Electro-hydrostatic actuator system and working machine

Abstract

The utility model relates to the technical field of electro-hydraulic control, and discloses an electro-hydrostatic actuator system and an operating machine.The system comprises a first oil port, a second oil port, a first oil way and a second oil way, the first oil way and the second oil way are arranged in parallel and used for being connected with the first oil port and the second oil port, and in the direction from the first oil port to the second oil port, the first oil way is connected with the second oil way. A first valve, a radiator and an oil supplementing pump are sequentially arranged on the first oil way, and under the conditions that oil returns from the first oil port and the electro-hydrostatic actuator system is in a first working condition, the first valve cuts off the flowing of returned oil to the radiator; and under the condition that the first oil port returns oil and the electro-hydrostatic actuator system is in the second working condition, the oil supplementing pump pressurizes the second oil port, so that return oil of the first oil port flows to the second oil port through the first oil way, the effect that the return oil of the system completely flows into the radiator can be achieved, and the heat dissipation effect is enhanced.

Description

Technical Field

[0001] The present application belongs to the field of electro-hydraulic control technology, and specifically relates to an electro-static hydraulic actuator system. In addition, it also relates to an operating machine. Background Art

[0002] In order to simplify the hydraulic system, realize device integration and lightweight, most of the electro-hydraulic integrated actuators adopt closed hydraulic systems. In closed hydraulic systems, internal leakage of each hydraulic component and friction of moving parts cannot be dissipated externally like open hydraulic systems. The heat generated will be absorbed by the hydraulic oil and hydraulic components of the system, causing the oil temperature of the hydraulic system to rise. The internal circulation of the oil cannot dissipate the heat generated by the system, and the system temperature rises too quickly to achieve high-frequency operation. At the same time, if the hydraulic oil temperature is too high, the hydraulic oil will oxidize and fail, shorten the service life of the hydraulic oil, accelerate the wear of the hydraulic components, and increase impurities, thereby posing the risk of blocking the pipeline or jamming the hydraulic components.

[0003] Hydraulic oil is used as a direct contact heat transfer medium in the hydraulic system. Oil cooling can efficiently remove heat from the hydraulic oil in a relatively small space. At the same time, compared with other heat dissipation methods (such as water cooling), oil cooling radiators are usually more compact and take up less space, so traditional hydraulic systems mostly use oil cooling. However, the current oil cooling radiator cannot withstand high pressure and cannot be directly connected to the electro-hydraulic integrated actuator. It is mostly introduced into the radiator through a flushing loop or by utilizing the volume difference caused by the asymmetric volume of the asymmetric cylinder. However, the flow through the radiator is limited, and most of the flow will flow directly to the pump suction port and circulate directly, resulting in poor heat dissipation effect. Utility Model Content

[0004] The purpose of the present application is to provide an electrostatic hydraulic actuator system, which can achieve that the system return oil flow completely flows into the radiator, thereby enhancing the heat dissipation effect. The second purpose of the present application is to provide an operating machine.

[0005] In order to achieve the above-mentioned object, the first aspect of the present application provides an electrostatic hydraulic actuator system, comprising a first oil port, a second oil port, a first oil circuit and a second oil circuit, wherein the first oil circuit and the second oil circuit are arranged in parallel and are both used to connect the first oil port and the second oil port, and in the direction from the first oil port to the second oil port, the first oil circuit is sequentially provided with a first valve, a radiator and an oil replenishment pump;

[0006] When the first oil port returns oil and the electrostatic hydraulic actuator system is in a first working condition, the first valve is configured to cut off the return oil from flowing to the radiator; when the first oil port returns oil and the electrostatic hydraulic actuator system is in a second working condition, the charge pump is configured to pressurize the second oil port so that the return oil from the first oil port flows to the second oil port through the first oil path;

[0007] The oil return pressure of the first oil port under the first working condition is greater than the oil return pressure of the first oil port under the second working condition.

[0008] In some specific embodiments, a back-pressure valve is further included, and the back-pressure valve is arranged on the first oil circuit and located between the first valve and the radiator.

[0009] In some specific embodiments, the first valve is a directional control valve, the directional control valve includes a first hydraulic control end and a second hydraulic control end, the first hydraulic control end is connected to the first oil port, the second hydraulic control end is connected to the third oil port, when one of the first oil port and the third oil port is in the oil return state, the other is in the oil intake state, and the directional control valve is configured as follows:

[0010] When the oil pressure of the first hydraulic control end is greater than the oil pressure of the second hydraulic control end, disconnecting the first oil port from the radiator;

[0011] When the oil pressure of the first hydraulic control end is lower than the oil pressure of the second hydraulic control end, the first oil port is connected to the radiator.

[0012] In some specific embodiments, it also includes an actuator, a main pump, a third oil port, a fourth oil port and a third oil circuit for connecting the third oil port and the fourth oil port, the first oil port and the third oil port are respectively connected to the two ends of the actuator, and the second oil port and the fourth oil port are respectively connected to the two ends of the main pump.

[0013] In some specific embodiments, an oil replenishment circuit is further included, the oil replenishment circuit is connected between the second oil port and the fourth oil port, and a first oil replenishment valve and a second oil replenishment valve are provided on the oil replenishment circuit, the first oil circuit is connected to the oil replenishment circuit, and is connected between a pair of the first oil replenishment valve and the second oil replenishment valve.

[0014] In some specific embodiments, an oil replenishment overflow valve is further included. The oil replenishment overflow valve is arranged in parallel with the oil replenishment pump, and the oil replenishment oil circuit is connected to the oil tank through the oil replenishment overflow valve.

[0015] In some specific embodiments, the first oil replenishing valve and the second oil replenishing valve are hydraulically controlled one-way valves, the hydraulic control chamber of the first oil replenishing valve is communicated with the fourth oil port, and the hydraulic control chamber of the second oil replenishing valve is communicated with the second oil port.

[0016] In some specific implementations, the first oil port and the third oil port are respectively provided with load holding valves on the oil circuits for connecting to the actuator.

[0017] In some specific embodiments, pressure detection devices are respectively disposed on the oil circuits of the first oil port and the third oil port for connecting to the actuator.

[0018] A second aspect of the present application provides a working machine provided with an electrostatic hydraulic actuator system as described in any one of the above-mentioned technical solutions.

[0019] Through the above technical scheme, when the electrostatic hydraulic actuator system is in the second working condition with relatively low return oil pressure, the oil replenishing pump is controlled to increase the pressure of the second oil port, so that the return oil of the first oil port flows to the second oil port through the first oil circuit, so that all the return oil flows to the second oil port through the radiator to realize return oil heat dissipation, and the heat exchange oil is not affected by the system, thereby enhancing the heat dissipation effect; and when the electrostatic hydraulic actuator system is in the first working condition with relatively high return oil pressure, the first valve effectively cuts off the return oil flow to the radiator, thereby avoiding damage to the radiator by the return oil high pressure, thereby ensuring the smooth operation of the subsequent heat dissipation of the hydraulic system.

