JPH0535203Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a single-acting cylinder cushion device used, for example, in a forklift.

(Prior Art) Generally, a single-acting cylinder used for a forklift or the like lifts a load W in the following manner under the configuration shown in FIG. That is, hydraulic oil is supplied to the bottom chamber 52 of the cylinder 51 by a pump (not shown), and the supply pressure is used to push down the piston 53 and lift the load W.

Further, when lowering the load W, the hydraulic oil in the bottom side chamber 52 is drained. As a result, the piston 53 is raised by the weight of the load W, and the load W is lowered.

(Problem to be solved by the present invention) However, in this type of single-acting cylinder,
Since there is no oil in one of the chambers, for example the rod side chamber, it was not possible to provide a cushioning device.

Therefore, when the load W reaches the maximum rising position,
The lower part 53a of the piston is the lower part 51 of the cylinder 51.
It had the disadvantage that it collided strongly with the cylinder a, damaging the piston and cylinder.

The object of this invention is to provide a single-acting cylinder cushioning device that can eliminate the above-mentioned drawbacks.

(Means for solving the problem) This idea is based on a single-acting cylinder in which hydraulic oil is supplied and discharged only from the bottom side of the cylinder tube, and the piston rod connected to the piston extends downward. It is something.

Based on the above-mentioned single-acting cylinder, this invention provides a vertically movable spacer in the rod side chamber to which no hydraulic oil is supplied, and divides the oil reservoir chamber and cushion chamber with this spacer as a boundary. Hydraulic oil is stored in these oil reservoir chambers and the cushion chamber, and the oil reservoir chamber is connected to an oil tank provided separately from the cylinder tube via a drain port formed on the cylinder tube side.
Moreover, the spacer has a cylindrical part whose outer periphery is in contact with the cylinder tube side, a horizontal part provided at the upper end of this cylindrical part, a protrusion formed on this horizontal part, and a radial direction of this protrusion. A notch is formed at the outer peripheral corner of the horizontal portion and allows constant communication between the oil reservoir chamber and the drain port,
Moreover, a flow passage is formed between this horizontal part and the piston rod, and the oil reservoir chamber and the cushion chamber are normally communicated via this flow passage, and when the piston comes into contact with the protrusion of the spacer, this flow passage It is characterized by a structure in which the two chambers communicate with each other through a diaphragm.

(Function) Since this invention is constructed as described above, when the piston moves toward the cushion chamber and hits the spacer, the oil reservoir chamber and the cushion chamber communicate with each other via the flow path and the throttle.

In this state, when the piston further pushes the spacer and moves it, the hydraulic oil filling the cushion chamber flows out to the oil reservoir chamber through the throttle.

Additionally, if the piston moves as described above, the volume of the oil reservoir chamber will also decrease, so the hydraulic oil in the oil reservoir will flow into the oil reservoir through the notch formed in the spacer and the drain port formed on the cylinder tube side. be discharged.

When the piston moves in the opposite direction, the two chambers communicate with each other through the flow passage.
In this case, the flow path resistance due to the restriction is eliminated, and the piston rises smoothly.

Also, at this time, the volumes of the oil reservoir chamber and the cushion chamber expand again, so hydraulic oil from the oil tank is sucked into both chambers.

(Effect of the invention) With a double-acting cylinder, both the bottom side and the rod side are always filled with hydraulic oil, so it is easy to install a cushion device.

However, in the case of a single-acting cylinder, especially in the case of a single-acting cylinder configured to lead hydraulic oil only to the bottom side, as in the case of this invention, it is possible to obtain the desired amount while storing hydraulic oil in a part of the rod side. It is very difficult to bring out the cushioning effect.

However, according to the cushion device of this invention,
Since the oil tank was installed separately from the cylinder tube,
Even single-acting cylinders can now be equipped with a cushion device to prevent the piston from bottoming out.

Moreover, since a notch is formed in the outer circumferential corner of the horizontal portion of the spacer to allow constant communication between the oil reservoir and the drain port, the amount of oil in the oil reservoir is always stable. In other words, the fact that the cutout is formed at the outer corner of the horizontal part of the spacer means that the passage connecting the oil sump chamber and the oil tank can always be maintained at the bottom of the oil sump chamber, regardless of the moving position of the spacer. Therefore, suction performance is improved when the volume of the oil reservoir chamber or cushion chamber is expanded.

