Electrical equipment to be coupled to printed circuit board

Abstract: The electrical equipment, which are to be coupled to a printed circuit board, provides insulation ribs (13e), (13f), (13g), (13h) formed projecting from a face between terminal plates (109), (209), (309), (110), (210), (310) which are provided on the upper face of said electrical equipment. The insulation ribs (13e), (13f), (13g), (13h) are inserted to oblong holes (66e), (66f), (66g), (66h) of the printed circuit board (66) when the electrical equipment is coupled to the printed circuit board (66). As a result, insulation distances, namely creepage distance, between terminal plates (109), (209), (309), (110), (210), (310) are secured along the height of the insulation ribs (13e), (13f), (13g), (13h) projecting from the upper face of the terminal plates (109), (209), (309), (110), (210), (310).

Description: The present invention relates to an electrical equipment which is to be coupled to a printed circuit board so as to achieve a rationalization of wiring workload for the electrical equipment. The following is an explanation of a conventional semi-conductor circuit apparatus, for example, a conventional inverter apparatus, which is wired by a conventional printed circuit board. FIG.9 is a basic circuit diagram of a conventional inverter apparatus. In FIG.9, three-phase alternating current of power-frequency, which is inputted through power terminals 54, is converted into a direct current by a diode module 51. The converted direct current is smoothed by a smoothing capacitor 53, and is inputted into a transistor module 52. The direct current supplied to the transistor module 52 is inverted to three-phase alternating current having a desired frequency, and the inverted alternating current is output from load terminals 55. The transistor module 52 is controlled by a control device 56. The above-mentioned inverter apparatus provides a resistor 57 for limiting rush current in order to control the rush current when the inverter apparatus starts to operate. If the resistor 57 for limiting the rush current was held active during operation of the inverter apparatus, voltage drop due to the operating resistor 57 would be generated in the inverter apparatus. For solving the above-mentioned problem, the inverter apparatus is constructed so as to operate the resistor 57 for limiting the rush current only at the starting time of the inverter apparatus. Therefore, an electromagnetic switch 58, which provides a short circuit between the input terminal and output terminal of the resistor 57, is provided to short-circuit the resistor 57 during the operation time of the inverter apparatus except the starting interval. Such an inverter circuit of an inverter apparatus, which is connected by a printed circuit board, is disclosed in the Japanese published unexamined utility model application No. Sho 60-83292 (Jikkai Sho 60-83292) as a semi-conductor circuit apparatus. The semi-conductor circuit apparatus is shown in FIG.10 which is a cross sectional side view showing the structure of the semi-conductor circuit apparatus. In FIG.10, parts and components corresponding to the circuit shown in FIG.9 have the same numerals. As shown in FIG.10, main circuit devices, such as the diode module 51, the transistor module 52 and the smoothing capacitor 53 etc. in the above-mentioned inverter circuit, are held inside a base 59. The above-mentioned main circuit devices which are held in the base 59 are covered by a cover 65 to be disposed in the inverter apparatus as the semi-conductor circuit apparatus. Radiating fins 60 are provided on the rear face of the base 59 to cool the rising temperature of the main circuit device due to the current flowing therein. The main circuit devices are electrically connected to one another by a main circuit printed board 66. Connecting terminals 51a, 52a, 53a of the main circuit devices are fixed to the main circuit printed board 66 by bolts 51b, 52b, 53b, respectively. As shown in FIG.10, the control device 56 for controlling the transistor module 52 is mounted on a control circuit printed board 70 which is electrically and mechanically connected to the main circuit printed board 66 by connectors 69. In the above-mentioned semi-conductor circuit apparatus, each insulation distance between the connecting terminals 51a, 52a, 53a, 53a of the main circuit device is defined by the distance along the surface of the main circuit printed board 66 which is made of a laminate plate formed by an insulation sheet. If floating dust or suspended particles stick on the main circuit printed board 66 and accumulate as dust etc. absorbed moisture, the insulating condition of the surface of the main circuit printed board 66 becomes deteriorated. In view of such state of the main circuit