US2844040A - Fluid displacement machine - Google Patents

Description

c. BANCROFT FLUID DISPLACEMENT MACHINE July 22, 1958 8 Sheets-Sheet 1 Filed May 25. 1953 mVzzvnm CHARLES BHNCROFT BY ATTORNEYQ July 22, 1958 c. BANCROFT 2,344,040

FLUID DISPLACEMENT MACHINE v Filed May 25. 195: s Sheets-Sheet 2 INVENTOR. CHARLES BeNcRoF-r ATTORNEYS July 22,1958 c. BANCROFI' 2,

rwznmsmcmuw momma: Filed May 25. 195: a Sheets-Sheet s' CHARLES BHNCROFT BY l ATTORNEYS IN V EN TOR.

y 22, 1958 c. BANCROFT 2 ,844,040

FLUID DISPLACEMENT MACHINE Fileii ma 25. 1953' v 8 Sheets-Sheet 4 IN VEN TOR.

CHARLES BHNCEOF'T HTTORNEYS July 22, 1958 c. BANCROFT 2,

FLUID- DISPLACEMENT MACHINE Filed May 25, 1953 8 Sheets-Sheet 5 INVENTOR. CHARLES BANCEOFT QTTOENEYS July 22, 1958 c. BANCROFTY 2,844,040

FLUID DISPLACEMENT MACHINE Filed May 25. 1953 s Sheets-Sheet s INVENTOR. CHARLES BFINCROFT BYW/ HTTORNEYS Filed May 25, 1953 8 Sheets-Sheet 7 FE INVENTOR. CHARLES Ba NC ROFT (QTTORNEYS July 22, 1958 c. BANCROFT 2,844,040

FLUID DISPLACEMENT MACHINE Filed May 25. 195: I i s Sheets-Sheet 8 IN V EN TOR.

CHARLES BHNCROFT ATTORNEYS United States Patent() 2,844,040 7 FLUID DISPLACEMENT MACHINE Charles Bancroft, New Canaan, Conn.

Application May 25, 1953, Serial No. 357,160

2 Claims. (Cl. 7452) This invention relates to a fluid displacement machine adapted for many uses.

One of the objects is to provide a machine design featuring improved mechanical balance, fewer parts, simplified construction, and greater compactness and lower cost, than are conventional. Another object is to provide a construction making possible a multi-cylinder, two cycle, internal combustion engine of improved volumetric efiiciency, which requires no valves, other than the pis-' tons themselves, for control of porting, and which does not require the partitioned crank-case ordinarily characteristic of prior art multi-cylinder two cycle designs. Still another object is to make possible a compact, vibrationless gas generator of relatively simple construction, or, alternately, an exceptionally compact, eight cylinder, four cycle engine, using relatively few moving parts, or an unusually compact, multi-cylinder, pump. Other objects will become apparent from the following.

The invention involves the use of reciprocatory pistons requiring a crank-shaft arrangement. In developing this arrangement advantage has been taken of the fact that when a second crank-shaft is rotatably mounted on the crank-pin of a crank-shaft of equal crank-throw radius, and is controlled in its rotation on that crank-pin so that it rotates at a speed, relative to the stationary main body of the unit, equal and opposite to that of the crankshaft on which it is mounted, its crank-pins reciprocate in straight lines intersecting the axis of rotation of the latter crank-shaft. When the pistons are rotatably mounted at their gravitational centers of these crank-pins, they can be confined within cylinders in which they will reciprocate through a stroke equal to twice the sum of the crank-throw radii of the two crank-shafts although all of the mechanical movements involved are purely rotary and can be balanced as such.

