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Патент USA US2405774

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Aug. 13‚ 1946-
c. A.BLAKESLEE
‘
2‚4'05‚774
CONTROL APPARATUS
Filed Jan. 11, 1944
IN VEN TOR.
Patented Aug. I3, 1946
2‚405,774
UNITED STATES/ PATENT OFFICE
2‚405‚774
CONTROL APPARA'I‘US
Clinton A. Blakeslee, Waterbury, Conn., assignor
to The Bristol Company, Waterbury, Conn., a
corporation of Connecticut
Application January 11, 1944, Serial N0. 517,808
19 Cla‚ims. (GI. 172-—239)
1
2
This invention relates to automatic control
mechanisms, and more especially I;o a device
wherein the control point of a regulating mecha
nism operated by a measuring Instrument of the
self-balancing potentiometer dass may readily
junction with control systems to which Ishis in
vention is especially applicable.
The single ?gure of the drawing represents
an embodiment of the invention whereby an
electrically-operated valve may be operatively
be adjusted through a wide range and use of a
associated with a temperature-measuring in
high degree of precision. In U. S. Letters Patent
N0. 2‚326‚238, granted I;o A. R. Mabey, August 10,
strument of the potentiometer dass.
Referring ‚now to the drawing:
v
The numeral III designates a furnace, oven, 01‘
1943, ‘obere is disclosed a method whereby a
pneumatic control device may effectively be ren 10 other enclosed spa.ce adapted to be heated by
the combustion 0f ?uid fue1 admitted thereto
dered subject 120 a. recording instrument of the
through a burner II, and in which it is desired
potentiometer dass having a chart With rec
to maintain a predetermined constan’ß tempera
tangular coordinates. The present invention in
ture as measured by a thermocouple I2 located
vo1ves the application 015 a differentia] principle
to the actuation of a control device from a. seli 15 Within the furnace, the regulation of said. tem
balancing Instrument having circular coordi
nates; and while it is applicable 120 other forms
perature being effected by control of the posi
tion of a valve I3 connected in a conduit I4
through which said fuel is supplied 130 the burner
from a source I5. The va1ve I3 is actuated by
trol system wherein modulation is e?ected by
varying I;he condition of an electri_cal circuit.
20 a reversible electric motor I'I having three ter—
minals I8, I9, and 20. rEhe internal connections
It is an object of this invention to provide a
of the motor are made such that When voltage
di?erential control mechanism readily adaptable
from. a suitable source is applied to the termi
I:o coordination with a self-balancing measuring
0f control, is especially adapted for use in a cou
nals I8 and I9 the motor will rotate in a sense
‘
II: is a further object 130 provide such a, mecha 25 120 close the valve I3, and when said voltage is
applied 110 the terminals 20 and I9 the motor
nism in a form which sha11 be inherently free
will operate in a sense to open said va1ve. A
of backlash between the control and actuated
slide-wire rheostat 2I, having terminals 22 and
elements.
23 is operatively engaged by a sliding contact
It is a further object to provide such a mecha
nism in a form especially adaptable to modulated 30 24 attached to the mechanism 0f the valve I3
and moved therewith by I:he motor I'I in a sense
regulation of the electrical type.
that as said valve is moved toward a closed po
II; is a further object ‘so provide such a. mecha
sition the contact approaches the terminal 22
nism in a form which sha1l be readily adjustable
and as said valve is opened the contact ap
to any desired control point, and Which shall
show a. consistent performance at all settings.
35 proaches the terminal 23.