This improvement in suction performance is also a major reason why single-acting cylinders have come to be equipped with cushion devices. This is because, if hydraulic oil for the cushion is simply poured into a part of the rod side chamber that normally does not contain hydraulic oil, it will scatter or leak, resulting in a decrease in the amount of oil.
However, as the amount of oil decreases, the cushioning effect naturally decreases. but,
In the case of this invention, since the amount of oil can be stably replenished from the oil tank as described above, the cushion effect will not be impaired due to a decrease in the amount of oil.

Also, without installing a separate oil tank like this idea,
When trying to form an oil sump chamber in a single-acting cylinder,
In order to prevent the hydraulic oil from decreasing, this oil sump chamber must be separated from other parts. If an attempt is made to partition the oil sump chamber in this manner, a partition wall or the like is required, and the volume of the oil sump chamber is ultimately reduced by the partition wall. However, when the amount of oil in the oil reservoir chamber decreases, the cushioning effect inevitably deteriorates. However, according to this invention, since a partition wall or the like is not required, a sufficient volume of the oil reservoir chamber can be secured and the desired cushioning effect can be exhibited.

(Embodiment of the present invention) In Fig. 1, 1 is a cylinder tube, 2 is a flange connected to the lower part of the cylinder tube 2, 3 is a piston rod, 4 is a piston, 5 is an oil seal, 6 is a bottom side chamber, and 7 is a flange connected to the lower part of the cylinder tube 2. 8 is a dust seal, and 9 is an oil seal.

A drain port 11 is provided at the top of the flange 2.
is formed. This drain port 11 communicates via a drain pipe 12 with an oil tank (not shown) provided separately from the cylinder tube 1.

On the other hand, a spacer 14 is provided in the rod side chamber 13 so as to be movable up and down. This spacer 14 is normally held in the position shown by a spring 17. The rod side chamber 13 is divided into an oil reservoir chamber 15 and a cushion chamber 16 by the spacer 14 thus constructed.

Further, the spacer 14 has an outer periphery connected to the flange 2.
The cylindrical portion 14a brought into contact with the cylindrical portion 14a;
The horizontal portion 14b provided at the upper end of the
The protrusion 14c formed on b and this protrusion 14c
a diaphragm 22 formed in the radial direction of the horizontal part 1;
A notch 21 formed at the outer peripheral corner portion of 4b to allow constant communication between the oil reservoir chamber 15 and the drain port 11.
It is equipped with

Moreover, the horizontal portion 14b and the piston rod 3
A flow path 23 is formed between the oil reservoir chamber 15 and the cushion chamber 16, and the oil reservoir chamber 15 and the cushion chamber 16 are normally communicated through the flow path 23. And piston 4 is spacer 1
When contacting the protrusion 14c of 4, this flow path 23
The two chambers 15 and 16 communicate with each other via the aperture 22.

Furthermore, a notch 21 is formed at a corner of the horizontal portion 14b to allow constant communication between the oil reservoir chamber 15 and the drain port 11, regardless of the moving position of the spacer 14.

A clearance (not shown) exists between the spacer 14 and the flange 2 thus constructed.
When the piston 4 is in the upper position, the hydraulic oil from the drain port 11 is always collected in the rod side chamber 13 as shown in the figure.

Next, the operation of the embodiment constructed as described above will be explained.

Hydraulic oil is supplied to the bottom side chamber 6, and the piston 4 descends due to the supply pressure, and as the piston 4 descends, the hydraulic oil in the oil reservoir chamber 15 passes through the notch 21, drain port 11, and drain pipe 12. It is discharged into an oil tank (not shown).

The piston 4 further descends and hits the protrusion 14c of the spacer 14, and as the piston 4 descends together with the spacer 14 against the spring 17, as shown in FIG. Through the throttle 22 and the clearance, the drain port 11 and the drain pipe 12
and is discharged into the oil tank.

At this time, the downward speed of the piston 4 is reduced due to the flow path resistance of the throttle 22 and the clearance. This prevents the piston 4 from strongly colliding with the rod cover 7 via the spacer 14.

