METHOD FOR ASSEMBLING AN ELECTRONIC CONTROL UNIT INTENDED FOR INSTALLATION IN A VEHICLE
The assembly process for electronic control units in vehicles addresses the challenges of metallic particle generation, manufacturing complexity, and tooling costs by using a clamping mechanism within the metal housing and cover, ensuring secure fixation and reduced manufacturing burdens.
Patent Information
- Application Number
- FR2022008898
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2022-09-06
- Publication Date
- 2025-05-02
- Estimated Expiration
- 2042-09-06
AI Technical Summary
Existing assembly processes for electronic control units in vehicles face challenges such as the generation of harmful metallic particles, high manufacturing complexity due to strict shape and tolerance requirements, and increased tooling costs and quality issues related to riveting.
An assembly process that uses a metal housing with internal protuberances to securely hold a printed circuit card, and a metal cover with complementary protuberances to apply a clamping force, eliminating the need for rivets and simplifying the manufacturing and assembly processes.
This solution ensures effective mechanical fixation and electrical continuity of the printed circuit card, reduces manufacturing complexity and costs, and allows for a thinner metal housing design, thereby reducing weight and production expenses.
Smart Images
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Abstract
Description
Title of the invention: METHOD FOR ASSEMBLING AN ELECTRONIC CONTROL UNIT INTENDED TO BE INSTALLED IN A VEHICLE
[0001] The invention relates to a method of assembling an electronic control unit intended to be installed in a vehicle, in particular a motor vehicle. The electronic control unit comprises a housing made of metallic material, and is typically but not limited to an electronic control unit of an engine of the vehicle (or electronic control unit ECU, from the English "Electronic Control Unit").
[0002] Electronic control units for vehicles are known which comprise a metal housing, a printed circuit board and a metal cover intended to close the metal housing. The metal housing defines a housing intended to receive the printed circuit board, the latter being fixed within the metal housing. More specifically, it is known to carry out the fixing of the printed circuit board within the metal housing or the metal cover, by screwing or by riveting. For example, when the metal housing is made of cast aluminum, the printed circuit board can be screwed into the housing.However, such screw fastening can generate metal particles that are harmful to the on-board electronics, which therefore requires a very controlled screwing process or parts inspection during assembly of the unit (to eliminate particles), and requires a high quality standard on the casting of the aluminum housing.
[0003] In order to avoid these drawbacks, other electronic control units incorporate housings made of metal sheets. When the metal cover is made of metal sheets, it is then known to fix the printed circuit board within the metal cover by riveting (for example via an intermediate plate, fixed in the cover and itself made of metal sheets). A dome or a protrusion is typically formed by deformation of the metal sheet. The printed circuit board is then plugged onto such a dome or such a protrusion, then the dome or the protrusion is crushed using a suitable tool to form the rivet and thus hold and fix the printed circuit board within the metal cover. The metal cover / printed circuit board assembly is then assembled on the metal housing and fixed to the latter.However, such a solution of fixing the printed circuit board by rivets imposes strong constraints on the cover / housing assembly in terms of initial shapes and tolerances. This complicates the manufacturing of such metal covers and housings from metal sheets (which are generally manufactured via a lamination / forming process). In addition, such a . The rivet fastening solution also poses problems in terms of tool development (which results in significant costs), and is likely to lead to quality problems in the parts produced (material cracks, particularly in the areas where the protrusions are crushed, the latter having been formed by prior stretching and deformation of the material).
[0004] The aim of the invention is to overcome the drawbacks of the prior art by proposing a method for assembling an electronic control unit for a vehicle, which makes it possible to ensure effective fixing of the printed circuit board within the metal housing / cover assembly of the unit, while facilitating the manufacture of the metal housing and cover (in particular when the latter are made of metal sheets), and thus simplifying the assembly of the assembly.
