Motor

Abstract

An electric machine comprises: an electronic module (1) comprising a printed circuit board (2), at least one conductive trace coupled to the printed circuit board (2) and at least partially defining a power supply circuit, a conductive element (7) arranged to connect a first trace portion of the conductive trace and a second trace portion of the conductive trace to determine a closure of the power supply circuit; the electronic module (1) comprises a first heat-sensitive joint between a conductive element (7) and the first trace portion, the conductive element being held in position by the heat-sensitive joint and being positioned relative to the conductive trace on an opposite side to the printed circuit board (2); the motor comprises an elastic element (15) pressed against the conductive element (7) to exert a force (F) on the heat-sensitive joint, and a support (11) housing the electronic module (2), said heat-sensitive joint being configured to yield to said force (F) when subjected to a temperature above a predetermined threshold temperature; the electronic module (1) is accommodated in the support (11), wherein the conductive traces and the conductive elements (7) are arranged towards the support (11); an elastic element (15) is arranged on the side opposite the conductive trace with respect to the support (11) and operates between the conductive element (7) and the support (11) such that a force (F) urges the conductive element away from the conductive trace.

Description

Technical Field

[0001] This invention relates to an electric motor, and more particularly to an electric motor for automotive applications. Background Technology

[0002] Increasingly common in the automotive industry is the use of electric motors as motors to drive fans, which are designed to remove heat, for example, from heat sinks used to cool vehicle motors.

[0003] In such applications, the market demand is for motors to meet increasingly stringent safety requirements, as well as to protect vehicles from malfunctions and abnormal events related to the motor itself, which could cause the motor to experience a sudden increase in temperature.

[0004] In particular, in this field, there is a need for an inherent safety mechanism to shut off the motor's power supply in case of overheating, before the temperature could reach a level considered dangerous.

[0005] The purpose of the European patent EP3641110 under the name of the applicant is an electric motor in which a conductive element is electrically connected to two branches of a conductive power supply trace via two thermal connectors.

[0006] Conductive traces and conductive elements form part of the motor's electronic power circuit, which is pressed against the motor's cover for heat dissipation.

[0007] The conductive element is pressed off the trace by a spring, which forms part of the elastic system that forces the electronic system against the cover and applies force to the thermal connector.

[0008] These connectors are designed to yield when subjected to temperatures above a predetermined threshold temperature, such that when the connector yields, a spring pushes the conductive element away from the trace, thereby disconnecting the power circuit.

[0009] The applicant has noted the critical drawbacks of existing solutions where the outline of the PCB for the electronic circuitry must allow the spring to pass through.

[0010] Because incorrect positioning can cause the protection system to malfunction, another key drawback noted by the applicant is the difficulty in checking whether the spring is correctly positioned.

[0011] In this context, our intention is to propose an electric motor and its assembly method that can overcome at least some of the shortcomings of the prior art and meet the aforementioned needs. Summary of the Invention

[0012] One object of the present invention is to provide a motor equipped with a protection system that does not require the PCB of the electronic circuit to have a special profile shape.

[0013] One object of the present invention is to provide a motor equipped with a protection system that is more reliable than the protection systems of the prior art.

[0014] These objectives are achieved by an electric motor and a method of assembling the same, which include the technical features described in one or more of the appended claims. The dependent claims correspond to different possible embodiments of the invention.

[0015] According to a first aspect, the present invention relates to an electric motor.

[0016] The motor includes an electronic power module that includes a printed circuit board and a plurality of conductive traces connected to the printed circuit board and at least partially defining a power circuit.

[0017] Conductive traces can be added to and connected to a printed circuit board or integrated into a separate structure (frame) within the printed circuit board itself.

[0018] The electronic module includes a conductive element configured to connect a first trace and a second trace in a conductive trace, and positioned relative to the conductive trace on a side opposite to the printed circuit board.

[0019] The electronic module includes a thermal connector between the connection portion of the conductive element and the first conductive trace, so that the conductive element is held in place by the thermal connector.

[0020] The motor includes an elastic element that presses against a conductive element to apply a force to a thermal connector, the thermal connector being configured to yield to the force when subjected to a temperature above a predetermined threshold temperature.

