阅读说明：本技术 液电耦合驱动多执行器系统及控制方法 (Liquid-electric coupling driving multi-actuator system and control method ) 是由 权龙� 乔舒斐 郝云晓 葛磊 王波 于 2021-11-17 设计创作，主要内容包括：本发明涉及一种液电耦合驱动多执行器系统及控制方法,属于液压传动和电机械传动技术领域,液电耦合驱动多执行器系统包括：一个或多个液电混驱执行器；与液电混驱执行器数量一致的第一逆变器及控制阀；各液电混驱执行器对应连接一个第一逆变器及一个控制阀；集中式液压单元,与各控制阀连接,用于为各液电混驱执行器供油并进行功率补偿；控制单元,分别与各液电混驱执行器连接,用于根据各液电混驱执行器的压力信息,控制对应的液电混驱执行器电机的输出扭矩,使各液电混驱执行器的驱动腔压力相等,极大地降低了由于各执行器的负载差异而导致的节流损失。(The invention relates to a hydraulic-electric coupling driving multi-actuator system and a control method, belonging to the technical field of hydraulic transmission and electromechanical transmission, wherein the hydraulic-electric coupling driving multi-actuator system comprises: one or more hydro-electric hybrid actuators; the number of the first inverters is consistent with that of the hydraulic-electric hybrid actuators; each hydraulic-electric hybrid-driven actuator is correspondingly connected with a first inverter and a control valve; the centralized hydraulic unit is connected with each control valve and is used for supplying oil to each hydraulic-electric hybrid drive actuator and performing power compensation; and the control unit is respectively connected with each hydraulic-electric hybrid-driven actuator and used for controlling the output torque of the corresponding hydraulic-electric hybrid-driven actuator motor according to the pressure information of each hydraulic-electric hybrid-driven actuator, so that the pressure of the driving cavity of each hydraulic-electric hybrid-driven actuator is equal, and the throttling loss caused by the load difference of each actuator is greatly reduced.)

1. An electro-hydraulic coupling drive multi-actuator system, comprising:

one or more hydro-electric hybrid actuators;

the number of the first inverters is consistent with that of the hydraulic-electric hybrid drive actuators;

each hydraulic-electric hybrid-driven actuator is correspondingly connected with a first inverter, a control valve and a pressure sensor group; the pressure sensor group is used for detecting pressure information of the corresponding hydraulic-electric hybrid drive actuator;

the centralized hydraulic unit is connected with each control valve and is used for supplying oil to each hydraulic-electric hybrid drive actuator and performing power compensation;

and the control unit is respectively connected with each liquid-electric hybrid-driven actuator and each pressure sensor and is used for controlling the output torque of the corresponding liquid-electric hybrid-driven actuator motor according to the pressure information of each liquid-electric hybrid-driven actuator so as to enable the pressure of the driving cavity of each liquid-electric hybrid-driven actuator to be equal.

2. The hydroelectrically coupled drive multi-actuator system according to claim 1, wherein the hydroelectrically hybrid driven actuator comprises:

a motor;

the speed reducer is connected with the motor;

the cylinder barrel is fixedly connected with the speed reducer;

the push rod is arranged in the cylinder barrel and is movably connected with the cylinder barrel;

the screw rod is arranged in the cylinder barrel, one end of the screw rod is connected with the speed reducer, and the other end of the screw rod is connected with the push rod through a screw transmission pair; the screw rod generates rotary motion under the control of the motor and the speed reducer, and further drives the push rod to generate linear motion through the screw transmission pair;

a sealing element is arranged between the push rod and the cylinder barrel; the sealing piece divides the cylinder barrel into two cavities, one side of the cylinder barrel, which is close to the speed reducer, is a rodless cavity, and one side of the cylinder barrel, which is close to the push rod, is a rod cavity;

the working oil port of the control valve is respectively communicated with the two cavities of the corresponding hydraulic-electric hybrid actuator; the control valve is used for providing power compensation for the corresponding hydraulic-electric hybrid actuator through a working oil port according to the pressure information of the driving cavity of the hydraulic-electric hybrid actuator; and an oil return port of the control valve is communicated with the oil tank.

