JPH11294404A - Hydraulically-driven device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulically-driven device to realize a function to hold select and switch a working direction and hold the stop position of a hydraulic actuator and decrease a wasteful energy consumption amount with simple constitution without needing an electromagnetically-operated hydraulic switch valve and its controlling electric device equipment. SOLUTION: A hydraulically-driven device comprises a forward reverse switching variable pump 2; a hydraulic cylinder piston device 4 selectively driven in a forward and reverse direction by working oil from the pump; and a valve device 10 to hold the stop position of a cylinder piston device 4 to block outflow of working oil from a cylinder to an external force exerted on the piston rod of the cylinder piston device 4. The valve device 10 comprises a passage shut-off valve 13 opened by oil discharged from a first port 2a of a pump intercommunicate the first port 2a and one port 4a of an actuator; and a spool 16 moved by oil discharged from a second port of the pump and forcibly opening the passage shut-off valve 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic drive device for driving a hydraulic actuator such as a cylinder in a forward / reverse direction using a hydraulic pump as a pressure source.

[0002]

2. Description of the Related Art In a press device, a bender machine or a lifter device, a hydraulic drive device for driving a hydraulic actuator such as a cylinder in a forward / reverse direction using a hydraulic pump as a pressure source is widely used.

Conventionally, in this type of hydraulic drive device, during operation, pressure hydraulic oil discharged from a hydraulic pump that is constantly driven to rotate in a fixed direction is switched in a forward / reverse direction by an electromagnetically operated hydraulic switching valve.
Alternatively, the operation of the hydraulic actuator is generally controlled by shutting off.

[0004]

In the conventional hydraulic drive system, it is necessary to rotate the hydraulic pump constantly during the operation of the equipment to be used, so that the energy consumption is wasted and the operation of the hydraulic actuator is not performed. The control of the electromagnetic operation switching valve as well as the electric control device for the electromagnetic operation switching valve in addition to the electric control device for the drive motor of the hydraulic pump is necessary, so the configuration of the device is complicated, There was a difficulty in meeting cost reduction demands in both manufacturing and use and maintenance.

Accordingly, an object of the present invention is to provide a relatively simple operation without the need for an electromagnetically operated hydraulic switching valve and an electric device and equipment for controlling the same, which are required in such a conventional hydraulic driving device. It is an object of the present invention to provide a hydraulic drive device with a small amount of energy consumption capable of realizing the function of switching the operation direction and maintaining the stop position of the hydraulic actuator with the configuration.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a hydraulic drive device according to the present invention has a pressure source capable of switching a hydraulic oil discharge direction between forward and reverse directions and a hydraulic oil from the pressure source. The hydraulic actuator includes a hydraulic actuator selectively driven in the opposite direction, and a valve device for preventing a hydraulic oil from flowing out of the hydraulic actuator against external force acting on the hydraulic actuator and holding a stop position of the hydraulic actuator.

Here, the pressure source is an electric motor device capable of forward and reverse rotation, a hydraulic pump selectively driven forward and reverse by the electric motor device, and a pressure regulating device in which the load pressure of the hydraulic pump is set in advance. A pressure control mechanism that keeps the discharge pressure to a necessary minimum when the pressure reaches the minimum value.

[0008] The hydraulic pump is a first port that is on the discharge side when rotating in one direction and is on the suction side when rotating in the other direction, and is on the suction side when rotating in the one direction. And a second port that is on the discharge side when rotating in the other direction.

Further, the valve device is provided with a spring force so that the hydraulic fluid discharged from the first port side of the hydraulic pump allows the first port and one of the ports of the hydraulic actuator to communicate with each other at a predetermined opening degree. And a spool moved by hydraulic oil discharged from the second port side of the hydraulic pump to forcibly open the flow path shutoff valve.

Further, the hydraulic drive device according to the present invention includes an oil passage connecting means for connecting the second port of the hydraulic pump to the other port of the hydraulic actuator. In one embodiment, the oil passage connection means includes an oil passage or a pipe that constantly connects the second port of the hydraulic pump to the other port of the hydraulic actuator. In another embodiment, the oil passage connection means is provided by the spool. The second port and the other port of the hydraulic actuator are opened and closed complementarily to the flow path cutoff valve and communicate with the second port and the other port of the hydraulic actuator at a preset opening degree by hydraulic oil discharged from the second port side of the hydraulic pump. In this case, the spool is forcibly opened by the hydraulic oil discharged from the first port side of the hydraulic pump. Go to

The hydraulic pump can be constituted by a variable displacement pump capable of rotating forward and backward, and in this case, the pressure control mechanism includes a pressure compensating valve for hydraulically controlling a discharge amount variable element of the variable displacement pump by a discharge pressure. Will be included. Further, the hydraulic pump may be constituted by a constant discharge type pump capable of rotating forward and reverse, and in this case, the pressure control mechanism may include a relief valve for releasing a discharge pressure exceeding a preset relief pressure to the tank line. Become.

