U.S. patent number 3,815,060 [Application Number 05/352,767] was granted by the patent office on 1974-06-04 for electromagnetic contactor for battery powered vehicles.
This patent grant is currently assigned to Square D Company. Invention is credited to Merlin Y. Turnbull.
United States Patent |
3,815,060 |
Turnbull |
June 4, 1974 |
**Please see images for:
( Certificate of Correction ) ** |
ELECTROMAGNETIC CONTACTOR FOR BATTERY POWERED VEHICLES
Abstract
A compact contactor for a battery operated lift truck. The
contactor may be mounted in either of two positions and has its
terminals arranged so it can be easily connected in a reversing
circuit for a motor. The contactor includes a novel movable contact
support which is molded in situ with a magnet plunger. The movable
contact support completely isolates the springs for the movable
contacts from the switching areas of the contactor and provides a
guide for the movements of the plunger. The support for the
stationary contact is arranged to position the terminals of the
contactor so the contactor is easy to wire and permit a range of
different sized contacts to be mounted on the support and
electrically connected by a pair of metal members.
Inventors: |
Turnbull; Merlin Y.
(Brookfield, WI) |
Assignee: |
Square D Company (Park Ridge,
IL)
|
Family
ID: |
23386415 |
Appl.
No.: |
05/352,767 |
Filed: |
April 19, 1973 |
Current U.S.
Class: |
335/133;
335/131 |
Current CPC
Class: |
H01H
50/546 (20130101); H01H 51/005 (20130101) |
Current International
Class: |
H01H
51/00 (20060101); H01H 50/54 (20060101); H01h
050/20 () |
Field of
Search: |
;335/133,132,202,255,126,131 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Broome; Harold
Attorney, Agent or Firm: Schmeling; William H. Rathbun;
Harold J.
Claims
What is claimed is:
1. In a D.C. operated electromagnetic switch the combination
comprising: a frame having a pair of spaced ends and portions
interconnecting the ends providing a path for magnet flux passing
through the ends, a magnet coil positioned between the ends, said
magnet coil having a cylindrical passage axially aligned with an
opening in a first of the pair of ends and a coil winding
surrounding the passage, a plunger having a cylindrical portion
movable in the passage and a portion extending through the opening
to a free end and a cavity in the plunger extending from the free
end axially into the cylindrical portion, an insulating support
mounted on the first end, said insulating support having an opening
extending therethrough axially aligned with passage, and a pair of
spaced stationary contacts mounted on a front surface of the
support on opposite sides of the opening, and an insulating movable
contact carrier having a portion extending through the opening in
the support and a portion molded in situ in the cavity
2. The combination as recited in claim 1 wherein portions of the
contact carrier engage portions of the block surrounding the
opening in the block for preventing rotation of the plunger in the
passage.
3. The combination as recited in claim 1 wherein the carrier and
plunger have axially aligned bores extending therethrough.
4. The combination as recited in claim 3 wherein the portion of the
carrier extending through the opening has an end providing movable
contact support surface that extends in a plane normal to the axis
of the bore through the carrier and a movable contact is positioned
on the contact support surface to provide a bridging engagement
with the stationary contacts.
5. The combination as recited in claim 4 wherein the
cross-sectional area of the bore at the end providing the movable
contact surface is reduced to provide a spring seat and the movable
contact is positioned on the contact surface by a member that has
an end extending through the reduced portion of the bore and
through an opening in a central portion of the movable contact.
6. The combination as recited in claim 4 wherein the member has an
enlarged end movable in the bore in the contact carrier and a
spring is positioned between the enlarged end and the spring
seat.
7. The combination as recited in claim 6 wherein the enlarged end
is movable along the walls forming the bore with a piston-like
action.
8. The combination as recited in claim 7 wherein the portion of the
plunger providing the free end includes a pair of ears extending
from said portion normal to the axis of the passage and said first
end includes a pair of non-magnet stop surfaces that are engaged by
the ears to limit the movement of the plunger in one direction when
the coil is energized by direct current.
