# US 5,343,797 A · Cylinder device

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- Number: US 5,343,797 A
- Document ID: US5343797A
- Status: Granted
- Kind: A
- Application number: 08/042,271
- Filed: 1993-04-02
- Granted: 1994-09-06
- Earliest claimed: 1992-04-02
- Assignees: Toshiba Kikai Kabushiki Kaisha
- Inventors: Akira Ochiai; Akihiko Yuasa; Shigeki Otaka
- Web page: https://patentgrep.com/patent/US5343797A

## CPC

- F15B 15/16: of the telescopic type
- F15B: SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR

## Abstract

A cylinder device which is capable of restraining the total length thereof to a shorter length even when the stroke is made longer, and which thereby provides the compact appearance and layout of, for example, a machine tool, in which the cylinder device is used. The cylinder device includes a first cylinder provided with an extensible piston rod. The piston rod is constituted as a cylinder tube of a second cylinder. The extensible piston rod of the second cylinder is formed in the interior thereof with a flow path for guiding a working fluid into a cylinder chamber of the second cylinder constituted by the piston rod of the first cylinder.

## Claims

### Claim 1

A cylinder device, comprising:
a hollow cylinder tube having a supply flow path formed therein for a working fluid;
a first piston slidably accommodated in said hollow cylinder tube;
a first guide bar inserted through said first piston;
a first piston rod connected to said first piston through said first guide bar and provided with a cylindrical room therein;
said first piston rod being provided with a first cushion chamber formed between an inner peripheral surface of said piston rod and an end portion of said guide bar;
a plurality of belleville springs provided between said guide bar and an inside of said first piston;
a second piston slidably accommodated in said cylindrical room of said first piston rod;
a second guide bar inserted through said second piston;
a second piston rod connected to said second piston through said second guide bar;
said second piston rod being provided with a second cushion chamber formed between an inner peripheral surface of said piston rod and an end portion of said guide bar;
a plurality of belleville springs provided between said guide bar and an inside of said second piston; and
a means for supplying the working fluid into said cylindrical room of said first piston rod.

### Claim 2

A double housing type machine tool, comprising:
a double housing balancing device and
a cylinder device having
a hollow cylinder tube having a supply flow path formed therein for a working fluid;
a first piston slidably accommodated in said hollow cylinder tube;
a first guide bar inserted through said first piston;
a first piston rod connected to said first piston through said first guide bar and provided with a cylindrical room therein;
said first piston rod being provided with a first cushion chamber formed between an inner peripheral surface of said piston rod and an end portion of said guide bar;
a plurality of belleville springs provided between said guide bar and an inside of said first piston;
a second piston slidably accommodated in said cylindrical room of said first piston rod;
a second guide bar inserted through said second piston;
a second piston rod connected to said second piston through said second guide bar;
said second piston rod being provided with a second cushion chamber formed between an inner peripheral surface of said piston rod and an end portion of said guide bar;
a plurality of belleville springs provided between said guide bar and an inside of said second piston; and
a means for supplying said working fluid into said cylindrical room of said first piston rod;
said double housing balancing device for holding a cross beam for up and down motion by said cylinder device, said cross beam bridging a pair of columns standing parallel to each other.