Motor

Abstract

The motor comprises a conductive element (25) arranged to connect a first track (21) and a second track (22) of a power circuit to close the circuit; the conductive element (25) is held in place by at least one mechanically breakable joint (26) which mechanically yields or breaks when subjected to a predetermined force, thereby disconnecting the power circuit; the motor comprises a system (50) for releasing the conductive element (50) from the first and / or second track when the housing (2) of the motor is moved close to a cover (3) covering the motor.

Description

Technical Field

[0001] The present invention relates to an electric machine, and more particularly to an electric machine provided with a system for preventing a short circuit in the event of an accident. Background Art

[0002] Typically, the electric machine comprises a housing having inside it a stator rigidly connected to the housing and a rotor rotatably connected to the housing, the rotor for example having permanent magnets, the electric machine for example being a brushless electric motor, to which reference is made hereinafter without limiting the scope of the invention.

[0003] An example of a prior art electric machine is described in application WO2013008180 in the name of the present applicant.

[0004] The electronic module or electronic drive circuit connected to the stator in a brushless electric motor comprises a printed circuit board and a plurality of active and passive electronic components defining the power part and a plurality of electronic signal components defining the control part arranged on the printed circuit board itself; generally speaking, there is a power supply circuit or line in the motor for supplying power to the electronic components of the power part.

[0005] The housing is covered by a cover to form a sealed container from which connection pins protrude to allow power supply and control of the electronic drive circuit.

[0006] This type of electric machine is used in particular in the automotive industry and in other industries subject to ever-changing and stringent safety regulations. More specifically, in the art there is an increasing need to prevent or limit the risk of short circuits in the event of an accident involving a vehicle in which the electric machine can be installed.

[0007] A short circuit, especially in the power supply line, can cause a fire that can spread from the motor to the entire vehicle.

[0008] In this context, the technical purpose underlying the present invention is to propose an electric machine capable of meeting the above-mentioned needs. Summary of the invention

[0009] It is an object of the present invention to provide an electric machine which reduces the risk of fire, in particular the risk of fire caused by a short circuit in the electronic drive circuit of the electric machine. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Other characteristics and advantages of the invention are more apparent from the non-limiting description of an electric machine shown in the accompanying drawings, in which:

[0011] - Figure 1 An electric machine according to the invention is shown in an exploded perspective view, with some components removed for simplicity;

[0012] - Figure 2An electronic module of an electric machine according to the invention is shown in an exploded perspective view, with some components removed for simplicity;

[0013] - Figure 3 Shown in top view Figure 2 Details of the electronic modules;

[0014] - Figure 4 shows a cross section of an electric machine according to the invention;

[0015] - FIG. 5A to FIG. 5E A detailed embodiment of an electrical machine according to the invention is shown in each case in a schematic cross section, with some components being cut away for greater clarity. DETAILED DESCRIPTION

[0016] Reference numeral 1 generally designates an electric machine according to the invention, which will hereinafter be described in detail only insofar as is necessary for an understanding of the present disclosure.

[0017] The electric machine 1 is preferably a rotary electric machine and is, for example, an electric motor of the sealed type, that is to say without any opening to its interior. In the following, explicit reference is made to this embodiment, without loss of generality thereby, it being understood that the scope of the invention also includes electric motors, electric pumps or alternators of the open type.

[0018] In the embodiment shown, the electric machine 1 comprises a housing 2 and a cover 3 covering the housing 2 so as to define, together with the housing 2 , a casing 4 or container which is closed and preferably sealed.

[0019] The housing 2 and the cover 3 are made of an aluminum alloy, but may be made of any other material.

[0020] The housing comprises a cup-shaped member 2a which is delimited at the bottom by a base wall 2b and has an open end on the side opposite to the base wall 2b.

[0021] The housing 2 has, at the open end, a substantially annular flange 2 c extending radially from the cup-shaped member 2 a and intended to be coupled to the cover 3 .

[0022] More specifically, the flange 2c is connected to the cup-shaped member 2a by a molding 2d which widens from the cup-shaped member 2a toward the flange 2c.

[0023] The cover 3 is coupled to the housing 2 at the flange 2c, and the inner diameter of the cover 3 is larger than the outer diameter of the cup-shaped member of the housing at least at the flange 2c.

[0024] In this way, the cover 3 can slide in a substantially telescopic manner on the cup-shaped member 2a, for example by deformation or breaking of the flange 2c, when the motor is compressed, for example by a force acting in a direction of action D1 parallel to the rotation axis R of the motor.

[0025] Preferably, in order to facilitate the crushing of the motor 1 in the direction D1 , the moulding 2 d is provided with a weakening feature 60 , which is preferably annular.

