U.S. patent number 3,817,225 [Application Number 05/122,933] was granted by the patent office on 1974-06-18 for electronic carburetion system for low exhaust emmissions of internal combustion engines.
Invention is credited to Jack C. Priegel.
United States Patent |
3,817,225 |
Priegel |
June 18, 1974 |
ELECTRONIC CARBURETION SYSTEM FOR LOW EXHAUST EMMISSIONS OF
INTERNAL COMBUSTION ENGINES
Abstract
An electronic fuel injection system for maintaining absolute
control over the air to fuel ratio flowing to the combustion
chambers of an internal combustion engine. The system includes
means for measuring the air flow rate to the engine. The flow rate
measurement is converted into a proportional electrical signal
which flows to a signal summing unit. The fuel flow rate from a
fuel pump is controlled by a signal received from the signal
summing unit, and provides a controlled fuel flow to the engine
which is proportional to the air flow. Means associated with the
fuel pump measures the exact flow rate therefrom and converts the
measurement into another proportional electrical signal which is
fed back to the summing unit to thereby form a closed loop circuit.
The summing unit compares the first signal with the second signal
and changes the fuel flow rate the required amount to maintain the
ratio thereof at a predetermined value. There is optionally
included within the system a warm-up enrichment, acceleration
enrichment, and temperature and barometric pressure conversion
means, all of which are connected back to the summing unit so as to
provide extremely close control over all parameters affecting the
air to fuel ratio.
Inventors: |
Priegel; Jack C. (El Paso,
TX) |
Family
ID: |
22405726 |
Appl.
No.: |
05/122,933 |
Filed: |
March 10, 1971 |
Current U.S.
Class: |
123/497;
261/DIG.48; 261/39.5; 123/482; 123/491; 261/DIG.74; 123/492 |
Current CPC
Class: |
F02D
41/18 (20130101); Y10S 261/48 (20130101); Y10S
261/74 (20130101) |
Current International
Class: |
F02D
41/18 (20060101); F02b 003/00 (); F02m
039/00 () |
Field of
Search: |
;123/32E,32EA,119R,139E,32EA |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Goodridge; Laurence M.
Assistant Examiner: Cox; Ronald B.
Attorney, Agent or Firm: Bates; Marcus L.
Claims
I claim:
1. In an internal combustion engine having a combustion chamber
wherein fuel is admixed with an airstream and combusted in the
combustion chamber thereof, an electronic carburetion system for
controlling the air/fuel ratio effected within the combustion
chamber, comprising:
a transducer means connected to measure the airstream flow rate to
the combustion chamber of the engine, said transducer means
including circuitry which produces a first signal which is
proportional to the measured airstream flow rate;
a positive displacement fuel pump means connected to supply a flow
of fuel to the combustion chamber; electrical circuit means
including a power source for driving said fuel pump means; circuit
means by which the magnitude of said power source is made
proportional to said first signal;
means including electrical circuitry by which the speed of the pump
means is measured and the measurement converted into a second
signal thereby providing a signal which is proportional to the fuel
flow rate from the pump means;
circuitry means for selecting a finite fuel flow rate for a finite
air flow rate;
means including circuitry, by which said first and second signals
are compared to one another and to said selected fuel and air flow
rate so as to determine that said finite fuel flow rate for said
finite air flow rate is present in the combustion chamber;
means by which said first signal is changed to a value to cause the
resultant fuel flow rate from the pump to be the selected finite
fuel flow rate for the selected air flow rate.
2. An electronic fuel induction system for controlling the air/fuel
ratio of a combustible mixture as the mixture flows to the
combustion chamber of an internal combustion engine comprising:
means for measuring air flow rate to the combustion chambers, means
converting said measurement into a first signal;
said means for measuring the air flow rate is a transducer;
said transducer having a rotor and a stator with the rotor being
disposed within the air stream of the air flowing to the motor,
means rotatably mounting said rotor with respect to said stator,
and means responsive to rotation of said rotor for measuring the
speed of said rotor;
a fuel pump means for delivering fuel to the combustion chamber of
the engine, means providing a driving force for said fuel pump in
proportion to said first signal;
means measuring the fuel flow rate delivered by said pump, means
converting the last said measurement into a second signal;
means for comparing said first signal to said second signal and
means responsive to said means for comparing for changing the fuel
flow rate so as to change said second signal to a value which
maintains the air/fuel ratio at a predetermined value;
said rotor is made of foamed polyurethane so as to provide a
lightweight rotor;
and, said journal means being axially located in said rotor.
