JPH1040795A - Inverting spring contact switching mechanism and thermal overload relay - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inverting spring contact switch mechanism composed of one part in which its inverting spring mechanism is easily fabricated and assembled as a contact switch mechanism mounted on a thermal overload relay so as to obtain a stable inversion point. SOLUTION: An inverting spring contact switching mechanism 6 combined with a bi-metal heat element 2 moving in response to an overload current of a main circuit is composed of an inverting plate spring 7 in which a traverse pair of an outer leg piece 7a and a central leg piece 7b are punched and formed for a piece of thin plate spring material and a curved spring portion 7a is formed for the central leg piece 7b, a support arm 8 for slidably supporting a tip end edge of the outer leg piece 7a, a support arm 9 for locking a tip end edge of the leg piece 7b while tensile force is applied to the spring portion of the leg piece, an normally closed contact 4a, and a normally opened contact 4b. Here, displacement of a bi-metal 2a of the heat element 2 based on the overload current is transmitted to the inverting plate spring 7 via a release lever 5 so as to switch the contact by inverting operation thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reversing spring contact opening / closing mechanism for opening and closing a movable contact by a snap action of a reversing spring mechanism responding to operation of a release lever, and an overload current to the reversing spring contact opening / closing mechanism. The present invention relates to a thermal overload relay that combines a bimetallic heat element that responds to an overload.

[0002]

2. Description of the Related Art As is well known, a thermal overload relay described above for protecting an overload is provided in addition to an operation control electromagnetic contactor connected to a power supply circuit of a motor. FIG. 4 is a block diagram of a thermal overload relay employing a conventional reversing spring contact opening / closing mechanism disclosed in Japanese Patent Application Laid-Open No. 2-86024. In the figure, 1 is a resin case of a relay,
In the case, a bimetallic heat element that responds to an overload current of a main circuit (for example, a power supply circuit of an electric motor) 2,
The reversing spring mechanism 3 and the contact mechanism 4 are incorporated.

Here, the heat element 2 transfers a load current of a main circuit to a bimetal 2a (only one phase is shown in the figure, but a three-phase circuit has three bimetals corresponding to each phase). One end of a shifter 2c connected to the tip of the bimetal 2a faces the seesaw release lever 5 with a heater 2b flowing therethrough wound thereon. On the other hand, the reversing spring mechanism 3
Is a reversing leaf spring 3a formed by pressing a thin metal spring material into a shape as shown in FIGS. 5A and 5B, and a U-shaped metal leaf spring material like the reversing leaf spring 3a. A reversing drive spring 3b which is bent and locked to the reversing leaf spring 3a, and a mounting board 3c. The reversing driving spring 3b has slit-shaped engagement holes opened at both ends thereof. And is fixed between the tip of the central leg 3d protruding into the window and the claw of the window edge facing the center leg 3d. And
The reversing spring mechanism 3 includes a locking piece 3e formed on the mounting board 3c.
Receiving groove 1a formed in resin case 1 with the tip of fulcrum as a fulcrum
And the end of the reversing leaf spring 3a is fitted and connected to the contact mechanism 4 described below and incorporated in a resin case. Is opposed to the center leg 3d. Reference numeral 3f denotes an adjusting screw for the operating point, and 3g denotes a compression spring for pressing and holding the reversing leaf spring 3a in the case.