In the hydraulic drive device according to the present invention, by selectively starting the drive motor device in the forward / reverse direction, the hydraulic actuator can be started in the forward / reverse direction via the hydraulic pump. For example, in the case of a simple device mounted on a vehicle, the DC motor can be configured as an operating section by combining an on / off switch and a speed adjusting notch, which simplifies the equipment configuration and operability. It is. In some cases, the discharge amount of the hydraulic pump can be controlled by the pump rotation speed by controlling the speed of the driving motor by an inverter device, and the operating speed of the hydraulic actuator can be controlled to a desired speed, and the hydraulic actuator can be started and / or stopped. It is possible to control the speed change at the time to a desired pattern. Also, the maximum discharge rate of the hydraulic pump is
It is needless to say that the adjustment can also be performed by a flow rate adjusting screw provided in a normal hydraulic pump.

When the drive motor is stopped and the hydraulic pump is stopped, the flow path cutoff valve of the valve device is closed by a spring force, and the flow from the hydraulic actuator to the hydraulic pump side is blocked. Since the hydraulic actuator is blocked by the outflow blocking function of the valve, the hydraulic actuator is kept stopped even if a load is applied to the hydraulic actuator.

When the drive motor is started in the normal rotation, the hydraulic pump sucks the hydraulic oil on the second port side and discharges it to the first port side. Thereby, the flow path cutoff valve of the valve device is opened against the spring force by the hydraulic fluid discharged from the first port side, and the first port of the hydraulic pump and one port of the hydraulic actuator are set as the flow path cutoff valve. Is communicated at the specified opening. This set opening degree can be adjusted as desired by, for example, using a structure in which a stopper member that abuts the valve body of the flow path shutoff valve that moves backward against the spring force at the backward limit position can advance and retract by a screw. is there.

Since the other port of the hydraulic actuator is connected to the second port of the hydraulic pump by the oil path connecting means, when the flow path shutoff valve is opened as described above, the discharge from the first port of the hydraulic pump is performed. Hydraulic oil is introduced into one port of the hydraulic actuator, and the hydraulic actuator starts to move, for example, in the forward direction. At this time, hydraulic oil sent out from the other port of the hydraulic actuator is supplied to the second port of the hydraulic pump via the oil passage connection means. Sucked into.

When the hydraulic actuator reaches the end of movement in the positive direction, the discharge pressure rises, and when it reaches the pressure regulation value set by the pressure control mechanism, the pressure control mechanism keeps the discharge pressure to the minimum necessary for energy consumption. Restrict. In this state, the operation of the drive motor may be stopped to stop the rotation of the hydraulic pump. In any case, the flow of the hydraulic oil flowing from the first port to the hydraulic actuator is stopped, and at the same time, the flow path cutoff valve is set to the neutral position by the spring force. To prevent the hydraulic oil from flowing out of the hydraulic actuator, so that the hydraulic actuator does not move from the stop position due to external force.

When the drive motor is started in reverse, the hydraulic pump sucks the hydraulic oil from the first port and discharges it to the second port. As a result, the spool of the valve device is moved by the hydraulic fluid discharged from the second port side to forcibly open the flow path shutoff valve, and the flow path between the first port of the hydraulic pump and one port of the hydraulic actuator is opened. It communicates with the opening degree set to the shutoff valve.

When the flow path shutoff valve is opened, hydraulic oil discharged from the second port of the hydraulic pump is introduced into the other port of the hydraulic actuator via the oil path connecting means, and the hydraulic actuator starts to move in the opposite direction. At this time, the hydraulic oil sent from one port of the hydraulic actuator is sucked into the first port of the hydraulic pump.

Also in this case, when the hydraulic actuator reaches the end of movement in the opposite direction, the discharge pressure rises, and when it reaches the pressure regulation value set by the pressure control mechanism, the pressure control mechanism keeps the discharge pressure to the minimum necessary. Limit energy consumption. In this state, the operation of the drive motor may be stopped to stop the rotation of the hydraulic pump. In any case, the flow of the hydraulic oil flowing from the second port to the hydraulic actuator is stopped, and at the same time, the flow path cutoff valve is set in the neutral position by the spring force. To prevent the hydraulic oil from flowing out of the hydraulic actuator, so that the hydraulic actuator does not move from the stop position due to external force.

According to another feature of the present invention, the spool of the valve device constitutes a flow path switching valve, and the flow path switching valve is configured to discharge any one of the first and second ports of the hydraulic pump. When the oil is not introduced into the hydraulic actuator, the spool is brought into contact with the flow path cutoff valve by a spring force, and the hydraulic pump is moved against the spring force by hydraulic oil discharged from the first port side of the hydraulic pump. A first switching position for communicating the second port side to the tank line, and a hydraulic pump discharged from the second port side of the hydraulic pump to move the first port side to the tank line and to connect the second port side to the tank line; And a second switching position in which the first port side and the second port side are both disconnected from the tank line by the flow path switching valve in the neutral position.

In particular, in this case, even if an asymmetric actuator is used as the hydraulic actuator, in which the flow rate of the hydraulic oil flowing to the other port side is smaller than the flow rate of the hydraulic oil flowing to the one port side during operation, In the reverse operation direction, the excess and deficiency of the supply / discharge flow rate of the hydraulic pump can be compensated for between the tank line and the supply / discharge flow rate by the switching operation of the passage switching valve of the valve device.

