US2914055A - Biasing control for fuel injection system - Google Patents

Description

Nov. 24, 1959 H. M. GAMMON BIASING CONTROL FOR FUEL INJECTION SYSTEM Filed Feb. 20, 1956 2 Sheets-Sheet 1 .57 V E .27 TE z" //0 WA RD M 624M10 Hiya.

Nov. 24; I H. M. GAMMON BJIIASING CONTROL FOR FUEL INJECTION SYSTEM Filed- Fe bQ 20, 1956 2 Sheets-Sheet 2 f'YI EJ-Z 2722- flaw/mo 44. @AMMO/V moi;

United States Patent i BIASING comm. FOR FUEL INJECTION SYSTEM Howard M. Gammon, Chardon, Ohio, assignor to Thompson Ramo Wooldridge, Inc., a corporation of Ohio Application February 20, 1956, Serial No. 566,461

2 Claims. (Cl. 123-140) engine should be varied in response to the amount 1 of air admitted to the combustion chamber in order to achieve perfect combustion. In many types of fuel injection control systems for internal combustion engines of the piston type, the quantity of fuel that is metered to the engine is regulated in accordance with induction system pressure that is measured by a sensing device in the control mechanism. In some cases, the fuel control mechanism does not obtain a pressure signal from the induction system instantaneously, wherein a rapid increase in induction system pressure results in a temporary leaning of the fuel-air mixture ratio until that time when the sensing device obtains an induction system pressure change signal. Such a temporary leaning of the mixture ratio is undesirable, particularly because it momentarily reduces the power and efiiciency of the engine.

In a carbureted engine, the same problem exists but is overcome by an accelerator pump or plunger that responds to the rapid change of throttle motion by injecting extra fuel into the induction system thereby avoiding a gas leaning out of the mixture. Some fuel injection systems utilize similar devices to displace extra fuel directly into the intake manifold or internally overriding the con trol linkage to create a higher rate of fuel displacement for injection. For the most part, these systems have not been altogether satisfactory and have included more or less complicated mechanisms.

Accordingly, it is an object of this invention to provide an improved device for regulating the quantity of fuelmetered to internal combustion engines that obviates the above named difficulties, and automatically regulates the fuel feed as to secure at all times proper combustion mixtures.

Another object of this invention is to provide a simply constructed mechanism for use with fuel injection systems which instantaneously provides momentary increases in metered fuel upon demand from a rapid increase in in duction system pressure.

A further object of this invention resides inthe provision of a biasing control for fuel injection systems associated with internal combustion engines which instantaneously reduces the quantity of metered fuel at a time when the throttle linkage is moved suddenly to close the butterfly valve in the induction system manifold, thereby conserving fuel and minimizing the quantity of unburned hydro-carbons that are expelled from the engine exhaust system.

Other objects, features and advantages of the invention will be apparent from the following detailed description of the accompanying sheets of drawings, wherein like ref- 2,914,055 Patented Nov. 24, 1959 ice erence numerals refer to like parts, in which, on the drawrugs:

Figure 1 is a diagrammatic view of a fuel control system embodying the present invention;

Figure 2 is a diagrammatic view of a fuel control system embodying a different form of the invention;

Figure 3 is a diagrammatic view of a fuel control system embodying a still different form of the invention; and

Figure 4 is a diagrammatic view of a fuel control system embodying another form of the invention.

As shown on the drawings:

, Referring now to Figure l, 10 represents an air intake manifold of an internal combustion engine having a fuel injection system (not shown) for metering fuel to the combustion chambers thereof. A butterfly valve 10a is interconnected with the throttle linkage of the engine for controlling the air pressure in the manifold. The manifold operates under a negative pressure or a vacuum. As is well known in fuel injection systems, a plurality of injectors are provided, one for each combustion chamber wherein the amount of fuel metered at each injection is regulated by a metering control through rod 11. This metering control is augmented by a pressure sensing element 12 responsive to engine manifold pressure. In the present invention, a biasing control element 17 is connected to the pressure sensing element to bias the function of said sensing element.

Actuation of the injector control rod 11 is in response to a pressure sensing device 12 having a casing or housing 13 of any suitable configuration. The control rod 11 extends through a bore in one end of the housing 13 and has its free end connected to a rigid portion of a flexible bellows 14 or other pressure responsive element in a pressure chamber 15 of the casing 13. The inside of the bellows 14 communicates with the atmosphere through a series of apertures 16 (only one shown) formed in the end of the housing 13 sothat any pressure above or below atmospheric pressure in the chamber 15 acts on the bellows 14 and the control rod 11. The contro-lrod '11 operates the fuel injector shown schematically at 40, which maybe of any desired construction. Movement of the control rod 11 in the direction marked Ace. will operate the injector to feed more fuel to the engine for acceleration and movement in the direction marked Dec. will de' crease the supply of fuel.

