JP2009231057A - Thermal overload relay - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermal overload relay having a small outline and consistently stable property without changing the reversing property of a contact reversing mechanism with the adjustment of a setting current. <P>SOLUTION: The thermal overload relay includes the contact reversing mechanism which consists of a lever support fixed and supported onto a case, a reversing lever turnably supported at its lower end with a first supporting part of the lever support and having a movable contact at the upper end, a temperature compensation auxiliary bimetal bent at the intermediate part into a U-shape and turnably supported at the intermediate bent portion by a second supporting part separated from the first supporting part of the lever support, a reversing spring bridged between one end of the auxiliary bimetal and the upper end of the reversing lever, a releasing lever for transmitting the motion of a shifter to the other end of the auxiliary bimetal, the movable contact provided at the upper end of the reversing lever, and a fixed contact opposed to the movable contact movable close thereto or apart therefrom. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a thermal overload relay used in combination with an electromagnetic contactor or the like, and more particularly to an improvement of a contact reversing mechanism driven by a main bimetal.

A thermal overload relay provided with this type of contact reversing mechanism is disclosed in Patent Document 1, for example. As shown in FIG. 9, the conventional thermal overload relay disclosed in Patent Document 1 includes a heater 20 that is energized by a main circuit current and generates heat according to the magnitude of the main circuit current, and the heater 20 The main bimetal 30 that is heated and deformed by bending, the shifter 40 that is driven and moved by the main bimetal 30 that is displaced by bending, and the contact reversing mechanism 60 that is driven by the shifter 40 to open and close the fixed contact 605b and the movable contact 602b. Are housed in a resin case 10.
As shown in FIG. 10, the contact reversing mechanism 60 includes a lever support 601 that is rotatably supported by a support shaft 101 provided in the case 10. The lever support 601 rotatably supports a reversing lever 602 serving as a movable contact having a movable contact 602b and a temperature-compensating auxiliary bimetal 603 by fulcrums 601p and 601q provided thereon. The reversing lever 602 and the auxiliary bimetal 603 are connected to each other by a reversing spring 604 and pulled. A fixed contact 605 having a fixed contact 605b at the distal end and a leaf spring having a base end fixedly supported by the case 10 and a reversing lever 602 having a movable contact 602b include a fixed contact 605b and a movable contact 602b. Is disposed opposite to the position where the can be contacted and separated.

Further, a settling current (operation) of a thermal overload relay having an adjustment knob 701 and an adjustment screw 702 whose tip is moved in the axial direction by a rotation operation of the adjustment knob 701 is opposed to the upper end of the lever support 601. An adjustment mechanism 70 for adjusting the current) is provided.
Such a thermal overload relay provided with the contact reversing mechanism 60 operates as follows.
When the main circuit current is passed through the heater 20, the heater 20 generates heat according to the current and heats the main bimetal 30. For this reason, the main bimetal 30 is bent and displaced in accordance with the magnitude of the main circuit current, so that the shifter 40 is moved in the left direction in FIG. For this reason, the shifter 40 comes into contact with the lower end of the auxiliary bimetal 603 of the contact reversing mechanism 60 and presses it.
When the main circuit current is small and normal, the displacement due to the curvature of the main bimetal 30 is small, and even if the auxiliary bimetal 603 is pressed by the shifter 40, the displacement is small, so the reversing spring 604 exceeds the reversing position. Instead, as shown in FIG. 10, it is located on the left side of the reversal axis CL. Therefore, the reversing lever 602 is pulled leftward by the reversing spring 604, the tip side is inclined toward the fixed contact 605, and the movable contact 602b is in contact with the fixed contact 605b and remains closed.

