US2079156A - Two-cycle diesel engine - Google Patents

Description

y 1937. T. B. DANCKWORTT TWO-CYCLE DIESEL ENGINE Filed Feb. 27, 1953 2 Sheets-Sheet 1 INVENTOR.

-May 4, 1937. T. B. DANCKWORTT TWO-CYCLE DIESEL ENGINE 2 Sheets-Sheet 2 Filed Feb. 27, 1953 INVENTOR.

Patented May 4, 1937 22 Claims.

This invention relates to that type of internal combustion engine commonly known as Diesel engines. a

The objects of the invention are many, but it may be said that the primary object is to create a Diesel engine which shall be suiiiciently light in weight, small and compact in size, and of such simple and economical'construction, and be so strongly free from sensitivity to fuel qualities,

in 3 that it may be used generally for all those purposes to which the common gasoline engine is "nowput. Further objects are to produce such an engine which shall be especially adapted to modern high speed requirements incorporating ideal exhausting, scavenging and charging actions, and which shall at the same time possess perfect balance, be almost completely free from noise and vibration, have low-bearing pressures and inertia forces, and as a consequence be highly efficient. 2 Fundamentally the invention comprises an opposed piston structure where the opposed pistons of each unit'operate in the same cylinder, the engine being equipped for Diesel-type operation. The preferred form is a two-cycle type engine rather than four-cycle, one piston controlling the air inlets for scavenging and air charging purposes and the other piston controlling the exhaust ports. Each piston is connected by means of rods or links and a lever with a crank shaft, there being one crank for each piston and therefore only two cranks per cylinder. The cranks are disposed exactly 180 apart, there being no relative offset between the cranks. However the rocking levers are so located with respect to each other and the crankshaft that the dead centers of the two pistons are not.reached simultaneously; that is the one piston may open the exhaust ports before the other piston opens the scavenging ports for admission of scavenging air, 40 the exhaust ports being closed before the air inlet ports are closed. In order to accomplish this without offset of the two-cranks from the 180 relationship, the crank shaft center is shifted to one side of the center line of the pivots of the two swinging lever-ends; also the lever fulcrums or the position of the lever and pivot centers may be adjusted or fixed to secure required relationships, tie-rods between the fulcrum mountings being a desirable means. While according to the preferred arrangement the cylinder is disposed horizontally and the crankshaft also is disposed horizontally below and transverse to the middle of the cylinder, this arrangement is not essential, as is apparent.

For the purpose of clearing and filling the cylinder, air pumping means is provided. Preferably this is in the form of a stepped piston'construction of the opposed pistons as shown. Here the ends of the pistons remote from the explosion chamber are stepped up in diameter and pump 5 an adequate supply of air under suflicient pressure by way of ducts or channels, to the cylinder air-ports for the purpose of first scavenging and then filling the cylinder with an air charge. Vi hile the illustration shows a stepped piston arrangement, other means such as blowers or separate air pumps, may be provided. The oil or other liquid fuel is supplied through the medium of any type of fuel pump driven from the crankshaft in any manner desired.

A valuable feature in the opposed piston type two-cycle Diesel engine is the provision of an ante-chamber in which a thorough mixing and vaporization of the liquid fuel together with initial ignition is effected before the fuel'enters the combustion space between the pistons. This chamber is preferably arranged to create tangential air turbulence inside the chamber and to discharge-into the combustion space of the cylinder. lBy reason of such construction, air from the cylinder entering the pre-combustion chamher during the compression period creates a considerable air turbulence. Into the turbulent heated air body the fuel is injected at a time when the air is at approximately maximum turbulence. These conditions effect an intimate mixture of fuel and air particles under high relative motions, reducing the ignition time lag, assisted also by especially favorable heat conditions whereupon ignition promptly follows; Inasmuch as this concentrated action takes place in a small space and at once effects complete fuel-air mixture, it is not necessary that the fuel be injected by fine nozzles or with very high fuel pressures to produce a fine spray because the action is suiiicient to date even for a coarse spray, without reducing the ignition time lag materially. This simplifies spray apparatus and vaporization requirements. Thus, when the preheated and prepared fuel enters the explosion space of the cylinder between the pistons it is freely distributed by means of the pressure difference in the chamber and its flow energy. Then, as the additional portion of the liquid fuel charge is injected under high pressure preferably at rising fuel pressures, by the fuel pump, the action continues with the result that a properly prepared and air 'sup plied charge is fed to a preliminary charge already in process of ignition. The heat, turbulence and fuel injection conditions result in prompt and proper ignition and distribution of the whole charge inside the cylinder combustion space. Air turbulence may be ,promoted by means of air-receiving or storage chambers disposed in the heads of the pistons and adapted to receive from and discharge to the combustion space.

