JPH07133866A - Cylinder device - Google Patents

Abstract

PURPOSE:To extend the lifetime of a seal member or the like by preventing dust or the like from entering space between a piston and a piston tube. CONSTITUTION:The external surface of a piston 31 is provided with a pair of ring grooves 34 and 34 open to the rod side edge 31A and the bottom side edge 31B thereof. A bearing 35 is coupled to each groove 34 and positioned so that one edge of each bearing 35 is aligned with the same plane as the edge 31A or 31B. According to this construction, dust can be prevented from entering space between the piston 31 and the tube 1 thereof. Furthermore, the projection 35A of each bearing ring 35 is coupled to the annular recess 34A of each groove 34, thereby retaining each ring 35 in the groove 34 in locked state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylinder device provided in a construction machine such as a hydraulic excavator and suitable for operating a working device.

[0002]

2. Description of the Related Art A hydraulic cylinder is taken as an example of a cylinder device according to the prior art and will be described with reference to FIGS.

In the drawing, reference numeral 1 denotes a tube forming the outer shape of a hydraulic cylinder, one end side of which is closed by a bottom cover 2, and a mounting eye 2A is integrally formed on the bottom cover 2. Further, the tube 1 is provided with supply / discharge ports 3 and 4 which are located on both axial ends of the tube 1 and which supply and discharge pressure oil to and from oil chambers A and B, respectively, which will be described later.

Reference numeral 5 denotes a rod guide provided on the other end side of the tube 1, and the rod guide 5 is a rod 10 described later.
Is slidably supported.

6 is slidably fitted in the tube 1,
2 shows a piston in which the inside of the tube 1 is divided into two oil chambers A and B, and the piston 6 is formed in a short cylindrical shape with an outer diameter slightly smaller than the inner diameter of the tube 1, and its end faces on both axial ends Are end faces 6A on the rod side and end faces 6B on the bottom side, respectively. A fitting insertion hole 7 into which a small-diameter portion 10A of a rod 10 described later is fitted is formed in the piston 6 so as to penetrate therethrough in the axial direction.

Further, on the outer peripheral surface of the piston 6, there is formed an annular seal groove 8 which is located at an intermediate portion in the axial direction and into which an O-ring 13 and a seal ring 14, which will be described later, are inserted, is formed all around. At the same time, ring grooves 9 and 9 into which bearing rings 15 to be described later are fitted are formed over the entire circumference at positions axially separated from the seal groove 8.

Reference numeral 10 denotes a rod having one end entering the tube 1 and the other end protruding outside the tube 1 through a rod guide 5, and one end of the rod 10 is fitted into a fitting insertion hole 7 of a piston 6. The small-diameter portion 10A is inserted, and a mounting eye 10B is integrally formed on the protruding end on the other end side. Also,
A threaded portion 11 is formed on the tip side of the small diameter portion 10A,
A nut 12 for fixing the rod 10 to the piston 6 is fastened to the screw portion 11.

Reference numeral 13 is an O-ring made of an elastic material inserted into the seal groove 8 of the piston 6, and 14 is the O-ring 13.
A seal ring as a seal member, which is located on the outer peripheral side of and is mounted in the seal groove 8, is shown. The seal ring 14 is formed in a ring shape from a synthetic resin material such as fluororesin. The inner circumference of the seal ring 14 is O
The ring 13 is elastically supported, and the outer peripheral side thereof projects radially from the seal groove 8 and is in sliding contact with the inner peripheral surface of the tube 1. As a result, the seal ring 14 liquid-tightly seals between the piston 6 and the tube 1 and prevents the oil liquid from leaking between the oil chambers A and B.

Reference numerals 15 and 15 denote bearing rings fitted in the ring grooves 9 of the piston 6, and the bearing rings 15 are made of a synthetic resin material such as fluororesin or a self-lubricating material such as carbon and have a square cross section. It is formed in a shape, and the outer peripheral side thereof projects radially from each ring groove 9 and is in sliding contact with the inner peripheral surface of the tube 1. The bearing rings 15 prevent the piston 6 from being displaced in the radial direction within the tube 1, and as shown in FIG.
A predetermined gap S is provided over the entire circumference between the inner peripheral surface and the inner peripheral surface.

The hydraulic cylinder according to the prior art has the above-described structure. For example, when pressure oil from a hydraulic pump (not shown) is supplied into the oil chamber A through the supply / discharge port 3, the oil chamber Since the pressure inside A is higher than that inside the oil chamber B, the piston 6 is pushed toward the oil chamber B, and the rod 10 is contracted into the tube 1. Further, when pressure oil is supplied from the supply / discharge port 4 into the oil chamber B, the piston 6 is pushed toward the oil chamber A side by the pressure oil in the oil chamber B, so that the rod 10 largely protrudes from the tube 1. Extend to.

