US2067171A

US2067171A - Engine

Info

Publication number: US2067171A
Application number: US653252A
Authority: US
Inventors: Ralph H Beard
Original assignee: Individual
Current assignee: Individual
Priority date: 1933-01-24
Filing date: 1933-01-24
Publication date: 1937-01-12
Anticipated expiration: 1954-01-12

Description

Jan. l2, 1937." R. H. BEIARD ENGIB A Filed Jam. 24, 1933 5 Sheets-Sheet l Mw @@w \l` xllVENTOR @OW R. H. BEARD ENGINE Filed Jan. 24, 1933 Jan. 12, 1937.

5 Sheets-Sheet 2 NNN NNN NNN NNN lnlv A wm. NW. 1 u v ,/NN

A@ uw nWEN-ljora my ATTORN Y 5 Sheets-Sheet 5 ENGINE Filed Jan. 24, 1933 Rf H. BEARD l. Il. n

Jan. 12, 1937. V

Patented Jan. 12, 1937 UNITED STATES PATENT OFFICE 23 Claims.

The invention is applicable to engines of the internal combustion type as well as to engines in which a gas or liquid under pressure is introduced from an external source. The invention will be fully understood from the following description read in conjunction with the drawings, in which:

Fig. 1 is a diagram illustrating in polar coordinates the relationship between piston position and angular displacement of crank shaft.

Fig. 2 is a corresponding view of a piston and crank shaft, in which the crank shaft is in a different angular position.

Fig. 3 is a longitudinal section through one embodiment of my invention.

Fig. 4 is an end View of the construction shown in Fig. 3.

Fig. 5 is a longitudinal section through the construction shown in Fig. 3 at a right angle to the showing in Fig. 3.

Fig. 6 is a longitudinal section through part of a further embodiment of my invention.

Fig. 7 is a longitudin-al section through part of a steam engine constructed in accordance with my invention.

Fig. 8 is a corresponding section through part of an internal combustion engine constructed' in accordance with my invention adapted to utilize an explosive charge.

Fig. 9 is a cross section through an alternative embodiment of my invention.

Fig. 10 is a detailed section through a piston adapted for use in the type of engine shown in Fig. 9.

Fig. 11 is a perspective View of the construction shown in Fig. 10.

Fig. 12 is an exemplified perspective view of a part of the construction shown in Figs. l0 and 11.

Fig. 13 is a diagram illustrating the preferred sequence of cycles used in the engine shown in Figs. 14 and 15.

Fig. 14 is Ia longitudinal section through a further alternative embodiment of my invention.

Fig. 15 is a side View of the construction shown in Fig. 14.

Fig. 16 is a cross section through the construction shown in Fig. 14, on the plane indicated by I-I.

Fig. 17 is a longitudinal section through a further alternative embodiment of my invention.

Fig. 18 is a cross section through the construction shown in Fig. 17, on the plane indicated by II-II.

Fig. 19 is a diagram illustrating the preferred (Cl. 12S-51) sequence of cycles utilized in combination with the engine shown in Figs. 17 and 18.

Fig. 20 is a diagram illustrating the preferred sequence of cycles utilized in combination with the engine shown in Figs. 22, 23 and 24.

Fig. 21 is a diagram indicating the preferred sequence of cycles used in combination with the type of engine shown in Figs. 26 and 27.

Fig. 22 is a longitudinal section through a further alternative embodiment of my invention.

Fig. 23 is a perspective view of part of the construction shown in Fig. 22.

Fig. 24 is a cross section through the construction shown in Fig. 22, on the plane indicated by III-III.

Fig. 25 is a longitudinal section showing a cooling method alternative to that shown in Fig. 22.

Fig. 26 is a longitudinal section through a further alternative embodiment of my invention.

