Abstract:
A manual switch for portable electric tools having minimum parts and ease of assembly. The switch is of the trigger actuated type and includes a single-piece molded housing, single-piece stationary contact-terminals, single-piece movable contact-terminals, and a snap-in assembled trigger. The double-pole stationary and movable contact-terminals are placed in slots in the single-piece molded housing member, this molded member is folded to form a switch housing, the return spring is inserted into the groove in the trigger, the cam end of the trigger along with the spring is inserted into the housing, the housing is closed by the rivet, and the trigger is snap-in assembled fully into its hole in the housing to complete assembly of the switch. The switch is connected to a tool motor circuit by pressing electrical conductors into holes in the bottom of the housing. These connections can be released by inserting a release tool alongside the lead, or by depressing built-in release buttons in an alternate design.

Description:
BACKGROUND OF THE INVENTION 
     Electric switches for portable electric tools and other uses have been known heretofore. However, such known switches have been rather complex in structure including a large number of parts making them expensive to manufacture and assemble. Consequently, it has become desirable to provide switches of this type that are simple in structure having the minimum number of parts in order to reduce the cost not only of fabrication of the parts but also the cost of assembly of the switch. 
     While such prior known switches have been useful for their intended purposes, this invention relates to improvements thereover. 
     SUMMARY OF THE INVENTION 
     An object of the invention is to provide an improved electric switch. 
     A more specific object of the invention is to provide an electric switch having minimum parts. 
     Another specific object of the invention is to provide an electric switch that is simple and economical to assemble. 
     Another specific object of the invention is to provide a switch of the aforementioned type that is completely insulated. 
     Another specific object of the invention is to provide a one-piece foldable housing for a double-pole electric switch. 
     Another specific object of the invention is to provide a snap-in assembled actuator for an electric switch. 
     Another specific object of the invention is to provide an electric switch with lead disconnect means that does not require additional tools. 
     Other objects and advantages of the invention will hereinafter appear. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an enlarged isometric view of a trigger switch for portable tools showing its external configuration; 
     FIG. 2 is an exploded isometric view of parts of the switch of FIG. 1; 
     FIG. 3 is a longitudinal cross-sectional view through one of the poles of the double-pole switch of FIGS. 1 and 2 showing a first version of the single-piece contact-terminal structure; 
     FIG. 4 is a cross-sectional view of the trigger and a part of the housing of the switch of FIGS. 1-3 showing the snap-in assembly structure of the trigger at the start of assembly thereof into the housing; 
     FIG. 5 is a cross-sectional view like FIG. 4 showing the snap-in assembly of the trigger at the completion of trigger assembly; 
     FIG. 6 is a cross-sectional view like FIG. 3 but showing a second version of the single-piece contact-terminal structure as well as the integrally-molded bias element on the housing; 
     FIG. 7 is a lateral cross-sectional view taken along line 7--7 of FIG. 6 showing the double-pole contact compartments; 
     FIG. 8 is a bottom view of the movable contact-terminal of the switch of FIGS. 6 and 7. 
     FIG. 9 is an unfolded view of the housing showing the internal configuration thereof; 
     FIG. 10 is a lower side view of the unfolded housing of FIG. 9; and 
     FIG. 11 is a cross-sectional view taken along line 11--11 of FIG. 9 showing the integrally molded bias element on the housing. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, there is shown an electric switch of the in-line trigger actuated type. As shown therein, the switch comprises a housing 2 having a lower portion 2a enclosing the switch contact-terminals and including two pairs of holes 4 and 6 in the bottom through which conductors are inserted to connect the contact-terminals to an electric circuit. This housing also comprises a relatively narrower upper portion 2b for retaining the slidable stem 8a of a switch actuating trigger 8 and its return spring 10. The housing is held together by a rivet 12 although other means may be used such as sonic welding or the like. This trigger also has an enlarged manually engageable portion 8b which may be depressed by the forefinger of the user when the switch is mounted in the handle of a portable electric tool such as a drill, saw, or the like. While an in-line movable trigger has been shown, it will be apparent that other types of operators could be used, such as a pivoted trigger, for example, so long as the portion of the actuator within the housing is linearly movable. 
     The switch housing is most clearly shown in FIGS. 2, 9 and 10. As shown therein, the housing is molded of plastic material as a single-piece, elongated generally rectangular member having the configurations hereinafter described. 
