Electrical switches for use in starter motors for i.c. engines

Abstract

Abstract An electrical switch is for use in an internal combustion engine starting mechanism of the kind including a starter motor, a pinion driven by the starter motor and engageable with a toothed wheel on the engine, and a solenoid for moving the pinion into engagement with the toothed wheel, the solenoid including an armature having an inner part for moving the pinion and an outer part coupled to the inner part. A switch of this kind includes a housing and first, second and third fixed contacts secured in the housing in spaced relationship and lying in a common plane. A movable carrier is mounted for movement in a direction at right angles to the plane of the fixed contacts and a conductive bridging piece is resiliently mounted on the carrier and is urged to lie in a plane parallel with the plane of the fixed contacts. A sleeve slidably mounted in the housing is engaged at one end with the carrier and projects at its other end from the housing for engagement with the outer part of the armature. A push rod is slidable within the sleeve and projects at one end from the sleeve for engagement by the inner part of the armature, resilient means urging the sleeve and the push rod outwardly. A movable latch member is movable by the push rod and is resiliently urged to a position wherein it projects above the plane of the fixed contacts to prevent the bridging piece engaging the third fixed contact during movement of the carrier towards the fixed contacts. The arrangement is such that in use upon energization of the solenoid the outer part of the armature moves the carrier through the sleeve towards the fixed contacts, the bridging piece engaging the latch member and thus being tilted relative to the carrier during further movement of the carrier. The bridging piece in its tilted condition engages the first and second fixed contacts to complete a first circuit of the starter motor and the latch member is then moved by the push rod when the pinion of the starter motor is fully engaged with the toothed wheel of the engine to permit the bridging piece to return to its original position with respect to the carrier so as to engage the third fixed contact to complete a second circuit of the starter motor. The second circuit when completed causes energization of the starter motor at a full torque value while completion of the first circuit causes energization of the starter motor at a reduced torque value.

Inventors

• 👤 Ronald Wilson

Bibliographic Details