[0026] In the example shown, the feature 60 is in the form of an annular groove that weakens the moulding 2d. The feature 60 is preferably coaxial with the axis of rotation R of the motor 1 and has a diameter substantially equal to the outer diameter of the cup-shaped member 2a of the housing.

[0027] In an alternative embodiment not shown, the feature 60 is, for example, a thin portion of the molding 2 d or any other type of feature capable of defining a line of weakness of the housing 2 .

[0028] Thus, when the motor 1 is compressed in the direction D1 , the feature 60 makes it easier for the molding 2 d to collapse, allowing the cover to slide relative to the housing.

[0029] The cover 3 is provided with a wall 4 a facing or toward the interior of the housing 4 .

[0030] Preferably, in the example shown, the wall 4 a is a heat dissipation wall, that is to say it is configured to promote the dissipation of heat from components inside the housing 4 .

[0031] In this example, the cover 3 is preferably provided with a plurality of heat dissipation fins which are provided at the heat dissipation wall 4 a and face the outside of the housing 4 .

[0032] In the case of this solution, the wall 4a does not necessarily have to be heat-dissipating, but can also be made of a heat-insulating plastic material, for example.

[0033] Preferably, the motor 1 comprises a stator 5 fixedly mounted in the housing 2 and a rotor 6 comprising a shaft 6a associated with the rotor 6 and rotatably connected to the housing 4 about a rotation axis “R”.

[0034] In a preferred embodiment, the housing 4 (particularly the cover 3 ) defines an internal housing 61 towards the inside of the housing 4 in order to couple the rotor 6 to the housing 4 .

[0035] Preferably, the internal housing 61 is delimited by a substantially annular projection 62 having, for example, the shape of a tube extending around the axis of rotation “R” towards the base wall 2 b of the housing.

[0036] At the base of the protuberance 62, the cover 3 is provided with a weakened feature 63, preferably annular, defining a preferential breaking line of the cover 3 itself, as will be explained in more detail below.

[0037] In the example shown, the feature 63 is in the form of a groove and is preferably coaxial with the axis R.

[0038] In alternative embodiments, the feature 63 is, for example, a thin portion of the cover 3, or it may be made in any other way suitable for defining a line of weakness of the cover 3 itself.

[0039] In the embodiment shown by way of example, the electric machine 1 comprises a bearing 64 mounted to the shaft 6 a at a first end thereof.

[0040] The bearing 64 engages with the inner housing 61 in such a way as to rotatably connect the shaft 6 a to the housing 10 , in particular the cover 3 .

[0041] The bearing 64 is appropriately inserted into the inner housing 61 , and the inner housing 61 is at least partially shaped to match the outer surface of the bearing 64 to prevent vibration of the shaft 6 a .

[0042] When the motor 1 is compressed in the direction D1 , the feature 63 promotes rupture of the cover along the feature itself, thereby allowing the shaft 6a and the bearing 64 to move relative to each other through the cover.

[0043] In fact, see Figure 4 , when the motor 1 is compressed in the direction D1, the housing may break along feature 60 and the cover may break along feature 63, thereby allowing the cover to slide telescopically on the housing.

[0044] Schematically, the stator 5 includes: a ferromagnetic core 5a; a plurality of conductive windings 5b wound around the ferromagnetic core 5a; and a spacer inserted between the ferromagnetic core and the windings.

[0045] At least the ferromagnetic core 5a and the spacers define a stator mounting for the conductive windings 5b.

[0046] In general, the term "stator mounting portion" as used in this disclosure refers to the collection of components of the electric machine 1 that maintain the winding 5b in proper shape and position, prevent it from accidental movement, and promote heat dissipation.

[0047] Especially referring to Figure 4 , it can be observed that, in the example shown, the stator 5 abuts against a base wall 2b of the housing 2 constituting a fixed reference for the stator. Generally speaking, the stator 5 always abuts against a fixed reference in the housing 2: for example, an annular abutment element protruding from a side wall towards the inside of the housing itself in an embodiment not shown.

[0048] Thus, the stator 5 , which is usually mounted inside the housing 2 , is fixed therein and mechanically blocked by a stop against axial movement, in particular against axial movement towards the base wall 2 b , which stop itself may constitute a stop for the stator 5 , as in the example shown.

[0049] The spacers in the stator 5 (often referred to as "front sheets") are insulators, preferably made of a polymeric material.

[0050] The first front piece 40 of the stator front pieces is provided with a plurality of holes 40a extending parallel to the rotation axis "R".

[0051] The hole 40 a allows the stator 5 to be mounted on the housing 2 using a machine that uses a plurality of drill bits that pass through the hole 40 a and press directly onto the ferromagnetic core, thus preventing damage to the front sheet 40 .

[0052] The motor 1 comprises power pins 7 a and 7 b , for example positive and negative respectively, which in the illustrated embodiment pass through the housing 4 and are configured for electrical connection to a DC power source external to the motor 1 .

