US2678028A - Expansion engine - Google Patents

Description

May 11, 1954 w, w, PAGET 2,678,028

' EXPANSION ENGINE Filed June 4, 1948 3 Sheets-Sheet l May 11, 1954 w. w. PAGET 2,673,028

EXPANSION ENGINE Filed June 4. 1948 5 Sheets-Sheet 2 27 V I B venior: Zdin Z1]. Puget.

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EXPANSION ENGINE Filed June 4, 1948 3 Sheets-Sheet 3 4 2 v t A; 10 //0 I213 9 1h ventor:

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Patented May 11, 1954 UNITED STATES PATENT OFFICE 2,678,028 EXPANSIONENGINE -Win W. Paget, Michigan City, 11111., assignor to Joy Manufacturing Company, Pittsburgh, Pa., a corporation QfLPBHHSYl-Vflllifl,

Application June 4, 1948, Serial N0. 31,017

12 Claims. 1

This invention relates to expansion engines,

that is to engines employed for thepurpose of removing energy from a fluid under pressure and thereby reducing the temperature thereof. Such engines are particularly useful in connection with oxygen producing apparatus, but they are also useful with refrigerating machines and other apparatus where it is desired to change the condition of a fluid under pressure by expending some of'its energy through the doing of work in an expansion engine.

The principal objects of the invention are to provide an improvedexpansion engine which is designed in such a manner as to insure a smooth and efficient operation at low temperatures, for example, temperatures at and below those of liquid air; and which embodies improved means for changing the point of cutoit thereof-whereby the same may be used, for example inoxygen producing apparatus, in the production of oxygen at a relatively low pressure, as-on the order of 50 pounds gauge, or at a relatively higher pressure as, for example, 2000 pounds per square inch,

for cylinder charging. A further and more particular object is to provide an expansion engine having an improved adjustable cutoff mechanism which may be fluid actuatedto effect a change from operation with relatively early outoii to operation with-cutofi at a point much later Further objects of the invention and advantages thereof will appear in the course -of the following description.

it a plurality of cam following rollers, one or more of which may be had in operative relation with an associated cam for providing for different points of cutoff.

Referring to the accompanying drawings, wherein I have shown what is-now considered a preferred embodiment of the invention,

Fig. 1 is a side elevational view of an illustrative embodiment of my improved expansionengine, parts being broken away to show. details of drive.

Fig. 2 is a vertical section through'the'low'er .end of the expansion engine, the section being taken on the planes of the line 2-2 .of Fig. 1, but enlarged.

Figs. 3 and 3A together provide a vertical axial section through the upper end of the expansion engine, the sectionbeing taken on the plane of the line 3-3 of Fig. l, but enlarged.

Fig. 4 is a vertical section on the planes of the line 44 of Fig. 2, showing details of construction, and-being on a smaller scale.

Fig.5 is a detail section on the planes of the section line 5-5 of Fig. 2, and on a smaller scale. Fig. 6 is a detail section on the planes of the line 6-6 of Fig. 2, and on a smaller scale.

Figs. 7 and 8 are further detail sections, respectively on the planes of the lines 5-5 and 6-6,

showing parts in different operating positions. Fig. 9 is a detail sectional view showing the construction of the pressure fluid operated device for effecting a change in the point of cutoff. Fig. 10 is a detail sectional view, with parts broken away, and on the plane of Fig. 5, showing a cam control detail, but on a scale larger than that 01' Fig. 5.

Fig. llis a detail sectional view on the plane of Fig. 5, showing parts in different relations to each other.

The expansion engine E, as shown in Fig. 1,

comprises a sectionl constituting a cylinder; a

section 2, which comprises the admission and exhaust valve assembly; a section 3, providing space for thermal insulation, and in which the greater part of the-valve assembly is enclosed; a section 4, in which are packing means; and a section 5,

which constitutes a crankcase and which houses "a crosshead or slide to which motion is transmitted from a crankshaft and which transmits -motion to the piston as hereinafter described, and which crankcase also houses improved mechanism for actuating the admission and exhaust valves.

One end of the cylinder section I (see Fig. 3)

is provided with a head H having a breather passage 12. The top of the head H supports a liquid. oxygen pump 13 comprising a cylinder 14 jacketed at [5 and containing a piston l6 adapted to be moved upon its, suction strokes by a spring I1, and to be engaged and-forced upon its pumpingstrokes by a surface l8 on piston l9 of-the'expansion engine, which last piston is reciprocable'in the bore 20 of the cylinder I. The head 2| of the liquid oxygen pump cylinder contains suitable admission and discharge valves, 22

:and 23-respectively, and means for moving the piston l6 ofthe liquid oxygen pump to a position 'in whichit will not beengaged andactuated' by the piston I9'isprovidedas at 24.

