CA1052203A

CA1052203A - Apparatus for preparing a liquid fuel for carburettors

Info

Publication number: CA1052203A
Application number: CA218,399A
Authority: CA
Inventors: H. C. Paul August
Original assignee: Individual
Current assignee: Individual
Priority date: 1974-01-22
Filing date: 1975-01-22
Publication date: 1979-04-10
Also published as: DD115739A5; DE2402970B2; DE2402970A1; JPS50112621A; NL164933C; SU703043A3; NL164933B; FR2258535A1; ES434185A1; FR2258535B1; GB1475451A; NL7500713A; BR7500437A; JPS5713752B2; IT1036732B; SE7500388L

Abstract

ABSTRACT OF THE DISCLOSURE

An apparatus for atomizing a liquid fuel for a petrol engine or an engine with central fuel injection, in which combustion air is fed to a carburettor downstream of a throttle valve and a fuel injection device through two opposed slots in the suction manifold. The slots are so dimensioned that, in consequence of the low pressure prevailing in the suction system of the engine, the combustion air at idle and/or at transition and partial load conditions flows from the slots at substantially the speed of sound in a direction which is substantially perpendicular to the direction of suction.

Description

iOS,'~Z~3 This invention relates to improvemcnts in apparatus for the preparation of fuel mixtures for carburettors.
The object of the invention is an apparatus for the preparation of liquid fuels for petrol engines and engines with a controlled fuel injection by the feeding of combustion air down-stream of the throttle valve of the carburettor and of the injection device through two slots opposite one another in the exhaust passage.
The invention further relates to an apparatus for the control of the accelerator pump and of the throttle valve the internal com-bustion engines by the accelerator which is advantageously presentin such an apparatus.
The problem of the invention is to prepare an idle running as well as also in the transition and partial load operation of the engine, a combustible mixture such that fuel is finely atomized and the size of the mist drops is about a maximum of 0.5 mm.
The solution of this problem consists in that the slots are so dimensioned that in consequence of the lower pressure pre-vailing in the exhaust system of the engine the combustion air in the idle running and/or in the transition and partial load operation of the engine flows from the slots at or almost at the speed of sound, whereby the direction of flow of the combustion air supplied is at right angles or substantiall~ at right angles to the direction of exhaust. Due to the high speed of flow the condensate forming on the walls of the exhaust opening is atomized as well as also in the centre below the throttle valve of the carburettor due to the currents meeting one ano~her at high speed a tuburlence zone is ljr:~

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:~05'~ 3 produced which atomizes those fuel drops which are formed primarily in the idle running, transition and partial load operation of the englne .
Thus a uniform condensate and drop-free mixture is produced before the entry into the combusted chambers of the engine and the fuel contained therein is not deposited on the walls of the cylinder which leads to low CO and CH values. The operation with condensate and drop-free fuel air mixtures gives the smallest fuel consumption which is theoretically possible so that the combustion air sucked in is fully utilized.
When the combustion air in the idle running and transition range flows from the first slot and-additionally the combustion air in the partial load range of the engine flows from the second slot at or about the speed of sound and in the combustion air feed to the slot in the partial load operation of the engine determining the speed of the combustion air a control member, for example, a throttle valve being provided the opening of which depends on the opening of the carburettor throttle valve to give an improved adaptation of mixture preparation to the actual operating condition of the engine.
In addition to or instead of combustion air engine exhaust can also be fed to the slot effective in the partial load operation which as is known effects the reduction in the formation of NO.
If the apparatus is to be used as an additional apparatus for motor vehicles already in service the engines of which are pro-vided with circulating air carburettors then it is expedient if the feed for combustion air in idle running is closed and opens only from transition operation of the engine. These modern carburettors al-ready have in them a system for the preparation of the idle running mixture ljr~

