JP5595987B2 - Hydraulic device - Google Patents

Description

  The present invention relates to a hydraulic device that is driven by pressure fluid from a hydraulic pump that is driven by an electric motor.

  Conventionally, a drive device that is directly driven by a servo motor has been used. However, when a large driving force is required, a hydraulic device that supplies a hydraulic fluid from a hydraulic pump driven by a motor to the hydraulic cylinder and obtains a large driving force by the hydraulic cylinder is used. The hydraulic equipment requires hydraulic equipment such as electric motors, hydraulic pumps, hydraulic tanks, control valves, etc., so there is a problem of increasing the size of the equipment, and research and development for miniaturization is carried out Has been.

  Patent Document 1 discloses a hydraulic device that prevents the occurrence of a hunting phenomenon. The hydraulic device described in Patent Document 1 includes a hydraulic pump driven by an electric motor and capable of rotating in both directions. The rod side port of a single rod type hydraulic cylinder is connected to a rod side pipe line, and a head side port. Are connected to both ports of the hydraulic pump via the head side pipe line, provided with at least an electromagnetic valve for communicating the head side pipe line and the hydraulic tank, and a rotation detection sensor for detecting the rotation of the electric motor. And a stop control means for closing the solenoid valve when the rotation speed detected by the rotation detection sensor is equal to or lower than the set rotation speed when the hydraulic pump sucks from the head side pipe and drives the hydraulic cylinder. It is provided.

Japanese Patent No. 3247617

In the hydraulic device described in Patent Document 1, it is described that the hunting phenomenon can be suppressed.
However, in an actual hydraulic device, it is difficult to improve the responsiveness of the hydraulic device when provided with stop control means for closing the solenoid valve when the rotational speed detected by the rotation detection sensor is equal to or lower than the set rotational speed. It becomes.

  That is, in general, when the hydraulic device is controlled based on the number of rotations, the hydraulic pressure is non-linear. Therefore, there is a dead zone in the relationship between the hydraulic device and the motor, and the piston rod is placed at a predetermined position. In order to stop, it is necessary to turn on and off the electromagnetic valve in a short time.

Therefore, in the hydraulic device described in Patent Document 1, it is described that the solenoid valve is controlled to be closed based on a predetermined rotational speed. However, in order to increase the response of the hydraulic device, the threshold value of the rotational speed is reduced. Frequently, the solenoid valve is repeatedly turned on and off in a short time, which shortens the life of the equipment.
On the other hand, if the threshold value of the rotational speed is increased, it is possible to prevent the solenoid valve from repeatedly turning on and off in a short time, but the responsiveness of the hydraulic device itself is lowered.

  The objective of this invention is providing the hydraulic apparatus which can suppress the opening / closing frequency of a solenoid valve, improving the responsiveness of a hydraulic pump.

(1)
The hydraulic device according to the present invention includes a hydraulic pump driven by a motor and rotatable in both directions, a hydraulic actuator driven by a piston rod by the hydraulic pump, a hydraulic pump, a head side port of the hydraulic actuator, A pair of pipes respectively connecting the rod side port, an electromagnetic valve inserted in the pipe of the head side port, and at least one of a check valve and an electromagnetic valve inserted in the pipe of the rod side port; A displacement detector for detecting the displacement of the piston rod of the hydraulic actuator.

  In this case, since a displacement detector that directly detects the displacement of the piston rod of the hydraulic actuator is provided, the polarity of opening and closing of the solenoid valve is detected in the rotation direction of the motor, and the threshold of opening and closing of the solenoid valve is determined by the displacement detector. Can be determined based on the piston rod displacement from or the piston rod speed. That is, the frequency of opening and closing of the electromagnetic valve can be suppressed while improving the response of the hydraulic pump by detecting and controlling the direct piston rod displacement instead of the indirect information based on the rotation speed of the motor. . That is, even in the dead zone of the hydraulic device, the state of the piston rod can be easily detected. As a result, it is possible to improve the durability of the hydraulic device while increasing the responsiveness of the hydraulic device.

(2)
The hydraulic device may further include a control device that controls the electromagnetic valve, and the control device may control opening and closing of the electromagnetic valve according to the output of the displacement detector.

  In this case, since the control device can control the opening and closing of the electromagnetic valve according to the output of the displacement detector, it can be controlled based on the direct piston rod displacement from the displacement detector rather than indirect information. it can. As a result, the control can be reliably performed even in the dead zone of the hydraulic pressure.