For example, when a single rod type cylinder piston device is used as a hydraulic actuator, if the head type cylinder chamber communicates with the one port and the rod side cylinder chamber communicates with the other port, the above-mentioned hydraulic actuator is used. In the operation at the time of normal rotation of the pump, the hydraulic oil pushed out of the rod-side cylinder chamber of the actuator and returned to the second port of the pump, rather than the flow rate of the hydraulic oil introduced into the head-side cylinder chamber from the first port of the hydraulic pump. However, at this time, since the flow path switching valve by the spool is in the first switching position, the second port side communicates with the tank line, and the shortage of the hydraulic oil sucked into the second port of the pump is reduced by the tank. It will be supplied by suction from the line.

Similarly, in the reverse operation of the hydraulic pump,
The flow rate of hydraulic oil pushed out of the head side cylinder chamber of the actuator and returned to the first port side of the pump is larger than the flow rate of hydraulic oil introduced from the second port side of the hydraulic pump to the rod side cylinder chamber of the hydraulic actuator. At this time, since the flow path switching valve by the spool is in the second switching position, the first port side is connected to the tank line and the second port side is cut off from the tank line, thereby being pushed out from the head side cylinder chamber. An excess of the coming hydraulic oil is released from the first port side to the tank line.

When the hydraulic pump is stopped, that is, when there is no flow to the hydraulic actuator from either the first port side or the second port side, the flow path switching valve assumes the neutral position. Both the first port side and the second port side are shut off from the tank line by the flow path switching valve.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a state of a hydraulic drive device according to a preferred embodiment of the present invention in a pump stopped state, FIG. 2 is a schematic configuration diagram of the same during normal rotation of the pump, and FIG. It is.

In the illustrated example, a variable vane pump 2 which can be rotated forward and backward is used as a hydraulic pump, and a single rod type hydraulic cylinder piston device 4 is used as a hydraulic actuator.
However, the present invention is not limited to this. As the hydraulic pump, a constant discharge type vane pump or gear pump combined with a relief valve as a pressure control mechanism can be used, or as a hydraulic actuator For example, a double rod type symmetric hydraulic cylinder piston device or a reversible rotary hydraulic motor can be used.

The hydraulic drive system according to the present embodiment is a variable displacement vane pump 2 which constitutes a pressure source capable of switching the hydraulic oil discharge direction between forward and reverse directions, and is selectively operated in forward and reverse directions by hydraulic oil from the pump 2. A single-rod type cylinder piston device 4 as a hydraulic actuator driven by the cylinder piston device and a stop position of the cylinder piston device 4 by preventing the hydraulic oil from flowing out of the cylinder against external force acting on the piston rod of the cylinder piston device 4 And a valve device 10 for holding.

The pump 2 in this embodiment is a variable displacement vane pump selectively driven in forward and reverse rotations by a motor device including a motor 7 that is started and stopped by an inverter control device 6 and controlled in forward and reverse variable speeds. Also, as is well known, when the load pressure of the pump reaches a preset pressure regulation value, the spring 21 is biased by a spring 21 as a pressure control mechanism that keeps the discharge pressure to a minimum necessary to compensate for leakage in the circuit. The pressure compensation valve 24 guides the discharge pressure when the pump discharge pressure exceeds the pressure regulation value, and performs cutoff control for the discharge amount variable element in which the operating piston 23 that gives the operating force by the discharge pressure to the eccentric cam ring 22 is used. Utilizes a pressure compensator control mechanism. It goes without saying that a combination of a constant discharge pump capable of rotating forward and reverse and a relief valve for regulating the circuit upper limit pressure may be used instead.

The pump 2 has a first port 2a which is on the discharge side when rotating in one direction and which is on the suction side when rotating in the other direction, and which is on the suction side when rotating in one direction and is on the other side. A second port 2b which is on the discharge side when rotating in the direction. The second port 2b of the pump 2 is always connected to the rod-side cylinder of the cylinder piston device 4 by an oil passage (piping) 5 which constitutes oil passage connection means. Room port 4b
It is connected to the.

The valve device 10 is connected to the first port 2 of the pump.
a port connected to port a, a port A connected to port 4a of the head side cylinder chamber of the cylinder piston device 4, a port B connected to the second port 2b of the pump 2, and a flow control with a check valve. And a T port connected to the tank line via the valve 3. The flow control valve 3 with a check valve gives a free flow to the flow flowing from the tank line to the T port, and adjusts the flow by a pre-adjusted throttle to the flow flowing from the T port to the tank line. Restrict.

As shown in FIG. 1, when the pump is stopped, a spring 12 is seated on the A port side of the valve seat 11 formed between the P port and the A port in the valve device 10, and the P port and the A port are stopped. A poppet valve body 13 that blocks communication between ports is arranged, thereby forming a flow path cutoff valve with extremely low leakage when the flow path is cut off. This poppet valve 13
When the hydraulic fluid discharged from the first port 2a side of the pump 2 is introduced, the first port 2a and the port 4a of the head side cylinder chamber of the cylinder piston device 4 as shown in FIG.
Is opened against the spring force of the return spring 12 by the operating oil discharged from the first port 2a introduced into the P port so that the opening and closing can be communicated with each other at the opening set by the opening adjustment screw 14.

