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Патент USA US2113637

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April 12, 1938.
2,113,637
B. S. AIKMAN
COMPRESSOR UNLOADER
Filed Sept. 4, 1935
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INVENTOR
EURTDN s. AIKMAN
BY
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ATTOR NEY
I
2,113,637
' Patented Apr. 12,1938
UNITED STATES
PATENT orFici-z
2,113,637
COMPRESSOR UNLOADER
-Burton s. Aikman, Wilkinsburg, Paaassignor?to
The Westinghouse Air Brake Company, Wil
merding, Pa., a corporation of Pennsylvania
Application September 4, 1935, Serial No. 39,133
(Cl. 230-24)
, 8 Claims.
This invention relates to a control system for
a ?uid compressor driven by an internal com
struction and is provided with a fuel inlet passage
or manifold 5 through which fuel is supplied to
bustion engine.
the cylinders of the engine.
.
It is the principal object of this invention to
5 provide a control system for a ?uid compressor
driven by an internal combustion engine, the con
trol system comprising unloading means asso
ciated with the compressor and operated by the
vacuum in the inlet passage of the engine.
10
A further object of this invention is to provide
a compressor control system of the type referred
to and which incorporatesmeans responsive to
the pressure of the ?uid compressed by the com
pressor and controlling a communication between
15 the engine intake passage and the unloading
means, whereby the unloading means is controlled
by the engine intake pressure in response to vari
ations in the pressure of the ?uid compressed by
the compressor.
20
'
'
The compressor I comprises a body having a
crank case chamber I0 formed therein, and hav- 5
ing a cylinder ll associated therewith and pro
vided with a bore in which is reciprocably mounted
a piston It. The upper end of the bore in the
cylinder llv is closed by means of a cylinder ‘head
l5, which has a chamber it formed therein, and 10
in which is positioned an exhaust valve l8 which
is urged by means of a spring 22 into engagement
with a seat I 9'surrounding a passage 20 com
municating with the chamber above the piston
l4 and with the chamber i6 in the cylinder head 15
I 5.
The chamber I6 is connected with a reser
voir 25 by way of a pipe 26. -
_
The wall of the cylinder I I has an annular pas
sage 30 formed therein surrounding the bore in
>
Another object of this invention is to provide
a compressor control system of the type referred
to and which incorporates means subject to the
pressure of the ?uid compressed by the com
pressor and subject also to the vacuum in the
25 inlet passage of the engine and controllinga pas
the cylinder and communicating with this bore by
way of a plurality of ports 32 which extend 2° .
through the wall of the cylinder and which com- . ’
municate with the bore at a point just above
the top of the piston I 4, when the piston is at
the lower end of its range of movement. A pas-'
sage‘ 35 is provided in the wall of the cylinder ll 25
sage between the engine inlet passage and the un
loading means.
A further object of this invention is to provide
and communicates with the crank case chamber .
l0 and with the'passage 30.
.
A combined air strainer and compressor un- '
a compressor control system of the type referred
30 to and having means subject to the pressure of the : loading'device 36 is provided and controls the
?uid compressed by the compressor, said means
being biased to a position to maintain the com
pressor loaded and being movable on a predeter
mined increase in the pressure of the ?uid com
35 pressed by the compressor to a position to effect
unloading of the compressor, said means being
subject also to the vacuum in the engine inlet
28w of ?uid from the atmosphere to the passage .
The combined air strainer and unloading'device
36 comprises a body section indicated generally
by the reference character 39, and having a sub- 35
stantially cylindrical peripheral portion 39 and a
central portion 40 which is connected with the
" passage on movement to the unloading position, - peripheral portion 39 by means of a radially ex
tending portion 4|.
whereby said means is maintained invsaid unload
40 ling position until the pressure of the ?uid com
pressed by the compressor is reduced to a value
substantially less than that required to e?’ect
movement of ,the said means from the loading
position to the unloading vposition.
45
other objects of the invention and features of
novelty willv be apparent from the_ following
_
The central portion 40 has a valve chamber 43 40
formed therein in which is mounted a valve 45
having a ?uted stem positioned in a bore extend
ing through the central portion 40, and having a
head adapted to seat on a seat surrounding the
bore in which the ?uted stem is positioned.
45'
A pair of annular perforated members 41 and
description taken in connection with the accom
. panying drawing, the-single ?gure of which is a
tral portion-40 and the peripheral portion 39 of
diagrammatic-view, partly in section, of a ?uid
the body section 98 and have placed between
48 are positioned in the cavity between the cen
50 compressor equipped with one embodiment of the
control system provided by my invention.
them a quantity of a suitable air straining mate- 50
‘
rial. such as curled hair, indicated at 49. The
member 481s held in position by means of the
cover plate 5|, which has a projecting portion 53
Referring to the drawings compressor is indi
cated generally by the reference character. I and
is driven by an internal combustion engine 3,, formed thereon and extending within-the periph
65 which may be of any suitable well-known con-v eral portion 39 andengaging the member 48.
