Title of Invention

"ROTARY ELECTRICAL MACHINE"

Abstract Rotary electrical machine comprising, a rear bearing (4), a rotor (1) centred and fixed on a rotation shaft (2) supported by at least the rear bearing (4), the rear bearing (4) comprising radial cooling fluid discharcre slots (4a, 4d), a stator (3) surrounding the rotor, the stator comprising an armature winding (7) comprising windings constituting phases of the electrical machine, an electronic power circuit (15) connected to the windings of the stator phases, a heat dissipating bridge (16) comprising on the one hand a first face on which the electronic power circuit is mounted and on the other hand a second face opposite to the said first face and oriented towards the rear bearing, the said second face forming a longitudinal wall of a cooling fluid flow passage (17), another longitudinal wall of this passage (17) being formed by the rear bearing (4) supporting the stator, characterised in that the electronic circuit (15) comprise electronic components in the form of at least one power transistor and one control unit for the control of said transistor, said components being placed on tracks (25) supported on said heat dissipating bridge (16), and in that the second face of the heat dissipating bridge (16) comprises cooling means (18) disposed in the fluid flow passage (17) and provided for cooling said electronic components.
Full Text The present invention relates to rotary electrical machine.
Field of the invention
The invention concerns a device for cooling the power electronics integrated at the rear of a reversible electrical machine such as an alternator or an alternator/starter of a motor vehicle. The invention finds applications in the field of the automobile industry and in particular in the field of alternators and alternator/starters for motor vehicles.
Prior art
In a. motor vehicle the alternator transforms a rotation movement of the inducing rotor, driven by the thermal engine of tlie_ vehicle, into an electrical current induced in the armature winding of the multiphase stator. In general, this stator comprises three phase windings, so that the alternator is of the three-phase type. The three phases of the armature are connected to a bridge rectifier. This bridge rectifier comprises three arms, each comprising at least two diodes connected to each phase. However, these diodes generate heat. Conventionally, the bridge rectifier can dissipate an energy of around 150 watts. It must therefore be cooled in order to prevent any overheating of the diodes.
Figure. 1 depicts an example of the rear part of a conventional alternator. This alternator comprises a rotor 1 fixed to a rotation shaft 2, whose axis .of rotation is referenced A and

constitutes the axis of the machine, as can also be seen in the document DE A 197 05 228. This rotor 1 is surrounded by a stator 3 comprising a magnetic circuit 8 and an armature winding 7. The stator 3, via its circuit 3 and its winding 7, generates an alternating current. The armature winding comprises phase windings connected in star and/or delta mode. Each of these windings comprises an output connected to the bridge rectifier. The current generated in the stator 3 is rectified by means of the bridge rectifier comprising diodes 9. This stator 3 is supported by a rear bearing 4 and a front bearing (not shown). The rotation shaft 2 is held by two bearings by means of roller bearings 6. As described in the document. DE A 0 197 05 22 8, the magnetic circuit 8 comprises a stator body in the form of a packet of metal sheets which, in a known manner, comprises notches, advantageously of the semi-closed type, for mounting the windings of the phases passing through the stator body and extending on each side of the body in order to form leading-out wires. In this document there can be seen the front bearing of the alternator, as well as the pulley thereof, intended to be driven in rotation by the thermal engine of the vehicle via a transmission comprising at least one belt, and the internal fans carried by the rotor and located radially below the leading-out wires, for internal ventilation of the alternator. To do this the bearings, hollow in shape, have inlet and outlet slots in the manner described below. The rear fan, bearing the reference 5 in Figure 1, is advantageously more powerful than the front fan.
In this alternator, some of the dissipating elements, namely the positive diodes 9 of the bridge rectifier, are mounted in a bridge dissipating heat energy 10. This heat-dissipating bridge comprises openings lOa-lOd, also referred to as slots, in which the coolin.g air circulates.

The diodes 9 are electrically connected to a connector 14, which also comprises air passages 14a-14f.
In additional, the dissipating bridge 10 comprises, on its top face, fins 13 which assist the cooling of the dissipating
bridge 10.
More precisely, the alternator of Figure 1 comprises, in its rear part, a cover 11 surrounding and protecting power electronics of the alternator, corresponding in particular to the bridge rectifier. To allow the passage of the air inside the cover 11, the latter is provided with openings 12a-12d, also referred to as slots. These openings are placed principally in the top part of the cover 11. In addition, the rear fan 5 fixed to the rotation shaft 2 or to the rotor 1 sucks air inside the alternator. This fan may for example be of the centrifugal or outward-flow type. In this way, the air, sucked by the fan 5, enters the rear part of the alternator through the slots 12a-12d and, channelled by the fins 13, sweeps the dissipator 10 and the diodes 9 and, consequently, cools them. The air then leaves radially through the slots 4a-4d produced in the rear bearing 4 of the stator 3.
The air is therefore sucked principally in the axis of the alternator at the protective cover 11 and is then driven laterally through the slots of the rear bearing 4, cooling the bridge rectifier, but also the other hot parts of the alternator such as the leading-out wires of the armature winding 7.
For more information, the path travelled by the cooling air flow is shown, in Figure 1, by broken lines and arrows.

