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Claims  |
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The embodiments of the invention in which an exclusive property or right is
claimed are defined as follows:
1. A switch, comprising:
a housing;
a carrier disposed within said housing, said carrier being movable within
said housing;
a plunger disposed within said housing, said plunger being movable relative
to said carrier, said plunger being movable relative to said housing;
a first stationary electrical contact structure attached to said housing at
a first side of said carrier;
a second stationary electrical contact structure attached to said housing
at a second side of said carrier;
a first movable electrical contact structure attached to said carrier at
said first side of said carrier;
a second movable electrical contact structure attached to said carrier at
said second side of said carrier;
first means for causing said first movable electrical contact structure to
move from a first position relative to said first stationary electrical
contact structure to a second position relative to said first stationary
electrical contact structure;
second means for causing said second movable electrical contact structure
to move from a first position relative to said second stationary
electrical contact structure to a second position relative to said second
stationary electrical contact structure;
first means for actuating said first and second causing means sequentially;
first means for forcing said first movable electrical contact structure to
move from said first position relative to said first stationary electrical
contact structure to said second position relative to said first
stationary electrical contact structure;
second means for forcing said second movable electrical contact structure
to move from said first position relative to said second stationary
electrical contact structure to said second position relative to said
second stationary electrical contact structure; and
second means for actuating said first and second forcing means
sequentially.
2. The switch of claim 1, wherein:
said first causing means comprises a first resilient pivot, said first
resilient pivot being pivotably attached to said plunger and to said
carrier; and
said second causing means comprises a second resilient pivot, said second
resilient pivot being pivotably attached to said plunger and to said
carrier.
3. The switch of claim 1, wherein:
said first forcing means comprises a first cam.
4. The switch of claim 3, wherein:
said first cam is rotatably attached to said housing, said first cam being
rotatable in response to contact with said plunger, said carrier being
movable in response to rotation of said first cam.
5. The switch of claim 1, wherein:
said second forcing means comprises a second cam.
6. The switch of claim 5, wherein:
said second cam is rotatably attached to said housing, said second cam
being rotatable in response to contact with said plunger, said carrier
being movable in response to rotation of said second cam.
7. The switch of claim 1, wherein:
said first stationary electrical contact structure comprises a first
electrically conductive pad at said first position relative to said first
stationary electrical contact structure and a second electrically
conductive pad at said second position relative to said first stationary
electrical contact structure.
8. The switch of claim 1, wherein:
said second stationary electrical contact structure comprises a first
electrically conductive pad at said first position relative to said second
stationary electrical contact structure and a second electrically
conductive pad at said second position relative to said second stationary
electrical contact structure.
9. The switch of claim 1, wherein:
said second actuating means comprises first and second surfaces of said
plunger, said first and second surfaces being disposed in planes which are
displaced apart from each other.
10. The switch of claim 9, wherein:
said second surface is disposed in a notch formed in said plunger.
11. A switch, comprising:
a housing;
a carrier disposed within said housing, said carrier being movable within
said housing;
a plunger disposed within said housing, said plunger being movable relative
to said carrier, said plunger being movable relative to said housing;
a first stationary electrical contact structure attached to said housing at
a first side of said carrier;
a second stationary electrical contact structure attached to said housing
at a second side of said carrier;
a first movable electrical contact structure attached to said carrier at
said first side of said carrier;
a second movable electrical contact structure attached to said carrier at
said second side of said carrier;
first means for causing said first movable electrical contact structure to
move from a first position relative to said first stationary electrical
contact structure to a second position relative to said first stationary
electrical contact structure;
second means for causing said second movable electrical contact structure
to move from a first position relative to said second stationary
electrical contact structure to a second position relative to said second
stationary electrical contact structure;
first means for actuating said first and second causing means sequentially;
first means for forcing said first movable electrical contact structure to
move from said first position relative to said first stationary electrical
contact structure to said second position relative to said first
stationary electrical contact structure;
second means for forcing said second movable electrical contact structure
to move from said first position relative to said second stationary
electrical contact structure to said second position relative to said
second stationary electrical contact structure; and
second means for actuating said first and second forcing means
sequentially, said first causing means comprising a first resilient pivot,
said first resilient pivot being pivotably attached to said plunger and to
said carrier, said second causing means comprising a second resilient
pivot, said second resilient pivot being pivotably attached to said
plunger and to said carrier.
