US1893035A - Internal combustion engine for pulverulent fuel - Google Patents

Description

Jan. 1933. R. PAWLIKOWSKI INTERNAL COMBUSTION ENGINE FOR PULVERULENT FUEL Filed Dec. 5. 1928 Patented drama 3 E933 htlttttldd EUDULIF PAWLHZQWSEI, F GOERLITZ,

ERNA'L COMBUSTION ENGINE ESE, PULVER'ULEHT Application filed; December 5, 1928, Serial No. 323,996, and in Germany Kay 2%, 18-27.

This invention relates to the scavenging of cylinders in solid fuel internal combustion engines of the two-stroke cycle type, and particularly to engines using pulverulent fuel 5 and having cylinders provided with scavenging and exhaust ports in their walls.

To insure safe operation of internal combustion engines using for instance powdered coal as fuel, experiments have proved to me that it will be necessary to scavenge the working cylinder space with a much larger volume of air during the brief cycle of action involved than has been possible hitherto so as to thoroughly tree the working cylinder from the ash residue of the preceding power stroke, which, chiefly during the compression stroke, enters with the leakage streams between the piston and cylinder walls, since the piston during compression moves in a direction op- 29 posite to that of the leakage streams passing outwardly through the piston rings, while, during the expansion'stroke, the piston leads with respect to the leakage streams and thus keeps tighter. The grains of ash and slag injected between the piston rings have an abrasive efiect and increase wear on the running faces. Furthermore, if certain kinds of powdered fuel are used and the cooling is insuficient, crusts of slag often form on the 30 walls of the combustion space and on the piston head, which, according to the invention are also to be removed and rendered harmless.

To attain the objectsstated the invention provides three groups of air inlet ports in the cylinder wall, two of which are directly opposite, or obliquely disposed to, a group of exhaust ports in the cylinder. According to the invention, the engine will thus be provided with a much greater total inlet cross section in the cylinder for the scavenging air than is found in the known oil engines, and this makes it possible to scavenge the working cylinder with a considerably larger volume of air than before. The residual ash of the cylinder is therefore distributed over a larger amount of air which passes out through the exhaust and the remaining dust content of the air to be compressed is so low that it will not be dangerous any more with respect to operation and wear.

it this larger volume of air were to be brought into the cylinder through air inlet ports having the prevailing smaller cross section, it would be necessary to use considerable over-pressure for blowing it in, which would involve greater driving power for the scavenging pump. This drawback is eliminated by the invention.

The invention further provides for the introduction oi the scavenging air into the cylinder in cold condition. @wing to its larger volume, the air will not be heated so quickly during its introduction and thus be able to cool layers of slag adhering to the wall of the combustion space and, particularly, to the piston head so suddenly that they will crack ed. These chipped oil particles of slag are delayed by the crank drive at the lower dead center and press on the piston head, and in order to counteract this delaying action the invention provides for the introduction into the cylinder of an additional force in the form of a larger volume of scavenging air, wholly or partly of higher pressure, which laterally displaces the loosened particles of slag and sweeps them out through the exhaust.

By way of example, the invention is illlustrated in the accompanying drawing which shows the essential features thereof while eliminating others not necessary to a clear understanding of the same.

Figure 1 is a vertical section of the cylinder of a two-stroke cycle internal combust-ion engine with additional scavenging air ports arranged according to the invention; Fig. 2, a vertical section of the cylinder of a two-stroke cycle engine provided with other additional scavenging air ports arranged according to the invention; Fig. 3, a

vertical section of the cylinder of a two-stroke cycle engine provided with additional scavenging air ports and valves arranged according to the invention; and Fig. 4, a vertical section of the two-stroke cycle engine provided with crank case scavenging and additional scavenging air valves arranged accordin" to the invention. 1

Referrin to the drawing: In the cylinder shown in ig. 1 scavenging and charging air is supplied in known manner through the ports 46, 48, exhaust and scavenging of the gases of combustion being effected through the exhaust ports 47 Since there would be no ports on the side of the cylinder opposite the ports 47 and compression can begin only after the closing of the latter, it would be disadvantageous to leave this fourth side of the cylinder unused. The invention provides therefore a fourth group of ports 49 for scavenging air in this side, which are preferably supplied with'th-e low-pressure scavenging air coming through the scavenging ports 46, 48 from the passage 52 but are provided also with a duct 57 for higher pres:- sure air. The group of ports 49 is separated from the passages 57, 52, which are at different pressure, by the shut-off members 51, 53.

