US1206722A - Construction of internal-combustion engines. - Google Patents

Description

' J. McKECHNIE. CONSTRUCTION, OF INTERNAL COMBUSTION ENGINES. APPLICATION FILED FEB. I2. 1916.

1 0,722 Patented Nov. 28, 1916.

. 4 SHEETSLSHEET 1.

R 4 a j 4 if f I J. McKECHNlE. CONSTRUCTION OF INTERNAL COMBUSTION ENGINES.

' APPLl( 3ATl0N FILED FEB. 12. 1916.

4 SHEETS-SHFET 2.

J. IVIcKECHNIE. CONSTRUCTION OF INTERNAL COMBUSTION ENGINES. APPLICATION FILED FEB. 12. 1916.

4 SHEETS-SHEET 3.

0. 6' F (D/Z 7 M f j I a o J. fame Patented Nov. 28,1916.

1'. McKECHNIE.

CONSTRUCTION OF INTERNAL COMBUSIION ENGINES; APPLICATION FILED FEB. 12.- 1916.

Patented Nov. 28, 1916.

4 SHEETS-SHEET 4.

UNITED STATES PATENT osnion.

JAMES MoKE C HNIE, OF IBARROW-IN-FURNESS, ENGLAND, ASSIGNOR 'IO VICKERS LIMITED, OF LONDON, ENGLAND.

' Specification of Letters Patent.

Patented Nov. 28, 1916.

Application filed February 12, 1916. Serial No. 77,937.

To all whom it may concern:

Be it known that I, JAMES MoKnonmna subject of the King of Great Britain, residing at Naval Construction Works, Barrowin-Furness, in the county of Lancaster, England, have invented certain new and useful I; Improvements in the Construction of Inter nal-Combustion Engines, of which the following is a specification.

This invention relates to the construction of internal combustion engines of the balanced kind employing three pistons, the central one of which has an area approximately equal to the combined areas of the outer pistons and moves in an opposite direction to the latter.

My invention provides certain improvements in engines of this kind (especially two-stroke cycle engines) which allow of greater compactness and economy in construction and increased efficiency.

The means for cooling piston rods and istons in engines of this kind is described and claimed in the application of James McKechnie Ser. No. 106634 filed June 29, 1916, which is a division of the present application.

- end, where it joins the passage leading to the According to my invention two compres sion spaces are provided, each comprising the space between the outer end of one of the smaller pistons and the outer end of one of, the smaller cylinders, and also a passage between the smaller and larger cylinders. The fuel may be sprayed through two injection valves without the admixture of air or the usual air spraying device may be employed. The spray is directed acrossthe upper end of each side cylinder toward the middle of the engine. To obtain the most efiicient combustion I may practically confine the compression space of each small cylinder to a transverse channel formedby channeling the piston end and the end wall of the cylinder, the piston at the conclusion of its outer stroke almost meeting the cylinder end except at the channel, which preferably widens from its outer or spraying end to its inner central cylinder. The central piston may serve also as an air compressor for the supply of scavenging air, for this purpose the central cylinder being provided with an extension a ove the piston, forming a chamber in which the air is compressed.

In an engine of the three piston balanced used, one for each injection valve.

type andof large size, it is difiicult to provide efiiclent water cooling for the central piston and piston rod by ordinary methods and I propose to employ an improved water cooling system in which the water is introduced and escapes through pipes or channels extending along the axis of the piston and piston rod and passing through the piston head. I

A convenient form of valve gear for operating the two injection valves and also the air starting valve comprises a cam shaft with a double or reversing cam for each injection valve and a double cam for, the starting valve, the shaft being displaceable axially for forward or reverse drive. A hand wheel and screw device may be used to move the cam shaft for regulating and reversing. Two fuel pumps are preferalbllly e pumps may be in the same casing and driven from a pair of eccentrics on a shaft'geared to the crank shaft through reducing gear. In order that the invention may be clearly understood and readily carried into effect, the same will be described more fully with reference to the accompanying drawings, in

which I Figure 1 is a vertical section of an engine embodying the various features ofmy invention. Figs. 2 and 3- are elevations of the a said engine taken at right angles to each other, with some details in section; Flg. 4;

is a section of the upper part of the central cylinder and piston showing a method of fitting a scavengingpump; and Fig. 5 is a vertical section, on an enlarged scale, of the cooling arrangement. a A is the engine casing.

B is the central cylinder and C, C are the outer cylinders.

D is the large central pistonand E, E are I the smaller side pistons working in the opposite direction to the piston D and with a combined cross sectional area equal to that of the central piston.

F is the crank shaft with central crank f and two side cranks f connected respecbular piston rod 03 belonging to the piston D. Qonnecting rods 0 are provided between the S11E66 cranks f and the side trunk pistons G is a fixed inner tube and G an outer tube leading the cooling water through the central piston rod 03 and piston D.

H, H are a pair of double or reversing cams for the injection valves J and H is a double cam for the starting valve K, the

cams H and H being fitted on the cam shaft h which is displaceable axially for regulating and reversing by the hand wheel h.