9. A reversing direct current contactor assembly comprising: a pair
of identical electromagnetically operated switches, each of said
switches including: an electromagnet comprising a frame having a
rear end, a front end, and portions connecting the rear end and the
front end providing a path for magnet flux passing through said
ends, a magnet coil positioned between the ends, said coil having a
cylindrical bore extending along a first axis with a front end of
the bore aligned with a circular opening in the front end of the
frame and a coil winding surrounding the cylindrical bore, and a
cylindrical plunger having a rear end portion movable in the bore
and a front end portion extending through the opening in the front
end of the frame, an insulating stationary contact support secured
on the front end of the frame, said support having a passage
extending therethrough aligned on the first axis, an insulating
movable contact carrier extending through the passage, said carrier
having a rear end secured to the front end of plunger and a movable
contact support surface at a front end of the carrier disposed
forwardly of a front surface of the support, an elongated movable
contact mounted on the support surface, said movable contact having
a central portion centered on the first axis and portions extending
in opposite directions from the central portion along a second axis
that is perpendicular to the first axis, means for positioning the
pair of switches so the second axis of the respective switches are
aligned in a plane through the first axis of both switches with the
switches spaced equidistantly from a third axis that extends
perpendicular to the plane so a side on the stationary contact
support of a first of the pair of switches confronts a side on the
stationary contact support of a second of the pair of switches with
the confronting sides extending parallel and in spaced relation to
the third axis, each of said switches including a pair of
stationary contact assemblies mounted on a portion of the front
surface of the support most proximate the third axis, a first of
said pair of contact assemblies including a metal support having a
mounting portion secured to portion of a corner of the front
surfaces of the support adjacent the confronting sides and a side
of the support that is spaced from a first side of the plane and a
contact support portion extending from the mounting portion along
an axis parallel to the third axis to a free end, a second of said
pair of contact assemblies including a metal support having a
mounting portion secured to a portion of a corner of the front
surface of the support adjacent the confronting side and a side of
the support that is spaced from a second side of the plane and a
contact support portion extending from the mounting portion along
an axis parallel to the third axis to a free end, said means for
positioning the switches including a first metal piece
interconnecting the mounting portions of the first pair of contact
assemblies and a second metal piece interconnecting the mounting
portions of the second pair of contact assemblies, each of said
metal pieces having a threaded opening and a means for connecting a
bared end of a wire centered on the third axis and an insulating
part formed of arc suppressing material, said part having a body
portion centered along the third axis and extending in the space
between the switches and a pair of ears extending from the body
portion, each of said ears having an opening aligned with one of
the openings in the metal pieces for mounting said insulating part
on the metal pieces, said insulating part providing a means for
directing hot gases generated upon the opening of the contacts of
said switches.
10. The combination as recited in claim 9 wherein each of said
switches includes a second pair of stationary contact assemblies
mounted on a corner portion of the front surface remote from the
confronting side and spaced from the first side of the plane, each
of said second pair of stationary contact assemblies including a
pair of metal stationary contact supports that are electrically
connected together and spaced to be alternately engaged by a
portion of the movable contact when the electromagnet is
alternately energized and deenergized.
Description
This invention relates to electromagnetic switches and is more
particularly concerned with a contactor which is particularly
suited for use in a battery operated lift truck and the like, its
use being readily apparent from the illustrated example and the
objects.
Electromagnetic contactors are conventionally designed so the size
of their current carrying parts corresponds to the magnitude of the
current the parts are expected to carry. The size of the current
carrying parts, e.g., the terminals, the movable contacts and the
stationary contacts of a contactor, together with the required
spacing between the parts, not only dictates the forces which the
movable contact springs must exert, but also dictates the forces
the magnet motor must deliver if the contactor is to provide an
acceptable number of switching operations without failure.
Contactors designed for service in battery operated lift trucks are
subject to vibration and shock, which requires that the force
exerted by the movable contact springs be sufficient to maintain
the movable contacts in tight engagement with the stationary
contacts to prevent erosion of the contacts by small arcs that
develop when the movable contacts bounce upon the stationary
contacts. Thus in contactors designed for truck service, the forces
of the contact springs and the magnet motor is not dictated by the
size of the contacts but rather by the magnitude of the shocks
which the contactor can be expected to endure so that the same size
magnet motor in a contactor for electric trucks may be used with a
range of different contacts.
The fact that the same magnet motor may be used with a range of
different sized truck contactors results in a reduction in the cost
of manufacture and inventories. The size of the contactor according
to the present invention is considerably smaller than contactors
heretofore known that have comparable current carrying
capabilities. This result is partly accomplished by incorporating a
novel plunger and movable contact support structure in the
contactor as well as other features which will be apparent from the
illustrated embodiment of the present invention and following
objects.
It is an object of the present invention to provide a contactor
with a novel movable contact support and armature wherein the
contact support is molded in situ with the armature.
Another object is to provide a compactor contactor for a battery
operated lift truck and the like which has a structure which will
permit the contactor to be mounted on a panel so the axis of
movement of a magnet plunger operator extends either perpendicular
or parallel to the panel.
A further object is to provide a contactor with a support for the
stationary contacts which includes an opening which provides a
guide for a support carrying the movable contacts of the
contactor.