Mounted upon a base-plate 25 is a circular
In carrying out the purposes of the invention
slide wire structure 2G, electrically engaged by
it is proposed to provide a measuring and con
a movable contact or slider 2'I, carried. by an
trolling Instrument having two identical cam
arm 28, which in turn is attached to a rotatable
members movable by the measuring element; and
the setting mechanism respectively, said cam 40 shaft 29 passing centrally through the slide—wire
structure 26 and journaled in the base-plate 25,
members being mutually disposed in a manner
whereby, with rotation of the shaft 29 the contact
110 act joint1y upon a di?erential mechanism
21 may traverse the length of the s1ide wire. For
which is simultaneously in engagement with their
purposes of clarity in the drawing, the active
respective peripheral surfaces. The degree of
actsivity of the controlling mechanism is made re 45 length of the slide-wire is shown as occupying
a comparatively small portion of I:he periphery of
sponsive to the displacement of said di?erential
the structure; but it Will be understood that its
mechanism as produced by the relative position
active length may be increased as desired in
ing of said cam members. The element of the
practice. The slide wire 26 forms a part of a
contro1 mechanism which is directly in engage
ment with the differential mechanism preferably 50 conventional potentiometer circuit, including a
battery 30 adapted to app1y a constant potential
takes the form of a slide-wire rheostat forming
to ‘ehe slide-wire terminals, and a contact-mak
a part of a bridge circuit; and I:o this circuit may
instrument.
ing galvanometer 3I. The thermocouple I2 is
be applied various compensating and anticipatory
devices which, while not forming parts of the
connected between a terminal of slide wire 26
presentinvention, are sometimes desirable in cou 55 and the galvanometer 3I; and the electrical ar
2‘,405,9741
3
4
rangement of the network is made such that by
traversely from, the shaft 59 is a cross-arm 60,
movmg the siiaer 271 with respect to the slide
wire
there may be obtained a condition of bal
ance as cletected. 'oy the galvanometer 3 l, Where
in the p0s1t1on 0I' the slider With respect to the
slide-wire becomes a measure of tne poteninal
existing between the terminals of the thermocou
ple E2, ancl therei'ore oi‘ the temperature to Whi0h
carrying on its extremities cam-followers or roll
ers öl and. 62 engaging the peripheries of the
Cams 55 and 56 respectively.
Extending from the rocker arm structure 58
in a sense substantially perpendicular to the pro
jection 58’ is a bracket 65 carrying on its ex
tremity a slide-Wim resistance EG. Fixen‘. to the
shaft or spinolle 59‚ and. de?eetable therevvith, is
n; is exposed;
Rotation of the shaft 29 is’ effected through 10 an extencled arm 67 bearing an insulated contact
58 adaptecl to traverse said slide-wire and to as
suitable gearing 35 by means of a reversible elec
tric motor
receivmg power from a source 37
and controlled by relay means 38 direciüy sub
ject to the de?ection 0f the galvanometer 3l.
sume with respect to the extended length thereof
a position dependent upon the angular de?ection
of said shaft about its axis of rotation. A ten
The mechanism and means ‘for balancing the po 15 sidn spring S9, extended. between the bracket 65
and a ?xed abutment on the base-plate 25 main
tentiometer network through rotation o1? the shaft
tains the followers 81 and 52 in de?nite engage
29 in response to the detection of an unbalanced
ment With cams 56 and 55 respectively, and effec
conolition by the galvanometer 52 may, for ex
tively eliminates backlash from the mechanism.
ample, be of the form fully set iorth and. de
Connected to the motor l'l of the valve I3 is a
scribed. in U. S. Letters Patent N0. 2‚32-0‚066 issued 20
relay member 70 having a sensitive winding and
to F. B. Bristol, May 25‚ 1943; and since this and.
ci1*cuit-controlling elements (not shown in the
other forms 0I" electrical self-balancing mecha
drawing) whereby said circuit-controlling ele
nisms are well known in the art, no further ex
ments Will be actuated in a sense dependent upon
planation cf that element of the device need "leere
be given.
