FR2484541A1 - Adjustable slow running jet - has mixture control system with auxiliary combustion air inlet in needle valve in mixing chamber - Google Patents

Abstract

The slow running jet fits in the carburettor auxiliary float chamber. The carburettor has an air inlet (Ar) and a duct (2b) for the slow running mixture (Mr). The jet is screwed into the side of the chamber. Fuel is admitted through the side of the block (4) at the orifice (6) and is released through the orifice (7). The mixing chamber (5) of the jet is fitted with a needle valve (11) which is located by a coil spring (24) and controlled by the screwed rod (17). Air is admitted through the channel (13) in the centre of the needle valve.

Description

PROCESS AND JET FOR THE PRODUCTION OF A
SLOW MOTION CARBIDE MIXTURE IN AN EXPLOSION ENGINE
The invention relates to a method for carrying out
tion of an idle fuel mixture1 intended to be delivered
in an intake manifold of an internal combustion engine; she
extends to an idle jet to be mounted on a coach
auxiliary idling burator for the implementation of the
method of the invention.

We know that, in an internal combustion engine,
when the throttle valve of the main carburetor is closed,
the idling speed is generally ensured by a carburetor
auxiliary equipped with an idle jet. In the sprinklers
known needle type, there is a single room for
make the air-fuel mixture.

/ This type of sprinkler has several disadvantages
come. First, the mixture produced has a bad
homogeneity and significant overconsumption ensues
in fuel when the engine is idling. Now, for o
driving in built-up areas, consumption under this regime has a
very important influence on average vehicle consumption
ass; moreover, the emission gases, imperfectly burnt at
idle, are a source of serious pollution.

/ moving needle./ In addition, the known idling nozzles, à 'are closed relatively suddenly when the engine speed
engine leaves idle speed to shift to idle speed
higher intermediate; sometimes there is a knock in
engine operation, with possible risks of
wedging.

The present invention proposes to remedy
faults in known idle jets.

An object of the invention is in particular
to indicate an improved process for carrying out the mé
idle fuel line, ensuring a homogeneous
birth of this mixture.

Another object of the invention is, thus,
allow significant savings in fuel consumption,
especially when driving in built-up areas.

Another object of the invention is to per
shift from idle to higher intermediate speeds and eliminate the risk of stalling the engine.

 Another objective is to give the option, at intermediate regimes or even at high regimes, to improve the main fuel mixture in order to allow better combustion and to allow significant savings on consumption at these regimes.

The process referred to by the invention is of the type in which an idle fuel flow C r is mixed with an idle air flow A r in an auxiliary idling carburetor; according to the present invention, the mixing is carried out in two phases
a pre-mixing phase, carried out in a first chamber, known as the turbulence chamber, and consisting in mixing the idle fuel flow C r with a small make-up air flow Aa compared to the flow A r in order to obtain a highly fueled premix M of air and fuel, p
and a final mixing phase, carried out in a second chamber, called the mixing chamber, and consisting in mixing the premix M p with the idle air flow Ar.

According to an embodiment giving good results, the premix M p is preferably carried out by means of a make-up air flow A a of between approximately 2% and 20% relative to the air flow of idle A
r
Experiments have shown that such a process makes it possible to obtain a fuel-hokogenic mixture which leads to significant savings in consumption during idling of the engine.

The homogeneity of the fuel mixture obtained is further improved by implementing the following advantageous operating conditions
- the premix M is produced in the turbulence chamber by guiding the make-up air A a and the fuel flow C r therein in relative perpendicular or intersecting directions deviating by less than 30 * from the perpendicular,
the premix M p is guided at the outlet from the turbulence chamber in a direction, first radial, centrifugal, at the immediate outlet from said turbulence chamber, then longitudinal towards the mixing chamber,
- the final mixture M r is produced in the mixing chamber by guiding the idle air A r and the premix towards it in relative perpendicular or intersecting directions deviating by less than 30 "from the perpendicular .

A fuel mixture is thus obtained which benefits from exceptional homogeneity, which seems to correspond to optimal conditions for reducing fuel consumption and pollution as much as possible at idle.

Furthermore, according to another characteristic of the process of the invention, the premix Mp is produced by means of a fuel flow rate Cr which is caused to vary in inverse function to the engine speed, so as to be maximum at idle speed and decrease at intermediate regimes to a minimum value of zero or very low, at high regimes.

