JPH0972312A - Cylinder driving hydraulic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lessen the consumption of power and to remove vibration and noise at the time of stopping. SOLUTION: A two-position changing over valve 7 is located in a position where both the ports P1, P2 of a cylinder 2 are cut off, and when a three- position changing over valve 3 is located at the first position (a), both rods 13 move right, and when the valve 3 is located at the second position (b), both the rods 13 move left. For stopping both the rods 13, the three-position changing over valve 3 is located at the third position, and the two-position changing over valve 7 is located in a position where a space between the ports P1, P2 is cut off. When in the case of the above stopping, pressure at the port P2 becomes higher than the pressure of an accumulator 6, pressure liquid is refluxed from the second pipe line 22 to the accumulator 6. In addition, when the pressure on the side of P1 becomes lower than the pressure in a reservoir tank 5, working liquid flows into P1 from the reservoir tank 5 through the third pipe line 23. In the case of stopping in the reverse direction, pressure liquid is refluxed to the accumulator 6 through the first pipe liner 21, and the working liquid flows into P2 through the fourth pipe line 24.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylinder-driven hydraulic device used for moving cargo handling.

[0002]

2. Description of the Related Art Conventionally, such a cylinder-driven hydraulic device is shown in FIG. 3, for example. When the cargo handling 31 is moved to the right in the figure, this cylinder-driven hydraulic device switches the switching valve 33 to the position a, and connects the discharge port 34a of the pump 34 and the port P1 on the left side of the cylinder 32 in the figure. The port P2 on the right side is communicated with the reservoir tank 35 at the same time. By doing so, the pressure liquid discharged from the discharge port 34a of the pump 34 is transferred to the port P.
Acting on 1, cargo handling 31 starts moving to the right in the figure. At this time, the moving speed of the cargo handling 31 is determined by the flow rate of the pressurized liquid supplied from the pump 34 to the cylinder 32.

Next, when the cargo handling 31 is stopped, the switching valve 33 is returned to the neutral position shown in FIG. 3, the discharge port 34a of the pump 34 and the port P1 of the cylinder 32 are shut off, and the port P2 and the reservoir are closed. The pipeline that communicates with the tank 35 is also shut off. By doing so, the pressurized liquid is no longer supplied from the pump 34 to the port P1.
In Fig. 3, the force to move further to the right disappears.

At this time, since the cargo handling 31 has been moving to the right until then, it tries to continue moving to the right as it is due to its inertia energy. When the cargo handling 31 moves to the right, the hydraulic fluid discharged from the port P2 of the cylinder 32 is blocked by the switching valve 33 from communicating with the reservoir tank 35, so that the hydraulic fluid is compressed to increase the pressure. The pressure causes a force to move the cargo handling 31 to the left in FIG. 3, and the cargo handling 31 is decelerated and stopped.

On the other hand, when the cargo handling 31 is moved to the left in FIG. 3, the switching valve 33 is switched to the position b and the pump 34 is moved.
Port P2 on the right side in the figure of discharge port 34a and cylinder 32 of
And the port P1 on the left side are communicated with the reservoir tank 35 at the same time. Then, the discharge port 34 of the pump 34
The pressure liquid discharged from a acts on the port P2, and the cargo handling 31
Starts moving to the left in the figure, and the moving speed is
4 is determined by the flow rate of the pressurized liquid supplied to the cylinder 32.

When the cargo handling 31 is stopped, the switching valve 33 is returned to the neutral position shown in FIG. 3, the discharge port 34a of the pump 34 and the port P2 of the cylinder 32 are shut off, and the port P1 and the reservoir tank 35 are connected. Also shut off the pipeline that connects the and. By doing so, the pressure liquid is not supplied from the pump 34 to the port P2, and the force for moving the cargo handling 31 further to the right in the figure disappears.

However, since the cargo handling 31 has moved to the left until then, it tries to continue moving to the left as it is due to its inertia energy. When the cargo handling 31 moves to the left, the hydraulic fluid discharged from the port P1 of the cylinder 32 is blocked by the switching valve 33 from communicating with the reservoir tank 35, so that the pressure increases due to compression. The pressure causes a force to move the cargo handling 31 to the right in FIG. 3, and the cargo handling 31 is decelerated and stopped.

