CN114606995B - Electric hydraulic system and loader - Google Patents

Abstract

The invention discloses an electric hydraulic system and a loader, wherein the electric hydraulic system comprises a closed hydraulic system for realizing lifting and descending of a movable arm and a hydraulic system for realizing steering of the whole loader and action of a tipping bucket oil cylinder, the closed hydraulic system maintains volume difference of large and small cavities of the movable arm oil cylinder through a gear pump and an energy accumulator, a motor M1 drives a bidirectional pump-motor to act, the closed hydraulic system is connected with an inverter through a motor controller M1, the inverter is connected with a common direct current bus, and the movable arm potential energy recovery of the electric loader is realized by utilizing an electric control technology of the inverter and the common direct current bus, so that the cruising ability of the electric loader is improved. The invention solves the problems of high energy loss and limited cruising ability of the loader in the prior art.

Description

An electro-hydraulic system and loader

technical field

The invention relates to an electrohydraulic system and a loader, belonging to the technical field of engineering machinery.

Background technique

In the prior art, the hydraulic system of a loader is generally composed of a working hydraulic system and a steering hydraulic system, and the realization forms of the working hydraulic system are all open systems, ranging from quantitative hydraulic systems, fixed variable hydraulic systems to full variable hydraulic systems. The quantitative hydraulic hydraulic system has high pressure overflow loss; the fixed variable hydraulic system realizes variable when turning, but it is still used as a quantitative system when working, and there is also overflow loss; the full variable hydraulic system realizes variable when turning and working, However, the hydraulic system is complex, and the cost of manufacturing and maintenance is relatively high.

In order to achieve the goal of "dual carbon", green new energy technologies have also been born in construction machinery, especially for loaders, which have promoted the development of new green technologies such as "hydrostatic drive" and "pure electric drive". However, the hydraulic system of the electric loader is still basically consistent with the hydraulic system of the fuel vehicle, and the problem of energy loss has not been better solved. At the same time, electric loaders are limited by their battery life, so there is no comprehensive promotion and application in the market.

Contents of the invention

In order to solve the deficiencies of the prior art, the object of the present invention is to provide an electro-hydraulic system and a loader, which solve the problems of high energy consumption and limited battery life of the loader in the prior art.

In order to achieve the above object, the present invention adopts the following technical solutions:

An electro-hydraulic system, including a closed hydraulic system that realizes boom lifting and lowering, and the closed hydraulic system includes a bidirectional two-speed pump-motor, an accumulator, a first electromagnetic reversing valve, a first one-way valve, a second Check valve, second electromagnetic reversing valve, boom hydraulic cylinder, gear pump, third electromagnetic reversing valve, hydraulic oil tank, motor M1, second joystick;

The oil ports of the large and small chambers of the boom hydraulic cylinder are respectively connected with the oil outlets of the third electromagnetic reversing valve and the second electromagnetic reversing valve, and the oil inlets of the second electromagnetic reversing valve and the third electromagnetic reversing valve are respectively connected with the two-way The two-speed pump-motor A and B ports are connected;

The oil inlet of the gear pump is connected to the hydraulic oil tank, the oil outlet of the gear pump is connected to the oil inlet of the first electromagnetic reversing valve, and the oil outlet of the gear pump is connected to the A port of the two-way two-speed pump-motor through the first check valve. The oil outlet is also connected to the B port of the two-way two-speed pump-motor through the second one-way valve, and the oil outlet of the first electromagnetic reversing valve is connected to the accumulator;

The motor M1 drives the two-way two-speed pump-motor action, and the inverter is connected to the inverter through the M1 motor controller, and the inverter is connected to the public DC bus;

The second joystick is used to realize the lifting and lowering of the boom.

Further, the aforementioned two-way two-speed pump-motor includes a reversing valve. When the B port of the two-way two-speed pump-motor is under high pressure, the reversing valve is in the second working position, so that only the single pump of the two-way two-speed pump-motor is in the working state ; When port B of the two-way two-speed pump-motor is at low pressure, the reversing valve is in the first working position, so that the two motors of the two-way two-speed pump-motor are in working condition at the same time.

Further, the foregoing also includes a first relief valve, the oil inlet of the first relief valve is connected to the oil outlet of the gear pump, and the oil outlet of the first relief valve communicates with the hydraulic oil tank.

Further, the foregoing also includes a second relief valve, a third one-way valve and a fifth one-way valve, and the oil inlet of the second relief valve is respectively connected to the bidirectional two-speed pump through the third one-way valve and the fifth one-way valve - A and B ports of the motor.

