Electricity: circuit makers and breakers – Multiple circuit control – Pivoted contact
Reexamination Certificate
2002-03-13
2003-05-06
Enad, Elvin (Department: 2832)
Electricity: circuit makers and breakers
Multiple circuit control
Pivoted contact
C200S558000
Reexamination Certificate
active
06559393
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a switch having a seesaw type movable contact blade.
FIGS. 1A and 1B
show an example of the prior art switch having a movable contact blade configured to be moved through a seesaw motion in a vertical cross-sectional view taken parallel to the major side of the switch and in a vertical cross-sectional view taken parallel to the minor side, respectively. A metallic support plate
60
is passed vertically through and secured to the bottom panel
12
of the box-like case
10
made of electrically insulating plastic material generally in the center thereof. The support plate
60
has upstanding guide projections
61
1
and
61
2
extending from the top end edge thereof at the opposite sides between which a movable contact blade
50
is swingably mounted on the top end edge. The top end edge of the support plate
60
serves as a fulcrum for the swinging movement of the movable contact blade
50
while the lower end portion of the support plate
60
extending outside of the bottom panel
12
defines a movable contact blade terminal
6
T which is electrically connected by contact with the movable contact blade
50
.
Attached to the undersurface of the movable contact blade
50
adjacent one end thereof is a movable contact
50
C. An inverted L-shaped fixed contact blade
70
is disposed on the bottom panel
12
of the case such that the upper horizontal leg
72
of the fixed contact blade
70
is in opposition to the undersurface of the movable contact blade
50
while the vertical leg of the blade extends as a fixed contact blade terminal
7
T downwardly out through the bottom panel
12
. The upper horizontal leg
72
of the fixed contact blade
70
has a fixed contact
70
C attached thereto in opposition to the movable contact
50
C.
A tumbler type actuator
40
is disposed over the movable contact blade
50
so as to close the top opening
10
A of the case
10
. The actuator
40
has pivot studs
47
extending from the opposite side walls thereof which are received in bearing holes
16
formed in the opposite side walls
11
of the case
10
. The actuator
40
further has an integral columnar portion
42
extending downwardly from the undersurface of the tumbler body in the center thereof The columnar portion
42
has a spring housing bore
42
A formed therein in which a coil spring
45
is accommodated. A plunger
43
has its upper end portion inserted in the housing bore
42
A and engaged by the coil spring
45
to be downwardly biased so that the lower end of the plunger
43
is always urged to be in sliding engagement with the upper surface of the movable contact blade
50
by the biasing force of the coil spring
45
.
In
FIG. 1A
, the tumbler type actuator
40
is illustrated as being depressed in its switch-off position in which the lower end of the plunger
43
presses down on the upper surface of the movable contact blade
50
on the side of the support plate
60
opposite from the movable contact
50
C to stably hold the movable contact
50
C opened from the fixed contact
70
C so that there is no electrical continuity between the terminals
6
T and
7
T. When the actuator
40
is pressed toward its switch-on position, it is turned clockwise as viewed in the drawing about the studs
47
so that the lower end of the plunger
43
is slidingly moved up the upper surface of the movable contact blade
50
toward and beyond the upper end of the support plate
60
against the spring force of the coil spring
45
to go over to the portion of the upper surface of the blade on the side of the movable contact
50
C whereupon the movable contact blade
50
is swung to bring the movable contact
50
C into abutment with the fixed contact
70
C to thereby stably hold the switch in the on-position. As a result, the terminals
6
T and
7
T are kept in electrical continuity.
While in this prior art switch the contact is established between the undersurface of the movable contact blade
50
and the straight top end edge of the support plate
60
, a complete line contact is not realized but there are actually a plurality of point contacts. Further, the positions of the contact points will change with the swinging movement of the movable contact blade
50
and may also move due to a mechanical shock or vibration, so that the electrical stability of the switch has not been satisfactory. In addition, since substantially all of the voltage across the terminals
6
T and
7
T is applied between the contacts
50
C and
70
C, the switch had the disadvantage that it was attended with an expedited wearing out of the contacts
50
C and
70
C due to discharge sparks during the making and breaking of the contacts.
SUMMARY OF THE INVENTION
It is an object of this invention is to provide a switch with a seesaw type movable contact blade which has a high withstandingness to voltage and which ensures a reduced wearing out of the contacts due to sparks occurring during the switching of the switch and is electrically stable.
The switch according to this invention comprises:
a box-like case having a bottom panel of an insulator and an opening in the top thereof;
a support plate secured to and extending vertically upwardly from the bottom panel and terminating in a top end edge defining a central convex portion which is the highest in the center thereof;
a movable contact blade formed of a generally quadrilateral metallic plate supported on the top end edge of the support plate for rotating movement about the top end edge defining a pivot axis and having attached thereon two movable contacts spaced apart in the direction of the pivot axis adjacent one end of the blade;
two fixed contact blades affixed at one end to the bottom panel and each having a fixed contact attached thereto adjacent the one end in opposition to a corresponding one of the movable contacts with the other end portion of each fixed contact blade extending out through the bottom panel to define a terminal;
a driving means having two sliding protrusions pressing on the upper surface of the movable contact blade and slidable in a direction perpendicular to the direction of the pivot axis;
coil spring means having a biasing force to urge the driving means toward the movable contact blade;
a rotatable actuator having a spring housing bore formed in the lower end portion in which the coil spring means is accommodated and including a columnar portion adapted to hold the driving means retractably in abutment with the movable contact blade as the driving means is slidingly moved on the movable contact blade; and
a cover means mounted so as to close the top opening of the case and having an aperture formed therethrough in the center thereof for rotatably holding the actuator which is inserted through the aperture;
whereby rotation of the actuator selectively establishes and break electrical continuity between the terminals between the two fixed contacts.
REFERENCES:
patent: 4389552 (1983-06-01), Sorenson
patent: 4814554 (1989-03-01), Magiera
patent: 5041706 (1991-08-01), Osika et al.
patent: 6175090 (2001-01-01), Blossfeld
Enad Elvin
Klaus Lisa N.
Lathrop, Esq. David N.
Sagami Electric Company
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