[0053] The electric machine 1 comprises an electronic module or electronic drive circuit 10 which in turn comprises a printed circuit board 11 or PCB and a plurality of electronic power components 12 .

[0054] In an example embodiment, the electronic power components 12 include a plurality of power transistors (eg, MOSFETs 12 a ) electrically connected to the winding 5 b to regulate the voltage and current thereof, thereby driving and controlling the rotation of the rotor 6 .

[0055] The electronic module 10 comprises a plurality of conductive tracks 20 between the power pins 7a and 7b and the electronic power component 12 to form a circuit or power line 10a for supplying power to the electronic power component 12. In the exemplary embodiment shown, the tracks 20 are arranged on the printed circuit board 11, preferably protruding thereon. More specifically, the conductive tracks 20 protrude 1.8 mm on the printed circuit board 11.

[0056] In alternative embodiments, the tracks 20 are embedded or arranged inside the PCB, for example based on the rated power of the electric machine 1 and thus on the rated power of the electronic power component 12 .

[0057] For example, Figure 5D An embodiment in which the power supply line 10 is formed in the printed circuit board 11 is shown.

[0058] exist FIG. 5A to FIG. 5D In the embodiment shown by way of example in FIG. 4 , the conductive track 20 is preferably arranged at a position facing the wall 4 a and is preferably made of a copper alloy, which is a good conductor of electricity and heat.

[0059] In the embodiment shown by way of example, as in the case where the thermally conductive filler 8b is indicated by cross-hatching, Figure 2 and Figure 3 As shown, a thermally conductive filler 8 (eg comprising thermally conductive paste) is inserted between the conductive track 20 and the wall 4a to fill the gap between these two components and promote heat conduction therebetween.

[0060] In fact, the conductive tracks 20 are in contact with the cover 3 by inserting the thermally conductive filler 8 which also acts as an electrical insulator since, in the preferred embodiment, as already mentioned, the wall 4a is a heat dissipating wall dissipating at least part of the heat in the housing 4 .

[0061] In any case, the cover 3 defines, at least in an axial direction of action D1 parallel to the axis of rotation R, an abutment element for the conductive track 20 by means of the wall 4 a.

[0062] In this example, the cover 3 defines an abutment element for the electrically conductive tracks 20 by the insertion of a thermally conductive filler 8 which also acts as an electrical insulator.

[0063] Overall, in the embodiment shown, the wall 4 a constitutes an abutment wall for the electrically conductive tracks 20 , in particular for the first tracks 21 and / or the second tracks 22 .

[0064] A thermally conductive filler 8 is preferably also inserted between at least some of the electronic power components 12 and the wall 4a, in order to promote direct dissipation of the heat generated by them.

[0065] The conductive track 20 has respective surfaces for contacting the MOSFET 12a and the wall 4a (via the thermally conductive filler 8).

[0066] In the example shown, the contact surface of the conductive trace is sized so as to form, in combination with the size of the conductive trace 20 itself, a preferential path for dissipating heat generated by the MOSFET 12 .

[0067] The plurality of conductive tracks 20 preferably include a first conductive track 21 and a second conductive track 22 which form an integral component of the power supply circuit 10a such that the supply current of the electronic power component 12 flows through them.

[0068] In the embodiment shown by way of example, the first track 21 and the second track 22 are arranged on top of the printed circuit board 11 close to the power pins 7a and 7b, preferably protruding thereon. More specifically, the first track 21 includes one of the power pins 7a and 7b, while the second track 22 is connected to the rest of the electronic module 10.

[0069] Thus, the track 21 may be a track connected to the positive power supply pin or a track connected to the negative power supply pin.

[0070] The electronic module 10 comprises a conductive element 25 , such as a metal plate or a bridge, electrically connected to the first track 21 and the second track 22 to close the power supply circuit 10 a .

[0071] Preferably, the conductive element 25 is located at the positive supply pin of the motor 1 : that is, it is preferably physically close to the pin 7a.

[0072] Preferably, the conductive element 25 is electrically close to the input of the power line 10 a , which means that in the electronic module 10 , there are no electrical or electronic components between the pin 7 a and the conductive element 25 .

[0073] The conductive element 25 is mechanically connected to the first track 21 and the second track 22 so that it can be separated from the first track 21 and the second track 22 in the event of an accident involving the electric machine 1 , as will be explained in more detail below.

[0074] In the example shown, the conductive element 25 allows current flow between the power pins 7 a and 7 b to power the plurality of electronic power components 12 and drive the rotor 6 to rotate.

[0075] The thickness of the conductive element 25 is preferably the same as the size of the trace so as not to form a resistance element that significantly affects the power circuit 10a.

[0076] The conductive element 25 is fixed to the first track 21 and the second track 22 by respective mechanically breakable joints 26 .