The invention, therefore, resides primarily in the combination of opposed pistons with twocycle Diesel engine controls, and especially where the pistons are connected by actuating levers to operate a crankshaft so set as to maintain proper relative piston movement while maintaining the cranks of the two pistons at 180. The invention also includes the combination of a pre-combustion chamber with an opposed piston engine. The invention resides also in the various combinations and arrangements above pointed out and in the methods of operation and ignition disclosed and in such other features of novelty as may elsewhere herein appear.

For a more detailed understanding of the in:- vention, reference is made to the accompanying drawings which serve to illustrate one embodiment of the invention. In these drawings:

Fig. 1 is a vertical longitudinal section through an engine constructed according to the present improvement, and taken approximately on the line I--I of Fig. 2;

Fig. 2 is a vertical cross section taken approximately on the line 2-2 of Fig. 1; and

Figs. 3, 4 and 5 are cross sectional details showing various arrangements for pre-combustion chambers capable of performing the desired functions, the showing being diagrammatic in character.

Figs. 6 and 7 illustrate a modification wherein air receiving and discharging chambers or pockets are provided in the heads of the pistons, Fig.

40 6 being a diagrammatic cross section indicating such a piston head together with a passage for supplying fuel from a pre-combustion chamber, and Fig. '7 being a fragmentary longitudinal section indicating fuel fed into the combustion space 45 of the cylinder directly from a fuel Jet.

The main cylinder block of the engine is designated III and its crank case is indicated at II. The block III houses the power cylinder I2 in which the two opposed stepped pistons I3 and I4 50 reciprocate in a preferably horizontal position. One end of the power cylinder is provided with a belt of inlet ports I5 for scavenging air, these being controlled by the leading edge of piston I3, and the other end of the cylinder I2 is pro- 55 vided with exhaust ports I6 which are controlled by piston I4. To the two opposite ends of the cylinder block III there are bolted two scavenging air cylinders I! in line with the cylinder I2, these air cylinders I! having lower housings or ex- 60 tensions I8 bolted to crank case II. The air cylinders I'I receive the enlarged stepped ends Ila and Na of the pistons I3 and I4, these enlarged ends serving as air pumps. The under sides of the air cylinders II are provided with openings I9 which pass the levers 20 and 2I that transmit the motion of the pistons I3 and I4 to a crank shaft 22. The reciprocation of the pistons is first transmitted by short connecting rods 24 and 25 to the upper ends of the levers 20 and 2|, whose lower ends in turn transmit to two cranks on the crank shaft 22 by way of slightly longer connecting rods 26 and 21. The two cranks of shaft 22 are without oifset with respect to each other, that is, they are 180 apart. It 75 will be noted that'the center of the crankshaft 22 is disposed at one side of (i. e. below) the line connecting the pivot centers of the lower ends of the levers 20 and 2i; however 'the crankshaft center could as readily be above said connecting or reference line depending upon the directional rotation of engine. It will also be noted that the crankshaft center line extends transversely of the axis of cylinder I2 and directly under the middle of said cylinder, and that all parts are of equal length and size and symmetrically disposed for the purpose of obtaining perfect balance. The leverarm ratio shown in the drawings is naturally not confined to this very proportion. It is understood that the many benefits derived from an uneven lever ratio may be utilized for the reduction of bearing pressures, inertia forces and piston speeds. Also, a shifting of the crank shaft center from the connecting line tangent to the arcs described by the pivot centers of the lower ends of said levers will produce any desired exhausting, scavenging and charging time periods. As to the fulcrums of the levers, these are carried respectively in adjustable mountings 28 and 29 whose lateral position may be adjustedas required by means of shims ll, the mountings being secured by means of a series of tie rods ll carried in the block I0. Also one may effect adjustment of the vertical position by slots in the fulcrum bearing blocks. This construction not only provides for suitable adjustment of the fulcrums but eliminates the tensile stresses of the engine block which can be made as light as possible. The effective offset of the crankshaft is of course necessary in the absence of oil'set of the two cranks from the 180 relationship, in order to cause one piston to trail the other in action so that the exhaust ports will be opened before inlet of scavenging air and be closed before the air inlet ports are closed. In addition such relative piston motions will accomplish substantially constant volume combustion.

