JP2022019388A - Hydraulic system - Google Patents

Abstract

To propose a hydraulic system which can reduce an impact caused when a driving direction of a movable table is reversed.SOLUTION: A hydraulic system (1) includes: an actuator (10) which drives a movable table (2) in a reciprocating manner and has a first port (10a) and a second port (10b); a first hydraulic pump (20) which supplies a working fluid to the first port (10a); a first motor (21) which drives the first hydraulic pump (20); a second hydraulic pump (30) which supplies the working fluid to the second port (10b); and a second motor (31) which drives the second hydraulic pump (30). The hydraulic system is controlled so that a discharge pressure of one of the first hydraulic pump (20) and the second hydraulic pump (30) lowers and a discharge pressure of the other of the first hydraulic pump (20) and the second hydraulic pump (30) rises in reverse control in which a driving direction of the movable table (2) is reversed.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to hydraulic equipment.

A conventional surface grinder reciprocates a movable table using a hydraulic device including a cylinder having two pressure chambers and a bidirectional hydraulic pump having two ports connected to each of the two pressure chambers of the cylinder. There is something to do (see Patent Document 1). In the above-mentioned surface grinder, when the moving direction of the movable table is reversed, the hydraulic oil flowing out from one pressure chamber of the cylinder flows into the other pressure chamber via a bidirectional hydraulic pump to decelerate the movable table. Therefore, the impact caused by deceleration is suppressed.

Japanese Unexamined Patent Publication No. 2013-226634

In the hydraulic device used in the conventional surface grinding machine, there is a demand for a large capacity to increase the flow rate of hydraulic oil supplied to the cylinder in order to accommodate a large movable table. However, in the above hydraulic device, if it is attempted to connect a plurality of bidirectional hydraulic pumps in parallel to the cylinder, it is difficult to control the plurality of bidirectional hydraulic pumps, so that it is not easy to reduce the impact at the time of reversal. There is a problem. Therefore, the hydraulic device is not suitable for a large-capacity surface grinding machine.

The present disclosure proposes a hydraulic device that can easily reduce an impact when reversing the driving direction of a movable table.

The hydraulic system of the present disclosure is
An actuator that reciprocates a movable table and has a first port and a second port,
When the movable table is driven in the first direction, the first hydraulic pump that supplies hydraulic oil to the first port and the first hydraulic pump
The first motor that drives the first hydraulic pump and
When the movable table is driven in the second direction opposite to the first direction, the second hydraulic pump that supplies hydraulic oil to the second port and the second hydraulic pump.
The second motor that drives the second hydraulic pump and
Equipped with a control device,
In the reversing control that reverses the drive direction of the movable table, the control device reduces the discharge pressure of one of the first hydraulic pump and the second hydraulic pump, and at the same time, the first hydraulic pump and the first hydraulic pump. It is characterized in that the first motor and the second motor are controlled so that the discharge pressure of the other of the two hydraulic pumps rises.

According to the present disclosure, in the reversal control for reversing the drive direction of the movable table, the discharge pressure of one of the first hydraulic pump and the second hydraulic pump decreases, and the other of the first hydraulic pump and the second hydraulic pump. Discharge pressure rises. At this time, since the pressures of the hydraulic oils that oppose each other in the actuator can be controlled by the first hydraulic pump and the second hydraulic pump, the deceleration of the movable table can be controlled accurately. As a result, the impact when reversing the driving direction of the movable table can be easily reduced.

The hydraulic system of one embodiment is
The first relief valve that returns the hydraulic oil discharged from the first port to the oil tank,
In the flow path between the first port and the discharge port of the first hydraulic pump, the first hydraulic pump is arranged at a position closer to the first hydraulic pump than the connection point to which the first relief valve is connected. A first check valve that regulates the flow of hydraulic oil from the port to the first hydraulic pump and
A second relief valve that returns the hydraulic oil discharged from the second port to the oil tank,
In the flow path between the second port and the discharge port of the second hydraulic pump, the second hydraulic pump is arranged at a position closer to the second hydraulic pump than the connection point to which the second relief valve is connected. It is equipped with a second check valve that regulates the flow of hydraulic oil from the port to the second hydraulic pump.

When the first hydraulic pump is driven by returning the hydraulic oil discharged from the first port of the actuator to the first hydraulic pump, the first motor rotates to generate regenerative energy, so that regenerative resistance is required. Become. On the other hand, according to the above embodiment, the flow of hydraulic oil from the first port to the first hydraulic pump is restricted, and the hydraulic oil from the first port is returned to the oil tank via the relief valve. .. As a result, it is difficult for hydraulic oil to flow into the first hydraulic pump from the first port, so that it is not necessary to deal with regenerative energy.

Similarly, when the second hydraulic pump is driven by returning the hydraulic oil discharged from the second port of the actuator to the second hydraulic pump, the second motor rotates to generate regenerative energy, so that regenerative resistance is generated. Is required. On the other hand, according to the above embodiment, the flow of hydraulic oil from the second port to the second hydraulic pump is restricted, and the hydraulic oil from the second port is returned to the oil tank via the relief valve. .. As a result, it is difficult for hydraulic oil to flow into the second hydraulic pump from the second port, so that it is not necessary to deal with regenerative energy.

The hydraulic system of one embodiment is
A third hydraulic pump that supplies hydraulic oil to the first port,
The third motor that drives the third hydraulic pump and
A fourth hydraulic pump that supplies hydraulic oil to the second port,
It is equipped with a fourth motor that drives the fourth hydraulic pump.
The above control device
When the first hydraulic pump supplies hydraulic oil to the first port, the third motor is moved so that the discharge pressure of the third hydraulic pump rises while the discharge pressure of the first hydraulic pump rises. Control and
When the second hydraulic pump supplies hydraulic oil to the second port, the fourth motor is moved so that the discharge pressure of the fourth hydraulic pump rises while the discharge pressure of the second hydraulic pump rises. Control.

According to the above embodiment, the hydraulic oil is supplied from the third hydraulic pump to the first port in addition to the first hydraulic pump, and the hydraulic oil is supplied from the fourth hydraulic pump to the second port in addition to the second hydraulic pump. Therefore, the capacity can be increased by increasing the flow rate of the hydraulic oil supplied to the actuator.

In the hydraulic system of one embodiment,
The inversion control includes a deceleration control for decelerating the movable table.
The above control device
In the deceleration control, when the first hydraulic pump supplies hydraulic oil to the first port, the first motor and the first hydraulic pump are driven so that the third hydraulic pump is driven after the first hydraulic pump is driven. Control 3 motors,
In the deceleration control, when the second hydraulic pump supplies hydraulic oil to the second port, the second motor and the second motor are driven so that the fourth hydraulic pump is driven after the second hydraulic pump is driven. 4 Control the motor.

According to the above embodiment, in the deceleration control, when the first hydraulic pump supplies hydraulic oil to the first port, the third hydraulic pump is driven after the first hydraulic pump is driven. Therefore, when the driving direction of the movable table is reversed from the state in which the movable table is driven by the second hydraulic pump and the fourth hydraulic pump, the pressure of the hydraulic oil supplied from the first hydraulic pump to the first port is second. By countering the pressure on the port side, the movable table is decelerated.

On the other hand, according to the above embodiment, in the deceleration control, when the second hydraulic pump supplies hydraulic oil to the second port, the fourth hydraulic pump is driven after the second hydraulic pump is driven. Therefore, when the driving direction of the movable table is reversed from the state in which the movable table is driven by the first hydraulic pump and the third hydraulic pump, the pressure of the hydraulic oil supplied from the second hydraulic pump to the second port is the first. By countering the pressure on the port side, the movable table is decelerated.

That is, the deceleration of the movable table when the drive direction of the movable table is reversed is controlled by the control of two hydraulic pumps on the drive side and the control of one hydraulic pump on the braking side. As a result, in the reversal control for reversing the drive direction of the movable table, the reversal control can be simplified as compared with the case where the two hydraulic pumps are controlled even on the braking side.

In the hydraulic system of one embodiment,
A third hydraulic pump that supplies hydraulic oil to the actuator,
The third motor that drives the third hydraulic pump and
A switching valve for switching between a first switching position for communicating the third hydraulic pump and the first port and a second switching position for communicating the third hydraulic pump and the second port is provided.
The above control device
When the first hydraulic pump supplies hydraulic oil to the first port, the third motor and the third motor and the like so that the discharge pressure of the third hydraulic pump rises while the discharge pressure of the first hydraulic pump rises. By controlling the above switching valve,
When the second hydraulic pump supplies hydraulic oil to the second port, the third motor and the third motor and the like so that the discharge pressure of the third hydraulic pump rises while the discharge pressure of the second hydraulic pump rises. The switching valve is controlled.