During the running of an engine having this fuel control system, the chamber 15 of the pressure sensing device is subjected to the pressure in the manifold 10, and.

is thusly in communication with the manifold through a biasing element 17. Hence, the control rod 11 normally responds to the variations in induction system pressure. The biasing element 17 includes a hollow cylinder 18 connected at one end to the chamber 15 of the pressure sensing element 12 through a suitable pipe or conduit 19, and at the other end to the intake manifold 10 through a suitable pipe or conduit 20. A piston 21 is slidably received within the cylinder bore and provided with a clearance 22 of predetermined dimension therewith. Connected to the piston 21 is a piston rod 23 which extends through one end of the cylinder 18 to be connected to the throttle linkage and foot accelerator pedal of the engine. An accelerator pedal 42 is shown pivoted at 43 on a support 41 for manual operation for operating the throttle butterfly 10a and the piston 21. The pedal 42 v is connected to an arm 53 of a bell crank 45 by a link is transmitted to the piston by connecting the piston rod 23 to the arm 52 of the bell crank.

In operation, when the foot pedal is suddenly pushed down toward its support 41 in the direction to accelerate the engine, the butterfly valve a will open to permit greater air flowage within the manifold 10, thereby decreasing the vacuum in the system including cylinder 18 and chamber 15. The piston 21 will be mechanically advanced by the accelerator pedal linkage towards the end 18a of the cylinder 18 which is in communication with the pressure sensing mechanism 12. This action on the piston instantaneously provides a compression of gases ahead of the piston that is immediately sensed by the pressure sensing mechanism 12, the positive pressure created by the sensing element subtracting from the vacuum in the manifold thereby collapsing the bellows 14 and causing the control rod 11 to be actuated for increasing the flow of metered fuel sent to the engine combustion chambers.

Due to the clearance 22 between the loosely fitting piston 21 and the cylinder bore, pressure on opposite sides of the piston 21 will equalize in a predetermined period of time to permit the sensing mechanism to respond to the manifold pressure. During normal operation, the clearance between the piston and the cylinder is sufficiently great so that small variances in manifold pressure will be registered almost instantaneously on the pressure sensing mechanism of the injector control. Alternatively, the piston could make sealing contact with the cylinder bore and be provided with a metered passageway therethrough. Hence, the biasing signal set up in the biasing element 17 by accelerator pedal movement and transmitted to the pressure sensing mechanism 12 instantaneously causes the fuel injection control to inject a larger amount of fuel than would normally be injected and thereby satisfies the immediate demand for accelerations and enrichment of the air-fuel mixture.

After a short acceleration time, pressures on both sides of the piston 21 will equalize and the fuel injector will be controlled by pressure in the manifold 10 as controlled by the factors of the position of the throttle valve 10a and the load on the engine as reflected in engine speed variation.

For deceleration conditions, should the throttle linkage be moved suddenly in the direction to close the butterfiy valve, the piston 21 will be suddenly moved to the end 18b of the cylinder 18 which.communicates with the manifold thereby reducing the pressure in the end of the cylinder that communicates with the pressure sensing mechanism 12 and, thusly, reducing the quantity of metered fuel to be fed to the engine by movement of the injector control rod 11. This biasing control, therefore, eliminates the inherent time delay in most fuel injection systems.

It will be understood that the relationship of the control rod 11 to the fuel injector and the relationship of the accelerator pedal linkage to the piston rod 23 and valve 10a, as shown and described in connection with Figure 1, will be the same in the forms shown in Figures 2, 3 and 4, and, therefore, need only be shown and described in detail in connection with Figure 1.

In Figure 2, a different form of the invention is illustrated, which largely differs from the embodiment shown in Figure 1 in that the manifold 10 is in direct communication with the chamber 15 of the pressure sensing mechanism 12 through a pipe or conduit 24. Also, the end 18b of the biasing element cylinder 18 towards which the piston 21 advances during deceleration of the engine is connected to the interior of the bellows 14 by a conduit or pipe 25, while the other end 18a of the cylinder is in communication with the atmosphere through a port 26. The operation of this embodiment is similar to that of the embodiment in Figure 1, except that depression of the accelerator pedal causes the piston 21 in the biasing element 17 to advance towards the end 18a of the cylinder 18 in which the atmospheric port 26 is positioned. This rapid acceleration will cause the inside of the bellows to be subjected to a reduced pressure which will instantaneously cause actuation of the control rod 11 to inject a larger amount of fuel into the engine cylinders. During deceleration, the piston 21 will be moved toward the end 18b of the cylinder 18, having the conduit 25 connected thereto, for expanding the bellows 14 and actuating the control rod to instantaneously reduce the quantity of metered fuel to be fed to the engine. Increases and decreases in vacuum in the manifold 10 will likewise expand and compress the bellows 14 to control the fuel supply during normal operation when the accelerator pedal and throtle valve 10a are not moved.

