US2400413A

US2400413A - Fuel proportioning device

Info

Publication number: US2400413A
Application number: US334393A
Authority: US
Inventors: Donald S Hersey
Original assignee: United Aircraft Corp
Current assignee: Raytheon Technologies Corp
Priority date: 1940-05-10
Filing date: 1940-05-10
Publication date: 1946-05-14
Anticipated expiration: 1963-05-14

Description

1946- D. S. l- |ERSEY 2,400,413 FUEL PROPORTIQNING DEVICE 7 Q Filed llay 10, 1940 Sheets-sheaf. 1

' mvamdn mall {Margy BY ATTORNEY D. s. H ERSEY' FUEL PROPORTIONING DEVICE May 14, 1946. 2,400,413

Filed May 10, 1940 2 Sheets-Sheet 2 INVENTOR ATTORNEY may be resorted t6 without in anyway f 1 is a sectional view Patented May 14, 1946 FUEL rnoron'rronmc' DEVICE Donald -S. Hersey, West Hartford, Conn., assignor to United Aircraft Corporation, East Hartford, Conn., a corporation of Delaware Application May 10, 1940, Serial No. 334,393

13 Claims. (Cl. 123-140) This invention relates to improvements in gas testing devices and has particular reference to an improved device for continuously testing the density of the,intake air supplied to an internal combustion engine and proportioning the engine fuel supply in accordance with the engine speed and density of the intake air. x

An object of the invention resides in the provision of a simplified and sensitive testing device operative to control another device, such as an density of engine intake air at each engine speed.

A further object resides in the provision of means for continuously and accurately detecting the density of engine intake air at all engine speeds within the operative range.

A still further object resides in the provision of improved means for continuously sampling en-- gine intake air and-accurately detecting the density of such air at all speeds within-the operative speed range of the engine and utilizing the den.-

sity indicationfor controlling the fuel supply to g the engine.

4 engine fuel supply means, in accordance with the.

A still further object is the provision of a device for properly proportioning the fuel and air fed to an engine. Y

Other objects and advantages will be more particularly pointed out hereinafter or will become apparent as the description proceeds. I

In the accompanying drawings in which like reference numerals are used to designate similar parts throughout, there is illustrated a suitable mechanical embodiment for the purpose of disclosing the invention. The drawings, however, are for the purpose of illustration only and are not to be taken as limiting 'the' invention as it will be apparent to those skilled in the art thatvarious changes in the illustrated construction exceedin the scope of the invention.

In the drawings,

pling and density detecting device constructed according to the invention, and

Fig. 2 is a somewhat schematic view, partly in section, ofan engine fuel supply mechanism and control therefor adapted to be operated bythe density detecting apparatus illustrated in Fig. 1,

Referrlng to the drawings in detail, the numeral I. generally indicates an engine intake air. duct which may be some part of the airscoop i2 shown in Fig. 2, the supercharger intake l4 or the diffuser II on the outlet side of the supercharger, as the device will operate" with equal facility on either side of the supercharger provided through. an air samit isproperly adjusted for the particular location.

A variablespeed variable capacity pump, generally indicated at l8, has one side thereof connected with the duct" by the conduit 20 and the opposite side connected with the duct through the conduits 22 and 24 and chamber 28 containing the fixed air orifice 28 provided in a diaphragm' 30 extending transversely of the-chamber and intercepting the airflow between the conduits 22 and 24. One side of the pump will be an intake side and the other an outlet side depending upon the direction of rotation of the pump rotor but.

it is not material to the operation of the device whether the chamber 28 is connected to the pump inletor the pump outlet so long as the

conduits

32 and 34 leading from the chamber upon opposite sides of the diaphragm 30 are properly connected with the indicating or control device which the density detecting apparatus is to operate.

The pump l8 includes a rotor 38 rotatable in fixed hearings in the casing 38 and driven by suitable means, such as the

