US2698577A - Nutating piston fluid displacement device - Google Patents

Description

Jan. 4, 1955 R. ROY, JR 5 77 NUTATING PISTON FLUID DISPLACEMENT DEVICE Filed Dec. 3, 1952 5 Sheets-Sheet l INVENTOR v 54-77722); JA. ?0

Jan. 4, R. ROY, JR NUTATING PISTON FLUID DISPLACEMENT DEVICE Filed Dec. 3, 1952 3 Sheets-Sheet 2 IN VENTOR ee/V770); J/P.

BY yfzw/w ATTORNEYS Jan. 4, 1955 R. ROY, JR 2,698,577

NUTATING PISTON FLUID DISPLACEMENT DEVICE Filed Dec. 3, 1952 3 Sheets-Sheet 5 .500 e i 9 1m Em m' f a w ATTORNEYS United States Patent N UTATING PISTON FLUID DISPLACEMENT DEVICE Robert Roy, Jr., Bradford, Pa.

Application December 3, 1952, Serial No. 323,794

13 Claims. (Cl. 103-5) This invention relates to fluid displacement devices, more specifically nutating piston fluid pumps or motors, and aims generally to improve the same and systems employing the same.

Known forms of devices of this character, typical of the conventional practice in the art, are disclosed in Bowns Patent No. 410,308 dated September 3, 1889, and Goodner Patent No. 1,434,741 dated November 7, 1922. In such conventional forms the nutating piston is in the form of a disc having one radial slot in it the edges of which engage a partition wall positioned between the inlet and outlet parts, which Wall is positioned in a plane perpendicular to the mid-plane of the disc, separates the inlet and discharge sides of the devices, and prevents rotation of the disc, as shown at Q in Figs. 2 and 3 of Bowns, and at 30 in Goodner. This construction presents a serious problem of packing as the plane of the disc has to tilt as well as slide relative to the plane of the partition wall that intersects it.

An important object of the present invention is to overcome these difficulties by providing a new form of nutating axis fluid displacement device in which the need for a partition wall perpendicular to the mean plane of the disc is eliminated. Other objects and advantages of the invention will also be apparent from the detailed description of a preferred embodiment herein.

The invention resides principally in the novel construction in which the fluid displacement vane of the nutating piston progresses helically in the direction of the piston axis, the chamber in which the vane operates progressing helically in the direction of the axis about which the piston axis nutates. By this arrangement the wall between the inlet and outlet ports is positioned parallel to the helical passage, that is, at the angle of pitch of the helix, and no longer has to serve the function of preventing rotation of the disc. The invention further resides in the novel structure and packing arrangements and features of construction hereinafter described in connection with the accompanying drawings of an illustrative embodiment of the invention and systems employing the same, in which:

Fig. 1 is a disassembled perspective view of one form of the fluid displacement device.

Fig. 2 is a plan view thereof, with fittings omitted.

Fig. 3 is a vertical elevational detail viewed from the plane 22 of Fig. 2, showing small arcs in the casing wall of the device for accommodating the motion of the ends of the vane.

Fig. 4 is a cross section taken on the plane 4c Fig. 3.

Fig. 5 is a fragmentary detail showing the high pressure end of one form of vane, typical of its cross section.

Fig. 6 is a fragmentary detail showing the low pressure end of such form of vane.

Fig. 7 is an operational diagram illustrative of the fluid displacement in the operation of the device.

Fig. 8 is a diagram of a liquid pumping system employing several of the devices operating in series.

Fig. 9 is a diagram of a multi-stage air or gas compressor employing a plurality of the devices of progres sively decreasing size.

Fig. 10 is a diagram of an internal combustion engine system employing one of the devices for compressing the charge and a plurality of the devices of progressively increasing size connectable to a common shaft and driven by the products of combustion.

Fig. 11 is a partially diagrammatic plan view illustrating a preferred mode of gauging a plurality of the fluid disso placement devices in series mechanically and flow-wise.

