JP2002130203A - Hydraulically driven apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To promote energy saving by reducing the output power of an electric motor and by keeping down consumption power, since a hydraulic fluid which is supplied to a hydraulic pressure actuator is controlled at a high pressure. SOLUTION: This hydraulic circuit, connecting both ports 2, 3 of a hydraulic pump 1 to both ports 6, 8 of a single-rod cylinder 5, has a booster 15 and a sequence valve 24. The booster 15 supplies the hydraulic fluid, whose pressure is increased by the delivery of the hydraulic fluid discharged from the pump 1, to the single rod cylinder 5. The sequence valve 24 delivers the hydraulic fluid, discharged from the hydraulic pump 1 to the booster 15, when the pressure of the hydraulic fluid from the pump 1 reaches to a set pressure. Accordingly, even if the pump 1 does not discharge a high-pressure fluid, the hydraulic circuit can perform high-pressure control, since the high-pressure fluid increased by the booster 15 can be supplied into the single-rod cylinder 5. Thereby, the electric motor driving the pump 1 is available with small electric power and consumption of power is reduced, energy saving can be promoted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic drive device for driving a hydraulic actuator with hydraulic fluid from a hydraulic pump driven to rotate by an electric motor.

[0002]

2. Description of the Related Art In this type of hydraulic drive apparatus, a hydraulic pump capable of rotating in both directions is rotationally driven by an electric motor such as a servomotor, and both ports of the hydraulic pump are connected to a hydraulic actuator as a hydraulic actuator. A hydraulic circuit is formed by connecting both ports of the cylinder, and hydraulic fluid is discharged from the hydraulic pump by rotation of the electric motor, and the hydraulic cylinder is driven by the hydraulic fluid discharged from the hydraulic pump. Then, the pressure of the hydraulic fluid supplied from the hydraulic pump to the hydraulic cylinder is detected by a pressure detection sensor, the actual value of the detected pressure is compared with a target value, and the electric motor is controlled by a controller. The pressure of the hydraulic fluid supplied to the hydraulic cylinder is precisely controlled. (See, for example, JP-A-2-38020).

[0003]

However, in such a conventional hydraulic driving apparatus, a high-pressure hydraulic pump is rotated to control the pressure of the hydraulic fluid supplied to the hydraulic cylinder at a high pressure. Therefore, an electric motor having a high output power corresponding to the above was required, and the power consumption was large, and it was difficult to achieve energy saving.

The present invention provides a hydraulic drive device capable of reducing the output power of an electric motor and controlling the pressure of a hydraulic fluid supplied to a hydraulic actuator at a high pressure to suppress power consumption and save energy. The task is to provide.

[0005]

Therefore, in the present invention,
A hydraulic circuit is formed by connecting both ports of a hydraulic pump rotatable and bidirectionally rotatable by an electric motor and both ports of a hydraulic actuator, and the hydraulic fluid discharged from the hydraulic pump is driven by the rotation of the electric motor. The hydraulic actuator is driven, the pressure of the hydraulic fluid supplied from the hydraulic pump to the hydraulic actuator is detected by a pressure detection sensor, and the detected actual value is compared with a target value to match the actual value to the target value. A control unit for controlling the rotation speed of the electric motor, wherein the hydraulic circuit includes a pressure intensifier that supplies a hydraulic fluid to the hydraulic actuator by increasing the pressure of the hydraulic fluid discharged from the hydraulic pump, and a hydraulic pump. And a sequence valve for introducing the pressure fluid discharged from the hydraulic pump into the pressure intensifier when the pressure of the pressure fluid discharged from the pressure reaches the set pressure.

