US2591892A

US2591892A - Charging device for internalcombustion engines

Info

Publication number: US2591892A
Application number: US700415A
Authority: US
Inventors: Townshend Ernest Frederi Ryder
Original assignee: Individual
Current assignee: Individual
Priority date: 1945-10-05
Filing date: 1946-10-01
Publication date: 1952-04-08
Anticipated expiration: 1969-04-08

Description

5 Sheets-Sheet 1 -Hfw'l Attorneys.

ANS

Inventor R. T21 WNSHEND April 8, 1952 E. F. R. TowNsl-IEND CHARGING DEVICE FOR INTERNAL-COMBUSTION ENGINES Filed OGL. l, 1946 April 8, 1952 E. F. R. TowNsl-IEND 2,591,892

I CHARGING DEVICE FOR INTERNAL-COMBUSTION ENGINES Filed Oct. l, 1946 5 Sheets-Sheet 2 Attorneys April 8 1952 E. F. R. TowNsHEND 2,591,392

` CHARGING DEVICE FOR INTERNAL-COMBUSTION ENGINES Filed Oct. l, 1946 5 Sheets-Sheet 3 Inventor April 8, 1952 E. F. R. TowNsHEND 2,591,892

CHARGING DEVICE FOR INTERNAL-COMBUSTION ENGINES Filed Oct. l, 1946 5 Sheets-Sheet 4 I -o Inventor 1| l v v I -rnesf FRToQnsh'nJ elAttorneys I' April 3, 1952 l:l F. R. TowNsHEND 2,591,892 v CHARGING DEVICE FQR INTERNAL-COMBUSTION ENGINES Filed oct. 1, 1946 5 sheets-sheet 5 7g j A'tlorney s Patented pr. 8, 1952 Ernest Fredjcrick- Ryder Townshends.. Waterlooville, England?.

Applicatonoctober '1, 1946,1Serial No; 70m/ 415i InGreatiBritain October/5; 1945" This.; invention.. malatesffto..-F internalfA combustion. engines. in.. particular to; those.. which;` operate.; wholly.; partially on` occasionally: upon.; gasa andi whlethe; applicationshereinafter.y to; bef. der

scribedis...to;.a;i railiizfw` locornotiyefengine,- ila-Willv beA understood.. that.v the.: invention; is). canaille; of. applicationY iniotherfelds.; FluittherlllOre.j while thisinyention; is.partcidarlxzfdesignedA for? use.: inv

Q nefobjectgoi'.the:present-invention:.isftorepror` duce.; an` internal, combustion. engine.` an aps proximation. to-` or an improvement. upon.Y the: torque: speed characteristics. of the,4 conventional steaanrlocomotiveuto enablertheinternal combus-` tions.engine-.to` beidirectlycoupled .to the.. drivingl wheels: ofv ai locomotive.A and: thus.. to; avoid.. the? complications,i weight, cost: andi losses7 inherent..v

imams-form of indirecudrivei.

The-main.. requirements.; arethat the, inter-nal combustion., engine: should:v beginn to.V funetionf.

satisfactorilyassuchLWhile still. al1-,rest and.T that;

the torque exerted While at rest and upgtofa; .modera-tie; speed. shouldl be; a, maximum.` Thereafter-fthetorquemay diminish as:speedincreases.` The,A invention. therefore. consists broadly; in.

the:provision;` of` means iso-secure. high` torque, at, starting., and while accelerating., during., which..

pressed., air,v is drawnf upon.. in. an economical manner.. This. may take; place; in twophases,`

which will be, referredto as starting; and. boost:- ing... lt/Ieans..mayt alsobe provideditomaintain a.)

high.. torque at low.. and. medium, speedsywheniit is; not.; permissible further. to.. exhaustv the stores of` compressediarij ThusA according.. to. one. feature.. of.' the present invention.aniinternal.combustionengine includes,-

means..l capable. of., operatingk when the, englne...is..