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In the form shown in Figs. 1 to 4, the fluid displacement device includes, in combination, a nutating axis piston comprising a piston shaft 1, a ball 2 thereon, and a piston vane 3 carried by the ball. The piston vane 3 progresses helically about the ball 2 with respect to the piston shaft 1 as a longitudinal axis. As shown in Figs. 1 and 4 the ball 2 is preferably composed of two identical halves. The facing walls of the ball halves are helically surfaced for one turn, with the ends of this surface joined by a surface 2a extending in a longitudinal plane that includes the plane of the piston shaft 1. As shown in Fig. 3, the helical vane is clamped between the two halves of the ball 2, where it fits about the piston shaft 1, the assembly being secured by nuts screwed onto the ends of the shaft 1 and abutting against the ball sections. -As shown in Fig. 4, the sections of the ball 2 are so formed as to present a true spherical surface at each side of the vane 3, notwithstanding the thickness of the vane.

As shown in Figs. 1 and 4, the helical vane 3 makes one full turn about the axis of shaft 1 and the ends of the helical vane 3 terminate at the longitudinal radial plane 2a that includes the axis of the piston shaft 1, and that coincides with the ends of the helical faces of the halves of ball 2 in the form shown. Outwardly of the piston assembling nuts, the ends of the shaft 1 are reduced in cross section to form driving pins for engagement with crank elements 10 hereinafter described, so that the piston has a nutating motion while the cranks 10 and stub shafts 9 to which they are attached have simple rotary motion about their axes.

As shown in Figs. 1 and 4, the casing 4a4b in which the piston nutates has sealing surfaces 5 conforming to and contacting the spherical surfaces of the ball 2, and has a vane chamber 6 therein. The vane chamber 6 has a volume conforming to the volume scanned by the vane during the nutation of the piston, and thus itself progresses helically with respect to the main axis about which the piston shaft 1 nutates, herein coinciding with the axis of the stub shaft 9. As is best shown in Fig. 4, because of the relation of the chamber to the vane, the chamber actually winds about the center of nutation and is symmetrical in cross-section and radial spacing with respect thereto, which fact is clarified in Fig. 4 by including the port end of the cut-away sections of the casing in phantom lines to show the symmetry, even though this figure is sectioned as the longitudinal radial plane 2a above mentioned at which the vane ends terminate, with the piston in one of the positions of nutation at which this plane coincides with the plane of the chamber ends, hereinafter described.

For simplicity and economy, the casing is divided into two identical parts despite the peculiar shape of the vane chamber 6. This is accomplished by dividing it at least in part along the longitudinal radial plane 40 including the axis of the stub shafts 9, and conforming to the plane of the paper in Fig. 4, i. e. to the plane of surface 2a in the position of nutation shown therein.

In the illustrative embodiment, the division of the easing into two identical parts 4a and 4b is effected along the just identified plane at the ends of the vane chamber, and along the helical dividing surface of symmetry 4d having the same pitch as that of the helical chamber 6 and centered between the side walls thereof.

As clearly shown in Figs. 2 and 4 the dividing surfaces, wherever employed, are suitably gasketed, or sealed, as at 4e, the two halves of the casing being suitably flanged and bolted together.

As clearly shown in Figs. 1, 2 and 4, the casing 4a4b 1s prov1ded at its opposite ends with axial extensions 7, aligned when the casing is assembled. Each extension 7 is internally axially recessed as at 8 to accommodate the motion of one end of the nutating piston shaft 1. Each recessed extension 7 in the assembled device has axially positioned in it a stub shaft 9, carrying a crank element 10, there being a journal and thrust bearing 12 so positioning each stub shaft 9. In the form shown eachjournal and thrust bearing 12 is an antifriction or ball bearing having an inner race and an outer race with antifriction elements therebetween; the extension comprises one end wall supporting the outer race, herein afforded by the cap 11 threaded onto the extension 7; the stub shaft 9 being axially movable through the inner race of bearing 12; and there being a compression spring 13 interposed between the inner race and the crank means the inner race, Spring, stub shaft and crank means rotating as a unit. lubricant sealed bearing, or a self lubricating bearing may be employed, or a lubricant seal such as a felt ring may be interposed in the set-back space 14 that affords clearance between the inner race and cap 11, if desired. With this arrangement the crank elements 10 are urged toward the ball 2 and maintain a suitable and self-adjusting engagement with the ends of the piston shaft 1.

