Electro-hydrostatic actuator system and working machine

Abstract

The utility model provides an electro-hydrostatic actuator system and an operation machine, and belongs to the technical field of electro-hydraulic control. The electro-hydrostatic actuator system comprises a hydraulic actuator, an electro-hydrostatic actuator and a hydraulic control system, wherein the hydraulic actuator comprises a first hydraulic cavity and a second hydraulic cavity; the balance valve comprises a first oil port, a second oil port and a control end, the control end is used for controlling the balance valve to work in a first state or a second state, in the first state, the first oil port is communicated with the second oil port in a one-way mode, and in the second state, the first oil port is communicated with the second oil port in a one-way mode. Proportional throttling is performed between the first oil port and the second oil port; the first end of the motor pump is connected with the first oil port, the second end of the motor pump is connected with the first hydraulic cavity, and the second oil port is connected with the second hydraulic cavity. The speed of the hydraulic actuator is controlled under the load exceeding condition, stall under the load exceeding condition is prevented, and safety is guaranteed.

Description

Technical Field

[0001] The utility model relates to the technical field of electro-hydraulic control, and particularly relates to an electro-hydrostatic actuator system and a work machine. Background Art

[0002] An electro-hydrostatic actuator system is an actuator that highly integrates a motor, a pump, a hydraulic valve, a fuel tank, and a hydraulic cylinder, and controls the hydraulic cylinder through the volume speed regulation of the motor pump. Compared with the traditional centralized valve control system, the electro-hydrostatic actuator system has less throttling and overflow loss, uses the power transmission method to replace the hydraulic pipeline, has the advantages of high energy efficiency, modularization, easy maintenance, etc., and has a higher power-to-weight ratio than the electric cylinder of the same specification.

[0003] The existing electro-hydrostatic actuator system uses a throttle valve to control the movement speed of the hydraulic cylinder, but it is difficult to control the speed under the overloading condition (that is, the force direction of the hydraulic cylinder is consistent with the movement direction), which brings greater safety risks. Summary of the Utility Model

[0004] The purpose of the embodiment of the utility model is to provide an electro-hydrostatic actuator system and a work machine. The electro-hydrostatic actuator system can realize the speed control of the hydraulic actuator under the overloading condition by setting a balance valve, prevent stalling under the overloading condition, and ensure safety.

[0005] To achieve the above purpose, the first aspect of the present application provides an electro-hydrostatic actuator system, including:

[0006] A hydraulic actuator, the hydraulic actuator includes a first hydraulic chamber and a second hydraulic chamber;

[0007] A balance valve, the balance valve includes a first oil port, a second oil port, and a control end, the control end is used to control the balance valve to work in a first state or a second state. In the first state, the first oil port to the second oil port conducts unidirectionally. In the second state, proportional throttling is performed between the first oil port and the second oil port;

[0008] A motor pump,

[0009] The first end of the motor pump is connected to the first oil port, the second end of the motor pump is connected to the first hydraulic chamber, and the second oil port is connected to the second hydraulic chamber.

[0010] In the embodiment of the present application, the number of the hydraulic actuators and the balance valves is multiple, and one hydraulic actuator is correspondingly connected to one or more balance valves.

[0011] In the embodiment of the present application, the number of motor pumps is multiple, and one motor pump is correspondingly connected to one or more hydraulic actuators.

[0012] In an embodiment of the present application, it further includes explosion-proof valves respectively corresponding to the multiple hydraulic actuators. The oil inlet of any one of the explosion-proof valves is connected to the second hydraulic chamber of the corresponding hydraulic actuator, and the oil outlets of the multiple explosion-proof valves are connected in sequence.

[0013] In an embodiment of the present application, it further includes an accumulator. The accumulator is connected to the motor pump and is used to supply oil to the motor pump.

[0014] In an embodiment of the present application, it further includes a switching valve. One end of the switching valve is connected to the accumulator, and the other end is respectively connected to the second end of the motor pump and the first hydraulic chamber.

[0015] In an embodiment of the present application, the other end of the switching valve is further connected to the control end. The maximum pressure of the accumulator is less than the opening pressure of the control end. When the accumulator provides control pressure for the control end, the balance valve operates in the first state.

[0016] In an embodiment of the present application, it further includes an oil filling port. The oil filling port is connected to the accumulator.

[0017] In an embodiment of the present application, the balance valve includes a valve core. The control end is connected to the second end of the motor pump, and the valve core is driven to move through the control end to control the balance valve to operate in the first state or the second state.

[0018] In an embodiment of the present application, the balance valve further includes a first overflow valve. The first overflow valve is connected between the first oil port and the second oil port and is used to conduct the first oil port and the second oil port when the pressure at the second oil port is greater than a first threshold.

[0019] In an embodiment of the present application, it further includes a second overflow valve and a make-up oil valve. The second overflow valve is connected between the first end and the second end of the motor pump. The one-way cut-off end of the make-up oil valve is connected to the hydraulic actuator, and the one-way conducting end of the make-up oil valve is connected to the accumulator.

[0020] The second aspect of the present application provides a work machine, including:

[0021] A boom;

[0022] The electro-hydrostatic actuator system as described above, and the electro-hydrostatic actuator system is arranged on the boom.

