US2410773A

US2410773A - Fuel control mechanism

Info

Publication number: US2410773A
Application number: US451874A
Authority: US
Inventors: Milton E Chandler
Original assignee: Chandler Evans Inc
Current assignee: Chandler Evans Inc
Priority date: 1942-07-22
Filing date: 1942-07-22
Publication date: 1946-11-05
Anticipated expiration: 1963-11-05

Description

Nov. 5, 1946;.'

M. E. CHANDLER FUEL CONTROL MECHANISM Filed` July 22 1942 lsbl.

vENToR nEChadler w o, 1 M mw NMF vm@ SS All ,w N 5 9 w QN Patented Nov. 5, 11946 41amV FUEL CONTROL MECHANISM Milton E. Chandler, New Britain, Conn., assignolj to Chandler-Evans Corporation, a corporation of Delaware Application July 22, 1942, Serial No. 451,874

nal combustion engines. A further object of my 'invention is to provide such an improved controlling mechanism especially adapted to use in connectlon with airplane engines,v either of the gasoline or fuel-oil operated type. A still further object of my invention is to provide such improved controlling mechanism of the typewherein the fuel supply through the injectors to the engine cylinders varies as a function of air flow to the engine, and wherein improved cooperating mechanism is provided to control the operation of the fuel injector pump in such manner as to maintain the quantity of fuel supplied by the injectors a function of air flow under all operating conditions of the engine including enrichment under overload conditions. A still further object of my invention is to provide improved controlling mechanism for the injector pump, wherein this controlling mechanism is controlled by variations in air flow, and -wherein the operation of said pump is also suitably modified by variations in the speed of the engine, while also including improved cooperating controlling means operative during the idling range. These and other objects and advantages will, however, hereinafter more fully appear.

In the accompanying drawing, I have shown 14 Claims. (C11. 12S-140) engine. In this construction, a connection i leads from the throat of the venturi 'I to a control valve casing il enclosing a diaphragm, generally indicated at D. which separates the casing into two expansible chambers I2 and lil. This connection i0 communicates with the chamber i2 below the diaphragm D, while a connection It leads from the scoop 8 through a chamber i5 communicating with the chamber i3 through an aneroid operated valve I5. Further, as shown, the diaphragm D comprises a central portion D' and a peripheral portion i32 surrounding the portion D and having its own periphery clamped between the peripheral portions of component casing members cooperating to form the lcasing il.

. Moreover, note that the portion D' of this diafor purposes-of illustration one embodiment which my inventio'n may assume in practice.

In this drawing: Y

Figure 1 is a diagrammatic view of my improved mechanism, and

Fig. 2 isa detail view showing the diaphragm valve of Figure 1 in a different position thereof.

In this illustrative construction, l'. have illustrated my invention asA applied to an engine I including a cylinder la and having a suitable service shaft 2' and injector pump mechanism, generally indicated at 3, driven from the shaft 2 by a wobble cam t and supplying fuel to an injector E, only one cylinder being shown in order to simplify illustration.

My improved controllingl mechanism, which controlsv the operation of the injector pump 3, herein includes controlling mechanism responsive to variations in air ow to the engine l. As shown, this mechanism includes an air meter d including a usual air venturi l, hereinof the rectangular type, and having a scoop and suitable throttle means s between theventuri i er.: the

dfi

phragm carries usual axially disposed cooperating discs Il and -a ring i8 of larger diameter than I these Vdiscs and has a coiled spring I9 biasing the ring i8 and the enclosed central portion D' of the diaphragm into the raised position shown in Figure 1, wherein the ring i8 is pressedagainst an annular series of stops 2li depending from the upper member 0f the casing il. The stops 2d are spaced so that the same pressure acts on the entire upper surfaceof diaphragm D. As shown,

