US2590575A - Fuel injector - Google Patents

Description

March 25,' 1952 G. M. ROGERS 2,590,575"

FUEL INJEcToR Filed Aug. 2, 1945 2 SHEETS- SHEET 1 K ATTORNEY 4 s n mwa 4 a MP0 H 6 22 9 J W 83 2 IM 7 f l.. 8 e i 8 .m O im l Q@ 65M Y B G. M. RQGERS `FUEL. INJECTOR March 25,

Filed A ug. 2, 1945 2 SHEETS-' SHEET 2 /80 INVENToR.

ATTORNEY Patented Mar. 25, 1952 UNITED STATES PATENT OFFICE FUEL INJECTOR Gardiner M. Rogers, Ithaca, N. Y.

Application August 2, 1945, Serial No. 608,588

(Cl. S-41) 13 Claims.

This invention pertains to the art of fuel injectors for internal-combustion engines, and is specifically directed to improvements in unitary fuel injectors of the jerk pump type such as are employed, for example, on General Motors type 7l engines.

An object of this invention is to improve the operating characteristics of fuel injectors for internal-combustion engines, and especially to improve injector operation consistently throughout the range of conditions encountered in use, whereby efficient combustion and engine opera.- tion is obtained at crankingI and idling speeds as also under load conditions.

Another object is directed to a fuel injector structure of the pump type wherein the pressure f 'z A further object is to improve the operating characteristics of fuel injectors whereby a more efficient fuel distribution to the engine is obtained.

Still another object is an improved structure whereby good atomization of the fuel injected is obtained at both'high and low operating speeds.

It is a further object to provide a fuel injector in which fuel leakage does not materially affect the quantity of fuel metered per stroke, thereby permitting greater manufacturing tolerances with consequent increase in interchangeability of parts.

Further objects and advantages of this invention, as well as its construction, arrangement and operation, will be apparent from the following description with the accompanying drawings, and from the accompanying claims. In the drawings Fig. 1 is a longitudinal sectional view of one form of an injector that embodies the invention,

Fig. 2 is a section taken on line 2-2 of Fig. 1,

Fig. 3 is a sectional View on line 3 3 of Fig. l,

Fig. 4 is a side elevation partly in section of a detail of the injector in Fig. 1,

Fig 5 is a detail elevation of the plunger of the injector in Fig. 1,

Fig. 6 is an enlarged developed prole view of the piston surface of the plunger in Fig. 5,

Fig. 7 is an enlarged detailed elevation of the 4piston embodied in the plunger in Fig. 5,

Fig. 8 is a sectional view, taken on line 3-8 of FigY,

Fig. `9 is a diagrammatic View that illustrates relationship between the plunger and the working barrel, and

Figs. 10 to 14 illustrate the sequence of operation of the piston in the pumping chamber during one stroke of the plunger.

The injector of the present invention is constructed to utilize the full capacity of its pump only at cranking and idling speeds, so that suffi# cient pressure for proper fuel atomization is maintained even at low operating speeds. As the speed of the engine is increased, surplus fuelis vented or spilled back into a reservoir through the use of a pressure-control valve, which operates to main adequate pressure on the fuel to in. sure proper atomization over the desired range of operating speeds. Thus, good fuel atomzation is maintained at the various operating speeds of the engine. Means are also provided to divide the quantity of fuel injected into a preliminary and main charge, which are fed to the engine in sequence and timed to insure efficient and smooth combustion.

Fig. 1 shows a section taken on the longitudinal centerplane of an injector that embodies the invention. The general form of this type of injector is the so-called jerk pump type similar to that employed, for example, in the General Motors series 7l diesel engine.

The disclosed injector comprises an outer housing or shell Il), provided with a cavity II, which terminates at its end in a shouldered bore I2 forming an opening to the exterior of the shell if! at its end. A nozzle E3 ts in the bore I2 and seats against the shoulder thereof as shown, the nozzle being extended through the bore I2 to project out of the end of shell I0. The nozzle I3 is provided with an orifice It preferably consisting of a plurality of orifice openings which spray the fuel that is forced through them under pressure. When the injector ismounted on an internalcombustion engine positioned for use in the manner of prior art practice, the exposed tip of the nozzle I3 including the orifice I4 projects into a cylinder of the engine to feed or deliver fue thereto.

The nozzle i3 is provided with the bore I5 that serves as a passage for fuel to the orifice I4, and the nozzle is provided with a counterbore that constitutes the chamber I6 which serves as a housing for a spring loaded valve consisting of the spring guide and stop pin Il, closure mem-'a ber i 8 and the spring I 9.

A spacer member-'20 also fits in the bore I2 against the nozzle I3 and has a central aperture or duct 2I terminating in an enlarged checkvalve chamber l0. A check valve 1I, in the form of a clover-leaf shaped disc, and with its edges notched accordingly, seats in the chamber 18. Check valve 1I permits the passage of fuel downward to the spray nozzle I3, but prevents reverse flow of the fuel in the event the closure member I8 leaks.

A base or abutment piece 23 is provided with a cylindrical plug 12 that fits in the bore I2 of the shell I8, and seats against the spacer member 28. The remainder of the abutment piece 23 projects into the cavity I I of the shell I8. The piece 23 is pierced lengthwise by a duct 22 that extends from an annular chamber or groove 13 in one end face of piece 23 to its opposite end where the duct 22 communicates with the check valve chamber 18 of the spacer piece 20. Sleeve member 24 seats or abuts against the end face of the base piece 23 that embodies the annular groove 13, and is disposed centrally of the cavity I I in the shell I0. The sleeve 24 is provided with a lengthwise duct 29 having the same radial disposition as the annular groove 13 with which it communicates.

The body or base 35 of the injector comprises the nipple 49 onto which the shell I8 is screwthreaded at 14 to close the cavity II, the gasket 52 being provided to make the closure fluidtight. As will be seen more fully hereinafter, the various components inside the shell I8 are held in proper operating positions relative to each other, in the manner illustrated in Fig. 1, by the shell I8 being attached to the nipple 49 of the body 35.

