Reliable Electrical Connection Between a Stationary Terminal and an Armature of a Switch

This invention relates to an electrical connection structure for a stationary terminal and a movable piece in a micro switch or the like.

One example of a conventional micro switch is as shown in FIGS. 22 and 23.

The micro switch comprises: a stationary terminal 1 which is a common terminal, and a pair of stationary terminals 4 and 5 which are fixedly inserted in a resin casing 9; a switching movable piece 3 having its base end portion engaged with a V-shaped engaging groove formed in one engaging piece 1a of the stationary terminal 1 (hereinafter referred to as "an armature 3", when applicable), and a movable contact 3a provided on its free end portion in such a manner that the movable contact appears on both sides (the upper and lower surfaces) of the free end portion; a movable spring 7 for operating the armature with a snap, the spring 7 having its base end portion engaged with a V-shaped engaging groove 6 formed in the other engaging piece 1b of the stationary terminal 1 and its free end portion engaged with the free end portion of the armature 3; and a push button 8 supported by the casing in such a manner that it is pushed against the middle of the armature 3 when depressed. In the normal state of the micro switch; that is, when the push button 8 is not depressed yet, as shown in FIGS. 22 and 23 the free end portion of the armature 3 is urged upwardly by the elastic restoring force of the movable spring 7, so that the movable contact 3a is held in contact with the contact of the stationary terminal 4 (which is a normally closed contact). When, under this condition, the push button 8 is depressed, the middle of the armature 3 is displaced below a predetermined position, instantaneously the armature 3 is urged downwardly by the elastic restoring force of the movable spring 8 (snap action), so that the movable contact 3a is tripped over to the contact 5a of the other stationary terminal 5 (which is a normally open contact). Thus, the switching operation has been accomplished.

In the above-described micro switch, the contact resistance of the switch occurs not only in a portion between the contact 3a and either of the contacts 4a and 5a but also in each of engaging portions between the stationary terminal 1 and the armature 3, between the movable Spring 7 and the stationary terminal 1 and between the movable spring 7 and the armature 3.

However, the frequent slide motion in the engaging portions makes the contact resistance unstable, as a result of which the switch is liable to become low in contact reliability. Furthermore, sometimes the micro switch suffers from the following difficulty: When the contact resistance increases, heat is generated to increase the temperature of the micro switch, thus adversely affecting the durability of the latter. Thus, there is much room for improvement in the durability of the conventional micro switch.

In order to improve the contact between the engaging groove 2 and the armature 3 in reliability, there has been proposed a method in which the engaging portions of the engaging groove 2 and the armature 3 are plated with silver. However, the method is not economical because the sliver plating will increase the manufacturing cost of the micro switch.

In order to improve the reliability in electrical connection of the stationary terminal 1 and the armature 3, a method has been proposed in which, as shown in FIG. 21, both ends of a lead wire 12 are soldered to the portions of the stationary terminal 1 and the armature 3 which are less displaced from each other. However, the method is also disadvantageous in that the number of components and the number of manufacturing steps are increased as much, and accordingly the manufacturing cost is increased.

In view of the foregoing, an object of this invention is to provide a switch which can be manufactured relatively readily without increase of the number of components, and is high in the reliability in electrical connection of the stationary terminal and the armature.

The foregoing object of the invention has been achieved by the provision of a first switch in which an armature swingably coupled to a stationary terminal is operated by depression of a push button to trip between contacts, and in which, the stationary terminal and the armature are partially welded to each other. In the first switch, the stationary terminal and the armature coupled to it are stably electrically connected to each other through the welded portions.

In the first switch, it is possible that the armature is swingably engaged with the stationary terminal through their engaging portions, and the armature and the stationary terminal are welded to each other by using portions thereof other than the engaging portions. The armature and the stationary terminal are electrically connected to each other by using their portions which are other than their engaging portions through which the armature and the stationary terminal are mechanically coupled to each other. That is, in the switch, the mechanical connection and the electrical connection of the stationary terminal and the armature are established independently of each other.

