Coil unit of electromagnetic contactor and assembling method thereof

In a coil unit of an electromagnetic contactor in which a coil having a coil strand wound around a flanged bobbin is mounted on a leg of a stationary core of an operating electromagnet, into one flange of the bobbin are press fitted a pair of terminal metal pieces respectively corresponding to an initial side and final side lead wires of the coil, and each of the terminal metal pieces is formed with a press fitting base making the terminal metal piece press fitted into the one flange, a coil connecting arm around which the lead wire of corresponding side of the coil is wound and a tab terminal made to have a plug-in connection with a connector of an extension lead.

BACKGROUND

The present invention relates to a coil unit of an operating electromagnet mounted on an electromagnetic contactor, and in detail, to a terminal structure of a coil with a coil strand wound on a bobbin, and to an assembling method of a coil unit to which the terminal structure is adopted.

For a coil unit of an operating electromagnet opening and closing main circuit contacts of an electromagnetic contactor, a single coil unit is generally known in which an assembly having a coil with a coil strand wound on a bobbin is mounted on a central leg of an E-shaped stationary core. In addition, a double coil unit (DC excitation system) is known in which the coil unit is divided into two sets of single coil units to be respectively mounted on right and left legs of a U-shaped stationary core with coils of the respective coil units made coupled in series for being connected to an operating circuit (See, for example, “A structure of an electromagnetic contactor and designations of parts thereof, SC-N6”, (online) Fuji Electric Technica Co., Ltd., [Retrieved on Aug. 30, 2008], Internet URL:http://www.fe-technica,co.jp/html/shohin/41/pdf/AH294_P1—10-17.pdf>).

The structure of an electromagnetic contactor mounting the related double coil unit, described in the foregoing non-patent document, for an operating electromagnet and the structure of the related double coil unit are shown inFIG. 8AtoFIG. 10D. First, inFIGS. 8A to 8C, the electromagnetic contactor is formed of a main body case1, a power supply side main circuit terminal2, a load side main circuit side terminal3, stationary contactors4and5, a bridging movable contactor6, a movable contactor holder7, a movable core8of an operating electromagnet, a two-leg stationary core9of soft-iron, a back spring10, a double coil unit11, a pair of extension leads (insulated covered wires)12, a printed-circuit board13of an operating circuit and external terminals14of the operating circuit. In the foregoing, the main body case1is formed with a structure dividable into three of a lower case1a, an upper case1band an arc-extinguishing chamber cover1c. The two-leg stationary core9is formed of a yoke9a, a left leg9band a right leg9c. The back spring10energizes the movable core8toward the release side. The double coil unit11has equally specified two sets of single coil units11A and11B, each having a coil16with a coil strand wound around a bobbin15of molded resin, combined to be mounted on the left leg9band the right leg9c, respectively, of the stationary core9. A pair of the extension leads12are connected to their respective single coil units11A and11B to be taken out therefrom. Moreover, reference numerals9b-1and9c-1denote magnetic pole plates of the left leg9band the right legs9c, respectively, of the stationary core9and reference numeral12adenotes a connector for making each of the extension leads12have a plug-in connection to the printed-circuit board13.

Next, the assembled structure of each of the aforementioned single coil units11A and11B is shown inFIGS. 9A to 9E. Each of the single coil units11A and11B has a structure having a coil16with a coil strand wound around the bobbin15of molded resin. The bobbin15has flanges15band15cat the upper and lower ends, respectively, of a barrel15a. On the rim of each of the flanges15band15c, a coupling tab15dand an engaging projection15eare formed which are used when coupling the single coil units11A and11B as will be described later. Moreover, the coil16is formed by winding a coil strand (an enameled wire, for example) around the barrel15aof the bobbin15and wrapping the outer surface of the wound coil strand with insulating tape17with the initial side lead wire16aand the final side lead wire16b, each being a part of the coil strand, being taken out from the bobbin15.

