US 3473728 A
Abstract available in
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Description (OCR text may contain errors)
Oct. 21, 1969 P. VULLIEZ 3,473,728
VOLUHETRIC APPARATUS SUCH AS A. VACUUM PUMP OR THE' LIKE, HAVING AN EXACT CIRCULAR TRANSLATION CYCLE Filed on. 2, 1967 4- Sheets-Sheet 1 FIG] .Oct. 21, 1969 P VULLIEZ 3,473,728
VOLUMETRIC APPARATUS SUCH AS A VACUUM 'PUMR OR THE" LIKE, HAVING AN EXACT CIRCULAR TRANSLATION CYCLE Filed Oct. 2, 1967 v4 Sheets-Sheet 2 Arr/ 4 Sheets-Sheet 5 Awe/Wag 7 firrys.
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Oct. 21, 1969 VOLUMETRIC APPARATUS SUCH As A VACUUM PUMP on THE LIKE, HAVING AN EXACT CIRCULAR TRANSLATION CYCLE Filed 001"- 2, 1967 3 Z mm 4???? n 7,? .w 1 L8 9 a M E g..:\\ 7 A .1. A 2 0 r l A- m 1 I Cl A A 3 2 Oct. 21, p; U
VOLUMETRICAPPARAIUS SUCH AS ACUUM PUMPI 0R THEr LIKE, HAVING AN EXACT CIRCULAR TRANSLATION CYCLE v Filed Oct. 2, 1967 4 Sheets-Sheet 4 I 1 /701, V0.4 4 /4-z a, N r'JM 3,473,728 VQLUMETRIC APPARATUS SUCH AS A VACUUM PUMP OR THE LIKE, HAVING AN EXACT CIR- CUlLAR TRANSLATION CYCLE Paul Vulliez, 13 Rue de la Brasserie, 27 Pont-Audemer, Eure, France Filed st. 2, 1967, Ser. No. 672,332 Claims priority, application France, Oct. 6, 1966, 78,983; Sept. 29, 1967, 122,797 Int. Ci. FtMc 17/02 U5. Cl. 23[i--146 Claims ABSTRACT OF THE DISCLOSURE A rotary machine such as a vacuum pump has at least one annular or spiral working member mounted for circular movement on at least three spaced crankshafts so that the points of closest approach of the working member sweep the walls of the working chamber but are at all times spaced from the walls of the Working chamber by a small constant clearance. Fluidtight bellows seal between the machine body and the working member about the crankshafts, and the side walls are unlubricated. The combination of the small clearance plus the lack of lubrication plus the bellows seal permits the total elimination of lubricant from the working chamber.
The present invention has for its object a volumetric cycle apparatus such as a vacuum pump or the like, the fluid tightness of which by bellows is complete with respect to the ambient, and in which the working parts move with respect to each other following an exact and generated circular translation cycle, without any friction contact or lubrication.
It is known that in order to isolate completely from the ambient by means of a metallic bellows or diaphragm a movin member having a rotating cycle, mounted inside a fixed casing, a very effective means is to create this rotating cycle by following an exact and generated circular translation, the fluid'tight sealing member being then associated on the one hand with the moving member and on the other hand with the fixed casing. By means of the exact and generated circular translation movement, the moving member describes a rotating cycle having an absolutely constant orientation, while the fluid-tight member which is associated therewith is thus protected against any functional or accidental torsion force.
In an apparatus of this kind, in addition to the protection of the fluid-tight sealing members against the effects of torsion, it is absolutely essential to maintain connited States Patent 0 stant the very small radial or lateral clearance between i the working members of the pump, so as to prevent any accidental contact and to obtain the best pumping performance. To this end, and taking into account their geometrical shapes and the reactions resulting from the work of pumping, these working parts must therefore move with respect to each other with the minimum radial and lateral play.
