Busbar for electric motor

Abstract

Busbar for electric motor The invention relates to an electric motor (100), in particular for motor-fan unit, preferably with a power greater than 800 W, comprising: a heat sink (1), a printed circuit board (2) mounted on the heat sink (1), a stator comprising at least one phase, at least one busbar (3) configured to electrically connect at least one phase of the stator to the printed circuit board (2), said busbar (3) comprising three sections (31, 32, 33) of which a first section (31) for connection to at least one phase of the stator, a second section (32) for connection to the printed circuit board (2) and a third section (33) for junction between the first section (31) and the second section (32), characterized in that the heat sink (1) comprises at least one housing (11) in which is housed at least in part the third section (33) of the busbar (3). [Figure 1]

Description

Title of the invention: Busbar for electric motor technical field

[0001] The invention relates to electric motors, in particular brushless motors, mainly for the field of motor-fan units and preferably for electric motors with a power rating greater than 800 W. Previous technique

[0002] It is known from the prior art that an electric motor typically consists of a control electronic board and a power electronic board. This distinction has the disadvantage of requiring multiple components, resulting in higher industrialization costs that could be improved. Furthermore, increasing the power of an electric motor leads to problems such as the overheating of busbars and necessitates larger cross-sections for these busbars, which also creates space constraints within the electric motor. The invention described herein aims to address, at least partially, these problems. Description of the invention

[0003] The present invention thus relates to an electric motor, particularly for a motor-fan unit, preferably with a power rating greater than 800 W, comprising: - a heat sink, - a printed circuit board mounted on the heat sink, - a stator comprising at least one phase, - at least one busbar configured to electrically connect at least one phase of the stator to the printed circuit board, said busbar comprising three sections, including a first section for connection to at least one phase of the stator, a second section for connection to the printed circuit board and a third junction section between the first section and the second section, characterized in that the heat sink comprises at least one housing in which at least part of the third section of the busbar is housed.

[0004] This has the advantage of reducing the size of the electric motor and allowing for better cooling of at least one busbar due to its at least partial integration into the heat sink. The invention has the additional advantage of having a single printed circuit board that integrates both power electronics and control electronics, which reduces the number of elements in the motor and therefore allows for a reduction in costs.

[0005] By "lodged" it is understood that the third section of the busbar is entirely contained within at least one housing of the heat sink.

[0006] According to one aspect of the invention, the heat sink is made of aluminum or an aluminum alloy in order in particular to guarantee the thermal conductivity and the weight of the electric motor.

[0007] According to one aspect of the invention, at least one bus bar is a low impedance conductor, in particular made of copper or a copper alloy.

[0008] According to one aspect of the invention, the electric motor is of the brushless type.

[0009] According to one aspect of the invention, the electric motor comprises several bars omnibus, preferably two omnibus bars, and even more preferably three omnibus bars. If the electric motor has two omnibus bars, it also has two stator phases. Similarly, if the electric motor has three omnibus bars, then it also has three stator phases. Thus, the electric motor has as many stator phases as there are omnibus bars.

[0010] According to one aspect of the invention, the third section of the at least one bus bar extends mainly in a plane parallel to the printed circuit board and the second and third sections of the at least one bus bar extend perpendicularly to this plane.

[0011] According to one aspect of the invention, the third section of at least one bus bar is electrically insulated by an electrically insulating body, in particular made of thermoplastic material.

[0012] According to one aspect of the invention, the electrically insulating body is entirely contained within at least one housing of the heat sink.

[0013] According to one aspect of the invention, the electrically insulating body is overmolded onto the third section of the busbar.

[0014] According to one aspect of the invention, the electrically insulating body is brought and held on the third section of the busbar by a fastening device.

[0015] According to one aspect of the invention, the fastening device comprises a snap-on device or crimped studs or clamp-mounted studs.

[0016] According to one aspect of the invention, in the configuration of an electric motor according to the invention comprising several busbars, the electrically insulating bodies of the busbars are joined together by insulating material bridges, preferably made of the same material as the electrically insulating bodies. It is thus understood that the heat sink comprises in This configuration provides a single housing unit to accommodate the third sections of the bus bars.

[0017] According to one aspect of the invention and alternatively, the insulating material bridges are made of a different material than the electrically insulating bodies.

[0018] According to one aspect of the invention, the insulating material bridges came from the material of the insulating bodies.

