US1968163A - Diesel engine - Google Patents

Description

4 Sheets-Sheet 1 DIESEL ENGINE B. v. E.-NORDBERG Filed April 15, 192s July 31, 1934.

. v. E. NORDBE'RG 1,968,163

DIESEL ENGINE FiledADIil 13, 1928 4 Sheets-Sheet 2 HEADEND DEAD PQINT July 31, 1934.

B. V. E. NORDBERG DIESEL ENGINE Filed April l5, 1928 4 Sheets-Sheet 5 July 31, 1934.

B. V. E. NORDBERG DIESEL ENGINE Filed. April 13. 1928 4 Sheets-Sheet 4 Patented July 31, 1934 DIESEL ENcmE Bruno V. E. Nordberg, Milwaukee, Wis., assigner vto Nordherg Manufacturing Company, Mil-1 waukee, Wis., a corporation of Wisconsin Application April 13, 1928, Serial No. 269,823

14 Claims.

This invention relates to internal combustion engines, and particularly to Diesel engines of the air injection type.

The invention resides in method and appara- 5 tus for regulating the supply of fuel in accordance with the load whereby a closer speed regulation of the engine is secured than has been had heretofore, and resides further in certain details of the mechanical structure used to feed the fuel. In an air injection Diesel engine the fuel is fed to Aan atomizing chamber and is then delivered in atomized form into the working cylinder by an air blast which is rendered effective by the opening o f a needle valve. The opening of this valve occurs in timed relation to the rotation of the main crank shaft of the engine, and is ordinarily effected by a/'cam mechanism.v Since the fuel injection is timed solely by the opening of the needle valve it is not material to operativeness just when the fuel is supplied to the atomizing chamber. It may be supplied sometime prior to the opening of the needle valve without in any way affecting the timing of injection. It has heretofore been considered desirable to preserve a so-called safety interval between the termination of supply of fuel to the atomizing chamber and the succeeding opening of the needle valve. This practice Was adopted not only for safety considerations but also because the practice permitted marked simplication of the fuel pumping mechanism. In ordinary service this practice is entirely satisfactory, but in cases where very close speed regulation is demanded it introduces difficulties because of the time lag between the measuring of fuel under the control of the governor and the `subsequent injection of that measured fuel into the cylinder. The arrangement heretofore used imposed a lag of the order of 190 of crank rotation, an interval in which marked changes in loadfrequently occur, with the'result that erratic speed variations are unavoidable.

The present invention is based on the discovery that the s'o-called safety interval is unnecessary, 4.3 and that the fuel feeding to the atomizing chamber and ejection of fuel from the atomizing chamber to the cylinder may be in a large degree concurrent. The effect is to eliminate the time lag heretofore considered unavoidable and thus 53 secure far closer speed regulation than has heretofore been secured.

The attainment of the desired result requires'y the use of individual fuel pumps, one for each cylinder, and the invention resides in this feature and in certain structural details of the pump -taken looking in the opposite direction from Fig. 3.

as well kas in the general method underlying the operation of the device. The more refined considerations involved in the method can be pointed out more satisfactorily after a discussion of the preferred embodiment of'the invention, which 60 will be given in connection with the accompanying drawings.

These drawings show the .invention applied toa vertical single-acting six cylinder engine of the two cycle air injection type having scavenging valves in the head, the exhaust being controlled by cylinder ports' which are overtraveled by the pistons. Engines of this general type are well known. l f y In the drawings,-

Fig. 1 is a vertical'transverse section taken between the third and fourth cylinders.

Fig. 2 is a vertical axial section of the needle valve and fuel injection chamber, on an enlarged scale.

Fig. 3 is aview of the upper portion of Fig. 1, on an enlarged scale.

Fig. 4 is a plan view `of the fuel feeding pump mechanism, thisview showing also portions of the third and fourth cylinders between which the fuel feeding mechanism is located.

Fig. 5 is an enlarged vertical section through one of the fuel feeding pump units, the view being Fig. 6 is a diagram indicating the crankangles subtended by the various events in the fuel feeding and injection phases of the cycle.

Referring first to Fig. 1, a bed plate is shown at l1 and portions of the frames at 12. The crank shaft is shown at 13, one of the crank pins at 14, connecting rod at 15, wrist pin at 16, cross head at 17 and cross head guides at 18. The

cross head 17 is connected to a trunk piston 19 of ordinary construction and this Works in .a 5f cylinder of ordinary construction not shown in detail.