According to the above embodiment, the supply destination of the hydraulic oil from the third hydraulic pump can be switched to either the first port or the second port by the switching valve. As a result, the cost of the hydraulic device can be reduced and the increase in size of the hydraulic device can be suppressed as compared with the case where the hydraulic pump is separately provided to supply the hydraulic oil to each of the first port and the second port. A large capacity can be realized.

In the hydraulic system of one embodiment,
The inversion control includes a deceleration control for decelerating the movable table.
The above control device
In the deceleration control, when the first hydraulic pump supplies hydraulic oil to the first port, the first motor and the first hydraulic pump are driven so that the third hydraulic pump is driven after the first hydraulic pump is driven. Control 3 motors,
In the deceleration control, when the second hydraulic pump supplies hydraulic oil to the second port, the second motor and the second motor are driven so that the third hydraulic pump is driven after the second hydraulic pump is driven. 3 Control the motor.

According to the above embodiment, in the deceleration control, when the first hydraulic pump supplies hydraulic oil to the first port, the third hydraulic pump is driven after the first hydraulic pump is driven. Therefore, when the driving direction of the movable table is reversed from the state in which the movable table is driven by the second hydraulic pump and the third hydraulic pump, the pressure of the hydraulic oil supplied from the first hydraulic pump to the first port is second. By countering the pressure on the port side, the movable table is decelerated.

On the other hand, according to the above embodiment, in the deceleration control, when the second hydraulic pump supplies hydraulic oil to the second port, the third hydraulic pump is driven after the second hydraulic pump is driven. Therefore, when the driving direction of the movable table is reversed from the state in which the movable table is driven by the first hydraulic pump and the third hydraulic pump, the pressure of the hydraulic oil supplied from the second hydraulic pump to the second port is the first. By countering the pressure on the port side, the movable table is decelerated.

That is, the deceleration of the movable table when the drive direction of the movable table is reversed is controlled by the control of two hydraulic pumps on the drive side and the control of one hydraulic pump on the braking side. As a result, in the reversal control for reversing the drive direction of the movable table, the reversal control can be simplified as compared with the case where the two hydraulic pumps are controlled even on the braking side.

It is a schematic block diagram of the large-sized surface grinding machine using the hydraulic system which concerns on 1st Embodiment of this disclosure. It is a graph which shows the operation of the hydraulic system which concerns on 1st Embodiment. (A) It is a schematic block diagram of the hydraulic system which concerns on 1st comparative example. (B) It is a schematic block diagram of the hydraulic system which concerns on 2nd comparative example. (C) It is a schematic block diagram of the hydraulic system which concerns on 3rd comparative example. It is a schematic block diagram of the large-sized surface grinding machine using the hydraulic system which concerns on 2nd Embodiment. It is a schematic block diagram of the large-sized surface grinding machine using the hydraulic system which concerns on 3rd Embodiment. It is a graph which shows the operation of the hydraulic system which concerns on 3rd Embodiment. It is a schematic block diagram of the large-sized surface grinding machine using the hydraulic system which concerns on 4th Embodiment. It is a graph which shows the operation of the hydraulic system which concerns on 4th Embodiment.

Hereinafter, the hydraulic system according to the embodiment of the present disclosure will be described with reference to the accompanying drawings.

[First Embodiment]
FIG. 1 is a schematic block diagram of a large surface grinding machine using the hydraulic device 1 according to the present embodiment.

Referring to FIG. 1, the hydraulic device 1 of the present embodiment includes, for example, a double-acting hydraulic cylinder 10 that reciprocates a movable table 2 having a weight of 20 to 30 tons.

The movable table 2 supports the workpiece on the upper surface. As described above, the movable table 2 is reciprocally driven by the hydraulic cylinder 10. The movable table 2 is provided with a first position detection sensor 3 and a second position detection sensor 4 for detecting the position of the movable table 2. The first position detection sensor 3 is provided at one end of the movable table 2 in the drive direction, and the second position detection sensor 4 is provided at the other end of the movable table 2 in the drive direction. There is. In the following description, the driving direction of the movable table 2 may be referred to as the X direction. Further, the direction from one side to the other side in the X direction may be referred to as the + X direction, and the direction from the other side to the one side in the X direction may be referred to as the −X direction. The + X direction of the present embodiment is an example of the first direction according to the present disclosure, and the −X direction of the present embodiment is an example of the second direction according to the present disclosure.

The hydraulic cylinder 10 includes a cylinder tube 11, a piston 12 that reciprocates in the cylinder tube 11, and piston rods 13A and 13B connected to both end faces of the piston 12. A movable table 2 is connected to the piston rods 13A and 13B. Further, the hydraulic cylinder 10 includes a first port 10a and a second port 10b. The hydraulic cylinder 10 of the present embodiment is an example of the actuator according to the present disclosure.

The hydraulic device 1 supplies hydraulic oil from the oil tank 5 to the first port 10a provided in the hydraulic cylinder 10, and drives the piston 12 of the hydraulic cylinder 10 in the + X direction, and the first hydraulic pump 20 and the first. A first motor 21 for driving the hydraulic pump 20 is provided. The first hydraulic pump 20 has a built-in pressure sensor (not shown) for detecting the discharge pressure and a flow rate sensor (not shown) for detecting the discharge flow rate. The first motor 21 is a variable rotation speed type motor.

The hydraulic device 1 supplies hydraulic oil from the oil tank 5 to the second port 10b provided in the hydraulic cylinder 10, and drives the piston 12 of the hydraulic cylinder 10 in the −X direction, and the second hydraulic pump 30. 2 A second motor 31 for driving the hydraulic pump 30 is provided. The second hydraulic pump 30 has a built-in pressure sensor (not shown) for detecting the discharge pressure and a flow rate sensor (not shown) for detecting the discharge flow rate. The second motor 31 is a variable rotation speed type motor.

The hydraulic device 1 includes a control device 40 that controls the pressure and flow rate of hydraulic oil supplied from the first hydraulic pump 20 and the second hydraulic pump 30 to the hydraulic cylinder 10.

The control device 40 receives a position detection signal indicating the position of the movable table 2 from the first position detection sensor 3 and the second position detection sensor 4, and drives the drive signal for driving the first motor 21 and the second motor 31. Output the drive signal. As a result, the control device 40 controls the rotation speeds of the first hydraulic motor 21 and the second motor 31, respectively.

Hereinafter, the operation of the hydraulic device 1 of the present embodiment will be described with reference to FIGS. 1 and 2.

FIG. 2 is a graph showing the operation of the hydraulic device 1 of the present embodiment. In FIG. 2, the horizontal axis is time and the vertical axis is an arbitrary scale. FIG. 2 shows the discharge pressure of the first hydraulic pump 20, the discharge flow rate of the first hydraulic pump 20, the discharge pressure of the second hydraulic pump 30, and the discharge flow rate of the second hydraulic pump 30, in order from the upper side. Further, FIG. 2 shows the operation of the hydraulic device 1 when the movable table 2 is driven in the + X direction, then the drive direction of the movable table 2 is reversed, and the movable table 2 is driven in the −X direction. ..

Referring to FIG. 2, when the movable table 2 is driven in the + X direction, the control of the hydraulic device 1 is the control of the section A for accelerating the movable table 2 and the control of the section B for driving the movable table 2 at a constant speed. It consists of the control of the section C for decelerating the movable table 2.

Similarly, when the movable table 2 is driven in the −X direction, the control of the hydraulic device 1 is the control of the section D for accelerating the movable table 2 and the control of the section E for driving the movable table E at a constant speed. It consists of the control of the section F for decelerating the table 2.

When the movable table 2 is reciprocated, the control of the sections A to C and the control of the sections D to F are alternately and repeatedly performed. That is, the control of the section D is performed following the control of the section C, and the control of the section A is performed following the control of the section F.

In the control of the section A for accelerating the movable table 2, the control device 40 controls the rotation speed of the first motor 21 so that the discharge pressure of the first hydraulic pump 20 increases and the discharge flow rate increases. On the other hand, in the control of the section A, the control device 40 controls the rotation speed of the second motor 31 so that the discharge pressure of the second hydraulic pump 30 decreases and the discharge flow rate decreases.

