ELECTRIC MOTOR

Abstract

An electric motor includes an assembly for connection to a printed circuit having a conductive insert through which connection holes pass, and a coil assembly having electrical connections terminated by connection plugs. The motor further includes connection pieces comprising a rod, the outer cross-section of which matches the cross-section of the connection holes, the connection piece having, at the proximal end thereof, a shoulder with a cross-section greater than the cross-section of the connection holes, the opposite end having a slot extending up to the shoulder, and including an opening on the distal end with a width greater than or equal to the cross-section of the connection plugs and at least one narrowing with a width less than the cross-section of the connection plugs, in order to ensure the expansion of the collar of the connection piece engaged in the hole of the printed circuit insert.

Claims

1. An electric motor comprising a connection assembly to a printed circuit that has a conductive insert through which connection holes pass and a coil assembly with electrical connections terminated by connector plugs, connection pieces comprising a rod, an outer cross-section of which matches a cross-section of said connection holes, the connection piece that has at a proximal end a shoulder with a cross-section greater than the section of said connection holes, an opposite end that has a slot extending up to said shoulder, and comprising an opening on a distal end whose width is larger than or equal to said cross-section of said connector plugs and at least a narrowing of a width less than said cross-section of said connector plugs, in order to ensure expansion of a collar of said connection piece engaged in said hole of said printed circuit insert.

2. The electric motor according to claim 1, wherein said slot extends beyond said shoulder, in a proximal direction, with said connection piece that has at least one external groove to enable its insertion through an elastic deformation of said insert hole.

3. The electric motor according to claim 1, wherein said connection piece has two elastically deformable limbs extending in a form of a shoulder and creating a slot with at least one shrinking.

4. The electric motor according to claim 1, wherein said connection holes have a central portion delimited by two parallel straight edges spaced apart by a width corresponding to a thickness of said connection piece at a level of said shoulder, said central part being extended on both sides by an enlarged area.

5. The electric motor according to claim 4, wherein said enlarged areas have distant edges spaced apart by a width corresponding to width of said collar of said connection piece.

6. The electric motor according to claim 3, wherein said limbs have an internal protuberance forming said shrinking.

7. The electric motor according to claim 1, wherein each of said limbs has an external reinforcement area below said collar, and each of said limbs has locking lugs extending from a lower end of said reinforcement to a lower level of said collar.

8. The electric motor according to claim 1, wherein said connection piece is made up of a superposition of a multiplicity of conducting sheets.

9. The electric motor according to claim 1, wherein said coil assembly is placed inside a tubular rotor, with said coil assembly being made of coils borne by teeth including a packet of ferromagnetic sheets, said teeth extending radially in relation to a tubular ferromagnetic core surrounding a core of conductive material thermally showing a first section in contact with a housing and a second section in contact with said tubular core of said motor; said core being in contact with the external housing of said motor in order to ensure evacuation of heat produced by coils.

10. The electric motor according to claim 1, wherein said thermal conductor material has a T-shape.

11. The electric motor claim 1, wherein said conductor has a hole for passage of an axle attached to a tubular rotor and driving a magnet set near a detection probe attached to said printed circuit placed in an extension of a core.

12. The electric motor according to claim 1, further comprising a detection probe placed in an axis of a core.

13. The electric motor according to claim 11, further comprising a recess of said core has at least one bearing for guiding said tubular rotor axis.

14. The electric motor according to claim 11, wherein said rotor comprises a transverse face with at least one through-light to ensure flow to the coil assembly.

15. The electric motor according to claim 14, wherein said through-light is configured to ensure forcing of air flowing during rotation of said rotor.

16. The electric motor according to claim 11, further comprising a ferromagnetic protuberance including an armour close to said detection probe.

17. A connection assembly comprising: a printed circuit including a conductive insert through which connection holes and a plurality of electrical connections terminated by complementary connector plugs; and connection pieces comprising a rod, an outer cross-section of which matches a cross-section of said connection holes, each of said connection pieces including at a proximal end thereof, a shoulder with a cross-section greater than said cross-section of said connection holes, an opposite end having a slot extending up to said shoulder, and a hole on a distal end with a width larger than or equal to said cross-section of said connector plugs, and at least one narrowing with a width less than said cross-section of said connector plugs, in order to ensure expansion of a collar of at least one of said connection pieces engaged in said hole of said printed circuit insert.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] This invention will be better understood upon reading the following description, with reference to the attached drawings where:

[0016] FIG. 1 shows a cross-sectional view of the entire connection assembly of the invention;

[0017] FIG. 2 shows a cross-sectional view of a connection assembly of the invention in the insert plane;

[0018] FIG. 3 shows a cross-sectional view of a variant embodiment of the connection piece;

[0019] FIG. 4 shows a cross-sectional view of a motor with an external rotor according to the invention; and

[0020] FIG. 5 shows a lower three-quarter view of the motor according to the invention.

DETAILED DESCRIPTION

Structure of the Connection System

[0021] FIG. 1 represents an exemplary embodiment of a connection piece (1) with two parallel limbs (2, 3) linked to a head (4). The connection system comprises several connection pieces (1) and a printed circuit (10) with complementary metallic inserts (7). The two limbs (2, 3) define a slot (5) between them extending up to the collar (6). The connection piece (1) is made up of a stack of cut sheets. The part (1) is housed in a metal insert (7) placed between two insulating layers (8, 9) in order to form a printed circuit comprising known conductive tracts (28) in the surface of at least one of the insulating layers.

