An electro-hydraulic servo drive unit and its application

Abstract

The present invention discloses an electro-hydraulic servo drive unit, belonging to the field of hydraulic drive. The electro-hydraulic servo drive unit of the present invention includes a servo motor, a first meshing gear pump, a second meshing gear pump, a liquid filling oil tank, a drive cylinder, a first check valve, a first relief valve, a first pressure sensor, a second check valve, a second relief valve and a second pressure sensor. Among them, the servo motor is simultaneously connected to the first internal meshing gear pump and the second internal meshing gear pump; one end of the first internal meshing gear pump is connected to the rodless cavity of the drive cylinder through a pipeline, and the other end of the first meshing gear pump is connected to the liquid filling oil tank through a pipeline; one end of the second internal meshing gear pump is connected to the rod chamber of the drive cylinder through a pipeline, and the other end of the second meshing gear pump is connected to the liquid filling oil tank through a pipeline. According to the electro-hydraulic servo drive unit of the embodiment of the present invention, it has both pressure signal and flow signal control functions, and can improve the accuracy and safety of driving.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydraulic drive, and particularly relates to an electro-hydraulic servo drive unit and its application. Background Art

[0002] At present, lower limb exoskeletons are mainly applied to the rehabilitation training of human lower limbs. A wearable lower limb exoskeleton can be worn on the human body and move synchronously with the human. It can detect human motion information during dynamic walking or actively provide driving torque to help the wearer complete walking with a large load and for a long time, reducing the fatigue of the wearer. The existing lower limb exoskeleton drive systems mainly adopt valve-controlled hydraulic drive or electric drive with motors arranged at joints. The valve-controlled hydraulic drive is characterized by low drive efficiency due to the load of the lower limb exoskeleton drive system following human motion information. In the electric drive, the driver is arranged at the joint position. The lower limb exoskeleton has a large inertia, a large power demand for the system, and at the same time, there are problems of self-disturbance of the system itself and poor following ability. Therefore, it is of great significance to improve and optimize the drive mode of the lower limb exoskeleton. Summary of the Invention

[0003] The object of the present invention is to provide an electro-hydraulic servo drive unit and its application.

[0004] First, according to one aspect of the present invention, the present invention provides an electro-hydraulic servo drive unit, including a servo motor, a first meshing gear pump, a second meshing gear pump, a filling oil tank, a first oil circuit, a second oil circuit, a first one-way valve, a first overflow valve, a first pressure sensor, a second one-way valve, a second overflow valve, and a second pressure sensor.

[0005] Preferably, the servo motor is simultaneously connected to the first internal meshing gear pump and the second internal meshing gear pump; one oil port of the first internal meshing gear pump is connected to the first oil circuit, and the other oil port of the first meshing gear pump is connected to the filling oil tank through a pipeline; one oil port of the second internal meshing gear pump is connected to the second oil circuit, and the other oil port of the second meshing gear pump is connected to the filling oil tank through a pipeline.

[0006] Further, one end of the first pressure sensor is connected to the servo motor through a pipeline, and the other end of the first pressure sensor is connected to the first oil circuit through a pipeline.

[0007] Further, one end of the first one-way valve is connected to the first oil circuit through a pipeline, and the other end of the first one-way valve is connected to the filling oil tank through a pipeline.

[0008] Further, one end of the first overflow valve is connected to the first oil circuit through a pipeline, and the other end of the first overflow valve is connected to the filling oil tank through a pipeline.

[0009] Further, one end of the second pressure sensor is communicated with the servo motor through an oil pipe, and the other end of the second pressure sensor is communicated with the second oil circuit through an oil pipe.

[0010] Further, one end of the second one-way valve is communicated with the second oil circuit through an oil pipe, and the other end of the second one-way valve is communicated with the liquid filling oil tank through an oil pipe.

[0011] Further, one end of the second overflow valve is communicated with the second oil circuit through an oil pipe, and the other end of the second overflow valve is communicated with the liquid filling oil tank through an oil pipe.

[0012] Further, the rotation directions of the first internal gear pump and the second internal gear pump are opposite.