In the first switch, it is also possible that an engaging groove is formed in an engaging piece of the stationary terminal, the base end portion of the armature is engaged with the engaging groove, a first tongue piece extended from the armature is laid on a second tongue piece formed by bending the middle portion of the engaging piece, and the two tongue pieces are welded together. The welding portions of the stationary terminal and the armature are located between the engaging portions through which the stationary terminal and the armature are mechanically engaged with each other; that is, the welding portions are located where the stationary terminal and the armature are less displaced from each other. Hence, the welding portions will not interfere the motion of the armature. The first tongue piece extended from the armature may be bent, and the end portion of the first tongue piece thus bent may be welded to the second tongue piece formed by bending the middle portion of the engaging piece. The tongue piece extended from the armature is bent, and therefore although the end of the tongue is welded to the stationary terminal, the armature can be swung (or tripped) smoothly with the engaging portion as a fulcrum.

In the first switch, it is also possible that an engaging groove is formed in an engaging piece of the stationary terminal, the base end portion of the armature is engaged with the engaging groove thus formed, an engaging recess is formed in the outer surface of the middle portion of the engaging piece, and a tongue piece extended from the armature is engaged with the engaging recess, and welded to the stationary terminal. The welding portions of the stationary terminal and the armature are located where the stationary terminal and the armature are less displaced from each other, and the welding portions will never interfere with the motion of the armature. In the switch, the engaging piece of the stationary terminal, having no cut, is high rigidity.

Further, the foregoing object of the invention has been also achieved by the provision of a second switch in which an armature swingably coupled to a stationary terminal is operated by depression of a push button to trip between the contacts, and in which a movable spring is laid between the stationary terminal and the armature and supported by and welded to the stationary terminal and the armature. The elastically movable spring is welded to the stationary terminal and the armature, and therefore the welding portions scarcely resist the tripping motion of the armature.

Moreover, the foregoing object of the invention has been also achieved by the provision of a third switch in which an armature swingably coupled to a stationary terminal is operated by depression of a push button to trip between the contacts, and in which an engaging groove is formed in an engaging piece of the stationary terminal, the base end portion of the armature is engaged with the engaging groove thus formed, a tongue piece extended from the armature is placed on a tongue piece protruded from the stationary terminal independently of the engaging piece, and the two tongue pieces are welded together. The engaging piece supporting the base end portion of the armature on the stationary terminal, and the tongue piece onto which the tongue piece of the armature is welded, are formed independently of each other. Therefore, when those tongue pieces are bent which are formed by cutting the stationary terminal, they will not interfere with each other, and therefore they can be formed with high accuracy.

In the accompanying drawings:

FIG. 1 is a vertical sectional view showing a switch, which constitutes a first embodiment of this invention;

FIG. 2 is an exploded perspective view of the switch shown in FIG. 1;

FIG. 3 is a perspective view showing essential components of the switch shown in FIG. 1;

FIG. 4 is an exploded perspective view of essential components of the switch shown in FIG. 1;

FIG. 5 is a perspective view showing essential components of a switch, which constitutes a second embodiment of the invention;

FIG. 6 is an exploded perspective view of essential components of the switch shown in FIG. 5;

FIG. 7 is a vertical sectional view showing a switch, which constitutes a third embodiment of the invention;

FIG. 8 is an exploded perspective view of essential components of the switch shown in FIG. 7;

FIG. 9 is a perspective view of essential components of the switch shown in FIG. 7;

FIG. 10 is a perspective view of essential components of a switch, which constitutes a fourth embodiment of the invention;

FIG. 11 is an exploded perspective view of essential components of the switch shown in FIG. 10;

FIG. 12 is a vertical sectional view showing a switch, which constitutes a fifth embodiment of the invention;

FIG. 13 is an exploded perspective view of essential components of the switch shown in FIG. 12;

FIG. 14 is a vertical sectional view showing a switch, which constitutes a sixth embodiment of the invention;

