POSITION PUMP

Description

DOMAINE DE L'INVENTION

[0001] The invention relates to a volumetric lobe pump.

[0002] For the purposes of the invention, a "volumetric pump" is a pump in which the pumping of a fluid results from the variation of a volume occupied by the fluid inside the pump, called the pumping volume. "Volumetric lobe pumps" include pumps for which several lobes make it possible to define this pumping volume inside the pump.

[0003] The invention can be used to pump a liquid or pasty fluid incorporating solid elements. The invention shows a particularly advantageous application for pumping grape harvest products for winemaking. ETAT DE LA TECHNIQUE

[0004] The operation of a volumetric lobe pump is described in particular in documents FR 2 645 915, FR 2 622 935 and FR 3 053 743.

[0005] Positive displacement lobe pumps consist of a stator with a fluid inlet and a fluid outlet, also called an exhaust stack. The stator has an internal cylindrical chamber forming a stator volume in hydraulic communication with the fluid inlet and the exhaust stack. To pump fluid from the fluid inlet to the exhaust stack, a lobe rotor is arranged inside the stator volume.

[0006] Each lobe typically has a cylindrical shape of ovoid section with a radial end intended to scrape the internal wall of the internal cylindrical chamber of the stator. Thus, during the movements of the rotor lobes between the fluid inlet and the extraction chimney, the volume between two lobes is first positioned opposite the fluid inlet so as to inject the fluids into the stator volume, for example by means of an Archimedes screw.

[0007] The rotational movement of the rotor then moves the volume between two lobes facing the internal wall of the stator, thus delimiting the pumping volume. The volume between two lobes is continuously moved until it reaches the extraction chimney. In this position, a valve rubs against the lobe located opposite the extraction chimney so that the rotational movement of the rotor moves the fluids from the pumping volume into the extraction chimney.

[0008] However, when the pumping volume is put into hydraulic communication with the extraction chimney, a counter pressure occurs in the pumping volume since the piping fixed to the extraction chimney is classically subjected to a pressure much greater than that imposed in the pumping volume by the rotation of the rotor.

[0009] For example, when pumping grape harvest products, the pressure in the piping connected to the extraction chimney is approximately two bars and a very high back pressure is observed when a rotor lobe passes from a state where it rubs against the internal wall of the stator to a state where its radial end is located opposite the extraction chimney. The abrupt transition between these two states is visible at the piping. Indeed, with translucent piping, the grape harvest products can be seen moving forward in jerks in the piping. Typically, in the piping, the grape harvest products move forward for a period of approximately one second and then, for a few milliseconds, the grape harvest products stop. They then move back in the piping when the pumping volume is put into hydraulic communication with the extraction chimney due to the pressure relief of the piping in the stator volume.After this relaxation, the harvested products move forward again under the pressure applied by the rotation of the rotor.

[0010] These pressure relief phases in the pipework are so intense that it is almost always necessary to use an anti-pulsation bell or anti-water hammer bell placed on the extraction chimney to avoid damaging the grape harvest products during pumping. Even with this anti-pulsation bell, these pressure relief phases are very noisy and the grape harvest products are still at risk of being damaged during pumping.

[0011] The technical problem of the invention is therefore to obtain a volumetric lobe pump allowing efficient fluid transfer by reducing these expansion phases at the extraction chimney. EXPOSE DE L'INVENTION

[0012] To meet this technique, the invention proposes to use a lobe rotor with chevron-shaped lobes so that the hydraulic communication of the pumping volume with the extraction chimney is progressive. To do this, the valve also has a chevron shape complementary to that of the lobes so as to obtain the guidance of the fluids from the stator volume to the extraction chimney.

[0013] For the purposes of the invention, a “chevron shape” corresponds to a shape in which two segments intersect at an angle between 120 and 170 degrees.

[0014] For this purpose, the invention relates to a volumetric lobe pump comprising: a stator comprising an inner wall defining a stator volume; the stator having a fluid inlet and an extraction chimney; the fluid inlet and the extraction chimney being in hydraulic communication with the stator volume; a rotor, rotatable inside the stator volume, comprising at least two lobes; each lobe having a radial end intended to scrape the inner wall of the stator so as to obtain a pumping volume between two consecutive lobes when they are positioned between the fluid inlet and the extraction chimney; a valve mounted at the extraction chimney so as to cooperate with the lobes to force the fluids, present in the pumping volume, to be displaced into the extraction chimney during rotation of the rotor; and valve return means configured to move the valve against the lobes when the lobes are displaced at the extraction chimney.