[0023] Through the above technical solution, by setting a balance valve and a motor pump, the balance valve includes a first oil port, a second oil port and a control end, and the control end is used to control the balance valve to operate in a first state or a second state. In the first state, the first oil port to the second oil port conducts unidirectionally, and in the second state, proportional throttling is performed between the first oil port and the second oil port; the first end of the motor pump is connected to the first oil port, the second end of the motor pump is connected to the first hydraulic chamber of the hydraulic actuator, and the second oil port is connected to the second hydraulic chamber of the hydraulic actuator. By controlling the control end of the balance valve, when the balance valve operates in the first state, hydraulic oil flows into the first oil port through the first end of the motor pump, flows into the second hydraulic chamber from the second oil port, pushes the hydraulic actuator to move, and the hydraulic oil in the first hydraulic chamber flows into the second end of the motor pump; by controlling the control end of the balance valve, when the balance valve operates in the second state, the hydraulic oil in the second hydraulic chamber flows into the motor pump through the balance valve. By controlling the rotational speed of the motor pump to adjust the system flow rate, the speed adjustment when the balance valve operates in the first state is realized. By adjusting the control pressure and the valve opening of the balance valve, the speed adjustment when the balance valve operates in the second state is realized. The balance valve can precisely control the flow rate of the liquid, thereby realizing precise speed control. By controlling the speed with the balance valve, the liquid flow in the system can be made more stable, reducing system fluctuations and improving the operation stability and reliability of the system. The motor pump has a wide speed regulation range, flexible adjustment of rotational speed acceleration, and is easy to realize smooth and fine movement control.

[0024] Other features and advantages of the embodiments of the present invention will be described in detail in the subsequent specific implementation part. Description of the Drawings

[0025] The drawings are used to provide a further understanding of the embodiments of the present invention, and constitute a part of the specification. Together with the following specific implementation manners, they are used to explain the embodiments of the present invention, but do not constitute a limitation to the embodiments of the present invention. In the drawings:

[0026] Figure 1 Schematically shows the schematic diagram of the electro-hydrostatic actuator system according to an embodiment of the present application;

[0027] Figure 2 Schematically shows the schematic diagram of the electro-hydrostatic actuator system for the luffing of the auxiliary boom of a crane according to an embodiment of the present application;

[0028] Figure 3 Schematically shows another schematic diagram of the electro-hydrostatic actuator system for the luffing of the auxiliary boom of a crane according to an embodiment of the present application.

[0029] Description of the Reference Numerals

[0030] 100 - Motor pump; 200 - Hydraulic actuator; 201 - First hydraulic chamber; 202 - Second hydraulic chamber; 300 - Balance valve; 310 - Spool valve; 320 - First overflow valve; 311 - Control end; 312 - First oil port; 313 - Second oil port; 400 - Accumulator; 500 - On-off valve; 600 - Make-up oil valve; 700 - Second overflow valve; 1 - First motor; 2 - Bidirectional hydraulic pump; 3-1 - Second overflow valve A; 3-2 - Second overflow valve B; 4-1 - First check valve; 4-2 - Second check valve; 5 - Charging check valve; 6 - Charging port; 7 - First accumulator; 8-1 - First balance valve; 8-2 - Second balance valve; 9-1 - First pressure sensor; 9-2 - Second pressure sensor; 9-3 - Third pressure sensor; 9-4 - Fourth pressure sensor; 10-1 - First luffing cylinder; 10-2 - Second luffing cylinder; 11-1 - First explosion-proof valve; 11-2 - Second explosion-proof valve; 12 - Normally open electromagnetic on-off valve; 13 - Power battery; 14-1 - Third luffing cylinder; 14-2 - Fourth luffing cylinder; 15-1 - Third balance valve; 15-2 - Fourth balance valve; 16-1 - Second accumulator; 16-2 - Third accumulator; 17-1 - First hydraulic check valve; 17-2 - Second hydraulic check valve; 17-3 - Third hydraulic check valve; 17-4 - Fourth hydraulic check valve; 18-1 - First fixed-displacement pump; 18-2 - Second fixed-displacement pump; 19-1 - Second motor; 19-2 - Third motor; 20-1 - Third overflow valve; 20-2 - Fourth overflow valve; 20-3 - Fifth overflow valve; 20-4 - Sixth overflow valve; 21-1 - Second normally open electromagnetic switch valve; 21-2 - Third normally open electromagnetic switch valve. Specific embodiments

[0031] The following will describe in detail the specific embodiments of the embodiments of the present invention with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only for the purpose of illustration and explanation of the embodiments of the present invention, and are not used to limit the embodiments of the present invention.

[0032] It should be noted that if there are descriptions involving "first", "second", etc. in the embodiments of the present application, such descriptions of "first", "second", etc. are only for descriptive purposes, and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the fact that those skilled in the art can implement them. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present application.

[0033] Please refer to Figure 1 ,Figure 1 Schematically shown is a schematic diagram of an electro-hydrostatic actuator system according to an embodiment of the present application. This embodiment provides an electro-hydrostatic actuator system, which can be used for remote control operations of various construction machinery. For example, it can be used for the luffing of the jib of a crane. Through the electro-hydrostatic actuator system, the valve-controlled cylinder system of the original jib luffing system can be replaced, eliminating the need for extremely long hydraulic hoses and hose reels, effectively improving the operation efficiency and reliability of the jib luffing system, and reducing the system cost at the same time.