Fig. 27 is a cross section through the construction shown in Fig. 26, on the plane indicated by IV-IV, and,

Fig. 28 is a longitudinal section through a further alternative form of piston, piston rod assembly, showing a further alternative cooling method. f

The scope of the invention may be developed by the following exposition of the theory in volved. Referring specifically to Fig. 1, I diagrammatically indicate in polar coordinates a piston I adapted to reciprocate in cylinder 2. The piston is connected to piston rod (3) (a) which is in turn connected through journal 4 and pin 5 to connecting rod (6) (b). The connecting rod is journalled to crank (7) (c) which is assumed to rotate about the origin of coordinates O making at any instant the angle e with respect to the line 8. 'I'he distance of the piston from the origin at any moment may be algebraically expressed by the following equation:

S=ai1/b2-c2 sin2 Q-c cos. 9 (1) In Fig. 2, I have diagrammatically indicated a second piston II adapted to reciprocate in cylin- Y der 2. Piston Il is connected to piston rod (I3) (d) which is in turn connected through journal I4 and pin I5 to connecting rod (I6) (e). The connecting rod is journalled to crank (I1) (b).

The crank is assumed to rotate about the same origin as before but at an angle g in advance of crank (1) (c) so that the angular position of crank I1) (b) may be algebraically represented by e--g with respect to line 8. In this case, the

distance of the piston II from the origin of coordinates may algebraically be represented by the equation:

s'=d+1/e2-f2 sire (eJrQ-f cos. (wfgi (2) In carrying out my invention, I mount pistons and Il in a common cylinder with both cranks connected to a common crank shaft 9. This position is diagrammatically illustrated in Fig. 3. The preferred method to accomplish this is to mount piston rods (3) (a) and (I3) (d) in

channels

20 and 2| in the wall of cylinder 2 as illustrated in Figs. 4 and 5. When so mounted, it is apparent that the pistons will alternately approach and retreat as the crank shaft 9 rotates. In general, and particularly where g is within the range of this can be utilized in accordance with my invention in the formation of a prime mover which has certain unique and highly desirable properties. For convenience in` presentation all angles will be hereinafter expressed in radians.

The distance s between the pistons for any value of g may be derived from the equation:

ds --c2 sin (Q-I-g) cos (Q-l-g) Q de L12-c2 sin2(9+g) +C sm( +g)+ c2 sin 9 cos 9 Y bZ--c2 sin 9 This equates to zero at the points for which sin. 9+g=sin. 9 viz, at the points for which -c sin 9 (4V) where n may be any number. It follows from this that the maximum value ofV s=4c cos. 9 at this point. 'Ihe shorter piston rod must be at least 2c in length to allow clearance. The other piston rod must equal the length of the shorter rod -f- 4c cos. e at the value of o corresponding to the maximum Value of s, -1- the necessary clearance between pistons.

In the form illustrated by the gures hereinabove considered with only two connecting rods, g is preferably equal to 11- and this form is diagrammatically indicated in Fig. 6. With respect thereto, it will be noted that the working pressure is simultaneously applied to two pistons moving in opposite directions, both of which drive a s-ingle crank shaft, thereby increasing the ef- Afective torque for any specific pressure so that the; rate ofY expansion is double the rate which couldbe obtained' with a single piston operating inra cylinder with a fixed head; and that the gas isdischarged at the end of the stroke at a much lower. pressure than would be the case with a single: piston type.

l This' construction may be utilized to advantage in an engineof the type in which the pressure is,A externally generatedgcf an hydraulic or steam engine, and such' an engine is diagrammatically shown in Fig. '1 in which steam is supplied through pipe 28 to the steam inlet valve 29 which comprises chest 39, valve seat 3|, and slide 32 suitably operated by rod 33 which enters the chest through stuiing box 34. The exhaust valve 38 similarly comprises educt 39, chest 4U, valve seat ell, and .slide 42 suitably operated by rod i3 which enters the chest through stufng box 44.

The preferredv application of my construction is, however, in an engine of the internal combustion type, and such an engine is diagrammatically indicated in Fig. 8, in which the inlet valve comprises the offset 5|, valve seat 52,

`poppet 53, valve stem 5i and intake manifold 55.

