CASE ASSEMBLED BY DISCONTINUOUS LASER WELDING

Abstract

A housing (B1) comprising a base (2) and a lid (4) made of a heat-fusible material, the base (2) having an open end surrounded at least partially by a flange (10) and the lid (4) having an open end surrounded at least partially by a flange (18), the two flanges (10, 18) being in contact with each other. The two flanges (10, 18) are joined by a laser weld that joins only a portion of the flanges, the weld being configured to ensure the desired assembly strength. The flanges (10, 18) have sufficient width (L1, L2) so that the weld width ensures the desired assembly strength. [Fig. 3]

Description

Title of the invention: Housing assembled by discontinuous laser welding. Technical field and prior art.

[0001] The present invention relates to a housing assembled by discontinuous laser welding and to a method of manufacturing such a housing.

[0002] In the field of braking, electromechanical actuators are increasingly used, particularly for actuation of the parking brake.

[0003] For example, a drum brake includes a hydraulic actuator for service braking, and an electromechanical actuator for operating the parking brake.

[0004] An electromechanical actuator comprises an electric motor, a reducer and a mechanical part transforming the rotational movement of the geared motor into a movement of segment separation.

[0005] The electric motor is for example fixed on the outer face of the drum brake plate.

[0006] To protect the motor and allow for its mounting, the motor is housed in a plastic casing comprising a base and a cover. The cover includes a connector for connecting the motor to a power supply and a control unit.

[0007] Generally, the lid and the base are joined together by welding, preferably using a laser beam. The laser welding assembly process is very advantageous because it provides localized heating, which limits the risk of damage to the other parts.

[0008] The lid and the base each have a flange at their open end. One end of the motor is housed in the base, and the other end is covered by the lid, with the two flanges in contact with each other. Laser welding is then performed between the two flanges. The lid material is transparent to the wavelength of the laser beam, while the base material is absorbent at this wavelength. The laser beam passes through the flange of the lid and heats the flange of the base, which fuses the contact areas of the two flanges. The path of the laser beam is such that it closes upon itself, forming a continuous weld between the two flanges. The resulting assembly has a cylindrical shape.

[0009] In one configuration, the connector extends radially. It is then located in the path of the laser beam. However, the connector is too thick for the laser beam to pass through without being damaged. Therefore, the weld The weld cannot be performed in the flange sections at the connector. The weld then fails to close on itself and has two points of discontinuity. The laser welded assembly is therefore weakened. Description of the invention

[0010] It is therefore an object of the present invention to provide a plastic material housing comprising a base and a lid having a robust assembly.

[0011] The stated purpose above is achieved by a housing comprising a base and a lid made of hot-melt material, the base having an open end surrounded at least in part by a flange and the lid having an open end surrounded at least in part by a flange, the two flanges being in contact with each other, in which the two flanges are joined by a laser weld which joins only part of the flanges, the weld being configured to ensure the desired robustness of the assembly.

[0012] For example, the cover includes an element extending radially outwards and preventing a closed weld from being made on all the flanges.

[0013] In one embodiment, the laser weld bead offers sufficient width, which makes it possible to compensate for the absence of a weld closing on itself.

[0014] In another embodiment, the weld path forms a continuous loop without completely surrounding the axis of the housing, so that the weld does not have a discontinuity or abrupt interruption which tends to weaken the assembly.

[0015] Very advantageously, the flanges are shaped to provide areas allowing the laser beam to make a half turn while remaining in contact with the flanges, which makes it possible to generate a robust weld bead.

[0016] Preferably, the housing and the cover define between them a housing for tightening a seal to make a watertight assembly.

[0017] In other words, the inventors thought of adapting the laser welding assembly so that it produces a sufficiently robust assembly, whereas other means of assembly could have been considered.

[0018] Thanks to the invention, the architecture of the case, which has a high compactness, is very little impacted.

[0019] The present invention relates to a housing comprising a base and a lid made of a heat-fusible material, the base having an open end surrounded at least partially by a flange and the lid having an open end surrounded at least partially by a flange, the two flanges being in contact with each other, in which the two flanges are joined by laser welding which assembles only part of the flanges, the welding being configured to ensure the desired assembly robustness.

