JP2001208004A - Hydraulic drive unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inexpensively provide a hydraulic drive unit that is capable of high frequency response and can lock when a hydraulic cylinder is not driven. SOLUTION: When type adjustable speed motor 3A is exclusively driven the hydraulic fluid in a reservoir 1 is pressurized by a one-way rotation type hydraulic pump 2A and supplied to a left side pressure chamber of the hydraulic cylinder 6 via a check valve 4A, and then the fluid moves a piston to the right side. The hydraulic fluid in a right side pressure chamber is blocked from flowing into a one-way rotation type hydraulic pump 2B by a check valve 4B, and is returned to the reservoir 1 via a pilot check valve 5B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic control device represented by a hydraulic servo device.

[0002]

2. Description of the Related Art FIG. 8 is a schematic diagram of a typical conventional hydraulic servo system. The hydraulic oil in the oil tank 11 is supplied to a servo valve 13 by a hydraulic pump 12. The servo valve 13 changes the supply direction and supply amount of hydraulic oil according to a command from a servo amplifier (not shown), supplies hydraulic oil to the hydraulic cylinder 14, and returns the return oil from the hydraulic cylinder 14 to the hydraulic tank 11. Excess hydraulic oil not supplied to the servo valve 13 is supplied to the oil tank 11 via the relief valve 15.
Is returned to.

[0003] An accumulator 16 is provided to absorb fluctuations in the pressure of the hydraulic pump 12 and to secure a sufficient amount of oil to operate the hydraulic cylinder 14 as a safety port when the hydraulic pump stops. . Hydraulic pump 1
2 is driven by a constant-speed motor 17. The oil tank 11 is provided with a cooling pipe 18 for cooling hydraulic oil, and is supplied with cooling water.

[0004] Such a conventional hydraulic control device has the following problems. First, the hydraulic pump 12 is rotating even when the cylinder 14 is stopped and the supply of hydraulic oil is not necessary, and the electric motor 1 for driving it is driven.
7 is consuming power. This is not only undesirable from the viewpoint of energy saving, but also causes the hydraulic oil itself to generate heat and the heat of the electric motor 17 to be transmitted to the hydraulic oil via the hydraulic pump 2 to wastefully raise the temperature of the hydraulic oil. The need for extra cooling water is also a problem from the viewpoint of energy saving.

Second, since the pressure loss at the servo valve 13 is large, the energy required for driving the hydraulic cylinder 14 is almost twice as much as that required for the actual operation, and this is not energy saving. Third, servo valve 4
If the cleanliness of the hydraulic oil is not increased, the stick may be raised and become inoperable. Therefore, it is necessary to provide a filter having a fine mesh. In this respect, a pressure loss occurs and energy is lost. Fourth, hydraulic cylinder 1
4. It is difficult to reduce the installation space by integrating the hydraulic pump 12, the electric motor 17, and the oil tank 11.

[0006] As a hydraulic control device that solves such problems, a device using a bidirectional rotary hydraulic pump and a variable speed motor has been developed and used. FIG. 9 shows a schematic configuration thereof. The two outlets of the bidirectional rotary hydraulic pump 19 are connected to the hydraulic cylinder 14. The two outlet pipes of the bidirectional rotary hydraulic pump 19 are connected to the inlet port of the low-pressure priority shuttle valve 21, and the outlet port of the low-pressure priority shuttle valve 21 is connected to the oil tank 11. I have. The bidirectional rotary hydraulic pump 19 is driven by a variable speed motor 20. Variable speed motor 2
By changing the rotation direction of 0, the drive direction of the hydraulic cylinder 14 changes, and by changing the rotation speed, the drive speed of the hydraulic cylinder 14 can be changed.

For example, a bidirectional rotary hydraulic pump 19
However, if it is rotating in the direction in which the hydraulic oil is sent from the lower side to the upper side in FIG. 9, the upper pipe of the pipes connected to the hydraulic cylinder 14 has a high pressure. Of the side ports, the upper port is closed and the lower port is open. Therefore, in the upper pipe, the hydraulic oil does not flow into the low-pressure priority type shuttle valve 21 but is supplied to the upper hydraulic chamber of the hydraulic cylinder 14. On the other hand, since the pressure of the lower pipe becomes negative pressure, the hydraulic oil in the lower hydraulic chamber of the hydraulic cylinder 14 is sucked into the bidirectional rotary hydraulic pump 19. At the same time, the hydraulic oil in the oil tank 11 flows backward from the outlet port of the low-pressure priority shuttle valve 21 via the lower inlet port and is supplied to the bidirectional rotary hydraulic pump 19. Thereby, even if the hydraulic oil leaks, the shortage of the hydraulic oil is compensated.

According to such a hydraulic drive device, since the servo valve can be omitted, the price of the device can be reduced and the necessity of increasing the cleanliness of the oil is eliminated. In addition, since a large oil tank is not required, the size of the entire apparatus is reduced, and the hydraulic cylinder 14, the bidirectional rotary hydraulic pump 19, and the variable speed motor 20 can be integrated. Further, when the hydraulic cylinder is not driven, the driving of the variable speed motor is stopped, so that energy can be saved.

