US2376160A - Supercharged compression-ignition internal-combustion power unit - Google Patents

Description

May 15, 1945. FQ ARBURG 2,376,160

SUPERCHARGED COMPRESSION-IGNITION INTENAL COMBUSTION POWER UNIT @Q74 INI/M7012 May 15, 1945. F` MARBURG 2,376,160

SUPERCHARGED COMPRESSION-IGNITION INTERNAL COMBUSTIQN POWER UNIT Filed Dec. 51, 1945 l '2 sheets-sheet 2 Patented May 15, 1945 SUPERCHABGED CUMPRESSION-IGNITION INTERNAL-COMBUSTION POWER UNIT -lancls Marburg', St. Petersburg, Fla. Application December 31, 1943, Serial No. 516,555

16 Claims. ('CL 123-176) e fluid-cooling was accomplished by applicant here- My invention broadly refers to improvements in supercharged, compression-ignition, internal combustion -power units. The present application is a continuation, in part, of my co-pending U. S. patent application Ser. No. 501,436, of September 6, 1943, f'or improvements in supercharged, compound, Diesel engines.- More specifically it refers to improvements in internal cylinder and `piston cooling, similar to that shown and explained in my U. S. Patent No. 2,310,643 of Itofore, by producing strong cooling-air suction within a cooling-fluid passage formed between Avaxially middle piston portions and the cylinder and the cylindrical crosshead guide during the inward piston stroke, whereupon compression of the sucked-in air and cooling-air movement were -produced by the reciprocating cylindrical cros'shead of4 larger diameter than the. power piston February 9, 1943. The main object of the present invention, is, to create a perfectly reliable, highly supercharged power unit, of plain construction, forming a requisite basis for a compound Diesel engine, preferably of similar type as shown and explained in my U. S. Patent No. 2,309,968 of February 2, 1943, and in my abovel said co-pending U. S. patent application.

In order to clearly understand the purpose of the invention, one must realize, that a highly superchargedv power unit of a given cubic piston displacement, at normal engine torque, may be charged with several times the weight of highly compressed air and of fuel, as a non-supercharged power unit of same cubic piston displacement, resulting in several times as high M. I. P., and in much higher mean temperatures than normally obtained in non-supercharged power units. For these reasons, it is advisable, or necessary, to maintain the maximum gas-pressures per sq. i. and themaximum gas-temperatures, within safe limits. In applicants power unit, maximum gas-pressures and maximum gastemperatures are maintained lower than in some of the present non-supercharged, high speed power units, whereas the gas-pressures and gastemperatures, during axially middle and axially inner piston positions. are very much higher than in non-supercharged power units, requiring novel, practically instantaneous, powerful internal cylinder and piston cooling, in order to prevent burning of axially outermost cylinder wall portions, exposed to intense heat during relatively large angular crank movements, and in order to facilitate lubrication of axially middle and axially inner power cylinder wall portions.

Heretofore, the writer provided intermittent, powerful internal cooling of axially outer and axially middle cylinder wall portions, by employing an extremely large amount of powerfully twirling cool scavenging air, and by simultaneously and successively providing additional, separate, intermittent. strong internal fluid-cooling of axially middle and kaxially inner power cylinder wall portions. This separate internal diameter during the outward piston stroke, the crosshead and crosshead guide, together with the valves, acting as a reciprocating cooling-air pump. The writer heretofore suggested that an additional, separate cooling-air pump be employed, besides the pumping action produced by the reciprocating cylindrical crosshead and the and the cylinder, the cooling-duid successively flowing also through his hollow power piston, strongly internally cooling the power cylinder and power piston. Applicant nevertheless rea1-.

izes, that reciprocating pumping action, such as shown and explained by him heretofore, at best, can only produce intermittent or variable coolingfluid movement through a cooling-fluid passage or passages, Internal cooling of the axially middle and axially inner power cylinder portions and of the power piston, by means of cooling fluid, as stated, mainly depends on 4heat-convection, which is directly proportional to the weight and velocity of the cooling-fluid contacting the internal power cylinder and the internal power piston-wall surface. In order vto produce most efficient internal fluid-cooling, with least loss of energy, cooling-fluid movement should be as steady and as rapid as possible, at uniform, moderate cooling-fluid pressure throughout the pipes and ports and cooling-huid passage or passages, causing the greatest possible weight of cooling-fluid, to move at highest velocity, through the coolig-uid passage or passages, It is lmpossible, to'produce steady. iiow of. cooling-fluid, in one direction, if the crosshead, as in applicants previous constructions, is of larger diameter than the power piston, causing irregular pumping action, even if separate additional means are provided, for producing cooling-fluid-movement through the passage or passages. On the contrary, it is important, that the power` piston and power cylinder and the crosshead and crosshead guide, should be of the same diameter and bore,

respectively, producing a cooling-fluid passage of constant cubic content during the reciprocating piston motion, non-disturbing steady coolingfluid movement through the passage or passages. Steady cooling-fluid movement through the passage or passages, preferably is produced solely by a centrifugal-or turbine-blower or-pump, orl

the like, or if cooling-lubricant is employed instead of cooling-air, steady cooling-lubricant movement may also be produced by gravity or other known, convenient means. Only in applicants construction does it become possible, to produce steady, undisturbed rapid cooling-fluid movement through the cooling-fluid passage or passages, at moderate, steady cooling-fluid pressure, which is especially of great importance, if cooling-lubricant is used for internal cooling, particularly at high piston velocity and revolutions, such as employed in high speed Diesel power units.. Experience has shown, that reciprocating pumps, moving non-compressible liquids, .such as cooling lubricant, at high piston-and reciprocating speed, are causing hammering nd breakage or serious wear and tear of val/v s, as well as loss of much energy. It is evident, that reciprocating pumping action, such as set forth and explained by applicant heretofore, under otherwise similar conditions, produces far less average cooling-fluid velocity solely in one direction, as centrifugal or turbine pumps,A a reciprocating pump therefor producing far less internal power cylinder-and power piston-cooling. The above mentioned disadvantages, resulting from applicants previous constructions are entirely avoided in applicants present, novel, more plain construction, set forth andl explained hereinafter, wherein the cylinder is of uniform bore and wherein the power piston and the crosshead are of one and the same diameter.