[0011]

By the way, in the above-mentioned prior art, the gap S is provided over the entire circumference between the outer peripheral surface of the piston 6 and the inner peripheral surface of the tube 1. Since S communicates with the oil chambers A and B on the rod-side end surface 6A side and the bottom-side end surface 6B side of the piston 6, respectively, the following problems occur.

That is, when dust or the like enters the pressure oil supplied to or discharged from the oil chambers A and B, the dust or the like enters the gap S, and if the dust is injected into the gap S for a long period of use, the dust will enter the gap S. Etc. will be accumulated. When the expansion and contraction operation of the rod 10 is repeated in such a state, the inner peripheral surface of the tube 1 may be damaged by this dust, which damages the seal ring 14 and the oil chambers A and B. There is a problem that the pressure oil leaks.

Further, the dust accumulated in the gap S may be released as a large lump into the oil chamber A or B,
This lump of dust penetrates into the supply / discharge ports 3 and 4 and the pipes connected to them, which causes clogging of the pipes, etc.
There are problems that the operation of the hydraulic cylinder is hindered and other hydraulic equipment is damaged.

The present invention has been made in view of the above-mentioned problems of the prior art, and provides a cylinder device capable of preventing dust and the like from entering between the piston and the tube and improving the life of the seal member and the like. It is intended to be provided.

[0015]

In order to solve the above-mentioned problems, the cylinder device of the present invention has a tube and a tube slidably fitted therein, and the inside of the tube is divided into two chambers. The piston and one end side are fixed to the piston,
The other end of the rod protrudes outside the tube, and a seal member is provided on the outer peripheral side of the piston and seals between the piston and the tube.

The features of the configuration adopted by the present invention are as follows:
On the outer peripheral side of the piston, a pair of ring grooves are formed apart from each other in the axial direction of the piston and open to both end side end faces of the piston, and the ring grooves are fitted so as to fill the respective ring grooves. The bearing rings are provided so as to prevent the pistons from being displaced radially in the tube.

Further, it is preferable that each of the ring grooves and each of the bearing rings be provided with an engaging portion for engaging with each other so that each of the bearing rings is retained in the ring groove in a state of being prevented from being pulled out.

[0018]

With the above construction, the end faces of the bearing rings can be arranged substantially flush with the end faces of both ends of the piston, and the gap formed between the piston and the tube by each bearing ring forms a chamber in the tube. Can be prevented from communicating with.

Further, by providing the respective bearing rings and the respective ring grooves with engaging portions which engage with each other, the respective bearing rings are positioned from the respective ring grooves of the piston as the piston slides in the tube. It can be surely prevented from slipping off or falling off.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS. In the embodiment, the same components as those of the prior art shown in FIGS. 6 and 7 described above are designated by the same reference numerals, and the description thereof will be omitted.

First, FIG. 1 shows a first embodiment of the present invention.

In the figure, reference numeral 21 designates a piston slidably fitted in the tube 1. The piston 21 is formed into a cylindrical shape substantially like the piston 6 described in the prior art, and its end faces on both end sides are formed. It has a rod-side end surface 21A and a bottom-side end surface 21B. A fitting insertion hole 22 is formed so as to penetrate through the piston 21 in the axial direction, and a seal groove 23 and a pair of ring grooves 24, 24 are formed on the outer peripheral surface.

However, in the piston 21 according to the present embodiment, one ring groove 24 is formed on the outer peripheral surface of the piston 21 so as to open to the rod side end surface 21A, and the other ring groove 24 opens to the bottom side end surface 21B. Thus, it is formed on the outer peripheral surface of the piston 21 over the entire circumference.

25 and 25 are ring grooves 2 of the piston 21.
4 shows a pair of bearing rings provided in FIG. 4, each bearing ring 25 is formed in substantially the same manner as each bearing ring 15 described in the prior art, but its axial dimension d is the axis of each ring groove 24. It is formed to have the same dimension as the direction. Then, each bearing ring 25 is fitted into each ring groove 24 so that the end surface thereof is located on the same plane as the rod-side end surface 21A or the bottom-side end surface 21B of the piston 21, and fills each ring groove 24. It has become. Further, each bearing ring 25 is fixed to each ring groove 24 with an adhesive or the like in a retaining state.

