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Патент USA US2127083

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Aug. 16, 1938.
I
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'
’
K. HOWE ‘
RHEOSTAT
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Filed Nov. 13, 1935
.24
2,127,083
2 Sheets-Sheet 1
A ‘ATTORNEY \
2
2,127,083
On the inner face of the plate I and surround~
ing the bearing and engaging the flange Ilia is an
insulating disk I2. The outer portion and rear
5
face of this disk is cut away to form a seat for
a metal collector ring l3 which has a strip 130,
extending outwardly therefrom to a terminal
connection 80. mounted in the terminal block 1. A
conducting wire or strip i3b connects the termi
nal 8a to one of the terminals 6, as shown
in Fig. 1, for use as a series connected rheostat.
The rheostat is readily adapted for use as a
potentiometer by omitting the conducting strip
. I31; and replacing the terminal connection to by
a third terminal like the terminals 6.
The contact arm Id of the rheostat is in the
24
form of a flat plate having outwardly bent sides.
Lda and has a large central opening to receive
an insulating block l5 which is located between
the sides Ila of the contact arm. The block if:
has an inwardly projecting circular portion
which projects within the central opening of the
contact arm and this inwardly projecting por
tion i5a of the block is cut with concentric spaces
as indicated in Fig. 2 for increasing the surface
leakage distance. A lug Hb is upset from a
central portion of the contact arm and engages
a hole in the inner face of the block IS. The
insulating block and contact arm are thus held
in fixed relationship to each other, by the side
portions Ila which embrace the sides of the block
and the lug Nb which prevents relative longi
tudinal movement. The contact arm extends
outwardly at one end and has a depressed por
tion Me for engaging the series of contacts 3
successively as the arm is turned. The opposite
end of the contact arm has another depressed
portion lld as shown in Fig. 2 which engages the
collector ring I! on the opposite side of the shaft
from the engagement of the other end of the
contact arm which engages the contacts 3. The
contact arm is rigid throughout all parts and
of good conductive material such as hard cop
per. In rheostats,. where double concentric, rows
of resistor contacts I are used, the contact arm
may have depressed portions He at its opposite
ends for engaging the two series of contacts.
The central portion of the insulating block I5
is provided with an enlarged circular cavity in
which is seated a spiral spring i6 which encircles
the bushing It and serves to impose pressure to
force the block l5 and contact arm inwardly so
that the contact arm always engages the con
tacts 3 and the collector ring i3 with su?lcient
pressure to maintain a desirable electrical con
tact at all times and in all positions.
The spring
is thus insulated in such a way that it cannot
carry current and by reason thereof it is not sub
jected to heating currents which might reduce its
tensionr Moreover, by reason of the contact am
60 making engagement with contacts at its opposite
ends and by reason of receiving the spring pres
sure at its central portion, the pressure imposed
upon the contacting portions is always balanced
and approximately equalized in any position of
- the contact arm.
In cases where the contact
arm has oppositely extending portions of pro
nounced difference in length, thespring ii, in
stead of encircling the shaft. may be located to
one side thereof and thereby apply the spring
pressure to a more central portion of the con
tact arm. Also, the spring may be of other form‘
than spiral and supported in any suitable man
ner.
.
The shaft ll of the rheostat extends through
the bushing and is threaded at its opposite ends
as shown in Figs.'2 and 4 and is likewise slotted
at its opposite ends for providing a locking en~
gagement of the parts without the necessity of
usingset screws. For the purpose of holding
the spring IS in position and imposing pressure
‘thereon and for locking the movable contact
arm and block IE to the shaft, a perforated plate
i8 is slid over the inner end of the shaft and
seats itself against the spring and between two
outwardly extending side portions i5b of the ill
insulating block.
The plate l8 has two inwardly v
projecting lugs I'o‘a on opposite sides of its cen
tral opening which project into the slot at the
end of the shafti'i. Thus the plate i8 is locked
to the shaft which plate in turn locks the in
sulating block and the contact arm to the shaft.
Turning of, the shaft will therefore result in
turning the contact arm to any position desired.
A washer is having lugs I9a which project into
the slot in the end of the shaft, is located on the
outer face of the plate 18 and the parts are locked
in position by the end nut 20 on the inner end
of the operating shaft. The use of set screws is
thus avoided and also the ?xed position of the
contact arm and insulating block in relation to
the operating shaft is insured and maintained
without any chance of the parts working loose.