The contact mechanism 4 has a structure in which a normally closed contact 4a and a normally open contact 4b are incorporated in an insulating slider 4c. The slider 4c is slidably supported on the resin case 1.
The distal end of the above-mentioned reversing leaf spring 3a is inserted into a slot opened at one end thereof and interconnected. 4d is a reset push button. The operating principle of the thermal overload relay having such a configuration is well known. In a steady state, the reversing leaf spring 3a of the reversing spring mechanism 3 tilts rightward by the repulsive force of the reversing drive spring 3b as shown in FIG. Then, the contact mechanism 4 is kept in the state shown in the figure. On the other hand, the bimetal 2a is heated by flowing a load current flowing through the main circuit to the heater 2b of the heat element 2, and when an overload current flows through the main circuit, the degree of curvature of the bimetal 2a is increased as shown by a dashed line in the figure. The shifter 2c pushes the release lever 5 to the left. As a result, the release lever 5 swings clockwise to push the central leg 3d of the reversing leaf spring 3a to the right. The connecting point between the center leg piece 3d and the reversing drive spring 3b is the reversing leaf spring 3a.
Is moved to the right side of the leaf spring beyond the dead center of the above, the reversing leaf spring 3a is reversed to the left by the spring force of the drive spring 3b, and the slider 4c of the contact mechanism 4 is rapidly driven to the left by the snap action. . As a result, the normally closed contact 4a is opened and the normally open contact 4b is closed, so that the main circuit current is shut off and the main circuit current is cut off. Then, based on this cutoff command, for example, the electromagnetic contactor connected to the main circuit is opened to cut off the overload current. After the main circuit current is cut off, when the reset push button 4d is pushed in when the bending of the bimetal 2a of the heat element 2 is sufficiently restored, the slider 4c of the contact mechanism 4 moves to the right, and is driven by the slider 4c. The mechanism 3 is reversed to the initial state, and the relay is reset.

[0005]

The conventional reversing contact opening / closing mechanism incorporated in the above-mentioned thermal overload relay, particularly the reversing spring mechanism 3 for driving the contact, has a problem in operating characteristics and assembly. Therefore, there are the following problems.
That is, in the conventional reversing spring mechanism 3, the reversing leaf spring 3a
And an inverted drive spring 3b bent in a U-shape. For this reason, at the time of the reversing operation of the reversing spring mechanism 3, sliding friction between the metal members occurs at the fitting engagement points A and B between the reversing leaf spring 3a and both ends of the driving spring 3b. The operating points vary, and the operating characteristics of the overload relay become unstable.

The reversing spring mechanism 3 is assembled from two parts, a reversing leaf spring 3a and a reversing drive spring 3b.
Therefore, in the assembling process, the driving spring 3
When connecting b, it is necessary to take a troublesome operation of bending the leaf spring of the drive spring 3b into a U-shape and hooking both ends thereof to the engaging claws of the reversing leaf spring 3a. For this reason, automatic assembling by a robot or the like is extremely difficult, and in reality, at present, this assembling operation is manually performed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has as its object to solve the above-mentioned problems, so that a reversing spring mechanism is made of one simple component which can be easily manufactured and assembled, and a stable reversing point can be obtained. It is an object of the present invention to provide an improved reversing spring contact switching mechanism and a thermal overload relay in which a bimetallic heat element responding to an overload current is combined with the contact switching mechanism.

[0008]

In order to achieve the above-mentioned object, the reversing spring contact opening / closing mechanism of the present invention is configured as follows. That is, three leg pieces including a pair of left and right outer leg pieces and a central leg piece are punched and formed in a “mountain” shape on one thin leaf spring material, and a curved tension spring portion is bent on the central leg piece. The formed reversing leaf spring, a first support arm for swingably supporting the reversing leaf spring with the tip edges of the left and right outer leg pieces as fulcrums, and a tip of the leg piece while applying a tensile force to the spring portion of the central leg piece. A second support arm for locking and fixing the edge in a fixed position, and a release lever disposed opposite to the central leg, and pressing the release lever by using the leg connection base of the reversing leaf spring as a contact drive unit. The contact is opened and closed by an inverting operation of the inverting leaf spring by an operation.

