Electric pump

Abstract

The invention relates to an electric pump (2) configured to be fluidically connected to a main dielectric fluid circuit, the pump (2) comprising: - an electric motor (4) comprising a stator (6) and a rotor (8), the rotor (8) being able to rotate about an axis of rotation (R), the stator (6) and the rotor (8) defining an air gap (10); - a pumping chamber (12) that houses a wheel (14) constrained to rotate with a rotor shaft (15), in particular a hollow rotor shaft, which is itself constrained to rotate with the rotor (8), the pumping chamber (12) defining a main flow path, in particular connected to the main dielectric fluid circuit; and - a secondary flow path (16) configured to allow the flow of a portion of dielectric fluid taken from the pumping chamber (12), this secondary circulation path (16) passing, in particular, into the air gap (10) between the stator (6) and the rotor (8).

Description

[0001] DESCRIPTION

[0002] Title: Electric Pump

[0003] [1] The invention relates in particular to an electric pump configured to be fluidically connected to a dielectric fluid circuit.

[0004] [2] An electric cooling pump is known for supplying coolant to cool a vehicle's internal combustion engine. The electric pump comprises an impeller, a rotor shaft to which the impeller is fixed, an electric motor with a stator and a rotor to drive the rotor shaft, a control circuit to operate the electric motor, and a pump housing that contains at least the control circuit and the electric motor. The coolant can circulate through the housing. Thus, the coolant circulates around the stator, the rotor, and the control circuit.

[0005] [3] The present invention aims in particular to improve pumps dedicated to a cooling fluid, of the dielectric fluid type.

[0006] [4] The invention relates to an electric pump configured to be fluidly connected to a main circuit of dielectric fluid, said pump comprising:

[0007] - an electric motor comprising a stator and a rotor, the rotor being rotatable around an axis of rotation, the stator and the rotor defining an air gap;

[0008] - a pumping chamber housing a wheel fixed in rotation to a rotor shaft, in particular hollow, itself fixed in rotation to the rotor, the pumping chamber defining a main circulation path, in particular connected to the main dielectric fluid circuit; and

[0009] - a secondary circulation path configured to allow circulation of a portion of dielectric fluid taken from the pumping chamber, this secondary circulation path passing in particular through the air gap between the stator and the rotor.

[0010] [5] The electric pump may also include one or more of the features described below, taken alone or in combination.

[0011] [6] Subsequently, the axial direction is oriented along the axis of rotation of the rotor.

[0012] [7] According to one aspect of the invention, the secondary circulation path passes through an internal axial conduit formed in the rotor shaft to send the dielectric fluid to the pumping chamber. [8] A portion of the secondary circulation path extends axially inside the rotor shaft, in particular from a first end of the rotor shaft to a second end opposite the first end.

[0013] [9] According to one aspect of the invention, the second end is located on the wheel side.

[0014]

[0010] Thus, the rotor shaft is hollow to form this internal axial conduit.

[0015]

[0011] According to one aspect of the invention, the wheel is a paddle wheel.

[0016]

[0012] According to one aspect of the invention, the pumping chamber includes a suction port for drawing dielectric fluid from the main dielectric fluid circuit into the interior of the pumping chamber, this suction port being in particular oriented along the axis of rotation of the rotor.

[0017]

[0013] The passage of the dielectric fluid through the air gap between the stator and the rotor ensures direct cooling of the electromagnetic part of the electric motor. This allows for the efficient dissipation of heat generated by electrical and magnetic losses.

[0018]

[0014] By arranging the return of the dielectric fluid in the pumping chamber via an internal axial conduit in the rotor shaft, particularly a hollow one, the invention makes it possible to take advantage of the significant pressure difference between the inlet and outlet of the dielectric fluid. This pressure difference promotes a higher cooling flow rate, even when the volume of fluid drawn from the pumping chamber remains moderate.

[0019]

[0015] The fact that the fluid passes inside the rotor shaft, especially a hollow one, maximizes thermal efficiency by bringing a larger internal surface into contact with the dielectric fluid.

[0020]

[0016] Integrating the secondary fluid circulation path into the rotor shaft, particularly a hollow one, optimizes the use of the internal space of the electric pump. This allows for the design of more compact electric pumps while maintaining high performance.

