US2717555A - Engine for pumping and the like having multiple rotors and swinging arms - Google Patents

Description

3 Sheets-Sheet 1 INVENTOR. JOHN M H//vcK/ EY ATTORNEYS PAY HINCKLEY ENGINE FOR PUMPING AND THE LIKE HAVING MULTIPLE ROTORS AND SWINGING ARMS VJW Sept. 13, 1955 Filed June 2l. 1949 Sept. 13, 1955 J. N, HlNcKLl-:Y 2,717,555

ENGINE FOR PUMPNG AND THE LIKE HAVING MULTIPLE ROTORS AND SW-INGING ARMS Filed June 21. 1949 5 sheets-sheet 2 37 f5" 4o" H5 I 37 INVEN TOR.

/3 JOHN N. //NCKLEY 43., l L 43 l BY la' as" 35 l m f/m 214, 44, /4 ATTORNEYS.

Sept. 13. 1955 L HlNcKLl-:Y

ENG R P M L I ROT ING AND H LIKE HAVING ORS AND NGING ARMS Filed June 2l. 1949 3 Sheec's-Sheel 5 90 160 ANGLE OF ROTAT/ON OF ROTOR .Y no; T L N K E C VN mm N, N M J ATTORNEYS.

United States Patent O ENGINE FR PUMPNG AND THE LiKE HAVING MULTIPLE ROTORS AND SWHNGNG ARMS .lohn N. Hinckley, Belmont, Mass.

Application June 21, 1949, Serial No. 100,352

7 Claims. (Ci. 1113-124) The invention relates to rotary engines, or pumps, such as used for placing uids under compression or under vacuum.

Objects of the invention are, generally, to provide such an engine or pump which is small, compact and simple in construction; and which can handle gases, liquids and owable solids of widely varying viscosity and fluidity.

According to a preferred form of the invention, the pump comprises a cylindrical casing having closely related, aligned inlet and outlet passages. Journaled within the cylindrical chamber are two, two-lobe rotors, the rotors being disposed at a geometrical 90 angle. Cooperating with each rotor is an arm carrying a partition or vane bearing against the cam surface of the rotor. Each arm is so pivoted that the end of the vane contacting the rotor moves along a substantially radial line with respect to the center of rotation of the rotor. The arms are relatively long to obtain minimum angular movement for the linear movement of the vane. Each pump unit discharges fluid at a rate which varies from zero to a maximum. The cam surfaces of the rotor are so shaped that the separate discharges of the units complement each other to provide a resulting discharge which is substantially uniform in rate. At the same time the cam surfaces of the rotors are such as to impart a substantially harmonic motion to the arms. The arms are held against the rotor cam surfaces by separate compression springs acting between the casing and caps pivoted between the side panels of the arms.

The invention also consists in certain new and original features and combinations hereinafter set forth and claimed.

Although the novel features which are believed to be characteristic of this invention will be particularly pointed out in the claims appended hereto, the invention itself, as to its objects and advantages, and the manner in which it may be carried out, may be better understood by referring to the following description taken in connection with the accompanying drawings forming a part hereof, in which:

Fig. 1 is a central vertical longitudinal section taken through the pump;

Fig. 2 is a transverse section, taken on the line 2-2 of Fig. 1, illustrating the iuid path of one of the pump units and illustrating, too, the action of the arms on the two rotors;

Fig. 3 is a section, taken on the line 3-3 of Fig. 1, illustrating the position of the arm on the other pump unit;

Fig. 4 is a plan section, taken on the line 4 4 of Fig. 2;

Fig. 5 is an outline of a rotor, illustrating the shape of its cam surface;

Fig. 6 is a perspective of one of the arms;

Fig. 7 is an enlarged view illustrating particular cooperation between the arm, rotor and casing;

Fig. 8 shows theoretical curves, illustrating the man- Patented Sept. 13, 1955 ner in which the separate discharges of the two pump units complement each other to provide uniform discharge; and

Fig. 9 is an outside view of a modied form of pump using two outboard bearings.

In the following description and in the claims, various details will be identified by specific names for convenience, but they are intended to be as generic in their application as the art will permit.

Like reference characters denote like parts in the several figures of the drawings.

