Hydraulic system for electrically controlled steering axle center locking and crane

Abstract

This invention discloses a hydraulic system for center-position locking of an electronically controlled steering shaft. The P1 port of the hydraulic selector valve is connected to a steering pump, and the P2 port is connected to a variable displacement piston pump. The B port of the hydraulic selector valve is connected to an accumulator. The accumulator is connected to the electronically controlled axle locking hydraulic circuit, providing high-pressure oil to achieve center-position locking of the electronically controlled axle locking cylinder. Port 1 of the dual-circuit steering gear is connected to port A of the hydraulic selector valve. The second steering pump is connected to port 1 of the other circuit of the dual-circuit steering gear, and ports 2 of the dual-circuit steering gear are both used for return oil. The left and right steering cylinders of the mechanical steering shaft are connected to the high-pressure oil ports of the dual-circuit steering gear to achieve hydraulic power steering. This invention, through the hydraulic selector valve, allows the emergency steering oil source of the mechanical steering shaft and the center-position locking oil source of the electronically controlled steering shaft to share the same oil pump device, prioritizing the emergency steering function of the mechanical steering shaft, reducing energy consumption, and saving on the number of oil pumps.

Description

Technical Field

[0001] This invention relates to a hydraulic system and a crane for center-position locking of an electronically controlled steering shaft, belonging to the field of engineering machinery technology. Background Technology

[0002] Currently, with the development of infrastructure construction at home and abroad, the level of technical research on construction machinery vehicles has been improved like never before, and the steering technology and design level of multi-axle construction machinery vehicles are showing a rapid development trend.

[0003] For the steering system of multi-axle construction machinery vehicles, it generally consists of a mechanical drive steering device, a hydraulic drive steering device, and a steering control device. With the continuous development of technology, electronic steering has been introduced into the steering system. Currently, the axles used in the vehicle can be divided into mechanical steering axles and electronic steering axles according to whether they steer. Mechanical steering axles are interconnected through mechanical linkages to ensure the wheel angle relationship between the mechanical axles. Electronic steering axles control the angle of each axle through electronic means, ultimately achieving a tire steering angle that conforms to the Ackermann steering relationship during the vehicle's steering process.

[0004] The aforementioned steering mechanism enables the vehicle to steer. However, to ensure high-speed stability and safety during vehicle operation, the electronically controlled steering axle is typically locked in the center position after the vehicle speed exceeds a certain level, and no longer follows the first axle for steering. To achieve the center position locking function, electronically controlled steering axles in domestic and international vehicles are equipped with a steering center position locking cylinder for locking the center position of the electronically controlled steering axle when the vehicle is traveling at high speed.

[0005] Currently, the steering hydraulic system of the electronically controlled steering axle of multi-axle vehicles is generally divided into two types: constant pressure variable system and load-sensitive system. In the constant pressure variable system, the oil pump device uses a constant pressure plunger variable pump, which supplies oil for both tire steering and center position locking functions of the electronically controlled axle. Its advantages are that it can provide constant pressure and fast pressure build-up response time. Its disadvantages are that it generates more heat and has higher energy consumption. In the load-sensitive system, the oil pump device uses a load-sensitive pump, which can provide oil for tire steering of the electronically controlled axle. Its advantages are that it provides a corresponding pressure oil source according to the actual load. When there is no load, there is only low pressure backup, generating less heat and having lower energy consumption. However, this system cannot meet the constant high pressure oil source required by the tire center position locking cylinder. Therefore, existing construction machinery vehicles generally use an additional plunger pump or gear pump that can provide constant high pressure to meet the oil supply of the tire center position locking cylinder of the electronically controlled steering axle.

[0006] Currently, when the steering hydraulic system of the electronically controlled steering axle of a multi-axle construction machinery vehicle chassis includes a center-position locking cylinder, a common approach is to share a constant-pressure variable pump with the tire power steering cylinder hydraulic system, or to use a separate steering pump. This continuously provides a constant high-pressure oil source to the center-position locking cylinder of the electronically controlled steering axle, achieving the center-position locking function. This approach results in high heat generation, high energy consumption, complex layout space, high cost, and difficulties in using the chassis hydraulic pump for power extraction, posing challenges to the overall vehicle matching and design. Summary of the Invention

[0007] The purpose of this invention is to provide a hydraulic system and crane for center-position locking of an electronically controlled steering shaft, in order to solve the defects of the prior art, which uses a constant pressure variable pump shared with the tire power steering cylinder hydraulic system, or a separate steering pump, resulting in high heat generation, high energy consumption, complex layout space, high cost, and difficulty in using the chassis hydraulic pump for power take-off.