[0020] Other features and advantages of the embodiments of the present application will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings are used to provide a further understanding of the embodiments of the present application and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the embodiments of the present application, but do not constitute a limitation on the embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without creative work. In the drawings:

[0022] Figure 1 It is a hydraulic principle diagram of the electrostatic hydraulic actuator system in a specific embodiment of the present application;

[0023] Figure 2 is a block diagram of a control strategy of an electrostatic hydraulic actuator system that can be applied in a specific embodiment of the present application;

[0024] Figure 3 The present invention is a flowchart of a control method applicable to an electrostatic hydraulic actuator system.

[0025] Description of Reference Numerals

[0026] 1-actuator; 2-load holding valve; 3-radiator; 31-cooling circuit; 4-oil replenishing pump; 51-oil replenishing oil circuit; 52-first oil replenishing valve; 53-second oil replenishing valve; 6-safety valve; 7-main pump; 8-oil replenishing overflow valve; 9-oil tank; 10-back pressure valve; 11-directional control valve; 12-pressure detection device; 101-first working oil circuit; 102-second working oil circuit. DETAILED DESCRIPTION

[0027] The specific implementation of the embodiment of the present application is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the embodiment of the present application, and is not used to limit the embodiment of the present application.

[0028] First of all, it should be noted that if the implementation methods of the present application involve directional indications (such as up, down, left, right, front, back...), then the directional indications are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0029] In addition, if there are descriptions involving "first", "second", etc. in the implementation methods of this application, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various implementation methods can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0030] Secondly, it should be noted that the electrostatic hydraulic actuator system of the present application belongs to the field of hydraulics. For technicians in this field, its substantial technical concept lies in the hydraulic connection relationship. Relevant hydraulic components, such as reversing valves, one-way valves, overflow valves, hydraulic pumps, etc. are all well known to those skilled in the art, and are also commonly used components in existing hydraulic systems. Therefore, these hydraulic components are only briefly described below. After knowing the technical concept of the present application, those skilled in the art can also simply replace the oil circuit or valves, etc., so as to realize the function of the electrostatic hydraulic actuator system of the present application, which also falls within the scope of protection of the present application.

[0031] Existing oil cooling methods mostly use flushing loops or utilize the volume difference caused by the asymmetric capacity of asymmetric cylinders to introduce the heat into the radiator, but the flow through the radiator is limited. That is to say, in the existing oil cooling methods, the return oil used for heat exchange is greatly affected by the system, and the return oil cannot be completely made to flow through the radiator. The flow through the radiator is limited, and the heat dissipation effect is poor.

[0032] In view of the technical problems existing in the above-mentioned prior art, such as Figure 1 As shown, the present application first exemplarily provides an electrostatic hydraulic actuator system, which includes a first oil port A, a second oil port B, a first oil circuit and a second oil circuit. The first oil circuit and the second oil circuit are arranged in parallel and are both used to connect the first oil port A and the second oil port B. In the direction from the first oil port A to the second oil port B, the first oil circuit is sequentially provided with a first valve, a radiator 3 and an oil replenishment pump 4. It should be noted that the first oil port A and the second oil port B can be conventional oil ports in the valve body, or nodes in the flow channel in the valve body or nodes in the hydraulic pipeline. These nodes are drawn out to facilitate the connection relationship between the components in the electrostatic hydraulic actuator system, and there may be no specific position reference.

[0033] Through the above technical scheme, when the oil returns to the first oil port A and the electrostatic hydraulic actuator system is in the first working condition, the first valve effectively cuts off the return oil flow to the radiator 3; when the oil returns to the first oil port A and the electrostatic hydraulic actuator system is in the second working condition, the oil replenishment pump 4 increases the pressure of the second oil port B to make the return oil of the first oil port A flow to the second oil port B through the first oil circuit; wherein, the return oil pressure of the first oil port A under the first working condition is greater than the return oil pressure of the first oil port A under the second working condition. Therefore, when the electrostatic hydraulic actuator system is in the second working condition with relatively low return oil pressure, the replenishing oil pump 4 can be controlled to increase the pressure of the second oil port B, so that the return oil of the first oil port A flows to the second oil port B through the first oil circuit, so that all the return oil flows to the second oil port B through the radiator to realize return oil heat dissipation, and the heat exchange oil is not affected by the system, thereby enhancing the heat dissipation effect; and when the electrostatic hydraulic actuator system is in the first working condition with relatively high return oil pressure, the first valve can effectively cut off the return oil flow to the radiator 3, thereby effectively avoiding the return oil high pressure from damaging the radiator 3, thereby ensuring the smooth and reliable operation of the subsequent heat dissipation of the hydraulic system. In addition, the present application is applicable not only to open circuits but also to closed circuits. When applied to a closed circuit, under the first working condition, the high-pressure return oil cannot flow to the oil inlet end of the radiator 3 through the first oil port A. At the same time, due to the presence of the oil replenishment pump 4, the high-pressure return oil is effectively prevented from flowing to the return oil end of the radiator 3 through the second oil port B, thereby ensuring that the return oil high pressure cannot act on the radiator 3. Under the second working condition, since the oil replenishment pump 4 pressurizes the second oil port B, all the return oil in the closed circuit can be effectively dissipated through the radiator 3, thereby improving the heat dissipation efficiency. Moreover, the oil replenishment pump 4 pressurizes the second oil port B, thereby helping to optimize the oil suction condition of the oil supply pump in the closed circuit, thereby increasing the upper limit of the speed of the oil supply pump and thereby improving the working capacity.

[0034] In some embodiments, see Figure 1 The electrostatic actuator system also includes a back-pressure valve 10, which is arranged in the first oil circuit and located between the first valve and the radiator 3, so that when the current working condition is in the second working condition, the oil replenishment pump 4 can increase the pressure of the second oil port B to make the pressure of the first oil port A greater than the opening pressure of the back-pressure valve 10, thereby making the return oil of the first oil port A flow back to the second oil port B through the first oil circuit.

[0035] In combination with some examples, the above-mentioned first working condition can be a negative load working condition (or called an overtaking load working condition), and the second working condition can be a positive load working condition (or called an impedance load working condition). In some embodiments, the electrostatic hydraulic actuator of the present invention can identify the working condition to control the first valve to control the corresponding working condition, for example, obtain the movement direction and load direction of the actuator 1, and identify whether it is the first working condition or the second working condition according to whether the movement direction and load direction of the actuator 1 are the same. The first valve is a directional control valve 11, and a specific embodiment of the directional control valve 11 is an electrically controlled directional control valve, and is connected to a controller. The controller controls the electrical signal of the electrically controlled end of the electrically controlled directional control valve according to the result of identifying that the current working condition is in the first working condition or the second working condition, thereby realizing the on-off control of the directional control valve 11 between the first oil port A and the radiator 3.