3. The hydroelectrically coupled drive multi-actuator system according to claim 2, wherein the pressure sensor group comprises:

the first pressure sensor is connected with the rodless cavity of the corresponding hydraulic-electric hybrid drive actuator and used for detecting pressure information of the rodless cavity of the corresponding hydraulic-electric hybrid drive actuator;

and the second pressure sensor is connected with the rod cavity of the corresponding hydraulic-electric hybrid drive actuator and is used for detecting the pressure information of the rod cavity of the corresponding hydraulic-electric hybrid drive actuator.

4. The hydroelectrically coupled drive multi-actuator system according to claim 1, wherein the centralized hydraulic unit comprises: the system comprises a second inverter, a motor, a hydraulic pump, an oil tank, an oil supply pipeline, an overflow valve, a bypass proportional valve and a shuttle valve;

the motor is connected with the second inverter;

the hydraulic pump is coaxially connected with the motor, an oil suction port of the hydraulic pump is communicated with the oil tank, and an oil outlet of the hydraulic pump is communicated with the oil supply pipeline;

the overflow valve is respectively communicated with the oil supply pipeline and the oil tank;

the shuttle valve is connected with the load detection end of the control valve corresponding to each hydraulic-electric hybrid actuator and is used for detecting the highest load pressure of the hydraulic-electric hybrid actuator;

the bypass proportional valve is provided with a first working oil port, a second working oil port, a third working oil port, a spring end and a pressure detection end;

a first working oil port of the bypass proportional valve is communicated with the oil tank; a second working oil port of the bypass proportional valve is communicated with an energy accumulator; a third working oil port of the bypass proportional valve is communicated with the oil supply pipeline; the spring end of the bypass proportional valve is connected with the shuttle valve, and the spring end of the bypass proportional valve is used for detecting the maximum load feedback pressure of each hydraulic-electric hybrid actuator;

the pressure detection end of the bypass proportional valve is connected with the oil supply pipeline, and the pressure detection end is used for detecting the outlet pressure of the hydraulic pump;

the bypass proportional valve is controlled by outlet pressure, load feedback pressure and spring force of the hydraulic pump; the outlet pressure of the hydraulic pump is always higher than the load pressure by a fixed value.

5. The hydroelectrically coupled drive multi-actuator system according to claim 4, further comprising:

and the direct-current bus is respectively connected with the first inverter and the second inverter and is used for carrying out energy distribution and energy sharing on each hydraulic-electric hybrid drive actuator.

6. The hydroelectrically coupled drive multi-actuator system according to claim 5, further comprising: and the power switch, the rectifier, the direct current-direct current DC-DC converter and the super capacitor bank are sequentially connected to the direct current bus.

7. A control method for a plurality of actuators driven by hydraulic coupling is characterized by comprising the following steps:

when a plurality of hydraulic-electric hybrid drive actuators under load difference act together, the running speed of each hydraulic-electric hybrid drive actuator is controlled by a respective motor;

the centralized hydraulic unit system carries out power compensation on the electric drive of each hydraulic-electric hybrid drive actuator;

and adjusting the output torque of the motor of each hydraulic-electric hybrid-driven actuator according to the pressure information of each hydraulic-electric hybrid-driven actuator, and further controlling the pressure of the driving cavity of each hydraulic-electric hybrid-driven actuator to enable the pressure of the driving cavity of each hydraulic-electric hybrid-driven actuator to be equal.

8. The method for controlling the electrohydraulic-coupled-drive multi-actuator according to claim 7, further comprising:

the bypass proportional valve is controlled to make the outlet pressure of the hydraulic pump higher than the highest load pressure by a fixed value, so that the opening of each control valve is maximum.

9. The method for controlling the electrohydraulic-coupled-drive multi-actuator according to claim 7, further comprising:

calculating the required flow of each hydraulic-electric hybrid-driven actuator according to a flow matching principle;

and adjusting the swing angle of a swash plate of the hydraulic pump according to the required flow, and controlling the output flow of the hydraulic pump to be consistent with the required flow.

Technical Field

The invention relates to the technical field of hydraulic transmission and electromechanical transmission, in particular to a hydraulic coupling driving multi-actuator system and a control method.

