Small-Sized Rotary Switch

This invention generally relates to a small-sized rotary switch. More particularly, the present invention relates to improvements in a stopper mechanism of a small-sized rotary switch.

Conventionally, a stopper mechanism is constructed, as shown in FIG. 1, in the following manner. A mounting screw 1 is provided on a cap 2 which is provided at its top portion with a plurality of apertures 2a. A pawl formed stopper 3 provided at its center with an opening 3a is fitted onto the mounting screw 1 of the cap 2 so that the pawl 3b is selectively inserted into one of the apertures 2a of the cap 2. The stopper 3 is then fixed to the cap 2 by tightening nuts 4 onto the screw 1. In the aforementioned construction, when a projection 5a, provided on a rotary shaft 5, engages with the pawl 3b of the stopper, the rotary shaft 5 is stopped.

Although there is no particular problem in the mechanical strength of the mechanism thus described, the problem in recent years of damage due to the environment arises from the miniaturization of switches. Namely, because of the presence of apertures 2a provided on the top portion of the cap 2 for insertion the pawl 3b of the stopper 3, the problem arises in that sulfide gas promoting oxidization of the electrical contacts or dust in the air intrudes into the cap through the apertures and causes an obstacle to the engagement between the contacts.

Furthermore, in recent years, small-sized switches tend to be used particularly in such a manner that the terminals of the switches are directly welded onto a printed circuit board. In such a case, there is a so-called washing step during which flux produced in welding is washed away after the small-sized switches are welded in an automatic welding vessel. At that time, in the conventional construction of switches, washing liquid flows onto the switch body through the apertures 2a of the cap, and therefore there is the possibility and thus disadvantage that the flux will not be washed out by a normal washing device. Consequently, the washing must be carefully controlled by using a brush for each switch, which is quite troublesome.

Therefore, it is an object of the present invention to provide a novel rotary switch which can eliminate the aforementioned disadvantages by providing a rotary stopper mechanism on the cap which eliminates the conventional apertures from the cap thereby sealing the switch.

It is another object of the invention to provide a novel small-sized rotary switch in which it is easier to alter the number of contacts of the switch, if necessary, thereby merely requiring one kind of switch.

In order to accomplish the foregoing, there is provided a small-sized rotary switch which comprises a switch base plate, fixed contacts formed on the base plate, a movable contact selectively engageable with one of said fixed contacts, a converter for holding the movable contact, a rotary shaft for rotating the converter, a cap adapted to accommodate all of the above-mentioned members therein and provided at the upper portion thereof with an aperture through which the rotary shaft extends, a stopper plate attached to the rotary shaft and disposed on the upper portion of the cap, the stopper plate being provided with an ear piece, and a variable stopper attached to the upper portion of the cap, with the stopper plate intervening therebetween, with an engagement projection being formed on either one of the cap and the variable stopper to engage the ear piece of the stopper plate.

The present invention will now be described in detail by reference to embodiments illustrated in the accompanying drawings in which;

FIG. 1 is an exploded perspective view showing a main portion of a switch of a conventional type,

FIG. 2 is an exploded perspective view showing an embodiment of a main portion of a small-sized rotary switch according to the present invention,

FIG. 3 is a centrally cross-sectional view of the embodiment shown in FIG. 2,

FIG. 4 is a top plan view showing the embodiment shown in FIG. 2 without the variable stopper,

FIG. 5 is a cross-sectional view showing the variable stopper in the embodiment shown in FIG. 2,

FIG. 6 is a cross-sectional view showing the stopper plate in the embodiment shown in FIG. 2,

FIG. 7 is a perspective view showing another embodiment of a main portion of the present invention,

FIG. 8 is a perspective view showing still another embodiment of a main portion of the invention,

FIG. 9a is a view showing still another embodiment of a main portion of the present invention,

FIG. 9b is a centrally cross-sectional view showing the variable stopper in the embodiment shown in FIG. 9b, and

FIG. 10 is a perspective view showing still another embodiment of a main portion of the invention.

Preferred embodiments of the present invention will be now described in detail with reference to the accompanying drawings.

In FIGS. 2 through 6, showing one embodiment of the present invention, a switch base plate 11 is formed with a concave-convex or corrugated portion 11a functioning to provide a changeover action by moving ball 12 thereon under the pressure of a resilient piece 13, a plurality of fixed contact pieces 11b and a common contact piece 11c. Each of the fixed contact pieces 11b extend downwardly through the base plate 11 to form an electric terminal 11b' at its end. A reference numeral 11d indicates a cut-out portion for fixing a hereinafter described cap to the base plate. The switch further includes a movable contact piece 14, a converter 15 for holding and moving the movable contact piece, a rotary shaft 16, and rubber rings 17 and 18, respectively. There is provided a cut-out portion 15a in which the ball 12 is positioned, a recess 15b in which the lower portion 16a of the rotary shaft 16 is fitted, a recess 15c in which the leg portion 13a of the resilient piece 13 is fitted, and a cut-out 16b, respectively.

