Manufacturing process for a sensor for an automotive vehicle
The described manufacturing process addresses the challenge of sensor sealing by using a mold configuration and sealing gel to create a robust, temperature-resistant seal around connection pins, enhancing the sensor's reliability against liquid ingress.
Patent Information
- Application Number
- FR2023001563
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2023-02-21
- Publication Date
- 2025-02-07
- Estimated Expiration
- 2043-02-21
AI Technical Summary
Existing sensor manufacturing processes for motor vehicles face challenges in ensuring tightness, particularly in sealing against liquids, due to thermomechanical property differences between metal pins and epoxy materials, leading to potential liquid infiltration and damage to the integrated circuit and measurement cells.
A manufacturing process involving a mold configuration to form a waterproofing case with a body and hatch, filled with a sealing gel, and reinforced by injection molding to create a robust seal around connection pins, using wedges and grooves to secure the hatch in place, eliminating the need for complex receptacles and frost application.
The process enhances the sensor's sealing capability, reducing the risk of liquid ingress and potential damage by utilizing a sealing gel and injection molding techniques to create a durable, temperature-resistant seal, thereby improving the sensor's reliability.
Smart Images
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Abstract
Description
Title of the invention: Method for manufacturing a sensor for an automotive vehicle technical field
[0001] The present invention relates to the field of sensors for motor vehicles and more particularly to a sensor and a method for manufacturing such a sensor. The invention aims in particular to improve the sealing of existing sensors. Prior art
[0002] In a known manner, a motor vehicle includes measuring sensors which allow, for example, the measurement of the rotational speed or angular position of a drive shaft such as a crankshaft or a camshaft to be measured, or the detection of the rotational speed of a gearbox.
[0003] In a known manner, these sensors operate in conjunction with a target fixed to the shaft whose parameter is to be measured. The target is, for example, in the form of a toothed wheel whose teeth vary an electromagnetic field generated by a magnet mounted in the sensor. The variations in the magnetic field are detected by sensitive elements, called measuring cells, of the sensor.
[0004] According to a known manufacturing process, the sensor is manufactured in several stages. First, an integrated circuit is overmolded with a polyepoxy material, commonly called "epoxy," onto a metal connection grid having pins. The assembly is then positioned in a mold, or in a pre-molded sub-assembly, and a magnet is optionally positioned or overmolded relative to the integrated circuit. The assembly is then assembled, and a final overmolding is applied, leaving only the pins protruding to seal the sensor while also forming an electrical connector for the sensor to the vehicle and a sensor mounting element, for example, a retaining ring.
[0005] In some cases, the sensor may be in contact with a liquid, for example by being immersed in an oil bath or in a mist of oil droplets.
[0006] Due to the difference in thermomechanical properties of the metal of the pins and the material of the overmolding elements, gaps may form during overmolding or, with wear, between these elements and thus allow liquid infiltration.
[0007] The sealing of the final overmolding is therefore important, in particular to prevent the liquid from entering the sensor along the electrical pins and thus damaging the integrated circuit and / or the measuring cells, in particular with the formation of dendrites which can create a short circuit.
[0008] A known solution consists of placing a receptacle around the pins and depositing a gel inside said receptacle so that said gel surrounds the pins to create a seal. However, positioning the receptacle and introducing the gel around the pins can be complex and time-consuming, and ensuring a seal between the sealing housing and the receptacle can be difficult.
[0009] There is therefore a need for a solution that will at least partially remedy these drawbacks. Description of the invention
[0010] To this end, the invention first relates to a method for manufacturing a sensor for a motor vehicle, comprising an integrated circuit connected to parameter measurement cells, and connection pins electrically connected to the integrated circuit and intended to be connected to the vehicle's electrical network, the method comprising the steps of: a. - placement of the connection pins on a support, b. - positioning of a mold around the connecting pins, said mold being configured to surround the connecting pins, c. - injection of overmolding material into the mold so as to obtain a sealing housing comprising a body and a hatch, said body being in the form of a parallelepiped-shaped belt of material comprising four solid faces delimiting an internal space, an open lower face and an open upper face of the sealing housing, the sensor connection pins passing through two opposite solid faces of the body, respectively called "front" and "rear", the other two faces of the body being a solid lateral face and a lateral face called "junction", the hatch being formed adjacent to the belt in the plane of the lower face of the body by being connected to the lateral junction face by at least one portion of overmolding material, called "connecting portion". d. - mold shrinkage, e. - application of a force on the hatch so as to detach said hatch from at least one portion of the connection and to slide said hatch to be inserted by sliding through the junction face and close the lower face of the sealing housing, f. - filling, via the upper face of the sealing housing, the internal space of the sealing housing with a sealing gel in order to seal the connection pins, g. - external overmolding of the entire sensor assembly.