Referring now to Figure 3, the biasing element 17 is shown associated with a different arrangement. This arrangement is substantially identical with that in Figure 1, except that the pressure sensing element 12 represents a specific fuel injection control system, namely the American-Bosch system. Inasmuch as the detailed construction and operation of this control system are well known in the prior art, it is not necessary to explain too much detail. However, for purposes of clarity, the system includes a hollow cylindrical shell 27 open at one end and slidably receiving a piston 28 having a port 29 in one end and being biased towards the open end by a pair of springs 30. The piston 28 is hollow and slidably received therein is a second piston 31 which is connected to the injection control rod 11 and biased away from the port 29 by a spring 32.

Another embodiment of the invention, shown in Figure 4, is basically the same as that shown in Figure 2 in that the biasing element is disposed between the pressure sensing mechanism and atmosphere, except that the biasing element and the pressure sensing mechanism are enclosed Within a common housing or casing 33. In this embodiment, the common casing 33 includes a hollow cylindrical section 33a at one end and a diametrically reduced hollow cylindrical portion 33b at the other end.

The larger housing section 33a encloses the pressure sensing mechanism, while the smaller housing section 3312 encloses the biasing element. The control rod 11 for the injectors is connected to a piston 34 slidably received within the housing section 33a and normally biased in the direction of the control rod 11 by a spring 35. To receive a signal from the biasing element, a piston 36 slidably received within the bore of the biasing element cylinder in the housing section 33b is directly connected to the piston 34 by a rod 37. A chamber 38 is defined between the pistons 34 and 36 which more or less corresponds to the chamber 15 in the pressure sensing mechanism 12 of Figures 1 and 2, and is connected to the manifold by a pipe or conduit 39.

The operation of this embodiment is substantially identical with the foregoing embodiment, wherein a rapid movement of the throttle linkage to accelerate the engine advances the piston 21 to compress the gas within the cylinder between it and the piston 36 of the pressure sensing mechanism. This signal generated by the compression of gases subjects the piston 36 to a pressure and causes it to slide axially towards the larger housing section 33a, and since this piston is connected directly to the control rod 11, it causes the fuel injection control to eject a larger amount of fuel into the engine. During normal operation, the piston 34 is subjected to the manifold pressure through the line 39 for accordingly adjusting the amount of fuel metered to the engine by the injectors. The clearance 22 between the piston and the cylinder bore allows equalization of pressure on both sides of the piston 21 to equal that of the atmosphere through the port 40.

From the foregoing, it is seen that the instant invention provides a biasing control for fuel injection systems which instantaneously causes momentary increases or decreases in metered fuel to the engine upon rapid acceleration or deceleration demands. 7

It will be understood that modifications and variations may be effected without departing from the scope of the novel concepts of the present invention, but it is understood that this application is to be limited only by the scope of the appended claims.

I claim as my invention:

1. In an internal combustion engine having a fuel injection system and a pressure sensing mechanism responsive to the manifold pressure for controlling the quantity of fuel metered to the engine by the system, the improvement of means for transmitting a pressure signal to said mechanism in response to rapid acceleration or deceleration of said engine for providing momentary increases or decreases in metered fuel to the engine, said means comprising a cylinder having a piston slidable therein and connected to the throttle linkage of said engine whereby relative movement between the piston and cylinder is caused with movement of the throttle linkage, one end of said cylinder communicating with said pressure sensing mechanism, said piston sized to provide a clearance of predetermined dimension with the bore of said cylin-:

der, and the other end of said cylinder communicating with the engine intake manifold.

2. The combination with an internal combustion engine of the injection type having an air intake manifold and a throttle valve therein, of adjustable fuel injection means, a pressure sensing mechanism, a control rod actuated by said mechanism and being connected to said injection means, said sensing mechanism responding to the pressure in the intake manifold, and signalling means between said sensing mechanism and said air intake manifold, said signalling means comprising a cylinder having a piston slidable therein and connected to said throttle valve, one end of said cylinder communicating with said sensing mechanism and said other end communicating with said intake manifold, and means defining a leakage path around the end of the cylinder connected with said sensing mechanism so that a temporary signal will be generated.

References Cited in the file of this patent UNITED STATES PATENTS 2,074,514 Muller Mar. 23, 1937 2,080,746 Schweizer May 18, 1937 2,189,475 Saur Feb. 6, 1940 2,794,432 Nystrom June 4, 1957 FOREIGN PATENTS 816,793 France May 10, 1937 378,233 Italy Jan. 26, 1940 572.787 Great Britain Oct. 23, 1945

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