[0008]

However, such a conventional cylinder-driven hydraulic device has the following problems. Every time I moved the cargo, I had to drive the pump and add energy,
If heavy cargo is moved frequently, a great deal of power is consumed. Also, when the moved cargo handling is stopped, the pipeline that allows the hydraulic fluid flowing out of the cylinder to flow out to the reservoir tank is shut off by switching the switching valve, so the cargo handling moves in the moving direction by inertial energy as it is. By continuing to do so, the inertial energy increases the pressure of the hydraulic fluid in the pipeline.

This pressure is generated in a short time in the pipe line between the cylinder and the switching valve, and the pressure becomes extremely large especially when the heavy cargo handling is suddenly stopped. Therefore, the generation of this pressure may cause vibration or noise, which may adversely affect the normal operation of the device. Therefore, in order to prevent such a problem from occurring in the related art, a special mechanism is provided in a switching valve that shuts off a pipeline that connects a cylinder and a reservoir tank so that the shutoff can be performed slowly. We are devising such as doing. However, in this way, although the generation of vibration and noise can be prevented, there is a problem that the time until the cargo handling is stopped is delayed.

The present invention has been made in view of the above problems, and consumes less power even if a heavy cargo handling is repeatedly started and stopped, and vibrates even if the heavy cargo handling is suddenly stopped. An object of the present invention is to provide a cylinder-driven hydraulic device that can be stopped in a short time without generating noise or noise.

[0011]

In order to achieve the above object, the present invention has a dual rod type cylinder in which the left and right pressure receiving surfaces have the same area, a fluid energy storage means, a low pressure reservoir tank, and a fluid energy storage. To a cylinder-driven hydraulic device consisting of an auxiliary pump for supplying pressurized liquid to the means,
From the first port and the second port for supplying or discharging pressurized liquid to or from the pressure receiving surfaces of the cylinder,
A first line and a second line in the free flow direction, which communicate with the fluid energy storage means via check valves, respectively, and the first port and the second line from the reservoir tank via check valves, respectively. A third pipe line and a fourth pipe line in the free flow direction, which communicate with the respective ports, a two-position switching valve, and a three-position switching valve are provided.

The two-position switching valve is switchably connected to a position where the first port and the second port communicate with each other and a position where the second port is shut off, and the three-position switching valve is connected to the fluid energy storage means. To the first port and above the second
The first position for communicating the respective ports with the reservoir tank and the fluid energy storage means for the second port.
Is provided so as to be switchable between a second position for communicating the respective ports with the reservoir tank and a third position for closing each of the first port and the second port.

According to this structure, when the cargo handling is attached to the rods of the double rod type cylinder and is moved in one direction, the two-position switching valve is provided with the first port and the second port of the cylinder. When the three-position switching valve 3 is switched to the first position, the high pressure of the fluid energy storage means acts on the first port and the second port communicates with the low pressure reservoir tank. Moves while being accelerated with cargo handling.

When the moving speed reaches a desired speed, the two-position switching valve is switched to a position where the first port P1 and the second port P2 communicate with each other, and
When the three-position switching valve 3 is returned to the third position, the pressures acting on the first port and the second port become equal, so that the rod moves at a constant speed along with the cargo handling. When stopping (braking) the rod, the two-position switching valve is switched to the position where the first port and the second port are shut off while the three-position switching valve is kept in the third position. Then, the rod tries to continue to move at a constant velocity motion together with the cargo handling, so that the pressure liquid in the cylinder tends to be discharged through the second port, but the second port is changed to the first position by the two-position switching valve.
Since it is cut off from the port, the pressure of the hydraulic fluid increases.

The increased pressure acts on the rod to push it back in the direction opposite to the moving direction, and the rod is decelerated and stopped together with the cargo handling. At this time, when the pressure of the second port becomes higher than the pressure of the fluid energy storage means, the pressure liquid is circulated to the fluid energy storage means while opening the check valve through the second pipeline and stored therein. .

