Electric hydraulic power-assisted steering system of forklift

Abstract

The utility model relates to an electric hydraulic power-assisted steering system of a forklift, which is characterized in that the forklift is provided with an original hydraulic system, the original hydraulic system is connected with a hydraulic oil cylinder through an original oil path, and the electric hydraulic power-assisted steering system comprises a steering angle sensor used for detecting and outputting angle information; the second electronic control unit is used for receiving the angle information from the rotation angle sensor and forwarding the angle information to the first electronic control unit, and when the angle information is larger than a threshold value, the second electronic control unit firstly closes an original hydraulic system and then forwards the angle information to the first electronic control unit; the first electronic control unit is used for closing the power steering pump or adjusting the rotating speed of the steering pump according to the angle information from the second electronic control unit; the utility model has the beneficial effects that the operation efficiency of the steering system can be effectively improved, the structure is reliable, the energy is saved, the maintenance is convenient, and the steering sensitivity is improved.

Description

Technical Field

[0001] The utility model relates to the field of aircraft testing, in particular to an electric hydraulic power steering system for a forklift. Background Art

[0002] Forklifts typically use hydraulic power steering or fully hydraulic steering. Turning the steering wheel activates the steering gear, which in turn is driven by a hydraulic pump. This pressure builds up in the steering gear, pushing the hydraulic cylinder to achieve steering. Traditional forklifts use a single hydraulic pump to provide pressure for both the steering gear and other lifting systems. These pressures often differ, or require the installation of additional components such as a steering priority valve. This complicates the hydraulic system, and the pump constantly needs to operate, leading to high levels of ineffective pressure relief in the oil circuit and significant energy waste.

[0003] Forklifts are placing increasingly stringent demands on their steering systems, requiring precise steering while also ensuring reliable performance, no malfunctions, a long service life, and ease of maintenance. Therefore, a forklift electric hydraulic power steering system is proposed that effectively improves the steering system's operating efficiency, features a reliable structure, conserves energy, facilitates maintenance, and enhances steering sensitivity. Utility Model Content

[0004] The purpose of the utility model is to overcome the deficiencies of the prior art and provide an electric hydraulic power steering system for forklifts. By setting up an electric hydraulic power steering system, the operating efficiency of the steering system can be effectively improved, and the structure is reliable, energy-saving, easy to maintain, and at the same time conducive to improving steering sensitivity.

[0005] The purpose of this utility model is achieved through the following technical solutions:

[0006] A forklift electric hydraulic power steering system, the vehicle is provided with an original hydraulic system, the original hydraulic system is connected to the hydraulic cylinder via a crude oil line, and is characterized in that the electric hydraulic power steering system includes:

[0007] Angle sensor, used to detect and output angle information;

[0008] a second electronic control unit, configured to receive angle information from the rotation angle sensor and forward the angle information to the first electronic control unit, wherein when the angle information is greater than a threshold, the second electronic control unit first shuts down the original hydraulic system and then forwards the angle information to the first electronic control unit;

[0009] Electronic control unit 1, for shutting down the power steering pump or adjusting the speed of the steering pump according to the angle information from electronic control unit 2;

[0010] The oil inlet of the power steering pump is connected to the hydraulic cylinder via a hydraulic oil pipe a, and the oil outlet of the power steering pump is connected to the steering cylinder via a steering gear, so as to form an oil supply pipeline for supplying oil to the steering cylinder and provide steering oil pressure.

[0011] In this solution, the power steering pump, as an independent power component, can independently establish oil pressure for the steering system, which can help save energy and avoid the problem of energy waste caused by traditional forklifts using one hydraulic oil pump to provide oil pressure for the steering gear and pressure for other lifting working systems at the same time.

[0012] In addition, this solution uses two electronic control units, which are connected in series. Only when both controllers respond to the steering command in turn can the steering action be executed, thereby improving the safety of the system.

[0013] In a preferred embodiment of this scheme, the steering gear is equipped with an oil return port, a high-pressure port, an output port 1, and an output port 2. The oil outlet of the steering pump is connected to the high-pressure port of the steering gear via a hydraulic oil pipe f; the oil return port of the steering gear is connected to the oil return port of the hydraulic cylinder via an oil return line; the output port 2 and output port 1 are correspondingly connected to the hydraulic oil port 1 and hydraulic oil port 2 of the steering cylinder. The two hydraulic oil ports of the steering cylinder always have one port for oil inlet and the other for oil outlet.

