Electro-hydraulic actuator

Abstract

The utility model discloses an electric hydraulic execution device. The electric hydraulic execution device comprises an oil cylinder, an oil storage tank, a two-way pump, a shuttle valve, a proportional overflow valve, a hydraulic control one-way valve, a first balance valve and a second balance valve. The oil cylinder is provided with an accommodating cavity which is provided with an opening at one end and is divided into a rod cavity and a rodless cavity by a piston connecting rod mechanism; the oil storage tank is installed on the oil cylinder and used for storing hydraulic oil. The two-way pump is communicated with the oil storage tank and is provided with two pressure ports; two input ports of the shuttle valve are connected with two pressure ports of the two-way pump; the proportional overflow valve is used for adjusting the system pressure in the electric hydraulic execution device; the hydraulic control one-way valve is provided with a control port, an oil inlet and an oil outlet, and the hydraulic control one-way valve can be controlled to be conducted according to the relation between the pressure at the control port and the system pressure; the first balance valve and the second balance valve are connected between the two pressure ports and the rod cavity and between the two pressure ports and the rodless cavity respectively. Through the arrangement, the oil way design is simplified, and the overall lightweight degree of the product is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of hydraulic systems, in particular to an electric hydraulic actuator. BACKGROUND

[0002] EHA is a closed pump control integrated device which uses servo motor to provide power and integrates adjustment, monitoring and auxiliary elements, and is widely used in aerospace, ship and automobile fields.

[0003] A conventional electric hydraulic actuator includes a bidirectional pump, a common motor, two main oil paths, a piston cylinder, two one-way balance valves, two hydraulic control one-way valves and two overflow valves. The two suction and pressure oil ports of the bidirectional pump are communicated with the two main oil paths respectively. The suction oil port of the bidirectional pump is communicated with a filter, and the discharge oil port is directly returned to an oil tank. The motor and the bidirectional pump are fixed with a valve block and connected through a shaft coupling. The two one-way balance valves, the two hydraulic control one-way valves and the two overflow valves are located in the valve block. The two suction and pressure oil ports of the bidirectional pump are connected with the two main oil paths through two inlet and outlet ports respectively.

[0004] As can be seen, in the related art, the electric hydraulic actuator needs two overflow valves and two hydraulic control one-way valves, which makes the overall oil path of the electric hydraulic actuator more complex and the design more difficult, and is not conducive to the lightweight design of the product. CONTENT OF THE INVENTION

[0005] In order to solve the problems of the prior art, the purpose of the present application is to provide an electric hydraulic actuator with a simpler oil path and a higher degree of overall lightweight.

[0006] To achieve the above-mentioned purpose, the present application adopts the following technical solution:

[0007] An electric hydraulic actuator includes an oil cylinder, an oil tank, a bidirectional pump, a shuttle valve, a proportional overflow valve, a hydraulic control one-way valve, a first balance valve and a second balance valve. The oil cylinder has a cavity with an open end, and a piston connecting rod mechanism is arranged in the cavity. The piston connecting rod mechanism divides the cavity into a rod cavity and a rodless cavity. The piston connecting rod mechanism includes a connecting rod extending in the open direction, and the connecting rod is located in the rod cavity. The oil tank is mounted on the oil cylinder and is used to store hydraulic oil. The bidirectional pump is communicated with the oil tank. The two input ports of the shuttle valve are connected with the two pressure ports of the bidirectional pump respectively. One end of the proportional overflow valve is connected with the output port of the shuttle valve, and the other end is communicated with the oil tank, which is used to adjust the system pressure in the electric hydraulic actuator. The hydraulic control one-way valve has a control port, an inlet port and an outlet port communicated with one pressure port of the bidirectional pump and the oil tank respectively, and controls the one-way conduction according to the pressure difference between the control port and the system pressure. The first balance valve is connected between the rodless cavity and the other pressure port of the bidirectional pump, and the second balance valve is connected between the rod cavity and one pressure port of the bidirectional pump.

[0008] Further, the two pressure ports are defined as a first pressure port and a second pressure port, when the bidirectional pump rotates forward, the oil pressure of the first pressure port is greater than that of the second pressure port, and the electric hydraulic actuator forms a first forward oil path, a second forward oil path, a third forward oil path and a fourth forward oil path. In the first forward oil path, the first pressure port communicates with the output port of the shuttle valve through the first input port of the shuttle valve, and the output port of the shuttle valve communicates with the oil tank through the proportional overflow valve. In the second forward oil path, the first balance valve is disconnected, and the first pressure port communicates with the rodless chamber through the one-way element of the first balance valve. In the third forward oil path, the first pressure port communicates with the oil inlet port, and the oil path between the oil inlet port and the oil outlet port is disconnected. In the fourth forward oil path, the first pressure port communicates with the control end of the second balance valve, so that the second balance valve is turned on, and the rod chamber communicates with the second pressure port through the second balance valve.

[0009] Further, the system pressure is set to be greater than the opening pressure of the control end of the second balance valve, so that the second balance valve is turned on when the bidirectional pump rotates forward.

