US2749898A

US2749898A - Fuel injection control

Info

Publication number: US2749898A
Application number: US370593A
Authority: US
Inventors: Walter F Isley
Original assignee: Continental Motors Corp
Current assignee: Continental Motors Corp
Priority date: 1953-07-27
Filing date: 1953-07-27
Publication date: 1956-06-12
Anticipated expiration: 1973-06-12

Description

A I V iii W. F. ISLEY Filed July 27, 1953 FUEL INJECTION CONTROL June 12, 1956 70 f/VG/A/f N M R n I. a A. 6 i f 2. 1% Ni V Q a 32 3 a m/ Z 2 2 1 0D B A 22 3 INVENTOR. WALTER F. IS LEY ATTO RNEYS United States Patent FUEL INJECTION CONTROL Walter F. lsley, Grosse Pointe, Mich, assignor to Continental Motors Corporation, Detroit and lvlnsliegon, Mich, a corporation of Virginia Application July 27, 1953, Serial No. 370,593

3 Claims. (Cl. 123-440) The present invention relates to fuel injection control means for the purpose of controlling the operation of fuel injection pumps and specifically to the actuation of such means in relation to manifold pressures of supercharged engines.

In the regulation of fuel delivery from variable discharge pumps in accordance with manifold pressures, the results heretofore obtained do not provide the fuel economy desired nor the most efficient fuel-air ratios obtainable at higher engine speeds. If some compensation is not made for the higher speeds, the fuel-air ratios become excessively rich. The droop in air rate at higher speeds is due to the volumetric efficiency change of the engine with speed, whereas the injector is a pump with essentially constant volumetric efficiency, hence the fuel rate is greater than that desired. Valves heretofore utilized to solve this problem have not proven satisfactory since they are unreliable, sensitive to barometric pressure, and ineffective on part throttle metering.

Therefore an object of this invention is to prevent the fuel-air ratio from becoming excessively rich due to the droop in air rate at high speeds, by providing a device which will effect a corresponding high speed droop in fuel metering rate.

Another object of this invention is to eliminate barometric sensitivity and make fuel metering more dependent on engine speed by providing a metering control valve which will effectively sense the pressure differential across the engine supercharger, since supercharger pressure rise is a function of engine speed.

Still another object of the invention is to simplify the fuel metering control by providing a valve comprising a minimum of connections and adjusting means, and utilizing none or" the mechanical connections to the throttle which heretofore have proven unreliable, since throttle position is not a true indication of engine speed.

With these and other objects as will be readily understood by those skilled in the art, reference is made to the following description and drawing wherein like characters refer to like parts throughout the several views, and in which Fig. 1 is diagrammatic illustration showing the arrangement and operation of the invention, and

Fig. 2 is a central vertical sectional view of the actual construction of the valve shown in the lower portion of Fig. 1. i

In the drawing, referring first to Fig. 1, a supercharge engine (not shown) is indicated with the supercharger 10, its air inlet 11 and its outlet 12 leading to the engine manifold. A suitable variable output fuel pump is indicated at 13, the variation of output being controlled by the position of a pin 13A determined by the bellows 13B, the expansion and contraction of which is due to the variation of pressure in the enclosing pressure compartment 13C. A decrease of pressure on compartment 13C results in a reduced fuel rate output of the pump 13.

From the diagram of Fig. 1, it will be noted that three

conduits

14, 15 and 16 are open to the main air conduit, conduit 14 opening to the air intake close to but ahead or upstream of the throttle 17. The second conduit 15 is open to the air intake behind the throttle 17 or downstream thereof but ahead or upstream of the supercharger 10. The third conduit 16 is open to the air outlet downstream or beyond the outlet of the supercharger.

As indicated, the conduit 14 leads first to a check valve 14A, beyond which it branches, one branch 14B terminating in the jet 14C of a venturi 18. The other branch 14D leads through a regulating valve 19 to a conduit 20 connected to the low pressure chamber of the venturi 18.