Background

The hydraulic system has the advantages of high power density and the like, and is widely applied to various non-road mobile equipment such as aerospace, deep sea equipment, engineering machinery, road building machinery, mining machinery, forestry machinery, agricultural machinery and the like. At present, for a multi-actuator hydraulic system, a mode of concentrated power source energy supply and multi-way valve power distribution is generally adopted, the output pressure of a pump is matched with the highest load link, and other links compensate the influence of load difference through respective pressure compensators, so that the pressure compensators and control valves of a low load link have large throttling loss, and the overall energy efficiency of the system is low. In addition, the equipment with the lifting device has the problem of serious kinetic potential energy waste.

The electromechanical actuator driving system is a technology for converting the rotary motion of a motor into linear motion through mechanical transmission, and compared with hydraulic driving, the electromechanical actuator driving system has the advantages of energy conservation, environmental protection, easiness in control, high control precision and the like, but the electromechanical actuator is low in power density and poor in bearing capacity. In addition, the conventional driving system with multiple electromechanical actuators is simple superposition of the driving system with a single electromechanical actuator, and the whole system has higher installed power.

In view of the foregoing, there is a need for a new multi-actuator control system to reduce throttling losses and packaging power.

Disclosure of Invention

The invention aims to provide a hydraulic coupling driving multi-actuator system and a control method, which can reduce throttling loss and installed power.

In order to achieve the purpose, the invention provides the following scheme:

an hydroelectrically coupled driven multi-actuator system, comprising:

one or more hydro-electric hybrid actuators;

the number of the first inverters is consistent with that of the hydraulic-electric hybrid drive actuators;

each hydraulic-electric hybrid-driven actuator is correspondingly connected with a first inverter, a control valve and a pressure sensor group; the pressure sensor group is used for detecting pressure information of the corresponding hydraulic-electric hybrid drive actuator;

the centralized hydraulic unit is connected with each control valve and is used for supplying oil to each hydraulic-electric hybrid drive actuator and performing power compensation;

and the control unit is respectively connected with each liquid-electric hybrid-driven actuator and each pressure sensor and is used for controlling the output torque of the corresponding liquid-electric hybrid-driven actuator motor according to the pressure information of each liquid-electric hybrid-driven actuator so as to enable the pressure of the driving cavity of each liquid-electric hybrid-driven actuator to be equal.

Optionally, the hydro-electric hybrid actuator comprises:

a motor;

the speed reducer is connected with the motor;

the cylinder barrel is fixedly connected with the speed reducer;

the push rod is arranged in the cylinder barrel and is movably connected with the cylinder barrel;

the screw rod is arranged in the cylinder barrel, one end of the screw rod is connected with the speed reducer, and the other end of the screw rod is connected with the push rod through a screw transmission pair; the screw rod generates rotary motion under the control of the motor and the speed reducer, and further drives the push rod to generate linear motion through the screw transmission pair;

a sealing element is arranged between the push rod and the cylinder barrel; the sealing piece divides the cylinder barrel into two cavities, one side of the cylinder barrel, which is close to the speed reducer, is a rodless cavity, and one side of the cylinder barrel, which is close to the push rod, is a rod cavity;

the working oil port of the control valve is respectively communicated with the two cavities of the corresponding hydraulic-electric hybrid actuator; the control valve is used for providing power compensation for the corresponding hydraulic-electric hybrid actuator through a working oil port according to torque information output by the motor of the hydraulic-electric hybrid actuator; and an oil return port of the control valve is communicated with the oil tank.

Optionally, the pressure sensor group comprises:

the first pressure sensor is connected with the rodless cavity of the corresponding hydraulic-electric hybrid drive actuator and used for detecting pressure information of the rodless cavity of the corresponding hydraulic-electric hybrid drive actuator;

and the second pressure sensor is connected with the rod cavity of the corresponding hydraulic-electric hybrid drive actuator and is used for detecting the pressure information of the rod cavity of the corresponding hydraulic-electric hybrid drive actuator.

