Method for manufacturing an inductive sensor with an insert and associated inductive sensor

Abstract

The invention relates to an inductive sensor (100), and its manufacturing method, said sensor comprising a housing (110) extending in a plane (x, y) with a thickness measured along an axis (z), a printed circuit board (130), an insert (120), the printed circuit board and the insert superimposed on the circuit being both embedded in a resin within an interior space of said housing, which is defined by a base (119) and an outer edge (116), characterized in that the outer edge of said housing comprises at least one surface (114) bearing against a surface (124) formed on the periphery of the insert, the printed circuit board thus being pressed against the base of said housing. Figure 1.

Description

Title of the invention: Method for manufacturing an inductive sensor with an insert and associated inductive sensor technical field

[0001] The present invention relates to an inductive sensor, in particular an angular position sensor, as well as a method for manufacturing such a sensor. State of the art

[0002] It is known in the prior art to use an angular position sensor to detect the rotational speed of a rotating part in order to enable electronic information processing.

[0003] When using an inductive angular position sensor, the rotating part is equipped with a partially metallized disk. Near this disk is an LC (coil-capacitor) type oscillating circuit whose damping depends on the distance between the coil L and the metallized area through which the eddy currents generated during oscillation pass. Observing this damping allows the rotation of the rotating part to be detected. The use of several coils can, for example, also allow the direction of rotation of the rotating part to be detected.

[0004] Usually, an angular position sensor includes a housing which contains a printed electronic circuit consisting mainly of a circular part which carries coils, a set of electronic components and an area grouping connection terminals.

[0005] The manufacturing processes generally consist of inserting the printed circuit into the housing and pouring a resin to immobilize and protect the printed circuit.

[0006] However, the volumes of resin represent significant manufacturing costs.

[0007] Therefore, it is necessary to reduce the volume of resin consumed, this which allows for cost savings on the one hand, and production time savings on the other, since with a smaller volume of resin, the polymerization time decreases accordingly.

[0008] Furthermore, it is important to position the circular part which carries coils very precisely, since the reliability of the sensor depends not only on the positioning, but also on the stability of the positioning of the coils.

[0009] In other words, it is necessary to ensure that, after resin coating, the coils are immobilized in the housing and that there is no play that would make lateral or vertical movements possible.

[0010] It is known to use rivets to position the printed circuit board in its enclosure and to permanently fix the circuit by driving these rivets into place. This fixing is carried out before the resin is poured.

[0011] However, such a method of immobilization does not give complete satisfaction.

[0012] Indeed, the use of rivets at the bottom of the case makes the design heavier and, above all, results in a production quality that is very sensitive to tolerances.

[0013] An object of the present invention is also to eliminate the use of these rivets, with of course the riveting operations. Description of the invention

[0014] To this end, the invention relates to a method for manufacturing an inductive sensor comprising at least one housing extending in a longitudinal plane (x, y) with a thickness measured along an axis (z) orthogonal to the longitudinal plane, a printed circuit board, an insert, said method comprising the following steps: - Positioning of the printed circuit board within an internal space of said enclosure, the internal space being defined by a base and an outer edge, - Positioning the insert over the printed circuit board, - Movement of the insert so as to bring together, one against the other, at least one bearing surface provided on the outer edge of said housing, and one bearing surface provided on the periphery of the insert, the printed circuit board thus being pressed by the insert against the bottom of said housing, - Pouring a resin into the internal space of said housing, which is fitted with the printed circuit board and the insert, - Polymerization of said resin.

[0015] Various embodiments of the invention are provided, incorporating, according to all their possible combinations, the different optional features set out below.

[0016] According to a particular manufacturing method, the movement of the insert bringing together at least one bearing surface provided on the outer edge of said housing, and a bearing surface provided on the periphery of the insert, consists of clipping the insert onto the outer edge of said housing.

[0017] According to a manufacturing method dedicated to an inductive angular position sensor, the insert and a part of the printed circuit board respectively have the shape of a disc hollowed in its center, a part of the interior space being of substantially complementary shape, the outer edge of the housing having an inner circumferential surface induced by the complementarity of shape, and having at least three protruding lugs each carrying a bearing surface, the insert also having at its periphery at least three protruding lugs each carrying a bearing surface.

[0018] In this configuration, the movement of the insert in the longitudinal plane (x, y) consists of the rotation of the insert about itself around the axis (z) orthogonal to the longitudinal plane, so as to position the at least three lugs of the insert under the au minus three lugs of the case, and thus place against each other the bearing surfaces of said lugs provided respectively on the outer edge of the case and on the periphery of the insert.

