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Dec-10,1946.
W
'J.G.OETZEL.
'
2,412,228
APPARATUS FOR REGULATING VEHICLE 'SPEED
_ .FiI'ed'Jan. 26, 1944
‘2 SheétS-Sheet 1
TCUORQEN‘
‘INVENTOR
John George OetJel
‘SPEED
,
’ ‘BY-M,
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ATTOR NEYS
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Dec. 10, 1946. ‘
‘
J. G. OETZEL.
'
2,412,228
APPARATUS FOR REGULATING VEHICLE SPEED
’
Filed Jan.- 26, 1944
v2 Sheets-Sheet 2
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Patented Dec. 10, 1946
2,412,228
UNITED STATES PATENT OFFICE
2,412,228
APPARATUS FOR REGULATING VEHICLE
'
SPEED
‘
John George Oetzel, Beloit, Wis., assignor to
Warner Electric Brake Manufacturing Com
pany, South Beloit, 111., a corporation of Illinois
Application January 26, 1944, Serial No. 519,726
8 Claims.
(01. 192-3)
2
1
This invention relates to the retarding of ve
hicles, particularly heavy automotive vehicles,
and the general object is to provide an auxiliary
troller such as an accelerator pedal I3. The ve
hicle is also equipped with independently acting
braking system which operates automatically and
main brakes M which may be actuated electrically
and controlled manually by depression of a foot
in a novel manner to reduce the burden on the
pedal I5 actuating a rheostat controller l6.
main brakes.
The present invention contemplates a novel
method of controlling the auxiliary or. friction
>
"
Another object is to provide a novel method of
controlling the energization of an auxiliary fric
tionless type of vehicle brake whereby to main
tain the latter at optimum e?ectiveness at differ
ent operating speeds.
'
less brake above described‘so as to approach opti;
mum effectiveness in retarding the vehicle over a
10 substantial range of the speeds at which braking
may be required in service operation of. the ve
hicle. The method includes the'steps of energiz
ing the auxiliary brake automatically as an incif
dent to retraction of the vehicle controller to a
may be controlled automatically as an incident 15 low speed position, and varying the degree of such
to a manipulation, such as operation of the accel-.
energization automatically‘ with the prevailing
vehicle speed so as to maintain greater 'energiza
erator, naturally occurring in the normal use of
tion at low speeds than at relatively higher speed.
the vehicle at a time when it is desirable to impose '
a retarding force.
As a result, the auxiliary brake, which necessarily
Another object is to provide a frictionless brak 20 is relatively bulky considering its available output,
may be utilized very effectively at low Ivehicle
ing system, the effectiveness of which varies with
speeds without danger of being damaged by over+
the vehicle speed and degree of electrical en
heating at high speeds. A substantially greater
ergization together with means for varying the
part of the total braking burden may thus be
energization automatically so that the system
may operate substantially at optimum effective 25 assumed by the auxiliary system with a resultant
A more detailed object is to provide a brake of
the frictionlesstype which is operable effectively
at comparatively low vehicle speeds and which
ness over a substantial speed range.
reduction in the frictional wear on the main or
The invention also resides in the novel char
acter of the means for controlling the brake
friction braking system.
The vehicle I0 is equipped with four eddy
current brakes 9, two at the rear end of the
Other objects and advantages of the invention 30 propeller shaft and two intermediate the shaft
ends with their stationary elements ,mountedon
will become apparent from the following detailed
a cross member 8 of the vehicle.‘ frame. 'The
description taken in connection with the accom
panying drawings, in which
~
number and location of the auxiliary brakes will,
Figure 1 is a plan view of the wheel and axle
of course, depend on the kind of vehicle, the
location of the prime mover, etc. The brakes .9
assemblies and the power plant of an automotive
vehicle equipped with a braking system embody
are of the same general‘ construction, that of the
rear units being shown in Fig. 2. Each includes
ing the present invention.
a plate I‘! having a cylindrical ?ange or drum
Fig. 2 is a section taken along the line 2-2 of
Fig. 1.