In the drawings accompanying and forming part of this specification, certain specific disclosure of the invention is made for purposes of explanation, but it will be ice ' understood that the details may be modified in various respects without departure from the broad aspect of the invention.

Referring to the drawing, the pump, according to the invention, comprises, in general, a casing 10 made up of a body 11 with end plates 12 and 13. The body is bolted to base 14 carrying an outboard bearing 15. Main shaft 16 is journaled in outboard bearing 15 and in bearing 31 on closed end plate 12. Two two- lobe rotors 17 and 18 disposed at a 90 index angle are keyed to main shaft 16, and a center plate 21 is disposed between the rotors. Arms 19 and 20 are mounted on pivot shaft 35 and bear against their respective rotors. Body 11 has inlet 22 and outlet 23.

In operation, with the main shaft 16 rotating in the direction of arrow A, uid is drawn in through inlet 22, is swept around the cylindrical chamber by the rotors 17, 18 and discharged from outlet 23, as will be explained in detail hereinafter. Each rotor causes a varying or intermittent discharge. The two rotors are in such phase relation that the maximum points of discharge of each rotor coincide with the minimum points of discharge of the other rotor; this causes a resultant iiow which is substantially uniform.

The pump will now be described more in detail.

The body 11 contains a cylindrical rotor chamber 25 intersected by inlet port 27 and an outlet port 28. These ports are separated by a thin wall 36 and together span an angle of almost of the circumference of the rotor chamber 25. Thin wall 36 has a cylindrical surface laid out concentric with the center of arm shaft 35. The inlet port 27 connects by a smooth walled conduit with inlet opening 22. Outlet port 28 connects by a smooth walled sector shaped, open-ended conduit with outlet opening 23. Inlet and outlet opening 22, 23 are suitably internally threaded to receive connecting pipes (not shown).

Closed end plate 12 carries a bearing 31 having a bushing 32 journaling main shaft 16. Open end plate 13 has a box 38 through which the main shaft passes. Packing 39 (or special mechanical seal) is held in the box by a gland 40 which is in turn held in position by suitable bolts 43. Box 38 has an annular flange 41 against which seats ring 42 for holding the packing (or mechanical seal) 39 in place. When used with mechanical seal, ring 42 is not used, and the rotatable member of the seal is driven from the shaft or from the rotor by a drive ring which fits with clearance in the annular space between iiange 41 and shaft 16.

End plates 12 and 13 have at inner surfaces for the rotors and arms to bear against; end plates 12, 13 have pivot shaft seats 33 counter-sunk at 34 for the hubs of arms 19 and 20. See Figure 4. Two seats 33, 34 are provided in each end plate; only one set of seats in each plate is used at any one time. The end plates are clamped against the body by bolts 30 and have gaskets 29 in between.

The second set of seats are for the purpose of permitting transposition of the end plates 12, 13 (and base 14) in case it is desired to drive the pump from the opposite side without changing direction of shaft rotation. The second set of seats are also for the purpose of permitting reversal ofthe directionof flow by reversing the position of the body 11 and all internal parts with the exception of rotors- 17, 18, center plate 21 and shaft r16, leaving the end plates 12, 13 and base 1d in the same position.

The body 11 has mounting lugs 44 through which bolts 45 pass to secure the casing to the base 14. The outboard bearing 15 has a bushing 46. The shaft 16 overhangs bearing 15 and has a keyed portion 37 for reception of a gear, pulley or direct coupling (not shown) for driving the pump.

The rotors 17 and 18 are identical. Hence, it is only necessary to describe one. The curvature of the rotor surface is such as to give the arms smooth movement with minimum vibration; it is such that the two rotors complement each other to give uniform rate of fluid iiow.

These problems, and rotor shape, are discussed more at length below.

Each rotor has a keyway 49 disposed at an angle of 45 with the major axis 47 of the rotor. The rotor sur face is symmetrical about the major axis 47 and about minor axis 48. The rotor surface has two straight portions 50, four arcs 51 laid out with Vpoints 53 as a center; and two arcs 52 laid out with the axis of the shaft as a center. Thus, the points where the minor axis 4S crosses the cam surface are low points and the arcs 52 at the ends of the major axis 47 are high points The surfaces 51), 51 constitute rises or falls and the arcs 52 constitute dwells The manner of laying out the rotor shape is explained hereinafter.