[0019] Preferably, the bearing surfaces of the lugs of the housing and the insert are beveled, so as to produce a clamping force when the bearing surfaces are engaged against each other.

[0020] Even more preferably, the bearing surfaces of the lugs of the housing and the insert are beveled, at an angle between 2 and 15 degrees with respect to the longitudinal plane (x, y).

[0021] Advantageously, the housing also includes a substantially circular inner edge having protrusions on its outer circumferential surface allowing centered positioning of the printed circuit in the inner space of said housing.

[0022] The invention also relates to an inductive sensor comprising at least one housing extending in a longitudinal plane (x, y) with a thickness measured along an axis (z) orthogonal to the longitudinal plane, a printed circuit board, and an insert, superimposed on the circuit, the printed circuit board and the insert being located in an interior space of said housing and both embedded in a resin, said interior space being defined by a bottom and an outer edge, the outer edge of said housing comprising at least one surface bearing against a surface provided on the periphery of the insert, the printed circuit board thus being pressed by the insert against the bottom of said housing.

[0023] Various embodiments of the invention are provided, incorporating, according to all their possible combinations, the different optional features set out below.

[0024] Advantageously, the printed circuit board is in direct physical contact with the bottom of the housing on one side and with the insert on the other, the resin not covering the insert on the side opposite the printed circuit board.

[0025] According to a particular embodiment, the insert is clipped onto the outer edge of the case.

[0026] According to another particular embodiment, the inductive sensor is an angular position sensor, the insert and a part of the printed circuit board respectively having the shape of a disc hollowed in its center, a part of the interior space being of substantially complementary shape, the outer edge of the housing having an inner circumferential surface induced by the complementarity of shape, and having at least three protruding lugs each carrying a bearing surface, the insert also having at its periphery at least three protruding lugs each carrying a bearing surface.

[0027] According to a preferred aspect of the aforementioned embodiment, the bearing surfaces of the The lugs of the housing and the insert are beveled, so as to produce a clamping force when the bearing surfaces are engaged against each other.

[0028] According to an even more preferred aspect the bearing surfaces of the lugs of the housing and the insert are beveled, at an angle between 2 and 15 degrees with respect to the longitudinal plane (x, y).

[0029] According to another advantageous aspect, the housing has a substantially circular inner edge having protrusions on its outer circumferential surface allowing for centered positioning of the printed circuit board within the interior space of said housing. Brief description of the FIGURES

[0030] The invention will be better understood upon reading the following description, given solely by way of non-limiting example and made with reference to the accompanying drawings in which: - Fig. 1 is a schematic representation of a perspective cross-section of a non-limiting example of an embodiment according to the invention of an inductive angular position sensor. - [Fig. 2] is a schematic perspective representation of a casing of a example of an embodiment according to the invention, non-limiting, of an inductive angular position sensor. - [Fig. 3] is a schematic perspective representation of an element contributing an example of an embodiment according to the invention, non-limiting, of an inductive angular position sensor. - Figure 4 is a schematic perspective representation of a circuit printed from an example embodiment according to the invention, non-limiting, of an inductive angular position sensor. - [Fig. 5] is a schematic perspective representation of a detail of a example of an embodiment according to the invention, non-limiting, of an inductive angular position sensor.

[0031] It is understood that the embodiments described below are in no way limiting. In particular, variants of the invention may be conceived comprising only a selection of the features described below, isolated from the other features described, if this selection of features is sufficient to confer a technical advantage or to differentiate the invention from the prior art. This selection includes at least one preferably functional feature without structural details, or with only a portion of the structural details if this portion alone is sufficient to confer a technical advantage or to differentiate the invention from the prior art.

[0032] In particular, all the variants and all the embodiments described are combinable with each other if nothing prevents this combination from a technical point of view.

[0033] In the figures and in the rest of the description, elements common to several figures retain the same reference. Detailed description of the FIGURES

[0034] Fig. 1 is a schematic representation of a perspective section of a non-limiting example of an embodiment according to the invention of an inductive angular position sensor 100.

[0035] The inductive sensor 100 comprises a housing 110 extending in an x, y plane with a thickness measured along an axis z, a printed circuit 130, an insert 120. The printed circuit and the insert superimposed on the circuit, are both embedded in a resin 150 in an interior space of said housing.

[0036] Fig. 2 is a schematic perspective representation of a housing 110 of a non-limiting example embodiment according to the invention of an inductive angular position sensor.

[0037] The internal space of the housing is defined by a base 119, an outer edge 116, and an inner edge 116'. The housing can be made of polyamide or polybutylene terephthalate (PBT). Other materials can also be used.