3. An electronic fuel induction system for controlling the air/fuel
ratio of a combustible mixture as the mixture flows to the
combustion chamber of an internal combustion engine,
comprising:
means for measuring air flow rate to the combustion chambers, means
converting said measurement into a first signal;
a fuel pump means for delivering fuel to the combustion chamber of
the engine, means providing a driving force for said fuel pump in
proportion to said first signal;
means measuring the fuel flow rate delivered by said pump, means
converting the last said measurement into a second signal;
means for comparing said first signal to said second signal and
means responsive to said means for comparing for changing the fuel
flow rate so as to change said second signal to a value which
maintains the air/fuel ratio at a predetermined value;
said means for measuring air flow rate is a transducer having a
housing, a stator, and a rotor; said means converting said
measurement into a first signal including means for providing said
signal in response to the rate of rotation of the rotor relative to
the stator;
said housing being in the form of a cylinder and having an inlet
end portion and an outlet end portion;
means mounting said stator axially of said housing, the effective
outside diameter of said stator being smaller than the inside
diameter of said housing to thereby provide an annulus
therebetween;
shaft means affixed to said stator; journal means by which said
rotor is rotatably received by said shaft means;
said rotor having a plurality of blades radiating therefrom, a
portion of said blades being disposed within said annulus.
4. In an internal combustion engine wherein fuel is admixed with an
air stream and combusted in a combustion chamber thereof, an
electronic carburetion system for controlling the air/fuel ratio
flowing to the combustion chamber of the apparatus, comprising:
a transducer means connected to monitor the air stream flow rate,
said transducer means generates a first signal which is
proportional to the air flow rate to the combustion chamber;
a positive displacement fuel pump means connected to supply a flow
of fuel to the combustion chamber; electrical circuit means
including a power source for driving said fuel pump means;
circuit means by which the magnitude of said power source is made
proportional to said first signal;
means including electrical circuitry by which the speed of the pump
means is measured and the measurement converted into a second
signal thereby providing a signal which is proportional to the fuel
flow rate from the pump means;
circuit means for selecting a finite fuel flow rate for a finite
air flow rate;
means including circuitry, by which said first and second signals
are compared to one another and to said selected fuel and air flow
rate so as to determine that said finite fuel flow rate for said
finite air flow rate is present in the combustion chamber;
means by which said second signal is changed to a value to cause
the resultant fuel flow rate from the pump to be the selected
finite fuel flow rate for the selected air flow rate.
5. An electronic fuel induction system for controlling the A/F
ratio of a combustible mixture as the mixture flows to the
combustion chamber of an internal combustion engine comprising:
a transducer for measuring air flow rate to the combustion
chambers, said transducer having a rotor and a stator with the
rotor being disposed within the air stream of the air flowing to
the motor, means rotatably mounting said rotor with respect to said
stator, said rotor being made of foamed plastic so as to provide a
lightweight rotor assembly; means responsive to rotation of said
rotor for measuring the speed of said rotor to thereby provide a
first signal;
a fuel pump means for delivering fuel to the combustion chamber of
the engine, means providing a driving force for said fuel pump in
proportion to said first signal;
means measuring the fuel flow rate delivered by said pump, means
converting the last said measurement into a second signal;
means for comparing said first signal to said second signal and
means responsive to said means for comparing for changing the fuel
flow rate so as to change said second signal to a value which
maintains the A/F ratio at a predetermined value.
6. The fuel induction system of claim 5, wherein said foamed
plastic is polyurethane.
7. The fuel induction system of claim 5, wherein said means
responsive to rotation of said rotor includes a magnet attached to
said rotor, means mounting a magnetically actuated switch adjacent
to said magnet whereby rotation of said magnet moves the contacts
of said switch to the opened and closed position.
8. The fuel induction system of claim 5, wherein said signal is in
the form of a frequency which is proportional to the rotor speed;
means for converting said frequency to a proportional current, and
means driving a fuel pump in response to said current;
said second signal being in the form of a frequency which is
proportional to the fuel flow; means for converting the last said
frequency to a proportional current; and, said means for comparing
including a current summing unit which tends to maintain the
recited proportional currents at a predetermined set value.