The rotors 17 and 18 are placed on the shaft, at a 90 angle, with their keyways 49 receiving the single key 55 and with the center plate 21 disposed between the rotors. The center plate 21 snugly ts the cylindrical wall 26 and the partition 36 between inlet and outlet; the center plate 21 has a keyway receiving key 55 and rotates with the rotors. of chamber and the end of the partition 36. The rotors also snugly lit against the end plates 12 and 13; these snug fits minimize leakage.

Referring now also to Fig. 6, the arms 19 and 2i) are identical and interchangeable; hence it is only necessary to describe one in detail. Each arm comprises side panels or members 56 connected by a vane or wall member 55. The side panels 56 have hubs 57 through which the arm shaft passes. The vane 58 terminates in a rounded tip or nose 59 which bears against the rotor surface. The rounded nose 59 is laid out with the point 67 as a center. The outer surface 68 of the vane 53 is cylindrical, laid out with the axis of arm shaft 35 as a center and snugly fits the cylindrical surface of the partition 36. The ends of vane 58 snugly engages the end plates 12, 13 and center plate 21.

Although so shown, it is not necessary for side panels 56 to snugly engage end plates 12, 13 and center plate 21. It is only important that the side panels 56 permit uid flow around or through them. The side panels 56 have holes 60' for pivot 60 which supports cap 61. Cap 61 has a depressed seat 62 for the end of helical spring 63. The spring 63 seats in casing groove 24 which extends all the way across the body 11.

Inoperation, it will be understood that the rotor springs hold the arms down against the surfaces of the rotors and that as the rotors rotate in the direction of arrow A, the arms oscillate back and forth. Referring to Fig. 2, the high point of rotor 17 is passing the zone of inlet 27 and the rotor has already trapped a volume of fluid in the space indicated by 69. Further movement of rotor 17 in the direction of arrow A carries the fluid trapped in space 69 around to the outlet port 28. Fig. 2 also shows uid previously trapped by the other side of the rotor 17 being delivered into the discharge port 28.

The dwells 52 snugly tit the cylindrical wall l It will be noted that the amount of fluid discharged by rotor 17 varies from a minimum occurring when arm 19 engages dwell 52 to a maximum occurring when arm 19 engages the middle of flat portion 5t). Since the two rotors 17 and 18 are indexed at 90, the points of maximum discharge of each rotor are intertted between the points of maximum discharge of the other.

It will be noted that, in addition to the force of the springs 63, the discharge fluid pressure acting on the tops of varies 5S is available for holding the arms down against the rotors; also that the pivoted caps 61 relieve the springs from a bending movement which would occur if the caps were not pivoted.

The pressure of springs 63 may vary according to design; excellent results have been obtained with springs causing the arms to exert very slight, but positive, pressure on the rotor when the arms are at their low points and the pump is at rest. The springs should have fairly high build-up characteristics, causing them to firmly press the arm tips against the rotors when the arms are at their high points; this prevents the inertia of the arms from raising them off the rotors.

The shape of the rotor surface and its relationship to the oscillating arms will now be discussed. This relationship is important from several standpoints: obtaining smooth fluid ow characteristics; obtaining easy motion for the arms; and obtaining shapes of both rotors and arms convenient for commercial manufacture.

It is important that the duplex pump, utilizing two, two-lobe rotors have a substantially uniform discharge rate. An absolute uniform discharge rate can be obtained theoretically with proper rotor shape and proper arm relationship. In practice, absolute uniform rate of discharge is not obtained because it is not desirable in commercially manufacturing the rotors and arms; but a suciently close approximation of uniform discharge rate is obtained for all practical purposes.

It is desirable to impart to the arms a simple harmonic motion. This reduces the duty of the springs and stresses on the arms and rotors. The rotor shape described above and illustrated in Fig. 5, is suciently close to theoretical shape to impart a motion to the arms that is approximately simple harmonic.

It is important also that the pivot shaft 35 for the arms be properly located; it is important to have the nose center 67 of the arm move along a line which substantially coincides with a radius of the main shaft 16, and that the thickness of vane 5S be small. This has a significant effect on the general contour of the rotor necessary to give substantially uniform discharge. It is important that the arm be relatively long to make vane movement more nearly straight; it will be noted that the effective arm length (see BC in Fig. 7) is substantially greater than the radius of the main chamber 25.