2| fast on one end of the shaft l8 which is jour;
'Fig. 3 shows curves illustrating the electrical 40 naled in the rear axle housing about the axle l9
characteristics of certain of the control parts.
and coupled‘at its forward end to the propeller
shaft. The axle is driven through bevel gearing
Fig. 4 is a schematic view and wiring diagram
20 so that the shaft [8 is disposed above the axle
of the automatic brake control.
permitting the drum 2| to be of substantial di
Fig. 5 is a section taken along the line 5-5 of
45 ameter. The drum and the plate are composed
Fig. 1.
Fig. 6 is a sectional view taken substantially
of cast iron or the like and formed with heat
along the line 6-6 of Fig. 5.
radiating ?ns 22.
a
a
The internal drum surface 23 is smooth and
For purposes of illustration, the invention has
is disposed close to the outwardly facing poles 24
been shown in the drawings as ‘applied to the
control of auxiliary brakes‘ 9 on a heavy auto 50 of a magnet ring 25 whose hub ‘25 is boltedito
motive vehicle l0. driven through the usual pro
the gear housing 21. An annular winding‘ 28is
peller shaft H by a prime mover such as an
disposed between the poles which may, if desired,
be constructed with annularly spaced teeth.
internal combustion engine [2 which operates at
varying speeds depending, among other things, on
When the winding is energized, magnetic ?ux
the position of a manually adjustable speed con 55 threads the circuit ‘around the winding .includ
energization.
2,412,228
4
3
I
vehicle. If it is desired at any time to permit
the vehicle to coast freely with the accelerator
ing the drum or inductor 2| creating eddy cur
rents in the latter. Since the magnet is station- ,
ary, a retarding e?ect is thus exerted on the
drum and, therefore, on the vehicle axle, the mag
nitude of this force being proportional to the
released, the driver may depress a button and
close a switch 50a preferably located on the‘ usual
gear shift lever 50b. This switch is in parallel
with the switch 48 so as to maintain the solenoid
44 energized and the eddy current brakes inef
fectual so long as the switch is held closed.
vehicle speed and also to the energizing cur
rent.
While current ‘for exciting the eddy current '
windings 28 may be derived from a storage bat
tery or the like, it is preferred to employ a sep;‘
Eddy current devices of the character described
‘have a speed torque characteristic of thegeneral
shape shown at 53 in Fig. 3, the output increas
ing progressively over a wide speed range. Such
arate electric generator 29 which may be mounted ,
on the side of the transmission case 36 and driven,
as by a belt 3! from the propeller shaft. As
a device, if energized su?ciently to produce a
retarding force of any considerable magnitude
shown, the generator is of the shunt type having‘
opposite terminals of its rotor 32'connected to:
Y at low vehicle speeds might become overheated
and damaged by prolonged operation at high
the brake windings 28 and a stator with‘ a ?eld
speeds‘. To avoid this, energization of the brake
windings 28 is controlled automatically in the
manner" described hereinafter to ?atten the
Winding 33 adapted to be connected in parallel‘
with the rotor when current is to be delivered.
In the present instance, the circuit for the gen
erator ?eld includes in. series relation a switch 20 speed-torque curve as indicated at 88 so that
above a selected vehicle speedat which the wind
35, a manually adjustable rheostat 36, a conduc-‘
ings 28 become energizedby'thegenerator29 ,
tor 31- leading to one terminal of a resistance ele
su?iciently to produce e?ective eddy current'ace
ment '38 which coacts'with a wiper arm 39 lead
ing to the'other rotor terminal. Thus, when the
switch 35 is closed and thevehicle is-in motion,
the output ofthe generator-and therefore the
degree of-energization of the'brake windings 28
will be determined by the setting of the rheo
st-at 36 and the position of ‘the arm 39 which
cooperates with the resistance element 38 to form 30
tion,. the retarding torque. developed remains; ap
proximately constant and resultsin substantially
uniform deceleration of the vehicle over the en
a- second‘ rheostat or voltage'controller 40 which
tire range of higher-vehicle speeds; ‘If desired,
provision may be made-forincreasing the torque
gradually with the vehicle speed in. view of the
fact that the rateof' heat dissipation by the eddy
current brakes increases somewhat with» the
maybe of standard construction.
speed.
I
In accordance-with ‘the present invention, the
brake windings 28 are energized automatically
asan-incident to retraction of the speed con
troller or accelerator 13 to low speed position.