The engine chosen fr illustation is a six cylinder engine, as will be apparent from consideration of the fact that six fuel feeding pumps are 10 illustrated in Fig. "l, but it is deemed unnecessary to illustrate the plurality of cylinders in side elevation for the reason that engines of this type are well known. However in Fig. 4 portions of the cylinder head structure ofthe No. 3 and105 No. 4 cylinders are `indicated by the reference numeral 2l,` and the studs and nuts which removably retain these cylinder heads in place are indicated by the reference numeral 22.

'rheexhausi pipe is indicated in Fig. 1 at 23 110 ,tions 25, one for each cylinder.

indicated in dotted lines on Fig. 1 at 26.

and the scavenging air. manifold at 24. From this last named manifold are branch conneclll'hese connections carry the scavenging air to valves which are located 'in the cylinder head, which valves are actuated from the cam shaft hereinafter described. The-valve and the valve mechanism, however, have been omitted from the drawing, as they form no part of the present invention andif illustrated would only confuse the drawing. No novelty resides in this feature of the engine.

Mounted on the crank shaft 13 is a skew gear This drives a companion skew gear 27 on a vertical shaft 28 which extends parallel to the axes of the cylinders and terminates at its upper end in a skew gear 29 which lies between and meshes with two skew gears 30 and 3l. The gear 30 is on the cam shaftv 32 and the gear 31 is on the fuel pump V Shaft 33.

the fuel pump shaft 33. This relation is adopt,

ed because the engine chosen for illustration is of the two cycle type. 1

The invention, or certain features thereof, is

' applicable to four cycle engines, and of course,

when so applied the drive ratios would be corre-y spondingly changed so that the cam shaft and the fuel shaft would be properly timed relatively to the crank shaft so that fuel feeding and fuel injection would be suitably changed according to vvwell known principles;

The cam shaft 32 carries cams, one of which is indicated at 34 in Fig. 3, arranged to actuate the fuel injection valve. There are six of these cams, one for each cylinder. There are also cams for actuating the scavenging valves in each cylinder, but these and the entire scavenging valve mechanism have been omitted from the` drawings, as already explained.

Each cam 34 coacts with a roller 35 which serves as a. follower and which is mounted on one end of a rocker arm 36 pivoted at 37 and carrying at its 'other end an adjustable thrust member 38.l 'Ihe thrust member 38 engages a tappet 39 which actuates the needle valve or fuel iniection valve. The construction of this fuel injection valve is shown in detail in Fig. 2. A portion of the outer wall of the cylinder head is shown at 21 (see also Fig. 4). The inner wall of the composite cylinder head which forms the upper end of the combustion chamber is shown at 41. This is-provided with a. flaring port 42 in which. is fixed the tubular shell 43 of thev fuel injection nozzle.

With the shell 43 communicate two connections of which the upper one, 44, is the blast air connection and the lower one, 45, is the fuel oil connection. At the lower end ofthe shell 43 is a seat 46 with a needle valve 47 and below the seat 46 is a small atomizing nozzle plate 48. Within the shell 43, and spaced therefrom, is a tubular` member 49 which is urged downward -by a coil spring 51. This-surrounds and guides the stem of the needle valve 47 and seats at its lower end in a plurality of perforated atomizing disks 52 which surround a contracted portion of the shell 49 and which serve to receive and retain the oil which is fed through the connection and flows downward through the narrow interval between the shells "43 and 49. The air entering through the connection 44 ows through the interval between the shell 49 and the Stem Qf mcafee' the needle valve 47. It is discharged above the` atomizing disks 52 through a port 53 in the shell 49o. The stem of the needle valve 47 is sealed by a packing gland 54 andis guided for longitudinal motion ina bearing bushing55 and is urged downward, that is, in a closing direction, by a coil spring 56. This is housed in a shell 57 and is adjustably` stressed by means of a thrust screw 53 which engages the spring seat 59. The upper end of the spring 56 is sustained by the spring seat 59. The screw 58 may be locked in adjusted positions by means of a check nut.

The tappet 3 9 is pivoted at 61 and reacts up` Wardly against a collar 62 which acts in thrust upward against a nut on the upper end of the stem of the valve 47, and also against a'spring seat 63 with which the lower end of the spring 56' contacts.

Valves of the type just described are well known and no novelty resides in their use.

Heretofore the fuel oil entered through the port 45 and such entering ow ceased before the valve 47 was unseated. A substantial interval was provided so that the entire charge of oil should be delivered to the atomizing plates 52 before the valve 47 opened. When this valve opened blast air flowing in through the port 44 discharged the fuel oil through the valve seat 46 and nozzle 48 and delivered it in atomized form within the cylinder.

