FR2721357A1 - Electrically driven pump esp. for coolant of vehicular heat engine - Google Patents

Abstract

The pump includes a rotor having a winding (7) and a slip ring (8) positioned side by side on an axial shaft, with a primary magnetic coupling element (56). The coaxial pump turbine (19) carries a secondary magnetic coupling element (43) separated from the primary by a wall (30) of the casing. The rotor and the primary coupling elements are preassembled together for introduction as a unit into the casing where they are guided in rotation by a ball bearing (54). The primary coupling element forms a barrier between the contact faces of the slip ring and this bearing.

Description

Electric pump for engine coolant
The invention relates to an electrically driven pump for a fluid, in particular the coolant of a vehicle heat engine, comprising a housing containing an electric motor provided with a rotor, a turbine coaxial with the rotor and coupling means in contactless rotation comprising a primary element integral with the rotor and a secondary element integral with the turbine, separated from each other in a sealed manner to said fluid by a partition of the housing.

In a known pump of this kind, the rotor and the primary element (comprising in particular a magnetic material for magnetic coupling) are fixed, on either side of a transverse wall of the housing, on a rotary shaft which is guided by a bearing through this wall. The primary element of the coupling means is mounted on the shaft after the latter has been placed in the housing. The motor rotor, including this shaft, and the primary element must therefore be balanced separately, which complicates the production of the pump. In addition, when the rotor has a winding and a collector interposed between the winding and the primary element in the axial direction, the dust produced by the friction of the brushes on the collector causes fouling of the bearing, reducing its service life.

The object of the invention is to remedy these drawbacks.

The invention relates in particular to a pump of the type defined in the introduction, and provides that the rotor and said primary element belong to a sub-assembly capable of being introduced in a unitary manner in the housing.

Other characteristics, complementary or alternative, of the invention are set out below - The rotor comprises a winding and a collector interposed between the winding and said primary element in the axial direction, and said subassembly is guided in rotation by a first bearing close to its axial end situated on the side of the primary element with respect to the rotor, the primary element forming a barrier between the contact surfaces of the manifold and the first bearing.

- Said subassembly is guided in rotation by two bearings, namely said first bearing and a second bearing close to its axial end situated opposite the primary element relative to the rotor.

- The turbine comprises a hub made of a material with a low coefficient of friction, rotatably mounted on a stationary shaft fixed to said partition.

- Said stationary shaft passes through said partition to extend substantially over the entire axial length of the housing, and carries said first bearing and, where appropriate, said second bearing.

- The rotor and the primary element are fixed to an axial tube, mounted on the stationary shaft by means of said bearings located respectively at the two ends of the tube.

- Said stationary shaft is located on one side of said partition and the first bearing is a bearing, a ring is fixed to the face thereof facing the primary element.

- The outer and inner rings of said bearing are fixed respectively to the partition and to a rotary shaft belonging to said sub-assembly.

- The turbine and the housing are in mutual axial contact, on the side opposite the motor, by parts made of materials with a low coefficient of friction. This feature is useful especially in the case of a cooling fluid operating in the liquid state and in the gaseous state, the pressure developed by the pump, and consequently the axial force exerted by the turbine on the housing, being relatively high.

- The turbine comprises fins made of material with low coefficient of friction extending axially from a front face and ending with free edges which come into contact with a part of the end wall of the housing made of material with low coefficient friction, said wall portion defining with said front face a space in which the fluid is subjected to the thrust of the fins. This arrangement leads to a pump efficiency comparable to that of a closed turbine pump, while avoiding the technical complications linked to the production of such a turbine. In addition, the axial contact force between the turbine and the housing is thus distributed over a relatively large area, which further reduces the corresponding pressure and therefore wear. On the contrary, it is possible, if desired, to provide that the fins come into contact with the end wall of the housing only over a fraction of their radial length.

- Fins for the ventilation of the motor extend from said primary element, axially towards the latter and / or radially towards the outside.

- The motor has a brush holder supporting brushes in contact with the collector, connected to electrical supply terminals, the brush holder being able to be introduced into the housing by a lateral opening of the latter, after switching on. in place of said sub-assembly, and having for this purpose a notch for the passage of the latter.

- The housing is composed of three main parts, namely first and second parts in the form of cups whose bottoms are turned opposite to each other, externally limiting the pump and respectively housing the motor and the turbine , and a third part forming said partition.