[0009]

However, the hydraulic drive device using the bidirectional rotary hydraulic pump and the variable speed motor has the following problems. When changing the driving direction of the hydraulic cylinder, the rotation speed of the variable speed motor once becomes zero and then rotates in the opposite direction, so that a delay during that time is inevitable. Therefore, high-frequency response is impossible. FIG. 10 shows this state. FIG. 10 shows the relationship between the rotational speed of the variable speed motor and the position of the hydraulic cylinder when the hydraulic cylinder is alternately moved in the left-right direction. As shown in the figure,
In order to change the moving direction of the hydraulic cylinder, it is necessary to set the speed of the variable speed motor to zero once and then rotate the motor in the reverse direction, so that a time delay indicated by τ in the figure is inevitable. The use of a bi-directional rotary hydraulic pump results in an expensive system. When the bidirectional rotary hydraulic pump repeats forward and reverse rotation at high speed, a large repetitive stress is applied to the shaft connected to the motor, and the life of the shaft is shortened. In addition, cavitation of oil may occur inside the pump, resulting in abnormal hydraulic drive.

When controlling the position of the hydraulic cylinder, it is necessary to reduce the speed of the variable speed motor as the deviation becomes smaller. Therefore, a variable speed motor having a wide speed control range is required, and an encoder having a large range capability is required to detect the speed. Therefore, the price of the device becomes high. When the hydraulic cylinder is externally loaded in one direction, stopping the variable speed motor changes the position of the hydraulic cylinder. To correct it, the variable speed motor needs to be turned on and off intermittently. In addition, since the hydraulic cylinder cannot be locked at the time of a power failure, a countermeasure is required separately.

The present invention has been made to solve such a problem, and provides a hydraulic drive device capable of high-frequency response, inexpensive, and capable of being locked when the hydraulic cylinder is not driven. That is the task.

[0012]

A first means for solving the above problems is a one-way rotary hydraulic pump with a check valve connected to a driven object, and the one-way rotary hydraulic pump. A one-way rotary variable speed motor that drives
An input port is connected to a pair of pipes between the one-way rotary hydraulic pump and the driven object, and a pair of pilot operated two-way valves are connected to an output port to a return pipe. The pilot port of the pilot operated two-way valve is connected to the outlet pipe of the one-way rotary pump with a check valve of the pipe to which the input port of the other pilot operated two-way valve is connected. (Claim 1).

In the present specification, the pilot operated two-way valve is a valve that permits the passage of hydraulic oil from an input port to an output port when a predetermined or more hydraulic pressure is applied to a pilot port. In the steady state, the passage of hydraulic oil from the input port to the output port is not allowed in the steady state, the passage of hydraulic oil from the output port to the input port is allowed, and when a predetermined oil pressure or more is applied to the pilot port, the input There is a pilot check valve that allows the passage of hydraulic oil from the port to the output port.

In this means, one-way rotary hydraulic pumps are used as a pair, and the driven bodies (hydraulic cylinders and the like) are driven in different directions by the respective hydraulic pumps. When one hydraulic pump is driven and the other is not driven, hydraulic oil from the driven hydraulic pump is supplied to the driven body through the check valve to drive the driven body. . Return oil from the driven body does not return to the other hydraulic pump side by the check valve, but returns to the oil tank from the return pipe through the pilot operated two-way valve. When both hydraulic pumps are driven, the low pressure side is connected to the return pipe via the pilot operated two-way valve, so that the driven body is driven by the high pressure side pump. When both pumps are not driven, the driven device is locked by the action of the check valve and the pilot operated two-way valve.

In this specification, "with check valve" does not necessarily mean that the check valve and the object are integrated, but the check valve and the object are connected by piping. It is a concept that includes things.

In this means, since the one-way rotary hydraulic pump is driven by the one-way rotary variable speed motor, the one-way variable speed motor is driven at a speed corresponding to the positional deviation of the driven body. , Precise position control becomes possible.

Further, in this means, since the rotation direction of the motor and the hydraulic pump is one direction, the stress load applied to the coupling shaft between the motor and the hydraulic pump and the hydraulic pump is reduced, so that their life is extended. Can be. Further, the price of the one-way rotary hydraulic pump is 1/5 to 1/10 or less of the price of the two-way rotary hydraulic pump, so that even if two pumps are used, the overall price is low.

Further, since the hydraulic pumps are used as a pair, the rotation speed control range of one motor may be about 1/10 of the maximum rotation speed, and the detection accuracy of the speed detector and the motor speed control accuracy are rough. May be. Therefore, inexpensive variable speed motors and encoders can be used, and inexpensive control methods and control devices can be adopted.

Further, the load applied to each motor per unit time is ２ of that when one pump is used, and the amount of heat radiation is relatively increased by that amount, and the temperature rise is reduced. Therefore, the rise in oil temperature is also smaller than when one pump is used. Further, although the number of parts is increased as compared with the case where one pump is used, the unit parts are small, so that integration with a driven body or the like is sufficiently possible.

