Johnson Electric S.a.

Georg Strobl

Benno Blase

Ho Seung Pun

Michel Tennoun

To F Wong

A brush assembly () for a miniature electric motor has a beryllium copper strip brush arm () and a graphite material brush head () moulded to an end thereof. The brush arm () has a number of apertures. The brush head () has a number of projections which pass through the apertures and form one or more caps () on the reverse side of the brush arm to secure the brush head () to the brush arm (). A method of forming the brush assembly is also provided.

Brush assembly

An oscillating motor has a rotor rotation of about &#xb1;15&#xb0; from a rest position. The rotor has two salient poles which face a respective permanent magnet across a small air gap. The stator has a laminated stator core supporting the magnets and also two salient poles each supporting a stator coil. The stator poles confront the rotor across a small air gap between the rotor poles. When no current is flowing through the coils, the rotor rests in a rest position with the poles aligned between the north and south poles of the magnets. During operations, the stator coils induce like magnetic poles in the stator poles which in turn induce like magnetic poles in the rotor poles causing the rotor to swing towards opposite magnetic poles of the permanent magnets. When current flows in the reverse direction, the rotor swings to the opposite poles of the magnets.

Electric motor

An electric motor comprises a statora rotorwindings on tlhe stator, a sleeveat one end of the motor for supporting or defining a bearing for the rotor and for attachment to a fuel pump. The sleeveforms the sole means of aligning the rotorand an impeller of the pump. The motor may be a brushless D.C. motor having sensors for sensing the position of the rotor relative to the stator, electronic circuitry for switching the current in the windings in response to outputs from the sensors so as to cause the rotor to rotate relative to the stator.

A brush assembly ( ) for a miniature electric motor has a beryllium copper strip brush arm ( ) and a graphite material brush head ( ) moulded to an end thereof The brush arm ( ) has a number of apertures. The brush head ( ) has a number of projections which pass through the apertures and form one or more caps ( ) on the reverse side of the brush arm to secure the brush head ( ) to the brush arm ( ). A method of forming the brush assembly is also provided.

A planar carbon segment commutator includes a commutator base of insulating material. The base has a rotational axis and front and rear surfaces extending, at least in part, transversely to the rotational axis. A plurality of apertures extends through the base. The commutator also includes a plurality of commutator terminals, each terminal having a terminal portion and a contact portion. Each contact portion extends through one of the apertures and is bent to lie against or in close proximity to the front surface of the base. Each terminal portion has two cutting edges for cutting insulation on a connector portion of a winding and a slot which, in use, straddles and grips the connector portion. The commutator also includes a plurality of carbon segments formed on the front surface of the base and over the contact portions, respectively, of the terminals and a housing having a plurality of housing recesses for receiving the terminal portions.

Planar carbon segment commutator

A rotor for a fuel pump motor has a shaft and a rotor core fitted to the shaft. A commutator is located on the shaft adjacent one end of the rotor core. Windings wound around poles of the rotor core are connected to terminals of segments of the commutator. A cover is fitted to the other end of the rotor core covering the ends of the windings protruding from the core. The cover has axially extending legs which are pressed into gaps between adjacent heads of the rotor poles. The commutator has an integral shroud in the form of a radially outer peripheral skirt extending axially from a radial wall of the commutator base towards the rotor core to cover the terminals and the ends of the windings protruding from the commutator end of the rotor core. A gap is left between the rotor core and the skirt and there are holes in the cover and radial wall of the commutator for the passage of fuel to cool the rotor.

Rotor

A bearing assembly 10 comprising an oil impregnated sintered bushing 15 supported by a bearing retainer 20 and a sintered oil collector 14 disposed in direct physical contact with an external surface of the bushing 15 to remove excess oil from the bushing. The oil collector 14 is preferably substantially oil free or non-impregnated, has a volume at least 10% that of the bushing and has a porosity which is 5 to 10% greater than the porosity of the bushing.