[0014] In a preferred embodiment of this solution, the output port 1 is connected to the hydraulic oil interface 2 through the hydraulic oil return line b, and the output port 2 is connected to the hydraulic oil interface 1 through the hydraulic oil pipe g.

[0015] In a preferred embodiment of this solution, the steering gear is further provided with a pressure relief port, which is connected to the hydraulic cylinder through a pipeline.

[0016] In a preferred embodiment of this scheme, the return oil port is connected to the first interface of the three-way valve through the hydraulic oil pipe c, the pressure relief port is connected to the second interface of the three-way valve through the hydraulic oil pipe d, and the three-way valve outlet is connected to the return oil pipeline of the hydraulic cylinder through the hydraulic oil pipe e.

[0017] In a preferred embodiment of the present scheme, the angle sensor is installed on the steering column to detect the angle change of the steering wheel; a cross-axis universal joint is provided at the bottom of the steering column, and an involute internal spline is provided at the bottom of the cross-axis universal joint, which cooperates with the external spline shaft of the steering gear.

[0018] In a preferred embodiment of this solution, the drive motor of the power steering pump is electrically connected to a battery on the forklift.

[0019] The beneficial effects of the present invention are as follows: (1) a dedicated power steering pump is added to the new electric hydraulic power steering system of a forklift in the present invention to provide oil pressure for the steering system of the forklift. The time and flow of establishing the oil pressure are controlled by the electronic control unit, which can accurately control the operation of the power steering pump and improve the steering sensitivity. Compared with the traditional forklift steering system, the energy saving effect is obvious and it is more conducive to extending the service life of the equipment;

[0020] (2) This solution uses two electronic control units, electronic control unit 1 and electronic control unit 2, which are connected in series. When the two controllers respond to the steering command at the same time, the steering action can be executed, which improves the safety of the system and helps to ensure reliable performance and prevent malfunction. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the overall structure of the utility model;

[0022] Figure 2 It is a schematic diagram of the connection between two electronic control units of the present invention;

[0023] Figure 3 Schematic diagram of the connection between the steering column and the steering gear;

[0024] Figure 4 This is a schematic diagram of the connection between the hydraulic actuator and the power steering pump;

[0025] Figure 5 Installation diagram of steering cylinder;

[0026] Figure 6 This is a connection diagram of a tee connector. DETAILED DESCRIPTION

[0027] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings, but the protection scope of the present invention is not limited to the following.

[0028] like Figures 1-4 As shown, a forklift electric hydraulic power steering system is provided. The vehicle is provided with an original hydraulic system. The original hydraulic system is connected to the hydraulic cylinder 4 through a crude oil line to provide pressure for the lifting working system. The electric hydraulic power steering system includes a power steering pump 5, a steering cylinder 6, an electronic control unit 1 7, and an electronic control unit 2 8.

[0029] Among them, the oil outlet of the steering pump 5 is connected to the steering cylinder 6 through the steering gear 3, and the oil inlet of the steering pump 5 is connected to the hydraulic cylinder 4 through the hydraulic oil pipe a15. That is, the original hydraulic cylinder 4 is used as a hydraulic station, that is, the lifting oil pressure is provided to the original hydraulic system through the original oil circuit, and the steering oil pressure can also be established for the steering system through the hydraulic oil pipe a15.

[0030] In this embodiment, since the steering pump 5 is an independently arranged power element, the steering pump 5 can independently establish oil pressure for the steering system according to the steering requirements. Therefore, this solution can avoid the problem of energy waste caused by traditional forklifts using one hydraulic oil pump to provide oil pressure for the steering gear and pressure for other lifting working systems at the same time.

[0031] At the same time, in this embodiment, an electronic control unit 2 8 is provided to receive the angle information from the rotation angle sensor 22. The electronic control unit 2 8 analyzes the angle information. When the angle information is less than a threshold value, the electronic control unit 2 8 forwards the angle information to the electronic control unit 1 7. When the angle information is greater than the threshold value, the electronic control unit 2 8 first turns off the power supply of the original hydraulic system and then forwards the angle information to the electronic control unit 1 7. This prioritizes the oil supply to the forklift's steering system, thereby achieving precise steering, while ensuring reliable performance, no malfunction, and a long service life.

