1. A steering system of an electric loader based on a hydraulic accumulator and a variable motor is characterized by comprising an oil tank, a first one-way valve, a power supply, a motor controller, an electric motor, a variable pump, the variable motor, an electronic steering wheel, an axial angle encoder, an electric control unit, a second one-way valve, a first electromagnetic directional valve, a second electromagnetic directional valve, a third electromagnetic directional valve, a first overflow valve 15, a fourth electromagnetic directional valve, a third one-way valve, the hydraulic accumulator, a fifth electromagnetic directional valve, a fourth one-way valve, a second overflow valve, a fifth one-way valve, a sixth electromagnetic directional valve, a displacement sensor, a left steering oil cylinder, a right steering oil cylinder, a first pressure sensor and a second pressure sensor;

the electric motor, the variable pump and the variable motor are mechanically connected coaxially; an oil outlet of the variable pump is connected with an oil inlet of the second one-way valve, an oil inlet of the variable pump is connected with an oil outlet of the first one-way valve, and an oil inlet of the first one-way valve is connected with the oil tank; an oil outlet of the second one-way valve is respectively connected with an oil inlet of the first overflow valve and a P port of the fourth electromagnetic directional valve; an oil outlet of the first overflow valve is connected with an oil tank; a T port of the fourth electromagnetic directional valve is connected with an A port of the first electromagnetic directional valve; a T port of the first electromagnetic directional valve is connected with the oil tank, and a B port of the first electromagnetic directional valve is respectively connected with an oil inlet of the variable displacement motor and a B port of the second electromagnetic directional valve; the oil outlet of the variable displacement motor is connected with an oil tank; the port A of the fourth electromagnetic directional valve is respectively connected with the port C of the sixth electromagnetic directional valve, the rodless cavity of the left steering oil cylinder and the rod cavity of the right steering oil cylinder, and the port B of the fourth electromagnetic directional valve is respectively connected with the port D of the sixth electromagnetic directional valve, the rod cavity of the left steering oil cylinder and the rodless cavity of the right steering oil cylinder; a port B of the sixth electromagnetic directional valve is connected with an oil inlet of the third one-way valve, a port A of the sixth electromagnetic directional valve is connected with an oil outlet of the fifth one-way valve, and an oil inlet of the fifth one-way valve is connected with an oil tank; a port A of the fifth electromagnetic directional valve is respectively connected with an oil outlet of the third one-way valve, an oil inlet of the fourth one-way valve, an oil inlet of the second overflow valve and the hydraulic accumulator, and a port B of the fifth electromagnetic directional valve is respectively connected with an oil outlet of the second overflow valve and the oil tank; an oil outlet of the fourth one-way valve is connected with an A port of the second electromagnetic directional valve; the motor is connected with a power supply through a motor controller; the electric control unit is electrically connected with the motor controller, the first electromagnetic directional valve, the second electromagnetic directional valve, the third electromagnetic directional valve, the fourth electromagnetic directional valve, the fifth electromagnetic directional valve and the sixth electromagnetic directional valve; the shaft angle encoder, the displacement sensor, the first pressure sensor and the second pressure sensor for detecting the electronic steering wheel are all connected with the electronic control unit in an electric signal mode; the first pressure sensor is connected with the rod cavity of the left steering oil cylinder and the rodless cavity of the right steering oil cylinder, and the second pressure sensor is connected with the rodless cavity of the left steering oil cylinder and the rod cavity of the right steering oil cylinder.

2. The steering system for an electric loader based on hydraulic accumulator and variable displacement motor of claim 1, wherein said power source is a battery.

3. A steering system for an electric loader based on hydraulic accumulators and variable displacement motors according to claim 1, characterized in that the connections other than the mechanical and electrical connections are oil connections.

4. The steering system of the electric loader based on the hydraulic accumulator and the variable displacement motor as claimed in claim 1, wherein the oil outlet of the fourth one-way valve connected with the port A of the second electromagnetic directional valve is further connected with the port A of the third electromagnetic directional valve, and the port B of the third electromagnetic directional valve is connected with the oil inlet of the variable displacement pump connected with the oil outlet of the first one-way valve.

Background

With the current situation of energy shortage and environmental pollution becoming more serious, the problems of high energy consumption and high emission of engineering machinery become more prominent, and the problems of emission and power consumption of the loader as the engineering machinery with wide application are more and more emphasized by people. The loader is mainly used for loading and transferring bulk materials, the load change range of the steering system is large and the change is frequent in the working process, a large amount of overflow loss is caused, and therefore, the reduction of the energy loss in the steering system of the loader is an important way for improving the energy saving performance of the loader.

