A five-cavity series-symmetrical single-rod electrostatic actuator and its working method

Abstract

The present invention discloses a five-cavity, series-connected, symmetrical, single-rod electrostatic hydraulic actuator and its working method. The actuator includes a dual controller, a dual motor pump unit, and a five-cavity, series-connected, symmetrical single-rod actuator. The actuator cylinder body is provided with ports A, B, C, D, and two T ports. Ports A and B are connected to the hydraulic pump of the first motor pump unit, ports C and D are connected to the hydraulic pump of the second motor pump unit, and the two T ports are connected to the external air. The piston forms three working chambers of equal area and two air chambers between the cylinder body and the inner cylinder barrel, achieving the same force area when extending (oil inlet from ports A / C) and retracting (oil inlet from ports B / D). Both dual motor pump units include bypass valves. When a single unit fails, the bypass valve isolates the faulty oil circuit, and the other unit maintains drive. The present invention compresses the axial size through a five-cavity, symmetrical, single-rod structure, and improves reliability by combining a dual-unit redundant design. It is suitable for electrostatic hydraulic actuator applications with stringent requirements on size and life.

Description

Technical Field

[0001] The present invention relates to the technical field of hydraulic transmission and control, in particular to the technical field of a five-cavity series-connected symmetrical single-rod electrostatic hydraulic actuator and a working method thereof. Background Art

[0002] Electro-Hydrostatic Actuators (EHAs), distributed drive devices integrating servo motors and hydraulic pumps, have recently been widely adopted in flight control systems for high-end aircraft, including large passenger aircraft and advanced fighter jets. Compared to traditional centralized hydraulic systems, EHAs eliminate long hydraulic lines by using localized drive and accumulator energy supply. This significantly improves system safety, reliability, and maintainability, while effectively reducing overall weight. EHAs have become a key development direction for aircraft control surface control systems.

[0003] However, the existing electrostatic hydraulic actuator technology still has the following shortcomings:

[0004] 1. Contradiction between structural size and power density:

[0005] The current mainstream solution adopts a symmetrical double-rod actuator structure. Although it can maintain the bidirectional force balance of the piston, its axial dimension is large, resulting in low power density, which makes it difficult to meet application scenarios with higher requirements for compactness.

[0006] 2. Flow imbalance problem of single-rod solution:

[0007] Although some solutions using a single-rod actuator can reduce the volume, due to the unequal effective areas on both sides of the piston, a complex flow compensation mechanism must be additionally configured. This not only increases system complexity but also easily leads to reduced control accuracy and asymmetric response.

[0008] 3. Insufficient reliability redundancy:

[0009] Existing systems mostly rely on a single motor pump unit for drive. Once this unit fails, the entire actuator will be paralyzed, making it difficult to meet the fault tolerance requirements of high-safety scenarios such as flight control systems.

[0010] Therefore, there is an urgent need to develop a new type of electrostatic hydraulic actuator that can significantly improve power density and fault tolerance while ensuring bidirectional thrust symmetry and control accuracy, so as to meet the increasingly stringent requirements for actuator compactness and reliability in fields such as aviation and heavy-duty machinery. Summary of the Invention

[0011] The purpose of the present invention is to solve the problems of insufficient power density and low reliability of the electrostatic hydraulic actuator system in the prior art, and to propose a five-cavity series symmetrical single-rod electrostatic hydraulic actuator and its working method, which can significantly shorten the axial dimension of the actuator cylinder while ensuring the same bidirectional force area of ​​the piston. At the same time, fault isolation and redundant control are achieved through the coordination of the dual motor pump unit and the bypass valve, thereby improving the system integration and reliability.