At this time, the pressure liquid tries to flow into the cylinder through the first port, but the first port has two ports.
Since the position switching valve blocks the second port, the pressure on the side of the first port in the cylinder becomes low. When the pressure becomes lower than the pressure in the reservoir tank, the hydraulic fluid flows from the reservoir tank into the first port by pushing the check valve open through the third conduit.

When the rod is moved in the direction opposite to the above-described direction and stopped, the two-position switching valve is set to the position that shuts off the first port and the second port, and the three-position switching valve is turned. Switch to the second position. As a result, the high pressure of the fluid energy storage means acts on the pressure receiving surface on the side of the second port of the cylinder, and the pressure receiving surface on the side of the first port communicates with the low pressure reservoir tank, so that the rod moves while being accelerated along with the cargo handling. . Then, when it is moved at a constant speed, the 2-position switching valve may be switched to a position where the first port and the second port communicate with each other, and the 3-position switching valve may be switched to a third position.

Next, when the rod is stopped together with cargo handling, the two-position switching valve is switched to a position where the first port and the second port are shut off while the three-position switching valve is kept in the third position. . In this state, the pressure liquid in the first port is compressed and the pressure increases, so that the force of pushing the rod back due to the pressure causes the rod to be decelerated together with the cargo handling and stopped.

At this time, when the pressure in the first port becomes higher than the pressure in the fluid energy storage means, the pressure liquid pushes open the check valve in the first conduit and circulates to the fluid energy storage means. Accumulated. Further, at this time, when the pressure on the side of the second port in the cylinder becomes low and the pressure becomes lower than the pressure of the reservoir tank, the hydraulic fluid from the reservoir tank pushes open the check valve of the fourth pipe to open the check valve. Pour into port 2.

As described above, in this cylinder-driven hydraulic device, when the rod of the cylinder to which the cargo handling is attached is decelerated and stopped, the inertia energy due to the cargo handling moving together with the rod is converted into the fluid pressure. The fluid energy stored in the storage means and then stored in the fluid energy storage means can be used when moving the cargo.

Further, a single rod type cylinder having different left and right pressure receiving areas is used for the cylinder, and a fluid pressure is supplied to the fluid energy accumulating means, the low pressure reservoir tank and the fluid energy accumulating means similar to the above. To a cylinder-driven hydraulic device equipped with an auxiliary pump for supplying check liquid to the pressure receiving surfaces of the cylinder from the first port and the second port for supplying and discharging the pressurized liquid, respectively. A first pipe line and a second pipe line in the free flow direction, which communicate with the fluid energy storage means via the reservoir tank, and a reservoir tank which communicates with the first port and the second port via check valves, respectively. A third line and a fourth line in the flow direction are provided.

Then, in the cylinder-driven hydraulic device,
A fifth conduit provided with a check valve in a free flow direction from any one of the first port and the second port toward the reservoir tank, and a conduit switching valve for switching communication and interruption of the conduit. A two-position switching valve for switching the first port and the second port between a position where they communicate with each other and a position where they shut off each other,
A first position in which the fluid energy storage means is in communication with the first port, a second port is in communication with the reservoir tank, and a fluid energy storage means is in communication with the second port and the first port is in communication with the reservoir tank. There is provided a three-position switching valve for switching between a second position for switching and a third position for closing each of the first port and the second port.

With this configuration, when the pipe line switching valve 11 is set to the position for shutting off the pipe line, the action when the cylinder rod is accelerated, decelerated, and stopped is the same as that of the cylinder-driven hydraulic device described above. Become. Then, when the rod is being accelerated and moved from the one having a large pressure receiving area to the one having a small pressure receiving area, when switching it to a constant velocity motion, the pipe line switching valve 11
The two-position switching valve is switched to a position in which the first port and the second port are communicated with each other, while the three-position switching valve is in the first port and the second port with the pipe being cut off. To the third position to close each.

Then, since the area of one pressure receiving surface of the rod of the cylinder is larger than the area of the other pressure receiving surface, the pressure liquid discharged from the second port flows into the cylinder through the first port. Less than the amount of pressurized liquid used. The difference in the amount of pressurized fluid between the two is replenished into the cylinder from the first port by opening the check valve from the reservoir tank through the third conduit.

