US2296268A - Charging device for internal combustion engines - Google Patents

Description

` Sept. 22, 1942. A. BC:H\l

CHARGING DEVICE FOR INTERNAL COMBUSTION ENGINES 5 Sheets-Sheet 1 Filed Nov. 25, 1939 .i 43 L i 1, 1l i f, n l

Sept. 22,1942. A. BUcHl 2,296,258

CHARGING DEVICE FOR INTERNAL COMBUSTION ENGINES I Filed Nov. 25., A19:59 i 3 sheets-sheet 2 Sepbzz, 1942. A. Boem 2,296,268

CHARGING DEVICE FOR INTERNAL COMBUSTION ENGINES Filed Nov. 25, 1959 s sheets-sheet s Patented Sept. 22, 1942 CHARGING DEVICE FOB INTERNAL COM a BUSTION ENGINES Alfred Bchl, Winterthur, Switzerland Application November 25, 1939, Serial No. 306,191 In Switzerland March Z8, 1939 1'4 claims.

This invention relates to charging devices for internal `combustion engines.

An object of this invention is to provide for4 the supply of air to an internal combustion engine, and normally charged by an exhaust gas turbine driven blower, by auxiliary blower means driven independently of the turbine so as to be operative under very low engine loads and during starting when the pressure developed by the exhaust gas turbine driven blower is inadequate .for the engine charging requirements.

A further object of this invention is to provide for the automatic transfer of the auxiliary blower output to the suction side of the turbine driven blower when the pressure developed by the latter is suilicient. H

A still further object of this invention is to provide for the delivery of part of the output of the'auxiliary blower to the suction side of the turbine driven blower even during starting orunder light engine loads and the other part directly to the engine intake. 4

Another object of this invention isto provide for the automatic. change over from charging of the engine directly by the auxiliary blower to the exnaust gas driven blower proportionately as the engine load increases and vice versa.

A further object of this invention is to provide for the control of fuel injection in the en-` gine cylinders in such manner that only cylinders which have previously been adequately charged with air will receive fuel.

Still another object of this invention is to provide for more efficient scavenging of the engine cylinders by utilizing scavenging air produced by the combined action of the two blowers for scavenging the cylinders.

Another object of the invention is to provide A that the scavenger air pressure supplied by the auxiliary blower will be higher than the resistance through-the cylinders even in starting so that no back ilow can occur.

A further object of the invention is to provide a blower for an arrangement of this kind having radially disposed impeller vanes and being free of diffusor blades whereby the blower driven directly by the engine will be operativeupon reversal of the engine.

Other objects of this invention relate tothe control devices for the blowers and conduits adapted to satisfy the charging and scavenging requirements of the engine under all conditions of operation thereof.

Other objects and advantages of the invention will be apparent from `the following description and illustration of the invention.

In the accompanying drawings several embodiments of the invention are illustrated by way of example in Figs. 1 to 10 so as to disclose their manner of operation.

Fig. -1 is a vertical section of a two cycle internal combustion Iengine operating in accordance with the invention;

Fig. 2 is a side elevation partly in section of the internal combustion engine shown in Fig. l;

Fig. 3 is a view of a modified detail of Fig. 2;

Fig. 4 is a side elevation partly in section of an internal combustion engine, the construction of which is modifled in several points from that of the machine shown in Figs. 2 and 3:

Fig. 4a is a view of modiiied details of Fig. 4;

Figs. 5 and 6 illustrate the invention as embodied in 'a i'our cycle internal combustion engine, in a side elevation and a corresponding end view respectively;

Fig. '7 shows a diagram indicating the variations of pressure in the two kinds of blowers and in the exhaust as turbine;

Figs. 8 and 9 represent diagrams indicating by way of example the variations of pressure in the exhaust conduits of a six-cylinder two-cycle internal combustion engine, and

Fig, 10 indicates schematically the corresponding positions of the cranks of tne crank shaft. Like numerals or characters denote like machine parts in all the figures. y

In Figs. 1 to 4 the numerals I, 2, 3, l, 5 and 8 designate the cylinders of an internal combustion engine representing a first embodiment of the invention. The engine is provided with a frame 1.

In Fig. 1 the piston 8 of the cylinder I is shown in section, the forces acting inthe piston being transmitted to the crank shaft I!) through a connecting rod 9. The engine illustrated is a-twocycle engine in which the scavenging and charging air enters through slots Il arranged in the cylinder, while the exhaust gases leave the cylin` der through an exhaust valve I2 located in the cylinder head. l