Since, when two crank-shafts are employed together as described above, the crank-pins of the second crank-shaft will move in straight lines intersecting the axis of the first or supporting crank-shaft; conversely, it follows that if two or more crank-pins of the second crank-shaft are forcibly restrained to such linear motion, as for example by pistons mounted on the crank-pins being confined within suitable cylinders, that crank-shaft will both be supported in its movement through the circle which it follows on the crank-pin of the first crank-shaft and will also be restrained to the opposite and equal rotation, while moving through that circle, which the circumstances require. Thus it follows that the pistons mounted on the crank-pins of the second crank-shaft act as supporting bearings for that crank-shaft and also control, or assist in controlling, that crank-shafts rotation on the crankpin of the first crank-shaft.

Specific examples of mechanisms and machines embodying the principles of the invention are illustrated by the accompanying drawings in which:

Fig. 1 is a perspective view showing an example of two sets of pistons provided with the type of crank organization described but constructed and arranged in accordance with the present invention;

Fig. 2. is a cross section showing the assembly of Fig. 1 in use in a machine which may be used as a two cylinder, two cycle gasoline engine;

Fig. 3 is a section taken substantially on the line 3-3 in Fig. 2;

Fig. 4 is a section taken substantially on the line 44 in Fig. 3;

Fig. 5 is a view similar to Fig. 2 excepting that it shows the principles of the invention applied to a machine adapted to function as a gas generator useful for operating turbines and the like; i 1

Fig. 6 is a section taken substantially on the line 6-6 in Fig. 5;

Fig. 7 is a view similar to Fig. 2 but showing a machine which may be used as a four cylinder, two cycle gasoline engine, this incorporating a modification of the arrangement shown by Fig. 1;

Fig. 8 is a section taken substantially on the line 88 in Fig. 7.

In the assembly shown by Fig. l, the described second crank-shaft is in the form of an intermediate crank-shaft having oppositely extending shafts 1, single-throw crankarms 2 and double-throw crank-arms 3, with crank-pins 4 extending between the arms 2 and 3, in each instance, and a crank-pin 5 extending between the arms 3, the latter being formed as a pair of spaced arms. The crank-arms are aligned with each other, the crank-pins 4 are eccentric to the shafts 1, and the crank-pin 5 is eccentric to the shafts 1 opposite to the crank-pins 4. The displacement of the crank-pins 4 and 5 relative to the shafts 1 are equal and opposite.

The shafts l oppositely extend through bearing holes 6 formed eccentri-cally in two shafts 7 of large diameters with the axial displacement of the shafts 1 relative to the axes of the shafts 7 being equal to the axial displacement of the crank-pins 4 or 5 relative to the crank-shaft 1. The shafts '7 are completely separate from each other and function as cranks mounting the crank-shaft previously described. This or an equivalent arrangement provides adequate room for proper bearings for the shafts 1 of the crank-shaft. The outer ends of the shafts 7 are reduced and cut-out to provide room for pinions 8 secured to the outer ends of each of the shafts 1. When these pinions 8 are engaged by stationary ring gears of proper diameter and axially concentric with the shafts 7, rotation of the shafts 7 in one direction results in opposite rotation of the intermediate crank-shaft under the control of the pinions 8, and therefore the crank-pins 4 and 5 move linearly in intersecting paths.

The pistons are made as two sets of oppositely facing pistons 99 and 14)10. The inner or back ends of the pistons 9 are rigidly interconnected by laterally spaced struts 11 which may be externally contoured as continuations of the cylindrical piston sides, whereby to in effect form a double-ended piston having a central slot. The struts may be centrally divided transversely and the parts clamped together by long screws 12 so as to form bearings journalling the struts 11 to the two crank-pins 4. The spacing between the struts 11 is sufficient for rotation of the arms 3. The inner ends of the pistons 10 are interconnected by a single strut 13 in a rigid manner, and this strut 13 may also be centrally split transversely with the parts held together by screws so as to form a bearing journalling the strut 13 to the crank-pin 5, or, as shown by the drawings, the strut may be solid and the crank-pin 5 made as separate parts projecting from the crank-arms 3 and bolted together in the manner common to radial engine crank-pins.