stationary, for. introducing,vv a. charge` of. com..-

pressedr air; intotthexcylinden. means.- for, therer aater` introducingiuel into...the saidr charge.n of; air inthe cylinder, and. meansrforfigniting, the fuel` as.;iteriter-sr the cylinder.. The., admissioniof; ain

may, be., controlled. by. a metering.2 device which.4

automatically, cutsyroffi the, sunlllt when.. a., plee determined.' quantity. has. passedi.. rirespeotil/.Qs Ofi the engine speed. The metering;deycemreferyn. ably. controlstheadmission'xof i filelwll; @Si :..e admission-poi staining: ain.. and; man' orr exam' e;- comprise. an.. ain-drinnen Iriotor` having. rsdu g; valves-both;on;itsfinlet;anliideliyernSidesiondian; engine air admissionivalilewarranged toghe. ksedg byi-apredeterminedicotatiomonthemotorl. 6.01.1.-

veniently the: metering;` dev of operates; through'. servo-ri'iechanisrn, for example contact,s and;` ai solenoid.

It.; isV de sirable.l during.; this nhaset to@ provide means for controlling the combustion pressure-i. Thus a. funtnep feature of. the;` inyentionf` is-ithe provisionfofameans forrautomaticallx @.Ontrollns. the rate of; admission; of.. fuelin, aocordancer.with2 the pressure in the enginefcyglindepsoas,toepneg. vente.` the latterrising.L above.: 2a I J.1 %d.te.Illnd4 figure.. Such means maycomprise.y alll auxliamc cylinder containing-l. a; piston1 sulojvect44 to. engine.:`

cylinder pressure tending to mQVfat away-from.;

aastopagainst a-resilient.f0rc.e, the. filel'injection valve; being, socontrolledi by the,v piston;- thatii-ts.. opening is reduced if the piston is displacedifigoin, its stop.

When the engine has in thisway been setvin; motioma more economical cycl'e;wl'iich-rnayabey termed boosting; is adopt-,edf 'I hns a further feature ofthe invention-isthe-provisionofmeans. for introducingfprecompressect'air-intothe-cylin-H der1 late in theV compression stroke and; thereafter injecting fuelfto` gvive -a high' mea-ri pressure? without' excessive maximum@ pressure ortem-N perature. The starting air valve may be used` for-admittinglthisdelayedlsuperchargea The=ain for this boost may be supplied from a high-prese sure reservoir-through af reducing valve andE ans 4 equalising chamber, so that if` at low speed'ssthe cylinderl pressure exceeds the; pressure, setting;V of theV reducing. vali/e while? thegstanting ainvalvef; isopeniain can be. returnedfromthe cylindentoi. the. eoualisine, chamber.L to prei/.ent1over-c.hareingj o f. thecylinder.. v v

During normal running, when-itsxis1 clearlyirnf. practcableto continuato drawr unonissippliesiof compressed .anthcisuperchareo admittedat the beginning.. 0i the compressione stroke as usuali... is 4supplied.from anexhaustedrivenzturb. owen.. while scavenge air is suppliedloygan, en riyeni. scavenge-vair. pump..` l

3 At higher speeds an excess of power and of supercharging air may become available and Vpart of the scavenge pump output may then be ,usedin conjunction with a second stage air compressor to pump up the air reservoirs, the excess Further features of the invention will bel apparent from the description given hereafter.

The invention may be carried into effect in various ways but one arrangement will be described by way of example with reference to the accompanying drawings in which Figure 1 is a schematic diagram showing the system of a two stroke gaseous fuel internal combustion engine suitable for direct coupling to the wheels of a locomotive,

Figures 2 to 5 are typical theoretical indicator diagrams illustrating a starting cycle (Figure 2), a boosting cycle (Figure 3), a heavy supercharging cycle (Figure 4) and, for comparison, an unsupercharged cycle, (Figure 5),

lFigure 6 is a diagram showing means for controlling the latest permissible cut off in accordance with supercharge and speed,

Figure 7 is a diagram showing the electrical circuit and timing system of the embodiment of Figure 1.

Figure 8 is an enlarged view of part of the embodiment of Figure 1 showing the hydraulic and pneumatic connections, with the electrical circuit removed for clarity, and,

Figure 9 is a greatly enlarged View, partly in section, showing the arrangement of components in and adjacent to the cylinder head of the embodiment of Figure 1.

In Figures 2 to 5 of the drawings, the following abbreviations are used for the expressions here indicated:

Pi represents pressure. V represents volume. TF. Abs. represents temperature in degrees absolute on the Fahrenheit scale. T. C. A. represents temperature of charging air. N represents compression or expansion index. Vc represents clearance volume. I.,M. I. P. represents ideal mean indicated pressure. v A. M. I. P. represents actual mean indicated pressure. B. M. E. P. represents brake mean eiective pressure.

