FR2637947A1 - VANE PUMP - Google Patents

Abstract

Vane pump, in particular used in devices for the treatment of liquid food substances, such as cream or dairy products, in which the suction pipe 6 of the pump is in direct communication with the suction chamber of the pump and with the pump. rotor and / or pump shaft housing and support area. In addition, the rotor 3 comprises a surface coating 15 of plastic material, in particular of polysulfone, which eliminates the risks of galling by friction and the rotating support is produced with two bushes 13, 14 and without precision bearings.

Description

The present invention relates to a vane pump for the

  treatment of liquid food substances, such as for example milk and its derivatives, and in particular a pump used in a device for whipping the cream by means of a texturizer.

  Pumps of this kind are widely used

  used in shops or communities where it is necessary to quickly prepare and on demand given quantities of whipped cream, ice cream or other similar products, observing at the same time

  the most stringent hygienic conditions for the pro-

duit.

  Known vane pumps, used ac-

  in these devices, are of the type comprising

  a stator in the form of a hollow cylindrical body, in the-

  which one rotor is mounted rotating, in an offset position, with vanes pushed elastically outwards. The stator is provided with product suction and discharge conduits, and the rotor is provided with a shaft connected to the shaft of an actuating motor, usually of the electric type, at the

  by means of a quick coupling gasket.

  These pumps must meet not only the normal requirements of economy and efficiency, but also

  to those of an easy assembly for operations of net-

  frequent cleaning, as well as an absolutely perfect seal in order to prevent liquid from infiltrating along the pump shaft and / or the motor shaft. Taking these requirements into account

  in the pumps of the known technique some drawbacks

  which limit the performance of the devices and

  make them expensive and not very rational to use,

  in some cases even sanitary hygiene problems

  to hush up. A first drawback derives from the fact that, when working with food substances, such as

  cream or similar products, susceptible to fermen-

  With the production of bacteria, it is extremely important to prevent the treated product from entering the clearances between the stator and the pump shaft and reaching the motor shaft; in this case, in fact, the stagnant and fermenting product could contaminate the substance

  food used thereafter. In order to avoid these pro-

  problems, known pumps provide for the use of press-

  packing, or similar holding devices, in

  the coupling between stator. and rotor.

  However, said cable glands are not always able to solve the problem, both because of their loss of efficiency through wear, and because in any case the distribution of pressures at

  the interior of the stator can easily allow the formation

  tion of accumulation spaces, with net-

consequent toyage.

  It has also been proposed to withdraw the liquid

  upstream of the cable gland, i.e. to unblock

  expensive the discharge pipe so that the area of the cable gland remains essentially under vacuum, in order to recirculate the product which has

  possibly infiltrated into said zone coming from the

  pump leakage. This provision presents for-

  both the disadvantage of creating a labyrinth course which causes high pressure losses and therefore reduces the

pump performance.

  Another disadvantage of pumps of this type is that, for the optimal functioning of the

  pump, it is extremely important to avoid ex-games

  discontinuous between the fixed parts and the rotating parts therefore, the rotor must be placed as close as possible to the stator without however rubbing on it to

  avoid the risk of seizure or in any case of deterioration

  tion of the parties. This requirement imposes a precision

  very high in the realization and assembly between sta-

  tor and rotor, with the use of precision bearings and other devices which increase disproportionately the cost of the pump, under penalty, otherwise, the loss of sufficient safety and duration characteristics in the time.

  The object of the present invention is to

  to solve the aforementioned problems, and in particular to eliminate the danger of losses and stagnation of the treated substance, by avoiding the drawbacks deriving from the use of cable gland, and guaranteeing an optimal coupling between rotor and stator without having to resort to of

  complex precision work.

  These objects are achieved by means of the invention which relates to a vane pump, in particular for food substances, such as milk and its derivatives,

  said pump comprising a stator in the form of a cy-

  hollow lindric provided with a suction pipe and a delivery pipe and a rotor comprising a drum

  equipped with pallets, rotatably supported in position

  offset position inside the stator and mounted on a shaft connectable to an actuating motor, characterized in that said suction duct is at the same time in direct hydraulic communication both with the suction chamber of the pump that with at least one point of the seat for housing said shaft and / or said drum. In addition, according to a preferred configuration,

  the pump according to the invention is characterized in that the-

  -dis rotor provides a surface coating of material

  anti-friction plastic, at least in its suscep-

  tibles to come into contact with the stator.

  This plastic material consists of pre-

  reference by polysulfonic or polyketonic resins such as those called PES, PEK and PEEK produced by

ICI (Imperial Chemical Industries).

  These features and benefits of

  the invention and others will emerge more clearly-

  ment of the description which follows, with reference to the

  attached sins, o: fig. 1 is a schematic top view of the vane pump according to the invention;

  fig. 2 is a sectional view of an embodiment

  possible tion of the pump according to the invention; fig. 3 is a sectional view of a second type of pump according to the invention; and fig. 4 is an enlarged perspective view of the outlet of the suction pipe of the pump of the

fig. 3.