     At the center of this elongated member there is a rectangular planar portion 14 extending laterally across and having a bias element or resilient finger 16 integrally molded near one edge of this planar portion. This bias finger has a rounded ridge 16a, shown in enlarged section in FIG. 11, extending inwardly of the housing so that it resiliently biases slidable stem 8a of the trigger downwardly toward the contacts as hereinafter more fully described. While only one bias finger 16 is shown, it will be apparent that another similar bias finger could be provided near the other edge of planar portion 14 so as to apply a balanced downward bias onto the trigger. 
     Rectangular planar portion 14 is defined by two narrow thin portions 18, one on each side thereof, extending laterally across member 2 so as to provide hinges affording right-angle bends to form the upper two corners of the housing as shown in FIG. 7. 
     At opposite sides of these hinge portions, there are two rectangular planar portions 20 and 22 forming the side walls of upper portion 2b of the housing within which the stem of the trigger slides. As shown in FIG. 9, at the lower ends of these rectangular planar portions 20 and 22 there are right-angled walls 20a and 22a that will partially overlap when the housing is folded to form the rear wall of upper portion 2b of the housing. 
     At opposite sides of planar portions 20 and 22, as shown in FIG. 9, this member 2 deepens to provide the two side walls 24 and 26 of the contact-terminal compartment. At opposite ends of these side walls 24 and 26 there are right-angled walls 24a, 24b and 26a, 26b which will form the opposite end walls of the contact-terminal compartments when the member is folded. As shown in FIG. 10, wall 24b joins with wall 20a whereas wall 26b joins with wall 22a to provide continuous rear end walls on the two folded halves of the housing. As shown in FIG. 10, walls 24a, 26a and 24b, 26b, respectively, partially overlap when the member is folded and are provided with suitable locking means such as two pairs of lugs 24c, 24d on walls 24a, 24b for catching in respective pairs of holes 26c, 26d in walls 26a, 26b when the housing is folded. The outer edges of these right-angled walls 24a, 24b and 26a, 26b are connected by further right-angled walls 28 and 30, respectively, having the pairs of holes 4 and 6 therein shown in FIGS. 1 and 2, these walls forming the bottom of the housing when the member is folded. 
     The upper edges of these connecting walls 28 and 30 have foldable flaps 32 and 34 integrally molded thereto via laterally-disposed thin hinge portions 36 and 38, respectively, as shown in FIG. 10. These hinge portions afford 180 degree folding thereof inwardly to provide a dividing wall separating the two compartments housing the respective poles of the double-pole switch. 
     In addition, single-piece molded member 2 has a pair of generally T-shaped inner walls 24e and 26e integrally molded onto side walls 24 and 26 and connecting walls 28 and 30, respectively, to provide retention means or slots for the stationary and movable contact-terminals. One set of these stationary and movable contact terminals 40 and 42 is shown in FIG. 2, the other set for the other pole of the switch being similar. The specific configuration of these generally T-shaped inner walls will differ slightly for different forms of contact-terminals. For example, the specific configuration of walls 24e and 26e in FIG. 2 is usable with the form of contact-terminals shown in FIG. 3 whereas the specific configuration of such walls in FIG. 9 is slightly different to match the form of contact-terminals shown in FIG. 6. 
     When a rivet or the like is used to hold the housing together after it is folded, suitable holes are provided when the housing member is molded. For this purpose, round holes 24f and 26f extend through side walls 24 and 26 including T-shaped inner walls 24e and 26e, respectively. And oblong holes 32a and 34a extend through flaps 32 and 34, respectively, to align with holes 24f and 26f, respectively, when these flaps are folded in. These holes 32a and 34a are oblong to afford free access of the rivet therethrough and to avoid the requirement of close tolerance molding dies. 
     As shown in FIG. 3, the contact-terminals are each formed from a single piece of metal strip to one end of which the contact element is welded. Stationary contact-terminal 40 has one end bent at a right angle and contact element 40a is welded to the lower surface of this bent end. This strip extends down along the rear end wall of the housing to the bottom thereof at which point it is bent back up in contiguous parallel relationship. The remainder of this strip is bent twice at right angles and is bent a third time at slightly more than a right angle at spaced apart points to form a loop 40b hugging one side of the T-shaped wall within the housing with the end 40c thereof being inclined upwardly to overlie the corresponding hole in the bottom of the housing. End 40c terminates against or very near the bent-back portion of the contact-terminal so that the insulation-stripped end of an electrical wire pushed up from below through the hole will be gripped therebetween for electrical connection and physical retention. 
     The terminal portion of movable contact-terminal 42 is similarly formed to fit the pocket on the other side of the T-shaped wall of the base and its contact element 42a end extends into overlapping relation with contact element 40a for closing and opening with respect thereto. An intermediate portion of movable contact-terminal 42 has a bend at a point spaced from contact element 42a affording a bump 42b for engagement by an integral cam 8c on the trigger to close and open the contacts. 