55
2,118,687
'2
by means of the casing section 55 which has a
pheric pressure as it is in communication with
the chamber 99 of the control device 89 by way
of the pipe I 95, and the spring 61 will maintain
threaded end portion which is screwed into
threads in the wall of the valve chamber 43 in
in the drawing, in which position communication
The cover plate 5| is held against the margin of
the peripheral-portion 39 of the body section 38
the body section 38, and which is provided with
> -an annular ?ange 56 engaging the inner margin
of the cover plate 5|.
The exposed end of the
casing section 55'is threaded and is adapted to be
10 screwed into a threaded opening in the wall of the
cylinder II. so that a passage 58 through the
casing section 55 communicates with the passage
'39 in the wall of the cylinder I I.
I
The combined air strainer and compressor un
loading device 36 includes a movable abutment in
1,5 the
form of a diaphragm 69, clamped between the
casing section 39 and a casing section. 62, and
having on one side thereof a chamber 64 in which
is mounted a follower 95 which engages one side
20 of the diaphragm 69 and to which is secured the
end of the stem of the valve 45. A spring 91
is also mounted in the chamber 64 and engages
the follower 55 so as to normally urge the follower
to move to the left and thus move the valve 45
I
25 away from its seat.
The diaphragm 69 has on‘the opposite side
thereof a chamber, 69 which is constantly con-'
the valve 45 in the position in which it is shown
is permitted between- the valve chamber ,43 and
the atmosphere through the air straining means
49. This permits ?uid to be supplied to the pas
sage 39 from the atmosphere, and effects loading
of the compressor.
10
When the engine 3 is started the crank shaft
of the compressor is rotated, and the piston 14
is caused to reciprocate in the bore in the cylinder
I I. On upward movement of the piston I4 from
the position in which it is_shown in the drawing, 15
the piston cuts oil’ communication through the
ports 32, and on further movement of the piston
the fluid in the chamber above the piston is com
pressed and the pressure of the ?uid acting upon
the exhaust valve I8 causes this valve to be
moved upwardly away from the seat I9 against
the spring 22 so that air ?ows from the piston
chamber to the exhaust valve chamber I9, and
therefrom by way of the pipe 26 to the reservoir
25
25.
On downward movement of the piston I4 the
exhaust valve I9 is moved into engagement with
nected with a chamber ‘I9 on one side of the air its seat I9 by the spring 22 so as to cut off the
straining means 49 by way ‘of passages ‘I2, and . ?ow of ?uid from the exhaust valve chamber I9
30 which communicates with the valve chamber 43
by way of the bore in which the valve 45 is
mounted. The chamber 14 on the opposite side
of the air straining means 49- is in communica
tion with the atmosphere by way of a passage 16.
The control system provided by this invention
35
includes a control device, indicated generally by
the reference character 89, and which as shown
comprises amovable abutment in the form of
a diaphragm 8| clamped between a casing section
40 92 and a body section 94, and having on one side
thereof a chamber 86 which is constantly cone
nected to the main reservoir 25 by way of a pipe
81. The diaphragm 8| has on the other side
thereof a chamber 99 in which is positioned a
.
45 plunger 92.
The body section 94 has a wall 9| extending
across the chamber 99 and having a passage 94
to the chamber in the bore in the cylinder II 30
above the piston I4, with the result that a par
tial vacuum is created in the chamber above the
piston. When the piston I4 moves to its lower
position, in which position the ports 32 are
again uncovered, ?uid ?ows from the passage 35
39 through the ports 32 to the chamber above the
piston. This produces a reduction in the pres
sure of the air or‘ ?uid in the passage 39 and
causes air or ?uid to ?ow to this passage from
the valve chamber'43, and on a reduction in the 40
pressure of the ?uid in‘the valve chamber-43,
?uid will be supplied thereto from the atmos
phere by way of the passage ‘I6, the chamber 14,
through the air straining means 49 to the cham
ber ‘I9, and therefrom by way of the passages 45
12 to the ‘chamber 69, and thence past the ?uted
stem of the valve 45 to the valve chamber 43.
On the next upward stroke of the piston I4 the
formed therein which is constantlyconnected '
with the engine ~inlet passage 5 by way of a air or ?uid which is in the chamber above the
piston I4 will be compressed, and this process
50 pipe 95. The end of the passage 94 is surrounded will be repeated with each revolution of the crank 50
by a seat 96 and a ballvalve 98 is held in engage
'
.
