Duty cycling feature for the proportional purge solenoid to improve low flow resolution
US6148804A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 22, 1999 |
| Grant date | Nov 21, 2000 |
| Priority date | — |
| Expiry date | Nov 22, 2019 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF02D41/004
- WIPO fieldEngines, pumps, turbines
- WIPO sectorMechanical engineering
Abstract
A method of controlling a proportional purge solenoid is provided to improve low flow resolution. The method includes looking-up a primary duty cycle corresponding to purge current in a three-dimensional surface by using purge flow and vacuum level as inputs. Should the primary duty cycle fall below a lowest allowable purge current threshold value, a secondary purge duty cycle (i.e., an on/off pattern of the primary duty cycle) is obtained from a two-dimensional table by using the actual calculated purge flow as an input. The two-dimensional table includes a sequence of program loops subdivided into a delay region wherein the purge flow and vacuum level data are learned, an updating region wherein the purge current of the three-dimensional surface is updated, and a control region wherein the primary duty cycle is toggled between on and off states. When the current program loop falls within the delay region, a recorded primary duty cycle is output. When the current program loop falls within the updating region, the primary duty cycle is applied at a time determined during the last program sequence. When the current program loop falls within the control period, the primary duty cycle…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.