BROOMING MACHINE FOR ELECTRIC MACHINE AND CORRESPONDING ELECTRIC MACHINE

Abstract

The invention relates to a brush machine (10) for an electrical machine comprising a commutator (12) having an axis of rotation (C) and at least one brush (14) configured to be in contact with an external surface (S) of the commutator. The commutator (12) comprises several commutator blades (16) arranged around the periphery of the commutator. Each blade comprises a body (161) extending longitudinally along the axis of rotation and an external surface (163) forming a portion of the external surface of the commutator. According to the invention, each blade has at least one channel (166) formed inside the blade body and near its external surface (163) and configured to be partially filled with a liquid under vacuum. The brush machine includes at least one heat dissipation device (30) and connecting elements (40), each configured to connect each channel (166) of a blade to a cooling device. (See Figure 4 for abbreviations.)

Description

Title of the invention: BROOMING MACHINE FOR ELECTRIC MACHINE AND CORRESPONDING ELECTRIC MACHINE technical field

[0001] The present invention relates to a brush machine for an electrical machine, in particular a direct current electrical machine. More specifically, the invention relates to the cooling of a commutator and the brushes of a brush machine.

[0002] The invention also relates to a corresponding electrical machine and in particular an electrical machine of an aircraft. Previous technique

[0003] Generally, an electrical machine comprises a frame, a rotating shaft, a stator fixed to the frame, also called an inductor, which is the fixed part of the electrical machine and a rotor, also called an armature and placed inside the stator, the rotor being a rotating part of the electrical machine.

[0004] Certain electrical machines, particularly direct current machines, also include a rotating commutator that creates an electrical connection between the stationary part (stator) and the rotating part (rotor) of the machine. For this purpose, these machines also include commutator brushes, also known as contactors or "carbon brushes." These commutator brushes are conductive components that provide the electrical connection between the stationary and rotating or moving parts of the machines. They supply power to the commutator during motor operation and collect the current from the commutator during generator operation.

[0005] Fig. 1 schematically represents a 10A brush machine according to the prior art comprising a 12A blade commutator and 14A brushes, two brushes in the illustrated example.

[0006] In this example, the brushes 14A, generally made of graphite, are arranged in parallel with each other. The commutator 12A comprises commutator segments 16A, generally made of copper. The segments 16A are electrically insulated from each other by thin insulating spacers 18A, often made of mica.

[0007] Figure 2 illustrates a half-sectional view of a 10A brushed machine comprising a 12A commutator and two 14A brushes. In the example shown, the commutator is cast. The 12A commutator has a hollow shaft, usually made of steel, supporting the commutator segments. All the parts of the 12A commutator are held together by means of an insulating resin 22A. In addition, to resist centrifugal forces, 24A rings are advantageously inserted in the collector.

[0008] The brush machine further comprises one or more brush holders 26A for maintaining the brushes in contact with the commutator. For example, as illustrated in [Fig. 2], the machine 10A comprises one brush holder 26A per brush. Each brush holder 26A has a cage for housing a brush 14A. Each brush 14A is movable within the cage by sliding and held against the commutator by a spring 28A.

[0009] The sum of mechanical and electrical losses in a brushed machine can, for certain types of DC machines, represent a significant portion of the losses and lead to excessive heating of the brushes and the commutator at the blade-brush interface. The brushes 14A and the commutator blades 16A can thus reach extreme temperatures of several hundred degrees during full-power operation.

[0010] Figure 3 shows a brush wear curve as a function of their operating temperature. As this figure shows, for an operating temperature reaching 200°C, the brush life is very limited, on the order of 1000 hours on average. Conversely, for an operating temperature of 100°C, the brush life is much longer.

[0011] The wear phenomenon of brushes is a very complex and non-linear phenomenon. However, there appears to be an ideal operating temperature for the brushes at around one hundred degrees, at which wear is minimal.