The valve device 10 also includes a spool 16 which is opposed to the poppet valve body 13 in the seating direction and abuts on the return spring 15 by the spring force.
When the discharge hydraulic pressure from the second port 2b side of the pump 2 is introduced, the flow path shut-off valve is moved by the discharge hydraulic oil from the second port 2b introduced to the B port as shown in FIG. Is forcibly pushed open against the spring force of the return spring 12. Here, the spring force of the return spring 12 is stronger than the spring force of the return spring 15.

The spool 16 constitutes a flow path switching valve, and this flow path switching valve is provided when neither the first port 2a nor the second port 2b of the pump 2 discharges hydraulic oil. As shown in FIG.
5 so that the P port and B
Each port takes a neutral position to shut off the port from the T port, and when the hydraulic oil discharged from the first port 2a side of the pump 2 is introduced, it is introduced from the first port 2a to the P port as shown in FIG. Return spring 15 by discharge hydraulic oil
Takes the first switching position to connect the B port to the T port while maintaining the closure between the P port and the T port, and discharge hydraulic oil from the second port 2b side of the pump 2 is introduced. 3, the port is moved against the return spring 12 of the poppet 13 by the discharge hydraulic oil introduced from the second port 2b side to the B port, as shown in FIG. The second switching position for disconnecting from the T port is taken.

The operation of the hydraulic drive system according to the present embodiment will be described below. First, when the drive motor 8 is stopped and the pump 2 is stopped, the poppet valve element 1 of the valve device 10 is stopped.
3 is closed by the spring force of the return spring 12, the cylinder piston device 4 is connected to the port 4 of the head side cylinder chamber.
It is shut off on the side a, so that the cylinder-piston device 4 is held stationary even if a load is applied to it.

When the drive motor 8 is started in the normal rotation, the pump 2 draws in hydraulic oil from the second port 2b and discharges it to the first port 2a. As a result, the discharge hydraulic oil is introduced into the P port of the valve device 10, so that the poppet valve body 13 is pushed open against the return spring 12, and the first port 2a of the pump 2 is connected to the cylinder piston as shown in FIG. The port 4 a of the head side cylinder chamber of the device 4 is communicated with the opening degree of the opening degree adjusting screw 14. That is, the opening degree adjusting screw 14 is used to move the poppet valve body 1 retreating against the spring force of the return spring 12.
A stopper member abuts on the retracted position 3 and can be adjusted to a desired position by adjusting the screw advance / retreat position.

When the P port and the A port are communicated at the set opening degree by the movement of the poppet valve body 13, the port 4b of the rod side cylinder chamber of the cylinder piston device 4 is connected to the second port 2b of the pump 2 by the oil passage 5. Connected to
Hydraulic oil discharged from the first port 2a of the pump 2 is introduced into the port 4a of the head-side cylinder chamber of the cylinder-piston device 4, and the cylinder-piston device 4 starts to move in the direction of extending the piston rod. The hydraulic oil delivered from the port 4b of the pump 2
It is sucked into port 2b.

In this case, the flow rate of the hydraulic oil introduced from the first port 2a of the pump 2 into the head side cylinder chamber of the cylinder piston device 4 is pushed out of the rod side cylinder chamber and returned to the second port 2b of the pump 2. The flow rate of the hydraulic oil becomes smaller in accordance with the volume difference between the head side and the rod side.
In the switching position, the spool 16 connects the B port to the T port while the port between the P port and the T port is shut off by the discharge hydraulic oil introduced into the P port as shown in FIG. Insufficient hydraulic oil based on the volume difference passes freely from the tank line through the flow control valve 3 with the check valve, and from the oil passage 5 through the T port and the B port of the valve device 10 to the second port of the pump 2. 2b is supplied by suction.

When the cylinder piston device 4 reaches the moving end of the piston rod in the extending direction of the piston rod, the movement of the piston is blocked, so that the pump discharge pressure rises, and the pump discharge pressure rises to the pressure adjustment value set in the pressure compensating valve 24 of the pump. When reached, the pump discharge pressure acts on the operating piston 23 through the pressure compensating valve 24, whereby the eccentric cam ring 22 reduces the amount of eccentricity against the spring 21 so that the discharge from the pump compensates for the internal leakage. At this time, the electric power consumption of the electric motor 8 is limited because the load power is the minimum necessary. In this state, the drive motor 8 may be stopped to stop the rotation of the pump 2. In any case, the flow of the hydraulic oil flowing from the first port 2a into the head side cylinder chamber of the cylinder piston device 4 stops, and at the same time, the poppet Since the valve element 13 returns to the seated state by the spring force, and the communication between the A port and the P port is blocked by the valve seat seal without leakage, the cylinder piston device 4 does not move from the stop position due to external force.