A cap 19 which is one of main members according to the present invention, is cylindrically formed and is engraved at its upper peripheral surface with FIGS. 19a (Numerals 1-12) indicating the number of contacts. The cap 19 is provided at its upper central portion with an aperture 19b through which the rotary shaft 16 extends. An area of the upper surface of the cap 19 inside the area engraved with the FIGS. 19a and around the aperture 19b is slightly lower than the upper peripheral surface of the cap to form a recess 19c. The recess 19c is concentrically formed centrally about the aperture with a medially placed groove 19e having a stopper 19d and at its outer side portion with a plurality of holes 19f corresponding to the FIGS. 19a. The stopper 19d may be a projection.

In assembling, after the sub-assembly comprising the ball 12, the resilient piece 13, the movable contact 14, the converter 15, the rotary shaft 16, and the rubber rings 17 and 18 is disposed on the base plate 11, the cap 19 is superimposed on the sub-assembly and both members are connected by engaging a pawl piece 19g of the cap 19 with the cut-out 11d of the base plate.

A stopper plate 20 which is one of the main members according to the present invention, is disposed within the recess 19c of the cap 19 and comprises an aperture 20a which is fitted onto and fixed to the rotary shaft 16, an ear piece 20b which is engaged by a projection 21b of a variable stopper 21, hereinafter described in detail, and a pawl piece 20c which moves along the groove 19e of the cap 19.

A variable stopper 24 which is still another of the main members according to the present invention, is constructed in the form of a circular cap. The variable stopper 21 has formed at the center of its upper surface an aperture 21a through which the rotary shaft 16 extends and is provided in the upper surface with an engagement projection 21b which engages with the ear piece 20b of the stopper plate to stop the rotation of the rotary shaft 16. If the engagement projection 21b is constructed so that its leading end is adapted to selectively fit into one of the holes 19f formed in the recess portion 19c of the cap 19, the variable stopper 21 can be easily fixed to the cap 19. However, the present invention is not limited to such a construction. The variable stopper 21 has also formed in the surface corresponding to the figures 19a, a window 21c through which the figures 19a are visible and one may be selected. However, in case where the variable stopper is made of a transparent material, the window may be eliminated.

In FIG. 7, which is a perspective view showing another embodiment of a main portion according to the present invention, a cap 29 is formed as a polygon having apexes, the number of which corresponds to that of the electrical contacts. The cap 29 is provided at its center portion with an aperture 29b through which the rotary shaft 16 (see FIG. 2) rotatably extends and has concentrically formed a recess 29c around the aperture 29b with a groove 29e having a stopper 29d. A variable stopper 31 is superimposed on the cap 29, having a stopper plate, not shown, intervening therebetween, which is identical to the stopper plate 20 shown in FIG. 2. The variable stopper 31 is formed as a polygon having a inner surface of the side portion corresponding to the circumferential surface of the cap 29 and is provided at its center with an aperture 31a through which the rotary shaft 16 rotatably extends. The variable stopper 31 is provided on the inner surface of the upper portion with an engagement projection 31b which will engage with the ear piece of the stopper plate identical to that of the stopper plate 20 shown in FIG. 2. The variable stopper 31 is also provided in the upper surface with a window 31c. Furthermore, the engagement projection 31b is adapted to be located so as to project into the recess 29c of the cap 29 lateral to the groove 29e.

FIG. 8 is a perspective view showing still another embodiment according to the present invention. In FIG. 8, a cap 39 is provided at its side surface with recesses. The number of recesses which correspond to the number of contacts in this instance, is twelve the cap has a center portion an aperture 39b through which the rotary shaft 16 shown in FIG. 2 extends. The recess 39c is concentrically formed in its surface with a groove 39e having a stopper 39d. Although, in this embodiment, a variable stopper is not shown, the variable stopper used herewith will be provided with a side portion an inner surface provided with a plurality of projections corresponding to the recesses provided on the circumferential surface of the cap 39. The inner surface of the upper portion of the variable stopper has a profile similar to that of the variable stopper 31 shown in FIG. 7.

In the constructions of the embodiments illustrated in FIGS. 7 and 8, it is not necessary to provided each cap with holes 19f as in the embodiment illustrated in FIG. 2.