[0012] To achieve the above-mentioned object, the present invention proposes a five-cavity series-connected symmetrical single-rod electrostatic hydraulic actuator, comprising a dual controller, a dual motor pump unit, and a five-cavity series-connected symmetrical single-rod actuator cylinder;

[0013] The dual motor pump units are a first motor pump unit and a second motor pump unit, each motor pump unit including a motor, a hydraulic pump, an accumulator, two one-way valves, two overflow valves and a bypass valve;

[0014] The five-chamber series-connected symmetrical single-rod actuator comprises a cylinder body, an inner cylinder, an intermediate seat, a cylinder body end cover and a piston;

[0015] in:

[0016] The dual controllers are electrically connected to the two motors respectively;

[0017] The cylinder body is sealed with the cylinder end cover, and the inner cylinder barrel and the middle seat are fixed in the center of the cylinder body;

[0018] The piston is located between the cylinder body and the inner cylinder barrel, and forms a sealed sliding fit with the cylinder body, the inner cylinder barrel, the intermediate seat and the cylinder body end cover;

[0019] The cylinder body is provided with port A, port B, port C, port D and two T ports;

[0020] Ports A and B are connected to the hydraulic pump suction and discharge ports of the first motor pump unit respectively, and ports C and D are connected to the hydraulic pump suction and discharge ports of the second motor pump unit respectively;

[0021] The two T ports are connected to the outside air to compensate for the volume change caused by the piston movement and balance the volume difference inside the actuator;

[0022] When oil is supplied to ports A and C at the same time, the piston extends; when oil is supplied to ports B and D at the same time, the piston retracts, and the force area of ​​the piston when extending and retracting is the same.

[0023] Preferably, the dual-motor pump unit is two sets of units with the same structure; the motor is a permanent magnet synchronous motor; and the hydraulic pump is a bidirectional hydraulic pump having an oil suction port and an oil discharge port.

[0024] Preferably, in each motor pump unit, the oil inlets of the two one-way valves are connected to the accumulator, and the oil outlets are respectively connected to the oil suction port and the oil discharge port of the hydraulic pump.

[0025] Preferably, in each motor pump unit, both ends of the two relief valves are connected to the oil suction and discharge ports of the hydraulic pump respectively, and the conduction directions of the two relief valves are opposite.

[0026] Preferably, in each motor pump unit, both ends of the bypass valve are connected to the oil suction port and the oil discharge port of the hydraulic pump respectively.

[0027] Preferably, five chambers are formed inside the actuator:

[0028] The first working chamber is surrounded by the inner cylinder and the piston, and is connected to ports A and C; the second working chamber is surrounded by the cylinder body, the inner cylinder, the middle seat and the piston, and is connected to port B; the third working chamber is surrounded by the cylinder body and the piston, and is connected to port D; the two air chambers are surrounded by the cylinder body, the inner cylinder, the middle seat and the piston, and are respectively connected to the two T ports; the effective working area of ​​the first working chamber is I, the effective working area of ​​the second working chamber is II, and the effective working area of ​​the third working chamber is III.

[0029] Furthermore, the hydraulic oil acts on area I of the first working chamber, area II of the second working chamber, and area III of the third working chamber, satisfying the following relationship: area I = area II = area III.

[0030] Preferably, a bushing is installed at one end of the piston, the center of the inner end of the bushing is connected to the plug rod, and the plug rod fixes the magnetic ring; the cylinder body is installed with a displacement sensor, and the magnetic ring is sleeved on the outside of the displacement sensor to form a non-contact detection structure.

[0031] Preferably, the cylinder end cover is provided with a damping hole connecting the D port and the third working chamber; when the piston is extended to the limit position, the piston blocks the D port, and the hydraulic oil flows into the third working chamber through the damping hole to push the piston to retract.

[0032] The cylinder body is equipped with ports A, B, C, D, and two T ports. Ports A and B are connected to the suction and discharge ports of hydraulic pump 1, respectively, while ports C and D are connected to the suction and discharge ports of hydraulic pump 2, respectively. The two T ports communicate with the air chamber within the cylinder body, balancing pressure differences caused by internal volume changes during actuation. Hydraulic oil from ports A and C enters the first working chamber, acting on area I. Hydraulic oil from ports B and D enters the second and third working chambers, acting on areas II and III, respectively. When oil is flowing through ports A and C and returning through ports B and D, high-pressure oil acts on area I and low-pressure oil acts on areas II and III, extending the piston and achieving the actuator's extension. Conversely, when oil is flowing through ports B and D and returning through ports A and C, hydraulic oil retracts the piston, retracting the actuator. Due to the five-chamber design and symmetrical arrangement, the piston's effective area is consistent in both extension and retraction directions, achieving symmetrical thrust and smooth motion.