In order that the enlarged ends Ila and Ma of the stepped pistons I3 and I4 may serve as air pumps as they reciprocate in the air cylinders I1, said enlarged ends are provided with air chambers 35 which receive air from the atmosphere by way of ports 26 in the cylinders I1 and cooperating slots 31 in the upper sides of the chamber walls of said enlarged piston ends. Valves 38 in the ends of the pistons permit air to be transferred by suction from chambers 35 into the chambers '39 within the air cylinders I'I, whence the air is pumped upon the return stroke past valves 40 into spaces 4I under the cylinder covers 42 and thence through annular passages 43 and 44 and passages 45 and 48 to an annular supply chamber 46 feeding the air inlet ports I5. Valves 4! may be provided for connecting the air spaces H with the crankcase space and the spaces within housings I8 when lower air pressures are required as speed builds up. This may be automatically effected through control by engine speed if desired. It is to be noted that by removal of the air cylinders I! with the extension hourings I8, ready access is obtained to the pistons I3, I4 and their rods and levers. As to the path of the air travel, the passages 43 and 44 are cast integral with the air cylinders I! as shown, and when the cylinders II are in operative position these passages communicate with air passages 45 and 48 which are cast integral within the engine block II, preferably outside the usual'water Jacket 4! of the block. Thus each of the passages ,4! and 48 is in communication with the passages 41 and 44 in the two air cylinders I1.

the engine block l0. With this construction the air passages are maintained in a cooled condition and thereby insure a suiiiciently cool air supply. For the purpose oi supplying liquid fuel a fuel pump 50 driven by the crank shaft22 may be employed, as indicated in Fig. 2, the pump 50 being adapted to force the fuel under pressure through a line 5| to an ejecting nozzle 52 for supply to the engine cylinder described above. The usual fly wheel 54 is shown mounted. on the crank shaft 22. A

According to the present invention the liquid fuel, instead of being sprayed directly into the combustion space between the opposed pistons of the two-cycle engine, is jetted from nozzle 52 into a removable pre-combustion or ante-chamber element 55 which is mounted in the engine block and communicates with the cylinder i2 by means ofa passage 56 shaped and directed to promote directional and timed turbulence within the pre-combustion chamber as air is forced into it under pressure from the combustion cylinder and to promote maximum dispersion of the resultant fuel vapor as it is subsequently forced into the explosion cylinder. The tangential arrangement shown in Figs. 2 and 5 efliciently produces the necessary swirls and eddy currents in both directions. Similarly the directing of the fuel stream across the incoming air streams as in Figs. 3 and 4 will produce the necessary turbulence in the ante-chamber, but non-tangential (symmetrical) distribution in the cylinder. As previously explained. this injection with comparatively low fuel pressures and high temperatures with air turbulence results in a high degree of vaporization and fuelconditioning without the necessity of especially fine fuel spraying with fine nozzles. In fact this conditioning is so efiective with this combination of ante-chamber and opposed piston construction, that the engine is not at all sensitive to fuel qualities anda wide range of fuels may be used if necessary or desirable. The separate construction of the precombustion chamber 55 is such as to cause it to retain heat and not give it up readily as do water cooled walls. Such heat aids vaporization of the fuel. This device 55, which may also be called a heat apron, acts as a temperature stabilizer, permits theuse of a wider range of fuels, the attainment of higher speeds by decreasing ignition time lag and reducing heat losses to water cooled walls and permits sloweridling speed and lower compression ratios, with consequent lower maximum pressures. The pre-combustion chamber 55 and passage 56 maybe flattened as indicated in Fig. l, for the purpose of improving the stated action.