(3)
In the hydraulic device, the solenoid valve may be integrally provided with solenoid valves provided on both of the pair of pipes.

  In this case, since the solenoid valves provided in both of the pair of pipes are integrally provided, the number of parts can be reduced. For example, a multi-directional multi-port multi-position electromagnetic valve, specifically a 4-direction 4-port 3-position electromagnetic valve can be used as the electromagnetic valve.

(4)
In the hydraulic device, the displacement detector may comprise a displacement sensor.

  In this case, the displacement amount and speed of the piston rod can be detected without imposing a large load on the movement of the piston rod.

(5)
In the hydraulic device, the displacement detector may comprise a magnetostrictive linear displacement sensor.

  In this case, since the displacement detector comprises a magnetostrictive linear displacement sensor, the size and weight can be reduced, and the displacement amount and speed of the piston rod can be detected without imposing a large load on the movement of the piston rod. .

(6)
In the hydraulic apparatus, the motor, the hydraulic pump, and the hydraulic actuator are a motor pump integrated cylinder.

  In this case, by forming the piping with a manifold, the motor, the hydraulic pump, and the cylinder that is the hydraulic actuator are integrated, so that the hydraulic device can be downsized.

It is a schematic diagram which shows an example of the hydraulic apparatus concerning this Embodiment. It is a schematic diagram which shows the arrangement | positioning and connection example of the solenoid valve of the hydraulic apparatus shown in FIG. It is a flowchart explaining the process of the controller which controls a solenoid valve. It is a schematic diagram which shows the other example of arrangement | positioning and the example of a connection of the solenoid valve of the hydraulic apparatus shown in FIG. It is a schematic diagram which shows the further another example of arrangement | positioning and the example of a connection of the solenoid valve of the hydraulic device shown to FIG. 2 and FIG. It is a schematic diagram which shows the further another example of arrangement | positioning and the example of a connection of the solenoid valve of the hydraulic apparatus shown in FIG.2, FIG4 and FIG. It is a schematic diagram which shows the further another example of arrangement | positioning and the example of a connection of the solenoid valve of the hydraulic apparatus shown in FIG.

  Embodiments according to the present invention will be described below with reference to the drawings. In this embodiment, a motor pump integrated cylinder in which a pump, a motor, and a hydraulic cylinder are integrated by forming a manifold into a pipe will be described.

(One embodiment)
First, FIG. 1 is a schematic diagram illustrating an example of a hydraulic device 100 according to the present embodiment, and FIG. 2 is a schematic diagram illustrating an arrangement and connection example of an electromagnetic valve 300 of the hydraulic device 100 illustrated in FIG. is there.

(Outline of hydraulic equipment)
1 mainly includes a hydraulic cylinder 200, a linear displacement meter 250, a solenoid valve 300, a motor 400, an encoder 420, a pressure gauge 430, a pump 450, a controller 500, and a tank 600. As described above, although the motor 400, the pump 450, and the hydraulic cylinder 200 are separately described in FIG. 1, they are integrally formed.

  The controller 500 in FIG. 1 includes, for example, a CPU (Central Control Unit), a ROM (Read Only Memory), a RAM (Random Memory), and the like.

  The hydraulic cylinder 200 is a double-acting cylinder and includes a piston 210 and a piston rod 220. A linear displacement meter 250 is attached to at least one of the piston 210 and the piston rod 220. Here, the linear displacement meter 250 includes a magnetostrictive sensor. The linear displacement meter 250 is arranged so that it can directly detect the displacement in the exit direction and the return direction of the piston rod 220 of the hydraulic cylinder 200.

  As shown in FIG. 1, pressure data of the pressure gauge 430 is given to the controller 500. The encoder 420 detects the drive displacement of the motor 400. Detection data of the encoder 420 is given to the controller 500. Although one pressure gauge 430 is shown in FIG. 1, it may be provided on both sides of the pump 450. Further, the illustration of the pressure gauge 430 is omitted from FIG.

  The linear displacement meter 250 detects the displacement in the exit direction and the return direction of the piston rod 220 of the hydraulic cylinder 200. The detection result of the linear displacement meter 250 is given to the controller 500. The controller 500 performs predetermined processing (PID control), converts a predetermined processing result into a motor control signal (torque signal), amplifies it, and gives it to the motor 400. The motor 400 is driven based on the motor control signal OF.

  Further, the controller 500 outputs a solenoid valve opening / closing signal OC to the solenoid of the solenoid valve 300. The electromagnetic valve 300 opens and closes the valve based on the electromagnetic valve opening / closing signal OC.

