Electromagnetic contactor

Abstract: An electromagnetic contactor includes an engaging portion formed on a side surface of its body and disposed below a coil terminal. An attachment is releasably attached to the body of the electromagnetic contactor. The attachment includes a casing containing an electric component, the casing having a resilient projection formed on a side surface thereof. The resilient projection is resiliently engageable releasably with the engaging portion. The attachment has a plate-like connecting element projecting outwardly from the casing. The connecting element is connectable with the coil terminal when the attachment casing is attached to the body of the electromagnetic contactor.

Description: The invention refers to an electromagnetic contactor comprising an attachment containing a functional component. From DE-U-86 22 553 an electromagnetic contactor with an attachment according to the preamble of claim 1 is known in which the contactor comprises a casing having stepped recesses at its lateral edges for cooling purposes in which terminals are located to which connecting elements of an attachment may be connected. The attachment comprises a housing having a shape adapted to the recess in a manner that said recess is completely filled. Thus, the total structure of the contactor equipped with the attachment is defined by a compact, unitary outfit. The casing of the attachment comprises a resilient protrusion which, in cooperation with a fixed abutment, engages matching holding means provided at the casing of the contactor so as to secure the attachment to the contactor. One of the connecting elements of the attachment is disposed at the end of a flexible cable protruding from the casing of the attachment so that after attaching the attachement to the contactor a separate connecting step is to be performed to electrically connect the attachment to the contactor. It is an object of the invention to provide an electromagnetic contactor which enables a firm and positive connection of an attachment to the electromagnetic contactor, and enables the attachment to be easily attached releasably to the electromagnetic contactor even after the electromagnetic contactor has been connected to a switchboard, and if necessary, can provide a sufficient insulation between the electromagnetic contactor and the attachment. This object is attained by the features set forth in claim 1. Preferred embodiments of the invention are subject matter of the dependent claims. With this construction, the attachment can be easily releasably attached to the electromagnetic contactor by resiliently engaging the engaging projection of the attachment with the engaging portion of the electromagnetic contactor. At this time, the plate-like connecting element is connected to the coil terminal and then is fastened thereto by a terminal screw. For removing the attachment from the electromagnetic contactor, the terminal screw is loosened, and the attachment body is pulled away from the electromagnetic contact. If the electrically-insulative material covering the connecting element is used, the insulating distance between the electromagnetic contactor and the attachment can be reduced, so that the assembly composed of the electromagnetic contactor and the attachment can be of a compact size. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view, showing an electromagnetic contactor and its attachment according to the present invention; Fig. 2 is an enlarged perspective view partially showing an engaging portion of the electromagnetic contactor of Fig. 1; Fig. 3 is an enlarged perspective view of the attachment of Fig. 1; Fig. 4 is a plan view showing the engagement of the engaging portion with resilient pawls; Fig. 5 is a cross-sectional view showing the connection between the electromagnetic contactor and the attachment; Fig. 6 is a side view of the electromagnetic contactor to which the attachment is attached; Fig. 7 is a perspective view of a modified attachment; Fig. 8 is a perspective view of another modified attachment; and Fig. 9 is a side view of the electromagnetic contactor to which the attachment of Fig. 7 or Fig. 8 is attached. DETAILED DESCRIPTION OF THE REFERRED EMBODIMENTS The invention will now be described with reference to the drawings. Referring to Fig. 1, an electromagnetic contactor include a body 1, and coil terminal portions 2 formed on one side surface of the body. A first engaging portion 3 is provided on the one side surface below the coil terminal portions 2, the first engaging portion 3 being formed by a recess which is formed in the one side surface of the contactor body. The first engaging portion 3 has a pair of opposed engaging projections 3a and 3b, as best shown in Figs. 2 and 4. An attachment 4 comprises a casing 5 containing a surge-suppressing element, an operation-indicating lamp, etc., the attachment casing 5 being made of a thermoplastic resin. As shown in Fig. 3, a pair of opposed resilient pawls 6 are formed integrally on one side surface of the attachment casing 5. Plate-like connecting elements 7 are formed on an upper surface of the attachment casing 5 and are connected to the electric components contained in the casing 5. The distance between the oppositely-directed outer surfaces of the pair of resilient pawls 6 is generally equal to the distance between the pair of engaging projections 3a and 3b. The attachment casing 5 is attached to the electromagnetic contactor 1 below the coil terminal portions 2 in a manner shown in Fig. 4. More specifically, first, the resilient pawls 6 are brought into contact with the engaging projections 3a and 3b, respectively. Then, the attachment casing 5 is urged against the electromagnetic contactor body 1, so that the resilient pawls 6 are resiliently deformed inwardly (i.e., toward each other), and when inclined surfaces 6a and 6a of the resilient pawls 6 pass past the engaging projections 3a and 3b, respectively, the resilient pawls 6 are fully fitted in the engaging portion 3, and at this time the resilient pawls 6 are returned to their original condition. Thus, the attachment casing 5 is attached to the electromagnetic contactor body 1 in intimate contact therewith. In this condition, the movement of the attachment casing 5 from the electromagnetic contact or body 1 in a direction of an arrow A (Fig. 2) is prevented by the resilient pawls 6. When the resilient pawls 6 are fitted in the engaging portion 3, the distal end of each of the connecting elements 7 is interposed between a coil terminal 8 of the coil terminal portion 2 and a head of a terminal screw 9, as shown in Fig. 5. Therefore, the attachment casing 5 is prevented from moving from the electromagnetic contactor 1 in a direction of an arrow B (Fig. 5) even if the terminal screws 9 are not tightened. The distal end of each connecting element 7 is notched to have a fork-shape or bifurcated shape, and therefore even if the terminal screws 9 are not removed from the coil terminals 8, the attachment casing 5 can be attached to the electromagnetic contactor 1 merely by loosening the terminal screws 9. Thus, as shown in Fig. 6, the attachment casing 5 can be attached to the electromagnetic contactor 1 in intimate contact therewith. For removing the attachment casing 5 from the electromagnetic contactor 1, the terminal screws 9 are loosened, and then the attachment casing 5 is pulled by the fingers away from the electromagnetic contactor 1, so that the resilient pawls 6 are resiliently deformed and are disengaged from the engaging projections 3a and 3b, thus achieving the removal. Figs. 7 to 9 show modified forms of the invention. In these embodiment, an electromagnetic contact 1 is of the same construction as that of the preceding embodiment of Figs. 1 to 6, and therefore will not be described here. These modified embodiments differ from the preceding embodiment in that the connecting elements 7 are covered by electrically-insulative members 10 and 10, respectively. As shown in Fig. 7, such electrically-insulative members 10 are separate and are mounted on and cover body portions of the connecting elements 7 except for their bifurcated distal ends. As shown in Fig. 8, the electrically-insulative members 10 and 10 may be formed integrally with the attachment casing 5. In these modified embodiments, when the attachment casing 5 is to be attached to the electromagnetic contactor 1, the resilient pawls 6 are pressed against the engaging projections 3a and 3b of the electromagnetic contactor 1 to be fitted in the engaging portion 3, as described above with reference to Fig. 4. Thus, the attachment case 5 can be attached to the electromagnetic contactor 1 as shown in Fig. 9. The removal of the attachment casing 5 from the electromagnetic contactor 1 can be done in the same manner as described above for the preceding embodiment of Figs. 1 to 6. As described above, according to the present invention, the engaging portion is formed on the side surface of the body of the electromagnetic contactor and is disposed below the coil terminal portions, and the resilient pawls engageable with the engaging portion are formed on the attachment casing, and the connecting elements for connection with the respective coil terminals project from the outer surface of the attachment casing. With this construction, the attachment can be easily attached to the electromagnetic contactor by one touch. Since an electrical connection between the attachment and the electromagnetic contactor is made by the connecting elements, the use of lead wires is unnecessary, and therefore time and labor for connecting such lead wires between the attachment and the electromagnetic contactor is saved. Further, the attachment casing is also secured to the electromagnetic contactor by the plate-like connecting elements, and therefore advantageously the attachment casing can be positively fixed to the electromagnetic contactor. Further, by electrically insulating the connecting elements, the insulating distance between the electromagnetic contact and the attachment casing can be reduced, which enables a compact-size assembly composed of the electromagnetic contactor and the attachment. By forming the electrically-insulative members of the connecting elements integrally with the attachment casing, the electromagnetic contactor and the attachment casing can be assembled into the unit more easily.

