JPH0439405A - Piston structure for reciprocating device - Google Patents

Abstract

PURPOSE:To attach each part at a precise position and to simplify part replac ing work by providing a threaded part and a positioning projection at the piston mounting position of a rod, and threadably attaching packing holding and press ing members to the thread part to have divided the piston at positions where their opposite faces are mutually butted for their positioning. CONSTITUTION:The outer periphery of a rod 2 is provided with a positioning projection 21 and a threaded part 22, and the first piston member 31 to hold a packing 4 to have divided a piston 3 and the second piston member 32 to press the packing 4 are threadably attached with their opposite faces butted to each other. Thus the attaching position of the piston 3 to the rod 2 can be precisely kept to simplify replacing work for the packing 4 or the like and to make stroke dead pace smaller.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application of M Soil Collection) The present invention relates to a piston structure of a reciprocating device used in a hydraulic mechanism or the like.

(Prior art) Conventionally, this type of piston structure has been used, for example, in
As shown in Japanese Patent No. 83 and as shown in FIG. 3, a small diameter shaft part (B) is provided at the mounting position of the piston (C) on the rod (A) via a positioning step part (a). At the same time, a wide rubber ring packing (E) that is in sliding contact with the inner wall of the cylinder (D) is held on the outer periphery of the piston (C), and the piston member (C) is attached to the rod (
A) is inserted onto the small diameter shaft part (B) so as to be in contact with the positioning step part (a), and a locking nut is attached to the outside of the small diameter shaft part (B) (F). By screwing the piston member (C), the piston member (C) is fixedly held at the position of the rod (A) with the gasket (E) interposed therebetween.

(Claim B to be solved by the invention) However, in the above piston structure, the piston member (C
) in the positioning position, the nut (F) is screwed onto the small diameter shaft (B) of the rod (A). This caused a problem in that the stroke dead space of the cylinder (D) became large and the length of the cylinder (D) in the MI direction became long.

The present invention was made in view of the above-mentioned problems, and its purpose is to accurately maintain the mounting position of the piston relative to the rod, and to easily replace parts such as the ring seal. It is an object of the present invention to provide a piston structure in a reciprocating device that can reduce the stroke dead space of a cylinder and shorten the axial length of the cylinder.

(Means for Solving the Problem) In order to achieve the above object, the present invention provides a rod (2).
and a piston (3) having a ring packing (4) attached to the rod (2) and reciprocating in sliding contact with the inner wall of the cylinder (1). A first piston member (31) for holding the gasket (4) on the threaded portion (22) by providing a threaded portion (22) and a positioning protrusion (21) at the mounting position of 3); 2nd to hold down the patch (3)
The piston member (32) is connected to each of these members (31) (3
2) is characterized in that the opposing surfaces are brought into contact with each other and screwed at the positioning position.

Further, the first piston member (31) that holds the ring packing (4) is provided with a centering portion (23) having an inner circumferential surface that fits and centers the outer circumferential surface of the rod (2). This is desirable.

(Function) The first piston member (31) that holds the piston (3) and the gasket (4), and the gasket.

and a second piston member (32) that presses the pin (3), one of these piston members (31)'' (32) is attached to the threaded portion (22) of the rod (2), and the positioning protrusion ( 21) until it comes into contact with the threaded portion (
22) Screw into the outer side of the one piston member above so that the opposing surfaces of these members (31) and (32) abut each other, and Tighten in the opposite direction (screwing direction), and each of the above members (31)
(32) By generating a reverse torque between the members (31) and (32), a loosening prevention function is exerted, and the positional deviation of each member (31) and (32) with respect to the rod (2) is prevented. 31) The double nut tightening action of (32) can fix the rod (2) in a predetermined position, and each of the members (31) and (32), that is, the piston (3),
Precisely held in place on said rod (2). Moreover, compared to the case of using a conventional locking nut, the stroke dead space of the cylinder (1) can be eliminated, the axial length of the cylinder (1) can be shortened, and further,
The first and second piston members (32) are connected to the rod (2).
By pulling it out, the gasket (4) can be easily replaced.

