Vacuum pump with filtering element

The present invention relates to the field of vacuum pumps.

A reference herein to a matter which is given as prior art is not to be taken as an admission that the matter was known or that the information it contains was part of the common general knowledge as at the priority date of any of the claims.

Vacuum pumps are already known, and in particular lubricated vanetype rotary vacuum pumps in which the filtration of the oil is based on the principle of coalescence. A flow of air loaded with oil circulates from an inlet of a casing, in which a filtering element is mounted, towards an outlet, from where it comes out again free of oil mist. The filtering elements generally take the shape of cylindrical cartridges typically provided with an entrance nozzle at an inlet of the casing and a watertight inner bottom in such a manner that the flow of air traverses the cylindrical walls before being directed towards an exhaust lid situated in principle on the opposite side from the entrance nozzle with respect to the axis of the cylinder. The cartridge can be kept in place in the casing with the aid of elastic elements or can be fixed on the entrance wall of the chamber by means of the inlet nozzle.

In order to increase the filtering capacity and in parallel the duration of the life of the filtering elements, there exist solutions according to which a plurality of cartridges are mounted in parallel inside a casing, such as disclosed, for example, in the document ΕΡ1 034 830 where the latter are mounted side by side on an inner wall of the casing. This particular arrangement where the nozzle of the cartridges is no longer directly connected to the inlet of the casing implies an inversion of the flow of air from the outside toward the inside of the cylindrical walls of the cartridges even though the flow always takes place along the axis of the cylinder, and the replacement of the cartridges there is relatively tedious.

Consequently there exists a need for a solution free of these known limitations.

It is desirable to provide an easier and more practical assembly and disassembly of the filtering elements in the casing of the pump.

According to one form of the invention, there is provided a vacuum pump comprising a casing in which are disposed a first inlet orifice and a second outlet orifice to allow the flowing of a flow of air, and in the interior of which a filtering element is mounted in a removable way, wherein at least one orifice of the casing selected from among the first inlet orifice and the second outlet orifice is disposed on an exhaust lid which is at the same time removable from the casing but integral with the filtering element, and wherein the connection between the casing and the exhaust lid is not tight.

In another form of the invention there is provided a cartridge for a vacuum pump comprising a casing on the inside of which a filtering element is able to be mounted in a removable way, according to at least the above embodiment, said cartridge containing the filtering element provided with an inlet nozzle and a closure nozzle arranged each on one side of an intermediate filtering part, the cartridge comprising an exhaust lid integrated in the closure nozzle of the filtering element, the connection between the casing and the exhaust lid not being tight. The filtering element is likely to be replaced often in the course of the life of the pump.

One advantage of the proposed solution is that it allows simultaneous mounting of the filtering element and of the exhaust lid in the pump, which enables not just savings in terms of labor, but likewise in terms of costs and efficiency since no special arrangement is necessary anymore in particular inside the pump for the essential fixation of the closure nozzle of the filtering element and the axial support thereof. According to a special advantageous embodiment, the exhaust lid and the closure nozzle are realized as a single piece in order to facilitate the machining.

According to preferred embodiments, the exhaust lid is connected to the closure nozzle with the aid of a connector, which acts as coupling piece.

Whether or not this connector on the one hand and the exhaust lid and the closure nozzle on the other hand are designed as a single piece, it preferably allows other functions to be integrated such as that of an anti-noise filter, in order to combat more effectively the noises caused by the pump, or moreover an oil filter through the agency of a baffle to prevent big drops from being able to reach the exhaust outlet. According to a preferred variant, the shape of the baffle and its arrangement between the closure nozzle and the exhaust lid enables these two elements, i.e. the oil filter and the anti-noise filter, to be combined into a single same piece, which allows additional operational gains, Moreover an alignment means can preferably be provided for mounting the baffle in such a way that it is oriented in the right direction.

According to other preferred embodiments, a handle can be integrated in the lid in order to further facilitate the operations of assembly and disassembly.

Moreover, the coupling piece between the exhaust lid and the fixation nozzle can likewise have guide surfaces in order to facilitate the insertion and the removal of the filtering element into and from the pump.

It will be understood from the detailed description which follows that the advantageous features taken from preferred embodiments can be taken alone or in combination.

Where the terms “comprise”, “comprises”, “comprised” or “comprising” are used in this specification (including the claims) they are to be interpreted as specifying the presence of the stated features, integers, steps or components, but not precluding the presence of one or more other features, integers, steps or components, or group thereto.