‘
25 the direction of current flowing in said Wind
ing. The relay member ‘Hi is interconnected with
Fixed 130 the shaft 29 is a pinion 35 meshing
the slide-Wire resistors 2I and 65 and a source of
With a gear sector ä€l integral With a_shaft 4l
electrical energy ‘H to form a briclge circuit; and
journalecl in the base platze 25. Attached 'to the
the circuit controlling elements of the relay are
shaft iil, and cle?ectable With the rotation there
oi’ through a limitecl angle, is an extencled arm 30 connected to said source of energy and to the
motor 20 in such a manner that unbalance cf the
42 carrying a pen or stylus 133 adapted t0 trans
briclge circuit due to motion of the sliding con—
verse the iace of a gracluated record chart M,
tact 58 along the slide-wire 66, Will cause the
and to inscribe thereon a trace of its movements.
relay member 10 to respond and actuate the mo
The chart 54 is driven at a constant velocity by
means of a conventional timing mechanism not 35 toi‘ 253 in a sense to cause the contact arm 24 by
its movement With respect to the slide wire 2! 150
sl1own in the drawing, whereby the trace made by
reestablish balance in the bridge network. 'I‘his
the pen or stylus 63 becomes a graphic record of
is a conventional and well-known form of non
positions assumed by said pen or stylus, and. there
trol, and is found in many clevices for distant
fore of the temperatures existing within the fur
nace or oven l!l over a periool oftime.
40 regulation of motors. An early exarnple of such a
control is disclosed in U. S. Letters Patent N0.
Journaled in a bracket member 55 integral With
599,903 granted to M. Pfatischer, May 12‚ 1896,
the base-plate 25 (which bracket member mal’
where the principle is shown in its application to
also form auxiliary bearings for the shafts 29
the steering of ships. For tliis element of the
and lli) is a shaft 46 coaxial With the shaft 29
and adapted for angular adjustment about its‘ 45 control system forming a part 0f the present in
vention no novelty is claimed; and lt neeol not
axis by means of a knob M. Fixed to the shaft
655 is a pinion 48 meshing With a gear sector 48
journaled upon a bracket 59 integral With the
base-plate 25, and rotatable through a limitecl
angle about an axis parallel to but displaced from
the axis of the shaft l1l. Attached to the gear
sector li% is an extended arm 5l terminating in
an index er pointer adapted to traverse the grad
uated surface of the chart 44, and t0 follow a
here be further described.
The operation of the apparatus embodying the
movable With said rocker arm structure about_
thereby will_rest upon the slide wire 56 in a'loca
principle of the invention may be described as
follows:
Assuming iirst that there exists a conclition of
equilibrium, with the valve I3 set at such a posi
tion ag t0 admit to the burner l I suf?cient fue1 170
maintain the space within chamber l? at a pre
tirne graduation upon said surface, laut, by Virtue 55 oletermineol constant temperature as detected by
the thermocouple 12 and measured by the position
et.‘ the displacernent of the axis of the shaft 45
of the sliding contact 21 With respect to the slide
from that of the shaft M, not in any position in
wire 26, the shaft 29 and the cam 55 will be
tersecting the path cf the pen or stylus 43.
maintained in position representative of said tem
Fixecl to the shaftg 29 and 66 respectively are
cams 55 and 5-‘5, angularly rotatable With said 60 perature, and the arm 42, actuated through the
shaft lll from the co-acting gear members 39
shafts in parallel planes and having their pe
and 4'5l, Will position the pen er stylus 43 upon
ripheries conformed to identical spiral contours
the graduated surface of the chart 44 to provide
whereby the length of any selected radius Will
a measure of said temperature value. By pre
be proportional to its angular displacernent from
65 vious acljustrnent the angular position of the carn
a selected reference radius.
55 about the common axis 0f the shafts 29 and
Jou‘rnaled upon the bracket 50 and rotatable
56 Will be the same as that of the cam 55, so that
through a limited angle about an axis 51 parallel
the cam followers 6! and 62 resting upon the
to, laut displaced from, the cornmon aXis of the
camg 55 and 56 respectively Will be at a common
shafts 29 and 45, is a rocker-arm structure 58
having a projecting portion 58’ extendecl beyond 70 radial distance from said axis, and the shaft
59 subject 170 the joint in?uenee of said cam fol
said common axis and carrying a pivotally mount
lowers will cause the arm 61 to occupy an‘ inter
ecl shaft or spindle 59 rotatable through a limitecl
mecliate position‚ whereby the contact 63 carried
angle about an axis intersecting the axis 57 anal
said last-named axis.