[0011] This process makes it possible to obtain a gel-filled sealing housing which allows The goal is to seal the sensor better than with a simple reflow fin block as known in the prior art, since the gel is less susceptible to deformation due to a rise in material temperature and is therefore less likely to create faults at the connection pins, which could allow liquid to reach the measuring cells. In addition, at least one row of reflow fins is arranged around the sealing housing to ensure the seal of this subassembly between the molding of the sealing housing and the final overmolding of the sensor. The connecting portions between the body of the sealing housing and the hatch can also serve as a feed channel for the plastic molding material of the hatch during injection, thus avoiding the need for a second injection point at the hatch.Furthermore, this solution eliminates the need for a hinge-type connection, which restricts the use of fiberglass-reinforced materials and makes precise assembly difficult. It also eliminates the need for clips to secure the hatch within the sealing housing.
[0012] Preferably, the step of injecting the overmolding material for the sealing housing includes forming, on the underside, at least one support wedge for the hatch. This wedge supports the hatch after it has been slid to close the sealing housing in the closed position of the underside.
[0013] Advantageously, at least one wedge is a distal wedge connecting the front and rear faces, and the solid lateral face opposite the joining face. This wedge shape, connected to three walls, provides solid support for the hatch during its attachment.
[0014] In addition to this distal wedge, the overmolding material injection step advantageously includes the formation, on the lower face, of two proximal wedges opposite each other, one extending from the lower edge of the front face, the other from the lower edge of the rear face.
[0015] Preferably, the proximal shims are positioned between the midpoint of the front and rear faces and the joining face, and are offset from the connecting pins so as not to be immediately below them for the molding of the sealing housing. These shims provide support for the hatch, particularly in its midsection.
[0016] Preferably, the overmolding material injection step also includes forming, on each of the front and rear faces, a retaining wedge extending from said front and rear faces into the internal space, as well as a retaining and sealing boss at the bottom of the junction face. These wedges are positioned above the hatch location to exert pressure on the top of the hatch once it is inserted into the body, thus locking it in the closed position. The retaining and sealing boss has the same function at the bottom of the junction face. The function of these devices is to ensure the sealing of the sealing housing. at the level of the distal wedge on the solid lateral face and also at the level of the lateral junction face, thus allowing the gel to be deposited in the sealing housing.
[0017] Advantageously, these retaining wedges are arranged opposite each other.
[0018] Further advantageously, these retaining wedges are located between two connecting pins so as not to be immediately below them for the molding of the sealing housing.
[0019] Preferably, the overmolding material injection step includes forming lateral sliding grooves and ridges along the lateral edges of the hatch. The edges slide on the shims on the underside. Since the hatch extends along a longitudinal axis parallel to the direction of hatch insertion, these lateral edges of the hatch are parallel to the longitudinal axis of the hatch along which it is inserted into the sealing housing. The outer edges of these lateral ridges flatten slightly during insertion of the hatch into the sealing housing along both the front and rear faces, thus ensuring the sealing of the housing and allowing the gel to be deposited within it.
[0020] Preferably, the overmolding material injection step includes the formation of a depression centered on the upper surface of the hatch. Thus, when the sealing housing is filled with gel, the gel fills this depression, and after solidification, this filling helps to keep the hatch in the closed position. Furthermore, molding the body and the hatch does not require additional drawers in the molding tool, but only a lower cavity and an upper cavity.
[0021] The invention also relates to the mold used for shaping the sealing housing with the method, comprising a body and a hatch, said body being in the form of a parallelepiped-shaped material belt comprising four solid faces delimiting an internal space, an open lower face and an open upper face of the sealing housing, the sensor connection pins passing through two opposite faces respectively called "front" and "rear", the hatch being formed adjacent to the belt in the plane of the lower face of the body by being connected to a solid face of the body by at least one portion of overmolding material, called "connecting portion", application of a force on the hatch so as to detach said hatch from at least one connecting portion and to slide said hatch to insert it by sliding and thus close the lower face of the sealing housing.
