Control method, controller and actuator system for electro-hydraulic actuator systems

Abstract

The present application relates to the technical field of electro-hydraulic control, and discloses a control method, a controller and an actuator system for an electro-hydraulic actuator system. The electro-hydraulic actuator system comprises a hydraulic cylinder including a rod cavity and a rodless cavity, a bidirectional hydraulic pump, an accumulator, and a plurality of electric proportional seat valves including a first electric proportional seat valve, a second electric proportional seat valve, a third electric proportional seat valve and a fourth electric proportional seat valve. The method comprises: acquiring a pump rotating speed and a pump rotating direction of the bidirectional hydraulic pump, a first pressure value of the rod cavity and a second pressure value of the rodless cavity; determining a working condition of the hydraulic cylinder according to the pump rotating speed, the pump rotating direction, the first pressure value and the second pressure value; and controlling at least one of the first electric proportional seat valve, the second electric proportional seat valve, the third electric proportional seat valve and the fourth electric proportional seat valve according to the working condition. The working condition is identified in real time, the optimal control mode is selected according to different working conditions, the accuracy and stability of control are ensured, and economic cost is saved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electro-hydraulic control, in particular to a control method for an electro-hydraulic actuator system, a controller and an actuator system. BACKGROUND

[0002] The electro-hydraulic actuator is a kind of actuator that highly integrates motor, pump, hydraulic valve, oil tank and hydraulic cylinder, and controls the hydraulic cylinder through motor pump volume speed regulation. Compared with the traditional centralized valve control system, the electro-hydraulic actuator has less throttling and overflow loss, adopts power electric transmission instead of hydraulic pipeline, has the advantages of high energy efficiency, modularity, easy maintenance, etc., and has the advantages of higher power-to-weight ratio compared with the same specification electric cylinder.

[0003] At present, the research of electro-hydraulic actuator mainly focuses on the fields of aviation and industry. Taking the industrial field as an example, the industrial field generally requires large actuator output force, high position and speed control accuracy, and mainly uses servo / frequency conversion motor and fixed / variable pump to control asymmetric hydraulic cylinder. Because the volumes of the rod cavity and the rodless cavity are different during the movement of the asymmetric hydraulic cylinder, an asymmetric pump, a high-speed on-off valve and other ways are mainly used to balance the flow of the two cavities. The asymmetric pump is difficult to manufacture, and the high-speed on-off valve group is expensive, resulting in high cost. SUMMARY

[0004] In order to overcome the deficiencies of the prior art, the embodiments of the present application provide a control method for an electro-hydraulic actuator system, a controller and an actuator system.

[0005] In order to achieve the above-mentioned purpose, the first aspect of the present application provides a control method for an electro-hydraulic actuator system, the electro-hydraulic actuator system comprising:

[0006] a hydraulic cylinder comprising a rod cavity and a rodless cavity;

[0007] a bidirectional hydraulic pump;

[0008] an accumulator;

[0009] a plurality of electric proportional seat valves, the plurality of electric proportional seat valves comprising a first electric proportional seat valve, a second electric proportional seat valve, a third electric proportional seat valve and a fourth electric proportional seat valve;

[0010] a first end of the bidirectional hydraulic pump is connected to a second end of the first electric proportional seat valve and a first end of the second electric proportional seat valve, a second end of the bidirectional hydraulic pump is connected to a first end of the third electric proportional seat valve and a second end of the fourth electric proportional seat valve, a first end of the first electric proportional seat valve and a first end of the fourth electric proportional seat valve are both connected to the accumulator, a second end of the second electric proportional seat valve is connected to the rod cavity, and a second end of the third electric proportional seat valve is connected to the rodless cavity;

[0011] The method comprises:

[0012] acquiring a pump rotating speed and a pump rotating direction of a bidirectional hydraulic pump, a first pressure value of a rod cavity and a second pressure value of a rodless cavity;

[0013] determining a working condition of a hydraulic cylinder according to the pump rotating speed, the pump rotating direction, the first pressure value and the second pressure value;

[0014] controlling at least one of a first electric proportional seat valve, a second electric proportional seat valve, a third electric proportional seat valve and a fourth electric proportional seat valve according to the working condition.

[0015] In the embodiment of the present application, the working condition of the hydraulic cylinder is determined according to the pump rotating speed, the pump rotating direction, the first pressure value and the second pressure value, including at least one of the following:

[0016] In the case that the pump rotating direction indicates that the bidirectional hydraulic pump sucks oil from the rod cavity and discharges oil to the rodless cavity, the working condition of the hydraulic cylinder is determined as an extension working condition, and in the case that the pump rotating direction indicates that the bidirectional hydraulic pump sucks oil from the rodless cavity and discharges oil to the rod cavity, the working condition is determined as a retraction working condition.

[0017] In the case that the flow direction indicated by the pump rotating direction is opposite to a load direction, the working condition of the hydraulic cylinder is determined as a resistance working condition, and in the case that the flow direction indicated by the pump rotating direction is the same as the load direction, the working condition is determined as an overrun working condition, and the load direction is determined according to the first pressure value, the second pressure value, an acting area of the rodless cavity and an acting area of the rod cavity.

[0018] In the case that the pump rotating speed is greater than or equal to a rotating speed threshold value, the working condition of the hydraulic cylinder is determined as a constant speed working condition, and in the case that the pump rotating speed is less than the rotating speed threshold value, the working condition is determined as a low speed working condition.

[0019] In the embodiment of the present application, the at least one of the first electric proportional seat valve, the second electric proportional seat valve, the third electric proportional seat valve and the fourth electric proportional seat valve is controlled according to the working condition, including:

[0020] In the case that the working condition is simultaneously determined as the low speed working condition, the resistance working condition and the extension working condition, the first electric proportional seat valve is controlled to be closed, the second electric proportional seat valve is controlled to be fully opened, and the third electric proportional seat valve is controlled to be closed.

[0021] The opening degree of the fourth electric proportional seat valve is controlled according to an outlet flow of the bidirectional hydraulic pump and a required flow of the hydraulic cylinder.

[0022] In the embodiment of the present application, the at least one of the first electric proportional seat valve, the second electric proportional seat valve, the third electric proportional seat valve and the fourth electric proportional seat valve is controlled according to the working condition, including:

[0023] In the case that the working condition is simultaneously determined as the low speed working condition, the overrun working condition and the extension working condition, the first electric proportional seat valve is controlled to be closed, and the third electric proportional seat valve is controlled to be closed.

[0024] adjusting the opening of the second electric proportional seat valve according to the front and back pressures of the second electric proportional seat valve;

[0025] controlling the opening of the fourth electric proportional seat valve according to the outlet flow of the bidirectional hydraulic pump and the required flow of the hydraulic cylinder.

[0026] In the embodiment of the present application, the method further comprises:

[0027] In the case where the working condition is determined as the constant speed working condition, the impedance working condition and the extension working condition at the same time, the first electric proportional seat valve is controlled to be closed, the second electric proportional seat valve is controlled to be fully opened, the third electric proportional seat valve is controlled to be closed, and the fourth electric proportional seat valve is controlled to be closed.

[0028] In the embodiment of the present application, the method further comprises:

[0029] In the case where the working condition is determined as the constant speed working condition, the overrunning working condition and the extension working condition at the same time, the first electric proportional seat valve is controlled to be closed, the third electric proportional seat valve is controlled to be closed, and the fourth electric proportional seat valve is controlled to be closed.

[0030] adjusting the opening of the second electric proportional seat valve according to the front and back pressures of the second electric proportional seat valve;

[0031] In the embodiment of the present application, the method further comprises:

[0032] In the case where the running instruction of the bidirectional hydraulic pump is not received or the electro-hydraulic actuator system is stopped, the second electric proportional seat valve is controlled to be closed and the third electric proportional seat valve is controlled to be closed.

[0033] In the embodiment of the present application, the method further comprises:

[0034] obtaining a third pressure value of a first oil port of the bidirectional hydraulic pump, a fourth pressure value of a second oil port of the bidirectional hydraulic pump, and a fifth pressure value of the accumulator;

[0035] In the case where at least one of the first pressure value, the second pressure value, the third pressure value, the fourth pressure value and the fifth pressure value is greater than a pressure threshold value, the second electric proportional seat valve is controlled to be powered off, the third electric proportional seat valve is controlled to be powered off, the motor corresponding to the bidirectional hydraulic pump is controlled to be stopped, the first electric proportional seat valve is controlled to be opened, and the fourth electric proportional seat valve is controlled to be opened.