[0034] For the convenience of explaining the solution, this embodiment mainly takes the electro-hydrostatic actuator system used for the luffing of the jib of a crane as an example for illustration. Further, this embodiment mainly takes two hydraulic actuators 200 as an example to explain the solution. This embodiment provides an electro-hydrostatic actuator system, including:

[0035] A hydraulic actuator 200, where the hydraulic actuator 200 includes a first hydraulic chamber 201 and a second hydraulic chamber 202;

[0036] A balance valve 300, where the balance valve 300 includes a first oil port 312, a second oil port 313, and a control end 311. The control end 311 is used to control the balance valve 300 to operate in a first state or a second state. In the first state, the first oil port 312 to the second oil port 313 conducts unidirectionally. In the second state, proportional throttling is performed between the first oil port 312 and the second oil port 313;

[0037] A motor pump 100,

[0038] The first end of the motor pump 100 is connected to the first oil port 312, the second end of the motor pump 100 is connected to the first hydraulic chamber 201, and the second oil port 313 is connected to the second hydraulic chamber 202.

[0039] Through the above technical solution, by setting the balance valve 300 and the motor pump 100, the balance valve 300 includes a first oil port 312, a second oil port 313 and a control end 311. The control end 311 is used to control the balance valve 300 to operate in a first state or a second state. In the first state, the first oil port 312 to the second oil port 313 are unidirectionally conducting. In the second state, proportional throttling is performed between the first oil port 312 and the second oil port 313. The first end of the motor pump 100 is connected to the first oil port 312, the second end of the motor pump 100 is connected to the first hydraulic chamber 201 of the hydraulic actuator 200, and the second oil port 313 is connected to the second hydraulic chamber 202 of the hydraulic actuator 200. By controlling the control end 311 of the balance valve 300, when the balance valve 300 operates in the first state, hydraulic oil flows into the first oil port 312 through the first end of the motor pump 100, flows into the second hydraulic chamber 202 from the second oil port 313, pushes the hydraulic actuator 200 to move, and the hydraulic oil in the first hydraulic chamber 201 flows into the second end of the motor pump 100. By controlling the control end 311 of the balance valve 300, when the balance valve 300 operates in the second state, the hydraulic oil in the second hydraulic chamber 202 flows into the motor pump 100 through the balance valve 300. By controlling the rotation speed of the motor pump 100 to adjust the system flow rate, the speed adjustment when the balance valve 300 operates in the first state is realized. By adjusting the control pressure and the valve opening of the balance valve 300, the speed adjustment when the balance valve 300 operates in the second state is realized, so that stepless speed regulation of the hydraulic actuator 200 can be achieved.

[0040] The balance valve 300 can precisely control the flow rate of the liquid, thereby realizing precise speed control. By controlling the speed through the balance valve 300, the liquid flow in the system can be made more stable, reducing system fluctuations and improving the operation stability and reliability of the system. The motor pump 100 has a wide speed regulation range, flexible adjustment of rotational speed and acceleration, and is easy to achieve stable micro-motion control. By adopting the motor pump 100 and the balance valve 300, closed-loop motor pump 100 volume speed regulation is realized, which helps to achieve stable control of the direction and speed of the hydraulic actuator 200.

[0041] In this embodiment, the above hydraulic actuator 200 can be a hydraulic motor, a hydraulic cylinder, etc. The motor pump 100 is used to convert power into fluid pressure or flow. The pump is driven by an electric motor to operate, and the pump transports the fluid from one position to another. The motor pump 100 includes: a hydraulic pump, and an electric motor connected to the hydraulic pump. The electric motor drives the hydraulic pump to suck and discharge oil, and the hydraulic pump's oil suction and discharge are controlled by adjusting the motor speed. The above hydraulic pump is a two-way hydraulic pump, and the two-way hydraulic pump can be a fixed-displacement pump or a two-way variable-displacement pump. The two-way variable-displacement pump controls the system flow rate through dual variable control of rotational speed and displacement, breaking the limitation of the minimum rotational speed of the fixed-displacement pump, and can further improve the speed regulation range.

[0042] It should be noted that the control end 311 of the balance valve 300 above can be controlled electrically or hydraulically. The structure of the balance valve 300 can be a single spool structure or a multi-spool structure, which is not limited in this embodiment.

[0043] In some embodiments, the balance valve 300 includes a spool 310, and the control end 311 is connected to the second end of the motor pump 100. The spool 310 is driven to move through the control end 311 to control the balance valve 300 to operate in a first state or a second state.

[0044] In this embodiment, the control end 311 is connected to the second end of the motor pump 100, that is, the control end 311 is connected to one end of the hydraulic pump. Thus, the control end 311 of the balance valve 300 is controlled by the hydraulic oil of the hydraulic pump, and the system flow rate and the control pressure of the balance valve 300 are controlled by controlling the motor speed in the motor pump 100, thereby realizing stepless speed regulation. The speed regulation range of the motor is relatively wide, and a motor pump 100 with a wide speed range can be preferably used to improve the micro-mobility of the system.