According to the reversing spring contact opening / closing mechanism having the above-described structure, the reversing spring mechanism is constituted by a single leaf spring, so that a troublesome assembling step of combining two parts unlike the conventional reversing spring mechanism is unnecessary. In addition, the number of parts is small, and it is possible to sufficiently cope with automatic assembly without relying on manual work for assembling into a product. Moreover, since there is only one reversing leaf spring, there is no portion where friction occurs during the reversing operation, and there is no buckling in the reversing operation, so that the reversing point is more stable than the conventional reversing spring mechanism. I do. This reversing spring contact opening / closing mechanism can be applied to various contact type relays that open and close contacts by snap action, or contact opening / closing mechanisms of switches.

Further, in the above-described reversing spring contact opening / closing mechanism according to the present invention, each component of the mechanism can be specifically configured in the following manner. 1) A plurality of locking grooves for variably adjusting the locking position of the tip of the central leg piece are formed in the second support arm, and the operating point of the reversing spring mechanism is adjustable. 2) A normally open or normally closed contact is attached to the leg connection base of the reversing leaf spring itself as a movable contact piece to reduce the size and size.

3) A contact drive lever is connected to the leg connecting base of the reversing leaf spring, and a separate contact mechanism is driven to open and close via the lever. 4) The side edge of the outer leg piece is bent into an L shape to form a reinforcing rib, and the bending rigidity of the leg piece is increased so that the outer leg piece does not buckle due to the tension spring force. 5) Opening a square window at the tip of the center leg of the reversing leaf spring, forming the edge of the window in an edge shape, and applying a tensile stress to the tension spring portion formed on the center leg, and Is hooked on the locking groove of the second support arm to stably lock and fix the central leg at a predetermined fulcrum position.

6) The tension spring portion formed on the center leg of the reversing leaf spring is formed wider than the other portions to relieve the stress applied to the spring portion and prevent the spring property from being reduced due to creep or the like. . On the other hand, the thermal overload relay according to the present invention transmits the bimetallic heat element responding to the overload current of the main circuit and the displacement of the heat element based on the overload current to the reversing spring contact opening and closing mechanism. A heat element based on overload current, combining a shifter and a swinging release lever for connecting the shifter and the center leg of the reversing leaf spring to invert the reversing leaf spring via the shifter by the displacement of the bimetal. The bimetallic displacement is transmitted to the reversing leaf spring of the contact opening / closing mechanism via the shifter and release lever, and the main circuit current interruption command is output by the contact opening / closing operation by the reversing operation of the reversing leaf spring. I do.

In order to reduce the size and size of the thermal overload relay, a normally closed contact is provided at its leg connecting portion by using the reversing leaf spring itself of the contact opening / closing mechanism in the above configuration as a movable contact piece. Further, there is a configuration in which a contact drive lever for driving a separately-installed normally open contact is connected to the leg connecting portion.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 to 3 for a thermal overload relay.
In the drawings of the embodiment, the same members corresponding to FIG. 4 are denoted by the same reference numerals. In FIG. 1, the heat element 2
Is the same as the conventional one shown in FIG. 4, in which a shifter 2c is connected to the free ends of three bimetals 2a with heaters 2b provided corresponding to the respective phases of the main circuit (three phases). The tip of the temperature compensating bimetal 5a coupled to the seesaw release lever 5 is opposed to the tip of 2c.

On the other hand, the reversing spring contact opening / closing mechanism 6 according to the present invention, which is connected to the heat element 2 via the release lever 5, has a reversing leaf spring 7 composed of a single leaf spring as will be described in detail later. A first and a second support arms 8 and 9 for supporting the reversing leaf spring 7, a normally closed contact 4a directly provided on the leaf spring using the reversing leaf spring 7 itself as a movable contact,
A normally open contact 4b separated from the reversing leaf spring 7;
It comprises an assembly of an L-shaped contact drive lever 10 having one end connected to a reversing leaf spring 7 and a tip facing the normally open contact 4b, and the release lever 5 described above. Reference numerals 11 and 12 are fixed contacts facing the normally closed contact 4a and the normally open contact 4b.

