WO2010058632A1

WO2010058632A1 - Hydraulic actuator and hydraulic vibration test device

Info

Publication number: WO2010058632A1
Application number: PCT/JP2009/063695
Authority: WO
Inventors: 繁松本; 博至宮下; 一宏村内; 光央角田
Original assignee: 国際計測器株式会社
Priority date: 2008-11-21
Filing date: 2009-07-31
Publication date: 2010-05-27
Also published as: JP2014025590A; KR101305982B1; JP5735595B2; JP2010151772A; CN102216750A; CN102216750B; TW201020536A; JP5368084B2; TWI420090B; KR20110070917A

Abstract

A hydraulic actuator provided with a hydraulic pump and a hydraulic cylinder unit. The hydraulic pump has a first suction and discharge opening and a second suction and discharge opening and can be reversely operated. The hydraulic cylinder unit is provided with a piston, a sleeve having an inner space partitioned by the piston into a first pressure chamber and a second pressure chamber, and a piston rod connected to the piston and having a front end projecting to the outside of the sleeve. The hydraulic actuator is provided with first piping for interconnecting the first pressure chamber and the first suction and discharge opening, and also with second piping for interconnecting the second pressure chamber and the second suction and discharge opening. When the hydraulic piston is reversely operated, hydraulic pressure is alternately applied to the first and second pressure chambers to vertically move the piston. The hydraulic actuator is further provided with a bypass pipe for interconnecting the first and second piping and also with an accumulator provided in the middle of the bypass pipe and applying back pressure to the first and second pressure chambers. A vibration test device equipped with the hydraulic actuator is also provided.

Description

Hydraulic actuator and hydraulic vibration test device

The present invention relates to a hydraulic actuator and a hydraulic vibration test apparatus capable of high-speed inversion driving.

As a vibration test apparatus that vibrates a subject with a hydraulic cylinder, for example, a device using a volumetric pump and a servo valve as described in JP-A-2000-2617 is known. Such a vibration test apparatus can vibrate the subject at a high frequency while applying a large load to the subject. An example of a circuit diagram of a hydraulic vibration testing apparatus using a servo valve is shown in FIG.

5 has a pump unit 110, a hydraulic oil tank 120, a hydraulic cylinder unit 130, a servo valve 140, and a vibration table 150. The hydraulic vibration test apparatus 101 shown in FIG. A workpiece W is fixed on the vibration table 150, and the workpiece W is vibrated by reciprocating the vibration table 150.

The pump unit 110 drives the volume pump body 111 by a motor 112, and is connected to a hydraulic circuit between the hydraulic oil tank 120 and the servo valve 140. Note that the rotation direction of the motor 112 is limited to one direction, that is, the motor 112 can only rotate forward. Further, the rotation speed of the motor 112 is kept substantially constant. The pump unit 110 has a function of only sending hydraulic oil from the hydraulic oil tank 120 to the servo valve 140, and its flow rate is kept substantially constant.

The cylinder unit 130 includes a sleeve 131, a piston 132 that can move within the sleeve 131, and a piston rod 133 that projects from one side of the piston 132 to the outside of the sleeve 131. A vibration table 150 is fixed to the tip of the piston rod 133. The inside of the sleeve 131 is divided into a first pressure chamber 131a and a second pressure chamber 131b by a piston 132. The first pressure chamber 131a and the second pressure chamber 131b are filled with hydraulic oil. The first pressure chamber 131a and the second pressure chamber 131b are connected to the servo valve 140 via

pipes

161 and 162, respectively.

Servo valve 140 is used to switch the hydraulic oil sent from pump unit 110 to either

pipe

161 or 162 and to control the hydraulic pressure of the hydraulic oil sent to the pipe. The servo valve 140 connects a pipe through which hydraulic oil is not sent to a pipe 164 that leads to the hydraulic oil tank 120. The switching operation and hydraulic pressure adjustment operation of the servo valve 140 are controlled by the controller 102.

