초록 ▼

A fuel-vapor-processing system for an engine has a canister for accumulating fuel evaporation gas. The system has a leak-check apparatus for checking a leak on passages. The leak-check apparatus includes a leak-check means for carrying out leak-check processing when the engine if in a stopped state.

A fuel-vapor-processing system for an engine has a canister for accumulating fuel evaporation gas. The system has a leak-check apparatus for checking a leak on passages. The leak-check apparatus includes a leak-check means for carrying out leak-check processing when the engine if in a stopped state. The leak-check means operates only if a predetermined condition is satisfied. It is thus possible to reduce the number of times the leak-check processing is carried out and, hence, possible to reduce power consumption. For example, only if a relatively small leak is detected when the engine is in a running state, the leak-check processing is carried out in a stopped state to verify existence of such a leak. In the leak-check processing, the temperature of fuel, detected by a sensor or an estimated value, may be taken into consideration.

대표청구항 ▼

What is claimed is: 1. A fuel-temperature estimation apparatus for estimating a fuel temperature of a fuel tank employed in an engine in a running state of the engine, the fuel-temperature estimation apparatus comprising: a fuel-temperature-increase estimation means for estimating an increase in fu

What is claimed is: 1. A fuel-temperature estimation apparatus for estimating a fuel temperature of a fuel tank employed in an engine in a running state of the engine, the fuel-temperature estimation apparatus comprising: a fuel-temperature-increase estimation means for estimating an increase in fuel temperature in the fuel tank on the basis of an operating condition in the running state of the engine; and a fuel-temperature-decrease estimation means for estimating a decrease in fuel temperature in the fuel tank on the basis of a vehicle speed and/or an intake-air temperature or on the basis of information having correlations with the vehicle speed and/or the intake-air temperature, wherein a present estimated value of the fuel temperature is updated on the basis of a fuel-temperature increase estimated by the fuel-temperature-increase estimation means and a fuel-temperature decrease estimated by the fuel-temperature-decrease estimation means. 2. A fuel-temperature estimation apparatus according to claim 1, wherein the fuel-temperature-increase estimation means estimates a fuel-temperature increase caused by exhaust-gas heat dissipated to the fuel tank. 3. A fuel-temperature estimation apparatus according to claim 1, wherein the fuel-temperature-increase estimation means estimates an increase in fuel temperature on the basis of the engine's revolution speed and/or load. 4. A fuel-temperature estimation apparatus according to claim 1, wherein: the fuel-temperature estimation apparatus is applied to a fuel system in which an excessive portion of fuel supplied by a fuel pump from the fuel tank to a fuel injection valve is returned to the fuel tank; and the fuel-temperature-increase estimation means estimates a fuel-temperature increase caused by exhaust-gas heat dissipated to the fuel tank as well as a fuel-temperature increase caused by the excessive portion returned from the fuel injection valve to the fuel tank. 5. A fuel-temperature estimation apparatus according to claim 1 wherein: the fuel-temperature estimation apparatus is applied to a fuel system with a configuration including a fuel pump installed in the fuel tank; and the fuel-temperature-increase estimation means also estimates a fuel-temperature increase caused by heat dissipated by the fuel pump in the fuel tank. 6. A fuel-temperature estimation apparatus according to claim 1, wherein the fuel-temperature-increase estimation means and the fuel-temperature-decrease estimation means each have a correction means for correcting a present fuel-temperature estimated value on the basis of an amount of residual fuel left in the fuel tank and/or a previous fuel-temperature estimated value. 7. A fuel-temperature estimation apparatus according to claim 1, wherein the fuel-temperature-increase estimation means and the fuel-temperature-decrease estimation means each estimate a fuel-temperature initial value at the present start of the engine on the basis of a fuel-temperature estimated value estimated in a previous stopped state of the engine, a lapse of time since the previous stopped state of the engine till the present start of the engine and an ambient temperature or information having a correlation with the ambient temperature. 8. A leak-check apparatus comprising a fuel-temperature estimation apparatus according to claim 1 and a leak-check means for checking a leak in an fuel-vapor-processing system of an engine in a running state of the engine, wherein the leak-check means uses a fuel-temperature estimated value estimated by the fuel-temperature estimation apparatus as a fuel-check execution condition determination parameter and/or a leak-check parameter. 9. A leak-check apparatus according to claim 8, wherein, as one of fuel-check execution conditions, a fuel-temperature estimated value estimated by the fuel-temperature estimation apparatus is required to be not greater than a predetermined value. 10. An abnormality diagnosis apparatus for diagnosing a fuel-temperature sensor for detecting a temperature of fuel in a fuel tank for a sensor abnormality, the abnormality diagnosis apparatus comprising: a fuel-temperature estimation apparatus according to claim 1; and an abnormality diagnosis means for diagnosing the fuel-temperature sensor for a sensor abnormality on the basis of a relation between fuel-temperature estimated values estimated by the fuel-temperature estimation apparatus and fuel-temperature detection values output by the fuel-temperature sensor. 