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Патент USA US2120546

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Junel4,l93&
-
R.C.BURT
2,120,546
MECHANICAL TRANSMI SS ION
Filed May 25, 1931
2 Sheets-Sheet 2
Nb.
mm;
7 72775;}? 6.9
_ Patented June 14, 1938
2,120,546 .
- UNITED STATES ' PATENT.) OFFICE
MEGHIANIOZ'IIf'EZtNSMSSIQN
‘
unfit: $1;gigsmnfagim
2 Claims. (CI. 60-14)
This invention relates to apparatus for the - being forced out of the compressor through check
transmission and control oi.’ mechanical energy, valve 9 and exhaust outlet ‘I. The amount of
force, power, or e?ect, from a source to any de—' ' compression depends upon the intake pressure
sired point.
5
P1v and the pressurevinto which the exhaust is
-
This invention has for its object the economical
transmission of mechanical power, with great
?exibility of power and speed and ?ne control.
' This transmission .of power is accomplished
through the .medium of an elastic gas, vapor, or
.10
?uid.
:
.
.
In thefollowing disclosure and claims the term
discharging or P2.
,
5
It is well known to engineers that the work
performed by the piston on the gas in this oper
ation'is equal to the integral of the pressure
multiplied by elemental changes in volume taken
around the cycle.
lil’
To illustrate:-assume we have a cylinder of .
“?uid” is used broadly to denote gas, vapor, air, ~ 100 cubic nches capacity, that it is ?lled with.
or compressible liquid, or othermaterial of like air at 15.lbs. per sq. inch and that no air can '
escape until we have compressed this air to a
characteristics.
‘
15
A compressor or pump is attached to the source pressure of 750 lbs. per sq. inch. Curve ill of. 15
of'power and this compressor takes the ?uid at Fig. 2 shows how the pressure within this cylin- '
der increases as the volume is decreased until
a pressure P1 and compresses it to a higher pres
sure P2, thus doing mechanical work on the ?uid ‘750 lbs. per sq. inch pressure is reached and then
and storing in the ?uid the energy of. compression. the air is exhausted. The statement in the pre
20 Another mechanism, known as a motor, takes this ceding paragraph simply states that the work 20
?uid and expands it back from pressure P2 to done by the cylinder on the air is proportional to
P1, thus extracting the power stored in the ?uid the area to the left and below the curve ill and
above the horizontal line of 15 lbs. per sq. inch
during compression.
and to the right of the vertical line representing
For many uses of this transmission it is desir
zero volume.
.
2
25 able to use compressed air for the working sub
In the formulae employed to explain my in
stance or elastic ?uid, and in many places in this
disclosure I shall refer to the elastic ?uid as the vention, the following characters appear and hay
the meanings here set forth:
.
air, but I do not limit my‘ invention to a trans
‘ P1=pressure of ?uid prior to compression.
mission using air. In fact, under certain condi
Pz=pressure of ?uid after compression.
'
30
30 tions, other vapors appear to be more desirable.
P or p=pressure of a ?uid, generally.
Referring to the drawings: Fig. 1 is a'sectional
V or v=volume of a ?uid, generally.
view of an air compressor; Fig. 2 is‘ a pressure
T=temperature of. a ?uid, generally.
’
volume diagram of an air compressor; Fig. 3 is
K=gas constant of a ?uid, generally. I
a graph showing the variation in work done by an
Cp=speci?c heat of a ?uid at constant pres- 35
35 air compressor when the initial volume and ?nal
sure.
.
pressure are held constant and the initial pres
Cv=specific heat of a ?uid at constant volume.
sure is varied; Fig. 4 illustrates one speci?c appli
W=work of compression of a ?uid.
cation of this transmission to a motor car; Fig. 5
e=the logarithmic exponent =2.'718.
is a diagram of the high pressure control system;
K1=a constant related to K.
40
.40 Fig. 6 is a diagram of the low pressure control
V1=volume of ?uid prior to compression.
system; Fig. "l is a horizontal longitudinal sec
'Y=Cp divided by Cv.
tional view of the air motor.
