JPS6361278B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic control device that includes a pair of cylinders and synchronizes them, with particular consideration given to safety even when the pipe line of one cylinder is damaged.

For example, in an elevator equipped with a pair of lift cylinders, if the conduit of one of the lift cylinders were damaged, there was a risk that the cargo being lifted or lowered would fall, but this invention can also avoid this risk. This is how it was done.

As a device of this kind, a device disclosed in Japanese Utility Model Application Publication No. 17300/1983 has been known.

The disadvantage of this safety device is that it requires two down control valves, which also increases costs.

It is an object of the present invention to solve the above-mentioned drawbacks of the prior art by using only one down control valve.

This will be explained below for each embodiment related to an elevator, and FIG. 1 is a circuit diagram common to each embodiment.

That is, in FIG. 1, a pair of lift cylinders 1 and 2 have a loading platform 5 fixed between the upper ends of their piston rods 3 and 4, and a cargo is placed on this loading platform. Both piston rods 3 and 4 are mechanically interlocked by a mast (not shown) or the like.

A down control valve C is provided at the bottom of the cylinder chamber 6 of one of the lift cylinders 1, and the other lift cylinder 2 is provided with a down control valve C.
The cylinder chamber 7 is communicated with this down control valve C via a conduit 8, and the control valve C is communicated with a switching valve 10 via a conduit 9.

However, in each of the embodiments described below, the structure of the down control valve C described above is slightly different.

First, the first embodiment shown in FIG. 2 will be explained.

The down control valve C in this first embodiment is located at the bottom of one lift cylinder 1.
The valve body 11 is inserted from the direction perpendicular to the axis of the cylinder. A spool 12 is housed inside the valve body 11, and a communication chamber 13 is formed between the inner end of the valve body 11 and the bottom.
This communication chamber 13 directly communicates with one of the cylinder chambers 6 through a communication hole 14, and also communicates directly with one cylinder chamber 6 through a communication hole 14.
5, it also communicates with the pressure chamber 16 above the spool 12. However, this check valve 1
5 allows flow only from the cylinder chamber 6 to the pressure chamber 16.

Reference numeral 17 in the figure is a spring holder for the check valve 15, and the oil that has passed through the check valve 15 is transferred to the hole 1.
8 into the pressure chamber 16, and the spring receiver 17 also functions as a stopper for the spool 12.

Furthermore, a through hole 19 and a control orifice 20 are formed in the valve body 11 .

The through hole 19 communicates with the cylinder chamber 6 via a first detection orifice 21 formed on the bottom of the lift cylinder 1, and also corresponds to an annular groove 22 formed on the spool 12. This annular groove 2
2 communicates with a relay chamber 24 through a spool hole 23 formed in the spool 12.

On the other hand, the control orifice 20
It communicates with the relay chamber 24 through an annular groove 25 and a spool hole 26 formed in
It also communicates with a switching valve 10 via a line 7 and a line 9.

A second detection orifice 26 is formed at the outer end of the valve body 11, and this second detection orifice 28 is communicated with the cylinder chamber 7 of the other lift cylinder via the pipe 8.

A spring 29 acts on the spool 12, and the spool 12 is normally maintained in the state shown. That is, the upper end of the spool 12 is brought into contact with the spring receiver 17.

Further, in the first detection orifice 21, when the spool 12 moves significantly against the spring 29, the through hole 19 and the annular groove 22 become different, so this is essentially the same as the opening area of the orifice 21 becoming smaller. It turns out.

Furthermore, when the spool 12 moves against the spring 29, the control orifice 20 also moves into the annular groove 2.
5 and its control orifice 20 are different,
This is essentially the same as the opening area of the control orifice 20 becoming smaller.

When the switching valve 10 is now switched to communicate the supply and discharge hole 27 with the pump, oil from the pump flows into the relay chamber 24 through the supply and discharge hole 27 and the control orifice 20, and the oil flows into the cylinder chambers 6 and 7. At the same time, it flows into That is, it flows into one cylinder chamber 6 through the first detection orifice 21, and into the other cylinder chamber 7 from the second detection orifice 28 through the conduit 8, raising the lift cylinders 1 and 2 at the same time. .

When the switching valve 10 is then switched to connect the supply/discharge hole 27 to the tank, the lift cylinders 1 and 2 begin to descend, and the oil flow path at that time is as follows.

That is, the oil in the other cylinder chamber 7 is depressurized by the second detection orifice 28 and flows into the relay chamber 24 . At the same time, the oil in one cylinder chamber 6 flows into the relay chamber 24 through the first detection orifice 21, but when the oil passes through the first detection orifice 21, a pressure difference is generated before and after the oil passes through the first detection orifice 21. The differential pressure then passes through the check valve 15 to the pressure chamber 16.
Since the spool 12 is introduced into the spring 2
Move against 9. This movement of spool 12 causes control orifice 20 to close slightly.