- Said three parts are mutually assembled by means of flanges facing radially outwards, the flange of the third part being clamped axially between the first two parts, using the flange of at least one of these .

- The primary element comprises an active part radially surrounding the secondary element and connected to a hub, and the partition comprises a cylindrical part extending in the radial gap between the secondary element and said active part, and a radial part extending between the hub of the primary element on the one hand and the turbine and the secondary element on the other hand, said cylindrical part being connected to the flange of the third part by a connection wall which internally covers the region radially exterior of the second part and defines with the cylindrical part an annular channel housing said active part.

- Said connection wall and the wall of the second part, facing the latter, each have at least one air inlet opening opening into a gap between these two walls, the respective openings thereof being mutually staggered along the walls so as to limit the risk of liquid entering the housing.

- A baffle is fitted in said interval, between the two openings.

- A filter retaining impurities, in particular liquids and dust, is disposed in said interval, between the two openings.

The characteristics and advantages of the invention will be explained in more detail in the description below, with reference to the appended drawings, in which - FIG. 1 is a view in axial section of a pump according to the invention; - Figure 2 is a corresponding exploded view; - Figure 3 is an exploded perspective view, and partially in axial section, of another pump according to the invention; - Figures 4 and 6 to 8 are partial perspective and sectional views showing details of the pump of Figure 3, in different variants; and - Figure 5 is a perspective view of a variant of the primary element shown in Figure 3.

The pump illustrated in FIGS. 1 and 2 comprises a housing 1 composed of three main parts, namely two parts in the form of cups 2 and 3, coaxial and whose bottoms 4 and 5 are turned opposite one of the other, these two parts defining a substantially closed interior space, and an intermediate part 6. Part 2 houses an electric motor rotor comprising a coil 7 and a manifold 8 fixed side by side on an axial tube 9. The hub 10 of a primary magnetic coupling element 11 is also mounted on one end of the tube 9, in the immediate vicinity of the manifold 8.

At its opposite end, the tube 9 is guided in rotation, by a ball bearing 12, in a centering cup 13 itself fixed in a recess 14 in the bottom 4 of the part 2, this bottom being completely closed. A fixed shaft 15 extends inside the tube 9 and projects at the two ends of the latter. On the side of the bottom 4, the shaft is held by the cup 13. On the other side, it passes through a substantially radial wall 16 of the housing, formed by the part 6, and extends in overhang over- between the end of the tube 9 and the wall 16, the axial bore of the hub 10 has an enlargement which houses a ball bearing 17 whose outer and inner rings are secured respectively to the hub 10 and the 'shaft 15, and which cooperates with the bearing 12 to guide in rotation the rotary sub-assembly formed by the rotor 7, 8, the tube 9 and the primary element 11.

The primary element 11 forms a barrier preventing the dust produced by the friction of the brushes on the collector 8 from reaching the bearing 17. An O-ring seal 18 is disposed in an annular housing limited by the shaft 15, the partition 16 and the inner ring of the bearing 17.

A turbine 19 comprising a hub 20, a flange 21 and fins 22 is arranged so as to rotate freely on the cantilever region of the shaft 15. A washer 23 surrounding the shaft 15 is interposed between the partition 16 and an axial end of the hub 20. The flange 21 extends radially outward from the other axial end of the hub 20, and the fins 22 extend axially in the direction of the bottom 5 of the part 3, from the flange. The bottom 5 of the part 3 defines a recess 24 of short axial length, limited by a radial planar end wall 25, in a central opening 26 from which an axial fluid inlet pipe 27 opens. In this recess is housed a washer 28 made of a material with a low coefficient of friction such as a plastic material loaded with graphite, the outside diameter of which is substantially equal to that of the flange 21 and the fins 22. An annular seal 29 is interposed between the wall 25 and the washer 28. The turbine 19 is also made of a material with a low coefficient of friction, and the fins 22 come into contact with the washer 28 through the entire radial length of their free edges facing towards it.

The partition defined by the intermediate part 6 of the housing comprises, in addition to the radial part 16, a cylindrical part 30 extending towards the bottom 5 from the peripheral edge thereof. At its end opposite to the part 16, this part 30 is connected to a connection wall 31 provided with external ribs 32, which extends opposite the annular region of the bottom 5 located radially outside the depression 24, and facing the cylindrical side wall 33 of the part 3. The ribs 32 come to bear on the part 3 and ensure the mutual positioning of the two parts.