The control of the hydraulic device 1 by the control device 40 is performed by controlling the movable table 2 at a constant speed from the control of the section A for accelerating the movable table 2 when the discharge pressure and the discharge flow rate of the first hydraulic pump 20 reach predetermined values. The control shifts to the control of the section B to be driven.

In the control of the section B for driving the movable table 2 at a constant speed, the control device 40 controls the rotation speed of the first motor 21 so that the discharge pressure and the discharge flow rate of the first hydraulic pump 20 are constant. On the other hand, in the control of the section B, the control device 40 stops the second motor 31 so that the discharge pressure and the discharge flow rate of the second hydraulic pump 30 become zero.

In the control of the section B, when the second hydraulic pump 30 is driven by returning the hydraulic oil discharged from the second port 10b of the hydraulic cylinder 10 to the second hydraulic pump 30, the second motor 31 rotates. Regenerative energy is generated. This regenerative energy is absorbed by a regenerative resistor (not shown) provided in the second motor 31.

The control of the hydraulic device 1 by the control device 40 is to control the movable table 2 from the control of the section B that drives the movable table 2 at a constant speed when the deceleration start position of the movable table 2 is detected by the second position detection sensor 4. The control shifts to the control of the section C to be decelerated.

In the control of the section C for decelerating the movable table 2, the control device 40 controls the rotation speed of the first motor 21 so that the discharge pressure of the first hydraulic pump 20 decreases and the discharge flow rate decreases. On the other hand, in the control of the section C, the control device 40 controls the rotation speed of the second motor 31 so that the discharge pressure of the second hydraulic pump 30 increases and the discharge flow rate increases. The control of the section C in the present embodiment is an example of the deceleration control according to the present disclosure.

The control of the hydraulic device 1 by the control device 40 is such that when the drive speed of the movable table 2 becomes zero, the movable table 2 is moved in the −X direction from the control of the section C in which the movable table 2 is driven in the + X direction and decelerated. The control shifts to the control of the section D in which the movable table 2 is accelerated while being driven. That is, the control device 40 reverses the drive direction of the movable table 2 from the + X direction to the −X direction.

In the control of the section D for accelerating the movable table 2, the control device 40 rotates the first motor 21 so that the discharge pressure of the first hydraulic pump 20 decreases and the discharge flow rate decreases following the control of the section C. Control the number. On the other hand, in the control of the section D, the control device 40 controls the rotation speed of the second motor 31 so that the discharge pressure of the second hydraulic pump 30 increases and the discharge flow rate increases following the control of the section C. do.

The control in which the control of the section C of the present embodiment and the control of the section D performed following the control of the section C are combined is an example of the reversal control according to the disclosure.

The control of the hydraulic device 1 by the control device 40 is performed by controlling the movable table 2 at a constant speed from the control of the section D for accelerating the movable table 2 when the discharge pressure and the discharge flow rate of the second hydraulic pump 30 reach predetermined values. The control shifts to the control of the section E to be driven.

In the control of the section E for driving the movable table 2 at a constant speed, the control device 40 stops the first motor 21 so that the discharge pressure and the discharge flow rate of the first hydraulic pump 20 become zero. On the other hand, in the control of the section E, the control device 40 controls the rotation speed of the second motor 31 so that the discharge pressure and the discharge flow rate of the second hydraulic pump 30 are constant.

In the control of the section E, when the first hydraulic pump 20 is driven by returning the hydraulic oil discharged from the first port 10a of the hydraulic cylinder 10 to the first hydraulic pump 20, the first motor 21 rotates. Regenerative energy is generated. This regenerative energy is absorbed by a regenerative resistor (not shown) provided in the first motor 21.

The control of the hydraulic device 1 by the control device 40 is to control the movable table 2 from the control of the section E for driving the movable table 2 at a constant speed when the deceleration start position of the movable table 2 is detected by the first position detection sensor 3. The control shifts to the control of the section F to be decelerated.

In the control of the section F for decelerating the movable table 2, the control device 40 controls the rotation speed of the first motor 21 so that the discharge pressure of the first hydraulic pump 20 increases and the discharge flow rate increases. On the other hand, in the control of the section F, the control device 40 controls the rotation speed of the second motor 31 so that the discharge pressure of the second hydraulic pump 30 decreases and the discharge flow rate decreases. The control of the section F in the present embodiment is an example of the deceleration control according to the present disclosure.

The control in which the control of the section F of the present embodiment and the control of the section A performed following the control of the section F are combined is an example of the reversal control according to the disclosure.

According to the hydraulic device 1 of the present embodiment, the following functions and effects are obtained.

In the reversal control for reversing the drive direction of the movable table 2, the discharge pressure of one of the first hydraulic pump 20 and the second hydraulic pump 30 decreases, and the other of the first hydraulic pump 20 and the second hydraulic pump 30 The discharge pressure rises. At this time, the first hydraulic pump 20 supplies the hydraulic oil to the first port 10a, while the second pump 30 supplies the hydraulic oil to the second port 10b, so that the pressure of the hydraulic oil supplied to the first port 10a. And the pressure of the hydraulic oil supplied to the second port 10b can be controlled individually. Therefore, the deceleration and acceleration of the movable table 2 can be controlled accurately. As a result, the impact when reversing the driving direction of the movable table 2 can be easily reduced.

[First comparative example]
FIG. 3A is a schematic block diagram of the hydraulic device 1001 according to the first comparative example.

Referring to FIG. 3A, the hydraulic device 1001 according to the first comparative example has a hydraulic cylinder 1010, a hydraulic pump 1020 for supplying hydraulic oil for an oil tank 1005 to the hydraulic cylinder 1010, and a fixed hydraulic pump 1020 for driving the hydraulic pump 1020. A motor 1021 having a rotation speed and a direction switching valve 1030 for switching a supply destination of hydraulic oil are provided. Further, the hydraulic device 1001 includes a relief valve 1040 and a flow rate adjusting valve 1050 that return a part of the hydraulic oil discharged from the hydraulic pump 1020 to the oil tank 5.

The direction switching valve 1030 communicates with the first port 1010a of the hydraulic cylinder 1010 and the discharge side of the hydraulic pump 1020 at the switching position on the left side, and communicates with the second port 1010b of the hydraulic cylinder 1010 and the oil tank 1031. It has become. Further, the direction switching valve 1030 communicates the second port 1010b of the hydraulic cylinder 1010 with the discharge side of the hydraulic pump 1020 at the switching position on the right side, and communicates the first port 1010a of the hydraulic cylinder 1010 with the oil tank 1031. It has become like.

In the first comparative example, since the hydraulic pump 1020 is driven by the motor 1021 having a fixed rotation speed, the discharge flow rate of the hydraulic pump 1020 cannot be adjusted. Therefore, a surplus flow is generated in which a part of the hydraulic oil discharged from the hydraulic pump 1020 returns to the oil tank 1005 via the relief valve 1040 and the flow rate adjusting valve 1050. On the other hand, in the hydraulic device 1 according to the first embodiment, the first hydraulic pump 20 is driven by the variable rotation speed type first motor 21, and the second hydraulic pump 30 is driven by the rotation speed variable second motor 31. Is driven, the discharge flow rate of the first hydraulic pump 20 and the discharge flow rate of the second hydraulic pump 30 can be adjusted. As a result, the surplus flow rate can be reduced and the energy saving property can be improved as compared with the first comparative example.

Further, in the first comparative example, the reversing control for reversing the driving direction of the movable table 1002 is performed by operating the direction switching valve 1030 to switch the supply destination of the hydraulic oil from the hydraulic pump 1020. Here, the configuration of the directional switching valve 1030 for appropriately decelerating the movable table 1002 (for example, the shape of the spool) or the configuration of the directional switching valve 1030 for obtaining good responsiveness in reverse control is the movable table 1002. Depends on the speed at which it is driven. Therefore, it is difficult to perform good reversal control in a wide speed range of the movable table 1002 by using the directional control valve 1030.

On the other hand, according to the hydraulic device 1 of the present embodiment, the discharge pressure and the discharge flow rate of the first hydraulic pump 20 and the discharge pressure and the discharge flow rate of the second hydraulic pump 30 can be independently adjusted. By controlling the opposing pressures on the first port 10a side and the second port 10b side of the hydraulic cylinder 10 by the first hydraulic pump 20 and the second hydraulic pump 30, the deceleration and acceleration of the movable table 2 can be accurately controlled. .. As a result, appropriate inversion control is possible in a wide speed range.

[Second comparative example]
FIG. 3B is a schematic block diagram of the hydraulic device 1101 according to the second comparative example.