a coiled spring 2|, lighter than the spring I8,-

acts on. saidupper member as an abutment and is also disposed centrally with and acts upon the upper face of the discs l1. On the opposite face f the discsil from the spring 2i is a depending button 22 attached to the adjacent face of a suitable small diaphragm 23 which is suitably attached to the lower casing member around the edge of an annular chamber 2t. This diaphragm 23 and valve member 22 are normally slightly raised by fluid pressure in chamber 2t, to provide communication beneath the diaphragm 23 between this annular chamber 2d and an axial discharge or drain passage 2b, and the button 22 rises and falls as necessary .to control the escape of iluid from chamber 2t, as hereinafter described. Note here also that connection between the chambers i2 and i3 on opposite sides of the diaphragm D is established by passages 2t and 2l having communication between the same controlled by a suitable valvel 28 forming a part of a usual manual rich mechanism, `not shown. The total air pressure differential between the scoop t and the throat of the venturi 'l is a measure of the velocity ofthe flowing/air. This pressure diierential produces a flow of air thru a secondary air passage which may be traced from scoop t thru connection it, chamber it, past valve it into chamber i3, connection 21, pastvnve 2|, mecum-es, chamber n ad e connection .Ilto the throat of venturi 1.

Inthis secondary-air passage, the total pres- Bure dinerentialbetween the scoop 8 and the throat oi' venturi A'I may be considered as being divided into two' component pressure drops, one y across thealtitude'compensating valve `|6 and the other across the restriction controlled 'by valve 23. The pressure responsive valve il cor' rects the pressure dinerential acting on the dia- Phrasm D so that it is an accurate measure of at its lower end at 39, and also pivotally cona nected between lts ends at 40 to a longitudinally A the mass'of air flowing per unit time. rather than Y the velocity of air flow. vUpon'a decrease in air density, such as accompanies an increase in altitude of an aircraft, the valve I6 moves .toward closed position.- thereby increasing the proportion of the total fuel pressure differential which,

takesplace scrum valve Ii, and decreasing the` proportion of the total fuel pressure differential which is effective on\ the diaphragm D, The

' pressure dierential on diaphragm Disthereby correctedfor the decrease in the` mass of air owingper unit time due to the decrease in density. l The valve 23 is normally in a position where a small fixed restriction connects the chambers l2 and I3. It may be manually moved from .this position to one -wheretheresriction is substantially closed.` When the restriction. is closed. there is no air now thru the secondary passage just traced, and hence no pressure drop thru the adjustable rod 4I controlling the positionof adjustment cfa valve member 42 in the injector pump 3.- In the illustrative constructiomthis valve member 42 is reciprocable in a fuel inlet chamber 43 in the injector pump casing and 'reciprocably mounted on the front ends of spring pressed plungers. operated by the wobble cam e, a' coiled spring I5 normally biasing' said valve member to the left. Herein, this valve member cooperates in its .diiierent longitudinal positions to vary the closing time of T-shapedinlet pas.. sageways 46 in the plungers 44 in such manner as to vary the amount of fuel supplied to these plungers from a usual fuel pump Il to fuel inlet valve I8. Valve Il then hasno controlling effect,

and the diaphragm D is then subjected v A to the total air pressure differential.

The pressure differential on the diaphragmy` D acts in a downward direction on the but- Aton' 22, and thereby tends to close the outlet passage 25. 'The pressure dierential on diaphragm 23 acts upwardly against the button 22; and thereby tends to open 'the outlet passage 25. Since the pressure in chamber I2 is small, being customarily measured in inches of water, while the pressure in chamber 2l :is relatively large, being customarily measured in inches of mercury or pounds per square inch, it may be considered that the force acting thru diaphragm 23 on button 22 in a valve opening direction is determined by the pressure in chamber 24, dis-- regarding the effect of variations in pressure in chamber l2.` The pressure diilerential acting downwardly on diaphragm D. as previously described,.is a measure of the mass of air entering the engine. yThe spring 2i assists this air pres- 41a and chamber 431. -Qheck valves I8 and relief .ports 49 communicating with relief passages 5@ being also provided.

. As a result of the control of the adjustment of the position of the piston 36 in accordance with variations in the air now to the engine. and the adjustment of the valve 42 by the piston 36,"lt will be apparent that the quantity of fuel supplied from the inlet Ila to each infector 5 will vary as a function of air now. Further, it willbe noted that when the air now increases sufllciently to overcome the spring i9 and increase the eective area of the diaphragm D, the pressure inpipe 33 will then be additionally built Iup in suchmanalso provided. A ball EOYernor; 5I, carried on a suitable engine service shaft, which may'ffbe the sure diierential' but, 'since this is a Arelatively light spring, its ei'l'ect lsnegligible except at very low air flows. The purpose and eect'of spring v2 I'at such low airfiows is explained below.