[0005] To this end, the invention thus relates, in its broadest sense, to a method of assembling an electronic control unit intended to be installed in a vehicle, the electronic control unit comprising a metal housing, a printed circuit board, a metal cover intended to close the metal housing, and means for fixing the metal cover to the metal housing, the metal housing defining a housing intended to receive the printed circuit board, the metal housing being provided with an internal wall and a rim extending the internal wall towards the outside of the housing, the metal cover having an internal face and an external face and comprising over all or part of its periphery a bearing part on the rim of the metal housing,the inner wall of the metal housing being provided with at least one first protuberance intended to be in contact with a first face of the printed circuit board, the metal cover being provided on its inner face with at least one second protuberance intended to be in contact with a second face of the printed circuit board, opposite the first face, the support part of the metal cover being configured such that a space is formed between the support part and the edge of the metal housing when said at least one second protuberance of the metal cover is in contact with the second face of the printed circuit board, and the method comprising the following steps: , - placing the printed circuit board in the housing defined by the metal casing, the first face of the printed circuit board resting on said at least one first protuberance; - placing the metal cover on the metal casing, said at least one second protrusion of the metal cover resting on the second face of the printed circuit board; - pressure on the support part of the metal cover, so as to close the space between the support part of the metal cover and the edge of the metal housing and exerting a clamping force on the printed circuit board, the printed circuit board being clamped between the first and second protrusions; and - fixing the metal cover to the metal housing at the support part of the metal cover, via the fixing means, the printed circuit board being held by clamping between the first and second protrusions.
[0006] Thanks to the various steps of the method according to the invention, the printed circuit board is held effectively by clamping between the metal housing and the metal cover. Such a configuration thus makes it possible to ensure effective mechanical fixing of the printed circuit board within the metal housing, while guaranteeing electrical continuity between the three elements metal housing / printed circuit board / metal cover. In addition, such a configuration makes it possible to eliminate the step of the prior art consisting of riveting the printed circuit board to the metal cover (a step which then becomes unnecessary). This makes it easier to manufacture the metal housing / cover assembly (in particular when the latter are made of metal sheets), because the presence of rivets is no longer necessary, and consequently to simplify the assembly operations of the electronic control unit.The shape and tolerance constraints that weighed on the manufacture of the metal housing / cover assembly of the prior art are in fact relaxed. Finally, compared to a metal housing of the prior art, the thickness of the wall of the metal housing used in the method according to the invention can be advantageously reduced (typically by a reduction factor of the order of 20%), because the thickness imposed to form rivets is no longer necessary. This makes it possible to reduce the weight of the metal housing, and consequently to reduce production costs. The method according to the invention also makes it possible to simplify the tooling used on the production line to carry out the assembly, as well as to reduce the costs relating to this tooling.
[0007] According to a particular technical characteristic of the invention, the fixing means consist of crimping means provided on the support part of the metal cover, and the step of fixing the metal cover to the metal housing is a crimping step.
[0008] Preferably, the crimping means comprise at least one crimping tab, said at least one crimping tab being mechanically deformable at a deformation zone and configured to be foldable towards the metal housing when the support part of the metal cover rests on the rim of the metal housing.
[0009] According to a particular technical characteristic of the invention, the metal housing is further provided with a pin for centering and positioning the circuit card. printed, said pin protruding from the internal face of the metal housing, a notch or an orifice for receiving the pin is provided by cutting in the printed circuit board, and the step of placing the printed circuit board in the housing defined by the metal housing comprises a phase of inserting the pin of the metal housing into the notch or the orifice provided in the printed circuit board, for centering and positioning the printed circuit board with respect to the metal housing. This allows indexing, in the horizontal plane (which is also the extension plane of the metal cover), of the printed circuit board with respect to the metal housing.Such a phase of inserting the pin of the metal housing into the notch or hole provided in the printed circuit board is particularly advantageous when a change of workstation occurs during assembly, prior to fixing the cover on the housing, such a change of workstation involving a movement of the electronic control unit. Such a phase in fact makes it possible to maintain the printed circuit board in position in the horizontal plane during such a movement of the electronic control unit.
[0010] According to a particular technical characteristic of the invention, the metal housing is further provided with at least one third protuberance intended to guide the printed circuit card in translation, said at least one third protuberance projecting from an internal lateral face of the metal housing, and the step of placing the printed circuit card in the housing defined by the metal housing comprises a phase of inserting the printed circuit card into the housing and a phase of guiding the printed circuit card in translation, via said at least one third protuberance, during its insertion into the metal housing.This makes it easier to place the printed circuit board in the metal housing, by allowing pre-positioning and natural translational guidance of the board in the housing (such guidance can, for example, make it easier to insert the pin of the metal housing into the notch or hole provided in the printed circuit board, for centering and positioning the board in the horizontal plane).
