EP0484214B1 - Casing of a pressurised chamber and motorpump using such casing - Google Patents

Abstract

The casing of a pressurised chamber comprises an integrally cast rotor shell centred on the rotor and having an inlet connection, at least one peripheral outlet connection and one open face designed to be sealed by a peripheral edge resting on a support casing. It comprises an outer shell 17, designed to rest axially by means of a central annular section 40 surrounding the inlet connection 18 on the annular outer face 43 of the rotor shell 15 and a front bearing section is fitted with at least two legs or bearings 51, 52 intended to permit the fixing of the outer shell 17 on the support casing 7a by means of fixing elements 55, 56. Application on pump casings of plastic or composite material affording excellent corrosion and abrasion resistance but more limited mechanical strength. <IMAGE>

Description

The present invention relates to a pressure chamber body, in particular to a pump body consisting of a rotor casing, in one piece, of generally annular shape centered on the rotor and having: an inlet connection opening out at the center of '' an annular outer face, at least one peripheral outlet connection and an open face intended to be closed by pressing a peripheral rim on a support body, the rotor casing being reinforced by an outer casing which is more resistant and rigid than the rotor casing and resting on the latter, the outer casing being capable of coming to bear axially, by a central annular part surrounding said inlet fitting, on the annular outer face of the rotor casing and at at least partially surround the periphery of the rotor casing, excluding the outlet peripheral connection (s) by a connecting part connecting a part of ppui frontal and the central annular part. It also relates to pump units using such pump bodies.

Whereas for medium and high power pumps, classic and resistant materials are still used such as steel, cast iron, bronze, for rotor and stator parts, low power pumps more and more widespread in domestic life, synthetic materials such as plastics, for example, are already widely used to make washing machine pumps operating under low pressure.

On the other hand, for longer pressures and longer service lives corresponding, for example, to central heating circulators, it has not hitherto been possible to produce pump bodies of this type in plastic or in material composite to replace the bronze or cast iron used until now. In addition to the problems of resistance to pressure, there are indeed problems of cantilever fixing of the pump unit which is in fact fixed to a rigid support by the pump body.

FR-A-2 402 785 has proposed a centrifugal pump, the body of which is constituted by the assembly of an outer casing of simple shape in stamped metal and a volute in molded plastic material, fitted in the aforementioned outer casing, acting as a partition wall between the suction and delivery ports and whose profile allows the guiding of the fluid between the aforementioned ports while providing good hydraulic efficiency. Such a pump body certainly withstands the moderate pressure forces of pumps for domestic use but it does not allow easy and resistant attachment of the pump set to a support, as is the case with monobloc pump bodies used up to now for long-life pumps such as heating circulators.

The present invention aims to make it possible to produce pressure chamber bodies such as pump bodies, of plastic material or of composite material (reinforced with fibers) very resistant to corrosion and, where appropriate, to abrasion, and much less expensive to produce than traditional foundry materials and which make it possible to withstand not only the pressure forces but also the mechanical forces of fixing a motor-driven pump unit to a rigid support and to the stresses caused by the pump connections to the fluid circuits served.

To this end, according to the invention, said front support part is provided with at least two tabs or supports intended to allow the fixing of said outer casing on said support body by fixing members such as screws by applying the rotor casing sealingly, by its peripheral rim, on the support body.

In order to obtain a better transmission of the pressing force exerted by the outer casing on the rotor casing, the lugs or supports are each associated with bearing surfaces of the outer casing on a bearing surface provided outside the peripheral rim of the rotor casing.

According to another embodiment of the invention, the outer casing is in one piece and its connecting part projects at least two front fixing bosses of said outer casing on an outer support. Each fixing boss has a bore substantially parallel to the rotor axis and capable of receiving a fixing rod such as a bolt or screw.

The load of an entire pump set can thus be transmitted to an external support directly by the part of the outer casing which provides the connection between the central annular part of the outer casing and the support body generally constituted by the casing of an electric motor much heavier than the pump itself. The connecting part advantageously has the shape of a bell whose flared central part is crossed by at least one cut open on the front bearing edge and allowing the passage of a peripheral outlet fitting of the rotor casing.

According to another embodiment of the pressure chamber according to the invention, the central annular part is crossed by the inlet connector which it surrounds by an open sleeve part which ends on the outside by a flange capable of come to bear on the outer edge of said inlet fitting while allowing free passage of a connecting duct to the inlet fitting. The flange projects slightly inward from an outlet bore formed in the inlet connector, so as to retain axially in position an annular seal disposed in said outlet bore.