If the opening area of the control orifice 20 becomes smaller, the discharge flow rate therefrom is restricted, and the lowering speed of the lift cylinders 1 and 2 is slowed down.

Further, at this time, if the actual opening area of the control orifice 20 becomes too small and the pressure in the relay chamber 24 becomes higher than the pressure in the pressure chamber 16, the spool 1
2 rises, increasing the effective opening area of the control orifice 20. Therefore, this spool 12 also has the function of a float control valve.

Next, if the conduit 8 is damaged, only one cylinder 1 will support the entire load, so the differential pressure across the first detection orifice 21 will become even greater, causing the spool 12 to move further against the spring 29. . Therefore, the actual opening areas of the first detection orifice 21 and the control orifice 20 are further reduced, thereby preventing the loading platform 5 from falling suddenly.

Note that the second detection orifice 28 is located in the cylinder chamber 7.
This is to maintain the differential pressure before and after the first detection orifice 21 by dropping the pressure oil from the first detection orifice 21. Therefore, it is desirable that both detection orifices 21 and 28 have approximately the same diameter.

Next, a second embodiment shown in FIG. 3 will be explained.

The down control valve C in this second embodiment has its valve body 30 integrated with the bottom of the lift cylinder 1. This valve body 30 is equipped with a spool 31 perpendicular to the axis of the cylinder, and one cylinder chamber 6
A communication hole 32 that opens directly to the switching valve 10 and a supply/discharge hole 33 that communicates with the switching valve 10 via the pipe line 9 are formed. Further, annular grooves 34 and 35 are formed at the inner ends of the communication hole 32 and the supply/discharge hole 33. Furthermore, a plug 3 attached to the outer end of this valve body 30
A second detection orifice 37 is formed in the cylinder 6, and this second detection orifice 37 communicates with the other cylinder chamber 7 via a conduit 8.

The spool 31 housed in the valve body 30 is normally held at the position shown in the figure by the force of a spring 38 interposed between the spool 31 and the plug 36.

That is, in the state shown above, the spool 3
The through hole 39 and the control orifice 40 formed at 1 correspond to the annular grooves 34 and 35, respectively.

A first detection orifice 41 is opened in the center of the through hole 39, and one cylinder chamber 6
When the oil passes through the first detection orifice 41, a pressure difference is generated before and after the oil passes through the first detection orifice 41. The differential pressure generated before and after the first detection orifice 41 pushes open the check valve 42 and is introduced into the pressure chamber 43, but the pressure introduced into the pressure chamber 43 causes the spool 31 to resist the spring 38. It is something that moves. The through hole 39 and the annular groove 34 are made so that the annular groove is considerably larger, and only when the spool 31 moves significantly, they are offset, and the opening area of the first detection orifice 41 is substantially reduced. It is something to do.

Further, the control orifice 40 and the annular groove 35 are in a relationship such that when the spool 31 moves against the spring 38 as described above, the relationship is such that the actual opening area of the control orifice 40 is reduced.

However, when the switching valve 10 is switched to connect the supply/discharge hole 33 to a pump (not shown), oil from the pump flows into the relay chamber 44 through the control orifice 40. The oil that has flowed into the relay chamber 44 flows into the cylinder chambers 6 and 7, respectively. That is, the air flows into one cylinder chamber 6 through the detection orifice 41, the through hole 39, and the communication hole 32. Further, the air flows into the other cylinder chamber 7 through the second detection orifice 37 and the conduit 8.

Since oil flows into both cylinder chambers 6 and 7 at the same time as described above, both lift cylinders 1 and 2 rise simultaneously.

After lift cylinders 1 and 2 rise, switching valve 1
0 and communicates the supply/discharge hole 33 with a tank (not shown), the lift cylinders 1 and 2 begin to descend due to the load, but the oil flow path at that time is as follows.

That is, the oil in the other cylinder chamber 7 is depressurized by the second detection orifice 37 and flows into the relay chamber 44 . At the same time, the oil in one cylinder chamber 6 flows into the relay chamber 44 through the first detection orifice 41, but when the oil passes through the first detection orifice 41, a pressure difference is generated before and after the oil passes through the first detection orifice 41. The differential pressure then passes through the check valve 42 to the pressure chamber 43.
Since the spool 31 is introduced into the spring 3
Move against 8. In this way, spool 3
1 moves, the control orifice 4 is moved as described above.
The actual opening area of 0 becomes smaller.