[0038] The bottom is defined as the lower internal surface of the housing and may include optional asperities (or bumps) 117 and surface topologies. These asperities, which generally have a very small height (approximately 0.2 mm), may be introduced to correct any flatness defect.

[0039] In more detail, the internal space of the housing is compartmentalized according to a hollow, disc-shaped portion 111 intended to house the portion of the printed circuit board carrying the coils. The internal space of the housing also includes an area 112 intended to house electronic components of the printed circuit board and an area 113 intended to house the printed circuit board connectors.

[0040] Part 111 of the internal space is substantially complementary in shape to the part of the printed circuit board carrying the coils.

[0041] The term "complementarity of form" means that two parts have similar geometries within tolerances of the order of a millimeter around the entire perimeter of the printed circuit and the insert, to allow the resin to be embedded.

[0042] It is indeed important to preserve some play when inserting the printed circuit board, and then inserting it into the interior space of the housing, to allow for subsequent resin coating.

[0043] The outer edge 116 of the housing largely has an inner circumferential surface induced by the complementarity of shape, which has at least three protruding lugs each carrying a bearing surface 114.

[0044] Fig. 3 is a schematic perspective representation of a contributing element of a non-limiting embodiment of an inductive angular position sensor according to the invention.

[0045] This contributing element to the invention is the insert 120, which has the shape of a disc hollowed in its center, its shape also complementary to the part 111 of the internal space of the housing. The insert 120 has three projecting lugs on its periphery, each carrying a bearing surface 124 shaped to be pressed against one of the bearing surfaces 114 carried by one of the three lugs on the outer edge 116 of the housing.

[0046] Translation along the (z) axis of the printed circuit board is thus rendered impossible.

[0047] The periphery of the insert preferably has three notches 122 allowing the insertion of said insert into the hollow disc-shaped part 111 of the housing at the level of the three lugs provided on the outer edge 116.

[0048] Preferably, the three lugs on the outer edge 116 of the housing, as well as the three lugs on the periphery of the insert, are distributed in a balanced manner, in that they are distributed at an angle of approximately 120 degrees each time.

[0049] [Fig.4] is a schematic perspective representation of a printed circuit board of an example embodiment according to the invention, not limiting, of an inductive angular position sensor.

[0050] The printed circuit board 130 includes a portion 131 with coils, a set 132 of electronic components and a connector 133. The portion 131 has the shape of a disc hollowed in its center.

[0051] [Fig.5] is a schematic perspective representation of a detail of an example embodiment according to the invention, not limiting, of an inductive angular position sensor.

[0052] In this figure and in accordance with the principle of the invention, it can be seen that the bearing surfaces 114 provided on the lugs of the edge 116 of the housing are pressed against the bearing surfaces 124 provided on the lugs of the insert 120.

[0053] Of course, other variants of the invention are entirely conceivable.

[0054] Thus, one can envisage a plurality of four or more lugs provided at the same time on the edge 116 of the housing and on the periphery of the insert 120.

[0055] One can also consider, instead of the lugs, one or more circular ribs provided both on the inner circumferential surface of the edge 116 of the housing and on the periphery of the insert 120.

[0056] The invention can also be applied not only to inductive angular position sensors, but also to linear inductive sensors.

[0057] In this application not shown in the figures, the internal space of the housing is compartmentalized according to a rectangular part intended to accommodate the portion of the printed circuit board carrying the coils. The internal space of the enclosure also includes an area for the electronic components of the printed circuit board and an area for the connectors of the printed circuit board.

[0058] The insert and the portion of the printed circuit board carrying the coils also have a rectangular shape complementary to that of the housing.

[0059] According to the invention, the outer edge of the housing has at least one bearing surface provided for being pressed against a bearing surface provided on the periphery of the insert.

[0060] These bearing surfaces can be supported by protruding lugs or continuous or non-continuous ribs respectively on the edge of the housing and on the periphery of the insert.

[0061] According to an improvement of the invention applicable to both linear inductive sensors and angular position inductive sensors, the bearing surfaces 114, 124 of the housing and the insert are beveled, so as to produce a clamping effect when the bearing surfaces 114, 124 are engaged against each other.

[0062] Advantageously and as shown in the enlarged inset of [Fig.2] and [Fig.3], the bearing surfaces 114, 124 of the lugs of the housing and the insert are beveled, at an angle between 2 and 15 degrees, with respect to the longitudinal plane (x, y), and preferably of the order of 5 degrees.

[0063] This makes it possible to guarantee sufficient tightening, by disregarding the tolerances of each of the parts, while keeping the force necessary for tightening within reasonable limits.

