CONNECTION STRUCTURE OF ELECTRIC APPARATUS

Abstract

 There is provided a connection structure of an electric apparatus capable of accurately positioning and connecting a terminal to be connected to a screw terminal of the electric apparatus. A connection structure of an electric apparatus is provided electrically connecting each of screw terminals formed in the electric apparatus and a terminal to be connected formed in a terminal component for a main terminal being a member to be connected. The connection structure includes a rotation-stop mechanism engaged mutually with the screw terminal and the terminal to be connected.

Description

BACKGROUND OF THE INVENTION

Field of the Invention

[0001] The present invention relates to a connection structure of an electric apparatus having screw terminals, such as a thermal overload relay, an electromagnetic contactor or the like.

Description of the Related Art

[0002] This type of connection structure of electric apparatus includes, for example, a thermal overload relay having three main terminals and four auxiliary terminals as described in PTL 1. Each of these terminals includes a screw terminal including a terminal plate formed with a female screw and a terminal screw threadedly engaged in the female screw of the terminal plate. A crimp terminal mounted to a connection cord, and a core wire exposed from the coat of the connection cord are normally connected to the screw terminal. The connection of the crimp terminal and the core wire in this case is done by threadedly engaging a terminal screw inserted through a washer with a female screw part of the terminal plate and fastening it in a state in which the crimp terminal or the core wire is placed on the terminal plate. Further, the screw terminal is connected with an electric apparatus such as other electromagnetic contactor or an intermediate component called an add-on component in addition to the crimp terminal or the core wire of the cord.

Citation List

Patent Literature

[0003] PTL 1: JP 2014-107023 A

SUMMARY OF THE INVENTION

[0004] Meanwhile, when members to be connected are individually connected to the screw terminals provided in the electric apparatus, as described above, a terminal to be connected of each member to be connected is placed on the terminal plate of each screw terminal, and thereafter the terminal screw inserted through the washer is threadedly engaged with its corresponding female screw part and then fastened. Therefore, when the fastening is started with the terminal screw and the washer kept in contact with the terminal to be connected, the terminal to be connected is co-rotated with the rotation of the terminal screw. Accordingly, a problem arises in that the connecting position of the member to be connected is shifted from the normal connecting position. Therefore, when a terminal cover covering each member to be connected is mounted, there occurs a case where the mounting of the terminal cover becomes difficult. Further, there occurs a risk that with its co-rotation, the member to be connected collides with a partition wall provided in the electric apparatus to damage the partition wall, thus degrading insulation performance and disabling the terminal connection at the normal position.

[0005] Thus, the present invention has been made by paying attention to the problems in the related art and aims to provide a connection structure of an electric apparatus capable of accurately positioning and connecting a terminal to be connected to a screw terminal of the electric apparatus .

[0006] To achieve the above object, one embodiment of a connection structure of an electric apparatus according to the present invention is a connection structure of an electric apparatus electrically connecting a screw terminal formed in the electric apparatus and a terminal to be connected formed in a member to be connected. The connection structure is provided with a rotation-stop mechanism engaged mutually with the screw terminal and the terminal to be connected.

[0007] According to one embodiment of the present invention, since a rotation-stop mechanism is provided at a screw terminal and a terminal to be connected, the rotation-stop mechanism is capable of stopping co-rotation of the terminal to be connected and performing its accurate positioning when a terminal screw is fastened in a state in which the terminal to be connected is placed on a terminal plate of the screw terminal.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] 

FIG. 1 is a front view of an electric apparatus illustrating one embodiment of the present invention;

FIG. 2 is a back view of the electric apparatus illustrating the one embodiment of the present invention;

FIG. 3 is a plan view of the electric apparatus illustrating the one embodiment of the present invention;

FIG. 4 is a perspective view illustrating a thermal overload relay;

FIG. 5 is a plan view illustrating a state in which a terminal cover is detached;

FIG. 6 is a perspective view illustrating a state in which the terminal cover is detached;

FIG. 7 is a cross-sectional view taken on line VII-VII of FIG. 1;

FIG. 8 is a cross-sectional view taken on line VIII-VIII of FIG. 3;

FIG. 9 is a cross-sectional view taken on line IX-IX of FIG. 3;

FIG. 10 is a cross-sectional view taken on line X-X of FIG. 3;

FIG. 11 is a cross-sectional view taken on line XI-XI of FIG. 3; and

FIG. 12 is a front view of the terminal cover.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009]  One embodiment of the present invention will next be described with reference to the accompanying drawings. In the following description of the drawings, the same or like portions are respectively denoted by the same or like reference numerals. However, the drawings are schematic and may be different from the actual ones in terms of the relationship between the thickness and plane dimensions, the rate of thicknesses between respective layers, etc.