[0021]

[0017] The rotation of the rotor generates a centrifugal force that helps to move the dielectric fluid in the secondary circulation path. This maximizes the flow rate without requiring additional systems to move the dielectric fluid.

[0022]

[0018] According to one aspect of the invention, the suction port of the pumping chamber is located axially on a volute of the electric pump and is configured to allow axial admission of the dielectric fluid into the pumping chamber.

[0019] According to one aspect of the invention, the pumping chamber has a radially open discharge port, allowing the dielectric fluid to be expelled to the external main dielectric fluid circuit after it has been set in motion by the impeller.

[0023]

[0020] According to one aspect of the invention, the pumping chamber communicates with at least one bypass slot allowing a portion of the dielectric fluid to be taken to supply the secondary circulation path.

[0024]

[0021] The bypass slot(s) are formed in a fixed housing defining a motor compartment housing the electric motor

[0025]

[0022] The fixed housing comprises a hollow main body inside which the stator is mounted.

[0026]

[0023] The fixed housing includes a first cover closing the main hollow body.

[0027]

[0024] According to one aspect of the invention, the first cover forms a separation between the pumping chamber and the engine compartment.

[0028]

[0025] According to one aspect of the invention, the bypass slot(s) are formed in the first cover.

[0029]

[0026] According to one aspect of the invention, the first cover closes, in a non-watertight manner, particularly with respect to the pumping chamber, the main hollow body.

[0030]

[0027] According to one aspect of the invention, the bypass slots are arranged in the first cover.

[0031]

[0028] According to one aspect of the invention, the first cover comprises a cylindrical portion extending axially around the rotor shaft. This cylindrical portion is configured to guide the rotor in rotation. A hydrodynamic bearing or a graphite bearing may be provided for this purpose.

[0032]

[0029] The bypass slots have, in a transverse plane, a circular arc profile.

[0033]

[0030] According to one aspect of the invention, the secondary circulation path includes an inlet formed by the bypass slot(s) communicating with the pumping chamber, the bypass slot(s) being in particular located closer to the discharge port than to the suction port.

[0034]

[0031] The secondary circulation path can thus draw from the dielectric fluid already pressurized by the wheel.

[0035]

[0032] According to one aspect of the invention, the bypass slot(s) are oriented substantially parallel to the axis of rotation.

[0033] According to one aspect of the invention, the bypass slot(s) are positioned substantially opposite the air gap between the stator and the rotor.

[0036]

[0034] By positioning the bypass slots opposite the air gap, the dielectric fluid is directed straight to this area, ensuring efficient circulation within the air gap and minimizing pressure losses. This allows for optimal cooling of the stator and rotor components. The orientation of the orifices, substantially parallel to the axis of rotation, reduces turbulence in the dielectric fluid flow as it is drawn from the pump chamber to circulate through the air gap.

[0037]

[0035] According to one aspect of the invention, the rotor shaft has a plurality of radial inlet ports allowing the dielectric fluid to enter the internal axial conduit, this plurality of radial inlet ports being located in particular at one end of the rotor shaft which is opposite the pumping chamber.

[0038]

[0036] According to one aspect of the invention, the rotor shaft includes an axial outlet orifice located at its end on the wheel side, i.e. at the second end, the axial outlet orifice opening into the pumping chamber.

[0039]

[0037] According to one aspect of the invention, the rotor comprises a transverse wall.

[0040]

[0038] According to one aspect of the invention, the transverse rotor wall is located at an axial end of the rotor opposite the pumping chamber.

[0041]

[0039] According to one aspect of the invention, the axial end transverse wall of the rotor has one or more holes for passing through this transverse wall.

[0042]

[0040] The rotor shaft is fixed rotationally to the rotor radially inside this transverse wall.

[0043]

[0041] In particular, the rotor includes a skirt located radially inside the transverse wall, the rotor shaft being mounted rotationally fixed to the rotor inside this skirt.

[0044]

[0042] According to one aspect of the invention, the holes in the transverse wall allow the passage of dielectric fluid from an interior space of the rotor to the external side of this transverse wall.

[0045]

[0043] According to one aspect of the invention, the holes formed on the transverse wall of the rotor allow the dielectric fluid which has circulated in the internal space of the rotor to join the radial inlet ports of the hollow rotor shaft, to flow towards the internal axial conduit of the hollow rotor shaft of the rotor.

[0046]

[0044] In particular, the radial inlet ports of the rotor shaft are axially offset relative to the skirt.