Another important novel featurewherein applicants present construction differs essentially from some of his previous constructions, is, that in the latter, a portion of the cooling-fluid or cooling-air, was forced to flow from the coolingfluid passage, into and through the combustion products outlet port. This is not the object of the present construction. On the contrary, the combustion products outlet port and the power piston, are'now arranged and constructed in such manner, that leakage of cooling-fluid from the cooling-fluid passage into and through the combus- -tion products outlet port is prevented. This is essential, in Vcase cooling-lubricant is moved through the passage or passages, which is prefer- .able in connection with applicants present novel construction. The writer provided special, novel means, preventing cooling-lubricant leakage, as set forth and explained hereinafter.

Other novel features of construction will be set forth and explained.

Before entering into the description of the attached drawings, applicant desires to explain the meaning of expressions frequentlyoccurring in the specification and claims.

Axially means in the direction of the cylinder axis. A xially outer cylinder and piston portions, refers to portions further removed from the engine crankshaft or powershaft, while axially inner cylinder-and piston-portions, refers to portions nearer to the crankshaft or powershaft. Outer" and inner and outwardly and inwardly, are understood in similar manner, unless differently specified.

Referring now to the attached drawings,

wherein the same numbers refer to same'parts and to same ports and passages, etc., Fig. 1 illustrates a cross-section through the engine in Va vertical plane through the crankshaft axis. Fig. 2 represents a horizontal cross-section through the engine on line 2-2 of Fig. 1. Fig. 3 shows the novel piston in erection and a vertical crosssection through the cylinder on line 3-3 of Fig. 1. Fig. 4 is a horizontal cross-section of the piston and cylinder on line 4-4 of Fig. 3. Fig. 5 represents a vertical cross-section through another novel piston and cylinder. cross-section on line 6-6 of Fig. 5. Fig. '7 illustrates a horizontal cross-section on line 1--1 of Fig. 5. Fig. 8 represents aA horizontal cross-section on line 8-8 of Fig. 1. Fig. 9 is a horizontal cross-section on line 9 9 of Fig. 1.

Referring now specifically to Figs. 1, 2,73 and 4, the engine casing II is secured/ to the crankcase I2, in similar known manner, as shown and explained i'n applicants above said U. S. patents. The engine cylinder I3'-I3", as shown, is continuous andV of uniform bore throughout and is screwed into the engine casing. The axiallyv outer cylinder portions I3', are serving as power cylinder. The piston consists of axially outer piston portions I4', serving as power piston, having piston rings I5 and sliding snugly within the power cylinder, and of axially middle piston portions I4 and of axially inner piston portions I4". The axially inner piston portions are of the same diameter as the power piston and are serving as cylindrical crosshead, sliding snugly within the axially inner cylinder portions I3" serving as cylindrical crosshead guide. The crosshead and crosshead guide are taking up all sidethrust produced by the connecting rod II, while driving the crankshaft I1'. The axially middle piston portions I4 contain a cavity, serving as a reciprocating cooling-fluid passage I8, of constant cubic contents, formed between the axially middle piston portions and the cylinder. A cooling-fluid inlet port I9 is provided for the cooling-fluid passage I8.

As illustrated, the hollow power piston I4' has a hollow axially inward extension, screwed onto a hollow axially outward extension of the crosshead I4", the two extensions, together, forming the axially middle piston portions I4. A hollow tubular conduit I8 is screwed into the axially inward extension of the hollow power piston and,

as shown, is reaching outwardly, partly through the hollow power piston, to adjacent to the power piston top, the conduit I6 subdividing the space within the power piston into a radially outer, annular shaped, second reciprocating coolingfluid passage I6 and into an interior space IB", the latter space communicating with the passage I6 adjacent to the piston top. Perforations are provided within the axially middle piston portions adjacent to the power piston, the perforations serving as second cooling-fluid ports 20, permitting communication between the axially outer end of the reciprocating cooling-fluid passage I8 and Fig. 6 is a horizontal gether, are forming a group and are arranged.

in series and in permanently open communication with each other. In addition to the above mentioned cooling-fluid ports and passages, a fifth cooling-fluid port 20 is provided, passing through the wall ofthe axially outer end of the hollow middle piston portions, adjacent to the power piston, as shown, permitting a portion of the total amount of cooling-fluid to flow from the second cooling-fluid passage I-S, directly into the third cooling-fluid passage I8. The cooling-fluid port 20' is of importance for reasons explained hereinafter. A cooling-fluid pump or blower 22,

face.

meanwhile has'been very greatly reduced. At'

ing airelatively 4very large total heat-exposed sur- The velocity of these minute fuel 'drops this period, the very hot and. densipowerfully twirling air, which in applicants engine, preferably' is compressed to one twentieth, more or less, of its atmospheric volume, at temperatures of 1200 degrees F., more or less, continues to rapidly break up, evaporate and gasify the fuel. Mixture of gas and air, under these conditions, ignites and burns'almost instantaneously. As soon as a portion of the fuel is ignited, heat radiation, which increases with the fourth power of the temperature, becomes the dominant factor, accelerating gasifying and combustion of injected fuel to such a degree, that fuel thereafter isburned up substantially as quickly as' it isinjected. Ever since beginning of Diesel engine development, mechanics have wrongly identified quick combus tion with explosion. Whereas explosion is quick combustion, the reverse is not necessarily true.