printed board 66, the distance between the connecting terminals of the main circuit devices in the conventional semi-conductor circuit apparatus should be set longer so as to ensure a good insulation between the connecting terminals 51a, 52a, 53a, 53a. As a result, the conventional semi-conductor circuit apparatus has been formed with large size. As shown in FIG.10, since there is an aperture A between the upper face of the main circuit devices and the rear face of the main circuit printed board 66, the floating dust or suspended particles are apt to be collected in the aperture A. As a result, the insulation in the aperture A is deteriorated by the accumulated dust etc. between the connecting terminals for the three phases or the connecting terminals and main circuit printed board 66. In order to solve the above-mentioned problem, a "printed circuit board" which is shown in FIG.11 is disclosed in the Japanese published unexamined utility model application No. 59-189257 (Jikkai Sho 59-189257). FIG.11 is a cross sectional view showing a printed circuit board 508 on which a relay 505 is mounted. Connecting terminals 506, 507 of the relay 505 are inserted into holes 512, 513 of the printed circuit board 508 so as to be electrically connected to copper foils 509, 510 as conductor foil which is printed on the printed circuit board 508. The printed circuit board 508 provides a projection 511 formed in rib shape between two holes 506 and 507 to isolate two copper foils 509 and 510. In other words, the distance for insulation, namely the creepage distance, between the connecting terminals 506, 507 becomes long by providing the projection 511 made of insulation material. However, the above-mentioned printed circuit board 508 can not be manufactured by a normal etching step or drilling step of copper-clad laminate board which is generally utilized for manufacturing the general printed circuit board having a flat surface. Therefore the printed circuit board 508 has to be manufactured by special manufacturing steps for printing the circuit on the insulation board. As a result, to use such printed circuit board increases the manufacturing cost of the apparatus. An object of the present invention is to provide an electrical equipment to be coupled to a printed circuit board having a proper distance for insulation between connecting terminals of the main circuit devices even when floating dust or suspended particles are stuck to the printed circuit board etc. and absorbs moisture, without increase of manufacturing cost. In order to achieve the above-mentioned object, an electrical equipment in accordance with claim 1 is provided. According to the present invention, since the electrical equipment for a printed circuit board provides insulation ribs which are provided between terminal plates and are formed so as to project above the upper face of the printed circuit board, the insulation distance between terminal plates is large due to the insulation rib even if the printed circuit board would be stained by dust and moistured damp dust etc. While the novel features of the invention are set forth particularly in the appended claims, the invention, both as to organization and content, will be better understood and appreciated, along with other objects and features thereof, from the following detailed description taken in conjunction with the drawings. FIG.1 is a perspective view showing an electromagnetic contactor embodying the present invention. FIG.2 is a front view showing the electromagnetic contactor of FIG.1. FIG.3 is a top plan view showing the electromagnetic contactor of FIG.1. FIG.4 is a cross sectional view taken along line IV-IV of FIG.3. FIG.5 is a side elevation view, partly in cross section view taken on line V-V of FIG.3. FIG.6 is a perspective view showing a combination of a main circuit printed board and the electromagnetic contactor of FIG.1. FIG.6 is a cross sectional view showing a creepage distance, i.e. an insulation distance between terminal plates of the electromagnetic contactor. FIG.8 is a front view showing another electromagnetic contactor embodying the present invention. FIG.9 is the basic circuit diagram of a conventional inverter apparatus. FIG.10 is a cross sectional view showing the structure of the conventional semi-conductor circuit apparatus. FIG.11 is a cross sectional view showing a relay mounted on the printed circuit board. It will be recognized that some or all of the Figures are schematic representations for purposes of illustration and do not necessarily depict the actual relative sizes or locations of the elements shown. Hereafter, an electromagnetic contactor as a preferred embodiments of the electrical equipment for a printed circuit board of the present invention is elucidated with reference to the accompanying