Fixed to, and. extendin‘g 76 tioh to maintain a balanced condition in the
5
bridge circuit‚ which includes the slide wire 2l;
EI whereby the cross arm 66 will be rotatedabouf;
and the valve motor I? will remain al; rest.
I*s may now be assumed that there has de
veleped a condition tending to lower the tem
perature Wi’?hin chamber I0. The E. M. F. devel
the point of engagement of the follower 62 with
oped by the thermocouple I2 will be correspond
the cam 48 as a fulcrum, causing
structure 58 to be retated in a
about the axis 51, and the slmft
time ‘so be rotated With respect
the rocker-arm
clockwise sense
ingly lowered with a resultant disturbance cf
arm struc’ßure in a sense t0 move the arm 6'!
59 at the same
tosaid rocker
ancl the con‘baci; 88 carried thereby, toward the
lef5-hand end of the slide wire 6%. This action
va‘nometer 3 i. The response of the galvanometer 10 Will cause izhe bridge network comprising saicl
slide Wire 65 and slidewire 2l tobecome unhal
will 'ee such as to actuate the relay 38, according
ance-d, whereupon the relay 76 will act to oper
t-o principleg hereinbefoi‘e sei; forth, in a sense to
ate the motor I‘! in a direction 130 close the valve
cause the motor 36, acting thr0ugh the gear train
I3, andr-incidentally to restore the bn'dge balance
35»t0 roiate the shaft 28 in 3, counter-clockwise
by moverneni; of the contact arm 24 with re'speci
sense as seen in the drawing, and to shift the
130 the slide Wire 2I.
.
sliding contact 21 to a position 0f lower potential
It will thus be seen there has been provicled. a
along the slide-wire 25, whereby electrical bal
mechanism which will continually tend 110 regu
ance cf the potentiometer network will be re
late th'e conditions Within the chamber l0»’00 a
stored. "Ehe shaft 41 will have been correspond
ingly rotatecl and the pointer arm 43 moved 130 a 20 constant temperature. It Will further be ap
parent that the temperature toward which regu
position where the pen er stylus 43 Will provide
lation is eifected may be established at-any cle
011 the chart 44 a measure cf the newly attainerl
sirecl predetermined value by manual adjust
temperature- value.
ment of the angular position of the cam 56 by
'I“ne cam 55 will have been corresponciingly ro
tatecl in a counter-cldckwise sense, so as to cauee 25 means of the knob 41. 'I‘he pointer 5l, angularly
movable with the gear sector 49, Will be subject
follewer 5l to engage a portion 01° i’cs periph
to displacement with any change in the setting
having an inereased radius. The movement
of the cam 56, so that itmay be ca'used topro
f the iolievver äl, aeting througlrthe cress arm
vide on the graduated surface of the Chart 44
E9, Will cim‘se seid arm tasWing abcut the point
of eneä‘agement of the follower 62 wi‘bh the periph '30 an indication of'the control point established. by
the potentiometer balance, whereby current Will
?ow throu-gh the sliding contact 21 and l31‘le gal
ery of Elle cam 56 as a fulcrum, whereby ‘übe shaft
the setting cf the cam 56.
59 and the rccker-arm structure 58, will be given
b0dily rotaizion about the axis 52', carrying il1e
braclze’s 85 anal the slide wire 66 through a CO1‘
respenriing limited angle about seid axis. A5
The terms anti expressions whichl have em
ployed are usecl as terms of description and not
015 limitation, andl have no intention, in the use
.
.
seid roäary metion is derived from a change in
equivalents of the features shown and described
o.f such terms and expressions, of excluding any
er portions thereof, but recognize that various
modi?cations are possible within the scope of the
consequerit'angular rotation of the s'naft 59 With
invention claimed.