[0020] In one embodiment, the flanges have sufficient widths so that the weld width ensures the desired assembly robustness.

[0021] Preferably, the minimum width of the flanges is 2.5 mm.

[0022] Preferably, the weld is configured to offer a tensile strength greater than 500 N and / or a vibration strength greater than 150g.

[0023] In another embodiment, each flange has a first angular end and a second angular end, the first two angular ends being in contact and the second two angular ends being in contact, at least the first angular end of each flange having a width in the radial direction sufficient for the laser weld formed during assembly to have in the first ends the shape of a loop connecting a forward path of a laser beam and a return path of the laser beam.

[0024] Most advantageously, the second angular ends of each flange have a width in the radial direction sufficient for the laser weld formed during assembly to have in the second angular ends the shape of a loop connecting a forward path of the laser beam and a return path of the laser beam.

[0025] According to an additional feature, one of the flanges has a groove configured to receive a portion of the other flange, and in which the welded assembly is located at the bottom of the groove. Advantageously, one of the flanges is internally edged by a groove and the other flange is internally edged by a sleeve, the sleeve penetrating the groove, and in which sealing means are clamped between a bottom of the groove and the sleeve.

[0026] In an advantageous example, the base and lid are made of glass fiber reinforced polybutylene terephthalate, for example 30% (PBT GF 30).

[0027] Another object of the present invention is an electric actuator comprising a housing according to the invention and a geared motor housed in the housing.

[0028] In one embodiment, the cover includes an element extending radially outwards, housing an electrical connector for the geared motor.

[0029] Another object of the present invention is a method for manufacturing a casing according to the invention, comprising: a) Supply of a base and a lid according to the invention, b) Bringing the flanges into contact so that said first angular ends are in contact with each other, c) Activation of the laser beam so that it targets one of the flanges, d) Movement of the beam in a first direction towards said first ex- angular openings, e) After reaching said extremities, movement of the laser beam in a second direction opposite to the first direction, the change of direction of movement being obtained by making a loop-shaped reversal at said first extremities.

[0030] In step b), a base and a cover according to the invention are provided, and in step e), the laser beam changes direction in the second ends of each flange by performing a loop-shaped reversal at said second ends.

[0031] In an advantageous example, the laser beam makes several paths between the first and second ends, the paths being at least partly coincident or at least partly distinct.

[0032] The manufacturing process may include a step between step a) and step b) of installing a geared motor in the bottom. BRIEF DESCRIPTION OF THE FIGURES

[0033] The following description will be better understood with the aid of the attached drawings, in which:

[0034] [Fig. 1] is a perspective view of an example of a housing according to the invention,

[0035] [Fig.2] is a view of one end of the housing of the [Fig.1],

[0036] [Fig.3] is a partial longitudinal sectional view of a first assembly method of the case of the [Fig.1],

[0037] [Fig.4] is a side view of an alternative embodiment of the housing of [Fig.1],

[0038] [Fig.5] is a top view of a housing according to a second assembly method,

[0039] [Fig.6] is a view from below of the cover of the housing of [Fig.5],

[0040] [Fig.7] is a bottom view of a housing cover according to a variant of the assembly method of [Fig.5],

[0041] [Fig.8] is a bottom view of a lid according to another embodiment of the second assembly method,

[0042] [Fig.9] is a bottom view of a lid according to another embodiment of the second assembly method. DETAILED DESCRIPTION OF IMPLEMENTATION METHODS

[0043] The invention will be described in detail in the context of an electric actuator housing for a brake. However, it will be understood that the invention applies to the assembly of any housing made of a hot-melt material.

[0044] Figures 1 and 2 show an example of an embodiment of a housing according to the invention. Housing B1 is configured to house an electric motor (not visible). Housing B has a rotary shape with axis X. It has a base 2 and a lid 4. The base comprises a body 6 having an open longitudinal end 8 surrounded by a flange 10.

[0045] The cover 4 includes a body 12 having an open longitudinal end 14. The body 12 also includes a radially projecting element 16 forming a connector for connecting the electric motor to a power source and a control unit (not shown).