[0012] Thus, in order to reduce their rate of wear and the periodicity of their maintenance, it is important to ensure good cooling of the collectors and / or brushes.

[0013] Conventionally, the cooling of a brushed machine consists of circulating air inside the machine. A fan is often used for this purpose. The fan is mounted directly on the machine shaft. Air is drawn from outside, then enters and circulates within the machine, brushing against the surface of the commutator and the brushes before being expelled from the outside of the machine.

[0014] However, such a cooling device does not allow the temperature of the commutator and brushes to be maintained within an optimal operating range, because the temperature of the brushes and commutator is the result of several phenomena: - mechanical losses of the commutator and brushes which increase with the rotational speed of the machine; - electrical losses in the commutator and brushes which depend on the load rate of the machine; - the airflow rate, which depends on the machine's rotation speed in the case of a self-ventilated machine; and - the quality of ventilation which depends on factors such as the temperature of the cooling air, the speed of the air and its path.

[0015] Channeling the air as close as possible to the places where losses are created, in particular at the interface between the collector and the brushes, is not always easy to achieve given the configuration of the collector and the brushes.

[0016] Thus, existing solutions are unsatisfactory for the following reasons. The commutator surface is smooth, which limits the surface area for heat exchange with the cold airflow generated by the ventilation system. The cooling air temperature can be high (above 50°C), which further limits the amount of heat that can be exchanged with the small surface area of ​​the commutator and brushes. The air circulating within the electric machine casing is difficult to channel along the surfaces to be cooled—the commutator surface and the brush surfaces—due to the rotor's rotational movement. Depending on environmental conditions, the cooling air may be at a high temperature. The brushes are guided around their entire circumference inside the cage, which must be of sufficient height to prevent jamming. This cage, often made of folded or stamped sheet steel for economic reasons, acts as a thermal barrier against the surrounding airflow. Thus, the cage significantly limits the surface area of ​​heat exchange between the brushes and the surrounding air circulating around it. Furthermore, to prevent jamming, the brushes are guided with adequate clearance, and 0.3 mm deep counterbores are also machined into their faces. All of these measures aim to limit the thermal contact between the brush and its cage and, consequently, the efficiency of heat transfer from the brush to the cooling fins of the cage.

[0017] The objective of the present invention is therefore to propose a brush machine that makes it possible to overcome at least some of these disadvantages and in particular to maintain the brushes and the commutator around an ideal operating temperature in order to optimize their lifespan. Summary of the invention

[0018] To this end, the invention relates to a brush machine for an electrical machine comprising a commutator having an axis of rotation and at least one brush configured to be in contact with an external surface of the commutator, the commutator comprising several commutator segments arranged around the periphery of the commutator, each segment comprising a body extending longitudinally along the axis of rotation and an external surface forming a portion of the outer surface of the collector. According to the invention, blades among the several blades advantageously each comprise at least one channel formed inside the body of the blade and near the external surface of the blade and configured to be at least partially filled with a liquid placed under vacuum. Furthermore, according to the invention, the brush machine includes at least one heat dissipation device and connecting elements, each configured to connect at least one channel of a blade to at least one cooling device.

[0019] Such a brush machine advantageously allows the life of the brushes to be significantly extended when they are subjected to high temperatures.

[0020] Indeed, the invention makes it possible to cool the commutator blades and brushes more efficiently by efficiently draining the losses created mainly at the interface of the commutator and the brushes because it is at this point that the most significant losses are generated.

[0021] The drainage of losses is achieved by means of channels arranged directly inside the collector blades. These channels, filled with a certain quantity of liquid, act as heat pipes by increasing the thermal conductivity of each collector blade.

[0022] This solution for draining losses at the brush / column blade interface makes it possible to lower the operating temperature and consequently increase the service life of the brushes and the blade collector.

[0023] The brushes are thus cooled more efficiently in order to bring them back to the "ideal" operating temperature and to make their service life acceptable to users (for example, by aligning the maintenance period for the brushes with the general overhaul period for the machine).