[0033] A method for operating the electrostatic hydraulic actuator according to any one of the above items, comprising:

[0034] Normal drive mode: When the piston extends, the dual controller controls the first and second motor pump units to supply oil to ports A and C respectively, and return oil to ports B and D, while the two T ports inhale air; when the piston retracts, the dual controller controls the first and second motor pump units to supply oil to ports B and D respectively, and return oil to ports A and C, while the two T ports exhaust air;

[0035] Fault-tolerant mode: When a single motor pump unit fails, its bypass valve opens to isolate the faulty oil circuit, and the other motor pump unit independently drives the actuator to move.

[0036] Beneficial effects of the present invention:

[0037] 1. Significantly improved fault redundancy capabilities:

[0038] Through the collaborative design of the dual-motor pump unit and the bypass valve, when a single unit fails, the bypass valve automatically isolates the faulty oil circuit, and the remaining units can independently drive the piston movement, greatly improving system reliability and meeting the fault tolerance requirements of high-safety scenarios such as aviation flight control.

[0039] 2. Effective compression of axial dimensions:

[0040] The five-chamber series symmetrical single-rod actuator structure is adopted. While ensuring the same bidirectional force area of ​​the piston, the axial length is only half of the traditional symmetrical double-rod structure, which significantly improves the power density and solves the problem of installation in a compact space.

[0041] 3. Optimization of motion smoothness:

[0042] The cylinder end cover is provided with a damping hole to form a buffer oil path when the piston moves to the extreme position, thereby avoiding jamming or reverse failure caused by rigid impact and enhancing the end positioning accuracy and service life.

[0043] 4. Compatible with standard hydraulic components:

[0044] The actuator's oil flow inlet and outlet are well symmetrical and can be directly matched with an industrial standard bidirectional hydraulic pump, eliminating the need for customized design and reducing the difficulty and cost of system implementation.

[0045] 5. Strong application adaptability:

[0046] It has the comprehensive advantages of compact structure, symmetrical thrust and high fault tolerance, and is particularly suitable for fields with strict requirements on size and reliability, such as aircraft control and heavy machinery actuation.

[0047] The features and advantages of the present invention will be described in detail through embodiments with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 This is a schematic diagram of a five-cavity series-connected symmetrical single-rod electrostatic hydraulic actuator and its working method according to the present invention;

[0049] Figure 2 This is a schematic diagram of the oil circuit when the piston of the actuator cylinder of the five-cavity series-connected symmetrical single-rod electrostatic hydraulic actuator and its working method is extended;

[0050] Figure 3 This is a schematic diagram of the oil circuit when the piston of the actuator cylinder of the five-cavity series-connected symmetrical single-rod electrostatic hydraulic actuator and its working method is retracted;

[0051] Figure 4 The present invention is a schematic structural diagram of a five-cavity series-connected symmetrical single-rod electrostatic hydraulic actuator and a working method thereof.

[0052] In the figure: 1-controller, 2-motor, 3-pump, 4-accumulator, 5-check valve, 6-relief valve, 7-bypass valve, 8-five-chamber series symmetrical single-rod actuator, 81-displacement sensor, 82-cylinder body, 83-insert rod, 84-piston, 85-cylinder body end cover, 86-piston end cover, 87-inner cylinder, 88-middle seat, 9-air. DETAILED DESCRIPTION