[0010] Further, the two pressure ports are defined as a first pressure port and a second pressure port, when the bidirectional pump rotates forward, the oil pressure of the first pressure port is greater than that of the second pressure port, and the electric hydraulic actuator forms a first forward oil path, a second forward oil path, a third forward oil path and a fourth forward oil path. In the first forward oil path, the first pressure port communicates with the output port of the shuttle valve through the first input port of the shuttle valve, and the output port of the shuttle valve communicates with the oil tank through the proportional overflow valve. In the second forward oil path, the first balance valve is disconnected, and the first pressure port communicates with the rodless chamber through the one-way element of the first balance valve. In the third forward oil path, the first pressure port communicates with the oil inlet port, and the oil path between the oil inlet port and the oil outlet port is disconnected. In the fourth forward oil path, the first pressure port communicates with the control end of the second balance valve, so that the second balance valve is turned on, and the rod chamber communicates with the second pressure port through the second balance valve.

[0011] Further, the system pressure is set to be greater than the opening pressure of the control end of the first balance valve, and the system pressure is greater than the opening pressure of the control port of the hydraulic control check valve, so that the first balance valve and the hydraulic control check valve are turned on when the bidirectional pump rotates backward.

[0012] Further, the electric hydraulic actuator further comprises an air filter, which communicates with the oil tank to make the space in the oil tank communicate with the atmosphere.

[0013] Further, the electric hydraulic actuator further comprises a displacement sensor connected with the piston connecting rod mechanism and a pressure sensor communicating with the rodless chamber, and the proportional overflow valve adjusts the system pressure based on the detection signals generated by the displacement sensor and the pressure sensor to close-loop control the pressure in the containing cavity and the speed of the piston connecting rod mechanism.

[0014] Furthermore, the electro-hydraulic actuator includes a first hydraulic circuit block and a second hydraulic circuit block. An oil reservoir is installed in the first hydraulic circuit block and is connected to the oil circuit in the first hydraulic circuit block. The second hydraulic circuit block is installed on the cylinder, and the oil circuit in the first hydraulic circuit block is connected to the cylinder through the oil circuit in the second hydraulic circuit block. Both the first balance valve and the second balance valve are installed in the second hydraulic circuit block and are connected to the oil circuit in the second hydraulic circuit block. When the first hydraulic circuit block is removed from the second hydraulic circuit block, the piston-connecting rod mechanism can maintain its position under the action of the first balance valve and the second balance valve.

[0015] Furthermore, the bidirectional pump is equipped with a drive motor, which is configured as a servo motor.

[0016] Furthermore, the bidirectional pump has an oil drain port that is connected to the oil reservoir.

[0017] The electro-hydraulic actuator provided in this application changes the relative pressure at the two input ports of the shuttle valve, connecting the input port with the relatively higher pressure to the output port of the shuttle valve. This alters the connection state of the oil circuit connected to the shuttle valve. Furthermore, it controls a proportional relief valve via an electrical signal to regulate the system pressure of the electro-hydraulic actuator. This reduces the number of components required for pressure regulation, allowing the system pressure of different electro-hydraulic actuators to be adjusted using only one shuttle valve and one proportional relief valve. This simplifies oil circuit design, reduces manufacturing costs, and improves the overall lightweight design of the electro-hydraulic actuator. Attached Figure Description

[0018] Figure 1 This is a schematic diagram from a first-view perspective of the electro-hydraulic actuator in the embodiments of this application;

[0019] Figure 2 This is a schematic diagram from a second perspective of the electro-hydraulic actuator in the embodiments of this application;

[0020] Figure 3 This is a hydraulic schematic diagram of the electro-hydraulic actuator in the embodiments of this application. Detailed Implementation

[0021] To enable those skilled in the art to better understand the present application, the technical solutions in specific embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings.

[0022] This application provides, as follows: Figures 1 to 3 The electro-hydraulic actuator 100 shown, as one implementation, includes a cylinder 11, an oil tank 12, a two-way pump 13, a shuttle valve 141, a proportional relief valve 142, a hydraulically controlled check valve 143, a first balance valve 151, and a second balance valve 152.

[0023] Specifically, the oil cylinder 11 has an open-ended accommodating cavity 111, and a piston connecting rod mechanism 1111 is arranged in the accommodating cavity 111, the piston connecting rod mechanism 1111 divides the accommodating cavity 111 into a rod cavity 1112 and a rodless cavity 1113, and the piston connecting rod mechanism 1111 includes a connecting rod 1111a extending in the open direction, and the connecting rod 1111a is located in the rod cavity 1112. The effective areas of the rod cavity 1112 and the rodless cavity 1113 are different, and the oil cylinder 11 can convert hydraulic energy into mechanical energy by alternately filling the rod cavity 1112 and the rodless cavity 1113.

[0024] The oil storage tank 12 is mounted on the oil cylinder 11 and is used to store hydraulic oil used by the electric hydraulic actuator 100.

