Nissan Motor Company Limited

Takane Hayashi

Takeshi Tsuyuki

Shigeaki Kakizaki

Hiroya Ishii

Masato Kobayashi

Hiroshi Katoh

Yousuke Sakayori

A thermostat failure detection device sequentially calculates a normal-time minimum water temperature on an assumption that a thermostat is normal and an internal combustion engine is operated in a state where the engine water temperature is less likely to rise, sequentially calculates a failure-time maximum water temperature on an assumption that the thermostat is in a stuck-open failure state and the internal combustion engine is operated in a state where the engine water temperature is likely to rise, determines the failure of the thermostat if the engine water temperature is lower than the normal-time minimum water temperature, determines the normality of the thermostat if the engine water temperature is higher than the failure-time maximum water temperature, and determines neither the normality nor the failure if the engine water temperature is between the normal-time minimum water temperature and the failure-time maximum water temperature.

Thermostat failure detection device and thermostat failure detection method

A fuel vapor purge system is configured to execute a highly accurate leak diagnosis with respect to a fuel vapor leak. After the engine is stopped, the temperature of the fuel vapor rises temporarily and then decreases until it reaches the outside ambient temperature. During this period, the purge line is closed off and a purge line pressure decreasing rate is detected when the purge line pressure is slightly above atmospheric pressure. The detected purge line pressure decreasing rate is then compared to a threshold value. The purge system is diagnosed as 'normal' if the purge line pressure decreasing rate is equal to or larger than the threshold value and as 'leaking' if the purge line pressure decreasing rate is less than the threshold value.

Fuel vapor treatment system with leak diagnosing

A fuel vapor purge system is configured to execute a highly accurate leak diagnosis with respect to a fuel vapor leak. After the engine is stopped, the temperature of the fuel vapor rises temporarily and then decreases until it reaches the outside ambient temperature. During this period, the purge line is closed off and a minimum value reached by the purge line pressure is detected. The difference between the minimum value of the purge line pressure and the atmospheric pressure is compared to a threshold value. The purge system is diagnosed as 'normal' if the difference is equal to or larger than the threshold value and a 'leaking' if the difference is less than the threshold value.

Disclosed is a leak detecting device for a fuel vapor treatment unit that purges a vapor gas generated through evaporation of fuel in a fuel tank () into an intake system () of an engine (). The leak detecting device includes a valve () that can selectively seal the fuel vapor treatment unit; a pressure detecting sensor () that detects a pressure in the fuel vapor treatment unit; and a controller (). The controller () is programmed to: issue a command to close the valve () with a view to sealing the fuel vapor treatment unit during stoppage of the engine (); calculate deviation amounts (P&#x2212;P) of the detected pressures during stoppage of the engine () after the fuel vapor treatment unit has been sealed; integrate absolute values (|P&#x2212;P|) of the deviation amounts, and determine, based on an integrated value (s), whether or not there is a leak occurring in the fuel vapor treatment unit.

Leak detecting device for fuel vapor treatment unit

Fuel vapor adsorbed by activated carbon in a canister is introduced to an engine by a manifold vacuum in an intake air passage and burnt. The controller estimates the fuel amount desorbed from the canister during purge, using a canister model (physical model) comprising an equation which computes the adsorption amount and an equation which computes the desorption amount from the adsorption amount and purge rate. An injection pulse width output to injectors is corrected to reduce an air-fuel ratio fluctuation due to the supply of this desorbed fuel to the engine

Fuel vapor emission control device for an engine

A fuel vapor emission control device of an engine includes a canister which adsorbs fuel vapor generated in a fuel tank , and a purge valve which opens and closes a pipe connecting the canister and an intake passage of the engine . A controller sets a target purge rate according to a difference between a target air-fuel ratio feedback deviation and an actual air-fuel ratio feedback deviation during purge, and drives the purge valve so that the target purge rate is achieved.

A fuel property detecting system comprises a control unit coupled to a fuel injector and an air-fuel ratio sensor. The control unit is arranged to sample data of a response wave-form of an exhaust air-fuel ratio in response to an injected fuel quantity at a transient period, to identify a plant model as to fuel in use by controlling a parameter of a previously constructed plant model on the basis of the input and output data so as to decrease a prediction error between the plant model and a norm model, to calculate a cutoff frequency of the identified plant model, and to estimate a fuel property of the fuel in use from the calculated cutoff frequency of the identified plant model and data previous stored in the control unit.

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Yokohama, Japan

Takane Hayashi