A sheet metal cover plate 20, which may some
times be in the form of a skeletonized frame, is
mounted on the back of the rheostat and has 30
an inwardly bent rim 20a which is offset at 20b
and fits within the rim la of the main rheostat
plate and is cut away to fit over and bent to
partially cover the terminal block ‘i. A saddle 2_i
with inward projections at its ends, embraces the 35
rim of the plate i and the offset portion 20b of
the cover plate and is held in place by a screw
22 which has a threaded engagement with the
rim of the plate I. Any number of these clips
or clamps may be used, three being shown in the
drawings spaced apart from each other around
the periphery of the rheostat, for holding the
cover in place; and supporting feet 23 may also
be used as desired for mounting ‘the rheostat in
place. These supports 23 may be held in place
by the screws 22 on the outside of the saddles
2|, the saddles 2| being provided with outwardly
extending bent edges 2la for maintaining the
supports 23 in fixed position in relation thereto.
The supports for the rheostat may be variously 50
arranged to suit the particular requirements and
may readily be mounted in multiple and like
wise the shafts in a number of rheostats may be
coupled together for multiple control.
The cover plate 20 has a series of separated cir
cular slots 200, as shown in Fig. 3 and on the
inside of the cover plate is another circular plate
"(I which is rotatably secured to the cover plate
20 by aneyelet 208. The plate 20d is large
enough to extend beyond the holes 200 of the 60
cover and affords means ‘for providing an ad
justable stop for the contact arm at any desired
intermediate position.
A screw 20f passes through any desired one 01'
the openings 20c and through the plate 20d and 65
engages a U-shaped angle piece 200, as shown in
Figs. 2 and 3. By loosing the screw 20! the posi~ ‘
tion of this angle piece may be adjusted as de
sired through the range of any one slot 20c and
by transferring the screw to another slot 200, 70
the range of adjustment may be extended to any
portion of the cover plate. The plate 18 is pro
vided with an extension "b at one end and has
an outwardly.v bent end Hie-which is adapted to
engage thestop 20a in its adjusted position. This 75
am'noss
auxiliary stop is desirable in cases where a pre
determined lirnit of adjustment is ?xed for the
control of any particular apparatus and the stop
200 is adjusted to such position that the arm no
will engage the same at the limiting predeter
mined position. In order to obtain continuous
adjustment of the stop 20g over all portions of
the contact arm travel, the piece 200 is provided
with two circumferentially spaced tapped holes
10 20h for receiving the screw 20/.” when the limit
of adjustment in one of the slots No is reached,
the screw "I may be transferred to the other
hole ilhiwhich permits adjustment throughout
the space occupied by the portions of the cover
3
ing shaft when adjusting the rheostat to different
positions, the‘application of such force is applied
to the shaft at a portion'immediately adjacent
to the pointer or "disk 24, and when the latter.
strikes the stop lb on either side thereof, there 5
are no undue strains imposed upon the operating
parts because the stop acts to oppose further
movementof the shaft beyond its limiting posi
tions in substantially the same plane as the ap
plication of the force for turning the shaft. It
is apparent that the operating parts of the rheo
stat may be quickly and conveniently assembled
and disassembled owing to the simplicity of rela
tionship and relatively small number. of parts.
20 between the slots "c. The U-shaped piece I It is also evident that the structure is sturdy and
209' may also be utilized for locking the contact dependable in long continued use without like
arm assembly in any ?xed position desired. The lihood of the parts working loose or being dis
Li-shaped piece 2001s of such dimensions that its placed from their proper relative positions. Also,
extending portions may embrace the projection by reason of the rigid structure of the contact
arm throughout and its balanced application of 20
20 Me of the plate II. For locking the parts in any
15
desired fixed position of ‘ adjustment. the U
contact pressure, the maintenance of good elec- .
shaped piece is placed to enclose projection lie
and the U-shaped piece is then fastened by its
trical contact at all times and in all positions of
screw 20! to remain in any desired position.
The operating handle and the part which 120-‘
Although a preferred form of the invention
has been described, the same may be applied in 25
operates with the main stop lb for limiting the
rotation of the operating shaft at the resistance
all out position and the resistance all in position,
are mounted on the front end of the operating
30 shaft close to each other. In front of the washer
9 on the shaft I1 is mounted a thrust washer 9b,
the rheostat is assured. ‘
various features thereof to other forms of rheo- .
stats than the particular type shown, and-to a
wide range of rheostats of different capacities;
also various modifications may be made therein
without departing from the scope of the inven 80
tion.
a
The invention claimed is:
as shown in Figs. 2 and _4. In front of this wash
er is mounted a plate 24 having a pointer 24a.