[0025] The bidirectional pump 13 is in communication with the oil storage tank 12, and the bidirectional pump 13 has two pressure ports 131. When the bidirectional pump 13 rotates clockwise or counterclockwise, one of the two pressure ports 131 is used to output hydraulic oil from the bidirectional pump 13, and the other is used to suck back the hydraulic oil into the bidirectional pump 13 according to the different rotation directions. The two pressure ports 131 of the bidirectional pump are defined as a first pressure port 1311 and a second pressure port 1312, respectively. In the embodiment of the present application, the bidirectional pump 13 has a drain port 132 in communication with the oil storage tank 12. The bidirectional pump 13 may have internal leakage due to poor mechanical sealing, long-term radial jumping, and the like during operation. The drain port 132 is used to allow the leaked hydraulic oil to flow back to the oil storage tank 12 through the drain port 132 when the bidirectional pump 13 has internal leakage.

[0026] The shuttle valve 141 has two input ports 1411 and one output port 1412, the two input ports 1411 are connected with the two pressure ports 131 of the bidirectional pump 13 respectively, and the output port 1412 is connected with the proportional overflow valve 142. By controlling the rotation direction of the bidirectional pump 13, the pressure relationship between the two input ports 1411 of the shuttle valve is changed, so as to change the communication state between the two input ports 1411 and the output port 1412 of the shuttle valve, and the input port 1411 with relatively high pressure of the two input ports 1411 of the shuttle valve is communicated with the output port 1412 of the shuttle valve, so as to change the communication state of the oil circuit connected with the shuttle valve 141.

[0027] One end of the proportional overflow valve 142 is connected with the output port 1412 of the shuttle valve, and the other end is in communication with the oil storage tank 12. The proportional overflow valve 142 can be controlled by an electric signal, so as to adjust the system pressure in the electric hydraulic actuator 100.

[0028] Exemplarily, the proportional overflow valve 142 comprises a proportional electromagnet and a valve core (not shown in the figure), and an electric signal is an electric current. When the electric current passes through the proportional electromagnet, the proportional electromagnet can generate a force acting on the valve core. By adjusting the electric current passing through the proportional electromagnet, the force generated by the proportional electromagnet changes, so as to adjust the size of the valve port of the proportional overflow valve 142, and then change the flow rate and flow of the hydraulic oil passing through the proportional overflow valve 142, so as to realize the adjustment of the system pressure in the electro-hydraulic actuator 100. It should be noted that the greater the electric current passing through the proportional overflow valve 142, the greater the system pressure in the electro-hydraulic actuator 100.

[0029] The hydraulic control check valve 143 has a control port 1431 in communication with an oil passage connected between the bidirectional pump 13 and the rodless chamber 1112. If the system pressure applied to the control port 1431 is greater than the opening pressure of the control port 1431 of the hydraulic control check valve 143, the hydraulic control check valve 143 is turned on.

[0030] The hydraulic control check valve 143 also has an oil inlet port 1432 and an oil outlet port 1433 in communication with one pressure port 131 of the bidirectional pump and the oil tank 12 respectively. When the hydraulic control check valve 143 is turned off, the hydraulic oil passing through the hydraulic control check valve 143 can only flow from the oil outlet port 1433 to the oil inlet port 1432. If the hydraulic oil flows into the oil inlet port 1432 at this time, the hydraulic oil cannot flow to the oil outlet port 1433 and flow out of the hydraulic control check valve 143 through the oil outlet port 1433. When the hydraulic control check valve 143 is turned on, the hydraulic oil passing through the hydraulic control check valve 143 can flow from the oil inlet port 1432 to the oil outlet port 1433 and flow out of the hydraulic control check valve 143 through the oil outlet port 1433.

[0031] The first balance valve 151 is connected between the rodless chamber 1113 and one pressure port 131 of the bidirectional pump, and is used to limit the flow direction of the hydraulic oil in the oil passage connected by the first balance valve 151.

[0032] The first balance valve 151 has a one-way element of the first balance valve and a control end 1511 of the first balance valve. The one-way element of the first balance valve is used to make the hydraulic oil flow in one direction through the one-way element of the first balance valve when the first balance valve 151 is turned off. The control end 1511 of the first balance valve is used to control the one-way conduction of the first balance valve 151.

[0033] The first balance valve 151 also has a first valve port 1512 and a second valve port 1513. If the first balance valve 151 is turned off, the hydraulic oil can flow from the first valve port 1512 to the second valve port 1513 through the one-way element of the first balance valve. If the system pressure applied to the control end 1511 of the first balance valve is greater than the opening pressure of the first balance valve 151, the first balance valve 151 is turned on, and the hydraulic oil can flow from the second valve port 1513 to the first valve port 1512.

[0034] The second balance valve 152 is connected between the rod cavity 1112 and the other pressure port of the bidirectional pump 13, and is used to limit the flow direction of the hydraulic oil in the oil passage connected with the second balance valve 152.

[0035] The second balance valve 152 has a second balance valve one-way element and a second balance valve control end 1521, the second balance valve one-way element is used to make the hydraulic oil flow in one direction through the second balance valve one-way element when the second balance valve 152 is disconnected, and the second balance valve control end 1521 is used to control the one-way conduction of the second balance valve 152.