11. An abnormality diagnosis apparatus according to claim 10, wherein the abnormality diagnosis means diagnoses the fuel-temperature sensor for a sensor abnormality on the basis of a relation between variations in the fuel-temperature estimated value estimated over a predetermined period and variations in the fuel-temperature detection value output over the predetermined period. 12. A fuel-temperature estimation apparatus having a fuel-temperature estimation means for estimating a fuel temperature of a fuel tank employed in an engine in a stopped state of the engine without using a temperature sensor, wherein an estimated value of the fuel temperature in the stopped state of the engine is updated on the basis of a lapse of time since the start of the stopped state or information having a correlation with the lapse of time. 13. A fuel-temperature estimation apparatus according to claim 12, wherein an estimated value of the fuel temperature in the stopped state of the engine is updated on the basis of a lapse of time since the start of the stopped state and an ambient temperature or on the basis of information having correlations with the lapse of time and the ambient temperature. 14. A fuel-temperature estimation apparatus having a fuel-temperature estimation means for estimating a fuel temperature of a fuel tank employed in an engine in a stopped state of the engine, wherein an estimated value of the fuel temperature in the stopped state of the engine is updated on the basis of a lapse of time since the start of the stopped state or information having a correlation with the lapse of time; and wherein the fuel-temperature estimation means has a correction means for correcting a present fuel-temperature estimated value on the basis of an amount of residual fuel left in the fuel tank. 15. A fuel-temperature estimation apparatus having an engine-running-state fuel-temperature estimation apparatus including a fuel-temperature estimation apparatus for estimating a fuel temperature of a fuel tank employed in an engine in a running state of the engine, the fuel-temperature estimation apparatus comprising: a fuel-temperature-increase estimation means for estimating an increase in fuel temperature in the fuel tank on the basis of an operating condition in the running state of the engine; and a fuel-temperature-decrease estimation means for estimating a decrease in fuel temperature in the fuel tank on the basis of a vehicle speed and/or an intake-air temperature or on the basis of information having correlations with the vehicle speed and/or the intake-air temperature, wherein a present estimated value of the fuel temperature is updated on the basis of a fuel-temperature increase estimated by the fuel-temperature-increase estimation means and a fuel-temperature decrease estimated by the fuel-temperature-decrease estimation means; an engine-stopped-state fuel-temperature estimation apparatus including a fuel-temperature estimation apparatus having a fuel-temperature estimation means for estimating a fuel temperature of a fuel tank employed in an engine in a stopped state of the engine, wherein an estimated value of the fuel temperature in the stopped state of the engine is updated on the basis of a lapse of time since the start of the stopped state or information having a correlation with the lapse of time. 16. A fuel-temperature estimation apparatus according to claim 15, wherein, in a stopped state of the engine, the fuel-temperature estimation means of the engine-stopped-state fuel-temperature estimation apparatus updates an engine-stopped-state fuel-temperature estimated value by setting an initial value of the engine-stopped-state fuel-temperature estimated value at an engine-running-state fuel-temperature estimated value estimated by the engine-running-state fuel-temperature estimation apparatus's fuel-temperature-increase estimation means or fuel-temperature-decrease estimation means. 17. A leak-check apparatus comprising: a fuel-temperature estimation apparatus having a fuel-temperature estimation means for estimating a fuel temperature of a fuel tank employed in an engine in a stopped state of the engine, wherein an estimated value of the fuel temperature in the stopped state of the engine is updated on the basis of a lapse of time since the start of the stopped state or information having a correlation with the lapse of time; and a leak-check means for checking a leak in a fuel-vapor-processing system of an engine in a stopped state of the engine, wherein the leak-check means uses a fuel-temperature estimated value estimated by the fuel-temperature estimation apparatus as a fuel-check execution condition determination parameter and/or a leak-check parameter. 18. A leak-check apparatus according to claim 17, wherein, in a stopped state of the engine, the leak-check means checks a leak in the fuel-vapor-processing system on the basis of a relation between variations in fuel-temperature estimated value estimated by the fuel-temperature estimation apparatus and variations in fuel-tank internal pressure. 19. A leak-check apparatus according to claim 18, wherein, in a stopped state of the engine, the leak-check means carries out leak-check processing to check a leak in the fuel-vapor-processing system on the basis of the variation in fuel-tank internal pressure over a period beginning at the start of the leak-check processing and ending at a time the fuel-temperature estimated value estimated by the fuel-temperature estimation apparatus becomes equal to or smaller than a predetermined value. 20. A leak-check apparatus according to claim 17, wherein, as one of fuel-check execution conditions, a fuel-temperature estimated value estimated by the fuel-temperature estimation apparatus right after or right before the start of a stopped state of the engine is required to be greater than a predetermined value. 