9. The fuel induction system of claim 5, wherein said fuel pump
means is a positive displacement pump; and further including a pump
motor, means connecting said motor to said pump, said means for
controlling the flow rate from said fuel pump includes means for
controlling the speed of said motor.
10. The system of claim 1, wherein said means for measuring the air
flow rate is a transducer;
said transducer having a rotor and a stator with the rotor being
disposed within the air stream of the air flowing to the motor,
means rotatably mounting said rotor with respect to said stator,
and means responsive to rotation of said rotor for measuring the
speed of said rotor.
11. The improvement of claim 10 wherein said means responsive to
rotation of said rotor includes a magnet attached to said rotor,
means mounting a magnetically actuated switch adjacent to said
magnet whereby rotation of said magnet moves the contacts of said
switch to the opened and closed position.
12. Method for controlling the air/fuel ratio in the combustion
chamber of an internal combustion engine comprising the steps
of:
1. measuring the air flow rate to the engine;
2. converting the measurement obtained in step (1) into a signal
which is proportional to the air flow rate;
3. driving a positive displacement fuel pump at a rate which is
proportional to the signal of step (2); and flowing the fuel into
the combustion chambers of the engine;
4. measuring the rate at which the positive displacement pump of
step (3) is driven;
5. converting the measurement of step (4) into a signal which
varies in proportion to the pump speed;
6. comparing the measurement obtained in step (5) to the
measurement obtained in step (2);
7. changing the rate in step (3) to cause the results of step (6)
to remain at a finite value representative of a selected air/fuel
ratio.
13. The method of claim 12, and further including the steps of:
8. measuring the air flow rate of step (1) by actuating a frequency
generator in response to the rate of the volumetric air flow;
and
9. changing the generated frequency into a current which is
proportional to the generated frequency in accordance with step
(2).
14. The method of claim 13 wherein step (4) is carried out by
utilizing the motion of a fuel pump drive means to generate a
second drequency which is proportional to the fuel flow rate, and
changing the second frequency into a current having similar
characteristics of the air flow rate current, in accordance with
step (5).
15. The method of claim 12, and further including an acceleration
enrichment detection means; means forming an acceleration
compensation current converter for producing a signal proportional
to said detection means;
including the last signal in step (6) so as to enrich the A/F ratio
upon sudden increase in the manifold pressure.
16. The transducer of claim 3, wherein said means for providing a
signal includes a magnetically actuated switch means affixed to
said stator, and a rotatable magnet; said switch means being
disposed in close proximity to said magnet; said rotatable magnet
being affixed to said rotor and forming part of the journal
means.
17. The transducer of claim 3, wherein said rotor includes a main
body portion to which said blades are integrally formed therewith,
said rotor being made of foamed polyurethane.
18. The transducer of claim 3, wherein said journal means includes
a magnet; and, said means for providing a signal includes means
responsive to rotational movement of said magnet.
19. The system of claim 4, wherein said means for producing said
first signal is a transducer, said transducer includes a rotor
which is turned in proportion to the air flow rate, said transducer
having means for producing a signal in the form of a frequency
which is proportional to the rotor speed; means for converting said
frequency to a proportional current, and means driving said fuel
flow producing means in response to the magnitude of said
current;
said second signal being in the form of a frequency which is
proportional to the fuel flow; means for converting the last said
frequency to a proportional current; and, said means for comparing
including a current summing unit which tends to maintain the
recited proportional currents at a predetermined set value.
Description
BACKGROUND OF THE INVENTION
Throughout the specification and claims, the term "I.C." is to be
understood to relate to an "internal combustion engine", while
"A/F" is to be understood to mean "air to fuel ratio." The term
"signal" relates to a current or voltage pulse of any suitable
value and wave form which is compatible with the teachings of this
invention.
Pollution of our environment with exhaust emissions from internal
combustion engines is considered to be a primary health hazard, and
for this reason great emphasis is presently being placed upon the
provision of means approaching complete combustion of hydrocarbon
fuels to thereby lower undesirable or hazardous exhaust emissions
to a minimum. Modern electronic technology provides vastly improved
means by which the A/F ratio of the gaseous mixture contained
within combustion chambers can be maintained at a predetermined
value in a manner which is far superior to mechanical carburetors
of the prior art. For example, Mycroft, U.S. Pat. Nos. 3,470,858;
Westbrook et al., 3,272,187; and Wallis, 3,240,191 propose various
systems for more closely controlling the A/F ratio in internal
combustion engines, and to which reference is made for further
background of this invention.