(Piping configuration of hydraulic equipment)
Next, the details of the piping configuration of the hydraulic apparatus 100 will be described with reference to FIG. The solenoid valve 300 in FIG. 2 uses two-port single-acting normally open solenoid valves 310 and 320. As shown in FIG. 2, one end of the pipe 451 p is connected to the head side port HP of the hydraulic cylinder 200, and the other end of the pipe 451 p is connected to the pump 450. Further, one end of the pipe 452p is connected to the rod side port RP of the hydraulic cylinder 200, and the other end of the pipe 452p is connected to the pump 450.

  A branch A is provided in the middle of the pipe 452p, and a branch C is provided in the middle of the pipe 451p. One end of the pipe 455p is connected to the branch C, and the other end of the pipe 455p is connected to the first port of the two-port single-acting normally open solenoid valve 320. One end of the pipe 454p is connected to the second port of the 2-port single-acting normally open solenoid valve 320, and the other end of the pipe 454p is connected to the first port of the 2-port single-acting normally open solenoid valve 310.

  Further, one end of the pipe 453p is connected to the second port of the two-port single-acting normally open electromagnetic valve 310, and the other end of the pipe 453p is connected to the branch A. One end of the pipe 460p is connected to the branch B provided in the middle of the pipe 454p, and the other end of the pipe 460p is connected to the tank 600.

(Hydraulic cylinder operation)
Hereinafter, the operation of the hydraulic cylinder 200 will be briefly described. First, the motor 400 rotates according to the motor control signal OF from the controller 500, and the pump 450 is driven according to the rotation of the motor 400. In the present embodiment, at least the pump 450 can rotate forward and backward. Furthermore, the motor 400 may be capable of forward and reverse rotation. That is, at least one or both of the pump 450 and the motor 400 may be rotatable forward and backward. A plurality of motors 400 and pumps 450 may be provided.

  The hydraulic cylinder 200 includes a rod-side port RP and a head-side port HP, and pressure oil is sent from the pump 450 to the head-side port HP via an electromagnetic valve 300 including two-port single-acting normally-open electromagnetic valves 310 and 320. In this case, the piston rod 220 is extended and returned to the pump 450 from the rod side port RP. As shown in FIGS. 1 and 2, this state is referred to as the piston rod 220 of the hydraulic cylinder 200 being in the outgoing direction.

On the other hand, when the pressure oil is sent from the pump 450 to the rod side port RP via the solenoid valve 300 including the two-port single-acting normally open solenoid valves 310 and 320, the piston rod 220 contracts and the pressure oil is sent from the head side port HP. Is returned to the pump 450 and the tank 600. As shown in FIGS. 1 and 2, this state is that the piston rod 220 of the hydraulic cylinder 200 is in the return direction.
As described above, the piston rod 220 of the hydraulic cylinder 200 double-acts in the exit direction or the return direction. Further, a heavy object (not shown) is connected to the piston rod 220 of the hydraulic cylinder 200, and the piston rod 220 of the hydraulic cylinder 200 double-acts in the outward direction or the return direction in order to move the heavy object. . In this embodiment, since a difference corresponding to the volume of the piston rod 220 is generated, the difference is absorbed and controlled by controlling the supply or discharge of the oil amount from the tank 600.

(Solenoid valve control processing)
Hereinafter, a control example of the electromagnetic valve 300 shown in FIG. 2 will be described. FIG. 3 is a flowchart for explaining processing of the controller 500 that controls the electromagnetic valve 300.

  As shown in FIG. 3, first, the rotation direction of the motor 400 is detected using the encoder 420 (step S1). Here, when the rotation direction of the motor 400 is the return direction, the traveling direction of the piston rod 220 of the hydraulic cylinder 200 is detected by the linear displacement meter 250 (step S2).

  Here, if the detection result from the linear displacement meter 250 determines that the traveling direction of the piston rod 220 of the hydraulic cylinder 200 is the outgoing direction, the controller 500 determines that a disturbance has occurred in the hydraulic cylinder 200, and The solenoid valve 300 including the two-port single-acting normally open solenoid valves 310 and 320 is controlled to be closed (step S3). That is, since the piston rod 220 of the hydraulic cylinder 200 moves in the reverse direction even though the solenoid valve 300 is controlled in the return direction, the solenoid valve including the two-port single-acting normally-open solenoid valves 310 and 320. 300 is closed and the movement of the piston rod 220 of the hydraulic cylinder 200 is suppressed.