When the piston opens during its descent the ports 49, equalization of pressure will take place between the cylinder space and the chamber situated in front of the ports 49, whereupon the piston will open the exhaust ports 47. As soon as the piston releases tne ports 48, air will flow out of the passage 52 and briefly afterwards, when'the piston has released also the ports 46, additional scavenging air will pass into the cylinder through the ports 46 and thoroughly scavenge it from both lower sides so as to effectively prevent the formation of an air vortex 50 in the center of the cylinder, which,

though revolving the air, does not admit fresh air into the cylinder. Before the piston closes the air ports 46, 48 during its ascent, the Valve 51 will be opened which with the ports 49 will further admit scavenging air into the cylinder. Before the piston closes the exhaust ports 47, the member 53 is opened and higher pressureair will enter the cylinder in pufilike fashion from the duct 57, so that a second thorough scavenging takes place and the previously loosened slag particles are more forcefully pushed out laterally through the exhaust. Prior to or simultaneously with the opening of the valve 53 the closing ofthe valve 51 must take place to prevent the higher pressure air from flowing into the low pressure conduit 52. Preferably, the higher pressure air coming out of the duct 57 can be used for charging the cylinder if the ports 49 are placed higher to the extent of the distance 54, so that the piston will close them somewhat later than the opposite exhaust ports 47. Ignition and expansion then go on in the usual manner.

Fig. 2 shows how one of the two tappet shafts required for the valves 51 and 53 in the construction according to Fig. 1 can be dispensed with if the intermediate valve 55 working in the same direction abuts with the top end of the: additional scavenging air valve 51 and if the high pressure charging air is delivered into the passage 52 for both valves. The ports 46, 47, 48 and 49 are arranged in the manner shown in Fig. 1.

After equalization of pressure between the cylinder and the chamber situated in front of the ports 49 has taken place during the descent of the piston, exhausting begins at the opening of the ports 47 whereuponthe ports 48 will be uncovered, scavenging commencing, however, only after the opening of the scavenging ports 46. During the entrance of low pressure scavenging air through the ports 46 the valve 51 can be opened only slightly so as to admit only very little of the higher pressure scavenging air from the passage 52 through the ports 48 and to make sure that this additional scavenging air can sweep out only through the exhaust ports 47 and not through the primary scavenging ports 46. As soon as the scavenging ports 46 are closed for a normal scavenging with low pressure air during the descent of the piston, the shut-ofi' higher pressure air can enter the cylinder from the passage 52 through the ports 48 and scavenge it from the side opposite the normal scavenging air ports 46 in order to drive out any residual gases that may have remained in the cylinder through the exhaust ports 47. When the piston covers the ports 48, the cam shaft tappet opens the valve 51 still farther, so that the latter lifts the valve 55 along with it. Hence the higher pressure air of the passage 52 will now pass through the ports 49 into the cylinder, scavenges it again, passes over the piston head and pushes the chipped off slag particles out of the opposite exhaust ports 47. When the latter are closed by the piston, the cylinder will be charged through the ports 49, the valves 55 and 51 until the ports 49 are closed, whereupon the valves 51 and 55 will be closed and compression take place in the usual way.

