Overmolded target for motor vehicle
By adopting overmolding technology in the sensor targets of motor vehicle axes, metal loss and tolerance problems in the manufacturing process of sensor targets are solved, and sensor manufacturing with lower cost and higher accuracy is achieved.
Patent Information
- Application Number
- CN202411198808.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2023-09-11
- Filing Date
- 2024-08-29
- Publication Date
- 2025-03-11
AI Technical Summary
The sensor targets of existing motor vehicle axes have metal loss and tolerance problems during the manufacturing process, resulting in inaccurate sensors.
Using overmolding technology, metal usage is limited by overmolding by the body at least partially around the metal teeth, and adapting to different shaft types through the various shapes and sizes of the fixing elements, reducing metal losses and tolerances.
Reduces the cost and manufacturing complexity of the target, improves the accuracy and manufacturing efficiency of the sensor, while adapting to the needs of different shaft types.
Smart Images
Figure CN119589882A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of motor vehicles, and more particularly to a target for a motor vehicle axle and a method for manufacturing the target. Background Art
[0002] In motor vehicles, it is known to use sensors together with the drive shaft, for example for measuring the rotational speed of the drive shaft and for transmitting this information to the electronic control unit of the vehicle for controlling the drive shaft or driver assistance features. For example, in electric motor vehicles, it is known to use such sensors to measure the rotational speed of said electric motor in order to be able to control this electric motor.
[0003] This type of sensor comprises a sensitive element fixedly mounted on a structural element of the vehicle, the structural element facing a metal target mounted on the end of a shaft so as to rotate together with the shaft.
[0004] Figure 1 An example of a sensor assembly 10AA of the prior art is schematically shown. 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 have different angular lengths I1, I2, I3, have the same heights h1, h2, h3, and are spaced apart by different angular widths C1, C2, C3. The sensor 120AA comprises a sensitive element comprising a magnetized portion 121AA mounted on a support 122AA electrically connected to the management module 130AA. During operation, the metal teeth 112AA pass through the magnetized portion 121AA causing a change in the magnetic field and generating signals received by the management module 130AA, which sends these signals to an electronic control unit (not visible) of the vehicle. The electronic control unit processes these signals in order to determine, for example, the angular position or rotation speed of the shaft.
[0005] In a known manner, such a target 110AA can be manufactured by pressing or by machining. When manufactured by pressing, the target 110AA exhibits tolerances that differ from one target 110AA to another and that, on average, overlap one another, thus making the sensor assembly 10AA somewhat inaccurate. When manufactured by machining, the tolerances prove smaller on average, but a large amount of metal is lost since the original metal workpiece needs to have at least the diameter of the tooth 112AA of the target 110AA and all the peripheral portions of the smaller diameter tubular portion 114AA need to be removed.
[0006] Therefore, a simple, reliable and effective solution allowing to at least partially remedy these drawbacks would be advantageous. Summary of the invention
[0007] To this end, the present invention firstly relates to a target for an axle of a motor vehicle, the target being configured to be mounted on the free end of the axle and comprising: at least one metal tooth; a body supporting the at least one metal tooth; and a fixing element comprising an insert portion configured to be at least partially fixed on the end of the axle, the target being notable in that the body is at least partially overmolded around the at least one tooth.
[0008] Overmolding the metal teeth makes it possible to limit the amount of metal used, in particular the amount of metal removed by machining or pressing, and thus reduces the cost of the target. The use of overmolding the teeth makes the target easy and cheap to manufacture. Another advantage of the target according to the invention lies in the fact that the fixing elements can have different shapes and different diameters in order to adapt to any type of shaft, while keeping the same body and therefore the same mold for making the body for the same configuration of teeth. In addition, the target according to the invention requires very little metal for the teeth or possibly for the fixing elements, and this significantly reduces the cost of the target. In addition, the use of overmolding the teeth makes it possible to greatly reduce, or even eliminate, the tolerances between the targets when manufacturing a batch of targets, thereby making the sensors using this target more accurate.
[0009] The end of the shaft preferably comprises a cylindrical portion, such as a hollow cylindrical portion.
[0010] In one form of embodiment, the fixing element comprises an attachment portion, distinct from the insertion portion and provided with at least one relief, the body being overmoulded around said attachment portion.
[0011] Preferably, the attachment portion has a circular shape.
[0012] As further preferred, at least one concave-convex portion of the attachment portion is a rib, a notch or a stripe.
[0013] In another form of embodiment, the fixing element and the body are obtained from the same overmoulding material.