[0008] A hydraulic system for center position locking of an electronically controlled steering shaft, the system comprising:

[0009] A hydraulic selector valve, wherein the P1 port of the hydraulic selector valve is connected to a steering pump and the P2 port is connected to a plunger variable pump, and the B port of the hydraulic selector valve is connected to an accumulator.

[0010] An electronically controlled axle locking hydraulic circuit is provided, wherein the accumulator is connected to the electronically controlled axle locking hydraulic circuit to provide high-pressure oil to achieve the center-position locking of the electronically controlled axle center-position locking cylinder;

[0011] A dual-circuit steering gear, wherein port 1 of the dual-circuit steering gear is connected to port A of the hydraulic selector valve;

[0012] Steering pump two is connected to port 1 of the other circuit of the dual-circuit steering gear, and ports 2 of the dual-circuit steering gear are both used for oil return.

[0013] A mechanical steering shaft is provided, wherein the left and right steering cylinders of the mechanical steering shaft are connected to the high-pressure oil ports of the dual-circuit steering system to realize hydraulic power steering.

[0014] Furthermore, the system also includes a first control valve group, a second control valve group (left), an electric steering shaft one, a second control valve group (right), and an electric steering shaft two;

[0015] The P port of the first control valve group is connected to the oil pump and is used to provide steering hydraulic assistance to the first and second electric steering shafts. The T port is used for oil return. The A port of the first control valve group is connected to the A1 port of the left and right sides of the second control valve group respectively. The B port of the first control valve group is connected to the A2 port of the left and right sides of the second control valve group.

[0016] The B1 oil port of the left and right sides of the second control valve group is cross-connected with the rodless and rod chambers of the steering cylinders on both sides of the electric steering shaft one and the electric steering shaft two. The B2 oil port of the left and right sides of the second control valve group is cross-connected with the rod chamber and rodless chamber of the steering cylinders on both sides of the electric steering shaft one and the electric steering shaft two.

[0017] Furthermore, the high-pressure oil at the output end of the accumulator enters from the P oil port of the second control valve group left and the second control valve group right respectively, and is connected to the third control valve group left and the third control valve group right, for controlling the center position locking cylinder.

[0018] Furthermore, the B ports of the left and right sides of the third control valve group are connected to the rod chamber of the locking cylinder, and the A port is connected to the rodless chamber of the locking cylinder.

[0019] Furthermore, the piston rod end of the steering cylinder is connected to a steering rocker arm, one end of which is connected to a center-locking cylinder, and the other end is connected to a steering knuckle arm via a steering tie rod.

[0020] Furthermore, the T-ports of the left and right sides of the third control valve group are connected in parallel with the T-ports of the left and right sides of the second control valve group to form a loop.

[0021] Furthermore, the No. 2 oil port of the dual-circuit steering gear forms a circuit as the return oil port.

[0022] A crane comprising the hydraulic system described above.

[0023] Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0024] In designing a steering system for multi-axle engineering machinery vehicles, this invention adds a center-position locking cylinder to the disconnected trapezoidal mechanism to ensure the reliability and safety of the electronically controlled steering axle at medium and high speeds. Furthermore, based on the steering hydraulic principle and pump selection, the oil sources for the steering cylinder and the center-position locking cylinder of the electronically controlled steering axle are independent. The oil source for the steering cylinder can be provided by a load-sensitive pump, reducing energy consumption and lowering oil temperature.

