Information
-
Patent Grant
-
6710277
-
Patent Number
6,710,277
-
Date Filed
Tuesday, December 17, 200222 years ago
-
Date Issued
Tuesday, March 23, 200420 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Friedhofer; Michael
- Klaus; Lisa
Agents
- Leydig, Voit & Mayer, Ltd.
-
CPC
-
US Classifications
Field of Search
US
- 200 520
- 200 DIG 42
- 200 523
- 200 325
- 200 529
- 200 533
- 200 534
- 200 535
- 200 6 R
- 200 6 B
- 200 440
- 200 441
-
International Classifications
-
Abstract
An electrical switch comprising a casing, a fixed contact and a moving contact, and an actuator supported for movement to a first position thereby moving the moving contact into contact with the fixed contact. The actuator is movable to a second position for permitting the moving contact to move out of contact from the fixed contact. Resilient means biases the moving contact out of contact from the fixed contact. The switch includes a remover having a part provided adjacent the fixed contact and movable by the actuator moving to the second position for removing the moving contact from the fixed contact in case the moving contact stays in contact with the fixed contact.
Description
BACKGROUND OF THE INVENTION
An electrical switch of the kind concerned typically has a casing, a fixed contact and a moving contact, and an actuator for moving the moving contact into contact with the fixed contact. The actuator is movable to an opposite position for permitting the moving contact to move out of contact from the fixed contact under the action of a spring.
In a faulty situation, the moving contact may be hindered from departing from the fixed contact while the switch is intended to be opened. This may occur, particularly but not exclusively, when the load current is large and the two contacts are welded together as a result of arcing and/or flashover across them.
The invention seeks to provide an improved electrical switch of this type in general.
SUMMARY OF THE INVENTION
According to the invention, there is provided an electrical switch comprising a casing, a fixed contact and a moving contact in the scaning, and an actuator supported by the casing for movement to a first position thereby moving the moving contact into contact with the fixed contact. The actuator is movable to a second position for permitting the moving contact to move out of contact from the fixed contact. Resilient means biases the moving contact out of contact from the fixed contact. The switch includes a remover having a part provided adjacent the fixed contact and movable by the actuator moving to the second position for removing the moving contact from the fixed contact in case the moving contact stays in contact with the fixed contact.
Preferably, the remover part is provided on the same side as the fixed contact relative to the moving contact for pushing the moving contact away from the fixed contact.
It is preferred that the remover is supported for sliding movement to remove the moving contact from the fixed contact.
It is further preferred that the electrical switch includes a pivotal member provided between the actuator and the remover for pivoting by the actuator to slide the remover.
In a preferred embodiment, the electrical switch includes a contact lever having a first end about which the lever is pivotably supported and an opposite second end supporting the moving contact. The remover part is arranged to act upon the second lever end for removing the moving contact from the fixed contact.
More preferably, the remover part faces the moving contact as the fixed contact and is slidable in a direction substantially perpendicular to the contact lever for hitting its second end to push the moving contact away from the fixed contact.
More preferably, the electrical switch includes a pivotal member provided between the actuator and the remover for pivoting by the actuator to move the remover, the pivotal member extending substantially parallel to the contact lever.
More preferably, the electrical switch includes a pivotal lever having a first end for pivoting by the actuator and a second end for moving the remover. The actuator includes a slider slidable by the actuator through a cam action, and the slider is positioned between the first ends of the contact lever and the pivotal lever.
Further more preferably, the actuator includes an inclined slot through which the slider extends at substantially right angles, such that the slider will be slid by the actuator through a cam action in a direction substantially perpendicular to the direction in which the actuator moves.
In a specific construction, the resilient means comprises a first spring biassing the actuator towards its second position and a second spring biassing the moving contact away from the fixed contact.
As an example, the electrical switch is a normally-open pushbutton switch.