Further, when the rod is accelerated and moved from the smaller pressure receiving area to the larger pressure receiving area, when switching it to the uniform velocity motion, the conduit switching valve is switched to a position where the conduits communicate with each other. The two-position switching valve is switched to a position where the first port and the second port communicate with each other, and the three-position switching valve is set to the third position where the first port and the second port are closed.

As a result, the pressure acting on the left and right pressure receiving surfaces of the rod becomes substantially equal to the atmospheric pressure, and the rod moves in a substantially constant velocity with the cargo handling. At this time, since the area of the pressure receiving surface on the side of the first port of the cylinder is larger than the area of the pressure receiving surface on the side of the second port, the pressure liquid discharged from the first port passes through the second port to the cylinder. There is more than the amount of pressure liquid flowing into the inside. The difference in the amount of pressurized fluid between the two is returned to the reservoir tank by opening the check valve provided in the fifth conduit.

[0027]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram showing a cylinder-driven hydraulic device for explaining a first embodiment of the present invention. This cylinder-driven hydraulic device includes a double rod-shaped cylinder 2 in which a load by a cargo handling 1 is applied to both rods 13 in which the left and right pressure receiving surfaces 13a and 13b have the same area.
An accumulator 6 as a fluid energy storage means, a low-pressure reservoir tank 5, and an auxiliary pump 4 for supplying pressurized liquid to the accumulator 6 via a check valve 10 are provided.

In addition, this cylinder-driven hydraulic device has a first port P1 and a second port P1 for supplying and discharging pressurized liquid to and from the pressure receiving surfaces 13a and 13b of the cylinder 2, respectively.
From the port P2 in the free flow direction to the accumulator 6 via the check valves 8a and 8b, respectively, and from the reservoir tank 5 to the check valves 9a and 9b, respectively. Through the first port P1 and the second port P2 respectively in the free flow direction by a third pipe line 23, a fourth pipe line 24, a two-position switching valve 7, and a three-position switching valve 3. Is provided.

The two-position switching valve 7 is switchably connected to a position where the first port P1 and the second port P2 communicate with each other and a position where the first port P1 and the second port P2 communicate with each other (the position shown in FIG. 1). Further, the three-position switching valve 3 is connected to the accumulator 6 at the first port P1 and the second port P2 at the first position a for communicating with the reservoir tank 5, and the accumulator 6 at the second port P2. Second position b in which the first port P1 communicates with the reservoir tank 5 respectively
And a third position (position shown in FIG. 1) for closing the first port P1 and the second port P2, respectively.

In this cylinder-driven hydraulic device, the pressure of the accumulator 6 is kept substantially constant by replenishing the pressurized liquid from the auxiliary pump 4. When moving the cargo handling 1 to the right in FIG. 1 with this hydraulic device, first, the two-position switching valve 7 is set to the position where the first port P1 and the second port P2 shown in the figure are shut off. 3 is switched to the first position a.
As a result, the accumulator 6 communicates with the first port P1 of the cylinder 2 and the second port P2 communicates with the reservoir tank 5. Therefore, the high pressure of the accumulator 6 acts on the pressure receiving surface 13a on the left side of the cylinder 2, and the tank pressure that is the atmospheric pressure acts on the pressure receiving surface 13b on the right side, so that both rods 13 receive the force in the right direction in the figure. Will be accelerated. Therefore, the cargo handling 1 moved by the both rods 13 moves rightward in FIG. 1 by the uniform acceleration motion.

The moving speed of both rods 13 is measured by, for example, a speed sensor (not shown), and when it reaches a desired speed, the two-position switching valve 7 is switched from the position shown in FIG. The port P1 and the second port P2 of the same are set to the positions where they communicate with each other, and at the same time, the three-position switching valve 3 is installed in
Return to the third position (neutral position) shown in. Thereby,
The pressures acting on the first port P1 and the second port P2 become equal, and the left and right pressure receiving surfaces 13a, 13 of both rods 13 are
Since the pressures acting on b become equal, both rods 13 move at a constant velocity together with the cargo handling 1.