[0025] In this invention, the hydraulic oil source for the center-position locking cylinder and the emergency steering hydraulic oil source for the mechanical steering shaft share a single plunger variable pump. The priority between the two is to first ensure the emergency hydraulic oil source for the mechanical steering shaft to avoid energy consumption and increasing the number of pumps. Therefore, the emergency hydraulic oil source can be switched to the hydraulic oil source for the center-position locking cylinder through a hydraulic control selector valve. By adding an accumulator to the hydraulic oil inlet circuit of the center-position locking cylinder, the hydraulic pressure response speed of the center-position locking cylinder can be improved. At the same time, it can be ensured that the center-position locking cylinder has sufficient pressure hydraulic oil to lock the vehicle in the center-position driving state when the mechanical steering shaft is in emergency steering. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the arrangement of the electronically controlled steering shaft mechanism of the present invention;

[0027] Figure 2 This is a schematic diagram of the steering oil pump of the present invention during normal operation;

[0028] Figure 3 This is a schematic diagram of a steering pump malfunction according to the present invention;

[0029] In the diagram: 1—First control valve group; 2—Left of second control valve group; 3—Left of third control valve group; 4—Electric steering shaft one; 5—Accumulator; 6—Hydraulic selector valve; 7—Dual-circuit steering gear; 8—Mechanical steering shaft; 9—Right of second control valve group; 10—Right of third control valve group; 11—Electric steering shaft two; 12—Plunger variable displacement pump; 13—Steering pump one; 14—Steering pump two; 15—Steering cylinder; 16—Neutral locking cylinder; 17—Steering rocker arm; 18—Steering tie rod; 19—Steering knuckle arm. Detailed Implementation

[0030] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0031] As shown in the attached figures, this invention discloses a hydraulic system for center-position locking of an electronically controlled steering shaft, the system comprising:

[0032] The hydraulic selector valve 6 has a P1 port connected to a steering oil pump 13 and a P2 port connected to a plunger variable pump 12. The B port of the hydraulic selector valve 6 is connected to an accumulator 5.

[0033] The accumulator 5 is connected to the hydraulic circuit for locking the electric axle, providing high-pressure oil to achieve the center-position locking of the electric axle center-position locking cylinder. The addition of an accumulator device to the hydraulic system for locking the center-position locking of the electric steering axle can enhance the rapid response and pressure build-up of the center-position locking function after receiving the solenoid valve command, ensuring that the hydraulic system can quickly supply a high-pressure oil source.

[0034] A dual-circuit steering gear 7, wherein port 1 of the dual-circuit steering gear 7 is connected to port A of the hydraulic selector valve 6; and ports 2 of the dual-circuit steering gear 7 are both used as return ports to form a circuit.

[0035] Steering pump 2 14 is connected to port 1 of another circuit of the dual-circuit steering gear 7, and port 2 of the dual-circuit steering gear 7 is used for oil return.

[0036] The mechanical steering shaft 8 has left and right steering cylinders connected to the high-pressure oil port of the dual-circuit steering gear 7 to realize hydraulic power steering.

[0037] In this invention, a hydraulic selector valve is used to enable the emergency steering oil source of the mechanical steering shaft and the center position locking oil source of the electric steering shaft to share the same oil pump device, and to protect them differently according to priority, giving priority to ensuring the emergency steering function of the mechanical steering shaft. The emergency steering pump can also provide a high-pressure oil source for the center position locking cylinder of the electric steering shaft.

[0038] This invention is mainly used in two operating conditions:

[0039] Operating Condition 1: When the steering pump 13 is working normally, the pump generates high-pressure oil that enters the P1 port of the hydraulic selector valve 6. According to the working logic of the hydraulic selector valve, under the action of the pilot oil source at the P1 port, the valve core will move to another working position. At this time, the P1 port of the hydraulic selector valve is connected to port A, and the P2 port is connected to port B. Steering pump 13 and steering pump 14 supply high-pressure oil to the dual-circuit steering gear to realize hydraulic power steering. Meanwhile, the plunger variable pump 12 enters the P2 port of the hydraulic selector valve and enters the hydraulic circuit of the electronic axle locking cylinder through port B, providing a continuous high-pressure oil source to the axle locking cylinder. At the same time, it can provide high-pressure oil to the accumulator 5 to ensure that the accumulator oil pressure is stable at the plunger pump system pressure.