In recent years, an energy recovery mechanism is applied to a loader, but a conversion route of an energy recovery system, such as a motor-capacitor-motor-pump, is subjected to energy conversion for many times, and a large amount of energy loss occurs when electric energy and hydraulic energy are converted into each other, which causes a situation that the recovery efficiency is low.

Disclosure of Invention

In view of the above, the present invention is directed to the disadvantages of the prior art, and a primary object of the present invention is to provide a steering system for an electric loader based on a hydraulic accumulator and a variable displacement motor.

In order to achieve the purpose, the invention provides a steering system of an electric loader based on a hydraulic accumulator and a variable motor, which comprises an oil tank, a first one-way valve, a power supply, a motor controller, an electric motor, a variable pump, the variable motor, an electronic steering wheel, an axial angle encoder, an electric control unit, a second one-way valve, a first electromagnetic directional valve, a second electromagnetic directional valve, a third electromagnetic directional valve, a first overflow valve, a fourth electromagnetic directional valve, a third one-way valve, hydraulic energy storage, a fifth electromagnetic directional valve, a fourth one-way valve, a second overflow valve, a fifth one-way valve, a sixth directional valve, a displacement sensor, a left steering oil cylinder, a right steering oil cylinder, a first pressure sensor and a second pressure sensor;

the electric motor, the variable pump and the variable motor are mechanically connected coaxially; an oil outlet of the variable pump is connected with an oil inlet of the second one-way valve, an oil inlet of the variable pump is connected with an oil outlet of the first one-way valve, and an oil inlet of the first one-way valve is connected with the oil tank; an oil outlet of the second one-way valve is respectively connected with an oil inlet of the first overflow valve and a P port of the fourth electromagnetic directional valve; an oil outlet of the first overflow valve is connected with an oil tank; a T port of the fourth electromagnetic directional valve is connected with an A port of the first electromagnetic directional valve; a T port of the first electromagnetic directional valve is connected with the oil tank, and a B port of the first electromagnetic directional valve is respectively connected with an oil inlet of the variable displacement motor and a B port of the second electromagnetic directional valve; the oil outlet of the variable displacement motor is connected with an oil tank; the port A of the fourth electromagnetic directional valve is respectively connected with the port C of the sixth electromagnetic directional valve, the rodless cavity of the left steering oil cylinder and the rod cavity of the right steering oil cylinder, and the port B of the fourth electromagnetic directional valve is respectively connected with the port D of the sixth electromagnetic directional valve, the rod cavity of the left steering oil cylinder and the rodless cavity of the right steering oil cylinder; a port B of the sixth electromagnetic directional valve is connected with an oil inlet of the third one-way valve, a port A of the sixth electromagnetic directional valve is connected with an oil outlet of the fifth one-way valve, and an oil inlet of the fifth one-way valve is connected with an oil tank; a port A of the fifth electromagnetic directional valve is respectively connected with an oil outlet of the third one-way valve, an oil inlet of the fourth one-way valve, an oil inlet of the second overflow valve and the hydraulic accumulator, and a port B of the fifth electromagnetic directional valve is respectively connected with an oil outlet of the second overflow valve and the oil tank; an oil outlet of the fourth one-way valve is connected with an A port of the second electromagnetic directional valve; the motor is connected with a power supply through a motor controller; the electric control unit is electrically connected with the motor controller, the first electromagnetic directional valve, the second electromagnetic directional valve, the third electromagnetic directional valve, the fourth electromagnetic directional valve, the fifth electromagnetic directional valve and the sixth electromagnetic directional valve; the shaft angle encoder, the displacement sensor, the first pressure sensor and the second pressure sensor for detecting the electronic steering wheel are all connected with the electronic control unit in an electric signal mode; the first pressure sensor is connected with the rod cavity of the left steering oil cylinder and the rodless cavity of the right steering oil cylinder, and the second pressure sensor is connected with the rodless cavity of the left steering oil cylinder and the rod cavity of the right steering oil cylinder;

as a modification of the present invention, the power source is a battery.

As an improvement of the invention, an oil outlet of a fourth one-way valve connected with the port A of the second electromagnetic directional valve is also connected with the port A of a third electromagnetic directional valve, and a port B of the third electromagnetic directional valve is connected with an oil inlet of the variable displacement pump connected with the oil outlet of the first one-way valve.