According to the invention, a vaned rotary blower I3 mechanically driven by the internal combustion engine is provided as well as a vaned. rotary blower I5 which is driven by an exhaust gas turbine I I, fed with exhaust gas from vthe engine through exhaust manifolds 43, Il, mechanically independently of the internal combustion engine. As shown in Fig. 1, the drive of the blower I3 is derived from the crank shaft III ci the engine through the intermediary of three gear wheels I 5. Il, Il, so that the blower I3 attains a high speed even ii' the engine rotates only slowly. The blower I3 supplies its delivery of charging air on the one hand through a pipe connection I8 directly into the intake device 20 of the internal combustion engine which device communicates with the entrance slots II unchecked. The mechanically driven blower I3 in turn is provided with a pipe connection 2i and a branch connecting conduit 22 leading to the entrance pipe connection 23 oi' the exhaust gas turbine driven blower I5. I'he latter blower supplies its delivery air likewise into the intake device 20 through an exit pipe connection 24. The rotors oi' both blowers I3, I5 are indicated in Figs. 2 and 3 in dotted lines showing the blades to be radially directed for delivery by action of centrifugal force.

Fig. 2 shows the manner in which, according to the invention, the control ot the air delivered by the two blowers is effected. An intake device 20 serves for the whole engine. The pipe bend 24 on the exhaust gas turbine driven blower I5 leads into this intake device without being provided with any shut-oi! means. The pipe bend I8 on the vmechanically driven blower, however, supplies its delivery air via a shut-oi! device 25 into 'the intake device 20. 'I'he construction of the shut-ofi device 25 is such in this instance that the device opens or closes and thus effects or interrupts communication between the mechanically driven blower I3 and the intake device dependent upon whether an excess of pressure is present on the side of the blower or on that o! the intake device.

The amount of delivery air to be supplied by the blower I3 to the blower I5 is conducted through the pressure pipe connection 2l of the blower I3 and the branch conduit 22 into the suction pipe connection 23 of the blower I5.

The manner of operation of the embodiment shown in Fig. 2 is as :follows:

On starting the engine the mechanically driven blower is immediately set in motion also, due to being coupled to the engine, and thus begins to deliver at once in consequence i' which the automatic shut-oi! device 25 opens, so that at least part of the air delivered by the blower passes into the cylinders through the intake device 20 and the entrance slots I I. In this way the starting of the engine and the scavenging of the cylinders is rendered possible. The exhaust gas turbine driven blower I requires a certain time for acquiring a speed suiiicing for overcoming its interior resistances and these ot the connecting conduits and for the subsequent delivering. As the loading, that is, the speed of revolution of the internal combustion engine increases the speed of this blower is increased more and more and after a certain condition o1' operation has been reached the delivery pressure produced will be higher than that of the blower I3. When consequently the pressure in the intake device 20 rises above the pressure that can possibly be created in the blower I3 under the prevailing conditions o1' operation, the automatic shut-ofi device 25 closes, whereupon the total charge is supplied by the blower I5. Due to the particular construction ci the mechanically driven blower, the air delivery thereof is supplied to the pipe connection 23 of the blower I5, so that the former blower participates also effectively in the air delivery but only as a low-pressure stage and supplies its delivery to the internal combustion engine via the exhaust gas turbine driven blower, at which time al1 of the air supplied to the intake device 20 by both blowers is conducted through the common branch air conduit 22.

It will be seen that by this means an entirely automatic .operation' is rendered possible irrespective oi the condition of operation o1' the internal combustion engine. If the engine should be required to run all oi a sudden at no-load or under a small load only the speed o! the exhaust gas turbine driven blower decreases rapidly, again, in certain circumstances fc such an extent that the mechanically driven blower I3 produces a higher delivery pressure than the blower I5, in such manner, that the total or the principal amount oi' the air delivery is effected by the blower I8 again. Fig. 2 shows the mechanically driven blower I3 to be provided with a centrifugal blower rotor 28.

Fig. 3 shows in a partial section a somewhat modified construction of the air control for the two different kinds of blowers I3 and I5 combined with an internal combustion engine which otherwise corresponds to that shown in Fig. 2. In the delivery bend I8 of the blower I3 first a damper 21 is included by means of which the portion of the air delivery supplied into the intake device 20 of the internal combustion engine can be regulated. Further toward the intake device 20 an automatically operating shut-oil member 25 is arranged which closes automatically on the setting up of a Pressure in the intake device 20 higher than that in the delivery pipe bend I8 of the blower I3.

A throttling member 28 is shown to be further included in the branch conduit 22 by means of which the proportion of the air delivery of the blower I3, being passed into the blower I5, can be varied or even reduced to zero. On the suction side of the blower I5 a further shut-oilmember 28 is provided by means of which the blower I5 can be controlled for drawing in air directly from the atmosphere wholly or partially. In the former case it is advantageous to close the shut-off member 28, when the shutoii' device 29 is in open condition, in order that the total air delivery of the blower I5 may pass 'ninto the intake device 20 of the internal combustion engine through the delivery pipe bend 24. The coupled operating device 30 serves for controlling these two members 28 and 28 so that by shifting this device in the direction of the arrow shown in Fig. 3 the member 28 is opened and the member 29 is closed.