When the hydraulic circuit is configured so that the hydraulic oil is sent from the pump unit 110 to the pipe 161, the hydraulic oil is supplied to the first pressure chamber 131a, and the internal pressure of the first pressure chamber 131a increases. Thereby, the piston 132 is pushed down toward the second pressure chamber 131b, and the vibration table 150 is lowered. At this time, the hydraulic oil in the second pressure chamber 131 b is returned to the hydraulic oil tank 120 via the pipe 162 and the servo valve 140. On the other hand, when the hydraulic circuit is configured so that the hydraulic oil is sent from the pump unit 110 to the pipe 162, the hydraulic oil is supplied to the second pressure chamber 131b, and the internal pressure of the second pressure chamber 131b increases. Accordingly, the piston 132 is pushed up toward the first pressure chamber 131a, and the vibration table 150 is raised. At this time, the hydraulic oil in the first pressure chamber 131 a is returned to the hydraulic oil tank 120 via the pipe 161 and the servo valve 140.

As shown in FIG. 5, the pipe 163 from the pump unit 110 to the servo valve 140 and the pipe 164 from the servo valve 140 to the hydraulic oil tank 120 are connected by a bypass pipe 165. All of the hydraulic oil supplied by the pump unit 110 does not go to the hydraulic cylinder unit 130, and a part is returned to the hydraulic oil tank 120 via the bypass pipe 165. In addition, in order to prevent the backflow of the hydraulic oil in the

pipes

163 and 164,

check valves

166 and 167 are provided in the respective pipes.

As described above, in the servo valve type vibration test apparatus, the controller 102 controls the servo valve 140 to periodically switch the hydraulic oil to be sent to the first pressure chamber 131a or the second pressure chamber 131b. Thus, the vibration table 150 is reciprocated. In the servo valve type hydraulic vibration testing apparatus, a part of the hydraulic fluid circulated at a high pressure and a large flow rate is sent to the hydraulic cylinder unit 130 by the servo valve 140. Therefore, the first pressure chamber 131a and the second pressure chamber When the hydraulic oil is sent to which of 131b, the pressure in the pressure chamber to which the hydraulic oil is sent rises instantaneously to a high pressure, and the moving direction of the vibration table 150 is switched without causing a time lag. For this reason, it is possible to vibrate the vibration table at a high frequency.

The vibration table 150 is provided with an acceleration sensor 103, and a signal indicating the acceleration detected by the acceleration sensor 103 is supplied to the controller 102. The controller 102 calculates the displacement, speed, or acceleration of the vibration table 150 based on the detection result of the acceleration sensor 103, and controls the servo valve 140 so that the vibration table 150 vibrates with a desired displacement, speed, or acceleration waveform. It is possible.

In a hydraulic actuator using a servo valve, in order to supply a desired pressure to a hydraulic cylinder instantaneously and stably, only a part of the hydraulic energy supplied by the pump is driven while continuously driving a pump having a sufficiently large flow rate. A configuration for supplying to a hydraulic cylinder has been adopted. For this reason, the amount of energy consumed by the vibration test apparatus using such a hydraulic actuator is much larger than the energy required for exciting the subject, and wasted energy is consumed. In addition, a large-capacity hydraulic oil tank is required to circulate the hydraulic oil by such a pump.

The present invention has been made to solve the above problems, and does not require a large-sized pump or hydraulic oil tank, and is a high-output hydraulic actuator capable of high-speed response, and a high frequency while applying a large load to the subject. An object of the present invention is to provide a vibration test apparatus capable of vibrating a subject.

According to an embodiment of the present invention, a hydraulic pump capable of reversing operation, a piston, and a piston are connected to a sleeve and a piston whose inner space is divided into a first pressure chamber and a second pressure chamber, and a tip projects out of the sleeve. A hydraulic cylinder unit including a piston rod, a first pipe connecting the first pressure chamber to the first intake / exhaust port, and a second pipe connecting the second pressure chamber to the second intake / exhaust port; An actuator is provided that moves the piston up and down by alternately applying hydraulic pressure to the first and second pressure chambers by reverse operation. The actuator further includes a bypass pipe that connects the first and second pipes, and an accumulator that is provided in the middle of the bypass pipe and applies back pressure to the first and second pressure chambers.