The bearing rings 25 prevent the piston 21 from being displaced in the radial direction within the tube 1, and as shown in the figure, the bearing ring 25 is provided between the outer peripheral surface of the piston 21 and the inner peripheral surface of the tube 1. A predetermined gap S is provided along the circumference.

The hydraulic cylinder according to this embodiment has the structure as described above, and its basic operation is not different from that of the prior art.

In this embodiment, however, a pair of ring grooves 2 are formed on the outer peripheral surface of the piston 21 and are axially spaced apart from each other and open at the rod-side end surface 21A and the bottom-side end surface 21B, respectively.
4 and 24 are formed in the ring grooves 24, and the end faces of the bearing rings 25 are the rod-side end faces 21 of the pistons 21.
The piston 21 and the tube 1 are configured to be fitted so as to be flush with the end surface 21B on the A side or the bottom side.
The gap S interposed between and does not communicate with the oil chambers A and B on the rod-side end surface 21A side and the bottom-side end surface 21B side of the piston 21.

Therefore, foreign matter such as dust can be surely prevented from entering the gap S, and the foreign matter is surely prevented from damaging the inner peripheral surface of the tube 1 and impairing the sealability of the seal ring 14. It can be prevented. As a result, it is possible to reliably prevent the pressure oil from leaking between the oil chambers A and B, and improve the performance and reliability of the hydraulic cylinder.
The life of the seal ring 14 and the like can be greatly extended.

Further, since no dust or the like is accumulated in the gap S, the accumulated dust is discharged into the oil chambers A and B as a large lump as in the prior art, and this lump of dust is piped. It is possible to prevent the occurrence of clogging and the like, and it is possible to solve problems such as hindering the operation of the hydraulic cylinder and damaging other hydraulic equipment.

Next, FIG. 2 shows a second embodiment of the present invention. The feature of this embodiment is that each ring groove and each bearing ring of the piston are provided with engaging portions for engaging each other, and each bearing is The structure is such that the ring is held in the ring groove in a retained state.

In the figure, reference numeral 31 denotes a piston slidably fitted in the tube 1. The piston 31 has substantially the same axial end faces as the piston 21 described in the first embodiment. The rod-side end surface 31A and the bottom-side end surface 31B are formed into a substantially columnar shape having a fitting insertion hole 32, a seal groove 33, and a pair of ring grooves 34 and 34 respectively opening to the rod-side end surface 31A and the bottom-side end surface 31B. Has been done. However, each ring groove 3 of the piston 31
An annular recess 34 </ b> A is formed at position 4 in the middle in the axial direction.

35, 35 are the ring grooves 3 of the piston 31.
4 shows a pair of bearing rings, each bearing ring 35 having an axial dimension d that is substantially the same as each bearing ring 25 described in the first embodiment. The bearing rings 35 are formed to be the same, and one end face of each bearing ring 35 is a rod-side end face 31A or a bottom-side end face 31B.
It is arranged so as to be located on the same plane as.

However, on the inner peripheral side of each bearing ring 35, a ridge portion 35A which is located in the middle in the axial direction and projects radially inward is formed annularly over the entire circumference. Then, each of the projecting ridges 35A corresponds to each of the ring grooves 3 of the piston 31.
4 to form an engaging portion together with the annular recess 34A formed in
Each of the protrusions 35A engages with the annular recess 34A of the ring groove 34, so that each bearing ring 35 is attached to the ring groove 34A.
It is held in the state that it does not come off.

Thus, even in this embodiment having such a structure, the same effect as that of the first embodiment can be obtained, but particularly in this embodiment, it is formed in each ring groove 34 of the piston 31. Since the protruding portion 35A of each bearing ring 35 is engaged with the annular recess 34A,
Each bearing ring 35 can be fixed in each ring groove 34 in a retaining state, and each bearing ring 35 can be expanded and contracted as the rod 10 expands and contracts.
Even if frictionally contacts the inner peripheral surface of the tube 1, it is possible to reliably prevent the bearing rings 35 from being displaced from the ring grooves 34 and dropping out.

Next, FIG. 3 shows a third embodiment of the present invention. The feature of this embodiment is that each ring groove of the piston is formed with an annular ridge protruding outward in the radial direction. An annular recess that engages with the protrusion is formed on the inner peripheral side of each bearing ring, and the protrusion of each bearing ring is fitted into the annular recess of each ring groove, so that each bearing ring is It is held in the ring groove in a state where it is not pulled out.

