JPS6123921Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a cylinder drive device for controlling the elevation and descent of a cylinder constituting a lifter or the like.

[Conventional technology]

When lifting or lowering a load using a lifter using a cylinder, it is normally driven by supplying compressed air from a high-pressure air source to the cylinder via a directional control valve, and the Air discharged from the cylinder is discharged to the atmosphere via the directional switching valve.

However, since the air discharged from the cylinder as the cylinder is driven and returned has pressure, that is, a large amount of energy, it is problematic from the point of view of energy saving to discharge it directly into the atmosphere.

As a prior art for solving this problem, a cylinder drive device as shown in FIG. 4 was previously proposed (see Japanese Utility Model Application Publication No. 102/1983).

This cylinder drive device connects a head chamber 22 of a cylinder 21 to a pressure accumulating tank 25 in which the pressure of an air source 24 is reduced to a desired pressure by a pressure reducing valve 23, and a conversion pipe 28 provided with an electromagnetic proportional flow control valve 27. The rod chamber 28 of the cylinder 21 is communicated with the pressure accumulator tank 25 through a recirculation line 29 having a pressure control valve 30 branched from the conversion line.

In this cylinder drive device, in the illustrated state where the load A is lowered and stopped, the electromagnetic proportional flow control valve 27 is energized and the pressure control valve 3 is energized.
When the energization of 0 is cut off, an amount of air corresponding to the amount of energization of the electromagnetic proportional flow control valve 27 flows from the pressure accumulator tank 25 into the head chamber 22, raising the load A with good controllability.

In addition, when the load A is lowered, the pressure control valve 30
When energized, the pressure air in the pressure storage tank 25 is reduced in pressure and flows into the rod chamber 28, and this acting force and the acting force of the load A overcome the acting force of the head chamber 22 and lower the load A. Along with this, the pressurized air in the head chamber 22 flows through the pressure accumulator tank 25 and is recovered. When the load A reaches the lower end, the electromagnetic proportional flow control valve 27 is de-energized and the head chamber 22 is closed.

The above-mentioned prior art has the advantage that since the amount of pressurized air supplied and discharged from the head chamber 22 is controlled by the amount of energization of the electromagnetic proportional flow control valve 27, it is possible to perform high-speed movement in the middle of a stroke and a buffer stop at the end of the stroke. It is excellent in that it has excellent controllability of the cylinder 21, and can suppress changes in the internal pressure of the pressure storage tank 25 as much as possible according to the stroke of the cylinder 21, thereby making the capacity of the pressure storage tank 25 as small as possible. There are, but
There is a problem with starting performance in the above process.

That is, at the descending end when the load A is raised and lowered repeatedly, the air pressure reduced by the pressure control valve 30 is supplied to the rod chamber 28 of the cylinder 21, and the combined force of this air pressure and the load is applied to the head chamber. The load is held in that position by overcoming the force exerted by the air pressure on the side.

When the load is increased from this state, the rod chamber 28 is opened to the atmosphere, and the head chamber 22 is communicated with the pressure storage tank 25 to supply air pressure to the head chamber 22. Since the air pressure acts as back pressure, it takes time to reverse the acting forces in both chambers, which causes a delay in starting the upward stroke.

In order to reduce this start-up delay, the air pressure in the rod chamber 28 can be discharged when the load A reaches the descending end to eliminate the back pressure during the upward movement. Since the relationship is reversed, the load increases unnecessarily, which is very dangerous. Even if the head chamber 22 is isolated from the pressure storage tank 25 by the electromagnetic proportional flow control valve 27, the piping from the head chamber 22 to the electromagnetic proportional flow control valve 27 has a considerable volume, so the air pressure inside it will cause a load. A is lifted and it is difficult to keep it in place.

[Problem that the invention attempts to solve]

The present invention is based on the above-mentioned previously proposed cylinder drive device in which a part of the exhaust gas is recovered and stored in a pressure accumulator tank for effective use of energy. The technical problem is to prevent dangerous and unnecessary increases in the load, eliminate back pressure when the load increases, and minimize the delay in starting the increase.

