Overmolded target for automotive vehicles

Abstract

The invention relates to a target (110) for a motor vehicle (1) shaft, said target (110) being configured to be mounted on a free end of said shaft and comprising at least one metal tooth (112), a body (114) supporting said at least one metal tooth (112), and a fixing element (116) comprising an insertion portion (116A) configured to be inserted at least in part on the end of the shaft, the body (114) being overmolded, at least in part, around the at least one tooth (112). Figure for abstract: Figure 3

Description

Title of the invention: Overmolded target for a motor vehicle Technical field

[0001] The present invention relates to the automotive field and more particularly concerns a target for a motor vehicle shaft and its manufacturing method. Prior art

[0002] In a motor vehicle, it is known to use a sensor with a drive shaft, for example to measure its rotational speed and feed this information back to an electronic control unit of the vehicle to enable its control or driving assistance. For example, in a vehicle with an electric motor, it is known to use such a sensor to measure the rotational speed of said electric motor in order to be able to control it.

[0003] This type of sensor comprises a sensitive element fixedly mounted on a structural element of the vehicle opposite a metal target mounted on the end of the shaft in a rotationally fixed manner.

[0004] [Fig. 1] schematically illustrates an example of a sensor assembly 10AA of the prior art. The assembly 10AA comprises a target 110AA, a sensor 120AA and a management module 130AA. The target 110AA comprises teeth 112AA extending from a central tubular portion 114AA mounted on a shaft 20AA of longitudinal axis XAA and rotating in a direction of rotation F. In this example, the teeth 112AA are of different angular lengths II, 12, 13, of the same heights hl, h2, h3 and spaced apart by different angular widths Cl, C2, C3. The sensor 120AA comprises a sensitive element comprising a magnetized portion 121 AA mounted on a support 122AA electrically connected to the management module 130AA. In operation, the passage of the metal teeth 112AA in front of the magnetized portion 121AA makes it possible to vary the magnetic field and generate signals which are received by the management module 130AA which sends them to an electronic control unit (not visible) of the vehicle.The electronic control unit processes the signals to determine, for example, the angular position or rotational speed of the shaft.

[0005] In a known manner, such a target 110AA can be manufactured by stamping or by machining. When manufactured by stamping, the target 110AA has tolerances which are different from one target 110AA to another and which on average add to each other, thus making the sensor assembly 10AA inaccurate. When manufactured by machining, the tolerances are on average less important but a significant quantity of metal is lost because the piece of metal original must have at least the diameter of the teeth 112AA of the target 110AA and the entire peripheral part of the tubular portion 114AA, of smaller diameter, must be removed.

[0006] A simple, reliable and effective solution to at least partially remedy these drawbacks would therefore be advantageous. Statement of the invention

[0007] To this end, the invention firstly relates to a target for a motor vehicle shaft, said target being configured to be mounted on a free end of said shaft and comprising at least one metal tooth, a body supporting said at least one metal tooth, and a fixing element comprising an insertion portion configured to be fixed at least in part to the end of the shaft, the target being remarkable in that the body is overmolded, at least in part, around the at least one tooth.

[0008] The overmolding of the metal teeth makes it possible to limit the quantity of metal used, in particular metal extracted by machining or stamping, and therefore to reduce the cost of the target. The use of overmolding of the teeth makes the target easy and inexpensive to manufacture. Another advantage of the target according to the invention lies in the fact that the fixing element can be of different shapes and different diameters to adapt to any type of shaft while retaining the same body and therefore the same mold for manufacturing the body for the same configuration of teeth. In addition, the target according to the invention requires little metal, only for the teeth and possibly for the fixing element, which significantly reduces the cost of the target.Additionally, the use of tooth overmolding makes it possible to greatly reduce, or even eliminate, tolerances from one target to another when manufacturing a batch of targets, thus making more accurate sensors using this target.

[0009] The end of the shaft preferably comprises a cylindrical portion, for example hollow.

[0010] In one embodiment, the fixing element comprises an attachment portion distinct from the insertion portion and provided with at least one relief, the body being overmolded around said attachment portion.

[0011] Preferably, the attachment portion is circular in shape.

[0012] More preferably, the at least one relief of the attachment portion is a rib, a notch or a vein.