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" S,~Z~[~3 which would be disturbed if a further such system were effective in an additional apparatus according to the invention.
As, however, with these circulating air carburettors the mixture improvement is effected only in the idle running and not in the transition and partial load operation, an apparatus according to the invention adapted to these conditions for the preparation of the mixture in the transition and partial load operation is very useful in respect of exhaust gas poisoning and utilization of fuel.
There is fed to the carburettor a fuel air mixture, which contains condensate and fuel drops, at high speed combustion air and/or engine exhaust gases or other gases which are heated by a heat exchanges electrically and/or by means of exhaust gases.
In consequence of the fine atomizing of the fuel with the apparatus according to the invention it is possible to operate with air excess in the operating ranges of the engine in which hitherto operation had to be with excess of fuel.
There is therefore achieved, besides an optimum utilization of fuel, an optimum fuel combustion and in conjunction therewith almost poison~free exhaust gases. Expansion devices for the deoxidation of exhaust gases such as the insertion of catalysts or after-burners in the exhaust gas system are therefore super-fluous or only necessary to a very limited extent.
Essential furthermore is to use for the combination of the condensate and drop-free mixture preparation with a o~aratively weak heat exchanger whereby the term weak heat exchanger relates to the fact tnat this prepares the fuel to a fine mist, but does not ywl/~ , _ 4 _ 105;~203 evaporate the fuel, in the mixture.
Without such a fuel preparation before the heat exchanger in the outer area of the suction pipe there would be a richer mixture with condensate and in the minor part a poorer mixture. That means: If it is desired to prepare fully the poorer mixture with the high fuel portion then so much heat energy is needed that the poor mixture would be completely evaporated and exactly that is to be avoided.
Only the combination of the condensate and drop-free mixture preparation and homogenuous mixture composition brings about the said advantage with a heat exchange of low output.
The mixture is further hased on the problem of carrying out the control of an accelerator pump so that at the moment of acceleration or of starting an immediate supply of combustion air with fuel is provided but in the interest of lower CO and CH values the adjustment of the fuel air mixture is maintained at about or above.
A further object of the invention is also to achieve a better preparation of the fuel from the accelerator pump.
The solution of this problem consists in delay means known per se in the transmission movem,ent between the accelerator, accelerator pump and throttle valve connected so that with acceleration the accelerator pump is actuated before the throttle valve.
By this measure it is achieved that first of all the fuel mist is present which is easily taken off by the air and carried in this at the same speed to feed the engine. Thereby there results at the moment of acceleration or the starting an ywl/,~ 5 -- ~ :
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~OS;~Z03 immediate supply of combustion air upon opening of the throttle valve with the finest fuel mist well distributed in the combustion air which is supplied, condensate and drop-free, uniformly to all cylinders.
Embodiments of the invention are described with reference to the accompanying drawings.
Fig. 1 is a diagrammatic representation of the arrangement of the apparatus according to the invention;
Fig. 2 is a section of apparatus on line C-C of Fig. 3;
Fig. 3 is a section of apparatus on line A-A of Fig. 2;
Fig. 4 is a section of apparatus which is provided as an additional apparatus to the circulating air carburettor;
Fig. 5 is a section on line B-B of Fig. 4;
Fig. 6 is a diagrammatic view similar to Fig. 1 of a further embodiment;
Fig. 7 is a section similar to Fig. 2 of the embodiment according to Fig. 6;
Fig. 8 shows a part of the carburettor according to Fig. 9 with the injection tubes according to the invention;
Fig. 9 shows the foot of a carburettor with a delay device for the throttle valve;
Combustion air and fuel are fed separately to a carburettor 10 (Figs. 1 - 3). The fuel air mixture produced in the carburettor arrives via the apparatus 11 for the feeding of the fuel-air mixture into the suction pipe 12 of the engine 13 from which the exhaust gases are led off via the exhaust pipe 14.
In idle running and in transition there emerges only ywl/~ - 6 -.