If the effective opening area of the control orifice 40 is reduced, the flow rate of discharge therefrom is restricted, thereby slowing down the downward speed of the lift cylinders 1, 2.

At this time, if the actual opening area of the control orifice 40 becomes too small and the pressure in the relay chamber 44 becomes higher than the pressure in the pressure chamber 43, the spool 3
1 rises, increasing the effective opening area of the control orifice 40. Therefore, this spool 31 also has the function of a float control valve.

Note that when the spool 31 rises as described above, the oil in the pressure chamber 43 leaks from around the spool 31.

Next, if the pipe line 8 is damaged, the entire load on the loading platform 5 will be supported by one lift cylinder 1, so the differential pressure across the detection orifice 41 will further increase, and the pressure within the pressure chamber 43 will also increase. Become. The higher the pressure inside the pressure chamber 43, the more
The spool 31 moves further against the spring 38, further reducing the effective opening area of the first detection orifice 41 and the control orifice 40.
To prevent a sudden fall of a loading platform 5.

It goes without saying that the second detection orifice in this embodiment also performs the same function as in the first embodiment.

The third embodiment shown in FIG. 4 has almost the same configuration as the second embodiment, so only the differences will be explained.

That is, in this third embodiment, the second detection orifice 45 is formed in the spool 46, and
This second detection orifice 45 corresponds to an annular groove 47 formed in the valve body 30.

The annular groove 47 is made sufficiently larger than the second detection orifice 45 so that its opening area is always constant regardless of the movement of the spool 46.

Everything else is the same as in the second embodiment.

The fourth embodiment shown in FIG. 5 is substantially different from the first embodiment, but the differences in construction are as follows.

That is, in this fourth embodiment, the valve body 4
8 is provided along the axis of the cylinder 1, and its inner end directly faces the cylinder chamber 6. Since the valve body 48 is made to directly face the cylinder chamber 6 in this way, the communication chamber 13 and the communication hole 1 as in the first embodiment are
4 is no longer necessary, and the first detection orifice 49 is provided in the valve body 48 and opens directly into the cylinder chamber 6.

Further, the second detection orifice 50 is connected to the spool 12.
The opening area is always maintained at a constant level regardless of the movement of the spool 12.

The rest is the same as the first embodiment.

Although all of the above embodiments are provided with a second detection orifice, this second detection orifice may not necessarily be provided.

Without this second detection orifice, the oil in the cylinder chamber 7 of the lift cylinder 2 would flow directly into the relay chamber 24 or 44 and out through the control orifice 20 or 40. However, the oil in the cylinder chamber 6 of the lift cylinder 1 also flows through the first detection orifice 2 as described above.
1 or 37, a pressure difference is generated before and after it, moving the spool and narrowing the opening of its control orifice. In other words, the control orifice will function satisfactorily even without the second detection orifice.

However, providing the second detection orifice has the advantage of improving the load balance between the cylinders 1 and 2.

As is clear from the above description, according to the hydraulic control device of the present invention, the down control valve is directly attached to the bottom of one cylinder, and the cylinder chamber of the other cylinder is communicated with the down control valve. The number of pipes can be reduced, and the number of damaged parts will be reduced accordingly.

Furthermore, even if the pipe line of the other lift cylinder is damaged, the return side of one lift cylinder is throttled to reduce the discharge flow rate and slow down its descending speed, so the platform will not fall suddenly.

[Brief explanation of drawings]

The drawings show embodiments of the present invention; FIG. 1 is a circuit diagram common to each embodiment, FIG. 2 is an enlarged sectional view of the main part of the first embodiment, and FIG. 3 is a main part of the second embodiment. FIG. 4 is an enlarged sectional view of the main part of the third embodiment, and FIG. 5 is an enlarged sectional view of the main part of the fourth embodiment. 1, 2...Cylinder, 6,7...Cylinder chamber,
C... Down control valve, 10... Switching valve, 11, 30, 48... Valve body, 12, 3
1, 46... Spool, 20, 40... Control orifice, 21, 41, 49... First detection orifice, 28, 37, 45, 50... Second detection orifice.

Claims (1)

[Claims] 1 A down control valve is provided at the bottom of one of the pair of cylinders, while the cylinder chamber of the other cylinder is communicated with this down control valve, and this control valve has a spool built into its valve body. In addition, a first detection orifice communicating with the cylinder chamber of the one cylinder is formed, and the differential pressure across the first detection orifice is guided to the end face of the spool. A hydraulic control device in which only a control orifice communicating with the first detection orifice and the switching valve is float-controlled by the moving spool.