WO1998029665A1

WO1998029665A1 - Cylinder device

Info

Publication number: WO1998029665A1
Application number: PCT/JP1997/004737
Authority: WO
Inventors: Naoki Ishizaki
Original assignee: Komatsu Ltd.
Priority date: 1996-12-26
Filing date: 1997-12-22
Publication date: 1998-07-09
Also published as: KR100504995B1; JPH10184613A; KR19980064138A; JP3781219B2

Abstract

A vacuum is not produced in a cushion chamber having a cushion function. A free piston (15) is movably provided on a small diameter part (11a) of a piston (11). When the piston (11) is made to slide toward a head cover (2), the free piston (15) is mated with a recessed part (16) to form a cushion chamber (20). When the piston (11) is made to slide by the pressure of fluid flowing into a cylinder chamber (13), the free piston (15) is moved by the fluid pressure to establish a communication of the cylinder chamber (13) with the cushion chamber (20). Hence the fluid is made to flow into the cushion chamber (20), thereby not producing a vacuum.

Description

Specification

Cylinder equipment

Technical field

The present invention relates to a cylinder device having a cushion function used in a vibration generator.

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A head chamber and a rod chamber are formed by inserting a screw with a rod into the cylinder tube, and the head chamber and the head chamber are alternately switched between a hydraulic power source and a tank. There is known a cylinder device which reciprocates a rod with a piston in communication with a cylinder.

With this cylinder device, the piston collides with the head side and rod side of the cylinder in the stroke end. A cushion chamber is formed between the ton and the rod side, and a fluid is sealed in the cushion chamber near the stroke to generate a sealing pressure and the piston is formed. They are braking to avoid collision.

In the above-mentioned cylinder device, the cushion chamber is filled near the stroke (cushion-operated type), or communicates with the head chamber and the rod chamber with a very small opening area. As a result, the cushion chamber is evacuated when the piston is moved in the opposite direction.

When the cylinder of the cylinder device moves at a low speed, such as when the work machine moves up and down, the above-mentioned problems caused by the vacuum in the cushion chamber are not noticeable, Vibration When used at relatively high frequency and small stroke, such as in a raw device, the cylinder device's piston moves at a high speed. If a vacuum is generated in the pump chamber, the vacuum may not be satisfied and the cushion function will be impaired.

Therefore, an object of the present invention is to provide a cylinder device capable of solving the above-mentioned problem.

Disclosure of the invention

According to the present invention, a cylinder 11 with a rod 5 is slidably fitted in a cylinder tube 4 to form cylinder chambers 13 and 14. Is provided with a free piston 15 that moves a predetermined stroke to the cylinder, and when the piston 11 approaches the stroke in the negative direction, the free piston 15 and the cylinder tube When the piston 11 moves in the other direction due to the fluid pressure flowing into the cylinder chambers 13 and 14, the cushion chambers 20 and 22 are formed between With fluid pressure, the free piston 15 moves away from the piston 11 and the cushion chamber 20, 2

This is a single cylinder device characterized by having a configuration in which the cylinder 2 and the cylinder chambers 13 and 14 communicate with each other.

According to the present invention, when the piston 11 moves in the minus direction, the cushion chambers 20 and 22 are formed between the free piston 15 and the cylinder tube 4. And the cushion room 2

Fluid pressure is enclosed in 0 and 22. When the piston 11 moves in the other direction, the fluid pressure flowing into the cylinder chambers 13 and 14 The free piston 15 is separated from the piston 11 by the cylinders 13 and 14 and the cushion chambers 20 and 22 communicate with each other. Fluid pressure flows into the chambers 20 and 22. Thus, the cylinder device has a cushion function and does not generate a vacuum in the cushion chamber 20.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1

FIG. 1 is a cross-sectional view illustrating an embodiment of the present invention.

Figure 2

It is an enlarged view of a free screw attachment part.

Fig. 3

FIG. 7 is an explanatory diagram of the operation of the freeston.

Fig. 4

FIG. 6 is a sectional view illustrating a second embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION As shown in Fig. 1, a head cover 2 is fitted and fixed to one end opening of a cylindrical body 1, and a rod cover 3 is fitted to the other end opening of the cylindrical body 1. The cylinder tube 4 is combined. The tip of the rod 5 has an intermediate diameter portion 6, a small diameter portion 7, and a screw portion 8, and has a first step portion 9 and a second step portion 10. The piston 11 is pressed against the second step 10 by a nut 12 fitted to the small diameter portion 7 and screwed to the screw portion 8.

A cylinder chamber 13 (head chamber) is formed between the piston 11 and the head cover 2 of the cylinder tube 4, and the piston chamber is formed. A cylinder chamber 14 (load chamber) is formed between the cylinder 11 and the rod cano 13 of the cylinder tube 4, and the cylinder chambers 13 and 14 are port A, Open to port B.