For 'this‘purpose, themovable contact 4| of the
switch'35'is'urged by a“ spring 42 to switch clos
ing position as shown~~in>~Fig. 3 and is connected
a
To impart such a speed-torque characteristic
to-the brakes, the currentsoutput of the-gener
35 ator .29 must'be decreased progressively asethe
vehicle speed increasesv aboveethe'value at which ’
the desired braking torque is attained- ~For~<this
purpose, the voltage regulator-4011s adjusted auto
matically to impart to the generator'a-speed7
to'the'ar‘mature 43' of a solenoid 44 so as to open ,40 current characteristic as shown in-F-ig; 3,» the
the switch ‘35 when the solenoid is energized. As
an incident to ~this latter' motion, the contact 4|
engages'a .contact 45 to connect a discharge re
sistance 46in series withthegenerator ?eld wind
ing “and thereby insure complete disabling of
the generatorr
.
'
‘
One terminal of the solenoid 744 islconnected to
the vehicle storage-battery 41 and the other ter
current ?rst increasing sharply as'indicated at
89, then decreasingquitev sharply-as." indicated _
at 86 from a 'pointB'l, and vfinally levelingeo?
at the higher speeds.
,
'
r
In the present instance; actuation .of'the arm
39 to obtain this ‘characteristic iis'e?ected- by’ a
speed responsive device-:60 which preferably? is a
clutch , operating by- eddy-current action'~~and
minal is‘connected through-a switch’ 48, the've
therefore without friction. As showmin Figs.=5
linkage ‘l 3a'to theaccelerzttor-pedal 13 so as'to be ;
disposed‘inopenposition as shown when the ac
ator 29. Projecting from~theehub are‘tWo-rings
hicleignitiontswitch 49; and’ a conductorrli? to they 50 andr?, therclutch comprises a rotor; '6I~~ having
a hub- 64*“ composed of nonmagnetic'material
other battery terminal; Themovable contact 5|
and supported through anantiefriction bearing .
of the switch“ is" connected through suitable
62 on an extension e3>of=theeshaft~oi the genere : ‘
celerator pedal is released and held by a_ spring 55 of - ‘magnetic materialv axially I spaced and""-.lyi;ng
against opposite’ sides of- a 'flangeJSi-b» on'qthe
52 in ‘the‘low speed idling position. Immediately
hub. Permanent magnetic bars 6l°~are pressed
upon *the'initial depression of the pedal to speed .
through. the rings and" the flange, . and; the rings
up the engine [2; the switch 48 is‘closed and‘ re
are formed around their periphery with ,annu';
mains closed at all higher speed positions of the
accelerator pedal vit, one‘ of which is shown'in 60 larly' spaced poles~64~having 'faces 65 disposed
close to the internal ‘cylindrical surface 66-~0f va
drum-67!. The latter is carried ~by1adisk=68 which
is keyed to the shaft extension:v The clutch is
contacts :E-I-e after the initial engagement with
housed within a cup-shapedcasing 14'fasten'ed
the contact 5|. Thus, when the vehicle ‘is in
motion-with the ignition switch closed; the sole— 65 by screws 15 to the generator housing and closed
dotted outline- in- Fig. 4.
This may be accom
plished by providing for yielding of the switch
‘
noid 44 will remain energized, the generator will
be disabled, and the eddy current'brakes will be
maintained inactive in all positions of the accel
erator pedal except the-lowspeed or released‘po
sition; However, when the accelerator pedal ‘is
released‘ ‘and the switch 48 is thereby opened, the
solenoid will be'deenergized whereupon the switch
35 will close automatically to render the gener
ator operative to deliver current to the windings
28. and. produce-a force retarding coasting of the
at its open end by a- removable plate 16." Turn_
ing of the rotor GI ‘is-resisted yieldably byi‘a
spring» 6910f ‘the torsion type having/aneye "H1
at one end anchored on~a pin ‘H whichprojects .
from the rotor through‘the spring and parallel
to :the rotor axis. The pin’ coacts ‘with 1other
similarly mounted pins ‘12 to support 'thezspring,
the other end 13 of which is bentoutwardlyz-and
anchored by a lug TL- The latteris'struckrout‘
. of a disk Sll'whichis adjustable around-1a‘ stag
2,412,228
6
'tlonary ?ange 9| on’ the plate 16 and ‘held in
position by a screw tightened clamp 92. By ad
justing the disk 90, any desired initial stress of
the spring may be obtained.