[0021] The conductive element determines the closure of the power supply circuit by electrically connecting the first and second traces. Yielding of the thermal connector causes the power supply circuit to open.

[0022] The motor includes a support structure that houses the electronic modules.

[0023] The electronic module is housed in a support, with conductive traces and conductive elements facing the support.

[0024] The elastic element is positioned relative to the support on the side opposite to the conductive trace.

[0025] The elastic element operates between the conductive element and the support, such that when the thermal connector yields, the force of the elastic element pushes the conductive element away from the conductive trace.

[0026] Preferably, the support has a seat for the electronic module, and preferably, the electronic module is secured in the respective seat.

[0027] Preferably, the support has a plurality of support teeth for the printed circuit board.

[0028] Preferably, the support has a cavity or opening at the conductive element. The conductive element preferably has a protrusion that extends from the connection portion to the first trace via a thermal connector. The protrusion is preferably inserted into the opening of the support in a manner that it passes through the support, and the elastic element is positioned relative to the support on the side opposite to the conductive trace.

[0029] Preferably, the elastic element operates between the protruding portion of the conductive element and the support, such that the force of the elastic element pushes the connecting portion of the conductive element away from the conductive trace toward the support.

[0030] Preferably, the elastic element is a leaf spring.

[0031] Preferably, the support has a seat for the elastic element.

[0032] Preferably, the shape of the seat for the elastic element and the elastic element are such that the elastic element will not accidentally come out of the seat once inserted.

[0033] Preferably, especially when the elastic element is a leaf spring, the seat of the elastic element is defined by at least two parallel side bands that define a guide for inserting the leaf spring into the seat.

[0034] Preferably, the leaf spring has at least one coiled end to make it easier to insert the spring into the corresponding seat.

[0035] The elastic element may include bimetal.

[0036] When the elastic element is a spring, the conductive element is subjected to a basically fixed constant force, regardless of whether the motor is running.

[0037] When the elastic element includes a bimetal, the force on the conductive element varies with temperature. The bimetal and the thermal connector are configured such that at a predetermined threshold temperature, the force of the bimetal corresponds at least to the force to which the thermal connector yields.

[0038] Advantageously, by using bimetallic materials, on average, at least the thermal connector is subjected to strain only when the motor is running, thus reducing the stress on the thermal connector.

[0039] Advantageously, bimetallic elastic elements are easier to insert into the seat because they typically have less deformation or preload than springs.

[0040] Preferably, the support includes at least one stop for connecting the portion, positioned along the thrust direction of the elastic element.

[0041] Preferably, the elastic element is configured to move the conductive element toward the stop after the thermal connector yields.

[0042] Preferably, the stop is positioned to block the conductive element at the stop position so that the elastic element can continue to press against the conductive element, particularly against its protrusion, and has sufficient residual pressure to keep the connection portion against the stop.

[0043] Preferably, the conductive element includes a (second) connection portion for connecting the conductive element to the second trace, and is positioned relative to the protrusion on the side opposite to the (first) connection portion described above.

[0044] Preferably, the conductive element is soldered to the second trace via a corresponding (second) connection portion and a corresponding (second) thermal connector.

[0045] Preferably, the conductive element is positioned to overlap with the first and second traces to define a bridging member that bridges the first and second traces. Preferably, the protruding portion defines a crown of the bridging member that is substantially Ω-shaped.

[0046] Preferably, the support includes a (second) stop for the (second) portion, positioned along the thrust direction of the elastic element. Preferably, the elastic element is configured to move the conductive element toward the (second) stop after the (second) thermal connector yields.

[0047] (Second) The stop is positioned to block the conductive element at the blocking position so as to continue pressing the elastic element against the conductive element, and has sufficient residual pressure to keep the (second) connection portion against the (second) stop.

[0048] The support may include a connecting fitting between a first stop and a second stop, substantially at the conductive element. The first stop, the connecting fitting, and the second stop define a cavity in the support.

[0049] Preferably, the support includes at least one protrusion at and facing the first trace to resist movement of the first trace away from the printed circuit board when the thermal connector yields. The resilient element may also actually carry away the first trace, which is instead blocked by the protrusion, by pushing the conductive element under high-temperature conditions that could damage all solder joints on the electronic module.

