Yoke of an electromagnetic clutch

A yoke of an electromagnetic clutch includes a ring case, a coil assembly, a connector, and at least one contact. The ring case includes an annular groove and an opening. The coil assembly is positioned in the annular groove. The connector is positioned in the opening of the ring-case and includes a first groove to receive an end portion of the coil assembly, a second groove to receive a lead wire of a diode, and a third groove to receive an end portion of an external wire. The at least one contact includes three pairs of slits and may be inserted in the connector so that each of the three pairs of slits is aligned with a respective one of the first groove, the second groove, and the third groove to form an electrical connection between the end portion of the coil assembly, the lead wire of the diode, and the end portion of the external wire.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a connector of an electromagnetic clutch. More particularly, the present invention relates to an electrical connector of a yoke of an electromagnetic clutch.

2. Description of Related Art

InFIG. 1, a compressor8of a vehicle air conditioner is shown. Compressor8may include an electromagnetic clutch9. Electromagnetic clutch9may selectively connect and disconnect a drive source to a drive shaft of compressor8.

Electromagnetic clutch9may include a yoke7. Yoke7comprises an annular-shaped ring case4, a coil assembly3, and a connector (not shown). Coil assembly3is positioned in an annular groove of ring case4. A bottom portion of ring case4is fixed to a housing of compressor8, via a plate10.

As shown inFIG. 2, coil assembly3comprises a coil bobbin1and a coil2wound around coil bobbin1. Coil2has end portions2a,2b. A substantially rectangular-shaped opening4ais formed through a bottom portion of ring case4. Coil assembly3may be positioned within annular groove of ring case4, so that end portions2a,2bof coil2pass through opening4a. After passing through opening4a, end portions2a,2bof coil2may be positioned in a connector5. Within connector5, each of end portions2a,2bof coil2may be connected electrically with a respective one of a pair of external wires6a,6b. Connector5may be secured to ring case4, so that a portion of connector5fits into opening4aof ring case4.

With reference toFIG. 3, connector5comprises a case5aand a cap5b. By caulking nail portions10aof plate10into nail receiving portions5nof case5a, case5amay be fixed to the bottom portion of ring case4. Cap5bmay include hooks (not shown). Case5amay include hook-receiving portions (not shown). When the hooks of cap5bengage the hook-receiving portions of case5a, cap5bmay be secured to case5a.

FIG. 4shows a known electrical terminal for connecting each external wire6a,6bto respective end portions2a,2bof coil2in connector5. Each external wire6a,6bmay be connected electrically to a respective end portion2a,2bof coil2, via a contact20. To connect each external wire6a,6bto a respective contact20, a portion of the insulation of each external wire6a,6bmust be removed to expose a core wire6dof each external wire6a,6b. After passing core wire6dof each external wire6a,6bthrough an electrical connection portion20aof each contact20, electrical connection portion20aof each contact20may be crimped or the like, around core wire6dof each external wire6a,6b, so that each external wire6a,6bmay be connected electrically to a respective contact20. Each contact20may include a slit20binto which a respective end portion2a,2bof coil2may be inserted, e.g., pressed or the like. When each end portion2a,2bof coil2is inserted into slit20bof a respective contact20, each end portion2a,2bof coil2is positioned in a direction that is substantially perpendicular to external wires6a,6b. By pressing each end portion2a,2bof coil2into slit20bof a respective contact20, each contact20may be connected electrically with a respective end portion2a,2bof coil2. In this way, each external wire6a,6bmay be connected electrically with a respective end portion2a,2bof coil2, via a contact20.

Thus, formation of an electrical connection between external wires6a,6band respective end portions2a,2bof coil2in electromagnetic clutches of known compressors may include the step of removing insulation from an end portion of each external wire6a,6bto expose core wire6d. Exposed core wire6dof each external wire6a,6bmay be inserted into a respective electrical connection portion20aof each contact20, and electrical connection portion20amay be crimped around core wire6dof each external wire6a,6b. Each contact20may be inserted into case5a, so that each end portion2a,2bof coil2is inserted into a slit20bof each respective contact20. Thus, this known method of connecting the external wires to the end portions of the coil may include multiple steps, each of which steps increases the time and cost of manufacturing the connector.