.
retard the vehicle at a rate, for example, on the
order of eight feet per second per secondvthat will
be comfortable to the vehicle occupants. The
rate selected may, under certain load and road
conditions, be excessive for safety of operation.
Under such conditions it may be desirable to re
By virtue of the permanent magnetic flux
which threads the drum 81 through circuits in
duce the capacity of the auxiliary brakes which
dicated by the arrows in Fig. 5, it will be apparent
may be accomplished by adjusting the rheostat 36
that a turning moment will be applied by eddy
so as to cut down the excitation of the wind‘
current action whenever the vehicle is in motion
r
and therefore when the drum is turning. The 10 ings 28.
speed-torque curve 93 of this clutch is more
This application is a continuation in part of
gradual than the curve 53 owing to the lower
my copending application Serial No. 491,468, ?led
June 19, 1943.
degree of ?ux saturation‘ employed. After a
predetermined low speed is attained with the
vehicle traveling forwardly, the torque developed
will be sufficient to overcome the initial stress '
of the spring 69 whereupon the rotor will turn
counterclockwise as viewed in Fig. 6 until the in~ I
I claim as my invention:
1. A braking system for an automotive vehicle
having a speed controller adjustable manually
away from and toward a low speed or idle posi
tion, said ‘system having, in combination, electric
' braking means, a generator for energizing said
creased stress of the spring balances the-turn
ing moment. As a result, the rotor will always 20 braking means when active and having a ?eld
circuit including a shunt winding, a discharge
occupy a position angularly spaced from the idle
resistance, a variable resistance, a magnetic relay
position, a distance corresponding to the prevail
adapted when energized to interpose said dis
ing vehicle speed. Herein the range of the rotor
charge resistance in said ?eld circuit and when
movement is nearly a full revolution being lim
ited by engagement of an arm 84 with a station 25 deenergized to interpose said variable resistance
in said circuit whereby to render the generator
ary lug 94 on the ?ange 9|. This arm is fast on
active, means for varying the value of said vari
a collar held by a set-screw 82 on a shaft 18
able resistance to regulate the generator output,
which is journaled in a bearing 19 at the center
and means operable to deenergize said relay when
of the plate 16. The outer end of the arm is‘
Clockwise 30 said speed controller is retracted to said idle po
sition and to energize the relay when the con
troller is positioned for operation of the vehicle
at higher speeds.
2. A braking system for an automotive vehicle
'Fig. 6, this being the position occupied by the arm
35 having a speed controller adjustable manually
when the engine is idling.
away from and toward a low speed or idle posi
To adjust output of the generator 29 accord
tion, said system having, in combination, electric
ing to the vehicle speed thus measured by the de
braking means, a generator for energizing said
vice 68, the shaft 18 carries the arm 39 of the
braking means when active and having a ?eld cir
rheostat 48. The resistance element 38 of the
latter is mounted on an insulating body 88 which 40 cuit including a shunt winding, a variable resist
ance adapted to be interposed in said ?eld circuit
is disposed within a casing 82 and held against
bifurcated and receives the pin 1 l.
movement of the rotor as the vehicle moves back
wardly is prevented by engagement of the arm ‘
84 on the other side of the lug 94 as shown in
rotation by a bracket 8| projecting into a hole in
the plate 16.
With the foregoing arrangement, the arm 84
will be swung clockwise away from the position
shown in dotted outline in Fig. 6 as the forward
Speed of the vehicle is increased above the idle
value and the rheostat 40 will be adjusted auto
matically with changes in the speed so that as
the vehicle speed increases, the value of the re- '
sistance included in the generator ?eld circuit
will be increased and the generator output cor
respondingly decreased. The scale of the spring’
,69 and the construction of the resistance 38 are
proportioned to impart a current-speed charac
teristic somewhat as indictaed at 86 whereby the
current energizing the auxiliary brakes 9 is re
duced progressively at a decreasing rate after the
clutch torque is increased sufficiently to overcome
the initial stress of the spring 69 as indicated at
81. In this way, the increase in braking effect
due to the increased vehicle speed is substantially
offset by a decrease in the excitation, and the
total retarding force exerted by the auxiliary
brakes 9 is maintained approximately uniform
as indicated by the curve 88. By thus adjusting
their retarding capacity automatically in accord
ance with changing service requirements, the
auxiliary brakes 9 are utilized at optimum effi
ciency at the various vehicle speeds at which they
may be brought into play by release of the ac
celerator pedal.
