US2415687A - Fuel injection system for internal-combustion engines - Google Patents

Description

Y Fb. 11, 1947. A. F. GILL 2,415,687

FUEL INJECTION SYSTEM FOR INTERNAL-COMBUSTION ENGINES Filed Ila} 6. 1940 /NVENTL7R ALA /TE/LL Patented Feb. 11,- 1947 FUEL INJECTION SYSTEIH FOB INTERNAL- COMBUSTION ENGINES Alan F. cm, Ottawa, Ontario, Canada Application May 6, 1940, Serial No. 333,675

This invention relates to internal combustion engines and particularly to the control of the power delivered by the engine from moment to moment by the control of the quantity of fuel supplied to it independently of the speed at which the engine is operated during such intervals.

Energy is derived from internal combustion engines by the combustion in a confined space of a mixture of fuel and oxygen, the latter generally being air and it will here be referred to as such. The fuel is almost invariably carbon or a carbon compound which may be in liquid form as for example oil or gasoline or in gaseous form, and it has been suggested that fuel be used in solid form as for example pulverized coal.

As is well known the ratio of fuel to air in the mixture in the combustion chamber is of prime importance in the operation of an internal combustion engine. If the mixture is too rich or too lean the combustion which can take place will not be sufllcient to drive the engine. Furthermore, although the engine will operate on a mix ture between these limits, there is an optimum mixture for a given engine under given conditions of load and speed.

In known types of engines the air supply arrangements are such that the engine can be regarded as an air pump. For instance, in most Diesel engines the air intake ports may be said to open directly to the atmosphere while in carburettor type engines they open indirectly to the atmosphere at its natural or at an induced pressure through a carburettor, and at any given setting of the choke and throttle the volume of air drawn in is the same for each engine stroke at a given speed. Consequently, the volume supplied in any given interval of time is a function of the engine speed. This is also true of the amount of fuel supplied. The fuel supply arrangements by their dimensions impose an upper limit on the amount of fuel capable of being delivered and in some cases provision is made to prevent the fuel supply falling below a minimum when the engine .is in operation.

In injection type engines'the supply of fuel to the combustion chamber is determined by a permanent or adjustable setting of the quantity of fuel to be admitted to the combustion chamber for each cycle. In carburettor type engines fuel is drawn by suction from a jet or jets and in normal operation of the engine under load the suction rises with an increase of the engine speed and decreases as it falls. In both types, therefore, the amount of fuel supplied in any given interval of time is a function of the engine speed.

Since the speed of the engine determines both the amount of air and the amount of fuel, any modification of the fuel-air ratio must be accomplished by manual adjustment, the resulting ratio being an approximation only to the desired optimum at any given time, with the possibility of it departing considerably from the optimum under varying conditions of load or speed.

It is an object of this invention to obtain in a convenient and simple way a close approximation to the optimum mixture for the speed and load conditions, as these vary from moment to moment without the necessity of momentary manual adjustment of the fuel-air ratio even in engines in which such ratio is capable of such adjustment.

The present invention consists in the provision in an internal combustion engine as the primary mode of adjusting the speed of the engine to the energy output required to be obtained from it,

of a fuel flow controlling means in the fuel line between the 'fuel reservoir and the point at which the .combustible fuel-air mixture is formed whereby the amount of fuel supplied to the engine in a given interval of time is regulated independently of the engine speed.

An engine according to the invention having a fuel flow controlling means operating independently of the speed of the engine tends automatically to adjust the fuel air ratio tothat required by the load conditions. For example, if the load is reduced during operation the engine speed increases with consequent increase in the amount of air which it draws in. However, because the fuel flow controlling means is independent of the speed of the engine the amount of fuel supplied a is unaffected by the changed speed. The fuel air ratio is therefore decreased with a consequent decreased power output which tends to limit the speed. Similarly if the load is increased, the

engine slows-down and the amount of air drawn in decreases correspondingly. However, since the fuel supply remains constant, the decreased air supply produces an increased fuel air ratio and unless the engine is overloaded this increased fuel air ratio gives an increased power output, and when this increased power output balances the increased load the engine continues to operate at the decreased speed which gives this increased power output. It is therefore evident that an engine according to the invention adjusts itself automatically to variations in the quantity of air supplied, whether such variations are caused by changes in the engine load or by change in the density of the atmospheric air.

The fuel controlling means is preferably a pump of suitable size and construction driven by a fluid motor, or an electric motor or other suitable means, the power for which may be derived indirectly from the engine but the speed of which is unaffected by the speed of the latter. In a simple form applicable to carburettor-type engines, it can be a controlled gravity feed so designed as to be independent of engine suction.

