JPH0578685B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a closed-circuit electro-hydraulic actuator package, and is particularly applicable to control surface control actuators for aircraft flight control systems, as well as general industrial equipment, robots, etc. The present invention relates to a closed-circuit electro-hydraulic actuator package that can also be applied to power packages.

[Prior art]

The circuit configuration of a conventional electro-hydraulic actuator package is shown in FIG. That is, a reversible hydraulic pump 2 driven by a DC servo motor 1 is provided, and the pump 2 is connected to the actuator main body 3 via oil passages 4A and 4B. The actuator body 3 has a piston 6 built into the cylinder 5 to define a pair of hydraulic chambers 7A and 7B, and an actuation rod 8 integrated with the piston 6.
is caused to reciprocate by the pressure difference between the hydraulic chambers 7A and 7B. For this reason, the discharge side port of the pump 2 during forward rotation is connected to one hydraulic chamber 7A via the first oil passage 4A, and the discharge side port during reverse rotation is connected to the other hydraulic pressure chamber 7A via the second oil passage 4B. It is connected to chamber 7B to form a closed circuit. Also, the first and second
An accumulator 9 is provided in order to introduce initial pressure into the oil passages 4A and 4B to maintain the stiffness of the actuator when it is in the neutral state. The accumulator 9 is divided into an oil chamber 11 and a gas chamber 12 by a piston 10, and the gas chamber 12 is filled with gas. There is. First and second oil passages 4A, 4B and oil chamber 1
1, the main introduction oil passage 13 that opens into the oil chamber 11 is branched, one branch first oil passage 13A is communicated with the first oil passage 4A, and the other branch second oil passage 13 is connected to the first oil passage 4A.
B is communicated with the second oil passage 4B. Check valves 14 are installed in the branch oil passages 12A and 13B.
A and 14B are interposed to prevent circuit pressure on the high pressure side (pump discharge side) from acting on the accumulator 9 side. Therefore, when the pump 2 rotates normally, the first oil passage 4A becomes the pump discharge pressure and acts on one hydraulic chamber 7A of the actuator main body 3, and the other hydraulic chamber 7B is supplied with the accumulator 9 through the second oil passage 4B. Since the pressure inside the gas chamber 12 of
The pressure difference (difference between the pump discharge pressure and the gas pressure) at 7B allows the control surface to be controlled by moving in the forward direction.

Note that an oil passage 15 connecting to the accumulator oil chamber 11 is opened so that the set pressure of the accumulator 9 acts inside the case of the pump 2 to maintain a low pressure. Further, a drive signal to the DC servo motor 1 is inputted through an amplifier 16 and a controller 17, and a detection signal from a position displacement detector 18 provided in the actuator body 9 is inputted to the controller 17 through the amplifier 16 to perform position correction. It is configured as follows. In the figure, 19 is a tachometer generator attached to the motor 1, and 20A and 20B are circuit protection relief valves.

[Problem that the invention seeks to solve]

However, with conventional closed-circuit electro-hydraulic actuator packages, it is not possible to maintain a large effective differential pressure across the piston of the actuator body, and the pressure is controlled only on one side of the actuator body, so the problem is that the rigidity of the actuator body is low. It was hot. In other words, the pressure characteristics in the conventional configuration are
As shown in Fig. 5, when the actuator body is not in operation, the gas pressure of the accumulator 9 is maintained at a constant initial pressure in the first and second oil passages 4A and 4B.
It acts as Po. Now, when the pump 2 is rotated forward from the neutral position (input "0"), the first oil passage 4
The internal pressure of A becomes the pump discharge pressure, and the solid line A in Figure 5
stand up like The differential pressure between this pressure and the initial pressure Po is an effective differential pressure that becomes the driving pressure of the actuator body 3. When pump 2 rotates in reverse, the dashed line B in the same figure
As expected, the difference from the initial pressure Po becomes the effective differential pressure. Therefore, in order to increase the effective differential pressure, it is necessary to lower the initial pressure or increase the capacity of the pump 2, but if the initial pressure is lowered, the actuator body 3 cannot maintain its rigidity due to the external force, and the pump capacity decreases. There is a problem in that an increase in the size of the device results in an increase in size and weight.

