Hybrid vehicle

A parallel-type hybrid vehicle, comprising:

• a gasoline engine designed in such a manner that a geometric compression ratio ε is set to a high compression ratio of not smaller than 13 but not larger than 18, the gasoline engine having specific fuel consumption characteristics such that an engine output at specific fuel consumption higher than minimum specific fuel consumption by 15 to 20% of the minimum specific fuel consumption is only in an operating range where the engine output is not larger than 10% of maximum output of the engine, and the fuel consumption is decreased sharply from 0% to 10% of maximum output of the engine by setting a spark ignition mode, in which an excess air ratio λ the engine is 1, and a fuel-air mixture in a combustion chamber is ignited by driving of an ignition plug in a high load operating range;
• and by setting a compression ignition mode, in which the excess air ratio λ is from 2 to 8, and the fuel-air mixture in the combustion chamber is compressed and ignited in a medium load operating range and in a low load operating range;
• a switched reluctance motor for use when the vehicle runs, the motor being a regenerative motor, the motor having characteristics such that motor efficiency is between 90% and 100% at a rotational speed of 75% of a maximum rotational speed of the motor when motor load is between 10% and 100% of a maximum load of the motor;
• a battery which supplies electric power for operating the motor as an electric motor, the battery being capable of charging electric power regenerated by the motor;
• and
• a transmission which transmits power of the engine to a wheel drive shaft, wherein
• the motor is coupled to the wheel drive shaft without being coupled to the transmission.

A parallel-type hybrid vehicle, comprising:

• a gasoline engine designed in such a manner that a geometric compression ratio ε is set to a high compression ratio of not smaller than 13 but not larger than 18, the gasoline engine having specific fuel consumption characteristics such that an engine output at specific fuel consumption higher than minimum specific fuel consumption by 15 to 20% of the minimum specific fuel consumption is only in an operating range where the engine output is not larger than 10% of maximum output of the engine, and the fuel consumption is decreased sharply from 0% to 10% of maximum output of the engine by setting a spark ignition mode, in which an excess air ratio λ of the engine is 1, and a fuel-air mixture in a combustion chamber is ignited by driving of an ignition plug in a high load operating range;
• and by setting a compression ignition mode, in which the excess air ratio λ is from 2 to 8, and the fuel-air mixture in the combustion chamber is compressed and ignited in a medium load operating range and in a low load operating range;
• a switched reluctance motor for use when the vehicle runs, the motor having characteristics such that motor efficiency is between 90% and 100% at a rotational speed of 75% of a maximum rotational speed of the motor when motor load is between 10% and 100% of a maximum load of the motor;
• a battery which supplies electric power for operating the motor as an electric motor, the battery being capable of charging electric power regenerated by the motor;
• a transmission which transmits power of the engine to a wheel drive shaft;
• and
• a control device which controls driving of the engine and driving of the motor, wherein
• the motor is coupled to the wheel drive shaft without being coupled to the transmission, and
• the control device calculates a target output of the engine in accordance with a running state of the hybrid vehicle, and controls to stop the engine and to cause the hybrid vehicle to run by the motor in a low load operating range where the target output is not larger than 10% of the maximum output of the engine, and in an operating range other than the operating range where the target output is not larger than 10% of the maximum output, controls to cause the hybrid vehicle to run by the engine, and causes the motor to perform solely a regenerating operation.