[0050] According to one aspect, the present invention relates to a method for assembling an electric motor according to the foregoing aspect.

[0051] The method includes: assembling an electronic module including a conductive element, connecting the electronic module to a support, and after connecting the electronic module to the support, engaging an elastic element with a protruding portion of the conductive element and the support. Attached Figure Description

[0052] Further features and advantages of the invention become more apparent in the exemplary, and therefore non-limiting, description of preferred, but not exclusive, embodiments of the motor and its assembly method.

[0053] The following description is based on the accompanying drawings, which are provided for illustrative purposes only and do not limit the scope of the invention. In the drawings:

[0054] Figure 1 An exploded perspective view shows the motor according to this disclosure;

[0055] Figure 2 Shown in 3D Figure 1 Details of the motor, some parts have been cut off for better clarity;

[0056] Figure 3 Shown in 3D Figure 1 Details of the motor, some parts have been cut off for better clarity;

[0057] Figure 4 Shown in three-dimensional cross-section Figure 1 Details of the motor, some parts have been cut off for better clarity;

[0058] Figure 5 Shown in three-dimensional cross-section Figure 1 Details of the motor, some parts have been cut off for better clarity;

[0059] Figure 6 The details of the motor according to this disclosure are shown in a schematic perspective view;

[0060] Figure 7 Shown in three-dimensional cross-section Figure 6 Details;

[0061] Figure 8 The details of the motor according to this disclosure are shown in a schematic perspective view;

[0062] Figure 9 Shown in cross section Figure 8 Details. Detailed Implementation

[0063] refer to Figure 1 The number 100 indicates an electric motor as described in detail herein only to the extent necessary for understanding this disclosure.

[0064] Motor 100 is a rotary motor, and in its preferred embodiment, it is a sealed type brushless electric motor, meaning that there are no openings inside it except for a possible pressure reducing valve. This embodiment is explicitly referenced without loss of generality.

[0065] The motor 100 includes a housing 101 and a cover 102, the cover 102 being used to close the housing 101 to define, together with the housing 101, a closed, preferably sealed, enclosure or container.

[0066] The motor 100 includes a stator 103 inserted into and locked in a housing 101. The stator 103 is preferably of the wound type and will not be described further.

[0067] The motor 100 includes a rotor 104, which preferably has permanent magnets (not further described), and the rotor 104 is associated with a stator 103 and rotatably connected to a housing 101 and a cover 102 about a rotation axis R.

[0068] The motor 100 includes an electronic module, which is represented by the number 1, and in the embodiment shown as an example, the electronic module is inserted into and housed in a cover 102.

[0069] Electronic module 1 includes a printed circuit board 2 (or PCB) and multiple electronic power components 3 and corresponding power supply pins 4.

[0070] The electronic power component 3 includes, for example, multiple power transistors, such as MOSFETs, power capacitors, and other components not shown. The MOSFETs are electrically connected to the stator 103, for example, to modulate its voltage and current, thereby driving and controlling the rotation of the rotor 104.

[0071] Electronic module 1 includes multiple conductive traces, one of which is represented by the numeral 5 by way of example, connecting to printed circuit board 2 between power supply pin 4 and electronic power component 3 to form power supply circuit 6 for powering electronic power component 3.

[0072] Conductive trace 5 is connected to the bottom surface 2a of printed circuit board 2.

[0073] In the illustrated embodiment, the conductive trace 5 is in the form of a separate structure (frame) added to and connected to the printed circuit board 2.

[0074] In an alternative embodiment not shown, the conductive trace 5 is integrated in the printed circuit board 2 and is accessible from the bottom surface 2a of the printed circuit board 2.

[0075] The electronic module 1 includes a conductive element 7 configured to connect a first trace portion 5a and a second trace portion 5b of the conductive trace 5.

[0076] The conductive element is positioned on the side opposite to the printed circuit board 2 relative to the conductive trace 5.

[0077] In the embodiment shown as an example, the conductive element 7 has a first connecting portion 7a for connecting the trace portion 5a and a second connecting portion 7b for connecting the trace portion 5b.

[0078] The conductive element 7 has a protruding portion 7c, which in the example shown protrudes from the first connecting portion 7a and the second connecting portion 7b.