[0045] Relative to the skirt, the radial inlet ports of the rotor shaft are located axially opposite the pumping chamber.

[0047]

[0046] According to one aspect of the invention, the rotor and stator are placed in an isolated space in a compartment receiving an electronic control board for the electric motor.

[0048]

[0047] According to one aspect of the invention, the space receiving the rotor and stator is isolated from the electronic board compartment by a sealed transverse separation wall.

[0049]

[0048] According to one aspect of the invention, the electric pump comprises a fixed housing defining a motor compartment housing the electric motor.

[0050]

[0049] According to another aspect of the invention, the engine compartment is configured to communicate fluidly with an electronic board compartment, in particular through a transverse wall.

[0051]

[0050] The transverse wall may be a separating wall, in particular a non-watertight one, between the engine compartment and the electronic board compartment and / or a support wall for an electronic board. When the transverse wall is a separating wall, it is referred to as a transverse separating wall.

[0052]

[0051] For example, one or more fluid inlet openings may be formed in the transverse wall, for the passage of dielectric fluid towards the electronic board compartment.

[0053]

[0052] According to one aspect of the invention, the separating wall is a wall of the hollow main body.

[0054]

[0053] According to one aspect of the invention, the separating wall forms a bottom of the hollow main body.

[0055]

[0054] According to one aspect of the invention, the fluid inlet openings are distributed around the axis of rotation of the rotor, in particular on a geometric circle centered on this axis of rotation of the rotor.

[0056]

[0055] According to one aspect of the invention, the fluid inlet ports, for the fluid inlet to the electronic board compartment, are 8 in number, by way of example.

[0057]

[0056] According to one aspect of the invention, the transverse separation wall has one or more fluid outlet openings configured to push the dielectric fluid from the electronic board compartment towards the radial inlet ports of the hollow rotor shaft.

[0058]

[0057] According to one aspect of the invention, the number of fluid outlet vents on the transverse separation wall is 3, by way of example.

[0058] According to one aspect of the invention, the fluid outlet vents on the transverse separation wall are formed in a convex area of ​​this transverse separation wall, located opposite the end of the hollow rotor shaft where the radial inlet ports to the internal axial conduit are located.

[0059]

[0059] According to one embodiment, on the engine compartment side, the end of the hollow rotor shaft where the radial inlet ports are located enters the cavity of the transverse separation wall formed by the domed area.

[0060]

[0060] The flow rate of dielectric fluid taken for internal cooling is, for example, 70 liters per hour.

[0061]

[0061] The fixed housing also includes a second cover to seal the electronic card compartment.

[0062]

[0062] Other features, details and advantages of the invention will become clearer upon reading the following description on the one hand, and several illustrative and non-limiting examples of embodiments given with reference to the accompanying schematic drawings on the other hand, in which:

[0063]

[0063] [Fig. 1] Figure 1 is a profile representation, in perspective, of an electric pump according to an example of an embodiment of the invention;

[0064]

[0064] [Fig. 2] Figure 2 is a partial perspective and cross-sectional representation of the electric pump of Figure 1;

[0065]

[0065] [Fig. 3] Figure 3 is a partial perspective representation of the electric pump of Figure 1;

[0066]

[0066] [Fig. 4] Figure 4 is a partial enlarged view of Figure 1;

[0067]

[0067] [Fig. 5] Figure 5 is a perspective and cross-sectional representation of an electric pump according to another embodiment of the invention;

[0068]

[0068] [Fig. 6] Figure 6 is a partial representation of the fixed housing of the electric pump of Figure 5;

[0069]

[0069] [Fig. 7] Figure 7 is an enlarged view of Figure 5.

[0070]

[0070] The features, variants, and different embodiments of the invention can be combined in various ways, provided they are not incompatible or mutually exclusive. In particular, variants of the invention may be conceived comprising only a selection of features, described hereafter in isolation from the other described features, if this selection of features is sufficient to confer a technical advantage and / or to differentiate the invention from the prior art.

[0071]

[0071] With reference to Figures 1 to 4, an electric pump 2 is seen, according to an example of an embodiment of the invention, said pump 2 being configured to be fluidly connected to a main circuit of dielectric fluid (not shown).