[0010] Accordingly, specific thicknesses and dimensions should be determined in consideration of the following description. Further, it is of course that portions different in terms of mutual dimensional relationships and ratios are included even between the drawings.

[0011] Further, the embodiment to be described below illustrates an apparatus or a method for embodying the technical idea of the present invention. The technical idea of the present invention is not indented to specify the materials, shapes, structures, and arrangements and the like of components to those described below. The technical idea of the present invention can be modified in various ways within the technical scope defined by claims described in the scope of claims.

[0012] One embodiment of the present invention will be described by taking a thermal overload relay being one of electric apparatuses.

[0013] A thermal overload relay (thermal relay) 10 includes three external connection pins 11u, 11v, and 11w protruding downward from its upper part and arranged in parallel, as illustrated in FIG. 1. These external connection pins 11u, 11v, and 11w are inserted through spring terminals formed in another electric apparatus to be connected, e.g., an electromagnetic contactor.

[0014] Also, the thermal overload relay 10 includes three main terminals 12u, 12v, and 12w arranged on its back surface in a parallel state as seen in a horizontal direction, as illustrated in FIG. 4. The main terminal 12u includes right and left side surfaces fixed in a state of being in contact with a side wall 13a and a partition wall 13b extending in the longitudinal direction of the thermal overload relay 10, as illustrated in FIG. 6. The main terminal 12v includes right and left side surfaces fixed in a state of being in contact with partition walls 13b and 13c extending in the longitudinal direction of the thermal overload relay 10, as illustrated in FIG. 6. The main terminal 12w includes right and left side surfaces fixed in a state of being in contact with partition walls 13c and 13d extending in the longitudinal direction of the thermal overload relay 10, as illustrated in FIG. 6.

[0015] Further, the thermal overload relay 10 includes, as illustrated in FIG. 4, auxiliary terminals 14a and 14b, and 14c and 14d arranged on its back surface stepwise in two stages outside the main terminal 12w in a state of being made parallel in the horizontal direction two by two. These auxiliary terminals 14a through 14d also include right and left side surfaces fixed in a state of being in contact with the partition wall 13d, a partition wall 13e, and a side wall 13f formed in the thermal overload relay 10 and extending in the longitudinal direction of the thermal overload relay 10.

[0016] These main terminals 12u through 12w and auxiliary terminals 14a through 14d respectively have a screw terminal structure including a terminal plate 15 and a terminal screw 16. The terminal plate 15 is made of a conductive metal material. The terminal plate 15 is formed in its center part with a cylindrical part 17 downwardly protruding by burring processing as illustrated in an enlarged form in FIG. 9. A female screw part 18 is formed on the inner peripheral surface of the cylindrical part 17. The terminal screw 16 is mounted with a washer 19 and threadedly engaged into the female screw part 18.

[0017] Each terminal plate 15 is formed with a protrusion 20 semicircular in section extending in the right and left direction as seen in its radial direction through the center of the female screw part 18 as illustrated in an enlarged form in FIG. 8. This protrusion 20 serves as a first engagement part forming a rotation-stop mechanism RS. The protrusion 20 is formed by emboss processing from its lower side upon press-processing the terminal plate 15.

[0018] The terminal screw 16 is threadedly engaged into the female screw part 18 of the terminal plate 15. The terminal screw 16 rotatably holds the washer 19 on its head side. The washer 19 can also be formed independently of the terminal screw 16.

[0019] Also, the thermal overload relay 10 includes three bimetals 21u, 21v, and 21w thereinside as illustrated in FIG. 7. These bimetals 21u through 21w are respectively heated when a current flowing between the external connection pins 11u through 11w and between the main terminals 12u through 12w respectively becomes in an overcurrent state, and hence brought into a trip state of shutting off a current-carrying path by a shifter, a release lever or a contact reversing mechanism not illustrated in the drawing.

[0020] Further, the thermal overload relay 10 includes a trip-state releasing reset bar 21 protruding from its upper surface as illustrated in FIG. 3.

[0021] The main terminals 12u through 12w and auxiliary terminals 14a through 14d of the thermal overload relay 10 are connected with a spring terminal component 31 being a member to be connected serving as an add-on component enabling connection to the thermal overload relay 10 by the spring terminals.

[0022] The spring terminal component 31 includes terminal components 32 for the main terminals, and terminal components 33A and 33B for the auxiliary terminals.

[0023] There are provided three terminal components 32 for the main terminals to be connected individually to the main terminals 12u through 12w as illustrated in FIGS. 4, 5, and 8.