[0036] In the embodiment of the present application, the electro-hydraulic actuator system further comprises:

[0037] The displacement sensor is connected with the piston of the hydraulic cylinder.

[0038] The method further comprises:

[0039] receiving a target speed of the piston;

[0040] obtaining an actual speed of the piston according to displacement information detected by the displacement sensor;

[0041] adjusting the speed of the piston according to a first deviation between the target speed and the actual speed in a case where the first deviation is greater than a first preset deviation;

[0042] receiving a target position of the piston;

[0043] obtaining an actual position of the piston according to displacement information detected by the displacement sensor;

[0044] adjusting the position of the piston according to a second deviation between the target position and the actual position in a case where the second deviation is greater than a second preset deviation.

[0045] The second aspect of the present application provides a controller configured to perform the above-mentioned control method for an electro-hydraulic actuator system.

[0046] The third aspect of the present application provides an electro-hydraulic actuator system, comprising:

[0047] a hydraulic cylinder comprising a rod cavity and a rodless cavity;

[0048] a bidirectional hydraulic pump;

[0049] an accumulator;

[0050] a plurality of electric proportional seat valves comprising a first electric proportional seat valve, a second electric proportional seat valve, a third electric proportional seat valve, and a fourth electric proportional seat valve;

[0051] a first end of the bidirectional hydraulic pump is connected to a second end of the first electric proportional seat valve and a first end of the second electric proportional seat valve, a second end of the bidirectional hydraulic pump is connected to a first end of the third electric proportional seat valve and a second end of the fourth electric proportional seat valve, a first end of the first electric proportional seat valve and a first end of the fourth electric proportional seat valve are both connected to the accumulator, a second end of the second electric proportional seat valve is connected to the rod cavity, and a second end of the third electric proportional seat valve is connected to the rodless cavity; and

[0052] the above-mentioned controller.

[0053] The fourth aspect of the present application provides a working machine comprising the above-mentioned electro-hydraulic actuator system.

[0054] Exemplarily, the first end of the first electric proportional seat valve is connected to the accumulator, the second end of the first electric proportional seat valve is connected to the first end of the bidirectional hydraulic pump, and the oil in the accumulator can be supplemented to the oil suction port of the bidirectional hydraulic pump through the first electric proportional seat valve. The first end of the fourth electric proportional seat valve is connected to the accumulator, the second end of the fourth electric proportional seat valve is connected to the second end of the bidirectional hydraulic pump, and a part of the flow can be divided to the accumulator through the fourth electric proportional seat valve, and the oil in the accumulator can be supplemented to the rodless cavity of the hydraulic cylinder through the fourth electric proportional seat valve. The states of the first electric proportional seat valve, the second electric proportional seat valve, the third electric proportional seat valve and the fourth electric proportional seat valve are controlled according to the working conditions of the hydraulic cylinder, that is, the working conditions can be identified in real time, and then the optimal control mode is selected according to different working conditions, so as to guarantee the accuracy and stability of control. The structure of the electro-hydraulic actuator system and the control method thereof provided in the embodiment of the present application are more suitable for the field of engineering machinery with complex and variable working conditions.

[0055] In the case that no operation instruction of the bidirectional hydraulic pump is received or the electro-hydraulic actuator system is shut down, the second electric proportional seat valve and the third electric proportional seat valve can be controlled to be closed, so that the hydraulic cylinder can be reliably stopped under the action of the second electric proportional seat valve and the third electric proportional seat valve and can be kept at the current position, and the oil cannot flow out of the hydraulic cylinder, thereby reducing the energy consumption of the system.

[0056] Particularly, when the hydraulic cylinder is in the working condition of high-frequency reciprocating action, since the electric control response is higher than the hydraulic control response, the rod cavity flow and the rodless cavity flow of the hydraulic cylinder can be balanced, the pressure impact of the electro-hydraulic actuator system can be reduced, and the frequency response of the system can be improved through the setting and control of the plurality of electric proportional seat valves. In the embodiment of the present application, the two-cavity flow of the hydraulic cylinder is balanced by using the symmetric pump and the plurality of electric proportional seat valves. The symmetric pump has a smaller manufacturing difficulty, and the electric proportional seat valve has a lower price, so that the economic cost is saved without affecting the function implementation of the electro-hydraulic actuator system. BRIEF DESCRIPTION OF DRAWINGS

[0057] The accompanying drawings are included to provide a further understanding of the embodiments of the present application, and constitute a part of the specification, and are used together with the following specific embodiments to explain the embodiments of the present application, but do not constitute a limitation on the embodiments of the present application. In the drawings:

[0058] Figure 1 A structural diagram for an electro-hydraulic actuator system according to an embodiment of the present application is schematically shown;

[0059] Figure 2 A flow chart of a control method for an electro-hydraulic actuator system according to an embodiment of the present application is schematically shown;

[0060] Figure 3 A control scheme diagram of a low-speed impedance extension working condition according to an embodiment of the present application is schematically shown;

[0061] Figure 4 Fig. 4 shows a control scheme diagram of the low-speed over-reach working condition according to an embodiment of the present application;

[0062] Figure 5 Fig. 5 shows a control scheme diagram of the normal-speed resistance-reach working condition according to an embodiment of the present application;

[0063] Figure 6 Fig. 6 shows a control scheme diagram of the normal-speed over-reach working condition according to an embodiment of the present application;

[0064] Figure 7 Fig. 7 shows a control scheme diagram of the low-speed resistance-retract working condition according to an embodiment of the present application;

[0065] Figure 8 Fig. 8 shows a control scheme diagram of the normal-speed resistance-retract working condition according to an embodiment of the present application;

[0066] Figure 9 Fig. 9 shows a control scheme diagram of the low-speed over-retract working condition according to an embodiment of the present application;

[0067] Figure 10 Fig. 10 shows a control scheme diagram of the normal-speed over-retract working condition according to an embodiment of the present application;

[0068] Figure 11 Fig. 11 shows a control scheme diagram of each hydraulic cylinder working condition according to an embodiment of the present application.

[0069] BRIEF DESCRIPTION OF DRAWINGS

[0070] 1 - motor; 2 - motor driver;

[0071] 3 - controller; 4.1 - first hydraulic control check valve;

[0072] 4.2 - second hydraulic control check valve; 5 - accumulator;

[0073] 6.1 - first electric proportional seat valve; 6.2 - second electric proportional seat valve;

[0074] 6.3 - third electric proportional seat valve; 6.4 - fourth electric proportional seat valve;

[0075] 7.1 - first safety valve; 7.2 - second safety valve;

[0076] 8.1 - first pressure sensor; 8.2 - second pressure sensor;

[0077] 8.3 - third pressure sensor; 8.4 - fourth pressure sensor;

[0078] 8.5 - fifth pressure sensor; 9 - displacement sensor;

[0079] 10 - hydraulic cylinder; 11 - bidirectional hydraulic pump. DETAILED DESCRIPTION

[0080] The specific implementation of the embodiments of the present application will be described in detail below with reference to the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the embodiments of the present application, and is not used to limit the embodiments of the present application.

[0081] It should be noted that if the present application embodiments involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative positional relationship, motion condition, etc. between the components in a certain posture (as shown in the drawings), if the specific posture changes, the directional indications will also change accordingly.

[0082] In addition, if the present application embodiments involve descriptions such as "first", "second", etc., the descriptions of "first", "second", etc. are only for description purposes, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first", "second" can explicitly or implicitly include at least one of the features. In addition, the technical solutions of each embodiment can be combined with each other, but it must be based on the realization of ordinary skilled in the art, when the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, nor within the scope of protection claimed by the present application.

[0083] Figure 1 The structural diagram for the electro-hydraulic actuator system according to the embodiments of the present application is schematically shown, which can be seen from Figure 1 The electro-hydraulic actuator system comprises:

[0084] The hydraulic cylinder 10 comprises a rod cavity and a rodless cavity;

[0085] The bidirectional hydraulic pump 11;

[0086] The accumulator 5;

[0087] The plurality of electric proportional seat valves comprises a first electric proportional seat valve 6.1, a second electric proportional seat valve 6.2, a third electric proportional seat valve 6.3, and a fourth electric proportional seat valve 6.4;

[0088] The first end of the bidirectional hydraulic pump 11 is connected with the second end of the first electric proportional seat valve 6.1 and the first end of the second electric proportional seat valve 6.2, the second end of the bidirectional hydraulic pump 11 is connected with the first end of the third electric proportional seat valve 6.3 and the second end of the fourth electric proportional seat valve 6.4, the first end of the first electric proportional seat valve 6.1 and the first end of the fourth electric proportional seat valve 6.4 are both connected with the accumulator 5, and the second end of the second electric proportional seat valve 6.2 is connected with the rod cavity, and the second end of the third electric proportional seat valve 6.3 is connected with the rodless cavity. Figure 1 Other components in the structural diagram will be described later and are not essential components.

