EP0618365A1 - Volumetric machine with magnetic driving system - Google Patents

Abstract

Volumetric machine comprising a piston (1) located in a capsule (2). The piston has a hypertrochoidal profile as well as the internal recess (3) of the capsule. The piston has n axes of symmetry and the capsule n + 1. The piston performs a planetary movement inside the capsule around the axis Δc of the capsule. To obtain this planetary movement, the piston is on the one hand mounted, free to rotate, on a crank pin (4) off-axis with respect to a carrier shaft (7) coaxial with the axis Δc of the capsule, the shaft (7 ) being driven in rotation and on the other hand, the surface of the piston and the internal surface of the recess (3) of the capsule (2) are equipped with permanent magnets (12, 13) creating magnetic repulsive forces. <IMAGE>

Description

The present invention relates to a volumetric machine such as a vacuum pump or a compressor.

In particular, the invention applies to a vacuum pump of small flow, dry, non-polluting and capable of discharging the pumped gas at atmospheric pressure.

Roots, claw or twin screw pumps are known, but these machines have two shafts, synchronized in rotation by lubricated gears, so they are not entirely dry.

We also know spiral pumps called "Scroll pumps", but they are expensive due to the need and the difficulty of obtaining a very precise profile of the spirals, in addition, they do not allow condensate pumping .

Dry vane pumps are still known, but the vanes wear out quickly and cause a significant deterioration in performance, a short service life of the pump and pollution of the vacuum chamber by wear products. Membrane pumps are still known, but membranes have a short service life, or piston pumps, but they have poor performance and a high level of noise and vibration.

The invention relates to a new type of dry primary pump which overcomes largely the problems and defects of known dry primary pumps. It is a volumetric machine with planetary and geometric hypertrochoidal movement.

The machine comprises a cylindrical piston, a cylindrical capsule which surrounds it and a bent shaft whose axes are parallel to those of the cylinders defining the shape of the piston and of the capsule, in rotoid connection with this piston and this capsule.

In this machine, the cylinder defining the shape of the piston has an order of symmetry with respect to its axis equal to S _p , that of the capsule an order of equal symmetry to S _c ; S _p and S _c are chosen so that these values differ by one. In addition, the geometry of the piston and of the capsule is chosen so that there is direct correspondence between these elements.

One of the organs, capsule or piston has a P₁ profile which is identified with a curve uniformly distant from a closed hypertrochoid, presenting neither double point nor cusp, excluding hypertrochoids degenerated into hypotrochoids, epitrochoids or peritrochoids. The P₁ profile can also be at zero distance from such a hypertrochoid and therefore identify with it. The definition of hypertrochoids is specified in French patent 2 203 421. The other organ has a profile P₂ which is the envelope of P₁ in a relative planetary movement defined by two circles C₁ and C₂ of centers and respective radii (0₁, R₁) and (0₂, R₂), these circles C₁ and C₂ being respectively integral with the profiles P₁ and P₂ and rolling over one another without sliding by internal contact, | 0₁0₂ | specifying the distance E of the bent shaft.

• Les machines pour lesquelles P₁ est le profil du piston et P₂ est le profil de la capsule, celui-ci s'identifiant à l'enveloppe extérieure de P₁ dans le mouvement planétaire de P₁ relativement à P₂ pour lequel R₁ = S_pE et R₂ = S_cE = (S_p+1)E (famille I).
• Les machines pour lesquelles P₁ est le profil du piston et P₂ est le profil de la capsule, celui-ci s'identifiant à l'enveloppe extérieure de P₁ dans le mouvement planétaire de P₁ relativement à P₂ pour lequel R₁ = S_pE et R₂ = S_cE = (S_p-1)E avec S_p>1 (famille II).
• Les machines pour lesquelles P₁ est le profil de la capsule et P₂ est le profil du piston, celui-ci s'identifiant à l'enveloppe intérieure de P₁ dans le mouvement planétaire de P₁ relativement à P₂ pour lequel R₂ = S_pE et R₁ = S_cE = (S_p-1)E avec S_p>1 (famille III).
• Les machines pour lesquelles P₁ est le profil de la capsule et P₂ est le profil du piston, celui-ci s'identifiant à l'enveloppe intérieure de P₁ dans le mouvement planétaire de P₁ relativement à P₂ pour lequel R₂ = S_pE et R₁ = S_cE = (S_p+1)E (famille IV).

