Electricity: circuit makers and breakers – Electric switch details – Actuators
Reexamination Certificate
2002-09-23
2004-01-06
Enad, Elvin (Department: 2832)
Electricity: circuit makers and breakers
Electric switch details
Actuators
C200S334000, C337S066000
Reexamination Certificate
active
06674034
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to electric switches and, more particularly, to a press button type safety switch, which automatically trips off upon an overcurrent and, which enables the user to view the on/off status of the safety switch from its outer appearance.
2. Description of the Related Art
A variety of electric switches, including seesaw switches and press button switches are known. In early days, a press button switch has only ON→OFF function, and cannot trip off automatically upon an overcurrent. In order to eliminate this problem, a variety of safety switches are developed. Regular safety switches are commonly of seesaw switching type.
FIGS. 1A and 1B
show a seesaw switch
1
invented by the present inventor. This design of seesaw switch
1
uses a plank
11
to move a conducting plate
12
between on/off positions. When an overcurrent occurred, the conducting plate
12
automatically trips off the contact
121
.
FIGS.
2
A~
2
E show an overload protective press button switch according to the prior art. This structure of overload protective press button switch comprises a housing
31
, the housing
31
having a top opening
311
and two open chambers
313
and
314
separated by a partition plate
312
, a metal contact unit
33
installed in the housing
31
, a switching mechanism
35
, a press button assembly
32
, and a linkage
34
. The linkage
34
comprises a spring member
342
supported on the partition plate
312
, a press member
341
mounted on the spring member
342
, and a swivel holder
344
pivoted to the housing
31
. The swivel holder
344
has a guide hole
343
, which receives the press member
341
, and a positioning portion
345
connected to the switching mechanism
35
.
When pressed the press button assembly
32
, the press member
341
is forced downwards to compress the spring member
342
and to bias the swivel holder
344
, thereby causing the switching mechanism
35
to switch on the metal contact unit
33
. When switched on, the spring member
342
pushes the press member
341
back to the initial position. The upper part I of this overload protective press button switch is similar to the design of the aforesaid prior art press button switch. The lower part II of this overload protective press button switch is similar to the design of the aforesaid prior art seesaw switch. This design is similar to Yu's Taiwan utility model no. 83365 (equivalent to U.S. Pat. No. 5,262,748) with the exception of the additional press button assembly
32
. The swivel holder
344
is equivalent to Yu's seesaw plank. This structure of overload protective press button switch is complicated, resulting in high manufacturing cost and inconvenience of use. When the push button assembly
32
pressed to the position shown in
FIG. 2C
, and the swivel holder
344
is biased leftwards, the metal contact unit
33
is switched on. When the user released the hand from the push button assembly
32
, the push button assembly
32
is moved to the position shown in FIG.
2
D. Viewing from the outside, it shows no difference between the position of FIG.
2
B and the opposition of
FIG. 2D
, therefore the user cannot know on or off status of the switch when viewed from the outside. For on/off indication, a complicated indicator circuit must be installed.
SUMMARY OF THE INVENTION
The present invention has been accomplished under the circumstances in view. It is one object of the present invention to provide a press button type overload protective safety switch, which enables the user to know “on or off status of the switch from the outer appearance of the switch. It is another object of the present invention to provide a press button type overload protective safety switch, which automatically trips off upon an overcurrent. It is still another object of the present invention to provide a press button type safety switch, which is simple and inexpensive to manufacture. To achieve these and other objects of the present invention, the press button type safety switch comprises a housing, the housing having a holding chamber separated by a horizontal partition wall thereof into an upper open chamber and a lower receiving chamber, and a through hole through the horizontal partition wall in communication between the upper open chamber and the lower receiving chamber; a plurality of terminals installed in the lower receiving chamber of the housing and electrically connected to external power supply; a switching mechanism installed in the lower receiving chamber of the housing and controlled to switch on/off the circuit of the terminals; a linkage adapted to switch on/off the switching mechanism, the linkage comprising spring members supported in the upper open chamber of the housing, a press button assembly supported on the spring members in the upper open chamber of the housing, and an actuating mechanism mounted in the through hole of the housing and connected between the press button assembly and the switching mechanism and controlled by the press button assembly to switch on/off the switching mechanism, the actuating mechanism comprising a conical spring mounted on the partition wall, a press member supported on the conical spring and partially inserted into the through hole of the housing, and a seesaw plank pivoted to the housing, the seesaw plank having a guide groove, which receives the press member for enabling the seesaw plank to be biased by the press member to switch on/off the switching mechanism, and a positioning portion disposed at one end thereof and connected to the switching mechanism; wherein: the linkage comprises at least one locating rod; the seesaw plank comprises at least one top hook adapted to hook on the at least one locating rod of the press button assembly to hold the press button assembly in a position where the spring members in the upper open chamber of the housing maintained compressed by the press button assembly when the press button assembly pressed by the user to switch on the switching mechanism.
REFERENCES:
patent: 3165611 (1965-01-01), Hagberg
patent: 5508485 (1996-04-01), Nishikawa
patent: 5521347 (1996-05-01), Imaeda et al.
patent: 6069545 (2000-05-01), Van Zeeland
patent: 6335500 (2002-01-01), Chi et al.
patent: 6462292 (2002-10-01), Wang
patent: 6469610 (2002-10-01), Chen
patent: 6552643 (2003-04-01), Chen
patent: 6552644 (2003-04-01), Yu
Enad Elvin
Klaus Lisa N
Rosenberg , Klein & Lee
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