Bearing assembly for a miniature motor

Carbon segments (7) of a planar commutator are molded over contact members (5). Anchor means (8), integral with each carbon segment (7) have an interlocking part (11) engaging the rear surface (6) of the contact member (5) and fit into a first blind hole (4) in the form of a recess of uniform transverse cross-section extending rearwardly of the front end (3) of a molded plastic base member (1). The contact members (5) are each attached to the base member (1) by means of locking portions (15) which project into second blind holes (14) having internal surfaces which grip the locking portions (15).

An assembled commutator has a segment support portion and a housing portion. The housing portion has housing members formed with axially extending 'T'-shaped recesses and transversely extending slots for receiving armature leads. Insulation displacing terminals are inserted in the 'T'-shaped recesses and formed with slots which cooperate with the transversely extending housing slots to grip and contact the armature leads. The terminals may also be formed with recesses for receiving armature leads after the terminals have been placed in the housing portion and during the winding of the rotor. The terminals are held in place by commutator segments and include recesses for receiving retainers located on the commutator segments. The commutator segments may also include a carbon portion which surrounds a copper connection strip for connecting the terminals to the carbon portion of the commutator segment.

Assembled commutator

Carbon segments (7) of a planar commutator are moulded over contact members (5). Anchor means (8), integral with each carbon segment (7) have an interlocking part (11) engaging the rear surface (6) of the contact member (5) and fit into a first envelope (4) in the form of a recess of uniform transverse cross-section extending. rearwardly of the front end (3) of a moulded plastic base member (1). The contact members (5) are each attached to the base member (1) by means of locking portions (15) which project into second envelopes (14) having internal surfaces which grip the locking portions (15).

Choke coils (5) are attached to the inner part (1) of a two-part end cap assembly by means of first and second leads (9 and 30). Contact means (10) attached to the outer part (6) of the assembly are provided with two slotted plugs which each have two legs. On insertion of each slotted plug in a respective slot formed in the external surface of the inner part (1) of the assembly, the two legs of the slotted plug engage opposite sides of a first lead (9) of one choke coil (5) extending transversely across the slot and bite the opposite sides so as to make good electrical and mechanical contact with the first lead. Both legs of each slotted plug are formed with retaining teeth for engagement with the end walls of the slot into which the slotted plug is inserted, to resist withdrawal of the slotted plug from the slot. This helps secure the inner and outer parts in axial engagement.

Two-part end cap assembly

A permanent magnet rotor for an electric motor has a shaft, a coupler mounted on the shaft, a flux ring fitted to the coupler and located within a ring magnet. The flux ring is a split ring having a nominal outside diameter greater than the inside diameter of the magnet and is keyed to the coupler.

Permanent magnet rotor

A bearing retainer 20 has a hollow body 21 with an open end forming a mouth 25. The mouth opens into an inner void 23 having a bearing support surface 28 for receiving a bearing. The void also has a plurality of axially extending ribs 30 defining a number of lubrication reservoirs or recesses 33. A plurality of teeth 26 extend axially from the open end for engaging a hole in the motor casing to prevent rotation between the retainer and the casing and are deformable to prevent axial separation. Proud co-planar abutment surfaces 27 are respectively disposed between adjacent teeth and bear against the casing to axially align the casing and retainer. The bearing is made by forging, casting or sintering.

Bearing retainer for a miniature motor

A planar carbon segment commutator has contact members, with terminals, attached to the front surface of an insulating base member by means of overmoulded carbon segments formed integral with anchor pieces disposed within apertures in the base member. Each aperture has a second part disposed rearwardly of a first part having a smaller cross-section than the second part and the anchor piece disposed within the aperture has a locking portion which fills the second part of the aperture to thereby resist withdrawal of the anchor piece from the aperture. The contact members are embedded in the carbon segments and have holes filled with carbon segment material to increase interlocking between the contact members and the segments.

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Stuttgart, Germany

Georg Strobl