The expression used in Figure 2 charge 4/1-1-454 B. t. u./lb." represents a supercharge of 400% added to the normal charge to which total air charge 454 British thermal units of heat are added per pound. Similar expressions are used in Figures* 3, 4 and 5.

Each of the Figures 2 to 5 bears reference numbers I, 2, 3, 4, 5 and 6 at various points on the cycle shown in the figures, and underneath each is a table giving the temperatures reached at these points in the cycle.

It will be observed that whereas in Figures 2,

3 and 5 the index N is the same for expansion and compression, in Figure 4 the compression index between 3 and 4 is given as 1.2, whereas the expansion index between '6 and 1 is 1.4.

Figure 5 enables a comparison to be made between the performance of the engine described below when operating on any of the cycles of Figures 2 to 4, and the performance of an ordinary supercharged internal combustion engine operating at maximum power between the same limits of temperature and pressure.

In practice the engine might comprise a horizontal two-stroke cycle engine of several cylinders (of which one only is indicated in the drawings), the pistons being connected to cranks on the driving wheels and axles by means of connecting rods. Connected to this engine and forming a part of it, for example, horizontally opposed to it, is a crank-driven dual purpose air pump, which functions at one time as a scavenge pump and at another time as the first stage of a starting and boosting air compressor. The second stage of the latter is preferably gear-driven from one of the axles. Above this engine may be arranged several air reservoirs, to contain air at a maximum pressure of some 450` lbs. per square inch, and the exhaust gas-driven turboblowers, auxiliaries and control gear. In the tender of the locomotive is carried the fuel, which may consist of coal gas or other inflammable gas, such as methane, either contained in metal cyllnders under high pressure, or in the liquid state in a suitably insulated tank, or otherwise. If the fuel is carried in the liquid state provision must be made to evaporate it under pressure, as by means of a small exhaust gas single-tube boiler.

The conditions of use of such an engine demand widely different characteristics depending on the particular circumstances, and the engine shown is arranged to function in accordance with three different cycles, referred to herein as starting, boosting, and normal running, as well as a variation of the last of these. Briefly, during the starting cycle a metering device measures out a suitable charge of compressed air which is admitted to the cylinder and this is immediately followed by a charge of compressed gaseous fuel which is injected into the charge of air in the cylinder, and ignited as it enters, by means of an injection and ignition device similar to that described in British patent specification No. 527,612.

The starting cycle is capable of functioning while the engine is at rest and serves to set it in motion and give it some initial acceleration. When the engine has gained some speed the arrangement is changed over to the boosting cycle in which a charge of cold compressed air from a reservoir is admitted to the cylinder late in the compression stroke and the fuel thereafter injected into it and ignited by the same fuel valve as before. With further increase of speed a further change is made to the normal running cycle in which the supercharge is introduced at the beginning of the compression stroke.

In the particular arrangement shown in the drawings, a two-stroke engine vcylinder 65 is equipped with a fuel injection-ignition valve 6l, as described in the before-mentioned specification, excepting that the hydraulic relief valve (numbered 15 in that specification) is dispensed with. The fuel injection valve'is described in detail in the prior specification, but briefly as indicated diagrammatically in the accompanying drawings, it comprises a needle valve which can 1 varies the extent to which the valve can open.

The hydraulic chamber I3 in the valve 6| come municates `directly through passages I4 and I6 with a hydr-aulic distribution valve 62 in connection through pipes |86 and |81 with respectivelya hydraulic accumulator |33 and a tank 64. The distribution valve 52 is of a balanced, piston type. It is arranged to be operated by a solenoid 65 acting in opposition to a spring |89.

In4 order to secure Lthe proper timing of the injection and ignition of fuel, electric current is supplied appropriately to the solenoid 65, through any suitable timed switchgear such as a camswitch or rotating contact segment. The use of a pair of rotating contact segments in series makes it possible readily to vary both the beginning and end and the duration ofl injection. As shown the switchgear t consists of a pair of brushes 61 and 1|) bearing respectively on a slipring 68 and avsegment 69 attached to it. lThis switch is connected in series with another similar assembly |60 comprising brushes 1| and 12. The sliprings and their associated segments are suitably insulated and mounted on a cam shaft 89,' by which they are revolved at engine speed. Segment brushes 1E) and 12 are arranged to have a measure of angular adjustment about the camsh'aft, whereby the timing of admission and cutoff can be varied, and for the purpose of rever sal.