In these and other prior art systems for controlling A/F ratio, the
air flow rate generally has been utilized to influence the fuel
flow rate, with mechanical provision be made for warm-up
enrichment, acceleration enrichment, as well as for temperature and
barometric changes. However, once the fuel flow rate demanded by a
particular instantaneous mass air flow rate has been determined by
the prior art electronic circuitry, control over the system is
generally left to chance, and as may be expected, variations in the
system downstream of the controlling sensor means inherently
changes a sufficient amount to render all of the previous control
work inefficient.
Therefore, it is desirable to provide an improved electronic
carburetion system for controlling the A/F to an I.C. engine, and
to positively measure the fuel flow rate from the fuel pump so as
to enable comparison of the actual fuel flow rate to be made with
the measured mass air flow rate, thereby enabling further
correction means to be employed as the ratio therebetween changes
from a predetermined ideal value.
SUMMARY OF THE INVENTION
This invention comprehends an electronic carburetion system for
controlling the A/F in the combustion chambers of an I.C.,
comprising: transducer means for measuring the air flow rate to the
intake system of the I.C. and for producing an electrical signal
proportional thereto. A fuel pump is controllably driven at a rate
which is proportional to the air flow rate signal. The fuel flow
rate to the I.C. is then measured and converted into an electrical
signal which is proportional to the fuel flow rate, and this
resulting signal is electronically compared to the corrected air
flow signal, to thereby determine that a combustible mixture having
the proper A/F is being ingested by the I.C. Should this actual A/F
value differ from the predetermined desired value, correction is
immediately made by the circuitry so as to increase or decrease the
fuel flow rate to the optimum predetermined desired set value.
Included with the before recited method, there is further provided
apparatus for carrying out the invention which includes a
transducer for converting the volumetric air flow rate into a
frequency. The frequency is converted into the before mentioned
signal which is in turn connected to a signal summing unit. The
signal summing unit receives a signal from each of the desired
parameters which must, of course, include a signal from the mass
air flow rate sensor and the fuel flow rate sensor so as to enable
attaining the foregoing described control.
The fuel pump is driven by a motor, with the motor being connected
to a positive displacement metering pump which has associated
therewith a transducer means for converting absolute fuel flow rate
to a frequency. The frequency is converted into a suitable signal
which can be connected to the before mentioned signal summing unit
so as to attain the aforesaid results.
A particular atomizer is connected to the metering pump so as to
attain efficient atomization of the liquid fuel. The atomizer and
the fuel pump can take on several different forms.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematical representation which includes any internal
combustion engine, with the instant invention being
diagrammatically illustrated in association therewith;
FIG. 2 is a flow sheet which diagrammatically sets forth the
essence of one form of the present invention;
FIG. 3 sets forth a specific embodiment of the invention, wherein
there is disclosed a schematical representation of circuitry for
carrying out the invention disclosed in FIG. 2;
FIG. 4 sets forth a perspective longitudinal part crosssectional
representation of a sub-combination of the invention;
FIG. 5 is a fragmentary cross-sectional view of a second embodiment
of the apparatus previously disclosed in FIG. 4;
FIG. 6 is a part cross-sectional, part elevational view of another
sub-combination of this invention;
FIG. 7 is a top plan view of FIG. 6, with some parts thereof being
removed and other parts thereof being shown in crosssection;
and
FIG. 8 is a fragmentary part cross-sectional view of a pump which
can be used in conjunction with the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Throughout this specification, wherever possible, like or similar
numerals will be applied to denote like or similar elements of
construction.
FIG. 1 diagrammatically discloses a motor generally indicated at
the arrow M. An exhaust manifold M1 is connected thereto in the
usual manner, with part of the exhaust gases optionally flowing at
M2 into carburetion system C1. Transducer means for measuring the
air flow rate to the engine is diagrammatically seen illustrated at
10, with air flowing at A through the metering means. Controller 11
receives a signal from 10 and controls the rate of fuel flow into
the internal combustion engine at 13. Feedback from 13 to the
controller is seen diagrammatically illustrated by the arrows in
the drawing.