Here, the above-mentioned reversing leaf spring 7 is shown in FIG.
As shown in (b), three leg pieces including a pair of left and right outer leg pieces 7a and a long central leg piece 7b are punched out from one thin leaf spring material into a "mountain" shape. In addition, a curved tension spring portion 7c bent into a V-shape is formed in the middle portion of the center leg piece 7b. The extension spring portion 7c is formed such that its width dimension D is wider than the leg piece width d of the central leg piece 7b.
The outer leg piece 7a is formed such that the tip of the leg piece has a knife edge shape. On the other hand, a square window 7d-1 is provided at the tip of the center leg piece 7b.
A frame-shaped locking portion 7d having an opening is formed, and the inner edge of the square window 7d-1 is shaped like a knife edge at the tip like the outer leg piece 7a. Further, the outer leg piece 7a is formed by bending the side edges of the left and right leg pieces into an L-shape as shown to form a reinforcing rib 7a-1, thereby increasing the bending rigidity of the outer leg piece 7a. Further, the above-mentioned normally closed contact 4a is connected to the leg connecting base 7e, which connects the outer leg 7a and the center leg 7b by using the reversing leaf spring 7 as a movable contact piece, by a heat caulking method or the like. I have.

The reversing leaf spring 7 is supported between the first and second support arms 8 and 9 so that the reversing leaf spring 7 can be reversed and reversible as shown in FIG. That is, the outer leg 7a is swingably locked and fixed to the V-shaped groove 8a of the first support arm 8 with its leading edge as a hinge of a swing fulcrum. On the other hand, the central leg piece 7b has its tip locking portion 7d in a state where a tensile force is applied to the leg piece so as to extend the tension spring portion 7c.
The rectangular window 7d-1 is hooked on a V-shaped locking groove 9a formed in the second support arm 9 disposed on the lower side, and locked at a position displaced in the front-rear direction with the tip fulcrum of the outer leg piece 7a. It is fixed. A plurality of grooves 9a are formed in the support arm 9 in a sawtooth shape so that the locking position of the central leg 7b can be variably adjusted along the longitudinal direction of the arm. By forming the grooves 9a of the plurality of adjustment steps in the second support arm 9 in this manner, the reversing plate is formed in correlation with the above-described assembly of the bimetal 2a, the shifter 2c, and the release lever 5 of the heat element 2. The reversal point of the spring 7 can be adjusted on the second support arm, or the reversal point due to an assembly error can be corrected.

Further, as described above, the reversing leaf spring 7 is
In the mounted state of being bridged between the second support arms 8 and 9, the spring tension of the tension spring portion 7c and the first support arm 8
The reversing leaf spring 7 self-stands in a stable posture in a state where the spring resistance of the leg piece for tilting the reversing leaf spring 7 with the fulcrum as a fulcrum.
Therefore, the reversing leaf spring 7, the first support arm 8, the second
If the respective parts of the support arm 9 are unitized and assembled, the assembly of the reversing spring mechanism is treated as a single unit even when the reversing spring mechanism 6 is incorporated in a case such as a thermal overload relay as described later. And can be easily incorporated into the case. Further, although tension-induced stress always acts on the tension spring portion 7c formed on the central leg piece 7b, the stress is relaxed by forming the spring portion 7c wide as described above, and the spring force is reduced by creep or the like. It can be prevented from lowering and the life can be extended.