[0011] According to a particular technical characteristic of the invention, the metal casing and / or the metal cover is made of metal sheets.
[0012] According to another particular technical characteristic of the invention, the electronic control unit is an electronic control unit of a vehicle engine.
[0013] The invention also relates to an electronic control unit intended to be installed in a vehicle, in particular a motor vehicle, the electronic control unit comprising a metal housing, a printed circuit board, a metal cover fixed to the metal housing and closing the metal cover, and means for fixing the metal cover to the metal housing, the metal housing metal defining a housing receiving the printed circuit board, the metal housing being provided with an internal wall and a rim extending the internal wall towards the outside of the housing, the metal cover having an internal face and an external face and comprising on all or part of its periphery a bearing part on the rim of the metal housing, the metal cover being fixed on the metal housing at the level of the bearing part, the internal wall of the housing being provided with at least a first protuberance in contact with a first face of the printed circuit board, the metal cover being provided on its internal face with at least a second protuberance in contact with a second face of the printed circuit board, opposite the first face, the printed circuit board being held by clamping between the first and second protuberances.
[0014] The invention also relates to a vehicle, in particular a motor vehicle, comprising an electronic control unit as described above.
[0015] Embodiments of the present invention will be described below, by way of non-limiting examples, with reference to the appended figures in which:
[0016] [Fig-1] is a top view of an internal face of the cover of a unit of electronic control for a vehicle, according to one embodiment of the invention;
[0017] [Fig.2] is a top view of an internal face of a metal housing of the electronic control unit, according to one embodiment of the invention;
[0018] [Fig.3] is a sectional view of the electronic control unit of Figures 1 and 2, taken along a section plane III-III;
[0019] [Fig.4] is a sectional view of the electronic control unit of Figures 1 and 2, taken along a section plane IV-IV;
[0020] [Fig.5] is an enlarged view showing a detail of the electronic control unit of [Fig.4];
[0021] [Fig.6] is a sectional view of the electronic control unit of Figures 1 and 2, taken along a VLVI section plane; and
[0022] [Fig.7] is a flowchart showing a method of assembling the electronic control unit of [Fig.l], according to the present invention.
[0023] In this document, unless otherwise indicated, the terms "horizontal", "vertical" or "transverse", "lower", "upper", "above", "below", "top", "bottom", "side" are defined with respect to the orientation of the electronic control unit assembled by the method according to the invention. In particular, in this application, the term "horizontal" designates an orientation parallel to the plane of extension of the printed circuit board installed within the electronic control unit, while the term "vertical" designates an orientation perpendicular to this plane.
[0024] Referring to [Fig.7] the present invention relates to a method of assembling an electronic control unit 2 according to the invention. The electronic control unit tronics 2 (shown in pre-assembled configuration in Figures 1 to 6) is intended to be installed in a vehicle (such a vehicle not being shown in the figures). The electronic control unit 2 is for example an electronic control unit of an engine of the vehicle (or electronic control unit ECU, from the English “Electronic Control Unit”).
[0025] The electronic control unit 2 comprises a metal housing 4, a printed circuit board 6, a metal cover 8 and means 9 for fixing the metal cover 8 to the metal housing 4. The metal housing 4 defines a housing 10 receiving the printed circuit board 6. As illustrated in FIGS. 2 to 6, the metal housing 4 is provided with an internal wall 12 and a rim 14 extending the internal wall 12 towards the outside of the housing 10 (the internal wall 12 delimiting the housing 10). The metal housing 4 has for example a substantially parallelepiped shape. The rim 14 (which extends in a horizontal plane) has for example three orthogonal sides and forms a sort of “U” when the metal housing 4 has a substantially parallelepiped shape. The internal wall 12 of the metal housing 4 is provided with at least one protrusion 15 intended to be in contact with a first face 17 of the printed circuit board 6.In the particular embodiment illustrated in Figures 1 to 6, the inner wall 12 is provided with three such protrusions 15. Preferably, as illustrated in Figures 2, 3, 4 and 6, the inner wall 12 forms a bottom 16 and an intermediate rim 18 (the intermediate rim 18 extending into the housing 10, above the bottom 16, and having for example three orthogonal sides and forming a sort of “U” when the metal housing 4 has a substantially parallelepiped shape). The intermediate rim 18 extends in a horizontal plane. Each of the protrusions 15 projects vertically upwards from the intermediate rim 18 of the inner wall 12, and extends into the housing 10. Each of the protrusions 15 is for example formed by punching in the intermediate rim 18 of the inner wall 12.