[0036] The second balance valve 152 also has a third valve port 1522 and a fourth valve port 1523, and if the second balance valve 152 is disconnected, the hydraulic oil can flow from the third valve port 1522 to the fourth valve port 1523 through the first balance valve one-way element. If the system pressure applied at the second balance valve control end 1521 is greater than the opening pressure of the second balance valve 152, the second balance valve 152 is turned on, and the hydraulic oil can flow from the fourth valve port 1523 to the third valve port 1522.

[0037] In the related art, the hydraulic actuator has two ordinary overflow valves and two hydraulic control one-way valves 143, which causes the need for manual adjustment of the overflow valve when adjusting the system pressure, and increases the complexity of the oil passage and the design difficulty, which is not conducive to the overall lightweight of the device.

[0038] In the embodiment of the present application, the bidirectional pump 13 can deliver hydraulic oil to different oil passages when rotating in different directions, the relative size relationship of the pressures at the two input ports 1411 of the shuttle valve 141 is changed, the input port 1411 with relatively large pressure is connected with the output port 1412 of the shuttle valve, thereby changing the communication state of the oil passage connected with the shuttle valve 141, and the proportional overflow valve 142 is controlled by the electric signal to adjust the system pressure of the electric hydraulic actuator 100.

[0039] Through the above setting, the elements required for pressure regulation are reduced under the premise of ensuring that the electric hydraulic actuator 100 can work normally, not only the system pressure of the electric hydraulic actuator 100 can be adjusted by using one shuttle valve 141 and one proportional overflow valve 142, but also the oil return of the electric hydraulic actuator 100 can be realized by one hydraulic control one-way valve 143, which reduces the leakage points of the electric hydraulic actuator 100, simplifies the oil passage design of the electric hydraulic actuator 100, reduces the manufacturing cost, and improves the overall lightweight degree of the electric hydraulic actuator 100.

[0040] As Figure 1As shown in the figure, the electro-hydraulic actuator 100 comprises a fixed part 16, which in the embodiment of the present application is provided as an intermediate hinge shaft and a front ear ring, and is fixedly installed by cooperation of the intermediate hinge shaft and the front ear ring, the front ear ring is provided with a joint bearing and a grease nipple, and the electro-hydraulic actuator 100 is provided with a dustproof sleeve.

[0041] As shown in the figure, Figure 1 As shown in the figure, the electro-hydraulic actuator 100 comprises an air filter 17 which is in communication with the oil tank 12, so that the space in the oil tank 12 is in communication with the atmosphere, thereby enabling the bidirectional pump 13 to suck hydraulic oil from the oil tank 12, while ensuring the cleanliness of the air inside the oil tank 12 and avoiding damage to the electro-hydraulic actuator 100 caused by contamination of the hydraulic oil.

[0042] As shown in the figure, Figure 2 and Figure 3 As an implementation manner, the electro-hydraulic actuator 100 comprises a displacement sensor 1531 connected with the piston connecting rod mechanism 1111 and a pressure sensor 1532 in communication with the accommodating cavity 111, the displacement sensor 1531 can monitor the position and speed of the piston connecting rod mechanism 1111 and generate a displacement monitoring signal, and the pressure sensor 1532 can monitor the pressure in the accommodating cavity 111 and generate a pressure monitoring signal, and through the displacement monitoring signal and the pressure monitoring signal, the real-time pressure in the accommodating cavity 111 and the real-time position and speed of the piston connecting rod mechanism 1111 can be determined.

[0043] As shown in the figure, Figure 3 As shown in the figure, the electro-hydraulic actuator 100 further comprises a driving motor 18 configured for the bidirectional pump 13, which is used to drive the bidirectional pump 13 to work. It should be noted that before the driving motor 18 is started, the proportional overflow valve 142 is controlled to be in a non-pressurized state, so that the no-load start of the motor can be realized without increasing other hydraulic components, thereby improving the service life of the electro-hydraulic actuator. In the embodiment of the present application, the driving motor 18 is provided as a servo motor, and by adjusting the speed of the servo motor, the speed of the bidirectional pump 13 can be changed, thereby realizing the adjustment of the speed of the piston connecting rod mechanism 1111.

[0044] Exemplarily, the pressure sensor 1532 includes a rodless cavity pressure sensor 1532a connected with the rodless cavity 1113 and a rod cavity pressure sensor 1532b connected with the rod cavity 1112. When the bidirectional pump 13 rotates clockwise, the rodless cavity pressure sensor 1532a can monitor the pressure in the rodless cavity 1113 in real time and generate a rodless cavity pressure monitoring signal, and the rod cavity pressure sensor 1532b can monitor the pressure of the rod cavity 1112 in real time and generate a rod cavity pressure monitoring signal. At this time, the pressure in the rodless cavity 1113 is higher than the pressure of the rod cavity 1112, and the proportional overflow valve 142 can adjust the system pressure in real time based on the rodless cavity pressure monitoring signal and the rod cavity pressure monitoring signal. The displacement sensor 1531 can monitor the position and speed of the piston connecting rod mechanism 1111 in real time and generate a displacement monitoring signal, and the servo motor can adjust the speed of the servo motor based on the displacement monitoring signal, thereby adjusting the speed of the piston connecting rod mechanism 1111.