When the main circuit current becomes larger than the preset set current, the main bimetal 30 is further bent and displaced. Accordingly, the shifter 40 presses the lower end of the auxiliary bimetal 603 to the left as shown by the dotted line in FIG. Displace this. As a result, the auxiliary bimetal 603 rotates about the fulcrum 601q, and the tip of the reversal spring 604 coupled moves to the right beyond the reversal axis CL passing through the fulcrum 601p supporting the reversing lever 602. 604 rapidly reverses the state, and the reverse lever 602 is rotated to the position indicated by the dotted line. As a result, the movable contact 602b is separated from the fixed contact 605b and opened, and an electromagnetic contactor (not shown) connected thereto cuts off the main circuit current and protects the main circuit from overcurrent.
Further, as shown in FIG. 11, adjustment of the settling current in the thermal overload relay is performed by rotating an adjustment knob 701 of the adjustment mechanism 70 provided almost integrally with the contact reversing mechanism 60 and using an adjustment screw 702. This is done by adjusting the pushing amount of the upper end of the lever support 601. When the adjustment screw 702 is pushed downward, the lever support 601 rotates about the support shaft 101 as shown by the dotted line in FIG. 11, and the auxiliary bimetal 603 supported by the lever support 601 also moves together. The interval with respect to 40 becomes large, and the settling current value can be adjusted to a large value.
Japanese Patent Laid-Open No. 07-134935 (FIG. 1)

The auxiliary bimetal 603 used in the contact reversing mechanism 60 of such a conventional thermal overload relay compensates for the influence of the ambient temperature on the main bimetal 30, and therefore has a larger size due to the bending characteristics of the main bimetal. The length is determined. For this reason, since the auxiliary bimetal 603 requires a certain length, there is a problem that the vertical space of the contact reversing mechanism 60 is increased and the outer shape of the thermal overload relay is increased.
In this conventional thermal overload relay, the settling current adjustment mechanism 70 is directly linked to the contact reversing mechanism 60. Therefore, in order to displace the lower end of the auxiliary bimetal 603 by the adjustment knob 701, The lever support 601 itself that supports the contact reversing mechanism 60 must be displaced. At this time, since the upper fulcrum 601p and the lower fulcrum 601q are displaced, the reversal axis CL serving as the reversal point with respect to the fixed contact 605b is shifted, and there is a problem that the reversal characteristic (reversal load) varies depending on the adjustment amount of the adjustment knob 701. .
The present invention solves the problems in the conventional thermal overload relay as described above, can reduce the outer shape, and does not change the reversing characteristics of the contact reversing mechanism by adjusting the settling current, and has stable characteristics. The object is to provide a thermal overcurrent relay.

In order to solve the above-mentioned problems, the present invention is configured to move in conjunction with a heater that generates heat when a main circuit current is passed through, a main bimetal that is heated and bent by the heater, and a bending displacement of the main bimetal. And a contact reversing mechanism that is driven by this shifter and opens and closes the open / close contact in a resin-made case, the contact reversing mechanism is fixedly supported by the case. A lever support, a lower end is rotatably supported by a first support portion provided on the lever support, a reversing lever provided with a movable contact at the upper end portion, and a middle portion is bent to form a U-shape. A temperature-compensating auxiliary bimetal that is rotatably supported by a second support portion that is provided apart from the first support portion of the lever support, and one end of the auxiliary bimetal. A reversing spring spanned between the upper end of the reversing lever, a release lever for transmitting the movement of the shifter to the other end of the auxiliary bimetal, and a movable contact provided at the upper end of the reversing lever. The movable contact and the fixed contact disposed so as to be capable of coming into contact with and separated from each other are characterized in that the movable contact is formed.
In the present invention, an adjustment cam rotatably supported on the case is provided, and the rotation current of the release lever of the settling current adjustment mechanism is displaced by the adjustment cam to adjust the settling current value. Can do.

  Further, a lever support fixedly supported by the case is disposed in a U-shape of an auxiliary bimetal formed in a U-shape.

According to the present invention, the auxiliary bimetal incorporated in the contact reversing mechanism is formed in a U shape, and the intermediate bent portion is rotatably supported by the lever support. ) Can be reduced to half that of the prior art, and the overall size of the thermal overload relay incorporating this can be reduced.
In the present invention, the lever support of the contact reversing mechanism is fixedly provided, and the displacement of the main bimetal is transmitted to the auxiliary bimetal of the contact reversing mechanism via the shifter and the release lever. Since the fulcrum can be displaced by the settling current adjustment cam, the inversion characteristics of the contact reversing mechanism will not change even if the settling current is adjusted, and the operation of the thermal overload relay can be stabilized. it can.