[0024] The broom machine according to the invention may include one or more of the following features, taken individually or in combination with each other in all technically possible combinations: - the collector is mobile in rotation around the axis of rotation and the heat evacuation device is integral with the collector during the rotation of the latter; - for each collector blade equipped with a channel, at least one channel extends parallel to the axis of rotation of the collector; - For each collector blade equipped with a channel, at least one channel extends longitudinally between a first end connected to the heat dissipation device and a second end opposite the first end, while being inclined relative to the axis of rotation of the collector at an angle of approximately 10°, the first end being closer to the axis of rotation than the second end; - each channel is centered in the body of the blade in a plane transverse to the blade; - two consecutive blades are separated by an inter-blade partition and each blade extends radially between a radially internal surface and a radially external surface and comprises two lateral surfaces each connecting the radially internal and external surfaces; and each channel is formed in one of the lateral surfaces and delimited by the adjacent inter-blade partition; - the partition between the blades is made of metal; - each blade is formed of a first part and a second part juxtaposed, the channel of the blade being formed at the interface of the first part and the second part; - each blade equipped with at least one channel has several channels parallel to each other; - the channels of the blades have a non-circular cross-section; - the cross-section of the blade channels is semi-circular, square or rectangular; - the liquid is water, ethanol or a coolant; - the brush machine includes several heat dissipation devices, each being connected to at least one channel of a blade by connecting elements, each blade being at the same electrical potential as the heat dissipation device to which it is connected; - the channels of the blades are connected by the connecting elements to the same heat evacuation device, the channels each being electrically isolated from the heat evacuation device; - the heat dissipation device is a finned radiator; - each fin is attached to a corresponding collector blade; - each fin and each corresponding collector blade are formed entirely from a single piece of material; - the blade channels are connected by the connecting elements to the same heat evacuation device, the brush machine comprising an electrically arranged insulating seal between the collector and the heat evacuation device, the seal comprising several passage orifices each for a channel of a collector blade; - the blade channels are connected to each other in pairs in series by being linked together by U-shaped connecting elements and electrically insulated; - Each connecting element includes a connecting tube extending between a first end inserted into the blade and surrounding the first end of the channel and a second end fluidly connected to the heat evacuation device; - the collector has between 30 and 50 collector blades; - the manifold is a molded manifold or a screwed manifold; - the manifold is a molded manifold or a screwed manifold.

[0025] The invention also relates to an electric machine, in particular for aircraft, having a longitudinal axis and comprising a stator, a rotor placed inside the stator and movable in rotation around the longitudinal axis and a brush machine according to the invention and as described above, the axis of rotation of the brush machine being collinear with the longitudinal axis of the electric machine. Brief description of the drawings

[0026] The present invention will be better understood and other details, features and advantages of the present invention will become more apparent upon reading the description of a non-limiting example that follows, with reference to the accompanying drawings in which: - the [Fig.1], already described, is a schematic three-dimensional view of a brush machine according to the prior art; - the [Fig.2], already described, represents a schematic half-section view of a brush machine according to the prior art; - the [Fig.3], already described, represents a brush wear curve as a function of their operating temperature; - [Fig.4] is a schematic half-section view of a brush machine according to a first embodiment; - [Fig.5] schematically represents a transverse view of a collector of the brush machine of [Fig.4]; - [Fig.6] illustrates an enlarged view of the connection of the manifold of the machine in [Fig.4] to a cooling device; - [Fig.7] illustrates an example in which the cooling device is a finned radiator rotating in two different positions; - [Fig.8] illustrates another example in which the cooling device is a finned radiator rotating in two different positions; - [Fig.9] represents a second embodiment of the invention in which each collector blade includes an independent cooling device; - [Fig. 10] is a schematic three-dimensional view of a collector of a brush machine according to a third embodiment of the invention; - Figure 11 schematically illustrates different possible positions of the channel in a collector blade according to the invention; and - [Fig. 12] schematically represents a three-dimensional view of an electrical machine comprising a brush machine according to the invention.