The most important feature of novelty in the present invention is that while the flow of fuel through the port 45 to the atomizing plates 52 commences before the valve 47 opens, and may commence a substantial period before such opening, it persists after the valve 47 has opened and continues through substantially the entire period of opening of said valve, terminating only so much before the closing of the valve 47 as will afford time for the blast to sweep the atomizing plates 53 free of fuel.

The cam shaft 32 carries a skew gear 65 (see Fig. 3) which meshes with a skew gear 66 splined on the vertical governor shaft 67. The gear 66 is centered by thrust springs 68 between thrust collars 69 fast on the shaft 67, the purpose being to afford a yielding drive of limited extent between the shaft 32 and the governor shaft 67.

Obviously, the use of skew gears implies the existence of Aaxial thrust on the splined gear 66 and this is taken up by the spring 68. The collars 69 not only receive the thrust of the springs but act as limiting stops for the axial shift of the gear 66. The shaft 67 carries at its upper end a governor whose exact form is immaterial, and which is indicated generally by the numeral 71 applied to its case. This governor acts to raise and lower a collar (not shown) mechanically connected to a lever 72 pivoted at 73 on a rigid bracket 74 forming part of the frame structure.

The response of the governor to an increase of speed results in moving the lever 72 upward, while a decrease in speed has the converse effect. The lever 72 is loaded by means of two springs, one

of which, 75, acts at the end of the Vlever and is l not adjustable, and the other of which, 76, acts near the fulcrum of the lever and is adjustable. The means for effecting this adjustment include a hand wheel 78 for manual adjustment and a lsmall electricl motor 77 for power adjustment.

tion'79 witha reach rod 80 which connects the governor to vary the effective stroke of all the fuel pumps, such variation being accomplished by ho`.ding the inlet valves of the fuel pumps open for greater or less portions of the displacement strokes of such pumps. A`tension spring 116 holds the parts in the position shown.

By referring primarily to Fig. 5, occasional reference being made .to Figs. 3 and 4, the construction of one pump unit will be. made plain, after I L the crank throws.

which the connection of all the pump units for simultaneous control will be expained.

The fuel pump shaft 33, which is also visible in Figs. 1, 3 and 4, is a short shaft lying in the interval between the 'third and fourth cylinders. This location is chosen merely because of nearness to shaft 28, which, in the engine illustrated, is located between these cylinders. 'I'he shaft 33 carries eccentrics 81, there being one for each cylinder-of the engine, the angular spacing and order of the eccentrics on the pump shaft corresponding accurately to the angular spacing and order of In other' words, the eccentrics which drive the pumps, and consequently the pumps, are timed lto conform to the working .strokes of the cylinders which they serve.

While I show eccentrics 81, any equivalent means for imparting reciprocating motion to the pump plunger might be used. For example, it has been the practice in fuel pumps occasionaly to use cams to operate the pump plungers, and in some cases the possibilityof designing a cam to give certain character of motion, or to produce this motion during la certain angular motinof the cam shaft has been found useful.l In the present instance the eccentrcs illustrated give j satisfactory operating characteristics and being simple are preferred, butby illustrating eccentrics Ido not mean to imply any necessary limita-A tions to that particular mechanismfas contradistinguished from other well knownrequivalents.

Coacting with each eccentric 81 is an eccentric strap and rod 82 which is pinned at 83 to a cross head 84. This cross head 84 works in a guide 85 and is'connected to a pump plunger 86. This lplunger is axially slidable in a cylinder and guide 87 whose form is clearly shown in the drawings and acts to draw oil into and displace it from a chamber 88 which connects with one end of the cylinder 87. Leading from the lower end of the chamber-88 is a discharge valve 89 which is urged in a closing direction -by a spring 91. The inlet valve is shown at 92 and preferably is located at the upper side of the chamber 88. It is urged upward, that is, in a closing direction, by a spring 93 which acts in thrust between the discharge valve 89 and the inlet valve 92. Each inlet valve is supplied with fuel oil from a chamber 94 immediatey above the valve 92. There is one of these chambers for each of the six pump units and the supply to each chamber arrives by way of a pipe 95 controlled by a corresponding valve 96 (see Fig. 4).

The arrangement of the inlet anddlscharge valves so that the fuel oil enters the' pump chamber at the top and discharges from the bottom 86 is actuated through and synchronously with.

that plunger. To accomplish this desired result a bracket 98 is mounted rigidly on the cross head 84, and pivoted to the bracket 98- at 99 is a rod 101 which is axially slidable in a rocker arm 102. This arm is pivoted in a manner hereinafter described and carries a nose 103 which bears on an adjustable tappet 104 at the upper end of a .thrust rod 105. The rod 105 is confined by a fixed guide 106, y passes through a stuing box 107 and intov the chamber 94 and in that chamber'enters into thrust engagement with the vupper end of the. downwardly 'opening inlet valve 92, this valve being provided with an extension stem 108 for that purpose. 'Ihe rod 105 is urged upward by a coil spring 109 which is seated in the chamber 94 and engages at its upper end a collar 111 fixed on the stem 105.