As was above noted, the ends of the piston vane 3, in the form shown, both lie substantially in a single radial plane including the piston shaft axis, i. e. in the plane 2a, Fig. 4. Hence, as the piston nutates, the tilting of the piston axis 1 in the plane of the paper in Fig. 1, causes the ends of the vane 3 to advance and retract relative to the longitudinal dividing plane 4c of the casing la-4b, as the tilt at right angles thereto causes them to swing back and forth across the ends of the chamber 6. Thus the vane ends trace or scan arcuate paths on either side of the plane 40 as the piston nutates. To accommodate this arcuate motion, the casing walls at the parts thereof extending in front of the vane ends in proximity to the ball 2, are arcuately curved as shown at 14 in Fig. 3. The complementary arcs shown in broken lines in Fig. 3 show the retraction path traced by each vane end when the other is advanced beyond the plane 4c by the nutation of the piston.

As best shown in Figs. 3 and 4, the pitch at which the helical vane 3 progresses about the axis of the shaft 1, or about the center of nutation, is so related to the angle of nutation that the vane ends scan areas that are nearly coplanar (though they advance and recede from said plane arcuately as just described in connection with Fig. 3), but which have their adjacent edges spaced apart sufficicntly to accommodate, or create, a wall 15 between them. This wall 15, as shown in Figs. 3 and 4 is created by the overlapping of the casing sections defining the ends of the chamber 6, which chamber ends are thus separated into independent, oppositely directed inlet and outlet ports at the ends of the chamber and substantially at the dividing plane 40. Since this wall 15 is afforded merely by the juncture of the ends of the helical casing walls at the opposite sides of the helical chamber 6, it may be considered as itself having a helical pitch, or it may be considered as a mere spaced separation of the ports having no third dimension as such. In any event it merely exists between the flat sides of the chamber contacted by first one side of one vane end and then by the other flat side of the other vane end, so that the vane ends merely touch it intermittently and so that no special packing is needed between the vane ends and the socalled wall as is required in the case of the wall transverse of the vane in the conventional devices to which reference has been made at the outset of this specification.

Since the inlet and outlet ports, as just noted, are oppositely directed, and are merely the ends of the helical chamber, inlet and outlet conduits or fittings 16 (Fig. l) are easily secured thereto that may themselves extend generally helically about the main axis of the stub shafts 9 of the device, or more or less tangentially to such helical path.

As will be apparent from Figs. 1 to 4, to enable securement of the port fittings 16, the port ends of the casing 4a4b are suitably flanged at 4 herein along the plane 40. As the flanged faces 16a of the fittings abut against the plane 40 (Fig. 3) except for the interposition of suitable gasketing or the like, the underlips of these fittings 16 are cut away, as at 16b, Fig. 1, to at least conform to the arcs 14', Fig. 3. As clearly shown in Figs. 1 and 4, the fittings or couplings 16 are secured to each end or section of the chambered casing at opposite sides of the helical dividing plane or wall 15 and communicate with the entire chamber areas presented by the cooperating ends of both sections 4a, 4b of the divided casing when such casing is divided by a helical dividing plane 4d as shown.

For many uses a simple rigid helical vane 3 is satisfactory and the manner of supporting the nutating piston and the ends of the piston shaft 1, best shown in Fig. 4, maintains adequate side wall contact pressure to insure a satisfactory seal, sliding contact or fine clearance being relied upon to prevent any substantial leakage past the peripheral edge of the vane.