Further, the foregoing also includes a power battery, and the power battery is connected to a common DC bus.

Further, the foregoing also includes a hydraulic system that realizes the steering of the whole machine and the operation of the dump cylinder. The hydraulic system includes a hydraulic pump, a priority valve, an electric proportional reversing valve, a steering hydraulic cylinder, a dump hydraulic cylinder, a first joystick, and a steering sensor. hydraulic steering gear,

The oil inlet port P of the priority valve is connected to the oil outlet port of the hydraulic pump, the first working oil port CF port of the priority valve is connected to the oil inlet port of the hydraulic steering gear, and the oil outlet port of the hydraulic steering gear is connected to the steering hydraulic cylinder;

The second working oil port EF port of the priority valve is connected with the oil inlet port of the electric proportional directional valve, and the two working oil ports of the electric proportional directional valve are respectively connected with the big and small chambers of the hydraulic cylinder of the dump bucket, and the return port of the electric proportional directional valve The oil port is connected with the hydraulic oil tank;

The first joystick controls the action of the electric proportional reversing valve.

Further, the foregoing also includes a motor M2 for driving the hydraulic pump, the motor M2 is connected to an inverter through the M2 motor controller, and the inverter is connected to the common DC bus.

Further, the foregoing also includes a motor M3 that provides power for the walking system, the motor M3 is connected to an inverter through the M3 motor controller, and the inverter is connected to a common DC bus.

Further, the foregoing also includes a complete machine control unit ECU, which is respectively connected to the M1 motor controller, the M2 motor controller, the M3 motor controller, the first electromagnetic reversing valve, the second electromagnetic reversing valve, and the third electromagnetic reversing valve. Electromagnetic reversing valve, electric proportional reversing valve, first joystick, second joystick and steering sensor of hydraulic steering gear.

A loader, comprising any one of the electro-hydraulic systems described above.

The beneficial effect that the present invention reaches:

1. The lifting and lowering of the boom adopts a closed hydraulic system, which greatly reduces the problem of high energy consumption. At the same time, when certain conditions are met, the gear pump reduces the speed to further reduce power consumption;

2. The potential energy of the boom is recovered by the lowering of the boom, and the electric control technology of the inverter and the public DC bus is used to realize the recovery of the potential energy of the boom of the electric loader and improve the battery life of the electric loader.

Description of drawings

Fig. 1 is the structural representation of the hydraulic system of the embodiment of the present invention;

Fig. 2 is a schematic diagram of the connection of the complete machine control unit ECU according to the embodiment of the present invention.

The meanings of reference signs in the figure: 1-power battery; 2-bidirectional two-speed pump-motor; 3-accumulator; 4-first electromagnetic reversing valve; 5-first one-way valve; 6-second one-way valve Directional valve; 7-first overflow valve; 8-third one-way valve; 9-second electromagnetic reversing valve; 10-second overflow valve; 11-boom hydraulic cylinder; 12-gear pump; 13- Reversing valve; 14-fourth one-way valve; 15-third electromagnetic reversing valve; 16-hydraulic pump; 17-priority valve; 18-electric proportional reversing valve; 19-hydraulic steering gear; 20-steering hydraulic cylinder ; 21-dipping bucket hydraulic cylinder; 22-hydraulic oil tank; 23-the fifth one-way valve.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings. The following examples are only used to illustrate the technical solution of the present invention more clearly, but not to limit the protection scope of the present invention.

Fig. 1 shows a schematic structural diagram of the hydraulic system of this embodiment. The hydraulic system of this embodiment includes a closed hydraulic system for lifting and lowering the boom, and a hydraulic system for steering the whole machine and actuating the dump cylinder.

The hydraulic system to realize the steering of the whole machine and the action of the dump cylinder, including the steering hydraulic cylinder 20 for driving the wheels to steer, the hydraulic steering gear 19 to realize the steering of the steering cylinder, the priority valve 17, the hydraulic pump 16, the electric proportional reversing valve 18, and the dump hydraulic cylinder 21 ; the hydraulic pump 16 that provides hydraulic fluid for the steering hydraulic cylinder 20 and the bucket hydraulic cylinder 21 is driven by the motor M2 , and the oil inlet of the hydraulic pump 16 is connected to the hydraulic oil tank 22 .

The oil inlet P port of the priority valve 17 is connected with the oil outlet port of the hydraulic pump 16, and the first working oil port CF port of the priority valve is connected with the oil inlet port of the hydraulic steering gear 19, through which the hydraulic steering gear 19 serves as the steering hydraulic cylinder 20 Provide hydraulic fluid; the second working oil port EF port of the priority valve 17 is connected with the oil inlet port of the electric proportional reversing valve 18, and the two working oil ports of the electric proportional reversing valve 18 are respectively connected with the large and small chambers of the dump hydraulic cylinder 21 The oil return port of the electric proportional reversing valve 18 is connected with the hydraulic oil tank 22 .

