Mitsuba Corporation

Michio Okada

Shinichi Nagashima

Koji Nara

Yoshikazu Sato

Masaaki Ohya

Eiichi Kimura

Mitsuhiro Kogure

In an engine starter comprising: a DC electric motor; an output shaft; a pinion unit; a reduction gear unit for transmitting an output of the electric motor to the pinion unit through the output shaft; a solenoid device for axially moving the pinion unit into mesh with a ring gear of the engine; a cover member for surrounding at least the pinion and the reduction gear unit, the cover member having an opening facing the electric motor; a substantially cylindrical member for surrounding the electric motor so as to serve as a yoke for the electric motor; a disk-shaped plate for covering an end of the electric motor facing away from the pinion unit; and an annular separator disposed between the reduction gear unit and the electric motor so as to separate them from each other, the disk-shaped plate is provided with at least one axial protrusions for engaging an inner surface of one end portion of the substantially cylindrical member so as to align the disk-shaped plate and the substantially cylindrical member with each other, and an annular separator is provided with at least one axial protrusions for engaging an inner surface of the other end portion of the substantially cylindrical member so as to align the annular separator and the substantially cylindrical member with each other, and the annular separator is fitted into the opening of the cover member. Thus, since the disk-shaped plate, the substantially cylindrical member (yoke), the annular separator and the cover member are all aligned with each other without using the outer surface of the yoke, the outer surface of the yoke is allowed to be formed with lower precision. This eliminates the need of an additional step of machining or otherwise finishing the outer surface of the yoke with high precision, to thereby simplify the manufacturing process and lower the manufacturing cost of the yoke.

Starter for an internal combustion engine

In an engine starter, to facilitate the assembling of a solenoid assembly, an annular outer peripheral wall is formed in the casing for receiving the energization solenoid assembly and to secure the solenoid assembly by crimping a free end of the annular outer peripheral wall onto an axial end of the solenoid assembly, and the energization solenoid assembly is fitted into the bore defined by the annular outer peripheral wall by engaging the outer periphery of the solenoid assembly with three fingers of an assembly tool. A plurality of crimping portions are defined by a plurality of recesses provided along the circumferential direction of the free end of the annular outer peripheral wall so that the fingers of an assembling tool when inserting the solenoid assembly are not interfered by the annular outer peripheral wall.

Assembling arrangement for engine starters

In an engine starter according to the present invention, an annular stopper disposed between the pinion unit and the solenoid device so as to determine the rest position of the pinion unit is formed with a tongue projecting radially outwardly from its outer periphery, and a shoulder surface defined in the gear cover so as to abut an end surface of the solenoid device and thereby determine the axial position of the solenoid device is formed with a recess for receiving the tongue of the annular stopper, with the tongue and the recess being dimensioned with respect to each other so as to allow the tongue to be resiliently interposed between the recessed part of the shoulder surface and the end surface of the solenoid device and to define a space which accommodates a corresponding deformation of the tongue. Thus, since a space which accommodates the deformation of the tongue of the stopper is provided within the recess of the shoulder surface, the tongue can be resiliently deformed so as to support the annular stopper steadily without affecting the axial position of the solenoid device.

In an engine starter including a solenoid device for actuating a switch for the electric motor and to drive the pinion into mesh with the ring gear of an internal combustion engine, the solenoid device includes an armature outer member which moves in the direction to push out the pinion against the spring force of a first return spring in the energized state of the solenoid device, and an armature inner member which is resiliently urged by a second return spring, and is telescopically disposed with respect to the armature outer member with a coil spring interposed coaxially between them. An annular spring retainer is press fitted into the inner bore of the armature outer member to receive a corresponding coil end of the coil spring. The spring retainer is stamp formed from non-magnetic material so as to have cylindrical portion which is fitted into the bore of the armature inner member, a flange portion which is bent perpendicularly from the cylindrical portion in the manner of an inwardly directed flange in its installed state, and a guide piece portion which is bent perpendicularly with respect to the axial direction from the free end of the flange portion. The forming of the armature outer member is thereby simplified, and the guide piece portion supports the coil spring with a centering action. More importantly, the spring retainer which may be made of non-magnetic material can prevent any significant leakage of magnetic flux from the spring retainer.