.
ment with the seat 96 by means of a spring 99 shaft of the compressor.
During operation of the engine 3 a partial
acting through a valve cage I99. The valve cage
I99 is moved against the spring. 99 by means of vacuum will be established in the engine inlet
55 the plunger 92 acting through the push pins I92,
which extend through openings in the wall 9I
which extends across the chamber 99.
The chamber 99 is constantly connected with
the chamber 64 of the combined air strainer and
compressor unloading device 36 by way of a pipe
I95, and is constantly connected with the atmos
phere by way of a passage I96, which has a ?ow '
capacity substantially less than that of the pas
sage 94 and pipe 95 by means of which the cham
.65 ber 99 is connected to the engine inlet passage 5.
In the operation of the system, assuming that
the compressor is idle and that the reservoir 25
is at atmospheric pressure, the spring 99 of the
control device 99 will maintain the ball valve
passage or manifold 5,'and this vacuum will, be 55
communicated to the pipe 95 and the passage 94,
but it will not be communicated to the chamber
99 in the control device 89 at this time as ‘the
ball valve 98 is held in engagement with the
seat 96 so as to cut oif communication between
the passage 94 and the chamber 99.
» >
_After a period of operation of the compressor
the pressure of the ?uid in the reservoir 25 will
have increased to a predetermined value such
that the pressure of the ?uid in the ‘chamber 86 65
exerts a force on the diaphragm 8| which exceeds
that exerted by the spring 99, acting on the other
side of the diaphragm 9| through the valve cage
I99, the push pinsI92, and the plunger 92. The
98 in engagement with the seat 96, while the ' diaphragm 8I will ‘thereupon be forced down 70
chamber 99 will be at atmospheric pressure as it wardly ‘against‘the spring 99, and the ball valve
is .in communication with the atmosphere byway
element 99 will’ be moved by gravity away from
of the passage
theseat 96.‘
I96.
>
-
v
'
'
_
~
Thechamber 64 of the combined air strainer
-
i
‘
‘Y
As soon as the'ball valve 99 moves away from
75 and unloading device 36 ‘will also beat ‘at-most f the seat 99, the ?uid which is inthe chamber 99
I
3
2,118,687‘
will be drawn through the passage 94 and-the
pipe 95 to the inlet passage 5, and a partial
vacuum will be established in the chamber 99,
as the rate at which ?uid is withdrawn from
the chamber 99 through the passage 94 and the
pipe 95 substantially exceeds that at which ?uid
is supplied to the “chamber 99 from the atmos
phere by way of the passage I96.
The resulting reduction in the pressure of the
10 ?uid in the chamber 99 increases the force effec
phere to the" valve chamber 93, thus eifecting
loading of the compressor.
The cylinder wall of the compressoris pro
vided with a passage 35, which extends between
the passage 39 and the crank case chamber l9, C21
so that on a reduction in the pressure of the
?uid in the passage 39 as result of operation of
the compressor, ?uid will flow from the crank
case chamber ill to the passage 39.
This pro-'
duces a partial vacuum in the crank case cham
tive to urge the plunger 92 downwardly and the ber l9 and causes air to tend to flow into the
plunger will thereafter be moved very rapidly crank case, chamber from the atmosphere
until it engages the wall 9|, which limits down ' through the joints in the walls of the crank case,
ward movement of the plunger 92.'
i
thereby opposing the escape of lubricant from
It will be seen, therefore, that as soon as the
valve 99 is moved away from the seat 96 as a
result of an increase in the pressure of the ?uid
in the reservoir 25, it will be moved to the
full open position very rapidly due to the re~
20 duction in the pressure of the ?uid in the cham
ber 99 which occurs when the valve 99 is moved
15
away from its seat.
I
'
On a reduction in the pressure of the ?uid in
the chamber 99, a similar reduction in the pres
25 sure of the ?uid in the chamber 69 will be ef
fected, as the chamber 64 is in communication
with the chamber 99 by way of ‘the pipe Hi5,
the crank case through the joints in the walls 15
of the crank case chamber.
From the foregoing it will be seen that the
compressor control system provided by this in
vention incorporates means responsive to the
pressure of the ?uid compressed by the com 20
pressor and to the pressure of the ?uid in the
inlet passage of the engine which drives the com
pressor; this means controlling the loading and
unloading of the compressor.