Furthermore, in the pressure bend 24 of the blower I5 a damper 3| may be included by means of whichvthe amount of air supplied in the intake device 20 by the blower I5 can be discontinued or varied. A shut-oildevice 32 arranged behind said damper 3i is provided for the event that the blower I5 draws in air from the atmosphere, while the delivery pressure of this blower has not yet reached as high a value as that produced by the blower I3. In such an event the shut-ofi device 32 shuts automatically to the `blower I5 and this shut-oil means opens automatically only, when the pressure produced by this blower` is greater than that in the pressure bend I8 of the blower I3.

If, however, the pressure produced by the blower I5, rises above that produced in the blower I3 the shut-ofi damper 25 closes and then the whole amount of air delivered into the engine 'I is supplied by the blower I5. The adjustment of the shut-oil members 2'I, 3i is effected by shifting shifted in opposite directions. i

Fig. 4 shows a somewhat different modification of the invention. In contrast to Figs. 2 and 3 in which the mechanically driven blower is inV verting the flow of air from the axial into the radial direction, in distinction from the radial blades shown in the same figure for the blower I5. By means of this drive the speed of the helical vane rotor blower can be varied in order to suit the requirements of vdifferent loads and engine speeds more properly and particularly for permitting for instance the blower to be driven at greater speed in starting the engine. for increasing the delivery pressure of the blower. 'I'he control of this variable speed gear, that is. the setting thereof to different speeds of the helical vane rotor blower can be effected by hand or in time with the fuel supply to the engine in any suitable manner. Suitable hand control means are shown in Fig. 4. A hand-wheel 50 is connected to a spindle I operatively connected with one end of a two-armed lever 52 the other end of which is pivoted to a forked control mem.. ber 53 of they variable speed gear 36. 'I'his control member4 is loosely mounted on the hub of the friction wheel 33" with both of its arms which wheelis slidably arranged on an intermediate driving shaft 54 with which it rotates by action of the friction wheel 36. The shaft 54 actuates a bevel gear drive 55 of the variable speed gear at 'different speeds dependent uponwhether the wheel 36" is adjusted by means of the handwheel 50 Vin one or the other direction radially of the wheel 36. The supply means for delivering the output of the two blowers I3, I5 is also somewhat modied. The intake device 20 of the internal combustion engine 1 is subdivided into three spaces 20, 20', and 20" by means of partitions 31, 38 (Fig. 4a) in each of these partitions at least one shut-oil. member, for example, a spring loaded shut-off member 39 is included which opens only when the pressure produced by the exhaust gas driven blower I5 is higher than that produced by the blower I3 at the respective condition of operation. To this end the delivery conduit 24 of the blower I5 is connected with the space 20' of the intake device by means of a conduit 40, as shown in Fig. 4. Alternatively, a conduit 4I may be inserted betweenthe delivery conduit 24 and a space 20" separated from the space 20 by a further partition wall 38 which also includes a shut-oil' member 39, as shown in Fig. 4a. Furthermore, an automatic shut-off device 25 is inserted between the blower pipe bend I3 and the intake device 20 in a manner similar to that shown in Fig. 2. i y

vThe manner of operation of the embodiment shown in Fig. 4 is as follows:

.If only one partition wall 31 having an automatically operating shut-off member 33 is provided the pipe bend 24 of the `blower I5 is connected with the intake device through the conduit 40, Fig. 4. In this case, for starting the engine. for example, only the cylinders 5 and l maybe supplied with fuel through the conduits 42, whereas-the cylinders I to 4 first operate without fuel injection. The blower I3 may, for

example, be constructed and dimensioned so as to be` adapted to deliver the supply of scavenging and charging air required for th cylinders l, I. Therefore, these two cylinders operate correctly during the starting operation. Dependent upon the adjustment of the throttling device 2l a. certain part of the air supplied by the blower I3 is delivered to the blower I5, and as the speed of the exhaust gas driven blower has attained a certain value also the delivery pressure of the blower I5 rises successively to a value higher than that produced by the blower I3. On this occurrence, which will take place the sooner the quicker the shut-off device 23 is entirely opened, the' valve 33 opens to the intake device 2l! and the automatic shut-off device 25 closes. From this moment the blower I3 delivers its entire output of air to the blower I5, whereupon the latter supplies the total amount of chargingand scavenging air for the internal combustion engine through conduit 40.

If, however, two partition walls 31, 38 are arranged in the intake device 20, 20', 20" (as shown in Fig. 4a) together with correspondingly mounted back pressure valves 33 and a corresponding supply conduit 4I for supplying the air delivered by the blower I5 into the space 20 of the 1ntake device, the outputv of this blower is still further throttled during the starting and running at small loads. The reason for this is that then charging and scavenging air is supplied only to the cylinders I, 2 whereas additional air is required to' be supplied the cylinders 3, 4 also only at a later time, when the member 39 arranged in the wall 38 opens. In thisycase the speed of the exhaust gas turbine driven blower increases more quickly, so that this blower can begin to deliver the total air supply after a shorter time, due to the initial demand on energy of a vane rotor blower being smaller at smaller outputs.