The present invention has focused on the above-mentioned conventional problems, and aims to provide a compact closed-circuit electro-hydraulic actuator package that can improve actuator rigidity and increase effective differential pressure.

[Means and actions for solving problems]

To achieve this object, the present invention includes an actuator body having two hydraulic chambers partitioned by a piston, a reversible pump that is the actuating main body of the actuator body, and an oil discharge side of the pump when the pump rotates forward. a first oil passage connecting the supply/discharge port and one of the hydraulic chambers; and a second oil passage connecting the supply/discharge port, which becomes the oil discharge side of the pump when the pump rotates in reverse, and the other hydraulic chamber. a closed circuit having an oil passage, an oil chamber divided into two by a common piston, and a gas chamber filled with gas that provides the initial pressure of the actuator body by pressing the common piston; The circuit pressure of the closed circuit is introduced into each of the divided chambers of the accumulator from each of the two oil passages, and the pressure receiving area of each of the divided chambers of the accumulator is the same as the area ratio of both hydraulic chambers of the actuator body. Circuit electro-hydraulic actuator package.

With this configuration, the two divided chambers of the accumulator are separated by a common piston, and
Since the pressure receiving area of each of the divided chambers of the accumulator is in the same ratio as the area ratio of both hydraulic chambers of the actuator body, when the first and second oil passages are at the same pressure, the gas in the gas chamber of the accumulator causes the common piston is pressed, and the two hydraulic chambers of the actuator are maintained at the same initial pressure via the first and second oil passages.

By forward rotation (reverse rotation) of the reversible pump, the first
The (second) oil passage pressure increases, and the second (first) oil passage pressure decreases. As a result, one of the two hydraulic chambers of the actuator has a low pressure and the other has a high pressure. The divided chambers of the accumulator main body are partitioned by a common piston, and the divided chamber of the accumulator on the side where the first (second) oil passage pressure is introduced has a higher pressure than the initial pressure, and the second (first) oil passage pressure is higher than the initial pressure. The pressure in the divided chamber on the side where the path pressure is introduced becomes lower than the initial pressure because the pressure in the other divided chamber becomes higher than the initial pressure, and the two pressures are balanced by the pressure balance in the accumulator. However, the two divided chambers are separated by a common piston, and the pressure receiving area of each of the divided chambers of the accumulator is the same as the area ratio of both hydraulic chambers of the actuator body, so the pressures in the two divided chambers are different. However, the pressure applied to the common piston from the two divided chambers is always constant, and the gas pressure in the gas chamber and the common piston pressure are always balanced.

Therefore, the effective differential pressure of the actuator body is the differential pressure between the reversible pump discharge pressure and the pressure decreasing from the initial pressure, and the initial pressure can be maintained high even though the effective differential pressure can be increased.

[Embodiments of the invention]

Embodiments of the closed circuit electro-hydraulic actuator according to the present invention will be described in detail below with reference to FIGS. 1 to 3. FIG. 1 is a circuit diagram of a closed circuit electro-hydraulic actuator package according to an embodiment. This actuator power package includes an amplifier 30 and a DC servo motor 32 to which a drive command signal is input through a controller 31, and uses the motor 32 as a drive source to rotate a constant discharge type reversible hydraulic pump 33. The pump 33 has two suction and discharge ports, and both suction and discharge ports are connected to an actuator body 34 that is the main actuator. The actuator main body 34 has two hydraulic chambers 36A and 36B partitioned by a piston 35, one of which is the hydraulic chamber 3.
6A is connected to a suction/discharge port that becomes a discharge side when the pump 33 rotates in the forward direction through a first oil passage 37A, and to the other hydraulic chamber 36B, a suction/discharge port that becomes a discharge side when the pump 33 rotates in reverse is connected to the second oil passage 37B. A closed circuit is formed between the pump 33 and the pump 33. Therefore, the pump 33
Due to the operation, a pressure difference is generated before and after the piston 35 of the actuator body 33, which causes the actuating rod 38 integrated with the actuator piston 35 to
can be moved back and forth.