Optionally, the centralized hydraulic unit comprises: the system comprises a second inverter, a motor, a hydraulic pump, an oil tank, an oil supply pipeline, an overflow valve, a bypass proportional valve and a shuttle valve;

the motor is connected with the second inverter;

the hydraulic pump is coaxially connected with the motor, an oil suction port of the hydraulic pump is communicated with the oil tank, and an oil outlet of the hydraulic pump is communicated with the oil supply pipeline;

the overflow valve is respectively communicated with the oil supply pipeline and the oil tank;

the shuttle valve is connected with the load detection end of the control valve corresponding to each hydraulic-electric hybrid actuator and is used for detecting the highest load pressure of the hydraulic-electric hybrid actuator;

the bypass proportional valve is provided with a first working oil port, a second working oil port, a third working oil port, a spring end and a pressure detection end;

a first working oil port of the bypass proportional valve is communicated with the oil tank; a second working oil port of the bypass proportional valve is communicated with an energy accumulator; a third working oil port of the bypass proportional valve is communicated with the oil supply pipeline; the spring end of the bypass proportional valve is connected with the shuttle valve, and the bypass proportional valve is used for detecting the maximum load feedback pressure of each hydraulic-electric hybrid actuator;

the pressure detection end of the bypass proportional valve is connected with the oil supply pipeline, and the pressure detection end is used for detecting the outlet pressure of the hydraulic pump;

the bypass proportional valve is controlled by outlet pressure of the hydraulic pump, load feedback pressure and spring force, so that the outlet pressure of the hydraulic pump is always higher than the load pressure by a fixed value.

Optionally, the system further includes:

and the direct-current bus is respectively connected with the first inverter and the second inverter and is used for carrying out energy distribution and energy sharing on each hydraulic-electric hybrid drive actuator.

Optionally, the system further includes: and the power switch, the rectifier, the DC-DC converter and the super capacitor bank are sequentially connected to the direct current bus.

In order to achieve the above purpose, the invention also provides the following scheme:

a control method for a hydraulic coupling drive multi-actuator comprises the following steps:

when a plurality of hydraulic-electric hybrid drive actuators under load difference act together, the running speed of each hydraulic-electric hybrid drive actuator is controlled by a respective motor;

the centralized hydraulic unit system carries out power compensation on the electric drive of each hydraulic-electric hybrid drive actuator;

and adjusting the output torque of the motor of each hydraulic-electric hybrid-driven actuator according to the pressure information of each hydraulic-electric hybrid-driven actuator, and further controlling the pressure of the driving cavity of each hydraulic-electric hybrid-driven actuator to enable the pressure of the driving cavity of each hydraulic-electric hybrid-driven actuator to be equal.

Preferably, the method for controlling the electrohydraulic coupling driven multiple actuators further comprises the following steps:

the bypass proportional valve is controlled to make the outlet pressure of the hydraulic pump higher than the highest load pressure by a fixed value, so that the opening of each control valve is maximum.

Preferably, the method for controlling the electrohydraulic coupling driven multiple actuators further comprises the following steps:

calculating the required flow of each hydraulic-electric hybrid-driven actuator according to a flow matching principle;

and adjusting the swing angle of a swash plate of the hydraulic pump according to the required flow, and controlling the output flow of the hydraulic pump to be consistent with the required flow.

According to the specific embodiment provided by the invention, the invention discloses the following technical effects: the pressure sensor is used for detecting the pressure information of each hydraulic-electric hybrid-driven actuator, and the output torque of the corresponding hydraulic-electric hybrid-driven actuator motor is controlled according to the pressure information, so that the pressure of the driving cavity of each hydraulic-electric hybrid-driven actuator is equal, and the throttling loss caused by the load difference of each hydraulic-electric hybrid-driven actuator is greatly reduced. In addition, by additionally arranging a control valve and a centralized hydraulic unit, power supplement is carried out on all the hydraulic-electric hybrid actuators, a low-power motor can drive and pull a high-power actuator, the total installed power of a multi-actuator system is obviously reduced, and the hydraulic-electric hybrid actuator system is particularly suitable for engineering equipment with multiple actuators.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.

FIG. 1 is a schematic structural diagram of a multi-actuator system driven by electro-hydraulic coupling according to the present invention;

FIG. 2 is a flow chart of a control method for driving multiple actuators by electro-hydraulic coupling according to the present invention;

FIG. 3 is a schematic diagram of a mechanical structure of an electro-hydraulic coupling driving excavator;

FIG. 4 is a schematic diagram of a circuit of the invention applied to a complete excavator.