The machines meeting these characteristics can be grouped into four families according to the nature of the organ whose shape is defined by P₁ and according to the comparative values of the radii R₁ and R₂. A distinction should be made:

• The machines for which P₁ is the profile of the piston and P₂ is the profile of the capsule, this identifying with the outer envelope of P₁ in the planetary movement of P₁ relative to P₂ for which R₁ = S _p E and R₂ = S _c E = (S _p +1) E (family I).
• The machines for which P₁ is the profile of the piston and P₂ is the profile of the capsule, this identifying with the outer envelope of P₁ in the planetary movement of P₁ relative to P₂ for which R₁ = S _p E and R₂ = S _c E = (S _p -1) E with S _p > 1 (family II).
• The machines for which P₁ is the profile of the capsule and P₂ is the profile of the piston, the latter being identified with the inner envelope of P₁ in the planetary movement of P₁ relative to P₂ for which R₂ = S _p E and R₁ = S _c E = (S _p -1) E with S _p > 1 (family III).
• The machines for which P₁ is the profile of the capsule and P₂ is the profile of the piston, the latter being identified with the inner envelope of P₁ in the planetary movement of P₁ relative to P₂ for which R₂ = S _p E and R₁ = S _c E = (S _p +1) E (family IV).

Other machines can be derived from machines belonging to one of the four preceding families. Indeed, one can use a profile P₂ of which at least part is identified with the envelope of P₁ in its movement relative to P₂ and of which at least part is external to this envelope in the case of families I or II and is inside this envelope in the case of families III or IV, the different parts connecting to define a closed curve.

The profiles of the piston and of the capsule of these machines have the advantage of being able to be machined by very large series production machines (turning type), which reduces their cost price.

The planetary movement of such machines can be achieved, either by an internal gear with parallel axes, the wheels of which are respectively integral with the piston and the capsule and whose pitch radii are respectively equal to R₁ and R₂, or, if the geometry of the surfaces of the piston and the capsule which are in contact allows sufficient driving and if the fluid conveyed in the machine is sufficiently lubricating, then the gear can be eliminated and the relative planetary movement is directly imposed, during the rotary drive of the bent shaft, by the piston-capsule contact.

However, with such a system for generating planetary motion, the machine has the disadvantage of not be perfectly dry, because it requires the presence of a gear for the planetary movement which must therefore be lubricated to allow lasting operation, or else the presence of a pumped lubricating fluid if the gear is removed and if the movement planetary is directly obtained by direct contact between the piston and the capsule. In certain applications where the vacuum must be very clean, this is unacceptable.

The object of the present invention is to propose a machine as described above, but also making it possible to dispense with lubricant in the means used to generate the planetary movement of the machine.

The invention thus relates to a volumetric machine comprising a cylindrical piston of axis Δ _p , rotary and located in a cylindrical capsule of axis Δ _c , characterized in that said piston has, in a plane perpendicular to its axis Δ _p , a section of hypertrochoidal geometry having S _p axes of symmetry, said capsule defining a hollow volume whose section by a plane perpendicular to its axis Δ _c has a hypertrochoidal geometry having S _c axes of symmetry, S _p and S _c differentiating d '' a unit, the axes Δ _p and Δ _c , parallel, being separated by a distance E, said piston being mounted, free to rotate about its axis Δ _p , on a crank pin of axis Δ _p secured to a shaft of axis Δ _c supported by said capsule, said shaft being intended to be driven in rotation about its axis Δ _c by a motor means, the piston and the capsule delimiting between them at least three chambers and the capsule comprising at least one inlet suction and a discharge outlet, and in that the rotation of the piston in its planetary movement around the axis Δ _c of the capsule is created by magnetic repulsive forces by means of permanent magnets located, on the one hand on the surface, or in the vicinity of the surface, of the piston and on the other hand on the internal surface, or in the vicinity, of said capsule.

