Engine starter having starter motor
AssigneesDenso Corporation, Nippon Soken, Inc.
InventorsTakashi Senda, Masahiko Osada, Shinji Usami, Tsutomu Nakamura, Masaru Kamiya, Yoshikazu Yokochi
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Abstract
An engine starter includes a starter motor which has an armature, a series-wound field coil and a parallel-wound field coil and a short-circuiting unit for short-circuiting the series-wound field coil under a predetermined engine starting condition. The series-wound field coil has a suitable current limiting resistance. The short-circuiting unit short-circuits the series-wound field coil after a crankshaft of an engine passes a first top dead center of an engine.
Claims36
1 An engine starter for rotating a reciprocating engine having a plurality of top dead centers comprising:
- a starter motor energized by a battery, said starter motor including an armature, a series-wound first field coil having a predetermined current limiting resistance and a parallel-wound second field coil;
- and
- a short-circuiting means for short-circuiting said first field coil after said starter motor rotates the engine to surmount a first top dead center;
- wherein said current limiting resistance limits main current supplied to said armature to an amount to provide a sufficient torque of the starter motor to surmount the first top dead center but to prevent terminal voltage of the battery from dropping to a predetermined minimum level.
The engine starter according to claim 1,
- wherein said short-circuiting means short-circuits said first field coil when the main current decreases to a predetermined level.
The engine starter according to claim 1,
- wherein said short-circuit means short-circuits said first field coil when a predetermined time has passed after the main current is supplied to the armature.
The engine starter according to claim 1,
- wherein:
- said first field coil comprises a plurality of magnetic pole cores and a plurality of series-connected first coil-sections respectively mounted on said pole cores;
- and
- said second field coil comprises a plurality of parallel-wound second coil sections connected in parallel with each other and a series-wound second coil section respectively mounted on said pole cores.
The engine starter according to claim 1,
- wherein:
- said first field coil comprises a plurality of magnetic pole cores and a plurality of first coil-sections respectively mounted on said pole cores to form a parallel circuit of said series-connected first coil sections;
- and
- said second field coil comprises a plurality of parallel-connected second coil sections respectively mounted on said pole cores and respectively connected in series to said parallel circuit.
The engine starter according to claim 1,
- wherein said second field coil is connected in series to said first field coil and in parallel with said armature.
An engine starter driven by a battery comprising:
- a power supply line having a main switch;
- a starter motor including an armature, a series-wound field coil and a parallel-wound field coil, said armature, said series-wound field coil being connected to the battery via said power supply line when said main switch is closed;
- field current control means for controlling current supplied to said parallel-wound field coil;
- and
- voltage-drop control means, connected in series to said power line, for controlling voltage drop of the battery to be less than 2 volts when said main switch is closed to supply current to said armature,
- wherein said starter motor is arranged to have a torque to surmount a first top dead center when voltage of the battery decreases by 2 volts from its normal voltage.
The engine starter according to any one of claims, characterized in that said field current control means controls field current supplied to said parallel-wound field coil according to a change in an engine load so that voltage change can be controlled within 0.3 volts.
Dependencies are inferred from the claim text.