Leak detection pump with integral vent seal
US5474050A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 13, 1995 |
| Grant date | Dec 12, 1995 |
| Priority date | — |
| Expiry date | Jan 13, 2015 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF02M25/0809
- WIPO fieldEngines, pumps, turbines
- WIPO sectorMechanical engineering
Abstract
An on-board diagnostic system for an evaporative emission control system of an internal combustion engine powered vehicle employs a positive displacement reciprocating pump to create in evaporative emission space a pressure that differs significantly from ambient atmospheric pressure. The pump is powered by using engine intake manifold vacuum to force an intake stroke during which both an internal spring is increasingly compressed and a charge of ambient atmospheric air is created in an air pumping chamber space. Vacuum is then removed, and the spring relaxes to force a compression stroke wherein a portion of the air charge is forced into the evaporative emission space. The rate at which the pump reciprocates to alternately execute intake and compression strokes indicates the pressure and flow through a leak in the evaporative emission space. Detection of this rate serves as a measurement of leakage for the purpose of distinguishing integrity of the evaporative emission space from non-integrity. The disclosed pump has a novel arrangement of its internal valving that reduces the number of parts required in comparison to a previous pump.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.