~
~
respec’t‘co l3l’le rocker-arm strueture 53 Will cause
I claim:
thev
5? to be similarly rotatecl, Whereby the 40
1. In a device for controlling the magnitude of
contact
Wl‘zl assume a new position With re
a variable, a measuring instrument sensitive to
spect to the slide wire 68, the change in position
changes in said variable, a cam, means com
being iowarcl the right as seen in the drawing.
trolled by said instrument for positioning saicl
'I'he chan're in position 01° ’che contact 58 With
cam in aceordance with said magnitude, a sec
respeet t0 the slicle Wire @36 Will disturb the bal
ond cam, means for positioning said second cam
ance of the bridge circuit comprising said slide
in accorclance with a desired magnitude, dilfer
Wim 68 and Ehe slide wire 2I, whereby the relay
position cf ene end only of the cross arm 653, the
15 Will be ener‘gize-cl in a sense t0 actuate the
ential means cooperating With said cams and op
erable thereby into positions corresponding ‘w
va1ve motor i? and open the valve I3, causing an
increaeed supply o=f I‘uel to be admiätecl from the 50 differences between the settings of said cams, and
means controlled by saicl differen’oial ‚means for
source l% through the conduit ‘4 to the burner
a?ecting ‘ehe magnitude o:f said variable.
i l, with a corresponding tendency torestore the
2. In a device for controlling the magnitude of
temperature within the chamber 53 to its former
a variable, a measuring instrument sensitive to
preCle-öermined val'ize. At the same time, the non
tac+„ arm 231 will have been shifted along the slide 55 changes in said variable, a cam, means controlled
by said instrument for positioning said cam in
wäre 2i in a senee to res‘bore the balance o-f the
accordance With said magnitude, a second cam
bridge eircuit and render ihe relay 'i'0 inactive, so
having a working surface substantially identical
th-at ‘alle valve ’motor I'.’ Will be brought to res’a
with th-e valve i3 in a new position correspsnd
With that of the ?rst mentioned cam, means for
ing to €he increased demand for fuel.
60 positioning seid second cam in accordance With
a desired magnitude, differential means cooper
In a e‘imilar marmer, shoulcl the temperature
ating with said cams and operable thereby into
wiä'n‘n ‘ehe chamber 25 rise above ‘ehe predeter
positions corresponding to differences between
value, ‘ehe resuliant increased potential
the settings of saideams, and means controlled
developed by the thermecouple I2, acting upon
'uhe galvanometer 31 through slidin-g contact 21 of 65 by saic1 differentia‘l means ior affecting the mag
nitude 'of said variable.
1
the poteniiomeier circuit, Will cause the relay 31
3. In a device for controlling the magnitude of
t-o reeponcl ancl to actuate the motor 35 in a sense
a variable, a measuring instrumeni; sensitive t0
130 restore the potentiometer balance by rotating
the shaft 29 in a cl-ockwise sense as seen in the
changes in said variable, a cam, means com
dravvine ancl shifting the sliding contact 27 to 70 trollecl by saicl instrument for positiom‘ng said
cam in accordance with saiol magnitude, a second
warcl ihe right on the slide wire 25, which change
cam having a working surface substantially
Will b-a indicated by pen er stylus 43 assuming
a new position 0:1 the chart 44. A’s the same time,
identical with that of the ?rst mentioned cam
the cam
being rotatecl in a clockwise sense,
and movable in a plane substantially parallel to
Will present a decreased radius 170"13h8 folloWe‘r 75 that- cf said?rst: mentioned cam, means‘ for posi
8
tioning said second cam in accordance with a
desired magnitude, di?erential means cooperat
ing with said cams and operable thereby into
able thereby into positions corresponding to- dif
positions corresponding 110 di?erenceg between
magnitude Qi said variable, and electrie circuit
the settings of said cams, and. means controlled
by said di?erentia1 means for a?ecting the mag
means controlled by saicl differential means for
controlling the operation of said motor.
9. In a device for controlling the magnitude
of a variable, a measuring instrument sensitive
nitude cf. said variable.