[0026] Preferably, as illustrated in Figures 3 and 6, the metal housing 4 further comprises a pin 20 for centering and positioning the printed circuit board 6. The pin 20 projects vertically upwards from the intermediate edge 18 of the internal wall 12, and extends into the housing 10. More preferably, the metal housing 4 further comprises at least one protrusion 19 for guiding the printed circuit board 6 in translation. In the particular embodiment illustrated in [Fig. 2], the metal housing 4 comprises three such protrusions 19. Each protrusion 19 projects horizontally from a respective internal lateral face 21A, 21B, 21C of the metal housing 4. More preferably, the edge 14 of the metal housing 4 is provided with several eyelets 36 for fixing the electronic control unit 2 within the vehicle, in this case four eyelets fixing 36 in the particular embodiment illustrated in Figures 2 to 6. Each fixing eyelet 36 is for example configured to allow the passage of a screw (not shown). Preferably, the metal housing 4 is made of metal sheets. The wall of the metal housing 4 has for example a thickness substantially equal to 1.2 mm (compared to a wall thickness of at least 1.5 mm for the metal housings of the prior art for which the fixing of the printed circuit board within the metal housing is carried out by riveting).
[0027] The printed circuit board 6 extends in a horizontal plane. Preferably, as illustrated in Figures 3 and 6, the printed circuit board 6 is provided with a notch 22 (or in a variant not shown, an orifice) for receiving the pin 20. The notch 22 (or the orifice) for receiving the pin 20 is formed by cutting into the printed circuit board 6. As will be detailed later, the printed circuit board 6 is held by clamping between the metal housing 4 and the metal cover 8 when the metal cover 8 is fixed to the metal housing 4.
[0028] The metal cover 8 is intended to close the metal housing 4 and has an external face 24 and an internal face 26 (the internal face 26 extending opposite the housing 10 when the metal cover 8 is arranged on the metal housing 4). The metal cover 8 has on all or part of its periphery a part 28 for bearing on the rim 14 of the metal housing 4. In the particular embodiment illustrated in FIGS. 1 to 6, the metal cover 8 has a substantially rectangular shape and the bearing part 28 of the metal cover 8 is located on a part of its periphery, in this case on the two short sides and on one of the long sides of the rectangle formed by the cover 8.As illustrated in Figures 4 to 6, the bearing portion 28 is configured such that a gap 29 is formed between the bearing portion 28 and the flange 14 when the bearing portion 28 rests on the flange 14 (and the metal cover 8 is not yet fixed to the metal housing 4). The bearing portion 28 is configured to press against the flange 14, in contact with the latter, when the metal cover 8 is fixed to the metal housing 4 (as will be described later).
[0029] The metal cover 8 is provided on its inner face 26 with at least one protrusion 30 intended to be in contact with a second face 32 of the printed circuit board 6, opposite the first face 17. In the particular embodiment illustrated in FIGS. 1 to 6, the inner face 26 of the metal cover 8 is provided with three such protrusions 30. Each of the protrusions 30 projects vertically downwards from the inner face 26 of the metal cover (and extends into the housing 10 when the metal cover 8 is arranged on the metal housing 4). Each of the protrusions 30 is for example formed by punching in the wall of the metal cover 8. Preferably, the metal cover 8 is made of metal sheets.