[0014] According to one aspect of the invention, the body defines at least one opening which passes through said body as far as the fixing element so as to allow the use of an insertion tool for inserting the target into the end of the shaft, allowing the passage of liquid coolant in the case of a "press-fit" type solution for versions of the power unit with liquid coolant, and allowing the use of fixing screws for the body and for the fixing element in the case of a screw-fastened solution.
[0015] Preferably, the teeth are made of stainless steel, aluminium or copper.
[0016] According to another aspect of the invention, the target comprises a plurality of teeth, preferably two, three, four or five teeth, over-moulded in the body.
[0017] Preferably, the teeth are evenly distributed.
[0018] In one form of embodiment, the insertion portion of the fixing element is a sleeve of the “press-fit” type, preferably having an annular groove.
[0019] In another form of embodiment, the insertion portion of the fixation element is a tube with a circular cross section, and the target is configured to be fixed to the shaft using screws.
[0020] According to one aspect of the invention, the body defines at least one opening through the body and the fixing element, for example allowing the passage of liquid coolant in the case of a "press fit" solution for a type of power unit using liquid coolant, or allowing the use of a fixing screw in the case of a screw-fastened solution.
[0021] Preferably, the head of the screw is retained on the target by a retaining member, for example of the locking knurl or notch type, so that the screw is captured.
[0022] Advantageously, the material of the fixing element is magnetically and / or electrically neutral to detection by the sensor.
[0023] It is also advantageous if the material of the fixing element is the same as that of the body, thereby making it possible to reduce the distance between the sensor and the shaft and thus increase compactness.
[0024] The invention also relates to a motor vehicle comprising a drive axle equipped with a target as described above.
[0025] The invention also relates to a method for manufacturing a target as described above, comprising the steps of positioning the at least one metal tooth in a lower part of a mold, placing an upper part of the mold on the lower part, and molding at least a portion of a body around the at least one metal tooth.
[0026] In one embodiment, the method comprises, before placing the upper part of the mould on the lower part, positioning the fixing element in such a way that its attachment portion is moulded into the body. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] Further features and advantages of the present invention will become more clearly apparent when reading the following description. This description is purely illustrative and is to be read with reference to the accompanying drawings, in which:
[0028] [ Figure 1 ] Figure 1 An example of a prior art sensor assembly is schematically illustrated.
[0029] [ Figure 2 ] Figure 2 An example of a vehicle according to the invention is schematically illustrated.
[0030] [ Figure 3 ] Figure 3 is a front perspective view of a first example of a target according to the present invention.
[0031] [ Figure 4 ] Figure 4 yes Figure 3 Rear view of the target.
[0032] [ Figure 5 ] Figure 5 yes Figure 3 Individual stereograms of the fixing elements of the target.
[0033] [ Figure 6 ] Figure 6 is a front perspective view of a second example of a target according to the present invention.
[0034] [ Figure 7 ] Figure 7 yes Figure 6 Rear view of the target.
[0035] [ Figure 8 ] Figure 8 yes Figure 6 Individual stereograms of the fixing elements of the target.
[0036] [ Fig. 9 ] Fig. 9 An embodiment of the method according to the invention is schematically illustrated. DETAILED DESCRIPTION
[0037] Figure 2 A schematic example of a motor vehicle 1 according to the invention is depicted.
[0038] The vehicle 1 comprises a sensor assembly 10 and a rotating shaft 20 (eg a motor shaft), the sensor assembly 10 being designed to measure the rotational speed of the rotating shaft.
[0039] The sensor assembly 10 includes a target 110 , a sensor 120 , and a management module 130 .
[0040] The target 110 is mounted on the free end portion 20A of the rotating shaft 20 .
[0041] The sensor 120 is fixed (ie non-rotating) and mounted in the vehicle 1 in line with the rotating target 110. The sensor 120 is capable of measuring the magnetic field changes caused when the shaft 20 rotates. The sensor 120 comprises, in particular, a sensitive element. Since the sensor 120 itself is known, it will not be described in detail here.
[0042] In this example, the end 20A of the shaft 20 on which the target 110 is mounted includes a hollow cylindrical portion (not visible), such as a tubular portion, allowing the target 110 to be mounted.
[0043] Figures 3 to 8 Two examples of targets 110 according to the present invention are shown.
[0044] The target 110 includes: at least one metal tooth 112 (for example, made of stainless steel, aluminum or copper); a body 114, which is at least partially molded around the at least one tooth 112; and a fixing element 116, which includes an insertion portion 116A, which is configured to be at least partially inserted on or into the hollow cylindrical portion of the end 20A of the shaft 20.