The solution which has been advantageously chosen in order to obtain this result is an exact and generated circular translation of the moving parts, effected by three synchronized eccentrics, the synchronization being obtained, either by the moving part itself or by a transfer member coupled to the moving part; in both cases, one of the eccentric shafts is a driving shaft.
With this construction comprising three synchronized eccentrics, the moving parts are maintained laterally in clearly defined planes, and radially the circular translation motion can be obtained with the maximum mechanical precision.
The rotary machine of the present invention comprises 3,473,728 Patented Oct. 21, 1969 "Ice a fixed body having an inlet and an outlet for a working fluid and a passageway for the working fluid extending between said inlet and outlet and disposed within said body, movable means for elfecting displacement of the working fluid from said inlet to said outlet, a mechanism by which said movable means is connected with and supported relative to said body, said mechanism comprising at least three crankshafts of equal eccentricity and synchronously coupled to one another for controlling circular-translatory movement of said movable means relative to said body during operation of the machine, means for driving said movable means to effect said movement, said passageway having walls that are shaped to match the configuration of the envelope of the space swept by said movable means during movement thereof, said movable means and the most adjacent walls of said passageway being spaced by a small constant clearance in any position of said movable means, and fluid-tight bellows means having ends fixed respectively to said movable means and to said body for isolating said passageway from the atmosphere, and permitting its operation Without any friction contact between the parts that are exposed to the interior of the passageway and therefore without any lubrication.
In one form of construction with a spiral ring, there may be employed two identical spiral rings, each with a side plate, both moving and set at from each other, one moving inside the other so as to constitute the whole of the active portion of the pump. This solution makes it possible to obtain, by construction, a perfect balance, while a double pumping volume is generated for the same lateral displacement of the fluid-tight bellows.
The coupling means between the moving member and the fixed body or between the two moving members, comprise, for each moving member, at least three cranks having the same orientation and equal eccentricity and synchronized by the moving member itself, at least one of the said cranks being a driving crank.
When the moving member in the form of an open ring is of suitable dimensions, it may be made hollow and the driving cranks are then mounted traversing inside the ring, and bellows means or fluid-tight membranes in the form of sleeves of any material such as metal or plastic, are arranged in the hollow ring and surround the cranks while having one of their extremities coupled to the fixed body and the other extremity to the ring. This construction is balanced from the point of view of axial reaction resulting from the pressure.
In the other cases in which thin moving parts are employed, that is to say having reduced thickness, the mounting of these moving parts is effected on an end-plate, which receives, following a lateral mounting, the action of the .coupling means with the body for giving it an exact circular movement of translation. 7 Y
This construction, obtainable with three bellows, can also be obtained with a single central bellows, inside which is located the rigid coupling member which fixes the moving member to the movement transfer member (see FIG. 9).
It will of coure be understood that these various forms of construction may be utilized in combination with each other.
According to the invention, the shape of the moving parts and of their curved casings is designed so as to prevent the back flow of the delivery fluid towards the suction, and also the complete emptying of the pumping chamber at the end of the delivery period.
While maintaining the above advantages, the invention also relates to a construction of a multi-stage pump for the application of vacuum or the compression 0 gaseous fluids.
In this connection, note should be made of the remarkable properties obtained with the construction having two identical spiral rings, whether they are both moving or whether one is fixed and the other moving. Starting from the center of the spiral rings and limiting their angular development to 360, it is found that at the end of the suction stage there is imprisoned a volume V which is wholly and gradually expelled after a single cycle of circular translation, the separation between the exhaust and the suction being constantly maintained by progressive and continuous juxtaposition at a distance equal to the small constant clearance of the spiral moving members.
Again starting from the center of the spiral rings and with an angular development of the volutes equal to twice 360, the volume V1 imprisoned at the suction is brought at the end of a cycle of circular translation and in a progressive manner, to the volume V having a value less than V1. It is then transferred during the course of a second cycle of circular translation to the first portion of 360 of angular development of the spiral ring and is completely expelled. The operation of a spiral ring of twice 360 of angular development becomes that of a pump with two stages. The continuous separation between the suction and delivery is constantly and doubly ensured by two continuous contacts on each spiral.