The invention also relates to a volumetric machine comprising a cylindrical piston of axis Δ _p , located in a cylindrical capsule of axis Δ _c , characterized in that said piston has, in a plane perpendicular to its axis Δ _p , a section of hypertrochoidal geometry having S _p axes of symmetry, said capsule defining a hollow volume whose section, by a plane perpendicular to its axis Δ _c , has a hypertrochoidal geometry having S _c axes of symmetry, S _p and S _c differentiating d '' a unit, the axes Δ _p and Δ _c , parallel, being separated by a distance E, and in that said capsule is mounted, free in rotation, around its axis Δ _c , on a crank pin of axis Δ _c secured to a shaft with axis Δ _p supported by bearings in a box enclosing said capsule, said box comprising a circular cylindrical housing with axis Δ _p of sufficient size to allow free rotation of the crank pin around the axis Δ _p of said tree and the movement p the axis of said capsule around the axis Δ _p , said capsule being open on a lateral face and said piston being connected, on the side of this face, without freedom of movement to said box, said shaft being intended to be driven in rotation around of its axis Δ _p by a motor means, the rotation of the capsule in its planetary movement around the axis Δ _p of the piston being created by magnetic forces of repulsion by means of permanent magnets located, on the one hand on the surface, or in the vicinity of the surface, of the piston and on the other hand on the internal surface, or in the vicinity, of said capsule, the piston and the capsule delimiting between them, at least three chambers, a lateral face of said box comprising at least one suction inlet and one discharge outlet in at least one said chamber.

The invention will now be described with reference to the accompanying drawing in which:

Figures 1, 2 and 3 show three possible profiles of piston and capsule according to the invention.

FIGS. 4 and 5 show diagrammatically in two views, a machine according to the invention with piston and capsule profiles in accordance with FIG. 1.

Figures 6 and 7 are two views similar to Figures 4 and 5 showing a variant.

Figures 8 and 9 are also two views similar to Figures 4 and 5 showing another variant.

FIG. 10 is a detail view showing a variant of FIGS. 8 and 9.

Figures 11 and 12 show, in more detail, a concrete example of machines according to the invention, still in the case of profiles according to Figure 1 and according to the variant of Figure 10. Figure 12 is a section along XII- XII of figure 11.

Figures 13 and 14 are another embodiment of a machine according to the invention, corresponding to the profiles of Figure 1, but in which the piston is fixed and where it is the capsule which performs a planetary movement around the piston axis.

   dans laquelle Z₁ désigne l'affixe du point générateur du profil P₁, chaque point étant précisé par une valeur particulière du paramètre cinématique k dont le domaine de variation est compris entre O et 2Sπ pour parcourir une seule fois la courbe, S est un nombre entier qui désigne l'ordre de symétrie de P₁ par rapport à l'origine du plan complexe et est choisi arbitrairement, E et R_m sont deux longueurs choisies librement à condition que la courbe correspondante ne présente ni point double, ni point de rebroussement, ce qui limite indirectement la valeur du rapport E/R_m The description which follows with reference to the figures listed above, relates to a group of particularly interesting machine profiles, belonging to the family I defined above and whose P₁ profile of the piston meets the following equation in the plan. complex: $$\text{Z₁ =}\frac{\text{1 + <figure-callout id="2" label="S" filenames="imgf0001.png,imgf0004.png" state="{{state}}">S</figure-callout>}}{\text{2}}\text{Ee}{}^{\text{i}\frac{\text{k}}{\text{s}}\text{(1-s)}}{\text{+ R}}_{\text{m}}\text{e}{}^{\text{i}\frac{\text{k}}{\text{s}}}\text{+}\frac{\text{1-<figure-callout id="2" label="S" filenames="imgf0001.png,imgf0004.png" state="{{state}}">S</figure-callout>}}{\text{2}}\text{Ee}{}^{\text{i}\frac{\text{k}}{\text{s}}\text{(1 + s)}}$$

in which Z₁ denotes the affix of the generating point of the profile P₁, each point being specified by a particular value of the kinematic parameter k whose range of variation is between O and 2Sπ to traverse the curve once, S is an integer which designates the order of symmetry of P₁ with respect to the origin of the complex plane and is chosen arbitrarily, E and R _m are two lengths chosen freely provided that the curve has neither double point nor cusp, which indirectly limits the value of the E / R ratio _m