[0015] The invention is characterized in that the radial end of each lobe has the shape of at least one chevron so that the hydraulic communication of the pumping volume with the extraction chimney is progressive, the valve having the shape of at least one chevron complementary to that of the lobes so as to guarantee the hermeticity of the hydraulic communication between the pumping volume and the extraction chimney.

[0016] Thus, the shape of the radial end of each lobe makes it possible to obtain a progressiveness in the hydraulic communication between the stator volume and the pressure contained in the piping connected to the extraction chimney. Indeed, in the state of the art as described in documents FR 2°645°915, FR 2°622°935 and FR 3°053 743, the radial end of the lobes is straight as is the opening of the extraction chimney in the stator volume. It follows that the passage of the radial end of a lobe at the edge of the opening of the extraction chimney in the stator volume causes a very rapid relaxation of the pressure of the piping in the stator volume.

[0017] In the invention, the straight edge of the extraction chimney opening cooperates with a chevron-shaped edge of the radial end of each lobe so that the pressure relief of the pipe is much slower.

[0018] Thus, the invention makes it possible to obtain progressive relaxation as the rotor moves, thereby limiting the compression and expansion phases that the fluid undergoes during pumping.

[0019] Furthermore, by limiting the compression and expansion phases that the fluid undergoes during pumping, it is possible to avoid using an anti-pulsation bell on the extraction chimney, to limit noise, and to improve the pumping speed.

[0020] Furthermore, the shape of the stator is not necessarily modified so that it is possible, in one embodiment, to transform an existing pump by simply replacing the rotor and the valve. When the invention is implemented to pump grape harvest products, limiting the stresses undergone by the grape harvest products during pumping makes it possible to protect the quality of the harvest, that is to say to guarantee the integrity of the harvest as much as possible.

[0021] The complexity of implementing the invention lies in the specific shape of the rotor lobes and the associated valve. More particularly, the rotor is movable on an axis and it can have a variable length inside the stator volume depending on the desired pumping volume. To ensure the progressiveness of the hydraulic communication of the pumping volume with the extraction chimney, it is possible to use one or more chevrons at the radial end of the lobes.

[0022] According to an embodiment with a chevron, the rotor has a first circular propeller with a left-hand pitch fixed on a second circular propeller with a right-hand pitch.

[0023] For the purposes of the invention, a circular propeller is inscribed in a cylinder of revolution so that the radial end of the propeller, i.e. that of the rotor, can cooperate with the cylindrical internal wall of the stator to form a substantially hermetic cavity.

[0024] Furthermore, the rotor may have two, three or four lobes without changing the invention.

[0025] With a two-lobe rotor, the radial end of each lobe forming a single chevron, the rotor cross-section is ovoid and the rotor is relatively simple to design and manufacture. For example, the rotor can be manufactured by manufacturing the two propeller parts independently and fixing them after manufacture.

[0026] The rotor can also be cast in one piece by casting a stainless steel core using a lost-wax casting technique. This stainless steel core can then be covered with a food-grade elastomer to accommodate the friction of the valve. In addition, the stainless steel core covered with a food-grade elastomer can be sandwiched between two stainless steel flanges, also made using a lost-wax casting technique. The two flanges are preferably made at the same time as the core.

[0027] Alternatively, three-dimensional printing can be performed to achieve this complex shape.

[0028] This three-dimensional impression is preferred when each lobe has several chevrons. For example, with two chevrons, the rotor may have a first circular propeller with a left-hand pitch fixed to a second circular propeller with a right-hand pitch, itself fixed to a third circular propeller with a left-hand pitch, itself fixed to a fourth circular propeller with a right-hand pitch. This embodiment makes it possible to obtain good progressiveness for the hydraulic communication of the pumping volume with the extraction chimney, particularly for large volume pumps.

[0029] As for the rotor axis, it can be fixed or mobile, for example by forming an epicyclic train. The valve return means can also correspond to any known means, such as springs.

[0030] Preferably, to limit the space requirement and facilitate maintenance operations, the valve return means correspond to magnetic means.