Referring to FIG. 3B, the hydraulic device 1101 according to the second comparative example includes a hydraulic cylinder 1110, a bidirectional hydraulic pump 1120 that supplies hydraulic oil to the hydraulic cylinder 1110, and a forward rotation that drives the hydraulic pump 1120. It is provided with a variable rotation speed motor 1121 capable of reversing.

In the hydraulic device 1101 of the second comparative example, when a plurality of bidirectional hydraulic pumps 1120 are to be connected in parallel to the hydraulic cylinder 1110 in order to increase the flow rate of the hydraulic oil supplied to the hydraulic cylinder 1110, a plurality of bidirectional hydraulic pumps 1120 are connected. It is necessary to link the discharge and suction timings of the hydraulic pump 1120, which complicates control. Therefore, the hydraulic device 1101 of the second comparative example is not suitable for driving a large-capacity large movable table.

On the other hand, in the hydraulic device 1 of the present embodiment, for example, even when the hydraulic pumps are separately connected in parallel to the first hydraulic pump 20, the first hydraulic pump 20 and the hydraulic pump are connected to each other. There is no need to link them. As a result, the capacity of the hydraulic device 1 can be increased without complicating the control.

Further, since the hydraulic circuit of the hydraulic device 1101 of the second comparative example is a closed circuit, there is a problem that the temperature of the hydraulic oil tends to rise.

On the other hand, since the hydraulic circuit of the hydraulic device 1 of the present embodiment is an open circuit, it is possible to suppress an increase in the temperature of the hydraulic oil as compared with the second comparative example.

[Third comparative example]
FIG. 3C is a schematic block diagram of the hydraulic device 1201 according to the third comparative example.

Referring to FIG. 3C, the hydraulic device 1201 according to the third comparative example includes a hydraulic cylinder 1210, a hydraulic pump 1220 that supplies hydraulic oil for an oil tank 1205 to the hydraulic cylinder 1210, and a rotation that drives the hydraulic pump 1220. It is provided with a variable number motor 1221 and a direction switching valve 1230 for switching the supply destination of hydraulic oil.

At the switching position on the left side, the direction switching valve 1230 communicates the first port 1210a of the hydraulic cylinder 1210 with the discharge side of the hydraulic pump 1220, and communicates the second port 1210b of the hydraulic cylinder 1210 with the oil tank 1231. It has become. Further, the direction switching valve 1230 communicates the second port 1210b of the hydraulic cylinder 1210 with the discharge side of the hydraulic pump 1220 at the switching position on the right side, and communicates the first port 1210a of the hydraulic cylinder 1210 with the oil tank 1231. It has become like.

In the third comparative example, the reversal control for reversing the drive direction of the movable table 1202 is performed by operating the direction switching valve 1230 to switch the supply destination of the hydraulic oil from the hydraulic pump 1220. Here, the configuration of the directional switching valve 1230 for appropriately decelerating the movable table 1202 (for example, the shape of the spool) or the configuration of the directional switching valve 1230 for obtaining good responsiveness in reverse control is the movable table 1202. Depends on the speed at which it is driven. Therefore, it is difficult to perform good reversal control in a wide speed range of the movable table 1202 by using the directional control valve 1230.

On the other hand, according to the hydraulic device 1 of the present embodiment, the discharge pressure and the discharge flow rate of the first hydraulic pump 20 and the discharge pressure and the discharge flow rate of the second hydraulic pump 30 can be independently adjusted. By controlling the opposing pressures on the first port 10a side and the second port 10b side of the hydraulic cylinder 10 by the first hydraulic pump 20 and the second hydraulic pump 30, the deceleration and acceleration of the movable table 2 can be accurately controlled. .. As a result, appropriate inversion control is possible in a wide speed range.

[Second Embodiment]
FIG. 4 is a schematic block diagram of a large surface grinding machine using the hydraulic device 101 according to the second embodiment of the present disclosure. The hydraulic device 101 of the second embodiment has the hydraulic pressure of the first embodiment except that the first relief valve 122, the first check valve 123, the second relief valve 132, and the second check valve 133 are provided. It has the same configuration as the device 101, and FIG. 2 is incorporated. Further, in the second embodiment, the same configurations as those in the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

Referring to FIG. 4, the hydraulic device 101 has a first relief valve 122 for returning the hydraulic oil discharged from the first port 10a of the hydraulic cylinder 10 to the oil tank 5, and a first hydraulic pressure from the first port 10a of the hydraulic cylinder 10. It is provided with a first check valve 123 that regulates the flow of hydraulic oil to the pump 20.

The first port 10a of the hydraulic cylinder 10 is connected to the inlet port 122a of the first relief valve 122. Further, the outlet port 122b of the first relief valve 122 is connected to the oil tank 5. The first relief valve 122 is a pilot-operated relief valve. The discharge side of the first hydraulic pump 20 is connected to the pilot port 122c of the first relief valve 122. As a result, the discharge pressure (pilot pressure) of the first hydraulic pump 20 is supplied to the pilot port 122c of the first relief valve 122, and the first relief valve 122 is controlled.

The first check valve 123 is arranged on the side of the first hydraulic pump 20 with respect to the connection point to which the first relief valve 122 of the flow path between the hydraulic cylinder 10 and the first hydraulic pump 20 is connected. The first port 10a of the hydraulic cylinder 10 is connected to the discharge side of the first hydraulic pump 20 via the first check valve 123.

The hydraulic device 101 includes a second relief valve 132 that returns the hydraulic oil discharged from the second port 10b of the hydraulic cylinder 10 to the oil tank 5, and hydraulic oil from the second port 10b of the hydraulic cylinder 10 to the second hydraulic pump. It is provided with a second check valve 133 that regulates the flow.

The second port 10b of the hydraulic cylinder 10 is connected to the inlet port 132a of the second relief valve 132. Further, the outlet port 132b of the second relief valve 132 is connected to the oil tank 5. The second relief valve 132 is a pilot-operated relief valve. The discharge side of the second hydraulic pump 30 is connected to the pilot port 132c of the second relief valve 132. As a result, the discharge pressure (pilot pressure) of the second hydraulic pump 30 is supplied to the pilot port 132c of the second relief valve 132, and the second relief valve 132 is controlled.

The second check valve 133 is arranged on the second hydraulic pump 30 side with respect to the connection point to which the second relief valve 132 of the flow path between the hydraulic cylinder 10 and the second hydraulic pump 30 is connected. The second port 10b of the hydraulic cylinder 10 is connected to the discharge side of the second hydraulic pump 30 via the second check valve 133.

In the hydraulic device 101 of the present embodiment, when the movable table 2 is driven in the −X direction, when the pressure on the first port 10a side of the hydraulic cylinder 10 becomes equal to or higher than the set pressure of the first relief valve 122, the first relief valve 122 Operates to return the hydraulic oil discharged from the hydraulic cylinder 10 to the oil tank 5.

Similarly, when the movable table 2 is driven in the + X direction, when the pressure on the second port 10b side of the hydraulic cylinder 10 becomes equal to or higher than the set pressure of the second relief valve 132, the second relief valve 132 operates and the hydraulic cylinder The hydraulic oil discharged from No. 10 is returned to the oil tank 5.

The hydraulic device 101 of the second embodiment has the same effect as that of the hydraulic device 101 of the first embodiment.

In the hydraulic device 1 of the first embodiment, when the first hydraulic pump 20 is driven by returning the hydraulic oil discharged from the first port 10a of the hydraulic cylinder 10 to the first hydraulic pump 20, the first motor 21 Rotates to generate regenerative energy, which requires regenerative resistance. On the other hand, according to the hydraulic device 101 of the second embodiment, the flow of hydraulic oil from the first port 10a to the first hydraulic pump 20 is regulated, and the hydraulic oil from the first port 10a is the first. It is returned to the oil tank 5 via the relief valve 122. As a result, it is difficult for hydraulic oil to flow into the first hydraulic pump 20 from the first port 10a, so that it is not necessary to deal with regenerative energy.

Similarly, in the hydraulic device 1 of the first embodiment, when the hydraulic oil discharged from the second port 10b of the hydraulic cylinder 10 is returned to the second hydraulic pump 30, the second hydraulic pump 30 is driven. Since the 2 motor 31 rotates to generate regenerative energy, regenerative resistance is required. On the other hand, according to the hydraulic device 101 of the second embodiment, the flow of the hydraulic oil from the second port 10b to the second hydraulic pump 30 is regulated, and the hydraulic oil from the second port 10b is the second. It is returned to the oil tank 5 via the relief valve 132. As a result, it is difficult for hydraulic oil to flow into the second hydraulic pump 30 from the second port 10b, so that it is not necessary to deal with regenerative energy.