[0036] In other examples, the first working condition and the second working condition can also be simply distinguished by combining the relative size of the return oil pressure of the first oil port A and the inlet oil pressure of the oil inlet corresponding to the first oil port A. Based on this concept, another specific embodiment of the directional control valve 11 is a hydraulically controlled directional control valve, see Figure 1 , which includes a first hydraulic control end and a second hydraulic control end, the first hydraulic control end is connected to the first oil port A, and the second hydraulic control end is connected to the third oil port C. When one of the first oil port A and the third oil port C is in the oil return state, the other is in the oil inlet state, so that the oil pressure of the two oil ports is introduced into the hydraulic control ends on both sides for pressure comparison. The directional control valve 11 is configured as follows: when the oil pressure of the first hydraulic control end is greater than the oil pressure of the second hydraulic control end, that is, under the first working condition, the first oil port A is disconnected from the radiator 3; when the oil pressure of the first hydraulic control end is less than the oil pressure of the second hydraulic control end, that is, under the second working condition, the first oil port A is connected to the radiator 3.

[0037] In some embodiments, see Figure 1The electrostatic hydraulic actuator system also includes an actuator 1, a main pump 7, a third oil port C, a fourth oil port D, and a third oil circuit for connecting the third oil port C and the fourth oil port D. The first oil port A and the third oil port C are respectively connected to the two ends of the actuator 1, and the second oil port B and the fourth oil port D are respectively connected to the two ends of the main pump, thereby forming a closed loop. It should be noted that the above-mentioned first oil circuit forms the return oil circuit of the actuator 1, and the third oil circuit is the oil inlet oil circuit of the actuator 1. When the movement direction of the actuator 1 changes, the first oil circuit forms the oil inlet oil circuit of the actuator 1, and the third oil circuit is the return oil circuit of the actuator 1. At this time, when the current working condition is in the first working condition, that is, the return oil pressure of the third oil port C is greater than the inlet oil pressure of the first oil port A, the first valve (directional control valve 11) cuts off the return oil flow to the radiator 3. When the current working condition is in the second working condition, that is, the return oil pressure of the third oil port C is less than the inlet oil pressure of the first oil port A, the replenishing pump 4 pressurizes the fourth oil port D so that the return oil of the third oil port C flows to the fourth oil port D through the first oil circuit.

[0038] In order to better understand the technical solution of the electrostatic hydraulic actuator system of the present application, Figure 1 The electrostatic hydraulic actuator system shown illustrates the technical solution of the electrostatic hydraulic actuator system of the present application.

[0039] like Figure 1As shown, an embodiment of the present application provides an electrostatic hydraulic actuator system, including an actuator 1, a main pump 7, a directional control valve 11, a back pressure valve 10, a radiator 3, an oil replenishment pump 4 and a heat dissipation circuit 31. The actuator 1 is connected to the main pump 7 through a first working oil circuit 101 and a second working oil circuit 102 to form a closed circuit. The main pump 7 delivers hydraulic oil to the actuator 1 through the first working oil circuit 101 and the second working oil circuit 102 to drive the actuator 1 to operate, wherein the heat dissipation circuit 31 corresponds to the first oil circuit, one of the first working oil circuit 101 and the second working oil circuit 102 corresponds to the second oil circuit, and the other corresponds to the third oil circuit. The directional control valve 11, the back pressure valve 10, the radiator 3 and the oil replenishment pump 4 are sequentially arranged on the heat dissipation circuit 31, and the hydraulic control valves at both ends of the directional control valve 11 are connected to the main pump 7 through a first working oil circuit 101 and a second working oil circuit 102 to form a closed circuit. The main pump 7 delivers hydraulic oil to the actuator 1 through the first working oil circuit 101 and the second working oil circuit 102 to drive the actuator 1 to operate, wherein the heat dissipation circuit 31 corresponds to the first oil circuit, and one of the first working oil circuit 101 and the second working oil circuit 102 corresponds to the second oil circuit, and the other corresponds to the third oil circuit. The directional control valve 11, the back pressure valve 10, the radiator 3 and the oil replenishment pump 4 are sequentially arranged on the heat dissipation circuit 31, and the hydraulic control valves at both ends of the directional control valve 11 are connected to the main pump 7 through a first working oil circuit 101 and a second working oil circuit 102 to form a closed circuit. The chambers are respectively connected to the first working oil circuit 101 and the second working oil circuit 102, and the back pressure valve 10, the radiator 3 and the oil replenishment pump 4 are all arranged on the heat dissipation circuit 31; when the actuator 1 works in the second working condition, the pressure on the oil inlet side of the actuator 1 is greater than the pressure on the oil return side of the actuator 1, and the direction control valve 11 is controlled to change direction, so that the oil return port of the actuator 1 is connected to the back pressure valve 10 through the direction control valve 11. At this time, the oil replenishment pump 4 can regulate the pressure of the oil return port of the actuator 1, so that the pressure of the oil return port of the actuator 1 is greater than the opening pressure of the back pressure valve 10, so that the back pressure valve 10 is opened, so that the return oil of the actuator 1 can completely flow to the radiator 3 through the back pressure valve 10 for heat dissipation, without being affected by the system, thereby enhancing the heat dissipation effect, and then, the hydraulic oil that has been heat-dissipated flows to the oil suction port of the main pump 7. The replenishing oil pump 4 can also pressurize the main pump 7, optimize the oil suction condition of the main pump 7, so that the main pump 7 can further increase its upper speed limit and improve the working capacity of the actuator 1; when the actuator 1 works in the first working condition, the pressure on the oil inlet side of the actuator 1 is less than the pressure on the oil return side of the actuator 1, and the direction control valve 11 is controlled to change direction, so that the oil return port of the actuator 1 and the back pressure valve 10 are cut off, effectively isolating the high-pressure oil in the oil return chamber of the actuator 1, so that the radiator 3 is not affected by the high pressure of the return oil. In the preferred case, the replenishing oil pump 4 will also run at a low speed to replenish oil to the oil inlet of the actuator 1. Among them, the second working condition can be an impedance load condition, and the first working condition can be an overrunning load condition. The impedance load condition refers to an execution action condition in which the hydraulic force is opposite to the load force, and the overrunning load condition refers to an execution action condition in which the hydraulic force is in the same direction as the load force.

[0040] In some embodiments, the directional control valve 11 may be a flushing valve, see Figure 1 , preferably a three-position three-way flushing valve.

[0041] In some embodiments, the actuator 1 may be a hydraulic cylinder. To better illustrate the technical solution of the present application, the following describes various embodiments using the actuator 1 as an example of a hydraulic cylinder. Of course, the actuator 1 may also be other actuator devices, such as a hydraulic motor, etc. When the actuator 1 is other actuator devices, it can be understood by referring to the case where the actuator 1 is a hydraulic cylinder.

[0042] In addition, in the following embodiment in which the actuator 1 is a hydraulic cylinder, the first working oil circuit 101 is described as the third oil circuit, and the second working oil circuit 102 is described as the second oil circuit; of course, the first working oil circuit 101 can also be used as the second oil circuit, and correspondingly, the second working oil circuit 102 is used as the third oil circuit, which can be understood by referring to the situation where the second oil circuit and the third oil circuit are set oppositely.

