US 2649290 A
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G. GRIFFON Aug. 18, 1953 CARBURETOR Original Filed Feb. 15, 1947 ess. am a/azr 5 NEYS GfqsTo/v GRM-FON Patented Aug. 18, 1,953
CARBURETOR Gaston Griffon, Neuilly-sur-Seine, France, as-
signor to Societe Solex, a society of France `Continuation of abandoned application Serial No.
728,737, February 15, 1947. February 14, 1951, Serial No.
This application 210,824. In
France February 15, 1946 (Cl. Z61-34) 4 Claims.
The invention relates to carburetors for internal combustion engines and more especially engines having a small number of cylinders.
Automatic carburetors, as now in use, permit of obtaining, when the engine is running on full load, a mixture the richness of which is substantially constant for considerable flow rate variations, provided that these carburetors are subjected to a continuous suction eiiect, as this is the case for tests performed with a centrifugal fan for instance, or when the carburetor is used in connection with an engine including more than four cylinders.
On the contrary, when these same carburetors are used with engines running at high speeds and having a small number of cylinders (from one to four) or on engines having six or four cylinders fed through a duplex carburetor, the richness of the air-fuel mixture is greater at low and mean speeds than at high speeds of the engine.
The object of my invention is to obviate this drawback. For this purpose, I combine a carburetor such as above mentioned with a pick-up pump controlling iuel delivery valve means such that the richness of the mixture delivered when the engine is running with the throttle fully open remains substantially constant at all speeds, despite the small number of cylinders of the engine.
Preferred embodiments of my invention will be hereinafter described With reference to the accompanying drawings, given merely by way of example and in which: Y
Fig. l shows curves illustrating the object of my invention;Y
Fig. 2 shows, in axial section, a carburetor system made according to an embodiment of my invention; Y
Fig. 3 shows, in axial section, a modification of a part of this carburetor system;
Fig. li shows, in axial section, a modication of the rst embodiment. Y Y
Fig. l shows a series of curves intended to explain the operation oi the device according to my invention.
rEhe upper part of Fig. 1 shows several curves corresponding to the richness of the mixture supplied by a conventional automatic carburetor under full load running conditions (with the throttle fully open) and at different speeds of the engine, for instance from 1000 to 4000 revolutions per minute, whereas the lower part of Fig. 1 shows the corresponding specic consumption curves.
Curve A was obtained by fitting a good carburetor of a conventional type on the induction pipe of a centrifugal fan. It shows that the richness of the mixture for air flow rates corresponding to those obtained in an engine for speeds ranging from 1000 to 4000 revolutions per minute is substantially constant for all the points of curve A.
Curve B-B was obtained with the same carburetor and the same adjustment but used in connection with a four cylinder engine. It will be seen that the richness oi the mixture is generally too high, being maximum for speeds ranging from 1000 to i500 revolutions per minute, decreasing as the engine speed increases up to 3200 revolutions per minute approximately (point B3), and then remaining substantially constant as the engine speed increases up to the highest values. Curve C-C indicates the specific consumptions corresponding to curve B-B.
Curve B1-B3-B shows the results obtained when the system according to my invention is used and curve C1-C gives the specific consumptions corresponding to curve B1-B3-B.
Curve B1-B3-B2 shows what can be obtained with a modication of my invention which maires it possible first to change curve B-B3 into curve Bl-Ba, then, for speeds ranging up from 3500 revolutions per minute, to enrich the mixture in the manner indicated for instance by curve B3-B2- The corresponding curve of specific consumptions is shown at C1-C2.
To obtain such results, according to my invention, I combine an automatic carburetor of a conventional type with a pick-up pump in a manner which will be hereinafter described. The essential parts of the conventional carburetor are visible on Fig. 2, to wit body I choke or venturi 2, calibrated jet 3 provided in the conduit ffl which connects the constant level chamber 2i' with nozzle device 5. The latter includes at its upper part a calibrated oriiice t for the iniiow of emulsion air. A throttle valve l is provided in the induction pipe 8 of the engine.
With such a carburetor used alone5 the richness curve under full load running conditions and for speeds of the engine ranging from 1000 to i050 revolutions per minute would be similar to curve B--Bfi-B of Fig, l, and the corresponding speciflc consumption curve would be similar to C-C.
In order to improve this operation, I maire use of a pick-up pump to control means for varying the section of a calibrated oriiice which serves to deliver fuel, this calibrated oriice being either the main jet or an auxiliary jet.