In each of the single coil units11A and11B, for forming the coil16with the coil strand wound around the bobbin15, the initial side lead wire16ais first temporarily fastened on the surface of the barrel15aof the bobbin15with a piece of adhesive tape18before the coil strand is wound around the barrel15aby an automatic coil winding machine. The final side lead wire16bis also temporarily fastened on the coil16with a piece of adhesive tape18in the same way as above. Finally, by wrapping the outer surface of the coil16with a strip of insulating tape17, each of the single coil units11A and11bis completed.

Next, the assembled structure of the double coil unit11with aforementioned two sets single coil units11A and11B arranged side by side to be combined are shown inFIGS. 10A to 10D. Namely, the single coil units11A and11B are combined by coupling their respective bobbins15with the flanges15bat the upper ends made butted against each other and the flanges15cat the lower ends made butted against each other, in which the coupling tabs15dare made engaged with the engaging projections15emated thereto. Then, as shown in a connection diagram given asFIG. 10D, the final side lead wires16bof the single coil units11A and11B are twisted together to be joined and soldered (W: solder). Moreover, the initial side lead wire16aof each of the single coil units11A and11B and the strand of the extension lead12for external connection are twisted together to be joined and soldered. Furthermore, a strip of the insulating tape17is wound around the outer surfaces of the coils16of the single coil units11A and11B so as to wrap the coils16together and cover the soldered junction of the final side lead wires16band each soldered junction of the initial side lead wire16aand the strand of the extension lead12for external connection. Thus, the coils16are coated for insulation for being provided as the assembly of the double coil unit11.

Thereafter, the assembly of the aforementioned double coil unit11is, as was explained with reference toFIGS. 8A to 8C, made fitted to the left leg9band the right leg9cof the stationary core9to be mounted on the lower case1aof the electromagnetic contactor. Then, the connectors12aof each of the extension leads12is made to have a plug-in connection to the circuit on the printed circuit board13.

Incidentally, the aforementioned coil unit with the related structure has the following problems in ease of assembling. First, in assembling each of the single coil units11A and11B, in the step of forming the coil16with a coil strand wound around the bobbin15, troublesome manual work is required in which each of the initial side lead wire16aand the final side lead wire16bof the coil16is temporarily fastened with a piece of the adhesive tape18. Second, in the step of forming the double coil unit11by combining two sets of the single coil units11A and11B, time consuming work process is required in which the final side lead wires16bof the single coil units11A and11B are twisted together to be soldered by manual work, and the initial side lead wire16aand the extension lead12for external connection of each of the single coil units11A and11B are also twisted together to be soldered by manual work. Therefore, in an assembling process of the coil unit, there are many working processes carried out by manual work to cause the products to be high in cost.

The invention was made in view of the foregoing with an object of providing a coil unit of an electromagnetic contactor in which unit a coil strand can be wound with reduced working man-hours of manual work and, together with this, the terminal structure of the coil is improved so that the connection of the lead wires of the coil and the connection of the lead wire of the coil and an extension lead can be carried out with a simple single plug-in operation without requiring soldering, and providing an assembling method of the coil unit.

SUMMARY OF THE INVENTION

In order to achieve the above object, according to the invention, in a coil unit of an electromagnetic contactor in which a coil having a coil strand as a conductor wire wound around a flanged bobbin is mounted on a leg of a stationary core of an operating electromagnet, into one flange of the bobbin are press fitted a pair of terminal metal pieces respectively corresponding to an initial side lead wire as an initial side conductor wire and a final side lead wire as a final side conductor wire of the coil, and each of the terminal metal pieces is formed with a press fitting base for making the terminal metal piece press fitted into the one flange, a coil connecting arm around which the lead wire as the conductor wire of corresponding side of the coil is wound and a tab terminal made to have a plug-in connection with a corresponding connector of an extension lead.