[0043] In some embodiments, the oil replenishment circuit 51 is further included, the oil replenishment circuit 51 is connected between the second oil port and the fourth oil port, and the first oil replenishment valve 52 and the second oil replenishment valve 53 are arranged on the oil replenishment circuit 51, and the first oil circuit is connected to the oil replenishment circuit 51 and is connected between the pair of the first oil replenishment valve 52 and the second oil replenishment valve 53. Figure 1 One end of the oil replenishing circuit 51 is connected to the fourth oil port D of the first working oil circuit 101, and the other end of the oil replenishing circuit 51 is connected to the second oil port B of the second working oil circuit 102. A pair of oil replenishing valves (a first oil replenishing valve 52 and a second oil replenishing valve 53) are provided on the oil replenishing circuit 51. The second oil replenishing valve 53 is arranged close to the first working oil circuit 101, and the first oil replenishing valve 52 is arranged close to the second working oil circuit 102. The heat dissipation circuit 31 is connected to the oil replenishing circuit 51, and the connection point between the heat dissipation circuit 31 and the oil replenishing circuit 51 is located between the pair of first oil replenishing valves 52 and the second oil replenishing valve 53.

[0044] Further, the first oil replenishment valve 52 and the second oil replenishment valve 53 may be hydraulically controlled one-way valves, the hydraulic control chamber of the first oil replenishment valve 52 is connected to the fourth oil port D, and the hydraulic control chamber of the second oil replenishment valve 53 is connected to the second oil port B. Figure 1 , the hydraulic control chamber of the second oil replenishment valve 53 is connected to the second working oil circuit 102, and the hydraulic control chamber of the first oil replenishment valve 52 is connected to the first working oil circuit 101. At the same time, the first working oil circuit 101 connects the main pump 7 with the large chamber of the actuator 1, that is, the first working oil circuit 101 is connected to the large chamber through the third oil port C, and the heat dissipation circuit 31 is connected to the third oil port C. The second working oil circuit 102 connects the main pump 7 with the small chamber of the actuator 1, that is, the second working oil circuit 102 is connected to the small chamber through the first oil port A, and the heat dissipation circuit 31 is connected to the first oil port A.

[0045] When the actuator 1 works in the second working condition and the actuator 1 is in the extended state, at this time, the pressure of the large chamber of the actuator 1 is greater than the pressure of the small chamber of the actuator 1, the first working oil circuit 101 serves as the oil inlet side, and delivers hydraulic oil to the large chamber of the actuator 1, and the second working oil circuit 102 serves as the oil return side, and the small chamber of the actuator 1 returns oil through the second working oil circuit 102, and the pressure of the third oil port C is greater than the pressure of the first oil port A. Under the pressure of the first oil port A and the third oil port C, the directional control valve 11 is switched, that is, it is in Figure 1 The left position function in the oil circuit makes the oil circuit between the first oil port A of the second working oil circuit 102 and the back pressure valve 10 connected. At the same time, the first oil replenishing valve 52 connected to the second working oil circuit 102 is in the open state, so that the oil replenishing pump 4 can adjust the pressure of the second oil port B, so that the pressure of the first oil port A is greater than the opening pressure of the back pressure valve 10, and the back pressure valve 10 is opened. According to the hydraulic principle, the return oil of the small chamber of the actuator 1 will completely pass through the first oil port A and the directional control valve 11 to the back pressure valve 10 in sequence, and then flow to the radiator 3 through the back pressure valve 10 for heat dissipation. After the heat is dissipated, the return oil will flow back to the second oil port B through the first oil replenishing valve 52 and flow to the suction port of the main pump 7. It can be seen that through the regulating effect of the supplementary oil pump 4, not only can the return oil side be pressurized so that the return oil can completely flow to the radiator 3 through the back pressure valve 10 for heat dissipation, but also the main pump 7 can be pressurized to optimize the oil suction condition of the main pump 7, so that the main pump 7 can further increase its upper speed limit and improve the working capacity of the electro-hydraulic actuator.

[0046] Similarly, when the actuator 1 works in the second working condition and the actuator 1 is in the retracted state, at this time, the pressure of the large chamber of the actuator 1 is less than the pressure of the small chamber of the actuator 1, and the first working oil circuit 101 serves as the return oil side, and returns oil to the large chamber of the actuator 1 through the first working oil circuit 101, and the second working oil circuit 102 serves as the inlet oil side, and delivers hydraulic oil to the small chamber of the actuator 1. The pressure of the first oil port A is greater than the pressure of the third oil port C. Under the pressure of the first oil port A and the third oil port C, the directional control valve 11 is switched, that is, it is in Figure 1 The right position function in the oil circuit makes the oil circuit between the third oil port C of the first working oil circuit 101 and the back pressure valve 10 connected. At the same time, the second oil replenishing valve 53 is in the open state, so that the oil replenishing pump 4 can adjust the pressure of the fourth oil port D, so that the pressure of the third oil port C is greater than the opening pressure of the back pressure valve 10, and the back pressure valve 10 is opened. According to the hydraulic principle, the return oil of the small chamber of the actuator 1 will completely pass through the third oil port C and the directional control valve 11 to the back pressure valve 10 in sequence, and then flow to the radiator 3 through the back pressure valve 10 for heat dissipation. After the heat is dissipated, the return oil will flow back to the fourth oil port D through the second oil replenishing valve 53 and flow to the suction port of the main pump 7.

[0047] When the actuator 1 works in the first working condition and the actuator 1 is in the extended state, at this time, the pressure of the large chamber of the actuator 1 is less than the pressure of the small chamber of the actuator 1, the first working oil circuit 101 serves as the oil inlet side, and delivers hydraulic oil to the large chamber of the actuator 1, the second working oil circuit 102 serves as the oil return side, and the small chamber of the actuator 1 returns oil through the second working oil circuit 102, and the pressure of the third oil port C is less than the pressure of the first oil port A. Under the pressure of the first oil port A and the third oil port C, the directional control valve 11 is switched, that is, it is in Figure 1 The right position function in the oil circuit cuts off the oil circuit between the first oil port A of the second working oil circuit 102 and the back pressure valve 10, effectively isolating the high-pressure oil on the return oil side of the actuator 1, so that the radiator 3 is not affected by the return oil high pressure. At the same time, under the pressure of the second working oil circuit 102, the second oil replenishment valve 53 is in an open state, and the oil replenishment pump 4 will run at a low speed, which can replenish oil to the fourth oil port D of the first working oil circuit 101 to prevent the large cavity of the actuator 1 from being sucked empty. Moreover, in the technical solution of the present application, for the return oil, the speed of the oil replenishment pump 4 and the main pump 7 can be lowered to control the speed of the actuator 1 to prevent stalling.

[0048] Similarly, when the actuator 1 works in the first working condition and the actuator 1 is in the retracted state, at this time, the pressure of the large chamber of the actuator 1 is greater than the pressure of the small chamber of the actuator 1, the first working oil circuit 101 serves as the return oil side, and returns oil to the large chamber of the actuator 1 through the first working oil circuit 101, and the second working oil circuit 102 serves as the inlet oil side, and delivers hydraulic oil to the small chamber of the actuator 1. The pressure of the first oil port A is less than the pressure of the third oil port C. Under the pressure of the first oil port A and the third oil port C, the directional control valve 11 is switched, that is, it is in Figure 1 The left position function cuts off the oil circuit between the third oil port C of the first working oil circuit 101 and the back pressure valve 10, effectively isolating the high-pressure oil on the return oil side of the actuator 1, so that the radiator 3 is not affected by the return oil high pressure. At the same time, under the pressure of the first working oil circuit 101, the first oil replenishment valve 52 is in an open state, and the oil replenishment pump 4 can replenish oil to the second oil port B of the second working oil circuit 102 to prevent the small cavity of the actuator 1 from being sucked into the air.