Reference can also be made to the document DE A 197 05 228 describing an example embodiment of the bridge rectifier as well as an example embodiment of the rotor in the form of a claw rotor. Document DE A 101 11 295 describes another type of bridge rectifier. In these two documents the negative diodes are carried by the rear bearing whilst being mounted on a plate fixed to the rear bearing or fitted therein, whilst the positive diodes are mounted on a plate, at a distance from the negative diodes. In the document DE A 100 11 295, this plate is provided with openings. This plate corresponds to the dissipator 10 in Figure 1, the diodes 9 being in the aforementioned manner the positive diodes.
Currently there also exist, reversible alternators, which can constitute an electric motor for driving the thermal engine of the vehicle in rotation via the shaft of the rotor fixed to the pulley of the alternator. Such a reversible alternator is referred to as an alternator-starter, or alternator/starter, and transforms the mechanical energy into an electrical energy, and vice versa. Thus an alternator/starter can start the engine of the motor vehicle, and constitute an auxiliary motor for assisting the thermal engine of the vehicle for driving the motor vehicle.
In this case the bridge rectifier situated at the output of the armature of the alternator/starter, that is to say connected to each phase of the armature, also serves as a bridge controlling the phases of the alternator/starter. This bridge rectifier has three arms, each comprising at least two power transistors of the MOS type. The transistors of this bridge rectifier are each controlled by a control unit. This control unit can be produced in various ways. Usually, this control unit comprises a driver associated with a comparator and other electronic

components . A bridge rectifier thus produced from power transistors and control units dissipates a lesser amount of energy than that dissipated by a diode bridge. This is because, when the bridge rectifier is functioning in rectifier mode, rather than in control mode, then the power transistors are controlled synchronously. For more information, reference can be made for example to the document EP A 1,134,886. However, the energy dissipated is all the same around 50 watts and the bridge rectifier must therefore also be cooled.
However, the control units as just described have relatively great bulk, so that mounting these control units and power transistors on a dissipating bridge leaves no more space, on the dissipating bridge, for slots. It is therefore not possible to cool the power transistor bridge by a circulation of air as shown in Figure 1.
In other words, the arrangement explained above requires producing axial air passages through the dissipating bridge and the connector, which reduces the space available for placing electronic components. In fact, this available space is sufficient to place a diode bridge rectifier but insufficient for larger power electronics. In particular, in the case of an alternator/starter, the power electronics are such that each diode on the bridge rectifier is replaced by at least one transistor and one control unit.
To resolve this problem of space, the patent application EP-A-l 03 2 114 proposes a device for cooling the power electronics of an alternator/starter, in which the dissipating elements consist of a base pressed on the rear bearing of the alternator/starter, this rear bearing comprising channels for the passage of the cooling air. In other words, in this

device, the dissipating bridge is pressed against the rear bearing which has, on its external rear face, cooling fins. The air therefore arrives laterally or radially and cools by convection firstly the rear bearing carrying the fins and secondly the dissipating bridge on which the power electronics are mounted. In addition, the dissipating bridge is also cooled by conduction by the fins on the rear bearing with which it is in mechanical contact.
However, in such a device, it is necessary for the dissipating bridge, or base, to be firmly pressed against the bearing so chat the cooling of the power electronics can take place. This is because, if any air gap exists between the base and the surface of the bearing, then the thermal conduction does not cake place, or takes place poorly between the base and the bearing, and consequently the cooling of the power electronics is only partial.
In addition, if the rear bearing is very hot, it will also be difficult to cool the dissipating bridge by convection.
Disclosure of the invention
One aim of the invention is to remedy the drawbacks of the techniques disclosed above and proposes an improved and more reliable device for cooling the power electronics of an alternator or alternator/starter of a motor vehicle, in which the cooling fluid is introduced laterally into the rear part of the machine and circulates in a flow passage for the fluid formed between the dissipating bridge and the rear bearing of the alternator.

To this end, the invention proposes a rotating electrical machine, in particular an alternator or an alternator/starter, for a motor vehicle, comprising:
- a rear bearing,
- a rotor centred and fixed on a rotation shaft supported by at
least the rear bearing,
- the rear bearing comprising radial cooling fluid discharge
slots,
- a stator surrounding the rotor,
- the stator having an armature winding comprising windings constituting phases of the electrical machine,
- an electronic power circuit connected to the windings of the stator phases,
- a heat dissipating bridge comprising on the one hand a first face on which the electronic power circuit is mounted and on the other hand a second face opposite to the said first face and oriented towards the rear bearing,
- the said second face forming a longitudinal wall of a cooling
fluid flow passage, another longitudinal wail of this passage
being formed by the rear bearing supporting the' stator,
in which the second face of the heat dissipating bridge comprises cooling means disposed, in the fluid flow passage.
In one embodiment the cooling means comprise fins.