The sleeve member 24 forms the body of the pump, and as shown in Fig. 4 is generally cylindrical in shape, comprising a central cylindrical working barrel or pumping chamber 25. The plunger 31, Fig. l, provides the piston 38 of the pump. The body 35 of the injector comprises the bore 16 which is directed upwardly into nipple 49 coaxially with the threads 14, and accordingly the bore 16 isdisposed coaxially with the bore I2 when the shell I8 is attached to the body 35. One end of the sleeve 24 is reduced to provide a cylindrical plug concentric with the working barrel 25. The plug 15 its into the bore 16 and extends therein to the shoulder 36 which abuts against the end of the nipple 49 when the sleeve 24 is positioned in the housing of the shell I8 attached to the body 35. This construction positions the working barrel 25 centrally in the shell I8 concentrically with the bore 16, and it positions duct 29 in communication with the annular groove 13 of abutment piece 23. Lengthwise thrust of the abutment piece 23 against the end face 88, Fig. 4, of the sleeve 24, and thrust of the abutment shoulder 36 against the end of the nipple 49, operates to hold the pump of the sleeve 24 rigidly positioned in the housing of shell I8 screwed onto nipple 49. A dowel hole k18, Fig. 4, is formed in the wall of the plug 15, and receives the dowel or keying pin 11 that engages the keyway 19 in the bore 16 of nipple 49. thereby preventing rotation of the sleeve 24 in the housing of shell I8.

The cavity II constitutes a reservoir of fuel around the sleeve 24, and it is supplied from the chamber 5I in a manner similar to prior art practice. A set of ducts 58 extend from the chamber 5I to the reservoir II for circulation of fuel from the chamber 5I through the ducts 58 to and around the reservoir I I, and by this means the reservoir II is constantly supplied with fuel. Filters 53 prevent foreign particles that are nonfluid from entering the reservoir II, each lter 53 being backed by a compression spring 54 to hold it seated in place in the chamber 5I.

The piston 38 ts in the working barrel 25, and is operated therein by the lengthwise reciprocation of the plunger 31. The shank 81 of the plunger 31 extends away from the piston 38, and is projected out of the end of sleeve 24 that embodies the plug 15 and through the bore 16 of body 35 into position for its actuation by the pump operating mechanism.

The bore 88 extends into the body 35 from the direction opposite to and coaxial with the bore 16, both bores extending to the internal annular shoulder 41 between them. The shank 81 of the plunger 31 passes through the shoulder 41 and through the bore 88. The body 35 is provided with the external cylinder or collar 46, coaxial with the bore 88, and extending to the shoulder 48.

The sleeve 58 its in the bore 88, and at its one end has the inwardly directed shoulder 8I that nts around the shank 81 of the plunger 31. At its other end the sleeve 58 is provided with the outwardly directed ange or shoulder 82, which serves as a seat for one end of the compression spring 6I, the spring being disposed around the collar 46 of body 35 and bearing at its other end against the shoulder 48 of collar 46. The spring 6I thereby tends to actuate the sleeve 58 out of the bore 88 by pressing against flange 82. Sleeve 58 is provided with the longitudinal slot 83. Stop pin 59 is projected through the wall of collar 46 into the bore 88 of body 35 and into engagement with the slot 83 of sleeve 58. The stop pin 59 holds the sleeve 58 in the bore 80 against the action of the spring 6I tending to push the sleeve 58 out of bore.

The annular groove 44, Fig. 5, near the end of the shank 81 of plunger 31, is adapted to receive the horseshoe washer 56, Fig. l, that ts inside the sleeve 58. The spacer sleeve 84 iits around the shank 81 of the plunger 31 and inside the sleeve 58, and it extends from the internal shoulder 8| of the sleeve 58 on which it rests to the horseshoe washer '56 against which it bears. Under action of the spring 6 I, shoulder 8l of sleeve 58 is pressed against the horseshoe washer 56 with the spacer sleeve 84 between them, whereby the sleeve 58 is attached to the plunger 31 and the two of them move together.

To assemble the plunger 31 and the. sleeve 58, spacer sleeve 84 is positioned around the shank 81 of plunger 31 and against the shoulder 8I of the sleeve 58, which is actuated along the shank 81 of the plunger 31 towards the piston 38 until the annular slot 44 projects out of its end far enough for the horseshoe washer 56 to be positioned in slot 44. Now the sleeve 58 is pressed into the bore 88 against the tension of spring 6I until the pin 59 can be projected into the slot 83 of sleeve 58. When the spring 6I is now released to act, it presses the end of slot 83 against the pin 59, and presses the shoulder 8l of sleeve 58 against the horseshoe washer 56, thereby holding the elements assembled in the body 35 of the injector.

The abutment head 51 ts in the end of the sleeve 58 that embodies the flange 82, and it engages the end of the plunger shank 81. Abutment head 51 is held in position in sleeve 58 by the spring clip 68. The rocker arm 62 presses against the abutment head 51 and thereby actuates the plunger 31 opposed to spring 6I in the downward direction of Fig. 1, and by this means the piston 38 moves downwardly in working barrel 25 to perform its working or pumping stroke. The spring 6I actuates the plunger 31 in the opposite upwardly direction during the upward stroke of the rocker arm 62, and by this means the piston 38 moves upwardly in the working barrel 25 to perform its fuel intake stroke. The slot 83 is elongated to permit lengthwise reciprocation of the plunger and sleeve assembly 31-58 relative to pin 59 when the plunger 31 is reciprocated down and up in the manner described.

The pinion 55 ts in the cavity of the bore 16 of body 35, and is keyed to the shank 81 of the plunger 31 by means of the at 43 thereof. See

Fig. 5. The spacer sleeve 45, Fig. l, fits in the bore 16 and is positioned between the end of sleeve 24 and the pinion 55, whereby the pinion 55 is held adjacent to the internal shoulder 41 and is thus properly located within the body 35. The pinion 55 is properly positioned in the bore 16 when it and the internal components of the injector are housed in the manner described hereinbefore by the shell I being attached to the nipple 49. The rack 63 is geared to the pinion 55 and is operable in a manner similar to prior art practice to rotate the pinion, thereby adjustably rotating the plunger 31 to control the quantity of fuel supplied to the engine.

The sleeve 24 is transversely bored to provide a plurality of radially disposed holes that constitute the intake port 36, Fig. 3, through which fuel ows from the reservoir of cavity into the working barrel 25. The bore 21 is directed radially through the sleeve 24, and is extended beyond the bore of working barrel 25 to include the bore 28 on the opposite side, The bore 28 connects with the lengthwise duct 29 to provide a fuel passage out of the working barrel 25 that extends to and through the end face 88 of the sleeve 24. Bore 28 thus constitutes the feedl port of the pump. Bore 21 comprises a by-pass port for the passage of fuel from the working barrel 25 into the reservoir l I.