When the pistons are arranged in right angularly related cylinders the pistons and their interconnecting struts are firmly guided to follow the reciprocating paths of the respective crank-pins, whereby the intermediate crankshaft is supported rotatively. By making the two halves of each piston set so that the crank-pin journal bearings are at the center of gravity of the piston set, in each instance, it becomes possible to balance the moving parts as purely rotary parts even though the pistons reciprocate. The forces involved are purely rotary in efiect. This effect is obtained when single pistons are journaled to each crank-pin, instead of the sets, when there is enough overhanging weight to make the center of gravity of each piston coincide with its crank-pin, and the piston is adequately guided linearly.

Referring now to Figs. 2 through 4, the pistons are shown reciprocatively positioned in a set of opposed cylinders and 16, and the pistons 9 reciprocatively positioned in a set of opposed cylinders 17 and 13. Each set of cylinders is radially arranged at right angles to each other. The cylinders are mounted by a crankcase 19 which completely encloses the crank-shaft assembly and is provided with axial holes in which the respective shafts 7 are journaled in bearings 20. The crank-case 19 outwardly extends axially from the radial walls in which the shafts 7 are journaled. End plates 21 are secured to the ends of the crankcase extensions 19a and these end plates immovably mount the previously described ring gears, shown at 22, with which the pinions 8 are constantly meshed as the pinions revolve due to rotation of the shafts 7. The shafts 7 are continued outwardly with reduced portions 23 forming journals mounted by bearings 24 in the end plates 21, the latter having holes 25 through which the outermost ends of the shafts 7 extend as at 26.

Due to the fact that the pinions 8 force the crank shaft 1 to rotate on its axis in the same fashion at both ends, the individually separate shafts 7 are rotatively locked together so that they function as a single shaft in which the crank-shaft 1 is eccentrically journalled. Neither of the shafts 7 can rotate independently of the other, the effect being that of a single crank-shaft formed as two rotatively interconnected halves. It is to be noted that the shaft 7 function as cranks having their outer ends journalling the crank-shaft 1 and revolving about axes common to the axes of the shafts 7.

The cylinders 15 and 16 have their outer ends closed and provided with threaded holes 27 in which spark plugs may be screwed to fully enclose these ends. The

outer ends of the cylinder 17 and 18 are completely closed by cylinder heads 28 in each instance.

The crank-case19is made with its previously described radial walls, which mount the bearings 20, in the form of hollow walls. space inside of these hollow walls, the spaces 30 being interconnected as to both crank-case bearing-mounting end walls. The crank-shaft arrangement is such that the pistons 9 diifer in angular phase from the pistons 16 during the operation of the machine. In the illustrated form the phase difference is 90 and, therefore, when one piston set is stationary at either of its reciprocating extremes, the other piston as at its mid-position and moving at its maximum velocity.

In Figs. 2 through 4 the cylinders 15 and 16 and the pistons 10 funtion as a two-cycle internal combustion engine, and the cylinders 17 and 18 and pistons 9 function as a scavenging blower for this engine. Passages from the cylinders 17 and 18 feed into the inner ends of the cylinders 15 and 16 where they are alternately either connected by slots in the pistons 10 with the intake manifold space 30 or, when the pistons are out of the way, directly with the crank-case. Thus the pistons 10 control the intake and output of what is in effect a scavenging blower formed by the cylinders 17 and 18 and the pistons 9. Since the pistons 10 are moving at their maximum velocities when the blower is shifted from input to out put, the valve action is rapid, which is advantageous.

A fluid intake passage 29 leads to the The blower output is thus fed into the crank-case from which it discharges into the cylinders 15 or 16 through passages opening into these cylinders and uncovered by the pistons when at their inner limits, whereby to both scavenge and charge these cylinders. Suitable exhaust ports are uncovered by the pistons at this time, as is usual. Additional intake passages for the scavenging blower cylinders 17 and 13 may be arranged to open from the intake manifold so that they are uncovered when the pistons 9 are at their inner limits. In such instances as when the valving action is at the end of a passage connecting with the cylinder, the volume of the passage is added to that above the piston during the compression phase, and the features of the present invention permit such passage to be made very short with a consequent ability to effect adequate volumetric efiiciency.