BRIEF DESCRIPTION OF DRAWINGS
The invention will now be more particularly described, by way of example only, with reference to the accompanying drawings, in which:
FIG. 1
is a perspective view of an embodiment of an electrical switch in accordance with the invention;
FIG. 2
is an exposed perspective view the switch of
FIG. 1
, showing all its components;
FIG. 3
is a cross-sectional side view of the switch of
FIG. 1
in an open condition i.e. switched off; and
FIG. 4
is a cross-sectional side view of the switch of
FIG. 1
in a closed condition i.e. switched on.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT
Referring to the drawings, there is shown an electrical switch in the form of a pushbutton switch
100
embodying the invention. The switch
100
has a rectangular box-like plastic casing
110
including an open top side sealed by a plastic lid
120
, which contains a pair of left and right switching mechanisms
210
operated by a single pushbutton actuator
300
. Each mechanism
210
is associated with a pair of switch terminals
410
and
420
and includes a moving contact lever
500
for making and breaking electrical connection between the two terminals
410
and
420
, together constituting a switch unit
200
. The terminals
410
and
420
are located on opposite front and rear sides of the casing
110
, and the contact lever
500
inside the casing
110
.
Each switch unit
200
includes a plastic frames
220
that supports components of the corresponding switching mechanism
210
, and the two frames
220
are located side-by-side within the casing
110
. Only one switch unit
200
is shown in the drawings and described herein for clarity, while the other unit
200
is simply a mirror image thereof in terms of design and construction.
The first terminal
410
has a vertical limb
412
lying on a front wall
112
of the casing
110
, and a horizontal limb
414
that extends from a lower end of the first limb
412
to underlie a casing bottom wall
113
. The horizontal limb
414
turns upwards into the casing
110
and in there it mounts, at its free end on the bottle wall
113
, a vertical fixed contact plate
416
facing rearwards.
The second terminal
420
has a vertical limb
422
located within a double rear wall
114
of the casing
110
, and a horizontal limb
424
that extends from a U-turned upper end of the first limb
422
into the casing
110
. The free end of the limb
424
terminates into a horizontal palm
426
that lies on a lower platform
222
of the support frame
220
. The palm
426
has a cutout
427
and a pair of bottom recesses
428
an opposite sides of the cutout
427
. The platform
222
is situated immediately above the fixed contact plate
416
.
The contact lever
500
extends generally upright, having a bifurcate upper end or portion
502
and including a lower end
504
that supports a moving contact knob
506
for movement into and out of contact with the fixed contact plate
416
to perform a switching action. The contact lever
500
is supported for pivotal movement by a generally upright copper lever holder
510
, which is in turn hinged by the palm
426
of the second terminal
420
for simultaneous pivotal movement, both about a horizontal axis.
The lever holder
510
has a T-shaped lower end
512
, and includes a trifurcate upper end providing a pair of left and right side fingers
514
bent through 90° outwards and a straight middle finger
516
pointing upwards. The crooked fingers
514
have respective notches engaging the contact lever
500
by its upper end
502
, whereby the lever holder
510
hingedly supports the contact lever
500
. The T-shaped lower end
512
is anchored through the cutout
427
by the recesses
428
of the palm
426
, whereby the lever holder
510
is hinged to the palm
428
.
The contact lever
500
lies alongside in front of the lever holder
510
, and an extension coil spring
530
co-extends with the contact lever
500
through its the upper portion
502
. The spring
530
is stretched across the lower end
504
of the contact lever
500
and an upper pin
532
of the support frame
220
, thereby holding the contact lever
500
and in turn the lever holder
510
in position, while the latter is anchored to the palm
426
. The spring
530
is hooked at its lower end to a small hole
505
of the contact lever end
504
immediately above the contact knob
506
. In particular, the spring
530
resiliently biasses the contact lever
500
into an inclined stable position (FIG.
3
).
While the lever holder
510
is hinged about the palm
426
below it, its upper end fingers
514
may be pivoted to swing the upper end
502
of the contact lever
500
about generally its lower end
504
from the stable position to a less inclined second position (FIG.