This electrical circuit also has in it a selector switch 13 the position of which determines whether the starting, boosting or normal running y cycle is selected. When starting this switch is so placed as to introduce into the circuit a further automatic switch 14 controlled by an air metering device presently to be-described.

To prevent the pressure in the engine cylinder from becoming excessive during starting the rate at which gas is injected by the valve 6| is automatically` controlled by a pressure regulator. This consists of a piston 15, subject on one side to pressure from the engine cylinder and on the other side to an opposing pressure applied in any suitable manner. The piston 15 is connected to the sleeve 1 which limits the lift of the valve 6| in such a manner that when the piston 15 moves outwards the sleeve I moves inwards, thus reducing the lift of the valve and therefore, the rate of injection of gas. In practice the piston 15 may carry piston rings and may terminate in a mitre head which normally mates with acomplementary seat in the cylinder head as shown. The external load may conveniently be applied by means of air pressure and spring pressure, a combination which can be arranged to give to the regulator the vrequisite degree vof sensitivity without introducing excessive bulk. As shown, the air pressure is derived from an air vessel 11 through a pipe ISI' and applied to the piston 'I5 through a larger piston 16 upon which a spring 18 also bears.

The connection between the piston i6 and the sleeve 1 may be made in several ways, for examplezit may be made hydraulically as shown in the drawing. Here the sleeve 1 is split, the lower part forming a floating, annular piston 82 which is actuated by hydraulic pressure from a cylinder 83 containing a pistond actuated by the piston 16. The tank 54 is connected through pipes |82 and |83 to the cylinder 83 (as shown best in Figs. 8 and 9) and through pipes |82 and |84 and a non-return valve |85 to the split sleeve 1.

For the purpose of admitting air .both when starting and when boosting the engine cylinder 60 is provided with a starting and boosting air valve 86. This is operated by hydraulic pressure from the hydraulic accumulator G3,.through the medium of a solenoid-operated distribution valve 81, which, when the selector switch 13 is setto start is controlled jointly by a single electrical cam-switch 88, similar to the cam-switch 65, andby a switch Bil controlled by the air metering device mentioned above.

The air-metering device consists of a positive displacement air motor 9| of vane or other suitable type through which they starting air passes from a reservoir 92 on the way tothe valve 85 and so to the engine. vOn the inlet and delivery sides respectively of the air motor 9|, are two automatic pressure reducing and controlling

valves

93, 94, so designed as to keep the inlet'and delivery pressures of the motor approximately constant, the mean pressure required here being substantially below that normally 'obtaining in the starting air reservoir 92. A shut-olf valve 95 and a throttle valve 96 are also provided. VThe air motor 9| is arranged to drive a flange 91'on a.

shaft |58 through gears I5?. The flange 91'drives through an electromagnetic `clutch 98a second flange which is urged by a spring to return to a datum position whenever the clutch is disengaged. The latter flange carries a'projection 99, arranged to engage a pivoted contact arm |00, after the clutch 98 has turned through a certain angle, and move it against the action of a spring IBI. The arm lili] carries at one end one contact of a normally closed switch for operating the air .valveand at the other end one contact of a normally open switch ilifor operating the fuel valve, and one contact Iof a normally open switch |93, for energising alholding coil |04. The second contact of the switch 9|) is supported by a spring |92, which is displaced by the force of the spring lill, and the adjustment of the contacts is such that when the arm IBG is moved (by the projection S9 of clutch 98) the switch |93 makes before the switch .14 makes or the switch 9i) breaks.

