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A CARBON CANISTER INTEGRITY DIAGNOSTIC FOR HEV USING ELCM PUMP

IP.com Disclosure Number: IPCOM000238913D
Publication Date: 2014-Sep-24
Document File: 1 page(s) / 222K

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The IP.com Prior Art Database

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A CARBON CANISTER INTEGRITY DIAGNOSTIC FOR HEV USING ELCM PUMP

Vehicles sold in North America must adsorb running loss, diurnal and refueling vapors inside a carbon canister. CARB is asking OEMs to investigate methods for diagnosing the integrity of carbon canisters,
i.e., canister's ability to adsorb and desorb hydrocarbons (HC). In ordinary vehicles, the canister integrity is easily diagnosable using temperature sensors inside the canister. Adsorption is validated during refueling event and desorption is validated during purging. With PHEV vehicles, purging is infrequent due to limited engine run time which constrains purging the canister. Also, refueling events are rare if driver chooses to plug in and recharge the battery every day. Hence a different method is needed to perform canister integrity diagnostics for PHEV.

Method

Vehicles sold in North America are required to perform Evap leak detection. Green states required to monitor for 0.02" leaks. For HEV, engine run time is limited hence a vacuum pump is required for leak detection. One such vacuum pump is the ELCM made by Denso Corporation. ELCM contains an internal pressure sensor. This method performs diagnostics on the canister using active testing via the ELCM system as well as temperature sensor at the load side of the canister. Next generation canister designs will include internal heated elements and thermocouples to facilitate better canister HC desorption. During a typical leak detection run, the...