[0046] The body 12 also includes a flange 18 partially surrounding the open end 14. In particular, the flange 18 is interrupted at the protruding element 16. Thus, an angular area a around the open end 14 does not have a flange. The angle a is less than 180°.

[0047] A housing in which the flange of the cover is not interrupted does not fall outside the scope of the present invention.

[0048] The fact that the flange 10 of the base is continuous and completely surrounds the body has the advantage of not having to orient the base relative to the lid. However, alternatively, the flange of the base is interrupted at an angular sector which overlaps the angular sector a.

[0049] The angular sector a is such that a larger portion of the flange 10 will be melted by laser irradiation to avoid any creation of a mechanical stop between the flange 10 and 18. The portion of the flange 10 melted is an angular sector of (360 - a + safety margin of a few degrees).

[0050] As can be seen in [Fig.2], the flange 18 has two free ends 18.1, 18.2 which potentially form areas of weakening.

[0051] Figure 3 shows a partial longitudinal cross-sectional view of a mode assembly of the casing shown in figures 1 and 2.

[0052] In this example, the flange 10 has an annular assembly face 20 and an annular groove 22 located radially inside the assembly face 20, and concentric with the assembly face.

[0053] The flange 18 has an annular assembly face 24 located in the bottom of an annular groove 26 and an annular sleeve 28 extending longitudinally and located radially inside the groove 26 and penetrating the groove 22.

[0054] The assembly face 24 does not close around the X axis due to the missing annular zone a. The assembly face 24 has the shape of a circular arc extending over an angle of 360°- a.

[0055] The cover material and / or the housing material are hot-melt.

[0056] At least the material of the flange 18 of the cover is transparent along the length of the wave of the laser beam used for welding, so when the laser beam passes, the flange 10 at the bottom is heated, causing local melting of the flange 10 and the flange 18.

[0057] Preferably, the same material is used for the manufacture of the lid and the housing. This is preferably a polymer material.

[0058] According to one example, the lid and the casing are made of poly(butylene terephthalate)(PBT)

[0059] According to another example, the lid and the case are made of polyamide 6 (PA6).

[0060] According to another example, the lid and the case are made of polypropylene.

[0061] According to another preferred example, the lid and the casing are made of polybutylene te- glass fiber reinforced phthalate, for example at 30% (PBT GF 30).

[0062] The weld extends over an arc of a circle extending over an angle of approximately 360°- a between the ends 24.1, 24.2 of the assembly surface 24.

[0063] The groove 22 is continuous and closes around the X axis, it then advantageously allows sealing means 30 to be housed between the cover and the bottom.

[0064] For example, the sealing means 30 comprise a silicone seal or a liquid seal, also known as a FIPG (Form In Place Gasket), which is polymerizable under ambient conditions or temperature. The seal is placed in a liquid state in the groove, the annular sleeve 28 is positioned to allow the seal to flow, and then the seal is polymerized. Alternatively, the sealing means comprise an O-ring type seal or a CIPG (Cured In Place Gasket) compressed between the bottom of the groove 22 and the free end of the annular sleeve 28.

[0065] In this embodiment, the assembly faces 20, 24 have a width considered in a radial direction sufficient to ensure a bond between the lid and the base, despite the fact that the weld has a discontinuity. 4.

[0066] Preferably, the weld width is such that it offers a tensile strength greater than 500 N.

[0067] Preferably, the weld width is such that it offers resistance to vibration greater than 150g.

[0068] The assembly face 20 advantageously has a width L1 of less than 3 mm, and preferably the width L1 is on the order of 2.5 mm.

[0069] In a preferred example, the assembly face 24 has a width L2 of approximately 3.7 mm. The dimensions of the assembly faces depend in particular on the weld depth.

[0070] Thus, it is possible to produce a weld of significant width, on the order of 2.5 mm. In comparison, a laser weld in the prior art is on the order of 1 mm to 1.5 mm.