Compared with the prior art, the technical scheme of the invention has the following beneficial effects:

1. the invention provides a steering system of an electric loader based on a hydraulic accumulator and a variable motor, which is characterized in that the variable motor mechanically connected with the motor and a variable pump coaxially is added on an oil return path of the steering system, the variable motor is utilized to recover hydraulic energy on the oil return path back and forth and directly provide torque for the variable pump, the link of energy conversion is reduced, the efficiency of energy conversion is improved, and the power consumption of the motor is further reduced.

2. The invention provides a steering system of an electric loader based on a hydraulic accumulator and a variable motor, which recovers overflow loss caused by external load action when the traditional steering system does not steer, is used for improving the pressure of an oil inlet of a variable pump and an emergency energy source when a motor fails to drive the variable pump, reduces the electric energy consumption of the motor, and improves the working efficiency and the safety performance of the loader.

Drawings

FIG. 1 is a schematic diagram of a steering system of an electric loader based on a hydraulic accumulator and a variable displacement motor according to the present invention;

the attached drawings indicate the following:

1. oil tank 2 and first check valve

3. Power supply 4 and motor controller

5. Motor 6, variable displacement pump

7. Variable displacement motor 8 and electronic steering wheel

9. Shaft encoder 10 and electronic control unit

11. Second one-way valve 12 and first electromagnetic directional valve

13. Second electromagnetic directional valve 14, third electromagnetic directional valve

15. First overflow valve 16 and fourth electromagnetic directional valve

17. Third check valve 18, hydraulic accumulator

19. Fifth electromagnetic directional valve 20, fourth check valve

21. Second overflow valve 22, fifth check valve

23. Sixth electromagnetic directional valve 24, displacement sensor

25. Left steering oil cylinder 26 and right steering oil cylinder

27. First pressure sensor 28, second pressure sensor

Detailed Description

The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention; it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments, and all other embodiments obtained by those skilled in the art without any inventive work are within the scope of the present invention.

In the description of the present invention, it should be noted that the terms "upper", "lower", "inner", "outer", "top/bottom", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplification of description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "disposed," "sleeved/connected," "connected," and the like, are used in a broad sense, and for example, "connected" may be a wall-mounted connection, a detachable connection, an integral connection, a mechanical connection, an electrical connection, a direct connection, an indirect connection through an intermediate medium, and a communication between two elements, and those skilled in the art will understand the specific meaning of the terms in the present invention specifically.

Referring to fig. 1, a specific structure of a preferred embodiment of the present invention is shown, which includes an oil tank 1, a first check valve 2, a power supply 3, a motor controller 4, an electric motor 5, a variable pump 6, a variable motor 7, an electronic steering wheel 8, an axial angle encoder 9, an electronic control unit 10, a second check valve 11, a first electromagnetic directional valve 12, a second electromagnetic directional valve 13, a third electromagnetic directional valve 14, a first overflow valve 15, a fourth electromagnetic directional valve 16, a third check valve 17, a hydraulic accumulator 18, a fifth electromagnetic directional valve 19, a fourth check valve 20, a second overflow valve 21, a fifth check valve 22, a sixth electromagnetic directional valve 23, a displacement sensor 24, a left steering cylinder 25, a right steering cylinder 26, a first pressure sensor 27, and a second pressure sensor 28; wherein:

the electric motor 5, the variable pump 6 and the variable motor 7 are mechanically connected coaxially; an oil outlet of the variable pump 6 is connected with an oil inlet of the second one-way valve 11, an oil inlet of the variable pump 6 is connected with an oil outlet of the first one-way valve 2, and an oil inlet of the first one-way valve 2 is connected with the oil tank 1; an oil outlet of the second check valve 11 is respectively connected with an oil inlet of the first overflow valve 15 and a P port of the fourth electromagnetic directional valve 16; an oil outlet of the first overflow valve 15 is connected with the oil tank 1; a port T of the fourth electromagnetic directional valve 16 is connected with a port A of the first electromagnetic directional valve 12; a T port of the first electromagnetic directional valve 12 is connected with the oil tank 1, and a B port of the first electromagnetic directional valve 12 is respectively connected with an oil inlet of the variable motor 7 and a B port of the second electromagnetic directional valve 13; the oil outlet of the variable displacement motor 7 is connected with the oil tank 1; the port A of the fourth electromagnetic directional valve 16 is respectively connected with the port C of the sixth electromagnetic directional valve 23, the rodless cavity of the left steering oil cylinder 25 and the rod cavity of the right steering oil cylinder 26, and the port B of the fourth electromagnetic directional valve 16 is respectively connected with the port D of the sixth electromagnetic directional valve 23, the rod cavity of the left steering oil cylinder 25 and the rodless cavity of the right steering oil cylinder 26; a port B of the sixth electromagnetic directional valve 23 is connected with an oil inlet of the third one-way valve 17, a port A of the sixth electromagnetic directional valve 23 is connected with an oil outlet of the fifth one-way valve 22, and an oil inlet of the fifth one-way valve 22 is connected with the oil tank 1; a port A of a fifth electromagnetic directional valve 19 is respectively connected with an oil outlet of the third one-way valve 17, an oil inlet of the fourth one-way valve 20, an oil inlet of the second overflow valve 21 and the hydraulic energy accumulator 18, and a port B of the fifth electromagnetic directional valve 19 is respectively connected with an oil outlet of the second overflow valve 21 and the oil tank 1; an oil outlet of the fourth one-way valve 20 is connected with an A port of the second electromagnetic directional valve 13; the motor 5 is connected with the power supply 1 through the motor controller 4; the electric control unit 10 is electrically connected with the motor controller 4, the first electromagnetic directional valve 12, the second electromagnetic directional valve 13, the third electromagnetic directional valve 14, the fourth electromagnetic directional valve 16, the fifth electromagnetic directional valve 19 and the sixth electromagnetic directional valve 23; the shaft angle encoder 9, the displacement sensor 24, the first pressure sensor 27 and the second pressure sensor 28 which are used for detecting the rotation angle of the electronic steering wheel 8 are all connected with the electronic control unit 10 in an electric signal mode; a first pressure sensor 27 is connected to the rod chambers of the left steering cylinder 25 and the rod chambers of the right steering cylinder 26, and a second pressure sensor 28 is connected to the rod chambers of the left steering cylinder 25 and the rod chambers of the right steering cylinder 26.

In this embodiment, the power supply 3 employs a battery.

The steering system is connected by oil passages except for mechanical connection and electric signal connection.

In this embodiment, in order to improve the working performance of the variable displacement pump 6, an oil outlet of a fourth check valve 20 connected with an opening a of the second electromagnetic directional valve 13 is further connected with an opening a of a third electromagnetic directional valve 14, and an opening B of the third electromagnetic directional valve 14 is connected with an oil inlet of the variable displacement pump 6 connected with an oil outlet of the first check valve 2.

In the working process, the hydraulic accumulator 18 is used as a high-pressure oil source, and the stored hydraulic pressure is directly released to the oil inlet of the variable pump 6, so that the pressure of the oil inlet of the variable pump 6 is increased, namely the pressure difference of the oil at the inlet and the outlet of the variable pump 6 is reduced, and the torque output of the motor is reduced. The first check valve 2 can ensure that the high-pressure oil released by the hydraulic accumulator flows to a certain direction, so that the high-pressure oil cannot flow back to the oil tank.

In this embodiment, when the electronic steering wheel 8 rotates, the shaft encoder 9 collects a rotation angle signal of the electronic steering wheel 8 and transmits the rotation angle signal to the electronic control unit 10, the displacement sensor 24 also synchronously transmits a displacement signal of the steering cylinder to the electronic control unit 10, the electronic control unit 10 converts the transmitted rotation angle signal and the transmitted displacement signal in real time, and controls the power-on and power-off states of the electromagnet of the fourth electromagnetic directional valve 16 according to the difference between the rotation angle signal and the displacement signal. When the electronic steering wheel 8 is rotated to the left and the difference value is not zero, the left electromagnet of the fourth electromagnetic directional valve 16 is powered on, the right electromagnet is powered off, at the moment, the fourth electromagnetic directional valve 16 works at the left position, the piston rod of the left steering oil cylinder 25 retracts, the piston rod of the right steering oil cylinder 26 extends, and the loader turns to the left; when the electronic steering wheel 8 is rotated rightwards and the difference value is not zero, the right electromagnet of the fourth electromagnetic directional valve 16 is powered on, the left electromagnet is powered off, at the moment, the fourth electromagnetic directional valve 16 works at the right position, the piston rod of the left steering oil cylinder 25 extends out, the piston rod of the right steering oil cylinder 26 retracts, and the loader turns rightwards; when the difference value between the rotation angle signal and the displacement signal converted and transmitted in real time by the electronic control unit 10 is zero, the left and right electromagnets of the fourth electromagnetic directional valve 16 lose power at the same time, at this time, the valve core of the fourth electromagnetic directional valve 16 returns to the middle position, and the loader stops steering. Meanwhile, the electric control unit 10 controls the displacement of the variable displacement pump 6 according to the rotating speed of the electronic steering wheel 8, so that the steering state of the whole vehicle is realized to follow the rotating state of the electronic steering wheel 8, and the energy saving performance and the controllability of the system are improved. And the electric control unit 10 sends a control signal to the first electromagnetic directional valve 12 to control the power-on and power-off states of the electromagnet of the first electromagnetic directional valve 12, when the electromagnet of the first electromagnetic directional valve 12 is powered on, the return oil directly returns to the oil tank, when the electromagnet of the first electromagnetic directional valve 12 is powered off, the return oil passes through the variable displacement motor 7, and meanwhile, the electric control unit 10 controls the output power of the variable displacement motor 7 by controlling the displacement of the variable displacement motor 7.