SUMMARY OF THE INVENTION

A need has arisen for an improved connector for establishing an electrical connection between external wires and end portions of the coil of an electromagnetic clutch. In particular, a need has arisen for an electrical connector that may be positioned in a yoke of an electromagnetic clutch to electrically connect external wires, end portions of the coil, and other wires, e.g., lead wires of a diode or the like.

A further need has arisen for a connector that establishes and maintains a secure electrical connection between the external wires and the end portions of the coil. A still further need has arisen for a connector that increases the electrical contact between the core wire of the external wires and a contact of the connector to strengthen and maintain a secure electrical connection.

Another need has arisen for a connector that securely retains a core wire of an external wire within a contact, e.g., that retains a core wire in a slit of a contact after the core wire is inserted into the slit. Still another need has arisen for a contact with a slit into which an external wire readily may be inserted, which may cut through insulation of an external wire, and which may retain a core wire of the external wire after the core wire is inserted into the slit, e.g., by narrowing in width.

In an embodiment of the present invention, a yoke of an electromagnetic clutch comprises a ring case, a coil assembly, a connector, and at least one contact. The ring case comprises an annular groove and an opening. The coil assembly is positioned in the annular groove of the ring case. The connector is positioned in an opening of the ring case and comprises a first groove adapted to receive an end portion of the coil assembly, a second groove adapted to receive a lead wire of a diode, and a third groove adapted to receive an end portion of an external wire. The at least one contact comprises three pairs of slits and may be inserted in the connector so that each of the three pairs of slits is aligned with a respective one of the first groove, the second groove, and the third groove, so that the at least one contact forms an electrical connection between the end portion of the coil assembly, the lead wire of the diode, and the end portion of the external wire.

In a further embodiment of the present invention, a method of connecting a plurality of wires in a connector case of a yoke of an electromagnetic clutch, wherein the connector case comprises a first groove, a second groove, and a third groove, comprises the steps of positioning a first wire in the first groove, positioning a second wire in the second groove, positioning a third wire in the third groove, positioning a contact in the connector case in alignment with each of the first, second, and third wires, and inserting the contact into the connector case, so that the contact engages the first, second, and third wires.

Other objects, features, and advantages of embodiments of this invention will be apparent to persons of ordinary skill in the art from the following detailed description of the invention and the accompanying drawings.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG.5(a) shows a connector for establishing an electrical connection between external wires6a,6band end portions2a,2bof a coil2, according to the present invention. The connector may further be used for connecting lead wires12a,12bof a diode12to external wires6a,6band end portions2a,2bof coil2. The connector may include a pair of contacts11and a connector case5a.

Each contact11may be substantially parallelepiped-shaped and include a substantially rectangular-shaped upper plate11a, a pair of first side plates11f, and a pair of second side plates11c. The pair of first side plates11fmay extend respectively from a first pair of opposing sides of upper plate11a. The pair of second side plates11cmay extend respectively from a second pair of opposing sides of upper plate11a. Each of first side plates11fmay include a slit11g, which may be formed at a lower edge of each first side plate11fand extend from the lower edge of each first side plate11ftoward upper plate11a. Each of second side plates11cmay include a pair of slits11d,11e, each of which slits11d,11emay be formed at a lower edge of each second side plate11cand extend from the lower edge of each second side plate11ctoward upper plate11a.