The functions and operation of the engine will be generally understood from the foregoing. The

positioning of the center of crankshaft 22 with respect to the reference line tangent to the arcs described by the swinging pivot points of the lower ends of levers 20 and 2i, together with any adjustment of the fulcrum mountings 28 and 29 required for the particular engine or the particular use, will of course have been made, in order that one of the pistons (I 3) will trail the other so that the air scavenging inlet ports i5 will be opened by piston 13 after the exhaust ports i6 have been opened by piston l4, and will not be closed until after the exhaust ports have been closed. This movement results in a short interval when the pistons are near dead center during which they will be travelling in the same direction. It is obvious that these relative positions may be effected in various ways such as by variation in the lengths of the two arms-of the levers or in the shape thereof or by shifting the parts, for example by vertical adjustment of the fulcrum mountings 28, 29 which may be accomplished by shifting the tie-rods 3| vertically in the apertures Ma (Fig. 2) through which they pass, these apertures having sumcient play for purposes of any necessary adjustment. The air necessary for both scavenging and fuel purposes is pumped through chambers 39 and ti and passages 43, M, 45 and 48 to supply chamber and ports i5 as above described. When the cylinder i2 has been properly scavenged and the charge I of air has been trapped and properly compressed, the fuel pump 50 operates to commence high pressure injection of liquid fuel into the heated, highly compressed air charge in pre-combustion chamber 55. This promptly initiates combustion which is facilitated by the turbulence produced by the swirling air still entering the pre-combustion chamber. The result is a thoroughly vaporized and conditioned'fuel which is now ready for discharge into the combustion cylinder between pistons l3 and M. The inclined walls of the discharge passage 56 serve to distribute and accelerate the remaining fuel thoroughly into the cylinder as the expansion of the highly vaporized and ignited fuel progresses and as the injection of fuel into the pre-combustion chamber continues. As a, result properly'timed and controlled combustion phases take place, the resultant energy being exerted upon both pistons and being in turn transmitted to bothcranks of the shaft 22. The combustion and power cycle having passed, the piston It opens exhaust ports l6 and the pressure in the cylinder promptly drops to atmospheric, whereupon piston I3 opens the air inlet ports for scavenging and the entire cycle recommences. If a cheaper construction is required at the expense of volumetric efliciency, the stepped feature of the pistons may be dispensed with, the outer ends of the pistons (opposite the explosion ends) serving without enlargement as air-compressing surfaces.

It also is to be noted that the effects of the pre-combustion chamber 55 may be augmented byair-receiving or storage chambers 60 located in the piston heads as shown in Figs. 6 and 7, these chambers being of a'shape suitable to create additional turbulence along with a directional air feeding action produced by their nozzle-like discharge ports 62. Or, these chambers 60 may be used alone and the pre-combustion chamber 55 omitted. In this case the fuel injection is made directly into the combustion space proper between the pistons. Either an'angement'a-ugments the air turbulence produced by piston movement, by reason of the discharge or escape of air from chambers 60 when the pistons enter upon their outward strokes.

The engine here presented is capable of ordinary high speed uses up to the range of 3000 to 4000 R. P. M. and has all the advantages previously set out herein. While the engine is indicated as being used in a horizontal position, it is obvious that it may be turned so that the cylinder axis is vertical, or so that the crank shaft is vertical, or the crank shaft could in fact be mounted above the cylinder. Obviously the engine may be built in any number of cylinder units.

From the foregoing it will be apparent that I have presented a structure in which the following features are new: (1) the use of an antechamber in oppos d piston engines; (2) the design of passage-connections therewith to control and direct the air turbulence in the chamber going inward as well as the control of combustion gases moving outwardinto the cylinder, Fig. 3; (3) the creation of uni-directional turbulence in the cylinder combustion space, Figs. 3 and 4; (4) the coordination of organized, port-controlled and directed cylinder air turbulence of either rotation with said chamber-produced hot tubulence,\Figs. 3 and 4; (5) the use of chamber gas-flow and energy-for creation of directional"-rotational cylinder turbulence and consequent fuel and air distribution, Figs. 2 and 5; (6) the combination of directional chamberproducts flow together with port-directed and controlled cylinder turbulence of either rotation, Figs. 2 and 5; (7) direct injection with air-storage-chamber-energy turbulence and distribution, Fig. 6.