"The piston I!) has a head 25 and an elongated skirt portion 26. The portion of the expansion engine cylinder below the head constitutes the bottom of a working chamber, or a clearance, into which fluid is admitted to do work on the piston during its upward stroke; and from the working chamber fluid is discharged during the downward strokes of the piston I9. The piston and cylinder are desirably formed from the same wear-resistant metal, the alloy sold under the trade name Nitralloy having been found to give superior results when hardened, ground and polished so that the diametrical clearance between the piston and cylinder is between .0003 inch and .0010 inch for a piston having a diameter of two inches. The periphery of the piston may be grooved, if desired, to minimize leakage and to promote centering of the piston in the cylinder.

The head of the piston I9 is formed with a central recess 28 which receives with clearance the flanged head 29 of a flexible piston-rod 30, and a member 3|, held in position by screws 32, has an opening 33, through which the piston rod 30 extends; and the member 3| anchors the flanged end of the connecting or piston rod to p the piston. Thus the necessary freedom for slight angular and slight bodily relative movements, to prevent lateral stresses, is secured. The piston rod will be observed shortly to transmit tension or pull, but not thrust.

The valve assembly 2 has a circular plate portion fitting against the lower end of the cylinder I and formed with an admission port 36 and an exhaust port 31 and a central opening 38 through which the piston rod 30 reciprocates. The plate portion 35 is a part of an admission and exhaust chamber providing casing 39. Beneath the casing 39 is a valve spring housing 40, which may be an aluminum casting and include a pair of depending socket-like casings 4| and 42 registering with the ports 36 and 31. The casing 39 is provided with admission and exhaust chambers 43 and 44, for connection with supply and discharge lines not shown, and admission and exhaust valves 45 and 46 are reciprocable in their respective chambers, and each is movable downwardly against the action of a suitable spring (41 associated with the valve 45 and 48 associated with the valve 46) by improved actuating and controlling means shortly to be described. The lower ends of the casings M and 42 are provided with guide bushings 49 and 50 within which there are guided flexible pull rods 5I and 52, which are suitably connected at their upper ends to the valves 45 and 46. The I guide bushings 49 and 50, and a corresponding guide bushing 53 for the piston rod, each have projecting bosses to which tubular casings 54, 55 and 56 are soldered. The guide bushing 53 also has an opposite projection secured in a bore 51 in the valve spring housing 40. Within the bore 51 there are suitable guide bushings 58, surrounding the piston rod, and other bushings 59, 60 and 6| surround the valve and piston rods and are spring held, as at 63 in position.

Within the section 4 extend glands 6-4, 65 and 66 associated with the valve and piston rods, and glands 51, 68 and 69 associated with the casings 54, 55 and 56.

The valve rods are connected to guided end members H and 12 adapted to be pulled, to open the valves, by the end portions 13 and 14 of bell crank levers 15 and 16, later more fully described.

The crankcase section 5 of the expansion engine includes a crankcase portion 80 providing a support 8I for one bearing 82 of a crankshaft 83, a head portion 84 supporting another crankshaft bearing 85, and a gear casing portion 86, housing spur driving gearing 81 and secured as shown to the crankcase 88 of a compressor 89 which supplies compressed air to the oxygen generator of which the expansion engine forms a part. The spur gearing may desirably include a driven pinion 90 suitably secured to the crankshaft (or an extension of the crankshaft) of the compressor.

The crankshaft 83 is rotatably supported by the bearings 82 and 85, and has a crankpin 94 connected by a connecting rod 95 with a tubular crosshead 96 having heads 91 and 98 connected by a trough-like portion 99 and guided respectively in cylindrical guideways I00 and IN. The lower head 98 is constructed similarly to a trunk piston and may be considered to be a piston, and carries a wrist pin I02 to which the lower end of the connecting rod 95 is pivotally connected. A breather conduit B extends from beneath the piston 98 to a point in the crankcase above the uppermost position of the piston 98. The upper head 91 has a central boss I03 in which there is rigidly fixed a reduced lower end portion I04 of a connecting element I05 fixed to the lower end of the piston rod 30. The head 91 is traversed by openings I06, I01 in which the lower ends of members H and 12 and their guides I08 and I09 may extend in the various positions of the crosshead 96. The axis of rotation of the crankshaft 83 will be noted to be laterally offset from theline of reciprocation of the axis of the piston rod 30.

