US2988077A

US2988077A - Modulus metered fuel injection system

Info

Publication number: US2988077A
Application number: US717178A
Authority: US
Inventors: Frederick W Hottenroth
Original assignee: Individual
Current assignee: Individual
Priority date: 1958-02-24
Filing date: 1958-02-24
Publication date: 1961-06-13
Anticipated expiration: 1978-06-13

Description

June 13, 1961 HoTTENRoTH 2,988,077

MODULUS METERED FUEL INJECTION SYSTEM 1 I 2 l l l l ,IH

INVENTOR.

United States Patent C 2,988,077 MODULUS METERED FUEL INJECTION SYSTEM Frederick W. Hottenroth, 2472 Overlook Road, Cleveland Heights, Ohio Filed Feb. 24, 1958, Ser. No. 717,178 Claims. (Cl. 12S-140) This invention relates to a fuel injection system for internal combustion engines in which the modulus of elasticity of the fuel itself is the measuring index for the successive charges of fuel delivered to the engine during the cycles of operation thereof.

One of the biggest problems in connection With present day fuel injection systems is the accurate metering of fuel into each cylinder so that each cylinder receives exactly the amount of fuel required for proper proportioning to the mass of induced air under the conditions existing at the moment. It is also extremely desirable that the system be responsive to changes with a minimum of time lag.

One object of my present invention is to provide a system which solves both of these problems and in addition is simple, both structurally and in operation, and is low in cost.

The common method of metering fuel for a fuel injection system measures slugs of fuel and distributes them to individual cylinders through piping having considerable volume. The fuel is injected either directly into the cylinder or at the intake valve. A spring-closed nozzle is generally used. The measurement is generally accomplished by a variable volume cylinder and piston pump. The slug volume is adjusted by suitable means affected by existing conditions.

Another object of my invention is to provide a small container or reservoir for fuel metering purposes preferably located closely adjacent each cylinder and which reservoir has a definite volume proportionally related to the modulus of elasticity of the fuel being used and to the change in volume of such fuel as between the maximum pressure thereof furnished by a fuel pump and the minimum pressure thereof resulting from the opening of a fuel admission valve from the fuel metering reservoir to the engine cylinder or its intake. To prevent undesirable additonal ilow of fuel from the fuel pump, a restriction is placed in the line leading from the fuel pump to the fuel metering reservoir, preferably just ahead of the reservoir.

A further object is to provide a fuel injection system in which the fuel charge is essentially dependent upon the fuel pressure so that by regulation of the fuel pressure it is possible to regulate the amount of fuel charge in response to existing conditions.

Still a further object is to provide a system in which the pressure in a fuel manifold is regulated by a by-pass type of regulator which itself is automatically varied to meet fuel requirements in response to manual control to change the speed of the engine modified by other factors such as air charge density, mass air flow, rich start mixture, rich idle mixture, rich mixture to obtain maximum power at full load operation and/or full throttle operation, acceleration and control associated therewith to prevent a momentary lean mixture condition upon sudden opening of the engine controlling throttle, fuel cut-off during deceleration, barometric pressure, ambient temperature and the like.

An additional object is to provide means in the system to permit use of lower pressures for the same size of container by the inclusion in the fuel metering reservoir of a material such as foam rubber, a rubber bag filled with air or the like, which has a lower modulus of elasticity than the fuel.

2,988,077 Patented .lune 13, 1961 ICC A final object is to provide a modulus metered fuel injection system wherein fuel is supplied under pressure to a cylinder of an internal combustion engine and means is provided for controlling the fuel from the supply comprising a fuel metering reservoir having a volume substantially equal to the change in such volume divided by the product of the modulus of elasticity of the fuel being used and the change in pressure of such volume, a restriction being provided between the fuel supply and the fuel metering reservoir, a fuel admission -valve being provided between the `fuel metering reservoir and the cylinder, and means being provided which is cyclically operable `for opening the fuel admission Valve.

With these and other objects in view, my invention consists in the combination of elements constituting my modulus metered fuel injection system, whereby the objects above contemplated are attained, as hereinafter more fully set forth, pointed out in my claims and illustrated in detail on the accompanying drawing, wherein:

FIG. l is a diagrammatic view of a modulus metered fuel injection system embodying my invention;

FIG. 2 is a diagrammatic view of an internal combustion engine with a fuel metering reservoir, fuel admission valve and a restriction of my system, shown in conjunction therewith;

FIG. 3 is a diagrammatic view illustrating the metering action of the fuel metering reservoir of my fuel injection system;

FIG. 4 is a similar diagrammatic View showing a modication of the fuel metering reservoir and the action involved; and

FIG. 5 is a diagrammatic view showing another modiiication of my system in which a restriction for fuel flow consists of a fuel shut-off valve.