In this way it is possible to multiply the number of stages of the pump, each stage ensuring an independent progressive compression before reaching the volume V of suction of the last stage.
The objects, characteristic features and advantages of the invention will further be brought out in the description which follows below of forms of construction selected by way of examples, reference being made to the accompanying drawings, in which:
FIG. 1 is a diagrammatic view in a direction parallel to the axis of a single-stage pump having a thick moving member traversed by the three driving cranks and three fluid-tight bellows, and with a static and dynamic balancing mass.
FIG. 2 is a view of this apparatus in cross-section, taken along the broken line II-II of FIG. 1.
FIG. 3 is a diagrammatic view showing the operation of spiral rings in a single stage;
FIGS. 4 and 5 are diagrammatic views showing the operation of spiral rings having two stages.
FIG. 6 is a diagrammatic view in a'direction parallel to the axis of a two-stage pump with two moving spiral rings and a shelf-balanced assembly.
FIG. 7 is a view of this apparatus in cross-section taken along the broken line VIIVII of FIG. 6.
FIG. 8 is a diagrammatic view perpendicular to the axis of a two-stage pump with one fixed spiral ring and the other ring moving, the assembly being effected laterally with a single central bellows and balancing by additional weight.
FIG. 9 is a view of this apparatus in cross-section taken along the axial line 1XD( of FIG. 8.
Reference will first be made to FIGS. 1 and 2 which relate, by way of non-limitative example, to an application of the invention to a volumetric vacuum pump of absolutely fluid-tight construction and having an internal operation with low friction and without lubrication, all the coupling members comprising bearings being strictly isolated from the pumping chamber by metallic bellows means.
As shown in FIGS. 1 and 2, the pump comprises a fixed body 10 made up of a cylindrical outer wall 11, a cylindrical inner wall 12 concentric with that preceding, and two lateral closure walls 13 and 14. The axis A of the cylindrical walls 11 and 12 of the body 10 is represented b a point in FIG. 1 and by a chain-dotted The pump also comprises a moving member 16 engaged in the cavity 15, which is constituted by a circular ring open at 17 and made hollow with a section along a radial plane advantageously in the general shape or a caisson so as to house freely the cranks 18 which, in this non-limitative assembly, constitute the coupling means with the fixed body in order to generate an exact circular translation travel.
The extremity of the ring on the suction side is out along a radial plane extended by a semi-cylindrical part 19 which ensures contact with the fixed part 12 so as to prevent any intercommunication between the delivery and the suction when the moving member is in contact with the outer wall 11, according to the instantaneous position of FIG. 1. On the delivery side, the moving member is terminated by a cylindrical portion, the envelope curve of which is constituted by the partition 30. The space 17 is in communication with the suction 27.
The coupling means between the moving member 16 and the body 10 comprise three eccentric means arranged at 120 and each consisting of a crank 18. This latter has a portion 20 mounted for rotation on the body 10 and held by the barrel 21 by means of bearings and abutments. The portion 18, eccentric by the amount E is also maintained by a guiding barrel 22 rigidly fixed to the moving member 16. By means of this mounting, the elfects of bending on the crank-shafts 18 are reduced to the maximum extent. Locking systems for the thrustbearings 36 ensure the distribution of the working play between the lateral faces of the moving member and the body. The amount of eccentricity E shown in FIG. I defines the exact circular radius of translation of the moving member 16.
In this construction, the drive is effected from the central shaft 26, on which is keyed the balancing weight 25. A coupling member 24 ensures the rigid fixing of the crank-shafts 18 with the central shaft 26 by means of eccetric arms. It should be noted that this fixing is necessitated by the presence of the balancing weight 25, the crank-shafts 18 being already synchronized with each other by the moving member 16.