Bell crank levers 15 and 16 are mentioned above. The bell crank lever 15 controls admission and cutofi; the bell crank lever 16, release and compression. The bell crank lever 16 and the bell crank lever 15 are both journaled on sleeve bearings I In on a fixed cross shaft I II extending through the upper portion of the crankcase section 5. Bell crank lever 16 has an arm II2 substantially at right angles to another arm H3 on which the end portion 14 is carried. A cam I I4 is fixed to the crankshaft 83 and has a surface H5 adapted to cooperate with a roller H6 rotatably mounted on the lower end of the arm II2. A spring I I1 acts between the arm H2 and an abutment II8 on another cover plate I I9 on the crankcase section 5, and maintains the roller in engagement with the cam I I 4, and when the roller actuating surface H5 is not in contact with the roller I I 6, the spring II1 moves the end 14 of the bell crank 16 upwardly and allows the spring 48 to close the exhaust valve.

As above noted, the bell crank 15 which controls the movements of the admission valve 45 is supported for oscillation on the shaft I I I. This structure is somewhat more complex than that of the bell crank 18, and it has not only an arm I23 similar to the arm II 3, and also an arm I 24 which carries a roller I26 rotatably mounted thereon; but the arm I24 has an outwardly projecting boss I21 which pivotally supports at I28 another bell crank lever I29 including an upwardly extending arm I 30 and a downwardly inclined arm I3I. The arm I3I carries at its free end a rotatable cam follower roller I 32 whose position with respect to the axis of the crankshaft can be controlled by an adjustable stop screw I33 extending through the arm I3I and engageable with a surface I34 on the boss I21, and by cylinder and piston mechanism I40 which includes a cylinder I 4| carried by the vertical arm I30 and having a bore I42 in which a piston M3 is received, thispiston *haVingastem or r'boss I'M adapted to engage a surface 145 stationary with the arm 124 of the bell crank 15; and -upon the admission of fluid to the bore M2 through a conduit M6, the cylinder member! "is adapted to be movedawayfrom the upper end: of .the arm I24 and thus toswing-the second bellvcrank relative to the'bell crank '65 and move therarm l3! counterclockwise in Figs. 4, 5, 7, :llilv and .111 until "the end of the adjustable screw 133 engages the surface I34.

Fig. 11 shows thatatthis time 'the:.ro11er 132 will be positioned for engagement by a cam DOT- tion [48 of a cam member Mil-carried by the crankshaft 83 and controlling admission andtcutoff. It will be observed that thespa'cing-of the cam rollers IZS-and [3'2 and thelength of the cam projection l 4'8are sush that with theparticular proportions'oi' this apparatus, cutoff ismade approximately twice as-late in the stroke'when the roller I32 is moved into cooperative relation with the cam. A spring I50 acts againstasurface [5! on the bell crank 129, and another surface I52 on the cover H9. This spring normally maintains the bell crank in such a position that the valve 35 may be seatedexcept whenthe cam portion I48 is cooperatingwith one of "the rollers I26 or I32.

Fig. '5 shows the-position of the-parts just as admission is about to take place, noting thatthe direction of rotation of the crankshaft is counterclockwise in this figure.

Admission is taking place with the parts in the position shownin Fig. 7. With the parts in thisposition it will'be evident that the period ofadmission is about onehalf completed. In the position of the parts shown in Fig. 11,'it will beobservedthat admission has been taking place nearly one andonehalftimes as long as the full period of admission when the roller 132 is=not cooperating with'the cam.

It will be apparent that notwithstanding the fact that the expansion engine will .be covered thoroughly with insulation in use,'there is provided means whereby the cutoff of the engine may be very easily and quickly'altered .merely 'by supplying fluid to and venting fluidfrom :the

conduit M6, which will desirably be a flexible conduit, at least between its'pointof ingress to the interior of the crankcase and its point .of connectionto the movable bell crank mechanism.

It will'be evident that the construction issimple,

that the same spring positions the main bell crank and the auxiliary bell crankwhenrthese are not being engaged and actuated by thecam, that the parts are simple and effective'and-positive in operation, that by reason of the construction of the crosshead and its guides there will beno'possible lateral fiexureof the'flexible piston rod, and that all of the parts of thereciprocating system may be made quite light. Other objects and advantages of the inventionwill b'e 'clearly apparent'to those skilled in the art.

While there is in this application specifically described one form which the invention may assume in practice, it'will be understood that this form of the-same isshown for purposes-of illustration and that the invention may bemodified and embodied in various other'forms' without departingfrom its spiritor-the scope of the .ap-

pended claims.