Claims: An electromagnetic contactor with an attachment, comprising: a body (1) having a side surface; a pair of coil terminals (8) provided on said side surface of said body (1); a pair of engaging portions (3a,3b) formed on said side surface and disposed below said pair of coil terminal (8); and an attachment (4) releasably attached to said body (1), said attachment (4) including a casing (5) containing an electric component, a pair of resilient projections (6) resiliently engagable with said pair of engaging portions (3a,3b), and a pair of plate-like connecting elements each having a fork-shaped distal end, projecting outwardly from said casing (5), and connectable to said pair of coil terminals (8), wherein said pair of resilient projections (6) of said attachment (4) are releasably engaged with said pair of engaging portions (3a, 3b), and said pair of plate-like connecting elements (7) are connected to said pair of coil terminals (8) characterised in that said fork-shaped distal ends of said plate-like connecting elements are inserted between said pair of coil terminals (8) and corresponding terminal screws (9) when said casing (5) of said attachment (4) is releasably attached to said electromagnetic contactor from one direction by one touch. An electromagnetic contactor as set forth in claim 1, in which said plate-like connecting element (7) is covered with an electrically insulative material except for that portion of said connecting element (7) connectable with said coil terminal (8). An electromagnetic contactor as set forth in claim 2, in which said electrically insulative material is integrally formed with said casing (5) of said attachment (4). An electromagnetic contactor as set forth in claim 1, in which said resilient projection comprises a resilient pawl (6). An electromagnetic contactor as set forth on any one of the preceding claims in which said engaging portions (3a,3b) comprise a pair of opposed engaging projections between which a recess is formed.

Inventors: HIROTA TAKATO C O FUJI ELECTRI, KOGAWA KUNIYUKI C O FUJI ELECT, OTAKE SHIGEAKI C O FUJI ELECTR, HIROTA, TAKATO C/O FUJI ELECTRIC CO., LTD., KOGAWA, KUNIYUKI C/O FUJI ELECTRIC CO., LTD., OTAKE, SHIGEAKI C/O FUJI ELECTRIC CO., LTD.
Applicants: FUJI ELECTRIC CO LTD, FUJI ELECTRIC CO., LTD.
Application year: 1989
Main classification: H01H50
IPC codes: H01H50