An additional object is to provide a contactor with a support for
the stationary contacts which includes an opening which provides a
guide for a support carrying the movable contacts of the contactor
and to provide the contactor with a magnet structure whereon the
stationary contact support is mounted.
A still further object is to provide a contactor with a support for
the stationary contacts which includes an opening which provides a
guide for a support carrying the movable contacts of the contactor
and to provide the contactor with a magnet structure whereon the
stationary contact support is mounted and wherein the movable
contacted support is molded in situ with the plunger.
An additional object is to provide a contactor with a molded
stationary contact support which is arranged so the contactor is
easy to wire and a range of different sizes of stationary contacts
may be mounted on the support.
A further object is to provide a movable plunger and a movable
contact support in a contactor with bores that are axially aligned
and arranged to receive a piston for reducing the contact bounce of
the contactor and a movable contact guide and spring so that the
spring is isolated from the arc generating portions of the
contactor.
Further objects and features of the invention will be readily
apparent to those skilled in the art from the following
specification and from the appended drawings illustrating certain
preferred embodiments, in which:
FIG. 1 is a perspective view of a pair of contactors according to
the present invention interconnected in a reversing circuit
configuration;
FIG. 2 is a cross-sectional view taken along line 2--2 in FIG.
1;
FIG. 3 is a top plan view of one of the contactors in FIG. 1;
FIG. 4 is a top plan view of the contactor in FIG. 3 taken
generally along line 4--4 in FIG. 2;
FIG. 5 is a perspective view partly showing in cross-section a
movable contact and magnet plunger structure as used in the
contactor in FIG. 2;
FIGS. 6, 7 and 8 respectively are top, side and end views of an arc
suppressing and directing member which is positioned between the
pair of contactors in FIG. 1; and
FIG. 9 is a side view of a normally open and a normally close
stationary contact which are selectively mounted on the contactors
in FIG. 1.
Referring to the drawing, an electromagnetically operated switch or
contactor 10 includes an electromagnet assembly 12, a stationary
contact assembly 14 and a movable contact and plunger assembly 22.
The electromagnet assembly 12 includes a magnet frame assembly 18
and a coil assembly 20. The magnet frame assembly 18 is fabricated
from a low carbon steel with reasonable high permeability at low
flux densities and includes a mounting plate 24, a magnet frame 26,
a cylindrical rear magnet pole or core 28 and a front magnet pole
assembly 30. The mounting plate 24 has a base portion 32 and a
flange 34 extending along a marginal edge of the base portion 32.
The base portion 32 is provided with openings 36 at each of its
four corners and the flange 34 has openings 38 in its opposite
ends. The openings 36 and 38 are provided so that the contactor 10
may be mounted in either of two positions on a panel, not shown, by
suitable screws which are selectively received in the openings 36
or 38 and threaded into the panel. When the openings 36 are used to
secure the contactor to the panel, the contactor will be oriented
so that the axis of the plunger assembly 22 will extend normal to
the panel. When the openings 38 are utilized to secure the flange
34 to the panel, another mounting part, not shown, is provided at
the front end of the contactor so the axis of the plunger assembly
22 will be parallel to the mounting panel. For purposes of
description, the components of the contactor 10 will be described
when the base portion 32 is secured to the mounting panel by screws
extending through the openings 36.
The magnet frame 26 is cup-shaped and has a rear wall 39 secured to
the mounting plate 24 and side walls 40 extending forwardly from
the rear wall 39 to outwardly extending flanges 42 at the front
ends of the wall 40. The side walls 40 of the cup-shaped frame 26
are slotted to make the part easier to manufacture and to provide
clearance and access to a pair of terminals 46 of a coil winding 48
which is part of the coil assembly 20. The rear wall 39 and the
mounting plate 24 are provided with circular openings 50 that are
centered on the axis of the plunger assembly 22.
The core 28 has an end secured in the openings 50 and includes a
bore 54 which extends through the core 28 along the axis of the
plunger assembly 22. The front end of the bore 54 is provided with
a counterbored portion 56 that has conically tapered side walls.
The diameter of the rear end of the bore 54 is slightly reduced to
provide an annular spring seat 58. The portion of the bore 54
extending rearwardly of the spring seat 58 is also counterbored to
provide clearance for the operator of a mechanical interlock, not
shown or described herein, which may be positioned at the rear end
of the contactor 10.
