U.S. patent number 3,677,241 [Application Number 05/141,161] was granted by the patent office on 1972-07-18 for carburettors operating under a constant reduced pressure.
This patent grant is currently assigned to Les Usines Laprade S.A.. Invention is credited to Pierre Gele, Bernard Laprade.
United States Patent |
3,677,241 |
Gele , et al. |
July 18, 1972 |
CARBURETTORS OPERATING UNDER A CONSTANT REDUCED PRESSURE
Abstract
A carburettor operating under a constant reduced pressure
comprising a mixing chamber formed in the intake manifold between
the main and an auxiliary throttle valve, and fed with air and fuel
by an emulsifying chamber, the input of air in which as required
for idling and reduced load conditions, is controlled by a valve
controlled in its turn by a vacuum chamber which is selectively
connected with the atmosphere and with the intake manifold so as to
make said valve close the corresponding input whenever the rotary
speed of the engine is above a predetermined value and the main
throttle valve is simultaneously closed or substantially so or else
whenever the temperature of the engine cooling medium sinks
underneath a predetermined value.
Inventors: |
Gele; Pierre (Odos Tarbes,
FR), Laprade; Bernard (Arudy, FR) |
Assignee: |
Les Usines Laprade S.A. (Arudy,
FR)
|
Family
ID: |
26215727 |
Appl.
No.: |
05/141,161 |
Filed: |
May 7, 1971 |
Foreign Application Priority Data
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May 8, 1970 [FR] |
|
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7016860 |
Dec 30, 1970 [FR] |
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704769 |
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Current U.S.
Class: |
123/327;
123/179.18; 123/588; 261/39.2; 261/78.1; 123/179.15; 123/585;
261/DIG.19; 261/50.1; 261/52 |
Current CPC
Class: |
F02M
17/09 (20130101); F02M 7/12 (20130101); F02M
1/10 (20130101); F02M 3/005 (20130101); Y10S
261/19 (20130101) |
Current International
Class: |
F02M
1/10 (20060101); F02M 17/00 (20060101); F02M
7/00 (20060101); F02M 7/12 (20060101); F02M
17/09 (20060101); F02M 1/00 (20060101); F02M
3/00 (20060101); F02m 007/06 (); F02m 001/08 () |
Field of
Search: |
;261/39A,5A,52,78R,DIG.19,5AA
;123/119DB,97B,124A,124B,179G,18T |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Miles; Tim R.
Claims
What I claim is:
1. In a carburettor fitted in the intake manifold of an internal
combustion engine, operating under constant reduced pressure
conditions, and comprising a main accelerator controlled
throttle-valve in the manifold, an auxiliary throttling member
subjected to the reduced pressure in the manifold on the upstream
side of the main throttle valve and defining with the latter a
fuel-and-air mixing chamber, an emulsion-forming chamber, a
fuel-fed jet opening into said emulsion-forming chamber and a
needle valve controlling said jet and controlled by the auxiliary
throttling member, the provision of at least one input port feeding
air into the emulsion-forming chamber in amounts corresponding
substantially to the complete burning of the fuel under idling and
reduced load conditions, for which the auxiliary member is closed
and of a connection between the emulsion-forming chamber and the
mixing chamber including at least one horizontal small diameter
tube provided with radial perforations, starting from the bottom of
the emulsion-forming chamber, a large-diameter channel opening into
the mixing chamber and fed by said small diameter tube, and an air
feeding channel starting from the upper end of the emulsion-forming
chamber and opening obliquely into said large diameter channel
above the end of the small-diameter tube feeding the large diameter
channel.
2. A carburettor as claimed in claim 1, comprising a conical valve
controlling one of the input ports and a member controlled by the
rotary speed of the engine and by the position assumed by the main
throttle valve and controlling said conical valve to thereby modify
the cross-sectional area of the port and consequently the richness
of the fuel-and-air mixture when the main throttle valve is
substantially closed and the rotary speed of the engine is above a
predetermined value.
3. A carburettor as claimed in claim 1, comprising a conical valve
controlling one of the input ports, a vacuum chamber including a
diaphragm controlling said conical valve, a three-way electrically
controlled valve adapted to connect selectively the inside of the
vacuum chamber with the external atmosphere and with a point of the
engine intake manifold on the downstream side of the main throttle
valve, a circuit energizing said valve, a tachometric relay
controlled by the rotary speed of the engine, and a switch inserted
in series with said relay in the valve energizing circuit to make
said valve connect the vacuum box with the manifold whenever the
main throttle valve is substantially closed and simultaneously the
rotary speed of the engine is above a predetermined value, and
connect the vacuum box with the atmosphere in all other cases.