In the actuator according to the embodiment of the present invention, a hydraulic pump that reversely operates in both forward and reverse directions is used. This hydraulic pump is directly connected to the hydraulic cylinder unit without passing through the servo valve, and drives the hydraulic cylinder unit. In the actuator according to the embodiment of the present invention, since the hydraulic cylinder unit is driven according to the flow rate and direction of the hydraulic oil output from the pump, a large pump such as that used for a servo valve actuator or No hydraulic oil tank is required. For the above reason, the energy consumption by the actuator according to the embodiment of the present invention is not so large as compared with the energy required for the vibration of the subject. Energy consumption can be greatly reduced.

A hydraulic pump that operates in reverse is characterized in that when the pump operation direction is reversed, the pressure of the hydraulic oil decreases, and a time lag of about several tens of milliseconds occurs before the pressure increases sufficiently. For this reason, if the pump is simply connected to the hydraulic cylinder unit, the time lag will occur when the pump drive direction is reversed and the moving direction of the vibration table is switched, and the vibration table is moved during that time. I can't. For this reason, the subject cannot be vibrated at a high frequency (several tens of Hz or more) such that this time lag cannot be ignored. However, in the actuator according to the embodiment of the present invention, since the accumulator applies back pressure to the first pressure chamber and the second pressure chamber of the hydraulic cylinder unit via the bypass pipe, the operation direction of the pump is reversed. However, the pressure of the hydraulic oil hardly decreases, and the time lag is extremely small. For this reason, in the actuator according to the embodiment of the present invention, the subject can be vibrated at a high frequency.

It is preferable that the back pressure applied by the accumulator to the first pressure chamber and the second pressure chamber is set larger than the minimum pressure required for driving the cylinder of the hydraulic cylinder unit. In this case, there is almost no response delay due to the hydraulic system.

The hydraulic pump used in the hydraulic actuator according to the embodiment of the present invention is typically a piston pump. The actuator preferably further includes a servo motor as a drive source for the hydraulic pump.

In addition, the hydraulic actuator according to the embodiment of the present invention may further include a sensor that detects the movement of the movable portion of the hydraulic actuator (or the object to be driven by the hydraulic actuator) and a controller that controls the servo motor. In this case, the controller can control the servo motor based on the detection result of the sensor. The sensor preferably includes any one of a displacement sensor, a speed sensor, an acceleration sensor, and a load sensor. In this case, the controller can control the servo motor to drive the piston in accordance with a predetermined displacement, velocity or acceleration waveform based on the detection result of the sensor. The sensor may be detachable from a hydraulic actuator (specifically, a controller).

The sensor may include a load sensor. In this case, the controller can control the servo motor so that the load detected by the load sensor changes according to a predetermined waveform based on the detection result of the sensor.

Further, according to the embodiment of the present invention, there is also provided a vibration test apparatus including the hydraulic actuator described above and a vibration table provided at the tip of the piston rod.

The vibration test apparatus according to the embodiment of the present invention preferably further includes a sensor provided on the vibration table and a controller for controlling the servo motor.

Further, the sensor provided on the vibration table may include a sensor that measures the displacement, speed, or acceleration of the vibration table. In this case, the controller can control the servo motor to drive the vibration table according to a predetermined waveform of displacement, speed, or acceleration based on the detection result of the sensor.

Further, the sensor may include a load sensor that measures a load applied to the subject. In this case, the controller can control the servo motor to apply a load to the subject according to a predetermined waveform based on the detection result of the sensor.

FIG. 1 is a schematic circuit diagram of a vibration test apparatus according to an embodiment of the present invention. FIG. 2 is a diagram showing a schematic configuration for applying a static load to a subject in the vibration test apparatus according to the embodiment of the present invention. FIG. 3 is a graph plotting acceleration and displacement of the vibration table in the embodiment of the present invention. FIG. 4 is a graph plotting acceleration and displacement of the vibration table in the comparative example. FIG. 5 is a schematic circuit diagram of a conventional hydraulic vibration test apparatus using a servo valve.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a circuit diagram of a vibration test apparatus according to the present embodiment. As shown in FIG. 1, the vibration test apparatus 1 according to this embodiment includes a pump unit 10, a hydraulic oil tank 20, a hydraulic cylinder unit 30, a vibration table 50, and an accumulator 70. The vibration table 50 is moved up and down by the hydraulic pressure supplied to the hydraulic cylinder unit 30, whereby the subject W fixed on the vibration table 50 is vibrated.