A second means for solving the above-mentioned problem is as follows.
A pair of one-way rotary hydraulic pumps connected to the driven object, a one-way rotary variable speed motor for driving the one-way rotary hydraulic pump, respectively, and between the one-way rotary hydraulic pump and the driven object. And a pair of pilot operated two-way valves each having an input port connected to the pair of pipes and an output port connected to the return pipe. The pilot port of the pair of pilot operated two-way valves is The hydraulic drive device according to claim 2, wherein the input port of the pilot operated two-way valve is connected to the outlet pipe of a one-way rotary pump with a check valve.

This means is obtained by removing the check valve from the first means, and is effective in a system which does not need to be locked when the hydraulic pump stops. At the time of normal operation, even if there is no check valve, there is no problem because the hydraulic oil on the low pressure side is returned to the oil tank through the pilot operated two-way valve. Other operations are the same as those of the first means. In the present means, since there is no check valve, the device can be simplified accordingly.

A third means for solving the above-mentioned problem is:
The first means or the third means, wherein when the driving direction of the driven object is changed, before the rotation of one variable speed motor stops, the function of starting the rotation of the other variable speed motor is started. (Claim 3).

In this means, when changing the driving direction of the driven object, the rotation of the other motor is started at a timing before an instruction to decelerate or stop is given to one motor. Therefore, at the timing when the other motor starts rotating, the rotation of the motor instructed to decelerate or stop is not stopped yet, but the hydraulic oil on the high pressure side is driven by the operation of the pilot operated two-way valve. Hydraulic oil supplied to the body and on the low pressure side is returned to the oil tank, so that both pumps do not interfere with each other and an excessive load is applied. If the instruction of deceleration or stop is given to other motors almost simultaneously with the rotation of the motor that has started to rotate to the command value, the switching is performed without delay at the time of switching. Therefore, the frequency response speed can be increased.

A fourth means for solving the above-mentioned problem is:
A pair of two-way solenoid valves connected to the driven object, a one-way rotary hydraulic pump with a check valve connected to the pair of two-way solenoid valves, and a one-way driving the one-way rotary hydraulic pump A rotary variable speed motor, and a pair of pilot operated two-way valves each having an input port connected to a pair of pipes between the two-way solenoid valve and the driven object and an output port connected to a return pipe. The pilot port of the pair of pilot operated two-way valves is connected to the outlet pipe of the two-way solenoid valve of the pipe to which the input port of the other pilot operated two-way valve is connected. (Claim 4).

In this means, the hydraulic oil from the one-way rotary hydraulic pump is supplied to the driven object through the check valve and the two-way solenoid valve on the open side to drive the driven object. I do. Return oil from the driven object is returned to the oil tank through the pilot operated two-way valve. When both solenoid valves are transiently opened when switching the two-way solenoid valve, the driven body is driven by the high pressure side because the low pressure side is connected to the return pipe via the pilot operated two-way valve. Is done. The speed control of the driven body is performed by operating the speed of the one-way rotating variable speed motor. When the hydraulic pump is not driven, the driven device is locked by the operation of the check valve and the pilot operated two-way valve.

The present means is slightly inferior in control accuracy to the first means, but only by adding two two-way solenoid valves,
Since only one pump and one motor are required, the system can be realized at low cost. Further, it is possible to reduce the cost as compared with a conventional one using a bidirectional rotary hydraulic pump and a variable speed motor, and it is possible to reliably lock the motor when stopped.

A fifth means for solving the above problem is as follows.
A pair of two-way solenoid valves connected to the driven object, a one-way rotary hydraulic pump connected to the pair of two-way solenoid valves, and a one-way rotary variable speed driving the one-way rotary hydraulic pump A motor and a pair of pilot operated two-way valves each having an input port connected to a pair of pipes between the two-way solenoid valve and the driven object and an output port connected to a return pipe; The hydraulic drive is characterized in that the pilot port of the pair of pilot operated two-way valves is connected to the outlet pipe of the two-way solenoid valve of the pipe to which the input port of the other pilot operated two-way valve is connected. An apparatus (claim 5).

In this means, the check valve is removed from the fourth means. Even in such a case, when the pump is stopped, both two-way solenoid valves are closed. In this case, an effect equivalent to that of the fourth means can be obtained.

A sixth means for solving the above-mentioned problem is:
A three-way solenoid valve having two output ports connected to a driven object,
A one-way rotary hydraulic pump with a check valve connected to the inlet port of the three-way solenoid valve, a one-way rotary variable speed motor driving the one-way rotary hydraulic pump, An input port is connected to a pair of pipes between each outlet port and the driven object, and a pair of pilot operated two-way valves are connected to an output port to a return pipe. The pilot port of the two-way valve
A hydraulic drive device (claim 6), characterized in that the input port of the two-way pilot operated valve on the other side is connected to the outlet pipe of a three-way solenoid valve.

In this means, the two two-way solenoid valves in the fourth means are replaced by one three-way solenoid valve. Therefore, it has the same function and effect as the fourth means.