Grooves for external wires6a,6b, e.g., curved notches5g, may be formed in connector case5ato receive external wires6a,6b. A pair of lead wire grooves5dmay be formed in connector case5ato receive lead wires12a,12bof diode12. Lead wire grooves5dmay extend inwardly from an outer wall of connector case5ain a direction that is substantially perpendicular to a longitudinal axis of the outer wall and to an axis of external wires6a,6bwhen external wires6a,6bare positioned in notches5gof connector case5a. A pair of coil grooves5cmay be formed in connector case5ato receive end portions2a,2bof coil2. Coil grooves5cmay extend inwardly from an outer wall of connector case5ain a direction that is substantially parallel to lead wire grooves5d. Two pairs of first grooves5fmay be formed in connector case5ato receive first side plates11fof each contact11. Two pair of second grooves5emay be formed in connector case5ato receive second side plates11cof each contact11.

To assemble the connector according to an embodiment of the present invention, each end portion2a,2bof coil2may be placed in a respective coil groove5cof connector case5a. Each lead wire12a,12bof diode12may be placed in a respective lead wire groove5dof connector case5a. Each external wire6a,6bmay be positioned in a respective external wire notch5gand extend through connector case5a, so that an end portion of each external wire6a,6bmay touch a wall5hof connector case5a. Wall5hmay be positioned on a side of connector case5athat is furthest removed from a side of connector case5ain which external wire notches5gare formed. External wires6a,6bmay extend in a direction that is substantially perpendicular to an axis of lead wire grooves5d, and thus to each of lead wires12a,12bwhen lead wires12a,12bare positioned in lead wire grooves5d.

To electrically connect end portion2aof coil2, lead wire12aof diode12, and external wire6a, one contact11of the pair of contacts11may be positioned in connector case5a, so that slit11gis aligned with external wire groove5gand end portion of external wire6a, Slit11eis aligned with lead wire groove5dand lead wire12aof diode12. Slit11dis aligned with coil groove5cand end portion2aof coil2. When upper plate11aof contact11is inserted into connector case5a, first side plates11fmay be inserted into first grooves5f, and second side plates11cmay be inserted into second grooves5e. Moreover, slit11gengages external wire6a, slit11eengages lead wire12aof diode12, and slit11dengages end portion2aof coil2, such that an electrical connection may be formed between external wire6a, lead wire12aof diode12, and end portion2aof coil2.

To electrically connect end portion2bof coil2, lead wire12bof diode12, and external wire6b, a second contact11of the pair of contacts11may be positioned in connector case5a, so that slit11gis aligned with second external wire groove5gand end portion of external wire6b. Slit11eis aligned with second lead wire groove5dand lead wire12bof diode12. Slit11dis aligned with second coil groove5cand end portion2bof coil2. When upper plate11a of contact11is inserted into connector case5a, first side plates11fof contact11may be inserted into first grooves5f, and second side plates11cof contact11may be inserted into second grooves5e. Moreover, slit11gengages external wire6b, slit11eengages lead wire12bof diode12, and slit11dengages end portion2bof coil2, such that an electrical connection may be formed between external wire6b, lead wire12bof diode12, and end portion2bof coil2. Thus, an electrical connection may be established between external wires6a,6b, end portions2a,2bof coil2, and lead wires12a,12bof diode12, via a pair of contacts11and connector case5a, as shown in FIG.5(b).

As shown inFIG. 6, an electrical connection may be formed between end portion2aof coil2and contact11, via engagement of end portion2awith slit11dof contact11. Moreover, an electrical connection may be formed between lead wire12aof diode12and contact11, via engagement of lead wire12awith slit11eof contact11.

Further, an electrical connection may be formed between end portion of external wire6aand contact11, via engagement of core wire6a″ of external wire6awith slit11gof each first side plate11fof contact11. This connection may be formed when contact11is inserted into connector case5a, e.g., when first side plates11fare inserted into first grooves5f, and second side plates11care inserted into second grooves5e. As contact11is inserted into connector case5a, the edges of slit11gcut through insulation of external wire6ato engage a portion of core wire6a″ of external wire6a. In this way, an electrical connection may be formed between external wire6aand contact11. An electrical connection may be formed in a similar manner between end portion of external wire6band a second contact11.