[0024] Each protruding 32 has an insulating case 35 molded of a synthetic resin material, for example. As illustrated in FIGS. 5 and 9, the insulating case 35 is formed of a bottom plate part 35a, a front plate part 35b, a rear plate part 35c, and a left side plate part 35d in the form of an approximately U-shape as seen from its side surface.

[0025] The bottom plate part 35a is formed in a rectangular shape as seen from its plane surface extending in its longitudinal direction. The bottom plate part 35a is formed with a downwardly protruding engagement protrusion 35a1 at its lower surface on the front end side of the bottom plate part 35a as illustrated in FIG. 9. The engagement protrusion 35a1 is engaged in an engagement hole 57 of a terminal cover 51 to be described later.

[0026] The front plate part 35b includes a first vertical plate portion 35b1 extending upward from the front end of the bottom plate part 35a, a second vertical plate portion 35b2 separated upward and frontward from the upper end of the vertical plate portion 35b1 and extending upward, and a curved plate portion 35b3 curved and extended upward and backward from the second vertical plate portion 35b2.

[0027]  The rear plate part 35c is extended upward from the rear end of the bottom plate part 35a to the upper end of the second vertical plate portion 35b2 of the front plate part 35b.

[0028] The left side plate part 35d extends upward from the left side end of the bottom plate part 35a and includes a front-side plate portion 35d1 approximately equal in height to the upper end of the curved plate portion 35b3 of the front plate part 35b, and a rear-side plate portion 35d2 approximately equal in height to the upper end of the rear plate part 35c. An annular circumferential wall 36 protruding to its right end side is formed on its inner surface of the left side plate part 35d.

[0029] The annular circumferential wall 36 includes a bottom wall portion 36a, a front wall portion 36b, an upper wall portion 36c, and a rear wall portion 36d continuing to each other as illustrated in FIGS. 5 and 9. The bottom wall portion 36a is separated by a predetermine interval from and opposite to the bottom plate part 35a.

[0030] The front wall portion 36b extends upward from the front end of the bottom plate part 35a and is separated by a predetermined interval from and opposite to the front plate part 35b. The front wall portion 36b is formed with a step portion 36e rearwardly shifted to the bottom wall portion 36a side and formed with an engagement protrusion portion 36f protruding forward at its intermediate portion as viewed in the vertical direction.

[0031]  The upper wall portion 36c slightly extends backward from the upper end of the front wall portion 36b. The rear wall portion 36d includes a vertical wall portion extending downward from the rear end of the upper wall portion 36c, an inclined wall portion extending obliquely backward from the vertical wall portion, and a vertical wall portion extending downward from the inclined wall portion and reaching the bottom wall portion 36a.

[0032] Further, the insulating case 35 holds a terminal to be connected 37 formed of a conductive metal material such as an iron material or the like as illustrated in FIG. 8. The terminal 37 to be connected 37 includes a terminal part 37a and a U-shaped conductive plate unit 37b continuing to the terminal part 37a.

[0033] The terminal part 37a is protruding and extend forward through a window portion 35b4 between the first and second vertical plate portions 35b1 and 35b2 of the front plate part 35b in the insulating case 35 and formed with a through hole 37c allowing the terminal screw 16 to be inserted therethrough at its tip as illustrated in an enlarged form in FIG. 9. Further, the terminal part 37a is formed on its lower surface side with an engagement groove 37d triangular in section extending in the horizontal direction as seen in the radial direction of the through hole 37c centering on the through hole 37c as illustrated in an enlarged form in FIG. 8. The engagement groove 37d is engaged with the protrusion 20 formed at the terminal plate 15 of each of the main terminals 12u through 12w to configure a second engagement part of the rotation-stop mechanism RS.

[0034] The U-shaped conductive plate unit 37b includes a front plate portion 37b1 extending downward from the rear end of the terminal part 37a, a bottom plate portion 37b2 extending backward from the lower end of the front plate portion 37b1, and a rear plate portion 37b3 extending upward from the rear end of the bottom plate portion 37b2. An engagement plate portion 37b4 protruding to the right is formed at the right side surface of the bottom plate portion 37b2 as illustrated in FIG. 4. An engagement protrusion 37b5 protruding forward is formed on the inner surface of the rear plate portion 37b3 on its upper end side.

[0035] Then, the terminal to be connected 37 is configured to hold the U-shaped conductive plate unit 37b in the insulating case 35 along the inner surfaces of the front plate part 35b, the bottom plate part 35a, and the rear plate part 35c. Here, in the U-shaped conductive plate unit 37b, the front plate portion 37b1 and the bottom plate portion 37b2 are inserted between the front plate part 35b and bottom plate part 35a of the insulating case 35 and the front wall portion 36b and bottom wall portion 36a of the annular circumferential wall 36 and held in the insulating case 35.