This gives a very gradual transition from idle speed to higher speeds without risk of stalling the engine; moreover, by an appropriate adjustment of the minimum value of the flow rate Cr, the operator can - depending on the type of engine and operating conditions - adjust the richness of the main fuel mixture leaving the main carburetor, either by enriching this mixture by the admission of a low flow rate of additional fuel C r, or by oxygenating it thanks to the additional air admitted.

 The above-mentioned variation in the fuel flow rate Cr will be obtained in a manner known per se by the depression effect generated by the engine, depression which decreases at the level of the auxiliary idling carburetor when the engine speed drops. According to a characteristic of the process of the present invention, this vacuum is transmitted to the turbulence chamber in order to act on a very tapered needle, movable in a fixed range, the fuel being brought to pass before being admitted into said turbulence chamber the passage between said needle and its range.

 The invention extends to a new idling nozzle which is intended to be mounted on an auxiliary idling carburetor with a view to implementing the method defined above.

This nozzle is of the type comprising means for supplying idle air Ar, means for discharging the fuel mixture Mrî for supplying fuel Cr, a mixing chamber with which the means for supplying air communicate A and the
r means for discharging the mixture M and an adjustment needle
r of the fuel flow Cr.

According to the present invention, this nozzle comprises
a turbulence chamber in which the needle is housed in order to define, with a fixed range, a passage in communication with the fuel supply means Cr,
means for supplying make-up air A opening into the turbulence chamber,
/. and means for connecting the turbulence chamber and the mixing chamber.

Other characteristics of the invention will emerge from the description which follows with reference to the appended drawings which present, by way of nonlimiting example, a preferred embodiment; on these drawings which form an integral part of the present description
q FIG. 1 is an axial section, on an enlarged scale, of a nozzle according to the invention, mounted in a well of an idle auxiliary carburetor which is partially seen in this figure,
FIG. 2 is a section of the nozzle through a transverse plane AA,
FIG. 3 is a diagrammatic view illustrating the mounting of the nozzle in an assembly of carburetion of an internal combustion engine,
Figures 4 and 5 are explanatory diagrams of operation, showing the nozzle respectively in idle speed and at a higher speed.

The idle jet 1 shown by way of example in the figures is called to be mounted in a well of the idle auxiliary carburetor which can be seen in 2 in FIGS. 1 and 3. This well of the auxiliary carburetor conventionally comprises a duct 2a for the arrival of the idle air Arr a duct 2b in the extension of the
first for the departure of the idling fuel mixture Mr and a duct 2c for distributing the idling fuel.

In addition, it is pierced with a partially tapped hole into which the nozzle 1 according to the invention is screwed.

 The latter comprises a hollow body 3 provided with an external thread for mounting in the auxiliary carburetor well 1.

 This hollow body 3 contains a fuel inlet nozzle 4 which is force-fitted through one end of the latter.

This nozzle 4 delimits in an annular groove of its peripheral periphery a mixing chamber 5 which communicates, on the one hand, with the conduit 2a of the carburetor by a channel 6 of air intake Ar, on the other hand, at l 'opposite, with the conduit 2b of the carburetor by a channel 7 for discharging the fuel mixture M which is produced in
r the idle jet.

 Furthermore, the nozzle 4 is pierced axially with a fuel supply channel 8 which communicates with the fuel line 2c and which opens at its other end by a conical bearing 9 in a turbulence chamber 10. Inside a movable needle 11 is arranged in this chamber 10 which is associated with sliding means allowing it to slide with gentle friction relative to the body 3.

In the example, these sliding means consist of a head 12 which carries the movable needle 11.

 This movable needle It has at the fixed bearing 9 a very tapered conical shape, with an apex angle approximately between 0e and 30, in particular of the order of 20 to 25 ". Of course, the conical bearing 9 has a conjugate form.

These elements are thus adapted to inject the fuel into the turbulence chamber 10
in a longitudinal direction or deviating by less than 30 'from the longitudinal direction.

 In addition, the needle 11 includes a longitudinal channel 13 for supplying make-up air Aasqui is formed along one axis thereof. This channel 13 opens at right angles to the turbulence chamber 10 by radial channels 14. The make-up air leaving the channels 14 and the fuel passing between the needle 11 and its range 9 thus have relative directions deviating less 30th from the perpendicular, when they are brought into contact in the turbulence chamber.

Furthermore, the nozzle 4 is provided with two diametrically opposite flats, which delimit lopgltudinal channels 15 between the latter and the body 3; these channels 15 open at one end into the mixing chamber 5 and communicate at their other end with the turbulence chamber 10 by radial channels 16 situated around this turbulence chamber.

