FR3127530A1 - positive displacement lobe pump - Google Patents

Abstract

The invention relates to a displacement lobe pump (10) comprising:- a stator (11) having an internal wall defining a stator volume;- a rotor (14) movable in rotation inside the stator volume; the rotor (14) having at least two lobes (15) configured to define a pumping volume (Vp); and- a valve (16) mounted at the level of the extraction chimney (13) so as to cooperate with the lobes (15) to force the fluids, present in the pumping volume (Vp), to be moved in a chimney extraction (13); the lobes (15) having a radial end (18-19) in the shape of at least one chevron so that the hydraulic communication of the pumping volume (Vp) with the extraction chimney (13) is progressive, the valve (16) having a shape of at least one chevron complementary to that of the lobes (15). Figure for abstract: Fig 1

Description

positive displacement lobe pump

Field of invention

The invention relates to a positive displacement lobe pump.

Within the meaning 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 pumping volume. The "displacement lobe pumps" include pumps for which several lobes make it possible to define this pumping volume inside the pump.

The invention can be used to pump a liquid or pasty fluid incorporating solid elements. The invention shows a particularly advantageous application for pumping the products of the harvest for the production of wine.

state of the art

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

Positive displacement lobe pumps have a stator with a fluid inlet and a fluid outlet, also called an extraction chimney. The stator has an internal cylindrical chamber forming a stator volume in hydraulic communication with the fluid inlet and the extraction chimney. To pump fluid from the fluid inlet to the exhaust stack, a lobed rotor is disposed within the stator volume.

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, when the lobes of the rotor move between the fluid inlet and the extraction chimney, the volume between two lobes is first of all positioned opposite the fluid inlet so as to inject the fluids into the volume. stator, for example by means of an Archimedean screw.

The rotational movement of the rotor then moves the volume between two lobes opposite 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 comes to rub against the lobe arranged opposite the extraction chimney so that the rotational movement of the rotor moves the fluids from the pumping volume into the extraction chimney.

However, when placing the pumping volume in hydraulic communication with the extraction chimney, a counter-pressure intervenes in the pumping volume since the piping fixed to the extraction chimney is conventionally subjected to a much greater pressure than that imposed in the pumping volume by the rotation of the rotor.

For example, during the pumping of harvested products, the pressure in the piping connected to the extraction chimney is approximately two bars and a very high backpressure is observed when a lobe of the rotor passes from a state where it rubs against the inner wall of the stator in a state whose radial end is located opposite the extraction chimney. The abrupt transition between these two states is visible at the level of the piping. Indeed, with a translucent pipe, we see the harvest products advancing jerkily in the pipe. Typically, in the piping, the harvested products advance for a period of approximately one second and then, for a few milliseconds, the harvested products stop. They then move back into the piping when the pumping volume is placed in hydraulic communication with the extraction stack due to the relaxation of the pressure of the piping in the stator volume. After this relaxation, the harvested products advance again under the pressure applied by the rotation of the rotor.

These pipe pressure release phases 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 harvested products. when pumping. Even with this anti-pulsating bell, these expansion phases are very noisy and the harvested products still risk being damaged during pumping.

The technical problem of the invention is therefore to obtain a volumetric lobe pump making it possible to obtain efficient fluid transfer by reducing these expansion phases at the level of the extraction chimney.

To respond to this technique, the invention proposes using a lobed 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.

Within the meaning of the invention, a “chevron shape” corresponds to a shape in which two segments intersect at an angle of between 120 and 170 degrees.

To this end, the invention relates to a positive-displacement lobe pump comprising:
- A stator comprising an internal 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 internal 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 level of the extraction chimney so as to cooperate with the lobes to force the fluids, present in the pumping volume, to be moved in the extraction chimney during the rotation of the rotor; And
- valve return means configured to move the valve against the lobes when the lobes are moved at the level of the extraction chimney.

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 a shape at least one chevron complementary to that of the lobes so as to guarantee the tightness of the hydraulic communication between the pumping volume and the extraction chimney.

Thus, the shape of the radial end of each lobe makes it possible to obtain 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 well as the opening of the extraction chimney in the stator volume. It follows that the passage of the radial end of a lobe at the level of the edge of the opening of the extraction chimney in the stator volume generates a very rapid release of the pressure of the piping in the stator volume.

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

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

In addition, by limiting the compression and expansion phases that the fluid undergoes during pumping, it is possible not to use an anti-pulsation bell on the extraction chimney, to limit noise, and to improve the speed. pumping.

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 for pumping harvested products, the limitation of the stresses undergone by the harvested products during pumping makes it possible to protect the quality of the harvest, that is to say to guarantee as much as possible the integrity of the harvest.