[Third Embodiment]
FIG. 5 is a schematic block diagram of a large surface grinding machine using the hydraulic device 201 according to the third embodiment. The hydraulic device 201 of the third embodiment is the second hydraulic device 201 except for the third hydraulic pump 250, the third motor 251 and the third check valve 252, the fourth hydraulic pump 260, the fourth motor 261 and the fourth check valve 262. It has the same configuration as the hydraulic device 101 of the embodiment. In the third embodiment, the same configurations as those in the second embodiment are designated by the same reference numerals as those in the second embodiment, and detailed description thereof will be omitted.

Referring to FIG. 5, the hydraulic device 201 of the present embodiment supplies hydraulic oil from the oil tank 5 to the first port 10a provided in the hydraulic cylinder 10 to drive the piston 12 of the hydraulic cylinder 10 in the + X direction. A third hydraulic pump 250 and a third motor 251 for driving the third hydraulic pump 250 are provided. Further, the hydraulic device 201 of the present embodiment includes a third check valve 252 that regulates the flow of hydraulic oil from the first port 10a of the hydraulic cylinder 10 to the third hydraulic pump 250.

The third hydraulic pump 250 has a built-in pressure sensor (not shown) for detecting the discharge pressure and a flow rate sensor (not shown) for detecting the discharge flow rate. The third motor 251 is a variable rotation speed type motor.

The discharge side of the third hydraulic pump 250 is connected to the first port 10a side from the connection point to which the first relief valve 122 of the flow path between the first port 10a and the first hydraulic pump 20 is connected.

The third check valve 252 is arranged in the flow path between the hydraulic cylinder 10 and the third hydraulic pump 250. The first port 10a of the hydraulic cylinder 10 is connected to the discharge side of the third hydraulic pump 250 via the third check valve 252.

The hydraulic device 201 of the present embodiment supplies hydraulic oil from the oil tank 5 to the second port 10b provided in the hydraulic cylinder 10, and drives the piston 12 of the hydraulic cylinder 10 in the −X direction. A 260 and a fourth motor 261 for driving the fourth hydraulic pump 260 are provided. Further, the hydraulic device 201 of the present embodiment includes a fourth check valve 262 that regulates the flow of hydraulic oil from the second port 10b of the hydraulic cylinder 10 to the fourth hydraulic pump.

The fourth hydraulic pump 260 has a built-in pressure sensor (not shown) for detecting the discharge pressure and a flow rate sensor (not shown) for detecting the discharge flow rate. The fourth motor 261 is a variable rotation speed type motor.

The discharge side of the fourth hydraulic pump 260 is connected to the second port 10b side from the connection point to which the second relief valve 132 of the flow path between the second port 10b and the second hydraulic pump 30 is connected.

The fourth check valve 262 is arranged in the flow path between the hydraulic cylinder 10 and the fourth hydraulic pump 260. The second port 10b of the hydraulic cylinder 10 is connected to the discharge side of the fourth hydraulic pump 260 via the fourth check valve 262.

The control device 40 of the present embodiment receives a position detection signal indicating the position of the movable table 2 from the first position detection sensor 3 and the second position detection sensor 4, and drives the first motor 21 as a second drive signal. It outputs a drive signal for driving the motor 31, a drive signal for driving the third motor 251 and a drive signal for driving the fourth motor 261. As a result, the control device 40 controls the rotation speeds of the first motor 21, the second motor 31, the third motor 251 and the fourth motor 261.

Hereinafter, the operation of the hydraulic device 201 of the third embodiment will be described with reference to FIGS. 5 and 6. The operation of the hydraulic device 201 according to the third embodiment is the same as the operation of the hydraulic device 1 according to the first embodiment, except for the operations of the third hydraulic pump 250 and the fourth hydraulic pump 260. In the operation of the hydraulic device 201 in the third embodiment, the description of the same configuration as the operation of the hydraulic device 1 in the first embodiment will be omitted.

FIG. 6 is a graph showing the operation of the hydraulic device 201 of the present embodiment. In FIG. 6, the horizontal axis is time and the vertical axis is an arbitrary scale. In FIG. 6, in order from the upper side, the discharge pressure of the first hydraulic pump 20, the discharge flow rate of the first hydraulic pump 20, the discharge pressure of the third hydraulic pump 250, the discharge flow rate of the third hydraulic pump 250, and the second hydraulic pump 30. The discharge pressure, the discharge flow rate of the second hydraulic pump 30, the discharge pressure of the fourth hydraulic pump 260, and the discharge flow rate of the fourth hydraulic pump 260 are shown. Further, FIG. 6 shows the operation of the hydraulic device 201 when the movable table 2 is driven in the + X direction, and then the drive direction of the movable table 2 is reversed and the movable table 2 is driven in the −X direction.

In the control of the section A for accelerating the movable table 2, the control device 40 controls the rotation speed of the first motor 21 so that the discharge pressure of the first hydraulic pump 20 increases and the discharge flow rate increases. Further, in the control of the section A, the control device 40 controls the rotation speed of the third motor 251 so that the discharge pressure of the third hydraulic pump 250 increases and the discharge flow rate increases.

At the start of the section A, the third motor 251 is stopped so that the discharge pressure and the discharge flow rate of the third hydraulic pump 250 become zero.

On the other hand, in the control of the section A, the control device 40 controls the rotation speed of the second motor 31 so that the discharge pressure of the second hydraulic pump 30 decreases and the discharge flow rate decreases. Further, in the control of the section A, the control device 40 stops the fourth motor 261 so that the discharge pressure and the discharge flow rate of the fourth hydraulic pump 260 become zero.

The control of the hydraulic device 201 by the control device 40 is performed by controlling the movable table 2 at a constant speed from the control of the section A for accelerating the movable table 2 when the discharge pressure and the discharge flow rate of the first hydraulic pump 20 reach predetermined values. The control shifts to the control of the section B to be driven.

In the control of the section B for driving the movable table 2 at a constant speed, the control device 40 controls the rotation speed of the first motor 21 so that the discharge pressure and the discharge flow rate of the first hydraulic pump 20 are constant. Further, in the control of the section B, the control device 40 controls the rotation speed of the third motor 251 so that the discharge pressure and the discharge flow rate of the third hydraulic pump 250 are constant.

On the other hand, in the control of the section B, the control device 40 stops the second motor 31 so that the discharge pressure and the discharge flow rate of the second hydraulic pump 30 become zero. Further, in the control of the section B, the control device 40 stops the fourth motor 261 so that the discharge pressure and the discharge flow rate of the fourth hydraulic pump 260 become zero.

In the control of the section B, the hydraulic oil discharged from the second port 10b of the hydraulic cylinder 10 is returned to the oil tank 5 via the second relief valve 132.

The control of the hydraulic device 201 by the control device 40 is to control the movable table 2 from the control of the section B that drives the movable table 2 at a constant speed when the deceleration start position of the movable table 2 is detected by the second position detection sensor 4. The control shifts to the control of the section C to be decelerated.

Referring to FIG. 6, in the control of the section C for decelerating the movable table 2, the control device 40 reduces the discharge pressure of the first hydraulic pump 20 and the discharge flow rate, so that the rotation speed of the first motor 21 decreases. To control. Further, in the control of the section C, the control device 40 controls the rotation speed of the third motor 251 so that the discharge pressure of the third hydraulic pump 250 decreases and the discharge flow rate decreases.

On the other hand, in the control of the section C, the control device 40 controls the rotation speed of the second motor 31 so that the discharge pressure of the second hydraulic pump 30 increases and the discharge flow rate increases. Further, in the control of the section C, the control device 40 stops the fourth motor 261 so that the discharge pressure and the discharge flow rate of the fourth hydraulic pump 260 become zero.

The control of the section C in the present embodiment is an example of the deceleration control according to the present disclosure.

The control of the hydraulic device 201 by the control device 40 is such that when the drive speed of the movable table 2 becomes zero, the movable table 2 is moved in the −X direction from the control of the section C in which the movable table 2 is driven in the + X direction and decelerated. The control shifts to the control of the section D in which the movable table 2 is accelerated while being driven.