' On the contrary, applicant heretofore explained,

preferably of centrifugal-or turbine-type, forces cooling-fluid to move steadily, rapidly, solely in one direction, throughout all of the ports and passages, which together are forming a group of constant volume or cubic content, at moderate, constant cooling-fluid pressure, producing almost instantaneous internal fluid-cooling of large portions of the cylinder surface, which are intermittently, successively, exposed to the Ahot piston and piston rings and tofcooling-fluid during the reciprocating piston motion.` As illustrated, -the power piston, as well as the cylinder, are strongly internally fluid-cooled. As furthermore shown, the cylinder is simultaneously externally liquidthat explosion within a Diesel engine, can only be avoided by almost instantaneous combustion at the beginning of fuel injection. This has been accomplished by the writer to a high degree in his above mentioned U. S. patents and it is accomplished to a still higher degree in his present invention, becausehe produces herein more concooled throughout its length, by permitting coolsufficient, to state, that the guide 28 for the spray valve casing 26, as shown, is screwed in to an outward extension 29 of the engine casing and is' perfectly aligned with the engine cylinder and with the axially outer conical bore 30 within the cylinder head. The cylinder head has a port 3|, :a "serving as fuel-inlet port, terminating into the compression chamber 32, formed between the cylinder head and the piston top while the piston tinuous powerful airand gas-twirl than heretofore, which is essential in a very highly superchargedpower unit, of the. type set forth andexplained by applicant.l Applicant heretofore stated, that the gases overflow from his power unit at very high pressures and temperatures and should be utilized and further expanded within a low pressurepower unit, similarly as shown by him heretofore, or the gases may be utilized in a gas turbine, as successfully accomplished in many power plants heretofore. Theoretically, compound power plants operate most efficiently with extremely high supercharging, resulting in overow of combustion products at relatively very high pressures and temperatures. Combustion products overflowing from such high pressure power units, furthermore can be employed very efficiently in connection with jet-propelled airis in axially outer'dead center position indicated Fuel is injected into the compression chambers of Diesel engines at initial velocities of fuel drops of between 500 ft. and 100,0 ft. per second, at fuel pressure varying in different types of engines between 3000 lbs. and 15,000 lbs. per sq. i. At these initial velocities, fuel drops instantly flatten and break up into minute drops, together offerplanes. Similar combinations have been reported used recently very successfully in high speed airplanes and in locomotives. Applicants purpose, as stated, is to produce a high pressure power unit, of very high M. I. P.. wherein the gas.- and air-overflow can be utilized for generating additional power or propulsion, as the case may be. n

Applicants present invention, furthermore consists in the peculiar construction of his piston and cylinder and in his novel arrangement of coolingfluid ports and cooling-fluid passages of constant cubic contents. The power piston and power cyl'- inder and the crosshead and crosshead guide, are of same diameters and bores, respectively, producing cooling-fluid passages of constant cubic contents during the reciprocating piston motion, permitting steady, rapid movement of coolingfluid through the passage or passages, at moderateapproximately at least constant cooling-fluid pressure. The construction of the piston and the arrangement of the ports and cooling-fluid passages, have beenclearly illustrated in Figs. l to 4. As stated, the first cooling-fluid passage I8 is separated from the third cooling-fluid passage I8 by longitudinal webbs 25. The third coolingfluid passage I8 isA in direct communication with the second-cooling-iiuid passage I6 by Way of the perforation or fifth cooling-fluid port 20. 'I'he cross-sectional area of the fifth cooling-fluid port 20'., as shown, is only about one third as great as the cross-sectional area of the coolingfluid port 2|, causing only about 25 per cent of the total amount of the cooling-fluid to flow from the second cooling-fluid passage I6', through' the fifth cooling-fluid port 20 directly into the outer end portion of the third cooling-fluid passage I8 and causing about '75 per cent of the total amount of the cooling-fluid to iiow axially outwardly through the second cooling-fluid passage I6', internally cooling the power piston wall containing the piston rings, whereupon the cooling-fluid flows axially inwardly through the radially interior space I6" and through the third coolinguid port 2I, into the third cooling-fluid passage IB', from where all cooling-fluid escapes through the fourth cooling-duid port I9'. The purpose of this construction, is,` to prevent accumulation of hot air, or hot lubricant, or of gases, within either one of the cooling-fluid passages I8 or I8', which purpose is obtained, because the perforations or cooling- fluid ports 20 and 20 communicate with the axially outer or upper-end of the cooling-fluid passages I8 and I8 and because of very strong, non-interrupted, steady cooling-fluid. movement through the passages. As shown, the perforation or cooling-iiuid port 2I communicates with the third cooling-fluid passage I8 further axially inwardly than the fifth cooling-fluid port 20'. As stated by the writer, it is important to produce non-interrupted, very steady cooling-huid movement throughout the ports and passages. This becomes essential in case cooling-lubricant is employed. Cooling lubricant should not be mixed with air or gases/winch otherwise would cause irregular now, reducing internal cylinder cooling. Accumulation of hot air or gases are prevented within the hollow power piston adjacent to the piston top, because of steady, high cooling-lubricant velocity only in one direction.