12. The switch of claim 11, wherein:
said first forcing means comprises a first cam.
13. The switch of claim 12, wherein:
said first cam is rotatably attached to said housing, said first cam being
rotatable in response to contact with said plunger, said carrier being
movable in response to rotation of said first cam.
14. The switch of claim 11, wherein:
said second forcing means comprises a second cam.
15. The switch of claim 14, wherein:
said second cam is rotatably attached to said housing, said second cam
being rotatable in response to contact with said plunger, said carrier
being movable in response to rotation of said second cam.
16. The switch of claim 11, wherein:
said first stationary electrical contact structure comprises a first
electrically conductive pad at said first position relative to said first
stationary electrical contact structure and a second electrically
conductive pad at said second position relative to said first stationary
electrical contact structure.
17. The switch of claim 11, wherein:
said second stationary electrical contact structure comprises a first
electrically conductive pad at said first position relative to said second
stationary electrical contact structure and a second electrically
conductive pad at said second position relative to said second stationary
electrical contact structure.
18. The switch of claim 11, wherein:
said second actuating means comprises first and second surfaces of said
plunger, said first and second surfaces being disposed in planes which are
displaced apart from each other.
19. The switch of claim 18, wherein:
said second surface is disposed in a notch formed in said plunger.
20. A switch, comprising:
a housing;
a carrier disposed within said housing, said carrier being movable within
said housing;
a plunger disposed within said housing, said plunger being movable relative
to said carrier, said plunger being movable relative to said housing;
a first stationary electrical contact structure attached to said housing at
a first side of said carrier;
a second stationary electrical contact structure attached to said housing
at a second side of said carrier;
a first movable electrical contact structure attached to said carrier at
said first side of said carrier;
a second movable electrical contact structure attached to said carrier at
said second side of said carrier;
first means for causing said first movable electrical contact structure to
move from a first position relative to said first stationary electrical
contact structure to a second position relative to said first stationary
electrical contact structure;
second means for causing said second movable electrical contact structure
to move from a first position relative to said second stationary
electrical contact structure to a second position relative to said second
stationary electrical contact structure;
first means for actuating said first and second causing means sequentially;
first means for forcing said first movable electrical contact structure to
move from said first position relative to said first stationary electrical
contact structure to said second position relative to said first
stationary electrical contact structure;
second means for forcing said second movable electrical contact structure
to move from said first position relative to said second stationary
electrical contact structure to said second position relative to said
second stationary electrical contact structure; and
second means for actuating said first and second forcing means
sequentially, said first causing means comprising a first resilient pivot,
said first resilient pivot being pivotably attached to said plunger and to
said carrier, said second causing means comprising a second resilient
pivot, said second resilient pivot being pivotably attached to said
plunger and to said carrier, said first forcing means comprising a first
cam, said first cam being rotatably attached to said housing, said first
cam being rotatable in response to contact with said plunger, said carrier
being movable in response to rotation of said first cam, said second
forcing means comprising a second cam, said second cam being rotatably
attached to said housing, said second cam being rotatable in response to
contact with said plunger, said carrier being movable in response to
rotation of said second cam, said first stationary electrical contact
structure comprising a first electrically conductive pad at said first
position relative to said first stationary electrical contact structure
and a second electrically conductive pad at said second position relative
to said first stationary electrical contact structure, said second
stationary electrical contact structure comprising a first electrically
conductive pad at said first position relative to said second stationary
electrical contact structure and a second electrically conductive pad at
said second position relative to said second stationary electrical contact
structure, said second actuating means comprising first and second
surfaces of said plunger, said first and second surfaces being disposed in
planes which are displaced apart from each other, said second surface
being disposed in a notch formed in said plunger. |
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Claims |
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Description |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to sequence switches that are
provided with a forced disconnect capability and, more particularly, to a
double-pole double-throw switch that moves a first set of movable contacts
prior to a second set of movable contacts and then forces the movement in
the event that a failure of some type prevented the normal movement of the
contacts.