In the control of the section D for accelerating the movable table 2, the control device 40 rotates the first motor 21 so that the discharge pressure of the first hydraulic pump 20 decreases and the discharge flow rate decreases continuously from the control of the section C. Control the number. Further, in the control of the section D, the control device 40 stops the third motor 251 so that the discharge pressure and the discharge flow rate of the third hydraulic pump 250 become zero.

At the start of the control of the section D, the third motor 251 is stopped so that the discharge pressure and the discharge flow rate of the third hydraulic pump 250 become zero.

On the other hand, in the control of the section D, the control device 40 controls the rotation speed of the second motor 31 so that the discharge pressure of the second hydraulic pump 30 increases and the discharge flow rate increases continuously from the control of the section C. do. Further, in the control of the section D, the control device 40 controls the rotation speed of the fourth motor 261 so that the discharge pressure of the fourth hydraulic pump 260 increases and the discharge flow rate increases.

At the start of the control of the section D, the fourth motor 261 is stopped so that the discharge pressure and the discharge flow rate of the fourth hydraulic pump 260 become zero. That is, when the second hydraulic pump 30 supplies hydraulic oil to the second port 10b of the hydraulic cylinder 10, the fourth hydraulic pump 260 is driven after the second hydraulic pump 30 is driven.

The control in which the control of the section C of the present embodiment and the control of the section D performed following the control of the section C are combined is an example of the reversal control according to the disclosure.

The control of the hydraulic device 201 by the control device 40 is performed by controlling the movable table 2 at a constant speed from the control of the section D for accelerating the movable table 2 when the discharge pressure and the discharge flow rate of the second hydraulic pump 30 reach predetermined values. The control shifts to the control of the section E to be driven.

In the control of the section E for driving the movable table 2 at a constant speed, the control device 40 stops the first motor 21 so that the discharge pressure and the discharge flow rate of the first hydraulic pump 20 become zero. Further, in the control of the section E, the control device 40 stops the third motor 251 so that the discharge pressure and the discharge flow rate of the third hydraulic pump 250 continue from the control of the section D to zero.

On the other hand, in the control of the section E, the control device 40 controls the rotation speed of the second motor 31 so that the discharge pressure and the discharge flow rate of the second hydraulic pump 30 are constant. Further, in the control of the section E, the control device 40 controls the rotation speed of the fourth motor 261 so that the discharge pressure and the discharge flow rate of the fourth hydraulic pump 260 are constant.

In the control of the section E, the hydraulic oil discharged from the first port 10a of the hydraulic cylinder 10 is returned to the oil tank 5 via the first relief valve 122.

The control of the hydraulic device 201 by the control device 40 is to control the movable table 2 from the control of the section E for driving the movable table 2 at a constant speed when the deceleration start position of the movable table 2 is detected by the first position detection sensor 3. The control shifts to the control of the section F to be decelerated.

In the control of the section F for decelerating the movable table 2, the control device 40 controls the rotation speed of the first motor 21 so that the discharge pressure of the first hydraulic pump 20 increases and the discharge flow rate increases. In the control of the section F, the control device 40 stops the third motor 251 so that the discharge pressure and the discharge flow rate of the third hydraulic pump 250 become zero following the control of the section E.

On the other hand, in the control of the section F, the control device 40 controls the rotation speed of the second motor 31 so that the discharge pressure of the second hydraulic pump 30 decreases and the discharge flow rate decreases. Further, in the control of the section F, the control device 40 controls the rotation speed of the fourth motor 261 so that the discharge pressure of the fourth hydraulic pump 260 decreases and the discharge flow rate decreases.

The control of the section F in the present embodiment is an example of the deceleration control according to the present disclosure.

At the start of the control of the section A following the control of the section F, the third hydraulic motor 251 is stopped so that the discharge pressure and the discharge flow rate of the third hydraulic pump 250 become zero. When the first hydraulic pump 20 supplies hydraulic oil to the first port 10a of the hydraulic cylinder 10, the third hydraulic pump 250 is driven after the first hydraulic pump 20 is driven.

The control in which the control of the section F of the present embodiment and the control of the section A performed following the control of the section F are combined is an example of the reversal control according to the disclosure.

In the third embodiment, the same action and effect as those in the second embodiment are obtained.

The hydraulic oil is supplied from the third hydraulic pump 250 to the first port 10a in addition to the first hydraulic pump 20, and the hydraulic oil is supplied from the fourth hydraulic pump 260 to the second port 10b in addition to the second hydraulic pump 30. There is. As a result, the flow rate of the hydraulic oil supplied to the hydraulic cylinder 10 can be increased to increase the capacity.

When the first hydraulic pump 20 supplies hydraulic oil to the first port 10a, the third hydraulic pump 250 is driven after the first hydraulic pump 20 is driven. Therefore, when the drive direction of the movable table 2 is reversed from the state in which the movable table 2 is driven by the second hydraulic pump 30 and the fourth hydraulic pump 260, the operation supplied from the first hydraulic pump 20 to the first port 10a. The movable table 2 is decelerated by the pressure of the oil countering the pressure on the side of the second port 10b.

On the other hand, when the second hydraulic pump 30 supplies hydraulic oil to the second port 10b, the fourth hydraulic pump 260 is driven after the second hydraulic pump 30 is driven. Therefore, when the drive direction of the movable table 2 is reversed from the state in which the movable table 2 is driven by the first hydraulic pump 20 and the third hydraulic pump 250, the operation supplied from the second hydraulic pump 30 to the second port 10b. The movable table 2 is decelerated by the pressure of the oil countering the pressure on the first port 10a side.

That is, the deceleration of the movable table 2 when the drive direction of the movable table 2 is reversed is controlled by the control of two hydraulic pumps on the drive side and the control of one hydraulic pump on the braking side. As a result, in the reversal control for reversing the drive direction of the movable table 2, the reversal control can be simplified as compared with the case where the two hydraulic pumps are controlled even on the braking side.

[Fourth Embodiment]
FIG. 7 is a schematic block diagram of a large surface grinding machine using the hydraulic device 301 according to the fourth embodiment. The hydraulic device 301 of the fourth embodiment has the same configuration as the hydraulic device 101 of the second embodiment except for the third hydraulic pump 350, the third motor 351, the third check valve 352, and the direction switching valve 370. is doing. In the fourth embodiment, the same configurations as those in the second embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

Referring to FIG. 7, the hydraulic device 301 of the present embodiment has a third hydraulic pump 350 that supplies hydraulic oil from the oil tank 5 to the hydraulic cylinder 10, and a third motor 351 that drives the third hydraulic pump 350. Be prepared. Further, the hydraulic device 301 of the present embodiment regulates the direction switching valve 370 for switching the supply destination of the hydraulic oil discharged from the third hydraulic pump 350 and the flow of the hydraulic oil from the hydraulic cylinder 10 to the third hydraulic pump 350. A third check valve 352 is provided. The directional switching valve 370 of the present embodiment is an example of the switching valve according to the present disclosure.

The third hydraulic pump 350 has a built-in pressure sensor (not shown) for detecting the discharge pressure and a flow rate sensor (not shown) for detecting the discharge flow rate. The third motor 351 is a variable rotation speed type motor.

The directional switching valve 370 of the present embodiment is an electromagnetic pilot switching valve.

The directional control valve 370 is in the first switching position on the left side when the first solenoid 371 is excited and the second solenoid 372 is not excited. At the first switching position, the first port 10a of the hydraulic cylinder 10 and the discharge side of the third hydraulic pump 350 communicate with each other.

On the other hand, when the first solenoid 371 is not excited and the second solenoid 372 is excited, the second switching position is on the right side. At the second switching position, the second port 10b of the hydraulic cylinder 10 and the discharge side of the third hydraulic pump 350 communicate with each other.

The directional control valve 370 is in the neutral position when the first solenoid 371 is not excited and the second solenoid 372 is not excited. In the neutral position, the communication between the third hydraulic pump 350 and the hydraulic cylinder 10 is cut off.

The directional switching valve 370 of the present embodiment has a pilot port 373 for switching the directional switching valve 370 to the first switching position. The pilot port 373 is connected to the discharge side of the third hydraulic pump 350.

The third check valve 352 is arranged in the flow path between the directional control valve 370 and the third hydraulic pump 350. The hydraulic cylinder 10 is connected to the discharge side of the third hydraulic pump 350 via the third check valve 352.