[0027] Elements having the same functions in the different implementations have the same references in the figures.

[0028] In the figures, the scales and proportions are not strictly respected for the purposes of illustration and clarity.

[0029] Furthermore, in the description and the claims, the terminology axial, radial and transverse will be adopted without limitation with reference to the trihedron A, R, T indicated in the figures, the axial axis A being parallel to the longitudinal axis of the lubrication chamber according to the invention. Description of the implementation methods

[0030] The invention applies to any type of brushed machine comprising a commutator and brushes, where losses in the brushes and commutator lead to excessive heating and increased wear of the brushes and commutator. Excessive heating is considered to be 100°C, an acceptable temperature limit, since temperatures above this very often lead to accelerated brush wear ([Fig. 3]).

[0031] Fig. 4 illustrates a schematic half-section view of such a brush machine 10 according to a first embodiment of the invention.

[0032] The brush machine 10 comprises a commutator 12 and at least one brush line(s). In the illustrated example, only one brush line is shown for clarity, this brush line comprising, in this example, two brushes 14. However, according to the invention, the brush machine 10 may comprise a single brush or several brushes per brush line.

[0033] Each brush 14 is configured to be in contact with an external surface S of the collector 12.

[0034] By convention in the present application, the terms "internal" and "external", "inside" and "outside" are defined radially with respect to the longitudinal axis C of the brush machine 10, which is in particular the axis of rotation of the commutator 12 of the brush machine.

[0035] The brush lines each extend parallel to the axis of rotation C of the commutator 12 and are arranged around the commutator. Preferably, the brush lines are evenly distributed around the commutator.

[0036] The brush machine 10 further comprises one or more brush holders not visible in [Fig.4] and as described, for example, with reference to [Fig.2]. These brush holders are configured to keep the brushes in contact with the commutator, for example by means of a spring as described previously.

[0037] The brushes are generally made of graphite.

[0038] In the example illustrated in [Fig.4], the brushes are arranged parallel to each other. However, other configurations are possible according to the invention.

[0039] The manifold 12 will now be detailed.

[0040] In the illustrated example, the manifold 12 is molded. However, the invention can also be applied to other types of manifolds, such as screwed manifolds.

[0041] The collector 12 has a hollow cylindrical shaft 20 with longitudinal axis C, which is also an axis of rotation of the collector during operation. Indeed, the collector 12 is free to rotate about the axis of rotation C.

[0042] Preferably, the collector shaft 20 is made of steel. The collector shaft 20 is configured to support collector blades 16 around its periphery.

[0043] Preferably, the collector 12 has a number of blades 16 between 30 and 50.

[0044] In addition, to resist centrifugal forces, rings 24 are advantageously inserted in the collector.

[0045] The collector blades are juxtaposed with each other so as to form an annular ring of blades.

[0046] Preferably, the collector blades 16 are made of copper or a copper-based alloy.

[0047] The blades 16 are electrically insulated from each other by thin insulating inter-blade partitions 18. Thus, two successive commutator blades are separated by an insulating inter-blade partition 18. In other words, there is an alternation of commutator blades 16 and inter-blade partitions 18 around the periphery. The inter-blade partitions 18 extend longitudinally along the longitudinal axis C of the commutator. The inter-blade partitions 18 are preferably made of mica.

[0048] With reference to [Fig.5] which illustrates a cross-sectional view of the collector 12, each collector blade 16 comprises a body 161 extending longitudinally along the longitudinal axis C of the collector which is also the axis of rotation of the collector in operation.

[0049] The body 161 extends radially between an internal surface 162 and an external surface 163. The external surface 163 forms a portion of the external surface S of the collector.

[0050] The body 161 further comprises two lateral surfaces 164 each connecting the radially internal surfaces 162 and external surfaces 163.