According to the present invention, the hydraulic pump is driven to rotate by the electric motor, and the hydraulic fluid discharged from the hydraulic pump is supplied to the hydraulic actuator to drive the hydraulic actuator and the hydraulic pressure is discharged from the hydraulic pump. When the pressure of the liquid reaches the set pressure of the sequence valve, the pressure liquid discharged from the hydraulic pump is introduced into the pressure intensifier, and the pressure intensifier supplies the pressure-intensified liquid to the hydraulic actuator, and supplies the pressure to the hydraulic actuator. The pressure of the increased pressure fluid is detected by a pressure detection sensor, the detected actual value is compared with a target value by a control unit, and the rotation speed of the electric motor is controlled so that the actual value matches the target value. The pressure of the pressurized liquid supplied to the actuator is pressure-controlled at a high pressure. Therefore, even if the hydraulic pump does not discharge the high-pressure hydraulic fluid, the high-pressure hydraulic pressure is increased by the pressure intensifier and supplied to the hydraulic actuator, so that the high-pressure pressure control can be performed. The output power of the electric motor that drives the pump can be small, and the output power of the electric motor can be reduced to control the pressure of the hydraulic fluid supplied to the hydraulic actuator at a high pressure, reducing power consumption and saving energy. Can be achieved.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. In FIG. 1, reference numeral 1 denotes a hydraulic pump capable of rotating in both directions. When the pump rotates forward, the hydraulic fluid sucked from a first port 2 is discharged from a second port 3 as a pressurized liquid, and when the pump rotates reversely, a second port flows. The hydraulic fluid sucked in from 3 is discharged from the first port 2 as a pressure fluid.
Reference numeral 4 denotes an electric motor such as a servo motor, which rotationally drives the hydraulic pump 1. Reference numeral 5 denotes a single rod cylinder having a piston rod 5A as a hydraulic actuator, and connects a head side port 6 to a first port 2 of the hydraulic pump 1 through a first flow path 7.
And the cap-side port 8 is connected to the second port 3 of the hydraulic pump 1 via the second flow path 9, and the piston rod 5A is connected to the cap-side chamber 5B by supplying the pressurized liquid from the cap-side port 8 to the cap-side chamber 5B. The work W is pressed down and the piston rod 5A is raised by the supply of the pressurized liquid from the head side port 6 to the head side chamber 5C to cancel the pressurization of the work W. A hydraulic circuit is configured by connecting both ports 2 and 3 of the hydraulic pump 1 and both ports 6 and 8 of the single rod cylinder 5 via both flow paths 7 and 9.

Reference numeral 7A denotes a branch flow path which branches from the first flow path 7 and connects to a tank T for storing hydraulic fluid. A check valve 10 is provided. 7 is provided so as to allow the flow to the tank 7 and prevent the flow from the first flow path 7 to the tank T. 9A is a branch passage branched from the second flow passage 9 and connected to the tank T. A pilot operated check valve 11 is provided. The pilot operated check valve 11 flows from the tank T to the second flow passage 9. And the pilot flow path 12 is provided in the first flow path 7 (from the location of the check valve 10 in the branch flow path 7A to the first flow path). 7 may be provided, and a part of the pressure fluid discharged from the first port 2 of the hydraulic pump 1 acts as pilot pressure via the pilot flow path 12 so as to be freely opened. Reference numeral 13 denotes a pilot-operated check valve disposed in the second flow path 9 and is a hydraulic pump 1
Is provided in such a direction as to allow the flow from the second port 3 to the cap-side port 8 of the single rod cylinder 5 and to prevent the flow from the cap-side port 8 to the second port 3. 7 (which may be closer to the first flow path 7 than the location of the check valve 10 in the branch flow path 7A), and a part of the hydraulic fluid discharged from the first port 2 of the hydraulic pump 1 is used as a pilot pressure. It is provided so as to be freely opened by acting through the flow path 14.