The rotor shape is determined as follows. Referring more particularly to Fig. 7, the length of the arm (BC), the diameter of the cylindrical chamber (major axis 47), the length of the minor axis 48, the line of movement (CO) of the center 67 of nose 59, the radius of rounded nose 59, the position of the arm pivot (line OB) are all first determined from experience, giving effect to the desirable relationships pointed out above. The exact rotor shape is then plotted by laying out the surface, as a cam, to give true simple harmonic motion to the arm. This method of laying out a cam is well known to those skilled in the art. After obtaining the exact shape to give true simple harmonic motion to the arm, the shape is approximated by substituting the two straight portions 50, four arcs 51 and two dwells 52, above mentioned. I have found that this combination of simple curves gives a very close approximation of the curve as plotted.

The shape of the rotor shown in Fig. 5 is largely a matter of compromise. The Variation of the motion it imparts to the arm from simple harmonic is not serious enough to require heavy springs. The discharge rate of the duplex pump is quite close to the theoretical constant rate. Because of the symmetrical shape and location of the keyway, the same rotor may be used interchangeably on both sides of the duplex pump. The flat surfaces of the rotor give a very convenient manufacturing gauge for measurement. The at surfaces and arcs of circles making up the cam surface are easily machined.

Referring to Fig. 8, a set of curves is shown to illustrate the discharge from the pump. The ordinate indicates rate of discharge; the abscissa indicates angular position of the rotor. Curve X indicates the discharge of rotor 17; curve Y indicates the discharge of rotor 18. These curves are shown as true sine curves for simplicity of illustration. Actually, the separate discharge of each rotor is only approximately simple harmonic. As will be noted, the geometrical phase relation of the curves is 90, but the cyclic phase relation is 180. This arises from the fact that each rotor has two lobes and each lobe causes the discharge to Vary through a complete simple harmonic cycle.

The arithmetical sum of curves X and Y is a straight line Z, indicating a theoretically constant discharge rate. The actual discharge rate has been found from actual tests to have a small variation from theoretical constant flow but the discharge is sufficiently uniform for most practical purposes.

The relationship between the curves X and Y in Fig. 8 and the discharge of the rotors will now be discussed. Rotor 17 in Fig. 2 has just passed its point of minimum discharge (arm on high point) and will reach its point of maximum discharge when the low point of the rotor passes under arm nose 59; this corresponds to the first 90 of curve X. As rotor 17 continues to rotate and arm nose 59 rides from the low point to the high point of the rotor, its discharge rate decreases from maximum to zero; this corresponds to the part of curve X between 90 and 180, and so on. At the same time rotor 18 is discharging according to the law of curve Y.

It will be noted that the curves X and Y, indicating the separate discharge rate of both units of the duplex pump, may be theoretically of other shapes; so long as their arithmetical sum is a horizontal straight line-so far as the problem of uniform discharge is concerned. However, for ease of operation of the reciprocating arms, the approximately simple harmonic discharge is indicated.

It will be noted that the pump, inherently, has a substantially perfect seal against back flow in case the pump stops. The area above eac'h rotor is always sealed by the arm. The area below each rotor is always sealed by a lobe being in contact with the cylindrical surface of the chamber 25 somewhere between inlet port 27 and outlet port 28.

The pump may be made of different materials, both metallic and non-metallic, depending upon the use to which it is put and the materials being pumped. Excellent results have been obtained by making the casing of a cast nickel alloy sold under the trade name of Ni-Resist. This resists the corrosion action of many fluids. Good results have been obtained by making the compression springs of stainless steel. Cast nickel alloy arms stand up well. Cast nickel alloy rotors also stand up well and may be precision machined. The main shaft and arm shafts are of stainless steel, hardened and ground for long reliable service.

Thus a pump is described which is simple in construction, has few parts, will give long life and trouble-free operation, It is of comparatively small geometrical size for its capacity. It gives substantilly uniform discharge; provides high vacuum and discharge; it can be installed in a straight line of pipe, just as easily as a gate valve; it has high mechanical efficiency and high volumetric eiiciency; it gives quiet, smooth operation; it permits no fluid re-circulation or cross leakage; it pumps both liquids and gases and provides a good vacuum pump, a good pressure pump, and a good compressor.

