Electricity: electrothermally or thermally actuated switches – Electrothermally actuated switches – With bimetallic elements
Reexamination Certificate
2001-07-17
2003-04-22
Vortman, Anatoly (Department: 2835)
Electricity: electrothermally or thermally actuated switches
Electrothermally actuated switches
With bimetallic elements
C337S061000, C337S060000, C337S059000, C337S037000, C200S277100, C200S277200, C200S332000, C200S341000
Reexamination Certificate
active
06552644
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to electric switches and, more particularly, to a safety press-button switch, which uses a linkage to control on/off switching of a bimetal plate, enabling the bimetal plate to automatically trip off upon an overload.
A variety of power switches are known for controlling on/off of power supply. Earlier power switches are seesaw switches, having ON/OFF function only. A seesaw switch does not trip off automatically upon an overload.
FIGS. 1A and 1B
show a seesaw switch according to the prior art. This structure of seesaw switch
1
comprises a cap-like switching lever
11
balanced on a support at its center and controlled to move a switching metal contact plate
12
between ON position and OFF position. The switching metal contact plate
12
automatically trips off upon an overload.
FIGS. 2A and 2B
show a press-button type safety switch according to the prior art. This structure of safety switch comprises a housing
21
, a press-button
22
supported on a spring
27
, an actuating block
23
connected to the press-button
22
, the actuating block
23
having a heart-shaped locating groove
24
at the right side, a bimetal plate
26
fastened to a right-sided power terminal
25
, the bimetal plate
26
having a top pin
27
adapted to engage the locating groove
24
. When pressing the press-button
22
, the locating groove
24
of the actuating block
23
is forced into engagement with the top pin
261
of the bimetal plate
26
to close the circuit. In case of heat is produced and transmitted from the right-sided terminal
25
to the bimetal plate
26
due to an overload, the bimetal plate
26
is deformed to disengage the top pin
261
from the locating groove
24
of the actuating block
23
, and the spring
27
immediately forces the press-button
22
upwards to OFF position. However, this structure of safety switch is still not satisfactory in function. When the metal contact holder
29
is lowered with the press-button
22
to force its contacts
291
;
292
into contact with the contact
281
of the middle terminal
28
and the contact
251
of the right-sided terminal
25
, electric current is not connected to the bimetal plate
26
, and the bimetal plate
26
is not directly sensitive to the electric current. When a short-circuit high temperature is produced, it is transmitted from the metal contact holder
29
to the right-sided terminal
25
, and then transmitted from the right-sided terminal
25
to the bimetal plate
26
. Because the transmission of heat from the metal contact holder to the bimetal plate
26
takes much time, the bimetal plate
26
does not trip off immediately upon an overload. Further, the four-contact (
281
;
291
;
292
;
251
) design is complicated. There are also known other similar safety press-button switches that automatically trip off upon an overload. However, these conventional safety press-button switches are commonly complicated, and expensive. In case one element fails, the actuating metal contact plate cannot trip off automatically upon an overload.
SUMMARY OF THE INVENTION
The present invention has been accomplished to provide a safety press-button switch, which eliminates the aforesaid drawbacks. It is one object of the present invention to provide a safety press-button switch, which uses a reversible linkage to control on/off status of a bimetal plate, enabling the bimetal plate to trip off automatically upon an overload. It is another object of the present invention to provide a linkage for a safety press-button switch, which fits any of a variety of on/off switching metal contact plates. It is still another object of the present invention to provide a safety press-button switch is easy to install and, durable in use. According to one aspect of the present invention, the safety press-button switch comprises a linkage formed of a lever and a switching rod pivoted together, and a press-button cap having a push rod and a hook arm respectively aimed at the switching rod and a positioning rod of the lever and adapted to force the lever to shift an actuating metal contact plate from OFF position to ON position and to hold the lever in position after the actuating metal contact plate switched on, the positioning rod of the lever being forced away from the hook arm by the deformation force of the bimetal plate for enabling the actuating metal contact plate to trip off automatically upon an overload. According to another aspect of the present invention, the actuating metal contact plate is a bimetal plate.
REFERENCES:
patent: 2476648 (1949-07-01), Zeller
patent: 2516670 (1950-07-01), Bourne
patent: 3469222 (1969-09-01), Brackett, Sr.
patent: 3706057 (1972-12-01), Ellenberger
patent: 4068203 (1978-01-01), Unger
patent: 4682138 (1987-07-01), Sell
patent: 4780697 (1988-10-01), Cobb et al.
patent: 4812799 (1989-03-01), Cobb et al.
patent: 5079530 (1992-01-01), Tsuchiyama
patent: 5264817 (1993-11-01), Sorenson
patent: 5453725 (1995-09-01), You et al.
patent: 5889457 (1999-03-01), Hsu et al.
patent: 5898355 (1999-04-01), Yu
patent: 5936505 (1999-08-01), Yu
patent: 6121868 (2000-09-01), Chiang
patent: 6445273 (2002-09-01), Yu
patent: 6448880 (2002-09-01), Yu
patent: 6456185 (2002-09-01), Yu
patent: 6480079 (2002-11-01), Bentley et al.
patent: 6483416 (2002-11-01), Yu
patent: 2704008 (1977-08-01), None
patent: 285340 (1988-10-01), None
Rosenberg , Klein & Lee
Vortman Anatoly
LandOfFree
Safety press-button switch does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Safety press-button switch, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Safety press-button switch will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3025233