In Figs. 1 to 3 as well as in Fig. 4, the exhaust gas conduits leading to the exhaust gas turbine I4 are subdivided into two branches 43, 44 which are fed by the cylinders I, 2, 3 and the cylinders 4, 5, 6 respectively. The purpose intended by' this arrangement will be hereinafter explained in connection with the description of Figs. 8 to l0.

In Figs. 5 and 6, the invention is illustratively exemplified as embodied in particular manner in a twelve-cylinder four-cycle internal combustion engine. The twelve cylinders of this engine are arranged in two rows of cylinders I, 2, 3, 4, 5, 6 and I', 2', 3,'4, 5', 6 which are arranged relatively to each other in V-shape. In this engine a separate exhaust gas turbine driven blower I5, I5' respectively is provided for each row of cylinders, which blowers are arranged at the same end of the engine `1 and are driven by exhaust gas turbines I4, I4', respectively, mechanically independently of the internal combustion engine. The particularity of construction of this embodiment consists in that only one blower I3 mechanically driven by the internal combus- Qtion engine is provided, which blower is adapted of pipe cori-` to supply its air. delivery by means nections I 3, I3' and correspondina, r conduits 45, 45 to two admission conduits 20a, 20h of the rows of cylinders Ito G and I' to 6', respectively;

-via respective automatically operating shut-off members 25, 25. Furthermore, the blower I3 35. The exhaust manifolds 43,44 and 43', 44

collecting the gases from the various groups of three cylinders each lead separately into the turbines I4, I4', respectively. This arrangement operates in such manner that in starting the engine or during the engine running under small loads the mechanically driven blower I3 supplies its air delivery through the conduits 45, 45 and the automatically operating shut-off members 25, 25 respectively by means of corresponding admission ,conduits 20, directly into the combustion cylinders. Another part of the air delivery of this blower, however, is supplied into the admission pipe connections of the blowers I5, I5' through the branch conduits 22, 22', respectively. Only after the two blowers I5, I5 produce a higher pressure than that produced by the blower I3 in the admission conduits 20, 20 via the shut-oil members 25, respectively, the shut-off members 25, 25' close automatically and the whole output of the blower I3 is then received by the blowers I5, I5 and supplied by these into the internal combustion engine at a higher pressure.

By the particular mode of collecting the exhaust gases from groups of cylinders by means of separate manifolds leading into separate chambers of each of the exhaust gas turbines I4, I 4' considerable fluctuations of pressure are obtained in advance of the exhaust gas turbines, if the volume of these manifolds and the entrance port areas oi the respective turbines are accordingly dimensioned, which fluctuations are of particular advantage regarding the scavenging of the engine. At the same time, the exhaust gas energy required for driving the exhaust gas turbine driven blowers and for delivering an increased amount oi scavenging air can nevertheless be procured by accordingly proportioning the pressure impulses acting lon the turbines. The exhaust gases leave the two exhaust gas turbines I4, I4' through conduits 46, 46' respectively.

In the diagrams of Fig. '7, the pressures produced by the two blowers I3 and I5 are plotted against the loading on the engine. The reference character po represents the atmospheric pressure, whereas p1 designates the delivery pressure of the blower driven by the internal combustion engine, which pressure, according to the invention, is intended not to vary more than to a certain extent over the whole range of loading. In the example shown, this pressure decreases somewhat as the loading increases. The variation of this pressure depends mainly on the characteristic of the blower I3 for variable output. Let it be assumed that p2 designates the mean pressure of the exhaust gases in advance of the exhaust gas turbine I4. This pressure is relatively low lfor small loads and increases progressively, particularly as a consequence of the temperature of the exhaust gases increasing and of the air-fuel charge of the internal combustion engine increasing as the load onvthe latter increases.

Now, if the blower I5 would draw in air directly from the atmosphere the pressure would vary as indicated by p3. At no-load and operating at small loads this pressure is practically zero but increases more rapidly than the mean pressure pz in advance of the exhaust gas turbine required for driving the blower provided that the exhaust gas turbo-blower has a high efciency. In point A the ,two pressures pz and pa are assumed to be equal and the pressure p3 rises behind the blower I5 above the mean values p1 existing in advance of the exhaust gas turbine. If, however, the two charging blowers I3 and I5 cooperate as provided according to the invention, in such manner, that the blower I3 delivers at first only part of its output and subsequently the whole output into the entrance pipe connection of the blower I5, the pressure in the blower pipe connection 24 rises as long as no throttling takes place, for example, by action of the shut-off device 23, in conformity with the curve p4. If, however, such throttling takes place the pressure in the pipe connection 24 drops somewhat, for example, in conformity with curve ps. y