FIG. 15 is an exploded perspective view of essential components of the switch shown in FIG. 14;

FIG. 16 is a perspective view of essential components of the switch shown in FIG. 14;

FIG. 17 is a vertical sectional view showing a switch, which constitutes a seventh embodiment of the invention;

FIG. 18 is a perspective view of essential components of the switch shown in FIG. 17;

FIG. 19 is a perspective view showing the stationary terminals of the switch shown in FIG. 17;

FIG. 20 is a perspective view showing the stationary terminals assembled in the switch shown in FIG. 17;

FIG. 21 is a perspective view showing essential components of a comparative example of the switch;

FIG. 22 is a vertical sectional view showing a conventional switch; and

FIG. 23 is a perspective view of essential components of the conventional switch shown in FIG. 22.

Preferred embodiments of this invention will be described with reference to the accompanying drawings.

A switch, which constitutes a first embodiment of the invention, is as shown in FIGS. 1 through 4. The switch is equal in fundamental structure to the above-described conventional switch. That is, the switch comprises: a stationary terminal 1 which is a common terminal with a pair of engaging pieces 1a and 1b; a movable piece 3 having its base end portion engaged with a V-shaped engaging groove 2 formed in the engaging piece 1a of the stationary terminal 1, and a movable contact 3a provided on its free end portion in such a manner that the movable contact appears on both sides (the upper and lower surfaces) of the free end portion (hereinafter referred to as "an armature 3", when applicable); a stationary terminal 4 which is a normally closed terminal with a stationary contact 4a which is confronted with the movable contact 3a from above; a stationary terminal 5 which is a normally open terminal having a stationary contact 5a which is confronted with the movable contact 3a from below; a movable spring 7 for operating the armature with a snap, the spring 7 having its base end portion engaged with a V-shaped engaging groove 6 formed in the other engaging piece 1b of the stationary terminal 1 and its free end portion engaged with the free end portion of the armature 3; and a push button 8 which is pushed against the middle of the armature 3. Those components 1 through 8 are fixedly held by a resin casing 9 which is made up of a casing body 9a and a cover casing 9b.

In the normal state of the switch; i.e., when the push button 8 is not pushed yet, as shown in FIG. 1 the free end portion of the armature 3 is urged upwardly by the elastic restoring force of the movable spring 7, so that the stationary contact (or normally closed contact) 4a of the stationary terminal 4 is held in contact with the upper surface of the movable contact 3a of the armature 3. When the pushed button 8 is pushed, the middle of the armature 3 is deflected downwardly, so that, when the engaging point of the armature 3 and the spring 7 goes across the prolongation (or dead point) of the straight line connecting the two engaging grooves 2 and 6, instantaneously the armature is displaced downwardly with a snap by the elastic restoring force of the spring 7. As a result, the lower surface of the movable contact 3a is brought into contact with the stationary contact (or normally open contact) of the stationary terminal 5.

In the stationary terminal 1, a tongue piece 1c is extended from the middle, in the direction of width, of the engaging piece 1a, and bent sidewards. The armature 3 has an engaging edge 3b, which is engaged with the engaging piece 1a of the stationary terminal 1. A tongue piece 3c is extended from the engaging edge 3b in such a manner that it is laid on the tongue piece 1c of the stationary terminal 1. The two tongue pieces 1c and 3c are welded together at the ends by soldering, so that the stationary terminal 1 and the armature 3 are positively electrically connected with each other. Those tongue pieces 1c and 3c may be connected by laser welding or spot welding.

A second embodiment of the invention is as shown in FIGS. 5 and 6. The second embodiment is also similar in fundamental structure to the above-described first embodiment. In the second embodiment, the tongue piece 3c of the armature 3 is longer than in the first embodiment, and it is curved. The end portion of the tongue piece 3c thus curved is connected to the tongue piece 1c of the stationary terminal 1 by soldering or laser welding or spot welding. The welding of the tongue pieces in this manner scarcely affects the motion of the armature; that is, the armature 3 can be smoothly tripped with a snap.