[0013] In another embodiment, the fixing element and the body are made from the same overmolding material.

[0014] According to one aspect of the invention, the body delimits at least one opening passing through said body to the fixing element to allow the use of an insertion tool. of the target in the end of the shaft and, in the case of a "press-fit" type solution, to allow the coolant to pass through for engine versions using coolant, and in the case of a screwed solution to allow the use of a fixing screw for the body and for the fixing element.

[0015] Preferably, the teeth are made of stainless steel, aluminum or copper.

[0016] According to another aspect of the invention, the target comprises a plurality of teeth, preferably two, three, four or five teeth, overmolded in the body.

[0017] Preferably, the teeth are equally distributed.

[0018] In one embodiment, the insertion portion of the fixing element is a press-fit type sleeve, preferably with an annular groove.

[0019] In another embodiment, the insertion portion of the fixing element is a tube of circular cross-section and the target is configured to be fixed on the shaft via a screw.

[0020] According to one aspect of the invention, the body delimits at least one opening passing through said body and the fixing element, for example to allow the coolant to pass through for engine versions using a coolant in the case of the “press-fit” solution version or to allow the use of a fixing screw in the case of the screwed solution version.

[0021] Preferably, the head of the screw is retained on the target by a retention member, for example of the gadroon or locking notch type, in order to make the screw captive.

[0022] Advantageously, the material of the fixing element is magnetically and / or electrically neutral for detection by the sensor.

[0023] Advantageously, the material of the fixing element is identical to the material of the body, which makes it possible to reduce the distance between the sensor and the shaft and therefore the size.

[0024] The invention also relates to a motor vehicle comprising a drive shaft provided with a target as presented previously.

[0025] The invention also relates to a method of manufacturing a target as presented previously, said method comprising the steps of positioning the at least one metal tooth in a lower part of a mold, placing the upper part of the mold on the lower part and molding at least one part of the body around the at least one metal tooth.

[0026] In one embodiment, the method comprises, prior to placing the upper portion of the mold on the lower portion, positioning the fastener such that its attachment portion is molded into the body. Brief description of the drawings

[0027] Other characteristics and advantages of the invention will become apparent from reading the description which follows. This is purely illustrative and must be read in conjunction with the appended drawings in which:

[0028] [Fig-1] [Fig.l] schematically illustrates an example of a sensor assembly of prior art.

[0029] [Fig.2] [Fig.2] schematically illustrates an example of a vehicle according to the invention.

[0030] [Fig.3] [Fig.3] is a front perspective view of a first example of a target according to the invention.

[0031] [Fig.4] [Fig.4] is a rear perspective view of the target of [Fig.3].

[0032] [Fig.5] [Fig.5] is an isolated perspective view of the fixing element of the target of [Fig.3].

[0033] [Fig.6] [Fig.6] is a front perspective view of a second example of a target according to the invention.

[0034] [Fig.7] [Fig.7] is a rear perspective view of the target of [Fig.6].

[0035] [Fig.8] [Fig.8] is an isolated perspective view of the fixing element of the target of [Fig.6].

[0036]

[0037] [Fig.9] [Fig.9] schematically illustrates an embodiment of the method according to the invention. Description of the embodiments

[0038] [Fig.2] represents a schematic example of a motor vehicle 1 according to the invention.

[0039] The vehicle 1 comprises a sensor assembly 10 and a rotating shaft 20, for example an electric motor shaft whose sensor assembly 10 is adapted to measure the rotational speed.

[0040] The sensor assembly 10 comprises a target 110, a sensor 120 and a management module 130.

[0041] The target 110 is mounted on a free end 20A of the rotating shaft 20.

[0042] The sensor 120 is fixed (i.e. non-rotating) and is mounted in the vehicle 1 to the right of the rotating target 110. The sensor 120 makes it possible to measure the variations in the magnetic field generated when the shaft 20 is rotated. The sensor 120 notably comprises a sensitive element. Since the sensor 120 is known per se, it will not be detailed further here.

[0043] The end 20A of the shaft 20 on which the target 110 is mounted comprises in this example a hollow cylindrical portion (not visible), for example tubular, allowing the target 110 to be mounted.

[0044] Figures 3 to 8 illustrate two examples of target 110 according to the invention.