With this mode of operation, after a certain moment, the pressure in the pipe connection 24 attains a value equal to that in the pipe connection I9 of the blower I3. This moment is indicated-by point B. Due to the presence of the automatic shut-off device 25 in the pressure pipe connection I9 of the blower I3, this device closes as the load further increases and after a certain pressure sufilcing for closing this shut-off device has been reached, the whole output of the blower I3 is delivered into the blower I5, so that then the latter alone supplies in the intake 20 of the internal combustion engine via the pressure pipe connection 24. This operating phase is assumed to begin in point C. From this moment the pressure in the intake device 20 rises in the pipe connection 24 by taking its course through point D, in conformity with curve p4, so that the whole charging and scavenging pressure conjointly produced by the blowers I3 and I5 is then available for the operation of the internal combustion engine.

In Fig-s. 8 and 9, the pressure conditions existing at the delivery end oi the two blowers I3, I5 and in advance of the exhaust gas turbine I4 are illustrated at a certain load on a twocycle internal combustion engine 'I as shown in Fig. 2, while this engine performs one revolution. For the passage of the exhaust gases from out of the six-cylinder internal combustion engine l, the crank positions of the individual cylinders of which and the direction oi rotation of which are indicated in Fig. 10, the exhaust manifolds collect the gases from groups of cylinders, as shown in Fig. 2. Only such cylinders exhaust in the various separate exhaust manifolds up to and inclusive of their entry into at least one exhaust gas turbine the exhaust puis of which do not interfere with the scavenging in the cylinders connected with the respective manifolds.

Furthermore, the dimensions and volumes of these exhaust manifolds as well as the extrance port areas of the respective turbines are so chosen that at the beginning of the exhaust period the pressure in advance of the turbine rises above the total scavenging pressure created -by the two kinds of blowers conjointly, whereas during the scavenging period this pressure drops down to atmospheric pressure as nearly as possible. Since, in the example shown, the internal combustion engine is a six-cylinder two-cycle engine, wherein exhaust puil's take place after each angular range of 60, for the cylinders I, 2, 3 and 4, 5, 5, the exhaust operations of which occur always at langles of apart, separate exhaust gas manifolds Il respectively are provided. `In this way, with the total delivery pressure produced by the mechanically and the exhaust gas turbine driven blowers conjolntly, which pressure is thus amazes e S members are simultaneoiisly open." To this end, the miei membert or the individual cylinders are thus maintained open during this range of crank angle which is also represented by the stretches elevated, the cylinders can thus be more eifec- 4,J-I I. `Il, as illustrated in Fig. 8, the exhaust tively scavenged at relatively great loads.

The highly fluctuating pressure of the exhaust gases setting up in the exhaust manifold 43 at a result oi the conditions in the cylinders 2, I, 3

and the corresponding` pressure in the exhaust lines pz represent the mean value of the exhaust members close at point H, that is, earlier than the inlet members, which close at point K, a proper lling of the cylinders is ensured after the exhaust members are closed. f

The invention oifers the advantage that during starting and operatingat small loads in an internal combustion engine constructed according to the invention an appropriate scavenging and charging of the engine is more reliably ensured gas pressures pi' and pr". The pressure p1 indi- 15 ,and that at relatively great loads higher scavengcates the 'delivery pressure of the mechanically driven blower, and p4 the resultant pressure of the end pressures in the mechanically driven and the exhaust gas turbine driven blowers. These ing and charging pressures than usual are obtained. Furthermore, both -kinds of blowers are utilized substantially at the full efficiency availableV at all loads. A vane rotor blower driven pressures are more or less constant if between by the exhaust 8856s fIOm the internal Combusthe blower I5 and the inlet members of they internal combustion engine a space is inserted the volume of which varies between appropriate limits. As evident from Figs. 8 and 9, a scavenging phase E-F of a relatively long duration can be obtained for the internal combustion engine, by means of the mode of operation indicated in these ilgures.

For explaining the control provided, according to the invention, for the inlet and exhaust the Venous requirements 0n air delivery dulm members' the corresponding opening periods are indicated in heavy lines below Fig. 8. The upper lines G-H represent the vcrank angles during which the exhaust members are open. The lower 'lines J--K on the other hand represent the openspaced forwardly from thelower dead center of cylinder 2 at a range of crank angle of approximately 20. l The opening period endures up to a-rpoint spaced forwardly from the lower dead centerof cylinder I at a range of crank angle' somewhat larger than 30. l

Now, if, as proposed, the volume of the exhaust manifold and the corresponding turbine entrance port area are relatively small, the pressure p2 in the exhaust manifold `43 increases rapidly,

namely in this instance, above the value of the delivery pressure p. of the two blowers I3, I5

arranged in series with this mode of operation.

After this pressure has surpassed its maximum value it decreases, however, again so as to assume 35 loads.y

tion engine has the annoying characteristic ofl aspiring only small volumes at low speeds as setting up during starting and operating theinter- Y nal combustion engine at small loads.