[0089] Figure 2 A flow chart of a control method for an electro-hydraulic actuator system according to an embodiment of the present application is schematically shown. Figure 2 As shown, in an embodiment of the present application, a control method for an electro-hydraulic actuator system is provided, comprising the following steps:

[0090] In step 201, the pump rotating speed and rotating direction of the bidirectional hydraulic pump 11, the first pressure value of the rod cavity and the second pressure value of the rodless cavity are obtained.

[0091] In step 202, the working condition of the hydraulic cylinder 10 is determined according to the pump rotating speed and rotating direction, the first pressure value and the second pressure value.

[0092] In step 203, at least one of the first electric proportional seat valve 6.1, the second electric proportional seat valve 6.2, the third electric proportional seat valve 6.3 and the fourth electric proportional seat valve 6.4 is controlled according to the working condition.

[0093] For example, the first end of the first electric proportional seat valve 6.1 is connected with the accumulator 5, the second end of the first electric proportional seat valve 6.1 is connected with the first end of the bidirectional hydraulic pump 11, and the oil in the accumulator 5 can be supplemented to the oil suction port of the bidirectional hydraulic pump 11 through the first electric proportional seat valve 6.1. The first end of the fourth electric proportional seat valve 6.4 is connected with the accumulator 5, the second end of the fourth electric proportional seat valve 6.4 is connected with the second end of the bidirectional hydraulic pump 11, and a part of the flow can be divided to the accumulator 5 through the fourth electric proportional seat valve 6.4, and the oil in the accumulator 5 can be supplemented to the rodless cavity of the hydraulic cylinder 10 through the fourth electric proportional seat valve 6.4. The states of the first electric proportional seat valve 6.1, the second electric proportional seat valve 6.2, the third electric proportional seat valve 6.3 and the fourth electric proportional seat valve 6.4 are controlled according to the working condition of the hydraulic cylinder 10, that is, the working condition can be identified in real time, and then the optimal control mode is selected according to different working conditions, so as to guarantee the control precision and stability. The structure of the electro-hydraulic actuator system and the control method thereof provided in the embodiment of the present application can be applied to the engineering machinery field with complex and variable working conditions.

[0094] The pump rotation speed and the pump rotation direction of the bidirectional hydraulic pump 11 can be obtained from the operation instruction or acquired through a sensor. In the case where no operation instruction of the bidirectional hydraulic pump 11 is received or the electro-hydraulic actuator system is shut down, the second electric proportional seat valve 6.2 is controlled to be closed and the third electric proportional seat valve 6.3 is controlled to be closed, so that the hydraulic cylinder 10 can be reliably stopped under the action of the second electric proportional seat valve 6.2 and the third electric proportional seat valve 6.3 and kept at the current position, and the oil cannot flow out of the hydraulic cylinder 10, thereby reducing the energy consumption of the system.

[0095] In particular, when the hydraulic cylinder 10 is in the working condition of high-frequency reciprocating motion, due to the fact that the electric control response is higher than the hydraulic control response, the rod cavity flow and the rodless cavity flow of the hydraulic cylinder 10 can be balanced through the setting and control of the plurality of electric proportional seat valves, the pressure impact of the electro-hydraulic actuator system is reduced, and the frequency response of the system is improved. In the embodiment of the present application, the two-cavity flow of the hydraulic cylinder 10 is balanced by using a symmetrical pump and a plurality of electric proportional seat valves. The symmetrical pump is less difficult to manufacture, and the electric proportional seat valve is less expensive. The economic cost is saved while the function of the electro-hydraulic actuator system is not affected.

[0096] In an embodiment, the working condition of the hydraulic cylinder 10 is determined according to the pump rotation speed and the pump rotation direction, the first pressure value and the second pressure value, and at least one of the following conditions is included:

[0097] In the case where the pump rotation direction indicates that the bidirectional hydraulic pump 11 sucks oil from the rod cavity and discharges oil to the rodless cavity, the working condition of the hydraulic cylinder 10 is determined to be the extension condition, and in the case where the pump rotation direction indicates that the bidirectional hydraulic pump 11 sucks oil from the rodless cavity and discharges oil to the rod cavity, the working condition is determined to be the retraction condition;

[0098] In the case where the flow direction indicated by the pump rotation direction is opposite to the load direction, the working condition of the hydraulic cylinder 10 is determined to be the impedance condition, and in the case where the flow direction indicated by the pump rotation direction is the same as the load direction, the working condition is determined to be the overrun condition, and the load direction is determined according to the first pressure value, the second pressure value, the acting area of the rodless cavity and the acting area of the rod cavity;

[0099] In the case where the pump rotation speed is greater than or equal to the rotation speed threshold value, the working condition of the hydraulic cylinder 10 is determined to be the constant speed condition, and in the case where the pump rotation speed is less than the rotation speed threshold value, the working condition is determined to be the low speed condition.

[0100] The extension working condition and the retraction working condition are introduced. The pump rotating speed and the pump rotating direction of the bidirectional hydraulic pump 11 can be obtained from the operation instruction or can be obtained through sensor acquisition. Taking the pump rotating speed and the pump rotating direction of the bidirectional hydraulic pump 11 obtained from the operation instruction (which can also be called a control instruction) as an example, the controller converts the handle or the signal of the upper computer into the control instruction i, and the value range of i is -Nmax≤i≤Nmax, and Nmax is the rated rotating speed of the motor 1. The sign of the control instruction i is determined. Exemplarily, if the sign is positive, the motor 1 drives the bidirectional hydraulic pump 11 to rotate in the positive direction, the bidirectional hydraulic pump 11 sucks oil from the rod cavity one end of the hydraulic cylinder 10 and discharges oil to the rodless cavity one end of the hydraulic cylinder 10, and at this time, the hydraulic cylinder 10 is in the extension working condition, that is, the piston in the hydraulic cylinder 10 is understood to be extended. If the control instruction i is negative, the motor 1 drives the bidirectional hydraulic pump 11 to rotate in the reverse direction, the bidirectional hydraulic pump 11 sucks oil from the rodless cavity one end of the hydraulic cylinder 10 and discharges oil to the rod cavity one end of the hydraulic cylinder 10, and the hydraulic cylinder 10 is in the retraction working condition, that is, the piston in the hydraulic cylinder 10 is understood to be retracted.

[0101] The impedance working condition and the overrun working condition are introduced. The first pressure value of the rod cavity of the hydraulic cylinder 10 is denoted as P A , the second pressure value of the rodless cavity of the hydraulic cylinder 10 is denoted as P B , the acting area of the rod cavity of the hydraulic cylinder 10 is denoted as A A , and the acting area of the rodless cavity of the hydraulic cylinder 10 is denoted as A B . The flow direction indicated by the pump rotating direction is determined by the rotating direction of the bidirectional hydraulic pump 11 driven by the motor 1. Exemplarily, in the extension working condition, the motor 1 drives the bidirectional hydraulic pump 11 to rotate in the positive direction, the bidirectional hydraulic pump 11 sucks oil from the rod cavity one end of the hydraulic cylinder 10 and discharges oil to the rodless cavity one end of the hydraulic cylinder 10, and at this time, if P B ×A B >P A ×A A , the load direction is opposite to the flow direction, and the impedance working condition is determined; otherwise, the overrun working condition is determined. In the retraction working condition, the motor 1 drives the bidirectional hydraulic pump 11 to rotate in the reverse direction, the bidirectional hydraulic pump 11 sucks oil from the rodless cavity one end of the hydraulic cylinder 10 and discharges oil to the rod cavity one end of the hydraulic cylinder 10, and at this time, if P B ×A B <P A ×A A , the load direction is opposite to the flow direction, and the impedance working condition is determined; otherwise, the overrun working condition is determined.

[0102] The constant speed condition and the low speed condition are introduced. The speed threshold can be the minimum speed Nmin of the bidirectional hydraulic pump 11. If the pump speed in the control instruction i is less than the minimum speed Nmin of the bidirectional hydraulic pump 11, the low speed condition is determined, otherwise the constant speed condition is determined. In order to ensure the working efficiency and service life of the bidirectional hydraulic pump 11, there is usually a minimum speed requirement for the bidirectional hydraulic pump 11. Of course, the speed threshold can also be set to other values as needed.