The wall 31 and the ribs 32 define with the annular region of the bottom 5 a peripheral pipe 34 collecting the fluid expelled by the rotation of the fins 22, and from which a tangential outlet pipe 35 originates. An O-ring seal 36 is disposed in an annular housing bounded radially inward by the wall 31, radially outward by the wall 33, and axially by two ribs 32. This seal, as well as the seal 18, prevent any leakage of the fluid to the outside the room reserved for him and which is delimited by rooms 3 and 6.

A flange 37 extends radially outward from the end of the wall 31 facing the part 2. This flange is clamped axially between two flanges 38 and 39 also extending outward from the edges free cylindrical side walls 40 and 33 of parts 2 and 3 respectively. For this purpose, the flange 39 has pins 41 which pass through holes in the flanges 37 and 38, and which can be deformed to produce an assembly by riveting, or else be threaded and receive tightening nuts. Each of the flanges 37, 38 and 39 may extend continuously over a large fraction of the circumference of the housing, or be formed by individual ears distributed along this circumference.

The primary coupling element 11 has a flange 41 which extends radially outwards from the hub 10, around the bearing 17, and a magnetic active part 42 extending axially in the direction of the bottom 5 from the peripheral region of the flange 41. The active part 42 can be made of ferrite, or a ferriteresin composite material, and can be secured by overmolding with the rest of the primary element. The active part 42 is located opposite the external face of the cylindrical wall 30 and cooperates with a secondary element 43 integral with the turbine 19 and surrounding the hub 20 thereof, opposite the internal face of the wall 30. The secondary element 43 can be made of the same materials as the active part 42, and can also be secured to the turbine by overmolding.

The side walls 33 and 31 of the parts 2 and 6 of the housing have recesses defining a lateral opening of the housing traversed by a brush holder 44. This comprises a radial plate 45 and a connection block 46. On the plate 45, located inside the housing, around the collector 8, are fixed unrepresented brushes which come into contact with the latter, and which are electrically connected to unrepresented supply terminals carried by the block 46. Like that of Figure 3 which will be described later, the plate 45 has a fork shape, the two branches, located on either side of the pump axis, each carry a brush. This fork shape allows the brush holder to be approached laterally from the unitary sub-assembly 7-8-9-11 previously balanced, during assembly of the pump, to bring the plate around the collector.

In a known manner, the motor also comprises permanent magnets 47 fixed on the internal face of the wall 40, around the winding 7.

The cylindrical wall 31 of the part 6 is crossed by an orifice 48 which opens in the interval 49 between the latter and the wall 33. One of the annular ribs 32, disposed axially between the orifice 48 and the opening 67 formed in the wall 33 for the passage of the brush holder 44, comes a short distance from the latter wall and thus constitutes a baffle in the passage of air between the outside of the housing and the orifice 48. The latter orifice , and this baffle, allow the entry of air into the housing for the ventilation of the engine, while limiting the risk of water entry.

In Figures 3 and following, the elements identical or analogous to the corresponding elements of Figures 1 and 2 are designated by the same reference numbers.

The partition of the intermediate part 6 of the housing comprises, in addition to the cylindrical wall 30, a solid radial wall 50, replacing the wall 16 provided with a central opening.

The shaft 15 is replaced by a shorter shaft 51, which extends from a central boss 52 of the wall 50, cantilevered towards the bottom 5 of the part 3. The tube 9 of the sub - rotary assembly is replaced by a solid shaft 53 whose end facing the turbine 19 is integral with the inner ring of a ball bearing 54, replacing the bearing 17 and whose outer ring adjusts inside d an annular rib 55 extending axially from the wall 50. The primary magnetic coupling element 56, having substantially the same configuration and the same arrangement as the element 11 of FIGS. 1 and 2, comprises a hub 57, a flange 58 and an active part 59 produced in a single piece of ferrite-resin composite material, the hub 57 being overmolded on a metal sleeve 60 itself force fitted on the shaft 53.

The washer 28 and the gasket 29 are replaced by an insert 61 forming the annular region, in contact with the fins 22 of the turbine 21, of the internal face of the base 5, this insert being made of resin loaded with graphite and secured by overmolding. with the rest of part 3, made of a non-graphitized plastic material having better mechanical strength.

The cylindrical side wall 33 of the part 3 is relatively thick and its free edge bears on the flange 37 of the part 6. The pins 41 are replaced by screws which pass through the flanges 38 and 37 of the parts 2 and 6 and are threaded into threaded holes 63 formed in the thickness of the wall 33, the heads of these screws resting on the flange 38.