By means of the invention it is, however, possible to deliver to the internal combustion engine a large amount of charging and scavenging air also under such conditions of operation although only at a low but sufcient pressure. In spite of starting and operating under relatively small and great loads, by means of the proposed auto-` matic changing over of supply paths without 'exi terior control the air delivery is adapted to all Since the mechanically driven vblower as well as the exhaust gas turbine driven blower have to supply greatvolumes of air during starting and operating at any load, in accordance with their output capacities, also the great drawback 40 of disturbance of operation by the setting up of a pumping eifect in the blower usually resulting from reduced delivery is eliminated.

What I claim is: l

1. Apparatus for supercharging the cylinders of internal combustion engines having air intake means for said cylinders, comprising a mechanically driven, varied, rotary, air blower an exhaust gas turbine driven, varied, rotary, air blower, separate air conduits connecting said different blowers individually with theair intake means of the engine, a common air conduit connected with both air blowers, a non-return valve member in the separate air conduit of said mechanically driven blower for automatically opening when said engine is in the initial condition of operation, thereby delivering part of the output of said mechanically driven blower into said engine intake means directly, and said valve automatically closing when the delivery air pressure its minimum value in the vicinity of the dead so of the turbine driven blower increases above that center of the cylinder I or forwardly from this center, which value should approach the atmospheric pressure as closely as possible, in order to subsequently increase again shortly after the opening of the exhaust member of the cylinder 3 e5 air conduit, and said mechanically driven blower Withthis course of the exhaust `gas pressure curve pz and that of the air pressure'curve p4 the result is obtained that inthe points E, F these pressures are alike. Between the points E, F,

of said mechanically driven blower at the higher power outputs of said engine, so that all of the air supplied to the intake means by said dinerent blowers is conducted through said common automatically delivers air to said intake means, in part, through said common air conduit again as the delivery pressure o'f said turbine driven blower decreases below that of said mechanically where the areas representing difference of presdriven blower at 10W engine POWer Outputssure are hatched, the exhaust gas-pressure p2' is smaller than the total charging pressure p4. Therefore, during this time the engine can be scavenged with precompressed air at the charg- 2. Apparatus for supercharging the cylinders of internal combustion engines having air intake means for said cylinders comprising a Vaned, ro-` tary, air blower mechanically driven by the ining pressure p4v when the inlet and the exhaust 75 terna! combustion engine, an exhaust gas turbine driven, vaned, rotary, air blower, separate air conduits connecting said blowers individually with the said engine air intake means, a common air conduit communicating with both oi' said blowers, pressure-actuated means responsive to the pressure of air delivered by the mechanically driven blower and also to the pressure of the air delivered by the turbine driven blower for automatically opening the air conduit connecting the mechanically driven blower with the air intake means of the engine when said engine is in the initial condition of operation, thereby delivering part of the air output of said mechanicallydriven blower into said intake means directly, and said means automatically closing the conduit from `the mechanically driven blower to said intake means when the delivery pressure of the turbine driven blower increases above that of said mechanically driven blower at the higher power outputs of said engine, so that all of the air supplied to the intake means by both blowers is conducted through said common air conduction means.

3. Apparatus for furnishing supercharging air for the cylinders of internal combustion engines comprising a mechanically driven, vaned, rotary blower driven from an extraneous source of power separate from the internal combustion engine, an exhaust gas turbine driven, vaned, rotary blower, separate air conduits connecting the air delivery outlets of said different blowers individually with the air intake means of the internal vcombustion engine, a common air conduit communicating with both blowers, a non-return valve member in said delivery air conduit of said mechanically driven blower for automatically opening when said engine is in the initial condition of operation, thereby delivering part of the air output of said,mechanically driven blower into said intake means directly, said valve automatically closing when the delivery pressure of said turbine driven blower increases above that of said mechanically driven blower at the higher power outputs of said engine, so that all of the air supplied to the intake means by said diierent blowers is conducted through said common conduit.

4. Apparatus for furnishing supercharging air for the cylinders of `internal combustion engines comprising a mechanically driven, vaned, rotary blower, an exhaust gas turbine driven, vaned, rotary blower, an air intake device having two separate intake chambers arranged on the internal combustion engine, air delivery conduits connecting each of said blowers with one of said separate chambers respectively, a shut-ofi device which'is pressure-actuated to its open position intercalated between said chambers, a branch air conduit communicating with both of said blowers, a`nonreturn valve member in the air delivery conduit of said mechanically driven blower, said valve being automatically maintained open during the initial condition of operation of a part of the cylinders of said engine for supplying the required amount of air charge into said intake device by said mechanically driven blower, said valve automatically closing by action of said turbine driven blower when the delivery pressure of the latter increases above that of said mechanically driven blower at the higher power outputs of said engine, so that all of the'A air supplied to the intake means by said different blowersis conducted through said branch conduit, and said shut-01T device is held open by action of the delivery pressure of said turbine driven blower so that the chamber connected with said mechanically driven blower is `in communication with said turbine driven blower by the effect of said pressure increase.