On the other hand, when it is determined that the traveling direction of the piston rod 220 of the hydraulic cylinder 200 is the return direction, it is determined whether or not the speed of the piston rod 220 of the hydraulic cylinder 200 is greater than a predetermined value SA (step S4). When the speed of the piston rod 220 of the hydraulic cylinder 200 is larger than the predetermined value SA, the head side two-port single-acting normally open solenoid valve 320 of the solenoid valve 300 is controlled to open (step S5).
As a result, part of the oil amount is returned from the head side to the tank 600 side via the head-side two-port single-acting normally-open electromagnetic valve 320. Therefore, since the amount of oil returned from the head side to the pump 450 is reduced, the amount of oil sent from the pump 450 to the rod side can be reduced.

  On the other hand, when the speed of the piston rod 220 of the hydraulic cylinder 200 is smaller than the predetermined value SA, the two-port single-acting normally open solenoid valves 310 and 320 on the rod side and the head side of the solenoid valve 300 are closed (step S3). Accordingly, all of the oil amount flows from the head side port HP to the pipe 451p side, and the oil amount sent from the pump 450 flows from the pipe 452p side to the rod side port RP, so that the speed of the hydraulic cylinder 200 can be increased.

  On the other hand, in the process of step S1, when the encoder 420 determines that the rotation direction of the motor 400 is the outgoing direction, the traveling direction of the piston rod 220 of the hydraulic cylinder 200 is detected by the linear displacement meter 250 (step S12).

  Here, if the detection result from the linear displacement meter 250 determines that the traveling direction of the piston rod 220 of the hydraulic cylinder 200 is the return direction, the controller 500 determines that a disturbance has occurred in the hydraulic cylinder 200, and The solenoid valve 300 including the two-port single-acting normally open solenoid valves 310 and 320 is controlled to be closed (step S3).

On the other hand, when it is determined that the traveling direction of the piston rod 220 of the hydraulic cylinder 200 is the outgoing direction, it is determined whether or not the speed of the piston rod 220 of the hydraulic cylinder 200 is equal to or less than a predetermined value SB (step S14). When the speed of the piston rod 220 of the hydraulic cylinder 200 is equal to or less than the predetermined value SB, the rod side two-port single-acting normally open solenoid valve 310 is controlled to open (step S15). As a result, the amount of oil can be supplied from the pump 450 to the head side from the tank 600 via the rod side two-port single-acting normally open solenoid valve 310, so that the speed of the piston rod 220 of the hydraulic cylinder 200 can be adjusted to the predetermined value SB. it can.
On the other hand, when the speed of the piston rod 220 of the hydraulic cylinder 200 is greater than the predetermined value SB, the two-port single-acting normally open solenoid valves 310 and 320 on the rod side and the head side of the solenoid valve 300 are closed (step S3).

  As described above, in the hydraulic device 100, since the pressure suddenly changes due to the minute displacement of the piston rod 220 of the hydraulic cylinder 200, a control system capable of high-speed response is required. Furthermore, since the movement of the piston rod 220 is nonlinear due to the problem of hunting or dead zone, the linear displacement meter 250 can be used for reliable detection.

(Other examples)
FIG. 4 is a schematic diagram illustrating another example of the arrangement and connection example of the electromagnetic valve 300 of the hydraulic device 100 illustrated in FIG. 2.

  Hereinafter, the hydraulic device 100a will be described. Note that the difference between the hydraulic device 100a shown in FIG. 4 and the hydraulic device 100 shown in FIG. 2 will be mainly described. Therefore, the description of the same part is omitted.

  First, the hydraulic device 100 a in FIG. 4 further includes pilot check valves 380 and 390 as the electromagnetic valve 300.

(Piping configuration of other examples of hydraulic equipment)
As shown in FIG. 4, one end of the pipe 451 p is connected to the head side port HP of the hydraulic cylinder 200, and the other end of the pipe 451 p is connected to the pump 450. Further, one end of the pipe 452p is connected to the rod side port RP of the hydraulic cylinder 200, and the other end of the pipe 452p is connected to the pump 450.

Branches A1 and A2 are provided in the middle of the pipe 452p, and branches C1 and C2 are provided in the middle of the pipe 451p.
One end of the pipe 455p is connected to the branch C1, and the other end of the pipe 455p is connected to the first port of the two-port single-acting normally open electromagnetic valve 320. In addition, one end of the pipe 454p is connected to the second port of the two-port single-acting normally open electromagnetic valve 320, and the other end of the pipe 454p is connected to the pilot port of the pilot check valve 380.