[0103] If the low speed condition, the impedance condition and the extension condition are determined at the same time, it can be called the low speed impedance extension condition. If the constant speed condition, the impedance condition and the extension condition are determined at the same time, it can be called the constant speed impedance extension condition. If the low speed condition, the overrun condition and the extension condition are determined at the same time, it can be called the low speed overrun extension condition. If the constant speed condition, the overrun condition and the extension condition are determined at the same time, it can be called the constant speed overrun extension condition.

[0104] If the low speed condition, the impedance condition and the retraction condition are determined at the same time, it can be called the low speed impedance retraction condition. If the constant speed condition, the impedance condition and the retraction condition are determined at the same time, it can be called the constant speed impedance retraction condition. If the low speed condition, the overrun condition and the retraction condition are determined at the same time, it can be called the low speed overrun retraction condition. If the constant speed condition, the overrun condition and the retraction condition are determined at the same time, it can be called the constant speed overrun retraction condition.

[0105] In an embodiment, the working conditions of the hydraulic cylinder 10 can be divided into the following eight kinds: low speed impedance extension condition, constant speed impedance extension condition, low speed overrun extension condition, constant speed overrun extension condition, low speed impedance retraction condition, constant speed impedance retraction condition, low speed overrun retraction condition and constant speed overrun retraction condition. According to the identification result of the working condition, control instructions are sent to the plurality of electric proportional seat valves (i.e. the first electric proportional seat valve 6.1, the second electric proportional seat valve 6.2, the third electric proportional seat valve 6.3 and the fourth electric proportional seat valve 6.4). That is, the working condition identification can be carried out in real time, and then the optimal control mode is selected according to different working conditions, so as to guarantee the accuracy and stability of control.

[0106] Figure 3 The control scheme diagram of the low speed impedance extension condition according to the embodiment of the application is schematically shown, which can be seen from Figure 3 In an embodiment, according to the working condition, at least one of the first electric proportional seat valve 6.1, the second electric proportional seat valve 6.2, the third electric proportional seat valve 6.3 and the fourth electric proportional seat valve 6.4 is controlled, including: in the case that the working condition is determined as the low speed condition, the impedance condition and the extension condition at the same time, the first electric proportional seat valve 6.1 is controlled to be closed, the second electric proportional seat valve 6.2 is controlled to be fully opened, and the third electric proportional seat valve 6.3 is controlled to be closed; and the opening degree of the fourth electric proportional seat valve 6.4 is controlled according to the outlet flow of the bidirectional hydraulic pump 11 and the required flow of the hydraulic cylinder 10.

[0107] In the low-speed resistance extension working condition, the fourth electric proportional seat valve 6.4 divides a part of flow to the accumulator 5 according to the control instruction i, and the divided flow is denoted as q = q P -q CYL , wherein q P is the outlet flow of the hydraulic pump 11, and q CYL is the required flow of the hydraulic cylinder 10, so that the speed of the hydraulic cylinder 10 is in proportional relationship with the control instruction i.

[0108] Figure 4 The control scheme diagram of the low-speed override extension working condition according to the embodiment of the present application is schematically shown, which can be seen from Figure 4 In an embodiment, according to the working condition, the control of at least one of the first electric proportional seat valve 6.1, the second electric proportional seat valve 6.2, the third electric proportional seat valve 6.3 and the fourth electric proportional seat valve 6.4 comprises: in the case that the working condition is simultaneously determined as the low-speed working condition, the override working condition and the extension working condition, the first electric proportional seat valve 6.1 is controlled to be closed, and the third electric proportional seat valve 6.3 is controlled to be closed; the opening degree of the second electric proportional seat valve 6.2 is adjusted according to the front and back pressures of the second electric proportional seat valve 6.2; and the opening degree of the fourth electric proportional seat valve 6.4 is controlled according to the outlet flow of the bidirectional hydraulic pump 11 and the required flow of the hydraulic cylinder 10.

[0109] Figure 5 The control scheme diagram of the constant-speed resistance extension working condition according to the embodiment of the present application is schematically shown, which can be seen from Figure 5 In an embodiment, according to the working condition, the control of at least one of the first electric proportional seat valve 6.1, the second electric proportional seat valve 6.2, the third electric proportional seat valve 6.3 and the fourth electric proportional seat valve 6.4 comprises: in the case that the working condition is simultaneously determined as the constant-speed working condition, the resistance working condition and the extension working condition, the first electric proportional seat valve 6.1 is controlled to be closed, the second electric proportional seat valve 6.2 is controlled to be fully opened, the third electric proportional seat valve 6.3 is controlled to be closed, and the fourth electric proportional seat valve 6.4 is controlled to be closed.

[0110] The electro-hydraulic actuator system further comprises a first hydraulic control check valve 4.1 and a second hydraulic control check valve 4.2, which can be seen from Figure 1 The first end of the first hydraulic control check valve 4.1 and the first end of the second hydraulic control check valve 4.2 are connected, the second end of the first hydraulic control check valve 4.1 is connected with the rod cavity oil circuit, the second hydraulic control check valve 4.2 is connected with the rodless cavity oil circuit, the control end of the first hydraulic control check valve 4.1 is connected with the rodless cavity oil circuit, and the control end of the second hydraulic control check valve 4.2 is connected with the rod cavity oil circuit. The first end of the first hydraulic control check valve 4.1 and the first end of the second hydraulic control check valve 4.2 are connected with the accumulator 5. The motor 1 is connected with the bidirectional hydraulic pump 11, the motor 1 drives the bidirectional hydraulic pump 11 to suck and discharge oil, and one end of the bidirectional hydraulic pump 11 is the oil suction port, and the other end is the oil discharge port.

[0111] In the above normal speed overrunning extension working condition, the inlet flow control of the hydraulic cylinder 10 is performed, the second electric proportional seat valve 6.2 is fully opened, and the remaining electric proportional seat valves are all closed. At this time, the rodless cavity oil way is high pressure, and the rod cavity oil way is low pressure. The first hydraulic control check valve 4.1 is automatically opened under the action of pressure (without the need for controller control). The oil supply flow of the rodless cavity is greater than the oil discharge flow of the rod cavity. The oil of the accumulator 5 is supplemented to the suction port of the bidirectional hydraulic pump 11 through the first hydraulic control check valve 4.1 and the first electric proportional seat valve 6.1. The speed of the hydraulic cylinder 10 is in proportional relationship with the control command i.

[0112] Figure 6 The control scheme diagram of the normal speed overrunning extension working condition according to the embodiment of the present application is schematically shown. Referring to FIG. 4, the control scheme diagram of the normal speed overrunning extension working condition according to the embodiment of the present application is shown. Figure 6 In an embodiment, according to the working condition, at least one of the first electric proportional seat valve 6.1, the second electric proportional seat valve 6.2, the third electric proportional seat valve 6.3 and the fourth electric proportional seat valve 6.4 is controlled, including: in the case that the working condition is simultaneously determined as the normal speed working condition, the overrunning working condition and the extension working condition, the first electric proportional seat valve 6.1 is controlled to be closed, the third electric proportional seat valve 6.3 is controlled to be closed, and the fourth electric proportional seat valve 6.4 is controlled to be closed; and the opening of the second electric proportional seat valve 6.2 is adjusted according to the front and back pressure of the second electric proportional seat valve 6.2.

[0113] In the above normal speed overrunning extension working condition, the inlet flow control and the outlet pressure control of the hydraulic cylinder 10 are performed. The second electric proportional seat valve 6.2 is opened and the opening of the second electric proportional seat valve 6.2 is adjusted to maintain the outlet pressure of the hydraulic cylinder 10 in a certain range, preventing the hydraulic cylinder 10 from stalling. The remaining electric proportional seat valves are all closed. At this time, the rod cavity oil way is high pressure, and the rodless cavity oil way is low pressure. The second hydraulic control check valve 4.2 is automatically opened in the reverse direction under the action of pressure. The oil supply flow of the rodless cavity is greater than the oil discharge flow of the rod cavity. The oil of the accumulator 5 is supplemented to the rodless cavity of the hydraulic cylinder 10 through the second hydraulic control check valve 4.2 and the fourth electric proportional seat valve 6.4, so that the speed of the hydraulic cylinder 10 is in proportional relationship with the control command i.