What I claim as new and desire tosecure by Letters'Patent is:

'1. In combination, in an expans1on= =engine, a cylinder, apiston reciprocableiwithinlsaidrcylindeiga crankcase, means for supportingsaid cylinder on said crankcase, a crankshaft in said .crankcase,-a crosshead guided in said crankcase for reciprocation along a path extending in the same direction as the path of reciprocation of said pistonand having an end nearer said cylinder and an end remote from saidcylinder, and

said crankshaft having its axis of rotation between the ends of the path of reciprocation of said crosshead, a connection between said crosshead, atthe end 'ofthe latter nearer said cylinder,with said piston, and a connection between said crankshaft and said crosshead at the end of -the latter remote from said cylinder, saidcylinder having distributing valve devices associated therewith having stems extending through the end of the crosshead nearer said cylinder, and valve operating means actuated by said'crankshaft andextending transversely of said .crosshead and between the ends of the latter into cooperative relation with said valve stems.

.2. In combination,.in an expansion engine, .a cylinder, apiston reciprocable within said cylinder, a crankcase, means for supporting said cylinder-on said crankcase, a crankshaft in said crankcase, a generally cylindrical crosshead guided in said crankcase for reciprocation along a path extending in the same direction as the path of reciprocation of said piston and having an end nearer said cylinder and an end remote ing levers pivoted on said crankcase and extending through said opening into cooperative relation with said valve stems.

"3. In combination, in an-expansion engine, a

"cylinder, a piston "reciprocable within-said cylinder, a crankcase, means for supporting said cylinder on said crankcase, a crankshaft in said "crankcase, a crosshead guided in said crankcase for reciprocation along a path extending in the "same direction as the path of reciprocation of said piston, said crosshead elongated in the direction'in which its path extends-and having one end between said cylinder and said crankshaft and its otherend at the opposite side of said crankshaft from said cylinder, a connection-between said crosshead, at the end of the latter nearer said cylinder, with'said piston, and a connection-between said crankshaft and said crosshead at the end of the latter more remote from said cylinder, said cylinder having distributing valve devices associated therewith having stems extending through the end of the crosshead nearer said cylinder, and valve operating means including bell cranks pivoted on axes adjacent the cylinder-supporting end of said crankcase and having arms extending laterally of said cross- "head, between the ends of the latter, into cooperativerelation with. said stems and further having arms extending towards said crankshaft, andsaid crankshaft having cams thereon cooperating with said arms.

:4. For'actuating and controlling the fluid admission and cut-off valve of an expansion engine having a crankshaft and a valve pulled from its seat to effect admission and oppositely moving to effect cut-01f, a valve operating rod traction on which effects valve opening, and means actuated by said crankshaft for pulling said valve actuating rod in a valve Opening direction including a cam moving with the crankshaft and two cam follower rolls each cooperatively engageable with said cam, said two cam follower rolls having means for supporting them for turning on relatively laterally ofiset axes, one of which is movable relative to the other to move the cam follower roll that rotates thereon selectively into positions in one of which it is maintained out of engageability by said cam as the latter moves with the crank shaft.

5. For actuating and controlling the fluid admission and cut-off valve of an expansion engine having a crankshaft and a valve to eifect admission and cut-off, a valve operating rod traction on which effects valve opening, and means actuated by said crankshaft for pulling said valve operating rod in a valve opening direction including a cam actuated by the crankshaft and two cam follower rolls for said valve, and means for rendering one or both of said cam follower rolls effective in the control of said valve including means for moving one of said rolls relative to the other and to said cam to position it for engagement by the latter or in another position in which it is out of the range of cam movement.

6. In combination, in an expansion engine l1aving a valve controlling admission and cutofi and a rotating shaft, means for controlling the movements of said valve incluuding a cam rotating with said shaft, a roller actuated by said cam whenever said expansion engine is running and adapted to effect opening of said valve device and to control the closing thereof to eiiect cutoff at a predetermined point in the working stroke of the expansion engine, another roller mounted for movement with respect to the first roller into and out of cam-engaging position, and means for selectively bringing it into engagement with said cam to extend the period of admission and out of cam engagement to leave control of the period of admission to the first roller.