drawings of FIGs. 1 to 7. FIG.1 is a perspective view showing the electromagnetic contactor embodying the present invention FIG.2 is a front view of the electromagnetic contactor of FIG.1. FIG.3 is a top plan view showing the electromagnetic contactor of FIG.1. FIG.4 is a cross sectional plan view taken along line IV-IV of FIG.3. FIG.5 is a side elevation view, partly in cross section view taken along line V-V of FIG.3. FIG.6 is a perspective view showing a combination of a main circuit printed board and the electromagnetic contactor of FIG.1. In FIG.1 to FIG.5, the electromagnetic contactor comprises a fitting base 1 for mounting on a base of an apparatus, i.e. inverter apparatus, a contactor case 2 for receiving a contact unit of the electromagnetic contactor. As shown in FIGs. 1 to 3, input terminal plates 109, 209, 309 and output terminal plates 110, 210, 310 for connecting a three-phase circuit are provided on the upper part of the contactor case 2. Two control terminals 116, 117 are also provided on the upper part of it. Both ends of the magnetic coil 3 shown in FIG.4 are electrically connected to the control terminals 116, 117, respectively. In FIG.4, a stationary core 4 is provided to face a movable core 5 with a predetermined interval I between the stationary core 4 and the movable core 5. A cross bar 6 which is made of insulation material is connected to the movable core 5. The cross bar 6 has a through-hole 6a which slidably holds a movable contact 8 upward and downward with respect to FIG.4. The cross bar 6 is guided in a manner to slide upward and downward by the above-mentioned contactor case 2. A spring 7 for applying pressure to the movable contact 8 is constituted by a compression coil spring. Movable contact points 8a, 8b which are provided on both ends of the movable contact 8 are provided so as to face fixed contact points 9a, 10a of stationary contacts 9, 10. As shown in FIG.4, the movable contact points 8a, 8b are arranged, in open state, to have a predetermined interval J between the movable contact points 8a, 8b and the fixed contact points 9a, 10a. The fixed contact points 9a, 10a are screwed on one end of the stationary contacts 9, 10, respectively. An arc cover 13 which is provided at an upper part of the contactor case 2 has metal arc runners 14, 15 therein for extinguishing an arc generated between movable contact points 8a, 8b and fixed contact points 9a, 10a. The stationary contacts 9, 10, movable contact 8 and arc runners 14, 15 are provided to arrange three sets abreast corresponding to three phases of the circuit. In FIG.4, the input and output terminal plates 209, 210 which are formed in U-shape have fixed contact points 9a, 10a on the lower end parts of the input and output terminal plates 209, 210. Top faces of the upper end parts of the input and output terminal plates 209, 210 are arranged on substantially even level with an upper face of the arc cover 13 which is unified with the contactor case 2. The height to the top faces of the input and output terminal plates 209, 210 from the bottom face of the electromagnetic contactor is shown by H1 in FIG.4. The input terminal plates 109, 209, 309, and output terminal plates 110, 210, 310 are provided to form three sets abreast corresponding to three-phase of the circuit. As shown in the top plan view of FIG.3, four insulation ribs 13e, 13f, 13g, 13h made of insulation materials are provided on an upper face of the arc cover 13. Two insulation ribs 13e, 13f are arranged between three input terminal plates 109, 209, 309, and the others, namely two insulation ribs 13g, 13h are arranged between three output terminal plates 110, 210, 310. The height of the respective insulation ribs 13e, 13f, 13g, 13h from the top faces of the input terminal plates 109, 209, 309 and output terminal plates 110, 210, 310 is shown by β in FIG.2. Accordingly, a height H2 of the electromagnetic contactor is given by following formula (1): H2 = H1 + β wherein H1 is the height to the top face of the terminal plates 109, 209, 309, 110, 210, 310 from the rear face of the fitting base 1. As shown in FIG.2, the control terminal plates 116, 117 which are formed in U-shape are provided on the upper part of the electromagnetic contactor. Lower ends of the control terminal plates 116, 117 are connected to lead wires 3a, 3b of the magnetic coil 3, respectively. The upper end parts of the control terminal plates 116, 117 have threaded holes 116b, 117b for connecting a control circuit. A spring 20 shown in FIG.5 is provided to apply pressure to the connecting unit of the cross bar 6 and the movable core 5 upward of FIG.5. FIG.6 shows a perspective view of a combination of a main circuit printed board 66 and the above-mentioned electromagnetic contactor. As shown in FIG.6, four oblong