[0013] According to another aspect of the present invention, the present invention also relates to the application of the above electro-hydraulic servo drive unit in a lower limb exoskeleton hydraulic drive system.

[0014] Compared with the prior art, the electro-hydraulic servo drive unit of the present invention has both pressure signal and flow signal control functions, which can improve the driving accuracy and safety. It can be applied to the drive system of wearable lower limb exoskeleton robots, reduce the lower limb inertia while improving the energy efficiency of the lower limb exoskeleton drive system, play a boosting function, and at the same time can feedback drive information, which can improve the coordination between the lower limb exoskeleton and human movement, and ensure the correspondence and consistency between the lower limb exoskeleton drive movement and the human lower limb joint movement during dynamic walking. It can be applied to objects that need to assist walking and bearing weight, and can also help lower limb exoskeletons for the rehabilitation of those with mild lower limb movement disorders. Description of the Drawings

[0015] The present invention will be further described in detail below in conjunction with the drawings and specific embodiments.

[0016] Figure 1 is the structural schematic diagram of the electro-hydraulic servo drive unit of the present invention;

[0017] Figure 2 is the application schematic diagram of the electro-hydraulic servo drive unit of the present invention in a lower limb exoskeleton system;

[0018] In the figure, A1 - servo motor, A2 - first internal gear pump, A3 - second internal gear pump, A4 - liquid filling oil tank, A5 - first oil circuit, A6 - second oil circuit, A7 - first one-way valve, A8 - first overflow valve, A9 - first pressure sensor, A10 - second one-way valve, A11 - second overflow valve, A12 - second pressure sensor, A13 - drive cylinder, A131 - rodless cavity of the drive cylinder, A132 - rod cavity of the drive cylinder, B - oil pipe of the rod cavity of the joint, C - oil pipe of the rodless cavity of the joint, D - joint drive cylinder, E - total liquid filling oil tank, F - cable, G - controller. Detailed Embodiments

[0019] The embodiments of the present invention are described in detail below through specific examples. However, the following specific embodiments are essentially only examples, and the present invention can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0020] Unless otherwise specified, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those skilled in the art. In addition to the specific methods, devices, and materials used in the embodiments, according to the knowledge of those skilled in the art of the prior art and the description of the present invention, any methods, devices, and materials of the prior art similar to or equivalent to those described in the embodiments of the present invention can also be used to implement the present invention.

[0021] As Figure 1 shown, the first exemplary embodiment of the present invention provides a electro-hydraulic servo drive unit, including a servo motor A1, a first meshing gear pump A2, a second meshing gear pump A3, a liquid filling oil tank A4, a first oil circuit A5, a second oil circuit A6, a first one-way valve A7, a first overflow valve A8, a first pressure sensor A9, a second one-way valve A10, a second overflow valve A11, and a second pressure sensor A12.

[0022] Specifically, the servo motor A1 is simultaneously connected to both the first internal meshing gear pump A2 and the second internal meshing gear pump A3; the rotation directions of the first internal meshing gear pump A2 and the second internal meshing gear pump A3 are opposite.

[0023] One oil port at one end of the first internal meshing gear pump A2 is connected to the first oil circuit A5, and the oil port at the other end of the first meshing gear pump A2 is connected to the liquid filling oil tank A4 through a pipeline.

[0024] One end of the first pressure sensor A9 is connected to the servo motor A1 through a pipeline, and the other end of the first pressure sensor A9 is connected to the first oil circuit A5 through a pipeline.

[0025] One end of the first one-way valve A7 is connected to the first oil circuit A5 through a pipeline, and the other end of the first one-way valve A7 is connected to the liquid filling oil tank A4 through a pipeline.

[0026] One end of the first overflow valve A8 is connected to the first oil circuit A5 through a pipeline, and the other end of the first overflow valve A8 is connected to the liquid filling oil tank A4 through a pipeline.

[0027] One oil port at one end of the second internal meshing gear pump A3 is connected to the second oil circuit A6, and the oil port at the other end of the second meshing gear pump A3 is connected to the liquid filling oil tank A4 through a pipeline.