With the foregoing in mind, the intake manifold space 30 connects with the portion of the cylinder 16 that is inner respecting the center of the engine, through ports 31, and with the inner portion of the cylinder 15, respecting the engine center, through ports 32. Both of the pistons 10 are provided in their side walls with longitudinally extending grooves 33 which register with the ports 31 and 32 as either piston approaches and is adjacent to its innermost limit, or in other words, throughout the inner half of its piston stroke.

The cylinder 16 has ports 34 spaced inwardly from the port 31 and with which the latter is connected by the grooves 33 when the latter register with the ports 31. These ports 34 connect with a passage 35 leading into the outer end of the cylinder 17, as shown by Fig. 2. The cylinder 15 has comparable ports 36 connecting with a passage 37 leading into the outer end of the cylinder 18. An exhaust port 38 is located in the cylinder 16 so as to be uncovered by the piston when the piston approaches and is adjacent to its innermost position, this port 38 connecting with an, exhaust passage 39. The cylinder 1.5 has a comparable exhaust port 40 connecting with an exhaust passage 41.

The ports 34 and 36 and their respective passages 35 and 37 are in part shown in broken lines in Fig. 2 only so as to indicate their locations. As shown in Fig. 3 there are three of these ports in each instance and the outer two are diametrically located for registration by the piston grooves. The passages 35 and 37, as the case maybe, extend as a semi-circle portion from the outer two ports, around behind the respective cylinder walls, and thus to the straight portions leading to the cylinders 17 or 18 in each instance. Referring to Fig. 3, the semi-circle portion of the passage 35 is in a plane above that of the drawing, as is indicated in Fig. 2 which also shows that the semi-circle portion of the passage 37 is below the plane of the drawing so it can be indicated by the broken lines in Fig. 3. In each instance, the center one of the ports 34 or 36 are in effect auxiliary ports which function when the charge is blown into the crank-case as subsequently described.

The crank-case interior connects with the cylinder 16 through a passage 42 and a port 43 located through the cylinder wall diametrically opposite to the exhaust port 39. The crank-case, in a similar manner, connects with the cylinder 15 through a passage 44 and a port 45. Preferably, the cylinders 17 and 18 have auxiliary ports 45a connecting with the intake manifold space 30 and located in each instance so as to be uncovered by the piston as the latter approaches and is at its innermost limit.

In operation the intake passage 29 is connected with a carburetor or the like for supplying a suitable corn.- bustible mixture, and, of course, spark plugs will be located in the holes 27 and energized by a suitably timed sparking voltage. 'Upon proper rotation of the shafts 7 the charge is sucked through the intake manifold 30, which would be by the left-hand piston 9 asthe operation is shown by Fig. 2, through the ports 31 and 34, by way of the registering piston grooves 33 of the piston in the cylinder 16, and thus into the cylinder 17 from the head ofwhich the pistons 9 are retreating. As the operation continues the pistons 9 reverse so as to compress the charge. In the drawings this compression is underway in the cylinder 18, which was previously sucked full of the charge. The compressed charge is driven through the passage 37 and into the crank-case, the piston in thecylinder being now clear of the ports 36. The compressed charge in the crank-case drives in through the passage 42 and port 43 into the cylinder 16.

Thus in succession the charge is appropriately introduced to. the cylinders so as to scavenge them free from burnt gases and provide them with fresh charges. As the appropriate one of the pistons 10 advances it cuts off all of the ports ahead of its working face and goes into its compression phase ready for firing. After firing, the exhaust is, of course, through the ports 38 and 40 or the exhaust passages 39- and 41, as the case may be.