3a

Other advantageous features emerge more clearly from the description which follows of a special embodiment of the invention given by way of non-limiting example and represented by the attached drawings, in which:

- Figure 1 is a schematic view of a vacuum pump containing a filtering cartridge according to the prior art;

- Figure 2 is a schematic view of a vacuum pump containing a new filtering element according to the present invention;

- Figure 3 is a three-dimensional view of a cartridge used as filtering element according to a first preferred embodiment for the present invention;

- Figures 4Α, 4Β, 4C and 4D represent different views of the cartridge represented in Figure 3, i.e. a view from above (Figure 4Α), a sectional view along the axis Α-Α of Figure 4Α (Figure 4Β), a view from the rear of the exhaust lid (Figure 4C) and finally a sectional view at the connector, along the axis C-C of Figure 4Β (Figure 4D; and

- Figure 5 is an enlarged schematic view of the inlet end of a cartridge used as filtering element according to a second preferred embodiment of the present invention.

Figure 1 illustrates a filtering element 3 taking the form of a cartridge mounted in the casing 2 of a vacuum pump 1 according to one known solution in the prior art. The filtering element 3 comprises an inlet nozzle 31, mounted at a first inlet orifice 21 of the casing 2 of the pump, and a closure nozzle 32 between which is mounted a filtering part 33 through which the flow of air, marked by the arrows F, is directed, which is then directed towards an outlet orifice 22 of the casing 2. The outlet orifice 22 of the casing 2 is arranged here in the center of a removable lid whose opening allows the insertion and the removal of the filtering element 3 inside the casing 2 of the vacuum pump 1. Due to the second orifice 22 and the flow of air F which traverses this closure lid, this element is generally called an exhaust lid (or flange) 4.

O-ring type seals and guide surfaces are generally provided at the inlet orifice 21 of the casing 2 and at the inlet nozzle 31 of the filtering cartridges to facilitate their mounting at this end, and to ensure the media tightness in order to ensure the good functioning of the vacuum pump 1.

In order to ensure the maintaining of the filtering cartridge in position in the casing 2, an adjustable elastic fixation element 10 comes to press against the rear face of the closure nozzle 32 of the cartridge, and it is retained moreover axially by the lateral shoulders 11 arranged on the inner face of the casing 2. Consequently, the replacement of a cartridge requires, on the one hand, the dismantling of the exhaust lid 4 with respect to the casing 1, then of the adjustable elastic fixation element 10 in order to free the filtering cartridge, which is tedious.

Figure 2 illustrates a schematic view of a modified cartridge 30 mounted in the casing 2 of a vacuum pump 1. This modified cartridge 30 henceforth comprises not just a filtering element 3, but also an integrated exhaust lid 4, which permits these drawbacks to be overcome.

The cartridge 30 henceforth encompasses the filtering element 3, whose body has a symmetry axis Α-Α aligned on the axis of the first inlet orifice 21 and of the second outlet orifice 22, that is to say their respective centers (i.e. the first center 210 of the first inlet orifice 21 and the second center of the second outlet orifice 220). The filtering element 3 still comprises an inlet nozzle 31, and a tight closure nozzle 32 to direct the flow of air F towards the lateral walls of the intermediate filtering part 33. However, the closure nozzle 32 is now no longer kept in place inside the casing 2 by a dedicated fixation, but directly through the fixation of the exhaust lid 4 on the casing 2 itself. In effect, as can be noted in Figure 2, a coupling piece which is called here a "connector" 5 connects the closure nozzle 32 with the exhaust lid 4 in such a way that a fixation of the latter on the casing 2 determines at the same time the positioning of the filtering element 3. The indirect fixation by means of the exhaust lid 4 thus makes it possible to save one operation during the putting in place and the exchange of the cartridge in the casing 2.

According to preferred embodiment illustrated by Figure 3 for the modified cartridge 30, the body of the filtering element 3 is preferably cylindrical, in order to facilitate an isotropic flow of fluid. The alignment of the symmetry axis Α-Α of the cylinder on that of the inlet and outlet orifices of the casing (reference numerals 21 and 22 respectively) moreover makes it possible to arrange guide surfaces 50 along the connector 5 in the partial prolongation of the cylinder in order to facilitate the operations of insertion and removal of the modified cartridge 30 in the casing 2. Such guide surfaces 50 are thus easy to machine, for example by injection or molding, and contribute even more to the simplification of the operations of assembly and disassembly. For such guide surfaces 50 along the axis Α-Α, other symmetrical geometric shapes, for example of the parallelepiped type are however likewise conceivable for the body of the filtering element 3, and the partial prolongation of these geometric shapes can thus form little beams or feet oriented along the axis Α-Α at its periphery.

In Figure 2, it can be noted that a baffle 6 is arranged in the space between the closure nozzle 32 and the exhaust lid 4. This baffle 6 has the purpose of preventing big drops of oil formed through coalescence at the exit of the filtering element 3 in the direction of the flow of air marked by the big arrow which pass behind the closure nozzle 32 from reaching the exhaust lid 4. The baffle 6 here is connected to the inner wall of the exhaust lid 4, but could also be arranged at the connector 5 itself, the underlying idea being to integrate this baffle 6 in the modified cartridge 30 in such a way that it fulfils a supplementary function without requiring another dedicated piece therefor.