L is the fuel pump casing. The central cylinder B is in open communication with both of the side cylinders C through the passages c and at the end of the 'compression stroke, in the position shown in Fig. 1, the large piston D approaches the end of its cylinder so closely as to leave only theminimum clearance permissible. There are therefore two compression spaces, one for each side cylinder, comprising the passages c and a transverse channel e in the upper end of each of the pistons E; these pistons also approach closely to the cylinder ends, except for the channels 6', which lead diametrically across the pistons from the inner passages c to the spraying nozzles or valves situated at J at the outer sides of the cylinders C. The ends of the cylinders C are suitably formed to complete the transverse channels and to confine the compression space at the end.

of the stroke practically to these channels and the passages c. .In large engines of the present type it is of importance to be able to spray the fuel in such amanner that intimate mixture is obtained throughout the compression space and by separating the compression space into two parts each hav- 1ng 1ts own spray and' moreover, by formmg each compression space as a channel along which the spray is inwardly directed,-

the greatest efficiency of spraying and fuel combustion is obtainable. As already mentioned each channel e may V widen from the outer end, where the no zzle J is placed, to the inner end, where leads into the passage 'c. The passage 0 is made large enough to givea free outlet to the exhaust gases and the scavenging air, the air entering through ports 6' in the small cylinders and escaping through exhaust ports I) in the large cylinder, on uncovering by the respective pistons C and B. A non-return air valve K may be placed at the top of one of the outer cylinders C for use in air starting and a safety valve M may be placed at the top of the other cylinder.

The casing, A is provided with the water jacket a around the central cylinder B and the side cylinders C, the lower part of the jacket also surrounding the central part a of the casing, through which the tubular piston rod d passes, so that the water jacket assists in cooling-this rod. "As already mentioned, it is desirable to cool the thick central piston rod by a special water cooling device comprising the fixed inner and outer tubes G and G and extensions through the piston and piston rod. ater is introduced by the inlet 9 through the fixed tube G that leads through the center of the cylinder or pump cover and passes into the end of the piston rod tube 9, which slides upon the tube G as the piston reciprocates. The outer fixed tube G having'an outlet 9 at its upper end surrounds the central inlet tube G, leaving an annular channel for the outward flow of the water, this outer tube passing through a stufiing box in the upper end of the piston rod (Z'.

The tube (which for convenience in fitting is made in three sections) extends from the outer end of the rod 03 to just within the piston D, which is hollow. A small collar on the upper end of the tube 9 at closes the annular passage at the top of the,tube 5/ immediately above openings formed in the piston rod and piston and leading to the interior of the latter, return openings passing back from the upper part of the piston chamber to the water channel in the rod d. The lower section 9* of the central tube 9 is perforated at g to allow of communication with the, annular return channel formed between the tube and the inner wall of the tubular piston rod.

The cooling water flows downwardly through the central tubes G and g to the lower end of the piston rod 03, thence upwardly through the annular passage surrounding the tube 9 to the openings g into the interior of the piston D, back through the return openings to the annular passage inside the piston rod and thence to the outlet 9 through the annular passage between the two fixed tubes G and G. An efficient circulation throughall parts of the piston and piston rod exposedto high temperature is thus obtained.

The valve gear for the starting and injection valves is shown in Figs. 2 and 3. As already mentioned the two double cams H and H are mounted on the same shaft h, which can be displaced axially for regulating and reversing purposes by the Wheel k and screw k The timing valve K for air starting, from which a" connection passes to the non-return air valve K on one of the cylinders C, is shown in section in Fig. 2 with the valve stem meeting one element of the air valve cam H. For starting in the reverse direction the shaft It is shifted to the right to bring the second cam element into operation. The air supply is cut out or in by the cut out valve K shown in section in Fig. 3 and operated by the starting hand wheel is acting throughthe worm is and worm quadrant 74 The valves K and K are operative only when the air supply is turned on by the valve K A connection Z from the quadrant k to the fuel pump casing L cuts 011' the fuel supply when the valve K is open, by, for example, holding open the fuel suctionvalve.

The two double cams H for the two fuel injection valves J are shaped to admit of timing and variable .fuel supply by axial adjustment of the shaft 72. in a manner well known. They operate the yalves simultaneously through the lever connections 3' and by moving the shaft hpast the central dead position the cams serve for reverse drive.

It is preferredto place two fuel pumps in the pump casing L, each pump supplying its own injection valve J which may. be arranged to inject under high pressure liquid fuel unmixed with air, the fuel entering the cylinder in the form of a spray. The pumps are driven through rods Z by the half speed eccentrics Z (Fig. 1) geared to the crank. shaft F through gearing Z the intermediate.

wheel of which drives the lubricating pump L through the eccentric Z (Figs. 1 and 3).

Z is the fuel inlet pipe and Z is an outlet pipe leading to an injection valve J.