[0028] One end of the second pressure sensor A12 is connected to the servo motor A1 through an oil pipe, and the other end of the second pressure sensor A12 is connected to the second oil circuit A6 through an oil pipe.

[0029] One end of the second check valve A10 is connected to the second oil circuit A6 through an oil pipe, and the other end of the second check valve A10 is connected to the fluid filling tank A4 through an oil pipe.

[0030] One end of the second relief valve A11 is connected to the second oil circuit A6 through an oil pipe, and the other end of the second relief valve A11 is connected to the fluid filling tank A4 through an oil pipe.

[0031] The operating principle of the electro-hydraulic servo drive unit in this embodiment is as follows:

[0032] When the driving cylinder A13 extends, the servo motor A1 rotates forward. The hydraulic oil is pressurized by the first internal gear pump A2 from the fluid filling tank A4 and enters the rodless cavity A131 of the driving cylinder through the first oil circuit A5. At the same time, the second internal gear pump A3 sucks out the oil in the rod chamber A132 of the driving cylinder and returns it to the fluid filling tank A4 through the second oil circuit A6. When the oil input by the first internal gear pump A2 into the rodless cavity A131 of the driving cylinder exceeds the oil volume required for the full stroke of the rodless cavity A131 of the driving cylinder, causing the oil pressure in this circuit to rise, the first pressure sensor A9 sends a signal to the servo motor A1, causing the servo motor A1 to decelerate or stop, playing a protective role. If a fault occurs during the extension process of the driving cylinder A13 and the servo motor A1 fails to stop in time, resulting in an increase in oil pressure, the oil can return to the fluid filling tank A4 through the first relief valve A8. The first check valve A7 can ensure the oil pressure between the first internal gear pump A2 and the driving cylinder A13, and can play a role in ensuring the one-way flow of oil when the first internal gear pump A2 sucks oil from the driving cylinder A13. The second check valve A10 can ensure the oil pressure between the second internal gear pump A3 and the driving cylinder A13, and can play a role in ensuring the one-way flow of oil when the second internal gear pump A3 sucks oil from the driving cylinder A13.

[0033] When the driving cylinder A13 contracts, the servo motor A1 reverses, and the hydraulic oil is pressurized by the second internal gear pump A3 from the liquid filling tank A4 and enters the rod chamber A132 of the driving cylinder through the second oil circuit A6. At the same time, the first internal gear pump A2 sucks out the oil in the rodless chamber A131 of the driving cylinder and returns it to the liquid filling tank A4 through the first oil circuit A5. When the oil input by the second internal gear pump A3 into the rod chamber A132 of the driving cylinder exceeds the oil volume required for the full stroke of the rod chamber A132 of the driving cylinder, causing the oil pressure in this circuit to rise, the second pressure sensor A12 sends a signal to the servo motor A1, causing the servo motor A1 to decelerate or stop, playing a protective role. If a fault occurs during the contraction process of the driving cylinder A13 and the servo motor A1 fails to stop in time, resulting in an increase in oil pressure, the oil can return to the liquid filling tank A4 through the second relief valve A11.

[0034] The electro-hydraulic servo drive unit of this embodiment has both pressure signal and flow signal control functions, which can improve the accuracy and safety of driving.

[0035] As Figure 2 shown, the second exemplary embodiment of the present invention provides the application of the electro-hydraulic servo drive unit in the lower limb exoskeleton hydraulic drive system. The controller G issues an instruction, and the electro-hydraulic servo drive unit A extracts oil from the total liquid filling tank E and supplies it to the joint driving cylinder D through the rod chamber oil pipe B of the joint and the rodless chamber oil pipe C of the joint, realizing the extension or retraction of the joint driving cylinder D and driving the joint to move.