4. A carburettor as claimed in claim 1, comprising a conical valve
controlling one of the input ports, a vacuum chamber including a
diaphragm controlling said conical valve, a three-way electrically
controlled valve adapted to connect selectively the inside of the
vacuum chamber with the external atmosphere and with a point of the
engine intake manifold on the downstream side of the main throttle
valve, a circuit energizing said valve, a tachometric relay
controlled by the rotary speed of the engine, and a switch inserted
in series with said relay in the valve energizing circuit to make
the valve connect the vacuum box with the manifold whenever the
main throttle valve is substantially closed and simultaneously the
rotary speed of the engine is above a predetermined value, and
connect the vacuum box with the atmosphere in all other cases, and
a further switch controlled by the temperature of the
engine-cooling medium and controlling the valve energizing circuit
to make the valve connect the inside of the vacuum box with the
manifold whenever said temperature sinks underneath a predetermined
value.
5. a carburettor as claimed in claim 1, comprising a conical valve
controlling one of the input ports, a vacuum chamber including a
diaphragm controlling said conical valve, a three-way electrically
controlled valve adapted to connect selectively the inside of the
vacuum chamber with the external atmosphere and with a point of the
engine intake manifold on the downstream side of the main throttle
valve, a circuit energizing said valve, a tachometric relay
controlled by the rotary speed of the engine, a switch inserted in
series with said relay in the valve energizing circuit to make the
valve connect the vacuum box with the manifold whenever the main
throttle valve is substantially closed and simultaneously the
rotary speed of the engine is above a predetermined value, and
connect the vacuum box with the atmosphere in all other cases, a
further switch controlled by the temperature of the engine-cooling
medium and controlling the valve energizing circuit to make the
valve connect the vacuum box with the manifold whenever said
temperature sinks underneath a predetermined value and
hand-operable means controlling the conical valve to make the
latter close the corresponding port when starting the engine under
low temperature conditions.
6. A carburettor as claimed in claim 1, comprising a conical valve
controlling one of the input ports and hand-operable means
controlling the conical valve to make the latter close the
corresponding port when starting the engine under low temperature
conditions.
Description
Our invention has for its object improvements in carburattors
operating under a constant reduced pressure. Carburettors of such a
type are generally provided with a main throughput adjusting flap
controlled by the accelerator pedal and with a transversely shifted
auxiliary flap or piston, adapted to move under the action of the
reduced pressure prevailing in the mixing chamber located between
two closing members whereby a substantial constant reduced pressure
is obtained in said mixing chamber. The auxiliary flap or piston is
connected in this case with a needle valve adapted to move inside
the opening of a jet so as to release the latter to an extent
varying with the position of the needle valve and consequently of
the auxiliary flap or piston. The jet and its needle valve are
fitted inside an emulsion-forming chamber, connected on the one
hand with the mixing chamber through suitable channels and on the
other hand with the external atmosphere through one or more ports
which may be opened and closed to a varying extent in accordance
with the actual operative conditions of the engine, in order to
obtain a predetermined reduction in pressure in the
emulsion-forming chamber and thereby in the amount of fuel to be
injected.
Such carburettors are generally satisfactory within a large range
of operative conditions for the engines incorporating said
carburettors. There are however two operative conditions for which
problems arise as concerns both pollution of the atmosphere by the
exhaust gases and acceleration. In fact, when idling, the engine
produces unburnt residuary components and carbonic gas to an
increasing extent by reason of the air flowing then at a slow rate
and the atomization of the fuel being poor. Furthermore, when the
engine decelerates, the main flap is closed while the engine is
still running at a high speed and therefore difficulties arise
which are ascribable to the considerable reduction in pressure
prevailing in the admission manifold. It has already been attempted
to remove this last drawback by cutting off completely or partly
the admission of fuel during the deceleration stage. It has been
found however, in the case of certain engines that the contents of
unburnt components and carbonic gas do not then decrease in the
exhaust gases and that in contradistinction, they increase and,
generally speaking, greater difficulties arise in such a case when
accelerating after such a deceleration stage.