[0114] In particular, in the working condition of high-frequency reciprocating action of the hydraulic cylinder 10, since the electric control response is higher than the hydraulic control response, the first electric proportional seat valve 6.1 can assist the first hydraulic control check valve 4.1, and the second electric proportional seat valve 6.2 can assist the second hydraulic control check valve 4.2 to balance the flow of the two cavities (i.e. the flow of the rod cavity and the flow of the rodless cavity) of the hydraulic cylinder 10, reduce the pressure impact of the electro-hydraulic actuator system, and improve the frequency response of the system. If only the hydraulic control check valve is used to balance the flow difference of the two cavities of the asymmetric cylinder, the frequency response of the hydraulic control check valve is lower than that of the electric proportional seat valve. Therefore, if only the hydraulic control check valve is relied on, the longer opening and closing time of the valve port of the hydraulic control check valve leads to the inability to adapt to the requirement of the system on high frequency response. In the embodiment of the present application, the electric proportional seat valve is used to cooperate with the hydraulic control check valve to balance the flow difference and improve the frequency response of the system.

[0115] Figure 7 The control scheme diagram of the low-speed impedance-retraction working condition according to the embodiment of the application is schematically shown, which can be seen from Figure 7 In an embodiment, according to the working condition, the control of at least one of the first electric proportional seat valve 6.1, the second electric proportional seat valve 6.2, the third electric proportional seat valve 6.3 and the fourth electric proportional seat valve 6.4 comprises: in the case that the working condition is simultaneously determined as the low-speed working condition, the impedance working condition and the retraction working condition, the second electric proportional seat valve 6.2 is controlled to be closed, the third electric proportional seat valve 6.3 is controlled to be fully opened, and the fourth electric proportional seat valve 6.4 is controlled to be closed; and the opening degree of the first electric proportional seat valve 6.1 is controlled according to the outlet flow of the bidirectional hydraulic pump 11 and the required flow of the hydraulic cylinder 10.

[0116] Figure 8 The control scheme diagram of the normal-speed impedance-retraction working condition according to the embodiment of the application is schematically shown, which can be seen from Figure 8 In an embodiment, according to the working condition, the control of at least one of the first electric proportional seat valve 6.1, the second electric proportional seat valve 6.2, the third electric proportional seat valve 6.3 and the fourth electric proportional seat valve 6.4 comprises: in the case that the working condition is simultaneously determined as the normal-speed working condition, the impedance working condition and the retraction working condition, the first electric proportional seat valve 6.1 is controlled to be closed, the second electric proportional seat valve 6.2 is controlled to be closed, the third electric proportional seat valve 6.3 is controlled to be fully opened, and the fourth electric proportional seat valve 6.4 is controlled to be closed.

[0117] Figure 9 The control scheme diagram of the low-speed override-retraction working condition according to the embodiment of the application is schematically shown, which can be seen from Figure 9 In an embodiment, according to the working condition, the control of at least one of the first electric proportional seat valve 6.1, the second electric proportional seat valve 6.2, the third electric proportional seat valve 6.3 and the fourth electric proportional seat valve 6.4 comprises: in the case that the working condition is simultaneously determined as the low-speed working condition, the override working condition and the retraction working condition, the second electric proportional seat valve 6.2 is controlled to be closed, and the fourth electric proportional seat valve 6.4 is controlled to be closed; the opening degree of the first electric proportional seat valve 6.1 is controlled according to the outlet flow of the bidirectional hydraulic pump 11 and the required flow of the hydraulic cylinder 10; and the opening degree of the third electric proportional seat valve 6.3 is adjusted according to the front and back pressures of the third electric proportional seat valve 6.3.

[0118] Figure 10 The control scheme diagram of the normal-speed override-retraction working condition according to the embodiment of the application is schematically shown, which can be seen from Figure 10In an embodiment, the control of at least one of the first electric proportional seat valve 6.1, the second electric proportional seat valve 6.2, the third electric proportional seat valve 6.3 and the fourth electric proportional seat valve 6.4 according to the working condition comprises: when the working condition is determined as the constant speed working condition, the overrun working condition and the retracting working condition at the same time, the first electric proportional seat valve 6.1 is controlled to be closed, the second electric proportional seat valve 6.2 is controlled to be closed, and the fourth electric proportional seat valve 6.4 is controlled to be closed; and the opening of the third electric proportional seat valve 6.3 is adjusted according to the front and back pressures of the third electric proportional seat valve 6.3.

[0119] The control principles of the extension working condition and the retracting working condition are similar, and are not described here again. The state control of the first electric proportional seat valve 6.1 in the retracting working condition is the same as the state control of the fourth electric proportional seat valve 6.4 in the corresponding extension working condition; the state control of the second electric proportional seat valve 6.2 in the retracting working condition is the same as the state control of the third electric proportional seat valve 6.3 in the corresponding extension working condition; the state control of the third electric proportional seat valve 6.3 in the retracting working condition is the same as the state control of the second electric proportional seat valve 6.2 in the corresponding extension working condition; and the state control of the fourth electric proportional seat valve 6.4 in the retracting working condition is the same as the state control of the first electric proportional seat valve 6.1 in the corresponding extension working condition. For example, in the constant speed resistance retracting working condition, the first electric proportional seat valve 6.1 is closed (the fourth electric proportional seat valve 6.4 is closed in the constant speed resistance extension working condition), the second electric proportional seat valve 6.2 is closed (the third electric proportional seat valve 6.3 is closed in the constant speed resistance extension working condition), the third electric proportional seat valve 6.3 is fully opened (the second electric proportional seat valve 6.2 is fully opened in the constant speed resistance extension working condition), and the fourth electric proportional seat valve 6.4 is closed (the first electric proportional seat valve 6.1 is closed in the constant speed resistance extension working condition).

[0120] Figure 11 The control scheme diagrams of various hydraulic cylinder working conditions according to the embodiment of the application are schematically shown in the following table. Figure 11 In the table, the first electric proportional seat valve 6.1 is abbreviated as valve 6.1, the second electric proportional seat valve 6.2 is abbreviated as valve 6.2, the third electric proportional seat valve 6.3 is abbreviated as valve 6.3, the fourth electric proportional seat valve 6.4 is abbreviated as valve 6.4, and the pump rotating speed is denoted as n. According to the table, the control of the first electric proportional seat valve 6.1, the second electric proportional seat valve 6.2, the third electric proportional seat valve 6.3 and the fourth electric proportional seat valve 6.4 according to the working condition comprises: Figure 11 It can be understood that the identification process of various hydraulic cylinder working conditions and the corresponding control mode are as follows.

[0121] The prior art electro-hydraulic actuator system only controls the flow into the hydraulic cylinder 10 by the motor pump volume speed, that is, directly by the motor speed, so the response speed of the motor pump in the prior art is lower than the response speed of the valve control in the embodiment of the present application; the system response and speed regulation characteristics in the prior art are not as good as the valve control under complex working conditions; or, the inlet and outlet of the valve control system in the prior art are usually controlled by the same valve, and the throttling loss is large. In the embodiment of the present application, each electric proportional seat valve is independently controlled by the load port, has high flexibility, small throttling loss, and stable control in the overrun working condition and low-speed working condition; multiple electric proportional seat valves are used to assist the motor pump volume speed, so as to improve the control accuracy and frequency response; multiple electric proportional seat valves are introduced to assist the valve control, which can effectively compensate for the insufficient response and control accuracy of the motor pump volume speed, and minimize energy consumption.

[0122] In an embodiment, the method further comprises: in the case where no operation instruction of the bidirectional hydraulic pump 11 is received or the electro-hydraulic actuator system is stopped, controlling the second electric proportional seat valve 6.2 to be closed and the third electric proportional seat valve 6.3 to be closed. In this way, the hydraulic cylinder 10 can be reliably stopped under the action of the second electric proportional seat valve 6.2 and the third electric proportional seat valve 6.3, and is kept at the current position, and the oil cannot flow out of the hydraulic cylinder 10, thereby reducing the system energy consumption. The prior art electro-hydraulic actuator system usually keeps the position by using a reversing valve or a motor, and the reversing valve is a spool valve structure, resulting in large internal leakage; using the motor to keep the position results in large energy consumption and heat generation; and in the embodiment of the present application, the multiple electric proportional seat valves are all cone valve structures, and have good sealing performance.

