and the check valve spring 9 is located in the accommodation space. The two ends of the check valve spring 9 are respectively connected between the check valve seat 3 and the valve body 1. The control valve core 5 includes an abutting end 51 and a moving end 52 which are connected to each other. The outer diameter of the abutting end 51 is smaller than the inner diameter of the valve sleeve 4. The control valve core 5 is arranged in the valve sleeve 4. The abutting end 51 is arranged close to the valve ball 14. The abutting end 51 is used to push the check valve seat 3 to move leftward through the valve ball 14, so as to make the main valve core 2 move leftward. The moving end 52 is matched with the inner wall of the valve sleeve 4. Multiple sealing rings 15 are arranged between the moving end 52 and the inner wall of the valve sleeve 4. The end of the control valve core 5 away from the valve ball 14 is the K port. The check valve seat 3 and the valve ball 14 are attached to the second annular boss 41 of the valve sleeve 4 under the spring force of the check valve spring 9 to form a pair of sealing pairs, realizing the internal isolation of the A port, B port and O port. When there is no pressure at the K port in the cartridge-type hydraulically controlled switching valve of the present invention, the main valve core 2 abuts against the first boss 11 under the action of the main spring 8, and the A port and B port are isolated from each other; the check valve seat 3 and the ball valve 14 are in the reset state under the action of the check valve spring 9, and the ball valve 14 abuts against the second boss 41, that is, the A port and O port are isolated from each other. At this time, the A port, B port, O port and K port of the cartridge-type hydraulically controlled switching valve of the present invention are all isolated from each other, so as to realize the reliable synchronous on-off of the A port and B port, and the leakage amount is extremely low during disconnection. When the K port is connected to hydraulic oil and the pressure reaches a certain value, it pushes the control valve core 5 to move leftward. The control valve core 5 pushes the valve ball 14 and the check valve seat 3 to move, so that the valve ball 14 is separated from the second boss 41. The check valve seat 3 further pushes the main valve core 2 to move leftward, so that the conical surface 22 of the main valve core 2 is disengaged from the first boss 11 of the valve body 1, and the A port, B port and O port are communicated and connected to the system return oil. When the first hydraulically controlled reversing valve 39 and the second hydraulically controlled reversing valve 39' are used in the electro-hydraulic steering hydraulic system, such as Figure 1As shown in the figure, the electro-hydraulic steering system has four working modes: all-wheel steering mode, road steering mode, rear axle locking mode, and crab steering mode:

[0035] In the all-wheel steering mode, both the fourth and fifth axles can steer freely: The first pair of forward-reverse valves 30 and the second pair of forward-reverse valves 30' are both energized. The D1 and D2 ports of the centering cylinder 66 and the K port of the second hydraulic control reversing valve 39' are connected to the system return oil, and the centering cylinder 66 is in a pressure-relieved floating state. The main spools 2 of the first hydraulic control reversing valve 39 and the second hydraulic control reversing valve 39' are in contact with the first boss 11 under the action of the main spring 8, and the A and B ports are isolated from each other. Under the control of the proportional direction valve, the centering cylinders 65 of the fourth axle and the boost cylinders 67 of the fifth axle assist to achieve the steering function.

[0036] In the road steering mode, the fourth axle is in a locked state and the fifth axle can steer freely: The first pair of forward-reverse valves 30 are energized, and the second pair of forward-reverse valves 30' are de-energized. The pressure oil in the accumulator 64 enters the D1 and D2 ports of the centering cylinders 65 of the fourth axle to achieve the centering function. The D1 and D2 ports of the centering cylinder 66 of the fifth axle and the K port of the second hydraulic control reversing valve 39' are connected to the system return oil, and the centering cylinder is in a pressure-relieved floating state. Under the control of the second pair of forward-reverse valves 30', the boost cylinders 67 of the fifth axle assist to achieve the steering function.