[0040] Operating Condition 2: When the steering pump 13 malfunctions or its drive power fails, causing the steering pump 13 to malfunction, the steering pump 13 cannot output high-pressure oil to the P1 port of the hydraulic selector valve. At this time, there is no pilot oil source at the P1 port to push the valve core to move. The hydraulic selector valve is connected with the P1 port blocked and the B port blocked, and the P2 port connected to the A port. The plunger variable pump 12 provides high-pressure oil to the steering gear to realize the hydraulic power steering function of the steering gear and ensure the mechanical steering priority level.

[0041] This embodiment provides a detailed description of the hydraulic circuit for the electronically controlled axle locking:

[0042] The system also includes a first control valve group 1, a second control valve group left 2, an electric steering shaft one 4, a second control valve group right 9, and an electric steering shaft two 11;

[0043] The P port of the first control valve group 1 is connected to the oil pump and is used to provide steering hydraulic power to the electric steering shaft 4 and the electric steering shaft 11. The T port is used for oil return. The A port of the first control valve group 1 is connected to the A1 port of the left 2 and the right 9 of the second control valve group, respectively. The B port of the first control valve group 1 is connected to the A2 port of the left 2 and the right 9 of the second control valve group. The B1 port of the left 2 and the right 9 of the second control valve group are cross-connected to the rodless chamber and the rod chamber of the steering cylinders 15 on both sides of the electric steering shaft 4 and the electric steering shaft 11. When the left steering cylinder of the same shaft is connected to the rodless chamber, the other side is connected to the rod chamber. The B2 port is cross-connected to the rod chamber and the rodless chamber of the steering cylinders 15 on both sides of the electric steering shaft 4 and the electric steering shaft 11. When the left steering cylinder of the same shaft is connected to the rod chamber, the other side is connected to the rodless chamber.

[0044] The high-pressure oil output from the accumulator 5 enters from the P port of the second control valve group left 2 and the second control valve group right 9, respectively, and is connected to the third control valve group left 3 and the third control valve group right 10. It is used to control the center position locking cylinder 16. The accumulator 5 can provide the high-pressure oil source required for the locking action of the electric axle locking cylinder, realize the center position locking function of the electric axle locking cylinder, and ensure that all the tires of the electric axle are locked in the center position, so as to realize the safe driving of the vehicle.

[0045] In this embodiment, it is further explained that the B port of the third control valve group left 3 and the third control valve group right 10 is connected to the rod chamber of the locking cylinder, and the A port is connected to the rodless chamber of the locking cylinder. The T port of the third control valve group left 3 and the third control valve group right 10 is connected in parallel with the T port of the second control valve group left 2 and the second control valve group right 9 to form a hydraulic circuit.

[0046] In this embodiment, the connection relationship of the electronically controlled axle locking hydraulic circuit mechanical device is as follows: Figure 1 As shown,

[0047] The piston rod end of the steering cylinder 15 is connected to the steering rocker arm 17. One end of the steering rocker arm 17 is connected to the center position locking cylinder 16, and the other end is connected to the steering knuckle arm through the steering tie rod 18. By adding the center position locking cylinder to the disconnected trapezoidal mechanism, the vehicle's center position locking and return-to-center functions are realized.

[0048] A crane comprising the hydraulic system described above.

[0049] The crane in this invention includes the above-mentioned system. When in operation, it reduces the number of steering pumps required for matching the vehicle's oil pump device, thereby reducing costs. At the same time, based on the characteristics of the electronically controlled steering axle, it can be matched with a load-sensitive system to reduce the energy consumption of the hydraulic system and lower the oil temperature. It also enables the centering and return-to-center functions of the electronically controlled steering axle in multi-axle vehicles, improving the safety and reliability of the vehicle's straight-line driving.