Fuel that flows out of the working barrel 25 through port 28 passes through lengthwise duct 29 and annular groove 13 into duct 22, from which it enters the check-valve chamber 10. The fuel is free to pass from chamber 10 into the duct 2| through the notches around the edge of the check-valve disc 1|. To enter the chamber I6 from duct 2| the fuel must be under sufiicient pressure to overcome the spring I9 and displace the closure member I8. The stop pin I1 is provided with a transverse notch, shown in dotted lines in Fig. l, through which fuel is enabled to pass from the chamber |6 into the passage I5, and from passage I the fuel is driven under pressure through orifice I4 into the engine.

A valve passage or duct 3| leads from the pumping chamber 25 to a ball valve recess 32. The duct 3| is a bore through the wall of the workingbarrel 25. The recess 32 is a counterbore exteriorly of the pump body 24 and is large enough to receive the ball 33, the recess 32 extending inwardly to a depth that is predetermined for the ball 33 to project out of the recess a predetermined amount. See Figs. 2 and 4. The port 3| constitutes a vent for the flow of Huid out of the working barrel 25 and the ball 33 constitutes a closure therefore.

' The ring or band 34 holds the hall 33 in closed position seated on the port 3|. A cylindrical groove V26 is turned in the exterior surface of the pump body 24 at the recess 32 to form a seat for the band 34, the groove 26 of the disclosed embodiment being concentric with the working barrel 25. The flow of fluid out of the working barrel 25 through the vent 3| is resisted by the band 34 tending to hold the ball 33 seated. The fuel in the working barrel 25 is stressed under pressure by operation of the pump 38--25, and when this pressure reaches a predetermined magnitude sufficient to overcome lresistance of the band 34, the closure 33 is lifted from the port 3| and fuel is thus vented out of the working barrel 25. The port 3|, ball closure 33 and band 34 therefore constitute a valve which operates to control the operating pressure in the working barrel 25.

The bore 25 is considerably larger, for an engine of commensurate size, than the bore of prior art positive-displacement pumps which are constructed for the entire pump displacement to be injected. Applicants pump is constructed for a displacement in excess of power requirements of the engine, and it is that portion of the pump displacement which is not injected into the engine that is by-passed back to the reservoir I| through the vent 3|. The orice opening of the vent 3| is varied by the closure 33 being lifted to different heights, and the closure 33 is lifted under pressure of the working barrel 25 to the height that affords the magnitude of orifice opening large enough to accommodate whatever portion of the pump displacement is not injected into the engine. The pressure in the working barrel 25, and accordingly the operating pressure of the pump 38-25, is balanced against the Stress of the band 34 tending to seat the ball 33.

The band 34 is constructed of any suitable material that affords the desired degree of re siliency, steel, and more particularly a suitable spring steel, having been used and found satisfactory. Homogeneous composition circumferentially is important, and the ring 34 therefore constitutes a continuous or closed band-that is preferably constructed of seamless tubing or rod stock.

Band 34 is preferably manufactured circular, with predetermined inside and outside diameters that are concentric. These dimensions are precisely established to determine and control the operating pressures of the pump 25-38, and to control and vary the operating characteristics of the pump, the injector and the engine Aunder circumstances that will be described more fully hereinafter. l

The annular groove or seat 26 provides a rest at 86, Fig. 2, which is opposite the recess 32. The inside surface of the band 34 bears against the rest 86 at one point in its circumference, and at an opposite point the band is pressed over the ball 33 positioned in the recess 32. This operates to distort the ring 34 from its normal circular contour to an ovate contour, the extent of ovate distortion depending upon the inside diameter of the ring with reference to the greater dimension measured from the surface of the rest at 86 to the remote surface of the ball 33.

The ring 34 has become spring-tensioned by its distortion to ovate contour, and the inside diameter of the ring is precisely predetermined 4to produce the exact extent of ovate distortion that affords the desired character of spring tension in the valve of ball 33. When the ball 33 is lifted from port 3| by the pressure in the working barrel 25 attaining a magnitude sufcient to overcome the tension of spring 34, the magnitude of ovate distortion of the ring is in,-

creased accordingly, and the tension of the spring 34 is thereby increased. When the Valve of ball 33 is in open condition, the pressure within the working barrel 25 continues to be balanced in opposition to the spring tension of band 34, and the operating pressure of the pump 38-25 is accordingly predetermined by the degree of ovate distortion of the band 34.

The wall thickness of the band 34 in addition to its inside diameter is a factor which, considering the width of the band also, determines the magnitude of resilient resistance that the band 34 exerts. The width of the band 34 being standard to t the seat 26, the outside diameter of the band is precisely established for determining the resiliency characteristics of the band. Thus, the various dimensions of the circular band 34 are established to provide resiliency characteristics that provide the desired pressure characteristics in the pump 38-25.

The band 34 being manufactured circular, it is capable of being machined more easily to accurate dimensions within close manufacturing tolerances. This is an important factor of merit in the pressure relief valve 33--34 of the present invention. It enables the pressure characteristics of the pump to be controlled precisely, thereby providing operating characteristics in the engine that are precisely best suited to meet the demands of the service expected from the contemplated engine installation. It also enables the operating characteristics of the engine to `be variably controlled easily and at low cost by replacing its set of rings 34 with a set having different dimensions providing different desired resiliency characteristics. The attribute of the dimensions of the rings 34 being determinable precisely accurately also functions to establish uniformity in the operating characteristics of different cylinders of a multiple-cylinder engine, andthis results in smoother performance of any engine embodying the invention.

Spring operation of the ring 34 extends from its contact with the ball 33 in opposite directions annularly towards the rest 36. Surface contact between the rest 86 and the inside surface of band 34 extends from the mid-point of contact at 86 away therefrom in opposite directions annularly. The portion of the band 34 that affords resiliency is that portion which is not in contact with the seat 26 at rest 86. Any increase in the extent of contact at rest 86 produces a corresponding diminution of the extent of the resilientportions of the band 34, and increased ovate distortion of the band caused by the valve of vent 3l being opened to a greater extent increases the extent of surface contact between the ring 34 and seat 26 at rest 86.