The cylindrical side wall 31 of the part 3 also has a relatively large thickness, and the ribs 32 are eliminated. The seal 36 is housed in an annular groove in this wall.

FIG. 3 shows the two branches 64 of the plate 45 of the brush holder 44, on which the brushes 65 are mounted, which are connected by wires to supply terminals 66 carried by the block 46.

FIG. 4 shows a turbine 19 and a part 3 slightly modified compared to those of FIG. 3. The hub 20 of the turbine extends beyond the flange 21 in the direction of the bottom 5 of part 3, and comes to bear axial on a stop 70 disposed at the center of the inner end of the inlet pipe 27. The stop 70 is part of an additional piece of resin loaded with graphite, also comprising a sleeve 71 fitted in the pipe 27 and retained axially by an internal shoulder 72 thereof, and radial arms 73 connecting the stop 70 and the sleeve 71. The friction between the hub 20 and the stop 70 replaces that between the fins 22 of the turbine and the insert 61 of the Figure 3. The shaft 51 not shown, identical to that of Figure 3, is guided in rotation in a bore 74 of the stop 70 and is no longer overhanging.

FIG. 5 shows a primary magnetic coupling element 56 modified with respect to that of FIG. 3 by the addition of radial fins intended to produce an air flow in the housing for cooling the engine. More specifically, four fins 80 are diametrically opposite two by two, in two mutually perpendicular axial planes. Each of these fins has an L shape, one branch of which extends radially outward from the hub 57 and axially towards the motor from the flange 58, and the other branch of which extends radially outward starting from the active part 59. There is also shown a fin 81 extending only from the active part 59 and located at half angular distance between two neighboring fins 80. It is possible to also provide fins extending only on the motor side, in addition to or instead of fins such as 80 and / or fins such as 81.

In the variant illustrated in Figure 6, a bearing 90 for the shaft 51, arranged in the same way as the stop 70 of Figure 4, is formed in one piece with the cup 3 and is connected to the tubing 27 by radial arms 91. Furthermore, the outer face of the cylindrical wall 31 of the part 6 is hollowed out by an annular groove extending axially from the flange 37 to a small distance from the groove housing the seal 36, thus defining a gap 92 between this wall and the wall 33 of the part 3.

In this interval open on the one hand orifices 93 passing through the wall 33, on the other hand orifices 94 passing through the wall 31 and arranged, in the axial direction, between the orifices 93 and the free edge 95 of the wall 33. the air for the ventilation of the engine can enter the housing through the openings 93 and through the axial gap between the free edge 95 and the flange 37, then cross the gap 92 and the openings 94, by a tortuous path which makes difficult water penetration.

This water inlet is made even more difficult by the arrangement according to FIG. 7, in which each orifice 94 is associated with two ribs 96 which extend in the interval 92, from the wall 31 and substantially up to the wall 33, in respective radial planes framing the orifice 94. These ribs extend over a fraction of the circumference of the wall 31 and force the air to bypass them in the circumferential direction.

In the variant of FIG. 8, the ribs 96, belonging to part 6, are replaced by filters 97, arranged on the path of the air towards the orifices 94. These filters allow air to pass and retain the liquids or dust.

In a variant not shown of the pump according to the invention, the part 3 is made entirely of a material with a low coefficient of friction, which allows direct support of the blades of the turbine without having to use the washer 28 or the insert 61. In another variant, an axial stop for a turbine hub such as that of FIG. 4 is made of a material with a low coefficient of friction and is attached to a central bearing such as the bearing 90 of FIG. 6, belonging to part 3. The blades of the turbine can come into contact with the end wall of the housing over only a fraction of their radial length.

The embodiments described above only illustrate some of the possible associations of the characteristics of the present invention, with each other and with the characteristics known in the prior art. It is possible, according to the invention, to use each of the new characteristics independently of the others, or to implement different associations, insofar as it is understood that such dissociations or associations do not come up against technical impossibilities.