Here, the accumulator 40, which is provided to keep the circuit pressure constant and maintain the actuator rigidity, is configured as follows. That is,
As the specific structure is shown in FIG. 2, this accumulator has a cylindrical cylinder case 41, the openings at both ends of which are closed by covers 42, 43 to form a closed container. A piston 46 that partitions a gas chamber 44 and an oil chamber 45 is slidably mounted inside the cylinder case 41, and the oil chamber 45 is further divided into two chambers 45A and 45B. For this purpose, the piston 46 is formed in the shape of a cylindrical container with one end open, and an oil chamber dividing rod 47 protruding from the cover 42 is inserted into the opening. The internal space of the piston 46 that is closed at the tip of the rod 47 is defined as a first divided oil chamber 45A, and the space formed around the outer circumference of the rod 47 is defined as a second divided oil chamber 45B. Of course, seals 48 are attached to the sliding parts between the piston 46 and the cylinder case 41, the sliding parts between the piston 46 and the rod 47, etc., to prevent fluid leakage. In the accumulator 40, which has three internal chambers, the gas chamber 44 is filled with gas to introduce the initial circuit pressure, and the two oil chambers 45A and 45B are filled with hydraulic oil. For this reason, a gas filling port 49 that opens into the gas chamber 44 is formed in the cover 43,
After filling, the gas valve 50 is shut off to set the filling pressure as the initial pressure. Further, a first port 51 communicating with the first divided oil chamber 45A is formed in the rod 47, and a first port 51 communicating with the first divided oil chamber 45A is formed in the rod 47.
A second port 52 communicating with B is formed in the cover 42. Furthermore, in this embodiment, the area of the piston 46 facing each chamber is adjusted so that the pressure receiving area of the first and second divided oil chambers 45A, 45B is 1/2 of the pressure receiving area of the gas chamber 44. Specifically, this can be easily set by adjusting the rod insertion opening area of the piston 46.

Such an accumulator 40 is connected to the closed circuit, and this is because the first oil path 3
A first branch oil passage 53A branched from 7A is connected to the first port 51 of the accumulator 40, and a second branch oil passage 53 branched from the second oil passage 37B.
B is connected to the second port 52, and the discharge side circuit pressure during normal rotation of the pump 33 is transferred to the first divided oil chamber 4.
5A, and the discharge side circuit pressure during reverse rotation is also introduced into the second divided oil chamber 45B.

Further, the first and second branch oil passages 53A, 53B
An oil passage 55 connected to an oil passage 54 connected to the inside of the case of the pump 33 is provided between them, and the oil passage 55 has check valves 56A and 56B interposed therebetween. Check valve 56
The directions of A and 56B are set so that the high pressure side, which is the pump discharge pressure, is shut off, and the low circuit pressure, which is the pump suction pressure, acts on the pump case.

In addition, relief valves 57A and 57B for circuit protection are interposed in bypass paths 58A and 57B, respectively, in the first oil passage 37A and the second oil passage 37B, and furthermore, in the event of a failure in the actuator circuit system, In order to reduce the resistance of the actuator main body 34, a normally closed bypass valve 59 is interposed in another bypass path 60. Further, a rotation speed detector 61 such as a tachometer generator is attached to the DC servo motor 32 to monitor the motor rotation speed and provide feedback to the controller 31 to provide a rotation speed correction function. A piston position detector 62 is attached, and the detected value is fed back to the amplifier 30 for position correction.

In addition, 63 in the figure is a fuel supply valve.