[0031] According to one embodiment, the valve return means comprise: a first annular magnet support, the first support being fixed relative to the stator; and a second annular magnet support, the second support being fixed relative to the valve; the two supports being coaxial with the axis of rotation of the valve and positioned opposite each other; the poles of the magnets of the first support being offset relative to the poles of the magnets of the second support so that the magnetic force of the magnets tends to move the valve against the lobes.

[0032] To improve the travel of these return means, they preferably comprise a third annular magnet support, the third support being free to rotate between the first support and the second support, the poles of the magnets of the third support being offset between the poles of the magnets of the first support and the magnets of the second support.

[0033] According to one embodiment, the return means of the valve comprise removable fixing means of the supports making it possible to open the return means in order to modify the magnetic power or the number of magnets when it is desired to modify the return force of the return means. BREVE DESCRIPTION DES FIGURES

[0034] The invention will be better understood on reading the following description, given solely by way of example, and drawn up in relation to the appended drawings, in which identical references designate identical or similar elements, and in which: [ Fig 1 ] there figure 1 is a sectional view of a volumetric lobe pump according to one embodiment of the invention; [ Fig 2 ] there figure 2 is a perspective and sectional view of the pump of the figure 1 ; [ Fig 3 ] there figure 3 is a perspective view from a first angle of the connection between the valve and the rotor of the pump of the figure 1 ; [ Fig 4 ] there figure 4 is a perspective view from a second angle of the connection between the valve and the rotor of the pump of the figure 1 ; [ Fig 5 ] there figure 5 is a perspective view from a third angle of the connection between the valve and the rotor of the pump of the figure 1 ; [ Fig 6 ] there figure 6 is a perspective view from a fourth angle of the connection between the valve and the rotor of the pump of the figure 1 ; [ Fig 7 ] there figure 7 is a top view of the pump rotor of the figure 1 ; [ Fig 8 ] there figure 8 is a top view of a rotor according to another embodiment; [ Fig 9 ] there figure 9 is a representation of the projection of the rotor displacements of the figure 1 on the inner wall of the stator; and [ Fig 10 ] there figure 10 is an exploded perspective view of the recall means of the figure 1 . DESCRIPTION DETAILLEE DE L'INVENTION

[0035] As illustrated on the figure 1 , a volumetric lobe pump 10 has a stator 11 whose internal wall forms a substantially cylindrical chamber. The lateral ends of the cylindrical chamber are closed by two plates bolted to the stator 11.

[0036] The stator volume formed in the cylindrical chamber is in hydraulic communication with a fluid inlet 12 and an extraction chimney 13.

[0037] In the example of the figures 1 And 2 , the fluid inlet 12 is located at the rear of the pump 10 while the extraction chimney 13 is arranged above the pump 10.

[0038] Of course, the positioning of the fluid inlet 12 and the extraction chimney 13 may vary without changing the invention. For example, the extraction chimney 13 can be positioned opposite the fluid inlet 12.

[0039] In the stator volume, a rotor 14 is mounted mobile in rotation around an axis 43. According to the invention, this rotor 14 has at least two lobes 15 whose radial end 18has a shape of at least one chevron.

[0040] In addition, a flap 16 is mounted at the level of the extraction chimney 13 and means of recall 17 of the valve 16 are used to constrain the end 42 of the valve 16 against the rotor 14. More precisely, the end 42 of the valve 16 extends across the entire width of the rotor 14 following the shape of the lobes 15.

[0041] According to the invention, and as illustrated in the figures 3 à 6 , the radial end 18 of each lobe 15 has a shape of at least one chevron and the end 42 of the valve 16 also has a chevron shape intended to match the chevron shape of the radial end 18 of each lobe 15. So the valve 16 comes to rub against the lobes 15 of the rotor 14to constrain the fluid present in a pumping volume Vp to be moved from the stator volume to the extraction chimney 13.

[0042] Pumping volume Vp is defined by the volume arranged inside the stator volume between two lobes 15 and the internal stator wall 11, as illustrated for example on the figures 1 And 2 . In fact, a radial end 18 of each lobe 15 rubs against the inner wall of the stator 11 so that the fluids are contained in this pumping volume Vp when none of the lobes are positioned opposite the fluid inlet 12 or the chimney to be extracted 13.