[0032] refer to Figure 3 、 Figure 5 As shown, in this embodiment, the steering gear 3 is equipped with an oil return port 31, a high-pressure port 32, an output port 1 33, and an output port 2 34. The oil outlet of the steering pump 5 is connected to the high-pressure port 33 of the steering gear 3 via a hydraulic oil pipe f10. The oil return port 31 of the steering gear 3 is connected to the oil return port of the hydraulic cylinder 4 via a return oil line 41. The output port 1 33 is connected to the hydraulic oil port 2 62 via a hydraulic return oil line b12, and the output port 2 34 is connected to the hydraulic oil port 1 61 via a hydraulic oil pipe g11. The two hydraulic oil ports of the steering cylinder 6 always have one port for oil inlet and the other for oil outlet. The pressure relief port 35 is connected to the hydraulic cylinder 4 via a pipe.

[0033] refer to Figure 1 、 Figure 4 、 Figure 6 As shown, in this embodiment, the return oil port 31 is connected to the first interface of the three-way valve 91 through the hydraulic oil pipe c9, and the outlet of the three-way valve 91 is connected to the return oil pipeline 41 of the hydraulic cylinder 4 through the hydraulic oil pipe e14; the pressure relief port 35 is connected to the second interface of the three-way valve 91 through the hydraulic oil pipe d13.

[0034] refer to Figure 3 As shown, the electric hydraulic power steering system also includes a steering column 2, and a cross-axis universal joint 21 is provided at the bottom of the steering column 2; the bottom of the cross-axis universal joint 21 is provided with an involute internal spline, which cooperates with the external spline shaft of the steering gear 3 to reliably transmit torque.

[0035] refer to Figure 3 、 Figure 4As shown, a steering angle sensor 22 is mounted on the steering column 2 to detect changes in the steering wheel angle. The steering angle sensor 22 is connected in series with control unit 1 7 and control unit 2 8 . Control unit 1 7 is electrically connected to the dynamic rotary pump 5 to control it to build pressure for the steering system. Control unit 2 8 is electrically connected to the original hydraulic system. It should be noted that the original hydraulic system is a common structure found in conventional forklifts and is not detailed in this embodiment.

[0036] refer to Figure 5 As shown, the steering cylinder 6 serves as an execution unit, and there are hydraulic oil interface 1 61 and hydraulic oil interface 2 62 on the cylinder body, which are correspondingly connected to the two oil chambers inside the steering cylinder 6. By pressurizing different interfaces, the reciprocating motion of the piston rod of the steering cylinder 6 can be realized, thereby driving the steering axle to move and achieving the purpose of steering.

[0037] Optional, reference Figure 4 The hydraulic oil pipe a15 supplies oil to the power steering pump 5, and the return oil pipe 41 of the hydraulic oil tank 4 can also serve as the return oil pipe for the steering system and other hydraulic systems.

[0038] In this embodiment, the driving motor of the power steering pump 5 is powered by a battery on the forklift.

[0039] refer to Figure 1 、 Figures 3-5 The electric power steering system hydraulic oil pipe connection method of this embodiment is specifically the following six pipelines:

[0040] First, the oil return port 31 - hydraulic oil pipe c9 - three-way valve 91 - hydraulic oil pipe e14 - oil return line 41 of the hydraulic oil tank 4;

[0041] Second, high-pressure port 32 — hydraulic oil pipe f10 — power steering pump 5;

[0042] Third, output port 1 33 - hydraulic oil pipe b12 - steering cylinder 6;

[0043] Fourth, output port 2 34 - hydraulic oil pipe g11 - steering cylinder 6;

[0044] Fifth, pressure relief port 35 - hydraulic oil pipe d13 - three-way valve 91;

[0045] Sixth, hydraulic oil tank 4——hydraulic oil pipe a15——power steering pump 5.

[0046] refer to Figure 4 One end of the steering cylinder 6 is fixed on the drive axle housing, and the other end is fixed on the steering knuckle.