[Means for solving problems]

In order to solve the above problems, in this invention,
The head chamber of the cylinder that drives the load up and down and the pressure accumulator tank that has the pressure necessary to increase the load are communicated via a balanced pipe equipped with an electromagnetic proportional flow control valve that provides a flow rate proportional to the amount of energization. and communicating the rod chamber in the cylinder and the pressure accumulating tank via a reflux passage equipped with a pressure control valve,
The pressure control valve switches the rod chamber into communication with the pressure accumulation tank and the atmosphere, and when communicating with the pressure accumulation tank, reduces the pressure in the pressure accumulation tank to a pressure that can lower the load against the air pressure in the head chamber. A pressure regulating mechanism is attached to the head chamber, and the pressure regulating mechanism is set at a position where the air in the head chamber is lowered to an extent that the load does not increase, and at a position where the air in the head chamber is lowered to the extent that the load does not increase. A technical measure has been taken to enable switching between the position and the position where communication is cut off.

[Effect]

In the cylinder drive device configured as described above, in order to lower the load at the rising end, the head chamber is communicated with the pressure accumulation tank via the electromagnetic proportional flow control valve, and the rod chamber is communicated with the pressure accumulation tank via the pressure control valve. When this happens, the air from the pressure storage tank is reduced to the required pressure by the pressure control valve and flows into the rod chamber, and due to the combined force of this air pressure and the load, the load is reduced together with the piston by the force exerted by the air pressure in the head chamber. moves downward against the

In this case, air in the head chamber is sent to the pressure storage tank as the load is lowered, but the amount of air is controlled according to the amount of electricity applied to the electromagnetic proportional flow control valve.
Since the air pressure in the pressure storage tank is not rapidly sent to the pressure storage tank, and a part of the air pressure in the pressure storage tank is supplied to the rod chamber through the pressure control valve, pressure changes in the pressure storage tank are suppressed as much as possible, and therefore the air pressure is small. Even if a pressure storage tank with a large capacity is used, the pressure change in the pressure storage tank can be made sufficiently small.

When the load reaches the lower end, the electromagnetic proportional flow control valve is de-energized to isolate the head chamber from the pressure storage tank, and the pressure regulating mechanism discharges the air in the head chamber at a low pressure.At the same time, the pressure control valve closes the rod. Open the room to the atmosphere. As a result, the air pressure in the rod chamber is discharged without causing an increase in the load, and the load waits at the lower end in preparation for the upward stroke.

When increasing the load from this state, the communication between the head chamber and the pressure regulating mechanism is cut off, and the air in the pressure storage tank is allowed to flow into the head chamber via the electromagnetic proportional flow control valve. Since the rod chamber is at atmospheric pressure, the air pressure in this rod chamber does not act as back pressure during startup, and therefore, startup is performed quickly. In this case, the speed control of the drive in the upward direction is performed with good controllability by increasing/decreasing the amount of electricity supplied to the flow rate control valve.

[Effect of idea]

According to the cylinder drive device of the present invention, when the load reaches the lowering end, the pressure regulating mechanism lowers the pressure in the head chamber and at the same time opens the rod chamber to the atmosphere, thereby preventing a dangerous increase in the load. The load can be left on standby at the descending end with all the air pressure in the rod chamber discharged without this occurring, thereby eliminating back pressure during the upward stroke and speeding up its startup.

Also, as mentioned above, in order to accelerate the start of the rise,
Since all the air pressure in the rod chamber is exhausted, there is a possibility that the load will increase dangerously, but since the cylinder lifting speed is controlled by the amount of current supplied to the electromagnetic proportional flow control valve, The load can be raised and lowered with good controllability.

〔Example〕

Hereinafter, an embodiment of the present invention will be described in detail based on the drawings. In FIG. 1, a cylinder 1 constitutes a lifter for raising and lowering a load A, and a head chamber 2 in the cylinder 1 is connected to a pressure reducing valve 3. The pressure of the air source 4 is reduced to a desired pressure by the pressure accumulating tank 5, and the balanced pipe 6 is equipped with an electromagnetic proportional flow control valve 7.
The rod chamber 8 in the cylinder 1 is connected to the pressure accumulator tank 5 by a reflux line 9 having a pressure control valve 10 branched from the balance line 6.
Furthermore, a pressure regulating mechanism 11 consisting of a three-port switching valve 12 and a small-capacity pressure reducing tank 13 is connected to the head chamber 2.