Reference numeral 15 denotes a pressure intensifier, which has a large-diameter piston 16 therein.
And a small-diameter piston 17 connected by a rod 18 so as to be movable in the axial direction.
A cylinder chamber 20 having a large pressure receiving area is formed on one side in the axial direction, and a pressurizing chamber 21 having a small pressure receiving area is formed on the other side in the axial direction of the small diameter piston 17. An intermediate chamber 22 is defined between the cylinder chamber 20 and the pressure-intensifying piston 19 is moved in the axial direction by introducing a pressurized liquid into the cylinder chamber 20, and according to the ratio of the pressure receiving area between the cylinder chamber 20 and the pressure chamber 21. The pressurized liquid is provided from the pressurizing chamber 21 so as to be freely discharged. Reference numeral 23 denotes a third flow path, which connects between the second port 3 side of the hydraulic pump 1 and the cylinder chamber 20 of the pressure intensifier 15 from the location of the pilot operation check valve 13 in the second flow path 9. I have. Reference numeral 24 denotes a sequence valve disposed in the third flow path 23. The sequence valve 24 is opened when the pressure of the hydraulic fluid discharged from the second port of the hydraulic pump 1 reaches a set pressure.
5 to be introduced into the cylinder chamber 20. A check valve 25 is disposed in the third flow path 23 in parallel with the sequence valve 24, and allows a flow from the cylinder chamber 20 to the second flow path 9 and a flow from the second flow path 9 to the cylinder chamber 20. Is provided in a direction to prevent 26 is a fourth flow path, and the second flow path 9
From the position of the pilot operated check valve 15 to the cap-side port 8 side of the single rod cylinder 5 and the pressure intensifier 15
And the pressurizing chamber 21 are connected. Reference numeral 27 denotes a fifth flow path, which is a pilot operated check valve 11 in the branch flow path 9A.
Is connected between the tank T side and the pressurizing chamber 21 of the pressure intensifier 15 from the disposition point. Reference numeral 28 denotes a check valve disposed in the fifth flow path 27, which is provided in a direction to allow the flow from the branch flow path 9A to the pressurizing chamber 21 and to prevent the flow from the pressurization chamber 21 to the branch flow path 9A. ing. A sixth flow path 34 connects the first flow path 7 to the intermediate chamber 22 of the pressure intensifier 15.

Reference numeral 29 denotes a speed detection sensor such as a rotary encoder for detecting the rotation speed of the electric motor 4. Reference numeral 30 denotes a pressure detection sensor, which is disposed on the cap side port 8 side of the single rod cylinder 5 from the location of the pilot operation check valve 13 in the second flow path 9, and the cap is disposed on the cap side port 8 of the single rod cylinder 5. The pressure of the pressure fluid supplied to the side chamber 5A is detected. A control unit 31 electrically controls the rotation direction and the rotation speed of the electric motor 4. The rotation speed of the electric motor 4 detected by the speed detection sensor 29 is fed back from the feedback wiring 32 and detected by the pressure detection sensor 30. The actual value of the pressure of the pressurized liquid is fed back from the feedback wiring 33. Then, the control unit 31 receives a target value of the pressure (higher than the set pressure of the sequence valve 24) according to the operation command, compares the target value according to the operation command with the actual value of the feedback pressure, and determines that the actual value is the target value. Speed detection sensor 2 to match the value
9 controls the rotation speed of the electric motor 4 which is fed back.

Next, the operation of the above configuration will be described. When the electric motor 4 is rotated forward and the hydraulic pump 1 is rotationally driven in the state shown in FIG. 1 in which the piston rod 5A of the single rod cylinder 5 is at the original position, the hydraulic pump 1 sucks the hydraulic fluid from the first port 2 Is discharged from the second port 3 as a pressurized liquid, which flows through the second flow path 9 and the pilot operated check valve 13 and is supplied from the cap-side port 8 of the one-rod cylinder 5 to the cap-side chamber 5B. The cylinder 5 drives the piston rod 5A downward in FIG. 1, and the hydraulic fluid in the head side chamber 5C is discharged from the head side port 6 and flows through the first flow path 7 to be sucked into the first port 2 of the hydraulic pump 1. Is done. At this time, the amount of hydraulic fluid discharged from the head-side port 6 is smaller than the amount of hydraulic fluid supplied from the cap-side port 8 by an amount corresponding to the volume of the piston rod 5A. When the pressure in the one flow path 7 becomes negative, replenishment is performed from the tank T via the check valve 10. Further, the sequence valve 24 is closed because the pressure of the hydraulic fluid discharged from the hydraulic pump 1 has not reached the set pressure, and the pressure intensifier 15 is in the state of FIG. 1 because the hydraulic fluid is not introduced into the cylinder chamber 20.