5. Apparatus for supplying supercharging air to the cylinders of internal combustion engines having fuel injected thereinto comprising a mechanically driven, vaned, rotary blower, an exhaust gas turbine driven, vaned, rotary blower, an air intake device arranged on said engine and having separate intake chambers, delivery air conduits connecting each of said different blowers with one of said separate chambers respectively, a shut-off device ,which is pressure-actuated to its open position4 intercalcated between said chambers of said air intake device, a branch air conduit communicating with both of said blowers, a non-return-valve member in the air conduit connecting its associated chamber with said mechanically driven blower, said valve, when open, supplying said chamber directly with a part of the air delivered by said mechanically driven blower sufficient for satisfying the air requirements for the initial conditions of operation of said engine, with part of said fuel supplied cylinders operating, and said valve, when closed by action of the delivery pressure of said turbine driven blower increasing above that of said mechanically driven blower at the higher power outputs of said engine, forcing said different blowers to conduct all of the air supplied thereby to t sure in advance of said turbine rises above the said inlet device through said branch air conduit, said shut-oil device being maintained open by said pressure increase.

6. Apparatus for supplying supercharging air to the cylinders of internal combustion engines comprising a mechanically driven, vaned, rotary blower, an exhaust gas turbine driven, vaned, rotary blower, said engine cylinders operating with scavenging, separate conduits providing communication between said blowers and the engine intake means individually, a common branch air conduit communicating with both blowers, a non-return valve member in the air delivery conduit of said mechanically driven blower for automatically opening when said engine is in the initial condition of operation, thereby delivering part of the output of said mechanically driven blower into said intake means directly, and automatically closing by influence of the operation of 'said turbine driven blower when the delivery pressure of the latter increases above that of said mechanically driven blower at the higher power outputs of said engine, whereupon all of the air supplied to the intake means by both of said' blowers is conducted through said branch air conduit, separate exhaust gas conduits leading from groups of engine cylinders, in which the exhaust periods do not interfere with the scavenging periods of other cylinders of the same group up, to and into the entrance of the turbine of said turbine driveny blower, the dimensions and volume of said conduits and the flow-area of the corresponding entrance ports of said turbine being so small that at the beginning of the exhaust period the prestotal resulting charging pressure of both of said blowers, whereas during the scavenging period said pressure is kept as much as possible below the charging pressure so that said cylinder groups will be scavenged most effectively for a relatively long time at said total pressure.

7. In apparatus for supercharging the cylinders of internal combustion engines, a mesaid cylinders having inlet-and exhaust ports, l

individual conduits providing communication between said different blowers with the ,intake means/oi the internal combustion engine, a common branch air conduit communicating with I both blowers, a non-return valve in the air delivery conduit oi said mechanically driven blower ior automatically opening when said engine is in the initial condition of operation, thereby delivering part of the output of said mechanically driven blower into said intake means directly, and said valve automatically closing under the inuence of the operation of said turbine driven blower when the delivery pressure of the-latter increases above that of said mechanically driven blower at the higher power outputs of said engine, whereupon all of the air supplied to the intake means by both of said blowers is` conducted through said common branch nconduit, exhaustgas conduit means interconnecting said engine and said exhaust turbine driven blower, means for driving said mechanically driven blower at a speed sufiicient to permanently maintain its delivery pressure at least somewhat higher l than the back pressure resulting from the flow resistance `set up in said cylinders, said exhaust gas conduit means and the turbine of Athe gas turbine driven blower preventing back ilow f exhaust gases from said exhaust gas conduit means into said cylinders while during the scavenging said inlet and exhaust ports are simultaneously opened. i

8. In apparatus for supercharging the cylinders of internal combustion engines 'a mechanically driven, vaned rotary blower, an exhaust gas turbine driven, vaned rotary blower, means providingindividual communication between both of said blowers and the air intake means of the internal combustion engine, a cornmon branch air conduit communicating with both blowers, a nonreturn valve in the individual air delivery Yconduit of said mechanically driven blower for automatically opening when said engine is inthe initial condition of operation, thereby delivering part of the output of said mechanically driven blower directly into the air intake means of the engine, and automatically closing under the influence of the condition of operation of said turbine driven blower when the delivery pressure of the latter increases above that ofV said mechanically driven blower at the higher power outputs of said engine, whereupon all of the air supplied to the intake means by both blowers is conducted through said branch air conduit means, the delivery pressure of said turbine driven blower being greater than that of said mechanically driven blower when said engine operates at said higher power outputs.l