A seventh means for solving the above problem is as follows.
A three-way solenoid valve having two output ports connected to a driven object,
A one-way rotary hydraulic pump connected to the inlet port of the three-way solenoid valve, a one-way rotary variable speed motor driving the one-way rotary hydraulic pump, and each outlet port of the three-way solenoid valve An input port is connected to each of a pair of pipes between the pump and the driven object, and a pair of pilot operated two-way valves are connected to an output port to a return pipe. The pilot port is a hydraulic drive device wherein the input port of the two-way pilot operated valve on the other side is connected to the outlet pipe of a three-way solenoid valve. .

In this means, the two two-way solenoid valves in the fifth means are replaced with one three-way solenoid valve. Therefore, it has the same function and effect as the fifth means.

Eighth means for solving the above-mentioned problem is:
A pair of pilot operation check valves each having an input port connected to a driven object and two output ports connected to two output ports of a four-way solenoid valve, and an input port of the four-way solenoid valve A one-way rotary hydraulic pump connected to the pump, and a one-way rotary variable speed motor that drives the one-way rotary hydraulic pump. The pilot port of the pair of pilot operation check valves is The pilot-operated check valve is connected to the pipe to which the output port is connected, and the four-way solenoid valve has the inlet port closed and the two outlet ports connected to the return pipe when in the neutral position. A hydraulic drive device characterized by the following.
(Claim 8).

In this means, when the four-way switching valve is driven in the first direction or the second direction, the hydraulic oil from the one-way rotary hydraulic pump is supplied via the pilot-operated check valve, respectively. The hydraulic fluid is supplied to the left and right hydraulic chambers of the driven object (the flow of hydraulic oil of the pilot operation check valve is in the forward direction). The hydraulic pressure in the opposite hydraulic chamber is returned to the hydraulic tank from the return pipe through the pilot operation check valve. (In the pilot operation check valve, the hydraulic pressure in the pilot port increases because the hydraulic pressure in the piping on the other side is high. Permissible.).

When the four-way switching valve is in the neutral position, the hydraulic oil from the one-way rotary hydraulic pump is blocked, and the output ports of the two pilot operated two-way valves are connected to the return pipe. However, the movement of the driven object is blocked by the operation of the pilot operation check valve as described above. In this means, it goes without saying that the return port of the four-way solenoid valve is connected to the oil tank via the return pipe.

A ninth means for solving the above problems is as follows:
A four-way solenoid valve having two output ports connected to a driven object,
A one-way rotary hydraulic pump connected to an inlet port of the three-way solenoid valve, and a one-way rotary variable speed motor driving the one-way rotary hydraulic pump; Is a hydraulic drive device wherein all ports are closed when in a neutral position.

In this means, when the four-way switching valve is driven in the first direction or the second direction, the hydraulic oil from the one-way rotary hydraulic pump is supplied to the left and right hydraulic chambers of the driven object, respectively. The hydraulic pressure in the opposite hydraulic chamber is
It is returned from the return pipe to the hydraulic tank through the one-way valve. When the four-way switching valve is in the neutral position, the hydraulic oil from the one-way rotary hydraulic pump is blocked, and the movement of the driven object is blocked by the four-way switching valve. In this means, it goes without saying that the return port of the four-way solenoid valve is connected to the oil tank via the return pipe.

According to a tenth means for solving the above-mentioned problems, a pair of pilot operation two-way valves of the first means to the eighth means are replaced with one pilot operation switching valve which performs the same operation. (Claim 10).

In this specification, the pilot switching valve is a first switching valve.
, Two input ports, A and B, and one output port,
And two pilot ports P _A, has a P _B, when the oil pressure according to the pilot port P _A is higher than the hydraulic pressure applied to the pilot port P _B leads to the input port B output port, the hydraulic pressure applied to the pilot port P _A when less than the hydraulic pressure applied to the pilot port P _B refers to those input port a connected to the output port.

Using such a pilot switching valve, the input port A and the pilot port P _A are connected to a pipe connecting to one hydraulic chamber of the cylinder, and the input port B and the pilot port P _B are connected to one hydraulic chamber of the cylinder. By connecting to the pipe, the same operation as the first means to the seventh means can be performed.

Second, two input ports, A and B, and 2
Two output ports C and D and two pilot ports P
_A, has a P _B, when the oil pressure according to the pilot port P _A is higher than a predetermined value than the hydraulic pressure applied to the pilot port P _B, the hydraulic pressure according to the pilot port P _B is higher than a predetermined value than the hydraulic pressure applied to the pilot port P _A In some cases, the input port A is connected to the output port C, and the input port B is connected to the output port D. Otherwise, the output port is blocked.

[0042] Using such a pilot selector valve, the input port A, the two output ports of the 4-way solenoid valve B, to connect the output port C, and D to the driven object, an input port pilot port P _A By connecting the pilot port P _B to the pipe connected to the input port B to the pipe connected to the port B, the same operation as that of the eighth means can be performed.

