US2793632A - Regulator and control device for an internal combustion aircraft engine - Google Patents

Description

May 28, 1957 D. J. DESCHAMPS 2,793,632

REGULATOR AND CONTROL DEVICE FOR AN INTERNAL COMBUSTION AIRCRAFT ENGINE Original Filed July 51, 1940 CCELERATlNG PUMP TO ENGINE l N VE NTOR DEE/HE'J. UEELHHNPS ATTORNEY REGULATOR AND CONTRGL DEVICE FOR AN INTERNAL COMBUSTION AIRCRAFT ENGINE Desire J. Deschamps, San Fernando, Calif assignor to Bendix. AviationCorporation, South Bend, Ind, a corporationof Delaware 4 5 Claims. (CL 123--1l)) This invention relates to a regulator foran internal combustion aircraft engine and more particularly to im- 'provements in aregulator of the type disclosed in-Mock 'U. S. PatentNo.2,'390,658, granted December 11, 1945,

and..Mock U. S. Patent .No. 2,447,267, granted August 17, 1948, and assigned to .Bendix AviationCorporation andto improvements in regulators designed for general use. p

, The present application is a division of the copending application Serial No. 675,981, filed June 11, 1946, by Desirefl. Deschamps, now Patent No. 2,641,237, issued "June 9,1953, asa continuation of application Serial No.

348,925, filed July 31, 1940, now abandoned, and as- .signed to .Bendix Aviation Corporation.

An object of the invention is to provide a regulator including'a novel compactservo valve and piston arrangement in which the servo valve is slidably mounted within avalve member on which the piston is in turn slitlably' mounted.

Another object of the invention is to provide a novel compact control mechanism, including a valve member, a cup shaped piston slidably mounted on said valve member, a main control valve slidably mounted in the valve-member to control the position of the piston,zand .a difierentialapressure responsive membrane operatively -connected to .and in axial alignment with the main con- ..trol valve.

Another object of the invention is to provide a novel regulator-in which the aforenoted control valve is operatively connected by a rod to a differential pressure responsive membrane mounted within the casing of said regulator, said casing having a pair of fluid filled chambers formed within the casing, a pair of auxiliary memibraneshaving equal efiective areas aflixed to said rod,

oneof said auxiliary membranes forming a wall for one of said ,chambers and the other auxiliary membrane forming awall for the other chamber, each of said auxiliary membranes operably connectedto said valve rod andarranged'in, spaced relation to said diflerential pressure responsive membrane of greater effective area, and

a conduit connectingthe one chamber with the other for applying opposing balancing pressures to said auxiliary membranes.

,Another object of the invention is to provide a novel regulator-having a plurality of such fluid pressure responsive membranes'with auxiliary pressure balancing membranesat opposite sides of each of said pressure responsive membranes.

Another object of theinvention is to provide a novel regulator combining in a compact assemblage the features aforenoted.

The above and other objects and features of the inventionyvill appear more fully hereinafter from a consideration of the following description taken in connection with the accompanying drawing wherein one emk'bodiment'of the invention is illustratedby Way of example.

7 2,793,632 Patented May 28, 195.7

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, 2 lnthe drawing there is shown a conduit 11 adapted to supply air flowing in the direction of the arrows to the combustion spaces of an internal combustion engine,

the amount of air supplied being controllable by an operator-operative throttle means or by manual operation of the throttle indicated at 12, said throttle being shiftable about its central pivot shaft which extends to the exterior of the conduit and is adapted to be turned through'a suitablelinkage, not shown, towhich the pilot or other operator of the engine willhaveaccess. 7

Fuel maybe injected or otherwise supplied to the combustion spaces oftheengine by suitable connections, not shown, leadingfrom the. outlet pipe 14 of the fuel injection or fuel delivery pump "16, the latter having a drive shaft .17 rotatable by and .in timed relationship with the crankshaftor other rotatable part of the engine, not shown. Fuel may be supplied to the pump 16 by a fuel conduit 18 leading (either directly, or by way of a transfer pump, not shown) from the tank 19 constituting the fuel source. The pump 16 may be of any desired type but is shown herein as being of a construction embodying a novel type of variable delivery control, as, described inv greater detail and claimed in U. S. Patent No. 2,243,374, granted May 27, 1941, toDesire J. Deschamps and assigned to Bendix Aviation Corporation.

As indicated at 21, the 'novel variable delivery mechanism may include a lever extending from the pump andadaptedto be turned about its rockshaft by movement of the linkage 22 connecting the lever 21 to an air fuel mixture regulator forming the ,subject matter of the present application.