In this embodiment, when one of the left and right electromagnets of the fourth electromagnetic directional valve 16 is powered, that is, the spool thereof is not in the neutral position, both the left and right electromagnets of the sixth electromagnetic directional valve 23 will be in the power-off state, and the highest safety pressure of the steering system is controlled by the first overflow valve 15; when the left and right electromagnets of the fourth electromagnetic directional valve 16 are in a power-off state, that is, the spool thereof is in a neutral position, the electronic control unit 10 collects pressure signals of the rod chambers and the rod-free chambers of the left steering cylinder 25 and the right steering cylinder 26 through the first pressure sensor 27 and the second pressure sensor 28, and controls the power-on and power-off of the left and right electromagnets of the sixth electromagnetic directional valve 26 through the comparison with the set highest system safety pressure. When the oil pressure detected by the first pressure sensor 27 is higher than the highest safety pressure of the system, the right electromagnet of the sixth electromagnetic directional valve 23 is electrified, the port C is communicated with the port A, and the port D is communicated with the port B, then the high-pressure oil in the rod cavity of the left steering oil cylinder 25 and the rod-free cavity of the right steering oil cylinder 26 is stored in the hydraulic accumulator 18 through the oil way D-B of the sixth electromagnetic directional valve 23 and the third one-way valve 17, and the supplementary oil from the oil tank 1 through the oil way A-B of the fifth one-way valve 22 and the oil way A-B of the sixth electromagnetic directional valve 23 is obtained from the rod-free cavity of the left steering oil cylinder 25 and the rod cavity of the right steering oil cylinder 26; when the oil pressure detected by the second pressure sensor 28 is higher than the highest safety pressure of the system, the left electromagnet of the sixth electromagnetic directional valve 23 is energized, the port C is communicated with the port B, and the port D is communicated with the port a, so that the high-pressure oil in the rodless chamber of the left steering cylinder 25 and the rod chamber of the right steering cylinder 26 is stored in the hydraulic accumulator 18 through the oil passages C-B of the sixth electromagnetic directional valve 23 and the third check valve 17, and the rod chamber of the left steering cylinder 25 and the rodless chamber of the right steering cylinder 26 are supplied with the supplementary oil from the oil tank 1 through the oil passages a-D of the fifth check valve 22 and the sixth electromagnetic directional valve 23. And the second overflow valve 21 connected with the hydraulic accumulator 18 is used for limiting the highest oil filling pressure of the hydraulic accumulator 18, and the fifth electromagnetic directional valve 19 connected with the hydraulic accumulator 18 is used for unloading the high-pressure oil of the hydraulic accumulator.

In this embodiment, when the electric motor 5 fails, that is, the variable displacement pump 6 loses power, the electronic control unit 10 controls the electromagnet of the second electromagnetic directional valve 13 to be powered on, the port a of the second electromagnetic directional valve is communicated with the port B, at this time, the hydraulic accumulator 18 serves as an emergency power source, and high-pressure oil of the hydraulic accumulator drives the variable displacement motor 7 to rotate through the fourth check valve 20 and the oil passages a-B of the second electromagnetic directional valve 13, so as to drive the variable displacement pump 6 to work, and realize steering in an emergency state.

The above description is only a preferred embodiment of the present invention, but the design concept of the present invention is not limited thereto, and any person skilled in the art can make insubstantial changes in the technical scope of the present invention within the technical scope of the present invention, and the actions infringe the protection scope of the present invention are included in the present invention.