FIG.7(a) shows the shape of slit11gof first side plates11fof contact11according to an embodiment of the invention. Moreover, slits11d,11eof second side plates11cmay have a shape similar to that of slit11g. Slit11gmay include a wide portion11hand a narrow portion11i. A tapered portion11h′ may connect wide portion11hand narrow portion11i. In a preferred embodiment of the invention, a depth L1and a width W of wide portion11hmay be greater than an outer diameter D of external wire6a, so that external wire6amay be held securely within wide portion11hbefore contact11is inserted into case5a. Thus, contact11may include slits11gof varying dimension.

Narrow portion11iof contact11includes two lateral edges11i′ and an end edge portion11i″. In a preferred embodiment of the invention, the distance between lateral edges11i′, i.e., the width w of narrow portion11i, may be less than a diameter d of core wire6a″ of external wire6a, so that core wire6a″ of external wire6amay be held securely in narrow portion11iin contact, e.g., in electrical contact, with lateral edges11i′ of slit11gwhen contact11is inserted into case5aand first side plate11fenters first groove5f, as shown in FIG.7(b). Referring again to FIG.7(a), in a preferred embodiment of the invention, a depth L2of narrow portion11imay be larger than outer diameter D of external wire6a, so that external wire6amay move along enough of a length of slit11gto securely establish an electrical contact between core wire6a″ and each lateral edge11i′ of slit11gof first side plate11f. When each first side plate11fof contact11is pushed into a respective first groove5fof connector case5a, tapered portions11h′ gradually cut into regions61,62, indicated by broken lines, of insulation6a′ of external wire6a, so that contact11may be inserted in connector case5awith comparatively less force than in known connectors.

Further, tapered projections11jmay be formed at both outer sides of first side plate11f. Referring to FIG.7(b), as each tip11f′ of first side plate11fapproaches a bottom surface5f′ of first groove5fof connector case5a, each tapered projection11jcontacts side walls5f′ of first groove5f. The engagement of side walls5f″ and tapered projections11jdeforms first side plate11fof contact11, so that a space Z between each tip11f′ of first side plate11fdecreases. As a result, a width of an entrance of narrow portion11i, i.e., a distance between lateral edges11i′ of narrow portion11iis reduced when first side plate11fis inserted into groove5f, so that core wire6a″ may be retained securely within narrow portion11iof slit11g. In this way, a secure electrical connection may be maintained between core wire6a″ of external wire6aand lateral edges11i′ of narrow portion11iof slit11gof contact11.

According to another embodiment of the invention, a width of wide portion11hof slit11gmay decrease in a stepwise manner as wide portion11hextends toward narrow portion11i, as shown in FIG.8. Wide portion11hmay include a plurality of tapered portions11h′ and a plurality of vertical portions11h″, each of which vertical portions11h″ extends in a direction that is substantially parallel to that of narrow portion11i. Tapered portions11h′ and vertical portions11h″ are positioned alternately along both sides of wide portion11hof slit11g, so that, as slit11gextends inwardly from an outer edge of first side plate11f, a width of wide portion11hof slit11gdecreases in a stepwise manner. Thus, when contact11is pushed into case5a, tapered portions11h′ gradually and stepwisely cut into insulation6a′ of external wire6a. Accordingly, each tapered portion11h′ may progressively cut into and through insulation6a′ of external wire6a.

According to a further embodiment of the invention, narrow portion11iof slit11gmay include a curved, substantially semicircular end portion11i″ having a diameter D2that is greater than a width of narrow portion11i, e.g., greater than a distance between lateral edges11i′ of narrow portion11i, as shown in FIG.9. End portion11i″ may form a rounded, extended space11kin first side plate11fat an end of narrow portion11iof slit11gthat is opposite to an opening of slit11g. When core wire6a″ is inserted into rounded, extended space11k, core wire6a″ may expand, e.g., individual wires of core wire6a″ may separate or spread apart. The expansion of the core wire6a″ within rounded, extended space11kmay retain core wire6a″ within rounded, extended space11kof narrow portion11i. According to this embodiment of the invention, a depth L2of narrow portion11iof slit11gmay be reduced compared to known connectors.