The electromagnetic clutch is connected in parallel with the airev'alve-controlling.solenoid 81 `and in series with'the switch 90 and the cam switch 88. Hence if and when the camswitch is closed (and the selector switch placed in the starting position) the air valve will be opened and theV clutch engaged so that as'the air passes into the cylinder the pin 99 will move towards' the contact arm |09. After a predetermined movement, corresponding to a predetermined metered charge of air, the arm |90 is swung in a clockwise direction (as viewed in the drawing). This first closes the switch |99, which is connected in series`with` the holding coil Iilt` and .the fuel cam switches 56,'and thereby holds'the arm |09 in'its clockwise position. until the circuit isk broken by the fuel cam switches 69. Next the switch is opened, closing the air valve and releasing the electromagnetic clutch which flies back to its ini- 75 fuel which continues, under theV control of the pressure limiting' device, until the fuel cam switches break circuit, closing the fuel valve and releasing the contact arm from its holding coil.

For use in the boosting cycle the air valve 36 can also be connected through a stop valve |00, an equalising chamber |01, and a reducing valve |06 to a boost air reservoir |05. Stop valves |08 and 95 are interconnected, so that when one is open the other is closed. When boosting, the air-valve-controlling solenoid 81 is connected, by a switch I0, in series with a single boosting camswitch` |09 (similar in construction to the camswitch 65), the selector switch 13 in the fuel and air valve circuits being simultaneously moved to the normal running position, thus cutting out the cam-switch 88 and the air meter switches 90 and 14. 'I'he boosting cam-switch |09 times. the air valve 86 to open and close late on the compression stroke of the engine.

Two separate rows of exhaust ports, and ||2, are provided towards the outer end of the engine cylinder 60, and these are uncovered successively by the engine piston, ||3, on its outward stroke. The inner ports which are the rst to be uncovered, communicate through nonreturn valves ||4, with an ante-chamber of an exhaust gas turbine IIS, which exhausts to atmosphere by a pipe ||1. The second row of exhaust ports l|2 communicate with the atmosphere through pipes |18 and |19. The piston ||3 is connected to a crank-axle |20 by a connecting rod |2|.

The exhaust turbine ||8 drives a blower |33 which delivers compressed air to a manifold |34,

whence the air may be admitted to the engine cylinder 60 through a timed supercharging air valve |35, and supercharging ports |36, which succeed the scavenge ports on the inward stroke of the piston. The supercharging air valve may be hydraulically operated in a similar man-I ner to the valve 86, connection to the hydraulic accumulator 63 or tank 64 being made througha solenoid-operated distribution valve |31, controlled by an electrical lcam-switch |30, on the camshaft 00, in series with an isolating switch |39. The latter remains open when starting and boosting. In normal running the supercharging air valve |35 is timed by the cam switch |38 to open as the scavenge ports |26 are covered by the incoming engine piston ||3. A valve permits the blower |33 alternatively to supply scavenge air to the scavenge ports |26 in place of the scav enge pump.

To control the compression pressure under conditions of low speed and heavy supercharge means are provided for injecting water into the engine cylinder. For this purpose a chamber |4| f is put into communication with the engine cylinder through a pipe |42 and a sampling valve compression stroke.

|43 for a short period immediately on the completion of the supercharge. A water pump |44 operated by pressure from the engine cylinder 60 in conjunction with a spring, delivers water through a metering orifice |45 and a non-return valve |46 to a nozzle |41 which injects a spray of water into the engine cylinder 60 during the 'I'he metering orice |45 is controlled by the pressure in the chamber |4| which will vary according to the degree of supercharge. A spill valve |48 cuts off the supply of water to the nozzle |41 at the end of the compression stroke of the engine. The valves |43 and |48 are operated respectively by engine-driven cams |49 and |50.

Figure 6 shows an arrangement by which the pressure in the chamber |4| is also employed to indicate and to help control automatically the latest allowable point of cut-off, i. e. the closure of valve 6|, according to the degree of supercharge and tothe speed in normal running.

Moreover provision is made. by what may be termed a picking-up cycle, to supersede the output of the blower when the corresponding permissible cut-off is insuiucient. This is achieved by connecting the manifold |34 to the boost reservoir |05, through a reducing valve |52 and an accelerating air valve |53, a non-return valve |54 in the blower discharge pipe |55 preventing a reversal of iiow through the blower. It is proposed to link the valve |53 to the cut-off controls in such a way that when in normal running the cut-01T is increasedmanually beyond the point corresponding to the pressure in the chamber |4 the valve |53 will open, admitting suiiicient air to correct the fuel/air ratio and thus providing the volume of exhaust gas necessary to accelerate the turbo-blower rapidly to meet the new conditions.