The exhaust valve similarly comprises offset 6|, valveseat 52, poppet valve 63, valve stem 64 and exhaust manifold 65. The charge may be ignited in any suitable way, and the engine may for example be adapted for spark ignition, semi- Diesel or full Diesel operation. Where ignition is by spark, the plug 56 projecting into intake chamber 51 may be utilized.

I have found it to be of further advantage in this connection to makethe cylinder of rectangular cross section and to make the piston rods flush with one or more of the inner plane surfaces of the cylinder. This type of construction is exemplified in end View in Figs. 9 and l1, and comprises cylinder 10 rst piston rod 1|, attached piston 12, and second piston rod 13. Rod 1| reciprocates in channel 111, and rod 13 reciprocates in channel 15. This is preferably utilized in combination with a special type of piston and piston ring exemplified in Figs. 10, 11 and 12, in which piston 12 is formed with groove 39 (Fig. 11) which carries split sealing member 8| consisting of overlapping

portions

32 and 83. These are urged outwardly against the cylinder walls by

coil springs

84 and 85 with seat in

holes

86 and 81 formed in piston 12 As illustrated in Fig. 9, with this type of construction both exhaust and intake valves may be conveniently located in header 9|) which communicates with the cylinder. The intake Valve may comprise seat 92, poppet 93, spring Sli and rod 95 connected to intake manifold 95. The exhaust valve may comprise seat |90, poppet 15|, spring |02 and rod |93 connected to exhaust manifold |94. The charge may be ignited by means of spark plug |95 although this type of engine may also be adapted for Diesel or Ysemi- Diesel operation.

The water jacket |95 may be provided for the purpose of cooling the engine.

In the types hereinbefore illustrated, each piston rod carries but one piston. The invention is not however limited to this construction; in fact certain salient advantages are achieved by suitably extending the cylinder and designing the engine so that two or more pistons are carried by each rod. This form of construction is schematically shown in Figs. 14, 15 and 16, in which rod 3) (a) carries pistons lli), and H2 while rod (I3) (d)Y carries pistons H3 and H4. The cranks (1) and (I1) (f) are preferably set at an angle 1r with respect to each other. In this case it will be noted that the pistons form four intermediate spaces i213, |2|, |22 and |23 bounded by the inner Walls of the cylinder and adjacent piston surfaces.

In operation, one half of these spaces are simultaneously expanding and one half contracting at any given instant of time, and the cylinder is thereby divided longitudinally into several independent overlapping strokes. Fig. 16 illustrates a cross-section through this construction on a plane midway between adjacent iston faces in the position of minimum clearance, for example through the plane indicated by I-I in Fig. 14 or through corresponding planes indicated by spark plugs lii, |31, |32 and |33 in Fig. 15. In this construction parts corresponding to those shown in Fig. 16 are indicated by corresponding numerals, and the continuation of intake manifold 96 appears in side view in Fig. 15. rlhe preferred sequence of cycles for this type of engine is illustrated diagrammatically in Fig. 13 in which working spaces, viz, spaces between adjacent piston faces, are indicated as ordinates, and the angular displacement of one crank with respect to the radius vector, 9:0 is indicated as abscissa.

This construction affords a favorable ratio of power to weight. In the usual type of engine there is a certain ratio of cylinder cross sectional area to length of stroke which cannot be exceeded for efcient operation; with the type illustrated, however, there is no such limitation inasmuch as the cylinder is divided into several separate strokes. For this reason. two or more times as much force may be applied to the crank shaft from a single cylinder as is possible with the usual type of engine. With respect to the steam type of engine having a single piston operating in a cylinder with a xed head, the stuffing box and cross head are eliminated, while at the same time retaining equal or greater uniformity of torque.

As stated, the engine which I have invented is especially well adapted for use as an internal combustion engine. In this case the construction operates to inhibit knocking at initial compressions where the knocking would be vpronounced in the ordinary type of internal combustion engine operating on identical fuel.