[0051] The body 161 further comprises one or more feet 165, in particular dovetail-shaped, extending radially inwards from the internal surface 162, i.e., towards the commutator shaft 20. The feet 165 are shaped to cooperate with the ferrules 24 in order to hold the blades in position despite centrifugal forces when the brush machine is in operation.

[0052] The parts of the collector 12 are held together with each other by means of an insulating resin 22, in particular the shaft 20, the frets 24 and the blades 16 of the collector.

[0053] According to the invention, each blade 16 advantageously comprises at least one channel 166 formed within the body 161 of the blade. For clarity, only a few channels are shown in [Fig. 5]. Each channel 166 is arranged near the outer surface 163 of the blade 16. Each channel 166 is thus arranged in the immediate vicinity of an interface between the blade 16 and a brush 14. By "near" or "in the immediate vicinity," it is understood that each channel is closer to the outer surface S of the commutator than to the axis of rotation C of the commutator 12. In other words, each channel 166 is closer to the outer surface S of the commutator than to the commutator shaft 20.

[0054] For example, each channel 166 is advantageously arranged at a distance from the external surface 163 of the blade 16 of between 1 mm and 5 mm.

[0055] Preferably, each channel 166 extends over substantially the entire length of the collector, the length being the dimension along the longitudinal axis C of the collector.

[0056] Each channel is configured to be partially filled with a liquid, for example water, ethanol or a coolant.

[0057] By "partially" filled with liquid, for the purposes of this invention, each channel contains liquid but is not entirely filled with liquid. More precisely, each channel is filled with liquid with a filling rate varying from a few percent to 20%. The filling rate is defined as the ratio between the volume of liquid placed inside the channel and the internal volume of the channel corresponding to the evaporation section, that is, the volume of the channel directly heated by the brushes.

[0058] Each channel is further evacuated so as to function as a heat pipe, that is, so as to transport the heat generated at the blade / brush interface to the outside of the collector 12. Indeed, once the quantity of liquid has been introduced into the channel, a vacuum is created inside it, either: - by heating the liquid until it evaporates, which will then expel the air trapped in the channel. The channel is then sealed. - using a vacuum pump.

[0059] Furthermore, according to the invention, the brush machine 10 advantageously comprises at least one heat dissipation device 30 and connecting elements 40. Each connecting element 40 is configured to connect the channel or channels 166 of each blade to a heat dissipation device 30.

[0060] According to the first embodiment of the invention illustrated in [Fig. 4], the brush machine 10 comprises a single heat dissipation device 30 for all the blades. Therefore, each connecting element 40 is configured to connect the one or more channels 166 of each blade to the heat dissipation device 30 common to all blades. Thus, each channel 166 filled with liquid, under vacuum and connected to the common heat dissipation device 30 is adapted to function as a heat pipe, i.e. to transport the heat generated at the blade / brush interface to the outside of the collector 12 and in particular to the common heat dissipation device 30.

[0061] The common heat dissipation device 30 is fixed to the manifold 12 during its rotation. For example, and as illustrated in particular in [Fig. 4], the common heat dissipation device 30 and all the parts of the manifold 12 are held together by means of the insulating resin 22.

[0062] For each collector blade 16, the channel 166 extends longitudinally between a first end 166A connected to the heat evacuation device 30 and a second end 166B opposite the first end 166A.

[0063] Preferably, for each blade, the channel 166 is inclined with respect to the axis of rotation C of the collector 12 so that the first end 166A is closer to the axis of rotation C than the second end 166B. The angle between the channel 166 and the axis of rotation C is less than 10° and preferably equal to 5°.

[0064] According to a particular case, for each blade, the channel 166 extends parallel to the axis of rotation C of the collector 12, i.e. an angle of 0°.

[0065] In the case where the blades comprise several channels 166, these are parallel to each other and can therefore all be inclined with respect to the axis of rotation C or be parallel to the axis of rotation C.

[0066] Fig. 6 represents an enlarged view of the brush machine 10 at the level of a connecting element 40 of a channel 166 of a blade to the cooling device 30 common to all the blades.