Referring now to Figs. 5, 6 and '7, another novel piston construction is shown, wherein the power piston and power cylinder and the crosshead and crosshead guide, respectively, are of same. diameters and bores and wherein a single annularshaped cooling-fluid passage I8", of constant cubic content, is provided between" the axially middle piston portions I4 and the engine cylinder. In this construction, the axially middle piston portions preferably are of smaller diameter than the power piston and crosshead. The construction furthermore differs from the construction shown hereinbefore because the radially interior the velocity of the cooling-fluid at the cooling-` fluid outlet. It should be explained, that unless the cooling-fluid velocity at the outlet, always is at least as great as the maximum piston speed, during the reciprocating piston motion, more or less air is momentarily sucked into the radially interior space, which should be avoided for reasons explained hereinbefore. Either the piston construction shown in Figs. 1 to 4, or the piston construction shown in Figs. to '7, may be ernployed, provided a sufficiently large amount of cooling-huid is pumped through the ports and passages and through the radially interior space I6" at sumciently high cooling-fluid velocity, maintaining the internal cylinder wall-and piston wall-surfaces suiciently cool, facilitating lubrication and smooth sliding of the piston and Ipiston rings within the engine cylinder. As illustrated, the piston constructions are similar, except that the piston shown in Figs. 5 to 7 does not contain the webbs 25' and does not contain the peculiar cooling-fluid port 2I and the cylinder does not contain the port I9'. It should |be noted however, that if cooling-lubricant is employed in the construction shown in Figs. l to 4, no air is sucked into any of the ports or passages, no matter what the engine speed or the velocity of the cooling-lubricant may be, permitting steady, rapid lubricant movement through the ports and passages during the reciprocating piston motion, at all engine speeds, at low lubricant pressure. For the above reasons, the construction shown in Figs. 1 to 4 is somewhat preferable to the construction shown in Figs. 5 to 7, the latter construction requiring somewhat higher cooling-1ubricant pressure and more rapid cooling-lubricant circulation. The cooling-lubricant should iiow through the hollow crosshead into the crankcase, at suiiiciently low temperatures, after internally cooling the power cylinder and power piston, preventing preheated lubricant from heating the bearings. If the amount of circulating coolinglubricant is very great, the cooling-lubricant, in the construction shown in Figs. .5 to '7, may, on the contrary be employed for cooling the wrist pin bearing. It is evident, that under various circumstances, or conditions, either the construction shown in Figs. 1 to 4, or the construction shown in Figs. 5 to 7, may lbe preferable.

Applicants novel constructions, permitting the use of cooling-lubricant, improve lubrication and cooling of the crosshead and crosshead guide, as well as of the power piston and the power cylinder, which is important, because the mean sidethrust taken up by the crosshead and guide is extremely high in connection with very high supercharging and compounding, as shown heretofore in diagrams in applicants U, S. Patent No. 2,309,968. Additional pressure-feed lubrication, such as usually provided in Diesel engines, must be provided herein. It is necessary, to cool the heated lubricant, before pumping it again through the ports and cooling-fluid passages. It furthermore is advisable, to purify the cooling-lubricant from time to time. The writer did not show means for cooling and purifyingthe cooling-lubricant, because this has nothing to do with the invention. Any known, convenient means, or method, for coolingand purifying lubricant, may be employed.

Referring now specifically to Fig. 8, a scavenging-and cooling-and supercharging-air inlet port 21, is shown, terminating tangentially into axially outermost portions of the power cylinder, producing powerful twirl, or methodical turbulence, during scavenging and supercharging, the twirl continuing during high compression, fuel injection, gasification and combustion, as set forth and explained and claimed by applicant in his above said U. S. patents and in his co-pending application.

. As heretofore, a reciprocating cylindrical valve 29 may be employed, controlling scavengingand cooling-air and supercharging-air inlet into the cylinder, the valve having a port 28', connecting the ports 28, whenever the air must overflow, the valve preferably being operated as set forth and explained by applicant in his U. S. Patent No.

2,309,968. The spaces 30 are employed for cooling-water circulation for the purpose of externally cooling the walls containing the reciprocating valve. The valve 29 furthermore preferably is internally cooled, not shown herein, but shown and claimed in applicants above said previous ,pending patent application.

It is suiicient to state, that the axially outermost power cylinder portions and the cylinder head, are primarily scavenged and powerfully internally air-cooled, the'combustion products, and successively the scavengingand cooling-air, flowing spirally inwardly through the power cylinder, escaping through the combustion products outlet port 21', while the latter port is uncovered by the power piston, as explained by applicant heretofore, permitting the gases, which at normalv engine load, are stillunder very high .pressures and at very high temperatures, to flow from the l high pressure power unit into a low pressure power unit, (not shown herein), wherein the gases are further expanded and utilized. The low pressure power unit may consist of a large low pressure power cylinder and piston, such as shown by the writer heretofore, or if conditions or future development in high pressure gas-turbines, or the like, make it advisable, a turbine power unit or jet-propelling may be employed in airplanes for utilizing the kinetic energy of the combustion products overflowing from the high pressure power unit. Fig. 9 shows a cooling-water space 3l, which may be necessary, if the power unit is very highly supercharged.

Referring to Fig. 9, the combustion products outlet port 2', as shown, emerges from within the power cylinder axially inwardly of the scavengingand cooling-air inlet port, in the direction or' the gas and air-twirl produced therein by the tangential air inlet, that is in the opposite tangential direction as the air inlet port. Thisarrangement is novel and important in connection with applicants high speed power units, wherein an extremely large amount of scavenging and cooling-air, at normal engine speed and torque,

.must flow spirally axially inwardly through the power cylinder, escaping through the piston-controlled tangential .gasand air-outlet port of limited cross-section, during time periods of only a few thousandths of a second. I t is evident, that in applicants power unit, scavenging and internal air-cooling and supercharging must be well controlled in order to produce sufficient internal air-cooling, as well as sufficient supercharging. Strong irregular turbulence must be prevented in the cylinder, because this would require additional excess air-overflow pressure to accomplish scavenging under suchconditions and because scavenging would be delayed and decreased, whereas supercharging would be greatly increased, causing excessive compression. All of this can be avoided, if substantially perfect uniflow of scav-` enging-air is produced through the tangential air-inlet port and the cylinder and the pistoncontrolled tangential gasand air-outlet port. 'I'his construction has been shown and explained in the writers previous application Ser. No. 501,436. than in the writers above said previous application.