[0019] According to one aspect of the invention and alternatively, the insulating material bridges are elements attached to the insulating bodies.

[0020] According to one aspect of the invention, the electrically insulating bodies are distinct from one another. In other words, in this configuration, there is no material bridge joining the electrically insulating bodies, either in pairs or all together. In this configuration, it is possible to house all the insulating bodies in a single compartment of the heat sink or to distribute the insulating bodies in two or three compartments within the heat sink.

[0021] According to one aspect of the invention, the electrically insulating body at least one bus bar and / or the insulating material bridges include a centering device.

[0022] In the case of several bus bars, for example three bus bars for a three-phase motor, the centering device can be common to the bus bars when they are joined by insulating material bridges or specific to each electrically insulating body if they are distinct from each other.

[0023] According to one aspect of the invention, the centering device comprises at least one centering pin, preferably two centering pins.

[0024] According to one aspect of the invention, the centering pin(s) are made of material from electrically insulating bodies or from insulating material bridges.

[0025] According to one aspect of the invention, the electrically insulating body of at least one bus bar and / or the insulating material bridges comprise at least one bearing surface on the heat sink and at least one bearing surface on the printed circuit board.

[0026] According to one aspect of the invention, each electrically insulating body comprises a bearing surface on the heat sink and a bearing surface on the printed circuit board.

[0027] According to one aspect of the invention, each insulating material bridge comprises a bearing surface on the heat sink and a bearing surface on the printed circuit board.

[0028] According to one aspect of the invention, the support surfaces are configured to hold the electrically insulating body(ies) in place and prevent them from moving. in the heat sink housing(s) when the printed circuit board is mounted on the heat sink.

[0029] According to one aspect of the invention, the bearing surfaces on the heat sink and on the printed circuit board are protruding and flat surfaces, extending from the electrically insulating bodies or the insulating material bridges and in the respective direction of the heat sink or the printed circuit board.

[0030] According to one aspect of the invention, the bearing surface(s) on the printed circuit board are placed at the junction of the first and third sections.

[0031] According to one aspect of the invention, at least one busbar is made of at least two elements, at least the first section being attached to and assembled onto the third section. The second section may be made from the material of the third section.

[0032] According to one aspect of the invention, the first section is mounted tightly and then secured to the third section, in particular by electric welding.

[0033] According to one aspect of the invention, the elements of at least one busbar have current-carrying sections of different dimensions or shapes. In this configuration, the first and third sections are bars with rectangular current-carrying sections, and the second section is a pin with a circular current-carrying section.

[0034] According to one aspect of the invention, at least one busbar is monobloc. In other words, the busbar(s) are each made from a single piece of material.

[0035] According to one aspect of the invention, the heat sink comprises at least one through-hole through which the first phase connection section of the stator passes through the heat sink. It is understood that the stator is located on one side of the heat sink and that the printed circuit board is located on a second side of the heat sink, opposite the first side.

[0036] According to one aspect of the invention, the heat sink comprises a single through orifice for the plurality of bus bars.

[0037] According to one aspect of the invention and alternatively, the heat sink comprises a through-hole by omnibus bar.

[0038] According to one aspect of the invention, the through orifice(s) are sealed with a common sealing gasket or each by a sealing gasket.

[0039] According to one aspect of the invention, the sealing gasket(s) are insulating washers. These parts, known to those skilled in the art, are add-on parts, notably made from rubber or elastomers.

[0040] According to one aspect of the invention, the sealing gasket(s) are filling gaskets cast into the through-holes. This type of gasket consists of filling the through-hole(s) into which the product has been inserted with a liquefied plastic product. The first sections of the busbars were pre-assembled. The seal was achieved by solidifying the plastic product.

[0041] According to one aspect of the invention, the second section connecting to the printed circuit board passes through the printed circuit board. The second section is soldered to the traces of the printed circuit board by selective wave soldering.

[0042] According to one aspect of the invention, the printed circuit board comprises a plurality of MOSFETs, some of which are connected to busbars. These busbars are configured to mount the connected MOSFETs in a dispersed manner on the printed circuit board. Preferably, these MOSFETs are dispersed in a region near the periphery of the printed circuit board. This has the advantage of distributing the heat sources across the printed circuit board, as MOSFETs are power components that generate heat during operation, which must be limited to avoid damaging the electric motor components most sensitive to high temperatures.