The action of the closed-circuit electro-hydraulic actuator package configured as described above is as follows. When the hydraulic pump 33 is rotated in the forward direction by the motor 32,
The first hydraulic chamber 36A of the actuator main body 34 becomes the pump discharge pressure, and this pressure is applied to the first branch oil passage 53.
The first divided oil chamber 4 of the accumulator 40 through A
Acts on 5A. On the other hand, although the second oil pressure chamber 36B communicates with the second divided oil chamber 45B of the accumulator 40, due to pressure balance, the second oil passage 37B
The circuit pressure is reduced by the amount of pressure increase in the first oil passage 37A, and is lowered from the initial pressure. in this case,
Since the pressure receiving areas of the first and second divided oil chambers 45A and 45B are made equal, the amount of pressure increase in the first divided oil chamber 45A and the amount of pressure decrease in the second divided oil chamber 45B are equal. Therefore, the second oil passage 37B communicating with the second divided oil chamber 45B is also lowered, and the pump 3
The suction side pressure of No. 3 is lower than the initial pressure. As a result, the pressure difference before and after the piston 35 of the actuator body 34 becomes equal to the pressure difference between the first and second divided oil chambers 45A, 45B of the accumulator 40, and this pressure difference causes the actuator body 34 to
will be driven.

Such operating characteristics are shown in FIG. When the pump 33 is driven in the positive direction from the rest state (neutral position) of the actuator body 34 (initial pressure Po),
The pressure in the first hydraulic chamber 36A increases as indicated by the solid line _C1 in FIG. 3, and the pressure in the second hydraulic chamber 36B decreases as indicated by the broken line _C2 in the figure. This differential pressure becomes an effective differential pressure, and can generate a pressure difference twice as large as the differential pressure between the initial pressure and the pump discharge pressure. The same holds true when the pump 33 rotates in reverse.

According to this embodiment, even if the initial pressure is set high, the effective differential pressure can be increased, and the actuator capacity can be doubled with the same pump capacity as the conventional pump. Also, by increasing the initial pressure,
Since the pressure inside the hydraulic chambers 36A and 36B before and after the piston of the actuator main body 34 can be controlled, the actuator rigidity is improved, which is particularly useful for use on aircraft where safety is required.

In the above embodiment, the pressure-receiving areas of the divided oil chambers 45A and 45B of the accumulator 40 are made equal, but this may be determined based on the specifications of the actuator body 34. For example, the actuator body may have a single-rod structure, or the neutral point If there is a difference in the reciprocating movement from the base, the pressure-receiving area may be different. Therefore, in addition to being used for controlling the control surfaces of aircraft, it can also be sufficiently applied to hydraulic systems other than flight control systems and drive parts of general industrial machinery, robots, etc., and has great effects.

〔Effect of the invention〕

According to the closed-circuit electro-hydraulic actuator package of the present invention described above, as described above, it is possible to maintain a high initial pressure while increasing the effective differential pressure, thereby improving actuator rigidity. can be done.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of the embodiment, Fig. 2 is a sectional view of the accumulator, Fig. 3 is a pressure characteristic diagram of the embodiment, Fig. 4 is a circuit diagram of the conventional example, and Fig. 5 is the same pressure characteristic. It is a diagram. 32... DC servo motor, 33... Reversible hydraulic pump, 34... Actuator body, 37
A, 37B... Oil path, 40... Accumulator,
44... Gas chamber, 45, 45A, 45B... Oil chamber.

Claims (1)

[Claims] 1. An actuator body having two hydraulic chambers separated by a piston, a reversible pump that is the operating main body of the actuator body, a supply/discharge port that becomes the oil discharge side of the pump when the pump rotates forward, and one of the hydraulic chambers. and a second oil passage that connects the other side of the hydraulic chamber and a supply/discharge port that becomes the oil discharge side of the pump when the pump rotates in reverse; an accumulator having an oil chamber divided into two by a piston and a gas chamber filled with gas that provides the initial pressure of the actuator main body by pressing the common piston; A closed circuit electro-hydraulic actuator package in which the circuit pressure of the closed circuit is introduced from each hydraulic path, and the pressure receiving area of each of the divided chambers of the accumulator is the same as the area ratio of both hydraulic chambers of the actuator main body.