Description of the symbols:

a power switch-1, a rectifier-2, a Direct Current bus-3, a filter capacitor-4, a Direct Current (DC-DC) converter-5, a super capacitor group-6,

a first inverter-7, movable arm linkage inverters-7-1 and 7-2, bucket rod linkage inverters-7-3 and 7-4 and a rotation linkage inverter-7-5;

the hydraulic-electric hybrid-driven actuator-8, the movable arm linkage hydraulic-electric hybrid-driven actuators-8-1 and 8-2 and the bucket rod linkage hydraulic-electric hybrid-driven actuators-8-3 and 8-4;

a motor-9, a reducer-10, a screw rod-11, a push rod-12, a cylinder barrel-13 and a sealing piece-14;

first pressure sensors-15, 15-1, 15-2, 15-3, 15-4, second pressure sensors-16, 16-1, 16-2, 16-3, 16-4;

a control valve-17, a movable arm linkage control valve-17-1, a bucket linkage control valve-17-2, a bucket rod linkage control valve-17-3 and a rotation linkage control valve-17-4;

third pressure sensors-18, 18-1 and 18-2, second inverters-19, 19-1 and 19-2, motors-20, 20-1 and 20-2, hydraulic pumps-21, 21-1 and 21-2, an oil tank-22, overflow valves-23, 23-1 and 23-2, a bypass proportional valve-24, an energy accumulator-25, a shuttle valve-26, a differential pressure compensator-27, a valve core displacement sensor-28 and a switch valve-29;

the device comprises a traveling device-30, a rotary motor-31, a rotary platform-32, a movable arm-33, an arm-34, a bucket-35 and a bucket hydraulic cylinder-36; a rotary motor 37;

the control valve comprises a first working oil port-A of the control valve, a second working oil port-B of the control valve, an oil inlet-P of the control valve, an oil return port-T of the control valve, a load pressure detection end-LS of the control valve, an oil supply pipeline-L, a first working oil port-E of the bypass proportional valve, a second working oil port-F of the bypass proportional valve and a third working oil port-C of the bypass proportional valve.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention aims to provide a hydraulic coupling drive multi-actuator system and a control method, which detect the pressure information of each hydraulic and electric hybrid drive actuator through a pressure sensor, and control the output torque of a corresponding hydraulic and electric hybrid drive actuator motor according to the pressure information, so that the pressure of the driving cavity of each hydraulic and electric hybrid drive actuator is equal, and the throttling loss caused by the load difference of each hydraulic and electric hybrid drive actuator is greatly reduced. In addition, by additionally arranging a control valve and a centralized hydraulic unit, power supplement is carried out on all the hydraulic-electric hybrid actuators, a low-power motor can drive and pull a high-power actuator, the total installed power of a multi-actuator system is obviously reduced, and the hydraulic-electric hybrid actuator system is particularly suitable for engineering equipment with multiple actuators.

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.

As shown in fig. 1, the electrohydraulic coupling driving multi-actuator system of the present invention includes:

one or more hydro-electric hybrid actuators 8;

the number of the first inverters 7 is consistent with that of the hydraulic-electric hybrid actuators 8, and the control valves 17 and the pressure sensor groups are arranged. Preferably, the control valve 17 is a three-position four-way control valve having a load pressure feedback function.

Each hydraulic-electric hybrid-driven actuator 8 is correspondingly connected with a first inverter 7, a control valve 17 and a pressure sensor group; the pressure sensor group is used for detecting the pressure information of the corresponding hydraulic-electric hybrid actuator 8.

And the centralized hydraulic unit is connected with each control valve 17 and is used for supplying oil to each hydraulic-electric hybrid actuator 8 and compensating power.

And the control unit is respectively connected with each hydraulic-electric hybrid-driven actuator 8 and each pressure sensor and is used for controlling the output torque of the corresponding motor of the hydraulic-electric hybrid-driven actuator 8 according to the pressure information of each hydraulic-electric hybrid-driven actuator 8 so as to enable the pressure of the driving cavity of each hydraulic-electric hybrid-driven actuator 8 to be equal. The influence of load difference of each actuator is eliminated without throttling loss, and the throttling loss caused by different driving cavity pressures of each hydraulic-electric hybrid actuator 8 is greatly reduced.

The invention supplements power for all motors by additionally arranging the control valve 17 and the centralized hydraulic unit, can realize that a small-power motor drives and pulls a large-power actuator, obviously reduces the total installed power of a multi-actuator system, and is particularly suitable for engineering equipment with multiple actuators.

Further, the hydro-electric hybrid actuator 8 includes: motor 9, reduction gear 10, cylinder 13, push rod 12 and lead screw 11.