[0045] Alternatively, when the bidirectional pump 13 rotates counterclockwise, the rod cavity pressure sensor 1532b can monitor the pressure in the rod cavity 1112 in real time and generate a rod cavity pressure monitoring signal, and the rodless cavity pressure sensor 1532a can monitor the pressure of the rodless cavity 1113 in real time and generate a rodless cavity pressure monitoring signal. At this time, the pressure in the rod cavity 1112 is higher than the pressure of the rodless cavity 1113, and the proportional overflow valve 142 can adjust the system pressure in real time based on the rodless cavity pressure monitoring signal and the rod cavity pressure monitoring signal. The displacement sensor 1531 can monitor the position and speed of the piston connecting rod mechanism 1111 in real time and generate a displacement monitoring signal, and the servo motor can adjust the speed of the servo motor based on the displacement monitoring signal, thereby adjusting the speed of the piston connecting rod mechanism 1111.

[0046] In the embodiments of the present application, the pressure sensor 1532 is used to monitor the pressure in the containing cavity 111 in real time, and the displacement sensor 1531 is used to monitor the speed and position of the piston connecting rod mechanism 1111 in real time. Based on the monitoring signals of the pressure sensor 1532 and the displacement sensor 1531, the working state of the electric hydraulic actuator 100 can be remotely monitored, and abnormalities can be found at the first time of failure of the electric hydraulic actuator 100. At the same time, the proportional overflow valve 142 and the servo motor can cooperate to realize closed-loop control of the pressure in the containing cavity 111 and the speed of the piston connecting rod mechanism 1111 based on the monitoring signals, thereby realizing precise synchronous control of each element in the electric hydraulic actuator 100, reducing the overall power loss of the electric hydraulic actuator 100, and improving the efficiency of the electric hydraulic actuator 100.

[0047] As an implementation manner, the electric hydraulic actuator 100 includes a first oil way block 14 and a second oil way block 15 (see Figure 2The first oil passage block 14 is fixedly connected with the second oil passage block 15, and the second oil passage block 15 is installed on the oil cylinder 11. A plurality of oil passages for hydraulic oil flow are formed in the first oil passage block 14 and the second oil passage block 15, and the oil passages in the first oil passage block 14 are communicated with the oil cylinder 11 through the oil passages in the second oil passage block 15.

[0048] Specifically, the oil tank 12, the air filter 17, the bidirectional pump 13 and the driving motor 18 are fixedly connected with the first oil passage block 14, and the oil tank 12 is communicated with the oil passages in the first oil passage block 14. At least part of the shuttle valve 141, the hydraulic control one-way valve 143 and the proportional overflow valve 142 are installed in the first oil passage block 14 and communicated with the oil passages in the first oil passage block 14. At least part of the first balance valve 151, the second balance valve 152 and the pressure sensor 1532 are installed in the second oil passage block 15 and communicated with the oil passages in the second oil passage block 15. In the case that the first oil passage block 14 is detached from the second oil passage block 15, the first balance valve 151 and the second balance valve 152 are both disconnected, and the piston connecting rod mechanism 1111 can be kept in position under the action of the first balance valve 151 and the second balance valve 152.

[0049] Through the above arrangement, at least part of the elements of the electric hydraulic actuator 100 are installed in the first oil passage block 14, and at least part of the elements of the electric hydraulic actuator 100 are installed in the second oil passage block 15, thereby improving the integration of the electric hydraulic actuator 100. In the non-working state, the electric hydraulic actuator 100 can keep in position under the action of the first balance valve 151 and the second balance valve 152, so as to replace or maintain the first oil passage block 14 and / or the elements fixedly connected with the first oil passage block 14 and / or the elements installed in the first oil passage block 14, thereby improving the convenience of maintenance of the electric hydraulic actuator 100.

[0050] As shown in FIG. 1, Figure 3 As an implementation manner, the two input ports 1411 of the shuttle valve 141 are defined as a first input port 1411a of the shuttle valve and a second input port 1411b of the shuttle valve, and the two pressure ports 131 of the bidirectional pump 13 are defined as a first pressure port 1311 and a second pressure port 1312, respectively. When the bidirectional pump 13 rotates clockwise, the oil pressure of the first pressure port 1311 is greater than that of the second pressure port 1312. At this time, the electric hydraulic actuator forms a first clockwise oil passage, a second clockwise oil passage, a third clockwise oil passage and a fourth clockwise oil passage.

[0051] In the first sequence oil path, the oil pressure of the first input port 1411a of the shuttle valve is greater than the oil pressure of the second input port 1411b of the shuttle valve, the first input port 1411a of the shuttle valve is opened, the second input port 1411b of the shuttle valve is closed, the first input port 1411a of the shuttle valve is communicated with the output port 1412 of the shuttle valve, and the output port 1412 of the shuttle valve is communicated with the oil tank 12 through the proportional overflow valve 142. At this time, the hydraulic oil can flow from the first pressure port 1311 through the first input port 1411a of the shuttle valve and the output port 1412 of the shuttle valve, and flow to the proportional overflow valve 142. When the system pressure of the electro-hydraulic actuator 100 is adjusted by the proportional overflow valve 142, the backflow hydraulic oil can flow back to the oil tank 12.