From the illustrations, it is evident, that the length of the power piston, the length of the piston stroke, the scavengingand cooling-air inlet port and the combustion products outlet port, are constructed and arranged in such manner, that the power piston, as stated, does not It is claimed herein more broadly,l

uncover thev combustion products. outlet .port,

while the piston isat or near axially outer dead center position. This is essential, if cooling-lubricant is moved through the coling-fluid ports and passages. stated, contains piston packing rings I5' arranged near thepxially inner power piston end,

see Figs. 1, 3 and 5), remaining always axially inwardlyy of the scavenging-,air inlet port and of the combustion products outlet port, these latter piston rings providing a tight packing and preventing leakage of cooling-lubricant from the cooling-fluid passage 'or passages, into and through the scavengingand cooling-air inlet port and into and through the combustionprodacts outlet port, which is essential, as stated, if cooling-lubricant is moved through the coolingluid'passage or passages, instead of cooling-air. If, on the contrary, cooling-air is employed, instead of cooling lubricant, the piston-controlled combustion products outlet port'l and the power piston and the piston stroke, lmay be arranged .l such manner,that a portion of the cooling-air escapes from the cooling-fluid passage through the combustion products outlet port, similarly as set forth and explained by, applicant in his U. S. Patent No. 2,310,643, while the remaining outer power cylinder portions, alternately, are

internally exposed to very hot combustion products and to extremely large amounts of relatively very cool scavenging-air.v The writer furthermore explained, that scavengingand cooling-air ow rapidly spirally inwardly, through the axially outer and axially middle power cylinder portions, before escaping through the combustion products outlet port. The time periods of successive internal cylinder wall surface exposure to intense heat and. to cool air, are extremeiy small, but the exposed surfaces, nevertheless, become heated and cooled, almost instantaneously, at least skindeep, during these short time periods, in conformance with known research work and established laws of heat-ray action and heat-convection, as more fully explained by applicant in his U. S. Patent No. 2,310,643. Inl addition to instantaneous powerful internal surface air-cooling of the axially outer and axially middle power cylinder wall portions, by an extremely large volume of cool scavenging-air, in the manner as originally proposed by the writer, applicant furthermore originally recommended strong internal fluid-cooling of axially middle and axially inner power cylinder wall portions, and ofthe crosshead guide. Applicant originally reasoned, that almost as important, to internallyl cool these latter cylinder wall portions, by directcontact with very large amounts of cooling-fluid, asfit is, to powerfully internally air-cool axially -ou`ter and axially middle power cylinder wall portions.- As stated in the writerfs above said U. S. patents, the power piston and piston rings furthermore` are almost instantaneously cooled skin-deep as a result of heat-convection produced between the piston and piston rings and the above said fluidcooled axially inner power cylinder wall portions, which latter wall portions herein preferably `are strongly internally cooled by cooling fluid during short 'intermediate time periods, before and after the piston reaches inner dead center position. In the writers present construc-I Applicants power piston,. as

tions. portions of the power cylinder and the piston rings, are cooled more eillciently, by heatconvection than heretofore, because cooling-fluid is moved uninterruptedly and steadily through the cooling-fluid passage or passages. Moreover, such cylinder wall portions, in applicants pres' ent construction, can be cooled internally far more strongly than heretofore, because coolinglubricant can be employed herein instead of cooling-air. This was impossible heretofore in known constructions. It should be understood, that heat convection, under otherwise similar conditions, is proportional to the density of the cool-V ing medium and that cooling-lubricant density is very much greater than cooling-air density.

Applicant stated heretofore, that the reciproeating piston and piston rings, to a considerable degree, act as almost instantaneous temperature equalizers of portions of the cylinder wall surface, and vice versa, producing momentarily at least, surface temperatures, facilitating lubrication and reducing sliding friction to a minimum, while the power piston is entirely free of side-thrust.

As stated, the power piston wall portions containing the piston rings, are powerfully internally cooled, preferably by contact with large amounts of cooling-lubricant, flowing closely alongside the internal power piston wall surface, the internal cooling of these power piston wall portions, in turn, producing strong internal cooling of the piston rings and of lubricant within( the piston ring grooves, maintaining this lubriaant below critical temperatures, at which the lubricant otherwise would carbonize, all of which is essential for continuous -lubrication and for safe operation of the engine.

The power piston rings and grooves, as illustrated, are arranged further axially inwardly within the power piston and power cylinder, than customary, and therefore do not get into contact with cylinder wall portions exposed to the most intense heat-ray action during relatively longest time periods. The axially outermost cylinder wall portions, as stated, are protected against internal burning, by powerful cooling-air twirl, produced primarily within these latter cylinder wall portions. The piston rings furthermore are protected against excessive heat-conduction from the piston top, by reduced thickness of the annular piston wall portions 35 arranged between the piston top and the piston rings, as shown, which has been explained and claimed by applicant heretofore.

Referring again to internal fluid-cooling of cylinder wall portions and to internal power piston cooling, which are subjects of applicants inventions, the writers present novel construction, as stated, facilitates greater heat-convection and internal cooling than heretofore, because it produces more steady and therefore increased mean cooling-fluid movement, through the coolingfluid passage or passages, under otherwise similar conditions. It furthermore permits of employment of cooling-lubricant instead of cooling-air, without danger of irregular, sudden, high cooling-lubricant pressures, which otherwise would cause heavy shocks and would have a tendency, of producing cooling-lubricant leakage from the cooling-fluid passage or passages into and through the combustion products outlet port, which is entirely avoided herein. In applicants previous constructions, it was the clearly expressed and illustrated purpose to cause a portion of the cooling-uuid to flow from the coolingfluid passage into and through the combustion products outlet port, whereas, on the contrary, it is the purpose of the present construction, to prevent cooling-lubricant fromilowing or leaking from the cooling-duid passage or passages into or through the combustion products outlet port, which latter object is fully accomplished.