1. A rheostat comprising a rotatable shaft, a
contact arm operated by said shaft, 8. stop mount
'Iv'his pointer also serves the function of coop
erating with the main stop lb at the extreme lim
ed on the‘ face of the rheostat, a pointer having
iting positions of the contact arm. Within the a portion“ extending within an opening of said
central opening of this plate or pointer projects shaft and adapted to engage said stop, a plate
having a portion extending within an opening of
a pair of oppositely disposed lugs 24b which en
gage the slot in the front end oi’ the operating said shaft andhaving oppositely bent portions,
operating means for rotating said shaft mounted
40 shaft i'l. Thus there is no opportunity for this
pointer to work loose or change its position rel ‘on said oppositely bent portions and spaced
atively to the shaft i1.
’
thereby from the end of said shaft, and means
In front of the pointer on the shaft is mounted for holding said pointer and said plate in posi
'
a metal strip or yoke 25 which extends across the tion on said shaft.
2. A rheostat comprising a plate, a rotatable
face of the plate 24 and fits over the shaft and
is provided with a pair of lugs Zia which extend . shaft, a contact arm operated by said shaft, a
into the slot at the front end of the operating stop disc having a portion encircling said shaft
and located on the front of the plate of the
shaft. It is thus locked to the shaft and main
tained in position relatively thereto. The strip rheostat, and a bearing sleeve for the shaft ex
25 is bent forwardly at its ends and again bent tending through the plate of the rheostat and
inwardly at its ends to form can 251; as shown having a‘ ?ange engaging one side of the plate
in Fig. 4. A nut 20 is screwed on the front end of the rheostat and also having a portion bent
of the shaft I‘! to hold the parts in position on over and in front of said encircling portion of
the shaft as regards any longitudinal movement the stop disc for holding said sleeve in fixed posi
tion on said plate and for likewise holding said
thereon. The handle 21 is of a general cylin
drical form with scored out central portion. It stop disc in fixed position with reference to said,
plate.
.
is provided with a pair of longitudinally extend
3. A rheostat comprising a plate carrying‘hxed
lng holes at opposite sides through which extend
hexagonal rods 20. The inner ends of these ' contacts, a sleeve ?xed to said plate, a shaft jour
60 rods have reduced portions Ila which are' nalied in said sleeve, an insulating block rotat
threaded and engage threaded holes in the ears ably and slidably mounted'on said sleeve, a rigid
25b. When these rods are screwed into place as contact arm coupled with said block and rotat
shown in Fig. 4, the shoulders of the rods at the ably driven by said block, a plate fixed to said
threaded ends seat against the faces of the ears shaft to turn therewith, said last named plate
,' Zilb and thus form rigid supports for securing the having a locking driving connection with said
handle in fixed position. The outer ends of these . block for rotating the same while permitting
rods have threaded openings which are engaged relative axial movement‘ thereof, and a spring
by screw bolts 29. A circular, face plate or name
plate 3| covers the main portion of the outer
70 end of the handle 21 and is located between the
35
40
45
60
‘
55
60
65
seated be ween said block and said last named
plate to c use said block to impose pressure'on
saidarmtomaintainsaidarmincontactwith
head of the screw bolts 2| and the outer ends of - said ?xed contacts.’
'
the rods 2: and thus serves to hold the. handle
4. YA rheostat comm an“, H i I
in fixed position on the yoke v2i.
contacts, a sleeve fixed to said plate, a'shaft jour
c In operation it will be evident am when‘ force ' nallcd in said sleeve, an insulating block rotatably
75 is applied to the yoke II for turning the operat
and 's‘lidably mounted on said sleeve, a rigid con‘ 75
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4
2,127,083
tact arm coupled with said block and rotatably
driven by said block, a plate ?xed to said shaft
to turn therewith, said last named plate having
a locking driving connection with said block for
rotating the same while permitting relative axial
movement thereof, said block having a central
recess formed in the rear face thereof, and a
spring between said last named plate and said
block and seated in said recess to cause said
10 block to impose pressure onsaid arm to hold
said arm in contact with said ?xed contacts. I
sure on said arm to maintain said arm in con-
tact with said ?xed contact.
