A starter that can improve heat radiation efficiency and improve the brush life. An upper movable contact is set on the end of a plunger shaft fixed on a plunger. The upper movable contact moves together with the plunger due to the attraction force of an attraction coil and contacts a fixed contact set to face the upper movable contact and which is connected to a terminal bolt. The upper movable contact is directly installed and integrated with a brush, so the heat generated by the bush is efficiently dissipated through the brush, upper movable contact, fixed contact and terminal bolt out the battery cable connected to the terminal bolt.
A starter motor has an armature, a commutator and brushes slidably supported by a brush holder, and a magnet switch controls motor operation. A switch supporting member supports the magnet switch and an energization control unit accommodating a bimetal switch having a contact therein. The energization control unit opens its inner contact to shut off the current carried to a magnet switch coil when the temperature of heat transferred via switch supporting member, i.e., the heat of the coil transferred via brushes and a switch yoke, reaches a predetermined temperature, thereby stopping motor operation.
In a coaxial engine starter comprising a pinion connected to the output shaft which is driven by an electric motor, via a helical spline, a switch unit for selectively closing a power supply line to the electric motor, and a solenoid device consisting of an annular armature and an annular energization coil surrounding the output shaft to axially drive the pinion and a moveable contact of the switch unit in the axial direction, the energization coil is disposed between the electric motor and the pinion with a commutator of the electric motor facing the energization coil, and a pigtail for one of the brushes is directly connected to the moveable contact. Also, the contacts of the switch unit are placed between a pair of adjacent brushes of the commutator. In particular, by separating the part of the armature for driving the moveable contact from the part of the armature for driving the pinion, the stroke of the moveable contact can be minimized, and the stress acing upon the connecting part of the pigtail upon movement of the contact can be minimized.
A starter for cranking an internal combustion engine is composed of an electric motor, an output shaft driven by the motor, a pinion gear coupled to the output shaft, and a magnetic switch. Electric power is supplied to the motor from an on-board battery through a switch, a movable contact of which is driven by the magnetic switch. The movable contact is connected to a brush lead wire via a connection formed by soft-soldering. The connection formed by the soft-soldering is positioned close to the commutator and covered with an end cover, so that the temperature of the connection becomes higher than other places in the starter. The connection easily melts away to thereby shut off power supply to the motor when its temperature becomes unusually high, and thereby the starter is protected from overheating.
In a coaxial engine starter comprising a pinion (6) connected to the output shaft (4) which is driven by an electric motor (3), via a helical spline (19), a switch unit (7) for selectively closing a power supply line to the electric motor, and a solenoid device (9) consisting of an annular armature and an annular energization coil surrounding the output shaft to axially drive the pinion and a moveable contact of the switch unit in the axial direction, the switch is adapted to be closed before the pinion is actuated by the solenoid device. Therefore, the output requirement for the solenoid device can be reduced as opposed to the conventional starter in which the pinion is actuated strictly by the solenoid device, and the size of the engine starter can be reduced.
A magnetic switch including a plunger is disposed on a rear end side of an armature via an end frame so that a moving direction of the plunger is perpendicular to an axial direction of the armature, and is fixed to the end frame by a fixing member. The fixing member is composed of a semi-circular portion having a shape corresponding to an outer circumference of the magnetic switch and arm portions extending from the semi-circular portion. Further, each of the arm portions has a deflection portion at an end thereof on a semi-circular portion side, and a claw portions at the opposite end (front end) thereof that is bent inward to be engaged with the end frame. When fixing the magnetic switch to the end frame, the deflection portion is deformed to have elasticity, and the claw portion is engaged with the end frame. As a result, the fixing member can easily and securely fix the magnetic switch to the end frame.