In another embodiment the cooling means comprise columns, for example circular in cross-section or in a diamond shape.
By virtue of this arrangement it is possible to easily machine the free ends of the columns so that these columns, in one embodiment, come into contact with the rear bearing. These columns stiffen the heat dissipating bridge.
In a variant the second face of the dissipating bridge is profiled for example by means of a curved portion in order to divert the fluid and/or to create a venturi effect.
All combinations are possible.
For example, the columns can be combined with the fins, the cooling means comprising partly columns and fins.
Thus, the cooling means being mechanically fixed to the bridge carrying the power electronics rather than fixed to the rear bearing, the cooling of the power electronics is guaranteed whatever the heat produced by the rear bearing. This is because the device according to the invention makes it possibli to achieve thermal decoupling between rhe rear bearing and the dissipating bridge so that the heat cannot propagate by conduction. Likewise, according to the invention, the cooling by convection of the second face of the dissipating bridge cools power electronics comprising many electronic components.
The invention is advantageously supplemented by the following various characteristics, taken alone or according to all oossible combinations thereo'f:

the cooling means, such as the fins and/or columns, are
disposed radially in the direction of the flow of the cooling
fluid so as to reduce the pressure drops;
the cooling means, such as the fins and/or columns, form
cooling channels radially oriented so as to thoroughly cool th
dissipating bridge over its entire radial extent;
the rear bearing carries deflectors placed at the discharge
from the radial slots on the rear bearings so that the cooling
fluid which emerges through the radial or lateral slots on the
rear bearing are not taken up by the radially incoming flow of
cooling fluid. Thus looping back of the cooling fluid flow is
avoided;
- a protective cover covers the power electronics and the
dissipating bridge and comprises at least one raised end in
order to form a deflector;
- the protective cover comprises at least one opening for the passage of the fluid;
- at least one space between the rotation shaft and the dissipating bridge forms an axial fluid flow passage;
- the dissipating bridge forms a mezzanine above the rear
bearing of the stator;
- the dissipating bridge is fixed to the stator bearing by connecting tie-rods;
- the dissipating bridge is fixed above the rear bearing by means of studs secured to the rear bearing or to the

dissipating bridge;
- a layer of electrically insulating material is placed betweer
the dissipating bridge and the rear bearing;
- the axial ends of the fins and/or columns fixed to the
dissipating bridge are situated at a distance from the rear
^*-'- - the dissipator, comprising the cooling means, and the bridge
carrying the power electronics are in a single piece,-
- uhe dissipator, comprising the cooling means, is attached to the bridge carrying the power electronics in order to form a dissipating bridge in two parts;
- the power components are placed on tracks,-
- the tracks are fixed to the heat dissipating bridge;
- the tracks are electrically insulated from the heat dissipating bridge.
The columns and/or fins may consist at least partly of heat
pipes.
In one embodiment the rear fan comprises at least two superimposed parts, as described for example in the document FR A 2 741 912, for increasing the number of blades and the power of the fan.
The cooling means according to the invention comprise at least one projection directed towards the rear bearing and fixed to

the second face of the bridge.
Brief description of the figures
Figure 1, already described, depicts the rear part of a conventional alternator with a conventional cooling device.
Figure 2 depicts the rear part of an alternator/starter in which the introduction and discharge of the cooling fluid takes place laterally.
Figure 3 depicts the rear part of an alternator/starter with the mezzanine on which the power electronics are placed.
Figures 4 to 6, 8 and 10 are partial views from below of the bottom face of the heat dissipating bridge turned towards the rear bearing for various embodiments.
Figure 7 is a view of the cross section of a column, constituting a cooling means according to the invention, for a variant embodiment.
Figures 9 and 11 are views in section along the lines IX-IX and XI-XI respectively of Figures 8 and 10.
Figure 12 is a partial view in section of the mounting of the dissipating bridge on the bottom of the rear bearing.

Detailed descriptions of embodiments of the invention
In these figures the common elements will be allocated the same reference numbers.
Figure 2 depicts a side view in section of the rear of an alternator/starter comprising a cooling device according to the invention. Like all known alternator/starters, the alternator/starter depicted in Figure 2 comprises a rotor 1 fixed to a rotation shaft 2 of axis A. This rotor 1 is surrounded by the stator 3 provided with a body 8 in the form of a packet of metal sheets with notches through which the windings of the armature winding 7 pass. The stator 3 is supported by the rear bearing 4 and the front bearing (not shown), which holds the rotation shaft 2 by means of roller bearings 6 . The rotor is for example a claw rotor as described in the documents DE A 197 05 228 or EP A 0515 259, to which reference should be made for more information. In a variant this rotor has projecting poles, for example of the hybrid type with projecting poles, which alternate circumferentially with permanent magnets, as described in the document WO 02/0545S6, to which reference should be made.
As explained before the alternator/starter comprises a bridge rectifier with MOS power transistors, associated with control units, known as drivers, for these power transistors. This bridge rectifier and these control units form together the power electronics, referred to as the power electronic circuit of the alternator/starter referenced 15 in Figure 2. These electronics Or power circuit 15 are mounted on the top face, referred to as the first face, of a heat dissipating bridge 16 described below.