[0022] The insert (7) has an oblong shearing (11) with an enlarged view in FIG. 2. The shearing (11) has a central area delimited by two parallel straight edges (12, 13) in contact with the lateral surfaces of the head (4) of the connection piece (1). This central area extends on both sides through protuberances (15, 16) with a greater width and each has an edge (17, 18) with a complementary shape to the respective limbs (2, 3), at the collar (6) of the connection piece (1).

[0023] The areas of electrical contact between the connection piece (1) and insert (7) correspond to the edges (12, 13 and 17, 18). The insert (7) has a thickness of approximately 1 millimetre, preferably between 0.5 and 2 millimetres, thus guaranteeing enough contact surface for the passage of high electric currents, for example, 10 KW for a current of 200 amperes at 48 volts.

[0024] The enlarged areas (15, 16) enabling a tilting of the connection piece (1), thus ensuring geometric tolerance during the assembly of the connection system. The insert (7) in the example described, forms a rib (22) to ensure flexibility and facilitate the insertion of the collar (6) of the connecting part. The connecting part (1) has a shoulder (20) to limit the movement of the connection piece (1) during insertion in the printed circuit. The limbs (2, 3) each have a protuberance (32, 33) directed towards the interior of the slot (5) in order to locally reduce the width of the slot (5). The distal end of the slot (5) is flared through chamfers and/or spokes (24, 25) provided in the inner surface of the limbs respectively (2, 3).

[0025] The complementary part to be connected comprises a connecting plug (26) made up of a flat bronze or copper sheet, for example, with a pointed end (27). During the insertion of the connection piece (1) in the slot (5), the limbs are spread apart (2, 3) when the end (27) meets the protuberances (32, 33). The spacing is reflected in a slight transverse expansion of the connection piece (1) at the collar (6), thus reinforcing contact between the peripheral edge of the connection piece (1) at the level of its collar (6), and the edges (17, 18) of the insert shearing. The elasticity of the limbs (2, 3) makes it possible to control the bearing force of the collar (6) on the edge (11) of the insert (7) shearing.

[0026] In the example described in FIG. 1, the connection piece (1) has a second shoulder (29) which, together with the first shoulder (20), form the collar. The second shoulder (29) has a slightly higher portion than that of the shearing (11) of the insert (7). Its passage can however be forced, given the elasticity of the rib (22) provided on the sides of the insert (7) shearing and the flexibility of the connection piece (1).

[0027] The operation of this first example of embodiment is as follows:

[0028] The closed circuit is prepared together with its insert shearings (7). The inserts (7) are linked to conductor tracks (28) in the printed circuit through electrical connections (14).

[0029] The connection pieces (1) are then introduced into the insert (7) shearings by pressing them against the upper surface of the printed circuit or the insert. The flexibility of the inserts enables the forceful passage of the second shoulder (29) until the first shoulder (20) enters into contact with the upper surface of the insert (7).

[0030] The printed circuit equipped with the connection pieces is then pressed on the complementary equipment with connector plugs (26) directed towards the printed circuit. Any likely misalignment is possible because of the mobility of the connection piece (1), thus an alignment tolerance is allowed.

[0031] By pressing the equipment with plugs (26) against the printed circuit, the plugs (26) enter the matching slots (5) of the connection pieces, thus leading to the spread of the limbs (2, 3) and expansion of the connection piece (1) at its collar (6), and therefore the reinforcement of the mechanical and electrical contact between the collar (6) and the connection piece (1) as well as the insert (7).

Structure of a Motor with Such a System

[0032] FIG. 4 represents an example of an external rotor motor (40) using such a connection system. The stator comprises a coiled stator (41) assembled on a core (42). The coils are supplied by conductors ending in connector plugs (26) to be inserted in the connection pieces (1) mounted on the printed circuit board (10). The advantage of such a system is that it enables the industrial production of the lower part of the motor comprising the external rotor (40) and the coiled stator on the one hand, and the upper part comprising the electronic parts on the other hand, then their simple mechanical assembly which consists in pressing the two parts against each other, in order to ensure both the mechanical and electrical assembly.

[0033] The stator has a core (42) that ensures both the mechanical strength of the coil stator (41), as well as the evacuation of power dissipated in the said coil stator. In the case of an external rotor motor, the heat produced by the coil assembly (41) is difficult to evacuate since it is confined in the motor. The invention relates to a core (42) with a first section (42a) surrounded by a coil stator (41), extending through a second section (42b) with a greater diameter and in the shape of a truncated cone. The core (42) thus has a generally T-shaped section. The second section (42b) is in contact with the metal box (44). This architecture makes it possible to improve the heat transfer generated by the motor coils and the iron losses to evacuate it to the metal housing (44). The core (42) has an axial discharge (45) crossed by an axle (46) attached to the external rotor (40). It drives a magnet (47) set in a detection probe (48) attached to the said printed circuit placed in the extension of the core (42). The detection probe (48) is placed in the axis of the core (42). The discharge has a bearing (49) for guiding the tubular rotor axis.

[0034] The magnet (47) is placed in a cavity (52), with the walls of the said cavity ensuring shielding around the detection probe (48). FIG. 5 shows a bottom view of the motor. The rotor comprises a transverse face (51) with at least one through-light (50) to ensure airflow in the coil assembly (41). These through-lights (50) are configured to ensure the airflow during the rotor rotation and can be straight bore (as illustrated) or inclined bore (not shown), to enable forced circulation.

[0035] FIG. 3 presents an alternative embodiment of the connection piece (1) which advantageously has locking lugs (30, 31) to eventually avoid the outlet of the connection piece (1) during the insertion of electrical connector plugs.