[0043]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a system diagram showing an example of a hydraulic drive device according to an embodiment of the present invention. In FIG. 1, 1 is an oil tank, 2A and 2B are one-way rotary hydraulic pumps, 3A and 3B are one-way rotary variable speed motors, 4A,
4B is a check valve, 5A and 5B are pilot check valves, 6
Is a hydraulic cylinder.

In the pressure chamber on the left side of the hydraulic cylinder 6, the hydraulic oil from the oil tank 1 is supplied with a one-way rotary hydraulic pump 2.
A, is supplied through the check valve 4A, the right pressure chamber,
The hydraulic oil from the oil tank 1 is supplied to the one-way rotary hydraulic pump 2
B, supplied through the check valve 3B.
The piping from the check valves 4A, 4B to the hydraulic cylinder 6 is branched on the way, and the pilot check valves 5A,
5B is connected to the input port. The pilot check valves 5A and 5B are opened when the pressure on the input port side is lower than the pressure on the pilot port side, flow the hydraulic oil on the input port side to the output port, and closed in the opposite case.

The one-way rotary hydraulic pumps 2A and 2B are driven by one-way rotary variable speed motors 3A and 3B, respectively. In this embodiment, a brushless servomotor of a 120 ° energized rectangular wave PWM drive system is used as the one-way rotating type variable speed motors 3A and 3B to reduce the size.

When a high-speed response is not required, only the one-way rotary variable speed motor 3A is required to move the hydraulic cylinder 6 to the right, and only the one-way rotary variable speed motor 3B is required to move the hydraulic cylinder 6 to the left. Drive. The speed of each one-way rotary variable speed motor is made variable according to the speed at which the hydraulic cylinder 6 is to be moved.

When only the one-way rotation type variable speed motor 3A is driven, the hydraulic oil in the oil tank 1 is pressurized by the one-way rotation type hydraulic pump 2A, and the hydraulic oil is supplied to the hydraulic cylinder 6 via the check valve 4A. The pressure is supplied to the left pressure chamber to move the piston to the right. The hydraulic oil in the right pressure chamber is prevented from flowing into the one-way rotary hydraulic pump 2B by the check valve 4B, and is returned to the oil tank 1 through the pilot check valve 5B. When only the one-way rotary variable speed motor 3B is driven, the reverse operation is performed.

It is assumed that when both the one-way rotary variable speed motors 3A and 3B are stopped, an external force for driving the hydraulic cylinder 6 to the left is applied to the rod. In this case, the pressure in the left pressure chamber of the hydraulic cylinder 6 increases, and the pressure in the right pressure chamber decreases. Therefore, the pilot check valve 5A is closed, and the check valve 4A is also closed.

Accordingly, the hydraulic oil in the pressure chamber on the left side of the hydraulic cylinder 6 is in a blocked state, and the hydraulic cylinder 6 is locked. At this time, the pilot check valve 5B is opened, and the operating oil in the pressure chamber may leak,
The installation position of the pilot check valves 5A and 5B is located above the hydraulic cylinder 6, and the pilot check valves 5A and 5B
By placing the pipe from the outlet port of 5B in the oil of the oil tank 1 so that the hydraulic oil is pushed up by the siphon phenomenon, such a situation can be easily prevented. One-way rotating type variable speed motor 3A,
When both rods 3B are stopped and an external force driving the hydraulic cylinder 6 to the right is applied to the rod, the movement of the hydraulic cylinder 6 is similarly locked. If it is not necessary to lock the movement of the hydraulic cylinder 6,
The check valves 4A and 4B can be omitted.

Frequently moving the hydraulic cylinder 6 left and right,
When a high-speed response is required, the response speed can be increased by driving the one-way rotary variable speed motors 3A and 3B in an overlapping manner. This is shown in FIG.
As shown in the figure, when the hydraulic cylinder 6 which has been driven in the right direction is reversed and driven in the left direction, before the stop command is given to the one-way rotary variable speed motor 3A, the one-way rotary variable speed motor is driven. When the rotation command is given to the one-way rotation type variable speed motor 3B, the rotation speed of the one-way rotation type variable speed motor 3B reaches the command value at the time when the stop command is given to the one-way rotation type variable speed motor 3A. To

Then, at the stage where the hydraulic pressure of the one-way rotary hydraulic pump 2A starts to decrease, the hydraulic pressure of the one-way rotary hydraulic pump 2B has reached a predetermined value, and the pilot check valve 5A is opened and 5B is opened. Upon closing, the hydraulic cylinder 6 is immediately driven to the left.

Similarly, when the hydraulic cylinder 6 that has been driven in the left direction is reversed and driven in the right direction, before the stop command is given to the one-way rotary variable speed motor 3B, the one-way rotary variable speed motor 3B is turned off. At the time when the rotation command is given to the one-way rotation type variable speed motor 3B and the stop command is given to the one-way rotation type variable speed motor 3B, the rotation speed of the one-way rotation type variable speed motor 3A has reached the command value. To

As can be seen from a comparison between FIG. 2 and FIG. 9, by adopting such a control method, the delay time τ seen in FIG. 9 is eliminated in FIG. 2, and the response speed is improved accordingly. I do.