The front magnet pole assembly 30 is secured to the front side of
the flanges 42 by screws 60 which extend through openings in a
front pole plate 62 into threaded openings in the flanges 42. The
front pole plate 62 is generally rectangular in shape and has a
circular central opening 63 centered on the axis of the plunger
assembly 22. Secured on the front side of the pole plate 62, as
with projection welds, is a pole plate 64. The pole plate 64 has a
central circular opening 66 centered along the axis of the plunger
assembly 22 and a pair of notches 68 extending outwardly from
opposite side walls of the opening 66. The notches 68 are arcuate
in shape and are centered in a plane defined by the axis of the
plunger assembly 22 that extends perpendicular to the panel on
which the contactor 10 is mounted. A rear side of the pole plate 64
is provided with a circular depression wherein a non-magnetic
stainless steel annular shim 70 is held captive between the pole
plates 62 and 64 when the pole plates are secured together. The
arcuate notches 68 are arranged to expose portions of the shim 70
to the front end of the magnet frame assembly 18.
The coil assembly 20 includes a molded plastic bobbin 72, a wave
washer 74, and the coil winding 48 which is random wound on the
bobbin 72 and covered with a suitable tape. The coil assembly 20 is
accurately positioned between the rear wall 39 and the pole plate
62 by projections 76 which extend from a rear end of the bobbin 72
into suitably located openings in the rear wall 39 and an annular
flange 78 which extends forwardly from the front end of the bobbin
72 into the opening 63. The bobbin 72 has a cylindrical bore 80
extending therethrough that is centered on the axis of the plunger
assembly 22. The magnet core 28 extends forwardly in the bore 80
and the plunger assembly 22 is movable and guided along its axis of
movement by the walls of the bore 80. The plunger assembly 22
includes a cylindrical plunger 82, a spring guide 84, an insulator
86, a guide pin 88 and a spring 90. Additionally, a movable contact
assembly 16 may be considered as part of the plunger assembly 22 in
view of the manner in which they are connected and cooperate, as
will be later described. As shown in FIG. 5, the cylindrical
plunger 82 has a body portion 92 which is guided in the bore 80 and
a conically tapered rear end 94 with a bore 96 extending between
the rear end 94 and a front end 98 of the plunger 82. The front end
of the bore 96 is provided with a counterbored portion which
provides a cavity 100 that has an appreciable depth and extends
rearwardly into the plunger 82. Extending outwardly at the front
end of the plunger 82 are a pair of arcuately shaped ears 102, most
clearly illustrated in FIG. 5. The ears 102 are sized to be
received in the notches 68 without engaging any side wall portion
of the notches 68.
The movable contact assembly 16 includes a molded movable contact
carrier 104, a movable contact 106, a movable contact guide 108, a
keeper 110, a washer 112 and a damper 114.
The carrier 104 is molded of insulating material in situ with the
plunger 82 and has a portion filling the cavity 100 in intimate
contact with the walls of the cavity 100 to provide a firm bond
therebetween. The carrier 104 has a bore extending forwardly from
its rear end which forms a continuation of the bore 96. A forward
end portion of the bore is slightly reduce in diameter to provide a
cylindrical bore 118 and an annular ridge 120 at the rear end of
the bore 118. Extending forwardly between the front end of the bore
118 and a front end 122 of the carrier 104 is a rectangular slot
124 which extends lengthwise along an axis that is parallel to the
panel on which the contactor 10 is mounted. The front end 122
extends in a plane that is perpendicular to the axis of movement of
the plunger assembly 22.
The insulator 86 has a cylindrical shape and is positioned in the
front end of the bore 96 against the ridge 120 to electrically
isolate the metal parts in the bore 96 from the metal parts in the
bore 118. The spring guide 84 is tubular in shape and is positioned
in the bore 96. The spring guide 84 has a closed front end
positioned against the insulator 86 and an outwardly flared rear
end which overlays the rear end of the tapered end 94. The guide
pin 88 has a head portion 126 positioned against the closed front
end of the spring guide 84 and a stem 128 extending from the head
portion 126 rearwardly through the bore 54 to the external rear of
the contactor 10. The spring 90 surrounds a portion of the stem 128
and is positioned between the head portion 126 and the spring seat
58 to constantly bias the plunger 82 forwardly in the bore 80.
The contact guide 108 is formed from a flat metal part to have a
stem portion 130 and a pair of feet 132 extending in opposite
directions at the rear end of the stem portion 130. The stem
portion 130 extends from the bore 118 through the rectangular slot
124 to provide a portion 134 at its front end that extends
forwardly of the front end 122 of the carrier 104. The portion 134
has a pair of notches 136 in its opposite sides and an opening 138
adjacent its front end. The washer 112 has a rectangular central
opening which receives the stem portion 130 while its rear surfaces
rest upon the feet 132. The damper 114 also has a rectangular
central opening and a rear surface which rests upon the front
surface of the washer 112. The damper 114 is formed of resilient
material and is disc-shaped and has a diameter which will cause the
peripheral edges of the damper 114 to frictionally engage the wall
portions of the bore 118 and move in the bore 118 with a
piston-like action. A spring 139 is positioned between the ridge
137 and the front side of the damper 114 to constantly bias the
contact guide 108 rearwardly in the carrier 104.