[0072]

[0072] Said pump 2 comprises:

[0073] - an electric motor 4 comprising a stator 6 and a rotor 8, the rotor 8 being rotatable around an axis of rotation R, the stator 6 and the rotor 8 defining an air gap 10;

[0074] - a pumping chamber 12 housing a bladed wheel 14, rotationally fixed to a rotor shaft 15, itself rotationally fixed to the rotor 8, the pumping chamber 12 defining a main circulation path, this main circulation path being connected to the main dielectric fluid circuit; and

[0075] - a secondary circulation path 16 configured to allow circulation of a portion of dielectric fluid taken from the pumping chamber 12, this secondary circulation path 16 passing through the air gap 10 between the stator 6 and the rotor 8.

[0076]

[0073] Subsequently, the axial direction is oriented along the axis of rotation R of the rotor 8.

[0077]

[0074] The secondary circulation path 16 passes through an internal axial conduit 18 formed in the rotor shaft 15 to return the dielectric fluid to the pumping chamber 12.

[0078]

[0075] A portion of the secondary circulation path 16 extends axially inside the rotor shaft 16, from a first end 20 of the rotor shaft 15 to a second end 22 opposite the first end 20. The second end 22 is located on the side of the blade wheel 14. Thus the rotor shaft 15 is hollow to form this internal axial conduit 18.

[0079]

[0076] The pumping chamber 12 includes a suction port 24 for drawing dielectric fluid from the main dielectric fluid circuit (not shown) into the interior of the pumping chamber 12, this suction port 24 being oriented along the axis of rotation of the rotor R.

[0080]

[0077] The passage of the dielectric fluid in the air gap 10 between the stator 6 and the rotor 8 ensures direct cooling of the electromagnetic part of the electric motor 4. This makes it possible to dissipate efficiently the heat generated by electrical and magnetic losses.

[0081]

[0078] By arranging the return of the dielectric fluid in the pumping chamber 12 via an internal axial conduit 18 in the hollow rotor shaft 15, the invention makes it possible to take advantage of the significant pressure difference between the inlet and outlet of the dielectric fluid. This pressure difference promotes a higher cooling flow rate, even when the volume of fluid drawn from the pumping chamber 12 remains moderate.

[0082]

[0079] The fact that the fluid passes inside the hollow rotor shaft 15 maximizes thermal efficiency by bringing a larger internal surface into contact with the dielectric fluid.

[0083]

[0080] The integration of the secondary fluid circulation path 16 into the hollow rotor shaft 15 optimizes the use of the internal space of the electric pump 2. This allows for the design of more compact electric pumps 2 while maintaining high performance.

[0084]

[0081] The rotation of the rotor 8 generates a centrifugal force which helps to move the dielectric fluid in the secondary circulation path 16. This makes it possible to maximize the flow rate without requiring additional systems to drive the dielectric fluid.

[0085]

[0082] The suction port 24 of the pumping chamber 12 is located axially on a volute 30 of the electric pump 2 and is configured to allow axial admission of the dielectric fluid into the pumping chamber 12.

[0086]

[0083] The pumping chamber 12 has a radially oriented discharge port 32, allowing the dielectric fluid to be expelled to the external (not shown) main dielectric fluid circuit after it has been set in motion by the impeller 14.

[0087]

[0084] The pumping chamber 12 communicates with a plurality of bypass slots 34, of which there are 4, allowing a portion of the dielectric fluid to be taken to supply the secondary circulation path 16.

[0088]

[0085] The bypass slots 34 are formed in a fixed housing 36 defining a motor compartment 36 housing the electric motor

[0089]

[0086] The fixed housing 36 comprises a hollow main body 38 inside which the stator 6 is mounted.

[0090]

[0087] The fixed housing 36 includes a first cover 40 closing the main hollow body 38.

[0091]

[0088] The first cover 40 forms a separation between the pumping chamber 12 and the engine compartment 36.

[0092]

[0089] The bypass slots 34 are formed in the first cover 40.

[0093]

[0090] The first cover 40 closes, in a non-watertight manner, the hollow main body 38 with respect to the pumping chamber.

[0091] The first cover 40 comprises a cylindrical portion 41 extending axially around the rotor shaft 15. This cylindrical portion 41 is configured to guide the rotor in rotation. A hydrodynamic bearing or a graphite bearing may be provided for this purpose.

[0094]

[0092] As illustrated in Figure 2, the bypass slots 34 have, in a transverse plane, a circular arc profile.

