JPS642808B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a multi-stage hydraulic cylinder incorporating a cushioning device.

Multistage hydraulic cylinders, in which a plurality of movable cylinders reciprocate telescopically, are frequently used when long strokes are required and installation space is limited. Therefore, this type of multi-stage hydraulic cylinder is required to have the shortest possible installation dimensions, and it is customary to omit factors that increase the installation size, such as cushioning devices. there was. That is, as shown in FIG. 1, a cushion device built into a conventional fluid pressure cylinder has a cushion boss 2 protruding from the center of a piston 1 that is inserted into a cushion hole 3a of a head cover 3.
In this conventional cushion device, the fluid pressure chamber 4 sandwiched between the piston 1 and the head cover 3 is closed and connected to the supply/discharge passage 6 only through the constriction portion 5. However, in this conventional cushion device, the cushion Since the fluid pressure chamber 4, which acts as Because it is necessary to provide the check valve 8 for This went against the demand for shorter lengths. Furthermore, due to the structure of the multi-stage hydraulic cylinder, there were cases in which conventional cushioning devices could not be used.

Due to the special circumstances mentioned above, multi-stage hydraulic cylinders do not have a built-in cushioning device, but other means such as providing an external shock absorber, using the cylinder without reaching its stroke end, or It has been used to compensate for the operating speed of the engine by using it at a lower speed.

However, recently there has been a strong demand for higher efficiency, especially in the fields of machine tools and industrial machinery, and multi-stage hydraulic cylinders are also required to operate at high speed and have short installation dimensions. The advent of fluid pressure cylinders was eagerly awaited.

The present invention has been made in view of the above-mentioned circumstances, and it is an object of the present invention to provide a multistage hydraulic cylinder with a cushion that has short mounting dimensions and can obtain a sufficient cushioning effect for this type of cylinder.

An embodiment of the present invention will be described below. In FIG. 2, pistons 10, 11
movable cylinders 12 each having a base end side thereof,
13 are fitted one after another, and a flow passage 14 is provided in the piston 10 of the first movable cylinder 12 in its axial direction, thereby forming forward side fluid chambers 15, 16 of each movable cylinder 12, 13.
On the other hand, a communication pipe 17 extending in the axial direction is provided in the center of the piston 10 of the first movable cylinder 12, and in the radial direction of the piston 10,
A flow path 18 is provided in the tube 13a of the second movable cylinder 13, and a plurality of flow holes 19a, 19b, 19c are provided in the tube 13a of the second movable cylinder 13 in the vicinity of the connecting portion with the piston 11 to communicate the inside and outside of the tube 13a. The reciprocating side fluid chambers 20 and 21 are communicated with each other.

Here, the piston 10 of the first movable cylinder 12 is provided with an annular groove 22 corresponding to the opening to the outer periphery of the flow passage 18 provided in the radial direction. The piston 10 is provided with one or more throttle holes 23 communicating with the moving side fluid chamber 20 . On the other hand, the tube 9a of the basic cylinder has a thick wall portion 9b and a mounting portion 9c at both ends.
A head side supply/discharge port 24 and a rod side supply/discharge port 25 are formed in both thick portions 9b, respectively.
is provided. This rod side supply/discharge port 25 is
It opens into the reciprocating side fluid chamber 20 at a position slightly closer to the head side than the rod side end, and the first movable cylinder 1
When the piston 10 moves toward the rod side, that is, upward in FIG. 2, a cushioning action is performed slightly before the piston 10 comes into contact with the rod side end, and the flow path to the second movable cylinder 13 is switched. That is, when pressure is applied to the forward fluid chambers 15 and 16, back pressure is generated in the backward fluid chambers 20 and 21, but the back pressure on the second movable cylinder 13 side is due to the throttle resistance caused by the throttle hole 23. This becomes higher than the back pressure on the first movable cylinder 12 side, so the first movable cylinder 12 moves forward first. Then, slightly before the piston 10 reaches the rod side end, the fluid near the rod side end of the reciprocating side fluid chamber 20 is closed by the piston 10 and is discharged only from the throttle hole 23 to the rod side supply/discharge port 25. At almost the same time, the flow passage 18 is directly connected to the rod-side supply/discharge port 25 via the groove 22, so the second movable cylinder 13 then moves forward.