A third embodiment of the invention is as shown in FIGS. 7 through 9. The third embodiment is also similar in fundamental structure to the above-described first embodiment. In the third embodiment, the tongue piece 1c is extended longer from the middle of the engaging piece 1a of the stationary terminal 1 than in the first embodiment, and is bent sidewards at a level lower than in the first embodiment. The tongue piece 3c is extended long from the armature 3, and bent downwardly at the end. The tongue piece 3c is set above the tongue piece lc, and under this condition the free ends of those tongue pieces 3c and 1c are connected together by soldering, laser welding or spot welding. Hence, the adverse effect of the welding of the tongues pieces on the motion of the armature can be more positively eliminated; that is, the armature 3 can be more smoothly tripped with a snap. In the third embodiment, the push button 8 has a recess 8a to eliminate its interference with the tongue pieces 1c and 3c.

A fourth embodiment of the invention is as shown in FIGS. 10 and 11. The fourth embodiment is also similar in fundamental structure to the above-described first embodiment. In the fourth embodiment, an engaging recess 1d is formed in the outer surface of the engaging piece 1c at the middle by pressing. A tongue piece 3c is extended downwardly from the engaging edge 3b of the armature 3 which is engaged with the engaging piece 1a of the stationary terminal 1. The tongue piece 3c thus extended is inserted into the engaging recess 1d. Under this condition, the tongue piece 3c is connected to the stationary terminal 1 by soldering, laser welding or spot welding.

In each of the above-described first through fourth embodiments of the invention, the stationary terminal 1 and the armature 3 are welded to each other by using their portions which are in direct contact with each other. However, they may be welded by using their portions which are in contact with each other through the movable spring 7.

A fifth embodiment of the invention is as shown in FIGS. 12 and 13. A switch shown in FIGS. 12 and 13 is different in structure from the above-described switches.

In the switch, its stationary terminal 1 has an engaging hole 10, into which one end portion of an operating metal part 11 is inserted. The other end portion 11a of the operating metal part 11 has an engaging groove 11b, with which one end portion of an armature 3 is engaged. The stationary terminal 1 has an engaging groove 1e, with which one end portion of a movable spring 7 is engaged. The other end portion of the spring 7 is engaged with the free end portion of the armature 3. When a push button 8 set in a casing 9 is depressed, the other end portion 11a of the operating metal part 11 is moved downwardly thereby. As a result, the armature 3 is tripped with a snap by the elastic restoring force of the spring 7, so that the movable contact 3a of the armature 3 is moved from the contact (or normally closed contact) 4a of an upper stationary terminal 4 over to the contact (or normally open contact) 5a of a lower stationary terminal 5.

The movable spring 7 has tongue pieces 7a and 7b at both ends which are formed by cutting for the stationary terminal 1 and the armature 3, respectively. The ends of those tongue pieces 7a and 7b are connected to the stationary terminal 1 and the armature 3 by soldering, laser welding or spot welding. Thus, the stationary terminal 1 is electrically stably connected to the armature 3 through the movable spring 7.

A sixth embodiment of the invention is as shown in FIGS. 14 through 16. The sixth embodiment is similar in fundamental structure to the first embodiment. In the sixth embodiment, its stationary terminal 1 has a pair of engaging pieces 1a and 1b which are bent, and a tongue piece 1c between the engaging pieces 1a and 1b. The tongue piece 1c is formed by cutting the body of the stationary terminal 1, and bent at the end. The armature has an elongated tongue piece 3c. The end portion of the tongue piece 3c is connected to the tongue piece 1c by soldering, laser welding or spot welding.

The sixth embodiment is free from the difficulty accompanying the above-described first, second and third embodiments that, since the tongue piece 1c is bent when formed by using the engaging piece 1a, the latter 1a is unavoidably deformed, so that the engaging groove 2 is lowered in positional accuracy.

