KR940006235Y1 - Cushion device in hydraulic cylinder - Google Patents

Abstract

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Description

Cushion device of hydraulic cylinder

1, 2 and 3 are enlarged end front views of the main portion of the embodiment of the present invention, in which FIGS. 1 and 2 constitute a cushioning mechanism on the cylinder head side, and FIG. Fig. 2 shows the initial stage of the starting operation stroke, and Fig. 3 shows the end of the cushion stroke as a cushion mechanism is formed on the cylinder bottom side.

4, 5 and 6 show a cushioning mechanism on the cylinder head side of the prior art, FIG. 4 is a longitudinal front view, FIG. 5 is an enlarged vertical front view of the main portion of the end of the cushion stroke, and FIG. An enlarged vertical front view of the main part of the start-up stroke.

* Explanation of symbols for main parts of the drawings

2: cylinder bottom 2a: inner circumference

3: cylinder head 3a: inner circumference

4a: small diameter part 4h: piston rod

4i: end 5: piston

9a: outer circumference 9d: cutout

9g: cross section 9h: cushioning

9i: Shoulder 9j: Inner Perimeter

A: bottom side pressure chamber B: head side pressure chamber

C: cylinder bore

The present invention relates to a cushioning device of a hydraulic cylinder.

As a conventional cushion device of this kind, a small diameter portion is provided on a piston rod adjacent to the pisoton, and the cushioning slides freely into the small diameter portion. In this type of cushioning, the cushioning may be bulging due to the pressure difference between the inner and outer circumferences of the inner and outer circumference of the cushioning in the cushioning stroke, which causes the crushing and erosion. come. In order to reduce such blockiness, there are shown in FIGS. 4, 5 and 6 (Japanese Patent Application No. 63-18603).

This prior art will be described below. FIG. 4 is an overall view, FIGS. 5 and 6 are enlarged views of recesses, and FIG. 5 is a final view of the cushion stroke during operation in the left direction of the piston, and FIG. 6 is an operation in the right direction of the piston. Indicates the beginning of the start-up operation.

In Fig. 4, reference numeral 1 denotes a cylinder tube, one end of which is closed by a cylinder bottom (2), and the other end is closed by a cylinder head (3). 4 is a piston rod, and the piston 5 which slides in the cylinder tube 1 is inserted in the right end, and it is press-fixed and fixed by the stop nut 6. As shown in FIG. Moreover, the left end penetrates through the cylinder head 3 and protrudes outward. The cylinder tube 1 is partitioned into a bottom side pressure chamber A and a head side pressure chamber B by the piston 5. The bottom side pressure chamber A is connected to the outside by the port 7 and the head side pressure chamber B by the port 8, respectively. 5, the small diameter part 4b is provided in the cylinder head 3 side of the 1st end part 4a of the fston rod 4, and the small diameter part 4b of the cylinder head 3 is provided in FIG. Shaft cushion ring 9 having outer circumference 9a suitable for forming a cushion stop on inner circumference 3a and inner circumference 9b forming annular passage 10 between small diameter portion 4b. Sliding freely in the direction. Both end surfaces 9f and 9g of the cushion ring 9 are provided with cutout portions 9c and 9d for communicating the inner circumference 9b and the outer circumference 9a. The convex part 9e which slides freely fits in the small diameter part 4b of the piston rod 4 in the substantially center position of the inside 9b, and the said convex part of the small diameter part 4b of the piston rod 4 is provided. The annular groove 4c which forms a recessed part is provided in the position corresponding to 9e. The positions of the convex portion 9e and the annular groove 4c form an annular passage 11 when the cushion ring 9 is in contact with the piston 5 (see FIG. 6), and the cushion ring 9 When a) abuts against the second end 4d of the piston rod 4, the convex portion 9e is fitted into the small diameter portion 4b of the piston rod 4 to close the annular passage 10. (See Figure 5).

The following describes the operation. In the expansion stroke in which the piston moves in the left direction, the hydraulic oil is supplied from the port 7 to the bottom pressure chamber A, and the piston 5 moves in the left direction (fourth). See also). Then, when the outer circumference 9a of the cushion 9 fitted to the small diameter portion 4b to the piston rod 4 is fitted into the inner circumference 3a of the cylinder head 3, the head side pressure chamber B The oil discharge passage to the port 8 becomes a narrow passage of only the annular passage 11, the pressure in the head side pressure chamber B rises, and the cushioning 9 moves left as shown in FIG. The convex portion 9e is fitted into the small diameter portion 4b of the piston rod 4 to close the annular passage 10. For this reason, the oil discharge passage from the head side pressure chamber B to the port 8 is between the small annular pole between the inner circumference 3a of the cylinder head 3 and the outer circumference 9a of the cushion ring 9. Iii) only, and further increases the pressure in the head side pressure chamber B and cushions it. At this time, the pressure acting on the inner circumference 9b of the cushion ring 9 is inserted into the convex portion 9e of the inner circumference 9b of the cushion ring 9 by the small diameter portion 4b of the piston rod 4. The closed cylinder head 3 side does not generate pressure in the annular passage 10, which communicates with the port 8 via the annular passage 10 and the notch 9c, and has a head only on the piston 5 side. Since the pressure in the side pressure chamber B acts, the convexity of the cushion ring 9 can be made smaller than that in which the pressure acts on the entire inner circumference 9b of the cushion ring 9.