Wherein the speed reducer 10 is connected with the motor 9.

The cylinder 13 is fixedly connected to the speed reducer 10.

The push rod 12 is arranged in the cylinder barrel 13 and is movably connected with the cylinder barrel 13.

The screw rod 11 is arranged in the cylinder barrel 13, one end of the screw rod is connected with the speed reducer 10, and the other end of the screw rod is connected with the push rod 12 through a screw transmission pair; the screw rod 11 generates rotary motion under the control of the motor 9 and the speed reducer, and further drives the push rod 12 to generate linear motion through the screw transmission pair. The control performance of the hydraulic-electric hybrid actuator is better due to mechanical transmission.

A sealing element 14 is arranged between the push rod 12 and the cylinder barrel 13; the sealing piece 14 divides the cylinder barrel 13 into two cavities, one side of the cylinder barrel 13 close to the speed reducer is a rodless cavity, and one side close to the push rod 12 is a rod cavity;

the working oil port of the control valve 17 is respectively communicated with the two cavities of the corresponding hydraulic-electric hybrid actuator 8; the control valve 17 is used for providing power compensation for the corresponding hydraulic-electric hybrid actuator 8 through a working oil port according to the pressure information of the driving cavity of the hydraulic-electric hybrid actuator 8; the oil return port of the control valve 17 communicates with the oil tank 22.

On the basis of ensuring the flow distribution precision of the system, the opening degree of the valve port of each control valve 17 is increased, the throttling loss of the valve port is reduced to the maximum extent, the throttling loss of the control valve 17 is minimized, and further the throttling loss of the whole system is minimized.

Still further, the pressure sensor group includes: a first pressure sensor 15 and a second pressure sensor 16.

The first pressure sensor 15 is connected with the rodless cavity of the corresponding hydraulic-electric hybrid actuator 8, and the first pressure sensor 15 is used for detecting pressure information of the rodless cavity of the corresponding hydraulic-electric hybrid actuator 8.

The second pressure sensor 16 is connected with the rod cavity of the corresponding hydraulic-electric hybrid actuator 8, and the second pressure sensor 16 is used for detecting the pressure information of the rod cavity of the corresponding hydraulic-electric hybrid actuator 8.

Specifically, the centralized hydraulic unit comprises: a second inverter 19, an electric motor 20, a hydraulic pump 21, a tank 22, a supply line L, a relief valve 23, a bypass proportional valve 24, an accumulator 25, and a shuttle valve 26.

The motor 20 is connected to the second inverter 19.

The hydraulic pump 21 is coaxially connected with the motor 20, an oil suction port of the hydraulic pump 21 is communicated with the oil tank 22, and an oil outlet of the hydraulic pump 21 is communicated with the oil supply pipeline L.

The overflow valve 23 is respectively communicated with the oil supply line L and the oil tank 22.

The shuttle valve 26 is connected to the load detection end of the control valve 17 corresponding to each hydraulic-electric hybrid actuator 8, and the shuttle valve 26 is used for detecting the highest load pressure of the hydraulic-electric hybrid actuator 8.

The bypass proportional valve 24 is provided with a first working oil port E, a second working oil port F, a third working oil port C, a spring end and a pressure detection end.

A first working oil port E of the bypass proportional valve 24 is communicated with the oil tank 22; a second working oil port F of the bypass proportional valve 24 is communicated with an energy accumulator 25; a third working oil port C of the bypass proportional valve 24 is communicated with the oil supply pipeline; the spring end of the bypass proportional valve 24 is connected with the shuttle valve 26, and the spring end of the bypass proportional valve 24 is used for detecting the maximum load feedback pressure of each hydro-electric hybrid actuator 8.

The pressure detection end of the bypass proportional valve 24 is connected to the oil supply line L, and the pressure detection end is used for detecting the outlet pressure of the hydraulic pump 21.

The bypass proportional valve 24 is controlled by the outlet pressure of the hydraulic pump 21, the load feedback pressure and the spring force, so that the outlet pressure of the hydraulic pump 21 is always higher than the load pressure by a fixed value.

Preferably, the centralized hydraulic unit also comprises a third pressure sensor 18. The third pressure sensor 18 is communicated with the oil supply pipeline L, and the third pressure sensor 18 is used for detecting the pressure of the oil supply pipeline L in real time.