~
4. In a device for controlling the magnitude of
ferences between tl1e settings of said cams, re
versible electric -motor means for affecting the
a variable, a measuring instrument sensitive to
to changes in said variable, a ?rst cam member
changes in said. variable, a cam, means con 10 movable under control cf said instrument, a sec
trolled by said instrument for positioning said
cam in accorolance with said magnitude, a sec
ond cam, means for positioning said second cam
in accorclance With a desired magnitude, differ
ond cam member having a working surface sub
stantially identical with that of said ?rst cam
member and adjustable in a plane parallel to
that o-f saicl ?rst cam member, a rocker element
ential means eooperating simultaneously with 15 rotatable through a limited angle about an axis
perpei1dicular to the planes of said cam mem
saicl carns and rockable thereby about an axis
into positions corresponding 130 differences be
bers, said rocker element having pivoted thereon
tween the settings of said cams, and means con
an extended differential member with its ex
tremities simultaneously engaging the respectiVe
trolled by said differential means for a?ecting
the magnitude of said variable.
20 cam members, first control means carried by said
5. In a device for controlling the magnitude cf
recker element, second control means movable
with respect 130 said. ?rst control means in re
a variable, a measuring instrument sensitive to
sponse to variations in the angular position of
changes in saicl variable, a cam, means controlled
by saicl instrument for positioning saicl cam in
said differential member about its axis, and
accordance With saicl magnitude, a second cam, 25 means controlled by said ?rst and sec0nd son
trol means 130 affect the magnitu'de of said vari
means for positioning saicl second cam in ac
cordance with a desired magnitude, di?erentia]
able.
I0. In apparatus for controlling the magni
means comprising a rockable shaft having ex
tensions engaging ‚said cams and rockable there
tuoleof a variable, a measuring instrument hav
by into positions corresponc'ling to di?ferences be 30 ing a movable element adapted to assume a po
sition representative 0f the magnitude of a cou
tween the settings of said carns, and means cou
trolled by saicl differential means for affecting
clition 130 be controlled, a ?rst cam member mov
the magnitude cf said variable.
able With said element, a second cam member
movable in a plane parallel 130 that of said ?rst
6. In a device for controlling the magnitude 0f
a variable, a measuring instrument sensitive 110 35 cam member, a rocker-arm rotatable through a
limited angle about an axis perpendlcular 110 the
changes in said variable, a cam, means cou
planes cf saiol cam members, said rocker arm
trollecl by said instrument for positioning said
having pivoted about an axis thereon an ex
cam in accordanee with said magnitude, a sec
tendecl differential member With its extremities
ond cam, means for positioning said second cam
in accordance Wibh a desired magnitude, differ 40 engaging saiol cam members‚ and means carried
by said rocker arm and adapted to affect the
ential means cooperating simultaneously with
magnitude 0f said variable according to the de
saicl cams and movable thereby into positions
corresponding 110 di?"erences betvveen the set
?ection of said differential member about its piv
otal axis.
tings of said cams, a frame carrying said differ
ll. In a device für controlling the magnitude
ential means and movable by said cams, control 45
of a variable, a measuring instrument sensitive
means movable with said differential means and
110 changes in said variable, a ?rst cam member
said frame respectively, and means controlled by
said control means for a?°ecting the magnitude
movable under control 0f said instrument, a sec
ond cam member having a working surface sub
01° saicl variable.
7. In a device for contr0lling the magnitude 50 stantially i'dentical with that of said. ?rst cam
member and adjustable in a plane parallel to
of a variable, a measuring instrument sensitive
that of said ?rst cam member, a rocker element
to changes in said variable, a cam, means com
rctatable through a limited angle about an axis
trolled by said instrument f0r positioning said
perpendicular to the planes of said cam mem
cam in accordance With said magnitude, a sec
ond cam, means f0r positioning said sec0nd cam 55 bers, said rocker element having pivoted there
on an extende_ol differential member With its ex
in accorclance With a desired magnitucle, differ
tremities simultaneously engaging the respective
ential means comprising a rockable shaft haVing
cam members, ?rst control means carried by said
extensions engaging said cams and roekable
rocker element, second control means movable
thereby into positions corresponding to differ
enees between ‘ehe settings of said carns, a frame 60 with respect to said ?rst control means in re
carrying saicl differential means and rockable by
said cams about an axis di?erent from thal; of
sponse to variations in the angular position o-f
said differential member about its axis, and
means controlled. by said ?rst and second C011
t1'01 means to a?lect the magnitude of saia vari
tively, and. means controllecl by said eontrol 65 able, separate indicating means associated re
spectively with said. cam members, and movable
means for a?eeting the magnitucle of said vari
110 provide indications of the measured magni
able.