[0077] In Figure 5a to Figure 5D In the embodiment shown, the joint 26 is, for example, a weld comprising a brazing alloy, preferably an alloy of tin and silver.

[0078] The tab 26 is mechanically breakable in the sense that the conductive element 25 , when subjected to a mechanical thrust, causes the tab 26 to tear or break and become disconnected from the track 20 .

[0079] The force required to break the joint 26 is, for example, 4-500N.

[0080] exist Figure 5A and Figure 5B In the embodiment shown, the connector 26 is preferably heat sensitive.

[0081] exist FIG. 5A to FIG. 5D In the preferred embodiment shown by way of example in FIG. 2 , the conductive element 25 is arranged to partially overlap the first track 21 and the second track 22 to form a bridge therebetween.

[0082] exist Figure 5EIn the embodiment shown, the conductive elements 25 are substantially coplanar with the tracks 21, 22 and in any case define a bridge between them. Preferably, the conductive elements 25 extend uninterruptedly, integrally with the tracks 21, 22. In this case, in order for them to be mechanically breakable when a predetermined force is applied to the joints 26, the joints 26 are, for example, in the form of weakened lines in which the thickness of the material forming the conductive tracks 20 is smaller at the ends of the conductive elements 25. In this embodiment, the conductive elements 25 are preferably also parts of the printed circuit board 11 provided with plastic material sections which are weaker at the joint lines 26 than the rest of the printed circuit board 11, so that they are mechanically breakable to a different extent than the rest of the printed circuit board.

[0083] Preferably, the electronic module 10 , in particular the printed circuit board 11 , is mounted on a support element 13 which is arranged on the underside of the printed circuit board 11 .

[0084] The support element 13 is inserted between the electronic module and the stator 5 and the rotor 6. The support element 13 is preferably made of a self-extinguishing, electrically insulating plastic and has a receptacle for the electronic module 10.

[0085] The support element 13 has side surfaces which are shaped to match the housing 2 or the cover 3 so as to reduce in practice the possibility of movement of the electronic module 10 within the casing 4 .

[0086] The electric machine 1 comprises a plurality of elastic means 30 which act on the electronic module 10 in such a way as to press the electronic module 10 against the cover 3 .

[0087] In the example shown, the elastic device 30 comprises a metal spring 30a, which may be replaced by an elastomer or the like, for example.

[0088] In a preferred embodiment, at least some of the springs 30 a are inserted in holes 40 a of the front sheet 40 and bear with one end against the ferromagnetic core and with the other end against the support element 13 to press the entire module 10 towards the wall 4 a and away from the stator 5 .

[0089] In this way, in particular the conductive track 20 is pressed against the wall 4a.

[0090] More specifically, in the example shown, the conductive tracks 20 together with the thermally conductive filler 8 are pressed against the wall 4 a since, as mentioned above, the wall 4 a is configured to dissipate heat.

[0091] exist Figure 5A and Figure 5BIn the embodiment shown, the motor 1 comprises an elastic element 31 , preferably a metal spring, to which reference is made explicitly without loss of generality, acting on the conductive element 25 so as to exert thereon an elastic thrust away from the first and second conductive tracks 21 , 22 .

[0092] This elastic thrust is transmitted to the electronic module 10 via the joint 26, which is preferably heat-sensitive, thereby helping to push it toward the heat dissipation wall 4a.

[0093] The electric machine 1 comprises a substantially cup-shaped seat or receptacle 27 for the elastic element 31 .

[0094] The seat 27 is preferably formed in the front panel 40 .

[0095] Reference Figure 5B In the embodiment shown, the housing 27 comprises one of the holes 40 a in the front plate and passes through this hole so as to come into direct contact with the ferromagnetic core 5 a.

[0096] As shown in the figure, the first end of the elastic element 31 is preferably arranged to abut against the ferromagnetic core 5 a of the stator 5 .

[0097] On the other hand, the second end of the spring 31 is operatively arranged to bear against the conductive element 25 .

[0098] Indeed, in the embodiment shown by way of example, the spring 31 has a line of action parallel to the axis of rotation of the electric motor 1 .

[0099] A cover or spacer 32 made of an electrically insulating material is provided between the end of the spring 31 and the conductive element 25 to prevent a short circuit between the conductive element 25 and the ferromagnetic core 5a.

[0100] The electric machine 1 comprises a system 50 for releasing or separating the conductive element 25 from the tracks 21 , 22 .

[0101] The system 50 comprises a stop or retaining element 51 arranged on the side of the cover 3 opposite to the conductive element 25 .

[0102] As will become clearer below, the stop element 51 acts as a thrust element forcing the conductive element 25 to separate from the track 20 when the motor 1 is crushed.

[0103] The stop 51 is integral with the stator 5 and preferably extends parallel to the rotation axis R of the electric machine 1 .