For press fitting the terminal metal piece, a terminal metal piece mounting base is formed at each of two positions extended from a rim of the one flange of the bobbin, the terminal metal piece mounting base having a press fitting groove into which the terminal metal piece is press fitted. Moreover, with a method of assembling a coil unit with the above structure, the coil unit is assembled by undergoing a process including the steps of press fitting a pair of the terminal metal pieces into the one flange of the bobbin, winding the initial side lead wire of the coil around the coil connecting arm formed in the one of the terminal metal pieces before winding the coil strand around the bobbin to form the coil, winding the final side lead wire of the coil around the coil connecting arm formed in the other terminal metal piece, soldering the initial side and final side lead wires of the coil wound around the coil connecting arms formed in their respective terminal metal pieces, and making the tab terminal formed in each of the terminal metal pieces have a plug-in connection with the connector of the extension lead.

Furthermore, in the invention, two sets of single coil units, each having the structure of the coil unit as described in the foregoing, are arranged side by side to be coupled with each other, the tab terminal of the terminal metal piece corresponding to the final side lead wire of the coil in the one single coil unit is made to have a plug-in connection with a connector at the one end of an extension lead for series connection and the tab terminal of the terminal metal piece corresponding to the final side lead wire of the coil in the other single coil unit is made to have a plug-in connection with a connector at the other end of the extension lead for series connection, and the tab terminal of the terminal metal piece corresponding to the initial side lead wire of the coil in each of the single coil units is made to have a plug-in connection with a connector of an extension lead for external connection, by which a double coil unit is formed.

According to the above described coil unit of the invention, when a coil strand is wound around the bobbin, there is required no troublesome manual work such that each of the initial side lead wire and the final side lead wire of the coil is temporarily fastened one by one with a piece of adhesive tape, but only by winding the end of a lead wire around the connection arm of the terminal metal piece press fitted beforehand into the flange of the bobbin, the coil strand and the bobbin in thus as-is states can be set in an automatic coil winding machine to make the coil strand wound around the bobbin.

Moreover, also in the step of connecting the extension lead to the lead wire after the coil strand has been wound on the bobbin, there is required no troublesome manual work like in the related art in which the lead wire and the strand of the extension lead to be connected to each other are twisted together to be soldered, but the lead wire can be easily connected to the extension lead by a simple single operation with plug-in ease of inserting the tab terminal formed in the terminal metal piece into a connector of the extension lead. This can reduce working man-hours of manual work to lower the manufacturing cost of the coil unit compared with that of the related structure.

Furthermore, also about a double coil unit formed with two sets of single coil unit arranged side by side to be connected, each of the connection of the two sets of the single coil units and the connection of the extension lead wires for external connection to the coil unit can be carried out with plug-in ease of only inserting the tab terminal formed in the terminal metal piece of each single coil unit into the corresponding plug-in connector attached to each of the extension lead for series connection and the extension leads for external connection without requiring any soldering work. This improves easiness in assembling the double coil unit.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following, an embodiment of the invention will be explained on the basis of an example shown inFIG. 1AtoFIG. 7Cwith the double coil unit applied to the operating electromagnet taken as a subject which electromagnet is mounted on the electromagnetic contactor shown inFIGS. 8A to 8C. Here,FIG. 1Ais a perspective view showing the structure of a bobbin of a single coil unit according to the example of the invention,FIG. 1Bis a perspective view showing the structure of a terminal metal piece to be press fitted to the bobbin shown inFIG. 1A,FIG. 2Ais a plan view showing the external shape of the bobbin shown inFIG. 1A,FIG. 2Bis a side view showing the external shape of the bobbin shown inFIG. 2A,FIG. 3is an enlarged perspective view showing a terminal metal piece mounting base in the section indicated by the arrow A inFIG. 1A,FIG. 4is an enlarged perspective view showing the terminal metal piece mounting base inFIG. 3with the terminal metal piece shown inFIG. 1Abeing attached thereto by press fitting,FIG. 5Ais a plan view showing the structure of a double coil unit formed with two sets of single coil units shown inFIG. 1Aarranged side by side to be combined,FIG. 5Bis a side view showing the structure of the double coil unit shown inFIG. 5A,FIG. 5Cis a connection diagram of the double coil unit shown inFIGS. 5A and 5B,FIG. 6Ais a side view showing an extension lead for series connection for connecting the respective lead wires of two coils in the double coil unit shown inFIGS. 5A to 5C,FIG. 6Bis a side view showing an extension lead for external connection to be connected to a lead wire of each coil in the double coil unit shown inFIGS. 5A to 5C,FIG. 7Ais a plan view showing a structure of a connector provided at each end of the extension lead for series connection shown inFIG. 6Aand at one end of the extension lead for external connection shown inFIG. 6B,FIG. 7Bis a perspective view showing the connector shown inFIG. 7A, andFIG. 7Cis a perspective view showing a structure of a solderless terminal provided at the other end of the extension lead for external connection shown inFIG. 6B. InFIG. 1AtoFIG. 7C, the constituents corresponding to those shown inFIG. 9AtoFIG. 10Dare denoted with the same reference numerals and signs with detailed explanation thereof will be omitted.