  One end of the pipe 453p is connected to the branch A1, and the other end of the pipe 453p is connected to the second port of the 2-port single-acting normally open electromagnetic valve 310. One end of the pipe 456 p is connected to the first port of the two-port single-acting normally open electromagnetic valve 310, and the other end of the pipe 456 p is connected to the pilot port of the pilot check valve 390.

  One end of the pipe 457p is connected to the branch A2, and the other end of the pipe 457p is connected to the out side connection port of the pilot check valve 380. One end of the pipe 458 p is connected to the in-side connection port of the pilot check valve 380, and the other end of the pipe 458 p is connected to the in-side connection port of the pilot check valve 390. A branch B is formed in the pipe 458p.

  One end of a pipe 459p is connected to the branch C2, and the other end of the pipe 459p is connected to an out-side connection port of the pilot check valve 390.

  A solenoid valve open / close signal OC from the controller 500 is connected to the solenoids of the two-port single-acting normally open solenoid valves 310 and 320. As a result, the same operation as that of the hydraulic device 100 shown in FIGS. 1 to 3 can be performed.

(Still another example 1)
FIG. 5 is a schematic diagram illustrating still another example of the arrangement and connection example of the electromagnetic valve 300 of the hydraulic device 100 illustrated in FIGS. 2 and 4.

  Hereinafter, the hydraulic device 100b will be described. Note that the difference between the hydraulic device 100b shown in FIG. 5 and the hydraulic device 100 shown in FIG. 2 will be mainly described. Therefore, the description of the same part is omitted.

(Regarding the piping configuration of the hydraulic device of still another example 1)
First, the hydraulic device 100b of FIG. 5 includes a check valve 370 instead of the 2-port single-acting normally open electromagnetic valve 310 as the electromagnetic valve 300. One end of the pipe 453 p is connected to the out side connection port of the check valve 370, and the other end of the pipe 453 p is connected to the branch A. One end of the pipe 454p is connected to the in-side connection port of the check valve 370, and the other end side of the pipe 454p is connected to the second connection port of the two-port single-acting normally open electromagnetic valve 320.

  A solenoid valve open / close signal OC from the controller 500 is connected to the solenoid of the two-port single-acting normally open solenoid valve 320. As a result, the same operation as that of the hydraulic device 100 shown in FIGS. 1 to 3 can be performed.

(Still another example 2)
FIG. 6 is a schematic diagram illustrating still another example of the arrangement and connection example of the electromagnetic valve 300 of the hydraulic device 100 illustrated in FIGS. 2, 4, and 5.

  Hereinafter, the hydraulic device 100c will be described. Note that the difference between the hydraulic device 100c shown in FIG. 6 and the hydraulic device 100a shown in FIG. 4 will be mainly described. Therefore, the description of the same part is omitted.

  First, the hydraulic device 100c in FIG. 6 does not use the 2-port single-acting normally open solenoid valve 320 as the solenoid valve 300, but uses only the 2-port single-acting normally open solenoid valve 310.

(Regarding the piping configuration of the hydraulic device of still another example 2)
As shown in FIG. 6, one end of a pipe 454p is connected to the branch C1, and the other end of the pipe 454p is connected to a pilot port of the pilot check valve 380.

  A solenoid valve opening / closing signal OC from the controller 500 is connected to the solenoid of the 2-port single-acting normally open solenoid valve 310. As a result, the same operation as that of the hydraulic device 100 shown in FIGS. 1 to 3 can be performed.

(Still another example 3)
FIG. 7 is a schematic diagram showing still another example of the arrangement and connection example of the electromagnetic valve 300 of the hydraulic device 100 shown in FIG.

  Hereinafter, the hydraulic device 100d will be described. Note that the difference between the hydraulic device 100d shown in FIG. 7 and the hydraulic device 100 shown in FIG. 2 will be mainly described. Therefore, the description of the same part is omitted.

  First, the hydraulic device 100d of FIG. 7 includes a four-way four-port three-position electromagnetic valve 330 as the electromagnetic valve 300, instead of the two-port single-action normally-open electromagnetic valve 310 and the two-port single-action normally-open electromagnetic valve 320. .