[0043] The simple chevron shape of each lobe 15 and more particularly illustrated in top view on the figure 7 . With the views in perspective figures 1 à 6 , we observe that this shape with a single chevron can be made with a first circular helix 20 having a left-hand step fixed on a second circular helix 21 showing a step to the right.

[0044] Alternatively, it is also possible to use lobes 15 and a flap 16 having a shape with several chevrons. For example, the double chevron shape of a lobe 15 is illustrated on the figure 8 .

[0045] This double chevron shape can be obtained with a first circular helix with a left-hand thread fixed on a second circular helix with a right-hand thread, itself fixed on a third circular helix with a left-hand thread, itself fixed on a fourth circular helix with a right-hand thread.

[0046] Besides the chevron shape of the lobes 15 of the rotor 14, the rotor may also have flanges 45arranged on the edges of the lobes 15. The shape of the flasks 45 is substantially identical to the shape of the edges of the lobes 15 of the rotor 14.

[0047] These flasks 45 are positioned at the longitudinal ends of the cylindrical chamber of the stator 11. So, one of the flasks 45 is mobile with respect to the fluid inlet 12 and periodically cuts off the fluid inlet 12 to define the pumping volume Vp. Preferably the lobes 15 have a stainless steel core covered with a food-grade elastomer while the flanges 45 are made of stainless steel to effectively cut any solid elements from the harvest when defining the pumping volume Vp.

[0048] There figure 9 illustrates a planar projection of the internal surface of the stator 11and radial end friction positions 18 of a lobe 15 during its movements in the stator volume. In a first position, at an instant ti, the radial end 18 is arranged opposite the fluid inlet 12. Then, at the moments ti+1 has ti+3, radial end 18 is displaced against the inner wall of the stator volume. At the instant ti+4, a small portion of the radial end 18 of the lobe 15 is located opposite the extraction chimney 18. Thus, a weak hydraulic communication is initiated between the pumping volume Vp and the extraction chimney 13. As the rotor moves 14, the contact surface between the pumping volume Vp and the extraction chimney 13 increases so that in the state ti+5 the pumping volume Vp is almost completely in hydraulic communication with the extraction chimney 13.

[0049] So, this figure 9 illustrates the progressiveness of the hydraulic communication of the pumping volume Vp with the extraction chimney 13.

[0050] Of course, the number of lobes 15, stator volume, diameter and length of the stator 11 can vary depending on pumping requirements. Similarly, the rotor rotation speed is conventionally defined according to the desired pumping requirements. Typically, the rotor rotation speed 14 can be between 0.5 and 2 seconds per revolution. In addition, the rotor 14 may include an axis of rotation 40 fixed, as illustrated on the figures 1 à 6 Alternatively, it is also possible to use an epicyclic gear train to mount the rotor.

[0051] Regarding the means of recall 17 of the valve 16, they can correspond to any known means, such as a spring or even a return system with plastic wedges. Preferably, the return means 17 of the valve 16 correspond to magnetic means using the cooperation of several magnets to cause a movement of the valve 16 against the different lobes 15. To do this, the valve 16 is mounted on a rotating axis 40 and has a connecting portion 41 to the chevron end 42. The valve axis 40 is fixed on an axle support 34 integrated into the recall means 17, illustrated in exploded view on the figure 10 .

[0052] These means of recall 17 include support 28 fixed on the stator 11 and intended to integrate a first ring of magnets 27.This first ring of magnets 27 is intended to cooperate with a second ring of magnets 28 mounted on a stand 26 fixed on the axis 40. When the axis 40 is moved, the North-South poles of the magnets 27 And 28 enter into phase opposition and tend to bring the valve back 16 against the rotor 14. In addition, to improve the stroke of these recall means 17, an intermediate crown 29 carrying a third ring of magnets 30 and preferably arranged between the crown of magnets 27 fixed on the stator 11 and the crown of magnets 28 fixed on the axis 40.

[0053] Caches 31, 32 And 33 are preferentially arranged between the different rings to guarantee the integration of the magnets 27, 28 And 30. A cork 35 is also reported on the axis 40after fixing it in the recall means 17.

[0054] Preferably, the supports 25, 26 And 29 as well as the caches 31, 32 And 33 are mounted by removable fixing means, for example screws, thus allowing the return means to be opened 17 to modify the magnets 27, 28 And 30 in order to modify the restoring force applied by these restoring means 17.