~05'~ 3 or mainly fuel from the idle running system, not shown, of the carburettor, and is located on one side of the carburettor.
Downstream of the carburettor, through the inlet 1, the passageway

2 and the slit 3 of the apparatus 11 is fed the quantity of air which the engine 13 requires for the idle running operation with the throttle valve of the carburettor closed. The slit 3 is designed to determine the quantity of air. It has in addition almost the effect of a LAVALL nozzle. In the area of a low pressure of more than 0.6 atmospheres the air flowing in through the slit 3 reaches the speed of sound. This means that in idle running and transition the air flowing in through the slit 3 enters at such a speed that it slows as far as the opposite wall and sweeps over almost the whole area below the throttle-valve. Fine condensate which on the wall of the carburettor in idle running and transition running meets the slit 3 and is finely atomized. The apparatus 11 has a further feed 4 which is provided with a control valve 5.
To the control member there is connected a passageway 6 in the member 11 which with the slit 7 forms the limitation for the manifold 8 for the fuel-air mixture. The control valve 5 is connected to the carburettor throttle valve so that when idle running it is closed and then with the opening of the carburettor throttle valve it is likewise opened. The slit 7 with its passage is so designed that upon opening the control valve 5 at a vehicle speed of about 50 - 60 km per hour, that is, at a low to medium engine ouput the highest possible passage way of air is achieved. This means that with its partial load speed the air flowing through the slit 7 has a very high velocity up to the speed of sound. An entry of gas is now allowed on the remaining ywl/~ /, 7 :.

l(~S'~Z(~3 periphery of the passage 8 which acts in a condensate removing manner and additionally removes drops forming under the carburretor throttle-valve. Both gas and air currents which enter through the slits 3 and 7 strike against one another in the fuel air inlet manifold 8 at high flow, velocity and cause the atomization of condensate and fuel drops.
The feed 4 is provided with combustion air through an opening 16. In addition a further feed 15 may be provided which is connected to the exhaust pipe 14 of the engine 13.
A further control valve 17 which is in communication with the control valve 5 as well as with the throttle-valve, (not shown) of the carburettor 10, allows for the admixing of exhaust gas from the exhaust pipe 14 according to the load operation of thé
engine so for that through the fresh air inlet 1 and the slit 3 together with the inlet 16 a fuel air mixture with an excess of air is fed to the manifold 8 to the induction pipe 12 of the engine.
The control for the feeding of the exhaust gas takes place via the control valve 17 so that in the whole partial load range of the engine, possibly idle running excepted, excess of air prevails in the fuel air mixture so that the constituent parts contained in the fuel-air mixture are completely burnt without injurious exhaust gases due to incomplete combustion leaving the engine. It is lmportant that in the idle running operation of the engine in which the entry of the additional air is effected substantially via the slit 3 as well as in partial load operation of the engine in which the additional air is effected via the slit 3 and also via the slit 7 the fuel air yWl/f~ - 8 -, -~

iOS;~:03 mixture in the manifold 8 in consequence of the additional air emerging from the slits 3 and ;' the currents of additional air collide against one another and are finely atomized and due to the dimensions of the slits 3 and 7 and adaptation of the carburettor 10 an excess of air prevails which feeds uniformly to each individual cylinder of the engine a homogenuous fuel air mixture with finely distributed fuel particles with excess of air.
Furthermore the feeding ofexhaust gas via the control valve 17 effects in the partial load range a lowering of the NO content which contributes to the further deoxidisation of the exhaust gases.
In Figs. 4 and 5 an apparatus is shown which feeds additional combustion air only after the transition range of the engine and which is designed as an additional apparatus for circulating carburetted air and is designated by 18. The apparatus 18 is built in at the same place as the apparatus 11 according to Fig. 1. The carburettor 10 has in this case already a circulating air system for idle running operation.
Under the idle running system, not shown is located a slit 19 of the apparatus and on the opposite side, an inlet slit 20. Additional air is sucked in via an inlet 21 and controlled by a control valve 5 ~nifested as throttle-valve and flows via a passagewaY 22 into an annular , channel 24 ~7hich connects the slits 19 and 20 bo one another.
The additional air sucked in first reaches the slit 19 and emerges into the manifold 8. On the opposite side '~ ' additional air enters a little later through the slit 20. A

restriction 23 increases the speed of the additional air, up t:

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` 105;~2~3 the speed of sound when the slits 19 and 20 form the measurement cross-section. Also with this apparatus 18 the air currents entering through the slits 19 and 20 meet at high speed up to the speed of sound approximately in the centre under the throttle-valve of the carburettor. The feed of the combustion air through the slit 19 which is located in the flow of the idle running system of the carburettor has also a high effectiveness when it commences from the transition operation. With known circulating air carburettors the combustion air for idle running is fed next to a by pass hole and therefore is only effective for producing an idle running mixture. It has no longer any positive action for the improvement of the mixture formation in the transition range. If in the flow of the idle running system of such a carburettor which also delivers the fuel for the transition operation the combustion air enters through the slit 19 at higher speed up to the speed of sound and thus the draw back of such carburettors namely faulty mixture preparation in the transition and partial load range is removed and the whole fuel condensate and drops of fuel forming under the throttle-valve are finely atomized by the air entering through the slits 19 and 20.
Exhaust gas from the exhaust pipe 14 of the engine 13 can be led to the feed 4 on the apparatus 11 via the feed 15 (Figs. 6, 7). This mixing of exhaust gases with the com~ustion air brlngs about a lowering of the NO control in the exhaust gas by about 60 - 70~.
Downstream of the apparatus 11 (Fig. 7) there is disposed a heat exchanger 57 by which the fuel is atomized to a size of drop not more than 1~. The heat exchanger has heating ywl/ ~ 10 -:: . - :.

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" lOS'~Z~3 wires 58 which are connected to the electric network if necessary with the insertion of a control device, not shown, additionally the heat exchanger has an annular heating chamber 50 in which a heating gas pipe 56 leads from the exhaust pipe 14 of the engine 13. The heat exchanger is of importance for cold starting because of the higher condensate attack with a cold engine upon starting the mixture has to be additionally enriched. This induces however higher engine wear upon starting than during the warm running range as the higher condensate formation leads to thinning of the lubrication oil. In addition there results a greatly increased fuel consump-tion for short distance travelling which may amount to as much as twice the consumption during normal long distance travelling.
Furthermore the exhaust gases contain with cold starting and warm running conditions high concentrations of CO and CH which especially in short distance occupational travelling in cities leads to a very high loading of the air with poisonous gases.
The heat exchanger renders it possible for a mixture composition to be fed to the engine a few seconds after cold starting which corresponds to the operation with a working warm engine without the running quality of the engine being adversely affected.
This measure brought about upon cold starting and warm running of the engine gives a lowering of the CO and CH concentration by more than 50%.
The heat exchangers upon cold starting of the engine is heated by the feeding of current. The current feed is so designed that upon switching on the ignition the wires of the heat exchanger become hot but not red hot. At the moment when ywl/,~

105'~3 the engine is running and the current generator supplies current the current feed is increased and as that a fine atomizing but no evaporation of the fuel takes place. Another operating possibility consists in that the heat exchanger is only heated electrically when the generator supplies current. That means that only with running engine is the heat exchanger heated.
The quantity of current fed is so limited that it only extends as far as a certain partial load range of about 50 - 60 km per hour on the level for the complete atomizing of the fuel. Additional heat energy of the exhaust gases is fed via the heating chamber 50 to the heat exchanger. When the heat exchanger due to the exhaust gases has reached a predetermined`temperature the supply of current is switched off.
The quantity of exhaust gases supplied is limited so far that a complete atomizing of the fuel is achieved only up to a certain partial load range which according to the power of the vehicle is between the speeds of 50 - 80 km per hour on the level.
The heating of the fuel-air mixturç becomes increasingly less upon the output becoming increasingly greater and which at face load is hardly heated at all so that in this output range the degree of efficiency of the engine due to the heating of the fuel-air mixture is not adversely affected.
The described preparation of the fuel to the finest mist, homogeneously distributed in the combustion air causes in addition a very mild combustion which contributes additionally to the lowering of NO concentration in the exhaust gases.
By the method according to the invention accordingly a substantially complete combustion without CO concentrations in the yWl/c~ - 12 -: . : : :: ~ . ,: ' :, .