apertures 66e, 66f, 66g, 66h are provided in the main circuit printed board 66 for insertion of the above-mentioned insulation ribs 13e, 13f, 13g, 13h of the electromagnetic contactor. The oblong apertures 66e, 66f, 66g, 66h are similar in plane shape to the insulation ribs 13e, 13f, 13g, 13h. Next, the operation of the above-mentioned electromagnetic contactor embodying the present invention is described with reference to FIGs. 4 and 5. When the magnetic coil 3 is energized by applying a voltage through the control terminals 116, 117, the movable core 5 is attracted to the stationary core 4 by the magnetic field of the magnetic coil 3. The connecting unit of the movable core 5 and the cross bar 6 is slid downward against the tension of the spring 20 shown in FIG.5. As a result, the movable contact points 8a, 8b which are slid by the moving cross bar 6 touch the fixed contact points 9a, 10a. In the case of the open state shown in FIG.4, the core interval I between the stationary core 4 and the movable core 5 is designed to become larger than the contact interval J between the movable contact points 8a, 8b and the fixed contact point 9a, 10a. Therefore, the movable contact points 8a, 8b are further slid downward from the touch position to the fixed contact points 9a, 10a so as to steadily contact the fixed contact points 9a, 10a. At the same time, the spring 7 is compressed by the cross bar 6, and the pressure of the compressed spring 7 is applied to the movable contact 8 as contact pressure therefor. As mentioned above, the closing operation of the electromagnetic contactor is thus finished. Next, when the voltage is removed from the magnetic coil 3, the attraction between the stationary core 4 and the movable core 5 is extinct. As a result, the connecting unit of the movable core 5 and the cross bar 6 is moved upward by the pressure of the spring 20, and the contact between the movable contact points 8a, 8b and the fixed contact points 9a, 9b is broken. An arc which is generated between the movable contact points 8a, 8b and the fixed contact points 9a, 9b at the above-mentioned breaking time is attracted to the arc runners 14, 15, and is cooled to extinguish. By the above-mentioned way, the breaking operation of the electromagnetic contactor finishes. The following is an explanation of the coupling operation of the main circuit printed board 66 and the above-mentioned electromagnetic contactor with reference to the accompanying drawing of FIG.6. As shown in FIG.6, the electromagnetic contactor is directly connected to the main circuit printed board 66 by bolts 68 which are screwed up into threaded holes 109b, 209b, 309b, 110b, 210b, 310b of the input terminal plates 109, 209, 309, and the output terminal plates 110, 210, 310, respectively, through terminal holes 80a of the printed circuit 80 in the main circuit printed board 66. The wiring for the electromagnetic contactor is finished by only connecting the electromagnetic contactor to the main circuit printed board 66. In the above-mentioned coupling operation for the wiring, the insulation ribs 13e, 13f, 13f, 13h of the electromagnetic contactor are inserted in the oblong apertures 66e, 66f, 66g, 66h of the main circuit printed board 66. Therefore, the distance for insulation, namely creepage distance, between the terminals of the printed circuit 80 in the main circuit printed board 66 is long due to the projection of the insulation ribs 13e, 13f, 13g, 13h from the upper face of the main circuit printed board 66. FIG.7 is a cross sectional view showing the creepage distance between the output terminal plates 210, 310. As shown in FIG.7, the creepage distance, i.e. the insulation distance between the output terminal plates 210, 310 is longer by at least two-times (2β) of the projection height β of the insulation ribs 13h than the interval X along a shortest straight line between the output terminal plates 210, 310. Therefore, since the insulation distance (creepage distance) becomes long by providing the insulation ribs 13e, 13f, 13g, 13h, the interval X along a shortest straight line distance between the terminals can be made short. As a result, an apparatus having the electrical equipment to be coupled to a printed circuit board embodying the present invention can be provided to have small outer dimensions, and can be manufacture by low manufacturing cost. And, since the insulation ribs 13e, 13f, 13g, 13h of the electrical equipment are provided to couple with the oblong apertures 66e, 66f, 66g, 66h of the printed circuit board 66, the aforementioned conventional printed circuit board having projections and hence being difficult to manufacture is no longer necessary at all. The above-mentioned flat printed circuit board 66 having the oblong apertures 66e, 66f, 66g, 66h for the inserting