[0079] The protruding portion 7c is spaced apart from the first connecting portion 7a and the second connecting portion 7b on the opposite side of the conductive trace 5.

[0080] The second connecting portion 7b is positioned on the side opposite to the protruding portion 7c.

[0081] In the example shown, the conductive element 7 is positioned to overlap with the first trace portion 5a and the second trace portion 5b in order to define a bridging element that bridges the first trace portion 5a and the second trace portion 5b.

[0082] The protruding part 7c defines the crown of the bridge member, which is basically Ω-shaped.

[0083] The electronic module 1 includes a first thermal connector 8a between the first connection portion 7a and the first trace portion 5a of the conductive element 7, so that the conductive element 7 is held in place by the first thermal connector 8a.

[0084] In the example shown, the electronic module 1 includes a second thermal connector 8b between the second connection portion 7b and the second trace portion 5b of the conductive element 7, so that the conductive element 7 is held in place by the second thermal connector 8b.

[0085] The thermal connectors 8a and 8b are formed by welding and include a brazing alloy layer, preferably an alloy of tin and silver.

[0086] Preferably, and particularly to prevent the conductive element 7 from rotating when soldered to the trace 5, the first trace portion 5a and the second trace portion 5b each have corresponding seats 9 and 10. Preferably, the shapes of the first connecting portion 7a and the second connecting portion 7b respectively match the corresponding seats 9 and 10.

[0087] The motor 1 includes a support 11 that houses the electronic module 1.

[0088] The electronic module 1 is housed in the support member 11, wherein the conductive traces 5 and the conductive elements 7 are arranged toward the support member 11.

[0089] The support 11 has a seat 12 for the electronic module 1, and preferably, the electronic module 1 is fastened in the seat 12.

[0090] In the illustrated embodiment, the support member 11 has a plurality of support teeth 13 for supporting the printed circuit board 1, wherein one of the support teeth 13 is in Figure 5 As shown in the image.

[0091] The support member 11 is inserted between the electronic module 1 and the stator 103.

[0092] The support member 11 is preferably made of self-extinguishing electrically insulating plastic.

[0093] The support 11 has a side surface that matches the shape of the cover 102 in order to reduce the possibility of movement of the electronic module 1 in practice.

[0094] The support member 11 has an opening or cavity 14 at the conductive element 7.

[0095] The protruding part 7c is inserted into the opening 14 so as to pass through the support member 11, for example, as shown in the image. Figure 2 and Figure 6 As shown.

[0096] The motor 100 includes an elastic element 15 that presses against the conductive element 7 to apply a force F to the thermal connectors 8a and 8b.

[0097] The thermal connectors 8a and 8b are configured to yield to force F when subjected to a temperature above a predetermined threshold temperature.

[0098] The conductive element 7 determines the closure of the power supply circuit 6 by electrically connecting the first trace portion 5a and the second trace portion 5b, and the yielding of the thermal connectors 8a and 8b causes the power supply circuit 6 to be disconnected.

[0099] In an alternative embodiment not shown, the conductive element 7 is fixed to one of the first trace portion 5a and the second trace portion 5b only by corresponding thermal connectors 8a, 8b, and is permanently electrically connected to the other, such that if the temperature rises above a threshold temperature, the individual thermal connectors 8a, 8b break under the pressure of the elastic element 15, causing the power circuit 6 to disconnect.

[0100] The elastic element 15 is positioned relative to the support 11 on the side opposite to the conductive trace 5.

[0101] The elastic element 15 operates between the conductive element 7 and the support 11, such that the force F pushes the connecting portions 7a and 7b of the conductive element 7 away from the conductive trace 5 toward the support 11.

[0102] The elastic element 15 operates between the protruding portion 7c of the conductive element 7 and the support member 11, such that the force F pushes the connecting portions 7a and 7b of the conductive element 7 away from the conductive trace 5 toward the support member 11.

[0103] In the example shown, the elastic element 7 is inserted between the protruding portion 7c of the conductive element 7 and the support 11, such that the force F pushes the connecting portions 7a and 7b of the conductive element 7 away from the conductive trace 5 toward the support 11.

[0104] In the example shown, the elastic element 7 is a leaf spring.

[0105] As shown in the figure, the support member 11 has a seat 16 for the elastic element 15.