[0022] The invention also relates to a vehicle sensor thus obtained with the method comprising an electrical connection connector to the vehicle and a fixing element to an element of said vehicle.
[0023] The invention also relates to a motor vehicle comprising a sensor obtained with the process thus described. Brief description of the drawings
[0024] Other features and advantages of the invention will become apparent from the following description. This description is purely illustrative and should be read in conjunction with the accompanying drawings, in which:
[0025] [Fig-1] Fig.1 schematically illustrates in perspective one form of realization of an assembly comprising an overmolding of a sealing housing, hatch in open position, on metallic connection pins and an overmolding of an integrated circuit and measuring cells connected to said connection pins.
[0026] [Fig.2] The [Fig.2] is a top perspective view of the sealing housing of the [Fig.1], hatch in the open position.
[0027] [Fig.3] The [Fig.3] is a perspective view from below of the sealing housing of the [Fig.1], hatch in the open position.
[0028] [Fig.4] The [Fig.4] is a top perspective view of the sealing housing of the [Fig.1], hatch in the closed position.
[0029] [Fig.5] The [Fig.5] is a perspective view from below of the sealing housing of the [Fig.1], hatch in the closed position.
[0030] [Fig.6] The [Fig.6] is a cross-sectional view of the sealing housing of the [Fig.1] after its overmolding, in its mold.
[0031] [Fig.7] Fig.7 schematically illustrates in perspective an embodiment of an assembly comprising an overmolding of a gel-filled sealing housing, hatch in the closed position, on metallic connecting pins and an overmolding of an integrated circuit and measuring cells connected to said connecting pins.
[0032] [Fig.8] The [Fig.8] schematically illustrates the sensor of the [Fig.1] after the sealing operation and a final overmolding of the sensor.
[0033] [Fig.9] Fig.9 schematically illustrates one embodiment of the process according to the invention. Description of the implementation methods
[0034] The sensor obtained by the process according to the invention is intended to be mounted in a motor vehicle. The sensor can be of any type. The sensor can, for example, be a position or speed sensor for a drive shaft such as a crankshaft, camshaft, gearbox, or any other suitable shaft.
[0035] Fig. 1 illustrates an example of an intermediate form of the sensor 1 during its manufacture in an embodiment of the process according to the invention.
[0036] Sensor 1
[0037] The sensor 1 includes two connection pins 10, a support overmolding 20 and a sealing housing 30.
[0038] Connection pins 10
[0039] The rectangular-section connecting pins 10 each comprise a free end 101 intended to be electrically connected to an electrical network of the vehicle (not shown), and a connection end 102 overmolded in a support overmolding 20.
[0040] Each connection pin 10 has a connector 103 allowing the said connection pin 10 to be electrically soldered with a connection leg 24 of the integrated circuit 23 (visible in [Fig.7]) of the sensor 1.
[0041] In the embodiment shown in [Fig.1], the two connecting pins 10 are initially linked to simplify the molding step and are subsequently punched to be separated.
[0042] Support overmolding 20
[0043] Still with reference to [Fig.1], the support overmolding 20 is molded around the connection ends 102 of the pins of the connection 10. Alternatively, the pins of the connection 10 could be attached to the support 20.
[0044] The support overmolding 20 delimits in this non-limiting example a cavity 21 intended to receive a magnet (not visible) and a receiving surface 22 of an integrated circuit 23 (visible on the [Fig.7]) of the sensor 1.
[0045] Sealing housing 30
[0046] With reference to figures 2 to 6, the sealing housing 30 comprises a body 31 and a hatch 32.
[0047] Body 31
[0048] The body 31 is parallelepiped in shape comprising six faces: a solid lateral face 311, a face 312 called the "front", a lateral face called the "junction" 313, a face 314 called the "rear" opposite the front face 312, a face called the "upper" 315 and a face called the "lower" 316
[0049] The opposite front faces 312 and rear faces 314 are traversed by the connection pins 10.
[0050] The front face 312 has an injection rim 319 of the overmolding.
[0051] The rear face 314 is extended in the direction of the connecting pins 10 by a set of reflow fins 317 which are also crossed by said connecting pins 10, limited by the rear face 314 and by a protective wall 318 of these reflow fins 317 during the final overmolding.