4
). As the spring
530
is stretched longer given that the second position is less inclined, this position is unstable. The lever holder
510
is to be pivoted by the actuator
300
acting upon its upper middle finger
516
(as hereinafter described). Upon release of the lever holder
510
, the spring
530
reacts to return the contact lever
500
to the stable position.
In the stable position (FIG.
3
), the moving contact knob
506
separates from the fixed contact plate
416
, whereby the switch unit
200
is normally open (switched off). In the second position (FIG.
4
), the moving contact knob
506
bears against the fixed contact plate
416
, whereby the switch unit
200
is closed (switched on).
The actuator
300
has a plastic body
310
sandwiched by the two support frames
220
, which is resiliently biassed upwards by a pair of compression coil springs
320
also between the frames
220
. The body
310
protrudes out of the lid
120
through an aperture
122
thereof, and has an uppermost end
312
to which a press knob (not shown) is snapped on. The space between the end
312
and the aperture
122
is sealed off by a frusto-conical rubber bellow
314
for dust protection. The body
310
is formed with an inclined slot
316
as shown, which has upper and lower ends
317
and
318
.
The actuator
300
includes a horizontal rod
330
inside the support frames
220
, which extends through the slot
316
at right angles and whose opposite ends carry a pair of knobs
332
disposed thereon. The rod
330
is slidable sideways back-and-forth along a linear passage
228
formed by a pair of opposed horizontal tracks inside the frames
220
. There is a cam action between the rod
330
and the slot
316
, which causes the rod
330
to slide rearwards (to the right in
FIG. 3
) or forwards (to the left in
FIG. 4
) when the body
310
is lifted by the springs
320
or lowered upon depression respectively.
The upper end middle finger
516
of the lever holder
510
is positioned in front of and aligned with the corresponding knob
332
of the rod
330
. When the rod
330
slides forwards, each of its knobs
332
will pivot the corresponding lever holder
510
by pushing its upper middle finger
516
, thereby closing both switch units
200
. Upon rearward sliding of the rod
330
, its two knobs
332
will release the corresponding lever holders
510
, thereby allowing both switch units
200
to return to the normally-open condition.
The platform
222
includes a central tunnel
224
which has front and rear ends
225
and
226
and extends horizontally from back to front through the support frame
220
. The tunnel front end
225
is positioned adjacent and immediately above the fixed contact plate
416
, together facing the moving contact knob
506
.
A plunger
250
is received in the tunnel
224
for sliding movement therealong. Immediately behind the plunger
250
, a generally upright kick lever
260
is hinged at mid-length by a horizontal pin
266
of the support frame
220
for pivotal motion. The lever
260
has upper and lower ends
262
and
264
and is provided between the actuator
300
and the plunger
250
.
The upper lever end
262
is positioned behind and aligned with the corresponding knob
332
of the rod
330
, for movement by the knob
332
when the rod
330
slides rearwards (to the right in
FIG. 3
) during opening of the switch unit
200
, whereby the lever
260
is pivoted. The lower lever end
264
is aligned with the rear plunger end
254
for kicking the plunger
250
forwards to protrude its front end
252
out of the front tunnel end
225
, or to protrude it further out, simultaneously upon said pivoting of the lever
260
.
The rear plunger end
254
is enlarged to stop the plunger
250
over protruding from the tunnel end
225
. Upon closing of the switch unit
200
, the knob
332
slides forwards (to the left in
FIG. 4
) away from the upper lever end
262
, whereby the lever
262
and in turn the plunger
250
is released. While the plunger
250
is free (to a limited but sufficient extent), it will not obstruct pivoting close of the contact lever
500
.
The front tunnel end
225
is positioned on the same side as the contact plate
416
relative to the contact knob
506
such that the associated plunger end
252
faces or points at the contact lever
500
. The plunger end
252
will, upon protruding, reach out to the position where the small hole
505
of the contact lever
500
was previously. In normal circumstances, given that the lower end
504
of the contact lever
500
will simultaneously be leaving this position under the action of the spring
530
, the plunger end
252
will not hit or touch the lever
500
(FIG.