3. A rheostat comprising a plate carrying ?xed
contacts, a sleeve ?xed to said plate, a shalt
journalied in said sleeve, an insulating block ro
tatabiy and slidably mounted on said sleeve, a
rigid contact arm coupled with said block and
rotatably driven by said block, a plate fixed to
said shaft to turn therewith, said last named
plate having a locking driving connection with
said block for rotating the same while permit~
5. A rheostat comprising a plate carrying ?xed ting relative axial movement thereof, a spring
contacts, a sleeve ?xed to said plate, a shaft Jour
seated between said block and said last named
nalled in said sleeve, an insulating block rotat
plate to cause said block to impose pressure on
15 ably and slidably mounted on said sleeve, a rigid said arm to maintain said arm in contact with
contact arm coupled with said block and rotat~ said ?xed contacts, and a cover for the rheostat.
ably driven by said block and having a central said cover having a projecting stop and said last
aperture of a size to prevent contact with said named plate being adapted to engage said stop
sleeve, said block having a channel formed across to limit the movement of said arm.
the rear face thereof, a plate ?xed to said shaft
9. A rheostat comprising a plate carrying ?xed
to turn therewith and ?tting in said channel to contacts, a sleeve ?xed to said plate, a shaft 20
cause rotation of said block and arm, said chan
journalled ‘in said sleeve, an insulating block
nel being su?icientlv deep to permit axial move
rotatably and slidably mounted on said‘sleeve.
ment of said block with respect to said last a rigid contact arm coupled with said block and
25 named plate, and a spring seated between said rotatably driven by said block, a plate ?xed to
last named plate and said block to cause said said shaft to turn therewith, said last named 25
block to impose pressure on‘ said arm to maintain plate having a locking driving connection with
said arm in contact with said ?xed contacts.
said block for rotating the same while permit
6. A rheostat comprising a plate carrying ?xed ting relative axial movement thereof, a spring
contacts, a sleeve ?xed to said plate, a shaft Jour
seated between said block and said last named 30
nalled in said sleeve, an insulating block rotat
plate to cause said block to impose pressure on
ably and slidably mounted on said sleeve, a rigid said arm to maintain said arm in contact with
contact arm coupled with said block and rotat
said ?xed contacts, a cover for the rheostat, and
ably driven by said block and havingv a central an inwardly projecting stop mounted on the in
aperture of a size to prevent contact with said ner face of said cover and adjustable circum
sleeve, said block having a channel formed across ferentially, said last named plate being adapted 35
the rear face thereof, a plate ?xed to said shaft to engage said stop to limit the movement of
to turn therewith and ?tting in said channel to said arm.
,
cause rotation of said block and arm, said chan
10. A rheostat comprising a plate carrying
nel being su?iciently deep to permit axial move
?xed, contacts, a sleeve ?xed to said plate, a
ment of said block with respect to said last named ' shaft Journalled in said sleeve, an insulating 40
plate, said block having a central recess on the block rotatably and slidably mounted on said
rear face thereof, and a spring between said sleeve, a rigid contact arm coupled with said
block and said last named plate and seated in block and rotatably driven by said block, a plate
46 said recess to cause said block to impose pressure ?xed to said shaft to turn therewith, said last
on said arm to hold the said arm in contact with named plate having a locking driving connec
said ?xed contacts.
,
tion with said block for rotating the same while
'I. A rheostat comprising a plate carrying ?xed permitting relative axial movement thereof, a
contacts. a sleeve ?xed to said plate, a shaft spring seated between said block and said last
60 Journalled in said sleeve, an insulating block ro
named plate to cause said block to impose pres
tatably and slidably mounted on said sleeve, a sure on said arm to maintain said arm in contact
rigid contact arm coupled with said block and with said ?xed contacts, a cover for the rheo
rotatably driven by said block, said contact arm stat, a member ‘having an inwardly projecting
extending to engage contacts on opposite sides stop mounted on the inner face of said cover,
of said shaft, a plate ?xed to said shaft to turn and means for adjusting said member circum
ferentially comprising setting means carried by
therewith, said last named plate having a lock
said member and extending through an arcuate
ing driving connection with said block permit
slot in said cover, said last named plate being
ting relative axial- movement thereof, and a adapted
to engage said stop to limit the move
60 spring seated between said block and said last ment of said arm.
named plate to cause said block to impose pres
KASSON HOWE.
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