[0036] Further, a terminal spring 38 formed of a conductive spring material in an inverted U-shape is held in the insulating case 35 as illustrated in FIG. 9. The terminal spring 38 includes a front plate part 38a, a curved plate part 38b, and an inclined plate part 38c. The front plate part 38a extends up to thereabove from the step portion 36e of the front wall portion 36b of the annular circumferential wall 36 along the front wall portion 36b. The curved plate part 38b is bent from the upper end of the front plate part 38a and passes between the curved plate portion 35b3 of the front plate part 35b of the insulating case 35 and the upper wall portion 36c of the annular circumferential wall 36 to extend to the rear side. The inclined plate part 38c is bent and extended in a dogleg shape rearwardly downward from the rear end of the curved plate part 38b, and has a tip engaged with the lower end side of the engagement protrusion 37b5 of the U-shaped conductive plate unit 37b.

[0037] The terminal spring 38 and the rear plate portion 37b2 of the U-shaped conductive plate unit 37b of the terminal to be connected 37 configure a spring terminal 39.

[0038] Further, the terminal components 33A and 33B for the auxiliary terminals are shaped in the form of a similar shape smaller than the above-described terminal component 32 for the main terminal as illustrated in FIG. 10. Thus, although the terminal components 33A and 33B for the auxiliary terminals are not described in detail, they respectively include an insulating case 45, an annular circumferential wall 46, a terminal to be connected 47, and a terminal spring 48. Here, the terminal to be connected 47 is formed with an engagement groove 47x as a second engagement part triangular in section, engaged with the protrusion 20 formed at the terminal plate 15 of each of the main terminals 12u through 12w of the thermal overload relay 10 in a manner similar to the terminal to be connected 37 of the terminal component 32 for the main terminal as illustrated in an enlarged form in FIG. 10. The engagement groove 47x and the protrusion 20 configure a rotation-stop mechanism RS. Incidentally, the terminal components 33A and 33B for the auxiliary terminals respectively include the two terminal springs 48 disposed in parallel.

[0039] Then, the terminal component 33B for the auxiliary terminal mounted to each of the auxiliary terminals 14c and 14d on the lower stage side is set longer in terms of the length of the terminal to be connected 47 than the terminal component 33A for the auxiliary terminal mounted to each of the auxiliary terminals 14a and 14b on the upper stage side. Thus, as illustrated in FIG. 10, when the terminal components 33A and 33B for the auxiliary terminals are respectively mounted to the auxiliary terminals 14a and 14b, and 14c and 14d, the terminal springs 48 are configured to prevent their engagement positions from overlapping each other in the vertical direction.

[0040] Further, an engagement protrusion 45x protruding downward at the lower surface of the insulating case 45 is formed on the front end side of a bottom plate part 45a of the insulating case 45 as illustrated in FIG. 11. The engagement protrusion 45x is engaged in an engagement hole 59 formed in an elongated groove 58 of the terminal cover 51 to be described later via a through hole formed in a U-shaped conductive plate unit 47b of the terminal to be connected 47.

[0041] Then, the terminal cover 51 is mounted so as to cover all of the terminal components 32 for the main terminals and the terminal components 33A and 33B for the auxiliary terminals in a state in which the terminal components 32 for the main terminals are individually mounted to the main terminals 12u through 12w of the thermal overload relay 10, and the terminal components 33A and 33B for the auxiliary terminals are individually mounted to the auxiliary terminals 14a and 14b, and 14c and 14d.

[0042] In the terminal cover 51, a terminal component storage unit 52 storing each terminal component 32 for the main terminal, and terminal component storage units 53A and 53B individually storing the respective terminal components 33A and 33B for the auxiliary terminals are formed to be partitioned by an insulating partition wall 54 as illustrated in FIG. 12.

[0043] The terminal component storage unit 52 is formed on its inner surface with an engagement groove 52a engaged with the engagement plate portion 37b4 formed at the rear plate portion 37b3 of the U-shaped conductive plate unit 37b of the terminal to be connected 37 as illustrated in FIG. 12.

[0044]  Also, the terminal component storage unit 52 is formed at its upper part with an eaves unit 55 covering the main terminals 12u through 12w of the thermal overload relay 10 as illustrated in FIG. 5. Likewise, the terminal component storage unit 53A is formed at its upper part with an eaves unit 56 covering the auxiliary terminals 14a and 14b. The eaves unit 55 is formed with engagement elongated holes 55a and 55b penetrating therethrough engaged with engagement parts 13g formed at the upper ends of the partition walls 13b and 13c of the thermal overload relay 10. The eaves unit 56 is formed with an engagement elongated hole 56a penetrating therethrough engaged with an engagement part 13g formed at the upper end of the partition wall 13e of the thermal overload relay 10.

