A redundantly driven electrostatic hydraulic actuator system

Abstract

The present invention discloses a redundantly driven electrostatic hydraulic actuator system, which relates to the field of hydraulic drive. The first and second servo drive motors of the system are directly connected to a planetary gear train, serving as the power input of the entire gear train. The sun gear in the planetary gear train serves as the output end of the gear train, and is further connected to the input end of a hydraulic pump. The hydraulic pump serves as the power core element of the redundantly driven electrostatic hydraulic actuator system, and its output end is directly connected to the two chambers of a hydraulic actuator, driving the hydraulic actuator to perform reciprocating linear motion (rotational motion). The planetary gear train can effectively convert the power input of the first and second servo drive motors into the forward and reverse output required by the hydraulic pump. The present invention effectively avoids the challenge of the motor crossing the zero point and the problem of the motor creeping at low speed, significantly improves the response speed and control accuracy of the electrostatic hydraulic actuator system, and improves the operating efficiency and stability.

Description

Technical Field

[0001] The invention belongs to the field of hydraulic drive, and in particular relates to a redundantly driven electrostatic hydraulic actuator system. Background Art

[0002] Among robot drive methods, hydraulic drive is widely used due to its high load and high stability. As a new hydraulic drive technology, electrostatic hydraulic actuator (EHA) has the advantages of high integration, high energy power density, and high power-to-weight ratio. However, the traditional EHA drive system usually uses a motor directly connected to a hydraulic pump to directly drive the EHA through the forward and reverse rotation of the motor. During the forward and reverse rotation of the motor, there are problems of low-speed creeping and zero-crossing, which have a great impact on the running stability and efficiency of the motor. The low-speed creeping and zero-crossing problems of the motor will have a very large impact on the efficient and smooth operation of the entire EHA. Therefore, a new drive method is needed to avoid the low-speed creeping and zero-crossing problems of the motor, improve the response speed and efficiency of the EHA system, and improve the control accuracy and stability of the EHA drive. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a redundantly driven electrostatic hydraulic actuator system, which can significantly improve the response speed and control accuracy of the EHA system, and improve the operating efficiency and stability.

[0004] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0005] A redundantly driven electrostatic hydraulic actuator system, the system comprising a first servo drive motor, a second servo drive motor, a planetary gear train, a hydraulic pump, an oil tank, a first main oil circuit, a second main oil circuit, a relief valve, a hydraulic cylinder or a hydraulic motor; wherein:

[0006] The planetary gear train includes a plurality of gears meshing with each other;

[0007] The first servo drive motor and the second servo drive motor are connected through different gears of a planetary gear system, and are used to provide power input for the planetary gear system. The first servo drive motor and the second servo drive motor always rotate in opposite directions, and the rotation direction of the hydraulic pump connected to the planetary gear system is changed based on the rotation angular velocity of the first servo drive motor and the second servo drive motor.

[0008] The output end of the hydraulic pump is connected to the rodless chamber and the rod chamber of the hydraulic cylinder, or to the oil inlet end and the oil outlet end of the hydraulic motor, respectively, through the first main oil circuit and the second main oil circuit, to drive the hydraulic cylinder to perform reciprocating linear motion or drive the hydraulic motor to perform rotational motion;

[0009] An input end of the overflow valve is connected to output ends of the first main oil circuit and the second main oil circuit, and an output end of the overflow valve is connected to the oil tank.

[0010] The beneficial effects of the present invention are:

[0011] Through the ingenious design of the planetary gear system, the power of the dual servo drive motor can be effectively converted into the output required by the hydraulic pump to supply oil to the two chambers of the hydraulic cylinder or hydraulic motor. In addition, the present invention does not require the motor to perform forward and reverse operations. It only needs to adjust the speed of the dual motors to enable the hydraulic pump to achieve forward and reverse rotation, and drive the hydraulic cylinder (hydraulic motor) to achieve reciprocating linear motion (rotational motion), thereby effectively avoiding the challenges of motor low-speed creeping and zero crossing, improving the control accuracy and response speed of the EHA system, and at the same time improving the stability and efficiency of the entire EHA system. As a transmission device, the planetary gear system can not only control the direction of the output, but also act as a reducer with a large reduction ratio, which can amplify the output torque without the need for an additional reduction box. Dual motors and dual inputs can achieve force-position hybrid control, while increasing the stiffness of the input and reducing the inertia of the output. The drive and connection devices are all modularly designed, without destroying the internal structure of the hydraulic pump, and are convenient for maintenance and replacement of components, and have a wide range of applications. It solves the problems of slow response speed, low control accuracy, and complex hydraulic circuit design in the existing pump control technology, while achieving the purpose of high efficiency and energy saving. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 The schematic diagram is a structural diagram of a redundantly driven electrostatic hydraulic actuator system of the present invention.