The flow sheet set forth in FIG. 2 broadly discloses the present
invention, wherein the illustrated transducer 10 converts air flow
rate therethrough into a proportional electrical frequency. The
signal from the transducer is in the form of a frequency which is
proportional to the volumetric air flow therethrough, and which
must be changed to a signal which is suitable for being processed
by the electronic controller 11. The controller accordingly is
provided with a frequency to current converter 26 which provides
the current summing unit 27 with an electric signal which is
proportional to the volumetric air flow at 10.
The loop compensation 28 can take on several different forms so
long as it properly stablizes the feedback. Since this portion of
the circuitry is a common technique known in the art, it will not
be discussed in further detail, other than to make reference to one
form of the circuitry as disclosed in FIG. 3.
Operational amplifier 29 increases the strength of the signal
received from the current summing unit to thereby provide a
suitable in-put signal for the power amplifier 20. The power
amplifier controls the level of power input to the pump drive
motor.
The pump drive motor drives a metering pump, which preferably is a
positive displacement pump as disclosed in FIG. 8, but which may
take on several different forms so long as it is a positive
displacemnt type metering apparatus, or the equivalent thereof.
Each cycle of the positive displacement metering pump provides a
porportional frequency at 15 which is converted into a current at
30 to thereby provide a signal which is suitable for being
processed by the current summing unit. Circuitry 30 is similar to
the before discussed circuitry 26.
The intake manifold 14 can take on several different known forms,
and is illustrated as being in the form of a housing having a
butterfly valve 23 disposed therein for controlling the air flow
rate to the engine. Atomizer nozzle 24 receives fuel by means of
the air bleed cross-over valve asembly 25. The illustrated
cross-over valve and nozzle combination is considered to be but one
of several different possible arrangements for atomization of fuel
downstream of the fuel pump.
FIG. 3 discloses one specific example of circuitry for attaining
the method generally set forth by the apparatus illustrated in
FIGS. 1 and 2. The air flow to frequency converter is seen to
include a rotating permanent magnet 31 which actuates the
illustrated magnetically actuated switch. The switch is of
conventional design. Accordingly, the switch makes and breaks at a
rate which is proportional to the volumetric air flow. The
transducer is connected by J1 to the controller by means of J2.
The metering pump 13 (the details of which will be more fully
discussed later on) is driven by pump motor 12, with a rotatable
permanent magnet 15' being connected to rotate with the pump shaft
in a manner to actuate the magnetic switch 43 in direct proportion
to the speed of the pump or the motor. The fuel flow transducer
formed by the switch is connected to J6, which in turn is connected
to J5 with the terminals 1 and 2 of J5 being connected to the
frequency to current converter 30.
It will be noted that the circuitry 26 is identical to the
circuitry 30, with the exception of the coupling capacitors leading
from the converter into the summing unit.
Similarly, circuitry 26' is identical to circuitry 30', except that
the current direction is opposite. The purpose of each of these
individual networks is to receive a pulsating current or frequency,
and convert it into a D.C. current which can be added or subtracted
one from the other.
The circuitry at 18 differs slightly from the circuitry seen at 26'
and 30' for the reason that the signal received from the
acceleration enrichment detection apparatus 17 is already a D.C.
current and accordingly does not need to be rectified.
Broadly, the circuitry at 26 comprises a means by which a
particular wave form may be generated as a result of terminals 33,
34 being cyclicly bridged by the transducer 10, with this action
supplying an alternating current at 35, with the alternating
current being rectified by the circuitry at 26', and the resultant
D.C. current being received across the 10K resistor S1 disposed
between terminals 37 and 38. The 10K resistor is one of four
summing resistors, and has one terminal thereof connected to the
common junction at 38, hereinafter called "the summing point."
The current flow from summming point to the 10K resistor S2 of the
operational amplifier must therefore have a signal strength of a
magnitude which exactly but indirectly controls the power amplifier
output to thereby provide the pump drive motor with sufficient
current to operate the metering pump at a speed required to deliver
a finite flow of fuel for a finite mass air flow rate.
Looking at the details of the frequency to current converter 26 and
26', those skilled in the art will realize that the circuitry 26 is
arranged whereby it can be in the form of printed circuitry
disposed on a card, or alternatively, can be an integrated circuit
in the form of a "chip."