When the drive motor 8 is started in reverse rotation, the pump 2 sucks the hydraulic oil on the first port 2a side and discharges it to the second port 2b side. Thereby, the spool 1 of the valve device 10
The poppet valve body 13 is forcibly opened by the movement of the hydraulic fluid 6 discharged from the second port 2b side flowing through the oil passage 5 to communicate with the first port 2a of the pump 2 as shown in FIG. The P port and the A port communicating with the port 4a of the head side cylinder chamber of the cylinder piston device 4 are communicated with the set opening degree.

When the P port and the A port are communicated with each other by the movement of the poppet valve body 13, the second port 2b of the pump 2 is connected to the port 4b of the rod-side cylinder chamber of the cylinder piston device 4 via the oil passage 5. The introduced hydraulic oil causes the cylinder piston device 4 to start moving in a direction to retract the piston rod. At this time, the hydraulic oil sent out from the port 4a of the head side cylinder chamber of the cylinder piston device 4 is connected to the P port which is now in communication with the P port. It is sucked into the first port 2a of the pump 2 after passing between the ports.

In this case, too, the flow rate of the hydraulic oil introduced into the rod-side cylinder chamber of the cylinder piston device 4 from the second port 2b side of the pump 2 is pushed out of the head-side cylinder chamber, and the first port 2a of the pump 2 The flow rate of the hydraulic oil returning to the side becomes larger according to the volume difference between the head side and the rod side. At this time, the flow path switching valve by the spool 16 is in the second switching position, and the spool 16 is moved to the position shown in FIG. As shown, the P port communicating with the first port 2a side of the pump 2 is connected to the T port and the B port is cut off from the T port, so that the hydraulic oil pushed out from the port 4a of the head side cylinder chamber to the A port. Of the above, the excess due to the volume difference is released to the tank line via the adjustment throttle of the flow control valve 3 with a check valve connected from the P port to the T port. In the present embodiment, the adjustment throttle of the flow control valve 3 with a check valve is adjusted to an optimal opening in order to prevent runaway of the lowering operation of the piston rod of the cylinder piston device 4. And if there is no need in terms of use, there is no need to provide a flow regulating valve with a check valve.
Further, when the opening degree of the adjustment throttle of the flow control valve 3 with a check valve is optimally set and adjusted in accordance with the volume difference, the operating speeds of the cylinder piston device 4 in both the forward and reverse directions can be evenly matched. .

Also in this case, when the piston rod of the cylinder piston device 4 reaches the moving end in the contraction direction, the movement of the piston is blocked, so that the pump discharge pressure rises, which is set in the pressure compensating valve 24 of the pump. When the pressure adjustment value is reached, the pump discharge pressure acts on the operating piston 23 through the pressure compensating valve 24, whereby the eccentric cam ring 22 reduces the amount of eccentricity against the spring 21 so that the amount of discharge from the pump reduces the amount of internal leakage. The compensation is kept to the necessary minimum, and at this time, the electric power consumption of the electric motor 8 is limited because the load power becomes the minimum necessary. In this state, the operation of the drive motor 8 may be stopped to stop the rotation of the pump 2. In any case, the flow of the hydraulic oil flowing from the second port 2b into the rod-side cylinder chamber of the cylinder piston device 4 stops, and at the same time, the poppet Since the valve element 13 returns to the seated state by the spring force, and the communication between the A port and the P port is blocked by the valve seat seal without leakage, the cylinder piston device 4 does not move from the stop position due to external force.

FIG. 4 is a schematic structural view of a hydraulic drive unit according to another embodiment of the present invention in a pump stopped state. In this embodiment, an intermediate spool is interposed in place of the valve device 10 in the above embodiment. A valve device 30 in which two flow path shut-off valves (poppets 33a, 33b) are opposed to each other, and another flow path cut-off valve (in the valve device 30 as oil path connecting means instead of the oil passage 5 in the above-described embodiment). The poppet 33b) is used. In FIG. 4, the same reference numerals as those in FIGS. 1 to 3 denote the same or corresponding parts, and their configurations and operations are the same as those in the above-described embodiment, and thus the detailed description will be omitted.

The valve device 30 is connected to the first port 2 a of the pump 2.
Pump 2 through a Pa port connected to the
The Pb port connected to the second port 2b, the A port connected to the port 4a of the head side cylinder chamber of the cylinder piston device 4, and the port 4b of the rod side cylinder chamber of the cylinder piston device 4 by the oil passage 5a. It has a B port connected to it and a T port connected to the tank line. In this embodiment, the T port is directly connected to the tank line. However, in this embodiment, a flow control valve with a check valve is interposed between the T port and the tank line as in the above embodiment. The flow flowing from the tank line to the T port may be given a free flow, and the flow flowing from the T port to the tank line may be restricted by a throttle adjusted in advance.

As shown in FIG. 4, when the pump is stopped, a spring 32a sits on a valve seat 31a formed between the Pa port and the A port in the valve device 30 from the A port side to stop the Pa port and the A port. A poppet valve body 33a that blocks communication between the ports is arranged, thereby forming a flow path cutoff valve with extremely little leakage when the flow path is cut off. The poppet valve body 33a is provided with an opening adjusting screw between the first port 2a and the port 4a of the head side cylinder chamber of the cylinder piston device 4 when the discharge hydraulic oil is introduced from the first port 2a side of the pump 2. The port is opened against the spring force of the return spring 32a by hydraulic oil discharged from the first port 2a introduced into the Pa port so as to communicate with the opening degree set at 34a.

