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Патент USA US2074749

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March 23, 1937..
c. H. KIRBY
2,074,749
CARBURETOR
Filed March 18, 1933
2 Sheets-Sheet l
“4/
2 --Z 5-1,,
10
CHAELES H. ,Z/eaY,
-March
3, 1937,
c. H. KBRBY
’
2,074,749
Filed March 18, 1933
2 Sheets-Sheet 2
CARBURETOR
Patented 'Mar. 23, 1937
2,074,749
UNITED STATES '
PATENT OFFICE
2,074,749
CARBURETOR
Charles H. Kirby, Flint, Mich., assignor, by
mesne assignments, to Borg-Warner Corpora
tion, Chicago, 111., a corporation of Illinois
Application March 18, 1933, Serial No. 661,435
4 Claims.
This invention relates to carburetors for in
ternal combustion engines and has special refer
ence to simplifying the starting thereof under
varied temperature conditions by providing an
5 improved automatic control of the starting and
usual manual dash control of the choke valve.
It is an object of this invention to provide an
improved and simpli?ed automatic choke con
ure 4.
10 trol to assist in starting a cold engine as well
as to provide optimum warming up conditions
by automatically graduating the choking effect
l to the temperature of the engine and at the
same time providing a faster idling speed for
20
25
30
35
40
45
'
50
Figure 2 is an enlarged fragmentary plan view
of the manifolding system of Figure 1.
Figure 3 is an enlarged fragmentary elevation
of the thermostatic choke control.
Figure 4 is an enlarged fragmentary section
through the bypass valve taken on the line
IV--IV of Figure 3 with parts omitted.
Figure 5 is a section on the line V--V of Fig
warming up mixture as a substitute for the
1,5
(Cl. 261-39)
Figure 6 is a fragmentary section, with parts 10
in elevation, of the choke valve levers taken on
the line VI-VI of Figure 3.
As shown:
'
An internal combustion engine ill is shown
cold starting by increasing the available area in Figure 1 to illustrate a typical carburetor and
of the idling bypass as the required choking ef
manifolding system comprising an exhaust heat
fect increases in severity due to low tempera
ed riser l2 feeding an intake manifold lit, the
riser jacket being fed exhaust gases from an ex
tures.
haust manifold I4. The carburetor comprises
It is another object of this invention to pro
vide an improved and simpli?ed control of the generally a body member ll having an air in—
choking e?ect and mixture bypass that will re
take II’, and a ?oat bowl ‘I provided with a
move such controls from possible abuse by the fuel inlet 8. This showing is intended to be
operator, and yet fully compensate for varia
conventional, since the subject matter of this
tions in operating conditions which require dif
invention is not limited to updraft carburetors.
ferent degrees and duration of choking effect nor in fact to a separate choke valve, because
and idling speed to secure prompt warming up the air valve type of carburetor chosen for il
lustration can be choked by a suitable control
of a cold engine without stalling thereof.
applied directly to the air valve instead of using
It is another object of this invention to pro
vide an improved automatic choke and bypass a separate choke valve in the air inlet anterior
control adapted to start an engine without open
to the air valve.
As shown, a throttle valve lever I5 is mount
ing the usual throttle control whereby an in
creased idling speed will be provided to offset ed on the outer end of a throttle shaft 16 which
unfavorable operating conditions, and in which is located on the riser in preference to a loca
the opening of the throttle, as when a load is tion in the carburetor body, and carries the
applied to the engine, will be compensated for usual throttle valve (not shown). The throttle
by an increased opening of the choke valve to shaft 16 carries a multiple arm device 6, one
portion 6’ of which is arranged to engage an
prevent loading of the engine with an over
abutment 5 on the riser l2 to determine the
rich fuel and air mixture.
closed position of the throttle, another portion
This invention embodies a number of improve
6" of which is adapted for connection in a throtments over that disclosed in my copending ap
plication Serial No. 224,035, ?led October 5, 1927, tle operated rod which is not shown, and a third
and which issued as Patent No. 1,919,470, on portion 6”’ of which is connected by means of
a link 4 to a fuel control valve member 4'. The
July 25, 1933.
Other and further important objects of this particular location of the throttle shaft forms
invention will be apparent from the disclosures no part of the present invention but is menin the specification and the accompanying draw
tioned at this point because the desired bypass
ings.
passage I ‘I has its intake I8 adjacent the table
l9 surrounding and forming the venturi 20 for
This invention (in a preferred form) ‘is illus
the low speed nozzle 2|. The bypass passage i'l
trated in the drawings and hereinafter more ful
preferably extends up through the riser 12 to
ly described.
On the drawings: ,
an outlet 22 in the intake manifold I3, as by
Figure l is _a side elevation of an internal com
such an arrangement the fuel and air mixture
bustion engine and manifolding system provided
with a thermostatic choke control embodying the
55' features of this invention.
