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

Abstract

The invention relates to an inductive sensor (100), as well as 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 (130), an insert (120), the printed circuit and the insert superimposed on the circuit both being embedded in a resin in an interior space of said housing, which is defined by a bottom (119) as well as 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 thus being pressed against the bottom of said housing. Figure for the abstract: Figure 1.

Description

Title of the invention: Method for manufacturing an inductive sensor provided 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 of manufacturing such a sensor. State of the art

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

[0003] When an inductive angular position sensor is used, the rotating part is equipped with a partially metallized disc. Near this disc is an oscillating circuit of the LC type (capacitor coil) whose damping depends on the distance between the coil L and the metallized zone traveled by the eddy currents generated during the oscillation. Observing this damping makes it possible to detect the rotation of the rotating part. The use of several coils can make it possible, for example, to also detect the direction of rotation of the rotating part.

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

[0005] Manufacturing processes generally involve inserting the printed circuit board into the housing and pouring a resin to immobilize and protect the printed circuit board.

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

[0007] This is why it is necessary to reduce the volume of resin consumed, which which allows a cost saving on the one hand, and production time on the other hand, since with a lower resin volume, the polymerization time decreases accordingly.

[0008] Furthermore, it is important to position the circular part which carries the 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 which would make lateral or vertical movements possible.

[0010] It is known to use rivets which allow the printed circuit to be positioned in its housing, and to fix the circuit permanently by punching these rivets. This fixing is implemented before pouring the resin.

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

[0012] Indeed, the use of rivets in 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 aim of the present invention is also to eliminate the use of these rivets, with of course the riveting operations. Statement 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, an insert, said method comprising the following steps: - Positioning of the printed circuit in an interior space of said housing, the interior space being defined by a bottom and an exterior edge, - Positioning the insert over the printed circuit, - Movement of the insert so as to place at least one bearing surface provided on the outer edge of said housing and one bearing surface provided on the periphery of the insert in contact with each other, the printed circuit thus being pressed by the insert against the bottom of said housing, - Pouring a resin into the interior space of said housing fitted with the printed circuit and the insert, - Polymerization of said resin.

[0015] Various embodiments of the invention are provided, integrating, according to all of their possible combinations, the various optional characteristics set out below.

[0016] According to a particular manufacturing method, the movement of the insert pressing against each 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, 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 respectively have the shape of a disc hollowed out in its center, a part of the interior space being of substantially complementary shape, the outer edge of the housing having an interior circumferential surface induced by the complementarity of shape, and having at least three projecting lugs each carrying a bearing surface, the insert also comprising at its periphery at least three projecting 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 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 at least least three lugs of the housing, and thus place the bearing surfaces of said lugs provided respectively on the outer edge of the housing and on the periphery of the insert in contact with each other.

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

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

[0021] Advantageously, the housing also comprises a substantially circular inner edge provided on its outer circumferential surface with protrusions allowing centered positioning of the printed circuit in the interior 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, and an insert, superimposed on the circuit, the printed circuit 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 as well as an outer edge, the outer edge of said housing comprising at least one surface bearing against a surface formed on the periphery of the insert, the printed circuit thus being pressed by the insert against the bottom of said housing.

[0023] Various embodiments of the invention are provided, integrating, according to all of their possible combinations, the various optional characteristics set out below.

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

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

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

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

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

[0029] According to another advantageous aspect, the housing comprises a substantially circular inner edge provided on its outer circumferential surface with protrusions allowing centered positioning of the printed circuit in the interior space of said housing. Brief description of the FIGURES

[0030] The invention will be better understood on reading the following description, given solely by way of non-limiting example and made with reference to the appended drawings in which: - [Fig.l] is a schematic representation of a perspective section of an exemplary embodiment according to the invention, non-limiting, of an inductive angular position sensor. - [Fig.2] is a schematic perspective representation of a housing of a non-limiting example of an inductive angular position sensor according to the invention. - [Fig.3] is a schematic perspective representation of an element contributory example of an embodiment according to the invention, non-limiting, of an inductive angular position sensor. - [Fig.4] is a schematic perspective representation of a circuit printed example of an 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 non-limiting example of an inductive angular position sensor according to the invention.