In the valve device 30, another flow path shut-off valve which functions complementarily to the flow path shut-off valve formed by the poppet valve body 33a is constituted by a poppet valve body 33b opposed to the flow path cut-off valve. That is, the valve seat 31b formed between the Pb port and the B port in the valve device 30 is seated by the spring 32b from the B port side when the pump is stopped to cut off the communication between the Pb port and the B port. Poppet valve body 33b
Are arranged symmetrically with the poppet valve body 33a, thereby constituting another flow path shut-off valve having extremely little leakage when the flow path is cut off. This poppet valve body 33b is
When the hydraulic fluid discharged from the second port 2b side is introduced, the second port 2b communicates with the port 4b of the rod side cylinder chamber of the cylinder piston device 4 at the opening set by the opening adjustment screw 34b. Return oil 3 from the second port 2b introduced to the Pb port so that the return spring 3
Opened against the spring force of 2b.

The valve device 30 includes two poppet valve bodies 33a, 3
3b, a spool 36 having a length dimension which abuts on both end surfaces of the poppet valve bodies in a seated state corresponds to the spool 16 of the above-described embodiment, and the both poppet valve bodies 33, 33b Has a symmetrical opening / closing structure for forcibly opening the complementary. That is, when the hydraulic fluid discharged from the first port 2a side of the pump 2 is introduced into the Pa port, the spool 36 moves rightward in the drawing to move the poppet valve body 33b against the spring force of the return spring 32b. When the hydraulic pressure from the second port 2b of the pump 2 is introduced into the Pb port, the forcible push-open valve is moved to the left in the drawing to move the poppet valve body 33a to the spring force of the return spring 32a. Forcibly push open in opposition.

The spool 36 constitutes a flow path switching valve, and this flow path switching valve is used when neither the first port 2a nor the second port 2b of the pump 2 discharges hydraulic oil. As shown in FIG.
Double return springs 32a, 32 acting via 3a, 33b
By the spring force of b, both ends of the spool 36 are brought into contact with both the poppet valve bodies 33a and 33b to take a neutral position in which both the Pa port and the Pb port are blocked from the T port. Further, when the hydraulic fluid discharged from the first port 2a side of the pump 2 is introduced,
The port is moved to the right in the drawing against the return spring 32b of the poppet valve body 33b on the return right side by the discharge hydraulic oil introduced into the port, and the Pb port is moved to the T port while maintaining the closure between the Pa port and the T port. The first switching position for communication is taken. The first switching position is, as described above, the right poppet valve body 33.
The position b is forcibly opened by the spool 36. Further, when the hydraulic fluid discharged from the second port 2b side of the pump 2 is introduced, the flow path switching valve is connected to the second port 2b.
The left side of the poppet valve body 33a moves to the left in the figure against the return spring 32a of the left poppet valve body 33a by the discharge hydraulic oil introduced into the Pb port from the side to maintain the closure between the Pb port and the T port and set the Pa port to T. A second switching position is established for communication with the port. The second switching position is a position where the left poppet valve body 33a is forcibly opened by the spool 36 as described above.

The operation of the hydraulic drive device according to this embodiment will be described below. First, when the drive motor 8 is stopped and the pump 2 is stopped, both the poppet valve bodies 33a and 33b of the valve device 30 are in the neutral position by the spring force of the return springs 32a and 32b on both sides, respectively. The valve seats 31a, 31b of the cylinder piston device 4 are closed, so that the ports 4a, 4b of the cylinder chambers on both sides of the cylinder piston device 4 are shut off by the valve device 30, so that the cylinder piston device 4 has no load from either side, for example. Even when a load is applied, it is kept in a stopped state.

When the drive motor 8 is started in the normal rotation, the pump 2 sucks the hydraulic oil from the second port 2b and discharges it to the first port 2a. As a result, the discharge hydraulic oil is introduced into the Pa port of the valve device 30, so that the poppet valve body 33a
Is pushed open against the return spring 32a, and the first
The port 2a and the port 4a of the cylinder chamber on the head side of the cylinder piston device 4 communicate with each other at the set opening of the opening adjusting screw 34a. That is, the opening adjustment screw 34a is
Poppet valve element 33a that moves backward against the spring force of 2a
And a stopper member that abuts at a retreat limit position, and the retreat limit position can be adjusted to a desired position by adjusting a screw advance / retreat position. At the same time, the pressure of the hydraulic oil introduced into the Pa port causes the spool 36 to move rightward in the drawing, forcibly pushing the poppet valve body 33b open against the return spring 32b, and the spool 36 The switching position is taken, and the Pa port and T
The right land portion 36b is opened while the port is kept closed to connect the Pb port to the T port.