The invention will be further illustrated by reference to the accompanying drawing which shows the invention applied to an engine of the carburettor equipped type and of the injection type operable on liquid fuel.

Figure 1 shows r carburretor type internal combustion engine according to the invention, only those parts of the engine being shown which are necessary to illustrate the invention.

Figure 2 shows a section of the pump of Figure 1 taken at right angles to the latter figure. Referring to Figure 1 there is there shown a carburettor type engine according to the invention having an air intake pipe I and a fuel jet 2 arranged therein so that the fuel discharges into the air stream to form a combustible mixture of fuel and air.

Fuel is supplied to the jet through a tube 3 by a measuring pump 4 to which fuel is in turn supplied from the fuel reservoir by the tube 3'. The measuring pump 4 is driven by an electric motor 5 which can derive its power from a battery or any'suitable source and whose speed is controlled by a rheostat or other known means according to the type of motor used. The motor 5 derives the pump through a shaft 6 having a.

cam I keyed to one end.

Referring to both Figures 1 and 2 the fuel measuring pump 4 consists of a cylinder 8 and a piston 9 operating therein. n the down stroke the piston, by the suction which it produces, draws the outlet valve l9 onto its valve seat II and lifts the inlet valve l2 from its seat 13, drawing fuel through the tube 3' into the cylinder 9.

The piston 9 has a yoke l4 at its lower end which journals a shaft l carrying a freely mounted roller IS. The latter bears against the cam I under the action of a spring I! which surrounds the outside of the cylinder and is held in place between the shoulder l8 on the pump head and the upper surface of the yoke l4.

In operation, the motor 5 rotates the cam 1 whose action on the roller l6 causes the piston to rise, the valve In to open and the valve l2 to close. On further rotation ofthe cam the piston is lowered under the action of the spring l1, so that the valve l2 opens the valve '19 closes and fuel is drawn into the cylinder 8.

In the embodiment of the invention illustrated.

in Figure 1, the amount of fuel supplied to the engine can be varied independently of the speed of the engine. Consequently, by varying the speed of the motor I, more or less fuel can be supplied as required and the ratio of fuel to air in the combustible mixture formed in the intake pipe I will vary inversely as the speed at which the engine operates.

Since the pump 4 is controlled independently of the speed of the engine it will deliver at any desired setting, a constant quantity of fuel over a given interval of time and the amount of fuel which it delivers will be unaffected by variations in engine speed. Consequently, when the engine,

operating at a given pump setting and under a given load, has an additional load applied which slows down the engine, the rate of fuel supply will be unaffected. On the other hand, the amount of air drawn in by the engine over the same time interval will decrease due to the decreased engine speed so that the ratio of fuel to .air in the combustible mixture is increased and this richer mixture results in increased power per engine cycle. It should be noted that this increased fuel air ratio results automatically from the decreased engine speed because the fuel supply is' independent of the engine speed.

A butterfly valve shown at 66 in Figure 1 is provided in the air intake so that air can be throttled and the compression pressure reduced in order to ensure satisfactory low speed operation and the. maintenance of a combustible mixture at such speeds.

What I claim is: 4 '1. An internal combustion engine having a combustion space and comprising means for supplying fuel to said combustion space at a rate independent of the engine speed, means for supplying air to said space at a rate dependent upon the engine speed, and means for controllably varying the rate of fuel supply.

2. An internal combustion engine having a combustion space and comprising means, including a fuel flow controlling pump, for supplying fuel to said combustion space at a rate independent of the engine speed, means for supplying air to said space at a rate dependent upon the engine speed, and means for controllably varying the speed of said pump independently of the speed of the engine.

ALAN F. GILL REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,871,989 Heitger Aug. 16, 1932 1,598,712 Chryst et al Sept. 7, 1926 1,534,829 Behnke Apr. 21, 1925 1,449,642 Warenskjold et a1. Mar. 27, 1923 1,935,924 Tice Nov. 21, 1933 1,853,811 .Hewitt Apr. 12, 1932 1,267,728 Winton May 28, 1918 1,835,615 Robert Dec. 8, 1931 1,991,390 Holzwarth Feb. 19, 1935 877,194 Holzwarth Jan. 21, 1908 1,877,983 Schilling Sept. 20, 1932 2,020,794 Mock Nov. 12, 1935 FOREIGN PATENTS Number Country Date 544,940 British May 4, 1942

Images