[0071] Preferably, the diameter of the housing is such that the total length of the weld bead is less than 300 mm

[0072] In [Fig.4], a variant embodiment of the housing of [Fig.1] can be seen in in which the 10' and 18' flanges completely surround the open ends of the lid and bottom.

[0073] The manufacturing process for the actuator in [Fig. 1] is, for example, as follows: - Supply of base 2 and lid 4. - Mounting the geared motor in the bottom. - The lid is placed on the bottom so that their flanges 10, 18 are in contact with each other. - The laser beam is positioned on the side of the cover and aims at the first end 24.1 of the assembly surface 24. The laser is moved along the flange 18 towards the second end 24.2 and to the end 24.2. In one example, the laser beam makes a single pass from end 24.1 to end 24.2 and in another example, the laser beam makes at least one pass and a return in order to achieve the desired weld width.

[0074] Figure 5 shows a top view of another example of a B2 housing according to the invention. Figure 6 shows a bottom view of the cover of the housing of Figure 5.

[0075] The cover 104 has a flange 118 partially surrounding the body of the cover and having two angular ends 118.1, 118.2 shaped so as to allow the laser beam to reverse direction when it reaches either of the angular ends, thus avoiding generating a discontinuity in the weld which can be detrimental to the robustness of the assembly.

[0076] Preferably, the weld according to this configuration is such that it offers a tensile strength greater than 500 N.

[0077] Preferably, the weld according to this configuration is such that it offers resistance to vibration greater than 150g.

[0078] The ends 118.1 and 118.2 each have substantially the shape of an ear.

[0079] The flange 118 has a groove 126, the bottom of which forms the assembly face 124 that defines the path of the laser beam. The groove 126 has, at both ends 118.1 and 118.2, a loop that allows the laser beam to perform a closed weld. The loops have an elongated shape. This design has the advantage of offering a smaller radial footprint.

[0080] The path of the laser beam in the groove 126 is symbolized by the dashed line.

[0081] The base includes a flange comprising an assembly face with a shape complementary to the assembly face 124.

[0082] In one variant, the flange 218 of the cover and / or the flange of the bottom are flat and do not physically delimit the path of the laser, as shown schematically in [Fig.7].

[0083] In [Fig.8], a variant embodiment of a lid can be seen in which the flange 318 has loop ends 318.1, 118.2 of the assembly face 324 having a circular shape.

[0084] Alternatively, the flange of the cover has a single end allowing the laser to perform a reversal without generating a discontinuity, which has the effect of improving the robustness of the assembly compared to an assembly comprising two discontinuities.

[0085] In the example described, and advantageously, the forward path of the laser beam and the return path are partly common. Alternatively, the forward and return paths are completely separate (represented by a dashed line) as can be seen on flange 418 shown in [Fig. 9].

[0086] This second assembly method has the advantage of not requiring a weld larger than that of the prior art. However, a housing according to the second assembly method with a weld larger than that of the prior art, for example on the order of 2.5 mm, does not fall outside the scope of this application.

[0087] An example of a manufacturing process for the housing according to the second assembly method will now be described.

[0088] The process comprises: - Supply of base 102 and lid 104. - Mounting of the geared motor in the bottom 102. - Placement of the lid on the bottom so that their flanges 110, 118 are in contact with each other. The laser beam is positioned on the side of the cover and aimed at the first ear 118.1. It then moves along the flange towards the second ear 118.2. When the laser beam reaches the second ear 118.2, it makes a U-turn, forming a loop, and returns towards the first ear 118.1, until it reaches the starting point of the weld. The laser beam can make several passes between the two ears. The resulting weld is seamless.

[0089] The invention makes it possible to preserve the assembly by means of a laser welding which ensures localized heating, which has the effect of putting less stress on the components during the welding step.

[0090] In the example shown, the housing has a substantially circular cross-section. It will be understood that the invention applies to housings of any cross-section, for example elliptical, polygonal, or rectangular.

[0091] Furthermore, in the above description, the cover includes a radial extension which prevents welding around the entire perimeter of the flanges. However, it will be understood that a cover with a different shape does not fall outside the scope of this application.

[0092] The present invention applies to any type of housing made of plastic material assembled by laser welding, more particularly to housings containing electrical actuators, and even more particularly brake actuators.