[0052] In the second sequence oil path, the first balance valve 151 is disconnected, and the first pressure port 1311 is communicated with the rodless cavity 1113 through the one-way element of the first balance valve. At this time, the hydraulic oil can flow from the first pressure port 1311 through the one-way element of the first balance valve into the rodless cavity 1113.

[0053] In the third sequence oil path, the first pressure port 1311 is communicated with the oil inlet port 1432, the control port 1431 is communicated with the second pressure port 1312, the system pressure at the control port 1431 cannot make the hydraulic control one-way valve 143 conductive, and the oil path between the oil outlet port 1433 and the oil inlet port 1432 is disconnected. At this time, the hydraulic oil flows from the first pressure port 1311 into the oil inlet port 1432, cannot enter the hydraulic control one-way valve 143, and flows out from the oil outlet port 1433.

[0054] In the fourth sequence oil path, the first pressure port 1311 is communicated with the control end 1521 of the second balance valve, and if the system pressure at the control end 1521 of the second balance valve is greater than the opening pressure of the second balance valve 152, the second balance valve 152 is conductive, and the rod cavity 1112 is communicated with the second pressure port 1312 through the second balance valve 152. At this time, the rod cavity 1112 returns oil, and the backflow hydraulic oil can flow through the one-way balance valve and flow back to the double-way pump 13 through the second pressure port 1312.

[0055] Specifically, the system pressure at the control port 1431 and the system pressure at the control end 1521 of the second balance valve are the same as the system pressure of the electro-hydraulic actuator 100, and the system pressure of the electro-hydraulic actuator 100 can be adjusted by the proportional overflow valve 142 controlled by the electric signal.

[0056] When the bidirectional pump 13 rotates clockwise, the shuttle valve 141 allows the hydraulic oil flowing from the first pressure port 1311 of the bidirectional pump 13 to flow through the shuttle valve 141 and enter the proportional relief valve 142, thereby regulating the system pressure of the electro-hydraulic actuator 100. If the system pressure is adjusted to be less than the opening pressure of the second balance valve 152, the second balance valve 152 is open, and the hydraulic oil returning from the rod chamber 1112 cannot flow through the second balance valve 152, at which point the cylinder 11 is stationary. If the system pressure is adjusted to be greater than the opening pressure of the second balance valve 152, the second balance valve 152 is open, and the hydraulic oil flowing from the first pressure port 1311 of the bidirectional pump 13 flows through the one-way component of the first balance valve into the rodless chamber 1113. The hydraulic oil returning from the rod chamber 1112 flows through the second balance valve 152 back to the second pressure port 1312 of the bidirectional pump 13, forming a circulation in the internal oil circuit of the electro-hydraulic actuator 100, at which point the cylinder 11 is in the working state.

[0057] With the above settings, the shuttle valve 141 controls the oil circuit connected to the proportional relief valve 142 when the bidirectional pump 13 rotates clockwise, and the proportional relief valve 142 adjusts the system pressure of the electro-hydraulic actuator 100, so that the oil circuit inside the electro-hydraulic actuator 100 forms a cycle or disconnects, thereby controlling the working state of the oil cylinder 11. This simplifies the oil circuit design of the electro-hydraulic actuator 100, reduces manufacturing costs, and improves the overall lightweighting of the electro-hydraulic actuator 100.

[0058] like Figure 3 Figure 3 As shown, in one implementation, when the bidirectional pump 13 rotates counterclockwise, the oil pressure at the first pressure port 1311 is less than the oil pressure at the second pressure port 1312. At this time, the electro-hydraulic actuator forms a first counterclockwise oil circuit, a second counterclockwise oil circuit, and a third counterclockwise oil circuit.

[0059] In the first counter-clockwise oil circuit, the oil pressure at the second input port 1411b of the shuttle valve 141 is greater than the oil pressure at the first input port 1411a of the shuttle valve 141. The second input port 1411b of the shuttle valve 141 is connected to the output port 1412 of the shuttle valve, and the output port 1412 of the shuttle valve is connected to the oil reservoir 12 through the proportional relief valve 142. At this time, hydraulic oil can flow from the second pressure port 1312 through the second input port 1411b and the output port 1412 of the shuttle valve 141, and flow to the proportional relief valve 142. When the proportional relief valve 142 is controlled to adjust the system pressure of the electro-hydraulic actuator 100, the returned hydraulic oil can flow back to the oil reservoir 12.

[0060] In the second counter-clockwise oil circuit, the second balance valve 152 is disconnected, and the second pressure port 1312 is connected to the rod chamber 1112 through the one-way component of the second balance valve. At this time, hydraulic oil can enter the rod chamber 1112 through the second pressure port 1312 and the one-way component of the second balance valve.