[0036] When the servo motor A1 rotates forward, the first internal gear pump A2 sucks oil from the liquid filling main fuel tank E and outputs the flow rate to the rodless cavity of the joint drive cylinder D, pushing the joint drive cylinder D to extend. At this time, the second internal gear pump A3 sucks the oil in the rod cavity of the joint drive cylinder D into the liquid filling main fuel tank D. The output flow rates of the first internal gear pump A2 and the second internal gear pump A3 are adjusted by regulating the rotation speed of the servo motor A1 through the controller G, thereby regulating the movement speed of the joint drive cylinder D. The position accuracy of the movement of the joint drive cylinder D is adjusted by controlling the rotation position accuracy of the servo motor A1. The first check valve A7 and the second check valve A10 are used to realize the pressure of the oil in the joint drive cylinder D and achieve one-way flow. When the oil output from the second internal gear pump A3 to the rodless cavity of the joint drive cylinder D exceeds the oil volume required for the full stroke of the rodless cavity of the joint drive cylinder D, causing the oil pressure in this circuit to rise, the first pressure sensor A9 and the second pressure sensor A12 connected between the second internal gear pump A3 and the joint drive cylinder D send signals to the servo motor A1, causing the rotation speed of the servo motor A1 to decrease, thereby controlling the oil flow rate entering the rodless cavity of the joint drive cylinder D and playing a safety protection role. When a fault occurs during the extension movement of the joint drive cylinder D, overload protection is achieved through the first relief valve A8 and the second relief valve A11. During the extension movement of the joint drive cylinder D, when the oil volume discharged from the rod cavity of the joint drive cylinder D during the full stroke cannot meet the oil suction requirement of the second internal gear pump A3, the liquid filling main fuel tank E can play a role in supplementary oil supply. The liquid filling fuel tank E can also provide damping for the system and improve the stability of the system. When the servo motor A1 rotates in reverse, the working principle of the joint drive cylinder D is the same as above.

[0037] The electro-hydraulic servo drive unit of this embodiment can be applied to the drive system of a wearable lower limb exoskeleton robot, reducing the lower limb inertia while improving the energy efficiency of the lower limb exoskeleton drive system, playing a boosting function, and at the same time being able to feedback drive information, improving the coordination between the lower limb exoskeleton and human movement, and ensuring the correspondence and consistency between the drive movement of the lower limb exoskeleton and the movement of the human lower limb joints during dynamic walking. It can be applied to objects that need assistance in walking and carrying loads, and can also help lower limb exoskeletons for the rehabilitation of those with mild lower limb movement disorders.

[0038] The above-described embodiments of the present invention do not constitute a limitation on the protection scope of the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the claims of the present invention.

Claims

1. An electro-hydraulic servo drive unit, characterized in that, the electro-hydraulic servo drive unit includes a servo motor, a first meshing gear pump, a second meshing gear pump, a liquid filling oil tank, a first oil circuit, a second oil circuit, a first check valve, a first relief valve, a first pressure sensor, a second check valve, a second relief valve and a second pressure sensor. Among them, the servo motor is simultaneously connected to the first internal meshing gear pump and the second internal meshing gear pump; the oil port at one end of the first internal meshing gear pump is connected to the first oil circuit, and the oil port at the other end of the first meshing gear pump is connected to the liquid filling oil tank through a pipeline; the oil port at one end of the second internal meshing gear pump is connected to the second oil circuit, and the oil port at the other end of the second meshing gear pump is connected to the liquid filling oil tank through a pipeline. One end of the first pressure sensor is connected to the servo motor through a pipeline, and the other end of the first pressure sensor is connected to the first oil circuit through a pipeline. One end of the first check valve is connected to the first oil circuit through a pipeline, and the other end of the first check valve is connected to the liquid filling oil tank through a pipeline. One end of the first relief valve is connected to the first oil circuit through a pipeline, and the other end of the first relief valve is connected to the liquid filling oil tank through a pipeline. One end of the second pressure sensor is connected to the servo motor through a pipeline, and the other end of the second pressure sensor is connected to the second oil circuit through a pipeline. One end of the second check valve is connected to the second oil circuit through a pipeline, and the other end of the second check valve is connected to the liquid filling oil tank through a pipeline. One end of the second relief valve is connected to the second oil circuit through a pipeline, and the other end of the second relief valve is connected to the liquid filling oil tank through a pipeline. The rotation directions of the first internal meshing gear pump and the second internal meshing gear pump are opposite.

2. Application of the electro-hydraulic servo drive unit according to any one of claims 1 in a lower limb exoskeleton hydraulic drive system.

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