[0045] In some embodiments, the balance valve 300 further includes a first relief valve 320. The first relief valve 320 is connected between the first oil port 312 and the second oil port 313 and is used to conduct the first oil port 312 and the second oil port 313 when the pressure at the second oil port 313 is greater than a first threshold.

[0046] In this embodiment, by providing the first relief valve 320 between the first oil port 312 and the second oil port 313, pressure is released or reduced when the pressure exceeds the set value to protect the balance valve 300 from the danger of overpressure.

[0047] In some embodiments, the number of the hydraulic actuators 200 and the balance valves 300 is multiple, and one hydraulic actuator 200 is correspondingly connected to one or more balance valves 300.

[0048] In this embodiment, compared with a single hydraulic actuator 200, multiple hydraulic actuators 200 can avoid bearing large side loads and make the system more stable. A balance valve 300 can be provided on one side oil path of the hydraulic actuator 200, that is, one hydraulic actuator 200 is correspondingly connected to one balance valve 300. Adopting the method of connecting one hydraulic actuator 200 to one balance valve 300 can improve the control efficiency and save costs; a balance valve 300 can also be provided on both the oil inlet and oil return side oil paths, that is, one hydraulic actuator 200 is correspondingly connected to multiple balance valves 300, which can improve the working safety and speed regulation accuracy of the hydraulic actuator 200.

[0049] In some embodiments, when there are multiple hydraulic actuators 200, an explosion-proof valve corresponding to each of the multiple hydraulic actuators 200 is further included. The oil inlet of any one of the explosion-proof valves is connected to the second hydraulic chamber 202 of the corresponding hydraulic actuator 200, and the oil outlets of the multiple explosion-proof valves are connected in sequence.

[0050] In this embodiment, please refer to Figure 2 , Figure 2 which schematically shows the schematic diagram of the electro-hydrostatic actuator system for the auxiliary boom luffing of a crane according to an embodiment of the present application. The Z ports of the first explosion-proof valve 11-1 and the second explosion-proof valve 11-2 are respectively connected to the A chambers of the first luffing cylinder 10-1 and the second luffing cylinder 10-2, and the P ports of the first explosion-proof valve 11-1 and the second explosion-proof valve 11-2 are connected to each other. During the luffing process, the A chambers of the first luffing cylinder 10-1 and the second luffing cylinder 10-2 communicate with each other through the first explosion-proof valve 11-1 and the second explosion-proof valve 11-2, so that the flow rates of the two chambers are basically the same, realizing the synchronous action of the two cylinders. In case of emergencies such as pipe bursts, the explosion-proof valve will immediately cut off and lock to avoid safety accidents.

[0051] In the case of multiple hydraulic actuators 200, the synchronous action of the multiple hydraulic actuators 200 is realized through the explosion-proof valve. At the same time, the explosion-proof valve can ensure that the luffing cylinder locks in case of emergencies such as pipe bursts, improving safety.

[0052] In some embodiments, the number of the motor pumps 100 is multiple, and one motor pump 100 is correspondingly connected to one or more hydraulic actuators 200. The above motor pump 100 can control one hydraulic actuator 200 with one motor pump 100, or one motor pump 100 can control multiple hydraulic actuators 200. Using one motor pump 100 to control one hydraulic actuator 200 makes the control more flexible, and using one motor pump 100 to control multiple hydraulic actuators 200 can improve the control efficiency and save costs.

[0053] In some embodiments, an accumulator 400 is further included. The accumulator 400 is connected to the motor pump 100 and is used to supply oil to the motor pump 100.

[0054] In this embodiment, the above accumulator 400 can also be a closed-type pressurized oil tank with the same function. Among them, the accumulator 400 is also connected to the leakage end of the motor pump 100 to ensure the stable flow of the fluid in the system.

[0055] In some embodiments, a switching valve 500 is further included. One end of the switching valve 500 is connected to the accumulator 400, and the other end of the switching valve 500 is connected to the control end 311. The maximum pressure of the accumulator 400 is less than the opening pressure of the control end 311. When the accumulator 400 provides control pressure for the control end 311, the balance valve 300 operates in a first state.

[0056] Considering that the electro-hydrostatic actuator system with the balance valve 300 cannot unload the pressure at the control port of the balance valve 300 after the operation stops, there is a safety hazard. Therefore, a normally open switching valve 500 can be provided between the control port of the balance valve 300 and the accumulator 400, and the maximum pressure of the accumulator 400 is set lower than the opening pressure of the balance valve 300. After the movement of the hydraulic actuator 200 stops, the normally open switching valve 500 is in a conducting state, and the control end 311 of the balance valve 300 is pressure-unloaded through the switching valve 500 to the accumulator 400, so that the balance valve 300 is in the first state, that is, the state where the first oil port 312 conducts unidirectionally to the second oil port 313. From the perspective of the hydraulic actuator 200, its movement can be reliably locked by the balance valve 300, ensuring the safety of the electro-hydrostatic actuator system.

[0057] In this embodiment, the switching valve 500 is a normally open proportional valve or a normally open electromagnetic switching valve 500. The normally open electromagnetic switching valve 500 has the characteristic of closing the valve in the energized state and opening the valve in the de-energized state. The normally open proportional valve controls the control pressure of the balance valve 300 by adjusting the opening of the proportional valve to achieve pressure unloading of the control pressure.