Next, embodiments of the present invention will be described based on examples shown in the drawings.
1 and 2 show the internal configuration of a thermal overload relay according to an embodiment of the present invention. FIG. 1 is a perspective view of the back plate viewed from the back side, and FIG. 2 is a similar back view.
As shown in FIGS. 1 and 2, the main part of the thermal overload relay of the present invention includes a heater 2 that is energized by the main circuit current and generates heat according to the magnitude of the main circuit current, and the heater 2. The main bimetal 3 that is heated and curved and displaced, the shifter 4 that transmits the displacement of the curved and displaced main bimetal 3, and the fixed contact 65a and the contact reversing mechanism 6 that opens and closes the movable contact 62a are driven by the shifter 4. It is comprised and it accommodates in the case 1 made from resin.
The details of the contact reversing mechanism 6 are shown enlarged in FIGS.
The contact reversing mechanism 6 includes a lever support 61, a reversing lever 62, a temperature-compensating auxiliary bimetal 63 formed in a U shape by bending an intermediate portion, and a reversing bridge between the reversing lever 62 and the auxiliary bimetal 63. And a spring 64. The lever support 61 includes a pair of support pieces 61p that are formed to project from an intermediate portion and a support projection 61q that is formed to project downward from a lower end surface. The support piece 61p is formed with a groove 61v having a V-shaped cross section on a receiving surface that receives a pair of support legs 62d of the reversing lever 62 and rotatably supports the support legs 62d. The lower end support protrusion 61q is also formed with an acute angle at the tip (see FIGS. 5 and 6).

Further, since the lever support 61 is disposed within the U-shape of the auxiliary bimetal 63 formed in a U-shape, the space efficiency in the left-right direction is increased.
In the contact reversing mechanism 6, the reversing lever 62 is rotatably assembled to the lever support 61 with its supporting leg 62 d housed in the V-shaped groove 61 v of the support piece 61 p serving as the first fulcrum of the lever support 61. In the auxiliary bimetal 63, a fitting hole 63h provided in an intermediate bent portion is loosely fitted with a fitting protrusion 61e provided in the lower end of the lever support 61, and the inner peripheral surface of the bent portion of the auxiliary bimetal 63 is a lever support 61. The support projection 61q is in contact with the tip of the support projection 61q so as to be pivotally assembled to the lever support 61. The contact reversing mechanism 6 is assembled by bridging the reversing spring 64 between the hook 62f of the reversing lever 62 and the hook 63f of the auxiliary bimetal 63 assembled to the lever support 61 in this way (see FIG. 4). In the assembled state, the reversing lever 62 and the auxiliary bimetal 63 are pulled together by the reversing spring 64, press against the support piece 61p and the support protrusion 61q, respectively, and are rotatably supported by the lever support 61.
The reversing lever 62 also serves as a movable contact of the opening / closing mechanism, and includes a contact 62a serving as a movable side contact of a normally open contact at the upper end.

Further, as shown in FIG. 5, the lever support 61 is integrally formed with a movable side lead terminal 61t for connecting the movable contact 62a to an external circuit and an attachment piece 61r for fixing the lever support 61 to the case 1. The lever support 61 is fixed to the case 1 by press-fitting the attachment piece 61 r into a fixing hole provided in the case 1 when the case 1 is stored in the case 1.
The fixed contact 65 provided with the fixed side contact 65a is arranged to face the reversing lever 62 that also serves as a moving contact, and the fixed contact 65a and the movable contact 62a are configured to be able to contact and separate. The stationary contact 65 is constituted by a spring plate fixedly attached to the case 1 (see FIGS. 1 and 3).
As shown in FIG. 7, an adjustment mechanism 7 for adjusting a settling current provided adjacent to the contact reversing mechanism 6 includes an adjustment knob 71 and a central axis of the adjustment knob 71 integrally coupled thereto. An adjustment cam 72 formed eccentrically with respect to the case 1, an adjustment link 73 rotatably supported on a fixed shaft 75 fixedly supported on the case 1, and a support shaft 73b formed to project from the adjustment link 73 And a release lever 74 that is rotatably supported.
Such an adjusting mechanism 7 is assembled as follows. First, the support shaft 73 b provided on the adjustment link 73 is inserted into the bearing 74 a of the release lever 74, and the release lever 74 is linked to the adjustment link 73. Then, the adjustment link 73 is rotatably fixed to the case 1 by fitting the bearing hole 73 c of the adjustment link 73 linked to the release lever 74 to the fixed shaft 75 fixed to the case 1. Further, an adjustment knob 71 and an adjustment cam 72 that are integrally formed are arranged on the upper end portion of the adjustment link 73 that is rotatably fixed to the case 1, and the outer peripheral surface of the adjustment cam 72 is provided on the adjustment link 73. The adjusting mechanism 7 is assembled by bringing it into contact with the receiving piece 73a.

