US3901204A - System for supplying fuel to internal combustion engines - Google Patents

Abstract

A system for supplying fuel to internal combustion engines by medium pressure injection including a pressurized fuel tank, a specially designed fuel pump and an electromagnetic fuel injector. The pump is a diaphragm-type pump of smaller diaphragm surface and increased spring pressure compared to conventional diaphragm-type fuel pumps. It is designed to provide an output fuel pressure at substantially that level necessary for feeding the injector thus obviating the necessity for a pressure regulator.

Description

United States Patent Jaulmes 1 1 Aug. 26, 1975 [5 SYSTEM FOR SUPPLYING FUEL TO 3,363,614 1/1968 Fisher 123/139 R INTERNAL COMBUSTION ENGINES 3,724,435 4/1973 Bier 123/139 AV [75] Inventor: Eric Jaulmes, Paris, France FOREIGN PATENTS OR APPLICATIONS Assigneez Ateliers de la Motobecane, Pantin, 608,211 l/l935 France 123/139 France Primary ExaminerWendell E. Burns [22] Filed: Dec. 5, 1973 Assistant Examiner.lames W. Cranson, Jr. pp NO: 421,870 Attorney, Agent, or firm-Browdy and Nelmark [57] ABSTRACT Foreign Application Priority Data A system for supplying fuel to internal combustion en- Dec. 27, 1972 France 72.46291 gines by medium pressure injection including a pressurized fuel tank, a specially designed fuel pump and [52] US. Cl... 123/139 A; 123/32 AE; 123/139 AW an electromagnetic fuel injector. The pump is a dia- [51] Int. CL" F02M 39/00 phragm-type pump of smaller diaphragm surface and [58] Field of Search 123/139 AH, 139 AV, increased spring pressure compared to conventional 139 AW, 123/32 EA, 32 AE diaphragm-type fuel pumps. It is designed to provide v an output fuel pressure at substantially that level nec- [56] References Cited essary for feeding the injector thus obviating the ne- UNITED STATES PATENTS cessity for a pressure regulator.

2,062,644 12/1936 Ensign 123/139 AV 5 Claims, 7 Drawing Figures FUEL TANK F 7 z AUXILIARY 5 l PUMP L ,5 INJECTOR I i l Iv l 1 PATENTED BZ 3,901,204,

sum 2 UP 3 T A N K PUMP REGULATION CONTROL :9 J 1 [LI z 5 5 Q g i *2 E s d E a 25 2 I I 0 5 222g M Z Cm 2 E '5 (I 0 1' THE TANK Rflt CANNOT as J PRESSURIZED l I AP Venl'um @4 H n. g a: x E 8 2 z n: 8 f ,t w a g Q a z E g E ZKg/cm E a 6 5 THE TANK CANNOT BE PRESSURIZED l Mp IN NOZZLE 2 PRESSURE IN TANK 1 I jog/cm 5 J E E 1 l LL 3 I l I Rflhn. PRESSURIZED l TANK I I g 5 u AP Venturl g E 2 5 m I d m 2 IL 3 75 5 3 6 i E I 2 z d I s fEgG E 5 5 1 d d a g 5 I: ZKg/Cm f =2 I g E 1 Rfltm. PRESSURIZED l TANK 1 {AP IN NOZZLE PATENTED AUBZB I975 saw 3 05 3 '1 PUMP FUEL TANK AUXIUARY INJECTOR SYSTEM FOR SUPPLYING FUEL TO INTERNAL COMBUSTION ENGINES FIELD OF THE INVENTION the high-pressure volumetric pump (feed) a discharge valve plus regulator (regulation) a controlled injector (control of flow).

3. The fuel line with a carburetor and pressurized present invention relates to a system for Supply 5 tank where the successive functions are accomplished ing fuel to internal combustion engine by means of a by: fuel injector, and more particularly to an improved a Pressunzed tank (feed) I pump for supply fuel from a storage tank to the injeca Fonstam'level chamber (regulahon) tor a et (control of flow).