At this time, the left and right pressure receiving surfaces 1 of both rods 13
Since the pressure receiving areas of 3a and 13b are equal, the second port P
The pressure liquid discharged from 2 flows into the cylinder 2 through the first port P1 in the same amount as that discharged.
Here, since a frictional force acts on the cargo handling 1 in practice, it is conceivable that the moving speed of the cargo handling 1 gradually decreases, which is slightly different from the above description. However, in general, the moving speed of the cargo handling often does not require very high accuracy, and in this case, it may be regarded as a substantially constant velocity motion as described above.

Next, when the movement of the cargo handling 1 is stopped (braking), the two-position switching valve 7 is shown in FIG. 1 with the three-position switching valve 3 kept in the third position (neutral position). Switch to the position where the first port P1 and the second port P2 are shut off. In this state, since the cargo handling 1 is trying to move to the right in the figure by the uniform velocity movement together with both rods 13, the pressure liquid in the cylinder 2 tends to be discharged through the second port P2, but the second port Since P2 is shut off from the first port P1 by the two-position switching valve 7, the pressure liquid is compressed and the pressure increases.

Due to the increase in the pressure, a force for pushing back the cargo handling 1 to the left in FIG. 1 acts, and the cargo handling 1 is decelerated and stopped. At this time, when the pressure in the second port P2 becomes higher than the pressure in the accumulator 6, the pressure liquid pushes open the check valve 8b and flows back to the accumulator 6 through the second pipe line 22 and accumulates therein. When the cargo handling 1 moves rightward in FIG. 1 together with the rods 13, the pressure liquid tries to flow into the cylinder 2 through the first port P1, but the first port P1 is switched between two positions. Since the second port P2 is shut off by the valve 7, the pressure on the left pressure receiving surface 13a side in the cylinder 2 becomes low.

When the pressure becomes lower than the pressure in the reservoir tank 5, the working fluid is discharged from the reservoir tank 5 into the check valve 9a.
To open the first port P1 through the third conduit 23.
Flow into. As a result, it is possible to prevent an inconvenience such as cavitation from occurring due to the pressure on the left pressure receiving surface 13a side in the cylinder 2 being extremely lowered.

On the other hand, when the cargo handling 1 is moved to the left in the opposite direction of FIG. 1, the two-position switching valve 7 is connected to the first port and the second port of FIG.
Then, the three-position switching valve 3 is switched to the second position b. Thereby, the accumulator 6
Communicates with the second port P2 of the cylinder 2, and the first port P1 communicates with the reservoir tank 5. Therefore, the high pressure of the accumulator 6 acts on the pressure receiving surface 13b on the right side of the cylinder 2, and the tank pressure which becomes the atmospheric pressure acts on the pressure receiving surface 13a on the left side, so that both rods 13 receive a force to the left and accelerate. To be done. Therefore, the cargo handling 1 moves leftward in FIG. 1 by the uniform acceleration motion.

Then, the moving speed of both rods 13 is
As in the case of moving the cargo handling 1 to the right, measurement is made by a speed sensor (not shown) or the like.
2 is switched to a position where they communicate with each other, and at the same time, the 3-position switching valve 3 is returned to the third position (neutral position) shown in FIG. As a result, the pressures acting on the first port P1 and the second port P2 become equal, and the pressures acting on the left and right pressure receiving surfaces 13a and 13b of both rods 13 become equal, so that both rods 13 and the like work together. Velocity motion (it can be regarded as approximately constant velocity motion as in the case of rightward handling of cargo handling 1).

At this time, the left and right pressure receiving surfaces 1 of both rods 13
Since the pressure receiving areas of 3a and 13b are the same, the first port P
The pressurized liquid discharged from 1 flows into the cylinder 2 through the second port P2 in the same amount as that discharged.
Next, when stopping (braking) the movement of the cargo handling 1,
With the position switching valve 3 kept in the third position (neutral position), the two-position switching valve 7 is provided with the first port P1 and the second port P1 shown in FIG.
Switch to a position to shut off port P2 of.