In the figure, reference numeral 41 designates a piston slidably provided in the tube 1. The piston 41 is formed in substantially the same manner as the piston 21 described in the first embodiment, and both end faces in the axial direction are formed. The rod-side end surface 41A and the bottom-side end surface 41B respectively become a fitting insertion hole 42, a seal groove 43,
It has a pair of ring grooves 44, 44. However, in each ring groove 44 of the piston 41, a ridge 44A is formed in an annular shape over the entire circumference at an axially intermediate position.

45 and 45 are ring grooves 4 of the piston 41.
4 shows a pair of bearing rings provided in FIG. 4, each bearing ring 45 being formed in substantially the same manner as each bearing ring 25 described in the first embodiment, but on the inner peripheral side of each bearing ring 45. Has an annular recess 45A formed at an intermediate position in the axial direction.

Here, the annular recess 4 of each of the bearing rings 45.
5A constitutes an engaging portion together with the protruding portion 44A of each ring groove 44. The annular recess 45A of each bearing ring 45 and the protruding portion 44A of each ring groove 44 are engaged with each other to hold each bearing ring 45 in the ring groove 44 in a retaining state.

Thus, also in this embodiment having the above-mentioned structure, it is possible to obtain the same effects as those of the above-mentioned embodiments.

Next, FIG. 4 shows a fourth embodiment of the present invention. The feature of this embodiment is that each ring groove of the piston is formed with an annular taper concave portion inclined in a V-shaped cross section, and An annular taper protrusion that engages with the taper recess is formed on the inner peripheral side of the bearing ring.

In the figure, reference numeral 51 designates a piston slidably provided in the tube 1. The piston 51 is formed in substantially the same manner as the piston 21 described in the first embodiment, and its both axial end faces are formed. The end face 51A on the rod side and the end face 51B on the bottom side are respectively formed, and the fitting insertion hole 52, the seal groove 53,
It has a pair of ring grooves 54, 54. However, in each ring groove 54 of the piston 51, a tapered recess 54A having a V-shaped cross section that is inclined toward the axially intermediate portion of each ring groove 54 is annularly formed over the entire circumference of the piston 51. Has been formed.

55, 55 are the ring grooves 5 of the piston 51.
4 shows a pair of bearing rings, each bearing ring 55 being formed in substantially the same manner as each bearing ring 25 described in the first embodiment, but on the inner peripheral side of each bearing ring 55. Is formed with a mountain-shaped tapered projection 55A having a cross section that is tapered from both axial ends of each bearing ring 55 to an intermediate portion. Then, each bearing ring 5
The inner diameter of 5 has a minimum diameter in the axial middle portion.

Here, the taper protrusion 55A of each bearing ring 55 constitutes an engaging portion together with the taper recess 54A of each ring groove 54. The tapered projection 55A of each bearing ring 55 and the tapered recess 54A of each ring groove 54 are engaged with each other to hold each bearing ring 55 in the ring groove 54 in a state where it is not pulled out.

Thus, also in this embodiment having the above-mentioned structure, it is possible to obtain the same operational effects as those of the above-mentioned respective embodiments.

Next, FIG. 5 shows a fifth embodiment of the present invention. The feature of this embodiment is that each ring groove of the piston is formed as a bent groove whose bottom surface protrudes radially outward in a mountain shape. At the same time, the annular tapered recesses that engage with the ring grooves are formed on the inner peripheral side of each bearing ring.

In the figure, reference numeral 61 denotes a piston slidably provided in the tube 1. The piston 61 is formed in substantially the same manner as the piston 21 described in the first embodiment, and the end faces on both axial sides are formed. The rod-side end surface 61A and the bottom-side end surface 61B respectively become a fitting insertion hole 62, a seal groove 63,
It has a pair of ring grooves 64, 64. However, in each ring groove 64 of the piston 61, a mountain-shaped taper projection 64A is formed on the bottom surface of each ring groove 64 so as to bulge from both ends in the axial direction to the intermediate portion, and is annularly formed over the entire circumference. Has been done.

Reference numerals 65 and 65 denote the ring grooves 6 of the piston 61.
4 shows a pair of bearing rings provided in No. 4, and each bearing ring 65 is formed in substantially the same manner as each bearing ring 25 described in the first embodiment, but the inner peripheral side of each bearing ring 65 is The diameter of the bearing ring 65 is expanded outward toward the intermediate portion in the axial direction to form a tapered recess 65A having a V-shaped cross section.

Here, the tapered recessed portion 65A of each bearing ring 65 constitutes an engaging portion together with the tapered protrusion 64A of each ring groove 64. The tapered recesses 65A of the bearing rings 65 and the tapered protrusions 64A of the ring grooves 64 are engaged with each other to hold the bearing rings 65 in the ring grooves 64 in a retaining state.