  FIG. 1 schematically illustrates a vane pump according to the invention, which comprises a stator 1 constituted by a hollow cylindrical body 2, in

  which opens a suction duct 6, and by a

  circle 2 ', in which a delivery duct 7 opens, as best shown in FIG. 2. The two conduits 6 and 7 are placed on each side and close to the point

  zero 20, o the rotor 3 is at the shortest distance from the sta-

  tor 1 (figure 1). Inside the stator and in an offset position, a rotor 3 is mounted comprising a drum 4 with paddles 19 elastically pushed outwards by a spring 5 'or similar means. In a preferred embodiment the pallets 19

  are made of carbon fiber, so as to be particular-

  wear resistant. The rotor is driven in ro-

  tation in the direction indicated by the arrow R by means of an electric motor, not illustrated, connected to the shaft 8 of the

pump.

  Fig. 2 shows in more detail in axial section the structure and construction of a first type

  vane pump according to the invention.

  The stator 1 comprises a cover 2 'and a cylindrical body formed by a cavity delimited by a side wall 10 and a bottom wall 11, which is integral with a cylindrical portion 12, axially hollow and of diameter smaller than that of the cavity 2. The stator body can be made in one piece from stainless steel, but, in another embodiment, the stator can be formed by a steel part of reduced thickness, which constitutes the internal wall of the stator. , coated on the outside, with a technique known in itself, with a layer of plastic material. In this way the use of metal in the body is considerably reduced

  pump, which is therefore lighter and more economical

  mique, without diminishing its performance.

  As mentioned before, the suction duct 6 is in direct hydraulic communication both with the variable volume suction chamber and with the housing and / or support area of the shaft.

and the drum.

  In the embodiment shown in Figure 2, the suction duct 6 has a single outlet located on the junction between the side wall 10 of the stator and its bottom wall 11. This outlet is generally in the form of a circular hole, of which at least one half in the cutting plane is placed above the surface of the

  bottom wall 11, while the remaining part is placed

  created below said surface and is in communication

  direct hydraulic with a 6 'groove provided on the side

  bottom king 11. This groove 6 ′ extends from the

  true blockage of conduit 6 to the part of the

  king 11 which constitutes the housing or the support of the rotor

  3, namely up to the first portion of the area above

  susceptible to infiltration of cream or other edible liquids. It is of course possible to extend

  said groove until it touches the area of lo-

  8 tree support and support; in any case, independent

  especially of its extension, thanks to the groove 6 ′, all of said housing and support area of the shaft 8 and / or of the drum 4 is placed in depression with the outlet of the suction duct 6, and possible infiltrations

  in this area cannot extend to the mo- tree

  tor or stagnate on the spot, but they are on the contrary

  recycled to the suction chamber of the pump.

  In the illustration of FIG. 2, the outlet of the suction duct 6 is substantially symmetrical with respect to the plane of the bottom wall 11, but it can

  also differentiate from this configuration, as my-

very in figure3.

  Unlike the embodiment of Figure 2, where the wall 11 is substantially on the same plane as

  the lower part of the rotor drum 3 and the

  lettes (not shown), in the embodiment of FIG. 3 the bottom wall 11 of the stator 1 has a recessed part, generally indicated by 16, which forms a step and constitutes a housing and support area

for rotor 3.

  The remaining part of the bottom wall 11 on the contrary constitutes the surface 18 along which

  move the paddles 19 of the rotor.

  As shown in Figures 3 and 4, the de-

  plugged suction line 6 is located in correspondence

  dance of the tread profile and concerns the surface 18, along which the rotor vanes move, the

  vertical part 17 of the step and the surface of the par-

  tie back 16. The vertical part 17 of the step as well as the recessed part 16 of the bottom wall 11

  are substantially in contact with the drum and appear

  so stick to the pump area likely

  liquid infiltration. Thanks to the presence of the outlet

  ché shaped as described, the conduit 6 is in direct hydraulic communication both with the suction chamber of the pump (thanks to the outlet part present on the surface 18), as with the housing and support area of the shaft and / or the drum (thanks to the outlet part present on the vertical part

  of step 17 and on the recessed part 16 of the pa-

king 11).

  In the two configurations shown in Figures 2, 3 and 4, the suction duct has a single outlet which concerns the suction chamber and the housing area; it is however possible to have pumps with two separate outlets of the same conduit

  one of which will be located traditionally-

  nelle in the suction chamber, while the other will be located in correspondence of the housing and

  shaft and / or drum support.

  In any case, thanks to these configurations, the liquid which could possibly return and infiltrate under the drum 4 and along the shaft 8 is in communication with the conduit 6 which recirculates it, not allowing its passage towards the seat of the shaft, with consequent deposits and stagnation, without this resulting in losses of efficiency for the pump itself. The effectiveness of the configuration illustrated in preventing infiltration is such that the device does not require the use of cable glands or

  similar support systems, which greatly simplifies

  build the pump and reduce the cost

  without any prejudice to safety and reliability.