Coaxial engine starter

Starting electric motor for automobile

In a starter for an internal combustion engine, comprising: a pinion; shift mechanism for moving the pinion into mesh with a ring gear of the engine; a housing for accommodating the pinion and the shift mechanism; an electric motor for rotating the pinion; a substantially cylindrical motor casing for accommodating the electric motor; a contact unit for selectively providing electric power to the electric motor; a brush holder stay disposed between the housing and the motor casing, the brush holder stay having a cavity opened toward the motor casing and the contact unit being mounted in the cavity; and a cover for covering the cavity of the brush holder stay, the cover is made of a flexible member so that the cover is naturally curved, and the cover is disposed between the brush holder stay and the motor casing with its concave surface facing the brush holder stay so that the cover is pushed toward the brush holder stay by an axial end of the motor casing. Thus, when pressed against the brush holder stay by the motor casing, the cover is deformed and made straight to produce a resilient restoring force, whereby increasing the pressing force to ensure sufficient watertight sealing effect.

In an electric motor comprising a plurality of permanent magnets (46) surrounding a motor armature (52) for supplying field flux to the armature, a cylindrical magnet cover (47) is fitted into an inner circumferential surface defined by the permanent magnets to protect the permanent magnets against chipping and other damages. The magnet cover is further provided with a radial flange (47b) having guide holes (47c) formed therein so that set bolts (48) passed axially inside the motor casings may be favorably guided as they are inserted from one axial end of the motor casing to the other. Preferably, to better guide the bolts, the guide holes may be each provided with a cylindrical guide boss (50, 51) which may be formed either by burring or cutting and lifting a part of the material of the flange.

Electric motor using permanent field magnets

In a starter (1) for an internal combustion engine including a planetary gear type reduction gear unit (2) and a housing (17) for accommodating at least the reduction gear unit (2), a recess (51) is formed at a lower part (17a) of the housing (17) in an installed state of the starter (1) in a manner that the recess (51) is formed in an inner periphery of the housing (17) so as to define a drain passage (51) extending substantially axially, and a part (52) of an outer periphery of a first annular member (12), which constitutes a part of the reduction gear unit (2), protrudes into the recess (51). Thus, the protruding part (52) of the outer periphery of the first annular member (12) forms a labyrinth structure in the drain passage (51) defined by the recess (51) formed in the inner periphery of the housing (17), to thereby effectively prevent water from entering the housing (17) through the drain passage (51) without substantially impeding the passage of water from the housing (17) to the outside. This protruding part (52) is integrally formed in the first annular member (12), and therefore no additional component parts are required to make the labyrinth structure.

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.

Coaxial engine starter system

In an engine starter comprising a pinion slidably fitted on the output shaft for driving a ring gear of an engine that is to be started, and a one-way clutch having a first end secured to the pinion and a second end which is engaged by the output shaft via spline means, a compression coil spring is interposed between a stopper secured to the output shaft and an annular shoulder defined in a cylindrical extension of the second end of the one-way clutch. Therefore, even when the pinion is forced into a high speed rotation by the engine which has been started by the engine starter, the pinion simply rotates freely, and no friction is applied to the compression coil spring or the stopper. Also, by receiving the compression coil spring in an annular space defined between the cylindrical extension of the second end of the one-way clutch and the output shaft, the compression coil spring can be protected from the centrifugal force which acts upon the compression coil spring when the output shaft of the engine starter rotates at an extremely high speed.

Engine starter system having an improved pinion assembly

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.

Growing community of inventors

Gunma, Japan

Michio Okada