The electromagnetic proportional flow control valve 7 closes the balance line 6 between the head chamber 2 and the pressure storage tank 5 when not energized, and opens steplessly with a valve opening proportional to the amount of energization when energized. The pressure control valve 10 is configured to flow from the pressure storage tank 5 into the head chamber 2 at a flow rate proportional to its valve opening degree, that is, the amount of energization.The pressure control valve 10 is configured as an electromagnetic proportional pressure control valve, When energized, the recirculation pipe 9 between the rod chamber 8 and pressure accumulator tank 5 is closed, and the rod chamber 8 is opened to the atmosphere, and when energized, the rod chamber 8 and pressure accumulator tank 5 are closed.
from the pressure accumulator tank 5 to the rod chamber 8 until the rod chamber 8 reaches a set pressure proportional to the amount of energization, that is, a pressure that can move the load down to the lower end against the air pressure in the head chamber 2. It is designed to allow air to flow in.

Note that if the air pressure supplied from the air source 4 is at the desired set pressure of the pressure storage tank 5, there is no need to provide the pressure reducing valve 3.

Next, the operation of the cylinder drive device described above will be explained.

FIG. 1 shows a case where the load A is at the lower end, and from this state the pressure control valve 10 is de-energized, the electromagnetic proportional flow control valve 7 and the 3-port switching valve 1
2 are both de-energized, the head chamber 2
does not communicate with the pressure accumulation tank 5 and the pressure reduction tank 13,
Further, the rod chamber 8 is isolated from the pressure storage tank 5 and is open to the atmosphere.

Now, if the electromagnetic proportional flow control valve 7 is energized in this state, a flow rate of air corresponding to the amount of energization will flow from the pressure storage tank 5 into the head chamber 2, and the cylinder rod 1a will support the load A at a speed corresponding to the flow rate. While doing so, make an upward stroke. With this rise, rod chamber 8
The air is discharged to the atmosphere from the pressure control valve 10, and as the pressure in the pressure storage tank 5 decreases due to the increase in the volume of the head chamber 2, air to compensate for the decrease in pressure is discharged from the air source 4 via the pressure reducing valve 3. The pressure storage tank 5 is replenished.

After this, in order to lower the load A again, the electromagnetic proportional flow control valve 7 is energized to keep the head chamber 2 and the pressure accumulation tank 5 in communication, and the pressure control valve 10 is energized to reduce the pressure from the pressure accumulation tank 5. It is sufficient to reduce the pressure and add it to the rod chamber 8. As a result, the acting force of the load A and the pressure accumulating tank 5 are applied to the rod chamber 8 side of the cylinder 1.
With the addition of the effect of the reduced pressure from the head chamber 2, the load A is lowered by overcoming the acting force on the head chamber 2 side.
As the load A decreases, pressurized air in the head chamber 2 is fed into the pressure storage tank 5 through the balance pipe 6, but the amount of air is controlled by the electromagnetic proportional flow control valve 7 and rapidly flows into the pressure storage tank 5. Also, since the pressure accumulator tank is communicated with the rod chamber 8 via the recirculation pipe 9, a part of the air that returns to the pressure accumulator tank flows back to the rod chamber 8, and the pressure accumulator tank 5 pressure rise is suppressed.

In addition, the speed of the above-mentioned load rise and fall strokes can be adjusted by changing the amount of current applied to the pressure control valve 10 or the electromagnetic proportional flow control valve 7, regardless of the slight pressure change in the pressure storage tank 5 that accompanies the stroke. This allows for high-speed movement in the middle of the stroke, a cushioned stop at the end of the stroke,
Furthermore, an emergency stop can be performed in the middle of a stroke.

When the load A reaches the lower end, the following operation is performed in preparation for the next upward stroke.