[0037] In the rear axle locking steering mode, both the fourth and fifth axles are in a locked state: The first pair of forward-reverse valves 30 and the second pair of forward-reverse valves 30' are both de-energized. The pressure oil in the accumulator 64 enters the D1 and D2 ports of the centering cylinder 66 to achieve the centering function. At the same time, the pressure oil enters the K ports of the first hydraulic control reversing valve 39 and the second hydraulic control reversing valve 39'. When the centering pressure rises to a certain value, it pushes the control spool 5 to move leftward. The control spool 5 pushes the valve ball 14 and the check valve seat 3 to move, so that the valve ball 14 is separated from the second boss 41. The check valve seat 3 then pushes the main spool 2 to move leftward, so that the conical surface 22 of the main spool 2 is disengaged from the first boss 11 of the valve body 1, and the A and B ports are connected and connected to the system return oil to reduce the centering resistance.

[0038] Crab steering mode: The fourth and fifth axles maintain the same angle as the front axle, and the vehicle runs along an oblique line.

[0039] When the first hydraulic control reversing valve 39 and the second hydraulic control reversing valve 39' are used in the electro-hydraulic steering hydraulic system, they can realize the function of selecting a steering mode suitable for the vehicle speed according to different vehicle speeds. When the vehicle speed is less than the set value V1, it is the all-wheel steering mode. When the vehicle speed is greater than V1 and less than V2, it is the road steering mode. When the vehicle speed is greater than V2, it is the rear axle locking steering mode to improve the vehicle's high-speed driving stability. The all-wheel steering mode, road steering mode, and rear axle locking steering mode are controlled by the steering control unit according to the vehicle speed signal.

[0040] Optionally, the valve sleeve 4 is threadedly connected to the inner wall of the valve body 1.

[0041] Optionally, a third annular boss 43 is provided on the outer wall of the valve sleeve 4, and the valve body 1 abuts against the third annular boss 43.

[0042] Optionally, an installation boss 36 protruding axially is provided at one end of the one-way valve seat 3 close to the main spool 2, and the installation boss 36 is arranged in the inner cavity of the main spool 2 to prevent misalignment when the one-way valve seat 3 pushes the main spool 2 to move.

[0043] Optionally, a retaining ring 10 is further provided on the inner wall of one end of the valve sleeve 4 away from the valve body 1. The inner diameter of the retaining ring 10 is smaller than the inner diameter of the control spool 5. The control spool 5 abuts against the retaining ring 10, and the retaining ring 10 is used to position the control spool 5.

[0044] Optionally, the retaining ring 10 is threadedly connected to the valve sleeve 4.

[0045] Optionally, the plug 6 is threadedly connected to the valve body 1.

[0046] Although the present disclosure is disclosed as above, the protection scope of the present disclosure is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present disclosure, and these changes and modifications will all fall within the protection scope of the present invention.

Claims

1. An electro-hydraulic steering hydraulic system, characterized in that, it includes a pressure source, a first pair of positive reversing valves (30), a first pilot-operated reversing valve (39), a first proportional direction valve (35), a power-assisted alignment cylinder (65), a second pair of positive reversing valves (30'), a second pilot-operated reversing valve (39'), a second proportional direction valve (35'), a power-assisted oil cylinder (67), an alignment cylinder (66) and a control unit. The P port of the first pair of positive reversing valves (30) is connected to the pressure source, the B port is connected to the D1 and D2 interfaces of the power-assisted alignment cylinder (65), and the T port is connected to a hydraulic oil recovery device. The K port of the first pilot-operated reversing valve (39) is connected to the B port of the first pair of positive reversing valves (30), the A port is communicated with the A chamber of the power-assisted alignment cylinder (65), and the B port is communicated with the B chamber of the power-assisted alignment cylinder (65). The A chamber and the B chamber of the power-assisted alignment cylinder (65) are also connected to the control unit. The P port of the second pair of positive reversing valves (30') is connected to the pressure source, the B port is connected to the D1 and D2 interfaces of the alignment cylinder (66), and the T port is connected to a hydraulic oil recovery device. The K port of the second pilot-operated reversing valve (39') is connected to the B port of the second pair of positive reversing valves (30'), the A port is communicated with the A chamber of the power-assisted oil cylinder (67), and the B port is communicated with the B chamber of the power-assisted oil cylinder (67). The A chamber and the B chamber of the power-assisted oil cylinder (67) are also connected to the control unit.