One of the advantages of these machines is that when the P₁ profile of the piston meets the above equation, the P₂ profile of the capsule which is the envelope of P₁ in the relative planetary movement, also meets this equation.

Thus, Figure 1 shows, in section, by a plane perpendicular to the axes Δ _p and Δ _c , parallel, of the piston 1 and the capsule 2, the profile of a piston and a capsule.

These profiles P₁ for piston 1 and P₂ for capsule 2 correspond to the above equation with a piston 1 of order of symmetry S _p = 2 and a capsule 2 of order of symmetry S _c = 3. E is the distance separating the axes Δ _p and Δ _c .

FIG. 2 is a view similar to that of FIG. 1, but in the case where the piston has an order of symmetry S _p = 3 and the capsule 2 an order of symmetry S _c = 4.

FIG. 3 shows another example in which the piston 1 has an order of symmetry S _p = 4 and the capsule 2 an order of symmetry S _c = 3.

It should be noted that the number of axes of symmetry is equal to the order of symmetry.

These three figures correspond to piston and capsule profiles corresponding to the above equation.

In the machines of the following figures, given in nonlimiting examples of the invention, a piston with two axes of symmetry S _p = 2 and a capsule with three axes of symmetry was chosen: S _c = 3.

Referring now to Figures 4 and 5, we will describe a machine according to the invention. These figures are simplified and in particular do not include the suction and discharge which are shown only in Figures 11 to 14. These Figures 4 and 5, as well as Figures 6 to 9, simplified, allow to understand the operation of the machine according to the invention and in particular the production relative planetary movement: either of the piston, Figures 4 to 12, or of the capsule, Figures 13 and 14.

Thus, with reference to FIGS. 4 and 5, we see a volumetric machine according to the invention comprising a piston 1 whose profile P₁ corresponds to the equation given above, and having two axes of symmetry: S _p = 2. This piston is cylindrical with axis Δ _p and it is located in a cylindrical capsule 2 with axis Δ _c . This capsule 2 defines a hollow cylindrical volume 3 the section of which has a profile P₂ also corresponding to the above equation and having three axes of symmetry: S _c = 3. These profiles P₁ and P₂ are hypertrochoidal profiles. The axes Δ _p and Δ _c are parallel and distant by a value E.

The piston 1 is mounted to rotate freely, about its axis Δ _p on a crank pin 4 by means of bearings 5 and 6. The crank pin 4 is integrally connected to a shaft 7 of axis Δ _c supported by the capsule 2 by levels 8 and 9.

The shaft 7 is rotated about its axis Δ _c by a motor not shown. During this rotation, the axis Δ _p of the pin 4, that is to say the piston 1 is rotated about the axis Δ _c. The planetary movement of the piston 1 is caused by magnetic repulsion forces by means of permanent magnets located, on the one hand, on the surface of the piston 1 and on the other hand on the internal surface of the capsule 2.

In FIGS. 4 and 5, it is a question, both on the piston and on the capsule, of a plurality of magnets 10 and 11 respectively. In the case of these two Figures 4 and 5, these magnets are substantially polarized radially and in such a way that the poles of the same name are on the surface on the piston and the capsule so as to produce repulsion forces.

Thus, during the rotation of the shaft 7 around its axis Δ _c by a motor means, it is the magnetic forces of repulsion of the magnets which will cause the movement complementary rotation of the piston on itself completing its planetary movement around the axis Δ _c of the capsule.

Thus, thanks to these magnetic forces of repulsion, the piston is positioned relative to the capsule, and this without contact, no lubricant is therefore necessary. These magnetic forces guide the piston when it is moved by the crankpin and give it a rotational movement on itself, that is to say with respect to its axis Δ _p .