The premix M produced in the chamber 10 p 'which is subjected to very significant turbulence, is thus guided at the outlet from this chamber, first radially in the centrifugal direction in the channels 16, then longitudinally towards the mixing chamber 5 .

This premix arrives in this chamber 5 with a longitudinal direction and comes into contact with the idle air A r arriving radially, in a direction perpendicular thereto.

Experiments have shown that these conditions seem to correspond to the ideal conditions for obtaining a very intimate and perfectly homogeneous mixture between the air and the idling fuel.

 Furthermore, the make-up air A a is guided towards the channel 13 of the movable needle through a rod 17 which is screwed into a plug 18, itself screwed to the end of the body 2. The rod 17 comprises a axial channel 19 through which the make-up air arrives; this channel is open at the outer end of the rod 17 and is associated with a cap 20 for adjusting the admitted make-up air flow rate. This cap comprises radial openings 21 opening at its screw pitch and the depth of screwing of said cap on the rod 19 makes it possible to adjust the pressure drop and therefore the air flow rate A a flowing at the level of the no screws. A lock nut 22 allows the cap 20 to be locked in the chosen position.

In addition, the rod 19 serves as a support by a flange 23 to a spring 24, which by its other end comes to bear with the head 12. This spring therefore pushes this head and its needle, in the direction of the spacing of the latter in relation to the scope 9.

 The rod 19 can be more or less deeply screwed into the plug 18 in order to adjust the restoring force exerted by the spring. A lock nut 25 allows the rod to be locked in the chosen position.

Figure 3 illustrates the assembly of the nozzle of the invention; we find in this figure the classic elements of a carburetor combustion engine assembly 26 of fuel supply with its float, main carburetor 27, throttle valve 28, well of the auxiliary carburetor 2 with its wealth screw 29, the nozzle 1 according to the invention being mounted on this well.

Figure 4 shows the nozzle during operation in idle speed when the throttle valve 28 is closed. The depression generated by the engine being insufficient at this speed, the action of the spring 24 moves the needle away from its conical bearing. The admitted idle fuel flow C r is maximum. This flow reaches the turbulence chamber 10 where it is brought into contact, perpendicularly or in a direction close to the perpendicular, with the make-up air Aa
The flow of this make-up air A is preliminary
ably adjusted to be low compared to the idle air flow rate A r which arrives conventionally in the well of the idle carburetor 2. For example, good results are obtained in most engines, by adjusting this flow rate AT
a at a value of the order of 4 to 5% relative to the air flow Ar
A highly carburized premix M is thus produced, in a first phase. in the turbulence chamber 10, then is delivered to the mixing chamber 5 where it is mixed in a second phase with the idle air flow Ar At the outlet of this chamber 5, the final fuel mixture
Mc of an exceptional homogeneity is sent in the tubulu
engine intake re.

When the engine speed increases, the depression generated by it increases and the movement of the very sharp moving needle towards its range very gradually reduces the fuel rate of the fuel mixture Mc, the latter always retaining its excellent homogeneity. This very gradual nature of the fall in the richness of the mixture suddenly avoids and eliminates the risks of stalling at intermediate speeds (up to 2000 rpm (rotation per minute) approximately)
The movable needle can be adjusted as shown in Figure 5 so that the minimum idle fuel flow is not zero at full speed, which allows, in some engines, to regulate the fuel rate of the fuel mixture produced in the main carburetor, especially when decelerating.

 It is also possible, in other cases, to authorize at high speeds the complete closure of the needle, allowing it to come to apply against its conical bearing.

 This adjustment of the minimum fuel flow to a low or zero value can be ensured by means of the head 12 which carries the needle; it suffices to position the latter relative to the needle, either so that in the front position, it abuts against the body 3 while preserving a minimum passage between the needle and its range, or on the contrary, that the needle is free to come into contact with its scope.

 Of course, the invention is not limited to the terms of the preceding description, but includes all the variants. In particular an air filter can be inserted in the rod 17 for supplying make-up air A a or any passage of the device which conducts air.