  According to another characteristic of the invention, as illustrated in FIG. 2, the rotor 3 placed inside the stator 1 is formed by a metal part or portion 5 whose surface is coated, at least in its parts which can enter in contact with the stator 1, a layer 15 of plastic material at low

  coefficient of friction. In a preferred embodiment

  tial this plastic material is constituted by po-

  lysulfones, o by the generic term "polysulfone" on

  wants to hear polymeric materials here in the-

  which along the polymer chain of the sul-

  foniques are interspersed at regular intervals.

  An example of these materials is:

  commercially available polysulfone under the name

  PES (polyethersulfone) mination a registered trademark of ICI (Imperial Chemical Industries). This product represents the preferred material for coating the rotor 3.

  It is also possible to use other ma-

  similar, such as polyketones,

  such as PEK (polyetherketone) and PEEK (poly-

  ether-etherketone), both produced by HERE.

  It has been found experimentally that, thanks to the

  coating thus formed, the rotor can slide on the

  tor without seizing up, in particular at said zero point and on the steel surface of the bottom wall 11 and

  cover 2 'of the stator. This advantage is particular-

  This is important in the case of polysulfones, because, as a result of the friction between the coating 15 and the steel surface of the stator walls, the polysulfone is "polished" and the coefficient of friction is reduced. It is not

  therefore more essential to carry out an extremely

  rotor 3 by means of bearings

  port to stator 1 and the rotor can be supported

  revolving by a simple chrome bushing with thick-

  sor 14 which fits into a coaxial socket 13 soli-

stator.

  This last socket, at least superficial-

  Lement, is in material with low coefficient of friction,

  for example in polytetrafluoroethylene (-Teflon4) or gra-

  phite. The sleeve 14 is integral with the shaft 8 of the pump. The invention is not limited to the illustrated embodiments, but also covers the numerous

  possible construction variants.

Claims (13)

  1) Vane pump, especially for sub-   liquid food stances, said pump comprising a stator (1) in the form of a substantially cylindrical hollow body provided with a suction duct (6) and a discharge duct (9), and a rotor (3), including   a drum (4) provided with pallets (19), supported in   revolving in offset position inside the sta-   tor and mounted on a shaft (8) connectable to an actuating motor, characterized in that the conduit   (6) is in both hy-   direct hydraulics as well with the suction chamber   of the pump with only at least one point in the housing area-   ment of said shaft and / or said drum.   2) Pump according to claim 1, character-   sée in that said suction channel (6) has a single outlet, a first part is located in the suction chamber, while the remaining part   is positioned in said housing and support area from the tree and / or the drum.   3) Pump according to claim 2, in la-   which the bottom wall of the stator rests on a single plane (11) along which move the lower parts of the pallets (19) and the lower part of the drum (4), characterized in that said outlet is located in the corner between the side wall (10) and the bottom wall   (11) of the stator, said outlet opening into said pa-   lateral king for about half of its extent   above the surface of said bottom wall and for the remaining half approximately below said surface, this second half being in communication with a   groove (6 ') provided on said surface of the lo-   support and support of the shaft and / or the drum.   4) Pump according to claim 2, in la-   which the bottom wall of the stator has a recessed part (16) which forms a step and constitutes the seat for housing and possible support for the rotor, the remaining part (18) of the bottom wall constituting the surface   along which move the pallets (19) of the drum   bour, characterized in that said outlet is located on   along the profile of said step (16) and interests the sur-   face on which the pallets move, as well as the vertical part of the step and the recessed part of the bottom wall of the stator.   5) Pump according to claim 1, character-   in that said suction duct (6) has two or more outlets, interconnected and placed respectively in said suction chamber and said   shaft and / or drum housing area.   6) Pump according to one of claims which   above, characterized in that said rotor (3) is   provided with a surface coating (15) of plastics material   tick with a low coefficient of friction at least in its parts in contact, or likely to come into contact, with the stator.   7) Pump according to claim 6, character-   in that said plastic material is chosen from   polysulfonic and / or polyketonic polymers.   8) Pump according to claim 7, character-   in that said plastic material is chosen from   products known as PES, PEK, PEEK (registered trademarks HERE).   9) Pump according to one of claims 1 to 8,   characterized in that the rotor (3) is supported in ma-   turning on the stator by means of a first socket (13) integral with the stator and a second   socket (14) coaxial with the previous one and integral with the ro-   tor, said sockets being in direct contact with each other.   10) Pump according to claim 9, character-   placed in that said first sleeve (13) is made of a material with a low coefficient of surface friction such as teflon 'or graphite.   11) Pump according to claim 9 or 10, charac-   terized in that said second socket (14) is made of tal, with chrome surface.   12) Pump according to one of the pre- claims   cédentes, characterized in that the stator is formed by a part in a single piece of plastic and by a part in stainless steel which constitutes the part internal.   13) Pump according to any one of the claims.   previous tions, characterized in that the pallets   (19) of the rotor are made of carbon fiber.