U.S. patent number 3,744,346 [Application Number 05/235,708] was granted by the patent office on 1973-07-10 for transmission controlled power enrichment override apparatus.
This patent grant is currently assigned to General Motors Corporation. Invention is credited to Howard E. Chana, Hugh L. Miner, Albert L. Thompson.
United States Patent |
3,744,346 |
Miner , et al. |
July 10, 1973 |
TRANSMISSION CONTROLLED POWER ENRICHMENT OVERRIDE APPARATUS
Abstract
A switch is closed by an automatic transmission when in a high
drive ratio to operate a solenoid that positions a fuel metering
rod in the fuel delivery passage of a carburetor to effect a
minimum flow area through a metering orifice. This overrides the
normal operation of the carburetor power enrichment system that
otherwise increases the flow area as the engine vacuum falls.
Inventors: |
Miner; Hugh L. (Grand Blanc,
MI), Chana; Howard E. (Flint, MI), Thompson; Albert
L. (Grand Blanc, MI) |
Assignee: |
General Motors Corporation
(Detroit, MI)
|
Family
ID: |
22886614 |
Appl.
No.: |
05/235,708 |
Filed: |
March 17, 1972 |
Current U.S.
Class: |
477/111; 123/438;
261/DIG.74; 261/69.1 |
Current CPC
Class: |
F01K
7/00 (20130101); F02M 7/20 (20130101); F24F
5/00 (20130101); Y10T 477/68 (20150115); Y10S
261/74 (20130101) |
Current International
Class: |
F24F
5/00 (20060101); F02M 7/00 (20060101); F02M
7/20 (20060101); F01K 7/00 (20060101); B60k
021/00 (); F02m 007/20 (); F02d 009/00 () |
Field of
Search: |
;74/859,860
;123/106,119R ;261/69R |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Myhre; Charles J.
Assistant Examiner: Perry; Thomas C.
Claims
What we claim as new and desire to secure by Letters Patent of the
United States is:
1. In combination with an internal combustion engine and a
carburetor providing an air fuel mixture thereto:
a. fuel metering valve means having a member movable in response to
engine vacuum to normally provide a variable metered fuel rate to
said engine in response to varying fuel enrichment demands,
b. fuel metering valve stop means having a first position out of
the path of travel of said member permitting unrestrained movement
of the same and a second position in the path of travel of said
member so as to limit the fuel enrichment of said first means
irrespective of the vacuum signal; and
c. means responsive to vehicle speed operative to position said
stop means in said first position under low speed conditions and in
said second position under higher speed conditions.
2. In combination with an internal combustion engine and a
carburetor for providing an air fuel mixture thereto:
a. fuel metering valve means operable to normally provide a
variable metered fuel rate to said engine in response to varying
fuel enrichment demands, said fuel metering valve means being
positionable to provide a flow area condition intermediate a
minimum flow area condition and a maximum flow area condition;
and
b. fuel metering valve override means responsive to a signal
indicating vehicle speed and including energizable solenoid means
and transmission controlled switch means for energizing said
solenoid, said transmission controlled switch means having a first
condition to cause said solenoid to normally allow said metering
valve means to be positioned in said intermediate flow area
condition and a second condition to cause said solenoid means to
position said metering valve means in said minimum flow area
condition.
3. In combination with an internal combustion engine for providing
a source of vacuum and a carburetor for providing an air fuel
mixture to said engine:
a. a vacuum unit for advancing the timing of ignition in said
engine when said vacuum is communicated to said vacuum unit;
b. fuel metering valve means operable to normally provide a
variable metered fuel rate to said engine in accordance with
varying fuel enrichment demands, said fuel metering valve means
being positionable to provide a flow area condition intermediate a
minimum flow area condition and a maximum flow area condition;
c. solenoid means operable to normally allow said metering valve
means to be positioned in said intermediate flow area condition and
to otherwise override said fuel metering valve means by positioning
said fuel metering valve means in said minimum flow area condition;
and
d. control means responsive to a signal indicating vehicle speed
for controlling said solenoid and said vacuum advance unit and
having a first condition operable to normally prevent said vacuum
from being communicated to said vacuum unit while also causing said
solenoid means to normally allow said metering valve means to be
positioned in said intermediate flow area condition and a second
condition for permitting said vacuum to be communicated to said
vacuum unit while also causing said solenoid to position said
metering valve means in said minimum flow area condition.