Claims (13)

1 / - Method for producing an idling fuel mixture M r intended to be delivered to an intake manifold of an internal combustion engine, of the type in which a flow of idling fuel C is mixed with a flow of air of  r idle speed Ar in an auxiliary idle carburetor, characteristic  r se in that the mixing is carried out in two phases a premixing phase, carried out in a first chamber, called the tuEbulence chamber, and consisting in mixing the flow of idle fuel C r with a flow of make-up air A low compared to the flow A in order to obtain  r keep a highly carburized premix Mp of air and fuel,  p and and a final mixing phase, carried out in a second chamber, called the mixing chamber and consisting in mixing the premix N with the idle air flow Ar. p  2 / - Method according to claim 1, charac terized in that the premix Mp is produced by means of a die  make-up air bit A has between 2% and 20% relative to the idle air flow Ar  3 / - Method according to one of claims 1 or 2, characterized in that the premix M is produced at  p by means of a fuel flow Cr which is caused to vary by  r inverse function of the engine speed, so as to be maximum at idle speed and to decrease at intermediate speeds to a minimum value, zero or very low, at high speeds.  4 / - Method according to claim 3, wherein the variation of the fuel flow C is obtained by  r the effect of depression generated by the engine, characterized in that said depression generated by the engine is transmitted to the turbulence chamber in order to act on a very tapered needle, movable in a fixed range, the fuel being brought to cross before its admission into said turbulence chamber the passage between said needle and its range. 5 / - Method according to one of claims 1, 2, 3 or 4, characterized in that the premix M is made in the turbulence chamber by guiding the make-up air A a and the fuel flow C r in relative perpendicular or intersecting directions deviating by less than 30 from the perpendicular. 6 / - Method according to claim 5, characterized in that the premix Np is guided at the outlet of the turbulence chamber in a direction, first radial, centrifugal, at the immediate outlet of said turbulence chamber, then longitudinal towards the mixing chamber.  7 / - Method according to one of claims 1, 2, 3, 4, 5 or 6, characterized in that the final mixture Mr is produced in the mixing chamber by guiding the idle air A r and the premix. M p in relative perpendicular or intersecting directions deviating by less than 30 'from the perpendicular.  8 / - Idle jet called to be mounted on an auxiliary idle carburetor for the implementation of the method according to one of claims 1, 2, 3, 4, 5, 6 or 7, said nozzle comprising means for supplying idle air Ar, means for discharging the fuel mixture Mr, means for supplying fuel Cri a mixing chamber (5) with which the means for supplying air A r and the means for discharging the mixture Nr, and a needle (11) for adjusting the fuel flow C said idle jet being characterized in that it comprises a turbulence chamber (10) in which the needle (11) is housed with a view to defining, with a fixed range (9), a passage in communication with the fuel supply means Cri means for supplying make-up air A  opening into the turbulence chamber (10), and means for connecting the turbulence chamber (10) and the mixing chamber (5).  9 / - Idle jet according to claim 8, characterized in that the means for supplying make-up air A comprise a longitudinal channel (13) formed in  has the needle (11) along the axis thereof and radial channels (14) connecting approximately at right angles to this longitudinal channel (13) with the turbulence chamber. (10), said needle (11) and its fixed bearing (9) being arranged to inject fuel into said turbulence chamber (10) in a longitudinal direction or deviating by less than 30 from the longitu dinal direction. 10 / - Idle jet according to one of claims 8 or 9, characterized in that the means for establishing communication between the turbulence chamber (10) and the mixing chamber (5) comprise radial channels (16) located around the turbulence chamber and the longitudinal channels (15) into which said radial channels open, these longitudinal channels (15) themselves opening into the mixing chamber (5). 11 / - Idling jet according to one of claims 8, 9 or 10, characterized in that the means for supplying make-up air a comprise means for adjusting (20, 21) the flow rate of said air. booster.  12 / - Idle jet according to one of the reyêndications 8, 9, 10 or II, characterized in that the needle (11) has a very tapered conical shape, with an angle at the top approximately between 100 and 30, said needle longitudinally movable being associated with elastic means (24) agencies to move it beyond its reach (9).  13 / - Idle jet according to one of claims 8, 9, 10, 11 or 12, characterized in that it comprises  a hollow body (3) with an external thread and comprising the idle air supply channel (6) A a and the fuel mixture evacuation channel (7) Mr,  . a fuel inlet nozzle (4) housed in the body (3) and delimiting therewith the mixing chamber (5), this nozzle (4) comprising the turbulence chamber (10), the means (15, 16) connecting the turbulence chamber and the mixing chamber, the conical needle bearing (9) and the fuel supply channel (8),  and the movable needle (II), arranged in the turbulence chamber (10) and associated with means (12) of axial sliding relative to the body (3), said needle (11) comprising means (13, 14) d make-up air supply A. at