[0067] According to the illustrated embodiment, each connecting element 40 comprises a connecting tube 42 extending between a first end 42A and a second end 42B. The first end 42A is brought into the blade 16 by surrounding the first end 166A of the channel 166. Thus, the inner diameter of the connecting tube 42 is equal to the outer diameter of the channel 166. The connecting tube is preferably made of copper.

[0068] The second end 42B is fluidly connected to the heat dissipation device 30. The second end 42B is further electrically insulated from the heat dissipation device 30 in the case where the heat dissipation device 30 is electrically conductive and connected to several collector segments 16, in order to prevent short-circuiting of the collector segments 16. For this purpose, the second end 42B of the connecting tube is covered by a thin layer of electrical insulation and having sufficient thermal conductivity, for example by the same insulating resin 22 as the resin holding together the elements of the collector 12 or by any other known means of insulation. Thus, the assembly formed by the channel 166 and the connecting tube 42 is filled with liquid and placed under vacuum to form a shaped heat pipe to transport heat from the collector blade / brush interface to the heat evacuation device 30.

[0069] Alternatively, to avoid short-circuiting the commutator segments 16 with each other, the brush machine 10 may include an electrically arranged insulating seal between the commutator 12 and the heat dissipation device 30. The seal then includes several passage holes, each for a channel 166 of a commutator segment.

[0070] The common heat dissipation device 30 may include a plate supporting fins 32 as in the example illustrated in Figures 7 and 8. Indeed, Figures 7 and 8 represent the case of a brushed machine 10 in which the heat dissipation device 30 is a rotating finned radiator 34 which is fixed rigidly to the commutator 12 and more precisely to one end of the commutator from which the ends 166A of the channels of the blades 16 emerge for their connection to the heat dissipation device 30. The rotating finned radiator 34 is thus free to rotate about the axis of rotation C of the commutator rigidly with the commutator 12.

[0071] In these figures 7 and 8, the sweep lines are intentionally not illustrated for the sake of clarity.

[0072] Figures 7 and 8 differ from each other in the diameter of the rotating finned radiator 34. In [Fig. 7], the outside diameter of the rotating finned radiator 34 is substantially equal to the outside diameter of the brush machine commutator. In [Fig. 8], the diameters are different. More precisely, the outside diameter of the rotating finned radiator 34 is larger than the outside diameter of the brush machine commutator.

[0073] Figure 9 schematically illustrates a second embodiment of the invention. The electric machine 100 according to this second embodiment of the invention differs from the electric machine 10 according to the first embodiment in that the brush machine 100 comprises several heat dissipation devices 300. Each heat dissipation device 300 is associated with a blade 16 and connected to the channel(s) 166 of this blade 16 by one or more connecting elements 40.

[0074] Thus, each collector blade 16 has a dedicated heat dissipation device 300. The heat dissipation device 300 is therefore at the same electrical potential as the collector blade 16, eliminating the risk of a short circuit between the blades. This embodiment therefore has the advantage of not requiring electrical insulation of each collector blade 16 from the heat dissipation device 300.

[0075] In the illustrated example, each heat dissipation device 300 is a fin 320 attached to the blade 16 of the collector. For example, the fin 320 is brazed to the associated blade 16. Alternatively, the 320 fins can be made in one piece with the 16 collector blades.

[0076] Figure 10 schematically represents a third embodiment of the invention in which the channels 166 of the blades are connected to each other in series, two by two. For this purpose, the channels are connected to each other by U-shaped and electrically insulated connecting elements 400.

[0077] Preferably, the U-shaped connecting elements 400 are advantageously integrated into one or more heat evacuation devices, such as, for example, a rotating radiator as illustrated in Figures 7 and 8.

[0078] Such a connection of the channels in series makes it possible to form a tube in the shape of a coil closed on itself, filled with liquid and placed under vacuum, making it possible to form an oscillating heat pipe.