[0013] Reference numerals:

[0014] 1. First servo drive motor, 2. Second servo drive motor, 3. First gear, 4. Second gear, 5. Third gear, 6. Fourth gear, 7. Fifth gear, 8. Sixth gear, 9. Hydraulic pump, 10. Oil tank, 11. First one-way valve, 12. Second one-way valve, 13. Overflow valve, 14. Third one-way valve, 15. Fourth one-way valve, 16. Hydraulic cylinder. DETAILED DESCRIPTION

[0015] The purpose of the present invention is to solve the problems of low-speed creeping and zero-crossing in the forward and reverse rotation process of the motor during the EHA driving process. The present invention will provide a new redundantly driven EHA system, which can significantly improve the response speed and control accuracy of the EHA system, and improve the operating efficiency and stability.

[0016] In order to make the above-mentioned objects, features and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with the accompanying drawings. The hydraulic actuator in the accompanying drawings is represented by a hydraulic cylinder, and the implementation method of the hydraulic motor is the same, and no further description is given.

[0017] Please refer to Figure 1 , is a schematic structural diagram of a redundantly driven electrostatic hydraulic actuator system of the present invention;

[0018] The redundantly driven electrostatic hydraulic actuator system includes a first servo drive motor 1 , a second servo drive motor 2 , a set of planetary gear trains, a hydraulic pump 9 , an oil tank 10 , a first main oil circuit, a second main oil circuit, a relief valve 13 , and a hydraulic cylinder 16 .

[0019] The planetary gear system includes a first gear 3, a second gear 4, a third gear 5, a fourth gear 6, a fifth gear 7, and a sixth gear 8. The first gear 3 is externally meshed with the second gear 4. The second gear 4 is also a planet carrier, connecting the third gear 5 and the fifth gear 7. The third gear 5 is externally meshed with the fourth gear 6 and internally meshed with the sixth gear 8. The fourth gear 6 is externally meshed with the third gear 5 and the fifth gear 7. The fifth gear 7 is externally meshed with the fourth gear 6 and externally meshed with the sixth gear 8. The sixth gear 8 is internally meshed with the third gear 5 and the fifth gear 7. The sixth gear 8 is connected to the hydraulic pump 9 to drive the hydraulic pump 9 to rotate.

[0020] The first servo drive motor 1 is directly connected to the fourth gear 6 in the planetary gear train, driving the fourth gear 6 to rotate, and serves as the first power input of the entire gear train.

[0021] The second servo drive motor 2 is directly connected to the first gear 3 in the planetary gear train, driving the first gear 3 to rotate, and serves as the second power input of the entire gear train.

[0022] according to Figure 1 The rotation speed expression of the sixth gear 8 can be solved as follows:

[0023] (1)

[0024] In the formula is the angular velocity of the sixth gear 8, is the angular velocity of the first servo drive motor 1 (ie, the fourth gear 6), is the angular velocity of the second servo drive motor 2 (ie, the first gear 3), is the number of teeth of the first gear 3, is the number of teeth of the second gear 4, is the number of teeth of the fourth gear 6, is the number of teeth of the sixth gear 8. According to expression (1), it can be seen that in order to make the output of the sixth gear 8 realize forward and reverse rotation, that is, The value of can be positive or negative, then , The signs of must be opposite, that is, the first servo drive motor 1 and the second servo drive motor 2 always rotate in opposite directions. It is stipulated that the rotation direction of the first servo drive motor 1 is the positive direction, and the rotation direction of the second servo drive motor 2 is the negative direction. When it satisfies , the output rotation direction of the sixth gear 8 is positive, driving the hydraulic pump 9 to rotate positively, thereby driving the hydraulic cylinder 16 to move downward. Similarly, when the speeds of the first servo drive motor 1 and the second servo drive motor 2 meet When the sixth gear 8 is output, the rotation direction is negative, driving the hydraulic pump 9 to rotate in the opposite direction, and then driving the hydraulic cylinder 16 to move upward. In this way, by using the planetary gear system, it is only necessary to control the rotation speed of the first servo drive motor 1 and the second servo drive motor 2, and the output rotation direction can be controlled without the need for forward and reverse rotation of the motor, which cleverly avoids the low-speed creep and zero-crossing problems that occur during the forward and reverse installation of the motor, improves the response speed and control accuracy of the EHA system, and improves the stability and efficiency of the entire EHA system.