The piston rod 5A of the single rod cylinder 5
Is driven downward and comes into contact with the work W, the pressure of the hydraulic fluid discharged from the second port 3 of the hydraulic pump 1 and supplied to the cap side chamber 5B of the single rod cylinder 5 increases. When the increased pressure reaches the set pressure of the sequence valve 24, the sequence valve 24 is opened and the hydraulic pump 1
The pressure fluid discharged from the second port 3 flows through the third flow path 23 and is introduced into the cylinder chamber 20 of the pressure intensifier 15, and the pressure intensifier 15 is operated by the force based on the pressure of the pressure fluid introduced into the cylinder chamber 20. The pressure-increasing piston 19 is axially moved upward in FIG. 1 to reduce the volume of the pressurizing chamber 21 and discharge the pressurized liquid from the pressurizing chamber 21. Is the fourth flow path 2
6, the single rod cylinder 5 is supplied from the cap-side port 8 to the cap-side chamber 5B through the second flow path 9, and the single-rod cylinder 5 is configured to increase the pressure of the pressure supplied to the cap-side chamber 5B to increase the piston pressure. The work W is pressed by the rod 5A. At this time, the working fluid in the intermediate chamber 22 of the pressure intensifier 15 is moved from the sixth flow path 34 to the first flow path 7 as the volume of the intermediate chamber 22 is reduced by the axial movement of the pressure intensifier piston 19 in the upward direction. Flows to Then, the pressure of the pressurized liquid supplied to the cap side chamber 5B is detected by the pressure detection sensor 30 and fed back to the control unit 31. The control unit 31 determines the actual value of the detected pressure and the target value of the pressure according to the operation command. And the speed detection sensor 29 is adjusted so that the actual value matches the target value.
The rotation speed of the electric motor 4 fed back from the controller is controlled, and the pressure of the pressure fluid supplied to the cap side chamber 5B of the single rod cylinder 5 is pressure-controlled at a high pressure.

The piston rod 5A of the single rod cylinder 5
When the electric motor 4 is rotated in the reverse direction in a state where the work W is pressurized, the hydraulic fluid discharged from the first port 2 of the hydraulic pump 1 flows through the first flow path 7 and the head side port 6 of the single rod cylinder 5 Is supplied to the head side chamber 5C, the single rod cylinder 5 drives the piston rod 5A toward the original position in the upward direction in FIG. 1, and the hydraulic fluid in the cap side chamber 5B is discharged from the cap side port 8 to the second flow path. 9, and is sucked into the second port 3 of the hydraulic pump 1 through the pilot operation check valve 13 that has been opened by the pilot pressure acting from the pilot flow path 14. The pressure intensifier 15 is configured such that a part of the pressure fluid flowing through the first flow path 7 is introduced into the intermediate chamber 22 from the sixth flow path 34 and a part of the hydraulic fluid flowing through the second flow path 9 is supplied to the third flow path 7. 2
6, the pressure-intensifying piston 19 is introduced into the pressurizing chamber 21 from FIG.
In the axial direction toward the original position in the downward direction.
0 is discharged to the third flow path 23, and the discharged hydraulic fluid is supplied to the second port 3 of the hydraulic pump 1 through the check valve 25.
Inhaled. At this time, contrary to the above, the amount of hydraulic fluid discharged from the cap-side port 8 is larger than the amount of hydraulic fluid supplied from the head-side port 6 by an amount corresponding to the volume of the piston rod 5A. The hydraulic fluid is discharged to the tank T when the pilot operation check valve 11 is opened by a pilot pressure acting from the pilot flow path 12. When the piston rod 5A of the single rod cylinder 5 is driven to the original position, the electric motor 4 stops.

In this operation, when the pressure of the hydraulic fluid discharged from the second port 3 of the hydraulic pump 1 reaches the set pressure of the sequence valve 24, the sequence valve 24 is opened and the hydraulic fluid flows through the third flow path 23. To the cylinder chamber 20 of the pressure intensifier 15, the pressure intensifier 15 supplies the pressure fluid increased in the pressure chamber 21 to the cap side chamber 5B of the single rod cylinder 5, and the pressure increase supplied to the cap side chamber 5B. The detected pressure of the hydraulic fluid is detected by the pressure detection sensor 30, and the detected actual value and the target value are compared by the control unit 31 to control the rotation speed of the electric motor 4 so that the actual value matches the target value. The pressure of the pressure fluid supplied to the rod cylinder 5 is pressure-controlled at a high pressure. For this reason, even if the hydraulic pump 1 does not discharge the high-pressure hydraulic fluid, the intensifier 1
Since the high-pressure fluid that has been increased in pressure in step 5 is supplied to the single rod cylinder 5 to achieve high-pressure control, the electric motor 4 that rotates the hydraulic pump 1 may have a small output power. The output power of the electric motor 4 can be reduced to control the pressure of the pressurized liquid supplied to the single rod cylinder 1 at a high pressure, and power consumption can be suppressed to save energy. Also, since the hydraulic pump 1 does not need to discharge a high-pressure liquid, it can be a low-pressure pump, which can improve durability and extend the life. When the pressure of the hydraulic fluid discharged from the hydraulic pump 1 reaches the set pressure of the sequence valve 24, the pressure increasing action by the pressure intensifier 15 is obtained. Is supplied from the pressure intensifier 15 to the cap-side chamber 5B, and the amount of pressure liquid supplied from the pressure intensifier 15 to the cap-side chamber 5B of the single rod cylinder 5 may be small.
Can be reduced in size.