Thus, also in this embodiment having the above-mentioned structure, it is possible to obtain the same effects as those of the above-mentioned embodiments.

In the second embodiment, the piston 3
Although a single annular recess 34A is formed in each ring groove 34 of No. 1 and a single ridge 35A is formed in each bearing ring 35, the present invention is not limited to this, and a plurality of ring grooves of the piston are provided. The annular recesses may be formed continuously in the axial direction, and a plurality of ridges corresponding to the annular recesses may be formed in each bearing ring. This point may be the same as in the third embodiment.

In the fourth embodiment, the piston 5
Although the tapered recess 54A is formed in each ring groove 54 of No. 1 and the inner peripheral surface of each bearing ring 55 is formed as the tapered protrusion 55A that engages with the tapered recess 54A, the present invention is not limited to this. A plurality of tapered recesses may be continuously formed in the groove in the axial direction, and a plurality of tapered protrusions corresponding to the tapered recesses may be formed on the inner peripheral surface of each bearing ring.

Further, in the above-mentioned embodiment, the hydraulic cylinder is described as an example of the cylinder device, but it may be applied to other cylinder devices such as a pneumatic cylinder device instead.

[0053]

As described in detail above, according to the present invention, a pair of ring grooves are formed on the outer peripheral side of the piston, which are spaced apart in the axial direction of the piston and open to both end side end faces of the piston. Since each ring groove is provided with a bearing ring that is fitted so as to fill the ring groove and restricts the piston from being displaced in the radial direction in the tube, the end faces of each bearing ring are connected to both ends of the piston. It can be arranged substantially flush with the side end faces. As a result, it is possible to reliably prevent dust and the like from entering between the piston and the tube, and it is possible to prevent the dust from damaging the inner peripheral surface of the tube and damaging the seal member. Therefore, the life of the seal member can be significantly extended, and the durability and reliability of the cylinder device can be improved.

Further, since each ring groove and each bearing ring are provided with engaging portions to be engaged with each other, each bearing ring can be retained in the ring groove in a retained state, and the piston in the tube can be retained. It is possible to reliably prevent the bearing rings from being displaced and falling out of the ring grooves of the piston due to the sliding.

[Brief description of drawings]

FIG. 1 is an enlarged vertical cross-sectional view of essential parts showing a piston, a bearing ring, and the like of a hydraulic cylinder according to a first embodiment of the present invention.

FIG. 2 is a sectional view similar to FIG. 1, showing a piston, a bearing ring and the like of a hydraulic cylinder according to a second embodiment of the present invention.

FIG. 3 is a sectional view similar to FIG. 1, showing a piston, a bearing ring, and the like of a hydraulic cylinder according to a third embodiment of the present invention.

FIG. 4 is a sectional view similar to FIG. 1, showing a piston, a bearing ring and the like of a hydraulic cylinder according to a fourth embodiment of the present invention.

5 is a sectional view similar to FIG. 1, showing a piston, a bearing ring and the like of a hydraulic cylinder according to a fifth embodiment of the present invention.

FIG. 6 is a vertical sectional view showing a hydraulic cylinder according to the related art.

FIG. 7 is an enlarged cross-sectional view of essential parts such as a piston and a bearing ring in FIG.

[Explanation of symbols]

 1 tube 10 rod 14 seal ring (seal member) 21, 31, 41, 51, 61 piston 24, 34, 44, 54, 64 ring groove 25, 35, 45, 55, 65 bearing ring 34A, 45A annular recess (engagement) Mating part) 35A, 44A Projection ridge (engagement part) 54A, 65A Tapered recess (engagement part) 55A, 64A Tapered projection (engagement part)

Claims (2)

[Claims] 1. A tube, a piston slidably inserted into the tube, and defining the inside of the tube into two chambers, one end side fixed to the piston, and the other end side protruding outside the tube. In the cylinder device including a rod and a seal member that is provided on the outer peripheral side of the piston and seals between the piston and the tube, the outer peripheral side of the piston is separated in the axial direction of the piston, A pair of ring grooves that open at both end sides of the piston are formed, and the ring grooves are fitted into the ring grooves so as to fill the ring grooves, and the piston is prevented from being displaced in the radial direction in the tube. Cylinder device characterized in that each bearing ring is provided. 2. The ring groove and the bearing ring,
The cylinder device according to claim 1, wherein an engaging portion that engages with each other is provided, and each of the bearing rings is held in a ring groove in a state where the bearing ring is not pulled out.