The fu`lcrum on which the rocker 102 is mount- `ed is adjustable to change the relation of the member 103 to th`e tappet 104. This adjustment might be effected in various ways, but in ythe example illustrated the result is secured by journalling each member 102 on a corresponding eccentric 112. The eccentrics 112 are mounted on a shaft 113 which is rotatable in bearings on brackets 114, the brackets 114 forming a part of the pump structure. consequently has the effect of moving the member 103 toward and from the tappet 104. During Rotation of the shaft 113` such adjustment the slip connection between the y parts 101 and 102 accommodates the relative motion of the parts. As the piston 86 moves outward (to the right in Fig. 5), the member 103 moves downward and according to the position of the shaft 113 will depress the rod 105 more or less.

It follows that on the ensuing inward movevment of the plunger 86, the valve 92 is initially held open for a period, whose duration depends on the position of the shaft 113. This shaft carries an arm 115 (see Figs. 3 and 4) to which The parts are so connected that as the gov- Vernor responds to an increase of speed the shaft 113 is rotated to lower the members 102 and 103 and thus increase the period during which the -inlet valves are held open upon the discharge lor displacement (inward stroke) of the pump plungers 86. The effect is to reduce the total amount of fuel displaced through the discharge valve 89. The reverse movement of the governor '71 has the opposite effect. i

'I'he timing of the fuel feeding events can now be explained with reference to Fig. 6.

The angles plotted in this figure are angles through which'the main crank shaft turns. The dead point is indicated by legend. The radial line marked A marks the earliest commencement of the pump delivery. The time of commence- .ment of pump delivery is variable according to the .position of the governor, as explained, but the latest setting possible must' be prior to the radial line marked B which indicates the fixed point at which the valve 47 opens. Obviously there should be fuel in the nozzle when the quantity of fuel fed. L

blast commences. The radial line C indicates the fixed point at which the delivery of fuel to vvthe nozzle ends, and the radial line D represents the fixed point at which the needle valve 47 closes.

In the particular example chosen for illustration, which is taken from actual practice, the angle from A to C is 110 degrees, the angle from B to D is 43 degrees, and the angle from C to D- which measures the maximum lag of response to the governor.

Under normal conditions of operation, however, fuel pumping does not commence at A but at some point between A and B, so the lag is under normal conditions materially less. In prior practice C precedes B byat least-10 degrees and as the pumping period occurred prior to C and coveredva large angle, the regulative lag was considerable. The` effect of the changed timing is greatly to improve the speed regulation.

The practical effect is to reduce excessive regulatory responses of the governor and thus reduce the tendency to governor oscillation, known as hunting The reduction of the hunting tendency, as will be readily understood, permits the use of a more sensitive and a more nearly iso- -chronous governor, than can be used where a hunting tendency exists. This involves additional gain in accuracy of regulation.

A number of incidental devices are indicated on the drawing for use in starting and stopping The plunger mechanism shown at 121 is a hand pump for priming purposes. The plunger 122 is locked in its outward position by a nut 123 in which position the valve head on the inner end of the plunger seats to prevent leakage. The lever 124 shown in its inactive position on Fig. 5, may be latched in either the hole 125 or 126 to hold the rod 105 in two different depressed positions. 'Ihe pipe shown at 127 is a manifold which feeds the various branches 95 with fuel oil. The handle 128 and connected linkage is a manual means for rotating the shaft 113 to stop the engine. The operation of handle 128 overpowers spring 116 and the purpose of pin.and.slot connection 79 and spring 116 is to permit the stopping mechanism to function. Except for this, link 8G might be merely pivoted to the governor lever at v'79.

What is claimed is,-

1. The method of regulating the power developed in a Diesel cycle using air injection, which consists in kcausing the period of feeding fuel to the nozzle and the period of feeding ,injection air through the nozzle into the cylinder to overlap, so that these periods proceed concurrently for a part of said injection period, and varying the quantity of fuel fed.