[0031] It is understood that the embodiments which will be described below are in no way limiting. In particular, it will be possible to imagine variants of the invention comprising only a selection of characteristics described below isolated from the other characteristics described, if this selection of characteristics is sufficient to confer a technical advantage or to differentiate the invention compared to the state of the prior art. This selection comprises at least one preferably functional characteristic without structural details, or with only a part of the structural details if it is this part which is only sufficient to confer a technical advantage or to differentiate the invention compared to the state of the prior art.

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

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

[0034] [Fig.l] is a schematic representation of a perspective section of an exemplary embodiment according to the invention, non-limiting, 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 a z axis, 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 an exemplary embodiment according to the invention, non-limiting, of an inductive angular position sensor.

[0037] The interior space of the housing is defined by a bottom 119 as well as an outer edge 116 and an inner edge 116'. The housing may be made of Polyamide or Polybutylene Tetra-rephthalate (PBT). Other materials may also be used.

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

[0039] In more detail, the interior space of the housing is compartmentalized according to a hollowed-out disc-shaped part 111 intended to accommodate the portion of the printed circuit carrying the coils. The interior space of the housing also comprises an area 112 intended to accommodate electronic components of the printed circuit and an area 113 intended to accommodate the connectors of the printed circuit.

[0040] The part 111 of the interior space is of a shape substantially complementary to the part of the printed circuit carrying the coils.

[0041] “Shape complementarity” means that two parts have similar geometries with tolerances close to the order of a millimeter around the entire perimeter of the printed circuit and the insert, to allow coating with resin.

[0042] It is indeed important to maintain a clearance when inserting the printed circuit, then the insert into the interior space of the housing, to allow them to be coated with resin later.

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

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

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

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

[0047] The periphery of the insert preferably comprises three notches 122 allowing the insertion of said insert into the hollowed-out 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 of the outer edge 116 of the housing, like the three lugs on the periphery of the insert, are distributed in a balanced manner, in the sense that they are distributed at an angle of the order of 120 degrees each time.

[0049] [Fig.4] is a schematic perspective representation of a printed circuit of an exemplary embodiment according to the invention, non-limiting, of an inductive angular position sensor.

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

[0051] [Fig.5] is a schematic perspective representation of a detail of an exemplary embodiment according to the invention, non-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, it is possible to envisage a plurality of four or more lugs provided both on the edge 116 of the housing and on the periphery of the insert 120.

[0055] Instead of the lugs, it is also possible to envisage 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 interior 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 interior space of the housing also includes an area for accommodating electronic components of the printed circuit board and an area for accommodating the connectors of the printed circuit board.

[0058] The insert and the portion of the printed circuit 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 comprises at least one support surface provided to be pressed against a support surface provided on the periphery of the insert.

[0060] These bearing surfaces can be carried by projecting lugs or continuous or non-continuous ribs provided respectively on the edge of the housing as well as on the periphery of the insert.

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

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

[0063] This makes it possible to guarantee sufficient tightening, by overcoming 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 shown in [Fig.2], the housing comprises a substantially circular inner edge 116' provided on its outer circumferential surface with protrusions 115 allowing centered positioning of the printed circuit in the interior space of said housing.

[0065] Now concerning the method of manufacturing an inductive sensor 100 whether of the linear or angular position type, as described previously, a step of positioning the printed circuit in an interior space of said housing is first carried out.

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

[0067] Then, the insert is set in motion in the x, y plane so as to place the at least one (preferably at least two) bearing surface 114 provided on the outer edge of said housing in contact with each other, against the at least one (preferably at least two) bearing surface 124 provided on the periphery of the insert.

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

[0069] Finally, a resin is poured into the interior space of said housing fitted with the circuit. printed and insert.

[0070] This resin can be an epoxy resin.