Gas fuel is supplied to the valve 6| under pressure from a gas reservoir, or bottle, |56. The hydraulic accumulator 03 is kept charged by an hydraulic pump |8|, driven by an electric motor |62, automatically regulated according to the level of the fluid in the accumulator.

The sequence of operations while starting and accelerating to full speed may be described as follows. Considering the engine and train to be initially at rest, and the piston I I3 to be just beyond its inner dead centre, gas fuel is supplied to the valve 6| (which is closed) under pressure from the gas reservair |56 by opening the stop valve |63. The

valves

95 and 98 are then opened and the switch 13 set to start. The consequent fiow of electric current through the switch and cam-switch 88 energises the clutch 98 (causing it to grip the flange 91) and the solenoid of the valve 81, which opens. Thereupon the Valve 86 opens and air flows into the cylinder 60 through the air motor 9|, which revolves and turns the flanges 91 and 98 through the gears |51. The air pressures before and after the air motor 9| being held approximately constant by the regulating

valves

93 and 94, a certain number of revolu tions of the motor 9| will represent a certain weight of air. When the required air charge has been delivered, the stop 99 carried on the clutch flange 90 touches the contact arm |00 and revolves it on its pivot, causing the switch |03 to make, thus energising the electromagnet |04 which attracts and holds the arm |00 whereupon i the switch 90 breaks and the switch 14 makes, in that order. Current now ceases to flow in the solenoid of the valve 81, causing the valve 06 to close, and in the coils of the clutch flange 98,

vthexpiston covers the. ports I l2.

which, being releasedv from the flangev 91., immediately returns toitslorignalposition (under the action of the before-mentioned spring) where it remainsuntil the. beginning of the next cycle. The closing of the switch 14 allows electriccurrentto. iiow through the solenoid 65` and camswitches |60 andA 66.. The. valve 62 therefore opens, causing the fuel valve 6|. to. open andto inject. gasfuel intogthecold compressed. air in the cylinder 6|), whereupon thev fuel is ignited fromVv the beginning of injection by` the ignition apparatus incorporated inthe valve 6L, as described in British patentspeciflcation No.V 527,612.

The piston |13 is nowin motion, .but at low speedstherate of addition of heatwillilbe such as to cause the. cylinder pressure. to. rise despite the displacement ofthe piston; Ata predetermined cylinder pressure (governed by the pressure. in the air vesselA 11) the pressure regulator piston 15 willbegin to move outwards,` reducing. the lift of. theI valve 6 I (through, the linkage 'already described) and so. limiting'they rateof injection of fuel that a given maximum cylinder pressure is not exceeded. Injection of burning fuel` continuesuntil thepoint of cut-off is reached, which is governed by the setting of the brushes aboutl the cam-switches 6B and |60. Expansion then takes place and the piston moves forward untilA the exhaust. ports ||I are uncovered,A whereupon the majority of the cylinder contents, escapes in a surge to the turbine ante-chamber l l5, reiiuxbeingv prevented, by vthe valves II4.I From the ante-chamber H5, the exhaust gasesr pass to atmosphere through the turbine I6, accelerating it in their passage., The. remainder of the cylinder contents, escapes directlyto atmosphere as In; the meantime the scavenge pump |22 hasA completed a stroke and has delivered air under pressure. to the air trunk |24. This air now entersthe cylinder. 6.6 through the non-return valves |25, drivingout what. remains of the exhaust gas and sup'- plying a freshr charge. Compression then .takes l0 charging. Atv low speedstoo much air will at first enterthe cylinder when the valve 86l is opened. 'Ihe excess is displa'cedby,- the piston andis accommodated in the chamber |01 withbut slight risein pressure. At a higher speed the desired quantity will have entered as the valve 86 closes. Preferably boosting should cease at this higher speed. Above this speed the cylinder pressure as the valve 86 closes would become progressively lower and the degree of supercharge would tend to decrease in inverse proportion to the speed;

Boosting may, howevenbe continued for so long as sufcientair pressure remains in the boost reservoir |05; the final speed depending on the Weightof the train and on the grade., a

To change overfrom boosting to normal running; theswitch II Il is opened and the switch i |39 isclosed, causing the starting air valve 86- to remain closed andl the supercharging air valve"` |35 to be brought into operation. NormalA supercharging nowy takes place,l ther charge; being supplied by` the exhaust turbo-blower., IIS, |33, through the supercharging air valve L35 and the ports |36; scavenge air being supplied normally bythe scavenge pump |22.` The degree o f supercharge will now tend to vary inversely as the speed, owingvto `the tendency of the proportion of exhaustgas trappedin the turbine ante-chamber |I5, by the reflux valves |I4, to vary in this manner. Q

It may alsobe notedthat, at speeds above those atA which' the vpressure regulator 15 comes into action, for a given cut-ofi, the quantity offuel injected and, therefore, the out-putof the engine, willvary inversely as the speed.

