Claims
- 1. In a hydraulic breaker comprising:
- a cylinder means;
- a piston slidably mounted in said cylinder means for sliding therein between an uppermost position and a lowermost position,
- said piston having a five-staged configuration including a first, a second, a third, a fourth and a fifth stage sequentially disposed along an axial direction of the piston,
- said piston also including a high pressure receiving surface extending between said first stage and said second stage, a lower pressure receiving surface extending between said fourth stage and said fifth stage and a gas pressure receiving surface,
- said high pressure receiving surface having a diameter larger than that of said gas pressure receiving surface, and said low pressure receiving surface having an area that is larger than that of said high pressure receiving surface;
- said cylinder means having a gas chamber therein for containing gas under pressure, said gas chamber open to said gas pressure receiving surface of said piston for urging said piston from said uppermost position to said lowermost position,
- a high pressure port open to a source of high pressure oil for allowing high pressure oil to pass into said cylinder means,
- a low pressure port for discharging oil from said cylinder means,
- a piston high pressure chamber defined between an interior peripheral wall of said cylinder means and said piston, said piston high pressure open to said high pressure receiving surface of said piston,
- said piston high pressure chamber and said high pressure port in constant open communication so that high pressure oil supplied through said high pressure port exerts a force on said high pressure receiving surface that acts in a direction to move the piston toward said lowermost position whenever the piston is being raised from said lowermost position or lowered from said uppermost position,
- a piston low pressure chamber defined between the interior peripheral wall of said cylinder means and said third stage of said piston, said low pressure chamber in constant open communication with said low pressure port for allowing oil to be incessantly discharged therefrom through said low pressure port whenever said piston is being raised from said lowermost position or lowered from said uppermost position, and
- a piston contradirection chamber open to said lower pressure receiving surface;
- a main valve movably disposed within said cylinder means for moving between first and second positions therein, said main valve in operative hydraulic communication with said high pressure port and said low pressure chamber and said contradirection chamber, said main valve having a passageway extending therethrough,
- said first position being a position at which a first flow path for oil is established from said contradirection chamber, through said passageway of said main valve and to said low pressure chamber for allowing oil in said contradirection chamber to be discharged therealong to said low pressure port as said piston is being lowered from said uppermost position,
- said second position being a position at which said first flow path is closed and a second flow path for oil is established between said high pressure port and said contradirection chamber for allowing high pressure oil to flow therealong to act on said lower pressure receiving surface for raising said piston from said lowermost position, the improvement thereof characterized in that the piston low pressure chamber has substantially same dimension of diameter as that of the fourth stage which is larger than the diameters of the second and third stages so that a spare space is provided for reserving an excess oil when the piston is lowering down at high speed.
Priority Claims (2)
Number |
Date |
Country |
Kind |
61-54133 |
Mar 1986 |
JPX |
|
61-220613 |
Sep 1986 |
JPX |
|
Parent Case Info
This application is a Continuation-In-Part of U.S. application Ser. No. 013,442 filed Feb. 10, 1987, now U.S. Pat. No. 4,817,737.
US Referenced Citations (4)
Foreign Referenced Citations (6)
Number |
Date |
Country |
1243118 |
Jun 1967 |
DEX |
2264986 |
Mar 1975 |
FRX |
2267858 |
Apr 1975 |
FRX |
2304448 |
Mar 1976 |
FRX |
1161369 |
Jun 1985 |
SUX |
2008187 |
May 1979 |
GBX |
Continuation in Parts (1)
|
Number |
Date |
Country |
Parent |
13442 |
Feb 1987 |
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