The control device 40 of the present embodiment receives a position detection signal indicating the position of the movable table 2 from the first position detection sensor 3 and the second position detection sensor 4, and drives the first motor 21 as a second drive signal. It outputs a drive signal for driving the motor 31, a drive signal for driving the third motor 251 and an excitation signal for exciting the first solenoid 371 and the second solenoid 372. As a result, the control device 40 controls the rotation speeds of the first motor 21, the second motor 31, and the third motor 251 and the switching position of the directional switching valve 370.

Hereinafter, the control of the hydraulic device 301 of the present embodiment will be described with reference to FIGS. 7 and 8. The operation of the hydraulic device 301 according to the fourth embodiment is the same as the operation of the hydraulic device 1 according to the first embodiment, except for the operation of the third hydraulic pump 350 and the direction switching valve 370. In the operation of the hydraulic device 301 in the fourth embodiment, the description of the same configuration as the operation of the hydraulic device 1 in the first embodiment will be omitted.

FIG. 8 is a graph showing the operation of the hydraulic device 301 of the present embodiment. In FIG. 8, the horizontal axis is time and the vertical axis is an arbitrary scale. In FIG. 8, in order from the upper side, the discharge pressure of the first hydraulic pump 20, the discharge flow rate of the first hydraulic pump 20, the discharge pressure of the second hydraulic pump 30, the discharge flow rate of the second hydraulic pump 30, and the third hydraulic pump 350. The discharge pressure, the discharge flow rate of the third hydraulic pump 350, the excited state of the first solenoid 371, and the excited state of the second solenoid 372 are shown. Further, FIG. 8 shows the operation of the hydraulic device 201 when the movable table 2 is driven in the + X direction, the drive direction of the movable table 2 is reversed, and then the movable table 2 is driven in the −X direction. There is.

In the control of the section A for accelerating the movable table 2, the control device 40 controls the rotation speed of the first motor 21 so that the discharge pressure of the first hydraulic pump 20 increases and the discharge flow rate increases. On the other hand, in the control of the section A, the control device 40 controls the rotation speed of the second motor 31 so that the discharge pressure of the second hydraulic pump 30 decreases and the discharge flow rate decreases.

At the start of the control of the section A, the third motor 351 is stopped so that the discharge pressure and the discharge flow rate of the third hydraulic pump 350 become zero. Further, at the start of the control of the section A, the first solenoid 371 is off and the second solenoid 372 is off.

In the control of the section A, the control device 40 turns on the first solenoid 371 and then drives the third hydraulic pump 350. When the first solenoid 371 is turned on, the direction switching valve 370 switches to the first switching position, and the first port 10a of the hydraulic cylinder 10 and the discharge side of the third hydraulic pump 350 communicate with each other. After that, when the third hydraulic pump 350 is driven, the hydraulic oil discharged from the third hydraulic pump 350 is supplied to the first port 10a of the hydraulic cylinder 10.

In the control of the section A, the control device 40 controls the rotation speed of the third motor 351 so as to increase the discharge pressure of the third hydraulic pump 350 and increase the discharge flow rate.

The control of the hydraulic device 301 by the control device 40 is performed by controlling the movable table 2 at a constant speed from the control of the section A for accelerating the movable table 2 when the discharge pressure and the discharge flow rate of the first hydraulic pump 20 reach predetermined values. The control shifts to the control of the section B to be driven.

In the control of the section B for driving the movable table 2 at a constant speed, the control device 40 controls the rotation speed of the first motor 21 so that the discharge pressure and the discharge flow rate of the first hydraulic pump 20 are constant. On the other hand, in the control of the section B, the second motor 31 is stopped so that the discharge pressure and the discharge flow rate of the second hydraulic pump 30 become zero.

In the control of the section B, the control device 40 controls the rotation speed of the third motor 351 so that the discharge pressure and the discharge flow rate of the third hydraulic pump 350 are constant. Further, in the control of the section B, the first solenoid 371 is on following the control of the section A, and the second solenoid 372 is turned off following the control of the section A.

The control of the hydraulic device 301 by the control device 40 is to control the movable table 2 from the control of the section B that drives the movable table 2 at a constant speed when the deceleration start position of the movable table 2 is detected by the second position detection sensor 4. The control shifts to the control of the section C to be decelerated.

Referring to FIG. 6, in the control of the section C for decelerating the movable table 2, the control device 40 reduces the discharge pressure of the first hydraulic pump 20 and the discharge flow rate, so that the rotation speed of the first motor 21 decreases. To control. On the other hand, in the control of the section C, the control device 40 controls the rotation speed of the second motor 31 so that the discharge pressure of the second hydraulic pump 30 increases and the discharge flow rate increases. The control of the section C in the present embodiment is an example of the deceleration control according to the present disclosure.

In the control of the section C, the control device 40 controls the rotation speed of the third motor 351 so that the discharge pressure of the third hydraulic pump 350 decreases and the discharge flow rate decreases. In the control of the section C, the control device 40 turns off the first solenoid 371 after the discharge pressure and the discharge flow rate of the third hydraulic pump 350 reach zero.

The control of the hydraulic device 301 by the control device 40 is such that when the drive speed of the movable table 2 becomes zero, the movable table 2 is moved in the −X direction from the control of the section C in which the movable table 2 is driven in the + X direction and decelerated. The control shifts to the control of the section D in which the movable table 2 is accelerated while being driven.

In the control of the section D for accelerating the movable table 2, the control device 40 rotates the first motor 21 so that the discharge pressure of the first hydraulic pump 20 decreases and the discharge flow rate decreases following the control of the section C. Control the number. On the other hand, in the control of the section D, the control device 40 controls the rotation speed of the second motor 31 so that the discharge pressure of the second hydraulic pump 30 increases and the discharge flow rate increases continuously from the control of the section C. do.

At the start of the control of the section D, the third motor 351 is stopped so that the discharge pressure and the discharge flow rate of the third hydraulic pump 350 become zero. Further, at the start of the control of the section D, the first solenoid 371 is off and the second solenoid 372 is off.

In the control of the section D, the control device 40 turns on the second solenoid 372 and then drives the third hydraulic pump 350. When the second solenoid 372 is turned on, the direction switching valve 370 switches to the second switching position, and the second port 10b of the hydraulic cylinder 10 and the discharge side of the third hydraulic pump 350 communicate with each other. After that, when the third hydraulic pump 350 is driven, the hydraulic oil discharged from the third hydraulic pump 350 is supplied to the second port 10b of the hydraulic cylinder 10.

In the control of the section D, the control device 40 controls the rotation speed of the third motor 351 so that the discharge pressure of the third hydraulic pump 350 increases and the discharge flow rate increases. When the second hydraulic pump 30 supplies hydraulic oil to the second port 10b of the hydraulic cylinder 10, the third pump 350 is driven after the second hydraulic pump 30 is driven.

The control in which the control of the section C of the present embodiment and the control of the section D performed following the control of the section C are combined is an example of the reversal control according to the disclosure.

The control of the hydraulic device 301 by the control device 40 is performed by controlling the movable table 2 at a constant speed from the control of the section D for accelerating the movable table 2 when the discharge pressure and the discharge flow rate of the second hydraulic pump 30 reach predetermined values. The control shifts to the control of the section E to be driven.

In the control of the section E for driving the movable table 2 at a constant speed, the control device 40 stops the first motor 21 so that the discharge pressure and the discharge flow rate of the first hydraulic pump 20 become zero. On the other hand, in the control of the section E, the control device 40 controls the rotation speed of the second motor 31 so that the discharge pressure and the discharge flow rate of the second hydraulic pump 30 are constant.

In the control of the section E, the control device 40 controls the rotation speed of the third motor 351 so that the discharge pressure and the discharge flow rate of the third hydraulic pump 350 are constant. Further, in the control of the section E, the first solenoid 371 is turned off following the control of the section D, and the second solenoid 372 is turned on following the control of the section D.

The control of the hydraulic device 301 by the control device 40 is to control the movable table 2 from the control of the section E for driving the movable table 2 at a constant speed when the deceleration start position of the movable table 2 is detected by the first position detection sensor 3. The control shifts to the control of the section F to be decelerated.

In the control of the section F for decelerating the movable table 2, the control device 40 controls the rotation speed of the first motor 21 so that the discharge pressure of the first hydraulic pump 20 increases and the discharge flow rate increases. On the other hand, in the control of the section F, the control device 40 controls the rotation speed of the second motor 31 so that the discharge pressure of the second hydraulic pump 30 decreases and the discharge flow rate decreases. The control of the section F in the present embodiment is an example of the deceleration control according to the present disclosure.

