Rate-based monitoring for an engine system
First Claim
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1. An engine management system comprising:
- a rate based monitor operable to perform test cycles on a monitored system when predetermined conditions are met, a test cycle being completed when a correct operation or malfunction of the monitored system could have been detected irrespective of whether a malfunction or correct operation is detected, the rate based monitor comprising;
a counter for counting a number of times a completed test cycle is performed; and
a timer operable to define a test cycle completion timing, the timer timing a test cycle from a start of a test cycle until a timing when the correct operation or malfunction of the monitored system could have been detected irrespective of whether a malfunction or correct operation is detected, the timer being reset it one or more of the predetermined conditions cease to be met;
wherein the counter is updated in response to the timer timing out on completion of a test cycle;
the monitored system is a fuel system that includes a fuel tank, and the test cycle is operable to rest for a leak; and
the rate based monitor is operable to effect a test cycle that includes;
closing an air path shutoff valve in an air path from an air intake to the fuel system;
opening a purge valve in a purge path from an engine intake manifold to the fuel system;
closing the purge valve when a predetermined pressure is detected in the fuel system; and
performing pressure computations based on measured pressures in the fuel system to detect a leak, a failure being notified in response to predetermined pressure computation results.
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Abstract
Rate based monitoring includes performing test cycles on a monitored system when predetermined conditions are met. Completion of a test cycle is determined by timing a period that is at least as long as the longer of a time required to detect a correct operation of the monitored system and a time to detect a malfunction of the monitored system, the timing being reset if one or more of the predetermined conditions cease to be met. A count is kept of completed test cycles.
18 Citations
12 Claims
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1. An engine management system comprising:
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a rate based monitor operable to perform test cycles on a monitored system when predetermined conditions are met, a test cycle being completed when a correct operation or malfunction of the monitored system could have been detected irrespective of whether a malfunction or correct operation is detected, the rate based monitor comprising; a counter for counting a number of times a completed test cycle is performed; and a timer operable to define a test cycle completion timing, the timer timing a test cycle from a start of a test cycle until a timing when the correct operation or malfunction of the monitored system could have been detected irrespective of whether a malfunction or correct operation is detected, the timer being reset it one or more of the predetermined conditions cease to be met; wherein the counter is updated in response to the timer timing out on completion of a test cycle; the monitored system is a fuel system that includes a fuel tank, and the test cycle is operable to rest for a leak; and the rate based monitor is operable to effect a test cycle that includes; closing an air path shutoff valve in an air path from an air intake to the fuel system; opening a purge valve in a purge path from an engine intake manifold to the fuel system; closing the purge valve when a predetermined pressure is detected in the fuel system; and performing pressure computations based on measured pressures in the fuel system to detect a leak, a failure being notified in response to predetermined pressure computation results. - View Dependent Claims (2, 3, 4, 5)
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6. An engine management system comprising:
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a rate based monitor operable to perform test cycles on a monitored system when predetermined conditions are met, a test cycle being completed when a correct operation or malfunction of the monitored system could have been detected irrespective of whether a malfunction or correct operation is detected, the rate based monitor comprising; a counter for counting a number of times a completed test cycle is performed; and a timer operable to define a test cycle completion timing, the timer timing a test cycle from a start of a test cycle until a timing when the correct operation or malfunction of the monitored system could have been detected irrespective of whether a malfunction or correct operation is detected, the timer being reset if one or more of the predetermined conditions cease to be met; wherein the counter is updated in response to the timer timing out on completion of a test cycle; and a count value in the counter forms a numerator of a rate based monitor ratio, a further count being maintained as a denominator of the ratio, the further count being a count of a number of times a predetermined drive cycle is completed.
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7. An engine management rate based monitoring method for performing test cycles on a monitored system, the test cycle only being performed when predetermined conditions are met, the method comprising:
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maintaining a count of a number of times a completed test cycle is performed; timing completion of a test cycle by timing a period that is at least as long as the longer of a time required to detect a correct operation of the monitored system and a time to detect a malfunction of the monitored system, the timing being reset if one or more of the predetermined conditions cease to be met; and updating the count on completion of the timed period; wherein the monitored system is a fuel system that includes a fuel tank, and the test cycle is operable to test for a leak; and a test cycle includes; closing an air path shutoff valve in an air path from an air intake to the fuel system; opening a purge valve in a purge path from an engine intake manifold to the fuel system; closing the purge valve when a predetermined pressure is detected in the fuel system; and performing pressure computations based on measured pressures in the fuel system to detect a leak, a failure being notified in response to predetermined pressure computation results. - View Dependent Claims (8, 9, 10, 11)
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12. An engine management rate based monitoring method for performing test cycles on a monitored system, the test cycle only being performed when predetermined conditions are met, the method comprising:
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maintaining a count of a number of times a completed test cycle is performed; timing completion of a test cycle by timing a period that is at least as long as the longer of a time required to detect a correct operation of the monitored system and a time to detect a malfunction of the monitored system, the timing being reset if one or more of the predetermined conditions cease to be met; and updating the count on completion of the timed period; wherein the count forms a numerator of a rate based monitor ratio, a further count being maintained as a denominator of the ratio, the further count being a count of a number of times a predetermined drive cycle is completed.
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Specification