[0045] Further, the terminal component storage unit 52 is formed on its lower surface side with the engagement hole 57 engaged with the engagement protrusion 35a1 formed in the insulating case 35 of the terminal component 32 for the main terminal so as to extend in its longitudinal direction as illustrated in FIG. 9. There is formed a hook part 52d snap-fit connected over the engagement protrusion 35a1 when the terminal cover 51 is mounted to the front end side of the engagement hole 57.

[0046] On the other hand, the terminal component storage unit 53B is formed on its lower surface side with the elongated grooves 58 each having a width not allowing insertion of a tool. The elongated groove 58 is formed at the bottom face of its front end with the engagement hole 59 penetrating therethrough engaged with the engagement protrusion 45x formed at the lower surface of the terminal component 33B for the auxiliary terminal. Incidentally, as illustrating in FIG. 11, a hook part 53d is formed at the upper surface of the end forming the engagement hole 59, of a bottom plate part 53c of the terminal component storage unit 53B of the terminal cover 51. The hook part 53d is snap-fit connected over the engagement protrusion 45x formed at the terminal component 33B for the auxiliary terminal when the terminal cover 51 is mounted.

[0047] Further, the terminal component storage unit 52 is formed on the rear end side of its upper surface with insertion holes 52b each allowing insertion of an electric connection part 61 such as a single wire, a stranded wire, or a stranded wire with a ferrule terminal for a main terminal connection cable 60 being penetrated therethrough in opposition to the tip side of the inclined plate part 38c of the terminal spring 38.

[0048] Also, the terminal component storage unit 52 is formed on the front side of each insertion hole 52b at its upper surface with an insertion hole 52c allowing insertion of a clamp releasing tool to press the terminal spring 38 and separate it from the electric connection part 61 being penetrated therethrough.

[0049] Likewise, there are formed two by two on the rear end sides of the upper surfaces of the terminal component storage units 53A and 53B, insertion holes 53a each allowing insertion of an electric connection part such as a single wire, a stranded wire, or a stranded wire with a ferrule terminal for an auxiliary terminal connection cable (not illustrated) so as to be opposed to the two terminal springs 48. Further, there are formed two by two on the front sides of the insertion holes 53a at the upper surfaces of the terminal component storage units 53A and 53B, insertion holes 53b each allowing insertion of a clamp releasing tool to press the terminal spring 48 and separate it from the electric connection part being penetrated through the terminal component storage units 53A and 53B.

[0050] The operation of the present invention will next be described.

[0051] To use the thermal overload relay 10 having the screw terminals illustrated in FIG. 4 as a thermal overload relay having spring terminals, the terminal components 32 for the main terminals are first individually mounted to the main terminal 12i (where i = u, v, and w) of the thermal overload relay 10 as illustrated in FIGS. 4 and 5. Likewise, the terminal components 33A for the auxiliary terminals are individually mounted to the auxiliary terminal 14j (where j = a and b) of the thermal overload relay 10. Further, the terminal components 33B for the auxiliary terminals are individually mounted to the auxiliary terminal 14k (where k = c and d).

[0052]  To mount each terminal component 32 for the main terminal to the main terminal 12i, the terminal screw 16 threadedly engaged with the female screw part 18 of the terminal plate 15 of the main terminal 12i is first detached together with the washer 19. In this state, the terminal part 37a of the terminal to be connected 37 protruding from the terminal component 32 for the main terminal is placed on the terminal plate 15.

[0053] At this time, the engagement groove 37d formed in the terminal part 37a of the terminal to be connected 37 is engaged with the protrusion 20 formed at the terminal plate 15. Since the terminal plate 15 is unrotatably fixed by the side walls 13a and 13f and the partition walls 13b through 13e, the terminal component 32 for the main terminal is positioned to extend in the longitudinal direction perpendicular to the front end surface of the thermal overload relay 10.

[0054] In this state, the terminal screw 16 mounted with the washer 19 is threadedly engaged with the female screw part 18 of the terminal plate 15 through the through hole 37c of the terminal to be connected 37 and then fastened.