Fluid-tight bellows 23, in the form of sleeves, are also housed inside the ring 16 and surround the cranks 18. Each bellows 23 is rigidly fixed at one extremity 28 to the barrel 21 fixed to the body 10, and by the other extremity 29 to the barrel 22 fixed to the moving member 16 Each bellows 23 is free from any torsion force by means of the mounting of the three cranks 18 which generate an exact circular translation movement of the moving member, and has only a slight undulating movement which only produces negligible fatigue. The bellows may be made of any suitable material, metallic, plastic or the like, and provide completely fluid-tight sealing.
It will be appreciated that the exact circular translation movement generated by the member 16 is efiected by a plurality (a minimum of three and non-aligned) of cranks 18 having an eccentricity E and synchronized line in FIG. 2. The walls 11 and 12 form between them by the member 16 itself. Without the static and dynamic balancing weight 25, the fixing member 24 could be dispensed with, the pump being then actuated by the single drive of one of the shafts 18.
As in the case of all the remaining figures, the direction of running corresponds to a rotation of the eccentrics in the direction of the arrows 30.
The wall 11 comprises an orifice 27 for admission of fluid, while the face 14 may comprise two delivery valves 31 and 32 communicating respectively with the radially inner and radially outer parts of the cavity.
Considering FIG. 1, it can be seen that for a working cycle, the volume generated by the action of the internal and external cylindrical walls of the ring 16 with their envelope curves is theoretically equal to the difference in volume between the cavity 15 and the ring 16.
In the instantaneous position of the moving member such as shown in FIG. 1, it is clearly seen that on the delivery side, the contact is never interrupted between the moving member 16 and its envelope curves of the cavity 15. In this same instantaneous position, the fluid compressed outside the moving member 16 partly escapes through the valve 32, the non-expelled volume then passing in the chamber on the inner face side of the moving member 16 and is then totally expelled through the valve 31, the separation between the suction and delivery being constantly maintained, in particularly by means of the part 19.
It will be noted that the parasitic volume located in the interior of the ring and the exterior of the metal bellows can readily be put into communication with the suction alone; it is then subjected to the pressure of the chamber to be pumped.
Reference will now be made to diagrammatic FIGS. 3, 4 and 5 which show the course of the pumping cycles with a moving member in the form of a spiral ring, moving in exact circular translation movement in the interior of a fixed portion constituted by an envelope curve having an identical spiral outline.
According to FIG. 3, there can be seen a moving member 16, the angular development of which is 360 and the envelope curve 12 of which is fixed to the body and has a spiral outline identical with the starting point located at B.
The outline of the spiral moving member is advantageously formed by semi-cylindrical portions having their centers at M1 and M2, the centers of the fixed spiral being at M3 and M4. The circular translation movement of the moving member is effected by three eccentrics rotating in the direction of the arrows 30 with a radius of eccentricity equal to E.
The suction at 27 is extended between the exterior of the moving ring 16 and the wall of the body 10 up to the point B at which the active pumping starts. The delivery is effected at the center through the orifice 31 (not shown in FIGS. 4 and 5 for the sake of clearness of the drawings).
According to the instantaneous position of the moving member 16 in FIG. 3, it is seen that the suction is taking place while the delivery into the central portion of the volume imprisoned during the preceding cycle is also in course.
Referring to FIG. 4, it can be seen that for the portion of spiral ring of 360 in angular development, as shown in FIG. 3, the suction is completed when the contacts B1 and B2 are established, the two volumes V imprisoned during the previous cycle then being completely expelled for a ring of this kind, a single cycle of circular translation makes it possible to isolate two volumes V, which are then joined together and progressively compressed, so as to be completely expelled through the orifice 31. The separation between the two suction zones 27 and the delivery 31 is constantly ensured by the continuous displacement of the contacts B1 and B2 (see FIG. 5) which return to the position of FIG. 4 when the end of delivery contact B3 is established.