The piston 1 and the capsule 2 define between them three chambers A, B and C which, each, during the planetary movement of the piston, increases and decreases alternately. Thus, each room is equipped with a suction inlet and a discharge outlet fitted with valves. These inputs and outputs are only shown in Figures 11 to 14.

Figures 6 and 7 show an example in which the permanent magnets are axially polarized in the same direction on the piston and the capsule so as to obtain repulsion forces.

Figures 8 and 9 show another example in which the magnets 10 and 11 are replaced by magnetized strips 12 and 13 axially magnetized. These strips could also be magnetized radially. These magnetic strips 12 and 13 can be attached to the piston 1 and the capsule 2 and be glued to their surface.

It is also possible, as can be seen in FIG. 10, which is a partial sectional view showing a variant, not directly attaching the magnetic strips 12 and 13 to the surfaces of the piston and of the capsule, but proceeding by molding the magnetizable material containing a plastic binder. In this case, the magnetic strips 12 and 13 are not directly on the surface but, for the purposes of molding, in order to form formwork, slightly below this surface; there therefore remains a thin wall 14 and 15 respectively of the piston and of the capsule separating the two magnetic strips 12 and 13.

The use of magnetic strips improves the distribution and the homogeneity of the magnetic repulsion forces compared to the use of a plurality of magnets, as in FIGS. 4 to 7.

Figures 11 and 12 show a more concrete machine than the previous ones with suction and discharge and in the case where the magnetic forces are created by two magnetic strips 12 and 13 which have been cast in accordance with Figure 10.

In these figures, the piston 1 is mounted by the bearings 5 and 6 on the crank pin 4 linked to a plate 16 itself secured to the shaft 7 which supports the assembly, cantilevered, by the bearings 8 and 9 mounted in part 2A of the capsule 2 in three parts 2A, 2B and 2C. The piston 1 is held by a screw 17 and a washer 18.

The machine comprises three independent pumping chambers A, B and C, which each pulsate like a heart and which each comprise an inlet and outlet block 19 comprising a suction inlet 20, equipped with a valve 21, and a discharge outlet 22, fitted with a valve 23.

In this example, where two axially polarized magnetic strips are used, the magnetic repulsive forces which angularly position the piston relative to the capsule axially generate an unstable equilibrium point. The axial positioning of the piston is then carried out as follows: the two magnetic strips 12, 13 are offset very slightly, axially, one with respect to the other, with respect to their unstable equilibrium point, so to obtain an axial force in a determined direction which is then collected by the mounting of the prestressed bearings.

One advantage of the configuration of the profiles P₁ with an order of symmetry S _p = 2 and P₂ with an order of symmetry S _c = 3 is that the profile P₂ of the capsule is made up of three straight lines and three closing arcs. Another advantage is that this machine has three chambers independent work, theoretically zero dead volumes.

The piston 1, outside the magnetic strip 12 and the capsule 2 in its three parts 2A, 2B and 2C, outside the magnetic strip 13, are made of non-magnetic material, aluminum for example, so as not to disturb the magnetic fields which position the piston relative to the capsule.

Finally, FIGS. 13 and 14 show an example in which the piston 1 is fixed and where it is the capsule 2 which describes a planetary movement around the fixed axis Δ _{p of the} fixed piston 1. In this example, the forces of Magnetic repellents are created by a plurality of permanent magnets 10 and 11 radially polarized, as in Figures 4 and 5. Of course, one could use magnets axially polarized or two magnetic strips polarized axially or radially.

In this example, the capsule 2 is mounted to rotate freely around its axis Δ _c on the crank pin 4 linked to the shaft 7, the axis Δ _{p of which} is itself coaxial with the axis Δ _p of the fixed piston 1. The shaft 7 is supported by bearings 8 and 9, mounted in a fixed box in two parts 24A and 24B. The box 24A, 24B encloses the capsule 2 in a circular cylindrical housing 25 of axis Δ _p whose dimensions are sufficient to allow the planetary movement of the capsule 2 around the axis Δ _p of the piston with sufficient play to avoid the contact.