     The switch may be provided with means for snap-in assembly of the trigger. For this purpose, as shown in FIGS. 4 and 5, the trigger is provided with an integrally-molded resilient finger 8d projecting slightly below the lower surface of slidable portion 8a of the trigger. The cam 8c end portion of the trigger may be inserted into the housing without compressing return spring 10 before the housing is finally closed by rivet 12. This finger 8d has a lower surface inclined toward the rear end of the trigger so that this finger will be cammed into the trigger out of the way when the trigger is pressed into the hole in the housing as shown in FIG. 4. When the trigger has been pushed far enough into the housing, this finger 8d will snap back inwardly of the front wall of the housing to lock the trigger to the housing. In this position, return spring 10 is sufficiently compressed so that whenever the trigger is pressed further in to actuate the switch and then released, this spring will restore the trigger to its fully extended position shown in FIG. 5. 
     While such snap-in finger is not shown in FIGS. 2 and 3, it will be understood that this version of the switch may include it. 
     The version of switch shown in FIGS. 6-8, differs from the version shown in FIGS. 2-3 in the configuration of the contact-terminals. The terminal portions of contact-terminals 44 and 46 in FIG. 6 are bent at a right angle inwardly along the bottom of the housing over the holes therein and are then provided with a near 180 degree re-entrant bend 44a, 46a so that the terminal end inclines substantially as in FIG. 3 against or very near the vertical portion thereof for gripping a stripped conductor pushed up from below through the hole in the housing. In both versions, it will be seen, the stripped wire is gripped between two parts of the terminal portion of the strip for a good electrical connection, rather than being gripped between the end of the terminal and a wall of the insulating housing. 
     In this version of contact-terminal, it will be apparent, a hole 46b must be provided in the right angle bent portion as shown in FIG. 8 overlying the hole in the housing as shown in FIG. 6 to afford insertion of the stripped wire to be connected. 
     To afford ready release of the wires connected to the switch, the switch may be provided with built-in release pins as shown in FIGS. 6 and 7. For this purpose, the terminal portion is provided with a second hole 46c shown in FIG. 8 spaced toward the re-entrant bend from the wire hole 46b. And, of course, a corresponding hole must be provided in the bottom of the housing for each press-in terminal, four in all, or the wire hole must be elongated. Plastic buttons 48 extend through these holes in the housing and terminal and are long enough so that when pushed up they will lift the inclined, gripping portions of the terminals and release the wires which can then be pulled freely out. The upper ends of these release buttons are preferably provided with beveled flanges 48a as shown in FIG. 6 so that they can be snapped into place and will be retained therein. 
     The switch is provided with means for guiding the in-line motion of the trigger. For this purpose, cam 8c on the lower side of the trigger is divided as shown in FIG. 2 providing a groove 8e between the two halves thereof. Also, flaps 32 and 34 are wide enough so that when they are folded in to abut one another and the housing is clamped or secured together by a rivet or sonic welding, the contiguous parallel edges of these flaps form a track as shown in FIG. 7 which enters groove 8e when the trigger is assembled in the housing and this track guides the trigger when it is depressed or pulled in to operate the switch. Also, bias finger 16 shown in FIG. 6 presses the trigger down onto this track to fix and maintain cam 8c in its proper path of travel in order to insure the effective opening and closing of the contacts. 
     The switch contacts are normally open and close when the trigger is depressed. This normally open state of the contacts with the trigger in its fully extended condition is shown in FIGS. 3 and 6. When the trigger is depressed, cam 8c slides on the bump of the movable contact until finally cam 8c passes to the rear of bump 42b in FIG. 3 clear of it. This allows the inherent upward bias in the movable contact leaf spring to raise the same to close the contacts. While the trigger was depressed, return spring 10 was compressed. Now when the trigger is released or the finger force thereon is relaxed, return spring 10 returns the trigger outwardly, causing cam 8c to engage bump 42b to open the contacts. 
     While the apparatus hereinbefore described is effectively adapted to fulfill the objects stated, it is to be understood that the invention is not intended to be confined to the particular preferred embodiments of manual switch for portable tools disclosed, inasmuch as they are susceptible of various modifications without departing from the scope of the appended claims. 
     While a trigger actuated manual switch has been shown, it will be apparent that with the necessary modifications to the single-piece housing molding, the invention could readily be adapted to other forms of actuators such as, for example, toggle lever, pushbutton, rocker button, or the like.