The operation of a spiral ring with an angular development of 360 corresponds to that of a vacuum pump having a single stage.
Consider again the assembly of FIG. 4, in which the moving member 16 has an angular development of twice 360. In the instantaneous position of this figure, it is seen that by the contacts B4 and B5 two volumes V1 have just been isolated at the end of the suction period. At the end of a first cycle of circular translation, the two volumes V1 are progressively compressed to a value V less than V1. This progressive compression, of which an intermediate position is shown in FIG. 5, is possible by the continuous displacement of the separation contacts (to within the clearance) bringing B4 to B1 and B5 to B2. At the end of a second cycle of circular translation, the two volumes V are first re-united and then progressively compressed and expelled through the orifice 31, as previously explained.
In this connection, FIG. 5 shows an intermediate position in which, with respect to FIG. 4, the moving member 16 has moved through a portion of a cycle corresponding to a rotation in the direction 30 through an angle a of the driving eccentrics. In this position, the next following suction at 27 is in course, the two volumes V1 of FIG. 4 having become V2, and the two volumes V of the same FIG. 4 being joined together at V3, following a position of the moving member 16 preceding the total delivery. It can be seen that the barriers B1, B2, B4 and B5, while occupying new positions, still effect the separation between the volumes of each of the stages and also between the volumes V2 and the suction.
It is thus found that the operation of a spiral ring of twice 360 in angular development is the same as that of a vacuum pump with two stages. Each stage effects its own compression in a progressive manner by the fact of the continuous separation (to within the working clearance) between the suction and the first compressed volume on the one hand and, on the other hand, between this first volume and the second volume expelled following the cycle of FIG. 3.
The full advantage of this construction will be understood, which permits, especially in the application to vacuum pumps, a multiplication of the number of stages with a single apparatus, in which the working parts of the pump are either one fixed and the other moving or both moving and set at 180 from each other.
FIGS. 6 and 7 give a non-limitative example of a pump in which the working portion is constituted by two identical moving members moving one inside the other so as to form a two-stage assembly which is statically and dynamically self-balanced.
The two identical moving members 16a and 16b having an angular development of twice 360, are each provided with a lateral end-plate at 35a and 35b respectively. The moving member 16b is coupled to its transfer member 33b by means of three rigid couplings 22b passing into the interior of the bellows 23. These bellows 23 are fast with the fixed body 10 at 28 and with the end-plate 35b at 29. The transfer member 33b is driven in exact circular translation movement by the rotation of the three cranks 18b associated with three shafts 20 centered in the body 10 by hearing means located at from each other, as shown in FIG. 6.
The coupling means between the moving member 16a and its transfer member 33a, not shown on the drawings, are mounted in exactly the same manner and symmetrically with those of the moving member 16b. The transfer member 33a of the moving member 16a is driven in an exact circular translation movement by the action of the three eccentrics 18a also belonging to the shafts 20, these eccentrics 18a being each fixed at with respect to each of the eccentrics 18b.
The adjustment of the lateral clearance between a moving member and the end-plate of the other moving member is effected by abutment means 36.
The two working portions 16a and 16b being moving, the delivery 31 is coupled to the body 10 by a bellows means or diaphragm 34.
The construction with the working part of the pump formed by two spiral moving rings, in addition to the facility of static and dynamic balancing, enables the amplitude of displacement of the two spiral rings, one with respect to the other, to be doubled for the same lateral displacement of the bellows 23, this being in comparison with the solution having one fixed spiral ring while the other ring is moving.
The construction can of course be envisaged with the moving member 16a secured to the fixed body 10, the moving member 16b being simply driven by three cranks, following a construction comparable with that of FIG. 2. This construction necessitates the addition of static and dynamic balancing weights.
FIGS. 8 and 9 relate to a pump with a moving member 16 having a spiral ring of twice 360 in angular develop ment, moving in the interior of a fixed portion constituted by an identical spiral ring 12 belonging to the body 10.
