Two stage flowmeter
US4232549A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 6, 1978 |
| Grant date | Nov 11, 1980 |
| Priority date | — |
| Expiry date | Dec 6, 1998 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01F1/44
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A low pressure drop air flowmeter for an automobile engine is disclosed. The meter contains a main air flow passage, a relatively small venturi to receive a portion of the air flow, pressure ports for sensing stagnation and static pressure and a set of swirl vanes disposed adjacent the outlet of the venturi and operative to impart a swirl to the remainder of the air in the main passage, thereby creating a reduced pressure at the venturi outlet for amplifying the pressure difference between the stagnation and static pressure without appreciably increasing the pressure drop across the flowmeter. A tertiary passage provides a path of fluid communication between points upstream and downstream of the swirl vanes. This passage can be selectively opened or restricted by a valve which, in the preferred embodiment of the invention, opens the tertiary passage with increasing overall flow rate. This arrangement results in a fluid flowmeter having a characteristic pressure drop which is less than that of a conventional device, particularly at high flow rates. Also disclosed is a solenoid valve operative to selectively sample stagnation pressure in the tertiary passage and signal pressure in th…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.