[0043] The invention also relates to a method for assembling an electric motor, particularly for a motor-fan unit, preferably with a power rating greater than 800 W, comprising a heat sink, a printed circuit board mounted on the heat sink, a stator comprising at least one busbar configured to electrically connect at least one phase of the stator to the printed circuit board, said busbar comprising three sections, including a first section for connection to at least one phase of the stator, a second section for connection to the printed circuit board, and a third section for junction between the first and second sections, said method comprising the following step: - house the third section of the busbar in a housing of the heat sink so as to minimize the distance between the heat sink and the printed circuit board. Brief description of the drawings

[0044] Other features, details and advantages of the invention will become clearer upon reading the following description, which is provided by way of example in conjunction with drawings in which: - [Fig.1] is a schematic view of an electric motor according to the invention; - [Fig.2] is a schematic view of omnibus bars from [Fig.1]; - [Fig.3] is a schematic view of bus bars from [Fig.1] and 2, comprising an electrically insulating body according to the invention; - [Fig.4] is a schematic cross-sectional view of an electric motor according to the invention.

[0045] It should first be noted that while the figures illustrate the invention in detail for its implementation, these figures can of course also be used to further define the invention where appropriate. It should also be noted that these figures only show a few examples of embodiments of the invention. Detailed description

[0046] The [Fig.[l] illustrates an electric motor 100, in particular for a motor-fan unit, preferably with a power rating greater than 800 W, comprising: a heat sink 1, a printed circuit board 2 mounted on the heat sink 1 and schematically illustrated by dashed lines for better visibility, a stator, not illustrated and comprising at least one phase, at least one bus bar 3 configured to electrically connect at least one phase of the stator to the printed circuit board 2, said bus bar 3 comprising three sections 31, 32, 33, of which a first section 31 for connection to at least one phase of the stator, a second section 32 for connection to the printed circuit board 2 and a third section 33 for junction between the first section 31 and the second section 32, characterized in that the heat sink 1 comprises at least one housing 11 in which is housed at least in part the third section 33 of the bus bar 3.Figure 2 particularly illustrates the different sections 31, 32 and 33 of the omnibus bars.

[0047] As can be seen in [Fig. 1] and 4, the third section 33 of the busbar 3 is entirely contained within at least one housing 11 of the heat sink 1.

[0048] The heat sink 1 is made of aluminium or an aluminium alloy in order in particular to guarantee the thermal conductivity and the weight of the electric motor 100.

[0049] At least one bus bar 3 is a low impedance conductor, in particular made of copper or a copper alloy.

[0050] The electric motor 100 is of the brushless type.

[0051] The electric motor 100 comprises several busbars 3, preferably two busbars 3, and even more preferably three busbars 3, as illustrated in Figures 1 to 3. If the electric motor 100 comprises two busbars 3, it also comprises two stator phases. Similarly, if the electric motor 100 comprises three busbars 3, then it also comprises three stator phases. It is thus understood that the electric motor 100 comprises as many stator phases as there are busbars 3.

[0052] The third section 33 of the at least one bus bar 3 extends mainly in a plane parallel to the printed circuit board 2 and the second and third sections 32, 33 of the at least one bus bar 3 extend perpendicularly to this plane.

[0053] The third section 33 of at least one busbar 3 is electrically insulated by an electrically insulating body 34, in particular made of thermoplastic material. The electrically insulating body 34 is particularly visible in [Fig. 3] and is masked in [Fig. 2] for better visibility of the busbar sections 3.

[0054] Fig. 4 shows that the electrically insulating body 34 is entirely contained within at least one housing 11 of the heat sink 1.

[0055] The electrically insulating body 34 is overmolded onto the third section 33 of the bus bar 3.

[0056] The electrically insulating body 34 is attached and held on the third section 33 of the busbar 3 by a fastening device.

[0057] The fastening device includes a snap-on device or crimped studs or clamp-mounted studs.

[0058] In a configuration as illustrated in Figures 1 to 3 of an electric motor 100 according to the invention comprising several bus bars 3, the electrically insulating bodies 34 of the bus bars 3 are joined together by insulating material bridges 35, preferably made of the same material as the electrically insulating bodies 34. It is thus understood that the heat sink 1 in this configuration comprises a single housing 11 to house the third sections 33 of the bus bars 3.

[0059] Alternatively and not illustrated, the insulating material bridges 35 are of a different material than the electrically insulating bodies 34.

[0060] The insulating material bridges 35 came from the material of the insulating bodies 34.