In this example, the capsule 2, housed in the box 24A-24B, is open on a lateral face, and it is the part 24B of the box which encloses the capsule 2, the piston 1 being fixed to this part 24B by screws, axes 26 and 27.

As in the previous examples, there are three independent chambers A, B and C which each have their suction and discharge. The same references designating the same bodies as in the previous figures.

Claims (6)

1 / Volumetric machine comprising a cylindrical piston (1) of axis Δ _p , rotary and located in a cylindrical capsule (2) of axis Δ _c , characterized in that said piston has, in a plane perpendicular to its axis Δ _p , a section of hypertrochoidal geometry having S _p axes of symmetry, said capsule defining a hollow volume (3) whose section, by a plane perpendicular to its axis Δ _c , has a hypertrochoidal geometry having S _c axes of symmetry, S _p and S _c being differentiated by a unit, the axes Δ _p and Δ _c , parallel, being separated by a distance E, said piston (1) being mounted, free to rotate about its axis Δ _p , on a crank pin (4 ) of axis Δ _p secured to a shaft (7) of axis Δ _c supported by said capsule (2), said shaft (7) being intended to be driven in rotation about its axis Δ _c by a drive means, the piston and the capsule delimiting between them at least three chambers (A, B, C) and the capsule comprising at least one inlet suction (20) and a discharge outlet (22), and in that the rotation of the piston (1) in its planetary movement around the axis Δ _c of the capsule (2) is created by magnetic forces ( 10, 11, 12, 13) repulsion by means of permanent magnets located, on the one hand on the surface, or in the vicinity of the surface, of the piston, and on the other hand on the internal surface, or in the vicinity , of said capsule. 2 / Volumetric machine comprising a cylindrical piston (1) of axis Δ _p , located in a cylindrical capsule (2) of axis Δ _c , characterized in that said piston has, in a plane perpendicular to its axis Δ _p , a section of hypertrochoidal geometry having S _p axes of symmetry, said capsule (2) defining a hollow volume (3) whose section, by a plane perpendicular to its axis Δ _c , has a hypertrochoidal geometry having S _c axes of symmetry, S _p and S _c being differentiated by a unit, the axes Δ _p and Δ _c , parallel, being separated by a distance E, and in that said capsule (2) is mounted, free in rotation, around its axis Δ _c , sure a pin (4) of axis Δ _c secured to a shaft (7) of axis Δ _p supported by bearings (8, 9) in a box (24A, 24B) enclosing said capsule, said box comprising a cylindrical housing (25) circular of axis Δ _p of sufficient size to allow the free rotation of the crank pin (4) around the axis Δ _{p of} said shaft (7) and the planetary movement of said capsule (2) around the axis Δ _p , said capsule (2) being open on a lateral face and said piston being connected, on the side of this face, without freedom of movement, to said box, said shaft (7) being intended to be driven in rotation about its axis Δ _p by a motor means, the rotation of the capsule in its planetary movement around the axis Δ _p of the piston (1) being created by magnetic forces of repulsion by means of permanent magnets (10, 11) located, d on the one hand on the surface, or in the vicinity of the surface, of the piston, and on the other hand on the internal surface, or in the vicinity, said capsule, the piston and the capsule delimiting between them, at least three chambers (A, B, C), a lateral face (24B) of said box comprising at least one suction inlet (20) and a discharge outlet ( 22) communicating in at least one said room. 3 / Volumetric machine according to one of claims 1 or 2, characterized in that said permanent magnets are axially polarized. 4 / Volumetric machine according to one of claims 1 or 2, characterized in that said permanent magnets are radially polarized. 5 / volumetric machine according to one of claims 1 to 4, characterized in that said permanent magnets comprise a plurality of magnets (10) on the piston and a plurality of magnets (11) on the internal surface of the capsule. 6 / Volumetric machine according to one of claims 1 to 4, characterized in that said piston carries a magnetic strip (12) and in that said capsule carries a magnetic strip (13).

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