Our invention has for its object to cut out such difficulties and
provides the following improvements in the carburettors of the type
referred to:
the air input port or ports of the emulsion-forming chamber are
provided with a cross-sectional passage area such that all or
almost all the air required for burning passes through said ports
when the engine is not subjected to any load and runs under idling
conditions and possibly under initiating acceleration conditions,
the auxiliary flap being then completely closed; on the other hand
the emulsion-forming chamber is connected with the mixing chamber
through one or more horizontal smalldiameter mixture-conveying
tubes starting from the bottom of the emulsion-forming chamber and
opening into an emulsion-forming tube of a larger diameter opening
in its turn into the mixing chamber while a passageway for air is
provided, starting from the upper end of the emulsion-forming
chamber and opening into the emulsion-forming tube in a direction
oblique with reference to the fuel-conveying tubes, which latter
are provided in registry therewith with radial bores furthering the
formation of the emulsion;
a conical valve adapted to move axially of one of the air input
ports in the emulsion chamber is connected with a control member,
the position of which depends on the rotary speed of the engine and
on the position of the main flap whereby the cross-sectional area
of said port is reduced and consequently the mixture becomes richer
when the main flap is closed or substantially so and the engine
revolves at a speed above a predetermined value;
as a further development of the invention, the last-mentioned
conical valve is connected with the diaphragm of a casing or vacuum
box the inside of which is subjected to a reduced pressure and is
connected through a pipe with the engine input manifold on the
downstream side of the main flap through the agency of a three-way
electrically controlled valve controlled by a tachometric relay and
a switch controlled by the main flap so as to connect the inside of
the casing subjected to a reduced pressure with the admission
manifold when the main flap is closed or substantially so and the
rotary speed of the engine is above a predetermined value, said
connection being cut off when the main flap opens or when the
engine speed drops underneath said value, so as to set the inside
of the casing under atmospheric pressure through the third way of
the electromagnetically controlled valve;
the electromagnetically controlled valve may also be actuated by a
thermosensitive switch operated by the temperature of the
engine-cooling fluid, so as to connect the inside of the casing
subjected to a reduced pressure with the admission manifold when
said temperature lies under a predetermined value whereby the
conical valve reduces the cross-sectional area of the port
controlled by it and consequently ensures the production of a
richer carburetted mixture;
a conical member engaging one of the air input ports in the
emulsion chamber may also be connected with a hand-operable member
adapted to close said port when the engine is to be started under
low temperature conditions.
By way of example and with a view to further the understanding of
the invention, the single figure of the accompanying drawing is a
diagrammatic cross-section of an embodiment of our improved
carburettor.
In said figure, it is apparent that the body 1 of the carburettor
is provided with the main throughput-controlling flap 2, the pivot
2a of which is connected through suitable means which are not
illustrated with the accelerator pedal. The extensions 3 of the
body 1 is provided with an auxiliary flap 4 the transversely
shifted pivot 4a of which is connected with the needle valve 5
through means which are not illustrated. The mixing chamber 1d
extends between the two flaps 2 and 4. The float chamber 1c is fed
with gasoline through the connection 21 secured to the cover,
incorporated with the extension 3, by the screw 20. The float 23
defines the level through the agency of the needle valve 24
cooperating with the connection 22 opening into the connection
21.
The emulsion-forming chamber 1e communicates with the mixing
chamber 1d through the emulsion-forming tube 9 into which the
air-feeding channel 8 and the gasoline-feeding duct or ducts 10 fed
by the emulsion-forming chamber open. The air feeding channel 8 is
directed obliquely with reference to the cooperating end of the
duct or ducts 10 which are provided with radial bores 10a adapted
to perfect the emulsion. The emulsion-forming tube 9 opens into the
venturi-shaped section 1a of the mixing chamber 1d. The gasoline
enters the emulsion-forming chamber 1e through the jet 7 the
opening port of which is controlled by the conical end 5a of the
needle valve 5 in accordance with the position assumed by the
auxiliary flap 4. The needle valve 5 slides inside a guiding member
6.
The amount of fuel passing out of the jet 7 depends furthermore on
the reduced pressure prevailing in the emulsion-forming chamber 1e,
which pressure depends in its turn on the constant cross-sectional
passageway area afforded by the channel 8 and on the
cross-sectional passageway area afforded by the air input ports of
the emulsion-forming chamber 1e. Said chamber 1e may be provided
with a plurality of air input ports controlled by suitably actuated
flaps so as to make the mixture richer upon acceleration and power
for other circumstances, so as to prevent the presence of unburnt
components and of carbonic gas in the exhaust gases or a
modification in the input of air with modifications of the
atmospheric pressure and the like.