[0123] In an embodiment, the method further comprises: obtaining a third pressure value of a first oil port of the bidirectional hydraulic pump 11, a fourth pressure value of a second oil port of the bidirectional hydraulic pump 11, and a fifth pressure value of the accumulator 5; in the case where at least one of the first pressure value, the second pressure value, the third pressure value, the fourth pressure value, and the fifth pressure value is greater than a pressure threshold value, controlling the second electric proportional seat valve 6.2 to be powered off, the third electric proportional seat valve 6.3 to be powered off, the corresponding motor 1 of the bidirectional hydraulic pump 11 to be stopped, the first electric proportional seat valve 6.1 to be opened, and the fourth electric proportional seat valve 6.4 to be opened.

[0124] The electro-hydraulic actuator system further comprises a first safety valve 7.1 and a second safety valve 7.2, which can be seen from Figure 1The first safety valve 7.1 is connected to the rod cavity oil way of the hydraulic cylinder 10, and the second safety valve 7.2 is connected to the rodless cavity oil way of the hydraulic cylinder 10, and the first safety valve 7.1 and the second safety valve 7.2 are used to limit the inlet and outlet pressures of the bidirectional hydraulic pump 11. The electro-hydraulic actuator system further comprises a first pressure sensor 8.1, a second pressure sensor 8.2, a third pressure sensor 8.3, a fourth pressure sensor 8.4 and a fifth pressure sensor 8.5, the first pressure sensor 8.1 and the second pressure sensor 8.2 are arranged at the inlet and outlet of the second electric proportional seat valve 6.2 respectively, the third pressure sensor 8.3 and the fourth pressure sensor 8.4 are arranged at the inlet and outlet of the third electric proportional seat valve 6.3 respectively, and the fifth electric proportional seat valve 8.5 is arranged at the outlet of the accumulator 5.

[0125] The electro-hydraulic actuator system limits the maximum inlet and outlet pressures of the bidirectional hydraulic pump 11 through the first safety valve 7.1 and the second safety valve 7.2, and simultaneously monitors the pressures at various positions of the electro-hydraulic actuator system in real time through multiple pressure sensors, thereby performing secondary protection. When an abnormal pressure of the electro-hydraulic actuator system is monitored, an alarm information is immediately sent out, and the system protection is performed through the ways of powering off the second electric proportional seat valve 6.2, powering off the third electric proportional seat valve 6.3, stopping the motor 1 corresponding to the bidirectional hydraulic pump 11, opening the first electric proportional seat valve 6.1, opening the fourth electric proportional seat valve 6.4, etc., thereby realizing the closed-loop control of the pressure.

[0126] The pressure unloading function of the port of the bidirectional hydraulic pump 11 can be realized through the electric proportional seat valve. If the second electric proportional seat valve 6.2 and the third electric proportional seat valve 6.3 fail or the system is urgently stopped, and a large pressure exists at the port of the bidirectional hydraulic pump 11 but does not reach the opening pressure of the first safety valve 7.1 and the second safety valve 7.2, at this time, the first electric proportional seat valve 6.1 or the fourth electric proportional seat valve 6.4 can be opened to communicate one port of the bidirectional hydraulic pump 11 with the accumulator 5, thereby realizing the pressure unloading of the pump port and prolonging the service life of the bidirectional hydraulic pump 11.

[0127] In an embodiment, the electro-hydraulic actuator system further comprises a displacement sensor 9 connected to the piston of the hydraulic cylinder 10; the method further comprises: receiving a target speed of the piston; obtaining an actual speed of the piston according to the displacement information detected by the displacement sensor 9; adjusting the speed of the piston according to a first deviation between the target speed and the actual speed in a case that the first deviation is greater than a first preset deviation; receiving a target position of the piston; obtaining an actual position of the piston according to the displacement information detected by the displacement sensor 9; and adjusting the position of the piston according to a second deviation between the target position and the actual position in a case that the second deviation is greater than a second preset deviation.

[0128] When the controller 3 receives the target position, the displacement information fed back in real time by the displacement sensor 9 is compared, and a corresponding control instruction is output by a closed-loop algorithm such as PID (Proportional Integral Derivative), so as to realize closed-loop control of the position of the electro-hydraulic actuator. By differentiating the displacement information fed back in real time by the displacement sensor 9, the speed of the hydraulic cylinder 10 can be obtained in real time. When the controller 3 receives the target speed, the speed of the hydraulic cylinder 10 is compared, and a corresponding control instruction is output by a closed-loop algorithm such as PID, so as to realize closed-loop control of the speed of the electro-hydraulic actuator. The speed closed loop is taken as an "inner loop", and the position closed loop is taken as an "outer loop", so as to realize double closed-loop control of the position and speed of the electro-hydraulic actuator.

[0129] The structure of the electro-hydraulic actuator system and the control method thereof will be further described below with some specific embodiments.

[0130] The electro-hydraulic actuator system in the embodiment can control the flow entering the hydraulic cylinder 10 by controlling the pump rotating speed and rotating direction of the bidirectional hydraulic pump 11, and then control the action of the hydraulic cylinder 10. The pressure of the system is collected in real time by the pressure sensors, and the displacement of the hydraulic cylinder 10 is detected by the displacement sensor, so as to realize closed-loop control of the position and speed of the hydraulic cylinder 10 in cooperation with the electric proportional seat valves. In an embodiment, the motor driver 2 is used to control the rotating speed and rotating direction of the motor 1. When the motor 1 is a servo motor, the motor driver 2 corresponds to a servo driver; when the motor 1 is a variable frequency motor, the motor driver 2 corresponds to a frequency converter.

[0131] The second electric proportional seat valve 6.2 is located at the rod cavity outlet of the hydraulic cylinder 10, the third electric proportional seat valve 6.3 is located at the rodless cavity outlet of the hydraulic cylinder 10, the first electric proportional seat valve 6.1 is located between the rod cavity oil way of the hydraulic cylinder 10 and the accumulator 5, and the fourth electric proportional seat valve 6.4 is located between the rodless cavity oil way of the hydraulic cylinder 10 and the accumulator 5. The plurality of electric proportional seat valves can only be unidirectionally conducted, and are at the unidirectional valve end when powered off. Such valves are of a cone valve structure and are reliable in sealing. The controller 3 can receive instruction signals and data of the pressure sensors and the displacement sensor, analyze the working condition in real time by a control algorithm, and then send control instructions to the motor driver 2, the first electric proportional seat valve 6.1, the second electric proportional seat valve 6.2, the third electric proportional seat valve 6.3 and the fourth electric proportional seat valve 6.4 through a control program, so as to control the action of the hydraulic cylinder 10.

[0132] For the bidirectional hydraulic pump 11, a bidirectional variable pump can be used instead of the bidirectional fixed displacement pump, and the output flow of the bidirectional hydraulic pump 11 can be controlled by controlling the two variables of the rotation speed and the displacement of the bidirectional hydraulic pump 11, so as to further control the speed of the hydraulic cylinder 10. Generally, in order to ensure the volumetric efficiency and service life of the bidirectional hydraulic pump 11, the bidirectional hydraulic pump 11 has a minimum rotation speed limit. In an embodiment, the low-speed movement of the hydraulic cylinder 10 can be controlled by the electric proportional seat valve by keeping the motor 1 at the minimum rotation speed, and after the bidirectional variable pump is used instead of the bidirectional fixed displacement pump, the speed of the hydraulic cylinder 10 can be controlled by keeping the bidirectional hydraulic pump 11 at the minimum rotation speed and adjusting the displacement to control the pump outlet flow.

[0133] In an embodiment, a bidirectional fixed displacement pump / bidirectional variable pump motor can be used instead of the bidirectional fixed displacement pump / bidirectional variable pump, and a generator-motor integrated machine can be used instead of the motor. When the electro-hydraulic actuator system is in an overrun condition, the bidirectional hydraulic pump 11 works in a motor mode to drive the generator-motor integrated machine to generate electricity, so as to convert potential energy into electrical energy and realize energy recovery.

[0134] The embodiment of the present application provides a controller configured to perform the control method for the electro-hydraulic actuator system in any one of the above embodiments.

[0135] The electro-hydraulic actuator system comprises:

[0136] The hydraulic cylinder comprises a rod cavity and a rodless cavity;

[0137] The bidirectional hydraulic pump;

[0138] The accumulator;

[0139] The plurality of electric proportional seat valves comprises a first electric proportional seat valve, a second electric proportional seat valve, a third electric proportional seat valve, and a fourth electric proportional seat valve;

[0140] The first end of the bidirectional hydraulic pump is connected to the second end of the first electric proportional seat valve and the first end of the second electric proportional seat valve, the second end of the bidirectional hydraulic pump is connected to the first end of the third electric proportional seat valve and the second end of the fourth electric proportional seat valve, the first end of the first electric proportional seat valve and the first end of the fourth electric proportional seat valve are both connected to the accumulator, the second end of the second electric proportional seat valve is connected to the rod cavity, and the second end of the third electric proportional seat valve is connected to the rodless cavity.