spur gears

40 and 42, one of which is driven from an engine drive shaft 44. The rotor carries a plurality of movv able radial vanes ,46 which rotate in a movable annular cage 48 provided at opposite sides with slots 50 and 52 facing the inlet and outlet apertures of the casing 38. The vanes 46 are held in contact with the inner surface of the cage by suitable means such as the loose roller 54 disposed between the inner ends of the vanes, and a casing liner 56 may be disposed between the cage 48 and the casing 38. The cage 48 maybe moved by means of a reciprocable shaft 58 one end of which is connected to the cage and the other end of which is connected to a thrust bearing 60 disposed between the flyballs 62' and the speeder spring of a centrifugalgovernor 85. The fly balls 82 may be mounted on a rotatable member 88 driven by suitable means such as the beveled gears 68 and HI driven from the shaft 44. If desired, the governor may be adjusted by changing the loading on the speeder spring by some suitable means such as the adjustable abutment 12 and pinion '14 in a manner well known to the art. The maximum capacity of the pump may be regulated by a suitable adjustable stop for the cage 48, such' as the set screw is which projects through the bottom of the casing 30 and conance with engine speed. As the cage is moved upwardly, as viewed in Fig. 1, incident to an increase in engine speed the pump chamber below the rotor 36 will be reduced and a pump chamber will be provided above the rotor which will move the air in the opposite direction. If the cage were moved up to a position in which it was coaxial with the rotor, in which case the two pump chambers would be equal, the capacity of the pump would be reduced to zero since the air through the upper part of the rotor would move in one direction as fast as the air through the lower part moved it in the opposite direction. The adjustment is such, however, that the displacement of the pump is correctly proportioned to engine speed, over the operative speed range of the engine, so that as the speed of the pump increases its displacement per revolution will be correspondingly decreased, and vice versa. The speed and displacement of the pump are so proportioned that the total volume of air passed by the pump in a unit of time will remain substantially constant. As indicated above the displacement per 7 and is connected with the flexible diaphragms.

revolution of the pump I8 increases with a decrease in the number of revolutions per minute. In order to place a limit on the size of-the pump required a certain minimum pump speed, such as that corresponding to the normal engine idling speed, may be selected as the one to determine the size of the pump.

' The air passing through the pump I8 is passed through the fixed orifice 28 in the chamber 26. Since it requires a definite pressure head to force the air through the orifice, the orifice will create a pressure differential between the two portions of the chamber 26 on opposite sides of the diaphragm 30. With air flowing through a ,fixed orifice at a fixed volumetric flow rate, the pressure head across the orifice is a linear function of the air density. Since the volumetric flow rate through the orifice 28 is constant over the entire operating range as described above, the pressure differential will always be directly proportional to the density of the air flowing through the orifice. Thus, the pressure difference between the two portions of the chamber 26 connected with the

conduits

32 and 34 respectively will constitute an accurate indication of the density of the engine intake air and this pressure differential may be utilized for various purposes such as indicating the intake air density or controlling some apparatus in accordance with the density variations of the intake air.

Fig. 2 illustrates one manner in which the pressure difference between the

conduits

32 and 34 may be utilized to control the engine fuel supply in accordance withthe intake air density and may also, if desired, continuously-indicate the intake air density.

In the arrangement shown in Fig. 2 a fuel nozzle I8, is operatively associated with the engine supercharger intake I4 and is connected with a variable capacity fuel pump, generally indicated at 80, by suitable conduit or channel 82, the intake side of the pump being connected by a suitable conduit 84 with a fuel source such as the gasoline tank of a vehicle.

The pump 80 may be generally similar to the pump I8'and may have a rotor 86 which is rotatable in the casing 88 and carries a plurality of radially movable vanes 90 in a movable annular cage 92, the vanes being held in operative positions by means of a loose roller 94 disposed between the inner ends of the vanes. The cage is provided with oppositely disposed slots one of which, as indicated at 06, faces the pump outlet port and the other, as indicated at 90, faces the pump inlet port. The rotor 86 is operatively connected with an engine drive shaft and is driven at engine speed or at some fraction or multiple thereof. The movable cage 02 is connected at one side between the

apertures

96 and 98 with a stem I00 which passes through a chamber I02 With this arrangement the pressure differential created in the chamber 26 by the flow of air through the orifice 20 is transferred to the opposite end portions of the chamber I02 and acts on the transverse diaphragm I06 to move the stem I00. The stem I00 moves the cage 92 to vary the capacity of the pump 00 by varying the ratio of the pump chambers on opposite sides of the rotor 06.

Since the pump is always driven at some rate in proportion to the speed of the engine, without a density correction it would always maintain a fuel supply in proportion to engine speed. With the above described density responsive apparatus, however, it will maintain a fuel supply which is proportional to engine speed and to the density of the engine intake air thereby maintaining a constant air fuel ratio for the engine or an air fuel ratio which is varied according to definite predetermined functions.

The mass of air, or weight of air per unit of time, flowing to an engine is the mathematical product of the cylinder volume of the engine multiplied by the engine speed, the density of the air at the engine intake ports and by a correction factor known as the volumetric efilciency of the engine.