Further, when the first piston member (31) holding the ring packing (4) is provided with a centering portion (23) having an inner circumferential surface that fits and centers the outer circumferential surface of the rod (2), , the rod (2) of the first piston member (31)
The centering of the packing (4) can be easily performed, and the sliding contact of the packing (4) with the inner wall of the 7th ring can be performed more accurately.

(Example) The reciprocating device shown in FIG.
1) A piston structure is provided inside the 7 cylinder (1) provided with (11), and this piston structure includes rods (2) that protrude outward from both sides of each lid (11). ,
It consists of a piston (3) installed at an intermediate position in the axial direction of the rod (2), and a rubber ring packing (4) with a corrugated cross section on the outer circumferential surface of the piston (3).
is disposed, and the packing (4) is reciprocated while slidingly contacting the inner wall surface of the seven cylinders (1).

Furthermore, fluid passages (12) and (13) are provided at both sides of the outer peripheral wall of the cylinder (1), and the ring of the piston (3) is provided through the fluid passages (12 and 13). The piston (3) is reciprocated by introducing and discharging pressure fluid into pressure chambers on both sides of the cylinder (1) defined by the packing (4).

However, in the above piston structure, the rod (
A circular positioning protrusion (21) protruding radially outward is integrally formed at the axial center position on the outer circumferential surface of the rod (2).
) is provided with a threaded portion (22) over a predetermined length on the negative side of the piston (3), while the piston (3) is
A first piston member (31) that holds the bar and a second piston member (32) that presses the bar socket (4) are formed separately, and on the inner circumferential surface of each of these members (31) and (32), Internal threads 31a) each threadedly engaged with the threaded portion (22).
(32a) is formed.

A plurality of rotation operation holes (33) (34) are formed on the side surfaces of each of the piston members (31) and (32), respectively, and each of the piston members ( 31) and (32), synthetic resin backup seal rings (6) and (5) are interposed.

Then, the second piston member (32) is connected to the rod (
2) one end of the second piston member (32) is inserted into the threaded portion (22) from the outside, and is inserted into the second piston member (32) through the operation hole (34).
By rotating the piston member (32), the internal thread (32a) of the piston member (32) is threaded along the threaded portion (22) and lightly abuts on the positioning protrusion (21). With the gasket (4) held on the outer periphery of the first piston member (31) and the seal rings (5) (5) held on both sides of the gasket (4), the first
The piston member (31) is rotated through the operation hole (33), and the inner thread 31 of the piston member (31) is rotated.
a) along the threaded portion (22), the second piston member (3) is threaded onto the threaded portion (22).
2), the first piston member (31) is inserted into the side surface of the second piston member (32) so that the opposing surfaces of these members (31) and (32) abut each other. is tightened in the opposite direction (screwing direction) through the operation hole (34) to generate a reverse torque between the respective members (31) and (32), and this reverse torque causes the respective members ( 3
1) (32) can be fixed to the rod (2) with a locking function, in other words, each of the members (31) (3
2) can be fixed to the rod (2) by the double NAND tightening action, and each member (31) (32), that is, the piston (3) is accurately held at a predetermined mounting position of the rod (2). Incidentally, by tightening the second piston member (32) in the opposite direction, a slight gap will be created between the positioning protrusion (21) and the second piston member (32). This allows the second piston member (32) to be held at the anticipated and accurate position.

As mentioned above, each of the members (3) from the rod (2)
1) In order to prevent the cylinder (32) from falling out, the cylinder (
The stroke dead space of 1) can be eliminated, and the axial length of this cylinder (1) can be shortened. Further, when replacing the packing (4), each seal ring (5), etc., it can be easily done by pulling out the first piston member (31) from the rod (2). Furthermore,
Due to the pressing action of the first piston member (31) on the second piston member (32), each of the seal rings (5
), the gasket (4) is elastically deformed into a rod that bulges outward in the radial direction, and the gasket (4) and the cylinder (1
) to ensure a good seal between the

Further, the first piston member (31) is provided with a centering portion (23) for centering the piston member (31) with respect to the rod (2). That is, on the inner peripheral surface of the first piston member (31), on the axially inward side,
the internal screw (31a) that is screwed into the threaded portion (23);
, and the internal thread (
A centering portion (23) having an inner circumferential surface that comes into contact with the outer circumferential surface of the rod (2) outside the threaded portion (22) is provided on the axially outer side of the rod (31a).