On the accompanying drawing, I have used the reference character FT to indicate a fuel tank from which a fuel pump FP pumps fuel through a filter F to a fuel manifold FM. The pressure of the fuel in the manifold FM is regulated by a pressure regulator PR of the by-pass type.

Conduits

10, 12 `and. 14 convey the fuel from the fuel tank FT to the fuel manifold FM and

return conduits

16 and 18 convey the by-passed fuel controlled by the pressure regulator PR from the fuel manifold FM back to the fuel tank FT.

The system is shown in FIG. l as connected with a four cylinder internal combustion engine, the cylinders of which are indicated at C1, C2, C3 and C4. Conduits 2t), 22, 24 and 26 lead from the fuel manifold FM to fuel metering reservoirs FMR and a restriction R is located ahead of each reservoir. The reservoirs communicate with fuel admission valves FAV terminating in nozzles N directed into the respective cylinders or into the intake manifold adjacent the intake valves for the cylinders. An alternative arrangement is shown in my copending application Serial No. 725,384, tiled March 3l, 1958, now Patent No. 2,924,207, wherein there is one fuel metering reservoir for all cylinders of an engine and the fuel admission valve is also a distributor valve.

In operation, fuel pressure is built up in the system by operation of the fuel pump FP as from an electric motor M and this pressure extends throughout the elements 12, F, 14, FM, 16, 20, 22, 24, 26, R, FMR and FAV of the system. The pressure, of course, must be built up in each fuel metering reservoir FMR between the successive fuel injection cycles thereof, and the restrictions R (in the nature of conduits with capillary bores or pierced diaphragms in which the perforations are only a few thousandths of an inch in diameter) are calculated to take this into consideration. The fuel in each reservoir FMR is compressed an amount proportional to the applied pressure. This compressed fuel is held captive in the reservoir FMR until the fuel admission valve FAV is opened whereupon a change of fuel is injected into the engine cylinder because of the expansion of the fuel in the fuel metering reservoir. The quantity of the charge of fuel injected is essentially equal to the volume change of the fuel resulting from the effect of the pressure change on the compressibility of the liquid. There will be a small additional amount of fuel delivered because of the flow of fuel through the restriction R while the Valve FAV is open but this is negligible because of the small size of the restriction and the Valve being open for only a short period of time.

To illustrate the Kfuel metering action, reference is made to FIG. 3 wherein the fuel metering reservoir FMR has volume V represented by the area of a rectangle b, c, f, e and Vc (rectangle a, b, d, e) represents a change in volume so that V plus Vc is the total volume of fuel when not under pressure and V is the volume thereof when under pressure. When the fuel admission valve FAV is opened, the compressed fuel in FMR expands and displaces the quantity Vc into the engine cylinder.

Assume the fuel to be gasoline. Gasoline has a compressibiility factor which gives a reasonable size volume for the reservoir FMR. A typical 8-cylinder gasoline engine consumes about .005 cubic inch per cycle per cylinder at 2,000 r.p.m. which decreases to about .004 cubic inch per cycle at 500 rpm., and also at 4,000 r.p.m. it decreases to about .004 cubic inch. A pressure of 1,000 p.s.i. compresses gasoline `0.7 percent or .007 of its original volume. Therefore, using the average figure of .005 for calculations, a volume of reservoir necessary to compress gasoline this amount would be 0.7 cubic inch at each cylinder. In other words, a reservoir having a volume of `0.7 cubic inch and fuel that is compressed `0.7 percent by 1,000 p.s.i. results in the calculation .7 .007 which gives an answer of approximately .005 which is needed as the cubic inch per cycle per cylinder requirement. This can be stated as an equation,

as follows:

VE V K Pc in which I/:volume of fuel metering reservoir Ver-desired change in volume of fuel K=modulus of elasticity of the fuel, and Pc=change in pressure of volume V which can be worked out as -ao-Xl000=%g==approximately .7 ou. in.

The value .000007 (modulus) is the Vchange in volume per unit volume per square inch.