It is further possible to provide the fourth group of ports on any other point of the cylinder if the fourth half cylinder side is practically occupied, for example, by the long exhaust ports 32, as shown in engine the additional scavenging air ports are arranged as effectively similaropenings controlled by the members 24, 34 comprising, for instance piston valves, sleeve valves, turn cocks and the like, near the cylinder cover, the member 24 being connected with the scavenging air pipe 31 whereas the member 34 is sup- 3 plied with higher pressure scavenging air through the duct 33. Exhausting and scavenging of the gases of combustionare effected by means of the exhaust ports 32. The scavenging air ports 28 are separated from the high pressure conduit 33 by the controlled valve 35 and from the low pressure conduit 31 by the controlled double valve 29, 30. The scavenging ports 27 are also fed from the low pressure conduit 31 and are shut off there- Fig. 3. In this member 51 is opened so that a current of till incense from hy the disc 29 ot the douhle valve 29, 30.

litter the gases of comhustion have been exhausted through the ports 32, the piston releases the scavenging ports 27 during its tarther descent while, simultaneously, the douhle valve 29, 30 will he opened and a current of scavenging air passes through the ports 27, 28 into the cylinder and drives the heavy, solid residue on combustion, such as ash and clinker from the hose of the piston into the open air. According to the invention, the additional air valve or valves 24- arranged in the cylinder head are opened simultaneously and it further quantity of air is blown into the cylinder, whereby the lighter ash perticles whirling around in the upper corners will he driven out entirely through the enhaust ports 32.

In oil and gas engines of known type eruploying the reversing method oil scavenging the residual gases could not he completely driven out of: the cylinder for the reason that the upper corners and nooks on the cylinder cover could he reached only imperfectly hy the current or scavenging sir passing through the lnuown lower scavenging ports having cross sections srnaller than those according to the invention, though this is not it serious drawloach in connection with such engines as there is no mineral ash that will cause trouhle.

Due to the three-told sir injection through the ports 27 and 28 end the valve 24:, a quantity of air greater than was hitherto possilole is delivered to the cylinder and mixes with the ash-containing residual air, so that the ash content of the weight of air in the cylinder is less. The greeter portion of the air escapes through the exhaust sud still lower ash particles ere thus contained in the remaining residual air. The introduction oil a greater volume of air efiects therefore a more thorough cleansing of the combustion space from all residue of coinhustion. Shortly hetore the closure out the exhaust ports 32 the inernhers 2 1-, 29 and 30 are closed and the nienihers 34: end 35 opened, so that u short yet powerful current oit scavenging air sweeps from the cylinder well opposite the exhaust ports 32 and drives out the of the chipped oh slag particles. As soon es the piston closes the exhaust ports 32, the scavenging is finished. The members 3% and 35 still remain open tor'cherging the working space, end the nuenuher 3% may even still charge when the piston has overrun already the ports 28. When the ports 28 are closed, the two controlled inernhers 3t, 35 nre closed ngein whereupon compression, iition and enpen sion tahe place in the usual way.

Fig. l illustrates the applicat on of the invention to engines with cranl-r case scavenging. The working piston l is constructed as a stepped piston having the annular step 36. During the descent of the piston l, the scavenging air is forced in known manner oil the stepped piston, whose suction valve 5 draws in atmospheric air or pro-coinpressed air from the crank case. The annular cylinder thus acts as compressor and with gradually increasing ar pressure forces during the ascent of the piston scavenging air into the overflow pipe to the valve il.

When the piston releases the exhaust ports 39 during its descent, the gases of combustion will he expelled. During its farther descent the piston 1 will release the ports 38 wh'le, simultaneously, the meinher .Z-l. will be opened, so that a scavenging nir current sweeps out the cylinder from the cover in a straight line while scavenging air passing through the ports 38 quenches the p'ston head and blows it clear from sol'd residue of combustion. Then the piston 1 closes again the ports 38, the valve 24 will be closed also and the member ll opened. 'lhus high pressure air once more sweeps out the working cylinder thoroughly and even enters when the piston has closed already the enhaust ports 39, so that the cylinder is charged and super-charged with fresh air until the valve Fl is closed, ivhen the compression of q the charge will set i n.