In the example of Fig. 2, I make use of an auxiliary jet.
This auxiliary jet is constituted by a calibrated oriiice 4'! provided in a conduit d@ which opens into choke 2 through a calibrated orice 45. Conduit l186 starts from the suction pump, which is constituted by a casing divided into two iiuidtight chambers or compartments it and t9 separated by a diaphragm 5t.
Compartment 43, which communicates with conduit 46, is fed with fuel through a connection 53 branching oi from the conduit t which connects the constant level chamber 2l with the main jet 3. A check Valve 58 in this conduit 53 prevents back ow of fuel therethrough. Coinpartment t9 communicates, through a tube with a chamber 55 adjacent to the induction pipe 8 of the carburetor and which communicates with the inside thereof both on the upstream side of throttle valve 'through an oriiice 5d, and on the downstream side thereof through an orifice 51.
A check valve 59 in the pump delivery conduit i6 prevents bach flow of air into the during the suction stroke of said pump.
Diaphragm 5d carries a central needle valve 5i capable of more or less obturating auxiliary jet fil. Diaphragm t@ is urged, on the face thereof opposed to that which car 1ics needle val"e by a spring 552 bearing upon the end wall of compartment d@ and which tends to apply needle valve 5i on its seat constituted by the edge of orifice 4l.
The carburetor is adjusted through the usual means, that is to say by a suitable choice of jet and emulsion air orifice t, to obtain, when the engine is running with the throttle iiaiiy open and at a speed of about 1500 revolutio s per m the desired value of the fuel in (point Bi of the curve of Fig. l).
The operation is as follows.
openings of throttie l, the suction. is very iiign in the induction conduit E of the engine and, consequently, opposite orifice El', whereas it is very low opposite orifice 5t. Therefore, in chiii and tube there is a vacuum between the suctions on the upstream and sownstream sides or throttle valve l, w h vs transmitted to compartment il@ of the piek-up pump.
The sections of orices 5S and il are determined in such manner that, when the engine is idling or throttle valve l little open-e the effort exerted upon diaphragm created in compartment de overcomes the action of spring 52 and therefore causes diaphragm ilfi to move toward the right of Fig. 7. This displacement causes, on the one hand, fuel to fiow into compartment and, on the other hand, needle valve 5i to move away from jet and therefore to clear the passage through this jet.
Now if the engine is made to pick up, that is to say if, starting from a low speed of said engine, throttle l' is suddenly opened, the high vacuum which existed opposite orifice 5l drops to a low value. The vacuum accordingly drops in coinpartinent fifi. Diaphragm liti moves toward the left and causes a certain amount of fuel to be delivered through conduit fit.
At the end of the pick-up pump delivery stroke, needle valve 5i rests upon its seat, preventing the fiow of fuel through jet fil. This position of the needle valve corresponds to low speed running of the engine, with throttle 'i fully open. rlhese are the conditions for which, as above stated, the carburetor has been adjusted to have a fuel richness represented by the point B1 oi the curves of Fig. l. Ii the carburetor were used alone, i. e. without the pick-up pump and the means it conby the partial vacuum trols, the richness of the mixture would tend to decrease for increasing values of the engine speed, as shown in the portion B-Ba of the curve B-Ba-B of Fig. 1.
But, as the engine speed increases, the suction increases opposite orifices tit and 5? so that the vacuum in compartment i9 reaches a value sufficient for again causing diaphragm 5e to move to- Vward the right against the action of spring whereby needle valve 5i again ciears the passage through auxiliary jet fil, the rate of iiow th sugli said auxiliary jet increasing according to a predetermined law as the speed or" the engine increases, to reach its maximum either for a speed corresponding to about 3200 revolutions per ii inute if it is desired to keep a substantially constant richness, as in the case of curve Bi-Bs-B, or for a iglier speed if it is desired to obtain a richer mixture at the highest speeds of the engine, an arrangement which gives a richness curve analogous to Bi-B3-B2 of Fig. l for instance.
The strength of spring 52 determines the time at which diaphragm 5t starts moving toward 'he right of fig` 2 and its i'ie; ty determines h range of displacement of needle valve El. profile of said valve '5i iet es the richness of the mixture for every speed the engine inside the range for which the correcting device is brought into play.
It may be advantageous, in some cases, in addition to the eifects above described, to reduce the richness of the mixture for lower power running. This result can be obtained by placing orifice 5l nearer to the throttle, at ci! for instance, whereby said orifice passes from the upstream to the downstream side for a certain degree of opening of throttle l.