In this state, the cargo handling 1 is trying to move to the left in the figure by the uniform velocity movement together with both rods 13,
The pressure liquid in the cylinder 2 is about to be discharged through the first port P1, but since the first port P1 is blocked from the second port P2 by the two-position switching valve 7, the pressure liquid is compressed. Pressure increases. Due to the increase in pressure,
A force that pushes it back to the right in FIG. 1 acts on the cargo handling 1, and the cargo handling 1 is decelerated and stopped. At this time, when the pressure of the first port P1 becomes higher than the pressure of the accumulator 6, the pressure fluid pushes open the check valve 8a to open the first conduit 21.
Through to the accumulator 6 and accumulated there.

When this cargo handling 1 is going to move to the left in FIG. 1 together with both rods 13, the second port P
Pressure fluid tries to flow into the cylinder 2 through 2, but
Since the second port P2 is cut off from the first port P1 by the two-position switching valve 7, the pressure on the right pressure receiving surface 13b side in the cylinder 2 becomes low. When the pressure becomes lower than the pressure of the reservoir tank 5, the hydraulic fluid from the reservoir tank 5 pushes open the check valve 9b and flows into the second port P2 through the fourth conduit 24. As a result, it is possible to prevent inconveniences such as cavitation from occurring due to the pressure on the right pressure receiving surface 13b side in the cylinder 2 being extremely lowered.

According to this cylinder-driven hydraulic device, when the cargo handling 1 is heavy, even if the cargo handling 1 is frequently started and stopped, the cargo handling 1 is decelerated and is moved when the cargo handling 1 is stopped. Since the inertia energy is converted into pressure and accumulated in the accumulator 6, and the fluid energy accumulated in the accumulator 6 can be used when the cargo handling 1 is moved next, power consumption is small. Also, cargo handling 1
Since the pressure generated in the pipeline at the time of deceleration or stop is recirculated to and accumulated in the accumulator 6, it can be stopped in a short time without generating vibration or noise even when heavy cargo handling is stopped. .

FIG. 2 is a circuit diagram showing a cylinder-driven hydraulic device for explaining the second embodiment of the present invention, and the portions corresponding to those in FIG. 1 are designated by the same reference numerals.
The cylinder-driven hydraulic device according to this embodiment includes a single rod type cylinder 20 having a single rod 15 in which left and right pressure receiving surfaces 15a and 15b have different areas. Also,
It has a fifth conduit 25 provided with a check valve 12 in the free flow direction from the first port P1 toward the reservoir tank 5 and a conduit switching valve 11 for switching between communication and interruption of the conduit. .

In this hydraulic device, the pressure of the accumulator 6 is kept substantially constant by replenishing the pressure liquid from the auxiliary pump 4 as in the embodiment of FIG. With this hydraulic device, when moving the cargo handling 1 to the right in FIG. 2, the line switching valve 11 is set to the position for blocking the line shown in the figure, and
The two-position switching valve 7 is set to a position that shuts off the first port P1 and the second port P2 shown in the figure, and the three-position switching valve 3 is switched to the first position a. By doing so, the single rod 15 is similar to the hydraulic device described in FIG.
Then, the cargo handling 1 moved thereby moves to the right in FIG. 2 due to the uniform acceleration motion.

When the moving speed of the one rod 15 reaches the desired speed, the two-position switching valve 7 is set to the position shown in FIG. To the position where the first port P1 and the second port P2 communicate with each other, and at the same time, the three-position switching valve 3 is returned to the third position (neutral position) shown in FIG.

As a result, the pressures acting on the first port P1 and the second port P2 become equal (approximately atmospheric pressure),
Since the areas of the left and right pressure receiving surfaces 15a and 15b of the one rod 15 are different, the pressures acting on the pressure receiving surfaces are different, but the difference is slight, so the one rod generated by the pressure acting on the pressure receiving surface 15a. The difference between the force for pushing 15 to the right in FIG. 2 and the force for pushing the one rod 15 to the left generated by the pressure acting on the pressure receiving surface 15b is small. Therefore, the single rod 15 and the cargo handling 1 both move to the right at a constant velocity.

At this time, in the cylinder 20, since the pressure receiving area of the left pressure receiving surface 15a is larger than the pressure receiving area of the right pressure receiving surface 15b, the pressure liquid discharged from the second port P2 is discharged from the first port. It is less than the amount of pressurized liquid flowing into the cylinder 2 through P1. The difference in the amount of pressurized fluid between the two is replenished into the cylinder 20 from the first port P1 by pushing open the check valve 9a from the reservoir tank 5 through the third conduit 23.