GI
15
20
26
30
35
40
45
50
1‘
in the bypass is heated by ?owing through the
heated riser and thus delivers a dry and stable
mixture unlikely to condense upon delivery to 5'
2
2,074,749
a cold manifold. While the long heated passage
I1 is desirable, the passage may discharge into
the riser or manifold at any point above the
throttle, the essential feature being that the
5 outlet 22 thereof is subjected to manifold suc
tion above the throttle, which suction, as is well
known, is a maximum under idling conditions
when the suction within the carburetor is often
ineffective to properly deliver and mix fuel from
10 the carburetor nozzles. This, as well as other
features of the carburetor, are disclosed in the
above mentioned copending application,
The bypass inlet I8 is controlled by a sleeve
valve 23, best shown in section in Figures 4 and
15 5. A side outlet port 24 is aligned with the pas
an increase in temperature to open the choke
valve and to uncoil in a counter-clockwise di
rection to lower the lever 4| and thus more or
less close the choke valve, The exact form and
location and the direction of operation of the
thermostat can of course be varied to suit dif
ferent installations, as the required action in
volves opening the choke valve upon the engine,
reaching the desired operating temperature and
closing the valve in proportion to the" cooling 10
of the engine to provide an increased ?ow of
mixture under unfavorable operating condi
tions.
Operation
sage I‘! to fully open the same and the valve
When the engine has been out of use for a
is also slightly notched as at 25 in Figure 5 to
su?icient time to cool off, the thermostat 44
maintain a restricted opening even when the
tends to uncoil in a counter-clockwise direction
valve is turned to its closed position. By main
20 taining a slight circulation through the bypass
passage at all times, stabilization and quick re
sponse to an opening movement of the valve
is secured, since quick response to valve move
ments is obtained if there is a moving column
of fuel and air mixture in the passage prior
to opening of the valve. The outer end 23' of
and force the lever 4| downwardly acting
through the rod 39 to move the choke valve into
its closed position. Such movement of the choke
valve also opens the bypass valve 23 by means
of the arm 32, link 34 and arm 35. Subsequent
starting of the engine will then involve only
closing the ignition and starting motor switches
to rotate the engine crankshaft, whereupon the
closed choke sets up the desired high suction
the sleeve valve 23 projects outwardly from the
body member H, as shown most clearly in Fig. 4
and is secured to an arm 35.
30
,
The carburetor air inlet horn 26 is provided
with an unbalanced butter?y choke valve 21
mounted on a shaft 28 offset to one side of a
major diameter of the air inlet in such a way
that high suction acting ,on the unbalanced
. choke valve tends to open the valve against the
on the usual fuel ori?ces and the open bypass
feeds the resulting rich fuel and air mixture
into the intake manifold above the throttle. The
bypass prevents cutting oil? the supply of fuel
and air mixture should the throttle remain closed
during the starting operation. The action of
the bypass, when fully open, serves to increase
the engine idling speed to that equivalent to a
resistance of a spring 29 (Fig. 6) tending to
vehicle speed as high as 15 or 18 miles per hour
cause an arm 30, rigidly mounted on the valve
in direct drive, the exact increase being of
course subject to choice by a suitable design of
shaft 23, to follow a floatingly pivoted lever
crank arm 3| as the latter is moved toward a
40 valve closing position, the crank arm 3| being
operated by a lever 33. The lever arm 32 is
provided integral with the arm 30, the arm
32 being connected by a link 34 to the arm 35
on the bypass valve 32, the arrangement being
such that the bypass valve is fully open when
the choke valve is closed and is closed, except
for the notch 25, when the choke valve is open.
The rigidly mounted arm 30 has a lug 36 yield
ingly held against the arm 3| by the spring 29
50 so that when the arm 33 is rotated in a counter
clockwise direction by a thermostatic control,
the unbalanced choke valve yieldingly follows
the arm 3|. However, high suction developed
against the closed unbalanced valve tends to ro
55 tate the valve and arm 30 in a clockwise direc
tion away from the arm 3| and this movement
is yieldingly limited by a spring biased plunger
31 in an integral offset 38 of the arm 30. The
foregoing described choke valve structure per
60 se is substantially similar to that disclosed in the
application of David Firth, Serial No. 575,720.
filed November 19, 1931 entitled “Automatic
choker valve”, which matured into Patent
1,966,201, granted July 10, 1934.
The choke valve operating lever 33 is linked
by a rod 39 to the free end 40 of a thermostati
cally operated lever which is pivoted at 42 in
a housing 43 mounted on the exhaust manifold.