According to the invention, the bottom face, referred to as the second face, axially oriented towards the rear bearing 4 of the electrical machine of this heat dissipating bridge 16, forms a wall of a longitudinal, or radial, passage 17 for flow of the cooling fluid in the alternator/starter. The other wall of this passage 17 is therefore formed by the top face of the rear bearing 4 described below.
According to the invention, the protective cover 11 comprises openings 17 situated opposite the flow passage 17. These openings communicate with the external periphery of the passage 17. in this way, the cooling fluid, in particular the air, is introduced into the rear of the alternator/starter through these openings 19 and then circulates in the passage 17, below the dissipating bridge 16, cooling the power electronics 15. A rear fan 5, fixed to the rotation shaft 2 or to the rotor 1, provides the suction of the air inside the passage 17. The openings 19 are advantageously distributed circumferentially in a regular manner at the external periphery of the cover 11.
Thus produced, the heat dissipating bridge 16 forms a mezzanine above the rear bearing 4. Figure 3, which depicts a profile view of the cooling device of the invention, clearly shows this mezzanine. This Figure 3 will be described in detail subsequently.
According to the invention the dissipating bridge 16 comprises, on its bottom face, cooling means 18.
In other words the bottom face of the bridge 16 is configured so as to form cooling means 18.

These cooling means are disposed in the passage 17 and provide the flow of cooling liquid along a chosen path, that is to say so that the fluid enters as close as possible to the rotation shaft in order best to sweep the bottom face of the dissipating bridge. Thus the bottom face of the dissipating bridge is cooled over the entire radial distance situated between the external periphery and the internal periphery close to the shaft, of the dissipating bridge.
In Figure 3 the dissipator 16 has a U shape. This dissipator 16 therefore has two arms 161, 162 and a head 163 connecting together the arms 161, 162.
A central axial passage 22, delimiting the internal periphery of the dissipator, is present between the two arms 161, 163. This passage is also delimited by the internal periphery 165 of che head 163. This central passage 22 has the axis A pass through it and is sized so as to be greater than the size of the shaft 2.
By virtue of this passage 22 the fluid enters as close as possible to the shaft 2 in the manner described below.
In this Figure 3 this dissipator is hollow in shape so that it has a U shaped bottom 160 whose periphery is delimited by a rim 166 here perpendicular to the bottom 160 oriented transversely with respect to the axis A.
The axial passage 22 is thus in the form of a channel.
In Figure 2 and 3 the cooling means consist of cooling, fins 18.
The adjacent fins form radial channels guiding the cooling

fluid in the passage 17 communicating with the passage 22.
These channels are splayed going from the internal periphery of the dissipator 16 to the external periphery thereof. These internal and external peripheries of the dissipator 16 delimit the passage 17 in association with the rear bearing 4. The fins are here radially oriented with respect to a centre defined by the axis A and here have a constant height.
Thus these channels comprise a bottom face formed by the rear bearing, the two facing sides of two adjacent fins and the U-shaped bottom 160 of the dissipating bridge formed between two adjacent fins. Advantageously the dissipator, comprising the fins, and the bridge carrying the power electronics, are in a single piece, thus forming a single-piece dissipating bridge.
The fins are for example moulded in one piece with a dissipating bridge and are advantageously thin in order to increase the number of them and improve the heat exchange surface here with the air.
In a variant, the dissipator can be attached to the bridge carrying the power electronics, thus forming a dissipating bridge in two parts. This fluid is then discharged through slots 4a-4d produced in the rear bearing 4 . These slots 4a-4d are preferably identical to those produced in an alternator bearing, like the one shown in Figure 1. Advantageously, the fins 18 are disposed radially in the direction of flow of fluid concentrated towards the central slots 4b and 4c on the hollow shaped rear bearing 4.
More precisely, this bearing 4 has a bottom 40 with a central hole for passage of the shaft 2. This bottom has a housing for

mounting the ball bearing 6 supporting the shaft 2 and is extended at its external periphery by an annular rim 41. The bottom 40 and rim 41 are respectively transversely and axially oriented with respect to the axis A.
The aforementioned top face of the bearing 4 is therefore formed by the top face of the bottom 40, which constitutes one of the walls of the passage 17.
The rim 41 carries the body 8 of the stator 3 internally.
The central slots 4b, 4c belong to the bottom 40, whilst the other slots, namely the lateral or radial slots 4a, 4d, belong to the rim 41.
In this Figure 3 only one 4b of the central slots and one 4a of the lateral slots have been referenced. The central slots, close to the central opening in the bottom 40, are in the form of a window, whilst the lateral slots are oblong in shape and located radially below the part, referred to as the leading-out wiire, of the windings of the armature winding 7 projecting with respect; to the body 8 . By virtue of these lateral slots the winding is therefore well cooled.
Thus, in the invention, the air (or any other cooling fluid) is sucked laterally through the openings 19 in the alternator/ starter and flows towards the central slots 4b and 4c of the bearing 4 whilst sweeping the cooling elements of the dissipating bridge, that is to say the fins 18, over their entire length before being discharged through the lateral slots 4a and 4d of the bearing 4. Thus the power electronics 15, or
ely the components thereof, are cooled by conduction, after cooling of the dissipating bridge 16, via the