The first control handle at the control end of the electric proportional reversing valve 18 is an electric control handle, and its output electric signal is fed back to the complete machine control unit ECU to realize the "on-demand supply" of hydraulic fluid for the dump hydraulic cylinder.

The hydraulic steering gear 19 is a load sensing full hydraulic steering gear; the steering gear can extend or retract the piston rod of the steering hydraulic cylinder 20, as shown in Figure 1, the rodless chamber of one of the steering hydraulic cylinders is connected to the R The rod chamber is connected with the L port of the steering gear; the rodless chamber of the other steering hydraulic cylinder is connected with the L port of the steering gear, and the rod chamber is connected with the R port of the steering gear, so the two steering hydraulic cylinders are synchronously reversed. Steering movement, that is, during the process of extending the piston rod of one of the steering hydraulic cylinders, the piston rod of the other steering hydraulic cylinder retracts, and the two steering hydraulic cylinders cooperate to drive the wheels to turn, and the speed of the steering hydraulic cylinder is affected by the input of the steering gear. control. The hydraulic steering gear 19 connects the steering column to the steering wheel through the steering sensor. The steering sensor detects the speed signal and feeds it back to the overall machine control unit ECU. The ECU outputs the signal to the motor controller M2, so as to realize the "on-demand" hydraulic fluid of the steering system.

A closed hydraulic system for lifting and lowering the boom, including a two-way two-speed pump-motor 2, an accumulator 3, a first electromagnetic reversing valve 4, a first one-way valve 5, a second one-way valve 6, a first Relief valve 7, third one-way valve 8, second electromagnetic reversing valve 9, second overflow valve 10, boom hydraulic cylinder 11, gear pump 12, third electromagnetic reversing valve 15, hydraulic oil tank 22, changer One-way valve 13, the fifth one-way valve 23.

Wherein, the boom hydraulic cylinder 11 is used to drive the lifting and lowering of the working parts of the loader; The oil inlets of the second electromagnetic reversing valve 9 and the third electromagnetic reversing valve 15 are respectively connected with the A and B ports of the two-way two-speed pump-motor 2; the two-way two-speed pump-motor 2 is driven by the motor M1, It is used to provide hydraulic fluid for the closed hydraulic system that realizes lifting and lowering of the boom; the gear pump 12 is used for the supplementary oil pump of the closed system, mainly replenishing the oil with the volume difference between the large and small cavities of the boom cylinder, its oil suction port is connected with the oil tank, and its oil outlet The port is connected with the oil inlet port of the first electromagnetic reversing valve 4, the oil outlet of the first electromagnetic reversing valve 4 is connected with the accumulator 3, and the oil outlet of the gear pump 12 passes through the first one-way valve 5 and the second one-way valve. The valve 6 is connected with the ports A and B of the two-way two-speed pump-motor 2 respectively, the oil outlet of the gear pump 12 is also connected with the oil inlet of the first overflow valve 7, and the oil outlet of the first overflow valve 7 is connected with the hydraulic oil tank 22 connected; accumulator 3, used for oil storage or release;

The second joystick that controls the lifting and lowering of the boom is an electric control handle, and its output electric signal is fed back to the ECU of the whole machine control unit to realize the lifting and lowering of the loader boom.

This embodiment also includes a travel motor M3 and a power battery 1, the travel motor M3 is used for the travel system of the whole machine, and the power battery 1 provides power for the hydraulic and travel systems, and can store recovered energy at the same time.

As shown in Figure 2, the complete machine control unit ECU is connected with the first electromagnetic reversing valve 4, the second electromagnetic reversing valve 9, the third electromagnetic reversing valve 15, the M1 motor controller, the M2 motor controller, and the M3 motor controller respectively. device, the first joystick, and the second joystick are connected.