[0058] By providing a normally open proportional valve or a normally open electromagnetic switching valve 500, the switching valve 500 can be conveniently controlled to open or close through energization and de-energization or pilot pressure, so as to unload the control pressure of the balance valve 300.

[0059] Taking the above example as an example, please refer to Figure 2 and Figure 3 , in a scheme where one motor pump 100 controls two hydraulic actuators 200, the normally open end of the normally open electromagnetic switching valve 12 is connected to the first accumulator 7 and the control ports X of the first balance valve 8-1 and the second balance valve 8-2. In a scheme where one motor pump 100 controls one hydraulic actuator 200, the normally open end of the second normally open electromagnetic switching valve 21-1 is connected to the second accumulator 16-1 and the control port X of the third balance valve 15-1. The normally open end of the third normally open electromagnetic switching valve 21-2 is connected to the third accumulator 16-2 and the control port X of the fourth balance valve 15-2.

[0060] By setting the maximum pressure of the accumulator 400 to be less than the opening pressure of the balance valve 300, when the system stops, the normally open switching valve 500 is in the conducting state. The control port of the balance valve 300 is communicated with the oil circuit of the accumulator 400 through the switching valve 500 to realize the unloading of the control pressure. The hydraulic actuator 200 is reliably locked by the balance valve 300. The control pressure of the balance valve 300 in the closed system can be unloaded through the switching valve 500 to realize load holding, thereby ensuring the safety of the electro-hydrostatic actuator system.

[0061] In one embodiment, an oil filling port 6 is further included, and the oil filling port 6 is connected to the accumulator 400.

[0062] In this embodiment, the oil filling port 6 is used to fill hydraulic oil into the system. Specifically, an oil filling check valve 5 may be provided between the oil filling port 6 and the accumulator 400. One end of the oil filling check valve 5 is connected to the accumulator 400, and the other end is connected to the oil filling port 6.

[0063] Please refer to Figure 2 , taking the example of one motor pump controlling two hydraulic actuators, the one-way conducting end of the oil filling check valve 5 is connected to the oil filling port 6, and the one-way cutoff end of the oil filling check valve 5 is connected to the first accumulator 7. The oil filling port 6 and the oil filling check valve 5 are used to fill hydraulic oil into the system. When filling, the oil flows through the oil filling check valve 5, the first check valve 4-1 and the second check valve 4-2 to the two chambers of the first accumulator 7 and the first luffing cylinder 10-1 and the second luffing cylinder 10-2. When the filling stops, the oil filling check valve 5 is reliably closed under the pressure of the first accumulator 7.

[0064] By providing the oil filling port 6, it is convenient to fill the electro-hydrostatic actuator with hydraulic oil during factory production and maintenance.

[0065] In some embodiments, as Figure 1 shown, the electro-hydrostatic actuator system further includes a second relief valve 700 and a make-up valve 600. The second relief valve 700 is connected between the first end and the second end of the motor pump 100. The one-way cutoff end of the make-up valve 600 is connected to the hydraulic actuator 200, and the one-way conducting end of the make-up valve is connected to the accumulator 400.

[0066] In this embodiment, both the second relief valve 700 and the make-up valve 600 may be two, which are respectively arranged on the oil circuits on both the inlet and outlet sides of the hydraulic pump. The make-up valve 600 controls the fluid flow at the two ports of the hydraulic pump to prevent fluid backflow or block the return flow, so as to ensure the directionality and stability of the pipeline system. The second relief valves 700 are respectively located at both ends of the hydraulic pump and are used to release or reduce pressure when the pressure exceeds the set value to protect the equipment and the pipeline system from the risk of overpressure.

[0067] In some embodiments, the hydraulic actuator 200 is a single-rod symmetrical cylinder.

[0068] In this embodiment, the piston rod of the single-rod symmetrical cylinder has only one outlet, and the outlet is symmetric with the center of the piston rod. This design can keep the cylinder balanced during operation, reduce deflection and vibration caused by asymmetric force, and increase the stability and service life of the cylinder.

[0069] By adopting a single-rod symmetrical cylinder, there is almost no volume difference between the two chambers of the cylinder, and only a very small-sized accumulator 400 is required to meet the system flow balance and the function of boosting the suction port of the hydraulic pump.

[0070] Please refer to Figure 2 , taking the example of one motor pump controlling two hydraulic actuators, the first luffing cylinder 10-1 and the second luffing cylinder 10-2 adopt single-rod symmetrical cylinders. There is almost no volume difference between the two chambers compared with single-rod asymmetrical cylinders. Only a small-sized first accumulator 7 is required to achieve system flow balance and boost the suction port of the bidirectional hydraulic pump 2, avoiding a sharp increase in the volume and mass of the boosting oil tank due to a large volume difference, which affects the lifting performance. The minimum pressure of the first accumulator 7 is greater than the opening pressures of the first check valve 4-1 and the second check valve 4-2, and the maximum pressure is less than the shell leakage pressure of the bidirectional hydraulic pump 2 and the opening pressures of the first balance valve 8-1 and the second balance valve 8-2. Ideally, the volumes of the two chambers of the first luffing cylinder 10-1 and the second luffing cylinder 10-2 are exactly equal, and the discharge flow rate of the bidirectional hydraulic pump 2 is equal to the suction flow rate. In actual use, there is always a small volume difference in the luffing cylinders due to factors such as machining and leakage. The first accumulator 7 supplies oil to the suction port of the bidirectional hydraulic pump 2 through the first check valve 4-1 and the second check valve 4-2 to ensure sufficient oil suction of the bidirectional hydraulic pump 2.