A seventh embodiment of the invention is as shown in FIGS. 17 through 20. In a switch shown in those figures, its resin casing 9 is made up of a casing body 9a and a cover 9b which are separable from each other, and its stationary terminals 1, 4 and 5 are held by the casing body 9a in such a manner that they are arranged in a line with their flat base end portions in one plane. The stationary terminal 1 has a pair of engaging pieces 1a and 1b, and a tongue piece 1c at predetermined positions, which are bent independently of one another. The armature 3 has an elongated tongue piece 3c, the end of which is connected to the tongue piece 1c by soldering, laser welding or spot welding.

As is apparent from the above description, the invention has the following merits or effects:

In a switch of a first aspect of the invention, in which an armature swingably coupled to a stationary terminal is operated by depression of a push button to trip between contacts and the stationary terminal is welded to the armature, the electrical connection of the stationary terminal and the armature is greatly improved in reliability; that is, they are high in durability. In welding the stationary terminal and the armature to each other, it is unnecessary to use an additional component such as a lead wire; that is, the stationary terminal is welded directly to the armature. Therefore, they can be relatively readily welded together by soldering, laser welding or spot welding. Hence, the switch can be manufactured at relatively low cost without increase in the number of components or in the number of manufacturing steps; that is, the switch should be highly appreciated in practical use.

When the armature is swingably engaged with the stationary terminal through engaging portions thereof, and the armature and the stationary terminal are welded to each other by using portions thereof other than the engaging portions in the first switch, the stationary terminal is directly welded to the armature; however, the welding scarcely affects the tripping motion of the armature. Hence, the switch is excellent in operating performance, having the same effects as the first switch.

When an engaging groove is formed in an engaging piece of the stationary terminal, the base end portion of the armature is engaged with the engaging groove, a first tongue piece extended from the armature is laid on a second tongue piece formed by bending the middle portion of the engaging piece, and the two tongue pieces are welded together in the first switch, the difficulty is more effectively eliminated that the welding adversely affects the tripping motion of the armature; that is, it is further improved in operating to performance. Further, when the first tongue piece extended from the armature is bent, and the end portion of the first tongue piece is welded to the second tongue piece formed by bending the middle portion of the engaging piece, the armature can trip more smoothly, and the difficulty is positively eliminated that the welded portions are for instance cracked when the armature is tripped repeatedly. That is, the switch is high in durability in quality, and in reliability.

When an engaging groove is formed in an engaging piece of the stationary terminal, the base end portion of the armature is engaged with the engaging groove thus formed, an engaging recess is formed in the outer surface of the middle portion of the engaging piece, and a tongue piece extended from the armature is engaged with the engaging recess, and welded to the stationary terminal in the first switch, the engaging piece of the stationary terminal, which is provided for connecting the latter to the armature, is high in mechanical strength. Hence, the switch has a merit that it is higher in durability, in addition to the merits of the first switch.

In a switch of a second aspect of the invention, in which an armature swingably coupled to a stationary terminal is operated by depression of a push button to trip between the contacts, and a flexible movable spring is laid between the stationary terminal and the armature and supported by and welded to the stationary terminal and the armature, the welding will not adversely affect the tripping motion of the armature, and the electrical connection of the stationary terminal and the armature is high in reliability. That is, the switch is excellent in performance.

In a switch of a third aspect of the invention, in which an armature swingably coupled to a stationary terminal is operated by depression of a push button to trip between contacts, an engaging groove is formed in an engaging piece of the stationary terminal, the base end portion of the armature is engaged with the engaging groove thus formed, a tongue piece extended from the armature is placed on a tongue piece protruded from the stationary terminal independently of the engaging piece, and the two tongue pieces are welded together, the difficulty that the welding adversely affects the tripping motion of the armature is more positively eliminated. That is, the switch is much higher in operating performance.

In each of the switches, in order to improve the reliability in electrical connection of the switching elements, namely, the stationary terminal and the armature, they are welded directly to each other. Hence, the switch is smaller in the number of components and in the number of manufacturing steps than the switch which uses lead wires for electrical connecting the switching elements. Accordingly, the switch is lower in manufacturing cost.