In this manner, the left poppet valve body 33a
And the Pa port and the A port are communicated at the set opening, and the right poppet valve body 33b is forcibly unseated by the rightward movement of the spool 36 to communicate between the B port and the Pb port. Hydraulic oil discharged from the first port 2a of the pump 2 is introduced into the port 4a of the head-side cylinder chamber of the cylinder-piston device 4, and the cylinder-piston device 4 starts to move in the direction of extending the piston rod. Hydraulic oil sent out from the port 4b of the oil passage 5a flows from the oil passage 5a to the B port, the Pb port and the oil passage 5b.
Through the second port 2b of the pump 2.

In this case, the flow rate of the hydraulic oil introduced from the first port 2a of the pump 2 to the head side cylinder chamber of the cylinder piston device 4 is pushed out of the rod side cylinder chamber and returned to the second port 2b of the pump 2. The flow rate of the hydraulic oil becomes smaller in accordance with the volume difference between the head side and the rod side.
The spool 36 is in the switching position, and the spool 36 is moved to the left land portion 36a by the discharge hydraulic oil introduced into the Pa port.
The Pb port (now communicating with the B port) is connected to the T port by the land portion 36b on the right side of the port while the Pa port and the T port are shut off, so that the shortage of hydraulic oil based on the volume difference is reduced. The oil passes through a free flow from the tank line and is suction-supplied from the oil passage 5b to the second port 2b of the pump 2 via the T port and the Pb port of the valve device 30.

When the cylinder piston device 4 reaches the moving end of the piston rod in the direction of extension of the piston rod, the movement of the piston is blocked, so that the pump discharge pressure rises, and the pump discharge pressure rises to the pressure regulation value set in the pressure compensating valve 24 of the pump. When reached, the pump discharge pressure acts on the operating piston 23 through the pressure compensating valve 24, whereby the eccentric cam ring 22 reduces the amount of eccentricity against the spring 21 so that the discharge from the pump compensates for the internal leakage. At this time, the electric power consumption of the electric motor 8 is limited because the load power is the minimum necessary. In this state, the drive motor 8 may be stopped to stop the rotation of the pump 2. In any case, the flow of the hydraulic oil flowing from the first port 2a into the head side cylinder chamber of the cylinder piston device 4 is stopped, and at the same time, the spool is stopped. 3
6 and both poppet valve bodies 33a and 33b return to the neutral position by the spring force and shut off the A port and the B port with the respective leak-free valve seat seals, so that the cylinder piston device 4 is moved from the stop position by an external force. Nothing.

On the other hand, when the drive motor 8 is started in the reverse rotation, the pump 2 sucks the hydraulic oil from the first port 2a and discharges it to the second port 2b. Accordingly, the valve device 30
Performs a complementary operation completely opposite to the above. That is, the valve device 30
When the discharge hydraulic oil is introduced into the Pb port, the poppet valve body 33b is pushed open against the return spring 32b, and the second port 2b of the pump 2 and the port 4b of the rod-side cylinder chamber of the cylinder piston device 4 are connected. Are communicated at the set opening of the opening adjusting screw 34b. The opening adjusting screw 34b is also moved backward with respect to the spring force of the return spring 32b.
3b is a stopper member which abuts at a retreat limit position, and the retreat limit position can be adjusted to a desired position by adjusting a screw advance / retreat position. At the same time, the pressure of the hydraulic oil introduced into the Pb port causes the spool 36 to move to the left in the drawing to forcibly open the poppet valve body 33a against the return spring 32a and to move the spool 36 to the second switching position. The left land portion 36a is opened by opening the left land portion 36a while keeping the closure between the Pb port and the T port by the right land portion 36b.
Connect a port to T port.

In this manner, the right poppet valve body 33b
When the Pb port and the B port communicate with the set opening degree, and the left poppet valve body 33a is forcibly removed by the left movement of the spool 36 and the A port communicates with the Pa port, Hydraulic oil discharged from the second port 2b of the pump 2 is introduced into the port 4b of the rod-side cylinder chamber of the cylinder-piston device 4, and the cylinder-piston device 4 starts to move in a direction to contract the piston rod. The hydraulic oil sent out from the port 4a is sucked into the first port 2a of the pump 2 via the A port and the Pa port.

In this case, the flow rate of the hydraulic oil introduced from the second port 2b of the pump 2 into the rod side cylinder chamber of the cylinder piston device 4 is pushed out of the head side cylinder chamber and returns to the first port 2a of the pump 2. The flow rate of the hydraulic oil increases in accordance with the volume difference between the rod side and the head side.
In the switching position, the spool 36 is moved to the land portion 36b on the right side by the discharge hydraulic oil introduced into the Pb port.
The Pa port (now communicating with the A port) is communicated with the T port by the land portion 36a on the left side of the head while the port between the Pb port and the T port is shut off, so that the port 4a of the head side cylinder chamber is pushed out to the A port. Excess hydraulic oil based on the volume difference among the hydraulic oil coming out is released from the Pa port to the tank line via the T port. In this embodiment, similarly to the embodiment shown in FIG. 1, a flow control valve with a check valve may be interposed between the T port and the tank line. If the adjustment throttle opening is adjusted to an optimal opening to prevent runaway of the piston rod of the cylinder piston device 4 or is optimally set and adjusted corresponding to the volume difference, the forward and reverse directions of the cylinder piston device 4 are changed. Operating speeds can be evenly matched with each other.