[0104] The stop 51 is preferably formed in the front pane 40 as a single component therewith.

[0105] One end portion 51 a of the stopper 51 faces the conductive element 25 and is spaced apart from the conductive element 25 by a predetermined distance “D”.

[0106] The predetermined distance "D" is, for example, between 1 mm and 3 mm.

[0107] like Figure 5A and Figure 5B As shown, the locking element 51 comprises the receptacle 27 for the spring element 31 .

[0108] exist Figure 5B In the embodiment of FIG. 5 , the stopper 51 is substantially tubular over its entire length, and the spring 31 is arranged inside it and extends from the ferromagnetic core 5 a to the conductive element 25 .

[0109] The resilient element 31 itself may form part of the stop element 51. More specifically, the resilient element 31 may be sized to be tightly packed and to facilitate mechanical separation of the joint 26.

[0110] For example, in a compressed or closely packed configuration, the length of the elastic element 31 measured in the direction of action D1 corresponds to the length of the receptacle 27 measured in the direction D1 .

[0111] exist Figure 5A In the embodiment of FIG. 5 , the stopper 51 has a solid base portion 52 and a hollow tubular portion, which defines a receiving portion 27 for receiving the elastic element 31 .

[0112] The elastic element 31 itself forms a part of the stop element 51 .

[0113] exist Figure 5C and Figure 5D In the embodiment of FIG. 5 , the stop element 51 is shown as a single member extending from the front panel 40 , which member is preferably solid.

[0114] The printed circuit board 11 and the support element 13 are shaped so as to allow positioning of the stop element 51 between the ferromagnetic core 5 a and the conductive element 25 .

[0115] As will become clearer below, in the embodiment shown by way of example, the printed circuit board 11 and the support element 13 have a particular shape, for example being provided with respective holes 11 a, 13 a, respectively, for the passage of the stop element.

[0116] The size of the holes 11a, 13a through which the stop element 51 passes is larger than the size of the stop element 51, so that the stop element 51 can slide in, for example, the action direction D1 in the event that the motor 1 is crushed or deformed, as will become clearer below.

[0117] More specifically, in a plane transverse to the action direction D1 of the stop element 51 , the hole 11 a in the printed circuit board 11 and the hole 13 a in the support element 13 (when the printed circuit board is provided with a support element) extend over a greater length than the stop element 51 .

[0118] Preferably, the printed circuit board 11 has a recess (ie, a material missing portion) at the stop element 51 to define the hole 11 a.

[0119] In one embodiment, the material absence of the printed circuit board 11 is defined by a portion formed on its outer periphery, which is bounded by a concave end edge 14 .

[0120] Preferably, the support member 13 has a through hole 13a below and substantially at the concave portion.

[0121] like Figure 5A and Figure 5B As shown, the shape of the printed circuit board 11 and the support element 13 also allows the stop element 31 to be positioned between the ferromagnetic core 5 a and the conductive element 25 .

[0122] Preferably, the first track 21 and the second track 22 have a first end portion 21a and a second end portion 22a, respectively, which face each other and protrude toward each other from the end edge 14 to form a cantilevered conductive portion extending above the recess of the printed circuit board 11.

[0123] Preferably, the conductive element 25 is soldered to respective regions of the first and second end portions 21a, 22a, in which regions the first and second tracks are thinner than they are in the remaining structure of the first and second end portions 21a, 22a.

[0124] More specifically, in the example shown, the conductive element 25 is soldered on the first end portion 21 a and the second end portion 22 a so as to overhang the hole or material absence of the printed circuit board 11 , also due to the housing for the construction.

[0125] Preferably, the printed circuit board 11 and the conductive element 25 are constructed and positioned relative to each other in such a way that a vertical projection of the conductive element on the positioning plane of the printed circuit board 11 is completely located within the hole or the material absence.

[0126] 5 , the portion of the housing 4 above the conductive element 25 defines a receiving space “V” adapted to enable the conductive element 25 to move away from the first track 21 and the second track 22 .

[0127] When the electric machine 1 is compressed, for example, in the axial direction and the housing 2 passes through the cover 3 , the electronic module 10 and the stator 5 move relative to one another.

[0128] Considering that the housing 2 and the stator 5 are fixed and the electronic module 10 is movable, the stop element 51 passes through the holes 11a, 13a in the support element and the printed circuit board and stops the conductive element 25, forcing it to disconnect from the track 20 at the connector 26 and interrupting the flow of current, thereby making the motor 1 safe.

[0129] Considering that the electronic module 10 is fixed, the stop element 51 passes through the holes 11a, 13a in the support element and the printed circuit board and forces the conductive element 25 to be disconnected from the track 20 at the joint 26, thus interrupting the circulation of the current and making the motor 1 safe.