tude 0f said variable and the set‘ting of said sec
8. In a device for controlling the magnitucle
ond cam member respectively.
cf a variable, a measuring instrument sensitive
12. In an instrument for measuring and cou
‘ca changes in said variable, a cam, means con 70
trolling the magnitucle of a variable condition,
trollecl by said instrument for positioning said
means sensitive 130 changes in said magnitude,
cam in accordance with said magnitude, a second
a graduated. sv.rface‚ a ?rsl; deflecting member
cam, means for positioning said second cam in
juxtaposed 120 said surface and adapted to provide
accorda'nce with a desired magnitude, differen
tial means cooperating with said cams and oper - 7-5 thereon a measure of said magnitude‚ a ?rst ro
said rockable shaft, control means movable with
said di?erential means and said frame respec
9,
10
tatable element controlled by said sensitive means
of said differential means and connected in said
control circuit to form wit‘n said ?‘rst resistance
a bridge network with said relay directionally
responsive to unbalance conclitions to command
the operation of said motor in a sense to restore
for posltioning said member With respect to the
graduatio‘ns 011 said surface, a second deflecting
member juxtaposed to said surface and adapted
to provide in conjunctlon with tl1e graduations
thereon measures corresponding to desired mag
nitudes of said conclition, a second rotatable ele
ment operable cencurrently with the positioning
0f said second ele?ecting mernber, di?’erential
the balance oi said network.
'
16. In a control systern for limiting the de
parture of tl1e magnitlicle cf a eonclltion from a
predetermined value, tl1e cornbinatien of two
mechanism comprising two similar cam members 10 cam members having slmilar eontours and. dis
placeable in parallel planes, one of said eam mem
and a follower jointly positioned by the sarne,
leere being positionable at Will in accordance With
one of the said cam members being connected 170
said predeterrnined value, ancl the other having
the ?rst rotatable element for movement there
means ior positioning lt in accordance With said
by, and the other of the said cam members be—
ing conn@cted to the sec‘oncl rctatable element for 15 magnitude, an element retatable through llmited
angles about twc axes, one of said axes lylng in
movement thereby. ancl means actuatecl by said
a plane parallel to said planes, and the other
follower for controlling said variable conclition.
13. In apparatus for controlling the magnitude
bel:1g angularly disposed‚ thereto, said rotatable
element having parts c‘ .gaging both said cams,
of a variable, a measuring instrument having a
movable element adapted to assume a position 20 whereby to be cle?ecteci about the first of said
axes in response to diilerences in the displace
representative of the magnitucle of a condition
ments of said cams, and to be de?ected about
to be controllecl, a ?rst cam member movable
the other of said axes to an extent proportional
With said element in a plane, a second cam mem
her movable in a plane parallel to that 01° said
to the mean cf the effective helghts of said can1s,
?rst cam member, a rocker-arm rotatable 25 and means operatively connectecl ts said element
for controlling said condltion.
through a limited angle about an axis perpen
17. In a control system for limiting tlie cl-epar
dicular to t-he planes 0f said carn members. a
ture of the magnitude of a conclition from a pre
variable resistance unit carrieri loy said rocker
deterrnined. value, the combination cf two cam
arm, an electrical netwerk including said re»
sistance unlt and means fer controlling said mag 30 mernbers having similar contours anal angularly
displaceable in different planes about a com1non
nitude‚ whereby changes in said resistance unit
axis intersecting said planes, one of said cams
will aifect the performance of said controlling
belng positionable about said axis at Will in ac
means, and means movably carried upen said
cordance With said precletermined value, and
rocker arm and positionecl relatively thereto un
der the joint influence of- said cam elements to 35 the other having means for positioning lt in ac
vary said resistance and thereby to command
the Operation 01° said controlling means.