[0064] According to an improvement of the invention applicable in particular to inductive angular position sensors and represented in [Fig.2], the housing has a substantially circular inner edge 116' having protrusions 115 on its outer circumferential surface allowing centered positioning of the printed circuit in the inner space of said housing.

[0065] Regarding now the manufacturing process of an inductive sensor 100, whether of the linear or angular position type, as described previously, a step is first taken to position the printed circuit in an internal space of said housing.

[0066] Then the insert is positioned on the printed circuit board,

[0067] Next, the insert is moved in the x, y plane so as to bring together at least one (preferably at least two) bearing surface 114 provided on the outer edge of said housing, against at least one (preferably at least two) bearing surface 124 provided on the periphery of the insert.

[0068] Thus, the printed circuit board is placed against the bottom of said housing.

[0069] Finally, a resin is poured into the internal space of said housing containing the circuit printed and inserted.

[0070] This resin can be an epoxy resin.

[0071] Let us recall that "complementarity of form" means that two parts have similar geometries within tolerances of the order of a millimeter, all around the printed circuit board and the insert.

[0072] It is indeed important to preserve some play when inserting the printed circuit board, then insert them into the internal space of the case, to allow them to be coated with resin.

[0073] A polymerization step of said resin allows the whole to be sealed permanently.

[0074] In the case where the inductive sensor is an angular position sensor, of the type as described above, that is to say comprising an insert 120 and a part 131 of the printed circuit 130 having respectively the shape of a disc hollowed in its center, a housing 110 with a part 111 of the interior space of substantially complementary shape, the outer edge 116 of the housing having for example one or more protruding lugs (or ribs) each carrying a bearing surface 114, the insert also having at its periphery one or more protruding lugs (or ribs) each carrying a bearing surface 124, the step of movement of the insert in the x, y plane consists of the rotation of the insert on itself about the z axis.

[0075] Due to this rotation, the lugs of the insert (or ribs) are positioned under the corresponding lugs (or ribs) of the housing, and the bearing surfaces 114, 124 of the lugs (or ribs) are pressed against each other.

[0076] Translation along the (z) axis of the printed circuit board is thus rendered impossible.

[0077] In the improvement in which the bearing surfaces 114, 124 of the lugs (or ribs) of the housing and the insert are beveled, a clamping effect is produced when the bearing surfaces 114, 124 are engaged against each other.

[0078] The rotation and subsequent tightening are delimited by the slope defined by the beveled surfaces. This slope has an angle between 2 and 15 degrees, with respect to the longitudinal plane (x, y), and preferably an angle of the order of 5 degrees.

[0079] This achieves a good compromise between sufficient clamping force to maintain the position of the printed circuit board against the bottom of the housing, and an permissible clamping force. "Permissible clamping force" refers to a force that can be applied by an operator on a production line, or a force applied by a robot without damaging the structure of the housing and the insert.

[0080] The insert may advantageously have gripping means 121 on its outer face so as to facilitate its movement (rotation in the case of an inductive angular position sensor or translation in the case of an inductive sensor) linear).

[0081] Advantageously, the positioning of the printed circuit in an internal space of said housing is accompanied by a centering of said circuit in said housing.

[0082] To this end, the housing may include a substantially circular inner edge 116' advantageously provided on its outer circumferential surface with protrusions 115 allowing for centered positioning of the printed circuit board within the interior space of said housing. Some of these protrusions may have an elastic effect in order to prevent movement of the printed circuit board in the (x, y) plane.

[0083] In the case now where the inductive sensor is a linear sensor, the movement of the insert consists of a translational movement in the (x, y) plane so as to slide the lugs (or ribs) of the insert under the lugs (or ribs) of the outer edge of the housing.

[0084] Of course, the invention is not limited to the examples just described.

[0085] It would be possible, for example, in the case of an inductive angular position sensor to provide lugs (or ribs) on the inner edge of the case as well as corresponding lugs (or ribs) around the periphery of the insert recess.

[0086] It is thus understood that the invention makes it possible to eliminate the use of rivets which require not only drilling operations 134 of the printed circuit but also riveting operations, during which rivets protruding from the bottom of the housing are passed through respective openings drilled in the printed circuit and then deformed to prevent any movement of withdrawal of the printed circuit.

[0087] The invention makes it possible to reliably immobilize the printed circuit in the housing before pouring the resin.

[0088] It is also understood that the invention makes it possible to reduce the volume of resin consumed, which allows for a saving in cost on the one hand, and in production time on the other, since with a smaller volume of resin, the polymerization time decreases accordingly.