2. Description of the Prior Art
Many different types of switches are well known to those skilled in the
art. In addition, it is also known to provide a switch with a forced
disconnect capability. This capability is also referred to as a positive
break capability. The purpose for a forced disconnect characteristic in a
switch is to mechanically force the movable contacts away from the
stationary contacts in the event of a switch failure wherein the movable
and stationary contacts become welded together. In switches that do not
have this positive break characteristic, the movable and stationary
contacts can be welded together and, even though the switch mechanism
attempts to open the electrical connection, the movable and stationary
contacts remain in electrical communication with each other because they
are welded together. A positive break characteristic provides an
additional mechanism that is able to force the disconnection of the
movable and stationary contacts mechanically and break the weld
connection.
U.S. Pat. No. 5,283,406, which issued to Olsen on Feb. 1, 1994, discloses a
switch with a movable carrier to which movable contacts are attached. The
switch is provided with a movable contact and a contact carrier that
significantly facilitates the manufacturing process that is necessary to
make the assembly. The contact carrier is provided with first and second
extensions that are generally flexible and associated with each other to
provide a gap therebetween. In the preferred embodiment of the device, the
second extension comprises first and second fingers that extend from the
contact carrier. The second extension is provided with protuberances that
permit a movable contact to deform the second extension as it is moved
inward toward the contact carrier. The extensions snap together after the
complete movable contact has moved into a predetermined space between the
extensions. The assembly of the present invention permits the movable
contact to be permanently retained between the first and second
extensions, but variably movable in position within that containment to
permit the position of the movable contact to adjust to the position of
the fixed contact with the contact carrier is moved within a housing
structure to force the movable contacts into electrical communication with
a pair of fixed contacts. The switch described in the. Olsen patent is a
double-pole double-throw switch. In addition, it illustrates a positive
break mechanism that comprises rotatable cams that can force the contacts
open even though they may be welded together.
Sequence switches are known to those skilled in the art. The purpose of a
sequence switch is to cause one set of movable and stationary contacts to
move relative to each other prior to a similar relative movement between
another set of stationary and movable contacts. When a switch of this type
is connected to electrical circuitry, a first circuit can be energized or
deenergized prior to a similar change in another circuit. The switch
described in the Olsen patent does not provide this sequencing capability.
Because of the necessity for a sequence switch to actuate or de-actuate
one set of contacts prior to another set of contacts, the forced
disconnect capability, or positive break capability, has not been
implemented in sequencing switches. It would therefore be significantly
beneficial if the capability to provide a forced disconnect mechanism was
available in a sequence switch.
SUMMARY OF THE INVENTION
The present invention provides a sequence switch that has the capability of
mechanically forcing its movable contacts away from its stationary
contacts in the event that the contacts are welded together through a
malfunction of the switch or associated circuitry. A switch made in
accordance with the present invention comprises a housing and a carrier
disposed within the housing. The carrier is movable within the housing. A
plunger is disposed within the housing in a way that allows the plunger to
be movable relative to the carrier and also movable relative to the
housing.
A first stationary electrical contact structure is attached to the housing
at a first side of the carrier and a second stationary electrical contact
structure is attached to the housing at a second side of the carrier.
First and second movable electrical contact structures are attached to the
carrier at the first and second sides of the carrier, respectively. The
movable electrical contact structures are able to be moved from a first
position to a second position relative to the stationary electrical
contact structures.
A first means is provided for causing the first movable electrical contact
structure to move from a first position relative to a first stationary
electrical contact structure to a second position relative to the first
stationary electrical contact structure. Similar means are provided for
causing the second movable electrical contact structure to move from a
first position relative to the second stationary electrical contact
structure to a second position relative to the second stationary
electrical contact structure. A first means is provided for actuating the
first and second causing means in a sequential order. In other words, the
first and second causing means are not actuated simultaneously but,
instead, according to a predetermined sequence.