[0055] At this time, in a state in which the upper surface of the washer 19 is made contact with the head of the terminal screw 16, and the lower surface of the washer 19 is made contact with the upper surface of the terminal part 37a of the terminal to be connected 37, an operator holds the terminal component 32 for the main terminal by hand for a period of time up to the start of engagement of the engagement groove 37d with the protrusion 20. Thereafter, when the operator releases the holding of the terminal component 32 for the main terminal and fastens the terminal screw 16, the terminal component 32 for the main terminal is accurately positioned and fixed by the engagement of the engagement groove 37d with the protrusion 20 while exhibiting both functions of positioning and rotation stop without the terminal component 32 for the main terminal being rotated by the rotation of the terminal screw 16. Accordingly, it is possible to easily carry out the work of mounting each terminal component 32 for the main terminal to the main terminal 12i in a short period of time.

[0056] At this time, the protrusion 20 formed at the terminal plate 15 of the main terminal 12i is formed in a semicircular shape as viewed from its side surface. The engagement groove 37d formed in the terminal part 37a of the terminal to be connected 37 is formed in a triangular shape as viewed from its side surface. Therefore, even when the cross sectional shapes of the protrusion 20 and the engagement groove 37d are not accurately molded, the positioning and the rotation stop can be accurately carried out by the centering function of the triangular engagement groove 37d.

[0057] Next, each terminal component 33B for the auxiliary terminal is individually mounted to the auxiliary terminal 14k. Even in this case, the terminal plate 15 of the auxiliary terminal 14k is formed with the protrusion 20, and the terminal to be connected 47 of the terminal component 33B for the auxiliary terminal is formed with the engagement groove 47x. Therefore, each terminal component 33B for the auxiliary terminal can be individually mounted to the auxiliary terminal 14k according to the procedure similar to the mounting of each terminal components 32 for the main terminals to the main terminal 12i. At this time, the positioning function and the rotation-stop function are exerted by the protrusion 20 and the engagement groove 47x to enable the work of mounting the terminal component 33B for the auxiliary terminal to the auxiliary terminal 14k to be easily carried out in a short period of time.

[0058] Further, each terminal component 33A for the auxiliary terminal is individually mounted to the auxiliary terminal 14j. Even in this case, the terminal plate 15 of the auxiliary terminal 14j is formed with the protrusion 20, and the terminal to be connected 47 of the terminal component 33A for the auxiliary terminal is formed with the engagement groove 47x. Therefore, each terminal component 33A for the auxiliary terminal can be individually mounted to the auxiliary terminal 14j according to the procedure similar to the mounting of each terminal components 33B for the auxiliary terminals to the auxiliary terminal 14j. At this time, the positioning function and the rotation-stop function are exerted by the protrusion 20 and the engagement groove 47x to enable the work of mounting each terminal component 33B for the auxiliary terminal to the auxiliary terminal 14j to be easily carried out in a short period of time.

[0059] Thus, the mounting of the terminal components 32 for the main terminals and the terminal components 33A and 33B for the auxiliary terminals to the main terminals 12u through 12w and the auxiliary terminals 14a through 14d of the thermal overload relay 10 is completed. In this state, as illustrated in FIGS. 5 and 6, the terminal components 32 for the main terminals and the terminal components 33A and 33B for the auxiliary terminals are extended in the longitudinal direction, and accurately arrayed and held in the horizontal direction.

[0060] In this state, the main terminals 12u through 12w and auxiliary terminals 14a and 14b of the thermal overload relay 10, the terminal to be connected 37 and terminal spring 38 of each terminal component 32 for the main terminal, and the terminal to be connected 47 and terminal spring 48 of each terminal component for the auxiliary terminal are exposed. Therefore, the terminal cover 51 is mounted to cover the main terminals 12u through 12w, the auxiliary terminals 14a and 14b, the terminal components 32 for the main terminals, and the terminal components 33A and 33B for the auxiliary terminals.

[0061] Upon mounting of the terminal cover 51, first, each terminal component storage unit 52 of the terminal cover 51 is made opposite to the terminal component 32 for the main terminal, and the terminal component storage units 53A and 53B are made opposite to the terminal components 33A and 33B for the auxiliary terminals. In this state, the terminal cover 51 is pushed to the back side of the thermal overload relay 10 to engage the engagement parts 13g formed at the partition walls 13b and 13c of the thermal overload relay 10 in the engagement elongated holes 55a and 55b formed in the eaves unit 55.

[0062] Simultaneously with that, the hook part 52d gets over the engagement protrusion 35a1 formed at the bottom face of the terminal component 32 for the main terminal so that the engagement protrusion 35a1 is snap-fit engaged in the engagement hole 57. Further, the hook part 53d formed at the lower surface of the terminal component storage unit 53B gets over the engagement protrusion 45x formed at the bottom face of the terminal component 33B for the auxiliary terminal so that the engagement protrusion 45x is snap-fit coupled to the engagement hole 59.