The position of button. 22 controls the pressure of nuid supplied to a fluid motor 35 which controls the displacement of the injector pump mechwhose outlet pressure is controlled by convenner as thereby to additionally actuate the" piston i8, i. e. even further, and thereby enrich the mixture as required under. such conditions'ffwhile maintaining the total j el flows. functionofair now. v, n j Cooperating with the mechanism above described and operating to'enablethe above control to be iniiuenced by variations in enginegspeed, improved cooperating controlling mechanism is shaft 2 or a suitableshaftfdriven therefrom, is connected to a dependlng'-linltb2 pivoted at 53 and connected through ac'rosslink 54 near its upper end to the lower end lot-the link-38.v .As a result of thisconnection',` hileythejjrod 4i will be operated by the piston .3l heretofore described to adjust the valve 42. theadlustment'of the latter will obviously be modified-by. the. action of the ball governor on the 5 2', the vgovernor moving the lower pivot 39 of the in sch mananism 3. The iiuid is supplied by' a gear pump 29,

tional relief valve 30. The fluid may be the-lubrieating oil of the engine, and the pump may be the usual oil pump. Most of the oil discharged by pump 29 passes thru a conduit 32, but a portion of the oil passes thru a restriction 3l intoal `conduit 33 and-thence thru chamber :fand the outlet controlled by the position o! button 22 into a drain 25, which .may be connected to a suitable reservoir or'to the inlet of pump 29. The fluid motor 35 includes a cylinder in which a piston 3B ismovable.` The nuid under pressure is supplied to the cylinder lfrom a conduit 34 coni nected to conduit 33. The pressure in conduit 33 (iiiA I ner 'as thereby to enable the speed of theengine to modify the effect ofgthelaircontrol and accordingly enable the mechanism to operate satisfactorlly under widely varying conditions.

Under idling conditions. the vquantity of air flowing thru the venturi I is quite small relative to the dimensions of the venturi. At such times, it hasbeen found that the pressure diiferential between the chambers l2 and I3 is not an accu- ,rate measure of the quantity'of air flowing thru the venturi. I have therefore provided the spring 2| which actsdownwardly onthe central portion Dv of the ldiaphragm D. At normal air flows, the force oi' spring 2| is so small as compared to the force due to the pressure differential acting on .the diaphragm that its enectis negligible. At low air ilows, however. the effect-of spring 2| on the diaphragm is large as compared to the eiect of Cooperating with the above described controlling mechanism is also further cooperating controlling mechanism modifying the operation of the injector pump during the idlingv range. As

shown, this mechanism includes a cam 55 carried on the throttle shaft 56 and cooperating with an adjustable member 51 carried on the lower end of the depending link `52. As shown, the latter link is biased toward the cam by a spring 58 and also carries an adjustable stop 59 engageable with a portion 59a on the engine and which cooperates with the member l in determining the limits of movement of the link 52 by the cam 55; Thus, when the throttle shaft 53 is adjusted into idling position, the above control mechanism automatically decreases the fuel delivered by the injector pump 3 to the quantity desired to operation.

It may be stated that the function of spring 2| is to transfer controlfof the fuel injector mechanism from the diaphragm D to the throttle during conditions of low air ow. Such conditions occur only when the throttle is within a range of positions adjacent its closed position, usually termed the idling range. The cam 55 is so de signed that it is effective to control the injector mechanism only when the throttle is Within this range of positions. Under such conditions, the spring 2l is eective-to maintain a substantially constant pressure in conduit 33, so that the position of piston 26 is substantially constant and the effective control of the fuel supply is 'provided by the throttle operated cam 55.

In the operation of the complete mechanism, in normal operation the central portion D of the diaphragm D will so control the valve member 22 and diaphragm 23 as to maintain the pressure in the pipe 33 a function of air flow. Consequently, the piston 36 through its connected linkage will so adjust the valve 42 automatically as to maintain the fuel flow from the fuel inlet 41a to the several plungers M also a function of air flow. Further, it will be apparent that as the engine speed varies, the ball governor 5I will modify the above control as necessary to automatically compensate for variations in engine speed, while, dur'- ing idling, the manual adjustment of the throttle shaft 56 will effect the desired manual adjustment during operation in the idling range. As the air flow to the engine increases, however, the normally functioning portion D' of the diaphragm D will be automatically increased in area by the addition of the peripheral portion D2 thereto, as above described, in such manner as further substantially to build up the pressure in the pipe 33,

and injectorsis provided, with each injector and cylinder successively supplied with a suitable charge of fuel through the action of the wobble cam ,4. Further, it will be understood that while I contemplate the use of my improved mechanism effect idling l scope of the appended claims.