[0106] The shapes of the seat 16 and the elastic element 15 ensure that the elastic element 15 will not accidentally come out of the seat 16 once it is inserted into the seat 16.

[0107] In an exemplary embodiment, the seat 16 for the resilient element 15 is defined by at least two parallel side straps 17, 18, which define guides for inserting the resilient element 15 into the seat 16.

[0108] As shown, the elastic element 15 has at least one curled end 15a to make it easier to insert the elastic element 15 into the corresponding seat 16.

[0109] In embodiments not shown, the elastic element 15 may include a generally known bimetallic material.

[0110] Special Reference Figure 4 and Figure 9 It should be noted that in the illustrated embodiment, the support member 11 includes a first stop 19 for the first connecting portion 7a, positioned along the thrust direction of the elastic element 15.

[0111] The direction of the thrust of the elastic element 15 basically corresponds to the direction of the force F parallel to the axis of rotation R.

[0112] Preferably, the elastic element 15 is configured to move the conductive element 7 toward the first stop 19 after the first thermal connector 8a yields.

[0113] The stop 19 is positioned to block the conductive element 7 in a stopped position so that the elastic element 15 can continue to press against the conductive element 7, particularly against its protruding portion 7c, and has sufficient residual pressure to keep the connecting portion 7a against the stop 19.

[0114] Preferably, the support includes a second stop 20 for the second connection portion 7b, positioned along the thrust direction of the elastic element 15. The elastic element 17 is configured to move the conductive element 7 toward the second stop 20 after the second thermal connector 8b yields.

[0115] The second stop 20 is positioned to block the conductive element 7 in a stopped position so that the elastic element 15 can continue to press against the conductive element 7, and has sufficient residual pressure to keep the second connecting portion 7b against the second stop 20.

[0116] exist Figure 6 and Figure 7 In one embodiment, the support 11 has no stops 19 and / or 20 and the conductive element 7 moves freely away from the support 11 after the first thermal connector 8a and / or the second thermal connector 8b yields.

[0117] exist Figure 8 and Figure 9 In one embodiment, the support member 11 includes a connecting fitting 22 for connecting the first stop 19 to the second stop 20.

[0118] The first stop 19, the connecting fitting 22, and the second stop 20 define the cavity 14 in the support member 11.

[0119] Preferably, the support 11 includes at least one protrusion 21 at and facing the first trace portion 5a to resist movement away from the printed circuit board 2 when the first thermal connector 8a yields. The elastic element 15 may also actually carry away the first trace portion 5a by pushing the conductive element 7 under high-temperature conditions that could damage all solder joints on the electronic module 1, whereby the first trace portion 5a is instead blocked by the protrusion 21.

[0120] The method for assembling the motor 100 is described only to the extent necessary for understanding this disclosure, and for simplicity, reference is made to the machine 1 of the type described above.

[0121] The method includes: assembling an electronic module 1 including a conductive element 7, connecting the electronic module 1 to a support 11, and after connecting the electronic module 1 to the support 11, engaging an elastic element 15 with the conductive element 7 and the support 11.

[0122] Specifically, the assembly method includes engaging the elastic element 15 with the protruding portion 7c of the conductive element 7.

[0123] In the example shown, the elastic element 15 is a leaf spring, which is preferably inserted into the seat 16 by translation. The leaf spring is inserted below the conductive element 7 having the coiled portion 15a and is pushed in until it is fully inserted into the seat 16.

Claims

1. An electric motor, comprising: - An electronic module (1), comprising: a printed circuit board (2); at least one conductive trace (5) connected to the printed circuit board (2) and at least partially defining a power circuit (6); a conductive element (7) configured to connect a first trace portion (5a) and a second trace portion (5b) of the conductive trace (5) to determine the closure of the power circuit (6), the electronic module (1) comprising a first thermal connector (8a) between a first connection portion (7a) of the conductive element (7) and the first trace portion (5a), the conductive element (7) being held in place by the first thermal connector (8a) and positioned relative to the conductive trace (5) on a side opposite to the printed circuit board (2), the motor comprising: - An elastic element (15) presses against the conductive element (7) to apply a force (F) to the first thermal connector (8a), which is configured to yield to the force (F) when subjected to a temperature above a predetermined threshold temperature, thereby disconnecting the power circuit (6). - A support (11) for accommodating the electronic module (2), the motor being characterized in that the electronic module (1) is accommodated in the support (11), wherein the conductive trace (5) and the conductive element (7) face the support (11), and the elastic element (15) is disposed on the side opposite to the conductive trace (5) relative to the support (11) and operates between the conductive element (7) and the support (11) such that the force (F) pushes the first connecting portion (7a) away from the conductive trace (5).