2. The method of regulating the power developed in a Diesel cycle using air injection, which consists in causing the period of feeding fuel to the nozzle and the period of feeding injection air through the nozzle into the cylinder to overlap so that they proceed concurrently for the major portion of said injection period, and varying the incense 3. l"he method of regulating the power -developed in a Diesel cycle using air injection, which consists in causing the period of feeding fuel to the nozzle and the period of feeding injection air through the nozzle into the cylinder to overlap, so that these periods proceed concurrently for a part of said injection period,y and varying the length of the fuelv feeding period.

4. The method of regulating the power developed in a Diesel cycle using air injection, which consists in causing the period .of feeding fuel to the nozzle and the period of feedinginjection air through the nozzle into the cylinder to overlap so that they proceed concurrently for the major portion of said injection period, and varying the length of the fuel feeding period.

5. The method of regulating the power developed in a Diesel cycle using air injection, which consists in causing the period of feeding fuel to the nozzle, and the period of feeding injection air through the nozzle into the cylinder to overlap, so that these periods proceed concurrently for a part of said injection period, and varying the lengthl of said fuel feeding period by v the time of commencing the same.

6. The method of regulating the power developed in a Diesel cycle using air injection, which consists in causing the period of feedingfuel to the nozzle and the period of feeding injection air through the nozzle into thel cylinder to overlap so that they proceed concurrently for the major portion of said injection period, and varying the length of said fuel feeding period by varylng the time of commencing the same.

7. The method of regulating the power developed in a Diesel cycle using air injection, which consists in causing the duration of the period of feeding fuel lto the nozzle to vary by varying the time of its commencement, causing the period of air injection through the nozzle into the cylinder to commence atleast as late as the latest possible commencement of said fuel feeding, then to proceed concurrently therewith, and to terminate at least as late as the termination of said fuel feeding.

c. The method of regulating the power developed ina Diesel cycle using air injection, which consists in causing the duration of the period of feeding fuel to the nozzle to vary, hy varying the time of its commencement, causing the period of injection of air'through the nozzle into the cyl-- inder to commence slightly after the latest possible commencement of saidfuel feeding, then to proceed concurrently therewith and to fur-w shortly after the termination of said fuel feedmg.

9. The combination with a Diesel engine cylinder of a fuel injecting nozzle of the air injection type having a fuel chamber, and a valve vwhich controls injection from said chamher'into the cylinder; a fuel pump for Afeeding fuel to said chamber; and connections for actuating said pump and valve in timed relation and arranged to cause said pump to deliver fuel to said chamber, and while delivery continues to open said valve, then terminate delivery and then close said valve.

lo. The combination with a Diesel engine cylinder of a fuel injecting nozzle of the air injection type having a fuel chamber and a valve which controls injection from said chamber into the cylinder; a fuel pump for feeding fuel to said chamber; and connections for actuating said pump and valve intimed relation and arranged to cause said pump to deliver fuel to said chamber,

v and while delivery continues to open said valve,

-then terminate delivery and then close said valve,

the period between the opening of the valve and the termination of delivery, materially exceeding the period between termination of delivery and the closing of the valve.

11. The combination with a. Diesel engine cylinder of a fuel injecting nozzle of the air injection type having afuel chamber and a valve which controls injection from said chamber into the cylinder; a fuel pump for feeding fuel to* said chamber; a governor connected to vary the duration of fuel feed by said pump for varying the time of commencement of its effective stroke; and connections for actuating said pump and valve in timed relation and arranged to cause said pump to deliver fuel to said chamber, and while delivery continues to open said valve, then terminate delivery and then close the valve.

12. The combination with a Die'sel engine cylinderof a fuelinjecting nozzle of the air injection type having a fuel chamber and avalve which controls injection from said chamber into the cylinder; a fuel pump for feeding fuel to said chamber; a governor connected to vary the duration of fuel feed by said pump by varying the time of commencement of its effective stroke; and connections for actuating said pump and valve in timed relation and arranged to cause said pump to deliver fuel to said chamber, and while delivery continues to open said valve, then terminate delivery and then close the valve, the period between the opening of the valve and the termination of delivery, materially exceeding the period between termination of delivery and the lclosing of the valve.

v13. The method of feeding fuel through an air im'ection Diesel fuel inlet valve having a fuel chamber subject to blast pressure, the valve controlling ow from said chamber to the engine working space, which consists in feeding fuel to said chamber, then While said feeding continues opening said valve, then terminating the fuel feed to said chamber and closing said valve.

14. The method of feeding fuel through an airinjection Diesel fuel inlet valve having a fuel chamber subject to blast pressure, the valve controlling flow from said chamber to the engine s A working space, which consists in starting feeding fuel to said chamber while said Valve is closed,

.then while said feeding continues opening said valve, thenv terminating the fuel feed to said BRUNdv. E. NORDBERG.

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