The spiral moving ring 16 comprises an end-plate 35 rigidly fixed to the transfer member 33 by the rigid coupling member 22 located inside the single bellows 23.
The transfer member 33 is given an exact circular translation movement by the action of the three cranks 18 belonging to the three shafts 2i) centered on the body by bearings arranged peripherally at 120 from each other. Abutment means 36 permit the adjustment of the lateral clearance between the moving member 16 and the corresponding working parts of the body 10.
The suction is effected along 27, and the delivery is located at 31 with a valve.
The dynamic and static balancing is eflected by means of an additional weight 25 put into circular translation movement by the three eccentrics 37 keyed on the shaft 20 with 180 displacement with respect to the cranks 18.
This construction is preferably employed in the case of pumps of small output.
As in the case of FIGS. 6 and 7, the exact circular translation movement is generated by the rotation of one of the shafts 20.
What I claim is:
1. A rotary machine comprising a fixed body having an inlet and an outlet for a working fluid and a passageway for the working fluid extending between said inlet and outlet and disposed within said body, movable means for effecting displacement of the working fluid from said inlet to said outlet, a mechanism by which said movable means is connected with and supported relative to said body, said mechanism comprising at least three crankshafts of equal eccentricity and synchronously coupled to one another for controlling circular-translatory movement of said movable means relative to said body during operation of the machine, means for driving said movable means to eflect said movement, said passageway having walls that are shaped to match the configuration of the envelope of the space swept by said movable means during movement thereof, said movable means and the most adjacent walls of said passageway being spaced by a small constant clearance in any position of said movable means, and fluidtight bellows means having ends fixed respectively to said movable means and to said body for isolating said passageway from the atmosphere.
2. A rotary machine as claimed in claim 1, said movable means being of split-ring shape, said passageway walls including cylindrical walls and a partition wall extending through the split of the ring, said inlet and said outlet being disposed on opposite sides of said partition wall.
3. A rotary machine as claimed in claim 1, said movable means being in the form of a hollow box, said crank- 8 shaft extending at least in part within said box, said bellows means comprising a plurality of sleeve-shaped bellows each of which surrounds a crankshaft.
4. A rotary machine as claimed in claim 1, said movable means comprising a first disc having a first spiralshaped projection on one side thereof, said body comprising a second disc opposite to said first disc and having a second spiral-shaped projection on one side thereof interleaved with said first projection, said first and second projections having the same angular extent, and connecting stub means rigid with one of said discs and extending on the side thereof which is opposite to the projection thereon, said bellows means surrounding said connecting stub means.
5. A rotary machine as claimed in claim 4, in the form of a single-stage vacuum pump, said angular extent being 360.
6. A rotary machine as claimed in claim 4, in the form of a plural-stage vacuum pump, said angular extent being at least twice 360.
7. A rotary machine as claimed in claim 1, said outlet being so constructed and arranged as to be alternately exposed by and completely swept by said movable means whereby said passageway has no residual volume adjacent said outlet.
8. A rotary machine as claimed in claim 1, said movable means comprising a first member and a second member, said first and second members being of spiral shape. said mechanism moving said first and second members relative to each other with equal eccentricities and equal rotational speeds but out of phase with each other.
9. A rotary machine as claimed in claim 8, said crankshafts being double crankshafts having eccentric portions one to drive said first member and the other to drive said second member.
10. A rotary machine as claimed in claim 1, said movable means being in the form of a spiral that coacts with a spiral rigid with said body.
References Cited UNITED STATES PATENTS 1,041,721 10/1912 Ball 91--56 1,376,291 4/1921 Rolkerr 230-l46 3,011,694 12/1961 Audemar 23Gl46 3,161,141 12/1964 Refson 103l32 3,194,167 7/1965 Wilson l03132 FOREIGN PATENTS 486,192 5/1938 Great Britain.
DONLEY J. STOCKING, Primary Examiner W. J. GOODLIN, Assistant Examiner