In the control of the section F, the control device 40 controls the rotation speed of the third motor 351 so that the discharge pressure of the third hydraulic pump 350 decreases and the discharge flow rate decreases. In the control of the section F, the control device 40 turns off the second solenoid 372 after the discharge pressure and the discharge flow rate of the third hydraulic pump 350 reach zero.

Further, at the start of the control of the section A following the control of the section F, the third motor 351 is stopped so that the discharge pressure and the discharge flow rate of the third hydraulic pump 350 become zero. When the first hydraulic pump 20 supplies hydraulic oil to the first port 10a of the hydraulic cylinder 10, the third hydraulic pump 350 is driven after the first hydraulic pump 20 is driven. Further, at the start of the control of the section A, the first solenoid 371 is off and the second solenoid 372 is off.

The control in which the control of the section F of the present embodiment and the control of the section A performed following the control of the section F are combined is an example of the reversal control according to the disclosure.

In the fourth embodiment, the same action and effect as those in the second embodiment are obtained.

The supply destination of the hydraulic oil from the third hydraulic pump 350 is switched to either the first port 10a or the second port 10b by the directional control valve 370. As a result, the cost of the hydraulic device 301 can be reduced and the size of the hydraulic device 301 is increased as compared with the case where the hydraulic pumps are separately provided to supply the hydraulic oil to each of the first port 10a and the second port 10b. It is possible to realize a large capacity while suppressing the pressure.

When the first hydraulic pump 20 supplies hydraulic oil to the first port 10a, the third hydraulic pump 350 is driven after the first hydraulic pump 20 is driven. Therefore, when the drive direction of the movable table 2 is reversed from the state in which the movable table 2 is driven by the second hydraulic pump 30 and the third hydraulic pump 350, the operation supplied from the first hydraulic pump 20 to the first port 10a. The movable table is decelerated by the pressure of the oil countering the pressure on the side of the second port 10b.

On the other hand, when the second hydraulic pump 30 supplies hydraulic oil to the second port 10b, the third hydraulic pump 350 is driven after the second hydraulic pump 30 is driven. Therefore, when the drive direction of the movable table 2 is reversed from the state in which the movable table 2 is driven by the first hydraulic pump 20 and the third hydraulic pump 350, the operation supplied from the second hydraulic pump 30 to the second port 10b. The movable table 2 is decelerated by the pressure of the oil countering the pressure on the first port 10a side.

That is, the deceleration of the movable table 2 when the drive direction of the movable table 2 is reversed is controlled by the control of two hydraulic pumps on the drive side and the control of one hydraulic pump on the braking side. As a result, in the reversal control for reversing the drive direction of the movable table 2, the reversal control can be simplified as compared with the case where the two hydraulic pumps are controlled even on the braking side.

Although the embodiments have been described above, it will be understood that various modifications of the embodiments and details are possible without departing from the purpose and scope of the claims.

1 Hydraulic device 2 Movable table 3 1st position detection sensor 4 2nd position detection sensor 5 Oil tank 10 Hydraulic cylinder (actuator)
10a 1st port 10b 2nd port 11 Cylinder tube 12 Piston 13A, 13B Piston rod 20 1st hydraulic pump 21 1st motor 30 2nd hydraulic pump 31 2nd motor 40 Control device 101 Hydraulic device 122 1st relief valve 122a Inlet port 122b Outlet port 122c Pilot port 123 1st check valve 132 2nd relief valve 132a Inlet port 132b Outlet port 132c Pilot port 133 2nd check valve 201 Hydraulic device 250 3rd hydraulic pump 251 3rd motor 252 3rd check valve 260 4th Hydraulic pump 261 4th motor 262 4th check valve 301 Hydraulic device 350 3rd hydraulic pump 351 3rd motor 352 3rd check valve 370 Direction switching valve (switching valve)
371 1st solenoid 372 2nd solenoid 373 Pilot port

Claims (6)

An actuator (10) having a first port (10a) and a second port (10b) while reciprocating the movable table (2).
When the movable table (2) is driven in the first direction, the first hydraulic pump (20) that supplies hydraulic oil to the first port (10a) and the first hydraulic pump (20).
The first motor (21) that drives the first hydraulic pump (20) and
When the movable table (2) is driven in the second direction opposite to the first direction, the second hydraulic pump (30) that supplies hydraulic oil to the second port (10b),
The second motor (31) for driving the second hydraulic pump (30) and
Equipped with a control device (40)
In the control device (40), in the reversal control for reversing the drive direction of the movable table (2), the discharge pressure of one of the first hydraulic pump (20) and the second hydraulic pump (30) is set. The first motor (21) and the second motor (31) so that the discharge pressure of the other of the first hydraulic pump (20) and the second hydraulic pump (30) increases as the pressure decreases. A hydraulic device that controls. The first relief valve (122) that returns the hydraulic oil discharged from the first port (10a) to the oil tank (5), and
The first hydraulic pump (20) is located at a connection point to which the first relief valve (122) is connected in the flow path between the first port (10a) and the discharge port of the first hydraulic pump (20). A first check valve (123), which is arranged close to the above and prevents the flow of hydraulic oil from the first port (10a) to the first hydraulic pump (20).
A second relief valve (132) that returns the hydraulic oil discharged from the second port (10b) to the oil tank (5), and
In the flow path between the second port (10b) and the discharge port of the second hydraulic pump (30), the second hydraulic pump (30) is more than the connection point to which the second relief valve (132) is connected. ), A second check valve (133) that regulates the flow of hydraulic oil from the second port (10b) to the second hydraulic pump (30). Hydraulic device. A third hydraulic pump (250) that supplies hydraulic oil to the first port (10a),
The third motor (251) that drives the third hydraulic pump (250) and
A fourth hydraulic pump (260) that supplies hydraulic oil to the second port (10b), and
It is equipped with a fourth motor (261) that drives the fourth hydraulic pump (260).
The control device (40) is
When the first hydraulic pump (20) supplies hydraulic oil to the first port (10a), the third hydraulic pump (250) is discharged while the discharge pressure of the first hydraulic pump (20) is increasing. The third motor (251) is controlled so that the pressure rises.
When the second hydraulic pump (30) supplies hydraulic oil to the second port (10b), the discharge of the fourth hydraulic pump (260) is performed while the discharge pressure of the second hydraulic pump (30) is increasing. The hydraulic device according to claim 1 or 2, which controls the fourth motor (261) so that the pressure rises. The reversal control includes deceleration control for decelerating the movable table (2).
The control device (40) is
In the deceleration control, when the first hydraulic pump (20) supplies hydraulic oil to the first port (10a), the third hydraulic pump (250) is driven after the first hydraulic pump (20) is driven. The first motor (21) and the third motor (251) are controlled so as to be driven.
In the deceleration control, when the second hydraulic pump (30) supplies hydraulic oil to the second port (10b), the fourth hydraulic pump (260) drives the second hydraulic pump (30) and then the fourth hydraulic pump (260). The hydraulic device according to claim 3, wherein the second motor (31) and the fourth motor (261) are controlled so as to be driven. A third hydraulic pump (350) that supplies hydraulic oil to the actuator (10),
The third motor (351) that drives the third hydraulic pump (350) and
The first switching position for communicating the third hydraulic pump (350) and the first port (10a), and the second switching position for communicating the third hydraulic pump (350) and the second port (10b). Equipped with a switching valve (370) to switch between
The control device (40) is
When the first hydraulic pump (20) supplies hydraulic oil to the first port (10a), the discharge of the third hydraulic pump (350) is performed while the discharge pressure of the first hydraulic pump (20) is increasing. The third motor (351) and the switching valve (370) are controlled so that the pressure rises.
When the second hydraulic pump (30) supplies hydraulic oil to the second port (10b), the discharge of the third hydraulic pump (350) is performed while the discharge pressure of the second hydraulic pump (30) is increasing. The hydraulic device according to claim 1 or 2, which controls the third motor (351) and the switching valve (370) so that the pressure rises. The reversal control includes deceleration control for decelerating the movable table (2).
The control device (40) is
In the deceleration control, when the first hydraulic pump (20) supplies hydraulic oil to the first port (10a), the third hydraulic pump (350) drives the first hydraulic pump (20) and then the third hydraulic pump (350). The first motor (21) and the third motor (351) are controlled so as to be driven.
In the deceleration control, when the second hydraulic pump (30) supplies hydraulic oil to the second port (10b), the third hydraulic pump (350) drives the second hydraulic pump (30) and then the third hydraulic pump (350). The hydraulic device according to claim 5, which controls the second motor (31) and the third motor (351) so as to be driven.

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