GB1466253A - Control circuits for manifold heaters - Google Patents

Abstract

1466253 Engine starting systems CAV Ltd 12 March 1974 [11 May 1973] 22474/73 Heading H2H A circuit for supplying a manifold heater 22 in a compression ignition engine comprises a switch 14 which when closed completes a circuit to the heater and a circuit to a delay device 18, and a further switch 21 operated by the delay device after a first delay period for completing a circuit to the heater independently of the switch 14, the delay device serving when the switch 14 is opened to maintain the further switch 21 operated for a second delay period after which the circuit to the heater is broken. The circuit is supplied by a battery 11 and when the movable contact of the switch 14 is engaged with a contact 16, the delay device 18 in the form of a heater begins to heat up. At the end of the first delay period, the heater causes both the switch 21 to changeover so that the manifold heater remains energized directly from the battery and a switch 19 to close so that a starter motor 17 is energized. When the engine starts the switch 14 is returned to its central position thus de-energizing the heater 18. At the end of the second delay period the heater 18 has cooled sufficiently to enable the switches 19, 21 to open thereby de-energizing the manifold heater. A contact 15 enables a warm engine to be started without energizing the manifold heater. In a modification, the switch 19 is replaced by a thyristor and the switch 21 controls a transistor which supplies current to the manifold heater.