[0050] This invention utilizes a constant-pressure variable displacement piston pump in the dual-circuit hydraulic power steering system, where the oil supply circuit with an emergency steering pump shares the oil supply circuit with the center-locking cylinder of the electronic steering shaft. A hydraulically controlled selector valve prioritizes the emergency steering function of the mechanical steering system. When the mechanical steering system does not require emergency steering, the constant-pressure variable displacement piston pump can provide oil for the center-locking of the electronic steering shaft. Simultaneously, a constant-volume accumulator is installed in the center-locking oil circuit of the electronic steering shaft. This improves the response time of tire center-locking and ensures that during emergency steering by the mechanical steering system, the accumulator can provide a high-pressure oil source to the center-locking cylinder of the electronic steering shaft, guaranteeing driving safety and reliability. This arrangement can be applied to multi-axle construction machinery vehicles with load-sensitive electronic steering hydraulic systems, reducing the number of hydraulic pumps, lowering energy consumption, saving space, and improving system stability and reliability.

[0051] 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 hydraulic system for center-position locking of an electronically controlled steering shaft, characterized in that, The system includes: The hydraulic selector valve (6) is connected to a steering oil pump (13) at port P1 and to a plunger variable pump (12) at port P2, providing a high-pressure oil source for the dual-circuit steering system and realizing the hydraulic power steering function of the dual-circuit steering system; the hydraulic selector valve (6) is connected to an accumulator (5) at port B. The accumulator (5) is connected to the hydraulic circuit for locking the axle of the electric vehicle and provides high-pressure oil to achieve the center position locking of the axle center position locking cylinder (16). A dual-circuit steering gear (7), wherein port 1 of the dual-circuit steering gear (7) is connected to port A of the hydraulic selector valve (6); Steering oil pump two (14) is connected to port 1 of another circuit of the dual-circuit steering gear (7), and ports 2 of the dual-circuit steering gear (7) are used for oil return. Mechanical steering shaft (8), the left and right steering cylinders of the mechanical steering shaft (8) are connected to the high pressure port of the dual-circuit steering gear (7) to realize hydraulic power steering of the steering gear; The electronically controlled axle locking hydraulic circuit includes a first control valve group (1), a second control valve group left (2), an electronically controlled steering shaft one (4), a second control valve group right (9), and an electronically controlled steering shaft two (11). The first control valve group (1) has its P port connected to the oil pump and is used to provide steering hydraulic assistance to the first electric steering shaft (4) and the second electric steering shaft (11). The T port is used for oil return. The A port of the first control valve group (1) is connected to the A1 port of the left (2) and right (9) of the second control valve group respectively. The B port of the first control valve group (1) is connected to the A2 port of the left (2) and right (9) of the second control valve group. The B1 port of the left (2) and right (9) of the second control valve group is cross-connected with the rodless and rod chambers of the steering cylinders (15) on both sides of the electric steering shaft one (4) and the electric steering shaft two (11). The B2 port of the left (2) and right (9) of the second control valve group is cross-connected with the rod chamber and rodless chamber of the steering cylinders (15) on both sides of the electric steering shaft one (4) and the electric steering shaft two (11).

2. The hydraulic system for center-position locking of an electronically controlled steering shaft according to claim 1, characterized in that, The high-pressure oil at the output end of the accumulator (5) enters the connected third control valve group left (3) and third control valve group right (10) from the P oil port of the second control valve group left (2) and the second control valve group right (9) respectively, and is used to control the mid-position locking cylinder (16).

3. The hydraulic system for center-position locking of an electronically controlled steering shaft according to claim 2, characterized in that, The B port of the left (3) and right (10) of the third control valve group is connected to the rod chamber of the middle position locking cylinder (16), and the A port is connected to the rodless chamber of the middle position locking cylinder (16).

4. The hydraulic system for center-position locking of an electronically controlled steering shaft according to claim 2, characterized in that, The piston rod end of the steering cylinder (15) is connected to a steering rocker arm (17). One end of the steering rocker arm (17) is connected to a center-position locking cylinder (16), and the other end is connected to a steering knuckle arm via a steering tie rod (18).

5. The hydraulic system for center-position locking of an electronically controlled steering shaft according to claim 2, characterized in that, The T-ports of the left (3) and right (10) of the third control valve group are connected in parallel with the T-ports of the left (2) and right (9) of the second control valve group to form a circuit.

6. The hydraulic system for center-position locking of an electronically controlled steering shaft according to claim 1, characterized in that, The two oil ports of the dual-circuit steering gear (7) form a circuit as the return oil port.

7. A crane, characterized in that, Includes the hydraulic system as described in any one of claims 1-6.

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