When the ball 33 is lifted, the two portions of the ring 34 that extend away from the ball 33 in opposite directions annularly to the points where contact is made with seat 26 at rest 36, in addition to becoming shortened, become progressively straighter, and they thus become increasingly stressed under tension at the same time losing quality of flexure. It is possible to dimension the spring 34 for itslegs extending away from ball 33 to approach straightness when valve 33-34 is opened to its fullest extent, and then the spring becomes virtually rigid, i. e., its resistance against further distortion approaches infinity. In practice it is desirable that the spring 34 operate resiliently at any extent to which the valve 33-34 becomes opened.

The inherent resiliency characteristic of the band spring 34 is that its tension increments ncrease progressively with unit increments of spring displacement. The curvature of the rest 36 with reference to the inside diameter of the band 34 is an additional factor which contributes to this characteristic of resiliency. Resistance to ovate distortion of the spring 34 accordingly increases in increments that increase progressively as the valve 33-34 is opened to progressively greater extents. When the fuel bypassed through the valve of ball 33 constitutes an increased percentage of the pump displacement, the percentage of the pump displacement that is injected into the engine is correspondingly reduced. Then the progressively increasing increments of increased spring tension resulting from the by-pass valve 33-34 being opened to a greater extent operates to compensate for the reduced quantity of fuel injected through the nozzle I4 which has a iixed orifice opening. Increased operating pressure of the pump 38-25 is thereby provided, which compensates to produce atomization that enables efficient combustion of the reduced charge of fuel.

In the practice of the invention, a spring 34 is selected with dimensions which aifcrd desired resiliency persistently over the contemplated range of orifice openings of the valve 33-34, and which establishes operating pressures in the working barrel 25 that are suitably high for good atomization under all contemplated conditions of engine operation either under load or when idling. Thus, efcient combustion is attained throughout the range of speeds at which the engine is constructed to operate. This is an important advance in the modern trend towards higher engine speeds. In addition, efficient combustion at idling speed inhibits engine fouling. Also, applicant attains high pump pressure While starting, and easier engine starting than under existing prior art practice is attained by practice of the present invention.

The diameter of the cylindrical surface of the seat 26 is important. It is constructed to a diameter which provides a radius of curvature less than the radius of curvature of the inside diameter of the band 34 by the predetermined amount that produces the desired extent of surface contact at rest 86 when the band is assembled in the valve 33-34. The depth of the recess 32, a ball 33 of given diameter being employed, is an additional factor of importance. These dimensions of elements of the pressure control device that are embodied in the pump body 24 are established, with reference to the inside and outside diameters of the band 34, pursuant to the purpose of attaining the hereinbefore described efcient engine performance throughout the range of operating conditions contemplated in use.

The piston 38 has a reduced waist or annular groove 39, Fig. 5, which breaks the lengthwise continuity of the cylindrical surface of piston 38 and forms an annular pressure chamber 40 in the working barrel 25 when the plunger 31 is assembled in the sleeve 24 as shown in Fig. 1. A transverse bore 42, Figs. '7 and 8, extends across waist portion 39 of the piston 38 and connects with an axial fuel passage 4l leading to the end face of the piston 38. The ducts 4I and 42 provide communication between the two portions vof the pumping chamber comprising the annular chamber 46 formed by groove 39 and the space within the working barrel 25 between the member 23 and the end face 85 of the piston 38. See Fig. 1.

The end face 85 of the piston 38 constitutes a valving shoulder for the intake port 30. One of the edges formed by the waist portion 39 of the piston 38 is contoured to provide valving shoulders 90 and 9| for the feed port 28 and the by-pass port 21 respectively. Fig, 6 is a developed view of a portion of the piston 38 of the plunger 31, illustrating the proiile of the valving shoulders 98 and 9| for the respective ports 28 and 21, the shoulder 99 extending to the left, and the shoulder 9| to the right, of the center line (00.1)

The valving shoulder 90 is positioned relative to valving shoulder 85 lengthwise of the piston 38 to open the feed port 28 at a predetermined time interval during the downward stroke of the plunger 31 after the intake port 30 has been closed by its valving shoulder 85. Closure of intake port 30 operates to trap fuel in the working barrel 25, which becomesv stressed under pressure by the continued downward travel of plunger 31. The magnitude of this pressure is invariably sufcientv to overcome the spring I9 and therefore to inject fuel into the cylinder of the engine through the orifice I4 of the nozzle I3. As previously explained, the pressure in the working barrel also becomes suicient to overcome the tension of spring 34, and the entire pump displacement spills through the vent 3I until the port 28 is opened. The pumping pressure under control of the spring 34 is sufficient for good atomization, and this pressure is available for injection when the port 28 is opened.

The valving shoulder 9| is located at a position sa shown in Fig. 6 that is upwardly from Valving shoulder 99, and therefore valving shoulder 9I opens the port 21 later during the downward stroke of the plunger 31 than valving shoulder 90 opens port 28. The operation of the by-pass valve 21 being opened causes the pressure in the working barrel 215 and in the chamber 4!! to be relieved, and it drops off to a magnitude that is not suicient to sustain injection, The spring I9 therefore actuates the closure member I8 to close the duct ZI, and the iiow of fuel through the duct 28 and orifice I4 stops, The fuel that is displaced by the continued downward movement of the plunger 31 after the port 21 is opened becomes lay-passed into the reservoir II through the passage of duct 21.

The valving shoulder 90 is preferably contoured helically as indicated by its downward inclination to the left away from the center line in the developed view Vof Fig. 6. Valving shoulder 9S also is preferably contoured helically, and is inclined downwardly in the direction to the right away from center line 0 in Fig. 6.

Rotation of the plunger 31, for example, by means'of the rack S3, Fig. 1, operates to regulate the time during the downward stroke of piston 38 when the valving shoulder 98 passes and opens the port 28, and the time when the valving shoulder 9| passes and opens the port 21 is also regulated thereby. Rotation of the piston 38 in the counterclockwise direction in Fig. 8 corresponds with moving the valving shoulders 98 and 91| relative to their respective ports 28 and 21 to the right in Fig. 5, theeifect being relative movement of theports 28 and 21 to the left in Fig. 6. The port 28 is thereby opened at an earlier time during the downward stroke of plunger 31 than previous to the adjustment, and the port 21 is lopened later than its previous *opening By the port 28 being opened earlier and the port` 21 later,

10 the time interval in the pumping stroke is prolonged during which injection takes place.