[0049] In some embodiments, Figure 1 As shown, the oil replenishment relief valve 8 is also included. The oil replenishment relief valve 8 is arranged in parallel with the oil replenishment pump 4. The oil replenishment oil circuit 51 is connected to the oil tank 9 through the oil replenishment relief valve 8, and the oil replenishment pump 4 is also connected to the oil tank 9. After the return oil of the actuator 1 passes through the radiator 3, part of the hydraulic oil flows to the oil tank 9, and the other part of the hydraulic oil flows to the oil replenishment pump 4, and under the action of the oil replenishment pump 4, it is used to increase the pressure on the return oil side of the actuator 1 and the pressure on the oil suction port of the main pump 7.

[0050] In some embodiments, the first oil port A and the third oil port C are used to connect the oil circuits of the actuator 1 and are respectively provided with load holding valves 2. Figure 1 A load holding valve 2 is provided between the first working oil circuit 101 and the second working oil circuit 102 and the oil inlet and outlet of the actuator 1, respectively, for achieving load holding of the actuator 1 in a loaded stationary state.

[0051] In some embodiments, the first oil port A and the third oil port C are used to connect the oil circuits of the actuator 1 and are respectively provided with pressure detection devices 12. Figure 1 A pressure detection device 12 is provided between the first working oil circuit 101 and the second working oil circuit 102 and the oil inlet and outlet of the actuator 1, respectively, for detecting the pressure of the large cavity and the small cavity of the actuator 1. Specifically, the pressure detection device 12 is a device for pressure detection, such as a pressure sensor.

[0052] In some embodiments, a safety valve 6 is provided between the first working oil circuit 101 and the second working oil circuit 102 .

[0053] like Figure 1As shown, a preferred embodiment of the present application provides an electrostatic hydraulic actuator system, including an actuator 1, a main pump 7, a directional control valve 11, a back pressure valve 10, a radiator 3, an oil replenishment pump 4 and a heat dissipation circuit 31. The actuator 1 is a hydraulic cylinder. The large chamber of the actuator 1 is connected to the main pump 7 through a first working oil circuit 101, and the small chamber of the actuator 1 is connected to the main pump 7 through a second working oil circuit 102. Load holding valves 2 are respectively provided at positions near the actuator 1 on the first working oil circuit 101 and the second working oil circuit 102, for achieving load holding of the actuator 1 in a loaded static state. Pressure detection devices 12 are respectively provided at positions near the actuator 1 on the first working oil circuit 101 and the second working oil circuit 102, for detecting the pressure of the large chamber and the small chamber of the actuator 1. The pressure detection device 12 is located between the actuator 1 and the load holding valve 2. The heat dissipation circuit 31 is arranged in parallel with the first working oil circuit 101 and the second working oil circuit 102. The heat dissipation circuit 31 is sequentially provided with a directional control valve 11, a back pressure valve 10, a radiator 3 and an oil replenishment pump 4. The directional control valve 11 is connected to the third oil port C of the first working oil circuit 101, and the connection point is located between the load holding valve 2 and the main pump 7. The directional control valve 11 is connected to the first oil port A of the second working oil circuit 102, and the connection point is located between the load holding valve 2 and the main pump 7. In addition, the heat dissipation circuit 31 is connected to the oil replenishing circuit 51, one end of the oil replenishing circuit 51 is connected to the fourth oil port D of the first working oil circuit 101, and the other end of the oil replenishing circuit 51 is connected to the second oil port B of the second working oil circuit 102. The first oil replenishing valve 52 and the second oil replenishing valve 53 are provided on the oil replenishing circuit 51, the second oil replenishing valve 53 is arranged close to the first working oil circuit 101, and the first oil replenishing valve 52 is arranged close to the second working oil circuit 102. The connection point between the heat dissipation circuit 31 and the oil replenishing circuit 51 is located between the first oil replenishing valve 52 and the second oil replenishing valve 53; the first oil replenishing valve 52 and the second oil replenishing valve 53 can be hydraulically controlled one-way valves, and the hydraulic control cavity of the second oil replenishing valve 53 is connected to the second working oil circuit 102, and the hydraulic control cavity of the first oil replenishing valve 52 is connected to the first working oil circuit 101. The oil replenishment overflow valve 8 is connected in parallel with the oil replenishment pump 4, the oil replenishment oil circuit 51 is connected to the oil tank 9 through the oil replenishment overflow valve 8, and the oil replenishment pump 4 is also connected to the oil tank 9. A safety valve 6 is provided between the first working oil circuit 101 and the second working oil circuit 102. Among them, the directional control valve 11 can be a three-position three-way flushing valve.

[0054] Combination Figure 1, combined with some specific application examples, when the current working condition is the second working condition, and the actuator 1 is in the extended state, at this time, the pressure of the large chamber of the actuator 1 is greater than the pressure of the small chamber of the actuator 1, the first working oil circuit 101 serves as the oil inlet side, and delivers hydraulic oil to the large chamber of the actuator 1, the second working oil circuit 102 serves as the oil return side, and the small chamber of the actuator 1 returns oil through the second working oil circuit 102, and the pressure of the third oil port C is greater than the pressure of the first oil port A. Under the pressure of the above-mentioned oil inlet side and the oil return side, the directional control valve 11 is switched, that is, it is in Figure 1 The left position function in the oil circuit makes the oil circuit between the first oil port A of the second working oil circuit 102 and the back pressure valve 10 connected, and the oil replenishment pump 4 can adjust the pressure on the return oil side so that the pressure of the first oil port A is greater than the opening pressure of the back pressure valve 10, and the back pressure valve 10 is opened, and the return oil of the small chamber of the actuator 1 will completely flow to the back pressure valve 10 through the directional control valve 11, and then flow to the radiator 3 through the back pressure valve 10 for heat dissipation. Alternatively, when the current working condition is the second working condition, and the actuator 1 is in the retracted state, at this time, the pressure of the large chamber of the actuator 1 is less than the pressure of the small chamber of the actuator 1, the first working oil circuit 101 serves as the return oil side, and returns oil to the large chamber of the actuator 1 through the first working oil circuit 101, and the second working oil circuit 102 serves as the inlet oil side, and delivers hydraulic oil to the small chamber of the actuator 1. The pressure of the first oil port A is greater than the pressure of the third oil port C. Under the pressure of the first oil port A and the third oil port C, the directional control valve 11 is switched, that is, it is in Figure 1 The right position function in the oil circuit makes the oil circuit between the third oil port C of the first working oil circuit 101 and the back pressure valve 10 conductive, and the oil replenishment pump 4 can adjust the pressure on the return oil side so that the pressure of the third oil port C is greater than the opening pressure of the back pressure valve 10, and the back pressure valve 10 is opened. According to the hydraulic principle that the fluid always flows in the direction of low pressure, the return oil of the small chamber of the actuator 1 will completely flow to the back pressure valve 10 through the direction control valve 11, and then flow to the radiator 3 through the back pressure valve 10 for heat dissipation. Through the regulating effect of the oil replenishment pump 4, the return oil side can be pressurized so that the return oil can completely flow to the radiator 3 through the back pressure valve 10 for heat dissipation. It is not affected by the system, the heat dissipation effect is enhanced, and the heat dissipation requirements of the electro-hydraulic actuator under high-frequency and high-load conditions are met, and no additional medium is required, it is easy to maintain, and the layout cost is low.

