Abstract: When a driver performs a steering operation with a small steering angle when a vehicle is stopped, a viscous clutch of a viscous heater is turned on after setting an idling rotational speed of an engine to a high value to prevent an engine stall. Further, when a driver performs the steering operation with a large steering angle when the vehicle is stopped, the viscous clutch is not turned on so that the viscous heater is not operated, thereby greatly reducing a driving load applied to the engine and a V-belt thereof.

Abstract: According to the present invention, when a vehicle speed is less than a set value (e.g., 40 km/h) and a throttle opening degree is more than a set value, it is determined that the vehicle is accelerating, and a viscous clutch is turned off. Therefore, a shearing operation of high-viscosity fluid by a rotor of a viscous heater is not performed. In this way, a driving load applied to an engine is reduced, so that an accelerating state suitable for an intention of a driver can be obtained. Further, when the vehicle speed is more than a set value (e.g., 40 km/h) and an engine rotational speed is more than a set value (e.g., 3500 r.p.m.), the viscous clutch is turned off, and a driving load applied to the engine and a V-belt is reduced.

Abstract: A heating apparatus for a vehicle includes a heat exchanger for implementing heat exchange between coolant which has cooled an engine and air directed to a vehicle interior to heat the vehicle interior. A viscous heater has a rotor and a heating chamber containing viscous fluid. The rotor rotates when being subjected to rotational power of the engine. The viscous fluid is subjected to a shear force and is heated when the rotor is subjected to the rotational power. The viscous heater heats the coolant fed to the heat exchanger as the viscous fluid in the heating chamber is heated. A clutch is operative for selectively permitting and inhibiting transmission of the rotational power from the engine to the rotor. A belt transmission device connects the engine and the clutch. A physical quantity detecting device is operative for detecting a physical quantity related to a rotational speed of the rotor.

Abstract: In a heating apparatus according to the present invention, when a temperature of cooling water in a cooling water circuit is equal to a set cooling water temperature or less, a viscous clutch is turned on to operate a viscous heater disposed in the cooling water circuit, for maintaining the temperature of the cooling water in the cooling water circuit at a predetermined value. A shaft of the viscous heater is rotated by a water-cooled engine through a belt transmitting mechanism and the viscous clutch. The set cooling water temperature is increased in accordance with an increase of a target air temperature calculated based on a set temperature, an inside air temperature, an outside air temperature, and a sunlight amount to optimize a used condition of the viscous heater.