. in all of these systems, presented for the sake of ex- BACKGROUND OF THE INVENTION amples, there is a physical dissociation between the first two functions due to the disproportion between lfhowh y m f g control the fuel feed the feed pressure and the required regulated pressure. f anlmemal combunshoh engme Perform three func- In conventional fuel lines supplying a carburetor of 3on5: i pp yv ff h and Control of type 1 hereinabove, the properties demanded of the The Supply yfunctloh can be accomplished either y pump mainly include ensuring flow at sufficient presmeahs of 3 P p usually of the dlaphragm yp p sure for the fuel to enter a constant-level chamber h at a rathef 10W pressulje f the Order P 200 g/cmzi which is generally located slightly above the pump, and y a Pressurized tank z creates a 'P to limit the feed pressure when the jet is delivering a sure level to 30 y a Volumemc P p P- small volume so as not to disturb the level in the float eratmg at a pressure level of the order of several kiloh b m ln known fuel lines of type 2 hereinabove, the pump The regulation function can be accomplished eipressure ismuch greater (possibly at least three times ther by means of a constant level (float) chamber or by as great) than the average pressure required to feed the means of a pressure regulator, possibly associated with injectors, and two pressure-limiting devices with rea discharge valve. turns to the tank are necessary.

The control of i flow function can be accompl shed. SUMMARY OF THE INVENTION by a fuel line which allows an amount to pass which is a function of several parameters: pressure, cross- The Principal Object of the Present Invention 15 to section and opening time. Preferably, one of these pa- Provide a Simplified fuel line which pp gasoline t0 r r i m bn d d h others remain t t an engine whose carburetion is controlled by an orifice Thus, there is always a fuel supply system consisting Such that v v of a pump, a pressure-regulating element which ensures The profile fi (needle'prolectfon h Seat) regulated f l pressure, d a control element which 2. The cross-section of the passageway is variable and serves to measure the amount of fuel fed into the cylin- ,comrolled (Opemng and the crosssectlon Versus d t x I travel of the needle relationship).

F the Sake f an example, we can mention the 3. The downstream pressure is known (depression in lowing types of systems: the make nozzle) I v 4O 4. The-upstream pressure 18 known and regulated to The com/6mm"?! fuel leading to the uwaconstant value, with the pressure being created by a tor where the successive functions are carried Out by; diaphragm pump connected mechanically to the cra ka diaphragm pump (feed) 7 l shaft of the engine. its function is simultaneously to ena constant-level chamber (regulation) sure feed to the controlling element (electromagnetic a jet (control of flow) 7 injector) and to ensure a constant pressure in the fuel 2. The fuel injection system with electromagnetic line. control, where the successivefunc tions are carried out The following comparative table summarizes the by: I j above.

. Conven. auto Conven. Conv. motorcy- Injection in carburetor Injection cle carburetor accord. w/in- FIG. 3 FIG. 4 vention.FlG. 6

Pressurized Pressurized tank tank Feed Diaphragm Special Dia- Pump phrugm pump Volumetric Pump Constant Constant level level Regulation chamber chamber Regulator Upstream Pressure Constant Constant Constant Constant Down- Variable Variable Control stream depress. in depress. in of Pressuthroat of throat of flow re. Venturi Venturi C ross- Variable opensection ing crosssection Lifting ti- Lifting time Time me of adjus of adjusta table needle ble needle Hence, the invention consists in achieving a novel combination of a pressurized tank with a special diaphragm pump, designed, on the one hand, to function as a feed from said tank, and, on the other hand, for the purpose of supplying an injector at a constant pressure, as is always necessary, but without using a regulating element. The injector is advantageously in conformity with the following patent applications of the assignee:

French Pat. No. 2,205,111 for an electronic control and monitoring system for the feed of fuel to two-cycle fuel injection engines; and

French Pat. No. 2,206,795 for improvements made to fuel injectors for engines; both of which are hereby incorporated by reference.

Such a fuel supply line is characterized by a single average pressure level between the feed element and the control element, without any additional element for regulating the pressure.

A novel feature of the fuel line thus conceived consists in the different operating conditions of the principal element, i.e., the pump.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be discussed in greater detail with reference to the attached sketches:

FIG. 1 is an explanatory graph of fuel pressure as a function of flow for the special diaphragm pump in accordance with the present invention in comparison with a conventional diaphragm pump.

FIG. 2 is an explanatory graph showing the available flow from the pump in accordance with the present invention as a function of the number of strokes per minute of the engine for a given pressure, and the maximum demand of the engine.

