Electricity: magnetically operated switches – magnets – and electr – Electromagnetically actuated switches – Multiple contact type
Reexamination Certificate
1999-11-09
2001-05-08
Barrera, Ramon M. (Department: 2832)
Electricity: magnetically operated switches, magnets, and electr
Electromagnetically actuated switches
Multiple contact type
C335S260000
Reexamination Certificate
active
06229415
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to contactors for motor vehicle starters, of the kind including an electronic circuit. More particularly, the invention relates to an electrical contactor of the type comprising a movable magnetic core which is displaceable coaxially, in the axial direction, in a winding, and which acts on a plunger that controls displacements of a contact plate for electrically connecting together two terminals of the contactor, the contactor further being of the type in which the control plunger extends axially forward through a hole formed in a fixed transverse core of the contactor, the fixed core being disposed axially in front of the winding, the contact plate being received within a hollow cover arranged in front of the winding, the contactor being also of the type in which an electronic circuit is disposed within the cover, between the fixed magnetic core and a separating plate through which the control plunger passes.
BACKGROUND OF THE INVENTION
It is known to make use of electronic control circuits for controlling the power supply for energising the winding of the contactor. Such electronic circuits give substantially perfect control of the displacement of the movable core of the contactor, this displacement being that which, firstly, puts the starter pinion into mesh with the toothed starter crown of the internal combustion engine of a motor vehicle, and secondly completes the power circuit so as to start the electric starter motor which initially drives the vehicle engine in rotation.
It was originally proposed to arrange the electronic circuit on the outside of the contactor, but it rapidly became clear that it was preferable to incorporate it with the front cover of the contactor, so as to reduce the total bulk of the latter. However, electronic circuits are very sensitive to dust, humidity and the presence of metallic particles that can cause unwanted electrical contacts to occur between the different electrical connections of the circuit.
In contactors according to the present state of the art, the electronic circuit, in the form of a printed circuit board, is arranged within a compartment in the cover, this compartment being bounded on the rear by a separating wall or partition. However, this compartment is not sealed, due to the fact that the plunger which actuates displacements of the contact plate passes axially and centrally through this compartment. As a result, given that the control plunger must slide axially through two axial holes, formed in the fixed magnetic core and in the separating partition, it is necessary to provide a radial clearance between the plunger and these holes. Thus, during axial displacements of the control plunger, dusts or humidity are able to enter the compartment in which the electronic circuit is mounted.
DISCUSSION OF THE INVENTION
An object of the invention is to overcome the above mentioned problem.
According to the invention, an electrical contactor of the type comprising a movable magnetic core which is displaceable coaxially, in the axial direction, in a winding, and which acts on a plunger that controls displacements of a contact plate for electrically connecting together two terminals of the contactor, the contactor further being of the type in which the control plunger extends axially forward through a hole formed in a fixed transverse core of the contactor, the fixed core being disposed axially in front of the winding, the contact plate being received within a hollow cover arranged in front of the winding, the contactor being also of the type in which an electronic circuit is disposed within the cover, between the fixed magnetic core and a separating plate through which the control plunger passes, is characterised in that the separating plate comprises a transverse wall portion and an axial bush in which the control plunger is arranged to slide axially, and in that the said bush is open at the front forward of the transverse wall portion and at the rear behind the fixed transverse core.
According to a preferred feature of the invention, the separating plate defines, within the cover, a front compartment in which the contacts and the contact plate are disposed, and a sealed rear compartment in which the electronic circuit is disposed. Preferably then, the axial bush of the separating plate has a rear axial end which is engaged sealingly in the hole of the fixed magnetic core. In preferred embodiments of this last mentioned arrangement, the rear axial end of the bush of the separating plate includes an internal radial collar portion which defines a substantially annular transverse face in axial engagement at the rear against a front face of the fixed magnetic core when the rear end of the bush is received in the hole of the fixed magnetic core.
According to another preferred feature of the invention, the axial bush of the separating plate has an axial front end which extends beyond the transverse wall portion and which defines an abutment surface for the contact plate.
According to a further preferred feature of the invention, the axial bush has a central bore which comprises a rear segment, in which a rear portion of the control plunger is guided, and a front segment of larger diameter. Preferably in that case, the contact plate is mounted for sliding movement on an intermediate portion of the control plunger; a helical compression spring is interposed between an external radial collar portion disposed behind the intermediate portion, and the contact plate, so as to urge the contact plate towards an advanced position; and the spring, which surrounds the intermediate portion, is received with the latter in the wide front segment of the axial bush when the control plunger is in a retracted or rest position.
The transverse wall portion of the separating plate preferably has stiffening ribs.
In some embodiments of the invention, the cover has a transverse face which faces towards the rear and which is disposed at the junction between the two said compartments of the cover, a peripheral edge portion of the transverse wall portion of the separating plate being in axial forward engagement with the said transverse face.
Preferably, the rear compartment of the cover, in which the electronic circuit is received, is substantially annular, around the axial bush of the separating plate.
Further features and advantages of the invention will appear more clearly on a reading of the following detailed description of a preferred embodiment of the invention, which is given by way of non-limiting example only and with reference to the accompanying drawings.
REFERENCES:
patent: 4644179 (1987-02-01), Poinout et al.
patent: 5227751 (1993-07-01), Shiroyama et al.
patent: 5703551 (1997-12-01), Lefebvre et al.
patent: 5770901 (1998-06-01), Niimi et al.
patent: 42 18 543 (1993-12-01), None
patent: 0 390 553 (1990-10-01), None
patent: 0 751 545 (1997-01-01), None
patent: 2 586 855 (1987-03-01), None
patent: 2 193 845 (1988-02-01), None
French Search Report dated Nov. 14, 1997.
Barrera Ramon M.
Morgan & Finnegan , LLP
Valeo Equipments Electriques Moteur
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