Optionally, the system further includes: a dc bus 3. The dc bus 3 is connected to the first inverter 7 and the second inverter 19, respectively, and the dc bus 3 is used for energy distribution and energy sharing for each of the hydraulic-electric hybrid actuators 8.

Further, the system of the multi-actuator driven by the liquid electricity coupling also comprises: and the power switch 1, the rectifier 2, the DC-DC converter 5 and the super capacitor bank 6 are sequentially connected to the DC bus 3.

The kinetic potential energy can be recycled through the direct current bus 3 and the super capacitor set 6. When the hydraulic-electric hybrid actuator 8 is in an overrunning load working condition, the kinetic potential energy of the actuator is converted into electric energy through the motor 9, the electric energy is stored to the super capacitor bank 6 through the direct current bus 3, and the kinetic potential energy generated by the system can be directly utilized through the direct current bus 3 to realize energy sharing. The surplus energy can also be further converted into hydraulic energy by the electric motor 20 and the hydraulic pump 21 of the centralized hydraulic unit and stored in the accumulator 25. The energy utilization process is the reverse of the recovery process.

In the present embodiment, the accumulator 25 is one of a gas bag type accumulator, a piston type accumulator, and a spring type accumulator. The motor 20 is electrically connected to the dc bus 3 through a second inverter 19 to obtain power.

As shown in fig. 2, the method for controlling the electrohydraulic coupling driven multiple actuators of the present invention includes:

s1: when the plurality of hydraulic-electric hybrid actuators 8 under the load difference act together, the running speed of each hydraulic-electric hybrid actuator 8 is controlled by a respective motor.

S2: the centralized hydraulic unit performs power compensation on the electric drive of each hydraulic-electric hybrid drive actuator 8.

S3: according to the pressure information of each hydraulic-electric hybrid actuator 8, the output torque of the motor of each hydraulic-electric hybrid actuator 8 is adjusted, and further the driving cavity pressure of each hydraulic-electric hybrid actuator 8 is controlled, so that the driving cavity pressure of each hydraulic-electric hybrid actuator 8 is equal.

Further, the method for controlling the electrohydraulic coupling driving multiple actuators further comprises the following steps:

s4: by controlling the bypass proportional valve, the outlet pressure of the hydraulic pump 21 is increased by a fixed value from the maximum load pressure, and the opening of each joint control valve 17 is maximized.

Still further, the method for controlling the electrohydraulic coupling driven multi-actuator further comprises the following steps:

s5: and calculating the required flow of each hydraulic-electric hybrid drive actuator 8 according to the flow matching principle.

S6: according to the required flow, the swash plate swing angle of the hydraulic pump 21 is adjusted, and the output flow of the hydraulic pump 21 is controlled to be consistent with the required flow.

The following is an embodiment of the invention in which the electrohydraulic coupling driving multi-actuator system and the control method are applied to an excavator:

fig. 3 is a schematic diagram of a mechanical structure of an electro-hydraulic coupling driven excavator, which is a typical multi-actuator mechanical device widely used in the present invention, and mainly includes: the traveling device 30 includes a revolving platform 32 disposed on the traveling device 30, a revolving motor 31 for driving the revolving platform 32 to revolve, boom-coupled hydraulic/electric hybrid actuators 8-1 and 8-2 connected to the revolving platform 32 and rotating relatively in the vertical direction and driving the boom 33 to lift and lower, an arm 34 attached to the tip of the boom 33 and rotating relatively, an arm-coupled hydraulic/electric hybrid actuator 8-3 for driving the arm 34 to move, a bucket 35 attached to the tip of the arm 34 and rotating relatively, and a bucket cylinder 36 for driving the bucket 35 to move.

FIG. 4 is a schematic diagram of a circuit of the invention, in which the multi-actuator system driven by the electro-hydraulic coupling is applied to the whole excavator. As shown in fig. 4, the electric drive excavator circuit includes:

a direct current bus 3;

one or two movable arm hydraulic-electric hybrid-driven actuators 8-1 and 8-2, one or two movable arm inverters 7-1 and 7-2 and a movable arm control valve 17-1;

one or two bucket rod connected hydraulic and electric hybrid actuators 8-3 and 8-4, one or two bucket rod connected inverters 7-3 and 7-4 and a bucket rod connected control valve 17-3;

a bucket hydraulic cylinder 36, a bucket linkage control valve 17-2;

a rotary motor 31, a rotary motor 37, a rotary joint inverter 7-5 and a rotary joint control valve 17-4;

two centralized hydraulic units each including a second inverter 19, an electric motor 20, a hydraulic pump, an oil tank 22, and a relief valve 23, and a control unit.