cooling means 18, here in the form of fins 18.
In addition, as the dissipating bridge 18 and the power electronics or electronic circuit 15 are at a distance from the rotation shaft. There exists, between this rotation shaft 2 and the dissipating bridge 16, a space 22 through which the air can. also circulate. This space 22 forms an axial fluid flow channel. According to one embodiment of the invention central slots 23a and 23b are produced in the protective cover 11. Air is then sucked through these slots 2 3a and 2 3b into the alternator/starter, and then flows through the space 22 along the rotation shaft 2 and rejoins the flow passage 17 under the dissipating bridge 16. In this way, the power electronics are cooled on the one hand laterally by the passage 17 and on the other hand axially by the space 22 . This flow of supplementary axial air passing through the space 22 also makes it possible to obtain much better cooling of the internal parts of the alternator, such as the ball bearings 6 and the leading-out wires for the windings of the armature winding 7, by an increase in the total air flow in the machine.
The path for the flow of cooling fluid at the rear of the alternator/starter is shown by the arrows and dotted lines, in Figure 2.
According to a preferred embodiment of the invention, deflectors 24 are placed downstream of the slots 4a and 4d produced in the rear bearing 4, or more precisely in Figure 2 axially downstream of the rear edge 42 of the slots 4a and 4d close to the bottom 40. These deflectors 24 make it possible to distance the inlet fluid flow from the outlet fluid flow so that the fluid emerging from the alternator/starter is not immediately re-introduced into the passage 17. Significant

recirculation of hot fluid coming from the inside of the' alternator/starter is thus avoided.
These deflectors 24, placed at the outlet from the lateral slots 4a and 4d in the bearing 4, are carried by the rear bearing. Thus, in one embodiment, the deflectors can be fixed co the bearing 4, close to the lateral slots 4a and 4d in the bearing. They can also be carried by the rear bearing whilst being produced in the protective cover 11, for example, by raising the free end of the protective cover, as depicted in Figure 2.
This cover, carried by the bearing 4 and advantageously made from plastics material, is hollow in shape like the rear bearing 4. It therefore comprises (Figure 2) a bottom 110, transversely oriented with respect to the axis A, extended at its external periphery by an annular rim 111 axially oriented with, respect to the axis A.
The central slots 23a and 23b are produced in the bottom 110 whilst the openings 19, in the form of slots, are produced in the rim 111.
The deflectors 24 are here connected together in order to form the free end of the splayed-shape rim 111, which makes it easy to mount the cover on the rim of the rear bearing. The base 124 of this end 24, facilitating the mounting of the cap 11, is located axially, here slightly recessed with respect to the front edge 43 of the slots 4a, 4b. This base 124 is therefore located axially between the edges 42, 43. In a variant the free end of the rim" comprises an alternation of splayed, that is to say raised, portions at the outlet from the slots 4a, 4b and not raised or bevelled portions for facilitating the

mounting of the cover. In a variant the rim 111 of the cover has a rim projecting radially and profiled according to the casing of the vehicle engine in order to form a deflector. This rim, forming a partitioning means, is placed upstream of the slots and downstream of the openings as described in the document EP A 0 740 400.
In the embodiment of the invention depicted in Figure 2, the protective cover 11 encloses the entire rear part of the alternator/starter, that is to say it encloses the power electronics 15 mounted on the dissipating bridge 16 and all the rear bearing 4. In this case, the protective cover 11 can comprise slots situated downstream of the lateral slots of the rear bearing and intended to allow the fluid to discharge out of the alternator/starter. It can also comprise, in addition to or in place of these slots, one or more deflectors -24 opposite the lateral slots 4a, 4d. These can be produced in the cover itself.
The protective cover 11 can also enclose the power electronics mounted on the dissipating bridge and the top part of the bearing 4, that is to say it does not enclose the lateral sides of the bearing comprising the slots 4a and 4d. In this case, the deflectors can be fixed to the bearing 4 or be produced by raising the free end of the cover.
According to one characteristic, the dissipating bridge 16 is fixed to the rear bearing 4 by means of tie rods or assembly bolts 20. According to one embodiment, the tie rods or assembly bolts, in general terms the assembly means 20, are the same as those used for normally fixing the bearing 4 to the magnetic circuit 8 of the stator 3, that is to say the same tie rods as those shown in Figure 1. These tie rods, for example

in the form of long screws, are visible for example in Figure 1 of the document EP A 0515 25 9.
In another embodiment of the invention the dissipating bridge 16 is fixed to the bearing 4 by means of fixing studs 21. These fixing studs can be fixed to the dissipating bridge 16 or to the bearing 4.
Figure 3 depicts, in profile, the cooling device of the alternator/starter, alone. In other words, the rotor, the stator and the rotation shaft are not. shown in this Figure 3 . There can therefore be seen, in this Figure 3, the rear bearing 4 with the dissipating bridge 16, which forms a mezzanine above the bearing 4. In the embodiment in this figure, the mezzanine is fixed to the bearing 4 by means of fixing studs 21. These fixing studs are at least two in number. They are distributed between the fins 18. The studs 21 are located close to the external periphery of the plate 40, that is to say radially above the central slots 4b.
In this Figure 3, it can clearly be seen that the fins 18 are axially shorter than the studs and that they are not in physical contact, or in electrical contact, with the rear bearing 4. For example, a space of 2 mm may separate the axial ends of the fins 18 and the bottom 40 of the rear bearing 4.
In the example in Figure 3, the dissipating bridge 16 constitutes approximately 3/4 of the surface of the bottom of the bearing 4, around the rotation shaft. On the top face of this bridge 16, the components 15 constitute the power electronics of the alternator/starter. It should be noted that -he surface of the dissipating bridge can vary according to the number and size of the components to be mounted.