4. In combination with an internal combustion engine for providing
a source of vacuum signals and a carburetor for providing an air
fuel mixture to said engine:
a. a transmission with an input connected to said engine and an
output connected to a load, said transmission having variable drive
ratio means for varying the ratio of the speed of the output to the
speed of the input from a high drive ratio to lower drive
ratios;
b. fuel metering valve means operable to normally provide a
variable metered fuel rate of said engine in accordance with
varying fuel enrichment demands, said fuel metering valve means
being positionable to provide a flow area condition intermediate a
minimum flow area condition and a maximum flow area condition;
c. solenoid means operable to normally allow said fuel metering
valve means to be positioned in said intermediate flow area
condition and to otherwise override said fuel metering valve means
by positioning said metering valve means in said minimum flow area
condition; and
d. transmission controlled switch means having a first condition
for causing said solenoid means to normally allow said fuel
metering valve means to be positioned in said intermediate flow
area condition and a second condition when said transmission is in
said high drive ratio to cause said solenoid means to position said
fuel metering valve means in said minimum flow area condition.
5. In combination with an internal combustion engine providing a
source of vacuum, said engine connected with the input of an
associated transmission the output of which is connected to a load,
said transmission having a variable ratio drive means for varying
the ratio of the speed of the output to the speed of the input from
a high drive ratio to lower drive ratios:
a. fuel delivery means for providing fuel to said engine and
including a fuel delivery passage, a fuel flow orifice in said
passage and a fuel metering rod translatable in said orifice to
effect a flow area intermediate a minimum flow area and a maximum
flow area, said minimum flow area allowing sufficient fuel to be
provided to said engine for normally operating said transmission in
said high drive ratio;
b. fluid motor means connected with said metering rod and
communicating with said source of vacuum for positioning said fuel
metering rod to effect said minimum flow area when said vacuum is
above a predetermined vacuum and for positioning said metering rod
to effect said intermediate flow area as said vacuum drops below
said predetermined vacuum while said transmission drive ratios are
less than said high drive ratio;
c. transmission controlled switch means responsive to said variable
drive ratio means and having a first condition when said
transmission is in said high drive ratio and a second condition
when said transmission is in said lower drive ratios; and
d. metering rod positioning means responsive to said conditions of
said transmission controlled switch and including a solenoid having
an armature that when said switch means is in said first condition
is translatable between a first position in which said metering rod
effects said minimum flow area and a second position in which said
fluid motor is allowed to position said metering rod to effect said
intermediate flow area in response to said vacuum.
6. In combination with an internal combustion engine providing a
source of vacuum, said engine connected with the input of an
associated transmission the output of which is connected to a load,
said transmission having a variable ratio drive means for varying
the ratio of the speed of the output to the speed of the input from
a high drive ratio to lower drive ratios:
a. a carburetor for providing said air fuel flow to said engine and
having a fuel delivery passage, a fuel flow orifice in said passage
and a fuel metering rod translatable in said orifice to effect a
flow area intermediate a minimum flow area and a maximum flow area,
said minimum flow area allowing sufficient fuel to be provided to
said engine for normally operating said transmission in said high
drive ratio;
b. fluid motor means in said carburetor connected with said
metering rod and communicating with said source of vacuum for
positioning said fuel metering rod to effect said minimum flow area
when said vacuum is above a predetermined vacuum and for
positioning said metering rod to effect said intermediate flow area
as the vacuum drops below said predetermined vacuum while said
transmission drive ratios are said lower drive ratios;
c. transmission controlled switch means connected with a source of
electrical energy and responsive to said transmission drive ratios,
said switch means having a closed condition when said variable
drive ratio is said high drive ratio and a normally open condition
when said drive ratio is said lower drive ratios; and
d. metering rod positioning means mounted on said carburetor and
responsive to said conditions of said transmission controlled
switch, said metering rod positioning means including a solenoid
that is normally de-energized when said transmission controlled
switch is in said normally-open condition and that is energized
when said switch is in said closed condition, said solenoid having
an armature that when said switch is in said first condition is
translatable between a first position in which said metering rod
effects said minimum flow area and a second position in which said
fluid motor is allowed to position said metering rod to effect said
intermediate flow area.