[0061] The second pressure port 1312 in the third reverse-time oil path is in communication with the control port 1431. If the system pressure at the control port 1431 is greater than the opening pressure of the hydraulic control check valve 143, the hydraulic control check valve 143 is turned on, the oil path between the oil inlet port 1432 and the oil outlet port 1433 is turned on, and the oil outlet port 1433 is in communication with the oil tank 12.

[0062] The second pressure port 1312 in the third reverse-time oil path is also in communication with the control end 1511 of the first balance valve. If the system pressure at the control end 1511 of the first balance valve is greater than the opening pressure of the first balance valve 151, the first balance valve 151 is turned on, and the rodless cavity 1113 is in communication with the first pressure port 1311 through the first balance valve 151.

[0063] At this time, the rodless cavity 1113 returns oil. The hydraulic oil returned by the rodless cavity 1113 can flow out of the rodless cavity 1113, flow through the first balance valve 151 from the second valve port 1513 to the first valve port 1512, and then directly flow back to the bidirectional pump 13 through the first pressure port 1311. Since the effective area of the rod cavity 1112 is smaller than that of the rodless cavity 1113, the hydraulic oil in the rod cavity 1112 is less than that in the rodless cavity 1113. When the rodless cavity 1113 returns oil, there will be excess hydraulic oil. The excess hydraulic oil can flow out of the rodless cavity 1113, flow through the first balance valve 151 from the second valve port 1513 to the first valve port 1512, then flow through the hydraulic control check valve 143 from the oil inlet port 1432 to the oil outlet port 1433, and finally flow back to the oil tank 12.

[0064] Specifically, the system pressure at the control port 1431 and the system pressure at the control end 1511 of the first balance valve are the same as the system pressure of the electro-hydraulic actuator 100, and the system pressure of the electro-hydraulic actuator 100 can be adjusted by the proportional overflow valve 142.

[0065] When the bidirectional pump 13 rotates reversely, the shuttle valve 141 can make the hydraulic oil flowing out of the second pressure port 1312 of the bidirectional pump 13 flow through the shuttle valve 141 into the proportional overflow valve 142 to adjust the system pressure of the electro-hydraulic actuator 100. If the system pressure is adjusted to be less than the opening pressure of the first balance valve 151 or the hydraulic control check valve 143, the first balance valve 151 or the hydraulic control check valve 143 is disconnected, and the hydraulic oil returning from the rodless chamber 1113 cannot flow through the first balance valve 151 or the hydraulic control check valve 143, at this time, the oil cylinder 11 is in a static state. If the system pressure is adjusted to be greater than the opening pressure of the first balance valve 151 and the hydraulic control check valve 143, the first balance valve 151 and the hydraulic control check valve 143 are both connected, the hydraulic oil flowing out of the second pressure port 1312 of the bidirectional pump 13 flows through the one-way component of the second balance valve into the rod chamber 1112, the hydraulic oil returning from the rodless chamber 1113 flows through the first balance valve 151 back to the first pressure port 1311 of the bidirectional pump 13, and the excess hydraulic oil flows through the hydraulic control check valve 143 back to the oil tank 12, the oil circuit inside the electro-hydraulic actuator 100 forms a circulation, at this time, the oil cylinder 11 is in a working state.

[0066] Through the above setting, the shuttle valve 141 controls the oil circuit connected with the proportional overflow valve 142 when the bidirectional pump 13 rotates reversely, and adjusts the system pressure of the electro-hydraulic actuator 100 through the proportional overflow valve 142, so that the oil circuit inside the electro-hydraulic actuator 100 is connected to form a circulation or disconnected, to control the working state of the oil cylinder 11, simplify the oil circuit design of the electro-hydraulic actuator 100, reduce the manufacturing cost, and improve the lightweight degree of the electro-hydraulic actuator 100 as a whole.

[0067] In summary, the electro-hydraulic actuator 100 provided by the present application changes the relative size relationship of the pressures at the two input ports 1411 of the shuttle valve, so that the input port 1411 with relatively large pressure is connected with the output port 1412 of the shuttle valve, thereby changing the connection state of the oil circuit connected with the shuttle valve 141, and adjusting the system pressure of the electro-hydraulic actuator 100 through the electric signal control proportional overflow valve 142. Under the premise of ensuring that the electro-hydraulic actuator 100 can work normally, the number of elements required for pressure regulation is reduced, not only one shuttle valve 141 and one proportional overflow valve 142 can be used to adjust the system pressure of the electro-hydraulic actuator 100, but also one hydraulic control check valve 143 can be used to realize the oil return of the electro-hydraulic actuator 100, reduce the leakage points of the electro-hydraulic actuator 100, simplify the oil circuit design of the electro-hydraulic actuator 100, reduce the manufacturing cost, and improve the lightweight degree of the electro-hydraulic actuator 100 as a whole.

[0068] It should be understood that all the modifications and variations can be made according to the above description by those skilled in the art, and all these modifications and variations shall belong to the protection scope of the claims attached to the present application.