[0079] According to this embodiment, each channel 166 of each blade extends longitudinally between a first end 166A and a second end 166B opposite the first end 166A. The first end 166A and the second end 166B open respectively onto a first transverse face 12A of the collector and onto a second transverse face 12B of the collector 12.

[0080] In addition, each connecting element 400 includes a U-shaped connecting tube 420 comprising two ends 420A, 420B. On the side of the first transverse face 12A of the collector, the ends 420A, 420B of a connecting tube 400 connect the first ends 166A of the channels of two adjacent blades 16. Similarly, on the side of the second transverse face 12B of the manifold, the ends 420A, 420B of a connecting tube 400 connect the second ends 166B of the channels of two adjacent blades 16 so as to form a continuous tube filled with liquid.

[0081] The connecting tube 420 is preferably made of copper.

[0082] The connecting tube 420 is further electrically insulated to prevent the short-circuiting of the collector blades 16 together. For this purpose, the connecting tube 420 is covered with a thin layer of electrical insulation.

[0083] The brush machine according to this third embodiment may further include a heat dissipation device for cooling the liquid in the channels in order to cool the blade / brush interface. The heat dissipation device is then arranged at one end of the commutator.

[0084] This third embodiment has the advantage of requiring only one vacuuming of the assembly instead of vacuuming channel by channel.

[0085] Regardless of the embodiment of the invention and the number of channels per collector blade, the channels of the blades preferably have a non-circular cross-section. For example, the cross-section of the blade channels is semi-circular, square, or rectangular.

[0086] Figure 11 illustrates several methods of creating a channel in a blade. The blade referenced I is without a channel. Preferably, each channel 166-11 is centered in the blade body in a plane transverse to the blade, such as in the referenced IL blade

[0087] Such a channel 166-11 is for example made by drilling or by electro-erosion. Alternatively, each channel 166-III can be formed in one of the lateral surfaces 164 and delimited by the adjacent inter-blade partition 18. Alternatively, the inter-blade partition 18 is made of metal or covered with a metal wall 182 and each channel 166-IV is formed in one of the lateral surfaces 164 and delimited by the metal wall 182 of the adjacent inter-blade partition 18. According to another alternative, each blade (here referenced V) is formed of a first part and a second part juxtaposed and the 166-V channel of the blade being formed at the interface of the first part and the second part.

[0088] Channels of type 166-III, 166-IV and 166-V are for example produced by machining or stamping.

[0089] The invention also relates to an electrical machine, in particular for aircraft, having a longitudinal axis and comprising a stator and a rotor placed inside the stator and movable in rotation around the longitudinal axis.

[0090] The electric machine further comprises a brush machine according to the invention and as described above. The axis of rotation of the brush machine is collinear with the longitudinal axis of the electric machine.

[0091] The electrical machine is preferably a direct current machine such as a motor, a generator, a starter or a starter-generator.

[0092] Figure 12 shows an example of such an electrical machine 1000 equipped with a brush machine 10 according to the invention. The brush lines are intentionally not shown for clarity. The commutator 12 of the brush machine includes a heat dissipation device 30. For example, and as shown in Figure 12, the heat dissipation device 30 is a rotating finned heat sink 34.

[0093] In the illustrated example, the electric machine 1000 comprises a rotor 1020. The rotor 1020 comprises a shaft 1030 on which is stacked a set of ferromagnetic disks 1040. Slots 1050 are axially formed at the periphery of the cylinder formed by the stacked disks.

[0094] Furthermore, the rotor 1020 comprises armature coils 1060 formed of windings wound according to a very precise pattern. The armature coils 1060 are inserted into the slots 1050 of the magnetic circuit. Each winding is composed of a series of sections, themselves composed of turns. As is known, a turn is a loop whose forward path is placed in one slot of the armature and whose return path is in the diametrically opposite slot.

[0095] The armature coils 1060 are connected to the commutator 12.