Next, when the movement of the cargo handling 1 is stopped (braked), the conduit switching valve 11 remains in the position where it blocks the conduit, and the three-position switching valve 3 also moves to the third position (neutral position). )
Then, the two-position switching valve 7 is switched to the position for shutting off the first port P1 and the second port P2 shown in FIG.
By doing so, as in the case of the hydraulic device described with reference to FIG. 1, the cargo handling 1 together with the one rod 15 moves at a constant velocity while the first port P1 and the second port P2 are blocked. Since it tries to move to the right, the pressure liquid at the second port P2 is compressed and the pressure increases, and the cargo handling 1 is decelerated and stopped.

On the other hand, when the cargo handling 1 is moved to the left in FIG. 2, the two-position switching valve 7 is also in the first port shown in the figure with the conduit switching valve 11 in the position for blocking the conduit shown in the drawing. Set the position to shut off P1 and the second port P2, and the 3-position switching valve 3
To the second position b. By doing so, the high pressure of the accumulator 6 acts on the pressure receiving surface 15b on the right side of the cylinder 2, and the atmospheric pressure is applied to the pressure receiving surface 15a on the left side, as in the case of the hydraulic device of FIG. Since the pressure acts, the one rod 15 receives the force in the left direction and is accelerated, and the cargo handling 1 moves leftward in FIG. 2 by the uniform acceleration motion.

When the moving speed of the one rod 15 reaches a desired speed, the conduit switching valve 11 is switched to a position for communicating the fifth conduit 25, and the two-position switching valve 7 is moved to the position shown in FIG. Switch from the position shown in to the first port P
1 and the second port P2 are brought into a position where they communicate with each other, and at the same time, the three-position switching valve 3 is returned to the third position (neutral position) shown in FIG.

Thereby, the single rod 1 of the cylinder 20
The pressures acting on the left and right pressure receiving surfaces 15a, 15b of 5 are substantially equal to the atmospheric pressure, and the areas of the left and right pressure receiving surfaces 15a, 15b are different, but the forces acting on the respective pressure receiving surfaces 15a, 15b are small. Therefore, both the single rod 15 and the cargo handling 1 make a substantially constant velocity motion to the left. At this time, the cylinder 20
Then, the pressure receiving area of the left pressure receiving surface 15a is the right pressure receiving surface 1
Since it is larger than the pressure receiving area of 5b, the first port P1
The pressure liquid discharged from the cylinder is larger than the pressure liquid flowing into the cylinder 20 through the second port P2. The difference in the amount of hydraulic fluid between the two is determined by pushing the check valve 12 open and
It is returned to the reservoir tank 5 through the pipeline 25.

Next, in order to stop the one rod 15 which moves to the left together with the cargo handling 1, the two-position switching valve 7 is set to the first position with the conduit switching valve 11 in the position for blocking the conduit. The port P1 and the second port P2 of the above are set to the position where they are cut off from each other, and the three-position switching valve 3 is set to the third position (the neutral position).
Then, as in the case of the hydraulic device of FIG. 1,
The pressure liquid on the side of the first port P1 in the cylinder 2 is compressed and the pressure rises, whereby the force that pushes it back to the right in FIG. 2 acts on the cargo handling 1, and the cargo handling 1 is decelerated. Stop. At this time, when the pressure at the first port P1 becomes higher than the pressure at the accumulator 6, the pressure fluid pushes open the check valve 8a and returns to the accumulator 6 through the first conduit 21 and accumulates there. Is similar to that of the hydraulic device of FIG.

When the cargo handling 1 moves to the left in FIG. 2 together with the single rod 15, the second port P
Although the pressure liquid tries to flow into the cylinder 20 through the second port 2, the second port P2 is blocked from the first port P1 by the two-position switching valve 7, so that the pressure receiving surface 15b on the right side in the cylinder 20 side is closed. The pressure will be low. When the pressure becomes lower than the pressure in the reservoir tank 5, the hydraulic fluid from the reservoir tank 5 opens the check valve 9b to open the fourth conduit 24.
The point of flowing into the second port P2 through the same is the same as in the case of the hydraulic device of FIG. The fifth conduit 25 is not provided on the first port P1 side, but the check valve 12 is provided in the free flow direction from the second port P2 to the reservoir tank 5 as shown by the phantom line in FIG. Even if the pipe switching valve 11 is provided, the same operational effect can be obtained.