The contact reversing mechanism 6 and the adjusting mechanism 7 thus configured are arranged side by side as shown in FIG. The tip (lower end) of the release lever 74 of the adjustment mechanism 7 is engaged with the shifter 4 linked to the main bimetal 3, and the pressing protrusion 74 b provided at the intermediate portion of the release lever 74 is a U-shape of the contact reversing mechanism 6. The auxiliary bimetal 63 formed in a shape is in contact with the free end on the opposite side to the end connected to the reversing spring 64.
When the main circuit current is in a normal current state smaller than the settling current, the shifter 4 and the release lever 74 are placed at a position indicated by a solid line in FIG. For this reason, the auxiliary bimetal 63 of the contact reversing mechanism 6 is also in the position indicated by the solid line, the reversing lever 62 is pulled by the reversing spring 64 and tilted to the lever support 61 side (right side), and is locked to the stopper 61s of the lever support 61. Therefore, the movable contact 62 a provided on the reversing lever 62 is separated from the fixed contact 65 a of the fixed contact 65 and opened.
When the main circuit current is in an overcurrent state larger than the settling current, the bending displacement of the main bimetal 3 increases, and accordingly, the shifter 4 drives the release lever 74 to the left as shown by the dotted line in FIG. Since the release protrusion 74b of the release lever presses the other free end of the auxiliary bimetal 63, the auxiliary bimetal 63 rotates around the support end 61q below the lever support 61 and is displaced as indicated by the dotted line. . As a result, the lower end of the reversing spring 64 connected to one end of the auxiliary bimetal 63 moves to the left beyond the reversing axis CL, so that the reversing spring 64 is rapidly reversed to the left, and the reversing lever 62 is indicated by a dotted line. Inclined toward the fixed contact 65, the movable contact 62a is closed to the fixed contact 65a, and an overcurrent is detected and notified.

Further, as described above, by pressing the other end of the auxiliary bimetal 63 and operating the reversing spring 64 connected at the other end of the auxiliary bimetal 63 formed in a U shape, Since the spring constant can be made larger than that of the auxiliary bimetal shape, the transmission efficiency of the reversing operation is improved.
As shown in FIG. 2, the movement of the reversing lever 62 is transmitted to the movable contact 68a of the normally closed auxiliary contact 68 by the interlocking lever 67 linked thereto, and the movable contact 68a is moved to the movable contact 68b. Is driven in a direction away from the fixed contact 68d provided on the fixed contact 68c, thereby opening the normally closed auxiliary contact.
The state set in the overcurrent state (normally open contacts 62a and 65a are closed and normally closed contacts 68b and 68d are open) is held by the reversing spring 64, but this is manually reset. In order to return to the original state, the reset rod 8 (see FIG. 2) is pushed in. Since the interlock lever 67 is returned to the original position by the pushing operation of the reset bar 8, the reversing lever 62 returns to the original position (position indicated by the solid line in FIG. 3), and the reversing spring 64 is reversed to the original state. Can be reset. Along with this, the auxiliary bimetal 63 also returns to its original position and prepares for the next overcurrent detection.