Regulator As shown in.the drawing, there is provided the novel regulator 23 operatively connected to the linkage 22 'by :a rod 24 adapted to be reciprocated by the pressure 'of a fluid acting upon 'a' cup-shapedpiston 25 which abuts anenlargedend 26 ofthetrod 24.

As shown, the portion 26 of rod 24 is affixedto a cylindrical extension 27 that is movable toward a stationary abutment plate 28, and serves to enclose a coiled compression spring 29., A flange. 27a is provided on cylinder 27 as an alternative operator-operative means for actuation of the variable delivery mechanism.

The piston 25 is'subject toxthecontrol not only of the spring 29,'abovereferred to,.but also of the fluid pressure supplying'and control means of which the essential parts include, a'meteringunit 33 corresponding in general to the metering unit similarly designated in the Mock U. S. Patent No. 2,447,267. The metering unit 33 of the present invention embodies certain improvements over 'the metering unit disclosed in the latter patent as will be apparent. The metering unit 33 operates a valve 34 controlling the supply of fluid OILOil under pressure to act upon the piston 25. The metering unit 33 senses air and'fuel flow to ,theengine so .as tocontrol the piston 25 and thus the fuel tothe engine through the fuel supply pump 16 in response thereto, as will be explained hereinafter.

In the drawing an air conduit is shown as including a venturi section 35 at apoint anterior tov the throttle 12,

and at a pointslightly inadvance of the venturi section 35 there is provided a tube 37 adapted to open into the 'air streampassingthrough the conduit, said tube extending into and opening at its other end into a chamber of the metering unit 33 as will be furtherexplained. Due to the location of the entering end of this tube 37, it will be apparent that the tube is subjected to the pressure of the air entering the venturi section 35 of theconduit. A smaller venturi tube 41) is positioned in theconduitl'l between the tube 37 and the throat of themainfventurisection 35, and atube 41 leads from the throat section of the smaller venturi tube 40 to another chamber of the metering unit 33 to be further described.

The metering unit 33 has a casing 42 which is-divided into four pressure chambers 43, '44, 45 and 46, the separation of the chamber from each other and from the external atmosphere being assured by the provision of applicants novel arrangement of the sealing diaphragms or auxiliary balancing membranes 47, 48, 49 and 50 having equal effective areas. In addition to the diaphragms 47-50 there are two relatively larger main control membranes or diaphragms 53 and 54 which separate the chambers 43 and 44 and the chambers 45 and 46, respectively.

Each of said diaphragms 47, 48, 49, 50, 53 and 54 are fastened at itsouter periphery in the casing 42 of the unit, and at its central portion each of the diaphragms is afiixed to a control rod 55.

The auxiliary membrane 47 forms a flexible wall sealingthe, chamber 43 from a chamber 56 defined. by a re- ,cess formed in the casing 42 and cap 57 removably 42 to the respective chambers 58 and 56. The cap 57 may be removed for adjusting the selected air-fuel mixture setting of the regulator 23, as will be hereinafter explained, and the conduit 62 provides means whereby the fluid or air filling the chambers 56, 58 and 59 will apply an equal and balanced pressure to the respective membranes 47, 48, 49 and 50. s

It will be seen then that through the pressure balancing conduit or channel 62 the fluid pressure applied in chamber 56 to the left of the membrane 47 will be balanced by a like fluid pressure applied in chamber 58 to theright of the-membrane 48, similarly the fluid pressure in chamber 58 applied to the left of membrane 49 will be balanced by a like fluid pressure applied in chamber 59 to the right of membrane 50. Thus since the auxiliary membranes 47, 48, 49 and 50 have equal effective areas the control rod55 will be balanced against changes in the ambientatmospheric pressure and will be unaffected thereby. Similarly, fluid pressures in chambers 43, 44,45 and 46 acting upon the auxiliary membranes 47, 48, 49 and 50, respectively, will be counterbalanced by such pressures acting in an opposite sense upon the main control membranes or diaphragms 53 and 54 having a greater effective area than the auxiliary membranes 47-50. Thus, the applicants novel arrangement of the diaphragms 47-50 provides a balanced mounting for the control rod 55. a r

The auxiliary diaphragms 47-50 and main control diaphragms 53 and 54 are shown as formed with an annular groove or depression to permit relatively free axial movement of the control rod 55 in response to pressure differences acting on opposite sides of the main control diaphragms 53 and -54.- I

The chamber .43 as shown in the drawing receives one end of the conduit 41 heretofore described, and the chamber 44'reccives one end of the conduit- 37; consequently the pressure difference between the chambers 43 and 44 will coincide with the pressure difference prevailing between the two points of entrance of air to the respective tubes, and said difference in pressure will vary with every change in mass airflow through the conduit 11. a