Namely, in the example, into each of a pair of terminal metal piece mounting bases15fformed in a lower flange15cof a bobbin15shown inFIG. 1A, a terminal metal piece19shown inFIG. 1Bis press fitted. Around a coil connecting arm19bprovided in the one of the terminal metal pieces19, an initial side lead wire16a(seeFIG. 4) of a coil16is wound to be temporarily fastened to the terminal metal piece19before a coil strand is wound around the barrel15aof the bobbin15by an automatic coil winding machine. Moreover, after the coil strand has been wound around the barrel15ato form the coil16, a final side lead wire16b(seeFIG. 4) of the coil16is wound around a coil connecting arm19bprovided in the other terminal metal piece19before the initial side and the final side lead wires16aand16bare soldered to the coil connecting arms19bprovided in the respective terminal metal pieces19, by which each of a single coil unit11A and a single coil unit11B are assembled.

Next, the respective bobbins15in the two sets of the single coil units11A and11B are made butted against each other to be coupled as shown inFIGS. 5Aand5B. Thereafter, tab terminals19cformed in the terminal metal pieces19are inserted into corresponding connectors22(seeFIGS. 7A and 7B) of an extension lead for series connection20(seeFIG. 6A) and extension leads for external connection21(seeFIG. 6B) to provide their respective plug-in connections, by which the single coil units11A and11B are connected in series to be assembled into a double coil unit11.

Following this, the detailed structure of the terminal metal piece19and its press fit mounting to the bobbin15will be explained. First, as shown inFIG. 1AandFIG. 2A, the lower flange15cof the bobbin15is provided with a pair of the terminal metal piece mounting bases15frespectively formed at the right and left corners on the side opposite to a coupling tab15d. The terminal metal piece mounting base15fhas an L-shaped press fitting groove15f-1(seeFIG. 3) opened on its rear wall.

While, as shown inFIG. 1B, the terminal metal piece19is formed with a press fitting base19abent in an L-shape corresponding to the shape of the press fitting groove15f-1, the coil connecting arm19bprojecting forward from the press fitting base19a, the tab terminal19cto be inserted into the connector22of the extension lead for series connection20or of the extension lead for external connection21for a plug-in connection with the connector22, and further, teeth19dfor preventing missing at each end rim of the press fitting base19a. The terminal metal piece19is, as shown inFIG. 1A, inserted into the terminal metal piece mounting base15fof the bobbin15from the side to be kept being secured at a specified position with the press fitting base19apress fitted into the press fitting groove15f-1.

When the coil16is provided with the bobbin15set in the automatic coil winding machine to have the coil strand wound around the bobbin15, the initial side lead wire16ais first wound several times around the coil connecting arm19bof one of the terminal metal pieces19to be temporarily fastened to the arm19b(seeFIG. 4). In such a situation, the coil strand is wound around the barrel15aof the bobbin15. After the coil strand has been wound around the bobbin15to be the coil16, the final side lead wire16bis wound several times around the coil connecting arm19bof the other terminal metal piece19to be temporarily fastened to the arm19b. Then, in the following soldering process, the temporarily fastened part of each of the initial and final lead wires16aand16b, respectively, is soldered to be connected to the terminal metal piece19so as not to be detached therefrom. With this, the assembly of the single coil units11A and11B is completed.