That is, the electromagnetic proportional flow control valve 7 is de-energized to cut off the head chamber 2 and the pressure accumulator tank 5, and the 3
The port switching valve 12 is energized to communicate the head chamber 2 and the decompression tank 13, and at the same time the pressure control valve 10 is de-energized to open the rod chamber 8 to the atmosphere. As a result, the rod chamber 8 becomes atmospheric pressure, and the air pressure in the head chamber 2 is reduced by flowing into the decompression tank 13, to the extent that the load A does not increase even if the rod chamber 8 becomes atmospheric pressure. Lower pressure.

If you want to increase the standby load again in this state, you can de-energize the 3-port switching valve 12 and energize the electromagnetic proportional flow control valve 7.
Since the pressure is reduced to atmospheric pressure and there is residual air pressure in the head chamber 2 and the conduit connected thereto, the response of the load is fast, and therefore the load A can be started at high speed.

FIG. 2 shows a different embodiment of the pressure regulating mechanism 11, which is composed of a 2-port switching valve 14 and a relief valve 15, thereby achieving the same effects as in the previous embodiment. It was designed so that

Next, an example of an experiment conducted based on the apparatus shown in FIG. 1 will be explained.

[Experimental conditions]

Load weight: 700kgf Cylinder: Inner diameter 180mm, Rod diameter 45mm, Stroke 800mm Accumulator tank: 79 Piping: Piping size 1B, Piping length 3m Pressure: Accumulator tank pressure P _T =4.3kgf/cm ² Rod chamber pressure P _r =2.6 kgf/cm ² Decompression tank: 0.7 Static constant pressure by connecting the decompression tank: P _t = 2.7 kgf/cm ² Figure 3 A shows when the pressure regulating mechanism 11 is not activated,
That is, the electromagnetic proportional flow control valve 7 and the pressure control valve 10
Both are turned on, the load A is placed on standby at the lower end with air pressures of 2.6 kgf/cm ² supplied to the rod chamber 8 and 4.3 kgf/cm ² supplied to the head chamber 2, and from that state the pressure control valve 10 is turned off. Figure B shows the case where the pressure regulating mechanism 11 is activated, that is, the pressure control valve 10 is turned off to open the rod chamber 8 to the atmosphere, and the electromagnetic proportional The flow control valve 7 is turned off, the 3-port switching valve 12 is turned on, the head chamber 2 is depressurized, the load A is placed on standby at the lower end, and the load is raised from that state. Therefore, when a pressure regulating mechanism is installed to adjust the pressure in the head and rod chambers,
It can be seen that the startup time was reduced from 0.25sec to 0.035sec, and the full stroke time was reduced from 2.53sec to 2.29sec.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing one embodiment of the present invention;
The figure is a circuit diagram showing different embodiments of the pressure regulating mechanism.
Figures A and B are diagrams showing experimental results, and Figure 4 is a circuit diagram of the prior art. DESCRIPTION OF SYMBOLS 1... Cylinder, 2... Head chamber, 5... Pressure storage tank, 6... Balance pipe, 7... Electromagnetic proportional flow control valve, 8
...Rod chamber, 9...Recirculation pipe, 10...Pressure control valve,
11...Pressure regulation mechanism.

Claims (1)

[Scope of utility model registration request] The head chamber of the cylinder that drives the load up and down and the pressure accumulator tank that has the pressure necessary to increase the load are communicated via a balanced pipe equipped with an electromagnetic proportional flow control valve that provides a flow rate proportional to the amount of energization. let me,
The rod chamber in the cylinder and the pressure accumulator tank are communicated via a recirculation pipe provided with a pressure control valve, and the pressure control valve is used to switch the rod chamber into communication with the pressure accumulator tank and the atmosphere, and to connect the pressure accumulator tank to the atmosphere. At the time of communication, the pressure in the pressure storage tank is reduced to a pressure that can lower the load against the air pressure in the head chamber, and the pressure is allowed to flow into the rod chamber, and a pressure regulating mechanism is attached to the head chamber, A cylinder drive device characterized in that the pressure regulating mechanism is configured to be switchable between a position where the air in the head chamber is lowered to an extent that the load does not increase and a position where communication for the lowering is cut off.