[0130] As already mentioned, the stop element 51 defines a thrust element that pushes the conductive element 25 off the track 20 and disconnects it from the track 20 when the machine 1 is flattened.

[0131] The conductive element 25 can move away from the first track 21 and the second track 22 under the pushing action of the stopping element 51 .

[0132] In practice, the release system 50 defines a disconnect switch for the electric power line.

[0133] The spring 31 is not essential for use as a disconnector; instead of a spring, a rigid element which is only used for removing the bridge may be provided.

[0134] When the joint 26 breaks (eg, when the weld breaks), the spring, if present, helps keep the bridge out of the way.

[0135] In the event of an accident involving a vehicle, the electric motor breaks and the electronic circuit is moved closer to the housing where it is integrated with the stator.

[0136] The cover pushes the circuit towards the housing and the stator, i.e. towards the front sheet.

[0137] When the joint 26 is broken, the front plate pushes the conductive element toward its outlet in the space V via the stop element.

[0138] When the stop element 51 forces the conductive element 25 away from the track 20, the wall 4a of the cover 3 in contact with the track 20 holds the track in place.

[0139] In the embodiment shown by way of example, the motor 1 includes a stop cap 35, which is made of an electrically insulating material and is arranged close to the conductive element 25 along the thrust direction of the elastic element 31, preferably parallel to the rotation axis R, so as to determine the stop position of the conductive element 25 driven by the elastic element 31 when the joint 26 is broken.

[0140] The stop cap 35 is preferably at least partially coupled to the support element 13 .

[0141] More specifically, the stop cap 35 is arranged in the accommodation space “V” and is preferably fixed to the printed circuit board 11 and / or the support element 13 by means of a reversible clip connection.

[0142] exist Figure 5A and Figure 5B In the embodiment, the stop cap 35 preferably stops the conductive element 25 at an extreme position, in which the elastic element 31 is still loaded and presses the conductive element 25 against the stop cap 35 to prevent further movement that may cause a short circuit between a conductive track 20 and the grounded housing 4 or between other components of the electronic module 10 and the power supply circuit 10a.

[0143] The stop position determines a distance between the conductive element 25 and each of the first track 21 and the second track 22 of, for example, at least 2 mm, preferably at least 3 mm.

[0144] In the preferred embodiment shown, the stop cap 35 comprises a cup 35 a extending into the space V and at least one flange 35 b extending at the opening of the cup towards the conductive track 20 to be inserted between the track and the cover 3 .

[0145] When the conductive element 25 is pushed into the space V by the stop element 51 , the outer flange 35 b electrically isolates the track 20 and the cover 3 from each other, thereby avoiding the risk of electrical contact between the track 20 and the cover 3 .

[0146] Preferably, the elastic element 31 is constructed to exert a residual pressure on the conductive element 25 in the stop position so as to lock the conductive element in this position in the presence of accelerations of up to 20g (preferably up to 50g) on ​​the conductive element, which may occur on the motor 1 due to high shocks or resonances in the engine compartment of a vehicle, where it is critical to keep the power circuit 10a disconnected.

[0147] In a preferred embodiment, the stop cap 35 has a concave shape, particularly at its cup-shaped portion 35a, and is configured to completely surround the conductive element 25 in the stop position. In addition, the stop cap 35 and the support element 13 are configured to define a protective cover around the conductive element 25 to prevent particles or foreign objects large enough from entering and closing the power circuit 10a when the conductive element 25 is in the stop position.

[0148] More specifically, the stopper cap 35 defines the upper portion of the cover, and a portion of the support member 13 around the through hole 13 a through which the elastic member 31 passes is configured to close the upper portion at the bottom.

[0149] Preferably, the stop cap 35 and the support element 13 are both made of a self-extinguishing electrically insulating material having a melting point at least 80°C higher than a predetermined threshold temperature, so as to keep the power circuit 10a in a disconnected state in the event of abnormally high temperatures inside the housing 4 and other faults or abnormal events.

[0150] In order to minimize the possibility that a short circuit still exists in the electronic module 10 after the power supply circuit 10a is disconnected by the conductive element 25, the conductive element 25 is arranged close to the power supply pin 7a.

[0151] The power pin 7 a is preferably one end 21 b of the first track 21 .

[0152] Thus, when the motor is crushed, the stopper 51 breaks the circuit at a point as close as possible to the power input so as to isolate or break most of the circuit in the motor.

[0153] In the event of an accident, the motor 1 is protected from short circuit.

[0154] In the example shown, the stop element allows, in the event of an accident involving the electric machine, the power supply line to be disconnected by breaking a conductive element acting as a bridge across the two parts of the line.

[0155] When the conductive element is connected to the conductive track using a layer of heat-sensitive material subjected to the force of an elastic element, it is able to cut off the power supply to the electrical components of the motor, thus also constituting an effective protection system against high temperatures and high currents.