Clockwise movement of the plunger 31 in Fig. 8 has the opposite effect. The valving shoulders 99 and 9I move relative to their respective ports 28 and 21 to the left in Fig. 6 causing the port 28 to be opened later and the port 21 to be opened earlier, the time interval of injection being reduced accordingly. This adjustment of the valving shoulders 90 and 9| to the left in Fig. 6 can be extended to a condition of the by-pass valve 21 being opened simultaneously with feed port 28, or slightly earlier. In this event, no injection takes place, and this adjustment is available to stop the engine. The arcuate portion 94 at the extreme right of valving shoulder 9| in Fig. 6 is provided for the port 21 to register therewith when the arcuate portion 95 at the extreme right of valving shoulder 98 registers with port 28. See also Fig. 9. It will be recalled that the ports 21 and 29 are diametrically opposite each other, or 180 apart, in the working barrel 25.

The valving shoulder 98 for the feed port 28 is stepped as indicated at 92 in Fig. 6, and as shown exaggerated in Figs. 5, 7, 8 and 9. This serves to inject a preliminary charge into the engine in advance of the main charge that supplies engine power requirements, the preliminary charge operating to enhance combustion of the main charge.

In practice, the step 92 is formed by grinding a recess into the cylindrical surface of the piston 38 adjacent to the valving shoulder 98. The depth of the recess is predetermined for a preliminary charge of predetermined magnitude, and

in practice a very slight depth serves the purpose,

about one thousandth of an inch (0.001) being sufcient.

The recess of step 92 extends away from the valving shoulder 99 a predetermined distance lengthwise of the piston 3S for the step 92 to open the port 28 a predetermined time interval before the valving shoulder 90 reaches the port 28 to open it fully. This times the preliminary `of the total displacement of pump 38-25, and

therefore almost the total pump displacement is by-passed through the vent 3I when the pre- `liminary charge is being injected. When the main charge is being injected, the orifice opening of the valve 33-34 is reduced to accommodate the reduced percentage of the pump displacement that is by-passed therethrough. Ovate distortion of the band 34 is greater when the preliminary charge is being pumped than when the main charge is being injected, thereby providing increased operating pressure of the pump 38--25 that compensates for the diminutive rate of flow through the nozzle orifice I4 and producing good atcmizaticn of the preliminary charge.

The cost of the injector of the present invention, kas also its maintenance costs, are greatly reduced by practice of the present invention. In

invention, so long as it does not constitute all the fuel otherwise by-passed through the vent 3 I, does not detract from the quantity of fuel fed to the engine. Therefore, theV piston 38 and the working barrel 25 can be manufactured to greater permissible production tolerances, and accordingly less costly manufacturing practices are suitable and available. The production cost is reduced thereby, and the parts are made interchangeable.

The annular collector groove 65, Fig. 4, is provided in the wall of the working barrel above the valve ports 28 and 3|, the by-pass duct 54 communicates with the groove 65 for the passage of fuel therefrom to the reservoir II. Leakage between the piston 38 and the working barrel 25 is arrested inthe groove 65, and is directed to the reservoir I I through the duct 64.

The operation of the injector follows, reference being had particularly to Fig. 1 and the sequence diagrams comprising Figs. l to 14.

Fuel oil from a suitable low pressure source of supply is fed to lter chamber 5I in pump block 35 from whence it flows through the oil ducts 58 into the reservoir l I formed by the annular space around the sleeve 24 in shell I8. The reservoir II provides a source of fuel for the pump 38-25 and supplies its needs continuously during all stages of its operation. The fuel from the lter cavities 5I circulates in reservoir II and serves to cool the injector.

During the suction stroke, as the piston 38 moves upwardly from its position shown in Fig. 14 towards its position in Figs. 10 and 1, the valving shoulder 85 at the end of piston 38 opens the intake port 30. Thereafter during continued upward movement of piston 38, oil from the reservoir II is drawn through the intake port 33 into the pumping chamber 25. Figs. 1 and 10 show .the plunger piston 3B at the end of the suction stroke.

In this position it will be seen that the feed and by- pass ports 28 and 21 respectively of the pumping chamber are covered by the cylindrical portion of the plunger piston 38. As the injection stroke of the plunger 31 starts, fuel in the lower end of the pumping chamber 25 is forced upwardly through the ducts 4I and 42 into the annular pressure chamber 4B.

After Ythe beginning of the downward stroke of the piston 33, the fuel in the working barrel 25 is displaced through the intake port 39 into the reservoir II until the intake port 38 is closed by passage of the valving shoulder 85. See Fig. 1l. The feed and by- pass ports 28 and 21 respectively continue to be closed. Now the fuel contained in the working barrel 25 and the chamber 48 is trapped, and it is stressed under pressure therein against resistance of the spring 34. When the pressure in the working'barrel 25 builds up to a magnitude sufficient to overcome the resistance of spring 34, the ball 33 is lifted from the port 3| in opposition to the tension of the spring 34. This takes place at a time during the pumping stroke of the plunger 31 before the port 28 is opened. Previous to fuel being fed to the engine through the feed port 28, the total displacement of the pump 38-25 is by-passed into the reservoir II through the valve of ball 33. This is so excepting for any leakage past the piston 38, which is also by-passed into the reservoir Il through the wiper groove and duct 64, Fig. 4.

The port 28 is opened during the downward stroke of the plunger 31 first by the stepped shoulder 92. See Fig. 12. A diminutive preliminary charge is thereby injected into the engine preceding the main or power charge by a predetermined time interval that enables the preliminary charge to become ignited before the main charge enters the cylinder. The main charge is injected when the valving shoulder 98 opens the port 28. See Fig. 13. The llame of the preliminary charge, which is present in the cylinder when the main charge enters, operates to assist ignition of the main charge, the main or power charge being thereby ignited smoothly without detonation or shock which detracts from smooth engine performance. 'Ihe operating pressure of the pump 38-25 during injection of the power charge is established to produce good atomization and an improved spray pattern, the operating pressure being determined by the pressure in the working barrel 25 being balanced against the tension of spring 34. Components of the valve 33-34 are dimensioned accordingly as hereinbefore explained.