It can now be seen that in a single compact unit the set of pistons 9 provide the previously described scavenging blower with its valve action controlled bythe working pistons so as to eliminate valves as such. The crankcase is used as part ofthe fiuid transfer system but it is not required to operate alternately under sub-atmospheric and super-atmospheric pressure, so there is no need for separating webs or diaphragms in the crank-case for any reason. The spaces between the radial crankcase-walls and the end plates 21 provide gear cases for the 'pinions 8 and ring gears 22 and may be flooded with lubricant as desired. The crank-shaft 1 and pinions 8 are balanced by counterbalances 46, and the gear box space also provides room in which these counterbalances may move. Referring now to the gas generator, shown by Figs. 5 and 6, the same fundamental parts and principles are usedas have been described in connection with the example shown by Figs. 2 through 4. Therefore, wherever possible the same numerals are used to identify corresponding parts and where these parts are modified the same numerals are used in conjunction with a letter.

In this gas generator the piston 10 in the cylinders 15.

and 16 function to power the pistons 9a in the cylinders 17a;and 18a, the pistons 91: and the last-named cylinders being of much larger diameter than are shown in connection with the first example for the corresponding scavenging blower parts. Another difference is that the intake system is modified by the provision of intake passages 29a directly in the heads of each of the cylinders 17a and 18a, respectively, these intake passages being provided with poppet check valves 47.

. As to the operation of this second example, the lefthand pliston 9a is shown moving to the right and sucking air in through the passage 29a, the poppet check valve 47 being sucked open to permit this. The righthand one of the pistons 9a is on its compression stroke and is forcing a large volume of air, previously sucked in as described, through the passage 37 and port 36 into the crank-case. The upper one of the pistons 10 has cleared the port 36 at this time, the piston having formerly blocked this port in the manner the lower one of the pistons 10 is shown doing in the case of the port 34, as required to close the passage 35 during the suction stroke. From thecrank-case the air drives up through the passage 42 and out of the port 43 so as to L scavenge and cool the cylinder'16 and from therethrough the exhaust port 41 mixed with the hot products of previous combustion, a residue of air being left in the-cylinderto charge it for the next compression. In this case the passage 42 surrounds all of the cylinders so as to be heated thereby and to cool the cylinders by the air moving through the passage 42.

The upper one of the pistons 10 is at the limit of its compression stroke. Because there is an excess of air involved this example shows the use of solid fuel injection nozzles 48 so that the machine operates in the 6 manner of a diesel. Asuitable fuel injection control must, of course, be provided.

This second example is particularly adapted to produce a large volume of highly compressed gas which may be used, by connections to the exhaust ports 41, for powering a turbine or the like. The pistons 9a work as pumps compressing large volumes of air into the passage 42 surrounding the cylinders and thus into the power cylintders above the pistons 10 where the air is heated by the combustion,. as to the portionof the air retained by the cylinders, so as to obtain a relatively high temperature beforebeing mixed with 'fresh scavenging air and discharged through the exhaust ports. The principles of the present invention provide for a compact and smooth operating unit capable of being controlled easily and which produces a large volume of hot compresed gas.

The four cylinder, two cycle, gasoline engine illustrated by Figs. 7 and 8 involves a modification of the crank-shaft and piston assemblies shown by Fig. 1.

In this modification the intermediate crank-shaft involves the use of two eccentrics 3a and 3b, instead of the crank-arms 3 of the first example. All of the power pistons 10a, of which there are four, are organized in the form of sets of two pistons each with the vertical ones interconnected by a rigid piston rod 13a journaled on the eccentric 3a and the horizontal ones interconnected by a rigid piston rod 13b journaled on the eccentric 3b. This arrangement provides a' four cylinder radial engine requiring somemeans for scavenging and recharging the cylinders above the pistons. This is provided for as described below.