[0156] In the motor described by way of example in this article, the elastic element that pushes the conductive element (if provided) has a dual purpose, namely, to provide the above-mentioned protection against high temperatures and high currents and to press the electronic module against a specific heat dissipation wall to promote heat dissipation; advantageously, this translates into higher production efficiency and lower production costs.

[0157] Advantageously, the thrust exerted by the elastic element 31 on the conductive element 25 generates a strain in the joint 26, and the joint 26 is constructed to mechanically resist this strain when its temperature is below a predetermined threshold temperature, in particular the melting temperature of the brazing alloy, preferably between 180°C and 250°C, and more preferably between 200°C and 230°C.

[0158] When the temperature of the joint 26 is greater than a predetermined threshold temperature, for example due to melting of the brazing alloy, the joint mechanically yields to strain and breaks, thereby causing the conductive element 25 to move away from the first conductive track 21 and / or the second conductive track 22 to break the electrical connection therebetween.

[0159] This event disconnects the power supply circuit of the power supply circuit 10a and instantly cuts off the power supply to the electronic power components 12, thereby stopping the motor 1. Advantageously, these features constitute a high temperature protection for the motor 1.

Claims

1. A motor (1), comprising: A housing (2) and a cover (3) covering the housing, the housing (2) and the cover (3) being coupled to each other to define a sealed housing (4); A stator (5) and a rotor (6) associated with the stator (5), wherein the stator (5) and the rotor (6) are both arranged in the sealed housing (4), and the stator (5) comprises a stator mounting portion (5a, 40) integrated with the housing; an electronic module (10) arranged in the sealed housing (4) between the housing and the cover and comprising a printed circuit board (11), a plurality of electronic power components (12) and a plurality of conductive tracks (20), the conductive tracks defining a power supply circuit (10a) between the respective power supply pins (7a, 7b) of the motor (1); A conductive element (25) arranged to connect a first track (21) and a second track (22) of the plurality of conductive tracks (20) to close the power circuit (10a), the conductive element (25) being held in place by at least one mechanically breakable joint (26), the at least one mechanically breakable joint (26) yielding or breaking mechanically when subjected to a predetermined force, thereby disconnecting the power circuit (10a), the motor comprising means for releasing the conductive element (25) from the first track (21) and / or the second track (22). A system (50) comprising a stop element (51) inserted between the stator (5) and the conductive element (25) to apply a predetermined force when the housing moves close to the cover, the stop element (51) being at least partially aligned with the conductive element (25) along an action direction (D1) parallel to the rotation axis (R) of the motor, the sealed housing (4) defining a receiving space (V) suitable for allowing the conductive element (25) to move away from the first track (21) and / or away from the second track (22).

2. The motor according to claim 1, wherein: The stop element (51) is arranged on a side of the cover (3) opposite to the conductive element (25).

3. The motor according to claim 1 or 2, wherein: One end portion (51a) of the stopper element (51) faces the conductive element (25) and is spaced apart from the conductive element (25) by a predetermined distance (D).

4. The motor according to claim 1 or 2, wherein: The conductive element (25) at least partially overlaps the first track (21) and the second track (22) on opposite sides of the stop element (51).

5. The motor according to claim 1 or 2, wherein: The stop element (51) has a main extension direction parallel to the rotation axis (R).

6. The motor according to claim 1 or 2, wherein: The stopping element (51) is integrated with the stator.

7. The motor according to claim 6, wherein: The stator mounting portion includes a spacer (40) facing the electronic module (10), and the stopper element (51) extends from the spacer (40).

8. The electric machine according to claim 7, wherein: The stop element (51) is made as a single component with the spacer (40).

9. The motor according to claim 1 or 2, wherein: The printed circuit board (11) is provided with a hole (11a) for the stopper element (51) to pass through, and the printed circuit board (11) is inserted between the conductive element (25) and the stator (5).

10. The motor according to claim 9, comprising a supporting element (13) inserted between the electronic module (10) and the stator (5) to support the electronic module (10), the supporting element (13) being provided with a hole (13a) for the stop element (51) to pass through.

11. The electric machine according to claim 10, wherein: In a plane transverse to the action direction (D1), the hole (11a) in the printed circuit board (11) and the hole (13a) in the support element (13) extend over a greater length than the stop element (51), so that when the motor is crushed and deformed, the stop element (51) can slide through the hole (11a) in the printed circuit board (11) and the hole (13a) in the support element (13).

12. The electric machine according to claim 1 or 2, wherein: At least for the first track (21) and / or the second track (22), the sealing housing (4) has at least one abutment wall (4a).

13. The electric machine according to claim 12, wherein: The abutment wall (4a) is a wall of the cover (3) and the first track (21) and the second track (22) directly face the cover.

