Electricity: electrothermally or thermally actuated switches – Electrothermally actuated switches – With bimetallic elements
Reexamination Certificate
2000-11-20
2002-11-12
Vortman, Anatoly (Department: 2835)
Electricity: electrothermally or thermally actuated switches
Electrothermally actuated switches
With bimetallic elements
C337S059000, C337S037000, C337S066000, C337S070000
Reexamination Certificate
active
06480090
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a universal device for safety switches, and more particularly, to a main body structure applicable to all kinds of safety switches with protection circuit which is formed in a collapsible manner. In case of overload, a conductive strip bounces into a deforming shape for a complete disconnection in order to ensure the electrical safety.
2. Description of the Prior Art
A conventional wall-mounted see-saw switch, as shown in
FIG. 1
, is usually used to control the On/Off of a light and which generally includes a button
11
capable of being positioned in two different positions as an exerted force is applied at one end for establishing a closed or opened circuit via a retaining tab
110
which butts against a plate
12
. However, this see-saw switch must be operated manually such that the closed or opened circuit can be attained once the button is pressed at one end. Unless the button is pressed at one end, otherwise the see-saw switch will remain in a preset position, i.e. opened circuit is remained in opened position; and closed circuit is remained in closed position. This see-saw switch can not be switched from the closed position to an opened position even an overload is encountered. If the supplied power can not be interrupted immediately, the electric conductive wires will become more and more hot, eventually, a risk of getting a fire can be encountered. In light of this, the safety and property of user can not be suitably protected.
U.S. Pat. No. 5,262,748, entitled to “Fuseless Breaking Switch”, hereinafter referred to as '748, has disclosed a subject matter which is intended to solve the defects of the conventional see-saw switch. This fuseless breaking switch comprises a casing
10
having a button
13
pivotally mounted thereof. The bottom of the casing
10
is further provided with three sets of prongs
15
,
16
,
17
. One set of the prongs
17
is disposed with a contact reed
170
having a platinum conductive protrusion
171
thereof. One end of the contact reed
170
is disposed above the corresponding prong
16
and is electrically connectable with the platinum conductive protrusion
160
. The button
13
is further provided with a coupled piece
14
, the other end of which is in turn connected to contact reed
170
. When the button
13
is depressed, the prongs
16
,
17
is electrically connected via the contact reed
170
and the platinum conductive protrusion
171
,
160
. When the current is overloaded, the contact reed
170
will be deformed by being heated. Accordingly, the electrical engagement of the contact reed
170
with said platinum conductive protrusion
31
is disconnected. Consequently, the supplied power is interrupted to ensure the safety and property of user.
Even the disclosure of U.S. Pat. No. 5,262,748 provides an improved breaking switch to solve the problem encountered by a see-saw switch, its defects can still be concluded as follows:
1. When the button
13
is depressed or jammed, or the curved spring blade
24
experiences a fatigue, the conductive protrusion
170
will not be disconnected even in case of an overload. The breaking switch itself will be melt by the increasing heat. The potential risk of getting fire can not be suitably avoided.
2. The operating principle of the breaking switch is based as follows. When the contact reed
170
made of double alloy piece is heated during an overload and the temperature rises till the breaking temperature (normally set between 100-150 degrees Celsius), the resilience will be larger than the curved spring blade
18
such that the breaking switch is actuated to opened circuit. In this case, even the button
21
is depressed to ON position and if the resilience of the contact reed
170
is still larger than the curved spring blade
18
, the engagement of the conductive protrusion
171
will be disconnected as soon as it is contacted. If the button
13
is kept at depressed position, even an engagement is attained between the conductive protrusions
171
,
160
, the contact reed
170
doesn't work and the temperature is still increasing. On the other hand, the platinum conductive protrusions
171
,
160
are contacted with each other by means of the depressing force of the user. If the force exerted thereon is not well distributed, a spark will be caused in contacting owing to load and poor contact. In this case, the platinum conductive protrusions
171
,
160
will be easily oxidized and the service life will then be shortened.
3. The contact reed
170
has a planar configuration which can only be moved and deformed in one direction in experiencing an increasing heat. Accordingly, the curved spring blade
18
shall be incorporated to achieve a two-directional breaking function. The curved spring blade
18
is made from metal sheet by punching. It's difficult to make the resilient rating of each curved spring blade
18
identical. If the rating is too high, the contact reed
170
can not be disconnected during the overloaded condition and the potential risk of getting fire will happen. If the rating is too weak, the engagement between two adjacent platinum conductive protrusions is insufficient such that a spark will be caused. This caused spark will reduce the service life of the platinum conductive protrusions
171
,
160
.
Taiwan Pat. 334165, as shown in
FIGS. 3A and 3B
, discloses a change-over device of a safety switch for protecting it from overload which is intended to remove the defects of the conventional switch. The safety switch includes a change-over button
20
having an insulting drive element
21
and an attachment element
22
at one end thereof. One end of a conductive strip
23
is clamped at one side of the attachment element
22
. The insulting drive element
21
is connected with a spring
24
at one end thereof. In case of overload, the conductive strip
23
will be deformed for disconnection from the contact point so that the conductive strip
23
together with the insulting drive element
21
are positioned by means of the insulting drive element
21
into an arched groove
25
for breaking the current loop. However, this kind of safety switch also includes the drawbacks of the U.S. Pat. No. 5,262,748. If one of the change-over button
20
, the insulting drive element
21
or the attachment element
22
is malfunctioned, the conductive strip
23
doesn't work even in case of overload. Besides, the spring
24
is wound by a metal wire so that it's difficult that the resilience of each section thereof is identical. The drawback of too strong or too weak resilience is also existing. Thus, it's still not an excellent safety switch.
Previously, the inventor of the present invention try to remove the above-mentioned defects with U.S. Pat. No. 5,760,672. It is characterized that a slight and proper jumping space (&Dgr;S) is created between a pushing part and a pulling part of a push-pull rod
9
(similar to the above-mentioned attachment element
22
). Accordingly, when a button shade or the push-pull rod
9
is malfunctioned, an alloy plate
7
(similar to the above-mentioned conductive strip
23
or the contact reed
170
) will also be deformed in a half-collapsible manner to be separated from the contact point
71
. Therefore, the switch is situated in a disconnected state for electrical safety. The expected effect thereof can be achieved under an ordinary state. However, the half-deformable design is still not a complete structure. Since the jumping space (&Dgr;S) is not perfect in setting and installing aspect, the half-deformable function wouldn't work even in case of a slight carelessness.
In the above-mentioned safety switches, the attachment element (or push-pull rod) and the conductive strip (contact reed or alloy plate) are connected in a coupled state. Therefore, if one of the attachment element or the change-over button is malfunctioned, the conductive strip can't be deformed for disconnection.
In addition, all kinds of the conventional
Rosenberg , Klein & Lee
Tsung-Mou Yu
Vortman Anatoly
LandOfFree
Universal device for safety switches does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Universal device for safety switches, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Universal device for safety switches will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2919181