A first means is provided for forcing the first movable electrical contact
structure to move from the first position to the second position and a
second means is provided for forcing the second movable electrical contact
structure to move from the first position to the second position. In
addition, a second means is provided for actuating the first and second
forcing means in a sequential order. In other words, the forcing means are
provided so that they can mechanically force the contacts apart in the
event that they become welded together.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be more fully and completely understood from a
reading of the Description of the Preferred Embodiment in conjunction with
the drawings, in which:
FIGS. 1 and 2 show switches made in accordance with the prior art;
FIG. 3 is an exploded perspective view of a switch made in accordance with
the present invention;
FIG. 4 is a sequence switch made in accordance with the prior art;
FIG. 5 is an illustration of a positive break sequence switch made in
accordance with the present invention; and
FIG. 6 is a perspective view of a forced disconnect sequence switch made in
accordance with the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Throughout the Description of the Preferred Embodiment, like components
will be identified by like reference numerals.
In U.S. Pat. No. 5,283,406, which is explicitly incorporated by reference
herein, a double-pole double-throw switch is described in detail. Exploded
views of a double-pole double-throw switch are clearly illustrated in U.S.
Pat. No. 5,283,406 along with the cam structures that are used to provide
the forced disconnect mechanism of the switch. These cams provide the
positive break characteristic of the switch. However, it should be
understood that the switch that is described in detail in U.S. Pat. No.
5,283,406 is not a sequence switch. In other words, the switch described
and illustrated in U.S. Pat. No. 5,283,406 is intended to move both sets
of movable contacts into and out of contact with the related stationary
contacts simultaneously with no sequencing behavior. The present
invention, on the other hand, is intended for use in switches that are
specifically designed to operate as sequence switches. The present
invention provides a means for allowing a sequence switch to also be a
positive break, or forced disconnect, switch.
FIG. 1 illustrates the type of switch described in U.S. Pat. No. 5,283,406.
It shows a switch similar to the one illustrated in FIG. 9 of U.S. Pat.
No. 5,283,406. A carrier 100 is disposed within a housing 110. A plunger
112 is slideably disposed through the carrier 100 and is movable relative
to both the carrier 100 and the housing 110. A plurality of connectors 114
are provided to permit the switch to be connected to external circuitry.
Reference numeral 120 identifies a resilient pivot that will be described
in greater detail below. Two resilient pivots, 120 and 122, are typically
used in switches of this type. On a first side of the carrier, stationary
contacts 130 and 132 are provided. Movable contact pads 136 and 138 are
attached to the carrier 100 for movement with the carrier in an up and
down manner. On a second side of the carrier 100, stationary contacts 140
and 142 are associated with electrical contact pads 146 and 148 which are
attached to a support structure 150. Two cams, which are identified by
reference numerals 160 and 162, are provided to force the carrier 100 in
an upward direction in response to a full downward movement of the plunger
112. In other words, the plunger 112 causes the carrier 100 to move in an
upward direction in response to the movement of the resilient pivot 120
after the plunger 112 moves downward a preselected distance. As the
plunger 112 continues to move downward, its bottom portion eventually
moves into contact with cams 160 and 162 and causes the cams to pivot
about their central axes. This rotation of the cams pushes upward against
the bottom portion of the carrier 100 if the carrier 100 has not already
moved upward. This mechanical action of the cams against the carrier 100
forces the movable contacts upward relative to the stationary contacts if
the movable and stationary contacts are welded together through some
malfunction of the system.
FIG. 1 shows the basic operation of a positive break, or forced disconnect,
switching mechanism. The plunger 112 is caused to move downward by a force
such as that indicated by arrow F in FIG. 1. This downward movement of the
plunger 112 causes the actuation and de-actuation of the switch and also
causes the mechanical action of the cams 160 and 162.