A vertical scavenging blower piston set 9a reciprocates with its piston heads respectively in the cylinders 15 and 16, the pistons being apertured so as to permit the sliding passage of the rod 13. This piston set 9a has the inner ends of its respective pistons interjoined by a strut 11a having a central cross head 49 in which a block 50 transversely reciprocates. This block 50 is journaled on an eccentric 51 fixed to the inner end of the left-hand one of the shafts 7 as viewed in Fig. 8. The horizontal set of the scavenging blower pistons 9b are interconnected by a strut 11b provided with a similar cross head 4% in which a block 50a reciprocates and is journaled on an eccentric 51a fixed on the inner end of the righthand one of the shafts 7. Horizontal pistons 9b are also apertured to slidingly pass the piston rod 13b. The crank-case 19a is made in rectangular fashion so that it may be internally provided with suitable guiding surfaces for supporting the two cross heads in their relatively right angular motions and in line with their respective piston sets.

The described assembly is timed so that the power piston sets 10aare out of phase with each other and so that the scavenging blower pistons 9a each lags in phase behind its associated power piston by 90. Furthermore, the eccentrics 51 and 51a are contoured so that in each instance the stroke of the blower piston is shorter than the power piston stroke.

'Each cylinder and its two pistons functions the same as the other 'so the following description is applicable to all. In each instance each cylinder has an intake port 52 opening into its inner end so as to be cleared by the porting piston 9a or 9b when the latter approaches and is at the limit of its innermost stroke limit. As shown in the right-hand one of the horizontal cylinders in Fig. 7, this results in sucking a charge, as from a carburetor, into the space formed between the two pistons 9b and 10b. As the action continues the piston 9b advances, as shown in the case of the cylinder 17, while the piston 10b is moving inwardly. Each cylinder has a transfer passage 53 opening into the cylinder through an inner port 54 and an outer port 55 respectively located so that one or the other is. closed by the adjacent piston 9b when the latter is at either of its stroke limits or adjacent thereto, but so as to span-the piston 9b'when' the latter is 7 at an intermediate position. Therefore, as the pistons 9b and 10b move, so as to diminish the space between them, as shown on the left-hand side of Fig. 7", the compressed charge is transferred to the crankcase.

In Fig. 7 the upper ones of the pistons 9a and 10a: are shown nearly at their closest positions, respecting each other, and at this time a transfer passage 56 is opened because it has an inlet port 57 positioned to be cleared by the piston 9a at this time, and an outlet port 58 cleared by the pistons 10a, whereby the charge is transferred from the crank-case to above the power piston so as to scavenge the cylinder thereabove and recharge it ready for compression and firing. The exhaust action after firing is readily apparent.

In all of the foregoing examples it is to be understood that those skilled in the art can effect the necessary timing as to the ignition means in the case of the gasoline type and the fuel injection in the case of the diesel type. The three examples serve to illustrate how the assembly of Fig. 1 permits the designing of unusually compact fluid displacement machines which may be balanced as though comprising only rotary parts. The invention further provides for the scavenging blowers with their necessary valve action provided by the power pistons with the resulting valve action rapidly inaugurated and terminated, due to the oscillatory motion imparted each piston and the timing already explained. i

It is to be understood that all of the piston sets are centrally journaled to the crank-arms, whether provided by arms as such or by eccentrics, at the centerof gravity of the piston set in each instance. Furthermore, the pistons and their interconnecting members, as to each set, are rigidly guided linearly by the cylinders in which the pistons reciprocate, whereby to rotationally support they intermediate crank-shaft in all instances, due to. there being a plurmity intersecting lines or paths through which the crank-pins or their equivalent reciprocate and which represent truly rotary motions. With proper rotary balancing smooth operation results. It is to beunderstood that by interconnecting the two spaced shafts as described, the rigid guiding by the cylinders is not absolutely necessary.

It is to be noted that where the valving of one cylinder is controlled by the piston of another cylinder, onset radially substantially 90, as shown by the drawings, the mid-point in time of any valving condition in the controlled cylinder occurs when the controlling piston is at the top or bottom of its stroke, and, therefore, if the valve timing is changed at one end of the stroke of the piston in the controlled cylinder, there should be a corresponding change in the valve timing at the other end of the stroke since the mid-point duration of port opening or closing must always correspond to the top or bottom of the stroke of the controlling piston.