"With the arrangement of the cooling device which has just been described, it is possible to connect the alternator and the bridge rectifier each to an earth which may be different for each one.
In addition, the electrical machine may comprise a layer of electrically insulating material, placed between the bottom face of the dissipating bridge and the rear bearing, in order to prevent any risk of electrical contact between these two elements. Advantageously, this layer of insulating material is fixed to the external face of the rear bearing and also comprises air passage slots facing those of the rear bearing for the cooling fluid to pass.
According to one embodiment, the electronic components 15 are placed on conductive tracks 25, 26. These tracks 25, 26 are isolated from the dissipating bridge, for example with alumina.
For example, use is made of an isolated metallic substrate consisting of a metallic sole plate covered with a polymer insulant and then a sheet of conductive material, such as copper, which is then etched in order to form the isolated electrical circuit. Then alumina is interposed between the dissipator and the isolated substrate. For more information reference should be made to the document EP A 1 032 114.
Here a single track 26 carries the electronic components in the form of chips, referred to as positive chips, defining the positive half bridges as described in the aforementioned document EP A 1 032 114. This track 26, in a U shape, is extended by a tongue 2 7 conformed so as to form the positive terminal of the alternator/starter. The tracks 25 each carry

the chips, referred as negative chips, defining a negative half bridge and are conformed so as each to have a crimping lug 2 8 serving for fixing the relevant winding of the armature winding. The chips, such as transistors of the MOSFET type, are connected by cabled connections. The negative chips are connected to earth. The negative terminal is not visible. Nevertheless, advantageously the bridge of the rear bearing is electrically isolated in order to prevent interference when the alternator is functioning in electric motor mode.
All this depends on the application.
The cooling device for an alternator/starter which has just been described can also be used in a conventional alternator. This is because the device according to the invention can also advantageously be used when the rear bearing releases a great deal of heat. In this case, in order to properly cool the power electronics, limited here to the bridge rectifier, the device according to the invention makes it possible to achieve thermal decoupling between the rear bearing and the dissipating bridge so that there is no heat exchange by conduction between the dissipating bridge and the rear bearing of the alternator. It can, in general terms, be implemented for any type of alternator, comprising in particular a rotor with claws or projecting poles.
Naturally the present invention is not limited to the example embodiments described.
In particular arrangements can be adopted for reducing pressure drops in the passage 17 and avoiding in particular recirculations of fluid within this.

Thus in a variant the fins 18 are axially of decreasing height For example, the fins 18 are higher axially at the internal periphery of the passage 17 then at the external periphery of the passage 17 in order to have an air flow speed which is as constant as possible.
In variants between two consecutive fins belonging to a first series of fins extending from the external periphery to the internal periphery of the passage 17, there is provided at least one radially shorter fin.
In a variant at least some of the fins 18 are split so that a circulation of air is created between the two faces of one fin 18 going from the side where the static pressure is the highest to the side where it is the lowest. In this way a shedding of the limit layer of cooling fluid, here air, and recirculations of this fluid in the opposite direction, are prevented.
Pressure drops are thus reduced and the cooling of the dissipating bridge 16 is improved.
The slits are straight or inclined with respect to the bottom 160 of the dissipator 16. The fins are thus in one variant divided into at least two parts.
The fins can have a sinuous shape.
At least some of the fins can be replaced by columns so that the cooling means can comprise fins and columns.
A11 combinations- are possible as can be seen in Figures 4 to

Thus in Figure 4 two radially oriented fins can be seen at 18 delimiting a passage channel 17 according to the invention. Between these two consecutive fins 18 belonging to a first series of fins there is at least one fin 181, here three fins, belonging to a second series of radially shorter fins.
The fins 181 are located at the external periphery of the passage 17. Other fins 182 are located at the internal periphery of the passage 17 between the two consecutive fins 18. These fins, here three in number, are roughly radially aligned with the fins 181 so that slits exist between the fins 181, 182 roughly radially aligned.
These slits are thin in one embodiment. Here the slits are wide so that two circumferential rows 281, 2 82 of columns are located radially between the fins 181 and 182. These columns are located on two circumferences and are here circular in cross section, or in a variant oval in cross section or in the shape of a diamond, as can be seen at 381 in Figure 2, in which the air path is depicted by an arrow. These fins are mounted so as to be staggered.
In a variant, as can be seen in Figure 5, the consecutive fins 18 0 in the first series of fins have a sinuous shape, here curved, to create a venturi effect and optimise the speed of the air flow.
In this case the number of fins 182, 2 82 is reduced, whilst the number of fins 181, 281 is increased. The entry to the passage 17 between the fins 18 has circumferentially a dimension greater than the exit from this' passage.
All these arrangements make it possible to improve the heat