It is to be understood that the embodiments here presented are merely illustrative and are not to be taken as limiting, since many variations of the generic invention may be made within the scope of the claims by those skilled in the art.

I claim:

1. A two-cycle Diesel engine comprising an engine block having a cylinder, opposed pistons mounted to reciprocate in the opposite ends of the cylinder and a crankshaft having a crank for each piston, the cylinder having air ports controlled by one piston and exhaust ports controlled by the other piston, a housing mounted over the outer end of each piston and having an air cylinder whereby the outermost face of the outer end of each piston constitutes an air pump, each piston having an air space therewithin, a valve in the outer end of each piston controlling a discharge port from said air space and communicating with the air chamber beyond each piston, and

means admitting atmospheric air into the air space in each piston, said engine block having an air passage cast integrally therein and communicating with each of said air cylinders and with said air ports.

2. A two-cycle Diesel engine having a cylinder, opposed pistons having closed outer ends, the pistons reciprocating in the opposite ends of said cylinder, a crankshaft, and a crank for each piston, the cylinder having air ports, an air chamber connected with the outermost face of outer end of, each piston whereby the outer end of each piston constitutes an air pump, each piston having an air space therewithin, a valve in the outer end of each piston controlling a discharge port from said air space and communicatingwith the air chamber beyond each piston, and means admitting atmospheric air into the air space in each piston, and means providing an air passage from said outer end to said air ports.

3. A structure according to claim 2 including valves in the outer ends of the pistons, and means admitting atmospheric air to the rear of said valves.

- 4. A structure according to claim 2 including a closed crankcase for the crankshaft, said crankcase being connected with the air chambers by means of valved passages.

5. A two-cycle Diesel engine comprising a cylinder block having a cylinder, two opposed pistons working in said cylinder, a crank shaft carried by said block, fulcrumed levers connecting the pistons with said crank shaft, a housing mounted over the outer end of each piston and havingan air chamber whereby the piston end constitutes a pump, means to supply air from said chamber to the cylinder, a closed air-tight crank case about the crank, and valved passages connecting said air chambers with the space within the crankcase.

6. A two-stroke cycle Diesel engine comprising a cylinder, opposed pistons facing each other and reciprocating in the opposite ends of the cylinder, a crankshaft having a crank for 'each piston, a lever for each piston having its ends connected with its piston and crank by-connecting rods, 2. fulcrum mounting secured in fixed position on each lever, means for adjustably mounting said fulcrum mountings on the engine, the two arms of each lever having unequal lengths thus providing an unequal lever ratio between each piston and its crank.

7. A two-cycle Diesel engine comprising a cylinder, opposed pistons working in the cylinder, a precombustion chamber communicating with the combustion space between the pistons by means of a single restricted duct disposed perpendicularly to the axis of the cylinder, and means to inject fuel into the precombustion chamber, said restricted duct being tangentially arranged with respect to the walls of the precombustion cham-' ber to inject air tangentially thereinto to produce air turbulence therein for fuel conditioning in the precombustion chamber, said duct being also tangentially arranged with respect to the cylinder walls to inject fuel tangentially into the cylinder to create turbulence therein for fuel dispersion.

-8. A method for supplying fuel to a two cycle Diesel engine having two opposed pistons working in a common cylinder and having a pre-combustion chamber in communication with the cylinder, comprising supplying air to the combustion space between the pistons, compressing the air and effecting turbulence in the pre -combustion chamber-as the air is forced thereinto under compression, injecting liquid fuel into the precombustion chamber while under compression whereby the turbulence in the air and the high temperature of compression effects vaporization and initial ignition, continuing the injection of the liquid fuel into the pre-combustion chamber to the extent of the fuel charge,etlfecting dispersion of the fuel charge to the cylinder, and imparting further turbulence by injecting air into the charge in the cylinder during the outward piston stroke.-

9. In an internal combustion engine of the Diesel type, a cylinder having air intake and exhaust ports, a piston working therein, a housing carried by said cylinder having a duct communicating with the cylinder combustion space, a separate pre-combustion chamber element mounted within said housing and constituting a heat apron which retains heat to facilitate ignition, a port in said element communicating with said duct, and means to inject fuel into said element, the element being free from valves and other moving parts.