The fuel conduit is also provided with a'venturi section'from the throat of -which leads a tube 61 terminating as shown in the chamber 46 of the metering unit 33, while a-seco'nd tube 6Z'leads from a pointslightly in advance of the venturi section of the fuel conduit to terminate within the chamber 45 of the metering unit 33. From this it follows that the pressure differences at the venturi section of the fuel supply conduit will produce a corresponding pressure difference on the opposite sides of the diaphragm 54 which, in conjunction with the diaphragm 53 and a coiled compression spring 65, will control the position of the control rod 55. The spring 65 acts through an adjustable nut 66 to bias the rod 55 to the left as viewed in the drawing so as to control the reciprocating action and position of the control rod 55 to which the said diaphragm are secured. This rod 55 is shown in axial alignment with and connecting through a swivel coupling 70 to the control valve 34 which governs communication between a pressure fluid supplying passage 72 on the one hand, and two associated passages 73 and 74 on the other, the passage 73 being a discharge passage, returns the oil to the oil sump of the engine. The other outlet passage 74 leads to a chamber 75 of annular shape, bounded at one side by a valve member 76 in which the valve 34 is slidably mounted and at the other side by the working face of the cup-shaped piston 25 slidably mounted on the valve member 76.

The valve member 76 projects from the casing or housing 42 and a feature of the invention is the compact assemblage of the servo valve 34 and piston 25 in which the valve 34 is slidably mounted in the valve member 76 on which in turn is slidably mounted the cup-shaped piston 25. As shown, there is further provided a compact assemblage in which the control rod.55, actuating diaphragms 53 and 54 and coil spring 65 are in axial alignment with the servo valve 34 and cup-shaped piston 25.

The setting of the spring 65 may be suitably adjusted by removal of the cover cap 57 and adjustment of the calibrating nut 66 to vary the force exerted by the spring 65 and thus the selected air-fuel mixture setting of the regulator 23, while the pressure balancing channel 62 serves to provide equal balancing pressures to the auxiliary balancing memberanes 47-50, as heretofore explained.

Starting of the engine As described and claimed in the copending application Serial No. 675,981, the piston 25 is controlled in such manner as to cause it to move automatically to full rich .position when the pilot stops the engine.

the biasing force of spring 65, opening port 74 and allowing oil from cylinder 77 to be forced 'into space 75,

moving piston 25 to the right,to the full capacity setting, thereby making the setting of the pump correct for the next start. Since the force on piston 25 must be great enough to fully compress spring 29, it is obvious that a reservoir of liquid under pressure must be available to assert such a force upon the piston 25, notwithstanding the falling off in engine oil pressure that accompanies the stopping of the engine. Cylinder 77, in cooperation with check valve 78, provides such a pressure reservoir.

Acceleration The mixture should momentarily be made richer when vthe pilot opens the air throttle briskly. With the control as described above, just the opposite would happen due to the lag inthe operation of the control. As

. described and claimed in the copending application Serial .No; 675,981 to offset this, advantage is taken of the very low pressure which exists in the intake manifoldahead "mix panacea of the .air throttle valve-12in providing for operation of the accelerating-pumpshown ati fii' Diaphragm L92 it functions as 28 inches with a naturally aspirated-engine and may be 42 or more in case of a supercharged engine. This low pressure underthese circumstances holds the diaphragm 92 against stop'93,"and"compressessprings 94. If the air throttle is quickly opened, the pressure immediately increases, relieving the suction in compartment 91, and the springs 94 push the diaphragm to the left, thereby forcing fuel out of compartment 96 until diaphragm 92 abuts stop 97. This fuel leaves through check valve 98 and enters compartment 46, by way of conduit 99. To get this result, the passage 61 connecting compartment 46 with the venturi throat in fuel conduit 18 should be relatively small.

When the throttle is again closed, the reduced pressure in 91 will permit return of diaphragm 92 to the right, allowing fuel to enter 96 at slow rate, through conduit 99 and narrow passage 95. Passage 95 is made relatively small to prevent a leaning of the mixture too speedily during the period of deceleration, thus preventing possible stalling.

Manual (or barometric) adjustment of the mixture A further feature of the invention resides in the provision of an air diaphragm 53 having a greater effective area than the fuel diaphragm 54 and a. little larger than needed to balance the force acting against fuel diaphragm 54 under selected fuel-air mixture conditions, together with a calibrated passage 101 putting compartments 43 and 44 in communication with each other in order to reduce the differential pressure in these two compartments in such a way that the force derived normally from the large air diaphrgam 53 just balances the fuel diaphragm 54 of lesser effective area under the selected conditions.