Subsequent to this, in the assembling process of the double coil unit11, like the assembling process of the double coil unit with the related structure explained with reference toFIGS. 10A to 10D, the respective bobbins15of the single coil units11A and11B are made butted against each other while being arranged side by side to be coupled as shown inFIGS. 5A and 5Bwith the coupling tab15dformed in each of an upper flange15band the lower flange15cof the one bobbin15made engaged with the engaging projection15eformed in each of the upper and lower flanges15band15cof the other bobbin15. Moreover, for unifying the coil16of the single coil unit11A and the coil16of the single coil unit11B with their respective bobbins15coupled to each other, a strip of insulating tape is kept being wound several times around over the outside of the coils16in both of the single coil units11A and11B.

In such an assembled state, the connector22(seeFIGS. 7A and 7B) attached to each end of the extension lead for series connection20(seeFIG. 6A) is then made to have the tab terminal19cinserted which is formed in the terminal metal piece19connected to the final side lead wire16bof the coil strand of the coil16in each of the single coil units11A and11B. This makes both of the coils16in their respective single coil units11A and11B connected in series as is shown in the connection diagram ofFIG. 5C.

Furthermore, the connector22attached to one end of the extension lead for external connection21(seeFIG. 6B) is made to have the tab terminal19cinserted which is formed in the terminal metal piece19connected to the initial side lead wire16aof the coil strand of the coil16in each of the single coil units11A and11B. This makes the extension lead for external connection21connected to the coil16in each of the single coil units11A and11B, by which the assembly of the double coil unit11is completed. To the other end of the extension lead for external connection21, a solderless terminal23(seeFIG. 7C) is attached which is to be connected to a control terminal of an electromagnetic contactor. The double coil unit11is, like the related one, mounted on a stationary core of an operating electromagnet (double leg core) to be assembled in an electromagnetic contactor.

As is apparent from the foregoing explanations, the double coil unit11in the example shown in the attached drawings requires no troublesome manual work as that carried out in forming the related structure explained with reference toFIG. 9AtoFIG. 10Din which each of the initial side lead wire16aand the final side lead wire16bof the coil16is temporarily fastened with a piece of the adhesive tape18for each of the single coil units11A and11B. The coil winding work can be carried out by using an automatic wire winding machine with manual work of only winding each of the initial side lead wire16aand the final side lead wire16bof the coil16around the corresponding coil connecting arm19bformed in the terminal metal piece19.

Moreover, also in connecting the single coil units11A and11B in series or in connecting the extension lead for external connection21to the initial side lead wire16aof the coil16, there is required no troublesome manual work such as that of twisting together the wires to be connected with each other and soldering them. Namely, the extension leads can be connected by a single operation with plug-in ease of only making the connector22of each of the extension lead for series connection20and the extension leads for external connection21have the corresponding tab terminal19cin the terminal metal piece19inserted therein. This can reduce working man-hours of manual work to considerably lower the cost compared with that of the related structure.

Although the example shown in the attached drawings is explained about the double coil unit formed by combining two sets of single coil units, the structure of the terminal metal piece19press fitted to the flange of the bobbin15for being attached thereto, the method of assembling the coil unit using the terminal metal piece19, and further the structure for wiring according to the invention, in which the plug-in connection is made with the tab terminal19cof the terminal metal piece19inserted into the connector22of the extension lead, can be of course applied to those of a single coil unit mounted on the central leg of an E-shaped stationary core.

This application is based on, and claims priority to, Japanese Patent Application No. 2008-240406, filed on Sep. 19, 2008. The disclosure of the priority application, in its entirety, including the drawings, claims and specification thereof, is incorporated herein by reference.