The operation when the cylinder / piston device 4 reaches the moving end in the contracting direction of the piston rod is the same as the operation at the moving end in the cautious direction described above, and therefore the description is omitted to avoid redundancy.

In this embodiment, the poppet valve bodies 33a, 33
Although the opening of 3b can be set in advance by the adjusting screws 34a and 34b, for example, when the discharge flow rate is adjusted by controlling the rotation speed of the pump 2 and the operating speed of the actuator can be adjusted, the flow setting screw 34a is used. , 34b need not be provided.

[0059]

As described above, in the hydraulic drive system according to the present invention, if the hydraulic pump is selectively driven in the forward or reverse direction by operating the switch of the drive motor, the hydraulic actuator is selectively driven in the forward or reverse direction. When the hydraulic actuator reaches the moving end, the electric power consumption of the electric motor is minimized, so that the energy consumption can be reduced. A simple structure hydraulically operated valve device that can be incorporated into the pump cover, for example, without the need for electrical devices and equipment for control. Can be realized.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a state of a hydraulic drive device according to a preferred embodiment of the present invention when a pump is stopped.

FIG. 2 is a schematic configuration diagram when the pump is rotating forward.

FIG. 3 is a schematic configuration diagram when the pump is reversely rotated.

FIG. 4 is a schematic configuration diagram illustrating a state of a hydraulic drive device according to another embodiment of the present invention in a pump stop state.

[Explanation of symbols]

 2: Hydraulic pump 2a: First port 2b: Second port 3: Flow control valve with check valve 4: Cylinder piston device (hydraulic actuator) 5: Oil passage (oil passage connection means) 6: Inverter control device 8: Drive Electric motor 10: Valve device 11: Valve seat 12: Return spring 13: Poppet valve body (flow path cutoff valve) 14: Opening adjustment screw 15: Return spring 16: Spool (flow path switching valve) 21: Spring 22: Eccentric cam ring 23: Operation piston (discharge amount variable element) 24: Pressure compensating valve 30: Valve device 31a, 31b: Valve seat 32a, 32b: Return spring 33a, 33b: Poppet valve body 34a, 34b: Opening adjustment screw 36: Spool

Claims (5)

[Claims] 1. A pressure source capable of switching a hydraulic oil discharge direction in a forward / reverse direction, a hydraulic actuator selectively driven in a normal / reverse direction by hydraulic oil from the pressure source, and an external force acting on the hydraulic actuator. A valve device for preventing the hydraulic oil from flowing out of the hydraulic actuator to hold the stop position of the hydraulic actuator, wherein the pressure source is a motor device capable of forward and reverse rotation, and selectively forward and reverse by the motor device. A hydraulic pump that is rotationally driven, and a pressure control mechanism that keeps a discharge pressure to a minimum when the load pressure of the hydraulic pump reaches a preset pressure adjustment value. A first port that becomes a discharge side when rotating and becomes a suction side when rotating in the other direction, and a first port that becomes a suction side when rotating in the one direction and a discharge side when rotating in the other direction. A second port, wherein the valve device communicates the first port and one of the ports of the hydraulic actuator at a preset opening by hydraulic fluid discharged from the first port side of the hydraulic pump. A flow path shut-off valve which is opened against spring force and a second hydraulic pump
A spool which is moved by hydraulic oil discharged from a port side to forcibly open the flow path shutoff valve, and further provided with an oil path connection means for connecting a second port of the hydraulic pump to the other port of the hydraulic actuator. A hydraulic drive device characterized in that: 2. The hydraulic pump according to claim 1, wherein said hydraulic pump comprises a variable displacement pump capable of rotating forward and backward, and said pressure control mechanism includes a pressure compensating valve for hydraulically controlling a discharge amount variable element of said variable displacement pump by a discharge pressure. The hydraulic drive device according to claim 1. 3. The hydraulic pump according to claim 1, wherein the hydraulic pump comprises a constant discharge pump capable of rotating forward and reverse, and the pressure control mechanism includes a relief valve for releasing a discharge pressure exceeding a preset relief pressure to the tank line. Item 2. The hydraulic drive device according to item 1. 4. The spool constitutes a flow path switching valve, and the flow path switching valve springs the spool when neither of the hydraulic oil discharged from the first and second ports of the hydraulic pump is introduced into the hydraulic actuator. A first position in which the hydraulic port is moved against a spring force by a hydraulic oil discharged from a first port side of the hydraulic pump to communicate the second port side to the tank line; And a second switching position for moving the first port side to communicate with the tank line by moving the hydraulic oil from the second port side of the hydraulic pump and disconnecting the second port side from the tank line. 2. The hydraulic drive device according to claim 1, wherein at the position, the first port side and the second port side are both shut off from the tank line by the flow path switching valve. 3. 5. The hydraulic actuator according to claim 1, wherein the hydraulic actuator is an asymmetric actuator in which the flow rate of the hydraulic oil flowing to the one port side is smaller than the flow rate of the hydraulic oil flowing to the other port side during operation. 5. The hydraulic drive device according to 4.