The pump unit 10 has a pump body 11 and a servo motor 12. The servo motor 12 is driven by an alternating current output from the servo amplifier 4. The servo motor 12 is configured to be able to rotate the drive shaft 12a in both forward and reverse directions and to precisely adjust the rotational speed of the drive shaft 12a. The servo motor 12 is a low-inertia AC servo motor capable of high-output and high-repetition-rate inversion driving.

The pump body 11 is a piston pump capable of sending hydraulic oil from the first intake / exhaust port 11a to the second intake / exhaust port 11b or from the second intake / exhaust port 11b to the first intake / exhaust port 11a. By driving the pump body 11 by the servo motor 12, the flow rate and direction of the hydraulic oil supplied by the pump body 11 can be changed. For example, when the servo motor 12 is driven in reverse at a constant cycle, the flow rate and direction of the hydraulic oil flowing between the first intake / exhaust port 11a and the second intake / exhaust port 11b change periodically.

The cylinder unit 30 includes a sleeve 31, a piston 32 that can move within the sleeve 31, and a piston rod 33 that projects from one surface of the piston 32 to the outside of the sleeve 31. A vibration table 50 is fixed to the tip of the piston rod 33. The inside of the sleeve 31 is divided into a first pressure chamber 31a and a second pressure chamber 31b by a piston 32. The first pressure chamber 31a and the second pressure chamber 31b are filled with hydraulic oil. The first pressure chamber 31a and the second pressure chamber 31b are connected to the first intake / exhaust port 11a and the second intake / exhaust port 11b of the pump body 11 through

pipes

61 and 62, respectively. In addition, as the

pipes

61 and 62, a high-pressure hose that can withstand a pressure increase (approximately several tens of MPa) of hydraulic oil generated when the vibration table 50 is moved (not causing elastic deformation) is used.

The hydraulic oil tank 20 is connected to the first pressure chamber 31a and the second pressure chamber 31b via

check valves

63 and 64, respectively. The

check valves

63 and 64 open when the internal pressures of the first pressure chamber 31a and the second pressure chamber 31b become lower than the hydraulic pressure (for example, atmospheric pressure) in the hydraulic oil tank 20, respectively. Hydraulic oil is supplied to the

pipes

61 and 62. In the present embodiment, when the first pressure chamber 31a (or the second pressure chamber 31b) is filled with the working oil, the check valve 63 (or the check valve 64) is opened and the pressure chamber 31a is opened from the working oil tank 20. The hydraulic oil moves to (or the pressure chamber 31b).

Specifically, the hydraulic oil is filled into the

pressure chambers

31a and 31b as follows. The first pressure chamber 31a and the second pressure chamber 31b are provided with a valve (not shown) for bleeding air. First, in a state where the valve of the first pressure chamber 31a is opened and the valve of the second pressure chamber 31b is closed, the pump unit 10 is set so that hydraulic oil and air are sent from the second intake / exhaust port 11b to the first intake / exhaust port 11a. To drive. Then, the air in the second pressure chamber 31b and the pipe 62 is released from the valve of the first pressure chamber 31a through the pipe 61. Eventually, since the pressure in the second pressure chamber 31b and the pipe 62 becomes lower than the pressure in the hydraulic oil tank 20, the check valve 64 opens and the hydraulic oil in the hydraulic oil tank 20 passes through the

pipes

62 and 61 to the first. The pressure chamber 31a is filled.

After the hydraulic oil is filled in the first pressure chamber 31a, the valve of the first pressure chamber 31a is closed, the valve of the second pressure chamber 31b is opened, and the hydraulic oil is sent from the first intake / exhaust port 11a to the second intake / exhaust port 11b. The pump unit 10 is driven so that Then, the air in the second pressure chamber 31b and the pipe 62 escapes from the valve of the second pressure chamber 31b, and the piston 32 rises and the hydraulic oil filled in the first pressure chamber 31a is pushed out to the pipe 61. It is. When the piston 32 rises to the top dead center, the pressure of the hydraulic oil in the first pressure chamber 31a and the pipe 61 becomes lower than the pressure in the hydraulic oil tank 20, so that the check valve 63 opens and the hydraulic oil tank 20 The hydraulic oil moves to the second pressure chamber 31b through the

pipes

61 and 62. After the second pressure chamber 31b is filled with hydraulic oil, the valve of the second pressure chamber 31b is closed.