[0055] Whatever the means of recall 17 used to constrain the valve 16 against the lobes 15, the invention makes it possible to obtain progressiveness in the hydraulic communication of the pumping volume Vp with the extraction chimney 13, thus limiting the stresses experienced by the fluids during pumping.

[0056] It follows that the invention makes it possible to obtain a pump 10limiting noise and stresses on fluids during pumping. Thus, this pump 10 is particularly suitable for pumping harvest products and protecting the quality of the harvest.

Claims

1. Positive displacement lobe pump (10) comprising: - a stator (11) having an internal wall defining a stator volume; the stator (11) having a fluid inlet (12) and an extraction shaft (13); the fluid inlet (12) and the extraction shaft (13) being in hydraulic communication with the stator volume; - a rotor (14), rotatable inside the stator volume, comprising at least two lobes (15); each lobe (15) having a radial end (18-19) intended to scrape the internal wall of the stator (11) so as to obtain a pumping volume (Vp) between two consecutive lobes (15) when they are positioned between the fluid inlet (12) and the extraction shaft (13); - a valve (16) mounted at the extraction shaft (13) so as to cooperate with the lobes (15) to force the fluids, present in the pumping volume (Vp), to be moved into an extraction shaft (13) during rotation of the rotor (14); and - return means (17) of the valve (16) configured to move the valve (16) against the lobes (15) when the lobes (15) are moved at the extraction shaft (13); characterised in that the radial end (18-19) of each lobe (15) has the shape of at least one chevron so that the hydraulic communication of the pumping volume (Vp) with the extraction shaft (13) is progressive, the valve (16) having the shape of at least one chevron complementary to that of the lobes (15) so as to ensure the hermeticity of the hydraulic communication between the pumping volume (Vp) and the extraction shaft (13).

2. Positive displacement lobe pump according to claim 1, wherein the lobes (15) and the valve (16) have a shape with a single chevron, the rotor (14) having a first circular propeller (20) with a left-hand pitch fixed to a second circular propeller (21) with a right-hand pitch.

3. Positive displacement lobe pump according to claim 1, wherein the lobes (15) and the valve (16) have a shape with two chevrons, the rotor (14) having a first circular propeller with a left-hand pitch fixed on a second circular propeller with a right-hand pitch, itself fixed on a third circular propeller with a left-hand pitch, itself fixed on a fourth circular propeller with a right-hand pitch.

4. Positive displacement lobe pump according to any one of claims 1 to 3, wherein the rotor (14) comprises two, three or four lobes (15).

5. Positive displacement lobe pump according to any one of claims 1 to 4, wherein the rotor (14) comprises a fixed axis of rotation.

6. Positive displacement lobe pump according to any one of claims 1 to 4, wherein the rotor (14) comprises a mobile axis of rotation forming an epicyclic gear train.

7. Positive displacement lobe pump according to any one of claims 1 to 6, wherein the return means (17) of the valve (16) correspond to magnetic means.

8. Positive displacement lobe pump according to claim 7, wherein the return means (17) of the valve (16) comprise: - a first annular support (25) for magnets (27), the first support (25) being fixed with respect to the stator (11); and - a second annular support (26) for magnets (28), the second support (26) being fixed relative to the valve (16); the two supports (25, 26) being coaxial with the axis of rotation of the valve (16) and positioned opposite one another; the poles of the magnets (27) of the first support (25) being offset with respect to the poles of the magnets (28) of the second support (26) so that the magnetic force of the magnets (27-28) tends to move the valve (16) against the lobes (15).

9. Positive displacement lobe pump according to claim 8, wherein the return means (17) of the valve (16) further comprise a third annular support (29) for magnets (30), the third support (29) being free to rotate between the first support (25) and the second support (26), the poles of the magnets (30) of the third support (29) being offset between the poles of the magnets (27) of the first support (25) and the magnets (28) of the second support (26) so as to increase the return stroke of the return means (17).

10. Positive displacement lobe pump according to claim 8 or 9, wherein the return means (17) of the valve (16) comprise means for removably fixing the supports (25-26, 29) allowing the return means (17) to be opened in order to modify the magnetic power or the number of magnets (27-28, 30) when it is desired to modify the return force of the return means (17).