Referring to FiG. 4, if a compressible body B is placed in the fuel metering reservoir, the volume of the reservoir can be reduced inversely proportional to the modulus ratio of such body to gasoline. The body B must, of course, have a lower modulus of elasticity than the gasoline and sponge rubber is suitable for this purpose. The volume of the body B is indicated as V1 (the entire solid line circle) whereas an applied pressure may reduce the volume to V2 (the small dotted circle). The compressed volume of the fuel equals the sum of the two Volumes to be compressed. One of these is the Volume of the body B and the other is the volume of the difference between the volume of the reservoir FMR and the body B. This sets up an equation as follows:

K V, Pc KP.,

V: KPDL K in which K1=Modulus of elasticity of compressible body, and V1=Initial volume of compressible body In my system it will be noted that the fuel charge is essentially dependent upon the fuel pressure. Therefore, by regulation of the fuel pressure it is possible to regulate the size of fuel charges to match existing conditions. Primarily this regulation may be done at the fuel manifold FM by the pressure regulator PR, by electric variation of the energization of the pump motor M, or by any other suitable means.

The pressure in the fuel manifold FM is regulated by the regulator PR which in itself may be automatically varied to meet fuel condition requirements by a diaphragm 28 which, in addition to sensing the pressure in the line 16 to provide automatic pressure regulation of by-pass type, senses air intake manifold conditions (AIM in FIG. 1) which in turn are varied by foot acceleration position by reason of the accelerator controlling a butterfly valve for the intake to the engine cylinder. The action of the pressure regulator may be modified by other factors such as rich start mixture, fast idle throttle, barometric pressure, etc. These modifying conditions are indicated RSM, FlT and BP respectively in FIG. l.

During the operation of the system the fuel passes through the restriction R and builds up pressure in the fuel metering reservoirs FMR until it reaches the manifold pressure value before it is time to open the valve FAV. This valve opens during the intake stroke of the engine piston shown at 30 in FIG. 2 in the cylinder C1. For instance, it may be opened by a push rod 31 actuated by a cam 32 on the intake cam shaft 34 which also actuates the intake valve 36 of the engine. When the pressure of the fuel held in the metering reservoir FMR is released, the fuel expands and the volume of expansion is discharged through the nozzle N. Shortly thereafter the valve FAV is reclosed and pressure again builds up in the container FMR as the fuel is admitted through the restriction R.

Alternate `arrangements may be used based on the same basic operating principle that the modulus of elasticity of the fuel itself is the metering characteristic of the system. Instead of a restriction R as in FIG. l, a fuel shut-off valve FSV may be used as shown in FIG. 5 which closes before the valve FAV opens and reopens after the valve FAV recloses. A desired quantity of fuel is thus held captive in the reservoir FMR between the closing of the valve FSV and the opening of the valve FAV. This makes a system which yis theoretically correct volume-wise since it eliminates the ow through the restriction R during the charge period of the reservoir FMR, and it also eliminates the small hole of the restriction R which is subject to clogging during operation in case the fuel is dirty.

Some changes may be made in the construction and arrangement of the parts of my modulus metered fuel injection system without departing from the real spirit and purpose of my invention, and it is my intention to cover by my claims any modified forms of structure or use of mechanical equivalents which may reasonably be included within their scope.

I claim as my invention:

1. A modulus metered fuel injection system comprising means for supplying fuel under pressure to a cylinder of an internal combustion engine, and means for controlling the fuel from said first means comprising a fuel metering reservoir, means for restricting the ow of fuel from said fuel supply to said fuel metering reservoir, a fuel admission valve between said fuel metering reservoir and the engine cylinder, and means for opening said fuel admission valve each cycle of operation of the engine, said fuel metering reservoir having a normal volume so related to the change in such normal volume under an applied pressure from said means for supplying fuel under pressure through said restricted means, to the modulus of elasticity of the fuel land to the change of such applied pressure that when pressure held captive in said reservoir between said restricting means and said fuel admission valve when closed is released by opening of said fuel admission valve, a charge of fuel will be discharged to the engine cylinder which charge has a volume that is the difference between the normal volume of said reservoir and such normal volume under said applied pressure.

2. A modulus metered fuel injection system comprising means for supplying fuel under pressure to a cylinder of an internal combustion engine, and means for controlling the fuel from said lirst means comprising a fuel metering reservoir, means for restricting the flow of fuel from said fuel supply to said fuel metering reservoir, said means comprising -a fuel shut-off valve, a fuel admission valve between said fuel metering reservoir and the engine cylinder, and means for sequentially closing said fuel admission valve before opening said fuel shutoff valve and then closing said fuel shut-off valve before opening said fuel admission valve each cycle of operation of the engine, said fuel metering reservoir having a normal volume so related to the change in such volume under an applied pressure from said means for supplying fuel under pressure through said fuel shutoff valve, to the modulus of elasticity of the fuel and to the change in such applied pressure that when pressure held captive in said reservoir between said fuel shut-olf valve and said fuel admission valve when both are closed is released by opening of said fuel admission valve, a charge of fuel will be discharged to the engine cylinder which charge has a volume that is the difference between the normal volume of said reservoir and such normal volume under said applied pressure.