The complexity of implementing the invention lies in the specific shape of the lobes of the rotor 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 progressive hydraulic communication between the pumping volume and the extraction chimney, it is possible to use one or more chevrons at the radial end of the lobes.

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

Within the meaning of the invention, a circular propeller is inscribed in a cylinder of revolution so that the radial end of the propeller, that is to say that of the rotor, can cooperate with the cylindrical internal wall of the stator to form a substantially hermetic cavity.

Furthermore, the rotor can comprise two, three or four lobes without changing the invention.

With a rotor with two lobes, the radial end of each lobe of which forms a single chevron, the section of the rotor is ovoid and the rotor is relatively simple to design and manufacture. For example, the production of the rotor can be obtained by producing the two parts of the propeller independently and fixing them after production.

The rotor can also be cast in one piece by casting a stainless steel core with a lost wax casting technique. This stainless steel core can then be covered with a food grade elastomer intended to receive 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 produced by a lost wax casting technique. The two flanges are preferably produced at the same time as the core.

Alternatively, a three-dimensional print can be made to achieve this complex shape.

This three-dimensional impression is preferred when each lobe has several chevrons. For example, with two chevrons, the rotor can have 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 helix 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, in particular for large volume pumps.

As regards the axis of the rotor, this 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.

Preferably, to limit the size and facilitate maintenance operations, the valve return means correspond to magnetic means.

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 one another;
the poles of the magnets of the first support being offset with respect 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.

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 magnets of the second support.

According to one embodiment, the valve return means comprise removable means for fixing the supports allowing the return means to be opened in order to modify the magnetic power or the number of magnets when it is desired to modify the return force. recall means.

brief description of figures

The invention will be better understood on reading the following description, given solely by way of example, and produced in relation to the appended drawings, in which identical references designate identical or similar elements, and in which:

there is a sectional view of a positive displacement lobe pump according to one embodiment of the invention;

there is a perspective, cross-sectional view of the pump from the ;

there is a perspective view from a first angle of the connection between the valve and the rotor of the pump of the ;

there is a perspective view from a second angle of the connection between the valve and the rotor of the pump of the ;

there is a perspective view from a third angle of the connection between the valve and the rotor of the pump of the ;

there is a perspective view from a fourth angle of the connection between the valve and the rotor of the pump of the ;

there is a top view of the pump rotor of the ;

there is a top view of a rotor according to another embodiment;

there is a representation of the projection of the displacements of the rotor of the on the internal wall of the stator; And

there is an exploded perspective view of the return means of the .

Claims (10)

Volumetric lobe pump (10) comprising:
- a stator (11) comprising an internal wall defining a stator volume; the stator (11) having a fluid inlet (12) and an extraction chimney (13); the fluid inlet (12) and the extraction chimney (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) comprising 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 the fluid inlet (12) and the extraction chimney (13);
- a valve (16) mounted at the level of the extraction chimney (13) so as to cooperate with the lobes (15) to force the fluids, present in the pumping volume (Vp), to be moved in the chimney d extraction (13) during the 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 level of the extraction chimney (13);
characterized 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 chimney ( 13) is progressive, the valve (16) having a shape of at least one chevron complementary to that of the lobes (15) so as to guarantee the tightness of the hydraulic communication between the pumping volume (Vp) and the chimney of extraction (13). Positive displacement lobe pump according to Claim 1, in which 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 on a second circular helix (21) with a right-hand pitch. Positive displacement lobe pump according to Claim 1, in which 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 helix with a left-hand pitch, itself fixed on a fourth circular helix with a right-hand pitch. Positive displacement lobe pump according to one of Claims 1 to 3, in which the rotor (14) has two, three or four lobes (15). Positive displacement lobe pump according to one of Claims 1 to 4, in which the rotor (14) has a fixed axis of rotation. Positive displacement lobe pump according to one of Claims 1 to 4, in which the rotor (14) has a movable axis of rotation forming an epicyclic train. Positive displacement lobe pump according to one of Claims 1 to 6, in which the return means (17) of the valve (16) correspond to magnetic means. Positive-displacement lobe pump according to Claim 7, in which the return means (17) of the valve (16) comprise:
- a first support (25) of annular magnets (27), the first support (25) being fixed relative to the stator (11); And
- a second support (26) annular 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). Positive displacement lobe pump according to Claim 8, in which the return means (17) of the valve (16) further comprise a third annular support (29) of magnets (30), the third support (29) being free in rotation 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 of the magnets (28) of the second support (26) so as to increase the return stroke of the return means (17). Volumetric lobe pump according to Claim 8 or 9, in which the return means (17) of the valve (16) comprise means for removable fixing of the supports (25-26, 29) allowing the return means (17 ) 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).