The total retarding ‘force produced by the
auxiliary brakes is, of course, determined by their
to render said generator operative to deliver cur
rent proportional to the value of the resistance,
means operable automatically to decrease and
increase the value of said resistance progressively
as the speed of the vehicle increases and decreases
respectively, a second resistance, and means oper
able automatically as an incident to retraction
of said controller to said idle position to interpose
said second resistance in said ?eld circuit.
3. A braking system for an automotive vehicle
having, in combination, electric braking means,
a generator driven by the vehicle and operable,
when active, to generate electric current in pro
portion to its speed and to energize said braking
means, said generator having a shunt ?eld wind
ing, a circuit for said winding including a switch
and a voltage regulator having a member ad
justable to vary the generator output, means con
trolling the opening and closing of said switch
to render said generator inactive and active, and
means responsive to the speed of said vehicle to
adjust said member and vary the generator out
put inversely proportional to changes in the ve
hicle speed.
4. A braking system for a movable vehicle hav
ing, in combination, braking means for the ve
hicle adapted to be energized electrically and to Q
exert a retarding force proportional to the de
gree of energlzation, a voltage regulator control
ling the excitation of said braking means and
having a member selectively adjustable to vary
the degree of such excitation, an eddy current
clutch having a driving element driven in unison
number and their design. These are such as to 75 with vehicle motion and a driven element con
2,141.2;228
7
'8
nected to said member, and'meansyieldablyree
‘ si‘sting: motion of said driven element to vary
the position of saidfmember in proportion to
changes in the vehicle speed.
7
,
, 5. A braking system for a movable vehicle hav
ing, in combination, braking means for theve
acting jto derive an'actuating force proportional
to the‘vehicle speed, and meansfor applying said
actuating force to said member to position'the
latter variably in accordance with changes in the
force.
,
,
V
'
1
7. A braking system for an automotive vehicle
hicle adapted to be energized electrically and'to
having, in combination,‘ electric braking means,
exert aretarding force proportional to the de- ’
a generator driven ‘by the vehicle and operable, '
gree of energization, a voltage regulator con
when active, to vgenerate electric current and en-,
trolling the excitation of said braking means and 10 ergize said braking means, a circuit governing the
having a ‘member selectively adjustable'to vary
action of said generator including a switch and
a voltage regulatorv having a member adjustable
the degree of such excitation, two constantly ex
cited magnetic elements rotatably mounted on
said vehicle, one being rotated in unison with
to vary the generator output, means controlling
the opening and closing of said switch to render
t the; vehicle motion and producing a magnetic 15 said generator inactive and active, and means
dragytending to rotate the other element, means
yieldably resisting rotation of said latter element
whereby vthe instantaneousposition of theilatter
corresponds to the prevailing vehicle speed, means ‘
connecting said last mentioned element and said 20
member to actuate the latter and decrease‘ the
excitation; of said braking means progressively
as the vehicle speed increases.
responsive to the speed of :said vehicle, to adjust
said member and ‘vary the generator output‘in
versely proportional- to changes in the vehicle
speed.
I
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-
8. A braking system for an automotive r-vehicle
having, in combination, electric braking means,
a generator driven by the vehicle and operable,
when active, to generate electric current and en
6. A braking system for a movable vehicle hav-'
ergize said braking means, a; circuit governing '
ing, in'combination, braking means for the ve 25 the output of said generator, and means auto
hicle adapted to be energized electrically and to
matically responsive to changes in the vehicle
speed and operable to adjust'thev outputof said
exert a retarding force proportional to the de
gree of energization, means controlling the exci
generator so as to cause said braking means to
produce a retarding torque which is substantially
tation of said braking means and having a mem
ber selectively‘adjustable to vary the degree of 30 uniform at di?ferent vehicle speeds;
' ‘
such excitation, a clutch driven in unison with
vehicle motion and having magnetic elements oo
JOHN GEORGE OETZEL, ,
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