The ECU of the whole machine control unit receives the signal of the operating handle and converts it to output the signal to the motor controller. The specific operation process is as follows:

1. When the second joystick inputs the boom lifting signal, the control unit ECU of the whole machine receives the signal and controls the motor controller M1. At the same time, the second electromagnetic reversing valve 9 and the third electromagnetic reversing valve 15 are energized. The electromagnetic reversing valve 9 and the third electromagnetic reversing valve 15 are changed from the first working position to the second working position, so that the oil inlet and outlet ports of the electromagnetic reversing valve are connected;

The motor M1 runs in the forward direction. At this time, the B port of the two-way two-speed pump-motor 2 communicates with the large chamber of the boom hydraulic cylinder 11 through the third electromagnetic reversing valve 15, and the small chamber of the boom hydraulic cylinder 11 passes through the second electromagnetic reversing valve. The valve 9 communicates with the A port of the two-way two-speed pump-motor 2 to form a closed circuit;

The B port of the two-way two-speed pump-motor 2 is under high pressure so that the reversing valve 13 is in the second working position, so that only one pump of the two-way two-speed pump-motor 2 is in the working state, and the oil inlet and outlet of the other pump are directly connected so that it is idling state;

At this time, the first electromagnetic reversing valve 4 is energized, so that the first electromagnetic reversing valve 4 changes from the first working position to the second working position, and at this time, the oil inlet and outlet of the electromagnetic reversing valve are connected. The oil suction port of the gear pump 12 communicates with the hydraulic oil tank 22 . When the pressure in the accumulator 3 is lower than the pressure of the first relief valve 7, the gear pump 12 outputs hydraulic fluid through the first one-way valve 5 and the second electromagnetic reversing valve 9 to the side of the small chamber of the boom cylinder 11 to compensate The volume difference between the large and small chambers of the boom oil cylinder realizes a closed hydraulic system, and at the same time fills the accumulator 3 through the first electromagnetic reversing valve 4; when the pressure in the accumulator 3 is equal to the pressure of the first overflow valve 7 , the gear pump 12 reduces or stops the rotational speed, reduces the output hydraulic fluid, and mainly releases the oil in the accumulator 3 to the small chamber side of the boom cylinder 11 to make up for the volume difference between the large and small chambers of the boom cylinder;

The second relief valve 10 determines the pressure of the boom closed system. When the load pressure of the boom cylinder is greater than the set pressure of the second relief valve 10, the second relief valve 10 is opened, and the large and small chambers of the boom cylinder respectively pass through The fourth one-way valve 14 and the third one-way valve 8 release pressure to protect the components of the closed hydraulic system.

2. When the second joystick inputs the boom lowering signal, the control unit ECU of the whole machine receives the signal and controls the motor controller M1. At the same time, the second electromagnetic reversing valve 9 and the third electromagnetic reversing valve 15 are energized. The electromagnetic reversing valve 9 and the third electromagnetic reversing valve 15 change from the first working position to the second working position, so that the oil inlet and outlet ports of the electromagnetic reversing valve are connected.

The two-way two-speed pump-port B of the motor 2 communicates with the large chamber of the boom hydraulic cylinder 11 through the third electromagnetic reversing valve 15, and the small chamber of the boom hydraulic cylinder 11 communicates with the two-way two-speed pump-port through the first electromagnetic reversing valve 9 The port A of the motor 2 is connected to form a closed circuit.

The B port of the two-way two-speed pump-motor 2 is at low pressure so that the reversing valve 13 is in the first working position, so that the two-way two-speed pump-motor 2 is in a dual-motor working state. The operation of the motor reverses and drags M1 in reverse, and the electric control technology of the inverter and the common DC bus is used to recover the potential energy of the lowering potential energy of the boom.

Now the first electromagnetic reversing valve 4 is energized, so that the first electromagnetic reversing valve 4 changes from the first working position to the second working position, the pressure in the accumulator 3 is lower than the pressure of the first relief valve 7, The hydraulic fluid of the gear pump 12 fills the accumulator 3 through the first electromagnetic reversing valve 4. When the pressure in the accumulator 3 is equal to the pressure of the first relief valve 7, the oil in the accumulator is released to the boom The small cavity side of the oil cylinder 11;

Therefore, when the two-way two-speed pump-motor 2 is lifting the boom, the single pump works to ensure the lifting time; when the boom is lowered, the dual motors work to ensure that the pump-motor does not overspeed.

The above descriptions are only exemplary embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection of the present invention. within range. The above is only a preferred embodiment of the present invention, it should be pointed out that for those of ordinary skill in the art, without departing from the technical principle of the present invention, some improvements and modifications can also be made. It should also be regarded as the protection scope of the present invention.