If the central piston D is to serve-also for scavenging purposes, by 1 utilizingits upper end, the construction of the cylinder B and piston D may be modified as shown in Fig. 4, the piston D being extended at D through the cylinder and provided with a flange 0Z in the enlarged cylinder extension B, so that the flanged end of the piston D forms a pump piston of increased area, sweeping out at'eachstroke a sufiicient volume of air to serve for the scavenging air.

supply ofthe three cylinders. The extension or pump cylinder B is provided with air inlet and outlet valves 6' and b and an air chamber 6 to which the air supply pipe leading to the cylinders C is connected at 6 The air inlet or supply pipe is shown at c in Fig. 3, the air passing into the cylinders C through the inlet ports 0 (Fig. 1). already referred to. C The pump may be double acting, as shown, the under-side of the piston flange d being utilized by placing air valves 6' and 12 both at the upper and lower ends of the pump cylinder B.

Fig. 4 does not show thecooling means for-the piston rod (1', but the arrangement of tubes shown in Fig. 1 may of course be employed in conjunction with the air compressor of Fig. 4.

The general operation of an engine conf structed on the lines illustrated is similar to that of an ordinary two strokeengine with ignition on Diesel lines. The method of ignition, however, forms no parts of the present invention. Starting with the engine in the position shown in Fig. 1, the

air has already been fully compressed and is now confined to the small spaces left inthe side cylinders C by the channels e on the top of the pistons E and the short com- 'municating channels 0 leading to the central cylinder B. At about .the maximum compression the cams H operate theinjection valves J and a'fine spray of fuel is forced by the fuel pumps through the spraying nozzles into the two compression'spaces,

\ the spray being directed inwardly along the channels 6 of the pistons E. The compression in the cylinders C is sufficient to ignite the fuel and combustion'follows on the usual lines. The pressure acts equally on the pistons D and E, which move in opposite directions but exert torque upon the shaft F der B are uncovered by the piston D andv at about the same point of the stroke the inlet ports 0"in the two side cylinders C are uncovered by the pistons E and scavenging air passes through these ports into both side cylinders and then through the passages 0 into the central cylinder B and out through the exhaust port. A clear path is thus provided between the inlet at oneend of the cylinder spaces and the exhaust at the other end. The pistons and cylinder ends are formed to insurea good sweep for the air, the ends of the side cylinders andthe tops .of the side pistons sloping slightly up to ward the center while the lower end of the central piston D is conical. On the inward stroke of the pistons the ports 0 and b are closed and compression of the charge is effectied, completing the usual two-stroke cyc e. /i

What I claim and desire tosecure by Letters Patent of the United States is 1. In an internal combustion engine, a

large central cylinder, two side cylinders having a combined cross section approximatelyequal to that of the large cylinder and connected to the latter by passages, a large piston in the central cylinder adapted at the end of the compression stroke almost to meet the cylinder end so as to leave no compression space in the said cylinder, two small side pistons acting oppositely to and balancing the pressures on the large piston, two separate compression spaces each made in the form of a transverse channel leading from the outside edge of a, small cylinder to one of the said passagesleading to the central cylinder, and an injection valve at the outer end of each channel and directed inwardly toward the central cylinder.

2. In an internal combustion engine, a large central cylinder, two side cylinders having a combined cross section approximately equal to that of the large cylinder and connected to the latter by passages, a large piston in the central cylinder adapted at the end of the compression stroke almost to meet the cylinder end so as to leave no compressionspace in the said cylinder, two small side pistons acting oppositely to and balancing the pressures on the large piston, a transverse channel in the end "of'each of the small pistons, each channel forming a narrow compression space leading from the outer edge of the small cylinder to the passage communicating with the large cylinder, and an injection valve at the outer edge of each small cylinder and directed along the corresponding channel.

' 3. In aninternal combustion engine, a large central cylinder, two side cylinders having a combined cross section approximately equal to that of the large cylinder and connected to the latter by passages, a large piston in the central cylinder adapted at the end of the compression stroke almost to meet the cylinder end so as to leave no compression space in the said cylinder, two

small side pistons acting oppositely to and balancing the pressures on the large piston, two separate compression spaces each made 1n the form of atransverse channel leading from the outside edge of a small cylinder to one of the said passages leading to the central cylinder, an injection valve at the outer end of each channel and directed inwardly toward the central cylinder, and a separate fuel pump for each valve and pump driving gear connected to the crank shaft.

4.. In an internal combustion engine, a large central cylinder provided With eX- haust ports in its Walls, two side cylinders each provided with airinlet ports in their walls and having a combined cross section approximately equal to that of the large cylinder and connected to the latter by passages, a large piston in the central cylinder adapted at the end of the compression stroke almost to meet the cylinder end so as to leave no compression space in the said cylinder, two small side pistons'acting oppositely to and balancing the pressures on the large piston, two separate compression spaces each made in the form of a transverse channel leading from the outside edge of a small cylinder to one of the said passages leading to the central cylinder, and an injection valve at the outer end of each channeland directed inwardly toward the central cylinder.

JAMES MGKEGHNIE.

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