FIG. 3 is a system diagram showing another example of the hydraulic drive device according to the embodiment of the present invention. In the following drawings, the same components as those shown in the preceding drawings in the section of the embodiment of the invention are denoted by the same reference numerals, and description thereof may be omitted. 2 is a one-way rotary hydraulic pump, 3 is a one-way rotary variable speed motor, 4 is a check valve, and 7A and 7B are two-way solenoid valves.

The hydraulic oil in the oil tank 1 is pressurized by the one-way rotary hydraulic pump 2 and supplied to the hydraulic cylinder 6 through one of the two-way solenoid valves 7A and 7B. The two-way solenoid valves 7A and 7B are not opened at the same time. Hydraulic oil in the hydraulic chamber of the hydraulic cylinder 6 connected to the open two-way solenoid valve and the opposite solenoid valve is returned to the oil tank 1 through the pilot check valve 5A or 5B. The operating speed of the hydraulic cylinder 6 is controlled by operating the rotating speed of the one-way rotary variable speed motor 3.

When the two-way solenoid valves 7A and 7B are switched, there may be a case where both are half-opened transiently. In this case, too, the low pressure side is returned to the oil tank 1 through the pilot check valve 5A or 5B. Does not occur.

When an external force is applied to move the hydraulic cylinder 6 to either direction while the one-way rotary hydraulic pump 2 is stopped, even if one of the two-way solenoid valves 7A and 7B is open, Stop valve 4 and pilot check valve 5A, 5
The lock of the movement of the hydraulic cylinder 6 by the block B is the same as that described in the embodiment shown in FIG. If the two-way solenoid valves 7A and 7B are closed when the one-way rotary variable speed motor 3 is stopped, the check valve 4 can be omitted. Also, when it is not necessary to lock the hydraulic cylinder 6, the check valve 4
Can be omitted.

FIG. 4 is a system diagram showing a third example of the hydraulic drive device according to the embodiment of the present invention. 8 is a three-way solenoid valve. In this embodiment, a pair of two-way solenoid valves of the embodiment shown in FIG. 3 is replaced by one three-way solenoid valve 8, and the operation thereof will be described with reference to FIG. FIG.
It will be obvious to those skilled in the art from the above description, and thus the description is omitted. In FIG. 4, there is no neutral position as a three-way solenoid valve, that is, there is no state in which any of the two ports on the outlet side are connected to the ports on the inlet side. It is necessary to provide.

A three-way solenoid valve having a neutral position (a position where both output ports are not connected to the input port) and which can be driven in two directions by a return solenoid is used, and the one-way rotary variable speed motor 3 is stopped. Then, if the three-way solenoid valve is set to the neutral position, it is not necessary to provide the check valve 6 for locking.

FIG. 5 is a diagram in which a pair of pilot check valves in FIG. When the hydraulic pressure applied to the left hydraulic chamber of the cylinder 6 is higher than the hydraulic pressure applied to the right hydraulic chamber, the cylinder 6
When the hydraulic oil from the right hydraulic chamber of the cylinder 6 is connected to the return pipe and the hydraulic pressure applied to the right hydraulic chamber of the cylinder 6 is higher than the hydraulic pressure applied to the left hydraulic chamber, the hydraulic oil from the left hydraulic chamber of the cylinder 6 Leads to return piping. It will be apparent to those skilled in the art that such a configuration performs the same operation as the hydraulic device having the configuration shown in FIG. In addition, even if the hydraulic circuit shown in FIGS.
A and 5B may be formed as a single pilot operated switching valve by a piping system as shown in FIG. 5, and a method thereof will not need to be explained to those skilled in the art.

FIG. 6 shows an example in which a four-way solenoid valve is used in place of the above-described two-way solenoid valve and three-way solenoid valve. 1
0 is a four-way solenoid valve. In this embodiment, the drive speed of the hydraulic cylinder 6 is controlled by changing the number of revolutions of the one-way rotary hydraulic pump 2 and the rotation direction is switched by a four-way solenoid valve. In this embodiment, no check valve is provided on the outlet side of the one-way rotary hydraulic pump 2. In the four-way solenoid valve 10, the supply and return of hydraulic oil are reversed depending on the operation direction during operation, and in the neutral position, the input port P is blocked and the two output ports A and B are connected to the return port T. It has become so.

When the four-way solenoid valve 10 is driven to the right in the figure, the hydraulic oil of the one-way rotary hydraulic pump 2 is supplied to the hydraulic chamber on the left side of the hydraulic cylinder 6 via the pilot check valve 5A. The hydraulic oil in the right hydraulic chamber 6 is returned to the hydraulic tank 1 via the pilot check valve 5B and the four-way solenoid valve 10. When the four-way solenoid valve 10 is driven to the left in the figure, the hydraulic oil of the one-way rotary hydraulic pump 2 is supplied to the hydraulic chamber on the right side of the hydraulic cylinder 6 via the pilot check valve 5B, The hydraulic oil in the hydraulic chamber is returned to the hydraulic tank 1 via the pilot check valve 5A and the four-way solenoid valve 10.