[0047] The electro-hydraulic steering system operates as follows: When the driver turns the steering wheel 1, the steering angle sensor 22 detects the change in steering angle and outputs a signal to the electronic control unit 8. The electronic control unit 8 controls the operation of other hydraulic systems in the vehicle based on preset thresholds. The angle information is then forwarded to the electronic control unit 1 7. The steering column 2 transmits torque to the steering gear 3. The electronic control unit 7 determines the steering action and controls the dynamic pump 5 to build pressure for the steering system. Output port 1 33 and output port 2 34 then perform a fluid inlet and return action. If hydraulic oil pipe g11 is inlet, hydraulic oil pipe b12 is return, causing the steering cylinder 6 to extend, rotating the wheel. Otherwise, the steering cylinder 6 compresses, rotating the wheel in the opposite direction. If the pressure inside the steering gear 3 exceeds the set value, the pressure relief port 35 opens, returning the hydraulic oil to the hydraulic tank 4 through the pipeline.

[0048] It should be noted that the original hydraulic system is a conventional hydraulic system of existing forklifts, which is used to provide pressure for the lifting working system and will not be elaborated in detail in this solution.

[0049] The above description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein and should not be construed as excluding other embodiments. Instead, the present invention can be used in various other combinations, modifications, and environments and can be modified within the scope of the concept described herein through the above teachings or techniques or knowledge in the relevant fields. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention are intended to be protected by the claims appended hereto.

Claims

1. An electric hydraulic power steering system for a forklift, comprising a vehicle; the vehicle is provided with an original hydraulic system, the original hydraulic system is connected to a hydraulic oil cylinder (4) via a crude oil line, and is characterized in that: The electric hydraulic power steering system comprises: Angle sensor (22), used for detecting and outputting angle information; The second electronic control unit (8) is used to receive angle information from the rotation angle sensor (22) and forward the angle information to the first electronic control unit (7), wherein when the angle information is greater than a threshold value, the second electronic control unit (8) first shuts down the original hydraulic system and then forwards the angle information to the first electronic control unit (7); An electronic control unit 1 (7) is used to shut down the power steering pump (5) or adjust the speed of the steering pump (5) according to the angle information from the electronic control unit 2 (8); The oil inlet of the power steering pump (5) is connected to the hydraulic cylinder (4) via a hydraulic oil pipe a (15), and the oil outlet of the power steering pump (5) is connected to the steering cylinder (6) via a steering gear (3), so as to form an oil supply pipeline for supplying oil to the steering cylinder (6) and provide steering oil pressure.

2. The electric hydraulic power steering system for a forklift according to claim 1, characterized in that: The steering gear (3) is provided with an oil return port (31), a high pressure port (32), an output port 1 (33), and an output port 2 (34); The oil outlet of the steering pump (5) is connected to the high-pressure port (32) of the steering gear (3) through the hydraulic oil pipe f (10); The oil return port (31) of the steering gear (3) is connected to the oil return port of the hydraulic cylinder (4) via the oil return pipeline (41); The output port 2 (34) and the output port 1 (33) are correspondingly connected to the hydraulic oil interface 1 (61) and the hydraulic oil interface 2 (62) of the steering cylinder (6).

3. The electric hydraulic power steering system for a forklift according to claim 2, characterized in that: The output port 1 (33) is connected to the hydraulic oil interface 2 (62) via the hydraulic oil return line b (12), and the output port 2 (34) is connected to the hydraulic oil interface 1 (61) via the hydraulic oil pipe g (11).

4. The electric hydraulic power steering system for a forklift according to claim 2, characterized in that: The steering gear (3) is further provided with a pressure relief port (35), which is connected to the hydraulic cylinder (4) through a pipeline.

5. The electric hydraulic power steering system for a forklift according to claim 4, characterized in that: The oil return port (31) is connected to the first interface of the three-way valve (91) via the hydraulic oil pipe c (9), the pressure relief port (35) is connected to the second interface of the three-way valve (91) via the hydraulic oil pipe d (13), and the outlet of the three-way valve (91) is connected to the oil return line (41) of the hydraulic cylinder (4) via the hydraulic oil pipe e (14).

6. The electric hydraulic power steering system for a forklift according to claim 5, characterized in that: The steering angle sensor (22) is mounted on the steering column (2) to detect the angle change of the steering wheel; A cross-axis universal joint (21) is provided at the bottom of the steering column (2), and an involute internal spline is provided at the bottom of the cross-axis universal joint (21). The involute internal spline cooperates with the external spline shaft of the steering gear (3).

7. The electric hydraulic power steering system for a forklift according to claim 6, characterized in that: The driving motor of the power steering pump (5) is electrically connected to the battery on the forklift.

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