10. A structure according to claim 9 wherein said duct is directed perpendicularly to the axis of the cylinder.

11. A structure according to claim 9 wherein the precombustion chamber element is flattened in one direction.

12. A structure according to claim 9 wherein with respect to the side walls of both the cylinder and the precombustion chamber.

13. A method for supplying fuel to a Diesel type engine having a cylinder in which opposed pistons reciprocate and in which a precombustion chamber is provided communicating with the cylinder I by a duct tangentially disposed with respect to the side walls of both the cylinderand said chamber, which comprises compressing air between the pistons and in said precombustion chamber, injecting fuel into said chamber while hot and under high compression with the air therein in a turbulent state due to said tangentiality and whereby the charge is ignited thereby causing the charge to be injected through said duct into said cylinder tangential to the cylinder walls, and producing a port-controlled rotary turbulence in said cylinder.

14. A two-cycle engine comprising a cylinder block having a cylinder, opposed pistons working in the cylinder, the cylinder having exhaust and air inlet ports controlled by the pistons, a crankshaft, lever driving mechanism between each piston and the crankshaft, bearings for the fulcrums of the two levers, means for moving said bearings vertically into adjusted position, and means for moving said bearings horizontally.

15. A two-stroke cycle Diesel engine having a cylinder, opposed pistons reciprocating in the opposite ends of the cylinder, a crankshaft having a crank for each piston, said cranks being disposed at approximately 180 to each other, a connecting rod for each piston, a fulcrumed lever for each piston having its ends connected with the respective connecting rod and with the respective crank to drive the crankshaft, the cylinder being provided with air ports controlled by the leading edge of one piston and with exhaust ports controlled by the leading edge of the other piston, the fulcrum for each lever having a fixed position on said lever, and means to adjust the fulcrum vertically and horizontally to cause the pistons to open the air ports after opening of the exhaust ports and to close the air ports after closing of the exhaust ports.

16. A two-stroke cycle Diesel engine having a cylinder, opposed pistons in the cylinder, a crankshaft having a crank for each piston, said cranks being arranged at approximately 180 .to each other, the cylinder having air inlet ports and exhaust ports controlled by the pistons, lever connections between the pistons and their cranks whereby the pistons drive said crankshaft, said pistons being stepped to provide an enlarged outer end for each piston, a housing providing an air cylinder for each enlarged outer end, whereby the outermost faces of the step pistons constitute air pumps, each piston having an air space therewithin, a valve in the outer end of each piston controlling a discharge port from said air space and communicating with the air chamber beyond each piston, means admitting atmospheric air into the air space in each piston, and means providing conduits for supplying the air from the tie-rods connected with and extended longitudinally of the cylinder and connected with the bearings for the lever fulcrums and binding said bearings to the cylinder block, the cylinder block being disposed between said bearings.

18. A structure according to claim 15 comprising tie-rods extending longitudinally of the full length of the cylinder, the bearings for the fulcrum being disposed adjacent the ends of the cylinder, and tie-rods binding said bearings against the cylinder.

19. A structure according to claim 7 including tie-rods extending longitudinally of the length of the cylinder, the fulcrum mountings being disposed adjacent the opposite ends of the cylinder andsaid tie-rods binding said fulcrum mountings in position upon the cylinder.

20. A structure according to claim 12 comprising air inlet ports controlled by the pistons whereby said ports tend to impart a directed rotary air turbulence in the cylinder coacting with the air turbulence induced in the cylinder from the precombustion chamber.

21. A two-cycle symmetrical opposed-piston Diesel engine comprising a cylinder block and crank case unit having a cylinder, opposed pistons in opposite ends of said cylinder, a crankshaft in said crank case radially opposite said cylinder and symmetrically disposed with respect to the working center of the cylinder, connecting rods and a-lever symmetrically connecting each piston with a corresponding crank of the crankshaft,

unit extending longitudinally therethrough and THOMAS BRUNO DANCKWOR'I'I.

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