When the four-way solenoid valve 10 is in the neutral position,
The hydraulic oil from the one-way rotary hydraulic pump 2 is a four-way solenoid valve 1
Blocked at 0. At this time, no problem occurs because the one-way rotary hydraulic pump 2 is stopped, but when the operation timing of both is a problem, the one-way rotary hydraulic pump 2 and the four-way solenoid valve What is necessary is just to provide a relief valve. When the four-way solenoid valve 10 is in the neutral position, the output ports of the pilot check valves 5A and 5B are connected to the return pipe. However, the pilot oil pressure becomes low. Blocked by check valves 5A and 5B.

FIG. 7 shows another example in which a four-way solenoid valve is used in place of the above-described two-way solenoid valve and three-way solenoid valve. In this example, unlike the one shown in FIG. 6, a pilot check valve is not provided, and the four-way solenoid valve has its input port, two output ports, and the return port blocked at the neutral position. It has become so.

Also in this embodiment, the driving speed of the hydraulic cylinder 6 is controlled by changing the number of rotations of the one-way rotary hydraulic pump 2, and the rotation direction is switched by a four-way solenoid valve.

In this embodiment, the four-way solenoid valve 1
The operation when 0 is driven to the right and left sides of the figure is the same as that of the embodiment shown in FIG. When the four-way solenoid valve 10 is in the neutral position, the movement of the hydraulic cylinder 6 is blocked by the four-way solenoid valve 10. The need to provide a relief valve between the one-way rotary hydraulic pump 2 and the four-way solenoid valve 10 if necessary is the same as in the embodiment shown in FIG.

[0067]

As described above, according to the first aspect of the present invention, since the rotation direction of the motor and the hydraulic pump is one direction, the life of the hydraulic pump can be extended and the cost can be reduced. Is cheaper. Further, since the detection accuracy of the speed detector and the speed control accuracy of the motor may be coarse, an inexpensive variable speed motor and encoder can be used, and an inexpensive control method and control device can be adopted. In addition, the overall temperature rise is reduced, and a large-scale cooling device is not required. Further, since the unit components are small, integration with a driven body or the like is sufficiently possible.

According to the second aspect of the present invention, since there is no check valve, the device can be simplified accordingly. In the invention according to claim 3, since the switching of the rotation direction is performed without delay at the time of switching, the frequency response speed can be increased.

In the inventions according to claims 4 to 7, since only one pump and one motor are required, a system can be realized at low cost. In addition, locking when the motor is stopped can be reliably performed.

In the invention according to the eighth aspect, even when there is no check valve, the lock at the time of stopping the motor can be reliably performed, and only one pump and one motor are required, so that the system can be realized at low cost.

According to the ninth aspect of the present invention, further,
The pilot switching valve can be omitted. Claim 10
In the invention according to the first aspect, the pair of pilot operated two-way valves can be replaced with one pilot operated switching valve.

[Brief description of the drawings]

FIG. 1 is a system diagram showing an example of a hydraulic drive device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a driving method of a one-way rotation type variable speed motor for increasing a response speed.

FIG. 3 is a system diagram showing another example of the hydraulic drive device according to the embodiment of the present invention.

FIG. 4 shows a third example of the hydraulic drive device according to the embodiment of the present invention.
It is a system diagram which shows the example of.

FIG. 5 shows a fourth embodiment of the hydraulic drive device according to the embodiment of the present invention.
It is a system diagram which shows the example of.

FIG. 6 shows a fifth embodiment of the hydraulic drive device according to the embodiment of the present invention.
It is a system diagram which shows the example of.

FIG. 7 shows a sixth embodiment of the hydraulic drive device according to the embodiment of the present invention.
It is a system diagram which shows the example of.

FIG. 8 is a diagram showing an outline of a typical conventional hydraulic servo system.

FIG. 9 is a diagram showing a schematic configuration of a conventional hydraulic control device using a bidirectional rotary hydraulic pump and a variable speed motor.

10 shows the relationship between the rotational speed of the variable speed motor and the position of the hydraulic cylinder when the hydraulic cylinder is alternately moved in the left-right direction in the hydraulic control device shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Oil tank 2, 2A, 2B ... One way rotation type hydraulic pump 3, 3A, 3B ... One way rotation type variable speed motor 4, 4A, 4B ... Check valve 5A, 5B ... Pilot check valve 6 ... Hydraulic cylinder 7A , 7B ... 2-way solenoid valve 8 ... 3-way solenoid valve 9 ... Pilot operation switching valve 10 ... 4-way solenoid valve

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Norihiro Kuzuu 2951-4 Ishikawacho, Hachioji-shi, Tokyo Inside Nireco Co., Ltd. (72) Inventor Masayuki 2951-4 Ishikawacho, Hachioji-shi, Tokyo 4 Nireko Corporation ( 72) Inventor Takeshi Aihara 2951-4 Ishikawacho, Hachioji-shi, Tokyo Inside Nireko Corporation (72) Inventor Takeo Yamada 2951-4 Ishikawacho, Hachioji-shi, Tokyo 4 Inside Nileko Corporation (72) Inventor Masayuki Fukuda Tokyo 2951 Ishikawa-cho, Hachioji-shi 4 F-term in Nireco Co., Ltd. (reference) 3H089 AA59 AA61 BB14 BB15 CC01 DA02 DA06 DA14 DB33 DB34 DB44 DB45 DB48 DB49 GG02