14. In a clevice for controlling the magnitude
of a variable, an electrlc motor adanted to control
said magnitude, a control circuit for said motor‚
including a resistance element variable by said
motor and a directlonal relay adapted to com
mand the operation of said unter, a measuring
instrument havlng a movable element adapted
c-ordance With said magnitude, an element rotat
able through a limlted angle about tvvo axes, one
of said axesl ‘in-g in a plane parallel to said. planes,
and the other being angulai‘ly disposed thereto,
said rotatable element having parts engaging both
said cams whereby to be de?ectecl about the ?rst
of said two axes in res-ponse to di?erences in the
displacernents cf said carns, and to be deflected
about the other cf said two axes to an extent pro
to assume a position representatlve of said mag 45 portional to the mean cf the effective radii of
said carns, and means operatively connected to
nitude, a first cam member movable With said
said element for controlling said condition.
element‚ a second cam member movable in a
plane parallel to tliat of said ?rst cam element,
18. In a control system for limiting the de‘par
ture 0f tlie magnitude of a condition from a pre
a rocker-arrn rotatable through a limited angle
abeut an axls perpendlcular to the planes of said 50 determined value, tl'1e combination of two cam
cam mem'oers, said. rocker-arm havlng pivotally
members having simllar contours ancl displace
mounted thereon a differential member adapted
able in parallel planes, cne 01° said cam mernbers
130 be angularly posltioned by t-lie joint infiuence
being positionable at Will in accordance With said
predetermined value, and the other having means
of said ?rst and second. cam members, ancl re
sistance means variable in accorclance With the 55 for positioning lt in accordance With said mag
angular position 0.1"‘ said dli‘ferential member and
connected in said contr0l clrcuit t0 form With
said ?rst resistance element a briclge network
with said relay directionally respensive to un
balance conditions t0 command the operatlon of 60
said motor in a sense to restore the balance of
said network.
nitucle, an element rotatalo-le through limited
angles about two axes, one of said. axes lylng in
a plane parallel to said planes, and the other
being angularly disposecl thereto‚ said rotatable
element having parts engaging both said cams,
whereby to be de?ected about the ?rst of said
axes in response to di?erences in the displace
ments cf said cams, and to be de?ected. about
15. In a device for controlling the magnitucle
the other of said. axes to an extent proportional
0f a variable, an electric motor adapted to can
trol said magnitucle, a control circuit f0r said mo 65 to th.e means of the eifective heights 01° said
tor including a resistance variable by said mo—
ca‘ms, anal means operatively connected to said
tor and a directional relay adapted to command
element for controlling said condition in response
the operation 0f said motor, a measuring instru
to de?ectiou 0f said elemen't about said first axis.
ment having a movable element adaptecl to as
19. In a control system for limiting the depar
sume a position representative of said magnitude, 70 ture of the magnitude of a condition from a pre
means settable into a position representative cf
determined value, t’ne combination of two cam
a desired magnitude, di?ferential means posi
members having similar contours and angularly
tioned under the jolnt control of said movable
displaceable in different planes ab0ut a co-mmon
element and said settable means, and resistance
axis intersecting said planes, one of said. cams
means variable in accordance with the position 75 being posltionable 'about said axis ab Will in ac
2,405,774
11
12
oordance with sa‚id predetermined va1ue‘, and. the
other having means for positioning it in accord
ences in the displaoements 0f said cams, and. 120
be de?ected about the other of said two axes to
ance with said magnitude, an element‚ rotatable
through a limited angle about two» axes, one of
an extent proportional to the mean of the effec
tive radii of said cams, and means operatively
said axes lying in a plane parallel to said planes,
connected to said element fo1‘ controlling seiid
and the other being angularly disposed. thereto,
sa‚id rotatable element having parts engaging
condition in response to de?ection of said element
about said ?rst axis.
CLINTON A. BLAKESLEE.
both said cams whereby to be de?ected about
the ?rst of said two axes in response to di?er
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