7. In combination, in an expansion engine having a valve controlling admission and cutoff and a rotating shaft, means for controlling the movements of said valve including a cam rotating with said shaft, a roller actuated by said cam whenever said expansion engine is running and adapted to effect opening of said valve and to control the closing thereof to effect cutoff at a predetermined point in the working stroke of the expansion engine, another roller movably mounted with respect to the first roller and having its axis of revolution offset from the axis of revolution of said first roller and supported for movement into and out of cam-engaging position, and means for selectively bringing said second roller into operative relation with said cam, to extend the period of admission, and moving it to a position in which it is out of the path of said cam, said second roller positionable with respect to the first roller, in cam engaging position, with its center at substantially the same distance from the center of said first roller as the effective length of the cam.

8. In an expansion engine, in combination, a valve for controlling admission and cut-off, and means for controlling the movements of said valve to provide different predetermined periods 8 A of admission including a cam and a lever having a portion movable to eifect valve opening and having a pivot and having a portion carrying a roller engageable with the cam, a second lever pivotally supported on the first lever and carrying another roller movable relative to the first roller between positions in which it is uncontacted by said cam or engageable by the latter, means for swinging both of said levers about the pivot of said first lever, and means for swinging the second lever relative to the first to control the position of the roller carried by said second lever.

9. In an expansion engine, in combination, a valve for controlling admission and cut-off and means for controlling the movements of said valve to provide different predetermined periods of admission including a cam and a lever having a portion movable to effect valve opening and having a pivot and having a portion carrying a roller engageable with the cam, a second lever pivotally supported on the first lever and at one side of its pivot carrying another roller movable relative to the first roller between positions in which it is uncontacted by said cam or engageable by the latter, said second lever also having a portion at the opposite side of its pivot from said second roller, means for swinging both of said levers about the pivot of said first lever, and means for swinging the second lever relative to the first to control the position of the roller carried by the second lever, said means for swinging both or" said levers including a spring yieldingly pressing the portion of said second lever at the opposite side of its pivot from its roller, towards the other lever.

10. In an expansion engine, in combination, a valve for controlling admission and cut-off, and means for controlling the movements of said valve to provide different predetermined periods of admission including a cam and a lever having a portion movable to effect valve opening and having a pivot and having a portion carrying a roller engageable with the cam, a second lever pivotally supported on the first lever and carrying another roller movable relative to the first roller between positions in which it is uncontacted by said cam or engageable by the latter, means for swinging both of said levers about the pivot of said first lever, and means for swinging the secod lever relative to the first to control the position of the roller carried by the second lever, said means for swinging the second lever including cylinder and piston mechanism at the end of the second lever remote from its roller.

11. In an expansion engine, in combination, a valve for controlling admission and cut-01f, and means for controlling the movements of said admission valve to provide different predetermined periods of admission including a cam and a lever having a portion movable to elfect valve opening and having a pivot and having a portion carrying a roller engageable with the cam, a second lever pivotally supported on the first lever and carrying another roller movable relative to the first roller between positions in which it is uncontacted by said cam or engageable by the latter, means for swinging both of said levers about the pivot of said first lever, and means for swinging the second lever relative to the first to control the position of the roller carried by the second lever, said means for swinging the second lever including cylinder and piston mechanism comprising a cylinder carried by the second lever at the end of the latter remote from its roller,

9 a piston in the cylinder and having a portion engageable with a portion of the first mentioned lever, and means for supplying and venting fluid relative to the cylinder.

12. In an expansion engine having a crank shaft and a valve device for controlling admission and cut-off, mechanism actuated by said crankshaft for pulling said valve device in an opening direction including a crank shaft rotated cam and two cam follower rolls, and means including pivotally connected, relatively adjustable cam follower roll supporting levers for rendering one of said last mentioned cam follower rolls continuously effective in the control of said valve device and the other only at will.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date Re. 9,818 Schultz July 19, 1881 119,039 McGowan et a1. Sept. 19, 1871 181,315 Crihfield Aug. 22, 1876 632,888 Ayres Sept. 12, 1899 935,194 Edgar Sept. 28, 1909 Number Number 20 7,729 26,342 13,152 228,510

10 Name Date Gibson Nov. 5, 1912 Grasso Feb. 3, 1914 Lake Apr. 28, 1914 Allen Sept. 5, 1916 Medanich Dec. 30, 1919 Burkel et a1. Dec. 30, 1919 Rauen May 15, 1923 Atsumi June 16, 1925 Ingalls Apr. 26, 1932 Holmes Jan. 9, 1934 Gehres 21, 1935 Cawley Feb. 11, 1936 Morgan Dec. 7, 1937 Wiegand Apr. 5, 1938 Hattink Aug. 21, 1951 FOREIGN PATENTS Country Date Great Britain May 27, 1887 Great Britain Nov. 28, 1997 Netherlands May 15, 1925 Switzerland Nov. 16, 1943

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