According to yet another embodiment of the invention, the one-piece rotor casing being made of a flexible material resistant to corrosion by the liquid conveyed by the pump, for example plastic or fiber-based composite material , it is likely to contain a pump rotor centered and guided on the inside outlet of the inlet fitting and the rotor casing is devoid of any fixing means or fixing accessory such as tab and bore but has an open external face rim capable of cooperating sealingly with a ring for fixing the envelope of the drive motor.

According to yet another embodiment of the invention, the outer casing is made in one piece by molding in a metal, such as an aluminum alloy, capable of receiving self-tapping screws.

In a pump unit comprising a rotor pump unit mounted in cantilever on the shaft of an electric drive motor and an electric motor unit consisting of a rotor tube sealingly enclosing the rotor and its bearings and a stator housed in an engine casing, the pump rotor mounted on the motor rotor is housed inside a pressure chamber body produced according to the embodiments which have just been described and the one-piece outer casing of which is rigidly fixed to a ring of the motor casing by sealingly applying the rotor casing to the motor casing, so as to delimit a pressure chamber containing the pump rotor and the inside the rotor tube.

• la figure 1 représente en coupe longitudinale selon l'axe du rotor de pompe et de moteur, un groupe motopompe pour circulateur de chauffage comportant un corps de pompe réalisé selon l'invention, les raccordements mécaniques et de fluide de ce groupe étant figurés en vues fragmentaires;
• la figure 2 représente une vue en bout du côté ouvert de l'enveloppe extérieure du corps de pompe;
• la figure 3 représente la coupe selon le plan III-III de la figure 2;
• la figure 4 représente la coupe selon les plans IV-IV de la figure 2.

Other objects, advantages and characteristics will appear on reading the description of an embodiment of the invention, given without limitation and with reference to the appended drawing in which:

• 1 shows in longitudinal section along the axis of the pump and motor rotor, a motor pump unit for heating circulator comprising a pump body produced according to the invention, the mechanical and fluid connections of this group being shown in views fragmentary;
• Figure 2 shows an end view of the open side of the outer casing of the pump body;
• Figure 3 shows the section on the plane III-III of Figure 2;
• FIG. 4 represents the section along the planes IV-IV of FIG. 2.

There is shown in section in Figure 1 a complete pump unit forming a heating circulator. The pump rotor 1 provided with centrifugal fins la is fixed in rotation and in axial position (by claws) at the end of a rotor shaft 2 which carries the rotor 3 of the electric drive motor 4 of the pump . This electric motor 4 comprises a stator 5 which is sealingly isolated from the rotor 3 by a non-magnetic and non-magnetic metal airgap 6 and which is surrounded by a rigid metal carcass 7 surmounted by a terminal box 8 and forming an envelope of the motor. Carcass 7 has, on the side of the pump rotor, a ring 7a open on the electric motor and closed in leaktight manner on the stator 5 up to the air-gap tube 6 (via the O-ring 10) by a sheet metal flange 9 which engages by its periphery in a centering bore 7b of the crown 7a and which carries a friction bearing 11 ensuring at the same time the axial guidance of the rotor shaft 2.

The pump rotor 1 is housed in a pump body 12 intended to form the pump volute and with which it cooperates to generate an overpressure on the fluid normally aspirated by a suction line 13 and discharged by a discharge line 14. The pump body 12 is made up, according to the invention, by the assembly of two monobloc parts: on the one hand, a rotor casing 15 of generally annular shape and centered on the rotor 1 by an inner sleeve 16 and, d 'on the other hand, an outer casing 17 more resistant and more rigid than the casing 15 and produced here in molded metal alloy, in particular in aluminum alloy.

The rotor casing 15 is provided, in the axis, with a connection 18 for inlet of the fluid to be pumped. This connector 18 is formed by a bore 18a formed inside a sleeve 19 which projects in the center of the annular outer face of the rotor casing. The bore 18a is extended outwards by a bore of larger diameter 18b intended to serve as a bearing for an O-ring seal 20 and, inwards, by the inner sleeve 16 which is housed in the inlet bore 21 of the rotor 1 at the inlet of the centrifugal fins 1a.