The threaded portion (
22), by bringing the centering portion (23) into sliding contact with the outer peripheral surface of the rod (2), centering of the first piston member (31) with respect to the rod (2) can be easily performed. As a result, the packing (4) can more accurately slide into contact with the inner wall of the cylinder. Furthermore, the second
Centering of the piston member (32) can be performed by the outer peripheral surface of the projection (21) provided on the rod (2).

Furthermore, in the present invention, as shown in FIG. 2, it is also possible to provide two sets of the aforementioned pistons (3) on the rod (2). That is, a wide positioning protrusion (21) is formed protrudingly from the center of the piston mounting position of the rod (2), and a seal ring (61) is provided on the outer peripheral part of the positioning protrusion (21). A support member (6) is inserted and threaded portions (22) (22) similar to those described above are attached to the outer peripheral surface of the rod (2) on both sides of the support member (6) in the axial direction.
are provided, respectively, and the pair of first piston members (31) are screwed into each threaded portion (22) to strongly press against both sides of the positioning protrusion (21), and then the pair of second The piston member (32) is screwed into each of the threaded portions (22) so as to strongly abut against the -side surface of the first piston member (31), and each of these members (31) and (32) is inserted into the rod (2).
). Further, U-shaped ring packings (4) (4) that slide into contact with the inner wall of the cylinder (1) may be inserted into the outer peripheral side of each of the first piston members (31).

Further, in the above embodiment, a double rod type in which both sides of the rod (2) in the axial direction protrude from both sides of the cylinder (1) has been described, but in the present invention, the − side of the cylinder (1) is It is also possible to apply the present invention to a single rod type in which one end of the rod (2) protrudes from.

(Effects of the Invention) As explained above, in the piston structure of the present invention, the threaded portion (22) and the positioning protrusion (21) are provided at the mounting position of the piston (3) on the rod (2), and the A first piston member (31) that holds the ring seal (4) and a second piston member (32) that presses the seal (4) are attached to the threaded portion (22).
Since the facing surfaces of the piston (32) are brought into contact with each other and screwed into the position, it is possible to accurately maintain the mounting position of the piston (3) with respect to the rod (2), and it is also possible to replace parts such as the gasket (4). It is easy to do, and the stroke dead space of cylinder (1) can be reduced.
This made it possible to shorten the axial length of the cylinder (1).

Further, a centering portion (23) having an inner circumferential surface that fits and centers the outer circumferential surface of the rod (2) is provided on the first piston member (3 pieces) that holds the ring packing (4). By this, the rod (2) of the first piston member (31)
) can be easily and reliably centered, and the packing (4) can be accurately brought into sliding contact with the cylinder (1).

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a reciprocating device to which the piston structure of the present invention is applied, FIG. 2 is a sectional view showing another embodiment, and FIG. 3 is a sectional view showing a conventional example. (1)・φ・・Cylinder (2)＠＠・Rod (21)・φ・Kist protrusion (22)−・Threaded portion (23)−・Centering portion (3)・... φ piston (31), φ 9 first piston member (32), φ 2nd piston member (4) ... ring packing

Claims (1)

[Claims] 1) Consists of a rod (2) and a piston (3) that is attached to the rod (2) and has a ring packing (4) that reciprocates in sliding contact with the inner wall of the cylinder (1). The piston structure is such that a threaded portion (22) and a positioning protrusion (21) are provided at a mounting position of the piston (3) on the rod (2), and the packing (4) is provided on the threaded portion (22). ), a first piston member (31) holding the packing (
4) A piston structure in a reciprocating device, characterized in that a second piston member (32) that presses the piston is screwed into a positioning position with opposing surfaces of these members (31) and (32) abutting each other. 2) The first piston member (31) holding the ring packing (4) is provided with a centering portion (23) having an inner circumferential surface that fits and centers the outer circumferential surface of the rod (2). Item 1
Piston structure in the reciprocating device described.