[0071] In some embodiments, as Figure 1 shown, pressure sensors are respectively arranged in the first hydraulic chamber 201 and the second hydraulic chamber 202.

[0072] Please refer to Figure 2, taking the example of a motor pump controlling two hydraulic actuators, the first pressure sensor 9-1 and the fourth pressure sensor 9-4 are respectively connected to the A chambers of the first luffing cylinder 10-1 and the second luffing cylinder 10-2, and the second pressure sensor 9-2 and the third pressure sensor 9-3 are respectively connected to the B chambers of the first luffing cylinder 10-1 and the second luffing cylinder 10-2. The pressure sensors further monitor the synchronism and off-load condition of the luffing cylinders by monitoring the pressures in the two chambers of the luffing cylinders. When the pressure difference between the first luffing cylinder 10-1 and the second luffing cylinder 10-2 exceeds the threshold during the luffing process, the luffing is stopped and an alarm is sent to the host. The second relief valve A3-1 and the second relief valve B3-2 are used to limit the maximum system pressure. When the system pressure reaches the set value of the relief valve during the luffing process, the oil is unloaded from the high-pressure side to the low-pressure side to protect the system safety.

[0073] As Figure 1 shown, by respectively arranging pressure sensors in the first hydraulic chamber 201 and the second hydraulic chamber 202, the pressures in the two chambers of the luffing cylinder can be monitored, further monitoring the synchronism and off-load condition of the luffing cylinder, which helps the normal progress of the lifting operation.

[0074] For the convenience of explaining the solution, taking two hydraulic actuators as an example below, the solutions of a motor pump controlling one hydraulic actuator and a motor pump controlling two hydraulic actuators are respectively explained.

[0075] First, please refer to Figure 2 , Figure 2 which schematically shows the schematic diagram of the electro-hydrostatic actuator system for the luffing of the auxiliary boom of a crane according to an embodiment of the present application. In the figure, it is a solution of a motor pump controlling two hydraulic actuators:

[0076] The first motor 1 is connected to the bidirectional hydraulic pump 2 to drive the bidirectional hydraulic pump 2 to rotate. The L end of the bidirectional hydraulic pump 2 is respectively connected to the one-way conduction ends A ports of the first balance valve 8-1 and the second balance valve 8-2. The one-way cut-off ends B ports of the first balance valve 8-1 and the second balance valve 8-2 are connected to the A chambers of the first luffing cylinder 10-1 and the second luffing cylinder 10-2. The R end of the bidirectional hydraulic pump 2 is connected to the control ports X of the first balance valve 8-1 and the second balance valve 8-2 and the B chambers of the first luffing cylinder 10-1 and the second luffing cylinder 10-2. The leakage end of the bidirectional hydraulic pump 2 is connected to the first accumulator 7. The second relief valve A3-1 and the second relief valve B3-2 are respectively connected to the L end and the R end of the bidirectional hydraulic pump 2. The one-way cut-off ends of the first check valve 4-1 and the second check valve 4-2 are respectively connected between the relief valve and the balance valve in the corresponding circuits, and the one-way conduction ends are connected to each other and connected to the first accumulator 7.

[0077] Second, please refer to Figure 3 , Figure 3Schematically shows another schematic diagram of an electro-hydrostatic actuator system for the luffing of the auxiliary boom of a crane according to an embodiment of the present application. The figure shows a scheme where one motor pump controls one hydraulic actuator:

[0078] The balance valve corresponding to the third luffing cylinder 14-1 is the third balance valve 15-1, and the corresponding motor pump includes a second motor 19-1, a first fixed-displacement pump 18-1, a first hydraulic check valve 17-1, a second hydraulic check valve 17-2, a third relief valve 20-1, a fourth relief valve 20-2, and a second accumulator 16-1. The balance valve corresponding to the fourth luffing cylinder 14-2 is the fourth balance valve 15-2, and the corresponding motor pump includes a third motor 19-2, a second fixed-displacement pump 18-2, a third hydraulic check valve 17-3, a fourth hydraulic check valve 17-4, a fifth relief valve 20-3, a sixth relief valve 20-4, and a third accumulator 16-2.

[0079] Among them, the second motor 19-1 is connected to the first fixed-displacement pump 18-1 to drive the first fixed-displacement pump 18-1 to rotate. The L port of the first fixed-displacement pump 18-1 is respectively connected to the unidirectional conduction end A port of the third balance valve 15-1. The unidirectional cut-off end B port of the third balance valve 15-1 is connected to the A chamber of the third luffing cylinder 14-1. The R port of the first fixed-displacement pump 18-1 is connected to the control port X of the third balance valve 15-1 and the B chamber of the third luffing cylinder 14-1. The third relief valve 20-1 and the fourth relief valve 20-2 are respectively connected to the L port and the R port of the first fixed-displacement pump 18-1. The unidirectional cut-off ends of the third hydraulic check valve 17-3 and the fourth hydraulic check valve 17-4 are connected between the relief valve and the balance valve, and the unidirectional conduction ends are connected to each other and connected to the second accumulator 16-1.