The conduit 15 is also branched with one branch 15A leading to the outlet of a needle valve 21 enclosed in a casing 22 of a valve structure and fixed to a diaphragm 23 in the casing while the other branch 1513 leads to the chamber 31 of the valve structure under the diaphragm, i. e., to the side of the latter opposite the needle valve 21.

The conduit 16, which is constructed in open communication with air outlet 12, is arranged to receive the flow of air from the jet 14C and is also connected to the low pressure chamber of the venturi 18, to which is also connected the conduit This conduit 2% as stated above, is open to the conduit MD, and is connected to both the pressure compartment 13C of the pump and through a passage 228 to chamber 22 of the valve structure, terminating in the latter on the needle valve side of the diaphragm 23. A suitable restriction 23A is placed in conduit 25;" between conduit 14D and the connection to the pump.

The control means indicated in Fig. 1, consists of two parts, namely the idling control part A and the high speed control part B, control part A serving to control the pump at idle or with the throttle open only a small amount. As the throttle is opened, however, this part A of the control means becomes inactive because check valve MA closes, and the other control part, designated B, takes over control. The control part B, just referred to, consists of the

conduits

15 and 16 and the valve structure shown in the lower portion of Fig. l, the actual structure of the valve being shown in Fig. 2. The construction and operation of control part A is described and claimed in my copending application Ser. No. 370,535, filed July 27, 1953, and entitled Fuel Injection Control.

T he valve structure consists of the housing 22, which for convenience is preferably a rather thick walled casing closed at its bottom end by a cap member 30 between which and the end of the chamber walls of housing 22 is clamped the diaphragm 23.

The cap 30 is provided with a well or chamber Si in which the spring 23A is located and held between the diaphragm 23 and the head of an adjusting screw 32 threaded through the bottom wall of the cap, the projecting end of screw 32 being protected by a cap or cover 33.

In the chamber 22A formed within the casing 22, above and fixed to the diaphragm 23, is the valve 21, slidably mounted in a sleeve 34 threaded into the upper wall of the chamber. The pointed upper end of the valve opens and closes communication between passage 15A within the upper wall of the casing 22 and chamber 22A through

passages

22B and 35. The passage 15B is shown as extending partially through the upper wall, then down within the side wall where it connects, through a suitable nipple with a passage 1115 opening to the chamber 31 in cap 3% by means of the passage 115A.

Also in the upper wall of casing 22 is a through passage 228, to one end of which is connected conduit 20 and to the other end of which is connected the vacuum As shown in the drawing, the bearing sleeve 34 for the valve 21 is provided with suitable openings 36 so as not to block the through passage 22B. And the spring 23B is shown as mounted between the lower end of sleeve 34 and a suitable shoulder on the valve 21.

As noted above and described in my copending application aforesaid, there is a drop in pressure from conduit 16 to 20 during closed throttle or idling operation, because check valve 14A is open and this drop in pressure is caused by the venturi construction 140. On opening the throttle, the proper fuel and ratio is maintained during the first portion of the throttle opening; that is, during engine idling operation by means of the operation of control part A. Almost immediately the check valve 14A is closed as the throttle is opened to increase engine speed, and during this intermediate engine speed operation, before control part B takes over, the pressures in

conduit

16 and 20 are substantially the same and pressure compartment 13C of the injection pump is directly responsive to pressure variations in

conduit

16 and 20, and during this intermediate engine speed operation the correct fuel and air ratio is automatically maintained. As the throttle moves to full open position, the fuel and air mixture tends to become too rich, and thus control part B is constructed and arranged to take over and decrease the fuel rate of the injection pump delivery.