A further feature of advantage in this type of engine is the fact that certain spaces may be in explosion and expanding, while other spaces are in compression and contracting, with the result that the power necessary for compression is principally communicated from adjacent spaces, and in any event directly through the piston rods, and does not constitute a load on the crank shaft, connecting rods, and associated bearings. The fact that certain spaces are in compression also operates to arrest the momentum of the piston rod at the expiration of any stroke and facilitates smoother operation.

While in the form of engine illustrated in Figs. 14, 15 and 16 the pistons and cylinder collectively dene four working spaces, it will be apparent that any multiple of the same may be employed to advantage. With this type, the number of explosions per cycle is identical with that derivable from the usual four cycle four cylinder engine. The term cycle, as herein employed denotes a movement of the crank shaft through an angle equal to 1r. The operation is somewhat smoother, inasmuch as the force applied to the crank shaft by any connecting rod is balanced by an equivalent force of opposite direction applied to the crank shaft by the other connecting rod.

Additional working spaces may be easily incorporated without any increase in the length of crank shaft or number of connecting rods, and without the relative increase in weight which would accompany a corresponding increase in the number of working spaces in an internal combustion engine of the prior art. For this reason I find a particular advantage in the construction shown in Figs. 17 and 18 when operated with the sequence of cycles shown diagrammatically in Fig. 19.

In this construction there are two piston rods |40 and |551. The construction of connecting rods, cranks. crank shaft, etc., correspond to that shown in Figs. 14 and l5 and need not therefore be more fully described. Rod IMI carries pistons lll-l. |62, 1&3 and |44. Rod 50 carries pistons IEl, |52 and |53. The cylinder 2 and adjacent piston faces dene collectively six working spaces |6| to linclusive. Each working space overlaps in part the contiguous working space. It will be apparent from Fig. 1'1 that at any instant three of these spaces are in contraction and three in expansion. This renders it convenient to operate by means of valve 589 in Fig. 18 on a six cycle basis in which each working space passes through the usual four cycle operation, viz, charge intake. compression, explosion and exhaust followed by a cycle of fresh air intake and a cycle of fresh air exhaust. The scavenging operation introduced by the fresh air cyclesl eliminates dead gases more completely than is possible in the usual four cycle operation and imparts cooler operation together with greater thermal eflciencies. Referring specifically to Fig. 18. which is a cross section through the construction shown in Fig. 1'7 on any plane midway between adjacent piston faces in position of minimum clearance, the charge intake is controlled by the valve |69, comprising seat 10, poppet |1|, rod |12 and spring |13. the valve is connected to intake manifold |14. is controlled by valve |19 comprising seat |80, poppet |8. rod |82 and spring 83, the exhaust valve is connected to exhaust manifold |85. The fresh air intake is controlled by valve |89, comprising seat |90, poppet |9|, rod |92 and spring |93. This valve is shown in direct communication with the atmosphere, although a fresh air manifold connected to an air cleaner may be employed. The air on the discharge cycle may be discharged through the exhaust valve and exhaust manifold. The appropriate valve controlling mechanism may be supplied by a mechanic or engineer familiar with this disclosure.

By an extension of my invention, however, I am enabled to obtain in a single cylinder a torque substantially equal to that derivable from a twelve cylinder four cycle engine. The construction preferably employed for this purpose is illustrated in Figs. 22 to 26. It will be noted that in this case I employ three piston rods, each of which is "7r Each of these is set at an angle M with respc 3 to the other cranks. Crank 28| is journalled to connecting rod 2M. crank 222 is journ'illed to connecting rod 2 l and crank 293 is journalled to connecting rod 2|2. These connecting rods are in turn journalled respectively to piston rods 225, 23S and 24S. Rod 220 carries pistons B2i and 222.

The exhaust Rod 23|! carries pistons 23|, 232 and" fill Cri

233. Rod 246 carries pistons 26| and 242. These reciprocate in cylinder 25D which is of rectangular cross section and carries Water jacket 25|.