[0055] Moreover, the return oil after heat dissipation can flow to the oil suction port of the main pump 7 through the oil replenishment pump 4. Since the oil replenishment pump 4 pressurizes the return oil side, that is, the main pump 7 is pressurized, the oil suction condition of the main pump 7 is optimized, so that the main pump 7 can further increase its speed limit and improve the working capacity of the electro-hydraulic actuator.

[0056] In some specific application examples, when the current working condition is the first working condition, the speed of the replenishing pump 4 is lowered, and the replenishing pump 4 is controlled to replenish oil to the oil inlet of the actuator 1. Specifically, when the current working condition is the first working condition, and the actuator 1 is in the extended state, at this time, the pressure of the large chamber of the actuator 1 is less than the pressure of the small chamber of the actuator 1, and the first working oil circuit 101 serves as the oil inlet side to deliver hydraulic oil to the large chamber of the actuator 1, and the second working oil circuit 102 serves as the oil return side, and the small chamber of the actuator 1 returns oil through the second working oil circuit 102. The pressure of the third oil port C is less than the pressure of the first oil port A. Under the pressure of the first oil port A and the third oil port C, the directional control valve 11 is switched, that is, it is in Figure 1 The right position function in the second working oil circuit cuts off the oil circuit between the first oil port A of the second working oil circuit 102 and the back pressure valve 10, effectively isolating the high-pressure oil on the return oil side of the actuator 1, so that the radiator 3 is not affected by the return oil high pressure. At the same time, under the pressure of the second working oil circuit 102, the second oil replenishment valve 53 is in the open state, and the oil replenishment pump 4 will run at a low speed, which can replenish oil to the first working oil circuit 101 to prevent the large cavity of the actuator 1 from being sucked empty. Alternatively, when the current working condition is the first working condition, and the actuator 1 is in the retracted state, the pressure of the first oil port A is less than the pressure of the third oil port C, so that the directional control valve 11 is in Figure 1 The left position function cuts off the oil circuit between the third oil port C of the first working oil circuit 101 and the back pressure valve 10, effectively isolating the high-pressure oil on the return oil side of the actuator 1, so that the radiator 3 is not affected by the return oil high pressure. The first oil replenishing valve 52 is in the open state, and the oil replenishing pump 4 can replenish oil to the second working oil circuit 102 to prevent the small cavity of the actuator 1 from being sucked into the air. At the same time, the second oil replenishing valve 53 is opened under the oil supply pressure of the second working oil circuit 102, and the return oil high pressure of the first working oil circuit 101 can be returned to the oil tank 9 through the oil replenishing overflow valve 8.

[0057] Correspondingly, further development based on the hardware platform of the electrostatic hydraulic actuator system provided in this application can realize the following control method:

[0058] When the first oil port A returns oil and the electrostatic hydraulic actuator system is in the first working condition, the first valve cuts off the return oil flow to the radiator 3;

[0059] When the first oil port A returns oil and the electrostatic hydraulic actuator system is in the second working condition, the oil replenishment pump 4 increases the pressure of the second oil port B so that the return oil of the first oil port A flows to the second oil port B through the first oil path.

[0060] In order to better understand some feasible application modes of the electrostatic hydraulic actuator system of the present application, the following Figure 1 The electrostatic hydraulic actuator system shown is described.

[0061] In some examples, the current operating condition of the electrostatic hydraulic actuator system may be identified as follows:

[0062] Obtain the motion direction and load direction of actuator 1; the specific steps are as follows:

[0063] Get the required flow Q of actuator 1 e (command signal) to confirm the movement direction of the actuator 1; specifically, the actuator 1 can require a flow rate Q e Differentiation is performed to determine the movement direction of the actuator 1 based on the differentiation result. For example, the extension direction of the actuator 1 is taken as the positive direction, and the retraction direction is taken as the negative direction. The required flow rate of the actuator 1 is the required instruction input when the actuator 1 is controlled. For example, the operating amplitude of the mechanical operating part (the rotation angle of the manual knob, the push position of the joystick) of the operator during manual control, the control parameters input in automatic control, etc. The above-mentioned operating amplitude and control parameters are converted into the required flow rate of the actuator, that is, the movement direction of the actuator 1 can be confirmed by the positive or negative of the required flow rate of the actuator 1. In addition, the movement direction of the actuator 1 can also be detected by a displacement sensor.

[0064] Obtain the pressure signals of the oil inlet chamber and the oil return chamber of the actuator 1 to confirm the load direction; specifically, obtain the pressure signal of the large chamber and the pressure signal of the small chamber of the actuator 1, and compare the two pressure signals. For example, the load direction is defined as the extension direction of the actuator 1 as the positive direction, and the retraction direction as the negative direction; in this way, when the difference between the pressure signal of the large chamber and the pressure signal of the small chamber is a negative value, it indicates that the load direction is positive, and when the difference between the pressure signal of the large chamber and the pressure signal of the small chamber is a positive value, it indicates that the load direction is negative;

[0065] When the movement direction and the load direction are the same, it is confirmed that the electrostatic hydraulic actuator system is in the first working condition; when the movement direction and the load direction are opposite, it is confirmed that the electrostatic hydraulic actuator system is in the second working condition.

[0066] like Figure 2 As shown, when judging the load direction, it is necessary to collect the pressure signal of the large cavity and the pressure signal of the small cavity of the actuator 1 through the pressure detection device 12. In order to ensure the accuracy of the judgment result, it is necessary to filter the pressure signal first to remove noise. The specific steps are as follows:

[0067] The pressure P of the large cavity of the actuator 1 is collected by the pressure detection device 12 b and the small chamber pressure P of actuator 1 c , and filter the pressure signal of the pressure detection device 12, the filtering method is as follows:

[0068] The pressure P of the large cavity of the actuator 1 is collected by the pressure detection device 12b and the small chamber pressure P of actuator 1 c , and filter the pressure signal of the pressure detection device 12, the filtering method is as follows:

[0069]

[0070] Where N is the low-pass cutoff frequency, T s is the time constant; f pb (t) is the current large cavity pressure value, f pc (t) is the current small cavity pressure value, so as to obtain the pressure curve after filtering. pb (t), filter pc (t).