The movable contact 106 is formed as a rectangular part of a highly
conductive metal, e.g., copper, and has noble metal contact areas
at its opposite ends. The movable contact 106 has a central portion
positioned on the end 122 and extends along an axis parallel to the
panel on which the contactor 10 is mounted. The central portion of
the contact 106 is provided with a rectangular slot 141 through
which the portion 134 of the contact guide 108 extends. Also, the
end 122 is provided with a pair of spaced abutments 140 which are
located on opposite sides of the central portion of the movable
contact 106 to prevent the movable contact from rotating on the end
104. The movable contact 106 is maintained assembled on the end 104
of the contact guide by the keeper 110 which is formed as a channel
part to have a notch 142 extending in its bight portion which
receives a portion of the contact guide while portions of the
keeper 110 surrounding the notch 142 are received in the notches
136. The keeper 110 has a length so an edge 144 engages a wall on
one of the abutments 140 when the portions of the keeper 110 are
received in the notches 136.
The portion 146 of the contact carrier 104 that extends forwardly
of the plunger 82 is substantially rectangular in shape and is
centered along a plane perpendicular to the panel on which the
contactor 10 is mounted. The portion 146 is movable in a
rectangular bore 148 that extends through a molded insulating
support 150. The support 150 is part of the stationary contact
assembly 14 and has a rear side mounted on the front end of the
magnet frame assembly 18 by a pair of screws 152 which are received
in bores 154 in the support 150. The support 150 is generally
rectangular in shape and has a raised abutment 156 extending
forwardly at each of its four corners of its front surface. Each
abutment has a threaded metal insert 158 embedded therein.
Two different types of stationary contacts may be mounted on any of
the four abutments 156 to selectively cooperate with the movable
contact 106 to provide a normally open or normally close contact
function. As shown in FIG. 9, one of the types of stationary
contacts designated by a numeral 160 is shaped to provide a
normally closed contact function and the other type, designated by
a numeral 162, is shaped to provide a normally open contact
function.
Each of the stationary contacts 160 and 162 includes a mounting
portion which is secured to a front face of one of the abutments
156 by a terminal screw designated as 164 in FIG. 9. The terminal
screw 164 extends through an opening in the mounting portion of the
contacts 160 and 162 and is threaded into the threaded insert 158
embedded within the raised abutment 156 whereon the associated
stationary contact 160 and/or 162 is positioned. The stationary
contact 160 includes a portion 166 that has a noble metal contact
170 secured thereon. The portion 166 extends from the abutment 156
whereon the contact 160 is secured to position the contact 170 so
that the contact 170 is centered along an axis that extends
perpendicular to the axis of movement of the plunger 82 and is
spaced equidistantly between a pair of adjacent abutments 156 at
the upper corners of the support 150 and a pair of adjacent
abutments 156 at the lower front corners of the support 150. The
portion 166 extends from its associated abutment 156 to position
the contact 170 so that the contact faces and is spaced from a
front surface portion 172 that extends on the front side of the
support 150 between the pair of adjacent abutments 156 at the top
edge of the support 150 and the pair of adjacent abutments 156 at
the bottom edge of the support 150. The normally open stationary
contact 162 includes a portion 174 that has a noble metal contact
176 secured thereon. The portion 174 extends from its associated
abutment 156 so that the contact 176 is positioned adjacent the
front surface portion 172 and faces forwardly with the contact 176
centered along an axis which is parallel to the axis which passes
through the center of the contacts 170 and equidistantly spaced
between the abutments 156 at the upper and lower corners of the
support 150.
The stationary contacts 160 and 162 are selectively positionable on
the front surface of the support 150 to provide a normally open
contact function, a normally close contact function, or a normally
open and a normally close contact function, providing a pair of the
same type of closed contacts, e.g., a pair of contacts 160 or a
pair of contacts 162, are selectively positioned on an adjacent
pair of abutments at either the top or the bottom edges of the
support 150. This arrangement will permit the movable contact 106,
which is rectangular in shape and movable in a plane passing
through the axes which passes through the centers of the contacts
170 and the contacts 176, the present noble metal contact portions
178 which are engageable with the contacts 170 and noble metal
contact portions 180 which are engageable with the contacts 176,
respectively, when the coil assembly 20 is respectively
de-energized and energized.