FIG. 2 shows an alternative representation of the switch illustrated in
FIG. 1. The illustration of FIG. 2 permits certain components to be seen
which would otherwise be hidden behind other portions of the switch. More
specifically, the resilient pivots, 120 and 122, are illustrated in their
operative positions. Both of these resilient pivots are pivotably attached
to the plunger 112 and the carrier 110. In other words, one end of each
resilient pivot is pivotably associated with a pivot point on the plunger
112. The other end of both resilient pivots is pivotably associated with a
pivot point on the carrier. The basic operation of a switch like the one
shown in FIG. 2 is that a downward movement of the plunger 112 eventually
causes the pivot points of the plunger 112 to move below the pivot points
on the carrier 100. When this occurs, the resilient portion of the
resilient pivots forces the plunger and carrier away from each other with
the carrier 100 moving upward and the plunger 112 continuing in a downward
movement. As the plunger 112 continues downward in response to force F,
the bottom surface 200 of the plunger 112 moves into contact with a
portion of the cams, 160 and 162, and causes the cams to rotate about
their central axes. This rotation of cam 160 in a clockwise direction and
of cam 162 in a counterclockwise direction causes the cams to push upward
against the bottom surfaces of the legs of the carrier 100. Switches of
this type are available and are known to those skilled in the art.
FIG. 3 illustrates an exploded view of a switch made in accordance with the
present invention. Certain portions of the switch shown in FIG. 3 are
similar to those described above in conjunction with FIGS. 1 and 2. For
example, the carrier 100 is functionally similar to the carrier described
above and shown in FIGS. 1 and 2. Likewise, the resilient pivots, 120 and
122, operate in a manner generally similar to that described above. The
plunger 312 is slightly different than the plunger 112 described above.
For example, the pivot points, 302 and 304, are offset from each other to
provide a sequencing of the movement of the carrier 100. This sequencing
characteristic, which is generally known to those skilled in the art, will
be described in greater detail below. The plunger 312 is provided with a
return spring 320 that causes it to move back to its original position
when a force F is removed. The cams, 160 and 162, are similar to those
described above.
With continued reference to FIG. 3, the cams are disposed on their axes,
330 and 332, so that they can pivot relative to the housing 110. The
carrier 100 is disposed within the housing and associated with the
alignment track 340 to control its upward and downward movement relative
to the housing 110. The plunger 312 is inserted through the carrier 100
and aligned with opening 347.
When cams, 160 and 162, rotate about their axes, 330 and 332, they are
caused to push upwardly against surfaces, 390 and 392, of the carrier 100.
This upward movement provides the positive break, or forced disconnect,
feature of the switch. With reference to the plunger 312 shown in FIG. 3,
an important difference between its shape and the shape of the plunger 112
described above can be seen. The bottom surface 200 of plunger 312 is
provided with a discontinuity that creates an additional surface 360.
Surfaces 200 and 360 are disposed in planes which are displaced from each
other. When plunger 312 is inserted within housing 110, the two surfaces,
200 and 360, are at different heights relative to the plane in which the
axes, 330 and 332 are disposed. This also places surfaces 200 and 360 at
different distances from cams 160 and 162 than was the case in FIGS. 1 and
2. In other words, surface 200 of plunger 112 in FIGS. 1 and 2 is
displaced from cams 160 and 162 by a constant distance. When the surface
200 moved into contact with one of the cams, it moved into contact with
the other cam simultaneously.
FIG. 4 is generally similar to FIG. 2, but illustrates a known structure
for providing a sequence switch which is available in commercial
quantities from the MICRO SWITCH division of Honeywell Incorporated and is
identified as Catalog No. GLZ321 as a basic switch and Catalog No. GLAA21B
as a complete limit switch. Since the resilient pivots, 120 and 122, are
associated with pivot points, 302 and 304, which are displaced from each
other in an offset manner as shown in FIG. 4, the movable contacts on the
left side of the carrier 100 operate sequentially before the moveable
contacts on the right side of the carrier 100. As the plunger 112 moves
downward in response to force F, resilient pivot 122 moves into a
generally horizontal position prior to resilient pivot 120 moving into a
generally horizontal position. This results from the fact that pivot point
302 is higher than pivot point 304. Therefore, as resilient pivot 122
moves into its over center position and begins to expand, the movable
contacts on the left side of the carrier 100 will move out of contact with
the lower stationary contacts and into contact with the upper stationary
contacts on the left side of the switch. This occurs prior to a similar
action by the movable contacts on the right side of the switch. As plunger
112 continues to move downward, resilient pivot 120 eventually moves into
a horizontal position and then begins to expand after it reaches an over
center position. This expansion then causes the right side of the carrier
100 to move upward and move its movable contacts from electrical
communication with the lower stationary contacts on the right side of the
switch toward a second position where they move into electrical
communication with the upper stationary contacts on the right side of the
switch. Therefore, the status of the movable contacts on the left side of
the switch changes prior to the change in status of the movable contacts
on the right side of the switch. This provides the sequencing nature of a
switch. This sequencing nature is generally known to those skilled in the
art and can be provided by applying several alternative techniques.