[0053] See Figure 1 、 Figure 2 、 Figure 3 and Figure 4The electrostatic hydraulic actuator of the present invention includes a dual controller, a dual motor pump unit and a five-chamber serial symmetrical single-rod actuator cylinder; the dual motor pump unit is a first motor pump unit and a second motor pump unit, each motor pump unit includes a motor, a hydraulic pump, an accumulator, two one-way valves, two overflow valves and a bypass valve; the five-chamber serial symmetrical single-rod actuator cylinder includes a cylinder body, an inner cylinder, an intermediate seat, a cylinder end cover and a piston; wherein: the dual controllers are electrically connected to the two motors respectively; the cylinder body is sealed with the cylinder end cover, and the inner cylinder and the intermediate seat are fixed to the inner center of the cylinder body; the piston is located in the cylinder body A sealed sliding fit is formed between the inner cylinder, and with the cylinder body, the inner cylinder, the middle seat and the cylinder end cover; the cylinder body is provided with port A, port B, port C, port D and two T ports; port A and port B are respectively connected to the hydraulic pump suction and discharge ports of the first motor pump unit, and port C and port D are respectively connected to the hydraulic pump suction and discharge ports of the second motor pump unit; the two T ports are connected to the external air to compensate for the volume change caused by the piston movement and balance the internal volume difference of the actuator cylinder; when oil is supplied to ports A and C at the same time, the piston extends; when oil is supplied to ports B and D at the same time, the piston retracts, and the force area of ​​the piston is the same when extending and retracting.

[0054] The working method of the present invention comprises:

[0055] Normal drive mode: When the piston extends, the dual controller controls the first and second motor pump units to supply oil to ports A and C respectively, and return oil to ports B and D, while the two T ports inhale air; when the piston retracts, the dual controller controls the first and second motor pump units to supply oil to ports B and D respectively, and return oil to ports A and C, while the two T ports exhaust air;

[0056] Fault-tolerant mode: When a single motor pump unit fails, its bypass valve opens to isolate the faulty oil circuit, and the other motor pump unit independently drives the actuator to move.

[0057] Working process of the present invention:

[0058] The five-cavity series-connected symmetrical single-rod electrostatic hydraulic actuator and its working method are described in conjunction with the accompanying drawings during operation.

[0059] Example 1:

[0060] like Figure 1-4 As shown, this embodiment provides a five-chamber, symmetrical, single-rod electrostatic actuator, primarily comprising dual controllers, a dual motor-pump unit, and a five-chamber, symmetrical, single-rod actuator cylinder. The motor-pump unit comprises a motor, a hydraulic pump, a check valve, a relief valve, and a bypass valve. The controller is electrically connected to the motor, and the motor output shaft drives the hydraulic pump via a coupling.

[0061] The motor is a permanent magnet synchronous motor, and the hydraulic pump is a bidirectional, reversible pump with an oil intake and an oil discharge port. The oil inlets of the two check valves are connected to the accumulator, and the oil outlets are connected to the hydraulic pump's oil intake and discharge ports, respectively. Each relief valve has two ends connected to the hydraulic pump's oil intake and discharge ports. The two relief valves conduct in opposite directions and are set to open at a pressure higher than the system's maximum operating pressure. This serves to relieve excessive pressure in abnormal situations and protect the system. Ports A and B of the hydraulic pump can alternately serve as the oil intake and discharge ports, depending on operating conditions.

[0062] The working principle of the motor pump hydraulic system is: the motor converts electrical energy into mechanical energy to drive the hydraulic pump to rotate, and the hydraulic pump converts mechanical energy into hydraulic energy and delivers pressurized liquid to the actuator, realizing the conversion of hydraulic energy into mechanical output.

[0063] The bypass valve is arranged between the oil suction and discharge passages of the hydraulic pump and is used to open the passage when a motor pump unit fails, isolating the faulty system, thereby ensuring that the other motor pump unit can independently drive the actuator, thereby enhancing the system redundancy capability.

[0064] To achieve high-precision control, the system is equipped with multiple sensors: pressure sensors are installed in the A and B pipelines, a resolver and current sensor are installed in the motor, and a displacement sensor is located inside the actuator. The controller calculates the position command signal and adjusts the motor speed to control the hydraulic pump flow rate, thereby controlling the piston position. The displacement, current, pressure, and motor angle signals fed back by the sensors are used for real-time closed-loop control.

[0065] The above configuration and principle introduction are all for a single motor pump unit configuration. The configuration and principle of the two motor pump units are the same and will not be described in detail here.