FIG. 3 is a diagram indicating the pressures in the various portions of a conventional automobile carburetor fuel supply system.

FIG. 4 is a diagram indicating the pressures in the various portions of a conventional injection fuel supply system.

FIG. 5 is a diagram indicating the pressures in the various portions of a conventional carburetor with pressurized tank fuel supply system.

FIG. 6 is a diagram indicating the pressures in the various portions of a fuel supply system in accordance with the present invention; and

FIG. 7 represents as an example, in axial section, of a diaphragm feed pump in accordance with the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS As is clearly shown by the graph in FIG. 1, the characteristic curve (at constant velocity) of the pressure as a function of the flow shows a favored zone (c) where the pump pressure remains constant while the flow remains below a certain level D.

It is this property which is applied to the supply of the injectors by means of the present invention.

This zone narrows when the velocity drops but, fortunately, the needs of the engine follow the same law and consequently it is possible to adapt the characteristic curve of the pump to the demand of the engine, as indicated by the graph in FIG. 2, where the available flow from the pump for various constant output pressures, on the one hand, and the maximum demand of the engine on the other hand are represented as a function of the number of strokes per minute. There are four elements of a diaphragm-type fuel pump which must be adjusted for each application in order to have the optimum compromise:

a. the force of the spring, which acts on the pressure; b. the effective area of the diaphragm, which affects the flow and the pressure; c. the travel of the diaphragm, which also affects the flow; and

d. the mechanical linkage between the crankshaft and the pump, which affects the relative positions of the curves.

The pump designed according to the present invention, therefore, consists, on the one hand, of a diaphragm with a reduced area, in an average ratio of 3:1 (for example) in comparison to a conventional pump, and on the other hand a return spring for this diaphragm which is essentially more rigid than the conventional spring and which exercises a force which is on the average twice as great.

In the pump according to the invention, the effective area of the diaphragm is at most 400 square millimeters and the force exercised by the return spring is at least 3 kg. As an example, a pump designed for a 350 cubic centimeter motorcycle engine has an effective diaphragm area of 300 square millimeters and the force exercised by the spring amounts to 6 kg. The pump output pressure is 2 kg/cm and the flow is 12 liters/hour for 2,500 strokes per minute.

For the sake of comparison, a conventional pump designed for a l,000l,500 cubic centimeter automobile engine has an effective diaphragm area of about 1,200 square millimeters and the spring exercises a force of 1.5 kg. The pump output pressure is grams/cm and the flow is 25 liters/hour at 1,000 strokes per minute. For the sake of an example, in FIG. 1 we have shown for 2,000 strokes/minute the characteristic curve (a) for the flow versus pressure for such a pump plotted with a dot-dash curve, and the characteristic curve (b) of a classic pump plotted with a dashed line.

On the other hand, since the diaphragm has a smaller area, but the stroke is comparable to that of conventional diaphragm pumps, the volume displaced with each cycle is low, although it is sufficient to satisfy the demand of the engine, and the gear ratio between the crankshaft and the pump is therefore selected appropriately. This low volume, however, still does not allow the pump to assume in a satisfactory fashion (especially during starting), the function of aspiration from a tank located below the level of the pump and the pump is therefore combined with a tank located above the pump level.

Such a feed system at medium pressure for an electromagnetic injector has unquestionable advantages as follows:

1. Simplicity of design of a diaphragm pump relative to a fuel pump of the paddle type, with rollers or pistons, where tightness is obtained by means of accurate machining which is costly.

2. Regulation by the pump itself, doing away with any discharge valve associated with a return line and intended to reduce the pressure level to a lower level, called the regulated level.

3. Direct and mechanical connection to the crankshaft which makes it possible to have independence relative to a battery, which may not exist in the vehicle, with the application of energy to this linkage correspending exactly to the pumping needs, and the elimination of a safety element which is normally required in the event of electrical feed in order to avoid useless pumping at very low speeds.

Means will preferably be included to eliminate gasoline vapor blocks in the system in which the reservoir is located above the level of the pump. The lines will be provided with conventional means; the pump advantageously situated at a level which is very slightly above that of the injectors and a very low-volume bypass (very small diameter tube) which will connect the output and input.