The pump may be used for handling fluids of corrosive nature, viscous materials, and materials of low fluidity. Due to its simplicity and ease of disassembly it is ideal for use as a sanitary pump in handling foods or other materials where cleanliness and sterility are a factor.

The dimensions of the pump may vary according to the size and the use. As an example, the cylindrical chamber of the pump may be 3 inches in diameter and 3 inches in axial length. Such a pump may be run at speeds from 400 to 1000 R. P. M., having a displacement of from ll to 27 gallons per minute; it may operate with discharge pressures up to 100 pounds per square inch on lubricating fluids; it may operate with vacuums up to 28 inches of mercury. Suction and discharge pipe size of such a pump may be 11/2 inches, the main drive shaft may be 1% inches in diameter.

Referring now to Fig. 9, the pump may be made with two outboard bearings, Here parts are given numbers with primes and double primes, corresponding to numbers of the main form. As shown, the base 14 has two outboard bearings 15 and 15". Added bearing 15 is separately bolted to base 14. The main shaft 16 journaled in these bearings passes through stuffing boxes or other mechanical seals 38 and 38 in both end plates of casing 10. This form is especially useful when it is essential to keep lubricant away frrom the material being pumped.

It will be understood that center plate 21 may be xed `in the casing if desired; in this event, the plate 21 may have a lug projecting up between the paths of tips or noses 59 of the arms 19, 20. This projecting lug seals any slight leakage that may theoretically occur when the arm is at its high point on the rotor and the inner end of the arm (facing the other arm) is not bearing against anything. In practice, the rotatable center plate, as illustrated, is preferred because of simplicity of construction.

It will be understood that the duplex arrangement of two lobe rotors is desired for simplicity; but triplex, (or other multiple) two lobe units may also be used. With such multiple arrangements the phase relation or index angle between the several rotors will vary according to the number of units to obtain smooth discharge; for example, in the case of triplex pump, the three two-lobe rotors of the three units may be arranged at 60 degree index angles.

In all forms of the invention, the pump may be run as a motor in either direction by applying uid pressure to either inlet 22 or outlet 23 according to the direction of rotation desired. The machine will also run in either direction as a pump; but the direction indicated by the arrow A is preferred.

While certain novel features of the invention have been disclosed herein, aud are pointed out in the annexed claims, it will be understood that various omissions, substitutions and changes may be made by those skilled in the art without departing from the spirit of the invention.

What is claimed is:

l. In a pump or the like, a casing having a cylindrical chamber with inlet and outlet passages, a shaft having a key and mounted for rotation within said chamber, two rotors mounted on said shaft, each rotor having two diametrically opposed lobes and having its outer surface symmetrical with respect to the major diametral axis connecting the center points of said lobes, said outer surface also being symmetrical with respect to a minor diametral axis perpendicular to said major axis, said rotors being identical and interchangeable, each rotor having a key way located at a point 45 between its major and minor axis, whereby said rotors may be disposed on said shaft with their respective key ways engaging the shaft key and with the rotors in relationship to each other, and

arms pivoted to said chamber wall and bearing on their respective rotors to separate said inlet and outlet passages.

2. In a pump or the like, a casing having a chamber, a shaft having key means and mounted for rotation within said chamber, two rotors mounted on said shaft, each rotor having two diametrically opposed lobes and having its outer surface symmetrical with respect to the major diametral axis connecting the center points of said lobes, said outer surface also being symmetrical with respect to a minor diametral axis perpendicular to said major axis, said rotors being identical and interchangeable, each rotor having a key means located at a point 45 between its major and minor axis, whereby said rotors may be disposed on said shaft with their respective key means engaging the shaft key means and with the rotors in 90 relationship to each other.

3. In an engine, a casing having a cylindrical bore with inlet and outlet passages, a rotor in said bore, an arm having spaced side members pivoted to said casing and a vane member bearing against said rotor to separate said inlet and outlet passages, a seat between said side members, a pivot shaft passing through said side members and said seat, and a helical spring seated on said seat and operating against the casing to hold the arm against the rotor, said side members having substantial depth whereby said seat is positioned substantially within the confines of the arm.