A substantially cylindrical ring-shaped portion 22 of the rotor casing 15 is directed towards the metal carcass 7 by surrounding the rotor 1 and ends in an open face 23 (see FIGS. 3 and 4) which comes to bear on respective bearing faces 24 and 25 of the flange 9 and of the carcass 7, the seal being ensured between the face 24 and the flange 9 by interposition of an annular seal. In fact, the open face 23 ends in a short section of sleeve 26 which engages inside the centering bore 7b formed in the carcass 7 and which ends in a front face of support provided with a seal. The sleeve section 26 is extended outwardly by a shoulder 27 bearing on the face 25 of the carcass 7 which corresponds to a flange 28 projecting over a small height outside the substantially cylindrical ring 22. The face of the rim 28 which looks on the side opposite to the open face 23 is here inclined to provide a carrying surface 29 whose function will be described later.

The rotor casing 15 has fluid outlet connections opening onto its periphery. A drain connection 30, closed in service by a threaded plug, is provided at the bottom of the substantially cylindrical part 22. A discharge connection 31 is provided at the upper part of the ring 22 and has a lateral orifice 32 forming a tangential start d 'a pump casing 33 delimited by an annular rib 34 projecting from the inside and a sleeve connector 31a provided with a cylindrical bore 35 for sealingly receiving the delivery pipe 14 fitted, if necessary, with an O-ring 36.

The outer casing 17 has a shape complementary to that of the rotor casing 15, centered on the suction opening 18a, 16 and showing a part of sleeve 38 which surrounds the sleeve 19 and ends in a flange 39 which protrudes slightly beyond the bore 18b of the sleeve 19 to retain the O-ring 20 axially, without however coming into contact with the suction pipe 13. The casing 17 continues after the sleeve 38 by a central annular part 40 which is provided with external ribs 41 and capable of coming to bear axially, directly or as shown, by means of an internal annular rib 40a, on the convex central bearing surface 42 of the annular external face 43, here partially toric , of the rotor casing 15.

The annular part 40 continues, opposite the sleeve 38, by a partially toric connecting surface 44 followed by a connecting part 45 in the general shape of a cylindrical ring coming to surround the substantially cylindrical ring 22 of the rotor casing. 15. This part 45 presents cutouts to allow the outlet connections of the casing to lead to the outside 15. A cutout 37 (see FIG. 4) allows the drain fitting 30 to protrude outside. To accommodate the discharge fitting 31, there is provided a wider cutout 46 (see FIGS. 2 and 3) and between the cutouts 37 and 46, the connecting part 45 of generally cylindrical shape, is shaped into two substantially semi-cylindrical parts 45a and 45b (see the two parts indicated on the Figure 4) which end frontally with two flanges 47 and 48 constituting a front support part. The flanges 47 and 48 each have respectively an inner surface 49 and 50 forming a bearing surface intended to cooperate with the carrying surface 29 formed on the flange 28 of the rotor casing 15. In two diametrically opposite zones on each of the ledges 47 and 48 is provided, in one piece with the ledges, a respective tab or support 51, 52 provided with means of attachment to the rigid metal carcass 7 of the motor forming a support body. The fixing means consist here of a hole or bore 53, 54 for the passage of a fixing screw 55, 56 on corresponding lugs 57, 58 of the carcass 7 of the engine, using nuts 59, 60 The bores 53, 54 can be replaced by tapped holes directly receiving a fixing screw whose head is disposed on the side of the electric motor 4.

Each of the two substantially semi-cylindrical parts 45a, 45b of the connecting part 45 comprises at least one cylindrical fixing boss 61, 62, 63 (see the three bosses in FIG. 2) coming from one-piece molding with the corresponding connecting part 45a or 45b and with the central annular part 40 continues and reinforced by the ribs 41. Each fixing boss 61, 62, 63 has a central bore 64 substantially parallel to the rotor axis 65. The bore 64 of generally cylindrical shape, the if necessary with a screw engagement pilot hole 66, generally came from foundry with the outer casing 17 made of an aluminum alloy much stiffer than the rotor casing 15 but relatively softer than steel . Bore 64 is provided a thread into which engages a screw 67 for fixing the motor pump assembly to a support structure 68 such as a boiler body. Since the rotor casing 15 is made of a relatively soft material, it would be possible to provide smooth bores 64 in which a self-tapping screw would engage.