[0025] The oil suction pipe of the hydraulic pump 9 is located below the oil level of the oil tank 10. The input end of the hydraulic pump 9 is connected to the sixth gear 8 in the planetary gear system. The output end of the hydraulic pump 9 is directly connected to the rodless chamber and the rod chamber of the hydraulic cylinder 16 through the first main oil circuit and the second main oil circuit, driving the hydraulic cylinder 16 to perform reciprocating linear motion.

[0026] The first main oil circuit includes a first one-way valve 11 and a third one-way valve 14, the input end of the first one-way valve 11 is connected to the output end of the hydraulic pump 9, the output end of the first one-way valve 11 is connected to the rodless chamber of the hydraulic cylinder 16, the input end of the third one-way valve 14 is connected to the rodless chamber of the hydraulic cylinder 16 and the output end of the first one-way valve 11, and the output end of the third one-way valve 14 is connected to the input end of the overflow valve 13.

[0027] The second main oil circuit includes a second one-way valve 12 and a fourth one-way valve 15, the input end of the second one-way valve 12 is connected to the output end of the hydraulic pump 9, the output end of the second one-way valve 12 is connected to the rod chamber of the hydraulic cylinder 16, the input end of the fourth one-way valve 15 is connected to the rod chamber of the hydraulic cylinder 16 and the output end of the second one-way valve 12, and the output end of the fourth one-way valve 15 is connected to the input end of the overflow valve 13.

[0028] The input end of the overflow valve 13 is connected to the output ends of the third check valve 14 and the fourth check valve 15 , and the output end of the overflow valve 13 is connected to the oil tank 10 .

[0029] The first servo drive motor 1 and the second servo drive motor 2 can effectively convert the power input of the first servo drive motor 1 and the second servo drive motor 2 into the output required by the hydraulic pump 9 through the planetary gear system.

[0030] The first servo drive motor 1 and the second servo drive motor 2 cause the hydraulic pump 9 to achieve forward and reverse rotation due to the different rotation speeds, thereby driving the hydraulic cylinder 16 to achieve reciprocating linear motion.

[0031] The first servo drive motor 1 is connected to the fourth gear 6 in the planetary gear system via a coupling.

[0032] The second servo drive motor 2 is connected to the first gear 3 in the planetary gear system through a coupling.

[0033] The sixth gear 8 in the planetary gear train is connected to the hydraulic pump 9 via a coupling.

[0034] The oil inlet of the overflow valve 13 is connected to the oil outlets of the third one-way valve 14 and the fourth one-way valve 15 , and the oil outlet pipe of the overflow valve 13 is inserted below the oil level of the oil tank 10 .

[0035] A rolling bearing is installed between the shaft of the second gear 4 in the planetary gear train and the shaft of the fourth gear 6 in the planetary gear train.

[0036] A rolling bearing is installed at the connection between the shafts of the second gear 4 in the planetary gear train and the third gear 5 in the planetary gear train.

[0037] A rolling bearing is installed at the connection between the shafts of the second gear 4 in the planetary gear train and the fifth gear 7 in the planetary gear train.

[0038] The redundantly driven electrostatic hydraulic actuator system further comprises a planetary gear reduction housing, and a rolling bearing is installed at the contact point between the sixth gear 8 in the planetary gear system and the inner wall of the planetary gear reduction housing.

[0039] A rolling bearing is installed at the contact point between the shaft of the first gear 3 in the planetary gear system and the inner wall of the planetary gear reduction housing.

[0040] A rolling bearing is installed at the contact point between the shaft of the second gear 4 in the planetary gear system and the inner wall of the planetary gear reduction housing.

[0041] A rolling bearing is installed at the contact point between the shaft of the third gear 5 in the planetary gear system and the inner wall of the planetary gear reduction housing.