The mass of fuel flowing or weight of fuel supplied to the engine per unit of time, is the mathematical product ofthe fuel pump volume multiplied by the fuel density and the pump speed, the pump speed being equal to engine speed times the ratio of the drive between the engine and the pump- The mixture ratio of the fuel and air supplied to the engine is thus equal to the product of the pump volume, pump speed and fuel density divided by the product of engine cylinder volume,

engine speed, intake air density and volumetric efllciency of the engine. Since the fuel density and cylinder volume are both substantially constant, the required fuel pump volume for a given fuel to air ratio becomes a function of the product of the intake air density and the volumetric efficiency of the engine cylinders. The volumetric efliciency of the engine cylinders is primarily a function of engine speed, the other factors effecting this value being of negligible importance, so that the required fuel pump volume for any given engine speed is directly proportional to the product of the density of the air at the cylinder intake ports and a factor which is a direct function of engine speed.

The fly ball governor 65,'controlling the volume of the variable displacement pump It can be arranged to over-control or under-control the proportion to the pump speed.

ratio of the displacement of this pump to pump speed in a. manner such that the pressure head across the orifice 28 is not directly proportional to the density of the air flowing through the ori-' fice but instead to the product of air density and a function of engine speed, which function can be made directly proportional to the efiect of the volumetric efiiciency of. the engine on the mass airflow at all engine speeds within a given range. If the fuel pump volume is then made directly proportional to the corrected pressure head across the orifice 28, as shown in Fig. 2, a desired fixed ratio of fuel to intake air can be maintained over the entire above mentioned range.

The indicated variation in the control of the pump M by the governor 65 can be accomplished in various ways such as, by interposing a cam mechanism between the flyballs 62 and the opposing spring 64 or by selecting for the spring 64 a spring having a spring rate which varies in the proper amount with compression of the spring.

If desired,avisual density indicator H4 may be connected to the conduits 32 and 3! by suitable means such as the conduits HS and III to ing the pressure differential and thereby the density of the fluid in the conduit.

3. A fluid sampling and density detecting device for intake air for an engine comprising, a variable displacement variable speed pump driven by the engine and means connecting both sides of said pump to an-intake air conduit for continuously withdrawing air from one location in said conduit and returning the air to said conduit at provide a continuous indication of the density fuel supply of an internal combustion engine have been hereinabove described and illustrated in the. accompanying drawings for the purpase of disclosing the invention, it is to be understood that the invention is not limitedto the particular embodiment so described and illustrated but that such changes in the size, shape and arrangement of the various parts may beresorted to as come withinthe scope of the sub- .ioined claims.

- Reference is'made to my copending applications Serial Nos. 311,153 (filed Dec. 27, 1939), and 370,160 (filed December 14, 1940),,which show and claim subject matter shown but not claimed in this application.. I 7

Having now described the invention so that others skilled in the art may clearly understand the same, what it is desired to secure by Letters Patent is as follows:

1. In an internal combustion engine operating under variable speed and load conditions, means for detecting density variations in engine intake air comprising, an engine intake air conduit, a variable displacement pump driven by said engine and means connecting both sides of said "pump with said conduit, a restricted orifice in said connecting means between one side of said pump and said conduit, a pair of conduits connected respectively with the spaces at the opposite sides of said orifice for transferring the pressure diflerential across said orifice to an indicating or control apparatus, and means for varying the displacement of said pump in inverse v 2. An air sampling and .density detecting device for use with a variable speed motor comprising with oppositesides of the orifice for measur a diiferent location, a speed responsive governor also driven by the engine and varying the dis placement of said pump to maintain the volumetric flow rate therethrough substantially constant, a chamber constituting a portion of the connecting means between one side of said pump andsaid conduit, a fixed orifice in said chamber so arranged that all of the fluid passing through said pump is constrained to pass through said orifice, and means communicating with the chamber at opposite sides of said orifice and connected to an indicating or control device.

4. An air sampling and densitydetecting device for intake airvfor an engine comprising, a variable displacement variable speed pump driven by the engine and means connecting both sides of 'said pump to an intake air conduit for continuously withdrawing air from one location in said conduit and returning the air to said conduit at a diiferent location, a speed responsive governor also driven by the engine and varying the capacity of said pump to maintain the volumetric flow rate thereof substantially constant, a chamber constituting a portion of the connecting means between one side of said pump and said conduit,

ferent location, an engine driven speed responsive governor operatively connected with said pump to maintain the volumetric flow rate thereof substantially constant, a chamber constituting a portion of the connection between one side of said pump and saidconduit, a partition in said cham ber transverse to the airflow therethrough dividing said chamber into two parts, an orifice in said partition, a variable capacity fuel pump for said engine, pneumatically actuated means'for regulating the capacity of said fuel pump, and means connecting the spaces in 1 said chamber at. op-' posite sides of said partition with said pneumatically actuated means. v

6. In combination with an engine having an air intake duct and a fuel supply, means for proportioning the amount of fuel supplied to"said engine to the mass of intake air flowing comprising, a variable displacement pump driven by said engine and connected at both sides to said air intake duct at spaced apart locations, an engine "driven speed responsive governor operatively connected with said pump to maintain the volumetric constituting a portion '01 the connection between one side of said pump and said air duct, a partition in said chamber transverse to the airflow therethrough, an orifice'in' said artition, a vari able capacity engine driven fuel pump, pneumatically actuated means for regulating the capacity of said fuel pump, and means connecting the spaces within said chamber at opposite sides of said partition with said regulating means.