Next, a mechanism for vibrating the vibration table 50 in the vibration test apparatus 1 according to the present embodiment will be described. When raising the vibration table 50, the pump unit 10 is driven so that the hydraulic oil moves from the first intake / exhaust port 11a to the second intake / exhaust port 11b. Then, the hydraulic oil is supplied to the second pressure chamber 31b through the pipe 62, the piston 32 is pushed into the first pressure chamber 31a, and the piston rod 33 and the vibration table 50 are raised. The hydraulic oil in the first pressure chamber 31a moves to the pump unit 10 via the pipe 61 as the piston 32 moves, and is sent from the pump unit 10 to the second pressure chamber 31b via the pipe 62.

When the vibration table 50 is lowered, the pump unit 10 is driven so that the hydraulic oil moves from the second intake / exhaust port 11b to the first intake / exhaust port 11a. At this time, since the hydraulic oil is supplied to the first pressure chamber 31a via the pipe 61, the piston 32 is pushed into the second pressure chamber 31a, and the piston rod 33 and the vibration table 50 are lowered. The hydraulic oil in the second pressure chamber 31b moves to the pump unit 10 via the pipe 62 as the piston 32 moves, and is further sent from the pump unit 10 to the first pressure chamber 31a via the pipe 61.

As shown in FIG. 1, the acceleration sensor 3 is attached to the vibration table 50 of the vibration test apparatus 1 according to the present embodiment. The acceleration sensor 3 is connected to the controller 2, and a signal indicating the acceleration detected by the acceleration sensor 3 is supplied to the controller 2. The controller 2 calculates the displacement, speed, or acceleration of the vibration table 50 based on the detection result of the acceleration sensor 3, and sets a target value to be given to the servo amplifier 4 based on the calculation result. send. The servo amplifier 4 generates an alternating current having a period and amplitude set based on a target value designated by the controller 2 from the power supplied from the power supply 5 and outputs the alternating current to the servo motor 12. By the above processing, the vibration table 50 can be vibrated with a predetermined displacement, speed, or acceleration amplitude, for example. Instead of the acceleration sensor 3, a displacement sensor or a speed sensor may be used.

Thus, the vibration test apparatus 1 according to the present embodiment supplies hydraulic oil to the first pressure chamber 31a or the second pressure chamber 31b of the hydraulic cylinder unit 30 by the pump unit 10 that can be driven in both forward and reverse directions. The vibration table 50 is moved in the vertical direction, and the subject W fixed thereon is vibrated.

Furthermore, the vibration test apparatus 1 according to the present embodiment includes a bypass pipe 65 that bypasses the

pipes

61 and 62, and an accumulator 70 provided in the middle of the bypass pipe 65. The accumulator 70 is a pressure vessel in which a layer of a gas having a predetermined pressure (dry nitrogen gas or the like) is formed, and the first pressure chamber 31a or the second pressure chamber of the hydraulic cylinder unit 30 is connected via

pipes

61 and 62. The pressure chamber 31b is pressurized with a constant pressure.

In a configuration that does not include the bypass pipe 65 and the accumulator 70, the pipe on the side not supplied with hydraulic oil (the pipe 61 when the vibration table 50 is raised and the pipe 62 when the vibration table 50 is lowered) has a low pressure close to atmospheric pressure. It has become. Therefore, immediately after the rising and lowering of the vibration table 50 are switched, the pressure of the piping and pressure chamber to which hydraulic fluid is supplied is increased to a high pressure (10 to several tens of MPa) that can move the piston 32 from this low pressure. It takes a time of about several tens of milliseconds to increase the pressure to the maximum. This period is a time lag when the vibration table 50 does not move. Since this time lag has a magnitude that cannot be ignored with respect to the vibration period, the vibration system 50 cannot be vibrated at a high frequency of several tens of Hz or more in the hydraulic system having such a configuration.