The head cover 1 side of the piston 11 has a small diameter, so that the free piston 15 is loosely fitted to the small diameter portion 11a so that the nut 12 does not come off. It is kept. The outer peripheral surface 15a of the free piston 15 is slidably fitted into the inner peripheral surface 16a of the concave portion 16 of the head cover 12 so that the inner peripheral surface 15b is A gap is formed between the small-diameter portion 11a and the small-diameter portion 11a.

As shown in Fig. 2, the free piston 15 is shorter than the dimension between the nut 12 and one end face 1 lb of the large-diameter portion of the piston 11 by an L dimension. In addition, a step 17 is formed on the first end face 15c on the piston side, and a slit is formed on the outer peripheral face 15a near the second end face 15d on the head force bar side. An oil passage 18 is formed, and this oil passage 18 is open to the inner peripheral surface 15 b by a radial oil passage 19.

Next, the details of the free piston 15 will be described together with the operation. When pressure fluid is supplied to cylinder chamber 14 from port B, cylinder chamber 13 is connected to tank from port A to tank, and piston 11 slides to the right. One end 11 of the piston 11 comes into contact with the first end 15c of the free piston 15 so that the free piston 15 and the free piston 15 are connected together. Move to the right.

When piston 11 comes close to the stroke, free piston 15 fits into recess 16 to form cushioning chamber 20, and this cushion The fluid pressure in chamber 20 is higher than oil passage 18 When the piston 11 slides further to the right, the cushion chamber 20 and the cylinder chamber 13 are shut off as shown in FIG. Since the fluid pressure is sealed in the cushion chamber 20, it has a cushioning function.

By supplying fluid pressure to port A and communicating port B to the tank from the above-mentioned state, piston 11 slides to the left, but as shown in Fig. 3, The free piston 15 moves to the right due to the inflow pressure into the cylinder chamber 13, the second end face 15 d comes into contact with the nut 12, and the first end face 15 c and the piston 1 One side lib of 1 leaves.

As a result, the fluid pressure flows into the cushioning chamber 20 as shown by the arrow in FIG. 3, and the cushioning chamber 20 is not evacuated.

A free piston 15 is also provided between the intermediate diameter portion 6 of the rod 5 and the concave portion 21 of the rod cover 3 in the same manner as described above. As a result, the cushion chamber 22 is formed, and when the piston 11 slides to the left and approaches the stroke, the fluid flows into the cushion chamber 22. When the piston 11 slides rightward, the other end face 11 c of the piston 11 and the free piston 15 are connected when the piston 11 slides to the right. Fluid pressure flows into the cushion chamber 22 from the gap between the first end face 15c, the gap between the intermediate portion 6 and the inner peripheral face 15b, and from the oil passages 18 and 19. Vacuum in cushion chamber 2 2 does not occur.

FIG. 4 shows a second embodiment, in which a cylindrical body 1 and a head cover 1 are formed in a body. Cut to the outer surface of free piston 15

Claims

A gap 30 is formed so that the fluid piston 15 moves to the right by the fluid pressure flowing into the cylinder chamber 13. The movement stroke of the free piston 15 is about 0.5 mm, and the stroke of the piston 11 is about 5 mm. Shows the state of moving to the right. A cushion chamber 22 is formed between the rod cover 3 and the free piston 15, and the cushion chamber 22 is formed with an oil hole 31 and one cylinder. It is designed to communicate with 14 and block. Reference numeral 32 denotes a chamber for pushing the free piston 15 to the right, and the port opens to the port B through the oil passage 33. Therefore, when the piston 11 moves to the left, fluid pressure is sealed in the cushion chamber 22 to provide a cushion function, and the piston 11 also has a cushion function. Since the high-pressure fluid pressure in the sealing chamber 22 does not act on the sealing member 34 between the rod cano 3 and the rod 5, the sealing member 34 can be prevented from being damaged. . When fluid pressure is supplied from the port B to the cylinder chamber 14, the oil path 33 to the chamber 32, the first step 9 and the second end face 1 of the free piston 15 are connected. The gap between 5d and the gap between the intermediate diameter portion 6 and the inner peripheral surface 15b acts on the stepped portion 17 to push the free piston 15 to the left. There is a gap between the end face 15c and the end face of the piston 11, and the fluid pressure flows from the oil passage 31 into the cushion chamber 22, and the vacuum is not established. Claim scope

1. A piston 11 provided with a rod 5 is slidably inserted into a cylinder tube 4 to form cylinder chambers 13 and 14. A free piston 15 is provided for a predetermined stroke movement, and between the free piston 15 and the cylinder tube 4 when the piston 11 approaches the stroke in the negative direction. When the piston chamber 11 forms the cushion chambers 20 and 22 and flows into the cylinder chambers 13 and 14, and the piston 11 moves in the other direction, the fluid pressure increases. The free chamber 15 is configured to communicate with the cushion chambers 20 and 22 and the cylinder chambers 13 and 14 at a distance from the S piston 11. A rendering device.