FIGS. 9a and 9b show another embodiment according to the present invention. FIG. 9a is a perspective view showing a cap, a stopper plate, and a variable stopper and FIG. 9b is a cross-sectional view of the variable stopper. In the present embodiment, the constructional elements comprising the cap and variable stopper are reversed with those elements of the embodiment illustrated in FIGS. 2 through 6. A cap 49 is formed with an aperture 49a through which the rotary shaft 16 (see FIG. 2) extends and is provided at its upper portion with projection 49b and a window 49c. The stopper plate 50 which is disposed on the cap 49 is formed with an aperture 50a through which the rotary shaft 16 extends, an ear piece 50b which engages the projection 49b, and a pawl piece 50c which engages a groove 51e of the variable stopper 51. The variable stopper 51, which is placed on the cap 49 and the stopper plate 50, is formed on the upper surface of a top portion with figures 51a corresponding to the number of contacts and at its center with an aperture 51b through which the rotary shaft 16 extends. The variable stopper 51 is further formed on the inner surface of its top portion with a recess 51c in which the stopper plate 50 is disposed, a circular groove 51e having a stopper, and holes 51f one of which is selectively engaged by the projection 49b of the cap 49 to serve to stop the movement of the ear piece 50b of the stopper plate at the number which corresponds to the number of contacts, respectively.

FIG. 10 shows still another embodiment according to the present invention. In the embodiment, a cap 59 is formed around its aperture 59a with a projection 59b, a portion of which forms an engagement member 59c. The pawl piece 60c of a stopper plate 60 is engageable with the engagement member 59c. Apertures 59a and 60a are provided through which the rotary shaft 16 (see FIG. 2) extends along with ear piece 60b.

Referring now to FIGS. 2 through 6 once again, in the illustrations, as an alternative to the construction of the variable stopper 21, the variable stopper may be constructed in the form of a disc rather than circular-shaped cap and may be attached to the upper portion of the cap 19 as by a screw. In such a case, the variable stopper is provided with apertures, the number of which corresponds to the number of the holes 19f of the cap 19. By inserting screws through one or more selected apertures into one or more holes, the variable stopper is located in a fixed position relative to the cap 19.

In the aformentioned contruction according to the present invention, although twelve contacts are shown to be included in a circuit, by changing the position in which the variable stopper is disposed on the cap 19, that is, by selecting one of the positions indicated by the figures 19a of the cap 19 through the engagement projection 21b, the range of rotation of the rotary shaft 16 can be limited thereby optionally setting, for example, four contacts or six contacts in a circuit. Furthermore, the number of contacts are displayed in the window 21c. Consequently, while monitoring the figures displayed on the window 21c, a desired number of contacts can be set and fixed by movement of the variable stopper 21.

In the embodiment, although the stopper plate 20 is formed with the pawl piece 20c which slidably moves in the groove 19e of the cap 19, and the stopper 19d is engaged by the pawl piece 20c to stop the same thereby constituting one of the stop points of the rotary shaft 16, the stopper 19d and the groove 19e may be eliminated and instead a projection, not shown, provided in place of the stopper 19d adapted to be engaged by a Z-shaped stopper, now shown, formed on the pawl 20c of the stopper plate 20 or the ear piece 20b.

The present invention constructed as mentioned above has the following advantages:

Since it is not necessary to provide apertures for the variable stopper on a cap, a sealed type switch can be obtained. Consequently, the configuration can prevent sulfide gas or dust from intruding into the interior of the switch and at the same time, a normal washing device can be used to wash out flux produced in the welding of terminals and thereby prevent the intrusion of washing liquid into the interior of the switch from occuring.

In a conventional rotary switch having a mounting screw, because the stopper plate is provided within the cap as shown in FIG. 1, the ear piece of the stopper must be seen through the apertures of the cap from the outside of the switch to know where the ear piece of the stopper is located, which is very difficult.

However, the stopper plate is disposed on the cap, where the location of the movable ear piece of the stopper plate can be recognized at a glance, and therefore the setting of the stopper by the variable stopper is easily made thereby avoiding error in setting of the stopper.

Furthermore, in case of a conventional rotary switch having no bushings or switch mounting screws, it is impossible to change the position of the stopper from the outside of the switch. Consequently, several kinds of switches of exclusive use such as three-contact switches, four-contact switches or six-contact switches, must be prepared in assembling switches. However, according to the present invention, even for a rotary switch having no bushings, only one kind of switch may be prepared and can be easily changed to have a specific number of contacts, if necessary.

Furthermore, as a result of the figures indicating the number of contacts being engraved on the upper surface of the cap, and the window being provided on the variable or movable stopper through which one can selectively set out these figures, the setting of the stopper is easily made and at the same time the number of contacts of the switch can be recognized at a glance by the figure located on the window.

In the case where the switch cap is formed to be cylindrical and the variable stopper is formed to be of a circular cap, the variable stopper is fitted onto and fixed to the cap in any desired position, and therefore the setting of the stopper is very easily made.

Although the present invention has been described with reference to certain preferred embodiments thereof, the embodiments are intended to be merely illustrative but in no way restrictive. Hence, various changes and modifications could be made by those skilled in the art without departing from the scope of the present invention.