Liquid-operated cylinder

• US 20110049811A1
• Filed: 08/16/2010
• Published: 03/03/2011
• Est. Priority Date: 08/26/2009
• Status: Active Grant

• Current Assignee: KYB Corp.
• Original Assignee: Kayaba Industry Company Limited (KYB Corp.)
• Inventors: Tanaka, Daisuke, Sueyoshi, Daisuke
• Granted Patent: US 8,403,335 B2
• Time in Patent Office: Days
• US Class Current: 277/434
• CPC Class Codes: F15B 15/1452 Piston sealings
• CPC Class Codes: F16J 15/164 the sealing action depending on movements; pressure difference, temperature or presence of leaking fluid
• CPC Class Codes: F16J 9/06 using separate springs or elastic elements expanding the rings; Springs therefor ; Expansion by wedging

Abstract

A piston seal (50) of a liquid-operated cylinder includes a main seal ring (51) that slidably contacts the inner circumferential surface (11) of the cylinder tube (10); an O-ring (52) that imparts a force causing an outer circumference of the main seal ring (51) to move closer to the inner circumferential surface of the cylinder tube (10) by pressing onto an inner circumference of the main seal ring (51); and a sub-seal ring (53) that is disposed parallel to the main seal ring (51) at a position further toward the cushion pressure chamber (6) and is pressed by the main seal ring (51), as pressure from the drive pressure chamber (5) is applied to the main seal ring (51), to slidably contact the inner circumferential surface of the cylinder tube (10).

Claims

1. A liquid-operated cylinder which is caused to extend by a pressurized hydraulic fluid guided into a drive pressure chamber, comprising:

a cylinder tube;

a piston that defines the drive pressure chamber and a cushion pressure chamber inside the cylinder tube; and

a piston seal that is disposed at an outer circumference of the piston and slidably contacts an inner circumferential surface of the cylinder tube,

wherein the piston seal comprises;

a main seal ring that slidably contacts the inner circumferential surface of the cylinder tube;

an O-ring that imparts a force causing an outer circumference of the main seal ring to move closer to the inner circumferential surface of the cylinder tube by pressing onto an inner circumference of the main seal ring; and

a sub-seal ring that is disposed parallel to the main seal ring at a position further toward the cushion pressure chamber and is pressed by the main seal ring, as pressure from the drive pressure chamber is applied to the main seal ring, to slidably contact the inner circumferential surface of the cylinder tube.

2. The liquid-operated cylinder as defined in claim 1, wherein:

the piston seal is disposed inside a housing groove formed at an outer circumference of the piston;

the housing groove includes a main housing groove in which the main seal ring is housed and a sub-housing groove in which the sub-seal ring is housed, the sub-housing groove assuming a smaller groove depth than the main housing groove and ranging continuously, via a stage, to the main housing groove; and

the sub-seal ring, assuming a ring width greater than a groove width of the sub-housing groove, is pushed in a direction extending along the groove width by the main seal ring housed inside the main housing groove as the pressure from the drive pressure chamber is applied to the main seal ring.