This pump has associated with it a flexible hose which is used to eliminate the slight fluctuations in pressure in the line relative to the average pressure level, playing the role of a capacitor, since these slight fluctuations can occur when the injectors are working and when the pump diaphragm spring is put under ten- This resilient hose connected to injector 26, is represented by in P16. 7, which shows a simple example of a modified diaphragm pump according to the invention.

A cam 11 cut in shaft 12 driven by the engine crankshaft through the necessary reduction gears acts on a push rod 13 which in turn moves a rocker arm 14. The latter deforms diaphragm 15 which, according to the invention, has a useful diameter which is significantly smaller than that of conventional diaphragms, its area being (for example) about three times smaller. The return spring 16 of this diaphragm is itself reinforced so as to exert a force which is about twice that of a conventional pump.

The intake nozzle is represented by 17 and the outlet nozzle is represented by 18. Valves 19 and 20 are associated respectively with each of these two nozzles.

Nothing will be changed in the invention if the function of the pressurized tank 22 is ensured by an auxiliary pump 24 (shown in broken lines because it is optional) which will furnish at the input of the special pump provided, a pressure level which is equivalent to that of this tank.

It will be obvious to those skilled in the art that various changes may be made without departing from the scope of the invention and the invention is not to be considered limited to what is shown in the drawings and described in the specification.

What is claimed is:

l. A system for supplying fuel to internal combustion engines by medium pressure injection, comprising:

a fuel tank;

a fuel injector;

a diaphragm-type fuel pump means for supplying fuel from said tank to said injector, said fuel pump means having an inlet, an outlet, a diaphragm and a spring return means;

linkage means for driving said fuel pump at a speed proportional to that of the engine;

means for causing fuel from said fuel tank to enter the intake of said fuel pump means at a predetermined pressure; and

line means for directly connecting the output of said fuel pump means to said injector without interposition of any pressure regulating means;

wherein the effective diaphragm area in said fuel pump means is at most 400 square millimeters and the force exercised by said spring return means is at least 3 kg,

whereby the fuel pump means output pressure will remain substantially constant as the fuel pump means output flow varies from a substantially nil value up to a predetermined maximum value.

2. A system according to claim 1, wherein the output pressure of said fuel pump means is about 2 kg/cm 3. A system according to claim 1, wherein said line means connecting said fuel pump means to said injector is resilient.

4. A system according to claim 1, wherein said means for causing fuel to enter the intake of said fuel pump means at a predetermined pressure comprises means for locating said tank above the level of said pump.

5. A system according to claim 1, wherein said means for causing fuel to enter the intake of said fuel pump means at a predetermined pressure comprises an auxiliary pump.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3,901,204

DATED August 26 1975 INVENTOR(S) Eric Jaulmes It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 6, line 38 (claim 4, line 4) "said means" should read -said fuel pump means-- Signed and Sealed this sixth D f January 1976 [SEAL] A ttest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner of Patents and Trademarks

Claims (5)

1. A system for supplying fuel to internal combustion engines by medium pressure injection, comprising: a fuel tank; a fuel injector; a diaphragm-type fuel pump means for supplying fuel from said tank to said injector, said fuel pump means having an inlet, an outlet, a diaphragm and a spring return means; linkage means for driving said fuel pump at a speed proportional to that of the engine; means for causing fuel from said fuel tank to enter the intake of said fuel pump means at a predetermined pressure; and line means for directly connecting the output of said fuel pump means to said injector without interposition of any pressure regulating means; wherein the effective diaphragm area in said fuel pump means is at most 400 square millimeters and the force exercised by said spring return means is at least 3 kg, whereby the fuel pump means output pressure will remain substantially constant as the fuel pump means output flow vaRies from a substantially nil value up to a predetermined maximum value.

2. A system according to claim 1, wherein the output pressure of said fuel pump means is about 2 kg/cm2.

3. A system according to claim 1, wherein said line means connecting said fuel pump means to said injector is resilient.

4. A system according to claim 1, wherein said means for causing fuel to enter the intake of said fuel pump means at a predetermined pressure comprises means for locating said tank above the level of said pump.

5. A system according to claim 1, wherein said means for causing fuel to enter the intake of said fuel pump means at a predetermined pressure comprises an auxiliary pump.

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