4. In an engine, a casing comprising a body with removable end plates, said body having a cylindrical chamber and a thin partition wall extending axially of the chamber and outwardly therefrom and dividing the space into an inlet and outlet port, said outlet port being sector-shaped and having a substantially cylindrical surface on the side of said partition wall, said casing having aligned inlet and outlet passages communicating respectively with said inlet and outlet ports, a main shaft passing through at least one of said end plates, two, two-lobe rotors on said shaft in 90 relationship, a removable center plate between said rotors closely fitting the wall of said cylindrical chamber, an arm for each rotor, each arm comprising spaced side panels connected by a vane, said vane having a nose riding on its corresponding rotor, said vane slidably engaging said cylindrical surface, an arm shaft seated in said end plates, said side panels having bearings riding on said arm shaft, each arm having a cap pivoted between the side panels thereof, each arm having a spring seated on said cap and operating against the wall of the casing, said arm shaft passing through said outlet port in such position that said nose moves substantially on a radius of said main shaft.

5. In an engine, a casing comprising a body with removable end plates, said body having a cylindrical chamber and a thin partition wall extending axially of the chamber and outwardly therefrom and dividing the space into an inlet and outlet port, said outlet port being sector-shaped and having a substantially cylindrical surface on the side of said partition wall, said casing having inlet and outlet passages communicating respectively with said inlet and outlet ports, said inlet and outlet ports together occupying between 90 and 180 of the total circumference of the cylindrical chamber, a main shaft passing through at least one of said end plates, two, twolobe rotors on said shaft in 90 relationship, a center plate between said'rotors closely fitting the wall of said cylindrical chamber, an arm for each rotor, each arm carrying at its end a vane, said vane having a nose riding on its corresponding rotor and engaging said cylindrical surface, an arm shaft seated in said end plates, said arms having bearings riding on said arm shaft, each arm having a cap pivoted thereto, each arm having a spring seated on said cap and operating against the wall of the casing, said arm shaft passing through said outlet port in such position that said nose moves substantially on a radius of said main shaft.

6. In an engine, a casing comprising an open ended body, said body having a cylindrical chamber with closely associated inlet and outlet ports, said body having a partition separating said ports, detachable end plates closing said cylindrical chamber and said discharge conduit, a main shaft, means for journaling said main shaft for rotation in said end plates, a rotor on said shaft having a cam surface, an arm adjacent said outlet port and having a nose riding on said cam surface, said end plates having first and second sets of aligned seats, a pivot shaft seated in one set of aligned seats, said arm being journaled on said pivot shaft, said second set of seats providing a mounting for said pivot shaft when said end plates are reversed with respect to said body.

7. In an engine, a casing comprising an open ended body, said body having a cylindrical chamber with closely associated inlet and outlet ports, said body having a partition separating said ports, said body having an inlet opening connected to said inlet port by a closed conduit, said body having an outlet opening connected to said outlet port by a sector-shaped, open-ended conduit, detachable end plates closing said cylindrical chamber and said discharge conduit, a main shaft, means for journaling said main shaft for rotation in said end plates, a rotor on said shaft having a cam surface, said cam surface having sealing relation with the cylindrical wall of said chamber, an arm in said sector shaped discharge conduit and having a nose riding on said cam surface, said arm having sealing relation with said partition, said end plates having first and second sets of aligned seats, a pivot shaft seated in one set of aligned seats, said arm being journaled on said pivot shaft, said second set of seats providing a mounting for said pivot shaft when said end plates are reversed with respect to said body.

References Cited in the le of this patent UNITED STATES PATENTS 630,426 Thurber Aug. 8, 1899 678,338 Harger July 9, 1901 1,001,533 Kinney Aug. 22, 1911 1,242,692 Hibner Oct. 9, 1917 1,509,051 McBryde Sept. 16, 1924 1,698,815 Jaworowski Ian. 15, 1929 1,701,792 Nelson Feb. 12, 1929 1,903,606 Anderson Apr. 11, 1933 FOREIGN PATENTS 2,666 Great Britain Oct. 28, 1864 9,965 Great Britain Aug. 3, 1886 22,901 Netherlands Aug. 15, 1929 25,849 France Feb. 20, 1923 626,596 France May 16, 1927

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