The contactor 10 is assembled by securing the mounting plate 24,
the magnet frame 26 and the magnet core 28 together and positioning
the coil assembly 20 within the mounting frame 26 so that the core
28 extends forwardly in the rear end of the bore 80 and the
terminals 46 are exposed through openings in the frame 26. The wave
washer 74 is then positioned on the front end of the coil assembly
20 and an assembly consisting of pole plate 62, the pole plate 64,
and the shim 70 is secured to the front end of the magnet frame
assembly 18 by the screws 60. The plunger assembly 22 is then
positioned within the bore 80 so that the ears 102 are aligned to
be received within the notches 68. The stationary contact support
150 when secured to the front end of the pole plate 64 by screws
152 will be in a position which will cause the rectangularly shaped
portion 146 of the contact carrier 104 to be received in the
rectangular bore 148 in the support 150. The rectangular bore 148
provides a guide for the movement of the contact carrier 104 and
prevents the contact carrier 104 and the plunger 82 from rotating.
If the contactor 10 is to provide a normally open type contact
switching function, the contacts 162 are secured on the abutment
156 as previously described before the movable contact 106 is
assembled on the front end 122 of the movable contact carrier 104.
If the contactor 10 is to provide a normally closed type of contact
switching function, the movable contact 106 is positioned on the
front end 122 before the contacts 160 are secured on the support
150 as described.
The movable contact 106 is installed on the front end 122 of the
carrier 104 by positioning the movable contact between the
abutments 140 on the front end 122 with the portion 134 on the
movable contact guide 108 extending through the rectangular slot
141 in the movable contact 106. The keeper 110 then is assembled on
the portion 134 with the aid of a pointed tool, such as a punch,
which has its point installed in the opening 138 and its shank
fulcrummed on one of the abutments 140 so the tool can be pivoted
on the abutment and cause the contact guide 108 to move against the
force of the spring 139 so that the notches 136 will be exposed at
the front side of the movable contact 106. The exposed notches 136
will permit the keeper 110 to be moved into a position where it
will maintain the movable contact 106 in its position on the end
122. It is readily apparent that the movable contact 106 may be
readily removed from the end 122 by merely lifting the side of the
keeper 110 that is remote from the notch 142 and sliding the keeper
110 out of engagement with the portion 134.
As shown in FIG. 2, the rear side of the support 150 is provided
with a recess 182 which receives the front end of the plunger 82,
including the ears 102. The front end of the recess 182 is provided
with stop surfaces 184 which are engaged by portions of the ears
102 to limit the forward movement of the plunger assembly 22 when
the contactor 10 is de-energized and the contactor 10 is not
provided with normally closed stationary contacts 160. When the
contactor 10 is furnished with a pair of normally closed type
stationary contacts 160 and the contactor 10 is de-energized, the
movable contact assembly 16 will be urged forwardly by the spring
90 so that the contacts 178 will be pressed into tight engagement
with the contact 170 and cause a slight spacing to be present
between the ears 102 and the stop surface 184.
The coil winding 48, when energized by direct current, will cause
the contactor 10 to be energized and the plunger 82 and the contact
carrier 104 to move rearwardly toward the core 28 against the force
provided by the spring 90. The movement of the plunger 82 is guided
by the bore 80 and limited by the engagement between the rear side
of the ears 102 and the front exposed surface portions of the
non-magnetic shim 70. The rectangular bore 148 and the portion 146
are arranged so that the ears 102 are prevented from engaging any
portions of the notches 68. The movement of the contact carrier 104
will cause the movable contact 106 to move out of engagement with
the stationary contacts 160 and into engagement with the stationary
contacts 162. The movement of the contact carrier 104 rearwardly
toward the energized position where the ears 102 engage the shim 70
will cause the contact portions 180 to engage the contacts 176
prior to the engagement between the ears 102 and the shim 70 so
that the movable contact 106 moves out of its engagement with the
end 122. The movement of the movable contact 106 from the end 122
is opposed by the spring 139 which provides a force through the
contact guide 108 and causes the contact portions 180 to be pressed
firmly against the contacts 176.
Any contact bounce which normally would occur when the contact
portions 180 engage the contacts 176 is reduced to a minimum by the
friction between the peripheral edges of the damper 114 and the
walls of the bore 118 as the damper 114 moves in the bore 118.
