US4048975A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Pistons
Assignee: FBJ Engineering Services Pty Ltd
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Filing: 1975-11-12
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Granted: 1977-09-20
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Expires: 1995-11-12
Abstract
Abstract A piston such as is used in internal combustion engines, steam engines, gas engines, air engines, pumps, compressors and the like from which the usual piston rings are absent the sealing of the piston being affected by means of right and left hand intersecting helical channels formed on a portion of the surface of the piston wall. It is preferred that the helical channels terminate at each end in a circumferential groove. The sealing is effected by means of oil trapped by the channels between the piston wall and a cylinder in which the piston operates.
Inventors
- 👤 William James Urquhart
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 15:32
CPC Classifications
F; F16; F16J; F16J1/00; F16J1/09; F04; F04B; F04B39/00; F04B39/04; F04B39/041; F04B39/045; F16J15/00; F16J15/44
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
136 words
A piston for use in an internal combustion engine or compressor without piston rings, said piston having as a sealing means a pair of circumferential grooves formed in the external surface of the piston, said grooves being spaced apart axially and being interconnected by right and left hand intersecting helical channels formed on the external surface of the piston, said grooves and channels being adapted to trap and retain lubricating oil, and a plurality of grooves in a plane perpendicular to the axis of the piston separated by at least one land having a sharp apex formed in the external surface of the piston, provided at one end of said piston wherein the diameter of the piston at the apex being substantially the same as the maximum diameter of the piston between the pair of grooves.
Claim 2
Dependent Claim
136 words
A piston for use in an internal combustion engine or compressor without piston rings, said piston having as a sealing means a pair of circumferential grooves formed in the external surface of the piston, said grooves being spaced apart axially and being interconnected by right and left hand intersecting helical channels formed on the external surface of the piston, said grooves and channels being adapted to trap and retain lubricating oil, and a plurality of grooves in a plane perpendicular to the axis of the piston separated by at least one land having a sharp apex formed in the external surface of the piston, provided at one end of said piston wherein the diameter of the piston at the apex being substantially the same as the maximum diameter of the piston between the pair of grooves.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-09-19 | 1981-03-21 | 1981-09-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-09-19 | 1985-03-21 | 1985-09-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-09-19 | 1989-03-21 | 1989-09-20 | $7700.00 | Window Closed / Lapsed |