In conclusion, heat-convection and internal cooling, as stated, are proportional to the velocity and the weight or density of cooling-fluid, moved through the passage or passages. Whereas cooling-air can be forced to flow through the coolingfluid passage or passages. at much greater velocity than cooling-lubricant, the total weight or density and the total heat-absorbing capacity of cooling-lubricant, which can be forced to flow through the passageor passages, in applicants present novel construction, nevertheless, is very much greater than the total weight and heatabsorbing capacity of cooling-air, which can be forced to flow through the passage or passages of fluid valves. It can be constructed of light weight per I. H. P. and as a short-stroke power uniti well adapted for tractors, motor trucks, busses, locomotives and` airplanes, whereas applicants previous, long stroke power unit, is better adapted ior heavy, stationary and marine service.

In his above said U. S. patents andr pending patent application, the writer has clearly set forth and explained the reasons, why a properly designed, compound, or multi-expansion, compression-ignition, internal combustion engine, will operate with a fraction of the fuelV and of the maximum bearing pressures and internal strains, per I, H. P., as a non-supercharged, non-compound, internal combustion engine. A foolproof, highly supercharged, high pressure power unit, is the necessary pre-requisite for a compound Diesel engine, The problem of constructing such a high pressure power unit is of fundamental importance in the development of Diesel engines. Applicant believes he has solved this problem in a practical manner.

M. I. P. signifies mean indicated gas pressure during the downward power pistonstroke. The abbreviation sq. i." signifies square inch.

The expression cooling-fluid passage or passages, signies a passage or passages, extending alongside portions of the internal cylinder wall surface and alongside of the internal power piston wall surface, means being provided, producing steady, rapid cooling-fluid movement through the passage or passages, for the purpose of practically instantaneous internal surfacer cooling' of cylinder wall-and power piston wall-portions, failitating efficient lubrication and safe operation of the high pressure power unit.

Cooling-fluid ports signifies inlet-and outlet ports into and from a passage or passages.

Cooling-fluid includes cooling-air and cooling-lubricant, or the like.

I claim my invention broadly ln` connection with supercharged, compression-ignition, inter- 1rzial combustion engines, of two cycle or four cycle ype.

Various changes in construction may readily `power cylinder andsaidn crosshead-guide being o suggest themselves to a mechanic versed in the art and nothing contained herein, is intended to imply, in any manner, that applicant is limiting v himself to the constructions shown and to the combinations described'herein, except as required 5 cylinder head and a piston, the power unit having an automatically controlled air-inlet port for scavenging and internal air-cooling and supercharging, the power unit having a fuel-inlet port terminatinginto the, compression chamber, the

power unit having a pis\tor`c'ontrolled outlet port l5 for scavenging air and combustion products, axially outer piston portions servingas power -pis, ton sliding snugly withnaxially outer cylinder constant cubic contents, said hollow piston portions having a second perforation serving as a third cooling-fluid port providing communication between saidhollow within said piston and a second cooling-Huid cavity provided between said axially middle piston portions and said cylinder, said second cavity serving as a third reciprocating cooling-huid passage of constant cubiccontents, the power unit having a fourth coolingfluid port communicating with said third coolinguid passage, the said rst said cooling-huid ""port, said iirst said cooling-huid passage, said second cooling-duid port, said second cooling-fluid passage, said third cooling-fluid port, said third cooling-iiuid passageand Ysaid fourth lcoolingiiuid port,'together, forming a group and being arranged in series and in permanently open communication with each other, means being proportions serving as power cylinder, axially inner ig-vidpd, non-disturbed by the reciprocating piston piston portions serving Vas cylindrical crosshead Vmsliding snugly `within axially inner cylinder portions serving as crosshead guide, a powershaft, means drivingsaid shaft from saidncrosshead, said power piston and said crosshead and aid one and the same diamemndrbore respectively,

aiall'middle piston portions having a cavity contents during the reciprocating piston motion,

said passage extending for the greater portion of `Vthe circumferen@ within said cylinderfthapower unit having a coolgfluid port terminating\ into said cooling-fluid passage and havingasecond Nand into mot1on,\producing uninterrupted, steady, rapid cooling-nui solely in one direction,

3. A structure as in\claim 2, wherein means are provided, preventing cooling-fluid leakage from the said cooling-huid passages into and through id scavengingand cooling-air inlet port d through the said combustion .products outlet port duringithe reciprocating piston \moti0n. s t

4. -A-structure as in claim 2 wherein the space within thesaid; hollow powenpiston is subdividedV by a tubular corduit into a substantially annular shaped radially exterior passage serving as the said second reciprocating cooling-duid passage cooling-Huid port emerging from withinsaid`cool- NN of constant cubic contents communicating with ing-fluid passage, said cooling-huid ports and said cooling-fluid passage together forming a group,

said cooling-uid passage being arranged in series between and in permanently open communi- `\said second cooling-fiuid port and into a radially interior space communicatingpat its axially outer end, adjacent to said piston topwith said second cooling-Huid passage and communicating at its cation with'said coolingd ports, means being 40 axially inner end with said hollow within said provided, non-disturbed by the' reciprocating pis- Ytn .motionf producing uninterrupted, gsteady,