[0080] Among them, the third motor 19-2 is connected to the second fixed-displacement pump 18-2 to drive the second fixed-displacement pump 18-2 to rotate. The L port of the second fixed-displacement pump 18-2 is respectively connected to the unidirectional conduction end A port of the fourth balance valve 15-2. The unidirectional cut-off end B port of the fourth balance valve 15-2 is connected to the A chamber of the fourth luffing cylinder 14-2. The R port of the second fixed-displacement pump 18-2 is connected to the control port X of the fourth balance valve 15-2 and the B chamber of the fourth luffing cylinder 14-2. The fifth relief valve 20-3 and the sixth relief valve 20-4 are respectively connected to the L port and the R port of the second fixed-displacement pump 18-2. The unidirectional cut-off ends of the third hydraulic check valve 17-3 and the fourth hydraulic check valve 17-4 are connected between the relief valve and the balance valve, and the unidirectional conduction ends are connected to each other and connected to the third accumulator 16-2.

[0081] It should be noted that the above example is described with two hydraulic actuators as an example. In specific implementation, the number of hydraulic actuators can be set according to actual needs, and this embodiment does not make any limitations.

[0082] Please refer to Figure 2, taking a motor pump controlling two hydraulic actuators as an example, the working process of the electro-hydrostatic actuator system applied to the auxiliary boom luffing system will be described in detail as follows:

[0083] The auxiliary boom luffing mainly includes three actions: lifting, lowering, and stopping. When the boom is lifting, the first motor 1 drives the bidirectional hydraulic pump 2 to rotate clockwise. At this time, the L port of the bidirectional hydraulic pump 2 is the oil discharge port, and the R port is the oil suction port. The pressure oil flows from the L port of the bidirectional hydraulic pump 2 to the A ports of the first balance valve 8-1 and the second balance valve 8-2. At this time, the balance valve conducts unidirectionally, and then flows through the B ports of the first balance valve 8-1 and the second balance valve 8-2 to the A chambers of the first luffing cylinder 10-1 and the second luffing cylinder 10-2. At the same time, the oil in the B chambers of the luffing cylinders flows to the oil suction port R of the bidirectional hydraulic pump 2. The first luffing cylinder 10-1 and the second luffing cylinder 10-2 extend under the pressure difference to achieve boom lifting.

[0084] When the boom is lowering, the normally open electromagnetic switch valve 12 is energized to block the oil circuit between the R port of the bidirectional hydraulic pump 2 and the first accumulator 7. The first motor 1 drives the bidirectional hydraulic pump 2 to rotate counterclockwise. At this time, the R port of the bidirectional hydraulic pump 2 is the oil discharge port, and the L port is the oil suction port. The pressure oil flows from the L port of the bidirectional hydraulic pump 2 to the control ports X of the first balance valve 8-1 and the second balance valve 8-2 and the B chambers of the first luffing cylinder 10-1 and the second luffing cylinder 10-2. By adjusting the rotational speed of the first motor 1, the flow rate of the oil discharge port R of the bidirectional hydraulic pump 2 and the pressure of the control ports X of the first balance valve 8-1 and the second balance valve 8-2 are controlled to control the valve opening of the first balance valve 8-1 and the second balance valve 8-2, and further control the lowering speed of the first luffing cylinder 10-1 and the second luffing cylinder 10-2 to achieve smooth lowering of the auxiliary boom.

[0085] When the boom stops, the first motor 1 stops rotating, and at the same time, the normally open electromagnetic switch valve 12 is de-energized. The control ports of the first balance valve 8-1 and the second balance valve 8-2 communicate with the first accumulator 7 to unload the control pressure and completely close the balance valve to achieve reliable stopping of the luffing cylinder.

[0086] It should be noted that the above description is based on an example of a motor pump controlling two hydraulic actuators. For a scheme of a motor pump controlling one hydraulic actuator, its working process is the same as the above process and will not be elaborated here.

[0087] This embodiment provides a working machine, including: a boom and the above-mentioned electro-hydrostatic actuator system, and the electro-hydrostatic actuator system is arranged on the boom.