[0071] Let us recall that “shape complementarity” means that two parts have similar geometries with tolerances close to the order of a millimeter, around the entire perimeter of the printed circuit and the insert.

[0072] It is indeed important to maintain a clearance when inserting the printed circuit, then insert them into the interior space of the housing, to allow them to be coated with resin.

[0073] A step of polymerization of said resin makes it possible to seal the assembly definitively.

[0074] In the case where the inductive sensor is an angular position sensor, of the type as described previously, that is to say comprising an insert 120 and a part 131 of the printed circuit 130 respectively having the shape of a disc hollowed out 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 projecting lugs (or ribs) each carrying a bearing surface 114, the insert also comprising at its periphery one or more projecting 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 along 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 axis (z) of the printed circuit is thus made impossible.

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

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

[0079] This provides a good compromise between sufficient clamping that maintains the position of the printed circuit board plated on the bottom of the housing, and an admissible clamping force. By "admissible clamping force" is meant an effort that can be carried out by an operator on a production line, or an effort 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 interior space of said housing is accompanied by centering of said circuit in said housing.

[0082] For this purpose, the housing may comprise a substantially circular inner edge 116' advantageously provided on its outer circumferential surface with protrusions 115 allowing centered positioning of the printed circuit in the interior space of said housing. Some of them may comprise an elastic effect in order to block the movements of the printed circuit in the plane (x, y).

[0083] In the case now where the inductive sensor is a linear sensor, the movement of the insert consists of a translation movement in the plane (x, y) 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 which have just been 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 housing as well as corresponding lugs (or ribs) on 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 projecting 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 in fact makes it possible to reliably immobilize the printed circuit in the housing before pouring the resin.

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

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

Claims

Claims

1. 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 (130) and an insert (120), characterized in that it comprises the following steps: • Positioning the printed circuit in an interior space of said housing, the interior space being defined by a bottom (119) and an outer edge (116) of said housing, • Positioning the insert (120) on the printed circuit, • Movement of the insert (120) so as to place 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 in contact with each other, the printed circuit thus being pressed by the insert (120) against the bottom of said housing, • Pouring a resin into the interior space of said housing fitted with the printed circuit and the insert,• Polymerization of said resin.,

2. Method according to claim 1, in which the movement of the insert (120) pressing against each other, 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. Method according to claim 1, in which the inductive sensor (100) is an angular position sensor, the insert (120) and a part (131) of the printed circuit (130) respectively having the shape of a disc hollowed out in its center, a part (111) of the interior space being of substantially complementary shape, the outer edge (116) of the housing having an inner circumferential surface induced by the complementarity of shape, which has at least three projecting lugs each carrying a bearing surface (114), the insert (120) also comprising at its periphery at least three projecting lugs each carrying a bearing surface (124), characterized in that: the step of moving the insert (120) consists of rotating 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 place the respective bearing surfaces (114, 124) of the lugs against each other.

4. A 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, in which the bearing surfaces (114, 124) of the lugs of the housing and of the insert are beveled, at an angle of between 2 and 15 degrees relative 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') provided on its outer circumferential surface with protrusions (115) allowing centered positioning of the printed circuit (130) in the interior 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 (130) and an insert (120), superimposed on the circuit, the printed circuit 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) as well as 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 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 (130) is in direct physical contact with the bottom (119) of the housing on the one hand and with the insert (120) on the other hand, the resin furthermore not covering the insert on the side opposite the printed circuit.

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. 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 part (131) of the printed circuit (130) respectively having the shape of a disc hollowed out in its center, a part (111) of the interior space being of substantially complementary shape, the outer edge (116) of the housing having an inner circumferential surface induced by the complementarity of shape, which has at least three projecting lugs each carrying a bearing surface (114), the insert also comprising at its periphery at least three projecting lugs each carrying a bearing surface (124).

11. An 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, in which the bearing surfaces (114, 124) of the lugs of the housing and of the insert are beveled, at an angle of between 2 and 15 degrees relative to the longitudinal plane (x, y).

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

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