In the case illustrated, two correcting flaps are provided of which
that referenced as 16 is carried by a diaphragm 17 and is adapted
to control an auxiliary air input through the channel 1f so as to
open the latter whenever the pressure in the admission manifold
sinks underneath a predetermined value. Said pressure is tapped off
a point located with reference to the flap 2 in a manner such that
the reduction in pressure can act only if the flap 2 begins
opening. This causes the mixture to become poorer whereby the
consumption of fuel is reduced under partial loads. To this end,
the chamber 19 extending between the diaphragm 17 and the cover 15
is connected with the admission manifold the reduced pressure in
which shifts the diaphragm against the pressure exerted by the
spring 18.
The conical valve 12 cooperates with the opening 11a in the washer
11 urged against its seat by the spring 37. Said frustoconical
valve 12 is rigidly secured to the barometric bellows 14 by the
screw 13, said bellows being secured furthermore to the rod 14a
projecting out of a vacuum box 25 screwed onto the body 1 by the
nut 26 fitted over the elastic washers 27. Air being admitted into
the emulsion-forming chamber 1e through the opening 1b, the vacuum
box 25 may be shifted by the starter rod 28 while its output pipe
29 is connected with the admission manifold through the
electromagnetically controlled three-way valve 30, the output 32 of
which opens into said manifold and the output 31 of which opens
into the atmosphere.
The electromagnetically controlled valve 30 is controlled by a
tachometric relay 35 energized by a switch 36 provided underneath
the pivot 2a of the main flap 2 and also independently thereof by a
heat sensitive switch 34 controlled by the temperature of the
cooling fluid of the engine.
It should be remarked that the input port or ports of the
emulsion-forming chamber 1e are designed in a manner such that when
the engine is idling, the fuel-burning air passes entirely or
substantially so through said ports, the auxiliary flap 4 being
closed so that the emulsified carburetted mixture passes out of the
emulsion-forming tube 9 under excellent fuel-atomizing conditions
even if the air input is very small. It should also be remarked
that the conical valve 12 forms a means for very simply adjusting
the fuel contents in the mixture through its conventional
connection with the barometric bellows 14, so as to be shifted
bodily therewith under the influence of the reduced pressure in the
admission manifold. The corrections thus obtained depend on the one
hand on the temperature of the fluid cooling the engine upon
opening of the communication between the connections 29 and 32 as
provided by heat-controlled switch 34 when the temperature of the
cooling fluid sinks underneath a predetermined value. When such a
communication is obtained, vacuum is established in the vacuum box
25 whereupon the conical valve 12 is drawn downwardly.
Consequently, the cross-sectional operative area of the port 11 a
decreases, which results in an increase in the reduction in
pressure in the emulsion-forming chamber 1e and in an increased
richness of the fuel and air mixture. On the other hand, the
electromagnetically controlled valve 30 is energized by the
tachometric relay 35 controlled by the switch 36. This has for its
result a communication between the connections 29 and 32 when the
engine is decelerated while the main flap 2 is closed and the
engine continues running at a high speed. The reduced pressure acts
on the vacuum box 25 and there is obtained a further downward
shifting of the conical valve 12 and consequently an increased
richness for the mixture. It should be remarked that this modus
operandi leads to a substantial reduction in the contents of
unburnt residuals and carbonic gas in the exhaust gases, although
such a modus operandi is in strict contradiction with all prior
practice attempting to reach a similar result during a deceleration
stage. The provision of a nozzle in the connection 32 allows
furthermore an adjustment of the more or less considerable delay in
the operation of the mixture-enriching means.
It should be remarked that the arrangement described which is
highly advantageous in certain cases may not be suitable in other
cases and in fact it may be reversed so as to reduce the richness
of the mixture during deceleration without widening thereby the
scope of the invention as defined in the accompanying claims.
The elastic fitting of the vacuum box 25 on the body 1 through the
agency of the elastic washers 27 and the control of said vacuum box
by a starter rod 28 ensures the formation of a richer mixture for
starting under cold temperature conditions conditions in a
particularly simple manner since the drawing of the starter rod 28
shifts the vacuum box system bodily downward so as to close the
port 11a.
* * * * *