The transducer 10 effectively shorts or bridges terminal 33 to
terminal 34 each revolution of the magnet 31 to thereby provide a
signal at 35 which consists of a square wave pulse of a controlled
amplitude, because of the following current flow path:
The action of transducer 10 energizes the solenoid actuated switch
at 33, with the latter making and breaking in response to the
former. This expedient avoids criticality beyond the circuit proper
26 which may otherwise be brought about as a result of lead loss,
inductance, and the like. Hence, the employment of dual switches
provides a means by which the incoming signal from the transducer
may be absolutely cleaned up.
The signal at 35 consists of a square wave pulse, the amplitude of
which is controlled by the illustrated 2.5K potentiometer, to
provide for adjustment of ratio control. This signal at 35 is
coupled to the rectifier bridge of 26' by the 0.1 MF capacitor.
In the rectifier bridge, a positive and negative transmission is
received at 35', which can appropriately be characterized as a
differential wave form, with the negative transition going through
the parallel arranged diodes between 35', 37 and the positive
transition going to ground through the 0.1 MF capacitor near
junction 36. The two diodes are placed in parallel at 35', 37; with
one of the diodes being placed in series with the illustrated 10K
resistor in order to achieve internal temperature compensation, or
to stabilize the circuitry for temperature.
The signal imposed upon summing resistor S1 is considered to be a
current which is proportional to frequency, and which goes to the
operational amplifier at the summing point.
Those skilled in the art will now recognize that the operation of
the circuitry at 30, 30' is essentially identical to the operation
of the circuitry at 26, 26', except that the diodes are reversed
with the positive transition of circuitry 30' being connected to S3
and the negative transition being connected to ground through the
before mentioned 0.1 MF capacitor near junction 36.
Hence, there is received at the summing point a positive transition
from transducer 10k a negative transition from transducer 13, and
positive transition from the circuitry 18. When the sum of the
signals are equal and opposite, the null point of operation has
been reached, and the system has attained its frequency of
operation for a particular flow rate.
Circuitry 18 is similar to 30' and provides a positive transition
at summing resistor S4, in response to throttle advancement.
Increase in current magnitude is brought about by acceleration
demand so as to enrich the A/F. This signal rapidly decays as an
exponential function so as to provide an I.C. with an
instantaneously richer combustion mixture, which rapidly returns to
the new null point, or set point, commesurate with the increased
flow rates.
The operational amplifier 29' is comprised of complex circuitry
which is familiar to those skilled in the art. The amplifier
receives a predetermined magnitude of current at 38 which is
proportional to the air flow rate through the transducer 10. This
signal is imposed upon the 10K resistor S2 which is connected
between junction 38 and terminal 4 of the operational amplifier.
Accordingly, as the current between junction 38 and 36' varies,
this signal will be amplified so that the resultant current at 41
is of the exact magnitude required to either speed up or retard the
fuel pump an amount necessary to maintain a predetermined air fuel
ratio.
The power amplifier 20 as well as the voltage regulator 21 are
conventional in design and merely represent one of several circuits
which could be used for this function, and accordingly, will not be
discussed in greater detail since the circuitry thereof is amply
disclosed in FIG. 3.
The atomizing nozzle 124 of FIG. 4 is a converging, diverging
super-sonic nozzle, hereinafter called an "atomizer." The main body
48 of the atomizer is preferably housed within a conduit which
forms part of the intake manifold assembly of the engine. The
housing includes a cup-like cavity 49 disposed downstream thereof
with the outwardly opening cavity being axially aligned with the
central longitudinal axis of the housing. Support member 50 rigidly
maintains the cup centrally disposed with respect to the
housing.
A small portion of the exhaust gases from the exhaust manifold are
diverted to flow at 51 into the converging section 51'. Fuel flows
through annulus 52 and through the radially spaced apart
passageways 53 into the diverging portion 54 of the throat.
Atomized fuel follows the dash-dot line seen at 55 and impinges
upon the vibrating cup in a manner seen indicated at 56.
In the embodiment of FIG. 5, exhaust gases flow at 51' while fuel
enters hollow tube 52' and exits at 55', where the exhaust gases
carry the atomized fuel into the cup 57. Converging section 58
directs the flow of exhaust gases into the cup. The depth "I" of
the cup, the length "X" of the rod, and the distance "L" between
the faces determine the frequency of vibration of the nozzle.