7. In combination with an internal combustion engine for providing
a source of vacuum, said engine connected to the input of an
associated transmission the output of which is connected to a load,
said transmission having a variable ratio drive means for driving
said output from said input and for varying the ratio of the speed
of said output relative to the speed of said input from a high
drive ratio to lower drive ratios; a vacuum unit for advancing the
timing of ignition in said engine when vacuum signals are applied
thereto, a vacuum conduit connected between said vacuum unit and
said engine and valve means in said vacuum conduit movable between
a closed position wherein transmission of vacuum to said vacuum
unit is prevented and an open position wherein transmission of
vacuum to said vacuum unit is permitted:
a. fuel delivery means including a fuel delivery passage, a fuel
flow orifice in said passage and a fuel metering rod translatable
in said orifice to effect a flow area intermediate a minimum flow
area and a maximum flow area, said minimum flow area allowing
sufficient fuel to be provided to said engine for normally
operating said transmission in said high drive ratio;
b. fluid motor means connected with said metering rod and
communicating with said induction passage for positioning said fuel
metering rod to effect said minimum flow area when said vacuum is
above a predetermined vacuum and for positioning said metering rod
to effect said intermediate flow area as said vacuum drops below
said predetermined vacuum while said transmission is in said lower
drive ratios;
c. metering rod positioning means translatable between a first
position in which said metering rod effects said minimum flow area
and a second position in which said fluid motor is allowed to
position said metering rod to effect said intermediate flow area;
and
d. transmission controlled switch means connected with said
metering rod positioning means and with said valve means in said
vacuum conduit, said switch means having a high drive ratio
condition when said transmission is in said high drive ratio for
causing said metering rod positioning means to be translated to
said first position from said second position while also shifting
said valve means to said closed position from said open position
and said switch means also having a low drive ratio condition when
said transmission is in said lower drive ratios for causing said
metering rod positioning means to be normally positioned in said
first position and for causing said valve means to be normally
positioned in said closed position, whereby with said switch means
in said high ratio condition said vacuum advance unit advances the
timing of ignition in said engine while said fuel delivery means
effect said miminum flow area.
Description
This invention relates to internal combustion engine carburetors
and particularly to carburetors having power enrichment
systems.
One common method of improving fuel economy in a vehicle powered by
an internal combustion engine has been to lower the axle ratio,
thereby in effect lowering the ratio of engine speed to road speed,
such ratio being commonly referred to as the N/V ratio. Other
methods of further lowering the N/V ratio to effect fuel economy
have involved transmission overdrive arrangements to reduce the
number of engine revolutions per wheel revolution. While lowering
the N/V ratio usually improves fuel economy, it has been found that
significant improvements in fuel economy are not readily obtainable
in vehicles as the N/V ratios drop below 30.
The present invention recognizes that one reason for this loss of
extra economy is that, in comparable driving conditions, the engine
vacuum is normally raised as the N/V ratio is lowered and that the
power enrichment system in the usual commercial carburetor, since
it normally increases fuel flow with falling engine vacuums, is
therefore used for a larger proportion of the time in normal
driving maneuvers. Such greater use of the power enrichment system
in such normal cruise driving thus prevents the attainment of
potential fuel economy that might otherwise be realized by lowering
the N/V ratio. The present invention further recognizes that
adequate vehicle performance is usually obtained in normal
expressway or open highway driving without requiring the use of the
power enrichment system.
According to the present invention, a carburetor having a
conventional power enrichment system is augmented by a solenoid for
overriding the normal operation of the power enrichment system when
the automatic transmission is in a high drive ratio. The carburetor
has a fuel delivery passage which includes a fuel metering orifice
and a tapered metering rod that is displaceable therein to increase
the flow area through the orifice as the engine vacuum falls. When
the solenoid is energized, its plunger positions the metering rod
to establish a minimum flow area through the orifice permitting
sufficient fuel to be drawn therethrough in accordance with engine
vacuum to sustain non-fuel enriched operation. The solenoid is
energized through a switch that is closed when the automatic
transmission is shifted to a high drive ratio, the switch being the
same as already available for controlling the application of engine
vacuum to a vacuum advance unit on the engine timing system
distributor to permit vacuum advanced ignition timing in high
transmission drives.
It is an object of the present invention to provide a vehicle speed
controlled apparatus for overriding the normal operation of the
power enrichment system of a carburetor.
It is another object of the present invention to provide, in an
internal combustion engine having a power enrichment system, power
enrichment override apparatus for preventing normal operation of
the power enrichment system and including a solenoid operated by
the automatic transmission of the vehicle when in a high speed
drive.