-
It will be seen also that the unloading con
and, on a reduction in the pressure of the ?uid
trol means is responsive only to the pressure of
the ?uid compressed by the compressor when this
pressure is below a predetermined value, and
in the chamber 69, the diaphragm 69 will be
that upon an increase in this pressure to a value
30 moved to the right against the spring 611 by the
pressure of the atmosphere in the chamber 69
on the opposite side of the diaphragm, and the
, valve 96 will be moved into engagement with
" the seat surrounding the passage in which the
35 valve is mounted, thus cutting oif the ?ow of
?uid from the atmosphere to the valve chamber
25
above said predetermined value the control means
is rendered subject to the pressure of the ?uid
in the engine inlet passage and is operated to
effect unloading of the compressor, whereby the
control means is maintained in the position to
effect unloading of the compressor until the pres 35
sure of the ?uid compressed by the compressor
falls to a value substantially lower than that
99. This cuts off the supply of ?uid to the com
pressor and causes the compressor to be unloaded,
with the result that on continued operation of
the
compressor no ?uid will be compressed by it
49
as long as the valve 45 is in the seated position.
The compressor will continue to run in the
unloaded condition until the pressure of the ?uid
in the reservoir 25 is reduced to a value such that
the force exerted by the diaphragm M as a result
45 of the?uid under pressure in the chamber 96
acting upon it, and as a result of the partial
vacuum in the chamber 99 acting upon it, is less
position to the open position, it will be moved
very rapidly after the initial movement thereof
than the force exerted by the spring 99 acting
through the plunger 92 and tending to move the
away from the closed position, and that on move
ment of this valve means to the closed position
diaphragm upwardly.
from the open position it will be held ?rmly in 50
When the‘pressure of the ?uid in the reservoir.
95 has been reduced to this value the ball valve
99 will be moved into engagement with the seat
engagement with its seat.
50
96 so as to cut o? communication between the
55 passage 99 and the chamber 99. This cuts oil
communication between the passage 99 and the
chamber 99, and permits the chamber 99 to be
restored to atmospheric pressure‘ by the ?ow of
?uid from the atmosphere through the passage
60
l96. When the chamber 99 is restored to atmos
pheric pressure the force exerted by the dia
phragm 9i acting through the plunger 92 and
tending to move the valve cage I99 downwardly
65 against the spring 99 will be decreased, with
the result that the spring 99 will hold the ball
_ valve 99 ?rmly in engagement with the seat 96.
When the chamber 99 is restored to atmos
pheric pressure a similar increase will be e?ected
70 in the pressure of the ?uid in the chamber 64 of
the combined air strainer and unloading device
36, and the diaphragm 69 will thereupon be
moved to the left by the spring 61 so that the
valve 45 will be moved away from its seat to
76 again permit the ?ow of ?uid from the atmos
originally required to effect movement of the
control means to a position to effect unloading
of the compressor.
7
This insures that there will be a pressure dif 40
ferential between the pressure at which the com
pressor is unloaded and the pressure at which
the compressor is loaded. This construction also
insures that when the valve means of the un
loading control means is_moved from the closed 45
-
It will be seen also that the control device
provided by this invention opens a passage
through which air is supplied to the engine inlet
passage when the control device moves to the
position in which the compressor is unloaded.
The system operates, therefore, to vary the mix
ture of the ?uid supplied to the engine in re
sponse to the loading and unloading of the com
pressor, the supply of air being increased when 60
the compressor is unloaded, at which time the
load on the engine is at a minimum. As soon as
the compressor is loaded, however, the supply of
air to the engine inlet passage through this pas
sage is cut off, and this has thee?ect of en
65
riching the mixture of the fuel supplied to the
engine when the engine is subjected to load.
While one embodiment of the control system
provided by this invention has been illustrated
and described in detail, it should be understood 70
that the invention is not limited to these details
of construction, and that numerous changes and
modi?cations may be made without departing
from the scope of 'the following claims.