If the compression has been- performed iso
In Fig. 1 is diagrammed an ordinary air com
thermally or at constant temperature, the equa
pressor, having a crank shaft i, a crank 2, con
45 necting rod 3, piston l, which moves up and down tion of the curve is given by Equation 1, as 45
with the rotation of the crank-‘shaft inside of the follows:
cylinder 5 which the piston tightly ?ts. On the
down stroke of the piston 'air is drawn ito the
cylinder through the intake 6 and inlet valve 8
.59 and is compressed on the up stroke of the piston,
_ PVEKT
<1)
If the compression has taken place adiabatically
or without loss of any heat by the air, then the I
2
2,120,546
equation is that given by Equation 2, as follows:
'
PV'I =Constant
(2)
Curve ll, Fig. 2 represents the same equation
(No. 1 above) as curve I0, except that the initial
' pressure P1 is higher and the work done is repre
sented by area bounded by the lines P1=250 lbs.
per sq. inch; v=zero; Pz=750 lbs. per sq. inch;
and the curve II. Curve l2 represents the Equa
10 tion 2 above, at the same volume and pressure
_ascurve H.
to zero to ?nd the maximum value for W, results
in a maximum value appearing when
%=e=2.718
stant, we have:
1
.
‘P71’.
H 1
1 P2
1__1
1.2 __v.
7-P1
'7 ‘:1
1 Pi'YPZ
,7
Cp
7_P1
.
1O
.
-
1
.
—--1
(3)
(IF;
1__‘l
‘Y
Equation 3 states the well known gas law:
speci?c heat at constant pressure Cp, divided by
vspecific heat at constant volume Cv, is a constant.
This constant is represented by the Greek letter
'
Work (T constant) =W=f pdv
v Or, instead of integrating pdv around the cycle,
we may integrate vdp between the limits of P1
and P2, which is the same thing. rI’hus,
15
7
(7)
P1
20
For air, 7:1.4, and
.
.112
'
25
7
for W when
_ To obtain the expression for the work of com
pression at constant temperature, we proceed a
2
By equating to zero, we ?nd a maximum value
20 7. For air it is 1.4.
follows:
i 14
1
‘5:7
16
(s)
Di?erentiating Equation 5, holding P2 con
P1
becomes 3.2 for maximum work.
It is also evident from Fig. 3 that much more 25
work can be obtained from a given cylinder work
ing at a limited upper pressure P2 by proper se
lection of the initial pressure P1. For example,
the compressor diagrammed in Fig. 2 would ab
sorb less than 6000 inch lbs. per stroke when op 30
erating from atmospheric pressure to 750 lbs.
P2
av. 1026(3) (4)
The expression for the work of adiabatic com
pression is derived as follows:
per sq. inch as in curve l0 and it would absorb
more than 27,000 inch lbs. per stroke when oper
ating from 250 lbs. per sq. inch to the same upper
pressure.
'
35
‘ From the foregoing‘consideration, it is evident
that a power transmission can be designed using
previously compressed air for its low pressure
intake and compressing it over a comparatively
small pressure ratio to a higher pressure. Then,
after transmission through a pipe and control,
. the compressed air can be expanded through an
air motor back to ‘the same'pressure as‘ that from
which it started.
-
By this means a transmission of extreme light-,
ness, flexibility, compactness and economy and
having other desirable features, may be obtained.
If the ‘initial volume V1 and final pressure P2
50 are held constant, and if different values of the
input pressure P1 are taken, it will be found that
the work done by the compressor increases as
P1 increases up to a certain value and then de
creases as P1 approaches P2 in value. This is
55 shown graphically as an example in Fig. 3 where
V1 is taken as 100 cu. inches; P2 is taken as ‘750
lbs. per sq. inch; and the work W is plotted
againstthe different values of P1. Curve I3, Fig.
3 corresponds to Equation 4 and curve l4 corre
60 sponds to Equation 5. Both curves have maxima
at nearly the same value of compression ratio.
These maxima are obtained by differentiation of
Equations 4 and 5, obtaining 6 and 7 below.
Differentiating Equation 4, holding P2 con
65 stant, we have
>
70
21'
(1P1
Fig. 4 shows a speci?c application of this trans
mission to a motor car and, while I do not limit
my invention to automobile transmissions, it
will serve as an example to illustrate the princi
ples involved.