7. An air sampling device for engine intake air comprising, a variable displacement engine driven pump connected at both sides to an intake air conduit for continuously withdrawing air from and returning the air to said conduit, an engine driven speed responsive governor including centrifugally actuated fiyballs and a speeder spring operatively connected with said pump to maintain the volumetric flow rate through said pump substantially constant at different engine speeds, said sp'eeder spring being designed to modify said substantially constant volumetric flow rate in accordance with the variations in the volumetric eificiency of said engine.

8. An air sampling and measuring device for intake air'for an engine comprising, a variable displacement pump driven by the engine and means connecting both sides of'said pum to an intake air duct for continuously withdrawing air from one location in said duct and returning the air to said duct at a difierent location, a speed .responsive governor also driven by the engine and operatively connected with said'pump and constructed and arranged so that it will vary the volumetric flow rate through the pump as a function of the engine volumetric efficiency, a cham:

ber constituting a portion of the connecting means between one side of said pump and said duct, and a diaphragm in said chamber having an orifice therein, fluid pressure connections extending from said chamber, one on each side of said diaphragm, .and means connected thereto for determining the pressure differential on opposite sides of the diaphragm.

9. An air sampling and measuring device for engine intake air comprising, a variable displacement engine driven pump, means connecting both sides of said pump to an intake air conduit for continuously withdrawing air from one location in said conduit and returning the air to said conduit at a difierent location, an engine driven speed responsive governor having a speeder sprin to said duct at a different location, an engine driven speed responsive governor operatively connected with said pump, a chamber constituting a portion of the connection between one side of said pump and said duct, a diaphragm, having an orifice therein, in'said chamber, said governor constructed and arranged to modify the volumetric flow rate of air through said orifice as a function of the volumetric efficiency of the engine, a variable capacity engine driven fuel pump, pneumatically actuated means for regulating the capacity of said fuel pump, and means neumatically connecting the spaces within "laid chamber at opposite sides of said partition with said regulating means.

11. In a density responsive device connected with the air supply line of an internal combustion engine, mechanism comprising, a diaphragm having a fixed area orifice therein, variable speed adjustable displacement pump means urging a. sample quantity of gas from said supply line through said orifice at a volumetric flow rate which is a function of the volumetric efliciency of the engine and means communicating with opposite sides of said diaphragm for transmitting the pressure difference on opposite sides of said diaphragm to an indicating or control apparatus.

12; In an internal combustion engine having I an air intake system variable delivery means for injecting fuel into the air in said system, a conduit connected with said system downstream relative to said fuel injecting means, said conduit having a restricted passage through which the intake mixture is passed, means for maintaining a flow rate through the restricted passage such that the pressure differential across the restriction varies in accordance with change in mixture density, and means actuated by said pressure differential for varying the delivery of said fuel and operatively connected with said pump. said speeder spring having a variable spring rate proportioned to modify the volumetric flow rate through said pump in accordance with variations in the volumetric efficiency of said engine, a restriction in said means connecting said ump and said conduit, and means for transmitting the pressure diiference at the opposite sides of said restriction to an indicating or control apparatus.

10. An air sampling device for engine intake air comprising, a variable displacement engine driven pump connected at both sides to an intake air duct for continuously withdrawing air from one location in said duct and returning the air injecting means to maintain the correct proportion of fuel to air for different intake air densities.

13. In a charge forming apparatus for an internal combustion engine provided with a supercharger for engine intake air, an engine driven adjustable displacement fuel pump, an air sampling device connected with the outlet of said supercharger for continuously passing a sample quantity of air from said supercharger outlet through a fixed area restriction and having means for maintaining a constant volumetric flow of said air through said restriction to provide across said restriction a pressure head proportional to the density of said intake air, and means actuated by said pressure head and operatively connected with said fuel pump for varying the quantity of fuel delivered by said pump in accordance with variations in intake air density to maintain a substantially constant proportion between the weight of intake air and the weight offuel delivered to said engine in the same time interval.

DONALD S. HERSEY.