The housing contains a coiled bi-metallic
thermostat 44 anchored at one end in an ad
justable mounting 45 and carrying a crank arm
46 at the other end which is pivoted at 41. The
lever 46 engages a pin 48 on the crank arm 4|
to move the latter. As shown, the thermostat is
75 intended to coil up in a clockwise direction with
the bypass area.
.
a
As the thermostat operates, through tempera
ture increases due to warming up the engine, to
gradually open the choke valve, the bypass con
tinues to function at a proportionately decreased
rate until the bypass valve reaches its limit of
closing movement when the notch 25 still permits 45
a minimum ?ow adapted to stabilize idling con
ditions at the minimum idling speed desired with
a motor thoroughly warmed up.
If the throttle were to be opened while the
choke valve was still substantially closed, the in 60
creased suction on the unbalanced valve would
cause the same to open moving the lever 3| to
wards the yielding stop 31 in opposition to the
spring 29, thus admitting su?icient additional air
to allow the engine to carry a substantially nor
mal load without excessive over-enriching of the
fuel and air mixture with consequent “loading” of
the engine.
It will thus be seen that I have invented an
improved thermostatic choke and bypass con
trol adapted to automatically supply a proper fuel 60
and air mixture to an internal combustion engine
for starting and warming up the same and where
in the idling speed of the engine is automatically
increased to overcome unfavorable operating tem
peratures which would cause stalling at the low 65
idling speeds desirable and satisfactory for use
with a warm engine.
I am aware that many changes may be made
and numerous details of construction may be va
ried through a wide range without departing from
70
the principles of this invention, and I, therefore,
do not purpose limiting the patent granted here
on otherwise than necessitated by the prior art.
I claim:
76
‘2,074,749
.
3
3.
In
combination
with
a
carburetor
and
a
1. In combination with a carburetor for an
internal combustion engine, including a choke manifolding system for an internal combustion
valve and a throttle valve for said carburetor, engine, including a choke valve and a throttle
valve for said carburetor, a bypass passage around
a bypass passage around said throttle valve loca
said throttle valve location, the discharge end of
tion, the discharge end of said passage being sub
jected to the suction above the throttle while said passage being subjected to the suction above
the throttle while the inlet end of said passage
the inlet end of said passage is so positioned rela
tive to the carburetor fuel delivery nozzles as to is so positioned relative to the carburetor fuel
delivery nozzles as to pick up a rich fuel and
pick up a rich fuel and air mixture therefrom, a
valve controlling said bypass passage, operating air mixture therefrom, a valve controlling said
linkage connecting said valve to the choke valve bypass passage, operating means having a yield~
to open said valve when the choke valve is closed, ing connection to the choke valve to permit partial
thermostatic means responsive to temperature opening of said valve in response to suction there
on, linkage connecting said operating means to
variation and operating linkage from said ther
the bypass valve to open said bypass valve when
- mostatic means to said choke valve, the thermo
static means being arranged to close said choke the choke valve is yieldingly closed, and thermo
valve and thereby open said bypass valve at low static means arranged to operate the choke valve
in accordance with temperature conditions.
temperatures and to open said choke valve at nor
4. In combination with a carburetor and a
mal operating temperatures.
2. In combination with a carburetor for an ‘manifolding system for an internal combustion
internal combustion engine, including a choke engine, including a choke valve and a throttle
valve and a throttle valve for said carburetor, a valve for said carburetor, a bypass passage around
said throttle valve location, the discharge end
bypass passage around said throttle valve loca
of said passage being subjected to the suction
tion, the discharge end of said passage being sub
jected to the suction above the throttle while the above the throttle while the inlet end of said
passage is so positioned relative to the carburetor
inlet end of said passage is so positioned rela
tive to the carburetor fuel delivery nozzles as to fuel delivery nozzles as to pick up a rich fuel and
pick up a rich fuel and air mixture therefrom, a air mixture therefrom, a valve controlling said
valve controlling said bypass passage, said valve bypass passage, said valve being slightly open at
all times to stabilize the mixture ratio at low
0 being slightly open at all times to stabilize the
idling speeds, operating means having a yield
mixture ratio at low idling speeds, operating link
age connecting said valve to the choke valve to ing connection to the choke valve to permit par
open said valve when the choke valve is closed, tial opening of said valve in response to suction
thermostatic means responsive to temperature thereon, linkage connecting saidv operating means
to the bypass valve to open said bypass valve
1-3 variations and operating linkage from said ther
when the choke valve is yieldingly closed, and
mostatic means to said choke valve, the thermo
static means being arranged to close said choke thermostatic means arranged to operate the choke
valve and thereby open said bypass valve at low valve in accordance with temperature conditions.
temperatures and to open said choke valve at nor
CHARLES H. KIRBY.
49 mal operating temperatures.
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