No waterY injection takes place during starting and boosting, norat moderate and vhigh speeds in ynormal running, because thepressure in the chamber I4I (which i'sput into communication with the engine cylinder 60 by the sampling valve |43 early on the compression stroke) isin'suicient to open the water metering orice I l5 againstfthe place. and the next cyclebegins. The maximum pressures reached during thecyclemay bewidely varied by adjusting the pressure i-n the air vessell 11.` For instancethe first cycle onstarting may be. limited to a low maximum pressurey and subsequent cycles may have progressively higher maximum pressures; the. pressure in` vessel 11 being steadily raised from a. low to a high value over the starting period. The indicator diagram l of. Figure 2 for the starting cycle` is seen to bear opposition of a spring load.` In normal running if the speed should drop owing toH a steep ',gradlent, the degree of supercharge will steadily increase, as will the `pressure in the chamber III-I, until f below a certain speed water injection will `autoswitch Hc is ser to boese the veuve e5 is. shut f and the valve |68 is opened. The engine now functions on the more economical boost cycle typied in Figure 3, the valve. 86 being timed by the cam-switch HB9 to open for a short period late on the compression stroke. As `will. be clear lfrom Figure 3 the low temperature and high pressure` of the air so admitted to the engine cylinder' permits a heavy supercharge to be carried without exceeding normal maximum pressures, and allows of a considerable higher fuel/air ratio withi-nnormal limits of temperature than is practicable. with conventional methods -of supermatically begin and will vary in quantity with the degree of supercharge; The effect is to lower the compressionY pressure and temperaturek to such an extent as to permit very heavy supercharges and relatively high fuel/air ratios to be employed yvithin normal limits of pressure and temperature. This cycle, which is illustrated by Figure 4, may continue indefinitely and down to the lowest speeds. The pressure in the vessel I4| may also be used to help regulate the maximum permissible cut-off according to the amount of supercharge and the speed as described below in connection with Figure 6. A

If speed is deliberately reduced, as for a signal `checlg'by shifting the

camfswitch brush

10 or 12 so as to reduce or prevent. the injection 'of fuel, the turbo-blower will `slow down and the pressure in the chamber I 4| will drop correspondingly..y To re-accelerate without'haying recourse` tor boosting, the valvev |53. may be linked to, the fuel cut-off controls in such a way that. if they are set to inject more fuel than that corresponding to .the pressure in the chamber |4|, the valve' |53 will open. By this means the `fuel/air ratio will be corrected and the turbo-blower accelerated rapidly to meet the. new conditions. Such anarrangement is shown diagrammatically in Figure 6 in which movement-of the control lever 200,

accises which moves over a quadrant 20| to vary the cutopened, to admit air from the reservoir 92 to operate the pressure-operated valve |53., Thus if the control lever 200 is up against the stop 202 the valve |53 will be opened.

The position of this stop is determined in accordance with the degree of supercharge, as indicated by the pressure in the chamber |4|, and, at moderate and higher speeds, in accordance with speed. Thus the pilot valve 203 is carried by a sliding rod 204 urged to the right (as seen in Figure 6) by a spring 205 and controlled by a floating lever 206. O'ne end of the latter is connected toa piston rod of a piston 2|0 in a small auxiliary cylinder 2|| connected to the chamber `|41 through a Valve 2I2 coupled to the valve |54 to open and close with it.

Hence if the valve |53 is opened to supply super-charging air from the reservoir the nonreturn valve |54 and with it the valve 2l2 will close and remain closed until the blower has speeded up enough to re-open the non-return valve. Only then will the valve 2|2 re-open and .allow the auxiliary piston 2|| to take up an altered position corresponding to the altered degree of supercharge.