Next, the operation of the thermal overload relay in which the reversing spring contact opening / closing mechanism 6 having the above-described configuration is combined with the heat element 2 will be described with reference to FIGS. 1 (a) and 1 (b). In the steady state shown in FIG. 1A, the bimetal 2
a is retracted to the position shown by the solid line in the figure, and the release lever 5 is almost free. In this state, the reversing leaf spring 7 is tilted rightward by the spring force of the tension spring portion 7c formed on the center leg piece 7b with the tip edge of the leg piece 7a as a swing fulcrum, and the normally closed contact 4a is closed. The normally open contact 4b is open. On the other hand, when an overcurrent flows in a main circuit (a power supply circuit of an electric motor or the like) and the bimetal 2a is largely bent as shown by a dotted line in the figure, the shifter 2c is greatly displaced in the direction of the arrow P and pushes the release lever 5 to release the lever. Rotates counterclockwise. As a result, the tip of the release lever 5 pushes the central leg 7b of the reversing leaf spring 7 to the left. Then, the central leg piece 7b receiving the pressing force resists the spring force of the tension spring portion 7c and is located on the left side of the swing fulcrum of the outer leg piece 7a, that is, the reverse leaf spring 7b.
, The reversing leaf spring 7 is pulled by the tension spring portion 7c.
1B, the tip of the outer leg piece 7a is tilted to the left with the tip of the outer leg piece 7a as a fulcrum, as shown in FIG. 1B. As a result, the normally closed contact 4a opens and the normally open contact 4b reversely operates to be closed by being urged by the contact drive lever 10, and uses the contact operation signal to display the operation of the overload relay. And open the electromagnetic contactor connected to the main circuit to cut off the overload current.

In the state where the bimetal 2a of the heat element 2 cools down after the current interruption and retreats to the steady position, the reset button 4d (the resin case 1 of the relay as in FIG. 4).
When the reversing leaf spring 7 is forcibly pushed rightward, the reversing leaf spring 7 performs a reversing operation and returns to the initial state shown in FIG. As a reset method, in addition to the method of resetting by manually operating the reset button 4d, the position where the reversal of the reversing leaf spring 7 is stopped by the overload current is regulated by a stopper, and after the current is cut off, the bimetal
When a returns to the steady state and the shifter 2c retreats, an automatic resetting method in which the spring force of the reversing leaf spring 7 itself automatically returns to the initial position can be adopted.

In the illustrated example, the normally closed contact 4a is directly attached to the reversing leaf spring 7 itself as a movable contact piece to reduce the size and size of the contact opening / closing mechanism. However, the present invention is not limited to this. For example, as shown in FIG. 4, the normally closed and normally open contact mechanism of the thermal overload relay is separated from the reversing leaf spring 7 and incorporated into the slider, and this contact mechanism is operated by reversing the reversing leaf spring 7. It can be configured to open and close. Further, it is needless to say that the reversing spring contact opening / closing mechanism can be applied to various contact type relays other than the thermal overload relay or the contact opening / closing mechanism of the switch.

[0022]

As described above, according to the structure of the present invention, the following effects can be obtained. 1) The reversing leaf spring of the reversing spring contact opening / closing mechanism is formed by punching and bending a single thin leaf spring material. In addition to having a small number of points, it can be configured inexpensively, and is easy to assemble and assemble into relays, etc., and can fully cope with automatic assembly. Unlike the conventional two-part reversing spring mechanism, there is no sliding part between the parts, and the buckling reversal method is not used. The curved spring portion formed on the center leg piece is reversed as a tension spring. Since the operation is performed, the inversion operation point does not vary and the operation characteristics are stabilized.

2) The thermal overload relay of the present invention in which such a reversing spring contact opening / closing mechanism is combined with a heat element has a smaller number of parts and is smaller and more compact than the conventional one. As well as being able to easily assemble the product easily and obtain stable operating characteristics,
Reliability is further improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a thermal overload relay according to an embodiment of the present invention, where (a) is an assembly configuration diagram of a reversing spring contact opening / closing mechanism combining a bimetallic heat element, and (b).
Figure showing the reversing operation state of the reversing spring contact opening and closing mechanism

FIG. 2 is a detailed structural view of a reversing leaf spring in FIG. 1,
(a) is a front view, (b) is a side view

3 is an external perspective view of an assembled state in which the reversing leaf spring of FIG. 2 is locked and fixed to a support arm.

FIG. 4 is a configuration diagram of a main part of a conventional thermal overload relay.

FIG. 5 is a structural view of a reversing spring mechanism employed in a conventional contact opening / closing mechanism, (a) is a front view, and (b) is a side view.