In this case, the valve construction is sho-wn diagrammatically in Fig. 24 which is a cross section through the construction shown in Fig, 22 on any plane midway between adjacent piston faces in position of minimum clearance. The intake is controlled by valve 259, comprising seat 260, poppet 26|, rod 262 and spring 263. The valve is connected to intake manifold 264. The exhaust is controlled by valve 269, comprising seat 21D, poppet 21|, rod 212 and spring 213. The exhaust valve is connected to exhaust manifold 214. These valves open into header 265 which is connected into the working space.

In this case, by reference to Equation (3) hereinabove it will be noted that the minimum clearance between the pistons carried by a pair of connecting rods will occur when the crank is at and the leading crank is at an angle The maximum clearance will occur when an angle 11 ing crank is at an angle 6 Each pair of cranks maintains a cycle which either leads or follows the cycle of any other pair of cranks by the angle Where this is operated four cycle, the working diagram is indicated in Fig. 2U. In this case it will be noted that there are three explosions for each angular movement of a crank through the angle 27T. and that each explosion overlaps the explosion of the leading and the following cycle. With this type the smoothness of operation is therefore substantially equivalent io that derivable from the usual four cycle six cylinder engine.

Where three piston rods are employed, I find it of advantage to follow each four cycles of charge intake, compression, explosion and exhaust with a fresh air of intake cycle and a fresh air exhaust cycle. A construction adapted to this purpose is shown diagrammatically in Figs; 26 and 2"?. In this case, piston rods 286, 296 and 300 reciprocate in cylinder 216 of rectangular cross section. Inasmuch as the construction of connecting rods is similar to that shown in Fig. 22, it need not be more fully described. In this case, piston rod 280 carries pistons 28|, 282 and 283. Piston rod 290 carries pistons 29|, 292, 293 and 294. Piston rod V306 carries pistons 30|, 302 and 363. The cylinder and pistons collectively define nine working spaces 32| to 329 inc. Each working space is individually defined by the cylinder and adjacent opposed piston faces. Of these spaces, three defined by thev cylinder and the adjacent opposed faces of the'pistons carried by any selected pair of piston rods will be expanding or contracting at any instant of time. The spaces defined by the cylinder and the adjacent faces of the pistons carried by any other pair of piston rods will either lag or lead by an angle of The sequence of cycles is shown diagrammatically in Fig. 21, in which the spaces 32| to 329 appear as ordinates and the angular movement of any selected crank is plotted as abscissa. The necessary mechanical movement to operate the valves can be supplied by a mechanic or engineer familiar with this disclosure. The valve construction, per se, will be apparent from Fig. 27 which is a cross section through the construction shown in Fig. 26 on any plane midway between adjacent piston faces in position of minimum clearance and in which intake is controlled by valve 340, comprising seat 34|, poppet 342, rod 343 and spring 344. The valve is connected to intake manifold 339. Exhaust is controlled by Valve 356, comprising seat 35|, poppet 352, rod 353 and spring 354. The exhaust valve communicates with exhaust manifold 349. The fresh air intake is controlled by Valve 369, comprising seat 36|, poppet 362, rod 363 and spring 364. The valves open into header 365 which communicates with the working space. The cylinder 361 is cooled by water jacket 368.

In Fig. 25 I have illustrated an alternative means for cooling pistons and piston rods. The pistons 310 and 31| shown in horizontal section are hollow, stationary jets 312 and 314 direct air or equivalent cooling medium against the side of the piston rod 315 and against the interior of the pistons whenever the same are in registry with the jet. Pistons 38|] and 38| carried by rod 382 are similarly cooled by means of

jets

383 and 384.

A further alternative cooling arrangement is exempliiied in Fig. 28, in which the piston rod 390 is hollow and the piston rod in combination with the hollow pistons 39|, 392 and 393 form a continuous passageway through which air or equivalent cooling medium may be forcibly circulated. The cooling medium is diverted into the bodies of the hoilow pistons by

baiiles

364, 395 and 396.

The foregoing description is for purposes of illustration and not of limitation, and it is therefore my intention that the invention be limited only by the appended claims or their equivalents, wherein I have endeavored to claim broadly all inherent novelty.