The other end of the fioating lever is connected to a governor 220 provided with a stop 22| so that below a predetermined speed it does not affect the position of the oating lever.

To bring the engine and train to a standstill, fuel injection is stopped by opening the switch 13, the valve |3| is opened and the valve |30 is closed. The scavenge pump |22 and the second-stage compressor |28 then act as a regenerative brake utilising the unwanted kinetic energy of the train to re-charge the air reservoirs 02 and |05 in readiness for the next start. l

What I claim as my invention and desire to `secure by Letters Patent is:

1. An internal combustion engine having starting means including means, capable o f operating when the engine is stationary, for introducing a charge of, cold precompressed starting air into a passed irrespective of the engine speed.

3. An internal combustion engine as claimed in claim 2 including a metering device which not only controls the admission of starting air but also controls the admission of fuel.

4. An internal combustion engine as claimed in claim 3 in which the metering device includes a -positive displacement air-driven motor having reducing valves tol maintain substantially constant pressures on both its inlet and delivery sides, and an air` engine admission valve arranged to be closed by a predetermined rotation of the motor.

5. An internal combustion engine as claimed in claim 4 in which the metering device operates through servo mechanism.

6. In an internal combustion engine, means for metering the supply of precompressed starting air to the cylinder and for thereafter operating the fuel valve, consisting of a positive displacement air motor in series with a constant pressure air supply to the cylinder, a movable part arranged to be driven by the air motor through a distance representing to scale the quantity of air which it is required to deliver to the .engine at one time, and after moving the said distance to interfere with the contacts of a servo mechanism in such a way as firstly to close the starting-air valve, secondly to open the fuel injection valve, in that order, and finally to re-set itself in readiness for a subsequent cycle.

7; An internal combustion engine having means for automatically controlling the rate of admission of fuel in accordance with the pressure in the engine cylinder -so as to prevent the latter risingabove a predetermined figure.

8. In an internal combustion engine means for starting-up on load including means for introducing a measured charge of starting air to successive cylinders, means for thereafter burning fuel in eachcompleted charge of air and means for preventing excessive cylinder pressure from arising however slowly the engine may move.V

v9. An internal combustion engine as claimed in claim 7 in which the means for controlling the pressure comprises an auxiliary cylinder containing a piston subject to engine cylinder pressure tending to move it against a resilient force away from a stop, the fuel injection valve being so controlled by the piston that Yits opening is reduced if the pistonis displaced from its stop.

10. An internal combustion engine having means for introducing a supercharge of cold precompressed air into the cylinder late in the compression stroke in addition to the normally aspired charge of primary air already being compressed by the piston to give a high total air charge without excessive air pressure or temperature, thereafter injecting fuel into the cylinder.

11. An internal combustion engine as claimed in claim 10 having a starting air valve for admitting air when starting, in which this valve is used for the admission of the precompressed delayed supercharge when running.

12. An internal combustion engine as claimed in claim 10 in which the air is supplied from a high-pressure reservoir through a reducing valve and an equalising chamber so that, if at low speeds the cylinder pressure exceeds the pressure setting of the reducing valve late in the compression stroke, air can be returned from the cylinder to the equalising chamber to prevent overcharging of the cylinder.

13. An internal comb'ustion engine as claimed in claim 7 in which the admission of fuel is also fcontrolled in accordance with crankshaft angle 13 14 timed sampling valve serving to put the chamber UNITED STATES PATENTS into communication with the engine cylinder for Number Name Date a period during the compression stroke and 734 220 Bryan et a1 July 21 1903 means for employing the pressure in this chamber 1 200519 Peterson oct. 10 1916 to control the position of the fuel cut-off regu- 5 114713361 Perrauu., Oct. 23 1923 m01* 1,528,665 Fischer P- Mar. 3, 1925 ERNEST FREDERICK RYDER 1,692,845 Kolb Nov. 27, 1928 TOWNSHEND. 1,856,024 Bchi Apr. 26, 1932 e lo 1,887,633 Geiger 1-- Nov. 15, 1932 1,887,634 Geiger Nov. 15, 1932 e REFERENCES CITED 2,010,469 Triebnigg Aug. 6, 1935 The following references are of record in the 2,093,592 Triebnigg 56131121, 1937 `1e of this patent: 2,243,883 Ramstad June 3, 1941