Claims (10)

[Claims] 1. A one-way rotary hydraulic pump with a check valve connected to a driven object, a one-way rotary variable speed motor for driving each one-way rotary hydraulic pump, and the one-way rotary A pair of pilot operated two-way valves each having an input port connected to a pair of pipes between the hydraulic pump and the driven object and an output port connected to the return pipe. A hydraulic port, wherein the pilot port of the one-way valve is connected to the outlet pipe of a one-way rotary pump with a check valve, the pipe being connected to the input port of the other pilot operated two-way valve. apparatus. 2. A one-way rotary hydraulic pump connected to a driven object, a one-way rotary variable speed motor for driving the one-way rotary hydraulic pump, and the one-way rotary hydraulic pump. An input port is connected to each of a pair of pipes between driven objects, and a pair of pilot operated two-way valves are connected to an output port to a return pipe. The port is
A hydraulic drive device characterized by being connected to an outlet pipe of a one-way rotary pump with a check valve, of a pipe to which an input port of a two-way pilot operated valve on the other side is connected. 3. The hydraulic drive device according to claim 1, wherein when the driving direction of the driven object is changed, before the rotation of one variable speed motor stops, the other variable speed motor is stopped. A hydraulic drive device having a function of starting rotation of a motor. 4. A pair of two-way solenoid valves connected to a driven object, a one-way rotary hydraulic pump with a check valve connected to the pair of two-way solenoid valves, and the one-way rotary hydraulic pump And a pair of pilot operation two-way motors each having an input port connected to a pair of pipes between the two-way solenoid valve and the driven object, and an output port connected to a return pipe. And a pilot port of the pair of pilot operated two-way valves is connected to an outlet pipe of a two-way solenoid valve of a pipe to which an input port of a mating pilot operated two-way valve is connected. A hydraulic drive device. 5. A pair of two-way solenoid valves connected to a driven object, a one-way rotary hydraulic pump connected to the pair of two-way solenoid valves, and a one-way rotary hydraulic pump for driving the one-way rotary hydraulic pump. An input port is connected to each of a pair of pipes between the directional rotating variable speed motor and the two-way solenoid valve and the driven object,
A pair of pilot operated two-way valves having an output port connected to the return pipe;
The pilot port of the two-way valve is
A hydraulic drive device characterized in that it is connected to the outlet pipe of a two-way solenoid valve of the pipe to which the input port of the one-way valve is connected. 6. A three-way solenoid valve having an output-side two port connected to a driven object, a one-way rotary hydraulic pump with a check valve connected to an input port of the three-way solenoid valve, An input port is connected to a one-way rotary variable speed motor that drives a one-way rotary hydraulic pump, and a pair of pipes between each outlet port of the three-way solenoid valve and a driven object, and output is provided to a return pipe. A pair of pilot-operated two-way valves having ports connected thereto, and a pilot port of the pair of pilot-operated two-way valves is connected to an input port of a mating pilot-operated two-way valve. A hydraulic drive device connected to the outlet pipe of the three-way solenoid valve. 7. A three-way solenoid valve having an output-side two port connected to a driven object, a one-way rotary hydraulic pump connected to an input port of the three-way solenoid valve, and the one-way rotary hydraulic pump. A one-way rotary variable speed motor for driving a hydraulic pump;
An input port is connected to each of a pair of pipes between each outlet port of the one-way solenoid valve and the driven object, and a pair of pilot operated two-way valves each having an output port connected to a return pipe. A hydraulic port, wherein a pilot port of a pair of pilot operated two-way valves is connected to an outlet pipe of the three-way solenoid valve of a pipe to which an input port of a mating pilot operated two-way valve is connected. Drive. 8. A pair of pilot operation check valves each having an input port connected to a driven object and two output ports connected to two output ports of a four-way solenoid valve; A one-way rotary hydraulic pump connected to the inlet port of the valve, and a one-way rotary variable speed motor for driving the one-way rotary hydraulic pump; The port is connected to a pipe to which the output port of the other party's pilot operation check valve is connected. When the four-way solenoid valve is in the neutral position, the input port is closed and the two output ports are connected to the return pipe. A hydraulic drive device connected to a hydraulic drive. 9. A four-way solenoid valve having two output ports connected to a driven object, a one-way rotary hydraulic pump connected to an input port of the three-way solenoid valve, and the one-way rotary hydraulic pump. A hydraulic drive device comprising a one-way rotary variable speed motor for driving a hydraulic pump, wherein the four-way solenoid valve has all ports closed when in a neutral position. . 10. A hydraulic drive device, wherein the pair of pilot operated two-way valves according to claim 1 is replaced by a single pilot operated switching valve that performs the same operation.