[0045] The target 110 comprises at least one metal tooth 112 (for example made of steel stainless steel, aluminum or copper), a body 114, overmolded, at least in part, around the at least one tooth 112, and a fixing element 116 comprising an insertion portion 116A configured to be inserted at least in part on or in the hollow cylindrical portion of the end 20A of the shaft 20.

[0046] In the two examples of Figures 3 to 8, the insertion portion 116A has a hollow cylindrical shape of circular section.

[0047] In the example of Figures 3 to 5, the insertion portion 116A comprises an annular groove 116A1 ([Fig. 3]) allowing easy “press-fit” type mounting with a circular rib of the shaft 20 (not visible). In the example of Figures 6 to 8, the insertion portion 116A has an external surface adapted to fit into the hollow cylindrical portion of the end 20A of the shaft 20 ([Fig. 8]) and allows the passage of a screw 117 in its center to fix the target 110 on the shaft 20.

[0048] In the two examples illustrated respectively in Figures 3 to 5 and 6 to 8, the fixing element 116 comprises an attachment portion 116B ([Fig.5]), distinct from the insertion portion 116A, in the form of a ring whose longitudinal axis coincides with the longitudinal axis of the insertion portion. The attachment portion 116B is provided over its entire external surface with ribs 116B1 ([Fig.5]) extending along the longitudinal axis of the fixing element 116 while being parallel to each other. In other words, in this non-limiting example, the ring is notched and the notches extend along the longitudinal axis of the fixing element 116 to prevent any rotation of the body 114 relative to the fixing element 116 once the attachment portion 116B is overmolded.

[0049] In both examples of Figures 3 to 5 and 6 to 8, the target 110 comprises three teeth 112. In other embodiments, the target 110 could comprise one, two, four, five or more teeth 112. Each tooth 112 is made of metal, for example stainless steel, aluminum or copper. Each tooth 112 has an angular cross-sectional shape, preferably with a thickness of between 0.6 mm and 2 mm.

[0050] The teeth 112 are equally distributed circularly on the target 110. In the examples of the figures, the teeth 112 are identical but, in another embodiment, the teeth 112 could be of different shapes. In the example of [Fig.3], each tooth 112 covers an angular opening of 60°. In another embodiment, the angular opening of the teeth 112 could be of different value.

[0051] The body 114 is made of a plastic material by being overmolded onto the teeth 112 and onto the attachment portion 116B. The body 114 has a circular shape. The spaces 114A between the teeth 112 are partly empty to save material when overmolding and lighten the target to reduce the need for a balancing step. These spaces can be through or not.

[0052] The spaces 114A are delimited by hollow shapes which serve to press the teeth 112 onto the faces of the impressions on the functional face side of the target 110 in order to ensure the correct position and overall flatness of the teeth 112. This presents a significant advantage compared to a target produced by “deep hammering” (or “deep stamping” which is a known process) in the context of an inductive sensor which requires high precision. The spaces 114A also make it possible to orient the target 110, in particular at the time of a press-fit insertion.

[0053] In another embodiment (not shown), the body 114 and the fixing element 116 could be made from the same overmolding material. In other words, the body 114 and the fixing element 116 could be a single piece obtained by injecting overmolding material from the teeth 112 into a mold.

[0054] The body 114 delimits at least one opening 114B passing through said body 114 as far as the fixing element 116 to allow the use of a tool for inserting the target 110 into the end 20A of the shaft 20. This opening 114B, when it completely passes through the target 110, can in particular be used to allow the circulation of coolant in certain types of shaft 20 of vehicle 1 and to grip and orient the target 110 during its insertion, in particular by press-fit.

[0055] With reference to [Fig.7], the body 114 comprises holding walls 114C serving to press the teeth onto the faces of the impressions on the functional face side of the target to ensure the very good position and overall flatness of the teeth 112, which proves to be important for an inductive type sensor and a significant advantage compared to a target of the prior art produced by deep stamping.

[0056] In another embodiment (not shown), the end 20A of the shaft 20 could be solid and receive a fitted or screwed target 110.

[0057] Manufacturing example

[0058] In this example, described in particular with reference to [Fig.9], the manufacture of the target 110 is carried out using a two-part mold.