In the contraction stroke, when pressure oil is supplied from the port 8, the end face 9g of the cushion ring 9 is acted on the end face 9f on the cylinder head 3 side of the cushion ring 9 as shown in FIG. Move to the right until it comes in contact with the piston (5). Then, the projection 9e of the inner circumference 9b of the cushion ring 9 is removed from the small diameter portion 4b of the piston rod 4 and the annular passage 11 between the annular groove 4c of the piston rod 4. ) Is formed. Then, the dark oil supplied from the port 8 is sent to the head side pressure chamber B through the annular passages 10 and 11 and the notch 9d, acting on the end surface of the piston 5, and the bottom side pressure chamber. Since the oil in (A) is drained to the port 7, the piston rod 4 moves to the right.

In the prior art as described above, in the cushion stroke, the annular passage 10 formed in the inner circumference 9b of the cushion ring 9 and the small diameter portion 4b of the piston rod 4 is connected to the port 8, Since no pressure is generated in the annular passage 10, bulging due to the pressure of the cushion ring 9 can be reduced. However, in this mechanism, the small diameter portion 4b of the piston rod 4 and the convex portion 9e of the inner circumference 9b of the cushion ring 9 are caused by the axial movement of the cushion ring 9 by the reciprocating motion of the hydraulic cylinder. ) Repeats sliding, and this sliding portion wears out, and the gap between them becomes large. For this reason, oil leaks at the place other than the annular gap between the inner circumference 3a of the cylinder head 3 and the outer circumference 9a of the cushioning ring 9, which causes a problem that the performance of the cushion changes.

The present invention aims to reduce the bulging of the cushioning while forming a check valve mechanism without providing a sliding portion that may wear between the piston rod and the cushioning and cause a change in the gap. will be.

The means of the present invention for solving the above problems, a small diameter portion is provided in the piston rod adjacent to the piston, the cushioning is fitted to the small diameter portion so as to be able to flow, the outer circumference of the cushion ring is the end of operation of the piston In the present invention, when the cushion stop is formed with the inner bottom of the cylinder bottom or the cylinder head, and the cushion stop acts, the pressure chamber and the discharge side are closed between the piston rod and the cushion ring. And a cushion mechanism constituting a check valve mechanism for connecting the supply side and the pressure chamber side in the actuation stroke of the piston, wherein the check valve mechanism is provided at an end portion extending to the small diameter portion of the piston rod and at the inner circumference of the cushion ring. It consists of the shoulder part which abuts on the said edge part.

The present invention having the above means, in the end of the stroke of the cylinder, when the outer circumference of the cushion ring is fitted to the inner circumference of the cylinder bottom or cylinder head to form a cushion aperture, the discharge passage of the pressure chamber becomes narrow and the pressure of the pressure chamber Is raised to move the cushioning away from the piston, and the end of the inner circumference of the cushioning abuts the shoulder portion of the small diameter portion of the piston rod to close the annular passage formed between the two. In the operation startup stroke of the cylinder, the cushioning is pressed to the piston side by the supply of pressure oil from the port, and the end portion of the inner circumference of the cushioning is separated from the shoulder portion of the small diameter portion of the piston rod to communicate with the annular passage. As described above, the check valve mechanism of the cushion device of the present invention is composed of abutment and detachment of the end portion of the inner circumference of the cushion ring and the shoulder portion of the small diameter portion of the piston rod, so that there is no sliding portion and oil leaks due to wear. This does not happen.

An embodiment of the present invention will be described with reference to FIGS. 1, 2 and 3.

1 and 2 show a cushioning mechanism on the cylinder head side. FIG. 1 shows the end of the cushion stroke when the piston is moved to the left, and FIG. 2 shows the initial and start of the operation start stroke in the right direction of the piston. 3 shows the cushion mechanism formed on the cylinder bottom side, and shows the end of the cushion stroke. Incidentally, the same components as in the prior art will be described using the same symbols, and detailed description thereof will be omitted.

