Reciprocatory piston and cylinder machine
US4790726A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 24, 1987 |
| Grant date | Dec 13, 1988 |
| Priority date | — |
| Expiry date | Feb 24, 2007 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S417/01
- WIPO fieldEngines, pumps, turbines
- WIPO sectorMechanical engineering
Abstract
A reciprocatory piston and cylinder machine particularly suitable for use as a vacuum pump includes a cylinder (17), a cylindrical piston (16) relatively slidably reciprocable within the cylinder (17), and means for substantially sealing the annular space between the piston (16) and cylinder (17) in lieu of oil or other liquid lubricant. The sealing means comprises a sleeve (102) of a low-friction material disposed under circumferential tension, and preferably also under longitudinal tension, on the cylindrical surface of the piston (16). Also disclosed is a reciprocatory piston and cylinder machine of particular prior construction having a one-way valve (42) in an exhaust port (30) ahead of a head portion (24) of the piston (16). The arrangement is such that, as the front face of the piston head portion (24) approaches the closed cylinder end (52), the piston head portion 24 physically moves the one-way valve (42) so as to open the exhaust port (30).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.