[Explanation of symbols]

 Reference Signs List 2 Heat element 2a Bimetal 2b Heater 2c Shifter 4a Normally closed contact 4b Normally open contact 5 Release lever 6 Reversing spring contact opening and closing mechanism 7 Reversing leaf spring 7a Outer leg piece 7a-1 Reinforcement rib 7b Central leg piece 7c Curved tension spring Part 7d Locking part 7d-1 Square window 7e Leg piece connecting base 8 First support arm 9 Second support arm 9a Lock groove 10 Contact drive lever D Width of tension spring part

Continuation of front page (72) Inventor Katsumi Akiike 1-1, Tanabe-Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Fuji Electric Co., Ltd.

Claims (9)

[Claims] An inverting spring contact opening / closing mechanism for driving a movable contact to an opening / closing position by a snap action of an inversion spring mechanism responsive to operation of a release lever, wherein a pair of left and right outer leg pieces are attached to one thin leaf spring material. , And the center leg piece are punched and formed into a “mountain” shape, and the center leg piece is formed by bending a curved tension spring portion. A first support arm that swingably supports a reversing leaf spring as a fulcrum, and a second support arm that locks and fixes the tip edge of the leg piece in a fixed position while applying a tensile force to the tension spring portion of the central leg piece. And a release lever arranged opposite to the central leg, and the opening / closing drive of the contact is performed by the reversing operation of the reversing leaf spring by the pressing operation of the release lever, using the leg connecting base of the reversing leaf spring as a contact driving unit. Reversing spring type Point opening and closing mechanism. 2. The contact opening and closing mechanism according to claim 1, wherein a plurality of locking grooves for variably adjusting the locking position of the tip of the central leg are formed in the second support arm. Reversing spring contact opening and closing mechanism. 3. A reversing spring contact opening / closing mechanism according to claim 1, wherein the reversing leaf spring itself is a movable contact piece and a normally open or normally closed contact is attached to a leg connecting base thereof. Spring contact opening and closing mechanism. 4. A contact opening / closing mechanism according to claim 1, wherein a contact drive lever is connected to a leg connecting base of the reversing leaf spring, and a separate contact mechanism is opened / closed via said lever. Reversing spring contact opening and closing mechanism. 5. The reversing spring according to claim 1, wherein a reinforcing rib is formed by bending a side edge of the leg piece into an L-shape so as to increase the bending rigidity of the outer leg piece. -Type contact opening and closing mechanism. 6. A contact opening / closing mechanism according to claim 1, wherein a square window is opened at the tip of the center leg of the reversing leaf spring, and the edge of the window is formed in an edge shape to lock the second support arm. A reversing spring contact opening / closing mechanism, which is locked and fixed in a groove. 7. The contact opening / closing mechanism according to claim 1, wherein a tension spring portion formed on a central leg of the reversing leaf spring is formed wider than other portions. 8. A bimetallic heat element responsive to an overload current of the main circuit, and three leg pieces comprising a pair of left and right outer leg pieces and a central leg piece on one thin leaf spring material are formed into a "mountain" shape. In addition, a curved spring portion is formed on the center leg piece, and the leading edge of the outer leg piece is locked to the first support arm to serve as a fulcrum.
A reversing leaf spring locked and fixed to the support arm of the above, and a shifter for transmitting the displacement of the heating element based on the overload current,
A pivoting release lever that connects the shifter and the center leg of the reversing leaf spring to invert the reversing leaf spring via the shifter by the displacement of the bimetal, and opens and closes by the reversing action of the reversing leaf spring. A thermal overload relay having a normally open or normally closed contact. 9. A thermal overload relay according to claim 8, wherein the reversing leaf spring of the contact opening / closing mechanism itself is a movable contact piece, and a normally closed contact is provided at a leg connecting portion thereof. A thermal overload relay characterized in that a contact drive lever for driving a normally open contact is connected to the relay.