[0141] Specifically, the controller can be configured to:

[0142] acquire a pump rotation speed and a pump rotation direction of the bidirectional hydraulic pump, a first pressure value of the rod cavity, and a second pressure value of the rodless cavity;

[0143] determine a working condition of the hydraulic cylinder according to the pump rotation speed and the pump rotation direction, the first pressure value, and the second pressure value;

[0144] According to the working condition, at least one of the first, second, third and fourth electric proportional seat valves is controlled.

[0145] In the embodiment of the application, the controller is configured to:

[0146] The working condition of the hydraulic cylinder is determined according to the pump rotating speed and the pump rotating direction, the first pressure value and the second pressure value, including at least one of the following:

[0147] In the case where the pump rotating direction indicates that the bidirectional hydraulic pump sucks oil from the rodless chamber and discharges oil to the rod chamber, the working condition of the hydraulic cylinder is determined as the extension condition, and in the case where the pump rotating direction indicates that the bidirectional hydraulic pump sucks oil from the rod chamber and discharges oil to the rodless chamber, the working condition is determined as the retraction condition.

[0148] In the case where the flow direction indicated by the pump rotating direction is opposite to the load direction, the working condition of the hydraulic cylinder is determined as the resistance condition, and in the case where the flow direction indicated by the pump rotating direction is the same as the load direction, the working condition is determined as the overrun condition, and the load direction is determined according to the first pressure value, the second pressure value, the acting area of the rodless chamber and the acting area of the rod chamber.

[0149] In the case where the pump rotating speed is greater than or equal to the rotating speed threshold value, the working condition of the hydraulic cylinder is determined as the constant speed condition, and in the case where the pump rotating speed is less than the rotating speed threshold value, the working condition is determined as the low speed condition.

[0150] In the embodiment of the application, the controller is configured to:

[0151] According to the working condition, at least one of the first, second, third and fourth electric proportional seat valves is controlled, including:

[0152] In the case where the working condition is simultaneously determined as the low speed condition, the resistance condition and the extension condition, the first electric proportional seat valve is controlled to be closed, the second electric proportional seat valve is controlled to be fully opened, and the third electric proportional seat valve is controlled to be closed.

[0153] The opening degree of the fourth electric proportional seat valve is controlled according to the outlet flow of the bidirectional hydraulic pump and the required flow of the hydraulic cylinder.

[0154] In the embodiment of the application, the controller is configured to:

[0155] According to the working condition, at least one of the first, second, third and fourth electric proportional seat valves is controlled, including:

[0156] In the case where the working condition is simultaneously determined as the low speed condition, the overrun condition and the extension condition, the first electric proportional seat valve is controlled to be closed, and the third electric proportional seat valve is controlled to be closed.

[0157] adjusting the opening of the second electric proportional seat valve according to the front and back pressures of the second electric proportional seat valve;

[0158] controlling the opening of the fourth electric proportional seat valve according to the outlet flow of the bidirectional hydraulic pump and the required flow of the hydraulic cylinder.

[0159] In the embodiment of the present application, the controller is configured to:

[0160] According to the working condition, at least one of the first electric proportional seat valve, the second electric proportional seat valve, the third electric proportional seat valve and the fourth electric proportional seat valve is controlled, including:

[0161] In the case where the working condition is determined as the constant speed working condition, the resistance working condition and the extension working condition at the same time, the first electric proportional seat valve is controlled to be closed, the second electric proportional seat valve is controlled to be fully opened, the third electric proportional seat valve is controlled to be closed, and the fourth electric proportional seat valve is controlled to be closed.

[0162] In the embodiment of the present application, the controller is configured to:

[0163] According to the working condition, at least one of the first electric proportional seat valve, the second electric proportional seat valve, the third electric proportional seat valve and the fourth electric proportional seat valve is controlled, including:

[0164] In the case where the working condition is determined as the constant speed working condition, the overrunning working condition and the extension working condition at the same time, the first electric proportional seat valve is controlled to be closed, the third electric proportional seat valve is controlled to be closed, and the fourth electric proportional seat valve is controlled to be closed.

[0165] adjusting the opening of the second electric proportional seat valve according to the front and back pressures of the second electric proportional seat valve.

[0166] In the embodiment of the present application, the controller is configured to:

[0167] In the case where the running instruction of the bidirectional hydraulic pump is not received or the electro-hydraulic actuator system is stopped, the second electric proportional seat valve is controlled to be closed and the third electric proportional seat valve is controlled to be closed.

[0168] In the embodiment of the present application, the controller is configured to:

[0169] obtaining a third pressure value of a first oil port of the bidirectional hydraulic pump, a fourth pressure value of a second oil port of the bidirectional hydraulic pump, and a fifth pressure value of the accumulator;

[0170] In the case where at least one of the first pressure value, the second pressure value, the third pressure value, the fourth pressure value and the fifth pressure value is greater than a pressure threshold value, the second electric proportional seat valve is controlled to be powered off, the third electric proportional seat valve is controlled to be powered off, the corresponding motor of the bidirectional hydraulic pump is controlled to be stopped, the first electric proportional seat valve is controlled to be opened, and the fourth electric proportional seat valve is controlled to be opened.

[0171] In the embodiment of the present application, the electro-hydraulic actuator system further comprises:

[0172] a displacement sensor connected to the piston of the hydraulic cylinder;

[0173] the controller is configured to:

[0174] receive a target speed of the piston;

[0175] obtain an actual speed of the piston according to displacement information detected by the displacement sensor;

[0176] adjust the speed of the piston according to a first deviation between the target speed and the actual speed when the first deviation is greater than a first preset deviation;

[0177] receive a target position of the piston;

[0178] obtain an actual position of the piston according to displacement information detected by the displacement sensor;

[0179] adjust the position of the piston according to a second deviation between the target position and the actual position when the second deviation is greater than a second preset deviation.

[0180] The embodiment of the present application provides an electro-hydraulic actuator system, comprising:

[0181] a hydraulic cylinder, the hydraulic cylinder comprising a rod cavity and a rodless cavity;

[0182] a bidirectional hydraulic pump;

[0183] an accumulator;

[0184] a plurality of electric proportional seat valves, the plurality of electric proportional seat valves comprising a first electric proportional seat valve, a second electric proportional seat valve, a third electric proportional seat valve and a fourth electric proportional seat valve;

[0185] a first end of the bidirectional hydraulic pump is connected to a second end of the first electric proportional seat valve and a first end of the second electric proportional seat valve, a second end of the bidirectional hydraulic pump is connected to a first end of the third electric proportional seat valve and a second end of the fourth electric proportional seat valve, a first end of the first electric proportional seat valve and a first end of the fourth electric proportional seat valve are both connected to the accumulator, a second end of the second electric proportional seat valve is connected to the rod cavity, and a second end of the third electric proportional seat valve is connected to the rodless cavity; and

[0186] the controller described above.

[0187] The embodiment of the present application provides an engineering machine, comprising the electro-hydraulic actuator system described above.

[0188] Those skilled in the art will appreciate that embodiments of the application can be readily used as software, hardware, or a combination of software and hardware. In a typical configuration, a computing device includes one or more processors (CPUs), input / output interfaces, network interfaces, and memory.

[0189] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks.

[0190] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks.

[0191] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks.

[0192] In a typical configuration, a computing device includes one or more processors (CPUs), input / output interfaces, network interfaces, and memory.

[0193] The memory can include non-persistent memory, random access memory (RAM), and / or non-volatile memory, etc. in the form of a computer-readable medium, such as read only memory (ROM) or flash memory. The memory is an example of computer-readable media.

[0194] Computer-readable media includes permanent and non-permanent, movable and non-movable media that can be implemented by any method or technology to store information. The information can be computer-readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical storage, magnetic cassette, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information accessible to a computing device. According to the definition herein, computer-readable media does not include transitory media such as modulated data signals and carriers.

[0195] It should also be noted that the terms "comprising", "containing", or any other variant thereof are intended to cover non-exclusive inclusions, so that a process, method, article or apparatus that includes a list of elements does not only include those elements, but also includes other elements not explicitly listed, or further includes elements inherent in such a process, method, article or apparatus. Without more limitations, the element defined by the statement "comprising a" does not exclude the presence of additional identical elements in the process, method, article or apparatus that includes the element.