insulation ribs 13e, 13f, 13g, 13h can be easily manufactured at low manufacturing cost. Even if floating dust or suspended particles stick on the main circuit printed board 66, and accumulated dust etc. absorbs moisture, the insulation distance between the terminals of the main circuit printed board 66 can be maintained by projecting the insulation ribs 13e, 13f, 13g, 13h from the oblong apertures 66e, 66g, 66g, 66h of the main circuit printed board 66. FIG.8 shows a front view of another electromagnetic contactor embodying the present invention. Parts and components corresponding to the aformentioned embodiment are shown by the same numerals and marks, and the description thereof made in the aforementioned embodiment similarly applies. Differences and features of this embodiment from the aforementioned embodiment are as follows. As shown in FIG.8, the electromagnetic contactor provides the insulation ribs 130g, 130h having a projection height β from the upper face of the output terminal plates 110, 210, 310 and input terminal plates. The projection height β is selected smaller than the thickness T of the main circuit printed board 66. Therefore, when a connecting conductor 100 is provided to connect the three-phase output terminal plates 110, 210, 310, and when another connecting conductor 100 is provided to connect the three-phase input terminal plates, in case of the aforementioned inverter circuit shown in FIG.9, the connecting conductors 100 can be mounted closely on the main circuit printed board 66 without interference with the insulation ribs 130g, 130h and so on. Apart from the above-mentioned embodiment wherein the insulation ribs are provided between the terminal plates of the electromagnetic contactor as an electrical equipment of the present invention, a modified embodiment may be such that an insulation rib is provided between a terminal plate and a control terminal plate of the electrical equipment. Apart from the above-mentioned embodiment wherein the insulation ribs are provided on the electromagnetic contactor, another modified embodiment may be such that the insulation ribs are provided on the terminal section of another electrical equipment, such as a solid-state contactor, a power relay, a diode module, a transistor module, a capacitor or the like, whereby the electrical equipment can improve the reliability of an apparatus which uses the electrical equipment to be coupled to the printed circuit board.

Claims: An electrical equipment to be coupled to a printed circuit board (66) comprising: a case (2) which has at least one substantially flat face, plural terminal plates (109; 209; 309; 110; 210; 310; 116; 117) which are to be connected to circuit parts on said printed circuit board, at least a part of each terminal plate being formed on said substantially flat face, said part each having connecting means (109b; 209b; 309b; 110b; 210b; 310b; 116b; 117b) for connection to said printed circuit board (66), and at least one insulation rib (13e, 13f, 13g, 13h) which is projecting above said otherwise substantially flat face between said plural terminal plates (109; 209; 309; 110; 210; 310; 116; 117) as means to assure a long creepage distance between said plural terminal plates. An electrical equipment in accordance with claim 1, wherein each insulation rib (13e, 13f, 13g, 13h) is adapted for insertion into a corresponding hole (66e, 66f, 66g, 66h) of said printed circuit board (66) when coupling said electrical equipment to said printed circuit board (66). An electrical equipment in accordance with claim 1 or 2, wherein said at least one insulation rib (13e, 13f, 13g, 13h) has such a height (β) that it projects from said substantially flat face but is smaller than the thickness (T) of said printed circuit board (66). An electrical equipment in accordance with claim 1, 2 or 3, wherein said plural terminal plates (109; 209; 309; 110; 210; 310; 116; 117) are three-phase input terminal plates, three-phase output terminal plates and control terminal plates of an electromagnetic contactor. An electrical equipment in accordance with claim 4, wherein said three-phase input terminal plates (109; 209; 309) are adapted for electrical connection to each other by one conductor (100) which is tightly mounted on said printed circuit board (66), and said three-phase output terminal plates (110; 210; 310) are adapted for electrical connection by other conductor (100) which is mounted tightly on said printed circuit board (66).

Inventors: OOTSUKA SHIGEHARU, SAKO YUJI, OOTSUKA, SHIGEHARU, SAKO, YUJI, Ootsuka, Shigeharu, c/o Nagoya Seisakusho, Sako, Yuji, c/o Nagoya Seisakusho, Mitsubishi
Applicants: MITSUBISHI ELECTRIC CORP, MITSUBISHI DENKI KABUSHIKI KAISHA
Application year: 1991
Main classification: H01H1
IPC codes: H01H1, H01H50, H01H9