In the embodiment, the single rod cylinder 5 is used as a hydraulic actuator, but a double rod cylinder or a hydraulic motor may be used. Further, although the pressure intensifier 15 and the sequence valve 24 are disposed on the second flow path 9 side, the pressure intensifier 15 and the sequence valve 24 are disposed on the first flow path 7 side according to the type and use of the hydraulic actuator to be used. Of course, it is also possible to dispose them in both flow paths 7 and 9.

[0016]

As described above, according to the present invention, a hydraulic circuit is formed by connecting both ports of a hydraulic pump which is rotatably driven by an electric motor and can rotate in both directions and both ports of a hydraulic actuator. The hydraulic actuator is driven by the hydraulic fluid discharged from the hydraulic pump by rotation drive, the pressure of the hydraulic fluid supplied from the hydraulic pump to the hydraulic actuator is detected by a pressure detection sensor, and the actual value and the target value to be detected are determined. And a control unit for controlling the rotation speed of the electric motor so that the actual value coincides with the target value, and the hydraulic circuit is configured to supply the hydraulic fluid increased in pressure by introducing the hydraulic fluid discharged from the hydraulic pump. A pressure intensifier that supplies the pressure actuator and a sequence valve that introduces the pressure fluid that is discharged from the hydraulic pump into the pressure intensifier when the pressure of the pressure fluid that is discharged from the hydraulic pump reaches a set pressure. Even if the hydraulic pump does not discharge the high-pressure hydraulic fluid, the high-pressure hydraulic fluid is supplied to the hydraulic actuator by increasing the pressure by the pressure intensifier. The output power of the electric motor that rotates the motor can be small, and the output power of the electric motor can be reduced to control the pressure of the hydraulic fluid supplied to the hydraulic actuator at a high pressure, reducing power consumption and saving energy. Can be planned. In addition, since the hydraulic pump does not need to discharge a high-pressure hydraulic fluid, a low-pressure hydraulic pump can be used to improve the durability and extend the life. When the pressure of the hydraulic fluid discharged from the hydraulic pump reaches the set pressure of the sequence valve, the pressure booster obtains the pressure increasing effect. This means that the pressurized liquid is supplied from the pressure intensifier to the hydraulic actuator in a small amount, and the pressure intensifier can be reduced in size.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram showing a first embodiment of the present invention and showing a part of a hydraulic drive device as a block.

[Description of Signs] 1 Hydraulic pump 2 1st port (port) 3 2nd port (port) 4 Electric motor 5 Single rod cylinder (hydraulic actuator) 6 Head side port (port) 8 Cap side port (port) 15 Intensifier 24 Sequence valve 30 Pressure detection sensor 31 Control unit

Claims (1)

[Claims] A hydraulic circuit is formed by connecting both ports of a hydraulic pump rotatable in both directions driven by an electric motor and both ports of a hydraulic actuator, and the hydraulic pump is driven by the electric motor to rotate. The hydraulic actuator is driven by the discharged hydraulic fluid, the pressure of the hydraulic fluid supplied from the hydraulic pump to the hydraulic actuator is detected by the pressure detection sensor, and the actual value detected is compared with the target value to determine the actual value. A pressure control device for controlling a rotation speed of the electric motor so as to match a target value, wherein the hydraulic circuit includes a pressure intensifier for supplying a hydraulic fluid to the hydraulic actuator, the hydraulic fluid being increased by introduction of a hydraulic fluid discharged from a hydraulic pump. And a sequence valve for introducing the hydraulic fluid discharged from the hydraulic pump to the pressure intensifier when the pressure of the hydraulic fluid discharged from the hydraulic pump reaches a set pressure.