[0063] Further, the engagement plate portion 37b4 formed at the U-shaped conductive plate unit 37b of each terminal component 32 for the main terminal is engaged in the engagement groove 52a formed at the terminal component storage unit 52.

[0064] Accordingly, the terminal cover 51 is dismountably mounted to the thermal overload relay 10 through the terminal components 32 for the main terminals and the terminal components 33A and 33B for the auxiliary terminals. That is, the engagement protrusion 45x formed at the insulating case 45 of the terminal component 33B for the auxiliary terminal is engaged in the engagement hole 59 formed in the bottom of the tool-uninsertable elongated groove 58 formed at the lower surface of the terminal component storage unit 53B of the terminal cover 51. Therefore, the state of engagement between the engagement hole 59 and the engagement protrusion 45x can not be released because the tool can not be inserted into the elongated groove 58. A release stop mechanism is configured by the elongated groove 58, the engagement hole 59, and the hook part 53d, thus making it unable to detach the terminal cover 51.

[0065] Incidentally, when any one of the terminal components 32 for the main terminals and the terminal components 33A and 33B for the auxiliary terminals covered with the terminal cover 51 fails, the terminal cover 51 is broken to replace the faulty terminal component, after that a new terminal cover 51 is mounted.

[0066] Thus, the mounting of the terminal cover 51 assumes a state illustrated in FIGS. 1 through 3. Thus, the conductive portions of the main terminals 12u through 12w, the auxiliary terminals 14a and 14b, the terminal components 32 for the main terminals, and the terminal components 33A and 33B for the auxiliary terminals are all covered. It is therefore possible to previously prevent an electric shock accident. Further, since the terminal components 32 for the main terminals and the terminal components 33A and 33B for the auxiliary terminals are insulated by the insulating partition wall 54 formed in the terminal cover 51, it is possible to surely insulate between the respective terminal components.

[0067] Then, the terminal components 32 for the main terminals, the terminal components 33A and 33B for the auxiliary terminals, and the terminal cover 51 are mounted onto the thermal overload relay 10 having the screw terminals to enable the thermal overload relay having the screw terminals to be configured as a thermal overload relay having spring terminals.

[0068] In this state, the electric connection part such as the single wire, stranded wire, or stranded wire with the ferrule terminal for the connection cable 60 is inserted into each of the insertion holes 52b and 53a of the terminal cover 51 to separate the terminal springs 38 and 48 from the U-shaped conductive plate units 37b and 47b. Thus, each of the tips of the terminal springs 38 and 48 is brought into contact with the conductive connection part to interpose the conductive connection part between the terminal springs 38 and 48 and the U-shaped conductive plate units 37b and 47b respectively.

[0069] At this time, since the connection cable 60 for each main terminal is thick in terms of the diameter of the single wire or the stranded wire, a large force is required when interposing it between the terminal spring 38 and the U-shaped conductive plate unit 37b. Therefore, a cantilever load is exerted to the side opposite to the terminal part 37a of the terminal to be connected 37 in the terminal component 32for the main terminal. However, the engagement plate portion 37b4 of the bottom plate part 37b2 of the U-shaped conductive plate unit 37b is in engagement with the engagement groove 52a formed in the inner surface of the terminal component storage unit 52 of the terminal cover 51. It is therefore possible to support the cantilever load exerted to the terminal component 32 for the main terminal while dispersing it to the terminal cover 51 and to prevent the terminal part 37a of the terminal to be connected 37 from being deformed.

[0070] Also, to detach the electric connection part 61 of the connection cable 60 from the spring terminal 39, a tool such as a minus screw driver is inserted into the tool insertion hole 52c (or 53b) to separate the inclined plate part 38c (or 48c) of the terminal spring 38 (or 48) from the electric connection part 61 to thereby release a lock state and then pull out the electric connection part 61.

[0071] Incidentally, although the above-described embodiment has described the case where the terminal plate 15 is formed with the protrusion 20, and the terminal to be connected 37 and 47 are respectively formed with the engagement grooves 37d and 47x, the present invention is not limited to it. The engagement groove may be formed in the terminal plate 15, and the protrusions may be formed at the terminal to be connected 37 and 47. Further, it may be practical to form a protrusion and an engagement groove in the terminal plate 15 with the cylindrical part 17 interposed therebetween and form an engagement groove opposite to a protrusion and a protrusion opposite to an engagement groove in the terminal to be connected 37 and 47.