Referring to Fig. 4, 3! is a gasoline engine
having a radiator 32', carburetor 3'5, and exhaust
manifold 34%. This engine, being started in any 55
.of the usual manners, drives a small auxiliary
compressor 35. This compressor takes air from
the atmosphere through a cleaner, conventional
ly illustrated at 36, and throttle 3?, compresses
and discharges it through the pipe shown into 60
tank 3%. The cleaner 38 may consist of a. box
or can having supported, spaced from the bot
tom, av wire screen 105 above which is placed
bronze wool I08. The intake pipe 107, open to
the atmosphere, enters at the top, and the dis 65
charge pipe 85 passes out the bottom of the
cleaner. At the same time the power compressor
39 has been taking air from at, compressing and
discharging it into tank 40. This process is con
tinued until the pressure in tank 40 has been 70
built up to a certain predetermined value, for
example, 750 lbs. per sq. inch. When P2, the
pressure in tank 40, has reached this pressure
the connecting tube 45. and the tube 02 transmits
this pressure to the diaphragm 43 which expands
3
2,120,546
closing the throttle 44 of carburetor 33 and. ing rod 94 operates through a crank to turn rear
closing the intake to pump 39 by action of valve axle |0| to which are attached'driving wheels I02.
The entire mechanism up to throttle l5 and re
45.
The action of this control mechanism can be turn pipe I1 is automatic, the entire control. of
the automobile is‘. accomplished by manipulation
best understood by referring to Fig. 5. Dia
phragm 43 is secured at its outer edge toshell of the throttle |5 through lever 9| and control
l9 through lever 96. These are operated exactly
46 which is mounted on the car frame 99. At
tached to the center of diaphragm 43 is a rod in the same manner as a steam engine.
Many economies may be incorporated in this
41 on which are nuts 48 spaced somewhat apart.
system. For example: compressor 39 and tank
10 Carried between these nuts is bell crank 49 piv
38 may be placed out in front where, being in the
oted about a center 59 and operating on the but
ter?y valve 44 of carburetor 33 through links‘ 5| air stream incident to the travel of the vehicle,
and 52. 'The movement of diaphragm 43 due they would be cooled, thus reducing the volume
to pressure in shell 431s resisted by springs 53 of air- to be compressed, andv the compressor 39
and tank 38 are so, shown in this preferred ar
15 which is in compression between the diaphragm
and bracket 54 mounted on the car frame.v An rangement in Fig. 4. The high pressure air may
extension 55 of rod 41 passes through packing 56 be passed through a heat interchanger 29 in the
and carries a cone 51 that seats against seat exhaust manifold for the purpose of expanding
58 of valve 45 when diaphragm 43 is extended. the air, or reducing its density, by taking waste
20 Compressor 39 takes in air through pipe 59, valve heat from the exhaust gases. The pipe 91 andv
45, pipe 60, pipe 6|, from the low pressure tank engine l5 may be heat insulated to conserve this
38. It is obvious, then, that the action of the heat.
diaphragm 43 under pressure is to close the en
Another economy of the system is that the
gine throttle 44 and also the valve 45, choking gasoline engine is always working under high
torque and never running at high speed and
25 off the intake to the compressor and unloading it.
10
15
20
'
25
light load. As will be understood‘from the con
At this stage the engine idles under little or no
load and the pressures are maintained. When
P1 reaches its proper value, for example, 250 lbs.
trol operations explained, the engine is always
per sq. inch, then diaphragm 1| closes valve 3'_|
idling at closed throttle with the compressor un- ,
30 and no more air is pumped into the system until
some escapes.
Should pressure P1 become too
high, safety valve-‘l2 lets air‘ escape to atmos
phere through pipe 13.
In the same manner
safety valve 82, allows air. to escape from tank
40 through pipes 4|, 60, and ti back to low pres
sure tank 38, if .Pz should become too high.
either operating with full compressor load, or is
loaded.
,
.
links I9 are gradually shifted to the reverse posi
tion, thus causing air to be taken from tank 38, .35
compressed , by engine i6 and driven through
The action of the low pressure control can be
pipe 24, check valve 25 and pipe 4| back into
seen in detail byreferring to Fig. 6. Diaphragm
‘ii! is secured at its outer edge to shell ‘l4 which
tank 40. This continues until a higher pressure
is reached in tank 49, of, perhaps, 1200 lbs. per
sq. inch. Thereafter air escapes through relief
40 is mounted on the car frame. - Attached to the
30
A simple pipe 24 and check valve 25 shunting
valve l5 permits regenerative braking. For re
generative braking the valve I5 is closed and the
center of the diaphragm is rod ‘15 that extends valve 52 into tank 38 again with a small amount
through packing it and carries a cone ll that 4 of heating, due to the Thompson-Joule e?ect.