As the throttle opens and the supercharger speeds up, the pressure differential between the intake and delivery of the supercharger greatly increases while the pressure in conduit also increases from a sub-atmospheric to substantially atmospheric pressure. The pressure in conduit 16 will remain subatmospheric until the throttle nears full opening but will become greater and greater until it becomes over-atmospheric. In response to such increasing pressures in conduit 16, the pressure in pump pressure compartment 13C, will also be increasing. Chamber 22A is open to conduit 16-20 and chamber 31 is open to conduit 15 and 158. However, as the pressure increases in chamber 22A above the diaphragm as a result of the increase in pressure in conduits 1620, it tends to open valve 21, and when such pressure exceeds the combined effort of the spring 23A and the pressure in the chamber 31 below the diaphragm, valve 21 will open, permitting pressure flow from chamber 13C through the open valve passage 22B to passage 15A and thence through conduit 15 to the supercharger inlet 11. Because of a pressure drop from conduit across orifice 20A, the flow through the valve reduces the pressure to chamber 13C, hence variably reducing the rate of fuel output of the injector pump 13 in the higher ranges of engine speed. The degree or magnitude of the pressure limiting effect in compartment 130 is a function or result of the relative rate of spring 23A, the size or rate of opening caused by the corresponding movement of valve 21, and the size of the restricted orifice 20A.

I claim:

1. In an apparatus for supplying fuel to an internal combustion engine having an air intake system, a supercharger in said system, and a variable delivery engine driven fuel injection pump provided with a pressure compartment and with a pressure responsive control device in said compartment and operable to vary the fuel output of said injection pump, a control means for controlling the pressure in the pressure compartment of said pump, a conduit connected with said air intake upstream of said supercharger and another conduit connected with said air intake downstream of said supercharger, and with the pressure compartment of said pump ported means and a valve structure disposed between said conduits and comprising a valve casing, provided with a compartment and a flexible diaphragm dividing said valve compartment into upper and lower chambers, a valve carried by said diaphragm and actuated to control the ported means connecting said first conduit with said second conduit, said second mentioned conduit open to said upper chamber, said first mentioned conduit open to said lower chamber, adjustable spring means in the lower chamber urging the valve to closed position, a precalibrated restricted orifice in said second conduitintermediate the connection of the second conduit with the air intake system of the engine and the connection between said second conduit and the pressure compartment of said pump, said valve opening in response to pressure rise in said second conduit to reduce the pressure in said pressure compartment of the pump by reason of the drop in pressure produced across said precalibrated restricted orifice aforesaid.

2. In an apparatus for supplying fuel to an internal combustion engine having an air intake system, a supercharger in said system, and a variable delivery engine driven fuel injection pump provided with a pressure compartment and with a pressure responsive control device in said compartment and operable to vary the fuel output of said injection pump, a control means for controlling the pressure in the pressure compartment of said pump, a conduit connected with said air intake upstream of said supercharger and another conduit connected with said air intake downstream of said supercharger and with the pressure compartment of said pump, a precalibrated restricted orifice in said second mentioned conduit, a port connecting said conduits, a valve controlling said port, means urging said valve to closed position, and valve actuating means operable in response to increasing pressures in said second conduit on opening said throttle to full open position to open said port, whereby to induce flow from said second conduit to said first conduit and causing a pressure drop across said precalibrated restricted orifice and thereby causing a decrease in pressure in said pressure compartment of said pump.

3. In an apparatus for supplying fuel to an internal combustion engine having an air intake system, a supercharger in said system, and a variable delivery engine driven fuel injection pump provided with a pressure compartment and with a pressure responsive control device in said compartment and operable to vary the fuel output of said injection pump, a control means for controlling the pressure in the pressure compartment of said pump, a conduit connected with said air intake upstream of said supercharger and another conduit connected with said air intake downstream of said supercharger and with the pressure compartment of said pump, a precalibrated restricted orifice in said second mentioned conduit, a port connecting said conduits, a valve controlling said port, means urging said valve to closed position, and valve actuating means operable in response to increasing pressures in said second conduit on opening said throttle to full open position to open said port, whereby to induce flow from said second conduit to said first conduit and causing a pressure drop across said precalibrated restricted orifice and thereby causing a decrease in pressure in said pressure compartment of said pump, said means urging said valve to closed position comprising adjustable spring means and connections to the pressure in said first conduit.

References Cited in the file of this patent UNITED STATES PATENTS