21. A method of estimating a fuel temperature of a fuel tank employed in an engine in a running state of the engine, the method comprising: estimating an increase in fuel temperature in the fuel tank on the basis of an operating condition in the running state of the engine; and estimating a decrease in fuel temperature in the fuel tank on the basis of a vehicle speed and/or an intake-air temperature or on the basis of information having correlations with the vehicle speed and/or the intake-air temperature; wherein a present estimated value of the fuel temperature is updated on the basis of the estimated increase in fuel temperature in the fuel tank and the estimated decrease in fuel temperature in the fuel tank. 22. A method according to claim 21, wherein the estimated increase in fuel temperature is caused by exhaust-gas heat dissipated to the fuel tank. 23. A method according to claim 21, wherein the estimated increase in fuel temperature is estimated on the basis of the engine's revolution speed and/or load. 24. A method according to claim 21, wherein: the method is applied to a fuel system in which an excessive portion of fuel supplied by a fuel pump from the fuel tank to a fuel injection valve is returned to the fuel tank; and the increase in fuel temperature is estimated by estimating a fuel-temperature increase which is caused by exhaust-gas heat dissipated to the fuel tank as well as a fuel-temperature increase which is caused by the excessive portion returned from the fuel injection valve to the fuel tank. 25. A method according to claim 21 wherein: the method is applied to a fuel system with a configuration including a fuel pump installed in the fuel tank; and a fuel-temperature increase caused by heat dissipated by the fuel pump in the fuel tank is estimated. 26. A method according to claim 21, further comprising correcting a present fuel-temperature estimated value on the basis of an amount of residual fuel left in the fuel tank and/or a previous fuel-temperature estimated value. 27. A method according to claim 21, wherein a fuel-temperature initial value is estimated at the present start of the engine on the basis of a fuel-temperature estimated value estimated in a previous stopped state of the engine, a lapse of time since the previous stopped state of the engine till the present start of the engine and an ambient temperature or information having a correlation with the ambient temperature. 28. A method of performing a leak-check, the method comprising: a method of estimation fuel temperature apparatus according to claim 21, and checking a leak in an fuel-vapor-processing system of an engine in a running state of the engine, wherein a fuel-temperature estimated value estimated by the fuel-temperature estimation method is used as a fuel-check execution condition determination parameter and/or a leak-check parameter. 29. A method according to claim 28, wherein, as one of fuel-check execution conditions, a fuel-temperature estimated value estimated by the fuel-temperature estimation method is required to be not greater than a predetermined value. 30. A method comprising estimating a fuel temperature of a fuel tank employed in an engine in a stopped state of the engine without using a temperature sensor, wherein an estimated value of the fuel temperature in the stopped state of the engine is updated on the basis of a lapse of time since the start of the stopped state or information having a correlation with the lapse of time. 31. A method according to claim 30, wherein an estimated value of the fuel temperature in the stopped state of the engine is updated on the basis of a lapse of time since the start of the stopped state and an ambient temperature or on the basis of information having correlations with the lapse of time and the ambient temperature. 32. A method comprising: estimating a fuel temperature of a fuel tank employed in an engine in a stopped state of the engine, wherein an estimated value of the fuel temperature in the stopped state of the engine is updated on the basis of a lapse of time since the start of the stopped state or information having a correlation with the lapse of time; and correcting a present fuel-temperature estimated value on the basis of an amount of residual fuel left in the fuel tank. 33. A method of performing a leak-check, the method comprising: estimating a fuel temperature of a fuel tank employed in an engine in a stopped state of the engine, wherein an estimated value of the fuel temperature in the stopped state of the engine is updated on the basis of a lapse of time since the start of the stopped state or information having a correlation with the lapse of time; and checking a leak in a fuel-vapor-processing system of an engine in a stopped state of the engine, wherein a fuel-temperature estimated value is used as a fuel-check execution condition determination parameter and/or a leak-check parameter. 34. A method according to claim 33, wherein, in a stopped state of the engine, a leak in the fuel-vapor-processing system is checked on the basis of a relation between variations in fuel-temperature estimated value and variations in fuel-tank internal pressure. 35. A method according to claim 34, wherein, in a stopped state of the engine, leak-check processing is performed to check a leak in the fuel-vapor-processing system on the basis of the variation in fuel-tank internal pressure over a period beginning at the start of the leak-check processing and ending at a time the fuel-temperature estimated value becomes equal to or smaller than a predetermined value. 36. A method according to claim 33, wherein, as one of fuel-check execution conditions, a fuel-temperature estimated value estimated right after or right before the start of a stopped state of the engine is required to be greater than a predetermined value.