I claim:

,1. An engine of the reciprocating piston type comprising a cylinder of rectangular cross section. a rst piston adapted to reciprocate in said cylind^r. a rst piston rod flush with one of the plane surfaces cf said cylinder connected to said first piston. a first connecting rod connected to said piston rod, a crank connected to said connecting rod. a crank shaft including said crank, a second piston adapted to reciprocate in said cylinder, a second piston rod flush with one of the plane surfaces of said cylinder connected to said second piston, a second connecting rod connected to said second piston rod, a second crankV connected to said second connecting rod included in the crank shaft mentioned, and means for applying uid pressure to adjacent opposed piston faces during at least a part of the intervals in which said pistons are receding.

2. An engine according to claim l, in which. the

vangle between said rst and second cranks is between gandw 3. An engine according to claim 1, in which the number of said piston rods is exactly two and in which the angle between said rst and second cranks is 1r.

4. An internal combustion engine of the reciprocating piston type comprising a cylinder of rectangular cross section, a first piston adapted to reciprocate in said cylinder, a iirst piston rod flush with one of the plane surfaces of said cylinder connected to said first piston, a first connecting rod connected to said piston rod, a crank connected to said connecting rod, a crank shaft including said crank, a second piston adapted to reciprocate in said cylinder, a second piston rod flush with one of the plane surfaces of said cylinder connected tol said second piston, a second connecting rod to said second piston rod, a second crank connected to said second connecting rod included in the crank shaft mentioned, means for introducing and means for igniting a charge in the space defined by said cylinder and the contiguous faces of said first and second pistons during at least a part of the intervals in which said pistons are receding.

5. An engine according to claim 4, in which the angle between said first and second cranks is between g and 1r 6. An engine according to claim 4, in which the number of said piston rods is exactly two and in which the angle between said first and second cranks is 1r.

7. An engine of the reciprocating piston type, comprising a. cylinder of rectangular cross section, a. rst group of pistons adapted to reciprocate in said cylinder, a rst piston rod connected to each of said first group of pistons, said piston rod being ush with one of the piane surfaces of said cylinder, a first connecting rod connected to said piston rod, a first crank connected to said connecting rod, a crank shaft including said crank, a second group of pistons adapted to reciprocate in said cylinder, a second piston rod connected to each of said second group of pistons, said second piston rod being flush with one of the plane surfaces of said cylinder a second connecting rod connected to said second piston rod, a second crank connected to said second connecting rod and included in the crank shaft mentioned, and means for applying fluid pressure to adjacent opposed faces of said pistons during at least a part of the intervals in which said pistons are receding.

8. An engine according to claim 7, in which the angle between said rst and second cranks is between g and ir.

9. An engine according to claim 7, in which the number of said piston rods is exactly two and in which the angle between said first and second cranks is 1r.

10. An engine of the reciprocating piston type comprising a cylinder of rectangular cross section, a first group of pistons adapted to reciprocate in said cylinder, a first piston rod flush with one of the plane surfaces of said cylinder connected to each of said rst group of pistons, a first connecting rod connected to said first piston rod, a first crank connected to said first connecting rod, a crank shaft including said crank, a second group of pistons adapted to reciprocate in said cylinder, a second piston rod flush with one of the plane surfaces of said cylinder connected to each of said second group of pistons, a second connecting rod connected to said second piston rod, a second crank connected to said second connecting rod and included in the crank shaft mentioned, a third group of pistons adapted to reciprocate in said cylinder, a third piston rod ush with one of the plane surfaces of said cylinder connected to each of said third group of pistons, a third connecting rod connected to said third piston rod, a third crank connected to said third connecting rod and included in the crank shaft mentioned, and means for applying fluid pressure to adjacent opposed piston faces during at least a part of the intervals in which said piston faces are receding.