[0053]

As described above, according to the present invention, when the load applied to the rod of the cylinder as a load is heavy, even if the load is frequently started and stopped repeatedly, the load is decelerated and stopped. The inertia energy due to the movement of the cargo handling consumed at the time of the operation is converted into the pressure of the fluid and stored in the fluid energy storage means, and the accumulated fluid energy can be used when the cargo handling is moved next time. It consumes less. Further, by recirculating and accumulating the pressure generated in the pipeline during deceleration and stop of the cargo handling to the fluid energy storage means, even when the heavy cargo handling is stopped, it is possible to reduce the vibration and noise for a short time. Can be stopped at.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a cylinder-driven hydraulic device for explaining a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing a cylinder-driven hydraulic device for explaining a second embodiment of the present invention.

FIG. 3 is a circuit diagram showing an example of a conventional cylinder-driven hydraulic device.

[Explanation of symbols]

 2, 20: Cylinder 3: 3 position switching valve 4: Auxiliary pump 5: Reservoir tank 6: Accumulator (fluid energy storage means) 7: 2 position switching valve 8a, 8b, 9a, 9b, 10, 12: Check valve 13 : Both rods 13a, 13b, 15a, 15b: Pressure receiving surface 15: Single rod 21: First pipe line 22: Second pipe line 23: Third pipe line 24: Fourth pipe line 25: Fifth pipe line Pipeline

Claims (2)

[Claims] 1. A double rod type cylinder having equal left and right pressure receiving surfaces, a fluid energy storage means, a low pressure reservoir tank, and an auxiliary pump for supplying a pressure fluid to the fluid energy storage means. A cylinder-driven hydraulic device, comprising: a first port and a second port for supplying or discharging pressurized liquid to the pressure-receiving surfaces of the cylinder, respectively.
A first line and a second line in the free flow direction that communicate with the fluid energy storage means via check valves, respectively, and from the reservoir tank via the check valves to the first port and the second port, respectively. A third pipe line and a fourth pipe line in a free flow direction which respectively communicate with the two ports, a two-position switching valve and a three-position switching valve are provided, and the two-position switching valve is connected to the first port. And a second port are connected so as to be switchable between a position where they communicate with each other and a position where they are shut off from each other, and the three-position switching valve, the fluid energy accumulating means to the first port, and the second port to the second port. A first position for communicating with the reservoir tank, a second position for communicating the fluid energy storage means with the second port, and a second position for communicating the first port with the reservoir tank, and the first port. Second po Hydraulics of the cylinder drive, characterized in that provided switchable preparative into a third position which closes each. 2. A single rod type cylinder having different left and right pressure receiving surfaces, a fluid energy storage means, a low pressure reservoir tank, and an auxiliary pump for supplying a pressure fluid to the fluid energy storage means. A cylinder-driven hydraulic device, comprising: a first port and a second port for supplying or discharging pressurized liquid to the pressure-receiving surfaces of the cylinder, respectively.
A first line and a second line in the free flow direction that communicate with the fluid energy storage means via check valves, respectively, and from the reservoir tank via the check valves to the first port and the second port, respectively. A free-flow-direction third and fourth conduits respectively communicating with the two ports, and a free-flow-direction check valve from either the first port or the second port toward the reservoir tank And a fifth conduit provided with a conduit switching valve for switching between communication and interruption of the conduit, and two positions for switching between a position for communicating the first port and the second port with each other and a position for disconnecting the second port. A switching valve; a first position for communicating the fluid energy storage means with the first port and a second position for communicating the second port with the reservoir tank; and the fluid energy storage means for the second port.
And a three-position switching valve that switches between a second position for communicating the first port with the reservoir tank and a third position for closing the first port and the second port, respectively. A cylinder-driven hydraulic device characterized by being provided.