Injection continues after port 28 is opened by valving shoulder 98 until the valving shoulder SI reaches and uncovers the by-pass port 21, bypassing the oil under pressure in the chamber 48 back into the reservoir I I which is under relatively low pressure. See Fig. 14. The pressure in the chamber 25 is thereby relieved, and the valve of ball 33 is closed. The spring I9, Fig. l, also operates to close the valve I8. The injection of the fuel charge is thus completed while the plunger 31 continues to travel to its extreme position in the downward direction. After the vent 3l closed in the manner descrbed, the total displacement of the pump 38-25 is by-passed into the reservoir II through the port 21. The cycle is repeated beginning with the suction stroke as shown in Fig. 10.

The plunger 31 is rotated by the pinion 55 in response to a particular setting of the rack 63 which may be actuated manually or by governor actionY in the usual manner common in the operation of internal-combustion engines. The effect of rotating the plunger 31 is to present different aspects of the helical valving shoulders 98 and 9| of piston 38 to the feed and by- pass ports 28 and 21 respectively. This has the effect of varying the distance lengthwise of piston 38 between those positions along the respective valving shoulders 98 and BI circumferentially that register with the respective ports 28 and 21, and this operates to vary the interval of time between the respective feed and by- pass ports 28 and 21 being opened. The quantity of fuel that constitutes a charge to meet the power requirements of the engine is thereby determined.

The spring-loaded valve 33-34 controls the pressure of the fuel in the chamber 40 since it acts as a pressure limiting valve. The spring band 34, because of its resiliency, exerts pressure on the valve ball 33, thereby determining the operating pressure in the chamber 48. The spring 34 places an initial loading on the ball 33 sucient to maintain the necessary pressure for good atomization at cranking and low speeds. As the engine speed is increased, the rate of pump displacement increases. The rate of fuel ow through the port 3| is increased accordingly, producing increased ovate distortion of the spring band 34, and increased operating pressure in the working barrel 25. Increased rate of flow through port 28 is resisted, the size of the oriiice I4 being fixed, and accordingly the effect of increased engine speed is to by-pass a greater percentage of the pump displacement through the valve 33-34, thereby increasing the operating pressure still more. Accordingly, at higher speeds relative to lower speeds, the quantity of fuel fed to the engine is less, and at the same time quality of atomization is enhanced by the increased Velocity of iluid iiow through orifice I4 as also by increased operating pressure of pump 38-25 generated because of increased ovate distortion of the band 34. This characteristic of the invention is not ernployed to eliminate use of a governor, but it functions to improve the stability of engine performance under varying load conditions, and over a wide range of engine speeds including idling speed.

Referring to Fig. 2 it can be seen that, by varying the internal diameter of the spring ring 34, the amount of initial tension in the spring when assembled over the valve ball 33 can be changed. A ring which is put on relatively loosely, that is with a small initial tension, will be springy, and will control the valve ball 33 to give a low pressure response at low speeds, the pressure response increasing as the speed increases. That is, the ring 34 will have a slowly increasing spring constant. Similarly a ring of a size that requires a greater degree of `initial tension in positioning it over the valve ball 33 generally will be relatively stiff, and will result in a high pressure response at low speed, the amount of lift of the valve ball 33 being progressively resisted in relatively higher increments. Such type of spring can be said to have a rapidly increasing spring constant.

The ring spring 34 also offers means for producing uniformity of pressure level in the pressure chamber 4U, Fig. 1, among a series of injectors. This is important in multi-cylinder engine construction where uniformity of operation among cylinders is vital.

For accomplishing the advantages noted hereinbefore, the pressure control valve 33-34 is preferably constructed and assembled in the manner now to be described, reference being made particularly to Fig. 2 of the drawings. During the process of manufacture, the valve ball 33 is in- 'serted into and valve ball recess 32 and is pressed against port 3i to form a seat, and it is further lapped into place until the measurement from thel rest-86 of spring seat 26 to the remote surface of the seated ball 33 gages to the predetermined desired value. This dimension can be made readily identical for all injectors of a set for a given engine, and can be established correctly for the desired operating characteristics of the injectors.

The ring spring 34 in turn is ground to predetermined inside diameter and thickness, so that any spring 34 made to specification whenassembled on any sleeve 24 and valve ball 33 manufactured to'predetermined dimensions as above described, will have a predetermined initial tension as also spring constant values that are predetermined for any magnitude of valve opening of vent 3|. By this means the pressure response characteristics of the injectors of a set for a given engine are easily and reliably controlled for a sprayed through the orifice It.

range of operating conditions they are expected to encounter in their intended use.

In the ordinary jerk pump, the pressure on the fuel at the spray nozzle will vary with the speed of the engine, increasing as the engine-speeds up and vice versa. Therefore the pressure of the oil sprayed through the orifice of the spray nozzle will be relatively low at low engine speeds. Ordinarily, small orifice openings are required to secure suihcient atomization of the fuel at such relatively low pressure. The use of small spray orifice openings, however, limits the fuel flow at higher operating speeds, when the velocity of oil iiow becomes high necessitating the use of high fuel pressures. This in turn requires almost microscopic fits between parts of the injector in order to minimize the high fuel leakage which tends to occur at Such high pressures.

From the above it can be seen that the size of the orifice openings and the range of fuel pressures employed in the nozzles of the prior art impose limitations on engine design. Whereas a prior art injector may be designed for satisfactory operation at a given operating speed it will not operate efiiciently over a wide range of speeds and an engine equipped with an injector constructed for full load conditions will be difficult to start at cranking speeds and will cause fouling and poor combustion when idling. Such limitations of the operating characteristics of a fuel injector over a wide range of operating speeds has acted as limiting factor in the field of high speed engine design for the above presented reasons.

The injector comprising the present invention overcomes the prior art difficulty by utilizing 'a plunger piston 38 of larger size than one normally employed in a jerk pump type of injector unit of equivalent capacity, together with orice openings !'4 of sufficient size to accommodate the quantity of fuel injected. The larger sized piston 38 enables a larger fuel displacement to be had at low engine speeds, the relatively large displacement causing sufhcient pressure even at low speeds to cause good atomization of the fuel This construe#A tion has been found to result in a marked improvement in the operating characteristics of a standard Diesel engine equipped with injectors embodying the present invention because it permits the engine to be operated for long periods at idling speed without fouling the engine. As the engine speed increases for a given rack setting, and the pressure builds up, the spring-loaded ball 33 is raised from its seat thereby controlling the pressure in chamber 43 at a predetermined level and spilling the excess'fuel back into the reservoir l I, so that, at higher engine speeds the proper amount of fuel under sufficient pressure for good atomization will be sprayed through the orifice i4. A rising fuel pressure characteristic with speed can be obtained in chamber 40, if desired, by positioning the upper contour edge of waist section 33 of plunger 3'! so that port 3l, Fig. 4, is partially covered during the injection interval.