[0042] The redundantly driven electrostatic hydraulic actuator system further includes a first servo motor driver and a second servo motor driver, wherein the first servo motor driver is connected to the first servo drive motor 1 , and the second servo motor driver is connected to the second servo drive motor 2 .

[0043] The redundantly driven electrostatic hydraulic actuator system further includes a controller, which is connected to the first servo motor driver and the second servo motor driver, respectively, to control the first servo motor driver and the second servo motor driver to drive the first servo drive motor 1 and the second servo drive motor 2.

[0044] The redundantly driven electrostatic hydraulic actuator system further comprises a sensor, wherein the sensor comprises a pressure sensing unit and a displacement sensing unit;

[0045] The pressure sensing unit is connected between the hydraulic rod of the hydraulic cylinder 16 and the workpiece, and the data line of the pressure sensing unit is connected to the controller;

[0046] The displacement sensing unit is connected between the hydraulic rod of the hydraulic cylinder 16 and the cylinder body of the hydraulic cylinder 16 , and a data line of the displacement sensing unit is connected to the controller.

[0047] By feeding back the pressure sensing data and displacement sensing data to the controller through the sensor, the controller can dynamically adjust the power applied to the first servo drive motor 1 and the second servo drive motor 2 to control their rotation speeds, thereby completing the closed-loop control of the entire system.

[0048] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0049] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A redundantly driven electrostatic hydraulic actuator system, characterized in that: The system includes a first servo drive motor, a second servo drive motor, a planetary gear train, a hydraulic pump, an oil tank, a first main oil circuit, a second main oil circuit, a relief valve, a hydraulic cylinder or a hydraulic motor; wherein, The planetary gear train includes a plurality of gears meshing with each other; The first servo drive motor and the second servo drive motor are connected through different gears of a planetary gear system, and are used to provide power input for the planetary gear system. The first servo drive motor and the second servo drive motor always rotate in opposite directions, and the rotation direction of the hydraulic pump connected to the planetary gear system is changed based on the rotation angular velocity of the first servo drive motor and the second servo drive motor. The output end of the hydraulic pump is connected to the rodless chamber and the rod chamber of the hydraulic cylinder, or to the oil inlet end and the oil outlet end of the hydraulic motor, respectively, through the first main oil circuit and the second main oil circuit, to drive the hydraulic cylinder to perform reciprocating linear motion or drive the hydraulic motor to perform rotational motion; An input end of the overflow valve is connected to output ends of the first main oil circuit and the second main oil circuit, and an output end of the overflow valve is connected to the oil tank.

2. A redundantly driven electrostatic hydraulic actuator system according to claim 1, characterized in that: The planetary gear system includes a first gear, a second gear, a third gear, a fourth gear, a fifth gear, and a sixth gear. The first gear is externally meshed with the second gear. The second gear is also a planet carrier, connecting the third gear and the fifth gear. The third gear is externally meshed with the fourth gear. The fourth gear is externally meshed with the third gear and the fifth gear. The fifth gear is externally meshed with the fourth gear and the sixth gear. The sixth gear is internally meshed with the third gear and the fifth gear. The sixth gear is connected to the hydraulic pump to drive the hydraulic pump to rotate. The first servo drive motor is connected to the fourth gear, and the second servo drive motor is connected to the first gear.

3. A redundantly driven electrostatic hydraulic actuator system according to claim 2, characterized in that: The changing of the rotation direction of the hydraulic pump connected to the planetary gear train based on the rotation angular velocity of the first servo drive motor and the second servo drive motor comprises: The expression for solving the rotation speed of the sixth gear is as follows: = (1) In the formula, is the angular velocity of the sixth gear, is the angular velocity of the first servo drive motor, is the angular velocity of the second servo drive motor, is the number of teeth of the first gear, is the number of teeth of the second gear, is the number of teeth of the fourth gear, is the number of teeth of the sixth gear; The first servo drive motor is defined as rotating in a positive direction, and the second servo drive motor is defined as rotating in a negative direction; When satisfied > >0, the rotation direction of the output sixth gear is positive, driving the hydraulic pump to rotate forward, driving the hydraulic cylinder to move downward or the hydraulic motor to rotate forward; When 0< < When the sixth gear is output, the rotation direction is negative, driving the hydraulic pump to rotate in the opposite direction, driving the hydraulic cylinder to move upward or the hydraulic motor to rotate in the opposite direction.