Next, when the hydraulic oil in the bottom side chamber 6 is drained, the load W
The piston 4 rises due to its own weight (see Figure 3). As the piston 4 rises, hydraulic oil is sucked up from the oil tank through the drain pipe 12 and supplied to the cushion chamber 16. When the piston 4 further rises to the position shown in FIG. 1, hydraulic oil accumulates in the oil reservoir chamber 15 as shown.

According to the embodiment described above, since the oil tank is provided separately from the cylinder tube 1, it is now possible to provide a cushion device for preventing the piston from bottoming out even in a single-acting cylinder.

Moreover, since the notch 21 is formed in the outer peripheral corner of the horizontal portion 14b of the spacer 14 to allow constant communication between the oil reservoir chamber 15 and the drain port 11, the amount of oil in the oil reservoir chamber 15 is always stable. .
In other words, the fact that the notch 21 is formed at the outer corner corner of the horizontal part 14b of the spacer 14 means that the passage connecting the oil reservoir chamber 15 and the oil tank is always connected to the oil reservoir chamber regardless of the moving position of the spacer 14. 15
Since the suction performance can be maintained at the bottom of the oil reservoir chamber 15 or the cushion chamber 16 when the volumes are expanded, the suction performance is improved.

This improvement in suction performance is also a major reason why single-acting cylinders have come to be equipped with cushion devices. This is because, if hydraulic oil for the cushion is simply put into a part of the rod side chamber 13 where no hydraulic oil is normally placed, the oil will scatter or leak, resulting in a decrease in the amount of oil. However,
As the amount of oil decreases, the cushioning effect naturally decreases. However, in the case of this embodiment, since the amount of oil can be stably replenished from the oil tank as described above, the cushion effect will not be impaired due to a decrease in the amount of oil.

Furthermore, if an oil reservoir chamber 15 is formed in a single-acting cylinder without a separate oil tank as in this embodiment, the oil reservoir chamber 15 is separated from other parts in order to prevent the hydraulic fluid from decreasing. Must. If an attempt is made to partition the oil reservoir chamber 15 in this way, a partition wall or the like will be required, and the volume of the oil reservoir chamber 15 will eventually be substantially reduced by the partition wall. However, when the amount of oil in the oil reservoir chamber 15 decreases, the cushioning effect inevitably deteriorates.
However, according to this embodiment, since a partition wall is not required, a sufficient volume of the oil reservoir chamber 15 can be secured, and the desired cushioning effect can be exerted.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the cylinder according to this invention, FIG. 2 is a sectional view of the piston in a lowered state, and FIG. 3 is an explanatory view of the conventional cylinder. 1...Cylinder tube, 2...Flange, 4
... Piston, 6 ... Bottom chamber, 11 ... Drain port, 13 ... Rod side chamber, 14 ... Spacer, 14a ... Cylindrical part, 14b ... Horizontal part, 14
c... protrusion, 15... oil reservoir chamber, 16... cushion chamber, 22... throttle, 23... distribution passage.

Claims (1)

[Scope of utility model registration request] In single-acting cylinders in which hydraulic oil is supplied and discharged only to the bottom side of the cylinder tube and the piston rod connected to the piston extends downward, the spacer can be moved up and down into the rod side chamber where hydraulic oil is not supplied. The oil reservoir chamber and the cushion chamber are separated by the spacer, and hydraulic oil is stored in the oil reservoir chamber and the cushion chamber, and the oil reservoir chamber is provided with a drain port formed on the cylinder tube side. connected to an oil tank provided separately from the cylinder tube through the cylinder tube, and
The spacer has a cylindrical part whose outer periphery is in contact with the cylinder tube side, a horizontal part provided at the upper end of this cylindrical part, a protrusion formed on this horizontal part, and a radial direction formed in the protrusion. It is provided with a throttle and a notch formed in the outer circumferential corner of the horizontal part to allow constant communication between the oil reservoir chamber and the drain port, and furthermore, a flow path is formed between the horizontal part and the piston rod, so that the piston rod is not normally The oil reservoir chamber and the cushion chamber are communicated through the flow passage, and when the piston comes into contact with the protrusion of the spacer, the two chambers are communicated through the flow passage and the restriction. Single-acting cylinder cushioning device.