[0066] The five-chamber, symmetrical, single-rod actuator comprises a cylinder body, an inner cylinder, an intermediate seat, a cylinder end cap, and a piston assembly. The cylinder body and end cap are sealed together, and the inner cylinder is mounted on the central axis of the cylinder body. The piston is located between the cylinder body and the inner cylinder, forming a sealed, sliding fit with the cylinder body, inner cylinder, and end cap.

[0067] The cylinder body is equipped with ports A, B, C, D, and two T ports for the intake and exhaust of hydraulic oil and air, respectively. Ports A and B connect to the suction and discharge ports of the first motor pump unit, while ports C and D connect to the second motor pump unit. When oil is supplied to ports A and C simultaneously, the piston extends; when oil is supplied to ports B and D, the piston retracts.

[0068] The five-chamber actuator consists of three working chambers and two air chambers. The first working chamber, formed by the inner cylinder and piston, has hydraulic oil acting on area I. The second working chamber, encompassed by the inner cylinder, piston, cylinder body, and intermediate seat, covers area II. The third working chamber, formed by the cylinder body and piston, covers area III. The air chamber is connected to the outside world through a T-port to balance pressure fluctuations within the chamber and maintain smooth system operation.

[0069] One end of the piston is fitted with a bushing, connected to a ball joint. The center of the bushing's inner end is threaded with a rod, which in turn connects to a magnetic ring. A displacement sensor is threaded into the ring, enabling contactless displacement detection. A connector with a built-in spherical bearing is mounted on one end of the cylinder body for docking with external mechanisms.

[0070] The piston includes a piston rod and a plug body. The plug body is in a sealed sliding fit with the annular inner wall of the cylinder body and the annular outer wall of the inner cylinder barrel to ensure that the hydraulic oil does not leak. The magnetic ring has a central hole extending therethrough, and the annular outer wall and the annular inner wall of the inner cylinder barrel are in a clearance fit to ensure smooth movement.

[0071] The end cap of the actuator cylinder body features a damping hole, creating a damped oil return path when the piston reaches its limit, mitigating end-of-stroke impact and preventing overshoot. When oil enters port D, it flows through the damping hole and acts on the bottom surface of the piston body, causing the piston to reverse direction and return to its original position.

[0072] During the movement of the actuator: when oil is supplied from ports A and C and oil is returned from ports B and D, high-pressure hydraulic oil enters the first working chamber, pushing the piston to extend, low-pressure oil returns from the second and third working chambers, and air enters through port T to replenish the space in the chamber; when oil is supplied from ports B and D and oil is returned from ports A and C, the piston retracts.

[0073] The three working areas I, II, and III enclosed by the inner cylinder, piston, intermediate seat, and cylinder body are equal. The cylinder body is equipped with ports A, B, C, D, and two T ports. Ports A and B are connected to the suction and discharge ports of the first motor pump unit, respectively, while ports C and D are connected to the suction and discharge ports of the second motor pump unit, respectively. The two T ports communicate with the air chamber within the cylinder body and are used to balance the pressure differences caused by changes in internal volume during actuation. Hydraulic oil from ports A and C enters the first working chamber, acting on area I; hydraulic oil from ports B and D enters the second and third working chambers, acting on areas II and III, respectively.

[0074] The structural design of three hydraulic action areas I=II=III ensures thrust symmetry and movement stability throughout the entire actuation process, meeting the strict requirements of high-performance flight control systems for actuator response consistency and structural compactness.

[0075] The working principle of the five-chamber series-symmetrical single-rod actuator of the present invention is: when the actuator is extended, the oil enters the first working chamber from ports A and C and acts on area I to extend the piston, the oil in the second working chamber and the third working chamber is discharged from ports B and D, and the two air chambers suck in air from the two T ports; when the actuator is retracted, the oil enters the second working chamber and the third working chamber from ports B and D and retracts the piston by acting on areas II and III, the oil in the first working chamber is discharged from ports A and C, and the two air chambers discharge air from the two T ports.

[0076] The above embodiments are intended to illustrate the present invention, not to limit the present invention. Any solution that is a simple transformation of the present invention falls within the protection scope of the present invention.