[0059] First of all, in a step E1, the metal teeth 112 are positioned in the lower part of the mold, in an equally distributed manner, bearing on positioning members of the mold, for example in the shape of a V.

[0060] In a step E2, the fixing element 116 is also positioned in the lower part of the mold, for example using a holding pin, so that the longitudinal axis of the fixing element 116 is substantially aligned with the axis of equal distribution of the teeth 112 (i.e. the axis around which the teeth 112 are distributed).

[0061] The upper part of the mold is then placed on the lower part to close the mold in a step E3 then the overmolding plastic material is injected into the mold closed in a step E4 in order to form the body 114 which then overmolds both the attachment portion 116B and, in whole or in part, the metal teeth 112.

[0062] In another manufacturing method where there is no step E2, the body 114 and the fixing element 116 could both be formed by injecting material into the mold to form a single piece of the desired shape.

[0063] When the teeth are pre-positioned in the lower cavity of the mold, substantially eccentric from the axis to facilitate their insertion into the tool, the eccentricity value of the teeth 112 when they are placed in position in the mold can be defined by the size of a cone of the mold. Thus, a relatively large size of the cone makes it possible to comfortably move the tooth 112 away from its Vs, which greatly facilitates its pre-insertion and then its final positioning.When closing the mold, the impression of the upper cavity of the mold slides, by its cone, on a portion of the edge of the large diameter of the tooth 112, edge opposite the functional face of the target 110 until slightly mating this edge (non-functional) so that the lateral surfaces of each tooth 112 come into contact and therefore into position on the bearing faces of the mold in the shape of a "V", guaranteeing an excellent relative position of tooth 112 / axis of the shaft 20, and with very good repeatability. Such positioning is important, particularly with regard to inductive technology. The method makes it possible to avoid damaging the functional edges of the teeth 112 which are preferably sharp all around the functional face.

[0064] The target 110 according to the invention makes it possible to have a precise position of each tooth 112 relative to the sensor 120 both in the axis of the shaft 20 and in the two other directions.

[0065] When mounting the “press-fit” type target 110 at the end of the shaft, the insertion tool (not shown but known per se) comes to bear on the fixing element 116 and then allows fitting without damaging the plastic part of the target 110.

Claims

Claims

1. Target (110) for a shaft (20) of a motor vehicle (1), said target (110) being configured to be mounted on a free end (20A) of said shaft (20) and comprising at least one metal tooth (112), a body (114) supporting said at least one metal tooth (112), and a fixing element (116) comprising an insertion portion (116A) configured to be mounted at least in part on said end (20A) of the shaft (20), the target (110), the body (114) being overmolded, at least in part, around the at least one tooth (112), the target being characterized in that the body (114) comprises holding walls 114C serving to press the at least one tooth onto impression faces on the functional face side of the target to ensure flatness of at least one tooth (112), and in that the fixing element (116) comprises an attachment portion (116B) distinct from the insertion portion (116A) and provided with at least one relief (116B1),the body (114) being overmolded around said attachment portion (116B).,

2. The target (110) of claim 1, wherein the attachment portion (116B) is circular in shape.

3. Target (110) according to any one of claims 1 or 2, in which the at least one relief (116B1) of the attachment portion (116B) is a rib, a notch or a vein.

4. Target (110) according to claim 1, wherein the fixing element (116) and the body (114) are made from the same overmolding material.

5. Target (110) according to any one of the preceding claims, wherein the body (114) defines at least one opening (114B) passing through said body (114) to the fixing element (116) to allow use of a tool for inserting the target (110) into the end (20A) of the shaft (20).

6. A target (110) according to any preceding claim, said target (110) comprising a plurality of teeth (112), preferably two, three, four or five teeth (112), overmolded into the body (114).

7. Target (110) according to the preceding claim, in which the teeth (112) are equally distributed.

8. Motor vehicle (1) comprising a drive shaft (20) provided with a target (110) according to any one of the preceding claims.

9. A method of manufacturing a target (110) according to one of claims 1 to 7, said method comprising the steps of positioning the at least one metal tooth (112) in a lower part of a mold, placing the upper part of the mold on the lower part and molding at least a part of the body (114) around the at least one metal tooth (112).

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