[0072] Further, the direction in which the protrusion 20 and the engagement grooves 37d and 47x extend can arbitrarily be set. They are not necessarily required to pass through the center of the terminal screw 16. The cross sectional shape of the protrusion 20 and the cross sectional shape of the engagement groove 37d may also respectively be set to an arbitrary cross sectional shape so long as they can be engaged with each other.

[0073] Also, the above-described embodiment has described the case where as illustrated in FIG. 4, the terminal component 33B for the auxiliary terminal is completely exposed from the rear end of the terminal component 33A for the auxiliary terminal in the state in which the terminal component 33A and the terminal component 33B for the auxiliary terminal are respectively mounted to the auxiliary terminals 14j and 14k of the thermal overload relay 10. However, the present invention is not limited to it, and the exposure region of the terminal component 33B for the auxiliary terminal may be narrowed to such an extent as to allow the insertion holes 53a and 53b of the terminal cover 51 to be faced to the outside.

[0074] Further, although the above-described embodiment has described the connection structure where the thermal overload relay 10, and the terminal components 32 for the main terminals and the terminal components 33A and 33B for the auxiliary terminals are connected to each other, the present invention is not limited to it. The present invention can be applied to a case where an electric apparatus having terminal to be connecteds is connected to the screw terminals of the electric apparatus.

[0075] Furthermore, although the above-described embodiment has described the case where the thermal overload relay is applied as the electric apparatus, the present invention is not limited to it. The present invention can be applied to an electric apparatus having an electromagnetic contactor, an electromagnetic relay, and other screw terminals. In this case, the present invention can be applied even to an electric apparatus with no auxiliary terminals, having only main terminals.

Description of Reference Signs

[0076] 10... thermal overload relay, 11u - 11w... external connection pin, 12u - 12w... main terminal, 13a, 13f... side wall, 13b - 13e... partition wall, 14a - 14d... auxiliary terminal, 15... terminal plate, 16... terminal screw, 17... cylindrical part, 18... female screw part, 19... washer, 20... protrusion, 31... spring terminal component, 32... terminal component for main terminal, 33A, 33B... terminal component for auxiliary terminal, 35... insulating case, 36... annular circumferential wall, 37... terminal to be connected, 37a... terminal part, 37b... U-shaped conductive plate unit, 37b4... engagement plate portion, 37b5... engagement protrusion, 38... terminal spring, 45... insulating case, 45x... engagement protrusion, 46... annular circumferential wall, 47... terminal to be connected, 47b... U-shaped conductive plate unit, 48... terminal spring, 51... terminal cover, 52, 53A, 53B... terminal component storage unit, 54... insulating partition wall, 55, 56... eaves unit, 55a, 55b, 56a... engagement elongated hole, 58... elongated groove, 59... engagement hole, 60... connection cable, 61... electric connection part.

Claims

1. A connection structure of an electric apparatus comprising:

a screw terminal formed in the electric apparatus; and

a terminal to be connected formed in a member to be connected,

wherein the screw terminal and the terminal to be connected are electrically connected, and

wherein a rotation-stop mechanism engaged mutually with the screw terminal and the terminal to be connected is provided.

2. The connection structure of the electric apparatus according to claim 1, wherein the screw terminal includes a terminal plate formed with a female screw part, and a terminal screw threadedly engaged with the female screw part, and
wherein a first engagement part is formed at a junction surface of the terminal plate with the terminal to be connected, the first engagement part configuring the rotation-stop mechanism extending in a radial direction of the female screw part.

3. The connection structure of the electric apparatus according to claim 2, wherein the terminal to be connected has an insertion hole inserting the terminal screw and a second engagement part is formed at a junction surface of the terminal to be connected with the screw terminal, the second engagement part configuring the rotation-stop mechanism engaged with the first engagement part.

4. The connection structure of the electric apparatus according to claim 3, wherein one of the first engagement part and the second engagement part includes an engagement protraction, and the other of the first engagement part and the second engagement part includes an engagement groove engaged with the engagement protrusion.

5. The connection structure of the electric apparatus according to any one of claims 1 to 4, wherein the member to be connected has the terminal to be connected at one end and has a spring terminal electrically connected to the terminal to be connected at the other end.

6. The connection structure of the electric apparatus according to any one of claims 1 to 5, including a terminal cover covering the member to be connected in a state in which the member to be connected is connected to the screw terminal.

7. The connection structure of the electric apparatus according to claim 6, wherein the screw terminal is provided in plural,
wherein the member to be connected is individually connected to a plurality of the screw terminals, and
wherein the terminal cover is configured to collectively cover a plurality of the members to be connected.

8. The connection structure of the electric apparatus according to claim 7, wherein an undetachable release stop mechanism is provided between the member to be connected and the terminal cover.

Drawing