Mazda Motor Corporation

Seiji Makimoto

Tetsushi Hosokai

Naoyuki Noguchi

Eiji Kanehisa

Futoshi Nishioka

Shingo Shigihama

Yoshimi Yamamoto

Masaaki Tamekiyo

Kazuki Murakami

The present invention provides a malfunction diagnostic apparatus for an evaporated fuel purge system in an internal combustion engine, capable of detecting abnormalities such as looseness or clogging in the purge line between a purge valve and an engine intake passage. An electric pump is turned on when a purge valve is in a closed state and a selector valve is in an open state. After the lapse of a given time period Tref, a load-current initial value I of the electric pump is detected at the moment switching the selector valve to a closed state. After the lapse of a given time period Tpump, the purge valve is switched to an open state, and a load-current final value at the moment after the lapse of a given time period Tpurge. As in the curve A, when a load current final value I is equal to or less than the load current initial value I , it is determined that the gaseous communication state in the purge line between the purge valve and the intake passage is normal. On the other hand, as in the curves B and C, when load current final values I and I are greater than the load current initial value I , it is determined that the gaseous communication state is abnormal. In case of abnormality, when the difference I &minus;I therebetween is less than a gaseous-communication-state determination threshold f as in the curve B, it is determined that the purge line is in an open-air state. If the difference I &minus;I is equal to or greater than the gaseous-communication-state determination threshold f as in the curve C, it is determined that the purge line is in a clogging state.

Malfunction diagnostic apparatus for evaporated fuel purge system

The invention relates to an apparatus for diagnosing thermostat trouble in an engine cooling system comprising a thermostat which works to open a valve to make a cooling water flow through a radiator when the cooling water temperature for an engine becomes more than a predetermined temperature, or to close the valve to make the cooling water bypass a radiator when this temperature becomes less than the predetermined temperature. The apparatus comprises means for calculating a radiation heat amount from a radiator received by the cooling water for the engine and means for determining whether the thermostat trouble has occurred based on the radiation heat amount calculated by the means for calculating the radiation heat amount.

Thermostat trouble diagnosis system in an engine cooling system

In a vehicle provided with an automatic transmission, gear-shifting shock is suppressed by changing the engine output power in response to a gear-shifting. The change in the engine output power is terminated when the actual engine speed reaches a completion decision engine speed, which is determined so that it corresponds to the time when the gear-shifting is completed, which is based on the fact that the engine speed changes according to a certain characteristic curve during the gear-shifting. The engine speed at which the gear-shifting is actually completed is detected for each gear-shifting according to the change in the rotational speed of the engine during the gear-shifting, and the completion decision rotational speed for each gear-shifting is set through learning on the basis of the preceding engine speed at which the gear shifting was actually completed.

Method of suppressing gear-shifting shock in an automatic-transmission

A vehicle is provided with an engine and an automatic transmission having a lockup mechanism which engages and disengages to directly connect and disconnect input and output shafts of a torque converter of the automatic transmission to and from each other. A control system for such a vehicle has a deceleration detecting circuit which detects that the engine is decelerating based on the engine speed and a throttle opening, and a lockup mechanism control circuit which causes the lockup mechanism to engage when the engine is decelerating and permits the same to disengage when the deceleration of the engine finishes. The control system inhibits the lockup mechanism control circuit from causing the lockup mechanism to disengage in a period in which the engine speed can temporarily fall because of the automatic transmission's shifting into neutral in the process of a downshift.

Control system for vehicle provided with automatic transmission

A control system for a vehicle with an automatic transmission in which the gear ratio is automatically changed in accordance with the operating condition of the vehicle includes a control means set for at least a first range if air-fuel ratios to be determined in accordance with engine speed and a second range of air-fuel ratios for controlling the air-fuel ratio of the engine to enrich a fuel mixture more than in the first range of air-fuel ratios. A shift control system has a first shift characteristic setting means for setting a first shift characteristic, and a second shift characteristic setting means for setting a second shift characteristic such that an upshift is effected in a higher vehicle speed range than that in the first shift characteristic. A characteristic changing means selects the first shift characteristic during ordinary driving (i.e. non-power driving) and the second shift characteristic during a specific operating condition. An air-fuel ratio changing means expands the first range of air-fuel ratios toward the high-speed side of engine operation when the second shift characteristic has been selected by the characteristic changing means to narrow the second range of air-fuel ratios. Thus, when an acceleration force is demanded during ordinary driving, the vehicle is driven to gain a sufficient acceleration force, and at the same time the air-fuel ratio enrichment control is restrained to control the worsening of fuel economy.

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Aki-gun, Japan

Seiji Makimoto