An engine cooling system for cooling an internal combustion engine on a motor vehicle such as an automobile, for example, includes an engine stop detector for detecting when the operation of the engine is stopped, an oil temperature detector for detecting the temperature of lubricating oil in the engine, a controller responsive to signals from the engine stop detector and the oil temperature detector for ascertaining whether the temperature of the lubricating oil at the time the engine is stopped is in excess of a reference temperature or not and for issuing a control signal when the temperature of the lubricating oil exceeds the reference temperature, and a fan driver for driving an engine cooling fan in response to the control signal from the controller.

The invention is directed to a control apparatus cooling system which includes a control apparatus arrangement for an internal combustion engine. The control apparatus arrangement is set into operation by an ignition contact signal. The control apparatus arrangement is cooled with the aid of a coolant loop which has a pump motor. A self-holding circuit is provided in the control apparatus arrangement and supplies the pump motor and a voltage stabilization with voltage to drive a microcomputer as soon as the ignition contact signal appears. The cooling of the control apparatus arrangement is not terminated immediately when the ignition contact signal ceases; instead, the pump motor continues to run until it is assured that components having conventional temperature resistance cannot become damaged in the control apparatus arrangement by overheating because of stored heat. The microcomputer determines when the switch-off condition is satisfied. This cooling system affords the advantage that components of conventional temperature resistance can be utilized in the control apparatus arrangement. Furthermore, the advantage is afforded that even after the ignition contact signal ceases, the microcomputer can still conduct self-diagnostic procedures which in conventional systems can only be carried out when the engine is started which then leads to a delay when starting the engine.

Safety apparatus for a motor vehicle electric consumer having a temperature-dependent internal resistance, which includes a temperature indicating circuit for providing a signal which accurately indicates the consumer temperature to a threshold switch which actuates a switching device to interrupt current flow through the consumer whenever the consumer temperature exceeds a predetermined maximum value. The temperature indicating circuit either may be a consumer resistance measuring circuit such as a bridge circuit including the consumer in one leg thereof, or may be a consumer temperature replicating circuit, connected in parallel with the consumer, such as a special RC network. The switching device either may be a switch connected in series with the consumer, or a switch connected in parallel with the consumer, in which case the apparatus also includes an overcurrent device connected in series with the parallel combination of the switch and the consumer.

A solid-state, multistage temperature controller for automatically controlling the operation of fans to maintain the temperature of an associated engine within preselected limits.

A radiator fan controller is provided for lowering temperature in an engine compartment by positively scavenging it if the compartment is hot enough to require scavenging. Coolant temperature Tw is compared with a high temperature determining threshold value TWS. In the case of Tw<TWS, vehicle speed VSP is compared with a low speed determining threshold value VSPS. In the case of VSP<VSPS, intake air temperature Ta is compared with an intake air temperature determining threshold value TAS. In the case of VSP<VSPS and Ta.gtoreq.TAS, it is determined that scavenging by running wind cannot lower the temperature and a radiator fan should be forcibly turned on. As a result, the engine compartment is forcibly scavenged by blowing air from the radiator fan to prevent respective components from suffering thermal damage caused by excessively rising temperature.