exchange surface of the dissipator with the air and to correctly manage the flow of air under the power electronics. In addition this facilitates the manufacture of the bridge 16 since this bridge does not have recourse solely to thin fins.
Naturally the cooling means can comprise solely columns 481 as can be seen in Figure 6.
These columns, here circular in cross section, can be radially aligned or circumferentially offset like the columns in the rows 281, 282 in Figure 4 and as can be seen at 581 in Figure 8. In a variant the columns are rectangular in cross section. This amounts in these cases to dividing each fin 18 into a plurality of parts separated from one another by slits.
It will be appreciated that the columns reinforce the mechanical strength of the dissipator. With columns it becomes possible to machine the free ends thereof so that in one embodiment the columns are in contact with the bottom 4 0 of the bearing 4. This contact is direct or in a variant indirect, a thermally insulating layer, visible for example at 50 in Figure 12, being interposed between the free ends of the columns and t:he bottom 4 0 of the rear bearing 4.
Some of these columns can constitute the studs 21 in Figure 3, so that a clearance can exist between the bottom 4 0 of the bearing 4 and the free ends of these other columns.
Naturally the bottom of the dissipator 16, or more precisely the bottom face thereof turned towards the bottom of the rear bearing, can comprise at least one curved portion as can be seen at 280 in Figures 10 and 11, in order to divert the air and create a venturi effect in the passage 17 in order to

optimise the speed of flow of the air.
This arrangement is another form of the cooling means according to the invention.
The columns in one embodiment do not have the same cross
section.
Some of the columns can be internally hollow, as can be seen at 681 in Figure 12, so that this column constitutes one of the fixing studs 21 of Figure 3. This stud may have the tie rods or the assembly screws 20 of Figure 2 passing through it.
Some of these columns can consist, of heat pipes having a condensation area located in the passage 17 and an evaporation area absorbing heat and in contact with the bottom face of the dissipator 16.
This heat pipe is internally hollow and is provided with a chamber enclosing a pressurised fluid, such as water. The chamber of the heat pipe is for example made from copper or stainless steel or nickel. This heat pipe takes off heat at the dissipator, passing from a liquid state to a gaseous state. It restores the heat in the passage 17.
Naturally the dissipator 16 is in a variant in the shape of a horseshoe or in the shape of a ring.
In a variant the dissipator can carry the voltage regulator and/or drivers for controlling the electronic components 15, such as chips in the form of transistors, belonging to a bridge rectifying the alternating current produced by the stator 3 into DC current, this bridge also in the aforementioned manner

being a control bridge when current is injected into the components 15 under the control of the drivers.
The arms of this bridge can form modules with their associated driver. In general terms the electronic power circuit 15 comprises several components and several parts.
One or more drivers can be provided. For example, there exists a single driver controlling all the chips constituting controlled switches. In a variant there exists one driver per chip to be controlled or one driver per arm of the bridge. The dissipator thus carries, in one embodiment, all the power part of the unit actuating and controlling the alternator/starter, that is to say the chips and the driver or drivers. The control and management part and the voltage regulator controlling the excitation winding of the rotor being mounted in an external housing.
The electronic circuit 15 can be mounted on the dissipating bridge as described in the document WO 03/051095, to which reference can be made. Thus this circuit comprises metallic tracks, for example made from copper, intended to receive the chips. Resin, for example of the thermoplastic type, is injected, leaving visible, by virtue of a mould, parts accessible at the bottom and top faces of the tracks for in particular mounting the chips on the top face of the tracks. The accessible bottom face of the tracks is in line with the chips.
Next a heat conducting and electrically insulating element is interposed between the tracks and the dissipator 16. This element may be epoxy resin or polyamide having adhesive faces. In a variant it is the case of a heat-conducting adhesive

comprising glass balls.
Next a protective cover is mounted.
It will be appreciated that the rear bearing is not modified profoundly compared with the one in Figure 1. This bearing has no housing for mounting negative diodes and possibly comprises studs for fixing the bridge.
The cooling means are here of the mechanical type and comprise at least one projection belonging to the second face of the dissipator 16 and mounted in the passage 17.




We claim:
1. Rotary electrical machine comprising:
- a rear bearing (4),
- a rotor (1) centred and fixed on a rotation shaft (2) supported by at least the rear bearing (4),
- the rear bearing (4) comprising radial cooling fluid discharge slots (4a, 4d)
- a stator (3) surrounding the rotor,
- the stator comprising an armature winding (7) comprising windings constituting phases of the electrical machine,
- an electronic power circuit (15) connected to the windings of the stator phases,
- a heat dissipating bridge (16) comprising on the one hand a first face on which the electronic power circuit is mounted and on the other hand a second face opposite to the said first face and oriented towards the rear bearing,
- the said second face forming a longitudinal wall of a cooling fluid flow passage (17), another longitudinal wall of this passage (17) being formed by the rear bearing (4) supporting the stator,
characterised in that the electronic circuit (15) comprise electronic components in the form of at least one power transistor and one control unit for the control of said transistor, said components being placed on tracks (25) supported on said heat dissipating bridge (16), and in that the second face of the heat dissipating bridge (16) comprises cooling means (18) disposed in the fluid flow passage (17) and provided for cooling said electronic components.
2. Rotary electrical machine as claimed in claim 1, wherein the cooling means (18) are disposed radially in the direction of the flow of cooling fluid.
3. Rotary electrical machine as claimed in claim 2, wherein the cooling means comprise cooling fins (18).
4. Machine as claimed in claim 3, wherein the cooling fins (18) form