[0061] Alternatively, and not illustrated, the insulating material bridges 35 are elements related to insulating bodies 34.

[0062] According to a configuration not shown, the electrically insulating bodies 34 are separate from one another. In other words, in this configuration, there is no material bridge joining the electrically insulating bodies 34, either in pairs or all together. In this configuration, it is possible to house all the insulating bodies 34 in a single compartment 11 of the heat sink 1 or to distribute the insulating bodies 34 in two or three compartments 11 in the heat sink 1.

[0063] As illustrated in [Fig. 3], the electrically insulating body 34 of at least one busbar 3 and / or the insulating material bridges 35 include a centering device. The centering device serves to ensure proper pre-assembly of at least one busbar 3 before welding.

[0064] In the case of several busbars 3, for example three busbars 3 for a three-phase motor, the centering device can be common to the busbars 3 when they are joined by bridges of insulating material 35 or otherwise proper to each electrically insulating body 34 if they are distinct from each other.

[0065] The centering device includes at least one centering pin 36, preferably two centering pins 36. [Fig.4] illustrates how at least one centering pin 36 interacts with the printed circuit board 2.

[0066] The centering pin(s) 36 came from the material of the electrically insulating bodies 34 or from the bridges of insulating material 35.

[0067] The electrically insulating body 34 of at least one bus bar 3 and / or the insulating material bridges 35 comprise at least one bearing surface 37 on the heat sink 1 and at least one bearing surface 38 on the printed circuit board 2 as particularly illustrated in [Fig.4].

[0068] Each electrically insulating body 34 comprises a bearing surface 37 on the heat sink 1 and a bearing surface 38 on the printed circuit board 2.

[0069] Each insulating material bridge 35 includes a bearing surface 37 on the heat sink 1 and a bearing surface 38 on the printed circuit board 2.

[0070] The bearing surfaces 37, 38 are configured to hold in place the electrically insulating body(ies) 34 and prevent them from moving in the housing(s) 11 of the heat sink 1 when the printed circuit board 2 is mounted on the heat sink 1.

[0071] The bearing surfaces 37, 38 on the heat sink 1 and on the printed circuit board 2 are protruding and flat surfaces, extending from the electrically insulating bodies 34 or the insulating material bridges 35 and in the respective direction of the heat sink 1 or the printed circuit board 2.

[0072] The bearing surface(s) 38 on the printed circuit board 2 are placed at the junction of the first and third sections 31, 33.

[0073] At least one omnibus bar 3 is made of at least two elements 301, 302, at least the first section 31 is brought and assembled on the third section 33. The second section 32 may be made of material from the third section 33.

[0074] The first section 31 is mounted tightly and then secured to the third section 33, notably by electric welding.

[0075] The elements 301, 302 of the at least one busbar 3 have current-carrying sections of different dimensions or shapes. In this configuration, the first and third sections 31, 33 are bars with rectangular current-carrying sections, and the second section is a pin with a circular current-carrying section.

[0076] Alternatively, at least one busbar 3 is monobloc. In other words, the busbar(s) 3 are each made from a single piece of material.

[0077] As shown in [Fig.4], the heat sink 1 includes at least one through hole 12 through which the first section 31 of connection to the phases of the stator passes through the heat sink 1. It is understood that the stator is placed on a first side of the heat sink 1 and that the printed circuit board 2 is placed on a second side of the heat sink 1, opposite the first side.

[0078] The heat sink 1 includes a single through orifice 12 for the plurality of bus bars 3.

[0079] Alternatively, the heat sink 1 includes a through orifice 12 through busbar 3.

[0080] The orifice(s) through 12 are sealed with a common sealing gasket or each by a sealing gasket 4.

[0081] The sealing gasket(s) 4 are insulating washers. These parts, known to those skilled in the art, are add-on parts, notably made from rubber or elastomers.

[0082] Alternatively, the sealing joint(s) 4 are filling joints cast into the through orifices 12. This type of joint consists of filling the through orifice(s) 12, in which the first sections 31 of the bus bars 3 have been pre-mounted, with liquefied plastic product. The seal is obtained upon solidification of the plastic product.

[0083] The second section 32 for connection to the printed circuit board 2 passes through the printed circuit board 2. The second section 32 is soldered to the traces of the printed circuit board by selective wave soldering.