[0052] The upper face 315 is devoid of overmolding material (i.e. is hollowed out) in order to allow the sealing housing 30 to be filled with gel 33.
[0053] The lower face 316 is hollowed out and configured to receive the hatch 32. Material remains present on this face, in the form of a distal wedge 3161 extending from the bottom of the solid lateral face 311, and two retaining wedges 3162, one extending from a section of the bottom of the front face 312 and the other from the rear face 314, two proximal wedges 3163, one extending from a section of the inside of the front face 312 and the other from the rear face 314. A retaining and sealing boss 3164 is present at the bottom of the joining face 313.
[0054] The joining face 313 is connected to the hatch 32 by the connecting portions 321
[0055] Hatch 32
[0056] The hatch 32 includes the connecting portions 321, a depression 322, and sliding grooves 323 as well as the lateral grooves 324 on either side of the hatch 32 in the direction of sliding in the body 31 of the sealing box 30.
[0057] Gel 33
[0058] The gel 33 is poured into the sealing housing 30 after the latter has been closed.
[0059] Mold 40
[0060] Fig. 6 represents the internal impressions of the upper part 41 and the lower part 42 of the mold 40.
[0061] Final overmolding 50
[0062] With reference to [Fig.8], the sensor 1 includes a final overmolding 50 forming the outer casing of the sensor.
[0063] The sensor 1 with final overmolding 50 also includes an electrical connection connector 51 configured to connect the free ends 101 of the connection pins 10 to the vehicle's electrical circuit, as well as a fixing member 52 which allows the sensor 1 to be fixed in the vehicle.
[0064] Example of implementation
[0065] The sealing process is shown in [Fig.9].
[0066] In a step 11, the connecting pins 10 are placed on a retaining support. Each connecting pin 10 has a free end 101 and a connector 103 on the connecting end 102.
[0067] In step E2, the upper part 41 and the lower part 42 of the mold 40 are positioned on the connecting pins 10 in order to clamp them. The internal enclosure of the mold 40 is configured to form the sealing housing 30, comprising the body 31 and the hatch 32.
[0068] The upper part 41 of the mold 40 and the lower part 42 are each in contact with the segment of the connecting pins 10 which is inside the sealing housing 30.
[0069] In a step E3, the mold is filled with material which takes the shape of the sealing housing 30. The injection rim 319 of the overmolding has been studied and positioned so that it is sized to be able to properly feed the housing 31, without deforming the pins 10.
[0070] After step E4 of removing the two parts of the mold 40, the sealing housing 30 is overmolded onto the connecting pins 10. The connecting pins 10 pass through the front face 312 and the rear face 314, while the hatch 32 is integral with the body 31 by the connecting portions 321.
[0071] In a step E5, the connecting portions 321 reduced by the insertion tool then these connecting portions 321 are cut by this same tool under the force of their insertion and the hatch 32 closes the lower face 316 of the body 31 of the sealing housing 30.
[0072] Preferably, the hatch 32 is slid into the lower face 316. The sliding grooves 323 of the hatch fit under the junction face 313 of the body 31 between the retaining wedges 3162 and the proximal wedges 3163, as well as above the distal wedge 3161 present on the lower face 316. This wedge system makes it possible to lock the hatch 32 and to ensure the sealing of the sealing housing 30.
[0073] The retaining and sealing boss 3164 on the lower edge of the joining face 313 also allows pressure to be applied to the hatch 32 to ensure the sealing of the sealing housing 30 and to hold the hatch 32 in position on the lower face 316 during the remaining operations of the sealing process. The external edges of the lateral grooves 324 are slightly compressed when the hatch 32 is inserted into the body 31 along the entire length of the front face 312 and the rear face 314, thus ensuring the sealing of the sealing housing 30 and allowing the gel to be deposited in the sealing housing 30.
[0074] Preferably, the cutting of the connecting portions 321 and the sliding insertion of the hatch 32 into the lower face 316 is done in one go, the force exerted on the hatch 32 being sufficient to section the connecting portions 321.
[0075] Once the hatch 32 is closed, the sealing housing 30 is filled with gel 33 in step E6. The gel 33 is poured into the space formed by the body 31 closed by the hatch 32 and surrounds the connecting pins 10. The gel 33 solidifies around the connecting pins 10 and prevents liquid from flowing back up these pins. During its solidification, the gel 33 fills the depression 322 in the hatch 32, blocking it and ensuring its closure. Once the gel 33 has solidified, the sealing process is complete.
