Electricity: magnetically operated switches – magnets – and electr – Electromagnetically actuated switches – Multiple contact type
Patent
1993-10-14
1996-01-02
Donovan, Lincoln
Electricity: magnetically operated switches, magnets, and electr
Electromagnetically actuated switches
Multiple contact type
335131, H01H 6702
Patent
active
054812364
DESCRIPTION:
BRIEF SUMMARY
PRIOR ART
The invention relates to an engaging relay for a starter device (starter, in particular pre-engaged drive starter) of an internal combustion engine, having a magnetic core to which a relay coil is assigned, and having an armature which has a switching axle which penetrates a through-opening of the magnetic core and on which a bushing is arranged which is mounted in a guide section of the through-opening and which bears a contact bridge.
Engaging relays of this kind serve the purpose of switching a high current with a relatively low control current. The high current (starter current) which is required to start an internal combustion engine by means of a starter is for example up to approximately 1000 amps in passenger cars and up to 2500 amps in utility vehicles. Therefore, the starter switch is sufficient to switch on the low control current. The high starter current is switched by means of the engaging relay. However, the engaging relay also has a further function since it serves to move the pinion of the starter forward for engaging in a ring gear of the internal combustion engine. The armature of the engaging relay is connected, for the purpose of switching the starter current, with a contact bridge which connects main current contacts to one another in the excited state of the engaging relay. In order to bring about a suitable contact pressure for switching the large starter current, the contact bridge is acted on axially by means of a spring arrangement and mounted on a switching axle of an armature of the engaging relay. The spring arrangement does not engage directly on the contact bridge but rather indirectly via a bushing which holds the contact bridge. During mounting and in operation, the known engaging relay has disadvantages because the assignment of the position of the contact bridge to its set position is often not maintained with sufficient accuracy.
ADVANTAGES OF THE INVENTION
In comparison with the above, the engaging relay according to the invention having the features specified in the main claim has the advantage that a play-free and positionally accurate assignment of the contact bridge to its set position is maintained. For this purpose, an anti-rotation element is arranged between the magnetic core and the bushing. In this way, the relative position of the bushing with respect to the magnetic core is always maintained or it is at least always restored when the engaging relay is in the non-excited state, since the bushing then moves deeply into the guide section of the opening. The contact bridge has a fixed rotary-angle assignment with respect to the bushing itself so that a correct alignment of contact bridge with respect to the magnetic core and also to the main current contacts is always ensured.
In accordance with a further development of the invention, there is provision for the anti-rotation element to be formed by a non-circular cross-section of the outer surface of the bushing, and for the guide section of the through-opening to be constructed so as to match the shape of the cross-sectional contour of the outer surface. In particular, the non-circular cross-section can be constructed as a quadrilateral [sic], preferably as a hexagon. In this way, the predetermined rotary-angle position is always maintained between magnetic core and bushing irrespective of the operating state of the engaging relay.
In order to compensate manufacturing tolerances and bearing play, there is preferably provision for the guide section to be of conical construction such that it tapers with increasing depth. This results in the outer surface of the bushing being supported free of play on the guide section in the non-excited state of the engaging relay so that an extremely precise rotary-angle alignment takes place. However, it is also expedient as an additional or alternative feature for the outer surface of the bushing to be of corresponding conical construction such that its cross-section increases in the direction of the contact bridge. This has the advantage of an increased guide a
REFERENCES:
patent: 4725801 (1988-02-01), Snyder
patent: 4987396 (1991-01-01), Bogner
Binnenwies Arno-Albert
Nguyen Ngoc-Thach
Ruehle Walter
Schuette Hartmut
Donovan Lincoln
Robert & Bosch GmbH
Striker Michael J.
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