In the vibration test apparatus 1 according to the present embodiment, the accumulator is always maintained so that the pressures of the

pipes

61 and 62 and the

pressure chambers

31a and 31b are maintained at a high pressure at which the hydraulic oil can transmit a sufficient driving force to the piston 32. 70 is pressurized. In other words, the accumulator 70 can always transmit a necessary load to the hydraulic oil in the

pressure chambers

31a and 31b and the

pipes

61 and 62 by applying a high back pressure to the first pressure chamber 31a and the second pressure chamber 31b. Kept in a state. For this reason, there is almost no time lag in the configuration without the accumulator 70, and the vibration table 50 can be vibrated at a frequency of several tens of Hz or more. In order to make the time lag as small as possible, the pressure of the gas layer of the accumulator 70, that is, the pressure applied to the hydraulic oil by the accumulator 70 is set to be larger than the minimum pressure required for the movement of the piston 32. . In addition, as the bypass pipe 65, a high-pressure hose or the like that can sufficiently withstand the pressure applied to the hydraulic oil by the accumulator 70 is used.

Also, the piston pump used in the pump body 11 of the pump unit 10 is likely to generate pulsation when driven. In the present embodiment, the pulsation is absorbed by the accumulator 70 provided between the pump unit 10 and the hydraulic cylinder unit 30. 2A, the subject W is sandwiched between the frame 52 and the pressurizing table 50, the vibration table 50 is raised, and a vertical compressive static load is applied to the subject W. As shown in FIG. Useful when performing additional compression tests. Similarly, as shown in FIG. 2B, the above-described feature is that the

jigs

53 and 54 attached to the vibration table 50 and the frame 52 ′ are fixed to the subject, the vibration table 50 is lowered, and the subject W It is also useful when performing a tensile test in which a vertical static load in the vertical direction is applied.

In addition, as shown in FIGS. 2A and 2B, the subject W is arranged between the frame and the vibration table, and the load applied to the subject W is periodically changed by reciprocating the vibration table. It is also possible to perform a vibration test. In that case, a load sensor such as a load cell may be provided on the frame or the vibration table, and the controller 2 may be configured to control the pump unit based on the measurement result of the load sensor. For example, it is possible to perform a so-called fatigue test in which a load is repeatedly applied to the subject W so that the amplitude of the load applied to the subject W is constant.

Next, the results of the vibration test performed by the vibration test apparatus 1 of the present embodiment described above and the results of the vibration test performed by the vibration test apparatus not equipped with an accumulator will be described. FIG. 3 plots the acceleration and displacement of the vibration table measured when the object W is vibrated by giving a target waveform of a sine wave with a frequency of 50 Hz to the vibration test apparatus 1 (example) according to the present embodiment. It is a graph. 4 plots the acceleration and displacement of the vibration table measured when the object W is vibrated by giving a target waveform of a sine wave with a frequency of 50 Hz to a vibration test apparatus (comparative example) without an accumulator. It is a graph. Note that there is no structural difference between the vibration test apparatus of the example and the vibration test apparatus of the comparative example other than the presence or absence of an accumulator. Further, the amplitude and frequency of the alternating current sent from the servo amplifier 4 to the servo motor 12 are not different between the example and the comparative example.

As shown in FIG. 3, in the embodiment, the measured acceleration and displacement waveforms of the vibration table are sinusoidal, and it can be seen that the workpiece W is vibrated in accordance with the target waveform of 50 Hz. On the other hand, as shown in FIG. 4, in the comparative example, the measured acceleration waveform of the vibration table is greatly broken from the sine wave, and the amplitude thereof is less than 1/10 of the embodiment. In the comparative example, the displacement of the vibration table is hardly changed.

Thus, the vibration test apparatus according to the present embodiment can vibrate the subject at a high frequency.

The technical scope of the present invention is not limited to the specific embodiments of the above exemplary embodiments and examples. In the above embodiment, a piston pump is used as the hydraulic pump of the actuator, but the present invention can be implemented using various types of hydraulic pumps other than the piston pump. In some embodiments of the present invention, for example, a rotary pump such as a gear pump or a vane pump is used.