14. The electric machine according to claim 12, wherein: The abutment wall (4a) is a heat dissipation wall, and the motor comprises: a heat conductive filler (8) inserted between the electronic module (10) and the sealed housing (4) to promote heat conduction from the electronic module (10) to the heat dissipation wall (4a); an elastic device (30) acting on the electronic module (10) to press the electronic module (10) against the heat dissipation wall (4a) of the sealed housing (4), thereby compressing the thermally conductive filler (8); The elastic means (30) comprises an elastic element (31) which is pressed against the conductive element (25) to exert an elastic thrust on the at least one mechanically breakable joint (26).

15. The electric machine according to claim 14, wherein: The at least one mechanically breakable joint (26) is heat-sensitive and is configured to break under the elastic thrust when subjected to a temperature higher than a predetermined threshold temperature, thereby disconnecting the power circuit (10a), and the stop element (51) includes the elastic element (31).

16. The electric machine according to claim 14, wherein: The stop element (51) comprises a receiving portion (27) for receiving the elastic element (31).

17. The electric machine according to claim 16, wherein: The stop element (51) is tubular over its entire length and defines the housing (27), the elastic element (31) is arranged in the stop element (51) and extends from the ferromagnetic core (5a) of the stator to the conductive element (25), the elastic element (31) being electrically isolated to avoid a short circuit between the ferromagnetic core (5a) and the conductive element.

18. The electric machine according to claim 16, wherein: The stop element (51) comprises a solid base portion (52) and a hollow tubular portion defining the housing (27), and the elastic element (31) extends from the base portion (52) to the conductive element (25) in the housing (27).

19. The electric machine according to claim 17, wherein: The elastic element (31) has a compressed or tightly packed configuration, the length of which measured in the direction of action (D1) is comparable to the length of the receiving portion (27) measured in the direction of action (D1), thereby facilitating the mechanical separation of the at least one mechanically breakable joint (26).

20. The electric machine according to claim 1 or 2, wherein: The at least one mechanically breakable joint (26) is made of a soldering alloy and the conductive element (25) is soldered to the first track (21) and / or the second track (22).

21. The motor according to claim 1 or 2 comprises a stop cap (35) made of an electrically insulating material and arranged along the action direction (D1) of the stop element (51), and the stop element (51) is constructed to move the conductive element (25) toward the stop cap (35) after the at least one mechanically breakable joint (26) is broken.

22. The electric machine according to claim 21, wherein The stop cap (35) includes a cup-shaped portion (35a) extending into the accommodating space (V) and at least one flange (35b), wherein the at least one flange extends from the cup-shaped portion toward the first track (21) and the second track (22) so as to be inserted between the first track (21) and the second track (22) and the cover (3).

23. The electric machine according to claim 1 or 2, wherein: The housing (2) includes a cup-shaped member (2a) into which the stator (5) is inserted, the cup-shaped member being defined at the bottom by a base wall (2b) and having an open end on the side opposite to the base wall (2b), an annular flange (2c) radially extending from the cup-shaped member (2a) at the open end, the cover (3) being connected to the housing (2) at the flange (2c), the inner diameter of the cover (3) being greater than the outer diameter of the cup-shaped member (2a) of the housing (2) at least at the flange (2c).

24. The electric machine according to claim 23, wherein The flange (2c) is connected to the cup-shaped member (2a) by a molding (2d), the molding (2d) widens from the cup-shaped member (2a) toward the flange (2c), and the molding (2d) has a first weakening feature (60) for weakening the molding (2d) itself.

25. The electric machine according to claim 24, wherein The first weakened feature (60) comprises an annular groove having a diameter equal to the outer diameter of the cup-shaped member (2a) of the housing (2).

26. The electric machine according to claim 1 or 2, wherein: The cover (3) defines an internal housing (61) facing the interior of the sealed housing (4) for connecting the rotor (6) to the sealed housing (4), the internal housing (61) being defined by a protrusion (62) extending around the rotation axis (R) toward the base wall (2b) of the housing (2), and the cover (3) having a second weakening feature (63) defining a preferential rupture line of the cover (3).

27. The electric machine according to claim 1 or 2, wherein: The cover (3) defines abutment elements for the first track (21) and the second track (22) at least in the action direction (D1), the electronic module (10) is inserted between the cover and the stator, and the motor includes an electrical insulator inserted between the first track (21) and the second track (22) and the cover (3).

28. The electric machine according to claim 1 or 2, wherein: The conductive element (25) is arranged close to the positive power pin (7a) and / or the negative power pin (7b) of the motor.

29. The electric machine according to claim 28, wherein The electronic module (10) does not include any electrical or electronic components between the positive power supply pin (7a) and the conductive element (25) and / or between the negative power supply pin (7b) and the conductive element (25).

30. The electric machine according to claim 3, wherein The predetermined distance is between 1 mm and 3 mm.

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