[0088] In this embodiment, taking a construction machine as a crane as an example, the above electro-hydrostatic actuator system can be used for the luffing of the jib. By controlling the rotational speed of the motor pump 100, the system flow rate can be adjusted to achieve the adjustment of the luffing and hoisting speeds of the crane. By controlling the rotational speed of the motor pump 100, the control pressure and the valve opening of the balance valve 300 can be adjusted, so as to achieve the adjustment of the lowering speed of the luffing, and further achieve the stepless speed regulation of the hydraulic actuator 200 and the stepless luffing of the system. The motor pump 100 has a wide speed regulation range, flexible adjustment of rotational speed acceleration, and is easy to achieve smooth and fine movement control, improving the fine movement performance of the jib luffing. Compared with the luffing cylinder of the jib that conveys pressure oil from the power source of the lower vehicle to the high altitude through a hydraulic hose nearly 100 meters long, this electro-hydrostatic actuator system eliminates the ultra-long hydraulic hose and the hose reel, improves the working efficiency and reliability of the system, reduces the system cost and weight, reduces the pipeline pressure loss, can increase the working pressure level of the luffing cylinder, reduce the acting area of the luffing cylinder, and further reduce the volume and weight of the luffing cylinder. By adopting the motor pump 100 and the balance valve 300, the volume speed regulation of the motor pump 100 in the closed circuit is realized, which helps to achieve the stable control of the direction and speed of the hydraulic actuator 200. Replacing the long pipeline valve control system with the electro-hydrostatic actuator system reduces the pressure loss, weight and cost of the system, and improves the system response, operation efficiency and operation performance.

[0089] In some embodiments, the construction machine may be a new energy construction machine, including a power battery, such as a lithium battery or a fuel cell, etc., for storing and releasing electric energy for various electric devices to use. The above construction machine may be a crane, a pump truck, an excavator, a fire truck or an electric vehicle, etc. For example, please refer to Figure 2 , the power battery 13 is connected to the first motor 1.

[0090] It should be noted that the above electro-hydrostatic actuator system can also be applied to existing fuel vehicles. For example, the power supply to the motor pump 100 is achieved through the combination of an engine and a generator.

[0091] By connecting the power battery to the motor pump 100 of the electro-hydrostatic actuator system, it is convenient to supply power to the motor pump 100, which helps the normal operation of the electro-hydrostatic actuator system.

[0092] It should also be noted that the term "including", "comprising" or any other variation thereof is intended to cover non-exclusive inclusion, so that a process, method, commodity or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or also includes elements inherent to this process, method, commodity or equipment. Without further limitation, an element defined by the statement "including one..." does not exclude the existence of another identical element in the process, method, commodity or equipment including the element.

[0093] The above are only embodiments of the present application and are not intended to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the scope of the claims of the present application.

Claims

1. An electrostatic hydraulic actuator system, characterized in that: include: A hydraulic actuator, the hydraulic actuator comprising a first hydraulic chamber and a second hydraulic chamber; A balancing valve, the balancing valve comprising a first oil port, a second oil port and a control end, the control end being used to control the balancing valve to operate in a first state or a second state, in which the first oil port is unidirectionally connected to the second oil port, and in which the first oil port and the second oil port are proportionally throttled in the second state; Motor pump, The first end of the motor pump is connected to the first oil port, the second end of the motor pump is connected to the first hydraulic chamber, and the second oil port is connected to the second hydraulic chamber.

2. The electrostatic hydraulic actuator system according to claim 1, characterized in that: There are multiple hydraulic actuators and balancing valves, and one hydraulic actuator is correspondingly connected to one or more balancing valves.

3. The electrostatic hydraulic actuator system according to claim 1, characterized in that: There are multiple motor pumps, and one motor pump is correspondingly connected to one or more hydraulic actuators.

4. The electrostatic hydraulic actuator system according to claim 2, characterized in that: It also includes explosion-proof valves corresponding to the plurality of hydraulic actuators respectively, the oil inlet of any explosion-proof valve is connected to the second hydraulic chamber of the corresponding hydraulic actuator, and the oil outlets of the plurality of explosion-proof valves are connected in sequence.

5. The electrostatic hydraulic actuator system according to claim 1, characterized in that: It also includes an accumulator, which is connected to the motor pump and is used to replenish oil to the motor pump.

6. The electrostatic hydraulic actuator system according to claim 5, characterized in that: It also includes a switch valve, one end of which is connected to the accumulator, and the other end of which is respectively connected to the second end of the motor pump and the first hydraulic chamber.

7. The electrostatic hydraulic actuator system according to claim 6, characterized in that: The other end of the switch valve is also connected to the control end. The maximum pressure of the accumulator is less than the opening pressure of the control end. When the accumulator provides control pressure to the control end, the balance valve works in the first state.

8. The electrostatic hydraulic actuator system according to claim 5, characterized in that: It also includes an oil filling port, which is connected to the accumulator.

9. The electrostatic hydraulic actuator system according to claim 1, characterized in that: The balancing valve comprises a valve core, the control end is connected to the second end of the motor pump, and the valve core is driven to move by the control end to control the balancing valve to work in the first state or the second state.

10. The electrostatic hydraulic actuator system according to claim 1, characterized in that: The balancing valve further includes a first overflow valve, which is connected between the first oil port and the second oil port and is used to connect the first oil port and the second oil port when the pressure of the second oil port is greater than a first threshold.

11. The electrostatic hydraulic actuator system according to claim 5, characterized in that: It also includes a second overflow valve and an oil replenishing valve, wherein the second overflow valve is connected between the first end and the second end of the motor pump, the one-way cut-off end of the oil replenishing valve is connected to the hydraulic actuator, and the one-way conducting end of the oil replenishing valve is connected to the accumulator.

12. A working machine, characterized in that: include: Boom; The electrostatic hydraulic actuator system according to any one of claims 1 to 11, wherein the electrostatic hydraulic actuator system is arranged on the arm.

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