Next, the adjustment operation of the set value of the operating current by the adjustment mechanism 7 will be described.
As shown in FIG. 8, when the adjustment knob 71 is rotated left and right by a driver or the like, the adjustment cam 72 is rotated together, and the outer diameter of the surface of the adjustment lever 73 that contacts the receiving piece 73a changes, and the receiving piece 73a. Therefore, the adjustment lever 73 rotates around the fixed shaft 75. Along with the rotation of the adjusting lever 73, the support shaft 73b, which is a fulcrum that supports the release lever 74 so as to be rotatable, moves in the direction of arrow A, so that the release lever 74 also moves in the direction of arrow B.
In a state where the release lever 74 is moved by such a turning operation of the adjustment knob 71, as shown by a dotted line in FIG. 4, the pressing protrusion 74b of the release lever 74 and the other end of the auxiliary bimetal 63 of the contact reversing mechanism 6 are connected. The distance of the interval changes, and the operating settling current value can be adjusted by changing this distance.
According to the adjusting mechanism 7 of the present invention, by adjusting the adjustment knob 71, the distance between the release lever 74 that transmits the movement of the shifter 4 to the auxiliary bimetal 63 and the auxiliary bimetal 63 is changed, thereby setting the operating current. While the value can be adjusted, the lever support 61 of the contact reversing mechanism 6 can be fixed without being displaced. Therefore, even if the settling current is adjusted, the reversing characteristics of the reversing spring in the contact reversing mechanism 6 This can be kept stable without fluctuation.

It is the perspective view which looked at the thermal overload relay by the Example of this invention, removing the back plate from the back side. It is a rear view which removes the back board of the thermal overload relay by the Example of this invention, and shows an inside. It is operation | movement explanatory drawing of the contact inversion mechanism by this invention. It is operation | movement explanatory drawing of the settling current adjustment mechanism by this invention. It is a perspective view which shows the structure of the contact inversion mechanism by this invention, and a settling current adjustment mechanism. It is a disassembled perspective view which shows the structure of the contact inversion mechanism by this invention. It is a disassembled perspective view which shows the structure of the settling current adjustment mechanism by this invention. It is a perspective view which shows the structure of the settling current adjustment mechanism by this invention. It is a front view of the state which removed the front cover which shows the structure of the conventional thermal overload relay. It is operation | movement explanatory drawing of the contact inversion mechanism in the conventional thermal overload relay. It is operation | movement explanatory drawing of the settling current adjustment mechanism in the conventional thermal type overload relay.

Explanation of symbols

1: Case 2: Heater 3: Main bimetal 4: Shifter 6: Contact reversing mechanism 61: Lever support 62: Reversing lever 63: Auxiliary bimetal 64: Reversing spring 7: Settling current adjusting mechanism 71: Adjustment knob 72: Adjustment cam 73: Adjustment lever 74: Release lever

Claims (3)

  A heater that generates heat when the main circuit current is passed through, a main bimetal that is heated and deformed by the heater, a shifter that moves in conjunction with the bending displacement of the main bimetal, and an open / close contact that is driven by the shifter. In a thermal overload relay configured by placing a contact reversing mechanism for opening and closing in a resin case, the contact reversing mechanism includes a lever support fixedly supported by the case and a lower end provided on the lever support. A reversing lever that is rotatably supported by one support portion and has a movable contact at the upper end portion, and a U-shape formed by bending an intermediate portion, the bent portion being a first support portion of the lever support The auxiliary bimetal for temperature compensation that is rotatably supported by a second support portion that is spaced apart from the first and second ends of the auxiliary bimetal, and is spanned between one end of the auxiliary bimetal and the upper end of the reversing lever. A reversing spring, a release lever that transmits the movement of the shifter to the other end of the auxiliary bimetal, a movable contact provided at the upper end of the reversing lever, and a fixed fixed to be opposed to the movable contact. A thermal overload relay characterized by comprising contacts. An adjustment cam that is rotatably supported by the case is provided, and the adjustment current is adjusted by displacing the rotation fulcrum of the release lever of the contact reversing mechanism. Thermal overload relay, characterized in that 2. The thermal overload relay according to claim 1, wherein the lever support fixedly supported by the case is disposed in a U-shape of an auxiliary bimetal formed in a U-shape.

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