The de-energization of the coil winding 48 will cause the contactor
10 to be de-energized and the plunger 82 and the movable contact
carrier 104 to move to the de-energized position previously
described. The engagement between the ears 102 and the shim 70
prevents the plunger 82 from being maintained in its energized
position by residual magnetism which would normally occur if the
shim 70 was made of magnetic metal. The force provided by the
spring 90 on the plunger 82 causes the plunger 82 and the movable
contact carrier 104 to move from an energized position to a
de-energized position where the contact portions 178 engage and are
firmly pressed against the contacts 170 by the force exerted by the
spring 90.
An advantage provided by the construction of the movable contact
assembly 16 is that the spring 139 is isolated and shielded from
high temperature exposure which is generated by arcs during the
operation of the contactor 10. The springs 139 thus will suffer no
loss in elastic modulus and will not require replacement when the
movable contacts 106 are replaced. The insulator 86 is included in
the contactor 10 to electrically isolate the movable contact
structure that includes the guide 108 from the panel on which the
contactor 10 is mounted.
A pair of contactors 10, designated as A and B, are shown in FIG. 1
as connected to control the energization of a series field direct
current motor reversing circuit. The connection between the pair of
contactors A and B is accomplished by a pair of identical
triangularly shaped metal conductor members 186 and 188 which
properly space the pair of contactors A and B and cause the arcs
generated by the switching contacts of the contactors A and B to be
properly directed. The members 186 and 188 also provide a support
for an arc directing chute member 190 as will be later
described.
The members 186 and 188 generally have an isosceles triangle shape
and each has a base b spaced and parallel to a plane passing
through the axis of movement of the plunger assemblies 22 of a pair
of contactors A and B. The sides of each member 186 and 188 extend
from the base b of the members to an apex 191 which is located in a
plane perpendicular to the base b and parallel and equidistant to
the axis of movement of the plunger assemblies 22 of the pair of
contactors A and B. The members 186 and 188 have openings 192 and
194 located adjacent their respective apices 191 with the openings
192 and 194 centered along an axis through the apices 191 of the
members 186 and 188. The members 186 and 188 also have a pair of
openings at the opposite ends of their respective bases b which are
arranged to receive screws which are threaded into the abutments of
the contactors A and B. Each member 186 and 188 is also provided
with a threaded opening 196. The openings 196 in the respective
members 186 and 188 are centered along an axis through the center
of the openings 192 and 194 and are located adjacent the base b of
the respective members 186 and 188.
The member 186 is secured to the contactors A and B by terminal
screws which also mount the contacts 160 and/or 162 on the
abutments 156 and on the contactors A and B respectively designated
as 164A and 164B. Similarly, the member 188 is secured to the
contactors A and B by terminal screws designated as 164C and 164D.
The members 186 and 188, when secured to the contactors A and B by
the terminal screws 164A-D, space the contactors equidistantly a
predetermined distance on opposite sides of a plane passing through
the centers of the openings 192 and 194 so that a space is provided
between the confronting adjacent side walls of the supports 150 of
the contactors A and B.
The member 190 is positioned between the contactors A and B by the
members 186 and 188. The member 190 is formed of a cold-molded,
non-tracking, arc-suppressing and quenching material as is well
known to those skilled in the art. The member 190 has a web portion
198 extending in the plane which is equidistant from the contactors
A and B. As shown in FIGS. 6-8, the web portion 198 interconnects a
pair of mounting portions 200 and 202. The mounting portions 200
and 202 are positioned adjacent the rear sides of the members 186
and 188 and are secured to the members 186 and 188 by screws which
pass through suitably located openings 204 in the mounting portions
200 and 202 and are threaded into the openings 196 in the members
186 and 188 respectively. The web portion 198 extends from a front
end 206 rearwardly to a rear end 208 and preferably is tapered so
that front end 206 has a greater thickness than the rear end 208.
Extending rearwardly from opposite sides of an upper end of the web
portion 198 is a rib 210. The rib 210 extends from the front end of
the web portion 198 rearwardly to provide openings 212 on opposite
sides of rear bottom edge of the web portion 198. Extending
rearwardly from opposite sides of a lower end from the front end to
the openings 212 in a rib 214. All of the corners between the ribs
210 and 214 and the web portion 198 are rounded in a manner most
clearly seen in FIG. 6.
When a pair of contactors A and B are constructed and
interconnected by a pair of members 186 and 188 so the contactors A
and B may be connected in reversing circuit for a series field
direct current motor, not shown, one side of a D.C. source, not
shown, is connected by a suitable terminal and screw, not shown,
which is threaded into the opening 194 and the other side of the
source is connected through the armature winding of the motor to a
terminal and a screw which is threaded into the opening 192.