rapid cooling-fluid movement throughout said group solely innone direction,

2. A superchaigd'compression-ignition,l insliding snugly within axially outer cylinder por.

tions serving as power cylinder, axially inner piston portions serving as cylindrical crosshead sliding snugly within axially inner cylinder portions serving as crosshead guide, a powershaft, means driving said shaft from said crosshead, said power piston and said crosshead and said power cylinder and said crosshead guide being of one and the same diameter and bore respectively, axially middle piston portions having a cavity and form-A ing together with said cylinder a reciprocating cooling-huid passage of constant cubic contents during the reciprocating piston motion, the power unithaving a cooling-fluid port communicating with said passage and having a second coolingfluid port communicating with said passage, said piston being hollow except the piston top and said crosshead, said hollow piston portions having a perforation serving as the said second coolingfluid port, said hollow within said piston serving as a second reciprocating cooling-huid passage of axially middle piston portions, the said third cooling-huid port permittingk communication between said'hollow within said axially middle pistonrtions and the said third cooling-uid pas- 4" sage, t e said third cooling-huid passage being `ternal combustion power unit, having a cylin eis\eparated from said iirst said coo-ling-iiuid pasage byaxial webbs arranged on said axially middle isgin portions, said third cooling-ud passage communicating withv the said fourth coolinguid port, the said iirst said cooling-fluid port, said first said cooling-fluid passage, said second cooling-fluid port, said second cooling-iiuid passage, said radially interior space, saidy hollow 1 within said axially middle piston portions, said 05 third cooling-fluid port, said third cooling-Huid passage and said fourth cooling-fluid port, to-

gether, forming a group and being arranged in series and in" permanently open communication with each other during the reciprocating piston motion, means being provided, non-disturbed by said second cooling-fluid passage communicat-V ing with the said second cooling-duid port and into a radially interior space communicating at its axially outer endadjacent to said piston top, with said second cooling-fluid passage and communicating at its axially inner end with said hollow within the said axially middle piston por- \mo\vement throughout said groupv wall of said hollow axially middle piston portions adjacent to said power piston and permitting direct communication between said second coolingfluid passage and the axially outer end portion cf said third cooling-fluid passage, the said rst said cooling-Huid port, said rst said coolingfluid passage, said second cooling-fluid port, said second cooling-iluid passage, said radially interior space, said hollow within said axially middle piston portions, saidthird cooling-fluid port, said third cooling-Huid passage and said fourth cooling-fluid port, together, forming a group and being arranged in series'and in permanently open communication with each other, means being provided, non-disturbed by the reciprocating piston motion, producing uninterrupted; steady, rapid movement of a portion of said cooling-fluid throughout said entire group solely in one direction, the arrangement being such, that a portion o-f said cooling-fluid flows from said second cooling-duid passage through said iifth cooling-huid port directly into the axially outer end portion of said third cooling-fluid passage.

6. A structure as in claim 1, wherein the said power piston, the said axially middle piston portions and the said crosshead are hollow, except the piston top, said hollow axially middle piston portions being perforated adjacent to said power piston, said perforation serving as the said second cooling-fluid port, said hollow withinsaid piston and within said crosshead serving as asecond reciprocating cooling-fluid passage of constant cubic contents during the reciprocating pisasvaieoton portions and with said hollow withinsaid crosshead, the said first said cooling-duid port. the said first said cooling uuid-passage. said second cooling-fluid port, said second cooling- 'fluid passage, said radiallyI interior space and said hollow within the axially inner end porsage are adapted for circulatlngcooling-lubricant through said ports and said passage, the

ton motion and communicating with said second cooling-fluid port, said first said cooling-fluid port, said first 4said cooling-fluid passage, said second cooling-fluid port and said second cooling-fluid passage, together, forming a group and being arranged in series andin permanentlyopen communication with each other, means being provided, non-disturbed by the reciprocating piston motion, producing non-interrupted, steady, rapid cooling-fluid movement throughout said group solely in one direction. d

7. A structure as in claim 1, wherein the said power piston, the said axially middle piston portions and the said cross head are hollow, except the piston top, said hollow axially middle piston portions being perforated adjacentto said power piston, said perforation serving as the said second cooling-fluid port, the space within said hollow power piston being subdivided by a tubular conduit into a substantially annularshaped radially exterior-,passage serving as a second reciprocating cooling-fluid passage of constant cubic contents duringvthe reciprocating piston motion, communicating with said second cooling-fluid port and into a radially interior space communicating at its axially outer end, adjacent to said piston top, with said second cooling-fluid passage and communicating at its axially inner end with said hollow within the axially inner end of said axially" middle pispiston stroke, the axial length and shape of said passage, and the location of said cooling-huid portsbeing such, that said passage does not communicate with said scavenging air inlet port and'with said combustion products outlet port y during the reciprocating piston motion, the arrangement permitting uninterrupted, steady cooling-lubricant movement through said cooling-fluid ports and said cooling-huid passage during the reciprocating piston motion, vmeans being provided, including a piston packing ring arranged adjacent to the axially inner end of said power piston, in such manner, that coolinglubricant leakage is prevented from said passage, past said .piston packing ring into said scavengng-air inlet port and into said combustion products outlet port.

9. A structure as in claim 1, wherein said scavenging-and supercharging-air inlet port is terminating tangentially into axially outermost cylinder portions, and wherein said air-and combustion products-outlet port emerges from within said cylinder further axially inwardly than said scavenging-air inlet port said air-and combustion products emerging from within said cylinder tangentially in the direction of the twirl produced by said tangential air-inlet port,

thus improving 1 uniflow, permitting higher scavenging-air velocity, increasing internal aircooling of the cylinder wall and piston top and facilitating lubrication of said power cylinder.

