Structure of sliding block electrical switch

An electrical switch includes a base, a sliding block, two short circuit metal pieces, contact metal pieces, and a cover. The base has a rectangular top slot, which receives the sliding block, and an elongate guide groove in the middle of the rectangular top slot along the length, which guides a bottom rail on the sliding block. Each short circuit metal piece has a protruded portion on a contact surface thereof engaged into a locating groove on a stop wall at either long side of the base for positioning.

BACKGROUND OF THE INVENTION 
The present invention relates to switching devices, and more particularly 
to an improved structure of sliding block electrical switch which 
eliminates the drawbacks of the sliding block electrical switch of U.S. 
Pat. No. 5,153,401, which is also an invention of the present inventor. 
The sliding block electrical switch according to U.S. Pat. No. 5,153,401, 
as shown in FIG. 1, which comprises a base 1, which has a rectangular slot 
12, depressions 13 located by each of two long sides of the rectangular 
slot 12 and respectively separated by walls 131, and holes 16, contact 
metal pieces 15 respectively lodged in the depressions 13, a sliding block 
2, which has a protruded portion 21 and a clamping block 22, two short 
circuit metal pieces 23 received in the rectangular slot 12 and 
respectively retained between the protruded portion 21 and the clamping 
block 22 of the sliding block 2 and moved by the sliding block 2 to make 
contact with the contact metal pieces 15 adjacent to each other, and a 
cover 3, which has hooks 31;32 respectively hooked in holes 16 on the base 
1. This structure of sliding block electrical switch is easy to assemble 
and disassemble manually without the use of any tools or fastening 
elements. As shown in FIG. 2, the sliding block 2 is capable of moving in 
the rectangular slot 12 so as to trigger the short circuit metal pieces 23 
to make contact with the contact metal pieces 15 located at different 
positions in order to carry out the function of circuit switching. In 
order to let the sliding block 2 be moved in the rectangular slot 12, the 
width of the sliding block 2 must be narrower than the width of the 
rectangular slot 12. This limitation affects the stability of the sliding 
of the sliding block 2 in the rectangular slot 12. Because there is no 
positioning means to hold the sliding block 2 in the rectangular slot 12 
and the contact between the short circuit metal pieces 23 and the contact 
metal pieces 15 is a contact between plains and circular surfaces, a 
contact error may occur easily. 
SUMMARY OF THE INVENTION 
The present invention eliminates the drawbacks of the sliding block 
electrical switch of U.S. Pat. No. 5,153,401. It is therefore the 
principal object of the present invention to provide an improved structure 
of sliding block electrical switch which allows the switching control 
sliding block thereof to be stably moved in the rectangular slot of the 
base thereof without deviating from the course. According to the preferred 
embodiment of the present invention, the sliding block electrical switch 
comprises a base having at the central portion of a top surface thereof a 
rectangular slot, an elongate guide groove disposed in the middle of the 
rectangular slot along the length, three depressions located by each of 
two long sides of the rectangular slot, each two adjacent depressions 
being separated by a respective partition wall, each partition wall having 
one shorter side perpendicularly connected to a respective stop wall in 
the middle and an opposite shorter side connected to an outer wall at 
right angles, each stop wall being located by one long side of the 
rectangular slot and having a locating groove vertically disposed on one 
side thereof adjacent to the rectangular slot; a sliding block in a 
rectangular shape disposed in the rectangular slot, the length of the 
sliding block being approximately equal to the combined length of two 
depressions, the sliding block comprising a bottom rail slidably fitted 
into the guide groove in the rectangular slot, two recesses bilaterally 
disposed at a bottom surface thereof, two clamping blocks bilaterally 
disposed at two long sides thereof and respectively spaced from either 
recess by a gap; two short circuit metal pieces respectively fastened to 
the sliding block at two opposite sides, each short circuit comprising a 
straight contact surface having two opposite ends bent inwards and 
inserted into the respective recess on the sliding block and hooked on the 
respective clamping block, the straight contact surface of each short 
circuit metal piece having a protruded portion engaged into the locating 
groove on either stop wall; contact metal pieces lodged in the depressions 
and equal in number and substantially in height to the depressions, the 
contact metal pieces each being of triangular construction, said contact 
metal pieces each comprising a support portion stopped between two 
adjacent stop walls, a contact surface projected from the support portion 
toward the rectangular slot for the contact of either short circuit metal 
piece, and a clamping portion for fastening a respective electrical wire; 
and a cover covered on said base at the top to hold the sliding block in 
the rectangular slot, the cover having a rectangular opening disposed in 
the middle corresponding to the rectangular slot.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to FIGS. 3 and 4, the sliding block electrical switch in 
accordance with the preferred embodiment of the present invention is 
generally comprised of a base 3, a sliding block 4, and a cover 7. The 
base 3 comprises at the central portion of a top surface thereof a 
rectangular slot 31. An elongate guide groove 32 is disposed in the middle 
of the rectangular slot 31 along the length. Located by each of two long 
sides of the rectangular slot 31 are three depressions 33. Two adjacent 
depressions 33 are partitioned by means of a wall 34. The wall 34 has one 
shorter side perpendicularly connected to a stop wall 35 in the middle and 
an opposite shorter side connected to an outer wall 37 at right angles. 