The above exemplary embodiment is an example in which an actuator having a characteristic configuration of the present invention is mounted on a vibration test apparatus. Such an actuator requires high frequency response, low vibration, and low noise. It can be installed in various hydraulic devices and systems. For example, the configuration of the present invention can be applied to a material testing apparatus, a robot arm, or the like.

DESCRIPTION OF SYMBOLS 1 Vibration test apparatus 2 Controller 3 Acceleration sensor 4 Servo amplifier 5 Power supply 10 Pump unit 11 Pump main body 11a 1st intake / exhaust port 11b 2nd intake / exhaust port 12 Servo motor 20 Hydraulic oil tank 30 Hydraulic cylinder unit 31 Sleeve 31a 1st pressure chamber 31b 1st 2 Pressure chamber 32 Piston 33 Piston rod 50 Vibration table 65 Bypass pipe 70 Accumulator

Claims

A hydraulic pump capable of reversing operation having a first suction port and a second suction port;
A hydraulic cylinder unit comprising: a piston; a sleeve whose internal space is divided into a first pressure chamber and a second pressure chamber by the piston; and a piston rod connected to the piston and having a tip protruding outside the sleeve; ,
A first pipe connecting the first pressure chamber and the first intake / exhaust port;
A second pipe connecting the second pressure chamber and the second inlet / outlet;
A hydraulic actuator that moves the piston up and down by alternately applying hydraulic pressure to the first and second pressure chambers by reversing the hydraulic pump;
A bypass pipe connecting the first and second pipes;
The hydraulic actuator further comprising an accumulator provided in the middle of the bypass pipe for applying back pressure to the first and second pressure chambers.
2. The back pressure applied by the accumulator to the first pressure chamber and the second pressure chamber is set to be larger than a minimum pressure required for driving a cylinder of the hydraulic cylinder unit. Hydraulic actuator described in.
The hydraulic actuator according to claim 1 or 2, wherein the hydraulic pump is a piston pump.
The hydraulic actuator according to any one of claims 1 to 3, further comprising a servo motor that drives the hydraulic pump.
A sensor provided in a movable part of the hydraulic actuator, and a controller for controlling the servo motor;
5. The hydraulic actuator according to claim 1, wherein the controller controls the servo motor based on a detection result of the sensor. 6.
The sensor includes any one of a displacement sensor, a speed sensor, an acceleration sensor, and a load sensor,
6. The hydraulic actuator according to claim 5, wherein the controller controls the servo motor to drive the piston in accordance with a predetermined displacement, speed or acceleration waveform based on a detection result of the sensor.
The sensor includes a load sensor;
6. The hydraulic actuator according to claim 5, wherein the controller controls the servo motor based on a detection result of the sensor so that a load detected by the load sensor changes according to a predetermined waveform.
A hydraulic actuator according to claim 1;
A vibration test apparatus comprising a vibration table provided at a tip of the piston rod.
9. The back pressure applied by the accumulator to the first pressure chamber and the second pressure chamber is set larger than the minimum pressure required for driving the cylinder of the hydraulic cylinder unit. The vibration test apparatus described in 1.
10. The vibration test apparatus according to claim 8, wherein the hydraulic pump is a piston pump.
11. The vibration test apparatus according to claim 8, further comprising a servo motor that drives the hydraulic pump.
A sensor provided on the vibration table;
A controller for controlling the servo motor;
The vibration test apparatus according to claim 11, wherein the controller controls the servo motor based on a detection result of the sensor.
The sensor includes a sensor that measures the displacement, speed, or acceleration of the vibration table,
The vibration according to claim 11 or 12, wherein the controller controls the servo motor to drive the vibration table according to a predetermined waveform of displacement, speed, or acceleration based on a detection result of the sensor. Test equipment.
The sensor includes a load sensor that measures a load applied to the subject,
14. The vibration according to claim 11, wherein the controller controls the servo motor to apply a load to the subject according to a predetermined waveform based on a detection result of the sensor. Test equipment.