Looking now to the details of the transducer 10 as particularly
shown in FIGS. 6 and 7, there is illustrated a cylindrical housing
60 having an outwardly disposed flange about one peripheral edge
portion thereof to facilitate attachment of the transducer to the
manifold at a location upstream of the control valve 23. Axially
aligned within the housing is a main body 61 having an upstanding
skirt 62 which forms a cavity 63 for housing at least one
magnetically actuated switch 59. The switches are anchored to the
floor of the cavity by any suitable attachment means, with
electrical conductors leading therefrom in the illustrated manner
of FIG. 7. A stationary shaft 64 has a keeper 64' removably affixed
to a marginal free end portion thereof, with the fixed end of the
shaft being rigidly secured within structure of the body. Radially
spaced apart streamlined vanes 65 supportingly attach the body to
the sidewall of the housing by means of a removable fastener 66.
The vanes present a small frontal area and provide means for
straightening air flow therethrough. An integral foamed
polyurethane plastic rotor 67 has radially spaced apart blades 68
attached thereto, with the blades being disposed with respect to
the axial air flow to provide an angle at 68' of 43.degree.
therebetween. The lower extremity 69 of each rotor blade is
slightly spaced apart from the upper extremity 65' of a stator
support vane. The blade is provided with an inside edge portion 70
which clears the exterior wall 61 of the housing in close tolerance
relationship therewith.
The rotor has a circumferentially extending lightening depression
71 outwardly disposed of a central built-up interior portion
thereof so as to form the illustrated axial passageway within which
there is received the permanent magnet 31.
The upstanding stationary shaft 64 has a low-friction nonmagnetic
bushing 72 which slidably receives the drilled passageway of the
magnet in low friction engagement therein in the usual manner of a
tubular bearing surface.
Electrical connection 73 is equivalent to J1 of FIG. 3. Annular
area 74 forms an annular air passageway between the housing 60 and
stator wall 61.
For purpose of illustration only, FIG. 8 discloses a positive
displacement piston pump assembly 80 having a bell shaped rotatable
housing 81. Affixed to base 82 is a cylinder 83, the interior of
which provides a pumping chamber at 84. Piston 85 reciprocates
within the cylinder while duct 87 cooperates with outlet 88 and
inlet 89 in a manner which serves the purpose of a valve. Shaft 90
imparts both reciprocatory as well as rotational motion into the
piston. Arm 92 engages the housing so as to stroke the piston each
revolution of the shaft. The angle formed between the shaft and the
piston determines the length of the stroke of the piston, and
accordingly, the volume of fluid delivered by the pump. For further
details of the operation of the pump per se, reference is made to
Pat. No. 3,168,872.
The pump housing has a magnetically actuated switch 94 attached
thereto and in close proximity to a magnet 95 which is attached to
and rotates with piston 85. The relative position of the magnet and
switch must be located respective to one another whereby the
magnetic flux of the rotating magnet will actuate the switch each
revolution of the shaft, for all longitudinal positions of the
piston relative to the cylinder. Where deemed desirable, the magnet
can be affixed to the shaft and the switch disposed adjacent
thereto.
OPERATION
When it is desired to commence operation of the motor, in some
instances it may be necessary to "charge" the intake manifold with
a rich mixture of hydrocarbons, and thereafter maintain a
diminishing rich mixture within the combustion chamber until the
engine reaches a suitable operating temperature. This can be
accomplished by momentarily connecting the fuel pump motor to the
battery. This action energizes the pump drive motor a sufficient
number of cylces to charge the intake manifold with a rich mixture
of hydrocarbons. After the engine has started, the warm-up
enrichment apparatus maintains a predetermined rich combustion
mixture during the warm-up period of the engine.
Assuming the engine to have reached equilibrium and to be operating
at a constant power output, should the throttle setting be changed,
this will immediately change the flow rate through the air flow
transducer. The transducer preferably is of the disclosed design
which is instantaneously responsive to air flow, so as to
immediately effect a corresponding change in the signal at junction
38, so that the power effected at conductor 45 immediately changes
the fuel flow rate of the fuel pump. The change in rotational speed
of magnet 15' is electrically fed back through the closed loop of
the frequency to current converter 30, where the signal across the
10K summing resistor connected to junction 27' adds to or subtracts
from the other voltages effected at junction 38. This feedback
signal provides the before mentioned closed loop circuitry which
assures that the A/F remains at the optimum or desired ratio.