10. A structure as in claim 1, wherein said cooling-fluid ports and said cooling-fluid passage contain rcooling-lubricant and are arranged axially inwardly from said scavengingair inlet port and from said combustion products outlet, port, the piston stroke and the axial length of said cooling-fluid passage andthe arrangement of said ports, being such, that said passage does not communicate with said scavenging-air inlet port and with said combus- 'tion products outlet port during the reciprocating piston motion, means being provided producing uninterrupted, steady cooling-lubricant movement through said passage, and means preventing cooling-lubricant leakage from said passage past said piston into said scavengingair inlet port and into said combustion products outlet port.

l1. A structure as in claim 1, wherein the eaiiiig uninterruptediy with a cooling-mild ,passage provided between said piston and liheimajorV `axially middle portionsy of,v saidfcylinder, said cooling-huid ports'f'being arranged in permanently open, comuncation with eachother by way o! 'said cooling-fluid'passage during the 're-' ciprocating piston mation, means being provided producing non-interrivip'ted,steady,l rapid cool- .port are provided within thewall ofy said cylinder axially inwardly of said scavenging-air inlet port and of said combustion products outlet port, portions of said piston being hollow,

saidhollow serving asa cooliii-grluid chamber fwithin said piston, a cooling-fluid inlet cavity and. a cooling-duid outlet cavity being provided and arranged between Said piston and said .cylinder wall respectively, said hollow piston portions having two perforations, said perforations said cylinder, axially outer piston portions serving as power piston sliding snugly within axially outer vcylinder portions serving as power cyl'-v inder, axially inner piston portions f`ser-ving as ing-fluid movement through Asaid cooling-lluid inlet port, said passage and said cooling-duid permitting communication between the said cavities and said chamber respectively, the said cooling-fluid-inlet port, said cooling-nuid-inlet cavity, one of said perforations, said chamber, the other one of said perforation's, ksaid cooling iiuidoutlet cavity and said coolig-uid-outlet port, together, forming a group and being arranged in series and in permanently open communication with each other during the reciprocating piston motion, means being provided, producing noninterrupted, steady cooling-fluid movement E throughout said group, for the purpose of strong- 'videdjterminating tangentially into axially outermost cylinder portions primarily scavenging and internally air-cooling said compression chamber and said axially outermost cylinderlportions, the power unit having a piston-controlled scavenging-air and combustion products-outlet portV y emerging from within said .cylinder tangentially in the direction of the twirl produced by said vtangential air-inlet and being arranged axially inwardly from said-scavengingand supercharging-air inlet port, the arrangement producing powerful, substantially unobstructed airand gas-twirl around the cylinder axis primarily within said compression chamber and said axially outermost cylinder portions, said twirl continuing uninterruptedly during scavenging, supercharging, fuel-injection, gasification and combus.. tion, said tangential air yinlet port and said tangential gasand air-outlet port co-operating in producing uniflow of airand combustion products, facilitating scavenging and internal aircooling and lubrication of said cylinder.

- 14. A supercharged, compression ignition, internal combustion power unit, having a cylinder of uniform bore, a pistonsliding snugly within crosshead siiding. snugly within axially inner cylinder portions serving as crossheadguide, said power piston and said crosshead and said power cylinder and said Crosshead guide being of one and trie same diameter and bore respectively, axially middle piston portions being oislesser diameter than said power piston and said ci'osshead, the power unit compression chamber .being arranged substantially concentrically with the cylinder axis and being in substantially non-restricted communication with axially outer cylinder portions, the power umt having a fuel inlet port adapted Ior iuel injection into said compressioii chamber, the power unit having an automatically controlled scavengingand supercharglng-air inlet port terminating tangentially into axially outermost cylinder portions primal-- ily scavenging and poweriully internally air-cooling said compression chamber and said axially l outermost cylinder portions, said power cylinder having a power piston controlled scavenging-air and combustion products outlet port emerging from witriin said cylinder tangentially in the olirection of the twirl produced by said tangential air-inlet port, said piston-controlled port being arranged axially inwardly trom said scavengingand supercharging-air inlet port, ,the arrangement being such that powerful substantial- 1y unobstructed airand gastwirl-are .produced Within said power cylinder around'fsald cylinder axis, said twirl continuing uninterruptedly during scavenging, supercharging, fuel-injection, gasiiication and combustion, said tangential piston controlled gasand air-outlet port, facilitating gasand air-overflow, improving uniflow and scavenging and internal air-cooling of the power r.cylinder and of the top of said piston as a result 'of increased heat convection from the hot' wall piston and cylinder portions, said cooling-huid ports and said cavity being arranged in permanently open 'communication with each other by way ofv said cavity during the reciprocating piston motion, means being provided producing non-' cooling-fluid movement interrupted, steady through said .cooling-fluid inlet port and said cavity and said cooling-Huid outlet port, for the purpose of effecting strong internal fluid-cooling of axially middle cylinder portions during the recipi-ocating piston motion.

16. A structure as in claim 1, wherein the wall of said cylinder has a cooling-fluid inlet port and a cooling-fluid outlet port arranged axially inwardly of said scavenging-air inlet ,port and said combustion products outlet port, axially outer and axially middle portions of said piston being hollow, said hollow serving as a coolingfluid chamber, a cooling-fluid inlet cavity and a -f cooling-fluid outlet cavity being provided and arranged within the axially middle portions of said piston and extending alongside the greater portion of the periphery within said cylinder, said hollow'piston portions having two perforations permitting communications between said cavities and said chamber respectively, said fluidinlet port, said uuid-inlet cavity, one of the said perforations, said chamber, the other one of the said perforations, said Huid-outlet cavity and said uid-outlet port, together, forming a. group and being arranged in series and in permanently open communication with each other during the reciprocating piston motion, means being provided, producing non-interrupted, steady cooling-uid movement throughout said group, for the purpose of strongly internally fluid-cooling axially middle portions of said cylinder and of said piston during the operation of the power unit.

FRANCIS MARBURG.

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