It is another object of the present invention to provide power
enrichment override apparatus of the foregoing type in which the
solenoid is operated by a transmission controlled switch.
It is another object of the present invention to provide power
enrichment override apparatus of the foregoing type wherein the
transmission controlled switch also controls vacuum advanced
ignition timing.
It is another object of the present invention to provide, in a
vehicle in which an internal combustion engine drives a
transmission having a high speed drive and in which a carburetor
provides fuel to the engine through a fuel passage including an
orifice and a metering rod displaceable therein to normally
increase flow area to the engine as the engine vacuum falls,
apparatus to prevent such normal operation of the power enrichment
system when the transmission is in the high speed drive, the
apparatus including a switch operated when the transmission is in
high drive to energize a solenoid for positioning the metering rod
to effect a minimum flow area through the orifice, such minimum
flow area permitting a sufficient fuel flow for sustaining engine
operation in the high speed drive.
These and other objects and features of the present invention will
become more apparent with reference to the following description
taken in conjunction with the single drawing wherein there is shown
a cross-section of a carburetor having apparatus for normally
providing power enrichment and incorporating apparatus in
accordance with the present invention for overriding the normal
operation of the power enrichment apparatus.
With reference now to the drawing, there is shown partly in outline
a commercial carburetor 10 incorporating a power enrichment
override apparatus 12 provided in accordance with the present
invention and described in further detail below.
Carburetor 10 provides an air fuel mixture under the control of a
throttle valve 13 to an induction passage 14 of an internal
combustion engine 16 connected to drive vehicle wheels 18 and 20
through an automatic transmission 22 and an axle 24. To provide
fuel to meet the demands of engine 16, carburetor 10 has a fuel
delivery passage denoted generally at 30 that includes fuel
metering means 32, a primary fuel delivery channel 34, and an
idling channel 36.
Fuel metering means 32 is controlled by a power enrichment system
40 and includes a valve seat 42 having a central orifice 44
therethrough and a metering rod 46 having a tapered end 48
extending through orifice 44. Power system 40 is normally operative
to position tapered end 48 in orifice 44 in accordance with engine
vacuum communicated from induction passage 14 through a vacuum
channel 50 shown dotted. When the engine vacuum is below a
predetermined magnitude, rod 46 positions end 48 to effect a
minimum flow area through orifice 44, sufficient fuel flowing
through such minimum flow area to meet normal engine demands under
substantially constant loads. As the engine vacuum decreases above
the predetermined vacuum, that is, as the absolute pressure in
induction passage 14 increases, power enrichment system 40 causes
tapered end 48 to be raised and retracted out of orifice 44 to
effect a flow area therethrough intermediate the minimum flow area
and some maximum flow area when rod 46 is fully retracted to its
upper limit. Power enrichment is then provided by the increased
flow of fuel drawn through the increased flow area. The above
described power system 40 may be of the conventional type and
operation described on page 64-47 of the "1971 Buick Chassis
Service Manual:" published by the General Motors Corporation.
It has been found that as the engine 16, transmission 22, and axle
24 are sized to require fewer engine revolutions per mile per hour
of vehicle speed, thereby lowering what is called the N/V ratio,
the engine vacuum in induction passage 14 is normally raised in
comparable driving conditions. It has also been found that adequate
vehicle performance is obtained under normal expressway or open
highway driving conditions, where the N/V ratio of a given vehicle
is usually the lowest, without requiring power enrichment. Unless
its normal operation is prevented under these cruise conditions,
power enrichment system 40 would provide increased fuel flow merely
because of the vacuum lowering effect of the lowered N/V ratio and
not because the operator of the vehicle desired the increased
performance associated with power enrichment. Therefore, to obtain
the fuel economy associated with preventing power enrichment system
40 from operating when it would otherwise operate even though not
desired by the operator, the normal operation of power enrichment
system 40 is prevented by power enrichment override apparatus 12
when the vehicle is operating in its high speed range. Since this
range is usually effected when the drive ratio between the
revolutions of output shaft 21 of transmission 22 to the
revolutions of input shaft 23 thereof is the highest, power
enrichment override apparatus 12 is caused to override the normal
operation of power enrichment system 40 when transmission 22 is
shifted into its high drive ratio from a lower drive ratio. For
this purpose, override apparatus 12 includes a solenoid 60 mounted
on a boss 62 upstanding from carburetor 10 directly above valve
seat 42 and metering rod 46, a transmission control switch 64
mounted on and operated by transmission 22, and a conductor 66 for
energizing solenoid 60 with power from a vehicle battery 68.