Claims (18)

Claims 1. Electrically driven pump for a fluid, in particular the cooling fluid of a vehicle heat engine, comprising a housing (1) containing an electric motor provided with a rotor (7, 8), a coaxial turbine (19) to the rotor and non-contact rotational coupling means comprising a primary element (11) integral with the rotor and a secondary element (43) integral with the turbine, separated from each other in leaktight manner against said fluid by a partition (16, 30) of the housing, characterized in that the rotor and said primary element belong to a sub-assembly (7, 8, 9, 11) suitable for being introduced in a unitary manner in the housing. 2. Pump according to claim 1, characterized in that the rotor comprises a winding (7) and a collector (8) interposed between the winding and said primary element in the axial direction, and in that said subassembly is guided in rotation by a first bearing (17) near its axial end situated on the side of the primary element relative to the rotor, the primary element forming a barrier between the contact surfaces of the collector and the first bearing. 3. Pump according to claim 2, characterized in that said subassembly is guided in rotation by two bearings, namely said first bearing (17) and a second bearing (12) close to its axial end situated opposite to the primary element with respect to the rotor. 4. Pump according to one of the preceding claims, characterized in that the turbine comprises a hub (20) made of a material with low coefficient of friction, rotatably mounted on a stationary shaft (15) fixed on said partition (16). 5. Pump according to claim 4, attached to one of claims 2 and 3, characterized in that said stationary shaft passes through said partition to extend substantially over the entire axial length of the housing, and carries said first bearing and the if necessary, said second bearing. 6. Pump according to claim 5, characterized in that the rotor and the primary element are fixed to an axial tube (9), mounted on the stationary shaft by means of said bearings located respectively at the two ends of the tube. 7. Pump according to claim 4, attached to one of claims 2 and 3, characterized in that said stationary shaft (51) is located on one side of said partition (50) and in that the first bearing is a bearing (54) of which a ring is fixed to the face of the latter facing the primary element. 8. Pump according to claim 7, characterized in that the outer and inner rings of said bearing are fixed respectively to the partition (50) and on a rotary shaft (53) belonging to said subassembly (7, 8, 53, 56) . 9. Pump according to one of the preceding claims, characterized in that the turbine and the housing are in mutual axial contact, on the side opposite the motor, by parts made of materials with a low coefficient of friction. 10. Pump according to claim 9, characterized in that the turbine comprises fins (22) of material with low coefficient of friction extending axially from a front face and ending with free edges which come into contact with an end wall part (28, 61) of the casing made of a material with a low coefficient of friction, said wall part delimiting with said front face a space in which the fluid is subjected to the thrust of the fins. 11. Pump according to one of the preceding claims, characterized in that fins (80, 81) for the ventilation of the motor extend from said primary element, axially towards the latter and / or radially towards the outside. . 12. Pump according to one of the preceding claims, characterized in that the motor has a brush holder (44) supporting brushes (65) in contact with the collector, connected to electrical supply terminals (66), the brush holder being adapted to be introduced into the housing through a lateral opening thereof, after the installation of said sub-assembly, and having for this purpose a notch for the passage of the latter. 13. Pump according to one of the preceding claims, characterized in that the housing is composed of three main parts, namely first and second parts (2, 3) in the form of buckets whose bottoms (4, 5) are turned opposite one another, externally limiting the pump and respectively housing the motor and the turbine, and a third part (6) forming said partition (16, 30). 14. Pump according to claim 13, characterized in that said three parts are mutually assembled by means of flanges (37, 38, 39) turned radially outwards, the flange (37) of the third part (6) being tightened axially between the first two parts (2, 3), using the flange (38, 39) of at least one of these. 15. Pump according to claim 14, characterized in that the primary element (11) comprises an active part (42) radially surrounding the secondary element (43) and connected to a hub (10), and in that the partition comprises a cylindrical part (30) extending in the radial gap between the secondary element and said active part, and a radial part (16) extending between the hub of the primary element on the one hand and the turbine (19) and the secondary element on the other hand, said cylindrical part being connected to the flange (37) of the third part by a connecting wall (31) which internally covers the radially outer region of the second part (3) and defines with the cylindrical part an annular channel housing said active part. 16. Pump according to claim 15, characterized in that said connection wall and the wall of the second part, facing the latter, each have at least one air inlet opening (48, 67) opening into an interval (49) between these two walls, the respective openings thereof being mutually offset along the walls so as to limit the risk of liquid entering the housing. 17. Pump according to claim 16, characterized in that a baffle (32, 96) is arranged in said gap (49, 92), between the two openings (48, 93, 94). 18. Pump according to claim 16, characterized in that a filter (97) retaining impurities, in particular liquids and dust, is arranged in said gap (92), between the two openings (93, 94).