Also, the tube 13a of the second movable cylinder 13
A plurality of communication holes 19a, 19b, and 19c provided in the piston are arranged in parallel in the axial direction, and the diameters thereof become larger sequentially from the piston side. Therefore, the second movable cylinder 13 moves forward and the piston 11 opens the communication holes 19a, 19b, 19 slightly before reaching the rod side end.
The rods c are sequentially fitted into the rod cover 12a starting from the largest diameter and are closed, thereby constricting the discharge flow path of the reciprocating side fluid chamber 21 to obtain a cushioning effect.

Now, a cushion boss 26 is formed in the center of the piston 10 of the first movable cylinder 12 on the side facing the forward fluid chamber 15, and a cushion hole is formed in the head cover 9b to fit the cushion boss 26 with a small gap. 27 are provided. Cushion boss 2
6 has a recess 26a in the center of the end surface of a cylindrical object and has a smaller diameter at the connection part with the piston 10, and the axial length of this cushion boss 26 is longer than the depth of the cushion hole 27. There is also a through hole 26b penetrating from the recess 26a toward the outer circumference.
It has a small diameter throttle hole 26c that penetrates through the through hole 26b and the forward fluid chamber 15. Therefore, when the piston 10 moves back and the cushion boss 26 fits into the cushion hole 27, the fluid in the cushion hole 27 has its discharge flow path narrowed by the throttle hole 26c, and a cushion effect is obtained, and the tip of the cushion boss 26 is inserted into the cushion hole 27. It comes into contact with the bottom of the hole 27 and acts as a stopper.

The size of the cushion volume formed by the cushion boss 26 and the cushion hole 27 is:
It is sufficient that the cushion volume be approximately the same as the cushion volume on the rod end side of the second movable cylinder 13 described above. In other words, from the perspective of the entire fluid pressure cylinder,
Generally, there is no need to differentiate the cushioning effect during forward movement and backward movement, so it is sufficient to match the cushioning effect to the same degree as that of the second movable cylinder 13 having the smallest diameter. Therefore, the outer diameter of the cushion boss 26 can be made sufficiently smaller than the outer diameter of the piston 10, and since the forward fluid chamber 15 is always in direct communication with the head side supply/discharge port, the There is no need for a check valve to improve the rise of the head, and there is no need to provide a supply/discharge path or a supply/discharge port in the head cover 9d. For these reasons, even if the cushion boss 26 and the cushion hole 27 are provided, the increase in length of the head cover 9d and tube 9a can be kept to a minimum.

In this embodiment, the small-diameter throttle hole 26c is provided as a throttle flow path for the cushion, but instead of this, the fitting between the cushion boss 26 and the cushion hole 27 may be loosened, and the gap between them may be used as the throttle flow path.
In this case, if it becomes necessary to adjust the cushion effect, the bolts fixing the head cover 9d to the thick wall portion 9b may be loosened, the head cover 9d removed, and additional machining performed at the necessary locations.

A cushion device similar to the above-mentioned cushion device formed between the piston 10 of the first movable cylinder 12 and the head cover 9d of the basic cylinder 9 is connected to the piston 11 of the second movable cylinder 13 and the first movable cylinder 1.
It is formed between the two pistons 10. However, since the piston 10 has a circular passage pipe 17 protruding from the piston 10 and this passage pipe 17 passes through the piston 11, the piston 11 has a circular cushion boss 28, and the piston 10 has a circular cushion boss 28. A fitting hole 29 is formed, and the cushion boss 28 is provided with a small diameter aperture hole 28a.

In the multistage fluid pressure cylinder with a cushion configured as described above, when pressurized fluid is first supplied to the head side supply/discharge port 24, the first movable cylinder 12 moves forward and exerts a cushioning action at the rod side end of the piston 10. At the same time, the flow path 18 is directly connected to the supply/discharge port 25, and the second movable cylinder 13 moves forward to act as a cushion for the rod side end of the piston 11. Next, when pressurized fluid is supplied to the rod side supply/discharge port 25, the first movable cylinder 12 has a larger area receiving back pressure, so the second movable cylinder 13 and the first movable cylinder 12 move back in this order, and each A cushioning action is performed at the head side ends of the pistons 11 and 10.

In this embodiment, cushion devices are provided on both sides of the first and second movable cylinders 12 and 13, and at the rod side end of the first movable cylinder 12 and the head side end of the second movable cylinder 13, Since the load does not stop, there is little need for cushioning action, and the cylinder is
When used in a vertical position as shown in the figure, there may be no need for the cushioning action at the rod side end of the second movable cylinder 13, and for these reasons, the cushioning device of the above-mentioned portion may be omitted. Good too.