3
).
The plunger
250
acts as a contact remover and is deployed as a safety measure for action in a faulty situation during intended opening of the switch unit
200
, where the contact lever
500
is hindered from pivoting its contact knob
506
away from the fixed contact plate
416
. This may occur, particularly but not exclusively, when the load current is large and the two contact members
506
and
416
are welded together by arcing and/or flashover across them. The plunger
250
is useful to hit the contact lever
500
in the region of its lower end small hole
505
, or the lower end of the spring
530
engaged thereat, thereby striking off or removing the contact knob
506
from the contact plate
416
.
It is important to note that the precise form of the contact remover
250
, including the lever
260
therefor, is not essential. For example, these two components may be replaced by a single lever, or a simple linkage, arranged to transmit the self-return movement of the actuator
300
to the moving contact
500
/
506
. Also, the contact remover
250
may act upon the moving contact
500
/
506
from behind, i.e. pulling instead of pushing.
In general, the subject electrical switch may not need to be a pushbutton switch and can be, for example, a rocker or toggle switch. It is also not necessarily a normally-open switch.
The invention has been given by way of example only, and various other modifications of and/or alterations to the described embodiment may be made by persons skilled in the art without departing from the scope of the invention as specified in the appended claims.
Claims
- 1. An electrical switch comprising:a casing; a fixed contact and a moving contact in the casing; an actuator supported by the casing for movement to a first position thereby moving the moving contact into contact with the fixed contact, the actuator being movable to a second position for permitting the moving contact to move out of contact from the fixed contact; resilient means biassing the moving contact out of contact from the fixed contact; and a remover having a part provided adjacent the fixed contact and movable by the actuator moving to the second position for removing the moving contact from the fixed contact in case the moving contact stays in contact with the fixed contact.
- 2. The electrical switch as claimed in claim 1, wherein the remover part is provided on a same side as the fixed contact relative to the moving contact for pushing the moving contact away from the fixed contact.
- 3. The electrical switch as claimed in claim 1, wherein the remover is supported for sliding movement to remove the moving contact from the fixed contact.
- 4. The electrical switch as claimed in claim 3, including a pivotal member provided between the actuator and the remover for pivoting by the actuator to slide the remover.
- 5. The electrical switch as claimed in claim 1, including a contact lever having a first end about which the lever is pivotably supported and an opposite second end supporting the moving contact, and the remover part is arranged to act upon the second lever end for removing the moving contact from the fixed contact.
- 6. The electrical switch as claimed in claim 5, wherein the remover part faces the moving contact as the fixed contact and is slidable in a direction perpendicular to the contact lever for hitting its second end to push the moving contact away from the fixed contact.
- 7. The electrical switch as claimed in claim 5, including a pivotal member provided between the actuator and the remover for pivoting by the actuator to move the remover, the pivotal member extending parallel to the contact lever.
- 8. The electrical switch as claimed in claim 5, including a pivotal lever having a first end for pivoting by the actuator and a second end for moving the remover, wherein the actuator includes a slider slidable by the actuator through a cam action, and the slider positioned between the first ends of the contact lever and the pivotal lever.
- 9. The electrical switch as claimed in claim 8, wherein the actuator includes an inclined slot through which the slider extends at right angles, such that the slider will be slid by the actuator through a cam action in a direction perpendicular to the direction in which the actuator moves.
- 10. The electrical switch as claimed in claim 1, wherein the resilient means comprises a first spring biassing the actuator towards its second position and a second spring biassing the moving contact away from the fixed contact.
- 11. The electrical switch as claimed in claim 1, being a normally-open pushbutton switch.
US Referenced Citations (2)
Number |
Name |
Date |
Kind |
5164561 |
Schaeffeler et al. |
Nov 1992 |
A |
5651452 |
Schaeffeler et al. |
Jul 1997 |
A |