[0095]

[0093] The secondary circulation path 16 includes an inlet formed by the bypass slots 34 communicating with the pumping chamber 12, the bypass slots 34 being preferably located closer to the discharge port 32 than to the suction port 24.

[0096]

[0094] The secondary circulation path can thus draw on dielectric fluid already pressurized by the blade wheel 14.

[0097]

[0095] The bypass slots 34 are oriented substantially parallel to the axis of rotation R.

[0098]

[0096] The bypass slots 34 are placed substantially opposite the air gap 10 between the stator 6 and the rotor 8.

[0099]

[0097] By positioning the bypass slots 34 opposite the air gap 10, the dielectric fluid is directed straight to this area, ensuring efficient circulation in the air gap 10 and reducing pressure losses. This allows for optimal cooling of the stator 6 and rotor 8 components. The orientation of the orifices, substantially parallel to the axis of rotation R, reduces turbulence in the flow of the dielectric fluid as it is drawn from the pumping chamber 12 to circulate in the air gap 10.

[0100]

[0098] The rotor shaft 15 has a plurality of radial inlet ports 42 allowing the dielectric fluid to enter the internal axial conduit 18, this plurality of radial inlet ports 42 being located at one end of the rotor shaft 15 which is opposite the pumping chamber 12. This end 15 protrudes from the rotor 8.

[0101]

[0099] The rotor shaft 15 includes an axial outlet orifice 50 located at its end on the side of the blade wheel 14, i.e. at the second end 22, the axial outlet orifice 50 opening into the pumping chamber 12.

[0102]

[0100] In this embodiment, the rotor 8 comprises a transverse wall 60. The transverse wall of the rotor 60 is located at an axial end of the rotor 8 opposite the pumping chamber 12. The axial end transverse wall 61 of the rotor 8 has several holes 62 for passing through this transverse wall 60. The rotor shaft 15 is fixed radially to the rotor 8 inside this transverse wall 60.

[0101] In particular, the rotor 8 comprises a skirt 62 located radially inside the transverse wall 60, the rotor shaft 15 being mounted radially to the rotor 8 inside this skirt 62.

[0103]

[0102] The holes 62 in the transverse wall 60 allow the passage of dielectric fluid from an interior space of the rotor 8 to the external side of this transverse wall 60.

[0104]

[0103] The holes 62 formed on the transverse wall 60 of the rotor 8 allow the dielectric fluid which has circulated in the internal space of the rotor 8 to join the radial inlet ports 42 of the hollow rotor shaft 15 to flow towards the internal axial conduit 18 of the hollow rotor shaft 15 of the rotor 8.

[0105]

[0104] The rotor 8 and the stator 6 are placed in a space 70 which is isolated from the fixed housing 36. This space 70 is isolated from a compartment 72 receiving an electronic control board for the electric motor 74, called an electronic board compartment 72.

[0106]

[0105] As illustrated in particular in Figure 1, the space 70 receiving the rotor 8 and the stator 6 is isolated from the electronic board compartment 72 by a sealed transverse partition wall 80.

[0107]

[0106] As represented in the embodiment of Figures 5 to 7, the engine compartment 36 is configured to communicate fluidly with the electronic board compartment 72. Several fluid inlet openings 82 are formed in a transverse wall 84, for the passage of dielectric fluid towards the electronic board compartment 72.

[0108]

[0107] The transverse wall 84 is a separating wall, in particular non-watertight, of the engine compartment 36 and the electronic board compartment 72. It can also be a support wall for an electronic board 74. When the transverse wall 84 is a separating wall, it is referred to as a separating transverse wall 84.

[0109]

[0108] The separating wall 82 is a wall of the hollow main body 38 and forms a bottom of the hollow main body 38.

[0110]

[0109] The fluid inlet openings 90 are distributed around the axis of rotation R of the rotor 8, on a geometric circle centered on this axis of rotation R of the rotor 8.

[0111]

[0110] The fluid inlet ports 90, for the fluid inlet to the electronic card compartment 72, are 8 in number.

[0112]

[0111] The transverse separation wall 84 has three fluid outlet openings 92 configured to discharge the dielectric fluid from the electronic board compartment 72 to the radial inlet ports 42 of the hollow rotor shaft 15.