9. In apparatus for supercharging the cylinders of directly reversible internal combustion engines, a mechanically driven, vaned, rotary blower having radial rotor bladesv but being devoid of iixed diiusor blades for avoiding the necessity of reversing means in said blower requiring to be controlled in conjunction with the Y conduit of said mechanically driven blower, said valve automatically opening when said engine is inthe initial condition of operation, thereby delivering part of the air output of said mechanically driven blower into the engine intake means directly, and automatically closing by action of said turbine driven blower when the air delivery pressure oi the latter increases above that of said mechanically driven blower at the higher power outputs of said engine, so that all of the air supplied to the intake means by saidy diierent blowers is conducted through said common branch air conduit.

l0. Iny apparatus for supercharging the cylinders of internal combustion engines a mechanically driven, vaned, rotary blower, an exhaust gas turbine driven, vaned rotary blower arranged at the same end of the internal combustion engine as said mechanically driven blower, separate air delivery conduits providing individual communication between said different blowers and the air intake means of the internal combustion engine, a common branch air conduit communicating with both blowers, a non-return valve in the air delivery conduit of said mechanically driven blower, said valve opening automatically when said engine is in the initial condition of operation, thereby delivering part of the output of said vmechanically driven blower into said engine intake means directly. and automatically closing by action of said turbine driven blower Awhen the delivery pressure of the latter increases above that of said mechanically driven blower at' the higher power outputs of said en-A gine, so that all of the air supplied to the intake means by said diierent blowers is then conducted through said branch conduit.

.11. In apparatus' for supercharging the cylinders of internal combustionlengines having air intake means, a vaned, rotary blower unit driven mechanically conjointly with the internal combustion engine, a plurality of exhaust turbine driven blower units, for supplying air for charging said engine, separate air delivery conduits providing individual communications between said two kinds of blowers and the air intake means of the internal combustion engine, a common branch air delivery conduit communicating with both said kinds of blowers, a non-return valve in the air delivery conduit of said mechanically driven blower, and pressure-actuated means for automatically opening said valve by l action of the delivery pressure of said mechanically driven blower, when said engine is in the initial condition of operation, thereby delivering partV of the output of said mechanically driven blower into said intake means directly, said means closing said valve automatically by action of said turbine driven blower when the delivery pressure, of the latter blower increases above that of said mechanically driven blower at the higher power outputs of said engine, so that all of the air supplied to said intake means by said different blowers is conducted through said commonl branch air conduit, said mechanically driven blower automatically delivering in part through .said branch conduction means again when the delivery pressure of said turbine driven blower decreases below that of said mechanically driven vidual air delivery conduits communicating with4 said diiierent blowers and with the air intake means of the internal combustion engine, a cornmon branch air conduit communicating with both blowers, a non-return valve in the air delivery conduit of said turbine driven blower for closing said engine intake means to said turbine driven blower, a non-return valve in the air delivery conduit of said mechanically driven blower for automatically opening when said engine is in the initial condition of operation. thereby delivering part of the air output of said mechanically driven blower into said `engine intake means directly, and automatically closing by action of said turbine driven blower when the delivery pressure of the latter increases above that of said mechanically driven blower at the higher power outputs of said engine, so that all of the air supplied to said intake means by said differrent blowers is then conducted through said branch air conduit, the non-return valve in said air delivery conduit of said turbine driven blower being opened by the eilect of said pressure increase.

13. In apparatus for supercharging the cylinders of internal combustion engines, a mechanically driven, vaned, rotary blower, an exhaust gas turbine driven, vaned, rotary blower, separate air delivery conduits communicating with said different blowers individually and with the air intake means of the internal combustion engine, a common branch air conduit communieating with both blowers, a non-returnvalve member in the individual air delivery conduit of said mechanically driven blower for automatically opening when said engine is in the initial condition of operation, thereby delivering part of the air output of said mechanically driven blower into said engine intake means directly, said valve automatically closing by action of said turbine driven blower when the air delivery pressure oi the latter increases above that of said mechanically driven blower at the higher power outputs of said engine, so that all of the air supplied to the intakemeans by said different blowers is then conducted through said common branch air conduit, and a throttling device in said common branch.

14. In apparatus for supercharging the cylinders of internal combustion engines, a mechanically driven, vaned, rotary blower, an exhaust gas turbine driven, vaned, rot-ary blower having an entrance opening to the atmosphere, a shut-off member at the said entrance to said turbine driven blower, separate air conduits communicating with said different blowers individually and with the engine air intake means, a common branch air conduit communicating with both blowers, a non-return valve member in the separate air delivery conduit of said mechanically driven blower for automatically opening when said engine is in the initial condition of operation, whereby part of the air output of said mechanically driven blower is delivered into said engine air intake means directly, and automatically closing by action of said turbine driven blower when the delivery pressure of the latter increases above that of said mechanically driven blower at the higher power outputs of said engine, so that all of the air supplied to said intake means by both of said blowers is then conducted through said common branch conduit.

ALFRED BCHI.

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