LOW PURGE FLOW VEHICLE DIAGNOSTIC TOOL
First Claim
1. A vehicle comprising:
- an internal combustion engine;
a sealed fuel system having a fuel tank, a canister for storing fuel vapor from the fuel tank, a vapor circuit positioned external to the fuel tank and in fluid communication with the fuel tank, and a control valve for controlling a flow of fuel vapor from the vapor circuit into the canister, wherein the vapor circuit includes an absolute pressure sensor, a pump, and a switching valve selectively connecting the fuel tank to the absolute pressure sensor when the control valve is open; and
a controller having an algorithm for evaluating or diagnosing a vapor purge function of the sealed fuel system using vacuum measurements from the absolute pressure sensor;
wherein the controller executes the algorithm only when the engine is running, vapor purge is enabled, and the pump is off, and diagnoses the vapor purge function by comparing the vacuum measurements to a calibrated vacuum.
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Accused Products
Abstract
A vehicle includes an engine, a sealed fuel system having a fuel tank, a canister for storing fuel vapor, a vapor circuit external to the fuel tank, and a control valve. The vapor circuit includes an absolute pressure sensor and a switching valve connecting the fuel tank to the control valve. A controller evaluates or diagnoses a vapor purge function of the sealed fuel system using vacuum measurements from the absolute pressure sensor, executing or diagnosing only when the engine is running, purge is enabled, and the pump is off. The controller diagnoses the vapor purge function by comparing the vacuum measurements to a threshold vacuum. An apparatus includes the vapor circuit and controller. A method for diagnosing the vapor purge function includes actuating the switching valve, measuring a vacuum in the system using the absolute pressure sensor, and comparing the measured vacuum to a threshold vacuum.
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Citations
14 Claims
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1. A vehicle comprising:
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an internal combustion engine; a sealed fuel system having a fuel tank, a canister for storing fuel vapor from the fuel tank, a vapor circuit positioned external to the fuel tank and in fluid communication with the fuel tank, and a control valve for controlling a flow of fuel vapor from the vapor circuit into the canister, wherein the vapor circuit includes an absolute pressure sensor, a pump, and a switching valve selectively connecting the fuel tank to the absolute pressure sensor when the control valve is open; and a controller having an algorithm for evaluating or diagnosing a vapor purge function of the sealed fuel system using vacuum measurements from the absolute pressure sensor; wherein the controller executes the algorithm only when the engine is running, vapor purge is enabled, and the pump is off, and diagnoses the vapor purge function by comparing the vacuum measurements to a calibrated vacuum. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An apparatus for use aboard a vehicle having a sealed fuel system, the sealed fuel system having a fuel tank, a canister for storing fuel vapor from the fuel tank, and a control valve for controlling a flow of fuel vapor into the canister, the apparatus comprising:
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a vapor circuit positioned external to the fuel tank and in fluid communication with the fuel tank and the control valve, and having an absolute pressure sensor, a pump, and a switching valve selectively connecting the fuel tank to the absolute pressure sensor when the control valve is open; and a controller having an algorithm for evaluating or diagnosing a vapor purge function of the sealed fuel system using vacuum measurements from the absolute pressure sensor; wherein the controller executes the algorithm only when the engine is running, vapor purge is enabled, and the pump is off, and diagnoses the vapor purge function by comparing the vacuum measurements to a calibrated vacuum. - View Dependent Claims (8, 9, 10, 11)
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12. A method of evaluating or diagnosing a vapor purge function of a sealed fuel system aboard a vehicle having an internal combustion engine and a fuel tank, the method comprising:
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actuating a switching valve in a vapor circuit positioned external to the fuel tank when the engine is running and a fuel system purge cycle is enabled, the vapor circuit including an absolute pressure sensor and a pump; measuring a vacuum level using the absolute pressure sensor while the pump is off; comparing the vacuum level from the absolute pressure sensor to an initial vacuum level after a control valve is opened and the switching valve is activated to thereby determine a vacuum differential; and executing a control action corresponding to the vacuum differential. - View Dependent Claims (13, 14)
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Specification