radially oriented cooling channels.
5. Rotary electrical machine as claimed in claim 2, wherein the cooling means comprise columns (281, 282, 481, 381, 481, 581, 681).
6. Machine as claimed in claim 5, wherein the cooling means comprise fins and columns.
7. Machine as claimed in claim 5, wherein some of the columns (681) constitute studs for fixing the heat dissipator (16) to the rear bearing (4).
8. Rotary electrical machine as claimed in claim 2, wherein the cooling means are formed by means of at least one curved portion (280) of the second face of the dissipator.
9. Rotary electrical machine as claimed in claim 1, wherein the rear bearing comprises a bottom (40) forming one of the walls of the fluid flow passage (17) in that this bottom (40) is extended at its external periphery by rim (41) provided with lateral slots (4a-4d) and in that the rear rearing carries at least one deflector (24) placed at the outlet from the lateral slots (4a—4d) on the rim (41) of the rear bearing (4).
10. Rotary electrical machine as claimed in claim 8, wherein it comprises a hollow-shaped protective cover (11) covering the electronic power circuit (15) and the dissipating bridge (16) and in that the deflector (24) is formed at the free end of the cover (11).
11. Rotary electrical machine as claimed in claim 9, wherein the free end (24) of the cover (11) is splayed in order to form the deflector.
12. Rotary electrical machine as claimed in claim 9, wherein the protective cover (11) comprise at least one opening (19) communicating with cooling fluid flow passage (17).
13. Rotary electrical machine as claimed in claim 1, wherein it comprises at least one space between the rotation shaft of the rotor and the dissipating bridge forming an axial fluid flow passage.
14. Rotary electrical machine as claimed in claim 1, wherein the dissipating bridge (16) forms a mezzanine above the rear bearing (4).
15. Rotary electrical machine as claimed in claim 3, wherein the dissipating bridge is fixed to the rear bearing (4) by connecting tie rods (20).

16. Rotary electrical machine as claimed in claim 14, wherein the dissipating bridge is fixed above the rear bearing by means of studs (21) fixed to the dissipating bridge.
17. Rotary electrical machine as claimed in claim 1, wherein it comprises a layer of electrically insulating material between the dissipating bridge and the rear bearing.
18. Rotary electrical machine as claimed in claim 3, wherein the axial ends of the fins fixed to the dissipating bridge are situated at a distance from the rear bearing.
19. Rotary electrical machine as claimed in claim 1, wherein the dissipating bridge, comprising the cooling means, and the bridge carrying the electronic power circuit are in a single piece.
20. Rotary electrical machine as claimed in claim 1, wherein the electronic power circuit (15) comprises power components placed on tracks (25).
21. Rotary electrical machine as claimed in to claim 1, wherein it consists of a reversible alternator.

Documents:

1375-delnp-2005-abstract.pdf

1375-DELNP-2005-Claims.pdf

1375-delnp-2005-complete specification ( as files).pdf

1375-delnp-2005-complete specification (granted).pdf

1375-delnp-2005-correspondence-others.pdf

1375-delnp-2005-correspondence-po.pdf

1375-DELNP-2005-Description (Complete).pdf

1375-DELNP-2005-Drawings.pdf

1375-delnp-2005-form-1.pdf

1375-delnp-2005-form-18.pdf

1375-DELNP-2005-Form-2.pdf

1375-delnp-2005-form-3.pdf

1375-delnp-2005-form-5.pdf

1375-delnp-2005-gpa.pdf

1375-delnp-2005-petition-137.pdf


Patent Number 243551
Indian Patent Application Number 1375/DELNP/2005
PG Journal Number 44/2010
Publication Date 29-Oct-2010
Grant Date 25-Oct-2010
Date of Filing 05-Apr-2005
Name of Patentee VALEO EQUIPMENTS ELECTRICQUES MOTEUR
Applicant Address 2,RUE ANDRE-BOULLE,F-94017 CRETEIL CEDEX,FRANCE
Inventors:
# Inventor's Name Inventor's Address
1 JEAN-MARIE PIERRET 24 RUE SIBUET,F-75012 PARIS,FRANCE.
2 MICHEL FAKERS 15 AVENUE DU VIEUX MOULIN,F-59113 SECLIN, FRANCE.
3 DIRK SCHULTE 48 AVENUE DE LA DAME BLANCHE,F-94120 FONTENAY-SOUS-BOIS, FRANCE.
4 JEAN JULIEN PFIFFER 3 RUE ROSALIE,F-91230 MONTGERON,FRANCE.
PCT International Classification Number H02K 11/00
PCT International Application Number PCT/FR2003/003217
PCT International Filing date 2003-10-28
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 02/13431 2002-10-28 France