[0084] The printed circuit board 2 comprises a plurality of MOSFETs (metal oxide semiconductor field-effect transistors). Part of the MOSFETs is connected to the bus bars 3. The bus bars 3 are configured to mount the part of the MOSFETs connected to them in a dispersed manner on the printed circuit board 2. Preferably, these MOSFETs are dispersed in a part near the periphery of the printed circuit board 2. This has the advantage of distributing the heat sources on the printed circuit board 2, since MOSFETs are power components that produce heat in use, which must be limited in order not to damage the components of the electric motor 100 that are most sensitive to high temperatures.

[0085] The invention also relates to a method for assembling an electric motor 100, particularly for a motor-fan unit, preferably with a power rating greater than 800 W, comprising a heat sink 1, a printed circuit board 2 mounted on the heat sink 1, a stator comprising at least one busbar 3 configured to electrically connect at least one phase of the stator to the printed circuit board 2, said busbar 3 comprising three sections, one of which first section 31 for connection to at least one phase of the stator, a second section 32 for connection to the printed circuit board 2 and a third section 33 for junction between the first section 31 and the second section 32, said method comprising the following step: - house the third section 33 of the busbar 3 in a housing 11 of the heat sink 1 so as to minimize the distance between the heat sink 1 and the printed circuit board 2.

Claims

Demands

1. Electric motor (100), in particular for motor-fan unit, preferably with a power rating greater than 800 W, comprising: - a heat sink (1), - a printed circuit board (2) mounted on the heat sink (1), - a stator comprising at least one phase, - at least one bus bar (3) configured to electrically connect at least one phase of the stator to the printed circuit board (2), said bus bar (3) comprising three sections (31, 32, 33) of which a first section (31) for connection to at least one phase of the stator, a second section (32) for connection to the printed circuit board (2) and a third section (33) for junction between the first section (31) and the second section (32), characterized in that the heat sink (1) comprises at least one housing (11) in which at least part of the third section (33) of the bus bar (3) is housed.

2. Electric motor (100) according to the preceding claim, wherein the third section (33) of the at least one bus bar (3) extends principally in a plane parallel to the printed circuit board (2) and the second and third sections (32, 33) of the at least one bus bar (3) extend perpendicular to this plane.

3. Electric motor (100) according to the preceding claim, wherein the third section (33) of at least one busbar (3) is electrically insulated by an electrically insulating body (34), in particular made of thermoplastic material.

4. Electric motor (100) according to the preceding claim, wherein the electric motor (100) comprises several bus bars (3), the electrically insulating bodies (34) of the bus bars (3) are joined together by insulating material bridges (35), preferably made of the same material as the electrically insulating bodies (34).

5. Electric motor (100) according to claim 3, wherein the electric motor (100) comprises several busbars (3), the electrically insulating bodies (34) being distinct from one another.

6. Electric motor (100) according to any one of claims 3 to 5, wherein the electrically insulating body (34) at least one busbar (3) and / or the insulating material bridges (35) comprise a centering device.

7. Electric motor (100) according to any one of claims 3 to 5, wherein the electrically insulating body (34) of at least one busbar (3) and / or the insulating material bridges (35) according to claim 4 comprise at least one bearing surface (37) on the heat sink (1) and at least one bearing surface (38) on the printed circuit board (2).

8. Electric motor (100) according to the preceding claim, wherein each electrically insulating body (34) comprises a bearing surface (37) on the heat sink (1) and a bearing surface (38) on the printed circuit board (2).

9. Electric motor (100) according to the preceding claim, wherein the bearing surfaces (37, 38) on the heat sink (1) and on the printed circuit board (2) are protruding and flat surfaces, extending from the electrically insulating bodies (34) or the insulating material bridges (35) and in the respective direction of the heat sink (1) or the printed circuit board (2).

10. Method for assembling an electric motor (100), particularly for a motor-fan unit, preferably with a power rating greater than 800 W, comprising a heat sink (1), a printed circuit board (2) mounted on the heat sink (1), a stator comprising at least one busbar (3) configured to electrically connect at least one phase of the stator to the printed circuit board (2), said busbar (3) comprising three sections, including a first section (31) for connection to at least one phase of the stator, a second section (32) for connection to the printed circuit board (2), and a third section (33) for junction between the first section (31) and the second section (32), said method comprising the following step: house the third section (33) of the bus bar (3) in a housing (11) of the heat sink (1) of in order to minimize the distance between the heat sink (1) and the printed circuit board (2).

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