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AN EVAP SYSTEM WITH ENERGY SAVING LATCHABLE VALVES

IP.com Disclosure Number: IPCOM000237278D
Publication Date: 2014-Jun-11
Document File: 1 page(s) / 217K

Publishing Venue

The IP.com Prior Art Database

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AN EVAP SYSTEM WITH ENERGY SAVING LATCHABLE VALVES

Vehicles sold in North America are required to adsorb diurnal, running loss and refueling vapors inside a carbon canister. The canister is typically cleaned or purged using engine vacuum. HEV and Start/Stop vehicles utilize a special Vapor Blocking Valve (VBV) to improve purge efficiency. This is due to limited engine run time in those vehicles. While purging, the VBV is commanded closed. This way, the canister is cleaned out without further loading with vapors from the fuel tank. At key off, VBV is typically open and the Evap system is vented to atmosphere. VBV draws 500mA current when energized. This results in a battery drain which translates to a fuel economy penalty. Additionally, vehicles must perform Evap leak diagnostics on the Evap system. Typically, a Canister Vent Solenoid (CVS) valve is used to seal the Evap system in order to perform leak diagnostics. The CVS draws up to 300mA when energized. If an Evap leak detection method that uses the diurnal temperature cycle is to be employed, the CVS could be commanded closed for a long duration. The current draw on the CVS would drain the battery.

Method

This system uses latchable valves in lieu of valves that demand continuous power. Both the VBV and the CVS are replaced with new latchable valves. The latchable valves typically require a 100ms 12V pulse to change state from open to close and visa-versa. Once pulsed, the latchable valve does not draw additio...