In this example, a two-stage hydraulic cylinder was explained, but the same applies to three-stage or more, and various methods of joining the component parts can be used, such as screwing, bolting, welding, and interference fitting. techniques can be used as appropriate.

As described above, the present invention sequentially fits a plurality of movable cylinders each having a piston on the base end side into a basic cylinder, and allows air to flow in the axial direction to each piston of the movable cylinder except for the movable cylinder with the smallest diameter. A passage is provided to allow the forward side fluid chambers of each movable cylinder to communicate with each other, and an axial passage pipe and a radial passage are provided for each piston of the movable cylinders except for the movable cylinder with the smallest diameter. It is a multi-stage fluid pressure cylinder in which the backward-moving fluid chambers of the cylinder are communicated with each other, and there is a circular or annular shaped cylinder concentric with the cylinder axis in the center of the side of the piston facing the forward-moving fluid chamber. A cushion boss is formed, and a cushion hole into which the cushion boss is fitted is provided on the surface of the head cover or other piston facing the cushion boss, and when the cushion boss is fitted into the cushion hole, the forward-side fluid flows inside the cushion hole. A throttled flow path is provided that allows communication with the chamber for a small amount of flow, and the cushioning action is performed by the fluid in the cushion hole. Therefore, a multi-stage fluid pressure cylinder with a cushion that has short and compact installation dimensions can be created. Obtainable. In addition, the forward fluid chamber can be made to communicate directly with the supply/discharge port, and the axial length of the cushion boss that fits into the cushion hole is formed to be longer than the depth of the cushion hole provided in the basic cylinder. Therefore, even at the end of contraction of the movable cylinder, a gap for the forward oil chamber is always formed between the piston from which the cushion boss protrudes and the corresponding head cover, and the forward oil chamber is Since the chamber is not blocked, hydraulic pressure is applied to almost the entire area of the end face of the piston during the forward motion, resulting in the effect that the desired start-up motion is extremely good. Furthermore, since the structure of the head cover is simplified, it can be manufactured compactly, and the head cover can be removed for inspection and adjustment easily.

Further, by providing a plurality of communication holes in the axial direction in the tube of the movable cylinder having the smallest diameter near the connection portion with the piston, which communicate the inside and outside of the tube, a cushioning effect can be obtained at the time of maximum expansion.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a cushion device portion of a conventional hydraulic cylinder, and FIG. 2 is a sectional view showing an embodiment of the present invention. 9... Basic cylinder, 10, 11... Piston, 12, 13... Movable cylinder, 14, 18...
...Flow path, 15, 16...Forward side fluid chamber, 17...
...Transmission pipe, 19a, 19b, 19c... Distribution hole (flow path), 20, 21... Reciprocating side fluid chamber, 26,
28...Cushion boss, 26c, 28a... Throttle hole (throttle channel), 27, 29...Cushion hole.

Claims (1)

[Claims] 1. A plurality of movable cylinders each having a piston on the base end side are sequentially fitted into a basic cylinder,
A flow passage is provided in the axial direction in each piston of the movable cylinder except for the movable cylinder with the smallest diameter, so that the forward side fluid chambers of each movable cylinder are communicated with each other, and each piston of the movable cylinder except the movable cylinder with the smallest diameter is It is a multi-stage fluid pressure cylinder in which an axial passage pipe and a radial flow passage are provided in the cylinder to allow the reciprocating side fluid chambers of each movable cylinder to communicate with each other. A circular or annular cushion boss that is concentric with the cylinder axis is formed in the center of the cylinder axis, and a cushion hole into which the cushion boss fits is provided on the surface of the head cover or other piston opposite to the cushion boss. A constricted flow path is provided in which the inside of the cushion hole and the forward-side fluid chamber can communicate with each other by a small amount when the cushion boss is engaged with the cushion boss, and the cushioning action is performed by the fluid in the cushion hole. The axial length of the cushion boss that fits into the cushion hole is formed to be longer than the depth of the cushion hole provided in the cylinder, and there is no supply/exhaust space between the piston and the corresponding head cover at the piston's final contraction position. A multi-stage fluid pressure cylinder with a cushion, characterized in that a space for a fluid chamber on the forward side that communicates directly with a port is always formed. 2. The multi-stage body pressure cylinder with a cushion according to claim 1, wherein the tube of the movable cylinder with the smallest diameter is provided with a plurality of communication holes in the axial direction near the connection portion with the piston, which communicate the inside and outside of the tube.