I may also, as shown by Fig. 3, move, by means of diaphragm 50, a needle valve 5i provided with a check valve 5 I located on the side of calibrated orifice 4'! opposed to said needle valve 5! so that said check valve can close said oriiice at the end of movement of diaphragm 5t toward the right.
Chamber 49 is then placed in communication either with orices 56 and 5l as in Fig. 2, or with only orifice 5l that is located on the downstream side of throttle 'I when it is desired to obtain a quick closing of orifice il and therefore a reduction of the richness of the mixture for powers close to the maximum power.
The working is the same as that of Fig. 2 concerning full throttle running, which means that under full load running conditions, at low speeds of the engine, diaphragm 5! is pushed toward the left by spring 52 and, consequently, needle valve 5l closes passage 4l. For higher speeds, needle valve 5l gradually clears passage i? whereas check valve 5l' moves closer and closer thereto, but without stopping it. For partly closed throttle running, the suction in the pipes reaches values higher than those obtained at high speed and under full load running conditions. Diaphragm 50 therefore keeps moving toward the right and passage 41 gets closed by check valve 5|. This closing may be either gradual or sudden according to the shape given to check valve 5 l In Fig. 4 I have shown a modification of the device of Fig. 2 according to which a needle valve 6I controls the ow section through the single main jet 3. This needle valve is controlled through pneumatic means as above described, adapted to work also as pick-up pump. It sufces, for this purpose, to provide a check valve S2 in conduit 4, which leads from chamber 21 to the main jet. The injection of fuel during picking-up periods then takes place directly into nozzle device 5.
The present application is a continuation of my application Ser. No. 728,737, filed February 15, 1947, now abandoned.
In a general manner, while I have, in the above description, disclosed What I deem to be practical and eflicient embodiments of my invention, it should be well understood that I do not wish to be limited thereto as there might be changes made in the arrangement, disposition and form of the parts without departing from the principle of the present invention as comprehended Within the scope of the accompanying claims.
What I claim is:
1. For use in connection with an internal combustion engine, the combination of a carburetor including an induction pipe and a throttle in said pipe, an automatic pick-up pump operative in response to variations of the suction in said pipe on both sides of said throttle, this pump including a part movable in response to variations of this suction from one position corresponding to the minimum value of this suction to another position corresponding to the maximum value of said suction, and a fuel discharge conduit leading from said pump to said pipe, and a metering valve operatively connected with said movable part and located in said fuel discharge conduit, said valve being so shaped and connected with said movable part as to increase gradually the flow section through said conduit in response to displacement of said movable part from said rst mentioned position thereof to said second one.
2. For use in connection with internal combustion engine, the combination of a carburetor including an induction pipe, a throttle in said pipe and a fuel conduit opening into said pipe, an automatic pick-up pump operative in response to variations of the suction in said pipe on both sides of said throttle, this pump including a fuel chamber having a Wall movable in response to variations of this suction from one position corresponding to a minimum value 4of this suction to another position corresponding to a maximum value of said suction, a supplementary fuel discharge conduit leading to said induction pipe, the outlet of said pump opening into said supplementary fuel conduit, and a metering valve operatively connected with said movable wall and located in said supplementary fuel discharge conduit, said valve being so shaped and connected with said movable part as to increase gradually the flow section through said supplementary conduit in response to displacement of said movable part from said first mentioned position thereof to said second one.
3. A combination according to claim 2 further including a check valve carried by said valve means to stop the flow of said supplementary conduit when said movable wall is at the end of its displacement produced by increasing suction on the downstream side of said throttle.
4. For use in connection with an internal combustion engine, the combination of a carburetor including an induction pipe, a throttle in said pipe and .a single fuel conduit opening into said pipe, an automatic pick-up pump operative in response to variations of the suction in said pipe on both sides of said throttle, the outlet of said pump opening into said conduit, this pump including a fuel chamber having a wall movable in response to variations of this suction from one position corresponding to a minimum value of this suction to another position corresponding to a maximum value of said suction, and a metering valve operatively connected with said movable wall and located in said outlet, said valve being so shaped and connected With said movable part as to increase gradually the ow section through said outlet in response to displacement of said movable part from said first mentioned position thereof to said second one.
References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,389,922 Mennesson Nov. 27, 1945 2,392,055 Mennesson Jan. 1, 1946 2,563,096 Bicknell Aug. 7, 1951 2,572,169 Mallory Oct. 23, 1951