Secured on the abutment 156 at the lower right corner of the
support 150 of the contactor B by a terminal screw designated as
164E is a normally closed stationary contact 160 and a normally
open stationary contact 162. Similarly secured to the abutment at
the lower left corner of the support 150 of the contactor A by a
terminal screw 164F is a normally closed stationary contact 160 and
a normally open stationary contact 162. A pair of normally closed
stationary contacts 160 are secured to the upper right and upper
left abutments 156 of contactors A and B respectively by the
terminal screws 164C and 164D respectively, which also secure the
member 188. Secured to the lower right and left abutments 156 of
the contactors A and B respectively by terminal screws 164A and
164B are a pair of normally open stationary contacts 162, not
shown.
Preferably, the contactors A and B are mechanically interlocked by
a mechanism, not shown, which is mounted at the rear of the
contactors A and B and actuated by the rear ends of the guide pins
88 so the contactors A and B are incapable of simultaneously being
in their energized or de-energized states. When the contactors A
and B are connected in the reversing circuit for a series field
direct current motor, the terminal screws 164F and 164E are
connected to opposite ends of the field winding.
When the contactor A is energized and the contactor B is
de-energized, the movable contact 106 of contactor A will interrupt
the circuit between the terminal screws 164C and 164F and complete
the circuit between the terminal screws 164F and 164A while the
movable contact 106 of the contactor B will cause the circuit
between the terminal screws 164D and 164E to be completed and the
circuit between the terminal screws 164E and 164B to be
interrupted. The completed circuit between the terminal screws 164F
and 164A will cause current to flow through the normally closed
contacts 160 of the contactor B and the normally open contacts of
the contactor A so that the motor field is energized by current
flow in one direction. For example, current from a D.C. source
which is connected by suitable conductors and screws which are
threaded into the openings 194 and 192 in a direction which will
casue current to flow from the opening 194 to the opening 192, will
flow through a path that includes the opening 194, the terminal
screw 164D, the normally closed contacts 160 of the contactor B,
the terminal screw 164E, the field of the motor, the terminal screw
164F, the normally open contacts 162 of the energized contactor A,
the terminal screw 164A and the opening 192.
A severe arc may be generated between the contacts 180 and 176 of
the contactor A when the contactor A is initially deenergized. The
hot gases generated by the arc are directed downwardly and
outwardly by the arc chute 190.
The current interrupting capability of the contactors A and B is
appreciably increased by the presence of the arc chute 190 and the
members 186 and 188 in the assembly. It will be seen that the arc
chute 190 provides a barrier between the contactors A and B reduces
the possibility of hot ionized gases from being transferred from
the contacts associated with the terminal screws 164A and 164C of
the contactor A to the space between the contacts associated with
the terminal screws 164B and 164D of the contactor B when the
contactor A is initially de-energized. The presence of hot ionized
gases in the space between the contacts associated with the
terminal screws 164B and 164D may cause a line-to-line short
circuit between the conductors which are connected to the openings
192 and 194. The members 186 and 188 aid in the effectiveness of
the arc chute 190. In practices heretofore used, the members 186
and 188 would be in the form of a flat strip of conductive metal
and the connections to the source would be made to one of the
terminal screws, e.g., terminal screw 164D, with the strap
providing the connection to the terminal screw 164C. When this
arrangement is used, the magnetic field generated by the current
flow when contactor A is interrupting current flow will cause the
arcs generated between the movable contacts associated with the
terminal screws 164A and 164C to strike the arc chute 190 at a
90.degree. angle and thus reduce the effectiveness of the web
portion 198 from directing the hot ionized gases away from the
opening contacts. The same result will occur when the contactor B
is initially de-energized to interrupt the circuit through its
contacts and the connection from the source is made to the terminal
screw 164C. The connections provided by the openings 192 and 194 at
a point equidistant between and remote from the terminal screws
164C-164D and 164A-164B respectively, causes the magnetic field
generated by currents through the contactors A and B to be
distributed so that arcs generated when the contacts of contactors
A and B open will strike the web portion at an angle which aids the
arc chute in directing the hot gases downwardly and forwardly
through the openings 212. The taper on the web portion 198 also
increases the efficiency of the arc chute 190.
The operation of the contactor B when the contactor B is energized
and de-energized is believed obvious in view of the foregoing
description of the operation and arcs generated when contactor A is
energized and de-energized. The only difference between the
operation of the contactor A and B is that the energization of the
contactor B will cause the direction of current flow through the
field of the motor to be in the opposite direction from the current
flow when contactor A is energized.
While certain preferred embodiments of the invention have been
specifically disclosed, it is understood that the invention is not
limited thereto, as many variations will be readily apparent to
those skilled in the art and the invention is to be given its
broadest possible interpretation within the terms of the following
claims.
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