The direct current bus 3 is connected with a power switch 1, a rectifier 2, a filter capacitor 4, a DC-DC converter 5 and a super capacitor bank 6.

The movable arm-linked inverters 7-1 and 7-2, the bucket rod-linked inverters 7-3 and 7-4, the rotation-linked inverter 7-5 and the second inverters 19-1 and 19-2 are all electrically connected with the direct current bus 3.

The direct current bus 3 respectively performs power distribution and energy sharing for each actuator pair through each inverter, and stores redundant energy to the super capacitor bank 6.

The movable arm hydraulic-electric hybrid actuator 8-1 and 8-2 are hydraulic-electric hybrid actuators of the hydraulic-electric coupling driving multi-actuator system, the movable arm hydraulic-electric hybrid actuators 8-1 and 8-2 are respectively connected with the movable arm inverter 7-1 and 7-2, and two cavities of the movable arm hydraulic-electric hybrid actuators are respectively communicated with a working oil port A, B of a movable arm linkage control valve 17-1.

The bucket rod connected hydraulic-electric hybrid-driven actuators 8-3 and 8-4 are hydraulic-electric hybrid-driven actuators of the hydraulic-electric coupling driving multi-actuator system, the bucket rod connected hydraulic-electric hybrid-driven actuators 8-3 and 8-4 are respectively connected with the bucket rod connected inverters 7-3 and 7-4, and two cavities of the bucket rod connected hydraulic-electric hybrid-driven actuators are respectively communicated with a working oil port A, B of the bucket rod connected control valve 17-3.

The rotary motor 31 is coaxially connected with the rotary motor 37, the rotary motor 37 is connected with the rotary union inverter 7-5, and two cavities of the rotary motor are respectively communicated with a working oil port A, B of the rotary union control valve 17-4.

Two cavities of the bucket hydraulic cylinder 36 are respectively communicated with a working oil port A, B of the bucket linkage control valve 17-2, and the bucket linkage is further provided with a differential pressure compensator 27 and a valve core displacement sensor 28. An oil outlet of the differential pressure compensator is communicated with an oil inlet of a bucket joint control valve 17-2, the bucket joint control valve 17-2 is a three-position four-way control valve with a load pressure detection function, a spring end of the differential pressure compensator 17-2 is communicated with a load pressure detection port LS, and the other end of the differential pressure compensator is communicated with a control valve oil inlet P.

The centralized hydraulic unit is used for supplying oil to the movable arm linkage liquid-electricity hybrid drive actuator, the bucket linkage liquid-electricity hybrid drive actuator, the rotary motor and the bucket hydraulic cylinder for power compensation.

The first centralized hydraulic unit and the second centralized hydraulic unit are connected through a switch valve 29, and when a single centralized hydraulic unit cannot provide enough flow, the control unit controls the switch valve 29 to be communicated, and the two centralized hydraulic units are merged to supply oil to the actuator.

The control unit is respectively connected with each hydraulic-electric hybrid actuator, the rotary motor, the control valve, the switch valve, the motor and the hydraulic pump.

The control unit controls the output torque of the corresponding boom hydraulic-electric hybrid actuator 8-1, 8-2, the output torque of the bucket hydraulic-electric hybrid actuator 8-3, 8-4 and the output torque of the swing motor 31, the bucket hydraulic cylinder 36 and the swing motor 37 according to the maximum load pressure information of the multiple actuators detected by the boom hydraulic-electric hybrid actuator 8-1, 8-2, the boom hydraulic-electric hybrid actuator 8-3, 8-4 and the pressure sensor, compensates the load difference among the multiple actuators, enables the driving cavity pressure of each actuator in the coordinated action to be equal as much as possible, and reduces the throttling loss at the control valve port caused by the load difference of the multiple actuators.

The concrete control method of the excavator system is the same as the control method of the hydraulic-electric coupling driving multi-actuator.

The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.