The assembly and operation of the motor pump assembly according to the invention will now be described. The entire electric motor being prepared and mounted, it is equipped with the pump rotor 1 mounted in cantilever at the end of the rotor shaft 2. The outer casing 17 comes to surround the rotor casing 15 which is thus positioned in rotation by engagement of the peripheral outlet fittings 30 and 31 in the corresponding cutouts 37 and 46. The outer casing 17 is positioned axially with respect to the rotor casing 15 by axial support of the annular rib 34 on the convex surface 42 of the outer annular face 43 of the casing 15. The bottoms of the cutouts 37 and 46 then come in close proximity to the outer surface of the corresponding fittings 30 and 31 without however coming into contact with them. At the same time, the flange 39 is placed in the immediate vicinity of the end of the sleeve 19 by axially trapping the O-ring 20. The bearing surfaces 49 and 50 also come in close proximity to the conical bearing surface 29 formed on the flange 28 of the rotor casing 15.

The rotor casing 15, thus equipped with its outer casing 17, is then carefully engaged on the rotor 1, taking care that its inner sleeve 16 engages well in the inlet bore 21 of the rotor. pump 1 to center the latter, and for the sleeve section 26 to engage inside the centering bore 7b up to the stop of the seal on the bearing face of the section 26 on the peripheral surface 24 for supporting the flange 9. The pressure chamber 69 containing the pump rotor 1 is sealed against the stator of the electric motor which is isolated from the rotor by the rotor tube 6 resting on the stator parts via two O-rings (seal 10 and seal 10a).

We can then tighten the mounting lugs 51 and 52 on the corresponding lugs 57 and 58 of the motor housing 7 by engaging the screws 55 and 56 in the corresponding holes 53, 54 and tightening them by the nuts 59, 60 The slight deformation, during tightening, of the substantially semi-cylindrical connecting parts 45a and 45b of the rotor casing 15, means that at the same time as the annular abutment surface of the rib 40a is applied to the domed central bearing surface. 42 of the annular outer face 43 of the rotor casing 17, the bearing surfaces 49 and 50 come to be applied firmly on the carrying surface 29 of the flange 28 thereby limiting the compression deformation of the cylindrical ring part 22 of the rotor casing 15, much more flexible and flexible than the outer casing 17.

The pump assembly thus mounted includes a flexible pump body inside, to cooperate well with the rotor 1, in a material resistant to the aggression of the transported liquid (here hot water) and not creating electrical torque with the pump rotor also made of composite plastic material (generally in two parts welded by friction with ultrasound). The outer casing 17 protects the rotor casing 15 against external mechanical attack and allows its rigid attachment to a support or a support structure, so as to support the external electric cantilever a great deal heavier than the pump.

To connect the pump assembly mounted according to the invention to its fluid inlet and outlet connections, the pump body can be engaged axially by its internal bore 18a on the suction pipe 13 already in place, the screws attachment 67 then being screwed into the threaded bore 64 corresponding to the bosses 61, 62 or 63 brought in front of these screws, to the engagement on the suction pipe 13. When the motor pump assembly is rigidly fixed in position on the suction line 13, it is then possible to engage a discharge line 14 provided with its O-ring seal 36, in the cylindrical bore 35 of the discharge connection 31. An annular seal could also be permanently installed in an annular groove formed inside the bore 35.

When the mounted pump is operating, it generates an overpressure in the pressure chamber 69 which tends to cause the rotor casing 15 to swell. Fortunately, in the embodiment according to the invention, the latter is surrounded directly, wherever have large sections capable of inducing high pressure stresses, by the rigid outer envelope 17. Only are subjected to the action of pressure without the reinforcement of the outer envelope 15, the peripheral connections 30 and 31 which have either extra thicknesses (connection 30), ie reinforcements and ribs (connection 31) allowing them to resist the action of pressure.

It is possible, in certain embodiments, to provide for manufacturing a first type of pump (for example, washing machine drain pumps) operating at low pressure and at moderate liquid temperatures and comprising only a rotor casing made of plastic and / or composite material, fixed to the carcass or the engine support by simple or easily removable means such as pivoting flanges or arches. A second type of manufactured pump uses the rotor casing made of plastic and / or composite material, reinforced by the monobloc outer casing according to the invention to convey fluids under pressures and / or at higher temperatures. The embodiment which has been shown for a single-stage pump with a single rotor can, of course, be used for multi-stage pumps with several rotors in series on the same motor shaft and the electric actuating motor 4 may be replaced by an engine of another type, for example, internal combustion.