[0112] The fluid outlet openings 92 on the transverse separation wall 84 are formed in a domed area 94 of this transverse separation wall 84, located opposite the end of the hollow rotor shaft 15 where the radial inlet ports 42 to the internal axial conduit 18 are located.

[0113]

[0113] The flow entering the electronic board compartment is favored by the centrifugal force created by the rotation of the rotor.

[0114]

[0114] In general, the number of orifices, openings, their orientation and their dimensions allow control of the flow of fluid in the engine compartment and in the electronic board compartment.

[0115]

[0115] The flow rate of dielectric fluid taken for internal cooling is, for example, 70 liters per hour.

[0116]

[0116] The fixed housing 36 also includes a second cover 96 for sealing the electronic card compartment 72.

Claims

DEMANDS

1. An electric pump (2) configured to be fluidly connected to a main circuit of dielectric fluid, said pump (2) comprising: - an electric motor (4) comprising a stator (6) and a rotor (8), the rotor (8) being rotatable around an axis of rotation (R), the stator (6) and the rotor (8) defining an air gap (10); - a pumping chamber (12) housing a wheel (14) fixed in rotation to a rotor shaft (15), in particular hollow, itself fixed in rotation to the rotor (8), the pumping chamber (12) defining a main circulation path, in particular connected to the main dielectric fluid circuit; and - a secondary circulation path (16) configured to allow circulation of a portion of dielectric fluid taken from the pumping chamber (12), this secondary circulation path (16) passing in particular through the air gap (10) between the stator (6) and the rotor (8).

2. Electric pump (2) according to claim 1, wherein the pumping chamber (12) includes a suction port (24) for drawing dielectric fluid from the main dielectric fluid circuit into the interior of the pumping chamber (12), this suction port (24) being in particular oriented along the axis of rotation (R) of the rotor (8).

3. Electric pump (2) according to claim 1 or 2, wherein the secondary circulation path (16) passes through an internal axial conduit (16) formed in the rotor shaft (15) to return dielectric fluid to the pumping chamber (12).

4. Electric pump (2) according to any one of the preceding claims, wherein the pumping chamber (12) communicates with at least one bypass slot (34) allowing a portion of the dielectric fluid to be drawn to supply the secondary circulation path (16).

5. Electric pump (2) according to any one of the preceding claims, wherein the rotor shaft (15) has a plurality of radial inlet ports (42) allowing the dielectric fluid to enter the internal axial conduit (16), this plurality of radial inlet ports (42) being in particular located at one end (20) of the rotor shaft (15) which is opposite the pumping chamber (12).

6. Electric pump (2) according to the preceding claim, in which the rotor (8) has a transverse wall (60), the transverse wall of rotor (60) is located at an axial end of rotor (8) opposite the pumping chamber (12), the axial end transverse wall (61) of rotor (8) has one or more holes (62) for passing through this transverse wall (60), the holes (62) formed on the transverse wall (60) of rotor (8) allow the dielectric fluid having flowed in the internal space of rotor (8) to join the radial inlet ports (42) of the hollow rotor shaft (15), to flow towards the internal axial conduit (16) of the hollow rotor shaft (15) of rotor (8).

7. Electric pump (2) according to any one of claims 1 to 6, wherein the rotor (8) and the stator (6) are placed in an isolated space (70) of a compartment (72) receiving an electronic control board for the electric motor (74), the space (70) receiving the rotor (8) and the stator (6) is isolated from the electronic board compartment (72) by a sealed transverse partition wall (80).

8. Electric pump (2) according to any one of claims 1 to 6, comprising a fixed housing (36) defining a motor compartment (36) housing the electric motor (12), and the motor compartment (36) is configured to communicate fluidly with an electronic board compartment (72), in particular through a transverse wall (84) which is a separating wall (84), in particular not watertight, of the motor compartment (36) and the electronic board compartment (72) and / or which is a support wall for an electronic board (74).

9. Electric pump (2) according to claim 8, wherein one or more fluid inlet openings (90) are formed in the transverse separating wall (84), for the passage of dielectric fluid towards the electronic board compartment (72).

10. Electric pump (2) according to claim 8 or 9 and according to claim 5 or 6, wherein the transverse separating wall (84) has one or more fluid outlet openings (92) configured to discharge the dielectric fluid from the electronic board compartment (72) to the radial inlet ports (42) of the hollow rotor shaft (15).

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