2. The motor according to claim 1, characterized in that, The support member (11) is provided with a first seat (16) for the elastic element (15).

3. The motor according to claim 1 or 2, characterized in that, For the first connection portion (7a), the support (11) includes a first stop (19) positioned along the thrust direction of the elastic element (15), the elastic element (15) being configured to move the conductive element (7) toward the first stop (19) after the first thermal connector (8a) yields.

4. The motor according to claim 3, characterized in that, The first stop (19) is positioned to block the conductive element (7) at the stop position so as to continue pressing the elastic element (15) against the conductive element (7) and have sufficient residual pressure to keep the first connection portion (7a) against the first stop (19).

5. The motor according to any one of the preceding claims, characterized in that, The conductive element (7) includes a second connecting portion (7b) positioned relative to the protrusion (7c) on the side opposite to the first connecting portion (7a). The conductive element (7) is connected to the second trace portion (5b) via the second connecting portion (7b) and a second thermal connector (8b). The conductive element (7) is positioned to overlap with the first trace portion (5a) and the second trace portion (5b) to define a bridging member that bridges the first trace portion (5a) and the second trace portion (5b). The protrusion (7c) defines the crown of the bridging member.

6. The motor according to claim 5, characterized in that, For the second connection portion (7b), the support (11) includes a second stop (20) positioned along the thrust direction of the elastic element (15), the elastic element (15) being configured to move the conductive element (7) toward the second stop (20) after the second thermal connector (8b) yields.

7. The motor according to claim 6, characterized in that, The second stop (20) is positioned to block the conductive element (7) at the stop position so as to continue pressing the elastic element (15) against the conductive element (7) and have sufficient residual pressure to keep the second connection portion (7b) against the second stop (20).

8. The motor according to any one of the preceding claims, characterized in that, The support member (11) includes a first stop (19) for the first connecting portion (7a) and a second stop (20) for the second connecting portion (7b), the first stop and the second stop being positioned along the thrust direction of the elastic element (15), the elastic element (15) being configured to move the conductive element (7) toward the second stop (20) after the second thermal connector (8b) yields, and the support member (11) including a connecting fitting (22) for connecting the first stop (19) to the second stop (20).

9. The motor according to any one of the preceding claims, characterized in that, The elastic element (15) is a leaf spring.

10. The motor according to claim 9, characterized in that, The support (11) is provided with a seat (16) for the leaf spring, the seat (16) being defined by at least two parallel side straps (17, 18) defining guides for inserting the leaf spring into the seat (16).

11. The motor according to claim 9 or 10, characterized in that, The leaf spring has at least one curled end (15a).

12. The motor according to any one of the preceding claims, characterized in that, The elastic element (15) comprises a bimetal.

13. The motor according to any one of the preceding claims, characterized in that, The support member (11) is provided with a plurality of support teeth (13) for the printed circuit board (2).

14. The motor according to any one of the preceding claims, characterized in that, The support (11) includes at least one protrusion (21) at the first trace portion (5a) to resist movement of at least the first trace portion (5a) away from the printed circuit board (2) when the first thermal connector (8a) yields.

15. The motor according to any one of the preceding claims, characterized in that, The support member (11) has an opening (14) at the conductive element (7), the conductive element (7) having a protruding portion (7c) protruding from the first connecting portion (7a), the protruding portion (7c) being inserted into the opening (14) so ​​as to pass through the support member (11).

16. A method for assembling an electric motor, said electric motor being the type according to any one of claims 1 to 15, the method comprising: - Assemble the electronic module (1) including the conductive element (7); - Connect the electronic module (1) to the support (11); - After the electronic module (1) is connected to the support (11), the elastic element (15) is engaged with the conductive element (7) and the support (11).

Images