What I claim as new and desire to secure by Letters Patent is:

1. In a fuel control mechanism for internal combustion engines, an air conduit, control means responsive to variations in the quantity of air flowing through said conduit,= hydraulic control mechanism controlled by said controlling means. fuel injector mechanism including an injector pump having a valve opened and closed during each cycle of operation of said pump, means con-l trolled by said hydraulic control mechanism for varying the time of closure of said valve to vary the delivery of said pump as a function of air flow, and means controlled by the engine throttle for modifying the closing time of said valve. i

2. In a fuel control mechanism for internal combustion engines, an air conduit,fcontro1 means responsive to variations in the quantity of air .flowing through said conduit, hydraulic control mechanism controlled by said control means, fuel injector mechanism including, an injector pump having a valve opened and closed during each cycle of operation of said pump, means controlled by said hydraulic control mechanism for varying thetime of closure of said valve to vary the delivery of said pump as a function of air flow, and

means controlled by engine speed for modifying the closing time of said valve.

3. In a fuel control mechanism, an air conduit, control means responsive to variations in the quantity of air flowing through said conduit, hydraulic controlmechanism including a cylinder and a piston therein reversely adjusted bysaid controlling means as a, function of air flow, fuel 'injector mechanism including an injector pump having a valve opened and closed during each cycle of operation of. said pump, linkage adjustable by said piston to control the time of closure of said Valve to vary the delivery of said pump as a function of air flow, and throttle operated means for adjusting said linkage to automatically vary the operation of said valve and the delivery of the pump during idling.

4. In a fuel control mechanism, an air conduit, control means responsive to variations in the quantity of air flowing through said conduit, hydraulic control mechanism including a cylinder and a piston therein .reversely adjusted by said controlling/ means as a function of air ow, fuel injector mechanism including an injector pump having a valve opened and closed during each cycle of operation of said pump, linkage adjustable by said piston to control the time of closure of said valve to vary the delivery of said pump as a function of air flow, and engine speed operated means for adjusting said linkage to modify vthe closing time of said valve in accordance with engine speed.

5. In a fuel supply system for an internal combustion engine, a conduit for air flowing to said engine 'for combustion purposes, means associated with said conduit for producing two unequal presinjector mechanism including a plurality of reciprocating pumps for supplying fuel directly to the cylinders of said engine,'means for controlling the fuel displacement per stroke of said pumps,

means responsive to the difference of said two unequal air pressures including a flexible diaphragm, means attached to said diaphragm for operating said fuel displacement controlling means and effective to increase said displacement in response to an increase of said difference of air pressures, spring means biasing said diaphragm in a direction to increase said fuel output, said spring meansl being effective when said difference of air pressures is small to operate said diaphragm in a displacement increasing direction, andfmeans operative as an incident to movement ofl said throttle means into a range of positions adjacent said closed position to reduce the displacement of said pumps regardless of the position of said diaphragm.

m i 6 A fuel supply system for a. m t ple cylinder 25 bustin engine comprising injector pump mech internal combustion engine, comprising a plurality of reciprocating inJector pumps for supplying fuel to the cylinders ofsaid engine, means 'for controlling the fuel displacement per-stroke offsaid pumps, fluid motor means including an expansible chamber having a. movable wall for operating said capacity control means, valve means for controlling the pressure in said chamber, a passage for air flowing to said engine for, combustion purposes, means responsive to the rate oi' flow of air thru said passage for controlling-said ,valve means, throttle means for controlling the flow of air thru said passage,

and means eective when said throttle means is in a, predetermined rangeof positions'to move said displacement control means concurrently therewith and independently of said motor means. '7. A fuel .supply system for an internal combustion engine, comprising injector pump mechanism for supplying fuel to said engine, means for controlling the capacity of said pump mechanism, fluid motor means, a floating lever, means connecting said capacity control means and said motor means to spaced points on said lever, a passage for air flowing to said engine for combustion purposes, means responsive to the rate of flow of air thru said passage for controlling said motor means, throttle means for controlling the now of air thru said passage, and means connecting said throttle means to another point on said lever, so that'said capacity control means may be positioned thereby independently of said motor means.