For other purposes known or other means may be employed to pack or seal the-peripheral edge and even to augment the side wall contact of the vane with the chamber walls. Dut to the peculiarities of the helical device afforded by this invention, it is especially well adapted for a simple and efficient seal augmentation, diagrammatically illustrated in Figs. 5 and 6.

According to these figures, the vane 30 or the portion thereof extending from the ball, is made hollow and with one or more flexible walls, which may be slightly concave as shown. At the low pressure end of the device the interior of the hollow vane 30 is closed, as shown in Fig. 6, but if its peripheral wall is concave, the thin space between such peripheral wall and the casing wall is left open to low pressure. At the high pressure end of the device, as shown in Fig. 5, the interior of the hollow vane is open, but if the peripheral wall thereof is concave, the slight space between that wall and the outer wall of the chamber is closed in any suitable way, as by a short length of packing, a short omission of the concavity, or otherwise. With this construction the pressure on the high pressure side of the vane at any given part of its cycle, is counterbalanced, and the flexible wall is pressed smoothly against the chamber wall, while the differential pressure across the perimetral flexible wall mantains this wall in sealing engagement at all times. If desired the perimetral wall of the vane may be formed of self-lubricating bronze or be provided with a strip of bearing metal or other packing for bearing against the perirnetral wall of the chamber.

Reference has just been made to the cycle of operation of the device, which cycle is diagrammatically illustrated in Fig. 7. In this figure the 0 and 360 chart shows the two ends of the helical vane in contact with one wall of the helical chamber, with its central portion in contact with the other wall thereof, corresponding to the position of nutation shown in Fig. 4 Considering the operation of the device as a pump, under these conditions one body of fluid a is being discharged, another body b is sealed off between the ends of the vane contacting the chamber wall, and another body c is being sucked in at the inlet. Progressing through 60 and to the tail of the body a and the leading half of the body b are being discharged, and the tail of body 0 and leading half of body d are being sucked in. At 180 the vane ends contact the opposite wall of the chamber and the body 0 is trapped between them, the bodies b and d being half discharged and half sucked in respectively. Progressing through 240 and 300 to 360 the tail of the body b and leading half of body 0 are discharged while the tail half of body d and leading half of body e are being sucked in. Finally at 360 the body d is trapped between the piston ends. Thus for each 180 rotation of the device one trapped body of fluid is positively displaced.

When driven as a motor, a source of fluid pressure is connected to the inlet end of the device. Referring to the 0 chart of Fig. 7, the body of fluid at a is discharging to a low pressure area, that at b is trapped and the body 0 is at high pressure. Thus the longitudinal component of the difference in pressure between a and c acting on the vane is equal to such difl'erence in pounds per square inch multiplied by the cross section of the chamber. Progressing through 60 and 120 to 180, the pressures of a and b are both dropped to outlet pressure, and c and d are at the high pressure, so the same steady pressure difference exists. Thus throughout the cycle a constant pressure difference is maintained and the device operates as a positive displacement turbine.

As shown in Fig. 8, a system employing the device as a high lift pump for non-compressible fluid, may comprise a plurality of the devices 4 with their chambers connected in series and located at progressively higher levels with respect to the level of the liquid source 35. As each device may lift the liquid nearly to a column height equivalent to one atmosphere of pressure, the arrangement may be employed to lift the liquid by as many of such column heights as there are devices 4. Since the devices are positive displacement devices, the discharge from the final pump of the series may be delivered to a closed pressure chamber 36, under a body of compressible fluid 37, from which the liquid may be withdrawn at rates independent of the rate of pumping and at whatever pressure 18 created in the chamber 36.

As shown in Fig. 9, since the device affects positive displacement it may be used for pressurizing air or other compressible fluids. For this purpose a plurality of the units 4 may be employed in series for compressing the fluid in steps to reduce the pressure differences across each unit, the devices progressively decreasing in size as shown, the final device of the series discharging to a suitable receiver 38, and the several shafts 9 of the devices 4 being driven from a common source of power illustrated as a countershaft 39.