105'~ZG3 exhaust gas is obtained. The CH concentrations in the exhaust gas are reduced to a minimum and the NO formation upon combustion lowered by more than 70%. Furthermore the lowest fuel consumption possible with full utilization of the combustion air is achieved.
In order to operate the heat exchanger independently of the operating range of the combustion engine it is essential for the electric heating of the heat exchanger to be thermos-tatically controlled. Such a possibility must be present, for example, with longer valley journeys if thereby the exhaust gases used perhaps previously for the heating have cooled so far that a satisfactory preparation is no longer possible. For this case then independently of a certain minimum temperature the electric heating of the h~at exchanger is switched on, provided that at the same time also the dynamo or the generator is running.
In order to maintain temperatures as uniform as possible in the range of the heat exchanger there exists a further possibility of the invention by heating the apparatus 11, for example, by additional passageways, ribs or the like through which flows a heat supplying liquid or gaseous medium.
By this measure an approximately uniform operating condition in the preparation of the mixture the following substantial advantage is achieved namely in the range where condensate is formed and is removed by additional air a heating takes place which again contributes substantially to the better preparation and mixture formation because with the formation of condensate the temperature is reduced. This is compensated for by an additional heating.

ywl~ 13 -~: . - - .

105'~Z03 In this connection it is further an advantage for a heat storer to be present through or around which flows the liquid or g~seous medium to heat the casing of the apparatus 11 directly or indirectly.
By this measure greater temperature fluctuations within the range of the condensate preparation and of the heat exchanger will be avoided which may result from different operating conditio~s of the engine (valley travelling, mounting travelling, etc).
All these advantages are achieved with a complete apparatus which is so simple and cheap that the prime costs are soon convered by the saving of fuel.
The apparatus shown in Figs. 8 and 9 is explained more precisely in the following.
In the carburettor foot 31 is located a throttle valve 32 with a throttle valve spindle 33 and a throttle valve lever 34. A second lever 35 is fixed on a shaft 36. The accelerator lever 37 is connected to this lever 34.which accelerator lever upon accelerating pulls in the direction of the arrow. The lever 35 is connected without play, to the lever 38 of an accelerator pump by means of a lever 39. A second connection by means of a lever 40 to the throttle-valve lever 34. This lever however engages in a slot 41 so that with the opening movement of the lever 35 the lever 40 first traverses a certain path before it comes into contact with the other end of the slot 41 and only then operates the throttle valve lever 34 of the carburettor throttle-valve 32.
By means of this apparatus, upon accelerating first of ywl/ ~l, - 14 -. .

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lOS;~203 all and immediately the lever 38 ~f the accelerator pump is actuated so that without delay fuel is injected via injection tubes 42 into a mixing chamber 43 of the carburettor.
The opening of the carburettor throttle-val~e 32 is effected a little later so that there is already fuel in the mixing chamber 43 of the carburettor when the throttle-valve is opened and the air current is introduced to the carburettor.
In order that the jet of fuel which emerges from the injection tubes 42 is better presented to the air flowing through and can be taken up and distributed uniformly a baffle plate 44 is placed a little below the outlet end of the injection tubes 42. The fuel jet meets this and is atomized into a mist around the baffle plate.
Thus this fuel mist can be easily~picked up by the air and carried therein at the same speed and can be fed to the engine.
There thus results at the moment of acceleration or of starting an immediate supply of combustion air upon opening the throttle valve with a fine fuel mist well distributed in the combustion air which fuel mist is fed free of condensate and free of drops uniformly to all cylinders.
The early operation of the lever of the accelerator pump is necessary so that a fuel mist already formed on the baffle plate 44 is available when the throttle valve is opened and the air current appli~d. With simultaneous operation of the carburettor throttle-valve and the accelerator pump there is for a moment an air flow without added fuel as the heavier fuel appears later than the lighter air.
With the hitherto known richer fuel adjustment for ywl/~ - 15 -.': : . . , . ' . ' ' - .
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-.. ' , ~0s;~3 idle running and transition this short time lack of fuel does not make itself noticeable.
As now in the interest of lower CO and CH-valves the adjustments of the fuel air mixture are at about ~1 and over it was necessary to remove the corresponding hole in the acceleration by the measure according to the invention.
The apparatus described in conjunction with Fig. 8 and 9 also may be driven without the apparatus according to Flgs. 1-7.