4. The redundantly driven electrostatic hydraulic actuator system according to claim 3, characterized in that: The first servo drive motor is connected to the fourth gear in the planetary gear system through a coupling; the second servo drive motor is connected to the first gear in the planetary gear system through a coupling; the sixth gear in the planetary gear system is connected to the hydraulic pump through a coupling.

5. The redundantly driven electrostatic hydraulic actuator system according to claim 4, characterized in that: The first main oil circuit includes a first one-way valve and a third one-way valve, the input end of the first one-way valve is connected to the output end of the hydraulic pump, the output end of the first one-way valve is connected to the rodless chamber of the hydraulic cylinder or the oil inlet end of the hydraulic motor, the input end of the third one-way valve is connected to the output end of the first one-way valve and the rodless chamber of the hydraulic cylinder or the oil inlet end of the hydraulic motor, and the output end of the third one-way valve is connected to the input end of the overflow valve; The second main oil circuit includes a second one-way valve and a fourth one-way valve, the input end of the second one-way valve is connected to the output end of the hydraulic pump, the output end of the second one-way valve is connected to the rod chamber of the hydraulic cylinder or the oil outlet end of the hydraulic motor, the input end of the fourth one-way valve is connected to the output end of the second one-way valve and the rod chamber of the hydraulic cylinder or the oil outlet end of the hydraulic motor, and the output end of the fourth one-way valve is connected to the input end of the overflow valve; The oil inlet of the overflow valve is connected to the oil outlets of the third one-way valve and the fourth one-way valve, and the oil outlet pipe of the overflow valve is inserted below the oil level of the oil tank.

6. The redundantly driven electrostatic hydraulic actuator system according to claim 5, characterized in that: A rolling bearing is installed between the shaft of the second gear in the planetary gear train and the shaft of the fourth gear in the planetary gear train.

7. The redundantly driven electrostatic hydraulic actuator system according to claim 6, characterized in that: A rolling bearing is installed at the connection between the shafts of the second gear in the planetary gear train and the third gear in the planetary gear train.

8. The redundantly driven electrostatic hydraulic actuator system according to claim 7, characterized in that: A rolling bearing is installed at the connection between the shafts of the second gear in the planetary gear train and the fifth gear in the planetary gear train.

9. The redundantly driven electrostatic hydraulic actuator system according to claim 8, characterized in that: The redundantly driven electrostatic hydraulic actuator system further comprises a planetary gear reduction housing, and a rolling bearing is installed at the contact point between the sixth gear in the planetary gear train and the inner wall of the planetary gear reduction housing; A rolling bearing is installed at the contact point between the shaft of the first gear in the planetary gear train and the inner wall of the planetary gear reduction housing; A rolling bearing is installed at the contact point between the shaft of the second gear in the planetary gear train and the inner wall of the planetary gear reduction housing; A rolling bearing is installed at the contact point between the shaft of the third gear in the planetary gear train and the inner wall of the planetary gear reduction housing.

10. The redundantly driven electrostatic hydraulic actuator system according to claim 9, characterized in that: The redundantly driven electrostatic hydraulic actuator system further includes a first servo motor driver and a second servo motor driver, wherein the first servo motor driver is connected to the first servo drive motor, and the second servo motor driver is connected to the second servo drive motor.

11. The redundantly driven electrostatic hydraulic actuator system according to claim 10, characterized in that: The redundantly driven electrostatic hydraulic actuator system further includes a controller, which is connected to the first servo motor driver and the second servo motor driver, respectively, and controls the first servo motor driver and the second servo motor driver to drive the first servo drive motor and the second servo drive motor.

12. The redundantly driven electrostatic hydraulic actuator system according to claim 11, characterized in that: The redundantly driven electrostatic hydraulic actuator system further comprises a sensor, wherein the sensor comprises a pressure sensing unit and a displacement sensing unit; The pressure sensing unit is connected between the hydraulic rod of the hydraulic cylinder or the output shaft of the hydraulic motor and the workpiece, and a data line of the pressure sensing unit is connected to the controller; The displacement sensing unit is connected between the hydraulic rod of the hydraulic cylinder and the hydraulic cylinder body, or between the output shaft of the hydraulic motor and the hydraulic motor body, and a data line of the displacement sensing unit is connected to the controller.

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