Claims

1. A five-chamber, series-connected, symmetrical, single-rod electrostatic hydraulic actuator, characterized by: It includes dual controllers, dual motor pump units and five-chamber series symmetrical single-rod actuators; The dual motor pump unit is a first motor pump unit and a second motor pump unit; each motor pump unit includes a motor, a hydraulic pump, an accumulator, two one-way valves, two overflow valves and a bypass valve; The five-chamber series-connected symmetrical single-rod actuator comprises a cylinder body, an inner cylinder, an intermediate seat, a cylinder body end cover and a piston; in: The dual controllers are electrically connected to the two motors respectively; The cylinder body is sealed with the cylinder end cover, and the inner cylinder barrel and the middle seat are fixed in the center of the cylinder body; The piston is located between the cylinder body and the inner cylinder barrel, and forms a sealed sliding fit with the cylinder body, the inner cylinder barrel, the intermediate seat and the cylinder body end cover; The cylinder body is provided with port A, port B, port C, port D and two T ports; Ports A and B are connected to the hydraulic pump suction and discharge ports of the first motor pump unit respectively, and ports C and D are connected to the hydraulic pump suction and discharge ports of the second motor pump unit respectively; The two T ports are connected to the outside air to balance the volume difference inside the actuator; When oil is supplied to ports A and C at the same time, the piston extends; when oil is supplied to ports B and D at the same time, the piston retracts, and the force area of ​​the piston when extending and retracting is the same; Five chambers are formed inside the actuator cylinder: the first working chamber is surrounded by the inner cylinder and the piston, and is connected to ports A and C; the second working chamber is surrounded by the cylinder body, the inner cylinder, the middle seat and the piston, and is connected to port B; the third working chamber is surrounded by the cylinder body and the piston, and is connected to port D; two air chambers are surrounded by the cylinder body, the inner cylinder, the middle seat and the piston, and are respectively connected to two T ports; among them, the effective working area I of the first working chamber, the effective working area II of the second working chamber and the effective working area III of the third working chamber are equal.

2. The electrostatic hydraulic actuator according to claim 1, characterized in that: The dual-motor pump unit is two sets of units with the same structure; the motor is a permanent magnet synchronous motor; the hydraulic pump is a bidirectional hydraulic pump with an oil suction port and an oil discharge port.

3. The electrostatic hydraulic actuator according to claim 1, characterized in that: In each motor pump unit, the oil inlets of the two one-way valves are connected to the accumulator, and the oil outlets are respectively connected to the oil suction port and the oil discharge port of the hydraulic pump.

4. The electrostatic hydraulic actuator according to claim 1, characterized in that: In each motor pump unit, two ends of the two relief valves are respectively connected to the oil suction and discharge ports of the hydraulic pump, and the conduction directions of the two relief valves are opposite.

5. The electrostatic hydraulic actuator according to claim 1, characterized in that: In each motor pump unit, two ends of the bypass valve are respectively connected to the oil suction port and the oil discharge port of the hydraulic pump.

6. The electrostatic hydraulic actuator according to claim 1, characterized in that: A bushing is installed at one end of the piston, the center of the inner end of the bushing is connected to the plug rod, and the plug rod fixes the magnetic ring; the cylinder body is installed with a displacement sensor, and the magnetic ring is sleeved on the outside of the displacement sensor to form a non-contact detection structure.

7. The electrostatic hydraulic actuator according to claim 1, characterized in that: The cylinder end cover is provided with a damping hole connecting the D port and the third working chamber; when the piston is extended to the limit position, the piston blocks the D port, and the hydraulic oil flows into the third working chamber through the damping hole to push the piston to retract.

8. A method for operating the electrostatic hydraulic actuator according to any one of claims 1 to 7, characterized in that include: Normal drive mode: When the piston extends, the dual controller controls the first and second motor pump units to supply oil to ports A and C respectively, and return oil to ports B and D, while the two T ports inhale air; when the piston retracts, the dual controller controls the first and second motor pump units to supply oil to ports B and D respectively, and return oil to ports A and C, while the two T ports exhaust air; Fault-tolerant mode: When a single motor pump unit fails, its bypass valve opens to isolate the faulty oil circuit, and the other motor pump unit independently drives the actuator to move.

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