[0030] The means 9 for fixing the metal cover 8 to the metal housing 4 are preferably provided on the support part 28 of the metal cover 8. The fixing means 9 are for example crimping means which make it possible to hold the printed circuit board 6 tight between the protrusions 15 of the metal housing 4 and the protrusions 30 of the metal cover 8. More precisely, in the particular embodiment illustrated in FIGS. 1 to 6, the fixing means 9 comprise nine crimping tabs 9A, 9B, 9C. Three crimping tabs 9A are provided on the support portion 28, at one of the short sides of the rectangle formed by the cover 8. Three other crimping tabs 9B are provided on the support portion 28, at the other short side of the rectangle formed by the cover 8. Three other crimping tabs 9C are provided on the support portion 28, at one of the long sides of the rectangle formed by the cover 8.As illustrated in Figures 1 and 3 to 5, each crimping tab 9A, 9B, 9C initially extends in a vertical plane and is mechanically deformable at a deformation zone 34 (such a deformation zone 34 being visible in [Fig. 5]). Each crimping tab 9A, 9B, 9C is configured to be foldable towards the metal housing 4, around the rim 14 of the metal housing 4, and thus to form a folding angle at the deformation zone 34, each crimping tab 9A, 9B, 9C having a final “C” shape when folded towards the housing 4 (such a final “C” shape not being shown in the figures). After folding (the folding not being illustrated in the figures), each crimping tab 9A, 9B, 9C then extends in a substantially horizontal plane, outside the housing 10, and holds by crimping the edge 14 of the metal casing 4.The cover 8 is then firmly fixed on the housing 4. The printed circuit board 6 is held by clamping between the protrusions 15 of the metal housing 4 and the protrusions 30 of the metal cover 8. In a variant not shown, the fixing means 9 may consist of screws, rivets, gluing means or any other known fixing means intended to fix two parts in contact.
[0031] Preferably, the metal cover 8 is provided on its support portion 28 with several eyelets 38 for fixing the electronic control unit 2 within the vehicle, in this case four fixing eyelets 38 in the particular embodiment illustrated in FIGS. 1 and 3 to 6. Each fixing eyelet 38 is for example configured to allow the passage of a screw (not shown), and is positioned on the cover 8 at a location corresponding to the location on the housing 4 of one of the fixing eyelets 36. Four pairs of eyelets 36, 38 are thus formed when the cover 8 is fixed on the housing 4, the two eyelets 36, 38 of the same pair being arranged opposite each other to allow the passage of the screw corresponding.
[0032] As illustrated in [Fig.7], the method for assembling the electronic control unit 2 comprises a first step 40 during which an operator or a robot places the printed circuit board 6 in the housing 10 defined by the metal housing 4. Preferably, the first step 40 of the method comprises a first phase 42, a second phase 44 and a third phase 46. The first phase 42 consists of inserting the printed circuit board 6 into the housing 10. The second phase 44 consists of guiding the printed circuit board 6 in translation during its insertion into the metal housing 4, via each of the protrusions 19 of the metal housing 4. This second phase 44 makes it possible to bring the notch 22 (or the orifice) formed in the printed circuit board 6 opposite the pin 20 provided on the metal housing 4.The third phase 46 consists of inserting the pin 20 into the notch 22 (or the orifice), for centering and positioning the printed circuit board 6 with respect to the metal housing 4. At the end of this first step 40, the first face 17 of the printed circuit board 6 rests on each of the protuberances 15 of the metal housing 4.
[0033] The method comprises a following step 48, illustrated in FIGS. 1 to 6, during which an operator or a robot places the metal cover 8 on the metal casing 4. The placing of the metal cover 8 on the metal casing 4 is carried out in such a way that the internal face 26 of the cover 8 carrying the protrusions 30 extends opposite the housing 10 (the protrusions 30 extending into the housing 10). At the end of this step 48, the protrusions 30 of the cover 8 are in contact with the second face 32 of the printed circuit board 6. A space 29 is formed between the bearing part 28 and the rim 14.
[0034] The method comprises a following step 50 during which a press presses by vertical pressure on the support part 28 of the metal cover 8, so as to close the space 29 between the support part 28 and the rim 14. This step 50 of pressing on the support part 28 of the metal cover 8 makes it possible to fill the space 29 between the support part 28 and the rim 14, and to simultaneously exert a clamping force on the printed circuit board 6, the printed circuit board 6 then being clamped between the protrusions 15 of the metal housing 4 and the protrusions 30 of the metal cover 8.
[0035] The method comprises a following step 52 during which a robotic tool fixes the metal cover 8 on the metal housing 4 at the level of the support part 28 of the metal cover 8, via the fixing means 9. More precisely, in the particular embodiment of FIGS. 1 to 6, the robotic tool folds each of the crimping tabs 9A, 9B, 9C towards the metal housing 4. After folding, each of the crimping tabs 9A, 9B, 9C extends in a plane substantially horizontal. rizontal around the rim 14 of the housing 4, outside the housing 10, and the cover 8 is firmly fixed on the housing 4. The printed circuit board 6 is then held by clamping between the protrusions 15 of the metal housing 4 and the protrusions 30 of the metal cover 8.