In FIG. 1, reference numeral 4h denotes a piston rod, and the small diameter portion 4b, the end portion 4i, and the middle diameter are sequentially arranged on the cylinder head 3 side of the first end portion 4a of the piston rod 4h. A part 4j is installed adjacent to each other. The small diameter portion 4b and the middle diameter portion 4i have an outer circumference 9a suitable for forming a cushion stop on the inner circumference 3a of the cylinder head 3, and the small diameter portion 4b and the middle diameter portion of the piston rod 4h. An inner circumference 9i which forms an annular passage 12 and 13 and a shoulder portion 9i which abuts against the end portion 4i between (4j) and is provided with a cushioning ring (9h) fitted to be movable in the axial direction. A cutout portion 9d for communicating the end face 9g on the piston 5 side of the cushion ring 9h with the outer circumference 9a is provided. In this embodiment, since the difference between the outer diameter of the cylinder inner diameter c and the piston rod 4h is small and the space for installing the cushion mechanism is small, the middle diameter portion 4j is provided on the piston rod 4h. The middle neck portion 4j may not be provided, and the effect thereof does not change.

The following operation is described. In the expansion stroke, the piston 5 supplied with the pressure oil from the port 7 to the bottom side pressure chamber A moves to the left and is cushioned in such a way that it is fluidly fitted to the small diameter portion 4b of the piston rod 4h. When the outer circumference 9a of the 9h is fitted into the inner circumference 3a of the cylinder head 3, the oil from the head side pressure chamber B to the port 8 flows out of the piston rod 4h. It becomes a narrow passage only for the annular passages 12 and 13 between the neck portion 4b, the middle neck portion 4j and the inner circumference 9j of the cushion ring 9h, and the pressure in the head side pressure chamber B rises to As shown in FIG. 1, the cushioning 9h moves to the left side, the shoulder portion 9j of the inner circumference 9j comes into contact with the end portion 4i of the small diameter portion 4b of the piston rod 4h, and the annular passage 12 ) And the annular passage 13 are closed. For this reason, the oil discharge passage from the head side pressure chamber B to the port 8 becomes only a small annular gap between the inner circumference 3a of the cylinder head 3 and the outer circumference 9a of the cushion ring 9h. The pressure in the head side pressure chamber B is further raised to cushion. At this time, since the annular passage 13 between the cylinder rod 9h and the middle diameter portion 4j passes through the port 8, the pressure acting on the cushion ring 9h is applied to the annular passage 913. Since the pressure of the head side pressure chamber B acts only on the annular passage 12 between the small-diameter portion 4b, the pressure acts on the entire inner circumference 9j of the cushion ring 9h. You can less bulge than.

In the contraction stroke, when the pressure oil is supplied from the port 8, it acts on the end face 9f of the cylinder head 3 side of the cushioning 9h to make the cushioning 9h end face 9g as shown in FIG. ) Moves to the right until it comes into contact with the piston (5). Then, the shoulder portion 9j of the inner circumference 9j of the cushion ring 9h is separated from the end portion 4i of the small diameter portion 4b of the piston rod 4h, and the annular passage 12 and the annular passage 13 To communicate. Then, the pressurized oil supplied from the port 8 is sent to the head side pressure chamber B via the annular passages 12 and 13 and the notch 9d, acting on the end surface of the piston 5, and the bottom side pressure Since the oil of the seal A is discharged to the port 7, the piston rod 4h moves to the right.

As described above, the configuration of the cushion mechanism on the cylinder head side has been described with reference to FIGS. 1 and 2, but the configuration and operation of FIG. 3 showing that the cushion mechanism is defined on the cylinder bottom side are completely the same. The same components as those in FIG. 2 are denoted by the same reference numerals, and detailed description thereof will be omitted.

The present invention forms a check valve mechanism by contacting and detachment between the shoulder portion of the small diameter portion of the piston rod and the end of the inner circumference of the cushion ring, and the bulging of the cushion ring is caused by applying hydraulic pressure only to the pressure chamber side of the check mechanism. At the same time, the cushion performance does not change since the oil leakage due to wear does not occur between the two sides. Moreover, since it is set as the shoulder part and the end part without providing a sliding part and an uneven part, processing is easy.

Claims (1)

A small diameter part is provided in the piston rod adjacent to the piston, and the cushioning ring is inserted into the small diameter part so that the outer periphery of the cushion ring is at the end of the operation of the piston. And at the same time, when the cushion iris is acted on, the pressure chamber side and the discharge side are closed between the piston rod and the cushion ring, and the feed side and pressure chamber side are connected in the actuation stroke of the piston. In the cushion mechanism constituting the valve mechanism, the check valve mechanism is configured with an end portion extending to the small diameter portion of the piston rod, and a shoulder portion provided on the inner circumference of the cushion ring and against the end portion. Cushion device.