However, because of this sequencing characteristic, it has been heretofore
impossible to provide a positive break or forced disconnect characteristic
to a sequencing switch. The normal manner of using cams to rotate in
response to contact by the bottom surface 200 of the plunger 112 could not
be applied because the movable contacts on the left side and right side of
the carrier must be changed in status sequentially.
FIG. 5 illustrates a preferred embodiment of the present invention which
combines the features of sequencing and positive break to a single switch.
In operation, a downward force F on plunger 312 causes it to begin to move
downward relative to the housing 110. This downward movement eventually
causes resilient pivot 122 to move to a horizontal position and then snap
over center to cause the movable contacts on the left side of the switch
to move out of electrical contact with the lower stationary contacts on
the left side of the switch and into electrical communication with the
upper stationary contacts on the left side of the switch. As plunger 312
continues to move downward, resilient pivot 120 eventually moves into a
generally horizontal position and then snaps over center to cause the
right side of the carrier 100 to move upward. When this occurs, the
movable contacts on the right side of the switch move upward relative to
the housing 110 and out of electrical communication with the lower
stationary contacts on the right side of the switch. This places the
movable contacts into a second position where they are in electrical
communication with the stationary contacts on the right side of the
switch. Therefore, when the plunger 312 is at this position, the two
movable contacts on the left and right sides of the carrier have
sequentially changed their positions. Continued downward movement of the
plunger 312 causes surface 200 of plunger 312 to move into contact with
portion 510 of the cam 160. This contact rotates cam 160 clockwise about
its central axis and moves the left side of cam 160 upward into physical
contact with the lower surface of carrier 110 which is identified by
reference numeral 390 in FIG. 3. When surface 200 moves into contact with
cam 160, cam 162 is unaffected and remains in its unactuated position.
Eventually, continued downward movement of plunger 312 moves surface 360
into contact with portion 516 of cam 162. This causes cam 162 to rotate in
a counterclockwise direction about its central axis. This moves the right
portion of cam 162 into contact with the lower surface of carrier 100
which is identified by reference numeral 392 in FIG. 3.
With continued reference to FIG. 5, it should be understood that the action
of cam 160 provides a positive break for the movable and stationary
contacts on the left side of the carrier 100 while cam 162 provides this
same function for the movable and stationary contacts on the right side of
the carrier 100. These two mechanical forced separations are provided
sequentially in conformance with the intended operation of the sequence
switch. Therefore, if either of the movable contacts becomes welded to the
lower stationary contact, the action of the associated cam, 160 or 162,
will separate the movable contact from its associated stationary contact.
Therefore, the present invention makes possible the application of a
positive break characteristic in conjunction with a sequence switch which
has heretofore been unavailable.
FIG. 6 is a perspective view of a forced disconnect sequence switch made in
accordance with the present invention. The view provided by FIG. 6
illustrates the relative positions of the resilient pivots, 120 and 122,
relative to the carrier 100 and also shows the plunger 312 in its position
relative to the carrier 100. It should be understood that the upward and
downward movement of the carrier 100 relative to the housing 110 is of
only a slight magnitude which is sufficient to move the movable contacts
in to and out of contact with the stationary contacts. It should also be
understood that the structure of the resilient pivots, 120 and 122, is
generally known to those skilled in the art. Each resilient pivot
comprises first and second ends that are associated with each other
through the central portion of a spring.
Although the present invention has been described in considerable detail to
illustrate and disclose a preferred embodiment of the present invention,
it should be understood that alternative embodiments are also within its
scope.
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Description |
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