[0036] The method of assembling the electronic control unit 2 according to the invention makes it possible to ensure effective fixing of the printed circuit board 6, by ensuring electrical continuity, within the metal casing 4 of the unit 2, while facilitating the manufacture of the metal casing 4 and the cover 8 (in particular when the latter is made of metal sheets), and by simplifying the assembly of the whole.
Claims
Claims
1. Method for assembling an electronic control unit (2) intended to be installed in a vehicle, the electronic control unit (2) comprising a metal housing (4), a printed circuit board (6), a metal cover (8) intended to close the metal housing (4), and means (9) for fixing the metal cover (8) to the metal housing (4), the metal housing (4) defining a housing (10) intended to receive the printed circuit board (6), the metal housing (4) being provided with an internal wall (12) and a rim (14) extending the internal wall (12) towards the outside of the housing (10), the metal cover (8) having an internal face (26) and an external face (24) and comprising on all or part of its periphery a portion (28) for bearing on the rim (14) of the metal housing (4),the inner wall (12) of the metal housing (4) being provided with at least one first protuberance (15) intended to be in contact with a first face (17) of the printed circuit board (6), the metal cover (8) being provided on its inner face (26) with at least one second protuberance (30) intended to be in contact with a second face (32) of the printed circuit board (6), opposite the first face (17), the bearing portion (28) of the metal cover (8) being configured such that a space (29) is formed between the bearing portion (28) and the rim (14) of the metal housing (4) when said at least one second protuberance (30) of the metal cover (8) is in contact with the second face (32) of the printed circuit board (6), characterized in that the method comprises the following steps:, - a placement (40) of the printed circuit board (6) in the housing (10) defined by the metal casing (4), the first face (17) of the printed circuit board (6) resting on said at least one first protuberance (15); - a placement (48) of the metal cover (8) on the metal casing (4), said at least one second protuberance (30) of the metal cover (8) resting on the second face (32) of the printed circuit board (6); - a support (50) by pressure on the support part (28) of the metal cover (8), so as to close the space (29) between the support part (28) of the metal cover (8) and the rim (14) of the metal housing (4) and to exert a clamping force on the printed circuit board (6), the printed circuit board (6) being clamped between the first and second protrusions (15, 30); and - a fixing (52) of the metal cover (8) on the metal housing (4) at the support part (28) of the metal cover (8), via the fixing means (9), the printed circuit board (6) being held by clamping between the first and second protrusions (15, 30) in that the fixing means (9) consist of crimping means provided on the support part (28) of the metal cover (8), and in that the step (52) of fixing the metal cover (8) on the metal housing (4) is a crimping step.
2. Method according to claim 1, characterized in that the crimping means (9) comprise at least one crimping tab (9A, 9B, 9C), said at least one crimping tab (9A, 9B, 9C) being mechanically deformable at a deformation zone (34) and configured to be foldable towards the metal housing (4) when the support part (28) of the metal cover (8) rests on the rim (14) of the metal housing (4).
3. Method according to any one of claims 1 or 2, characterized in that the metal housing (4) is further provided with a pin (20) for centering and positioning the printed circuit board (6), said pin (20) projecting from the internal face (12) of the metal housing (4), in that a notch (22) or an orifice for receiving the pin (20) is formed by cutting in the printed circuit board (6), and in that the step (40) of placing the printed circuit board (6) in the housing (10) defined by the metal housing (4) comprises a phase (46) of inserting the pin (20) of the metal housing (4) into the notch (22) or the orifice formed in the printed circuit board (6), for centering and positioning the printed circuit board (6) with respect to the metal housing (4).
4. Method according to any one of claims 1 to 3, characterized in that the metal housing (4) is further provided with at least one third protuberance (19) intended to guide the printed circuit board (6) in translation, said at least one third protuberance (19) projecting from an internal lateral face (21A, 21B, 21C) of the housing metallic (4), and in that the step (40) of placing the printed circuit card (6) in the housing (10) defined by the metallic housing (4) comprises a phase (42) of inserting the printed circuit card (6) into the housing (10) and a phase (44) of guiding in translation, via said at least one third protuberance (19), the printed circuit card (6) during its insertion into the metallic housing (4).