[0196] The above only is an embodiment of the present application, and is not used to limit the present application. For those skilled in the art, the present application can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application shall be included in the scope of claims of the present application.

Claims

1. A control method for an electro-hydraulic actuator system, characterized in that, The electro-hydraulic actuator system includes: Hydraulic cylinders include rod chambers and rodless chambers; Two-way hydraulic pump; accumulator; Multiple electro-proportional seat valves, the multiple electro-proportional seat valves including a first electro-proportional seat valve, a second electro-proportional seat valve, a third electro-proportional seat valve and a fourth electro-proportional seat valve; Wherein, the first end of the bidirectional hydraulic pump is connected to the second end of the first electro-proportional seat valve and the first end of the second electro-proportional seat valve, the second end of the bidirectional hydraulic pump is connected to the first end of the third electro-proportional seat valve and the second end of the fourth electro-proportional seat valve, the first end of the first electro-proportional seat valve and the first end of the fourth electro-proportional seat valve are both connected to the accumulator, the second end of the second electro-proportional seat valve is connected to the rod chamber, and the second end of the third electro-proportional seat valve is connected to the rodless chamber; The method includes: The pump speed and direction of rotation of the bidirectional hydraulic pump, the first pressure value of the rod chamber, and the second pressure value of the rodless chamber are obtained. The operating conditions of the hydraulic cylinder are determined based on the pump speed and pump rotation direction, the first pressure value and the second pressure value, wherein the operating conditions include low-speed operating conditions, overrunning operating conditions and retraction operating conditions. According to the operating conditions, control at least one of the first electro-proportional seat valve, the second electro-proportional seat valve, the third electro-proportional seat valve, and the fourth electro-proportional seat valve; The step of controlling at least one of the first electro-proportional seat valve, the second electro-proportional seat valve, the third electro-proportional seat valve, and the fourth electro-proportional seat valve according to the operating condition includes: When the operating conditions are simultaneously determined to be low-speed operating conditions, overtaking operating conditions, and retraction operating conditions, the second electro-proportional seat valve and the fourth electro-proportional seat valve are controlled to close. The opening degree of the third electro-proportional seat valve is adjusted according to the pressure before and after the third electro-proportional seat valve; The opening degree of the first electro-proportional seat valve is controlled according to the outlet flow rate of the bidirectional hydraulic pump and the required flow rate of the hydraulic cylinder.

2. The method according to claim 1, characterized in that, Determining the operating condition of the hydraulic cylinder based on the pump speed and direction of rotation, the first pressure value, and the second pressure value includes at least one of the following: When the pump rotation direction indicates that the bidirectional hydraulic pump draws oil from the rod chamber and discharges oil to the rodless chamber, the hydraulic cylinder is determined to be in an extended state. When the pump rotation direction indicates that the bidirectional hydraulic pump draws oil from the rodless chamber and discharges oil to the rod chamber, the hydraulic cylinder is determined to be in a retracted state. When the flow direction indicated by the pump rotation direction is opposite to the load direction, the hydraulic cylinder is determined to be in an impedance condition. When the flow direction indicated by the pump rotation direction is the same as the load direction, the condition is determined to be in an overrun condition. The load direction is determined based on the first pressure value, the second pressure value, the effective area of ​​the rodless chamber, and the effective area of ​​the rod chamber. When the pump speed is greater than or equal to the speed threshold, the hydraulic cylinder is determined to be in constant speed condition; when the pump speed is less than the speed threshold, the condition is determined to be in low speed condition.

3. The method according to claim 2, characterized in that, The step of controlling at least one of the first electro-proportional seat valve, the second electro-proportional seat valve, the third electro-proportional seat valve, and the fourth electro-proportional seat valve according to the operating condition includes: When the operating conditions are simultaneously determined to be low-speed operating condition, impedance operating condition, and extension operating condition, the first electro-proportional seat valve is controlled to close, the second electro-proportional seat valve is fully opened, and the third electro-proportional seat valve is controlled to close. The opening degree of the fourth electro-proportional seat valve is controlled according to the outlet flow rate of the bidirectional hydraulic pump and the required flow rate of the hydraulic cylinder.

4. The method according to claim 2, wherein controlling at least one of the first electro-proportional seat valve, the second electro-proportional seat valve, the third electro-proportional seat valve, and the fourth electro-proportional seat valve according to the operating condition comprises: When the operating conditions are simultaneously determined to be low-speed operating conditions, overrunning operating conditions, and extension operating conditions, the first electro-proportional seat valve and the third electro-proportional seat valve are controlled to close. Adjust the opening degree of the second electro-proportional seat valve according to the pressure before and after the second electro-proportional seat valve; The opening degree of the fourth electro-proportional seat valve is controlled according to the outlet flow rate of the bidirectional hydraulic pump and the required flow rate of the hydraulic cylinder.

5. The method according to claim 2, characterized in that, The step of controlling at least one of the first electro-proportional seat valve, the second electro-proportional seat valve, the third electro-proportional seat valve, and the fourth electro-proportional seat valve according to the operating condition includes: When the operating conditions are simultaneously determined to be constant speed, impedance, and extension, the first electro-proportional seat valve is closed, the second electro-proportional seat valve is fully open, the third electro-proportional seat valve is closed, and the fourth electro-proportional seat valve is closed.

6. The method according to claim 2, characterized in that, The step of controlling at least one of the first electro-proportional seat valve, the second electro-proportional seat valve, the third electro-proportional seat valve, and the fourth electro-proportional seat valve according to the operating condition includes: When the operating conditions are simultaneously determined to be constant speed operating condition, overrunning operating condition, and extension operating condition, the first electro-proportional seat valve, the third electro-proportional seat valve, and the fourth electro-proportional seat valve are controlled to close. Adjust the opening degree of the second electro-proportional seat valve according to the pressure before and after the second electro-proportional seat valve.

7. The method according to claim 1, characterized in that, The method further includes: In the absence of an operating command from the bidirectional hydraulic pump or a shutdown of the electro-hydraulic actuator system, the second electro-proportional seat valve and the third electro-proportional seat valve are controlled to close.

8. The method according to claim 1, characterized in that, The method further includes: Obtain the third pressure value of the first oil port of the bidirectional hydraulic pump, the fourth pressure value of the second oil port of the bidirectional hydraulic pump, and the fifth pressure value of the accumulator; If at least one of the first pressure value, the second pressure value, the third pressure value, the fourth pressure value, and the fifth pressure value is greater than the pressure threshold, the second electro-proportional seat valve is de-energized, the third electro-proportional seat valve is de-energized, the motor corresponding to the bidirectional hydraulic pump is stopped, the first electro-proportional seat valve is opened, and the fourth electro-proportional seat valve is opened.

9. The method according to claim 1, characterized in that, The electro-hydraulic actuator system also includes: A displacement sensor is connected to the piston of the hydraulic cylinder; The method further includes: Receive the target velocity of the piston; The actual speed of the piston is obtained based on the displacement information detected by the displacement sensor; If the first deviation between the target speed and the actual speed is greater than a first preset deviation, the speed of the piston is adjusted according to the first deviation. Receive the target position of the piston; The actual position of the piston is obtained based on the displacement information detected by the displacement sensor; If the second deviation between the target position and the actual position is greater than the second preset deviation, the position of the piston is adjusted according to the second deviation.

10. A controller, characterized in that, Configured to perform a control method for an electro-hydraulic actuator system according to any one of claims 1 to 9.

11. An electro-hydraulic actuator system, characterized in that, include: A hydraulic cylinder, comprising a rod-side chamber and a rodless chamber; Two-way hydraulic pump; accumulator; Multiple electro-proportional seat valves, the multiple electro-proportional seat valves including a first electro-proportional seat valve, a second electro-proportional seat valve, a third electro-proportional seat valve and a fourth electro-proportional seat valve; Wherein, the first end of the bidirectional hydraulic pump is connected to the second end of the first electro-proportional seat valve and the first end of the second electro-proportional seat valve; the second end of the bidirectional hydraulic pump is connected to the first end of the third electro-proportional seat valve and the second end of the fourth electro-proportional seat valve; the first ends of the first and fourth electro-proportional seat valves are both connected to the accumulator; the second end of the second electro-proportional seat valve is connected to the rod chamber; and the second end of the third electro-proportional seat valve is connected to the rodless chamber. The controller according to claim 10.

12. An engineering machinery, characterized in that, Including the electro-hydraulic actuator system according to claim 11.

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