It is oi course possible to vary details of construction without departing from the spirit of the invention. For example. the valves 24 and 3-1 in the upper cylinder head as shown in Fig. Sand the valves 24. and 34 in Fig. l may he interchanged, so that, n Fig. 3, the inlet ports 3% may he disposed above the exhaust ports 32 and opposite the air ports 28, 27 while the inlet ports 24 are arranged opposite the group of inlet ports 3 lahove the ports 2?, 28. @r in Fig. i, the inlet. ports ll for the higher pressure air may he disposed above the scavenging porfs 38 and opposite the exhaust ports 39 in the cylinder head while the third group of inlet ports for the low pressure air may he positioned directly opposite the inlet ports ll and above exhaust ports 39.

The types of construction described may of course he used for double acting engines. Always the cylinder will he swept out with a volume oi s r two or three times greater than now, owing to the tact that the air inlet ports have a cross section two or three times greater than those in existing engines, and the dustladen residual air from the preceding ignition stroke, which contains a large amount of ssh and slag, will thus he driven out almost completely from the cylinder and even out of its corners. This feature is absolutely necessary for the operation of pulverulent fuel engines, but is also useful for oil engines. If the same over-pressure for the scavenging and charging air is retained, a much larger volume of pure air can be brought into the cylinder, owing to-the much greater sum total of all port cross sections, or, retaining the same volume of air, the engine may be made to run much more quickly, since it is "more rapidly scavenged and charged through the greater cross section of the ports. If the same speed is maintained and the cross section of the ports increased from two to threefold, the pressure of the scavenging and charg'ng air may be reduced one-half to onethird, because the increased cross section of the ports will insure suflicient scavenging and charging of the cylinder even with lower pressure scavenging air, and the air pump will therefore consume less power.

I .claim:

' 1. In a two cycle engine, comprising a cylinder having a scavenging air port and an exhaust port above said scavenging air port, a second inlet port for supplying low pressure air opposite said scavenging port in said cylinder wall, a third inlet and charging air port for supplying first low pressure air and then high pressure air above said second scavenging air port and opposite said exhaust port in said cylinder wall.

2. In a two cycle engine, comprising a cylinder having a scavenging air port, an exfor the .high pressure air haust port above said scavenging port, a second 'inletport opposite said scavenging air port and a third inlet and charging port above said second inlet port and opposite said exhaust port, as claimed in claim 1 a duct for the highpressure air connected to the space in front of the third inlet and char ing air ports, a controlled air admission va ve associated with said space for the introduction of the high pressure air into said space, means interposed between the spaces in front of said second and third inlet air ports for preventing the high pressure air from passing into the conduit of the low pressure air.

3. In a two cycle engine, comprising a cylinder havin haust port a ove the said scavenging port, a second inlet port opposite said scavenging port and a third inlet and charging air port above said second inlet portand opposite said exhaust port, as claimed in claim 1, a duct connected to the spacein front of the second inlet port,'a controlled air admission device associated with said space for introducing high pressure air into said s ace, a controlled device for the admission 0 high pressure air from said space into the space in front of the third inlet and charging ports, means for actuating said devices by one valve-gear shaft.

4. In a two cycle engine,comprising a cylinder having a scavenging air port and a charging air port aboye said scavenging port, an exhaust port opposite said scaven ing and charging ports in said cylinder wa a. third inlet port for supplying low pressure air above said exhaust port in said cylinder wall and opposite said scavenging port and a fourth high pressure air port in the cylinder wall directly opposite said third air port and directly above said first two .air ports.

5. In a two cycle engine, comprising'a cylinder having a scavenging air port and an' charging ports in said cylinder wall, a third inlet port for supplying high pressure air above said exhaust port in said cylinder wall and opposite said scavenging air port and a fourth low pressure air port in the cylinder wall directlyopposite said third air port and directly above said first two air ports.

7. In a two cycle engine, comprising a cylinder having a scavenging air port and an exhaust port opposite said scavenging air port in'said cylinder wall, an inlet port for supplying high pressure air above said scavenging port in said cylinder wall and opposite said exhaust port and a third low pressure air port in the cylinder wall directly opposite said inlet port and directly above said exhaust port.

In witness whereof I hereunto set my hand this 6th day of November A. D., 1928.

RUD. PAWLIKOWSKI.

a scavenging air port, an ex-'

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