It is however very important to mention that, thanks to the structure of the cartridge 30 mentioned above, the connection between the casing 2 and the exhaust lid 4 does not necessarily have to be tight. Flowever, the tight closure of the casing 2 is not detrimental to good functioning of the modified cartridge 30, and gaskets or similar devices can likewise be used.

The presence of a noise suppressor device 7, arranged in the same space between the closure nozzle 32 and the exhaust lid 4, can also be discerned in Figure 2. The noise suppressor 7 is indicated, according to this preferred embodiment, with the aid of an arrow of broken lines because it is preferably formed at the baffle 6 itself. If the molding device allows, the noise suppressor 7 and the baffle 6 can be designed as a single piece, which in this case serves in parallel the function of "muffler" at the exit of the casing 2 of the vacuum pump 1, and this by possibly supplementing noise-attenuating devices arranged ordinarily at the inlet, such as, for example, the anti-noise valve 9 visible in Figure 4C described in the following.

Figure 3 illustrates a modified cartridge 30 according to a preferred embodiment of the invention, according to which the body of the filtering element 3 is cylindrical and it is connected to an exhaust lid 4 of square shape and in the periphery of the corners of which four holes have been provided for insertion of fixation screws. The outlet orifice 22 is round in order to allow an easy connection, for example to an exit pipe. Thus the modified cartridge 30 remains symmetrical with respect to the axis of the filtering element 3 constituted by the inlet nozzle 31, the closure nozzle 32 and the intermediate filtering part 33. The square shape as well as the dimensions of the exhaust lid are preferably selected to correspond to the usual shape of existing flasks and thus to facilitate the flattening against the contact surface of the pump 1 at the time of assembly as well as to facilitate the configuration of alignment devices on its periphery. It will be understood however this it is likewise possible to envisage mounting ears in the form of tongues projecting towards the exterior, and which will be spaced regularly about circular arcs of the same length, or even other suitable, preferably symmetrical, geometric shapes.

According to this preferred embodiment, the exhaust lid 4 and the closure nozzle 32 are designed as a single piece, such that the connector 5 constitutes here only one hypothetical intrinsic piece because it is impossible to determine where this intermediate coupling piece begins behind the closure nozzle 32 and where it stops at the lid. One can however distinguish, in this intermediate space, the guide surfaces 50 in the prolongation of the cylinder.

The material used to achieve the end of this cartridge 30 by molding can consist, for example, of polyamide or of polypropylene, or of any suitable material able to support a flow of air circulating at about 80°C. Furthermore a conductible material will preferably be chosen, such as, for example, polypropylene with insertion of stainless steel fibers in order to reduce as much as possible the level of static electricity.

Notable moreover in Figure 3 is the presence of a grating above the baffie 6 in the available space between the closure nozzle 32 and the exhaust lid 4. This grating constitutes an advantageous variant for realization of the noise suppressor 7, illustrated previously in Figure 2: in effect, this permits, on the one hand, the exhaust flow to be guided, and, on the other hand, the sound level to be reduced, thanks to the successive passage of the flow of air in the smaller sections and then in the bigger ones. Furthermore, instead of letting the air calm down through a big hole, the fact that it is separated into a certain number of small holes or slots, increases the frequency of the generated sound, the range of which is more restricted, and thus contributing to achieving the same object sought of reduction of the noises. Finally, this grating permits a laminar flow to be created, eliminating the turbulence normally generated during the blowing, and consequently reducing even more the noise level.

This preferred embodiment illustrated by Figure 3 for the noise suppressor 7 has moreover two technical advantages: the first consists in achieving the function of anti-noise attenuation at the outlet without any piece necessitating a dedicated supplementary volume having to be specifically provided for this effect, thus reducing the bulkiness, and the second being, in the case where the grating is designed in a modular way with respect to the connector 5 and the baffle 6, to simplify its manufacturing process as well as make its replacement independent from that of the pieces in which it has the purpose of being inserted. It will nevertheless be understood that regardless of whether the noise suppressor is designed in modular fashion or not with respect to the other pieces, and in particular the baffle 6, forms other than that of the grating illustrated in Figure 3 could be chosen with a view to reduce noise without departing from the scope of the present invention.

In the following Figures 4Α, 4Β, 4C and 4D will likewise be referred to for the detailed description of the modified cartridge illustrated in three dimensions in the preceding Figure 3. For reasons of clarity, the noise suppressor grating 7 has no longer been represented there, however.