[0071] Then, take the filter pb The large cavity pressure filter after filtering in n sampling periods in (t) pb [1,…,n] and filter pc The small cavity pressure filter after filtering in the n sampling periods in (t) pc [1,…,n], and find its average value p bv1 ,p cv1 , the formula is as follows:

[0072]

[0073] The average value p bv1 、p bv2 They are used as the pressure signals of the large chamber and the small chamber of actuator 1 respectively, and the load direction is determined according to the following formula:

[0074] Load direction = p bv1 -p cv1 .

[0075] The load direction can be defined as the extension direction of actuator 1 as positive and the retraction direction as negative; then the average value p bv1 With p bv2 When the difference is negative, it means that the load direction is positive, that is, the same direction as the extension direction of actuator 1. Similarly, in the average value p bv1 With p bv2 When the difference is positive, it means that the load direction is negative, that is, opposite to the extension direction of actuator 1.

[0076] Further, obtain the required flow rate Q of actuator 1 e Some possible implementation plans are as follows:

[0077] If the load direction is positive, the pressure of the large cavity is marked as the main pump outlet pressure p e , the small cavity pressure is the main pump return oil pressure pd (pressure at the suction port of main pump 7);

[0078] If the load direction is negative, the small cavity pressure is marked as the main pump outlet pressure p e , the large cavity pressure is the main pump return oil pressure p d ;

[0079] The power value p is set in the controller w , combined with the current main pump outlet pressure p e , calculate the allowable output flow Q r , the formula is as follows:

[0080]

[0081] The permissible output flow Q r The controller receives the input command flow Q a Compare and take the smaller value of the two and assign it to the demand flow Q e Alternatively, the controller can directly accept the input command flow Q a , according to the input command flow Q a The positive or negative value of determines the movement direction of actuator 1.

[0082] Furthermore, we can combine the demand flow Q e , to control the speed of the main pump motor. The specific control method is as follows:

[0083] Calculate the required speed n of the main pump motor e , the formula is as follows:

[0084]

[0085] Among them, β is the volumetric efficiency of the main pump, V n Main pump displacement;

[0086] The controller obtains the actual speed n of the main pump motor w , as the feedback signal to calculate the motor required speed n e The deviation e(k) is input into the PI control law, and the required speed n e The discrete PI control law is as follows:

[0087] ΔI(k)=K p1 [e(k)-e(k-1)+K i1 e(k),

[0088] e(k)=n e (k)-n w (k)

[0089] Among them, n e(k) is the expected required speed n at the kth step e , n w (k) is the speed feedback value n at the kth step w Thus, the speed of the main pump motor is controlled in a closed loop.

[0090] Through the above method, the movement direction and load direction of the actuator 1 can be obtained, and the speed of the main pump motor can be controlled. Among them, the load direction refers to the direction of the load force.

[0091] The controller determines the current working condition type according to the movement direction and load direction of the actuator 1. When the movement direction and the load direction are opposite, the controller confirms that the current working condition of the actuator 1 is the second working condition (impedance load condition); when the movement direction and the load direction are the same, the controller confirms that the current working condition of the actuator 1 is the first working condition (overrunning load condition); illustratively, a four-quadrant judgment is performed on the actuator 1, specifically: take a row vector with load type, load direction and movement direction as elements, recorded as [load type, load direction, movement direction], then the four-quadrant judgment is [overrunning load, positive, positive], [impedance load, positive, negative], [impedance load, negative, positive] and [overrunning load, negative, negative]. Among them, [overrunning load, positive, positive] means that both the load direction and the movement direction are positive, then the current working condition of actuator 1 is confirmed to be the first working condition (overrunning load condition); [overrunning load, negative, negative] means that both the load direction and the movement direction are negative, then the current working condition of actuator 1 is confirmed to be the first working condition (overrunning load condition); [impedance load, positive, negative] means that the load direction is positive and the movement direction is negative, then the current working condition of actuator 1 is confirmed to be the second working condition (impedance load condition); [impedance load, negative, positive] means that the load direction is negative and the movement direction is positive, then the current working condition of actuator 1 is confirmed to be the second working condition (impedance load condition).

[0092] Based on the judgment of the current working condition of the above-mentioned actuator 1, the controller can control the charge pump 4 to pressurize the suction port (second oil port B) of the main pump 7 (the suction port of the main pump 7 is connected to the return port of the actuator 1, and while the suction port of the main pump 7 is pressurized, the return port of the actuator 1 is also pressurized). Since when the current working condition of the actuator 1 is the second working condition, pressurization is required, and when the current working condition of the actuator 1 is the first working condition, pressurization is not required, therefore, the specific pressurization selection method is as follows:

[0093] [Exceeding load condition, expected boost pressure P n =0]

[0094] [Impedance load condition, expected boost pressure P n =Set boost pressure]

[0095] [Impedance load condition, expected boost pressure Pn =Set boost pressure]

[0096] [Exceeding load condition, expected boost pressure P n =0]

[0097] In this way, the corresponding boost pressure can be built into the controller, and the desired boost pressure can be selected according to the type of current working condition of the actuator 1 .

[0098] like Figure 2 As shown, the controller determines the current working condition type according to the movement direction and load direction of the actuator 1. When it is confirmed that the current working condition of the actuator 1 is the first working condition (overload working condition), the controller controls the oil replenishment pump motor to control the oil replenishment pump 4 to run at a speed lower than the preset speed, so that the oil replenishment pump 4 slows down and gradually approaches to stop (will not stop completely). Preferably, the oil replenishment pump 4 can also be controlled to replenish oil to the oil inlet of the actuator 1. For example, see Figure 1 , the replenishing valve (first replenishing valve 52 or second replenishing valve 53) between the replenishing pump 4 and the oil inlet side opens under the action of the return oil high pressure, thereby realizing the connection between the replenishing pump 4 and the oil inlet. In addition, because in the first working condition, the pressure on the return oil side of the actuator 1 is higher than the pressure on its oil inlet side, the driving direction control valve 11 is reversed, so that the oil circuit between the return oil side (first oil port A) of the actuator 1 and the back pressure valve 10 is cut off, and the high-pressure oil on the return oil side of the actuator 1 cannot flow through the radiator 3, isolating the influence of the high pressure on the radiator 3. The return oil high pressure opens the replenishing oil overflow valve 8 through the replenishing valve on the return oil side, and returns the oil to the oil tank 9 until the zero pressure or negative pressure condition appears on the oil inlet side, and the replenishing valve on the return oil side is closed, forming a high pressure to counteract the load.

[0099] When it is confirmed that the current working condition of the actuator 1 is the second working condition (impedance load condition), it is necessary to control the charge pump 4 to increase the pressure of the second oil port B. Specifically, the target boost pressure and the actual pressure of the second oil port B are obtained, wherein the target boost pressure is the expected boost pressure P n , the actual pressure is the main pump return oil pressure p d , the controller sets the main pump return oil pressure p d As a feedback signal, calculate the desired boost pressure P n The deviation e(x) between them is input into the PI control law, and the desired boost pressure P n The discrete PI control law is as follows:

[0100] ΔI(x)=K p2 [e(x)-e(x-1)+K i2 e(x) ,

[0101] e(x)=P n (x)-p d (x) ,

[0102] Among them, P n (x)—Expected demand pressure P at the kth step n , p d (x)—kth step downforce feedback value p d , K p2 —Proportional gain coefficient, K i2 —Integral gain coefficient. Thus, the target boost pressure and the actual pressure can be combined to realize the pressure closed-loop control of the motor speed of the charge pump, and the control signal of the pump speed of the charge pump 4 can be obtained, so as to control the charge pump 4 to boost the oil suction port of the main pump 7 and the oil return port of the actuator 1.