The stop wall 35 is located by one long side of the rectangular slot 31. A 
locating groove 36 is made on one side of the stop wall 35 adjacent to the 
rectangular slot 31. The depression 33 communicates with the rectangular 
slot 31. An insertion slot 38 is disposed at an outer side of the 
depression 33. Further, the base 3 comprises at both sides thereof a slot 
39, which is similar to the depression 33 and is not connected with the 
rectangular slot 31. An insertion slot 39A is disposed at an outer side of 
the slot 39. Lodged in the depression 33 is a contact metal piece 5, which 
is equal in height to the depression 33 and is of a triangular 
construction arranged in such a manner that it obstructs the common 
passage shared by both rectangular slot 31 and depression 33. The contact 
metal piece 5 comprises a support portion 51 stopped between two adjacent 
stop walls 35, a contact surface 52 projected from the support portion 51 
toward the rectangular slot 31 for the contact of the short circuit metal 
pieces 6 moved by the sliding block 4, and a clamping portion 53. 
The sliding block 4 is made to slide in the rectangular slot 31. The length 
of the sliding block 4 is approximately equal to the combined length of 
two depressions 33. The sliding block 4 comprises a protruded block 41 
disposed at the upper edge of the top surface thereof, and made for use in 
moving the sliding block 4 by the user, an elongate bottom rail 42 
disposed at the bottom in a longitudinal direction and made to slide in 
the guide groove 32 on the base 3 for guiding the sliding of the sliding 
block 4 in the rectangular slot 31. A recess 43 is made on both long sides 
of the sliding block 4. A clamping block 44 is disposed by the outer side 
of the long side of the sliding block 4 and spaced from the recess 43 by a 
clearance. 
Two short circuit metal pieces 6 are fastened to the sliding block 4 and 
moved by it to make contact with the contact metal pieces 5 adjacent to 
each other. The short circuit metal piece 6 comprises a straight contact 
surface 61 having two opposite ends bent inwards and inserted into the 
recess 43 and hooked on the clamping block 44. A protruded portion 62 is 
made on the straight contact surface 61 in the center and fitted into the 
locating groove 36. 
The cover 7 covers on the base 3 to hold the sliding block 4 to the base 3. 
Hooks 72 are made respectively at the bottom and the top surfaces of the 
cover 7 and inserted into holes 3A on the base 3, and therefore the cover 
7 is fastened to the base 3. A rectangular opening 71 is disposed in the 
middle of the cover 7 corresponding to the rectangular slot 31 on the base 
3 through which the protruded block 41 projects over the cover 7 for 
moving by the user. 
Referring to FIGS. 5 and 6, when assembled, the sliding block 4 is received 
in the rectangular slot 31 with the bottom rail 42 slidably fitted into 
the elongate guide groove 32. When moved, the bottom rail 42 is guided by 
the elongate guide 32, and therefore, the sliding block 4 does not deviate 
from the course. As the sliding block 4 is moved from one contact point to 
another in the rectangular slot 31, the protruded portion 62 on the 
straight contact surface 61 of either short circuit metal piece 6 
respectively engages into the locating groove 36 on the respective stop 
wall 35 adjacent to each other, and therefore the contact surface 61 of 
either short circuit metal piece 6 is firmly maintained in contact with 
the contact surface 52 of the respective contact metal piece 5 adjacent to 
each other. 
Further, an electrical cable can be conveniently fastened to either contact 
metal piece 5 by by inserting the conductor of the electrical cable in 
between the clamping portion and the support portion 51. 
While only one embodiment of the present invention has been shown and 
described, it will be understood that various modifications and changes 
could be made without departing from the spirit and scope of the 
invention.