11. An engine according to claim 10, in which the angle between any two cranks is 33E l2. An engine of the reciprocating piston type, comprising a common cylinder, a set of pistons at least three in number adapted to reciprocate in said cylinder, a set of piston rods, a set of connecting rods, a set of cranks, a common crank shaft including said cranks, each of said cranks being set at a uniform angle to any one of two adjacent cranks, each one of said pistons being connected through one of said connecting rods to one of said cranks.

13. An engine according to claim 12 in which the angle between any two adjacent cranks is 21r divided by the number of cranks composing the said set.

14. An engine of the reciprocating piston type, comprising a common cylinder, a first piston, adapted to reciprocate in said cylinder, a first piston rod connected to said first piston, a first connecting rod connected to said piston rod, a first crank connected to said connecting rod, a crank shaft including said crank, a second piston adapted to reciprocate in said cylindera second piston rod connected to said second piston, a second connecting rod connected to said second piston rod, a second crank connected to said second connecting rod and included in the crank shaft mentioned, a third piston adapted to reciprocate in said cylinder a third piston rod connected t0 said third piston, a third connecting rod connected to said third piston rod, a third crank connected to said third connecting rod and included in the crank shaft mentioned, each of said cranks being set at a uniform angle to any one of two adjacent cranks, and means for applying fluid pressure to adjacent opposed piston faces during at least a. part of the intervals in which said piston faces are receding.

15. An engine according to claim 14 in which the angle between any two adjacent cranks is 21r is 16. An engine of the reciprocating piston type comprising a cylinder, a first group of pistons adapted to reciprocate in said cylinder, a first piston rod connected to each of said first group of pistons, a rst connecting rod connected to said piston rod, a first crank connected to said connecting rod, a crank shaft including said crank, a second group of pistons adapted to reciprocate in said cylinder, a second piston rod connected to each of said second group of pistons, a second connecting rod connected to said second piston rod, a second crank connected to said second connecting rod and included in the crank shaft mentioned, a third group of pistons adapted to reciprocate in said cylinder, a third piston rod connected to each of said third group .of pistons, a third connecting rod connected to said third piston rod, a third crank connected to said third connecting rod and included in the crank shaft mentioned, each of said cranks being set at a uniform angle to any one of two adjacent cranks and means for applying fluid pressure to adjacent opposed piston faces during at least a part of the intervals in which said piston faces are receding.

17. An engine according to claim 14 in which the angle between any two cranks is 18. An engine of the reciprocating piston type comprising a common cylinder, a rst piston adapted to reciprocate in said cylinder, a first piston rod flush with one of the surfaces of said cylinder connected to saidfirst piston, a first connecting rod connected to said piston rod, a crank connected to said connecting rod, a crank shaft including said crank, a second piston adapted to reciprocate in said cylinder, a second piston rod ush with one of the surfaces 4or" said cylinder connected to said second piston, a second connecting rod connected to said second piston rod, a second crank shaft connected to said second connecting rod included in the crank shaft mentioned, and means for applying fluid pressure to adjacent opposed piston faces during at least a part of the intervals in which said pistons are receding.

19. An engine according to claim 18, in Which the angle between said first and second cranks is between l lg and 1r 20. An engine according to claim 18, in which the number of said piston rods is exactly two and in which the angle between said rst and second cranks is 1r.

21. An internal combustion engine of the reciprocating piston type comprising a common cylinder, a rst piston adapted to reciprocate in said cylinder, a first piston rod flush with one of the surfaces of said cylinder connected to said first piston, a first connecting rod connected to said piston rod, a crank connected to said connecting rod, a crank Shaft including said crank, a second piston adapted to reciprocate in said cylinder, a second piston rod flush with one of the surfaces of said cylinder connected to said second piston, a second connecting rod connected to said second piston rod, a second crank connected to said second connecting rod included in the crank shaft mentioned, means for introducing and means for igniting a charge in the space defined by said cylinder and said pistons.

22. An engine according to claim 2l, in which the angle between said first and second cranks is between 23. An engine according to claim 21, in which the number of said piston rods is exactly two and in which the angle between said rst and second cranks is 1r.

RALPH H. BEARD.