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, the execution of which by the controller causes the controller to diagnose a vapor purge function of the sealed fuel system using vacuum measurements from the absolute pressure sensor;
wherein the controller is configured to execute the algorithm only when the engine is running, vapor purge is enabled, and the pump is off, and diagnoses the vapor purge function while the pump remains off by comparing the vacuum measurements to a calibrated vacuum.
4 Assignments
0 Petitions
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.
20 Citations
11 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, the execution of which by the controller causes the controller to diagnose a vapor purge function of the sealed fuel system using vacuum measurements from the absolute pressure sensor; wherein the controller is configured to execute the algorithm only when the engine is running, vapor purge is enabled, and the pump is off, and diagnoses the vapor purge function while the pump remains off 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 is configured to execute the algorithm only when the engine is running, vapor purge is enabled, and the pump is off, and diagnoses the vapor purge function while the pump remains off by comparing the vacuum measurements to a calibrated vacuum. - View Dependent Claims (8, 9, 10, 11)
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Specification