Claims

1. An electro-hydraulic actuator, characterized by Comprise: a cylinder having a cavity with an open end, a piston rod mechanism is arranged in the cavity, the piston rod mechanism divides the cavity into a rod cavity and a rodless cavity, the piston rod mechanism comprises a connecting rod extending towards the open end, the connecting rod is in the rod cavity; a tank mounted on the cylinder for storing hydraulic oil; a bidirectional pump in communication with the tank; a shuttle valve, two input ports of the shuttle valve are connected with two pressure ports of the bidirectional pump respectively; a proportional relief valve, one end of the proportional relief valve is connected with an output port of the shuttle valve, the other end of the proportional relief valve is in communication with the tank, the proportional relief valve is used for adjusting the system pressure in the electro-hydraulic actuator; a hydraulic control check valve, the hydraulic control check valve has a control port, an inlet port and an outlet port, the inlet port is in communication with one pressure port of the bidirectional pump and the tank respectively, the outlet port is in communication with the other pressure port of the bidirectional pump, the hydraulic control check valve is controlled to be unidirectionally conducted according to the pressure difference between the pressure of the control port and the system pressure; and a first balance valve and a second balance valve, the first balance valve is connected between the rodless cavity and the other pressure port of the bidirectional pump, the second balance valve is connected between the rod cavity and one pressure port of the bidirectional pump.

2. The electro-hydraulic actuator according to claim 1, wherein two pressure ports are defined as a first pressure port and a second pressure port, when the bidirectional pump rotates forward, the oil pressure of the first pressure port is greater than the oil pressure of the second pressure port, the electro-hydraulic actuator forms the following oil paths: a first forward oil path, the first pressure port is in communication with the output port of the shuttle valve through the first input port of the shuttle valve, the output port of the shuttle valve is in communication with the tank through the proportional relief valve; a second forward oil path, the first balance valve is disconnected, the first pressure port is in communication with the rodless cavity through the unidirectional element of the first balance valve; a third forward oil path, the first pressure port is in communication with the inlet port, the oil path between the inlet port and the outlet port is disconnected; a fourth forward oil path, the first pressure port is in communication with the control end of the second balance valve, the second balance valve is conducted, the rod cavity is in communication with the second pressure port through the second balance valve.

3. The electro-hydraulic actuator according to claim 2, wherein the system pressure is set to be greater than the opening pressure of the control end of the second balance valve, when the bidirectional pump rotates forward, the second balance valve is conducted.

4. The electro-hydraulic actuator according to claim 1, wherein two pressure ports are defined as a first pressure port and a second pressure port, when the bidirectional pump rotates reversely, the oil pressure of the first pressure port is less than the oil pressure of the second pressure port, the electro-hydraulic actuator forms the following oil paths: a first reverse oil path, the second pressure port is in communication with the output port of the shuttle valve through the second input port of the shuttle valve, the output port of the shuttle valve is in communication with the tank through the proportional relief valve; a second reverse oil path, the second balance valve is disconnected, the second pressure port is in communication with the rod cavity through the unidirectional element of the second balance valve. ​ ​ A second reverse-time oil path, the second balance valve is closed, the second pressure port communicates with the rodless chamber through the one-way element of the second balance valve; A third reverse-time oil path, the second pressure port communicates with the control port, so that the hydraulic control check valve is conducted in the direction from the oil inlet port to the oil outlet port; the second pressure port communicates with the control end of the first balance valve, so that the first balance valve is conducted, and the rodless chamber communicates with the first pressure port through the first balance valve.

5. The electro-hydraulic actuator of claim 4, wherein the system pressure is set to be greater than the opening pressure of the control end of the first balance valve, and the system pressure is greater than the opening pressure of the control port of the hydraulic control check valve, so that the first balance valve and the hydraulic control check valve are conducted when the bidirectional pump is counterclockwise rotated.

6. The electro-hydraulic actuator of claim 1, wherein the electro-hydraulic actuator further comprises an air filter, which communicates with the oil tank, so that the space in the oil tank is communicated with the atmosphere.

7. The electro-hydraulic actuator of claim 1, wherein the electro-hydraulic actuator further comprises a displacement sensor connected with the piston-rod mechanism and a pressure sensor communicated with the accommodating cavity, and the pressure in the accommodating cavity and the speed of the piston-rod mechanism are closed-loop controlled based on the displacement sensor and the pressure sensor.

8. The electro-hydraulic actuator of claim 1, wherein the electro-hydraulic actuator comprises a first oil path block and a second oil path block, the oil tank is installed in the first oil path block and communicates with the oil path in the first oil path block, the second oil path block is installed in the oil cylinder, and the oil path in the first oil path block communicates with the oil cylinder through the oil path in the second oil path block; the first balance valve and the second balance valve are both installed in the second oil path block and communicate the oil path in the second oil path block, and the piston-rod mechanism can maintain the position under the action of the first balance valve and the second balance valve when the first oil path block is detached from the second oil path block.

9. The electro-hydraulic actuator of claim 1, wherein the bidirectional pump is configured with a driving motor, and the driving motor is set as a servo motor.

10. The electro-hydraulic actuator of claim 1, wherein the bidirectional pump has a drain port, and the drain port communicates with the oil tank. ​ ​ ​ ​ ​ ​

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