Of course, the present invention is not limited to the embodiments described and shown, but it is susceptible of numerous variants accessible to those skilled in the art.

Claims (10)

1. Pressurised chamber body, in particular a pump body, consisting of a one-piece rotor casing (15) of generally annular shape centered on said rotor (1) and having: an inlet connector (18) discharging at the center of an outer annular face, at least one peripheral outlet connector (31) and an open face (23) designed to be closed off by abutment of a peripheral flange (28) against a support body, the said rotor casing (15) being reinforced by an outer casing (17) which is stronger and more rigid than said rotor casing (15) and which abuts against the latter, said outer casing (17) being adapted to bear axially, by means of a central annular portion (40) thereof surrounding said inlet connector (18), against the annular outer face (43) of the rotor casing (15) and to surround, at least partially, the periphery of said rotor casing (15) except for said peripheral outlet connector or connectors (30, 31), by means of a bridge portion (45) connecting a forward abutting portion (47, 48) and said central annular portion (40), characterized in that said forward abutting portion (47, 48) is provided with at least two tabs or lands (51, 52) designed to allow said outer casing (17) to be fixed onto said support body (7a) by applying, using fixing means such as screws (55, 56), said rotor casing (7) in a sealed manner, by means of said peripheral flange (23), to said support body (7).
2. Chamber body according to claim 1, characterized in that said tabs or lands (51,52) are each associated with bearing surfaces (49, 50) of said outer casing (17) on a load-bearing surface (29) provided at the outside of said peripheral flange (28) of said rotor casing.
3. Chamber body according to claim 1 or 2, characterized in that said outer casing is of a one-piece construction (17) and its bridge portion (45) carries at least two projecting bosses (61, 62, 63) for forward mounting of said outer casing on an external support (68).
4. Chamber body according to claim 3, characterized in 8that each mounting boss (61, 62, 63) includes a passage (64) substantially parallel to the axis of the rotor (65) and designed to receive a mounting rod means (67).
5. Pressurized chamber body according to any one of claims 1 to 4, characterized in that said bridge portion (45) of said outer casing has a bell-shape the central widened-out portion of which has at least one cut-out portion (37, 46) passing therethrough, which is open on the forward abutment edge (47, 48) and enables a peripheral outlet connector (30, 31) of the rotor casing to pass therethrough.
6. Pressurized chamber body according to any one of claims 1 to 5, characterized in that the central annular portion (40) of the outer casing (17) has passing therethrough an inlet connector (18) while surrounding said inlet connector with an open sleeve portion (38) which terminates externally at a flange (39) designed to surround the outer edge of said inlet flange, leaving a passage free for a connecting conduit (13) to said inlet connector (18).
7. Pressurized chamber body according to claim 6, characterized in that said flange (39) slightly overlaps, internally, an outlet passage (18b) provided in the inlet connector (18) whereby an annular sealing gasket (20) arranged in said outlet passage (18b) is maintained axially in place.
8. Pressurized chamber body according to any one of claims 1 to 7, said one-piece rotor casing (15) being made from a flexible material resistant to corrosion by the liquid pumped by said pump, for example a plastics material or a fiber-based composite material, characterized in that said rotor casing (15) is designed to contain a pump rotor (1) which is centered (sleeve 16) and guided on the internal outlet of said inlet connector (18), and in that said rotor casing (15) is devoid of all fixing means or all fixing accessory such as tabs or drillings, but has an outer flange face (23) designed to cooperate, in a sealed manner, with a mounting ring (7a) of the drive motor housing (7).
9. Pressurized chamber body according to any one of claims 1 to 8, characterized in that the outer casing (17) is of a one-piece construction obtained by casting a metal such as an aluminium alloy, designed to receive steel self-tapping screws.
10. A motor-driven pump assembly comprising a pump block with a rotor mounted in cantilever fashion on the shaft of a driving electric motor, and an electric motor block consisting of a rotor tube surrounding the rotor and the bearings thereof in a sealed manner, and a stator housed in a motor housing, characterized in that said pump rotor (1) mounted on said motor shaft (2) is housed inside a pressurized chamber body according to any one of claim 1 to 9 the outer one-piece construction casing (17) of which is rigidly fixed onto a crown (7a) of the motor housing (7) thereby applying, in a sealed manner, said rotor casing (15) against said motor housing (7) so as to define a pressurized chamber (69) containing said pump rotor (1) and the inside of said rotor tube (6).

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