Claims (9)

1. An electrohydraulic system, characterized in that it includes a closed hydraulic system for lifting and lowering the boom, and the closed hydraulic system includes a bidirectional two-speed pump-motor (2), an accumulator (3), a second 1. Electromagnetic reversing valve (4), first one-way valve (5), second one-way valve (6), second electromagnetic reversing valve (9), boom hydraulic cylinder (11), gear pump (12) , the third electromagnetic reversing valve (15), the hydraulic oil tank (22), the motor M1, the second joystick; The oil ports of the large and small chambers of the boom hydraulic cylinder (11) are respectively connected with the oil outlets of the third electromagnetic reversing valve (15) and the second electromagnetic reversing valve (9), and the second electromagnetic reversing valve ( 9) The oil inlets of the third electromagnetic reversing valve (15) are respectively connected to the A and B ports of the two-way two-speed pump-motor (2); The oil inlet of the gear pump (12) is connected to the hydraulic oil tank (22), the oil outlet of the gear pump (12) is connected to the oil inlet of the first electromagnetic reversing valve (4), and the oil outlet of the gear pump (12) passes through the first The one-way valve (5) is connected to the A port of the two-way two-speed pump-motor (2), and the oil outlet of the gear pump (12) is also connected to the two-way two-speed pump-motor (2) through the second one-way valve (6). Port B is connected, and the oil outlet of the first electromagnetic reversing valve (4) is connected to the accumulator (3); The motor M1 drives the action of the bidirectional two-speed pump-motor (2), and is connected to the inverter through the M1 motor controller, and the inverter is connected to the common DC bus; The second control handle is used to realize the lifting and lowering of the boom; The two-way two-speed pump-motor (2) includes a reversing valve (13). When the B port of the two-way two-speed pump-motor (2) is under high pressure, the reversing valve (13) is in the second working position, so that the two-way two-speed Only the single pump of the two-speed pump-motor (2) is in working condition; when the B port of the two-way two-speed pump-motor (2) is at low pressure, the reversing valve (13) is in the first working position, so that the two-way two-speed pump-motor ( 2) The two motors are in working condition at the same time. 2. An electro-hydraulic system according to claim 1, characterized in that it further comprises a first relief valve (7), the oil inlet of the first relief valve (7) is connected to the outlet of the gear pump (12) Oil port, the oil outlet of the first relief valve (7) communicates with the hydraulic oil tank (22). 3. An electrohydraulic system according to claim 1, characterized in that it further comprises a second relief valve (10), a third check valve (8) and a fifth check valve (25), the The oil inlet port of the second relief valve (10) is respectively connected to ports A and B of the bidirectional two-speed pump-motor (2) through the third check valve (8) and the fifth check valve (25). 4. The electrohydraulic system according to claim 1, further comprising a power battery (1), and the power battery (1) is connected to a common DC bus. 5. An electro-hydraulic system according to claim 1, characterized in that it also includes a hydraulic system for realizing the steering of the whole machine and the action of the dump cylinder, the hydraulic system includes a hydraulic pump (16), a priority valve (17), Electric proportional reversing valve (18), steering hydraulic cylinder (20), dump bucket hydraulic cylinder (21), first joystick, hydraulic steering gear with steering sensor (19), The oil inlet port P of the priority valve (17) is connected to the oil outlet port of the hydraulic pump (16), and the first working oil port CF port of the priority valve (17) is connected to the oil inlet port of the hydraulic steering gear (19) , the oil outlet of the hydraulic steering gear (19) is connected to the steering hydraulic cylinder (20); The second working oil port EF port of the priority valve (17) is connected to the oil inlet port of the electric proportional reversing valve (18), and the two working oil ports of the electric proportional reversing valve (18) are respectively connected to the bucket hydraulic cylinder (21) The large and small chambers are connected, and the oil return port of the electric proportional directional control valve (18) is connected with the hydraulic oil tank (22); The first joystick controls the action of the electric proportional reversing valve (18). 6. An electrohydraulic system according to claim 5, characterized in that it further comprises a motor M2 that drives the hydraulic pump (16), the motor M2 is connected to an inverter through the M2 motor controller, and the inverter connected to the common DC bus. 7. A kind of electrohydraulic system according to claim 6, is characterized in that, also comprises the motor M3 that provides power for walking system, described motor M3 is connected inverter through M3 motor controller, and described inverter is connected Common DC bus. 8. An electrohydraulic system according to claim 7, characterized in that, it also includes a complete machine control unit ECU, and the complete machine control unit ECU is respectively connected to the M1 motor controller, the M2 motor controller, and the M3 motor controller , the first electromagnetic reversing valve (4), the second electromagnetic reversing valve (9), the third electromagnetic reversing valve (15), the electric proportional reversing valve (18), the first joystick, the second joystick and Steering sensor for hydraulic steering gear (19). 9. A loader, characterized in that it comprises an electro-hydraulic system according to any one of claims 1-8.

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