(Regarding the piping configuration of the hydraulic device of still another example 3)
As shown in FIG. 7, one end of the pipe 455 p is connected to the branch C, and the other end of the pipe 455 p is connected to the second port of the four-way four-port three-position solenoid valve 330. One end of the pipe 454 p is connected to the branch A, and the other end of the pipe 454 p is connected to the first port of the four-way four-port three-position solenoid valve 330.
One end of the pipe 460 p is connected to the third port of the four-direction four-port three-position electromagnetic valve 330, and the other end of the pipe 460 p is connected to the tank 600.

  A solenoid valve opening / closing signal OC from the controller 500 is connected to each solenoid of the four-way four-port three-position solenoid valve 330. As a result, the same operation as that of the hydraulic device 100 shown in FIGS. 1 to 3 is performed.

  In the present embodiment, the rotation direction of the motor is detected by the encoder 420. However, the present invention is not limited to this, and any other rotation direction detection device, motor rotation direction detector, non-contact sensor. A motor having a function of detecting the rotation direction may be used.

  In the above embodiment, since the linear displacement meter 250 for detecting the piston rod displacement of the hydraulic cylinder 200 is provided, the opening / closing polarity of the electromagnetic valve 300 is detected in the rotational direction of the motor 400, and The open / close threshold can be determined based on the piston rod displacement or the piston rod speed from the linear displacement meter 250. That is, instead of indirect information based on the rotation speed of the motor 400, the direct displacement of the piston rod is detected, and the controller 500 controls the solenoid valve 300, thereby improving the responsiveness of the pump 450 and improving the response of the solenoid valve 300. Opening and closing frequency can be suppressed. As a result, in the hydraulic devices 100, 100a,..., 100d, it is possible to improve durability while improving responsiveness.

  In the present invention, the motor 400 corresponds to a motor, the pump 450 corresponds to a hydraulic pump, the hydraulic cylinder 200 corresponds to a hydraulic actuator and a motor pump integrated cylinder, the controller 500 corresponds to a control device, The pressure devices 100, 100a, to 100d correspond to hydraulic devices, the head side port HP corresponds to the head side port, the rod side port RP corresponds to the rod side port, and the solenoid valves 300, 310, 320, 330 The check valves 370, 380, and 390 correspond to check valves, the linear displacement meter 250 corresponds to a displacement detector, a displacement sensor, and a magnetostrictive sensor, and the four-way four-port three-position solenoid valve 330 corresponds to a solenoid valve. This corresponds to a solenoid valve provided as a unit.

  A preferred embodiment of the present invention is as described above, but the present invention is not limited thereto. It will be understood that various other embodiments may be made without departing from the spirit and scope of the invention. Furthermore, in this embodiment, although the effect | action and effect by the structure of this invention are described, these effect | actions and effects are examples and do not limit this invention.

100, 100a, to 100d Hydraulic device 200 Hydraulic cylinder 250 Linear displacement meter 300, 310, 320, 330 Solenoid valve 370, 380, 390 Check valve 400 Motor 450 Pump HP Head side port RP Rod side port

Claims (7)

A hydraulic pump driven by a motor;
A hydraulic actuator driven by a piston rod by the hydraulic pump;
A pair of pipes connecting the hydraulic pump and the head side port and the rod side port of the hydraulic actuator;
An electromagnetic valve interposed in the pipe of the head side port;
At least one of a check valve and a solenoid valve inserted in a pipe line of the rod side port;
A displacement detector for detecting piston rod displacement of the hydraulic actuator;
A control device for controlling the solenoid valve,
The control device closes the electromagnetic valve when the rotation direction of the hydraulic pump and the output direction or return direction of the piston rod of the hydraulic actuator do not match in the output of the displacement detector . The hydraulic device according to claim 1, wherein the control device controls opening and closing of the electromagnetic valve according to a speed and a displacement of the displacement detector . The hydraulic device according to claim 1 or 2, wherein the control device controls the opening of the electromagnetic valve of the head side port when the speed of the displacement detector exceeds a predetermined value . The solenoid valve comprises a pair of conduits electromagnetic valve provided in both of that provided as an integral, hydraulic apparatus according to any one of 3 from 請 Motomeko 1. It said displacement detector ing from the displacement sensor, the hydraulic device according to any one of 請 Motomeko 1 4. The displacement detector is composed of a magnetostrictive sensor, a hydraulic device according to any one of 5 請 Motomeko 1. Said motor, said hydraulic pump and said hydraulic actuator is a motor pump integrated cylinder, hydraulic system according to any one of 請 Motomeko 1 6.