Having now described my invention, what I
9,118,637
claim as new and desire to secure by Letters Pat
ent, is:
1. In a control system for a ?uid compressor
driven by an internal combustion engine the com
bination of a fuel inlet passage for the engine,
unloading means associated with the compressor,
a control device for controlling operation of the
unloading means, said control device comprising
means subject to the pressure of the ?uid com
10 pressed by the compressor and biased to a posi
tion to e?ect loading of the compressor and being
moved to a position to effect unloading of the
compressor on a predetermined increase in the
and controlling communication between said
chamber and the engine inlet passage. '
5. In a control system for a ?uid compressor
driven by an internal combustion engine, in com
bination, a fuel inlet passage for the engine, un
loading means for the compressor, biasing means
associated with the unloading means and yield
ingly urging said unloading means to a position
to effect loading of the compressor, movable
abutment means subject to the opposing pres 10
sures of the atmosphere and of the ?uid inav
chamber and operate on a reduction in the pres
sure of the ?uid in said chamber to effect move
ment of the unloading means to a position to un
load the compressor, means for supplying ?uid 15
pressure of the ?uid compressed by the compres
15 sor, said means being subject to the pressure of
the ?uid in the engine inlet passage after ‘move-_ from the atmosphere to said chamber at a given
ment away from the loading position, whereby rate, and movable abutment means subject to
the pressure required to move said means from the opposing pressures of the ?uid in said cham
the loading position exceeds the pressure required ‘ ber and of the ?uid compressed by the compressor
20 to maintain said means away from the loading
and controlling a communication between said 20
position, and whereby the compressor remains un
chamber and the engine inlet passage through
by the compressor is reduced to a value less than
that required to effect unloading of the compres
engine inlet passage at a rate more rapid than
said given rate.
loaded until the pressure of the ?uid compressed _ which ?uid may flow from “said chamber to the
25
sor.
'
6. In a control system for a ?uid compressor 25
V
2. In a control system for a ?uid compressor
' driven by an internal combustion engine, in com
bination, a fuel inlet passage for the engine, un
loading means for the compressor, movable abut
30 ment means subject to the opposing pressures of
the atmosphere and of the ?uid in a chamber
for controlling operation of the unloading means,
means for supplying ?uid to said chamber, and
movable abutment means subject to the opposing
35 pressures of the ?uid in said chamber and of the
?uid compressed by the compressor and control
ling communicationbetween said chamber and
‘the engine inlet passage.
3. In a control systemior a ?uid compressor
40 driven by an internal combustion engine, in com
bination, a fuel inlet passage for the engine, un
loading means for the compressor, movable abut
ment'means subject to the opposing pressures of
the atmosphere and of the ?uid in a chamber
45 for controlling operation of the unloading means,
means for supplying ?uid from the atmosphere to
said chamber at a given rate, and movable abut
ment means subject to the opposing pressures of
the ?uid in said chamber and of the ?uid com
pressed by the compressor and controlling a com
munication between said chamber and the engine
driven by an internal combustion engine, in com
bination,‘ a fuel inlet passage for the engine, un
loading means for the compressor, yielding means
urging said unloading means to a position to
effect loading of the compressor, movable abut
30
ment means subject'to and operated on a reduc
tion in the pressure of the ?uid in a chamber _
to move the unloading means to a position to
effect unloading of the compressor, means for
supplying ?uid to said chamberyand means re 35
sponsive to the opposing pressures of the ?uid
compressed by the compressor and of the ?uid in
said chamber for establishing communication be
tween said chamber and the fuel inlet-passage.
7. In a control system for a ?uid compressor 40
driven by an internal combustion engine, in com
bination, a fuel inlet passage for the engine, un
loading means for the compressor, a movable
abutment subject to the pressure of the ?uid in a
chamber for operating the unloading means, 45
means for supplying ?uid to said chamber, valve
means for controlling communication between
saidqchamber and the fuel inlet passage, means
responsive to the pressure of the ?uid compressed 50
by the compressor for moving said valve means to
a position to establish communication between
inlet passage through which ?uid may ?ow from I said chamber and said inlet passage, and means
the chamber to the engine inlet passage at a
rate more rapid than said given rate.
55
4. In a control system for a ?uid compressor
driven by an internal combustion engine, in com
bination, a fuel inlet passage for the engine, un
loading means for the compressor, biasing means
associated with the unloading means and yield
60 ingly urging said unloading means to a position
to effect loading of the compressor, movable abut
ment means subject to the opposing pressures of
the atmosphere and of the ?uid in a chamber and
‘ operated on a reduction in the pressure of the
65 ?uid in said chamber to effect movement of the
unloading means to a position to unload the com?
pressor, means for supplying ?uid to said cham
- ber, and movable abutment means subject to the
opposing pressures of the ?uid in said chamber
70 and‘ of the ?uid compressed by the compressor
subject to pressure of the ?uid in said chamber
and opposing movement of the valve means by 55
the means responsive to the pressure of the ?uid
compressed by the compressor.
8. In a control system for a ?uid compressor
driven by an internal combustion engine having a
fuel inlet passage associated therewith, a movable 60
abutment subject to and operated on a reduction
in the pressure of the ?uid in a chamber to unload
the compressor, means for supplying ?uid to said
chamber, and a movable abutment subject to the
opposing pressures of the ?uid compressed by the 65
compressor and of the ?uid in said chamber and
controlling a communication between said cham
ber and said inlet passage.
I
.
BURTON S. m .
70
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