Solenoid 60 is grounded at 61 and is normally de-energized, and
transmission control switch 64 is normally open when transmission
22 is not in a high drive ratio. Solenoid 60 has an armature
plunger 70 that, when solenoid 60 is de-energized, is normally
retracted by a spring 72 out of engagement with power enrichment
system 40 to allow normal operation thereof. When in a high drive
ratio, transmission 22 closes transmission control switch 64
thereby energizing solenoid 60. Plunger 70 is thereby extended
downward to position power enrichment system 40 so that tapered end
48 of metering rod 46 effects the minimum flow area through orifice
44.
Also connected by a conductor 74 to transmission control switch 64
is an ignition timing system 76 which may be of the type described
in U.S. Pat. No. 3,584,521, entitled "Ignition Timing Arrangement,"
issued to Richard Tooker and James Dawson on June 15, 1971,
assigned to the assignee of the present invention and hereby
incorporated herein by reference. As further described in the
Tooker patent, timing system 76 has a valve operated by a switch
such as switch 64 for controlling the communication of engine
vacuum to a vacuum advance unit on the vehicle ignition timing
distributor to permit vacuum advance timing during vehicle
operation when the transmission is in a high drive. Such advance
timing has been found advantageous in reducing automotive exhaust
emissions, unburned hydrocarbons and oxides of nitrogen. As also
shown in the Tooker patent, transmission control switch 64 may be
controlled according to vehicle speed through a governor on the
output shaft of the transmission or may be controlled by a drive
ratio shift valve in the transmission.
In normal operation of power enrichment system 40, metering rod 46
is either held down to effect a minimum flow area through orifice
44 or is raised in accordance with falling engine vacuums to
increase the flow area to some area intermediate the minimum flow
area and a maximum flow area. Metering rod 46 is held down to
effect minimum flow area when the magnitude of the vacuum in
induction passage 14 is sufficient to overcome the upward bias of a
piston spring 80 on piston 82 comprising enrichment system 40 so
that piston 82 is held against a clip 84. When in this minimum flow
area position, metering means 32 still permits fuel to flow at a
rate determined by the pressure drop between the substantially
atmospheric pressure on the upstream side of orifice 44 and the
downstream pressure in either primary passage 34 when throttle
valve 13 is open or in idle passage 36 when throttle valve 13 is
closed. With throttle valve 13 open, the rate of fuel flow through
metering means 32 when in the minimum flow area position is
normally sufficient to sustain nonenriched vehicle operation under
constant loads, and, with throttle valve 13 closed, the rate of
fuel flow through metering means 32 is normally sufficient to
sustain idle operation of the engine 16.
Should the vacuum in induction passage 14 fall as the absolute
pressure therein increases, the pressure differential on the
opposite sides of piston 82 decreases to a point where the effect
of vacuum on piston 82 is overcome by the upward bias of spring 80.
As the vacuum falls below that required to hold piston 82 in the
position to effect minimum flow area, spring 80 moves piston 82
upwards to retract tapered portion 48 of metering rod 46 to
increase the flow area through orifice 44 above the minimum flow
area. The resulting increase in the fuel flow causes engine 16 to
increase its power output.
To prevent the above-described normal mode of power enrichment
system operation while also permitting vacuum advanced timing in
ignition timing system 76, the normally-open transmission control
switch 64 is closed by transmission 22 when in a high drive ratio.
Solenoid 60 is thereby energized so that plunger 70 thereof holds
metering rod 46 down in a position effecting a minimum flow area
through orifice 44. While the normal operation of power enrichment
system 40 is thereby prevented, the minimum flow area through
orifice 44 permits fuel to flow therethrough at a rate determined
by the pressure in primary passage 34 or idle passage 36.
Therefore, even though solenoid 60 is energized to maintain a
minimum flow area through orifice 44, the fuel supplied to primary
passage 34 through metering means 32 in this minimum flow area
condition is sufficient to permit normal non-enriched vehicle
operation as might be required for normal expressway or open
highway driving.
Having described one embodiment of the present invention, it is
understood that the specific terms and examples are employed in a
descriptive sense only and not for the purposes of limitation.
Other embodiments of the present invention, modifications thereof
and alternatives thereto may be used. I therefore aim in the
appended claims to cover such modifications and changes as fall
within the true spirit and scope of my invention.
* * * * *