Claims

Demands

1. A housing comprising a base and a lid made of a heat-fusible material, the base (2) having an open end surrounded at least partially by a flange (10, 110) and the lid (4) having an open end surrounded at least partially by a flange (18, 118), the two flanges (10, 110, 18, 118) being in contact with each other, wherein the two flanges (10, 110, 18, 118) are joined by a laser weld that joins only a portion of the flanges (10, 110, 18, 118), the weld being configured to ensure the desired assembly strength, wherein the flanges (10, 18) have widths (L2, L3) sufficient for the weld width to ensure the desired assembly strength, and wherein the weld extends over a 360° arc such that the The weld has a discontinuity

2. Housing according to claim 1, wherein the minimum width of the flanges is 2.5 mm.

3. Housing according to claim 1 or 2, wherein the weld is configured to provide a tensile strength greater than 500 N and / or a vibration strength greater than 150g.

4. Housing comprising a base and a lid made of a hot-melt material, the base (2) having an open end surrounded at least partially by a flange (10, 110) and the lid (4) having an open end surrounded at least partially by a flange (18, 118), the two flanges (10, 110, 18, 118) being in contact with each other, wherein the two flanges (10, 110, 18, 118) are joined by a laser weld that joins only a portion of the flanges (10, 110, 18, 118), the weld being configured to ensure the desired assembly strength, wherein each flange (110, 118) has a first angled end and a second angled end, the first two angled ends being in contact and the second two angled ends being in contact, at least the first angled end of each flange (110,118) having a width in the radial direction sufficient so that the laser weld formed during assembly has, at the first ends, the shape of a loop connecting a forward path of a laser beam and a return path of the laser beam.

5. Housing according to claim 4, wherein the second angular ends of each flange (110, 118) have a width in the sufficient radial direction so that the laser weld formed during assembly has in the second angular ends the shape of a loop connecting a forward path of the laser beam and a return path of the laser beam.

6. Housing according to any one of the preceding claims, wherein one (18) of the flanges has a groove (26) configured to receive a portion of the other flange (10), and wherein the welded assembly is in the bottom of the groove (26).

7. Housing according to any one of the preceding claims, wherein one (10) of the flanges is internally edged by a groove (22) and the other of the flanges is internally edged by a sleeve (28), the sleeve (28) penetrating into the groove (22), and in which sealing means (30) are clamped between a bottom of the groove (22) and the sleeve (28).

8. Housing according to any one of the preceding claims, wherein the base and lid are made of glass fiber reinforced polybutylene terephthalate, for example 30% (PBT GF 30).

9. Electric actuator comprising a housing according to one of the preceding claims and a geared motor housed in the housing.

10. Electric actuator according to the preceding claim, in which the cover comprises an element extending radially outwards, housing an electrical connector for the geared motor.

11. A method for manufacturing a housing according to claim 4, comprising a) Providing a base and a lid, b) Bringing the flanges into contact so that said first angular ends are in contact with each other, c) Activating the laser beam so that it targets one of the flanges, d) Moving the beam in a first direction towards said first angular ends, e) After reaching said ends, moving the laser beam in a second direction opposite to the first direction, the change in direction of movement being obtained by making a loop-shaped reversal at said first ends.

12. A method for manufacturing a housing according to claim 5, comprising a) Providing a base and a lid, b) Bringing the flanges into contact such that said first angular ends are in contact with each other, c) Activating the laser beam so that it targets one of the flanges, d) Displacement of the beam in a first direction towards said first angular extremities, e) After reaching said first extremities, displacement of the laser beam in a second direction opposite to the first direction, the change of direction of displacement being obtained by making a loop-shaped reversal at said first extremities, and the laser beam changing direction in the second extremities of each flange by making a loop-shaped reversal at said second extremities.

13. A manufacturing method according to the preceding claim, wherein the laser beam makes several paths between the first and second ends, the paths being at least partly coincident or at least partly distinct.

14. A manufacturing method according to any one of claims 11 to 13, comprising a step between step a) and step b) of installing a geared motor in the bottom.

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