In yet another embodiment of the invention, a plurality of saw teeth11mmay be formed on both lateral edges11i′ of narrow portion11i, as shown in FIG.10. When core wire6a″ enters narrow portion11iin this embodiment of the invention, individual wires of core wire6a″ may contact one or more saw teeth11m, so that a contact area between core wire6a″ and narrow portion11imay be increased compared to known connectors. In this way, an electrical connection between core wire6a″ and contact11may be improved compared to known connectors.

In a still further embodiment of the invention, end portion11i″ of narrow portion11iof slit11gmay include a tooth11n, as shown in FIG.11. Tooth11nmay be formed at end portion11i″ of narrow portion11iand extend away from end portion11i″ and toward an opening of slit11g. When core wire6a″ enters narrow portion11iin this embodiment of the invention, tooth11nin may extend into core wire6a″, e.g., tooth11nin may extend into and contact individual wires of core wire6a″, so that a contact area between core wire6a″ and narrow portion11imay be increased compared to known connectors. In this way, an electrical connection between core wire6a″ and contact11may be improved compared to known connectors.

In an additional embodiment of the invention, narrow portion11iof slit11gmay include a pair of projections11p, as shown in FIG.12. Projections11pmay be positioned at an entrance of narrow portion11i, e.g., at a position of narrow portion11iadjacent to wide portion11h. Projections11pmay extend inwardly, e.g., toward one another, so that a width of narrow portion11iis reduced at projections11p. After core wire6a″ enters narrow portion11i, projections11pcooperate to retain core wire6a″ within narrow portion11iof slit11g. In this way, an electrical connection between the core wire6a″ and contact11may be maintained.

Thus, contact11according to the present invention, may include three pairs of slits11d,11e,11g. Contact11may be positioned in a connector, e.g., a connector case5a, in alignment with three wires, each of which wires may be inserted simultaneously into one of the three pairs of slits when contact11is inserted into connector. Thus, an electrical connection may be formed between an end portion2a,2bof coil2, a lead wire12a,12bof diode12, and an external wire6a,6b, via contact11, by placing end portion2a,2bof coil2, lead wire12a,12bof diode12, and end portion of external wire6a,6bin connector case5aand by pressing contact11into connector case5aand onto each wire, so that each wire is engaged by a respective pair of slits11d,11e,11gof contact11.

By the present invention, the step of removing insulation from an end portion of an external wire may be omitted. By the present invention, the step of crimping the exposed external wire in a contact may be omitted. Moreover, by the present invention, each of the external wire, the lead wire of a diode, and the end portion of the coil may be connected by inserting a contact into a connector case.

Moreover, the connector of the present invention securely maintains the electrical connection formed between the contact, the external wires, the end portions of the coil, and the lead wires of the diode, via an improved design of one or more slits of the contact. For example, the width of an entrance of each slit may narrow progressively as the slit extends away from a slit opening, so that the external wire may inserted more easily into each slit and so that the slit may cut through insulation of the external wire more easily than in known electrical connectors.

According to the present invention, the contact area between the core wire of the external wire and the contact may be increased, so that a secure electrical contact may be established and maintained therebetween. Moreover, the connector of the present invention may include a contact with a slit configured to retain the core wire within the slit of the contact after the core wire is inserted into the slit, so that the core wire may not escape from the slit, as may occur in known connectors.

Although the present invention has been described in detail in connection with preferred embodiments, the invention is not limited thereto. It will be understood by those skilled in the art that variations and modifications may be made within the scope of this invention, as defined by the following claims.