2. The electro-hydraulic steering hydraulic system according to claim 1, characterized in that, the control unit includes a first proportional direction valve (35), a second proportional direction valve (35') and a controller. The controller is connected to the first proportional direction valve (35), the second proportional direction valve (35'), the first pair of positive reversing valves (30) and the second pair of positive reversing valves (30'). The A port and the B port of the first proportional direction valve (35) are respectively connected to the A chamber and the B chamber of the power-assisted alignment cylinder (65). The controller controls the first proportional direction valve (35) to communicate the first proportional direction valve (35) with the A chamber or the B chamber of the power-assisted alignment cylinder (65). The A port and the B port of the second proportional direction valve (35') are respectively connected to the A chamber and the B chamber of the power-assisted oil cylinder (67). The controller controls the A port and the B port of the second proportional direction valve (35') to communicate with the A chamber or the B chamber of the power-assisted oil cylinder (67). The controller controls the first pair of positive reversing valves (30) and the second pair of positive reversing valves (30') to be energized or de-energized.

3. The electro-hydraulic steering hydraulic system according to claim 2, characterized in that, It also includes an electromagnetic directional control valve (33), a first relief valve (32), a hydraulic oil pump (61), and a check valve (310). The pressure source is an accumulator (64). A first pressure sensor (311) is provided on the accumulator (64). The first pressure sensor (311) is connected to the controller. The controller is connected to the electromagnetic directional control valve (33). The controller controls the energization or de-energization of the electromagnetic directional control valve (33). The hydraulic oil pump (61) is connected to the accumulator (64) to provide pressurized oil for the accumulator (64). The inlet of the first relief valve (32) is connected to the hydraulic oil pump (61), and the inlet of the first relief valve (32) is connected to the accumulator (64). The check valve (310) is arranged between the accumulator (64) and the inlet of the first relief valve (32). The oil return port of the first relief valve (32) is connected to the hydraulic oil recovery device. The P port of the electromagnetic directional control valve (33) is communicated with the hydraulic oil pump (61), and the T port of the electromagnetic directional control valve (33) is connected to the control port of the first relief valve (32).

4. The electro-hydraulic steering hydraulic system according to claim 3, characterized in that, it also includes a first shuttle valve (34), a second shuttle valve (34'), a third shuttle valve (71), and a fourth shuttle valve (71'). The first inlet and the second inlet of the first shuttle valve (34) are respectively communicated with the A chamber and the B chamber of the alignment assist cylinder (65). The first inlet and the second inlet of the second shuttle valve (34') are respectively communicated with the A chamber and the B chamber of the assist cylinder (67). The first inlet of the third shuttle valve (71) is communicated with the outlet of the first shuttle valve (34). The second inlet of the third shuttle valve (71) is communicated with the outlet of the second shuttle valve (34'). The first inlet of the fourth shuttle valve (71') is communicated with the T port of the electromagnetic directional control valve (33). The second inlet of the fourth shuttle valve (71') is communicated with the outlet of the third shuttle valve (71). The outlet of the fourth shuttle valve (71') is communicated with the control port of the first relief valve (32).

5. The electro-hydraulic steering hydraulic system according to claim 4, characterized in that, it also includes a first balance valve (38) and a second balance valve (38'). The first balance valve (38) is connected between the A chamber and the B chamber of the alignment assist cylinder (65). The second balance valve (38') is connected between the A chamber and the B chamber of the assist cylinder (67).