[0076] The support overmolding 20 is overmolded in a step E7 onto the connection end 102 of the connection pins 10, and a sensor is placed on it and connected to the connectors 103. Alternatively, this step could be carried out before or simultaneously with the molding of the sealing housing 30.
[0077] Depending on the nature of the signal measured by the sensor, a magnet can be added in the support overmolding 20 in the location 21.
[0078] In another embodiment, the overmolding of the sealing housing 30 and that of the support overmolding 20 are carried out simultaneously.
[0079] Once the sealing process and the overmolding of support 20 have been carried out, the final sensor 1 is obtained following a final overmolding 50 which is carried out on the assembly shown in [Fig.1] including the connection pins 10, the sealing housing 30 and the support overmolding 20, so as to have a final overmolding 50 which encloses these elements.
[0080] The sensor 1 thus obtained is fixed in the vehicle by the fixing member 52.
[0081] The invention therefore proposes a reliable and efficient method for sealing a sensor for automobiles.
Claims
Claims
1. Method for manufacturing an electronic sensor (1) for a vehicle, said sensor (1) comprising an integrated circuit (23), comprising cells for measuring a parameter, and connection pins (10) on the one hand electrically connected to the integrated circuit (23) and intended on the other hand to be connected to an electrical network of the vehicle, said method comprising the steps of: - placement (El) of the connection pins (10) on a support, - positioning (E2) a mold (40) around the connection pins (10), said mold (40) being configured to surround the pins, - injecting overmolding material (E3) into the mold (40) so as to obtain a sealing housing (30) comprising a body (31) and a hatch (32), said body (31) being in the form of a belt of material of parallelepipedal shape comprising four solid faces delimiting an internal space, an open lower face (316) and an open upper face (315) of the sealing housing (30), the connection pins (10) of the sensor (1) passing through two opposite solid faces of the body (31), respectively called "front" (312) and "rear" (314), the other two faces of the body (31) being a solid lateral face (311) and a lateral face called "junction" (313),the hatch (32) being formed adjacent to the belt in the plane of the lower face (316) of the body (31) by being connected to the lateral joining face (313) by at least one portion of overmolding material, called “connecting portion” (321), - retraction (E4) of the mold (40) - applying (E5) a force to the hatch (32) so as to detach said hatch (32) from the at least one connecting portion (321) and to slide said hatch (32) to insert it by sliding through the joining face (313) and close the lower face (316) of the sealing housing (30), - filling (E6), via the upper face (315) of the sealing housing (30), the internal space of the sealing housing (30) with a sealing gel (33) in order to seal the connection pins (10), - external overmolding (E7) (50) of the entire sensor (1).
2. The method of claim 1, wherein the step of injecting overmolding material into the sealing housing (30) comprises: formation, on the lower face (316), of at least one wedge supporting the hatch (32).
3. Method according to the preceding claim, in which the at least one shim is a distal shim (3161) connecting the front (312) and rear (314) faces, and the solid lateral face (311), opposite the junction face (313).
4. Method according to any one of claims 2 or 3, in which the step of injecting overmolding material comprises the formation, on the lower face (316), of two proximal wedges (3163) facing each other, one extending from the lower edge of the front face (312), the other from the lower edge of the rear face (314) as well as a holding and sealing boss (3164) at the bottom of the joining face (313).
5. A method according to any preceding claim, wherein the step of injecting overmolding material comprises forming on each of the front (312) and rear (314) faces a retaining wedge (3162) extending from said front (312) and rear (314) faces into the internal space.
6. A method according to any preceding claim, wherein the step of injecting overmolding material comprises forming lateral sliding grooves (323) and lateral flutes (324) along the lateral edges of the hatch (32).
7. A method according to any preceding claim, wherein the step of injecting overmolding material comprises forming a depression (322) centered on the upper surface of the hatch (32).
8. Sensor (1) for a vehicle obtained with the method according to one of claims 1 to 7, said sensor comprising an electrical connection connector (51) to the vehicle and a fixing member (52) to an element of said vehicle.
9. Motor vehicle comprising a sensor (1) according to the preceding claim.