3. A modulus metered fuel injection system comprising means for supplying fuel under pressure to a cylinder of an internal combustion engine, and means for controlling the fuel from said first means comprising a lfixed volume fuel metering reservoir hav-ing a volume equal to that required for the difference between the volume off fuel in said reservoir under an applied pressure yand the volume of fuel therein under the pressure at which a charge thereof is released Ito the cylinder to be the only volume constituting such charge, means for restricting the ow of fuel from said fuel supply to said fuel metering reservoir, a fuel admission valve be` tween said fuel metering reservoir and said cylinder, means cyclieally operated for opening said fuel admission valve, and means to vary the applied pressure to change the volume of the fuel charge to meet engine requirements.

4. A modulus metered fuel injection system comprising means for supplying fuel under pressure to a cylinder of an internal combustion engine, and means for controlling the fuel from said first means comprising a fixed-volume fuel metering reservoir having a volume equal to that required for the difference between the volume of fuel in said reservoir under an applied pressure and the volume of fuel therein under the pressure at which a charge thereof is released to the cylinder to be the only volume constituting such charge, means for restricting the flow of fuel from said fuel supply to said fuel metering reservoir, said means comprising a fuel shut-olf valve, a fuel admission valve between said fuel metering reservoir and said cylinder, means cyclically operated for closing said fuel admission valve before opening said fuel shut-off valve and for closing said fuel shut-off valve before opening said fuel .admission valve, and means to vary the applied pressure to change the volume of the fuel charge to meet engine requirements.

5. A modulus metered fuel injection system comprising means for supplying fuel under predetermined pressure to a cylinder of an internal combustion engine, and means for controlling the fuel from said first means comprising a rst valve and a fixed-volume fuel metering reservoir in which ythe fuel is compressed to said predetermined pressure and then trapped by said first Valve, and a second valve opened in n'med relation to the operating cycles `of the engine for releasing only the differential volume of the compressed and trapped fuel to the engine cylinder, which differential volume is the difference between the volume of fuel in said reservoir when at said predetermined pressure and the volume thereof when said second valve is open to the engine cylinder and the pressure has equalized with that in the cylinder.

6. A modulus metered fuel injection system according to claim 5 in which said fixed-volume fuel metering reservoir has therein a compressible body of material that has a lower modulus of elasticity than the fuel.

7. A system for modulus metering liquid to a liquid receiver, which system measures individual charges of the liquid, comprising a fixed-volume chamber, an inlet valve leading thereto, an outlet valve leading therefrom to the receiver, means for pumping liquid through said inlet valve into said chamber and compressing the liquid therein, means for closing said inlet valve and then opening said outlet valve so the quantity of liquid metered to the receiver is equal only to the difference between the volume of the liquid in said fixed-volume chamber compressed by the inlet pressure and the volume of the liquid in the chamber when the liquid is permitted to expand by its reduction in pressure to the pressure in the receiver.

8. A modulus metering system for delivering liquid comprising means `for supplying liquid under predetermined pressure to `a point of consumption thereof, and means for controlling charges of liquid from said first means comprising a fixed-volume liquid metering reservoir in which the liquid is compressed and `trapped to said predetermined pressure, and -a valve associated With said reservoir for releasing a portion only of the compressed and trapped liquid to said point of consumption when said valve is opened, said portion being the differential volume of liquid compressed in said chamber compared to such liquid when decompressed by opening of said valve.

9. A modulus metered fuel injection system according to claim 2 .and including a compressible body of material in said fuel metering reservoir having a lower modulus of elasticity than the fuel.

10. A modulus metered fuel injection system according to claim 4 in which said fuel metering reservoir has therein a body of lower elastic modulus than the fuel.

References Cited in the file of this patent UNITED STATES PATENTS 1,919,601 Simmen July 25, 1933 2,420,550 Miller May 13, 1947 2,453,196 Clark Nov. 9, 1948 2,576,451 Dickson et al Nov. 27, 1951 2,592,132 Feilden et al. Apr. 8, 1952 2,747,555 Brunner May 29, 1956 2,825,396 Greer et al Mar. 4, 1958