As shown in Fig. 10, a similar series of devices 4 of progressively increasing size may be employed to obtain mechanical power by the expansion of a compressible fluid therethrough without producing an excessive pressure drop across any one of the devices, and such power may be delivered from the several stub shafts 9 to a common shaft 40, shown as a counter shaft in Fig. 10. The source 41 of expansible fluid under high pressure may be a combustion chamber provided with suitable igniting means 42 and a check valve 43, and the explosive charge may be continuously delivered thereto through the check valve 43 by another one of the devices 4 drawing the charge from a carburetor or other charge forming device 44.

As previously mentioned, the oppositely directed inlet and outlet ports of the present device constitute continuations of the helical chambers 6 of the devices progressing helically about the main axis of the stub shafts 9 thereof. Hence the devices are especially Well adapted to have their stub shafts 9 coupled to one another in line, and to have the inlet and outlet ports of the helical chambers of devices of the same hand connected in series with but a short fluid coupling substantially aligned with the helical chambers, and not interposing any sharp bends therebetween that would reduce the hydraulic or pneumatic elficiency of the system. These capabilities are illustrated, partly diagrammatically, in Fig. 11, which shows two of the devices 4 with their stub shafts coupled together as by a flexible or splined coupling 45 that may be embraced within a suitable extension coupling sleeve 46 that may have right-and-left hand threaded engagement with the extensions 7, to secure the units 4 together; and which also indicates by the broken lines 47 how a direct coupling without sharp bends and continuing the general path of the helical chambers may be made between them.

With such an arrangement the units 4 of the series employed in Fig. 9 may be closely and efliciently coupled together; the same is true with respect to the series of units 4, and the additional unit 4 of Fig. 10, all of which may in effect he on a common shaft so that the turbine shaft drives the charge feeding unit, proportioned to provide the proper volumetric displacement ratio; and with long couplings 45 and 47 or long couplings 45, 46, and 47 the pumping units 4 of Fig. 8 may also be directly coupled while maintaining the proper differences in elevation therebetween.

For general definition herein the helical vane 3, the helical chamber 6 and the helical dividing plane 4d have been described as helical with reference to the respective axis of the parts carrying the same, and in such connection it will be understood that in the form shown each of these elements is helicocentric or helicoradial about the center of nutation as clearly shown in Figs. 1 and 4, so that a radial line drawn in the side faces of any of these elements, disregarding gasketry, passes substantially through such center of nutation, which fact accounts for the wavy appearance in Figs. 2 and 11 of the line of intersection of the heticocentric gasketed plane of division 4d, 42 with the eared or scalloped bolt accommodating flanges of the units 4a, 412.

While there have been described herein What are at present considered preferred embodiments of the invention, it will be obvious to those skilled in the art that minor modifications and changes may be made therein without departing from the essence of the invention. It is therefore to be understood that the exemplary embodiments are illustrative and not restrictive of the invention, the scope of which is defined in the appended claims, and that all modifications that come within the meaning and range of equivalency of the claims are intended to be included therein.

I claim:

1. In a device of the class described, in combination, a nutating axis piston comprising a piston shaft, a ball thereon, and a piston vane carried by the ball, said piston vane progressing helically with respect to the axis of said piston shaft, a casing having sealing surfaces contacting said ball while permitting nutating motion of said piston, said casing having a vane chamber therein, said vane chamber progressing helically with respect to the axis about which the piston shaft nutates and having a volume conforming to the volume scanned by the vane during the nutation of the piston, said helical chamber having inlet and outlet passages at its ends formed as helical extensions of said helical chamber.

