Abstract:
The casisng of an electrical switch is made waterproof by a sliding seal interposed between a switch operating member located outside the casing and the peripheral edge of an opening into the casing. The operating member and seal engagingly slide on the peripheral edge of the casing and the operating member has a part which projects into the casing through a hole in the seal.

Description:
This is a continuation application from application Ser. No. 794,243 filed Nov. 1, 1985 now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to a waterproof structure for a switch, and more particularly to a waterproof structure of an automobile switch for a power window or the like. 
     Conventionally, this type of switch is constructed by combining an operating member with a lever which projects from an opening at the top of a casing to form a seesaw type switch. The waterproof structure of such a switch is formed by covering it with an elastic material such as rubber to seal the opening in the casing, or by entirely covering the switch with a waterproof sheet. 
     However, this conventional waterproof structure is difficult to install, and high in cost. Further, the operating force for operating the switch is undesirably large by this technique because the elastic material must be plied to operate the switch. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to eliminate the above-mentioned problems in the prior art. 
     It is another object of the present invention to provide a waterproof structure for a switch is simple in structure, easy to install, and low in cost. 
     It is further object of the present invention to provide a waterproof structure for a switch which may be operated with a light operating force and has a good operational feel. 
     According to the present invention, the waterproof structure of the switch comprises an elastic waterproof material slidably seated on the opening edge of a casing through which an operating member projects. The waterproof material is formed with a through-hole at a substantially central portion thereof, the through-hole being dimensioned to fit tightly around part of the operating member which projects into the casing. 
    
    
     Other objects and advantages of the invention will become apparent from the following description and accompanying drawing. 
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 is an exploded view in perspective of a switch in a preferred embodiment of the invention; 
     FIG. 2 is an elevational view in section of an essential part of the switch; 
     FIG. 3 is a side view in section of the essential part of the switch; and 
     FIG. 4 is an elevational view in section similar to FIG. 2, with an operating member inclined. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIGS. 1 to 4, reference numeral 1 designates an upper case provided with a semicylindrical projected portion 2 on an upper surface thereof. The projected portion 2 is provided with an opening 3 on an upper surface thereof. 
     Reference numeral 4 designates a lever having a head portion projecting from the opening 3 of the upper case 1. The lever 4 is formed with a through-hole 4a at a substantially central portion thereof, into which a support shaft 5 is inserted, and the lever 4 is pivotally supported by the support shaft 5. That is to say, the lever 4 is retained in the upper case 1 by engaging one end of the support shaft 5 into a stopper hole 1a provided at a side surface of the upper case 1. The semicylindrical projected portion 2 preferably has a radius of curvature which matches the arc described by the lever 4 as it pivots about the shaft 5. 
     FIG. 1 illustrates assembly of the entire switch. The lever 4 is provided with a pair of drive member receiving portions 4b at a lower end thereof, and each of drive members 7 downwardly biased by coil springs 6 each of which is received in each of the drive member receiving portions 4b. 
     Reference numeral 8 designates a lower case adapted to be engaged with the upper case 1 to form a switch casing. Fixed to the lower case 8 are terminals 10 and 11 which are provided with fixed contact points 9. Central terminals 12 having conductor plate supporting portions 12a which are bent into an L-shape are fixed by caulking to a bottom surface of the lower case and they communicate out of the case by means of terminals 13. 
     Reference numerals 14 designate conductor plates supported by the conductor plate supporting portions 12a of the central terminals 12 and adapted to be pivoted by the drive members 7. The conductor plates 14 are formed in a V-shape, and are provided with contact points 15 at both ends of each. 
     The head portion of the lever 4 projecting from the opening 3 of the upper case 1 is combined with an operating member 16 for forming a seesaw type switch. Slidably seated on the peripheral edge 3a of the opening 3 of the upper case 1 is a sheet-like waterproof material 17 formed of elastic materials such as polyester having an outer peripheral edge of a size larger than an outside dimension of the peripheral edge 3a. The waterproof material 17 is interposed between the peripheral edge 3a and an abutting bottom surface 16a of the operating member 16 arcuately formed so as to be fitted to the peripheral edge 3a. 
     Combination of the head portion of the lever 4 with the operating member 16 is effected by engaging a projection 4c formed at the head portion of the lever 4 with a recess of a receptacle portion 16b provided on a lower surface of the operating member 16. The waterproof material 17 is formed with a through-hole 17a at a substantially central portion thereof which through-hole 17a has a peripheral edge tightly contacting with an outer peripheral surface of the receptacle portion 16b of the operating member 16. Further, a grease such as silicone having viscosity is applied on the peripheral edge 3a of the upper case 1, to enhance sealing and provide lubrication. 
     According to the waterproof structure in the present invention, when the operating member 16 is operated into an inclined position as shown in FIG. 4, the waterproof material 17 slides in association with the motion of the operating member 16. Accordingly, the waterproof structure does not increase the operational torque or change the operational feeling. 
     Further, the waterproof sheet 17 may be easily installed onto the operating member 16 by disposing the waterproof material 17 on the head portion of the lever 4 and pressfitting the receptacle portion 16b of the operating member 16 to the head portion of the lever 4. 
     Furthermore, since the size of the waterproof material 17 is larger than the outside dimension of the opening edge 3a of the upper case 1, it does not allow formation of a clearance when the operating member 16 is inclined and the waterproof material 17 slides on the peripheral edge 3a. 
     Having thus described the preferred embodiment of the invention, it should be understood that numerous structural modifications and adaptations may be restored to without departing from the spirit of the invention.