Abstract: A spark ignited internal combustion engine is disclosed in which at least one of the inlet tracts of the engine has an optical knock sensor in the form of an infra-red temperature sensor located in it. The infra-red temperature sensor is positioned to sense by viewing past an inlet valve means associated with the respective inlet tract at least during part of the induction stroke of the respective cylinder of the engine the temperature of the upper surface of the respective piston. A control system for such an engine is also disclosed in which the output from the infra-red temperature sensor is supplied to an electronic control unit. The electronic control unit operates so as to adjust the ingition timing of the engine in response to the signal received from the infra-red temperature sensor.

Abstract: In a multiplex system for automotive vehicles, battery (+V) current is supplied to each load (70, 71) connected to a non-intelligent slave unit (20) via a power switch (TR) in the slave controlled by a capacitor (CT) which is charged or discharged in an assigned time slot by high or low voltage (A,C) applied on a low current signal line from a remote intelligent unit (10). If a load (70, 71) goes open-circuit then a voltage source (TR1, Z1) in the slave provides low current via a resistor (R2, R3) and the forward direction of a zener diode Z to charge the capacitor CT to an intermediate voltage which is detected at the remote intelligent unit (10) during an assigned load driving time slot.

Abstract: In a multiplex system for automotive vehicles, battery (+V) current is supplied to a load (70) connected to a non-intelligent slave unit (20) via a power switch (TR) in the slave controlled by a capacitor (CT) which is charged or discharged in an assigned time slot by high or low drive voltage applied on a low current signal line (42) from a remote intelligent unit (10). If the load (70) goes short-circuit then a thyristor (TH) adjacent the power switch (TR) turns on to turn off the power switch (TR) and provide a discharge path for the capacitor (CT) via the load (70), this discharged condition being detected at the remote intelligent unit during an assigned load driving time slot. Thus a dedicated extra channel (time slot) is not required at the slave unit for short-circuit testing of the load.

Abstract: A manually operable electrical toggle switch (60) is connected in a low current signalling link (40) via a non-intelligent slave unit (20) in a time slot assignment multiplex system for automotive vehicles to an intelligent master unit (10) which in response to a binary input from the switch (60) provides an output signal on such a signalling link (40) to control high current to a load (70) connected to a slave unit (20). The switch (60) has conductive plastics contacts (63) to avoid oxide corrosion problems and may be all plastics. The binary input from the switch (60) is provided by one of two resistances (R2or R3) which are distinguishable in the master unit (10) from each other and from both a short circuit and an open circuit in the signal line (42) of the link (40).