[0096] The invention, as presented, describes a brush machine having more efficient cooling than a conventional brush machine, and in particular the invention makes it possible to cool the commutator blades and the brushes of the brush machine more efficiently.

[0097] Obviously, the invention is not limited to the embodiments described above and provided solely by way of example. It encompasses various modifications, alternative forms and other variants that a person skilled in the art may consider within the scope of the invention, and in particular all combinations of the different modes of operation described above, which may be taken separately or in combination.

[0098] For example, according to the invention, the collector may comprise several collector blades having at least one channel formed inside the blade body as described above, and several other blades without channels. The blades having a channel and the blades without channels are arranged alternately. For example, every other blade or every third blade has a channel while the other blades have no channels.

[0099] According to another example, a collector according to the invention may comprise one or more blades, each comprising several channels.

Claims

Demands

1. Brush machine (10; 100; 200) for an electrical machine comprising a commutator (12) having an axis of rotation (C) and at least one brush (14) configured to be in contact with an external surface (S) of the commutator, the commutator (12) comprising several commutator blades (16) arranged around the periphery of the commutator, each blade (16) comprising a body (161) extending longitudinally along the axis of rotation and an external surface (163) forming a portion of the external surface (S) of the commutator; characterized in that blades (16) among the several blades each have at least one channel (166) formed inside the blade body and near the external surface (163) of the blade and configured to be at least partially filled with a liquid placed under vacuum; and in that the broom machine (10) includes at least one heat dissipation device (30; 300) and connection elements (40;400), each configured to connect at least one channel (166) of a blade (16) to at least one heat dissipation device (30).;

2. A broom machine according to claim 1, wherein the commutator (12) is movable in rotation about the axis of rotation (C) and the heat evacuation device (30) is fixed to the commutator (12) during the rotation thereof.

3. A brush machine according to claim 1 or 2, wherein for each commutator blade (16) equipped with a channel, at least one channel (166) extends parallel to the axis of rotation (C) of the commutator or at least one channel (166) extends longitudinally between a first end (166A) connected to the heat dissipation device (30) and a second end (166B) opposite the first end while being inclined with respect to the axis of rotation (C) of the commutator at an angle of about 10°, the first end being closer to the axis of rotation than the second end.

4. Broom machine according to any one of the preceding claims, wherein each blade (16) equipped with at least one channel has several channels (166) parallel to each other.

5. Broom machine according to any one of the preceding claims, wherein the liquid is water, ethanol or a coolant.

6. Broom machine (100) according to any one of the preceding claims, comprising several heat dissipation devices (300), each being connected to at least one channel (166) of a blade (16) by connecting elements (40), each blade (16) being at the same electrical potential as the heat dissipation device (300) to which it is connected.

7. Broom machine according to any one of claims 1 to 5, wherein the channels (166) of the blades are connected by the connecting elements to the same heat dissipation device (30), the channels each being electrically insulated from the heat dissipation device.

8. Brush machine according to any one of claims 1 to 5, wherein the channels (166) of the blades are connected by the connecting elements (30) to the same heat dissipation device, the brush machine comprising an electrically arranged insulating seal between the collector and the heat dissipation device, the seal comprising several passage holes each for a channel of a collector blade.

9. Brush machine according to any one of claims 1 to 5, wherein the channels (166) of the blades are connected to each other in series by being connected to each other by U-shaped connecting elements (400) and electrically insulated.

10. A broom machine according to any one of the preceding claims, wherein each connecting element (40) comprises a connecting tube (42) extending between a first end (42A) brought into the blade by surrounding the first end of the channel and a second end (42B) fluidly connected to the heat evacuation device.

11. Electric machine (1000), in particular for aircraft, having a longitudinal axis and comprising a stator, a rotor (1020) placed inside the stator and movable in rotation about the longitudinal axis and a brush machine according to any one of the preceding claims, the axis of rotation of the brush machine being collinear with the longitudinal axis of the electric machine.

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