When the manifold pressure is suddenly increased, the vaporized
fuel in the manifold condenses into larger droplets or particle
size to thereby effectively reduce the apparent A/F, or the
combustion efficiency, in a resulting manner which is similar to
leaning the mixture. Accordingly, the acceleration enrichment
apparatus offsets this apparent change in A/F. The enrichment
apparatus provides the current summing unit with a signal which has
an exponential decay so as to provide an initial large flow of fuel
which decays back to a suitable set point, exactly like the action
of an accelerator pump on a conventional carburetor.
The air flow transducer used herein is preferably fabricated in
accordance with the disclosure as set forth in conjunction with
FIGS. 6 and 7 because the vane type transducer has an almost
weightless rotor thereon which is instantaneously responsive to
changes in the volumetric air flow rate to the engine. The rotor is
made of foamed polyurethane and is of one piece construction. The
magnet 31 is cemented within the formed central passageway of the
rotor, and each of the vanes are disposed at an angle of
43.degree.. The blade angle and size is selected to give the
maximum torque for the mass of the blade, as well as the optimum
resultant mechanical advantage due to the angle of aerodynamic
reaction on the flat portion of the blade.
The trailing edge portion of each vane is set at a large radius and
encloses a marginal portion of the housing so as to present a
maximum surface area to the air flowing through the annulus 74,
thereby gaining the maximum mechanical leverage. The width of the
vanes of the rotor are maintained at the optimum ratio with respect
to radius 74'. Otherwise, the innermost portion of the rotor will
offer excess drag at high air flow velocities. The rotor blade is
built up at 68' so as to transfer loads from the trailing edge
portion back up into the main portion 67 of the rotor. The use of
foamed plastic provides an extremely lightweight rotor of more than
adequate strength, and brings about an unexpected response rate
with respect to the air flowing through the transducer.
It is essential that the rotor be supported by a low friction
journal means in order that the starting torque resulting from air
movement thereacross be of a large value as compared to the
resisting frictional torque.
At any specific air flow rate through the housing, there is a
variation in velocity from point to point across a section thereof.
By ducting the air through the illustrated annulus, a smoother flow
across the sensing blades is effected. Disposition of the effective
blade area within this annulus discourages any pumping action at
extreme velocities.
Straightening vanes may be disposed upstream of the blades so as to
minimize any spiral effect which may otherwise be generated because
of the inherent flow characteristics of a duct.
The extra magnetically actuated switch is provided to avoid
disassembly of the unit in the event the first switch should fail.
The rotor, the magnetic switches of the apparatus, the motor, the
pump, and the pot are the only moving parts of the system.
It is possible to substitute a small inductance coil for the
magnetic switch if deemed desirable, however, since the probability
of failure of one of the switches is remote, the advantages of the
magnetic switch off-sets this alternate feature.
In operation of the nozzle of FIG. 5, a small portion of the
exhaust gases are recirculated at 51' so as to provide a fluid
drive for the nozzle and at the same time to ingest inert flue
gases into the induction system of the vehicle, which further
reduces the formation of oxides of nitrogen because of the diluent
effect. The exhaust gases converge at 58 and exit from the nozzle
as a jet stream which impinges upon cup 57. The cup vibrates at a
frequency which is coincident with the rod. In order to achieve
this result, the free end portion of the rod must have a planar
surface thereon with sharp edges facing the jet stream. Hence, the
resonant cavity together with the resonant rod accentuate each
other to thereby produce greater shearing velocities which
literally explode the hydrocarbons impinging on the rod and the cup
so that complete vaporization of the fuel is achieved in a manner
which has not heretofore been attained.
It is also possible to utilize cylinder head pressures rather than
the exhaust manifold pressure as a source of fluid pressure for the
sonic atomizer of either FIGS. 4 or 5.
Those skilled in the art of pneumatic circuitry realize that "what
one can accomplish electrically, one can also duplicate
pneumatically." Accordingly, those skilled in the art will envision
the substitution of comparable pneumatic apparatus and flow
conduits for the electronic circuitry used herein so as to practice
the essence of the present invention. Therefore, such an expedient
is contemplated by this invention, and is to be considered to lie
within the metes and bounds of the intellectual property claimed
herein.
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