After this regenerative braking process, the ex
seats on valve seat ‘(18 of valve 31 when diaphragm
"H is extended. The movement of the diaphragm
is resisted by spring l3 which is in compression
between diaphragm ‘H and bracket 89 mounted
on the car frame. Compressor 35 takes air from
the atmosphere through cleaner 36, pipe 3 |_, valve
31, and pipe 82, discharging it through pipe 33,
and pipes 34 and ti into low pressure tank 38.
When the pressure in tank 38 reaches a pre
determined value the diaphragm it will have
extended, pushing the rod '35 upward and closing
the valve 37.
cess pressure is available for’ subsequent accelera
tion without any call upon the motor 3i. ’
45
While I have shown reciprocating motors and
compressors, I do not wish the invention in cer
tain of its aspects to be limited thereto, as me.
chines other than those with reciprocating pistons
.50
may be suitable.
I claim:
1. In combination, a reversible valve fluid
motor adapted for driving a vehicle, a prime
The compressor 35‘ is then un
mover, a ?uid compressor driven by said prime '
loaded and inactive until the pressure in tank » ‘mover, a high pressure connection between the
38 dram sumciently to permit the diaphragm
actuated valve to open and allow air to be taken
in by the compressor.
High pressure air from tank 49 is :brought back
exhaust port of- said compressor and the intake
port of said motor, a low pressure connection
between the exhaust port of said motor and the
intake port, of said compressor, a high pressure
reservoir in said high pressure connection, a low
pressure reservoir in said low‘pressure connection,
which expands the air and returns it to tank‘ means controlling the operation of said compres
33 through pipe H. Thus no air is lost from'the sor tending to maintain the pressure in said high ..
system.
pressure reservoir, substantially constant at a
Engine it is exactly like a steam or compressed normal value, a relief valve connected to said 65
through pipe 95, through thr'ottle valve 85, oper
ated by lever 9|, to the intake side of engine it
air engine having the usual cylinder 92, piston,
93, connecting rod 94, and valve mechanism i8
which through the valve link it controls the time
of cut-o? and admission as well as the exhaust
70 events through change of the phase relation of
valve 95 with respect to piston 93. A‘ standard
Stephenson link has been shown and since this
valve gear is so old and so well known to those
skilled in the art, it is not considered necessary
to explain its operation in detail." The connect
high pressure reservoir, said relief valve being
‘set to discharge at some pressure higher than
said normal pressure and adapted thereupon to
discharge ?uid into said low pressure reservoir,
means for reversing the valves on said motor to
cause the motor to act as a compressor, a throt
tle in said high pressure connection between said
high pressure reservoir and said motor, and valve
means adapted when said throttle is closed to
prevent the ?ow of ?uid from said. high pressure\ 75
4
2,120,648
reservoir into said motor but to permit ?uid constant at a normal value, a relief valve con
compressed by the motor to be pumped back into nected to said high pressure reservoir, said relief
the high pressure reservoir.
valve being set to discharge at some pressure
2. In combination, a vehicle, a valve controlled higher than said’ normal pressure and adapted
reversible fluid pressure motor for driving said thereupon to discharge ?uid into said low pres
vehicle, a prime mover, a compressor driven by =sure reservoir, means for reversing the valves on
said prime mover, a high pressure connection be
tween the exhaust port of said compressor and
the intake port of said motor, a low pressure con
10 nection between the exhaust port of said motor
and the intake port of said compressor, a high
pressure reservoir in said high pressure connec
tion, a low pressure reservoir in said low pressure
connection,‘means controlling the operation of
15 said compressor tending to maintain the pres
sure in said high‘pressure reservoir substantially
said‘ motor to cause the motor to act as a com
pressor, a throttle in said high pressure connec
tion between said high pressure reservoir and
said motor, and a check valved connection shunt 10
ing said throttle and acting independently of the
setting of said throttle to permit ?uid compressed
by the motor to be pumped back into the high
pressure reservoir.
‘
ROBERT CADY BURT.
15
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