[0089] Depending on the size of the insert adopted, it is indeed possible to achieve reductions in resin volumes of up to 50%.

Claims

Demands

1. A method for manufacturing an inductive sensor (100) comprising a housing (110) extending in a longitudinal plane (x, y) with a thickness measured along an axis (z) orthogonal to the longitudinal plane, a printed circuit board (130), and an insert (120), characterized in that it comprises the following steps: • Positioning the printed circuit board in an interior space of said housing, the interior space being defined by a base (119) and an outer edge (116) of said housing, • Positioning the insert (120) on the printed circuit board, • Moving the insert (120) so as to bring into contact, at least one bearing surface (114) formed on the outer edge (116) of said housing, and a bearing surface (124) formed on the periphery of the insert, the printed circuit board thus being pressed against the base of said housing by the insert (120). housing, • Pouring of resin into the internal space of said housing fitted with the printed circuit board and the insert,• Polymerization of said resin.

2. A method according to claim 1, wherein the movement of the insert (120) bringing together at least one bearing surface (114) provided on the outer edge (116) of said housing and a bearing surface (124) provided on the periphery of the insert, consists of clipping the insert (120) onto the outer edge (116) of said housing.

3. A method according to claim 1, wherein the inductive sensor (100) is an angular position sensor, the insert (120) and a portion (131) of the printed circuit board (130) having respectively the shape of a disc hollowed in its center, a portion (111) of the internal space being of substantially complementary shape, the outer edge (116) of the housing having an inner circumferential surface induced by the complementary shape, which has at least three protruding tabs each carrying a bearing surface (114), the insert (120) also having at least three protruding tabs on its periphery each carrying a bearing surface (124), characterized in that: the movement step of the insert (120) consists of the rotation of the insert on itself along the axis (z) orthogonal to the longitudinal plane, so as to position the at least three lugs of the insert under the lugs of the housing, and thus press the respective bearing surfaces (114, 124) of the lugs against each other.

4. Method according to claim 3, wherein the bearing surfaces (114, 124) of the lugs of the housing and the insert are beveled, so as to produce a clamping force when the bearing surfaces (114, 124) are engaged against each other.

5. Method according to claim 4, wherein the bearing surfaces (114, 124) of the lugs of the housing and the insert are beveled, at an angle between 2 and 15 degrees with respect to the longitudinal plane (x, y).

6. A method according to any one of claims 3 to 5, wherein the housing has a substantially circular inner edge (116') having protrusions (115) on its outer circumferential surface allowing centered positioning of the printed circuit board (130) in the inner space of said housing.

7. Inductive sensor (100) comprising a housing (110) extending in a longitudinal plane (x, y) with a thickness measured along an axis (z) orthogonal to the longitudinal plane, a printed circuit board (130) and an insert (120), superimposed on the circuit, the printed circuit board and the insert being located in an interior space of said housing and embedded in a resin, said interior space being defined by a bottom (119) and an outer edge (116), characterized in that the outer edge of said housing comprises at least one surface (114) bearing against a surface (124) formed on the periphery of the insert, the printed circuit board thus being pressed by the insert (120) against the bottom of said housing.

8. Inductive sensor according to claim 7, characterized in that the printed circuit board (130) is in direct physical contact with the bottom (119) of the housing on one side and with the insert (120) on the other side, the resin not further covering the insert on the side opposite the printed circuit board.

9. Inductive sensor according to claim 7 or 8, characterized in that the insert (120) is clipped onto the outer edge (116) of the housing.

10. An inductive sensor according to claim 7 or 8, characterized in that the inductive sensor (100) is an angular position sensor, the insert (120) and a portion (131) of the printed circuit board (130) having respectively the shape of a disc hollowed in its center, a portion (111) of the internal space having a substantially complementary shape, the outer edge (116) of the housing having an inner circumferential surface induced by the complementarity of form, which has at least three protruding lugs each bearing a bearing surface (114), the insert also having at its periphery at least three protruding lugs each bearing a bearing surface (124).

11. Inductive sensor according to claim 10, wherein the bearing surfaces (114, 124) of the lugs of the housing and the insert are beveled, so as to produce a clamping force when the bearing surfaces (114, 124) are engaged against each other.

12. Inductive sensor according to claim 11, wherein the bearing surfaces (114, 124) of the lugs of the housing and the insert are beveled, at an angle between 2 and 15 degrees with respect to the longitudinal plane (x, y).

13. Inductive sensor according to any one of claims 10 to 12, wherein the housing has a substantially circular inner edge (116') having protrusions (115) on its outer circumferential surface allowing centered positioning of the printed circuit in the inner space of said housing.

Images