Abstract: Since the starting of an engine at a lower temperature is troublesome, the temperature of the engine is measured by a sensor. When the measured temperature is lower than a reference temperature, the pump is first switched on for circulating a thermal medium. This permits the thermal medium to transfer heat of the hot water stored in a hot water storage tank to the engine, hence warming the engine, decreasing the viscosity of the oil, and preventing the generation of dew in the engine to ease the start up of the engine.

Abstract: A means for eliminating a frozen or near frozen state in a drain of the condensed water generated by the action of an exhaust gas heat exchanger is provided. The condensed water separated from the exhaust gas in a silencer (31) is passed through a waste water trap provided with the joint (34) and discharged to the outside. The joint (34) also has a passage provided therein for circulating a heat transfer medium through an externally (separately) installed heat exchanger (52A). When the engine (2) is started, it is judged, based on the temperature of the waste water trap or the water measured by a sensor (53), whether the frozen state is present or not. When it is judged that the frozen state is present, a water pump 10 is switched on for circulating the heat transfer medium through the waste water trap.

Abstract: In a single-cylinder 4-cycle engine including an oxygen concentration sensor provided at a location upstream of an exhaust emission control catalyst, the influence of pulsation of the exhaust gas is eliminated to enhance the detection accuracy by detecting of the concentration of oxygen in the exhaust gas. A first pulse generator generates a pair of pulse signals a and b per one rotation of a crankshaft, and a second pulse generator generates pulse signals c and d at every very small angle of rotation of the crankshaft. The angular speed of the crankshaft is detected from the interval of the pulse signals c and d. The pulse signal output a when the angular speed is smaller is determined as being the output during a compression stroke, and is used as an ignition signal a1. The pulse signal output a when the angular speed is larger is determined as being the output during an exhaust stroke, and is used as an oxygen concentration detecting signal a2.

Abstract: A fuel feed device for a gas engine includes a thermally insulated cartridge case for receiving therein a disposable gas cylinder or cartridge. The cartridge case has a built-in temperature sensor for detecting the temperature of the gas cartridge, and a built-in electric heater for heating the gas cartridge. The electric heater is controlled such that the temperature detected by the temperature sensor is kept within a predetermined temperature range. A working machine driven by the gas engine is also disclosed.