As shown, this passage 101 has a valve 162 which normally allows restricted flow from 43 to 44. If, now, this valve 102 is closed the pressure difference between 43 and 44 and the control valve 34 will immediately increase the output of the fuel injection pump 16, although the air flow entering the engine has not increased. Thus the mixture becomes richer. Conversely, opening the valve 102 beyond its normal setting will correspondingly lean out the mixture.

A similar arrangement on the fuel diaphragm unit could give corresponding results, but may not always be advisable because of the difliculty of sealing a valve which would pass fuel instead of air.

The valve 102 could also be operated by means of an evacuated bellows similar to the one disclosed in the Mock U. S. Patent No. 2,447,267 (above referred to) to correct for changes in temperature and barometric pressure, thus acting as an altitude correcting device to vary the richness of the mixture.

Although only one embodiment of the invention has been illustrated and described, various changes in the form and relative arrangements of the parts may be made to suit requirements.

What is claimed is:

1. For use in controlling the fuel-air ratio of an aircraft engine; a control device comprising, in combination, a housing having chamber means formed therein, differential fluid pressure responsive means mounted in said chamber means and adapted to be connected so as to sense the fuel-air ratio of said engine, a member projecting from said housing, a control valve slidably mounted within said membenraficup-shapedpiston slidablyrmounted on said projecting member, and said meinbertprojecting into said cup-shaped member and having formed therein first conduit means for directing a fluid pressure medium into the cup-shaped piston toefiect movement of said piston in one direction on saidjprojecting member, said .first conduit means being controlled ,by. said valve, .said projecting. member havingformed therein second conduit means-controlled 'by said valve for draining the fluid pressure medium from withinthe cup-shaped piston to the exterior, spring means biasing said cup-shaped piston in another direction in" opposition to said fluid pressure medium within thecup-shaped piston, and a control rod in axial alignment withand operably connecting said valve to said differential fluid pressure responsive means, and means operatively connected to said piston and adapted to be connected to a device to vary the fuelair ratio.

2. The combination defined by claim 1 in which the last mentioned connecting means includes a member slid ably mounted on said piston and biased into operative engagement with the piston by the spring means for operatively connecting the fuel-air ratio varying device to said piston, and operator-operative means for actuating said last mentioned member for independently adjusting said fuel-air ratio varying device.

3. A control device comprising, in combination, a valve member, a control valve slidably mounted within said valve member, a cup-shaped piston slidably mounted on said valve member, said cup-shaped piston having a closed end defining with an end of said valve member a fluid pressure chamber, said valve member having formed therein fluid pressure conduit means for connecting the fluid pressure chamber to a source of fluid pressure medium, other fluid conduit means for drainingfluid pressure medium from the pressure chamber, said control valve being movable to selectively connect said pressure chamber to one or the other of said conduit means for controlling operation of the piston, and spring means biasing said piston in opposition to the fluid pressure medium in said fluid pressure chamber.

4. A control device comprising, in combination, a valve member, a control valve slidably mounted within said valve member, a cup-shaped piston slidably mounted on said valve member, said cup-shaped piston having a closed end defining with an end of said valve member a fluid pressure chamber, said valve member having formed therein fluid pressure conduit means for connecting the fluid pressure chamber to a source of fluid pressure me dium, other fluid conduit means for draining fluid pressure medium from the pressure chamber, said control valve being movableto selectively connect said pressure chamber to one or the other of said conduit means for controlling operation of the piston, a cylindrical member slidably mounted on said piston, a spring biasing said cylindrical member into operative engagement with said piston, and means for actuating said cylindrical member independently of said piston.

5. A control device comprising, in combination, a valve member, a control valve slidably mounted within said valve member, a cup-shaped piston slidably mounted on said valve member, said cup-shaped piston having a closed end defining with an end of said valve member a fluid pressure chamber, said valve member having formed therein fluid pressure conduit means for connecting the fluid pressure chamber to a source of fluid pressure medium, other fluid conduit means for draining fluid pressure medium from the pressure chamber, said control valve being movable to selectively connect said pressure chamber to one or the other of said conduit means for controlling operation of the piston, a cylindrical member slidably mounted 'on said piston, a spring biasing said cylindrical member into operative engagement with said piston, an actuating rod operatively connected to the 'cylindrical member," and an operator-operative means connected to the cylindrical member for. actuation of the rod independently of the piston. l

References Cited in the file of this patent UNITED STATES PATENTS Simons June 14, 1910 Ebeling Mar. 2, 1915 Treat June 17, 1930 Campbell May 26, 1931 Wasson May 7, 1935 Dodson Apr. 26, 1938 Browne July 11, 1939

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