2. In a device of the class described, in combination, a nutating axis piston comprising a nutating piston shaft, a ball thereon and a piston vane extending from the surface of the ball, said piston vane comprising approximately one complete turn progressing helically with respect to the axis of said nutating shaft by such pitch that during nutation of the piston its vane ends scan areas that are nearly co-planar but have between their adjacent edges a space sufiicient to accommodate a wall, a casing having sealing surfaces contacting said ball while permitting nutating motion of said piston, said casing having a vane chamber therein, said vane chamber progressing helically with respect to the central axis about which the piston shaft nutates and having a volume conforming to the volume scanned by the vane during the nutation of the piston, said helical chamber having inlet and outlet passages at its respective ends on opposite sides of the casing wall occupying said space between the ends of the chamber, said passages being formed as helical extensions of said helical chamber.

3. A combination according to claim 2, in which the ends of the vane both lie substantially in a single radial plane including the piston shaft axis, so that said vane ends, respectively, scan arcs on either side of said plane as the piston nutates, said casing, at the part thereof extending in front of the vane ends in proximity to the ball, being arcuately curved to accommodate said arcuate motion.

4. A combination according to claim 2, in which the casing is symmetrically divided into two identical sections along a helical dividing surface having the same pitch as that of the helical chamber and centered between the side walls thereof, and along a longitudinal radial plane connecting the ends of said helical dividing surface.

5. A combination according to claim 4 in which the inlet and outlet passages include ports formed at said longitudinal dividing plane and which further comprises couplings secured to each section at the outer side of said helical dividing plane and communicating with the entire chamber area presented by the cooperating ends of both sections adjacent said plane.

6. A combination according to claim 4, in which each divided half of the casing has an axial extension, aligned with that of the other when the two halves are assembled, which extension is internally axially recessed to accommodate the motion of one end of the nutating piston shaft, a stub shaft axially positioned in said recessed extension, a journal and thrust bearing in said extension so positioning said stub shaft, and crank means connecting said nutating and stub shafts within said extension.

7. A combination according to claim 6 in which each bearing is a combination journal and thrust antifriction bearing having an inner race and an outer race with antifriction elements therebetween, in which the extension comprises an end wall supporting said outer race, in which the stub shaft is axially movable through the inner race, and in which a compression spring is interposed between said inner race and said crank means for urging said crank means into engagement with said piston shaft, said inner race, spring, stub shaft, and crank means rotating as a unit.

8. A combination according to claim 2 in which the casing is symmetrically divided into two identical halves at least in part along a radial plane including the axis about which the piston nutates.

9. A fluid displacement device of the nutating piston type-i. e. of the type that has a casing with a chamber therein and a piston that nutates about a center of nutation and that is provided with a piston vane that nutates in the chamber in said casing and that is provided with inlet and outlet passages extending from said chamber to the exterior of the casing-particularly characterized in that its piston vane and chamber progress helically about the center of mutation on which the piston nutates, in that the pitch of the helically progressing vane is greater than the angle of nutation of the piston so that the cross section of one end of the helical chamber is spaced axially away from that at the other end of such chamber, and in that its inlet and outlet passages are formed as helical extensions of said helical chamber.

10. A fluid displacement device according to claim 9, in which the helical vane is hollow and has at least one concave flexible wall and is internally in communication with the displaced fluid at the high pressure side of the device so that fluid pressure expansion of said concave wall creates a sealingpressure thereof against the Wall of the chamber.

, 11. A fluid displacement device according to claim 10, in which the peripheral Wall of the hollow vane is flexible and pressed against the peripheral Wall of the chamber by said fluid pressure.

' 12. A fluid displacement device according to claim 9, having inlet and outlet fittings extending from the ends of the helical chamber and generally helically about the main axis.

13. The combination of a plurality of deviceseach ac- References Cited in the file of this patent UNITED STATES PATENTS Re. 18,527 Simmons July 12, 1932 883,888 Keller Apr. 7, 1908 936,932 Neumann Oct. 12, 1909 1,271,729 Kristufek July 9, 1918 2,365,616 Zweifel Dec. 19, 1944 2,414,166 Pescara Jan. 14, 1947 2,567,581 Salter Sept. 11, 1951 FOREIGN PATENTS 943 Great Britain 1888 8,227 Great Britain 1911 106,347 France 1875 441,528 Great Britain Jan. 21, 1936

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