8. A fuel supply system for an internal combustion engine, comprising injector pump mechanism for supplying fuel to said engine, means for controlling the capacity of said pump mechanism, fluid motor means, a floating lever, means connecting said capacity control means and said motor means to spaced points on said lever, a passage for air flowing to said engine for combustion purposes, means responsive to the rate of ow of air thru said passage for controlling said motor means, throttle means for controlling the flow of air thru said passage, and means op erative to connect said throttle means to another point on said lever when said throttle means is in a range of positions near its closed position, so that said capacity control ymeans is then p anism for supplying fuel to said engine, means for controlling'the capacity of said pump mechanlsm, uid motor means, a floating lever, means connecting said capacity control means and said motor means to spaced points on said lever, a

passage for air flowing to said engine for combustion purposes, means responsive to the rate of flow of air thru said passage for controlling said motor means, throttle means for controlling the flow of air thru said passage, cam means connected to said throttle means for concurrent movement therewith, and follower means for'said cam means for transmitting motion to another point on said lever, said cam and follower means being effective to move said` lever when said throttle means is in a range of positions adjacent itsclosed position, so that said capacity, control independently of said motor means.

l0. A fuel supply system for an internal commeans is then positioned by said throttlev meansl anism for supplying fuel to said engine, means for controlling the capacity of said pump mechanism, fluid motor means, a floating lever, means connecting said capacity control means to an intermediate point on said lever, means connect-y ing saidI motor means to one end of said lever, a passage for air flowing to said engine for combustion purposes, means responsive to the rate of flow of air thru said passage for controlling 35 said motor means, throttle means for controlling the Aflow of air thru said passage, a secondlever pivoted at one end and connected by a link to `the other end of said floating lever, means biasing said, second lever in a direction to increase the capacity of said pump mechanism, stop means for limiting the movement of said second lever by said biasing means, means responsive to the speed of said engine for moving said second lever against said biasing means, and cam means connected to said throttle means for moving said second lever against said biasing means when said throttle means is in a range of positions adjacent its closed position.

11. A fuel supply system for an internal combustion engine, comprising injector' pump mechanism for supplying fuel to said engine, means for controlling the capacity of said pump mech'- anism, iluid motor means, a floating lever, means connecting said capacity control means and said 5,', motor means to spaced points on said lever, a

passage for air flowing to said engine for combustion purposes, means responsive to the rate of ilow of air thru said passage for controlling said motor means, 'and means responsive to the 50,/ speed of said engine for positioning another point on said lever and thereby moving said capacity control means independently of the said motor means.

l2. A fuel ,supply system for an-internal com- 35 bustionengine, comprising pump mechanism for supplying fuel to said engine, means for varying the capacity. of said pump mechanism,l a floating lever, a connection between said capacity varying means and a central point on said lever, iluid motor means for positioning one end of said lever, means responsive to the power output of -said engine for controlling said fluid motor means, and means responsive to the speed of said engine for positioning the opposite end of said lever.v A

i3. A fuel supply system for an internal combustion engine, comprising pump mechanism for supplying fuel to said engine, means for varying the capacity of said pump mechanism, s, floating lever, a connection between said capacity -varying means and a central pointcn said leverI iiuid motor means for positioning onev end of said lever, means responsive to the power output of` sive to the speed of said engine associated with said other end of said lever and effective to position said other endwhen the speed exceeds a predetermined value regardless of said manually operable means.

14. A fuel supply system for an internal combustion engine, comprising pump mechanism for supplying fuel to said engine, means for ying the capacity oi said pump mechanism, floating lever means, a connection between said capacity varying means and a central point on said lever means, uid motor means for positioning one end-of said lever means, means responsive to the power output of said engine for'controlling said uid motor means, a manually operable element positioned adjacent the other end of said lever means, spring means biasing said other end into engagement with said element so that said other end is positioned by said element, 4means responsive to the speed of said engine and associated with said other end of said lever means and effective when said speed exceeds a predetermined value to move said other end of said lever means out of engagement with said manually operable element so that the position oi said other end is thenkdetermined by said speed resmnsive means and said spring means.