[0103] When the current working condition of the actuator 1 is the second working condition (impedance load working condition), the present application realizes the pressure control of the return oil circuit (the first oil circuit in the return oil state) by controlling the speed of the oil replenishment motor pump, so that the oil pressure at the return oil port is maintained at a set value, and the set value is higher than the opening pressure of the back pressure valve 10 behind the directional control valve 11. Since the hydraulic oil preferentially flows to the direction of low pressure, when the heat dissipation oil circuit is connected in parallel with the main pump suction oil circuit, the return oil liquid preferentially flows into the directional control valve 11, and then outputs to the suction port (second oil port B) of the main pump 7 through the oil replenishment pump 4. In this process, the radiator 3 arranged behind the directional control valve 11 can cool the entire return oil flow without being affected by the system, strengthen the heat dissipation effect, meet the heat dissipation requirements of the electro-hydraulic actuator under high-frequency and high-load working conditions, and does not require additional media, is easy to maintain, and has low layout costs. At the same time, the main pump 7 can be pressurized to optimize the main pump 7 suction working condition, so that the main pump 7 can further increase its speed limit and improve the working capacity of the electro-hydraulic actuator. When the current working condition of the actuator 1 is the second working condition (overload working condition), since the pressure on the return oil side of the actuator 1 is higher than the pressure on its inlet oil side, the driving direction control valve 11 is reversed, and the oil circuit between the return oil side of the actuator 1 and the back pressure valve 10 is cut off, effectively isolating the high-pressure oil in the return oil chamber of the actuator 1, so that the radiator 3 is not affected by the return oil high pressure.

[0104] In addition, the symbols and their meanings used in this application are specifically shown in the following table:

[0105]

[0106]

[0107] The second exemplary embodiment of the present application provides a working machine, which is provided with an electrostatic hydraulic actuator system of any one of the above-mentioned embodiments. It should be noted that the above-mentioned working machines include engineering machinery, agricultural machinery, working robots, etc., and the driving modes of the above-mentioned working machines are also diverse, for example, it can be a fuel-driven working machine, or it can be a new energy-driven working machine, and the new energy drive includes pure electric, extended-range electric, hybrid drive, fuel cell and hydrogen drive, etc.

[0108] The third exemplary embodiment of the present application also provides a new energy vehicle, including a power battery and an electrostatic hydraulic actuator system, the electrostatic hydraulic actuator system is the electrostatic hydraulic actuator system of any one of the above embodiments, and the power battery is used to power the main pump 7 of the electrostatic hydraulic actuator system. In some specific embodiments, the new energy vehicle may include a pump truck, a truck crane, a truck-mounted crane and conveyor, a mixer truck, a road construction vehicle, a sanitation vehicle, etc.

[0109] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0110] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0111] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. An electrostatic hydraulic actuator system, characterized in that: The invention comprises a first oil port, a second oil port, a first oil circuit and a second oil circuit, wherein the first oil circuit and the second oil circuit are arranged in parallel and are used to connect the first oil port and the second oil port, and in the direction from the first oil port to the second oil port, the first oil circuit is provided with a first valve, a radiator (3) and an oil replenishment pump (4) in sequence; When the first oil port returns oil and the electrostatic hydraulic actuator system is in a first working condition, the first valve is configured to cut off the return oil from flowing to the radiator (3); when the first oil port returns oil and the electrostatic hydraulic actuator system is in a second working condition, the replenishing oil pump (4) is configured to pressurize the second oil port so that the return oil from the first oil port flows to the second oil port through the first oil path; The oil return pressure of the first oil port under the first working condition is greater than the oil return pressure of the first oil port under the second working condition.

2. The electrostatic hydraulic actuator system according to claim 1, characterized in that: It also includes a back pressure valve (10), which is arranged on the first oil circuit and located between the first valve and the radiator (3).

3. The electrostatic hydraulic actuator system according to claim 1, characterized in that: The first valve is a directional control valve (11), the directional control valve (11) comprising a first hydraulic control end and a second hydraulic control end, the first hydraulic control end being connected to the first oil port, the second hydraulic control end being connected to the third oil port, when one of the first oil port and the third oil port is in an oil return state, the other is in an oil intake state, the directional control valve (11) being configured as follows: When the oil pressure at the first hydraulic control end is greater than the oil pressure at the second hydraulic control end, disconnecting the first oil port from the radiator (3); When the oil pressure at the first hydraulic control end is lower than the oil pressure at the second hydraulic control end, the first oil port is connected to the radiator (3).

4. The electrostatic hydraulic actuator system according to claim 1, characterized in that: The invention also comprises an actuator (1), a main pump (7), a third oil port, a fourth oil port and a third oil circuit for connecting the third oil port and the fourth oil port, wherein the first oil port and the third oil port are respectively connected to two ends of the actuator, and the second oil port and the fourth oil port are respectively connected to two ends of the main pump (7).

5. The electrostatic hydraulic actuator system according to claim 4, characterized in that: The invention also includes an oil replenishing circuit (51), wherein the oil replenishing circuit (51) is connected between the second oil port and the fourth oil port, and a first oil replenishing valve (52) and a second oil replenishing valve (53) are provided on the oil replenishing circuit (51), and the first oil circuit is connected to the oil replenishing circuit (51) and is connected between a pair of the first oil replenishing valve (52) and the second oil replenishing valve (53).

6. The electrostatic hydraulic actuator system according to claim 5, characterized in that: It also comprises an oil replenishment overflow valve (8), the oil replenishment overflow valve (8) being arranged in parallel with the oil replenishment pump (4), and the oil replenishment oil circuit (51) being connected to the oil tank (9) via the oil replenishment overflow valve (8).

7. The electrostatic hydraulic actuator system according to claim 5, characterized in that: The first oil replenishing valve (52) and the second oil replenishing valve (53) are hydraulically controlled one-way valves. The hydraulic control chamber of the first oil replenishing valve (52) is communicated with the fourth oil port, and the hydraulic control chamber of the second oil replenishing valve (53) is communicated with the second oil port.

8. The electrostatic hydraulic actuator system according to any one of claims 4 to 7, characterized in that: The first oil port and the third oil port are used to connect the oil circuits of the actuator (1) and are respectively provided with load holding valves (2).

9. The electrostatic hydraulic actuator system according to any one of claims 4 to 7, characterized in that: The first oil port and the third oil port are used to connect the oil circuits of the actuator (1) and are respectively provided with pressure detection devices (12).

10. A working machine, characterized in that: An electrostatic hydraulic actuator system according to any one of claims 1 to 9 is provided.

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