Thus the injector comprising the invention permits satisfactcry engine operation over a Wide range of operating speeds. The injector, by functioning satisfactorily at cranking speeds to permit i easy starting, by operating efficiently at idling speeds over long periods without fouling, and and by delivering power efliciently at full load conditions makes higher engine speeds feasible, in addition to improving the operation of present engines.

From the preceding description of operation, it becomes clear that the amount of fuel metered through the spray nozzle I3 of the injector comprising the present invention depends on the time interval between the opening of the feed port 28 bythe valving shoulder 90 and the opening of the by-pass port 21 by valving shoulder 9 I. Moreover as the engine speed increases the pressure is maintained at a predetermined level in the pressure chamber 4U by the pressure regulating valve 33-34. Thus the time interval between the opening of the feed port 28 and the by-pass port 2 varies directly as the speed of the engine, and, as the amount of fuel injected depends on this time interval, it follows that for a given setting of the rack 63 the amount of fuel dispensed to the engine decreases with increase of engine speed and vice versa, a condition which gives the engine inherent speed stability without dependence on governor or manual control. This is of marked contrast with the action of existing injectors wherein the amount of fuel injected per stroke varies but little with change of speed.

It will be noted that the operating characteristics of the injector of the present invention can be readily modified as desired merely by selecting a spring ring 34 dimensioned to provide the desired resiliency characteristic. Since the pressure in the chamber is regulated by the spring 34, it is obvious that the discharge pressure at which the fuel is sprayed through the spray orice I4 is controlled by the characteristic of the spring 34. By this means the pressure of the fuel injected can always be regulated at an established value so as not to exceed any predetermined maximum, fora wide range of engine speeds.

From the above description it is clear that the full displacement of the injector pump 38-25 is utilized only at low engine speeds to maintain adequate spray orice pressure. At low speeds, the fuel leakage is insignificant due to the relatively low pressure of the fuel. Since, at higher speeds, the fuel displacement is not utilized because of the by-passing through the pressure control valve 33-34 as above described, it follows that a certain amount of fuel leakage, as long as it does not exceed the amount to be spilled through valve 33-34, is permissible.

In prior art constructions, the amount metered to the orifice by the plunger depends on the plunger displacement for all operating speeds, and any leakage is critical. That is, each increment of plunger displacement has to be utilized to pump the required amount of fuel to be dispensed through the spray orice and any fuel leakage in the injector is vital in that it robs from the required amount of fuel to be injected. Microscopic ts between plunger and pumping chamber are required with resulting expense in manufacturing cost and impracticability of interchangeability of parts. f

In the present invention such close tolerances between pumping parts are not so critical for reasons presented hereinbefore, and as a consequence, manufacturing tolerances are greater. Interchangeability of parts is thus made possible and mass production possibilities increased.

Use of the'stepped shoulder 9| for delivery of a preliminary charge results in an efficient fuel distribution to the engine. By injecting a small quantity of fuel as a preliminary charge, followed sequentially by injection of the main charge on the already burning preliminary charge, a relatively slow, expansive combustion takes place in the cylinder instead of the detonaition resulting `'when the main charge is injected en masse. As is familiar to those skilled in the art, a relatively slow, expansive combustion results in a desirable smoothness of operation and greater operating efficiency. The relative size and position of the stepped shoulder 9 I, Figs. 5 to 8, depends on the desired characteristics of the engine and fthe type of fuel employed, and is shown in Figs. 5 to 8 by way of illustration only,

The injector of the invention has been described and illustrated as a self contained unit in which the pumping mechanism and spray nozzle are combined into a unitary structure ready for application Ito an engine. It is obvious however, that the novel pumping mechanism and injection control means comprising the present invention may be incorporated into a central pumping unit adapted to be connected by fuel distribution lines to separate discharge nozzles provided in the engine cylinders in the manner well known in the art.

It is to be understood that various modifications and changes may be made in this invention without departing from the spirit and scope ithereof as set forth in the appended claims.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

What is claimed is:

l. In a fuel injector for an internal-combustion engine, an injector pump comprising a pumping chamber, apparatus for determining the operating pressure of the pump comprising a vent in the pumping chamber and :a closure therefore, a spring holding the closure in closed condition and permitting the yent to be opened resiliently, the spring comprising a continuous band around the pump engaging the closure and the exterior surface of the pumping chamber at points that are opposite each other on iits inside surface.

2. In a fuel injector for an internal-combustion engine, an injector pump comprising a sleeve embodying a cylindrical pumping chamber, apparatus for determining the operating pressure of the pump comprising a vent from the pumping chamber to the exterior of the sleeve and a closure for the vent exteriorly of the sleeve, a spring holding the closure in closed position and permitting the vent to be opened resiliently, a sea-t for the spring comprising a cylindrical exterior surface of the sleeve at the closure disposed concentric with the pumping chamber, Ithe closure projecting exteriorly of the sleeve above the cylindrical surface of the seat, the spring comprising a normally circular continuous band engaging the closure and the seat at opposite points on its inside surface.

3. In a fuel injector for an internal-combustion engine, a pump with a capacity in excess of power requirements of the engine and comprising a 4working barrel and a piston operable therein to pump fuel to the engine, a feed port in the working barrel and the piston comprising a valving shoulder positioned to open the feed port at a predetermined time in the pumping stroke, a pressure control device for the pump comprising a vent in the working barrel, a spring operable resiliently opposed to the operating pressure of the pump to hold the vent closed against the flow of fuel therethrough, the vent comprising an orice opening that is variable under variations of andere 17 the operating pressure of the pump opposing the tension of the spring, the valving shoulder being' positioned in the piston to open the feed port after the tension of the spring has beenv overcome to open the vent.

4. In a fuel injector for an internal-combustion engine, an injector pump with la, capacity in excess of the power requirementsmf ithe engine and comprising a pump body embodying a cylindrical working barrel, awport from the lworki'ng barrel through the wall thereof te the exterior of the pump body, a closure for the port exteriorly of the pump body, a recess into the exterior of the pump body and extending to the port, the recess being o'f a size to receive the closure positioned against the port, a spring holding the closure in closed position against the port andk permitting the closure to lift away from the port resiliently,'a seat for the spring comprising a cylindrical exterior surface ofthe pump body at the recess disposed concentrically with the lworking barrel and including a rest opposite the recess, the recess being of a depth for the closure to project out of the pump body above the cylindrical surface of :the seat by a predetenmined amount, the spring comprising a continuous band positioned in the spring seat and engaging the closure and the rest at opposite points on its inside surface, the band being normally circular and being tensioned to hold the closure seated by being stressed to ovate contour, the resiliency characteristics of the spring depending upon the inside diameter of the bland being less by a predetermined amount than the measurement from the closure to the rest.