6. The electro-hydraulic steering hydraulic system according to claim 5, characterized in that, the first hydraulic control directional control valve (39) and the second hydraulic control directional control valve (39') have the same structure. The first hydraulic control directional control valve (39) includes a valve body (1), a main spool (2), a main spring (8), and a plug (6). The valve body (1) is provided with an A port and a B port. A first boss (11) is provided on the inner wall of the valve body (1) near the B port. A central through hole (26) is provided in the main spool valve (2). The central through hole (26) extends along the length direction of the main spool valve (2). A conical surface (22) is provided at one end of the main spool valve (2). An annular groove (23) is formed in the outer wall of the main spool valve (2) near the conical surface (22). The main spool valve (2) is arranged in the valve body (1). The outer wall of the middle part of the main spool valve (2) is matched with the inner wall of the valve body (1). The position of the annular groove (23) corresponds to the position of the B port. The conical surface (22) abuts against the first boss (11). The plug (6) is connected to the first end of the valve body (1). The conical surface (22) is located between the plug (6) and the first boss (11). One end of the main spring (8) is connected to the inner wall of the plug (6), and the other end of the main spring (8) is connected to the end of the main spool valve (2) with the conical surface (22). The A port is located between the plug (6) and the conical surface (22).

7. The electro-hydraulic steering hydraulic system according to claim 6, characterized in that, a spring mounting boss (25) is provided on the end surface of the conical surface (22) corresponding to the plug (6), and one end of the main spring (8) connected to the conical surface (22) is sleeved on the spring mounting boss (25).

8. The electro-hydraulic steering hydraulic system according to claim 7, characterized in that, It further includes a valve sleeve (4), a check valve seat (3), a valve ball (14), a control spool (5), and a check valve spring (9). An O port is provided on the valve sleeve (4). A second annular boss (41) is provided on the inner wall of the valve sleeve (4), and the second annular boss (41) is arranged close to the O port. The other end of the valve body (1) corresponding to the plug (6) is the second end. The valve sleeve (4) is connected to the second end of the valve body (1). The check valve seat (3) is arranged in the valve sleeve (4), between the other end of the main spool (2) corresponding to the conical surface (22) and the second annular boss (41). A groove is provided on the check valve seat (3), and the valve ball (14) is arranged in the groove. The outer wall of the check valve seat (3) protrudes beyond the outer wall of the main spool (2), and there is a gap between the outer wall of the check valve seat (3) and the inner wall of the valve sleeve (4). The valve ball (14) is adapted to abut against the second annular boss (41). There is an accommodation space between the outer wall of the other end of the main spool (2) corresponding to the conical surface (22) and the inner wall of the valve body (1). A radial through hole is provided on the main spool (2) and is communicated with the accommodation space. The check valve spring (9) is sleeved on the main spool (2), and the check valve spring (9) is located in the accommodation space. Two ends of the check valve spring (9) are respectively connected between the check valve seat (3) and the valve body (1). The control spool (5) includes an abutting end (51) and a moving end (52) which are connected to each other. The outer diameter of the abutting end (51) is smaller than the inner diameter of the valve sleeve (4). The control spool (5) is arranged in the valve sleeve (4). The abutting end (51) is arranged close to the valve ball (14). The moving end (52) is matched with the inner wall of the valve sleeve (4). The abutting end (51) is used to push the check valve seat (3) to move leftward through the valve ball (14), so as to make the main spool (2) move leftward. One end of the control spool (5) away from the valve ball (14) is the K port.

9. The electro-hydraulic steering hydraulic system according to claim 8, characterized in that, the valve sleeve (4) is threadedly connected to the inner wall of the valve body (1). A third annular boss (43) is provided on the outer wall of the valve sleeve (4), and the valve body (1) abuts against the third annular boss (43).

10. The electro-hydraulic steering hydraulic system according to claim 9, characterized in that, an axially protruding mounting boss (36) is provided at one end of the check valve seat (3) close to the main spool (2). The mounting boss (36) is arranged in the inner cavity of the main spool (2). A retaining ring (10) is provided on the inner wall of one end of the valve sleeve (4) away from the valve body (1). The inner diameter of the retaining ring (10) is smaller than the inner diameter of the control spool (5). The control spool (5) abuts against the retaining ring (10).

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