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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. Apparatus for the preparation of liquid fuels for a carburettor of an internal combustion engine and for engines with a central fuel injection device by the feeding of combustion air downstream of a throttle valve of the carburettor and of the injection device with the aid of two slots lying opposite one another in a suction manifold of the engine, characterized in that the slots are so dimensioned that in consequence of the low pressure prevailing in the suction system of the engine the combustion air in idle running and/or in transition and partial load operation of the engine flows from the slots at essentially the speed of sound and in that the direction of flow of the combustion air supplied is essentially perpendicular to the direction of suction.

2. Apparatus according to claim 1, characterized in that the combustion air in idle running and transition operation flows from a first one of said slots and additionally the combustion air for the partial load range of the engine flows from the second slot at or substantially at the speed of sound.

3. Apparatus according to claim 2, characterized in that the combustion air fed to the second slot is controlled by a control member, for example, a throttle valve which is connected to the carburettor throttle valve for opening therewith.

4. Apparatus according to claim 3, characterized in that the control member is completely or almost completely closed in the idle running of the engine depending on the opening of the carburettor throttle valve, is partially opened in the transition operation, is fully opened in the partial load operation and is completely or substantially completely closed in the full load operation.

5. Apparatus according to claim 4, characterized in that a feed for exhaust gases is provided upstream of the control member.

6. An apparatus according to claim 5, characterized in that in the feed for exhaust gases a control member, for example a throttle valve, is arranged which in dependence on the operating range of the engine determines the quantity of exhaust gases to be supplied.

7. Apparatus according to claim 6, characterized in that the control member for exhaust gas influences the supply of exhaust gas to the second slot so that there is an excess of air for the fuel-air mixture which enters the suction manifold of the engine.

8. Apparatus according to claim 1 which is used as an additional device for carburettors which feed combustion air in idle running operation, for circulating air carburettors, characterized in that the feed for combustion air is closed in the idle running range and commences to open only during the transition range of the engine.

9. Apparatus according to claim 8, characterized in that the combustion air is fed to said slots via an annular channel leading into a channel for the feeding of the combustion air.

10. Apparatus according to claim 9, characterized in that said channel is directed to the centre of said annular channel and said slots lie in the direction of said channel.

11. Apparatus according to claim 10, characterized in that one of the slots is positioned next to the channel and is located in the flow of the idle running system of the carburettor.

12. Apparatus according to claims 1 and 8 characterized in that at least one of said slots is located downstream of the idle running system of the carburettor.

13. Apparatus according to claim 1 characterized in that the apparatus is designed as a part of the carburettor.

14. Apparatus according to claim 1 characterized in that combustion air with fuel distributed uniformly therein, before entry into the engine passes through a heat exchanger.

15. Apparatus according to claim 14, characterized in that means are provided so that upon switching on the engine ignition current passes through heating wires of the heat exchanger, the heat being insufficient to heat the wires to red heat.

16. Apparatus according to claim 15, characterized in that means are provided which upon starting the engine feed a higher current to the heating wires than the current employed after starting.

17. Apparatus according to claim 14, characterized in that means are provided which control the supply of heating energy such that the fuel is not evaporated but is only atomized.

18. Apparatus according to claim 17, characterized in that a circuit of heating wires includes a switch device which switches the heating wires on only when a dynamo of the engine is running.