5. In a fuel injector for an internal-combustion engine, an injector pump with a capacity in excess of the power requirements of the engine and comprising a pump body embodying a cylindrical working barrel, a port from the working barrel through the Wall thereof to the exterior of the pump body, a closure for the port exteriorly of the pump body, a recess into the exterior of the pump body and extending to the port, the recess being of a size to receive the closure positioned against the port, a spring holding the closure in closed position against the port and permitting the closure to lift away from the port resiliently, a seat forthe spring comprising a cylindrical exterior surface of the pump body at the' recess disposed concentrically with the working barrel and including a rest opposite the recess, the recess being of a depth for the closure to project out of the pump body above the cylindrical surface of the seat by a predetermined amount, the spring comprising a continuous band positioned in the spring seat and engaging the closure and the rest at opposite points on its inside surface, the band being normally circular and being tensioned to hold the closure seated by being stressed to ovate contour, the resiliency characteristics of the spring depending upon the thickness of the band and upon the inside diameter of the band being less by a predetermined amount than the measurement from the closure to the rest.

6. In a pumpas defined in claim 4, the diameter of the cylindrical surface of the spring seat being of a predetermined magnitude less than the inside diameter of the band for the desired extent of surface contact between the band and rest when the band is seated.

7. In a fuel injector for an internal-combustion engine, an injection pump with a capacity in excess of engine power requirements and comprising a pumping chamber, a device for cori-y trolling the operating pressure of thepunp corn--A prising a vent through the wall of the pumping chamber to by-pass the portion of the pum-p dis-4 placement in excess of the injected fuel, a closure for the vent seated against it exteriorly of the pumping chamber, a spring holding the closure seated and being operable to hold the vent open resiliently in balance with and opposed to the operating pressure ofthe pump to control the orifice area ofthe vent variably, the springcomprising a continuous band around the pumping chamber and engaging the closure and thepumping chamber exteriorly at opposite points on its inside surface, the band being normally circular and exerting its spring tension by being distorted to ovate contour, ovate distortion of the band varying according to various orifice areas of the vent to control the balancing operating pressure of the pump variably accordingly.`

8. In a device for controlling the operating pressure of a pressure uid apparatus,- a vent and a spring operating opposed to the operatinggpressure of the apparatus to control the flow of lfluid through the vent, the spring comprising a normally circular continuous band that is tensioned by being distorted to ovate contour.

9. In a set of fuel injectors for a multiple-cylinderinternal-combustion engine, a pump for each injector'to feed fuel to its cylinder, a device for controlling the operating pressures of the several pumps uniformly comprising a vent for each pump and a spring for each vent operable resiliently opposed to the operating pressure of its pump to control the flow. of uid through the vent, each spring comprising a normally circular continuous band that is tensioned by being distorted to ovate contour, the dimensions of the several bands being alike for uniform operating pressures in the several pumps of the respective cylinders.

l0. For a set of injectors as dened in claim 36, selectively interchangeable sets of spring bands, the dimensions of the several bands of each set being alike and the dimensions of the bands of different sets being different to provide different resiliency characteristics.

1l. In a fuel injector for an internal-combustion engine, a pump with a displacement in excess of power requirements of the engine and embodying a working' barrel and a plunger comprising a piston operable therein, a feed port in the working barrel, the piston comprising a valving shoulder positioned lengthwise thereof to open the feed port to inject a main charge that supplies engine power requirements at a predetermined time in the pumping stroke of the plunger, the piston comprising a step ground into its face at the valving shoulder to a predetermined depth to inject a diminutive preliminary charge of predetermined quantity, a by-pa-ss port for the passage of that portion of the pump displacement in excess of the injected fuel from inside to outside the working barrel and a closure therefore projecting above the exterior surface of the working barrel, a spring resiliently holding the closure in closed position on the port opposed to the operating pressure of the pump, the spring comprising a continuous band around the working barrel engaging the closure and the exterior surface of the working barrel at opposite points on its inside surface, the feed and by-pass ports being positioned relative to each other lengthwise of the working barrel for the by-pass port to be opened under pressure of the pump before the step of the 19 piston reaches the feed port to inject the preliminary charge.

12. In a fuel injector for an internal-combustion engine, a pump comprising a working barrel and a piston operable therein to inject fuel to the engine, the working barrel comprising a port for fuel passage to the engine, the piston comprising a Valving shoulder to open the port for injecting a main charge that supplies engine power requirements, a step adjacent the valving shoulder ground into the piston face to a predetermined depth to inject a diminutive preliminary charge of predetermined magnitude, the step extending a predetermined distance away from the valving shoulder lengthwise of the piston to time the preliminary ncharge with reference to the main charge.

13. For the injector pump of an internal-combustion engine, a piston comprising a cylindrical surface, an edge of the cylindrical surface extending circumferentially comprising a Valving shoulder for injecting the main charge to supply engine power requirements, a recess adjacent the valving shoulder and ground to a depth in the cylindrical surface predetermined to inject a diminutive preliminary charge of predetermined 20 magnitude, the recess extending a predetermined distance away from the valving shoulder lengthwise to time the preliminary charge with reference to the main charge.

GARDINER M. ROGERS.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,586,046 Nelson June 8, 1926 1,596,194 YLang Aug. 17, 1926 1,732,918 Sutton Oct. 22, 1929 2,096,711 Fielden Oct. 26, 1937 2,140,956 Hall Dec. 20, 1938 2,144,861 Truxell, Jr Jan. 24, 1939 2,144,862 Truxell, Jr Jan. 24, 1939 2,174,898 Scott Oct. 3, 1939 2,378,165 Waeber June 12, 1945 2,380,148 Camner July 10, 1945 2,441,167 Raspet May 1l, 1948 2,462,363 Cook Feb'. 22, 1949 2,464,288 Belt Mar. 15, 1949 2,496,804 Meitzler Feb. 7, 1950

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