In Figure 4Α, one finds again all the reference numerals of Figure 3, except for the noise suppressor 7, and only the guide surfaces 50 are marked on the periphery of the connector 5. Even though the baffle 6 is not discernible in its entirety in this figure, it can be noted in Figure 4Β that an alignment system formed by separate pairs of holes for the screwing of the exhaust lid 4 to the casing 2 is provided, namely here two first screw holes 41, and two second screw holes 42 having distinct spacings; in this case, the spacing between the first pair of first screw holes 41 is slightly smaller than that between the second pair of second screw holes 42. Such an alignment system makes it possible to correctly align the baffle 6 in the interior of the casing 2 so that the roof - constituted here by the lateral spoilers 61 well visible in Figure 4D, and which form an integral part there - is correctly oriented, allowing drops of oil to be retained formed by gravity at the outlet of the exhaust filter. Other alignment systems are likewise conceivable, for example with the aid of a bayonet mounting, or with a different number of screws and other geometric shapes for the exhaust lid 4; nevertheless this proposed variant with the aid of pairs of holes and separate screws has the advantage of particularly simple implementation.

Figure 4C in the sagittal sectional plane Β-Β makes it possible to mark an anti-noise valve 9 at the inlet nozzle 31 of the filtering element 3, which makes it possible, together with the noise suppressor at the outlet 7 (not illustrated in this figure), to maximize the soundproofing performance of the working of the pump with respect to the outside. Another possibility for reduction of noise at the inlet nozzle 31 of the filtering element 3 is represented in Figure 5. In this embodiment of the invention, the noise limitation valve 9 illustrated in Figure 4C can be replaced by a reduction of the section of passage for the flow of air. As can be seen in Figure 5, the air (represented by the arrows) penetrates into the interior of the filtering element 3 through a circular ring 37 and a series of bores 38 in such a way that the flow of air passing through the circular ring 37 quickly expands thanks to the widening 39. This flow of air then rejoins the air passing through the bores 38 in a tangential way by pressing it on the conical surface likewise represented in Figure 5. This arrangement makes it possible to have the same noise damping as with using the movable valve 9 while making it possible to achieve the assembly in one single easy-to-machine piece. The reliability is also improved since one no longer has static pieces in the filtering element 3.

Returning to the embodiment represented in Figure 4C, a guide surface 50 can still be discerned there in the prolongation of the bottom of the cylinder, as well as a vertical sectional plane C-C in the intermediate space between the fixation nozzle 32 and the exhaust lid 4 which allows a handle profile 8 to be marked, integrated in the connector 5, visible in Figure 4D. This handle 8 thus integrated in the back of the exhaust lid 4 is consequently hidden by the latter, as Figure 4Β demonstrates which shows a view from the exterior, and thus has an advantage of aesthetic order, as well as a reduction in terms of bulkiness and thus advantages in terms of compactness. Such a configuration likewise allows facilitation of the connection by a possible connector at the outlet.

The integrated handle 8 has a particular shape, here in the form of a "U", not interfering, on the one hand, with the prolongation of the orifice (that is to say, according to the embodiment, the second outlet orifice 22 of the said exhaust lid 4) so as not to disrupt the flow of fluid during normal operational mode of the vacuum pump 1. Such a "U" shape allows a particularly easy and intuitive grip to be maintained by the user, like a drawer: it suffices for his fingers to be introduced in the outlet orifice 22 and then to pull the exhaust lid 4 toward him.

According to this described preferred embodiment, the integrated handle 8 is also designed in an integral way, that it to say in one piece with the closure nozzle 32 and the exhaust lid 4. It thus forms an integral part of a hypothetical coupling piece between these two elements and as such, one can consider in a preferable way designing the integrated handle 8 and the connector 5 as a single piece, which makes it possible to simplify the machining process.

Although in the foregoing description the preferred embodiment illustrated refers to a structure of monobloc type (i.e. realized as a single piece) for the cartridge 30 proposed within the scope of the present invention, it will be easily understood that other variants are possible for assembly of the different constituent parts of this cartridge 30 relating to different technical functions that they fulfil without departing from the scope of invention. It is in notably possible to achieve all the pieces of the cartridge 30 independently and to provide suitable means of attachment to allow their assembly. A cartridge 30 composed of such "detached pieces" and these "detached pieces" for the cartridge 30 likewise forms part of the present invention in the same way as the cartridge 30 achieved in a monobloc manner. Moreover, other geometric, preferably symmetrical, shapes, are likewise conceivable for the exhaust lid and the filtering element. Furthermore, the determination of the inlet and outlet orifices of the casing has been made conventionally with respect to the usual flow of air, but it is likewise possible to envisage pumping devices which would involve an inverted flow of air making the air pass from the outside toward the inside of the filtering cartridge.