If then, as may be true in the case of the piston gas generator shown by the drawings, it is preferable to have the pumping cylinders connection to the output manifold (in this case the crank-case area) delayed during the output stroke of the pumping pistons until the pressure in tnese cylinders reach that already existing in the crankcase section, forming the output manifold, and to have this connection broken, as before, at the end of each output piston stroke, it can be seen that the mid-point of duration of such a port opening would not coincide with the top or bottom of the stroke of the controlling piston.

- However,- by changing the radial angular relationship. of

the controlled cylinder to that of the cylinder in which the controlling piston works, the top or bottom of the stroke can be made to coincide with the mid-point of the port opening duration as. required; It is expressly understood that such variations in the radial angular relationship of the various sets of pistons can. be introduced for such purposes or other purposes, without effecting the basic principles of this invention, as described here, or their advantages, such as the balancing advantages, etc;

It is also to be understood that while the invention is illustrated by examples having the crank-case section acting as a connecting manifold between the scavenging pumps and the control cylinders, other examples can be constructed to have the crank-case section acting as a preliminary intake manifold or eliminated entirely from any function in connection with the passage of working fluids through the unit. Also, although all the drawings included herewith relate to four cylinder units, or an equivalent construction, any number of crank-pins and sets of pistons can be employed to provide any number of working cylinders in a single row or multi-row construction or to provide single cylinder, in line, or V-type units.

To simplify the description, reference hasbeen made herein to single ports in instances where the drawings show a multiplicity of openings, to etfect loopscavenging forexample. It is to be understood, therefore, that herein a reference to a port is to be construed as meaning a single opening or a group of interconnected openings.

I claim:

1. A fluid displacement machine including a plurality of sets of opposed cylinders arranged radially about an axis, a piston in each of the cylinders, struts laterally spaced axially respecting said axis and interjoining the pistons in one of the cylinder sets, a strut positioned between the spaeed struts and interjoining the pistons inanotherof the cylinder sets, cranks journaled to rotate onsaid axis and positioned on opposite sides of the spaced struts and having arms revolving about said axis, and a crank-shaft journaled by and between the cranks arms and having crank-arms on the outside of the spaced struts with crank-pins'extending therefrom and journaled to and extending through the struts and double crank-arms between the struts and which are joined by a crank-pin journaled to and extending through the strut positionedbetween the spaced struts.

2-. A fluid displacement machine including a plurality. of sets of opposed cylinders arranged radially about anaxis, a piston in each of the cylinders, struts laterally spaced axially respecting said axis and interjoining the pistons in one of'the cylinder sets, a strut positioned between the spaced struts and interjoining the pistons inanother of the cylinder sets, cranks journaled to'rotate onsaid axis and positioned on opposite sides of the spaced struts and having arms revolving about said axis, andacr-ank-shaft journaled by and between the cranks arms and having crank-arms on the outside of the spaced strutswith' crank-pinsv extending therefrom and journaled to and extending through the struts and double crank-arms be-- tween the struts and which are joined by a crank-pin journaled to and extending through the strut positioned between the spaced struts, the cranks and crank-arms hav-- ing equal effective lengths, and means for causing the cranks to rotate synchronously together and for causing opposite rotation of the crank-shaft, whereby the crankpins move through intersecting linear paths while supported rotatively by the pistons and struts.

References Cited in. the file of this patent UNITED STATES PATENTS 1,056,746 Pitts Mar. 18, 1913 1,585,453, Williamson May 18; 1926, 1,761,429. Dean June 3, 1930 1,774,105 Nelder "Aug. 26, 193.0 1,787,599 Stickney Jan. 6,. 1931 2,088,863 McClelland' Aug. 3, 1,937 2,132,595 Bancroft Oct. 11, 1938 2,199,625; Fiala-Fernbrugg n, May, 7, 1940; 2,223,100 Foster Nov. 26, 194.0,

FOREIGN PATENTS 341,010 Great Britain July 4, 1929 884,403; France Apr. 27, 1943.

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