Testing method for fuel vapor treating apparatus
First Claim
1. A testing method for a fuel vapor treating apparatus, the treating apparatus including a canister for collecting fuel vapor generated in a fuel tank through a vapor line, wherein the fuel in the tank is supplied to an engine, a purge line for purging the collected fuel in the canister into an air intake passage of the engine by a negative intake pressure generated in the intake passage during operation of the engine, a vapor control valve connected to the vapor line between the tank and the canister for adjusting a flow of the fuel vapor passing from the tank to the canister, wherein the vapor control valve opens in accordance with a difference between the pressure of the tank and the pressure of the canister, the method comprising:
- selectively detecting the pressure at a tank side of the vapor control valve and the pressure at a canister side of the vapor control valve by using pressure detecting means;
judging whether a malfunction has occurred related to a sealing of the tank side or related to a sealing of the canister side based on the detected pressure of the tank side and the detected pressure of the canister side;
alternately detecting the pressure of the tank side and the pressure of the canister side during a predetermined time period subsequent to a starting of the engine; and
judging whether a malfunction of the pressure detecting means has occurred based on the detected pressures.
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Accused Products
Abstract
A fuel vapor treating apparatus that collects fuel vapor produced in a fuel tank and treats the vapor without releasing it into the atmosphere. The treating apparatus is provided with a canister that collects the fuel vapor through a vapor line. A vapor control valve provided in the canister adjusts the flow of fuel vapor directed toward the canister from the tank. A purge line connects the canister to an air intake passage of an engine. The fuel collected in the canister is purged into the air intake passage through the purge line. A purge control valve provided in the purge line adjusts the flow rate of the fuel flowing through the purge line. A three-way valve selectively switches the section to which the pressure sensor is connected between the tank side and the canister side. An electronic control unit (ECU) controls the second control valve and the three-way valve. The ECU tests the sealing of the tank side and the canister side based on the tank pressure and the canister pressure, which are detected by the pressure sensor. The ECU controls the three-way valve to alternately connect the pressure sensor to the tank side and the canister side during a predetermined time period subsequent to the starting of the engine. As the connection is switched, alteration in the output occurs in accordance with the normal state or abnormal state of the connected side. The ECU further tests the pressure sensor by distinguishing the output alteration.
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Citations
17 Claims
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1. A testing method for a fuel vapor treating apparatus, the treating apparatus including a canister for collecting fuel vapor generated in a fuel tank through a vapor line, wherein the fuel in the tank is supplied to an engine, a purge line for purging the collected fuel in the canister into an air intake passage of the engine by a negative intake pressure generated in the intake passage during operation of the engine, a vapor control valve connected to the vapor line between the tank and the canister for adjusting a flow of the fuel vapor passing from the tank to the canister, wherein the vapor control valve opens in accordance with a difference between the pressure of the tank and the pressure of the canister, the method comprising:
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selectively detecting the pressure at a tank side of the vapor control valve and the pressure at a canister side of the vapor control valve by using pressure detecting means; judging whether a malfunction has occurred related to a sealing of the tank side or related to a sealing of the canister side based on the detected pressure of the tank side and the detected pressure of the canister side; alternately detecting the pressure of the tank side and the pressure of the canister side during a predetermined time period subsequent to a starting of the engine; and judging whether a malfunction of the pressure detecting means has occurred based on the detected pressures. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A testing method for a fuel vapor treating apparatus, the treating apparatus including a canister for collecting fuel vapor generated in a fuel tank through a vapor line, wherein the fuel in the tank is supplied to an engine, a purge line for purging the collected fuel in the canister into an air intake passage of the engine by a negative intake pressure generated in the intake passage during operation of the engine, a vapor control valve connected to the vapor line between the tank and the canister for adjusting a flow of the fuel vapor passing from the tank to the canister, wherein the vapor control valve opens in accordance with a difference between the pressure of the tank and the pressure of the canister, the method comprising:
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selectively detecting the pressure at a tank side of the vapor control valve and the pressure at a canister side of the vapor control valve by using pressure detecting means; judging whether a malfunction has occurred related to a sealing of the tank side or related to a sealing of the canister side based on the detected pressure of the tank side and the detected pressure of the canister side; alternately detecting the pressure of the tank side and the pressure of the canister side for first predetermined time periods by using said pressure detecting means during a second predetermined time period subsequent to a starting of the engine; and judging whether a malfunction of the pressure detecting means has occurred when the alternately detected pressure values remain outside of a predetermined range for a third predetermined time period. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17)
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Specification