[0045] exist Figures 3 to 8 In both examples, the insertion portion 116A has a hollow cylindrical shape with a circular cross-section.
[0046] exist Figures 3 to 5 In the example of FIG. 1 , the insert portion 116A includes an annular groove 116A1 ( Figure 3 ), which annular groove enables easy installation of the "press fit" type with the circular rib (not visible) of the shaft 20. Figures 6 to 8 In the example of FIG. 1 , the insert portion 116A has an outer surface designed to be push-fit into the hollow cylindrical portion of the end portion 20A of the shaft 20 ( Figure 8 ) and allows screw 117 to pass through the center of the shaft to secure target 110 to shaft 20.
[0047] exist Figures 3 to 5 and Figures 6 to 8 In the two examples shown, the fixing element 116 includes an attachment portion 116B ( Figure 5 ), and the attachment portion is in the form of a ring whose longitudinal axis coincides with the longitudinal axis of the insertion portion. The attachment portion 116B is provided with ribs 116B1 ( Figure 5), these ribs extend along the longitudinal axis of the fixing element 116 and are parallel to each other. In other words, in this non-limiting example, the ring is notched and these notches extend along the longitudinal axis of the fixing element 116 so as to prevent any rotation of the body 114 relative to the fixing element 116 once the attachment portion 116B is overmolded.
[0048] exist Figures 3 to 5 and Figures 6 to 8 In the two examples, the target 110 includes three teeth 112. In other forms of embodiments, the target 110 may include one, two, four, five or more than five teeth 112. Each tooth 112 is made of metal, such as stainless steel, aluminum or copper. Each tooth 112 has an angular cross-sectional shape with a preferred thickness between 0.6 mm and 2 mm.
[0049] The teeth 112 are evenly distributed in a ring shape on the target 110. In the example of the figures, the teeth 112 are identical, but in another form of embodiment, the teeth 112 may have different shapes. Figure 3 In the example of FIG. 1 , each tooth 112 has an angular width of 60°. In another form of embodiment, the angular width of the teeth 112 may have a different value.
[0050] The body 114 is made of a plastic material overmolded onto the teeth 112 and overmolded onto the attachment portion 116B. The body 114 has a circular shape. The spaces 114A between the teeth 112 are partially empty in order to save material during the overmolding process and to reduce the weight of the target, thereby reducing the need for a balancing step. These spaces may or may not be through-going.
[0051] The spaces 114A are defined by hollow shapes that serve to press the teeth 112 tightly against the face of the cavity on the functional face side of the target 110 in order to ensure the correct positioning and overall flatness of the teeth 112. In the context of inductive sensors requiring a high level of precision, this provides a significant advantage over targets produced by deep swaging (or "deep drawing" as the process is known). The spaces 114A also enable the target 110 to be oriented, especially at the moment of press-fit insertion.
[0052] In another form of embodiment (not shown), the body 114 and the fixing element 116 may be obtained from the same overmolding material. In other words, the body 114 and the fixing element 116 may be a one-piece component obtained by injecting the material used to overmold the tooth 112 into a mold.
[0053] The body 114 defines at least one opening 114B that passes through the body 114 as far as the fixing element 116 to allow the use of an insertion tool to insert the target 110 into the end 20A of the shaft 20. When the opening 114B passes through the target 110, this opening can be used in particular to allow liquid coolant to circulate in the shaft 20 of certain types of vehicles 1, and to grip and orient the target 110 when it is inserted (particularly using a press fit).
[0054] refer to Figure 7 The body 114 includes retaining walls 114C which are used to press the teeth tightly against the surface of the cavity on the functional surface side of the target so as to ensure excellent positioning and overall flatness of the teeth 112, which proves to be important for inductive sensors and has significant advantages over prior art targets produced by deep drawing.
[0055] In another form of embodiment (not shown), the end 20A of the shaft 20 may be solid and receive a push-fit or screw-fastened target 110 .
[0056] Example of manufacturing
[0057] In particular, refer to Fig. 9 In the example described, target 110 is manufactured using a two-part mold.
[0058] First, in step E1 , the metal teeth 112 are positioned evenly distributed in the lower part of the mold, against positioning members (for example V-shaped members) of the mold.
[0059] In step E2 , the fixing element 116 is likewise positioned in the lower part of the mold (for example using retaining pins) so that its longitudinal axis is substantially aligned with the axis of the evenly distributed teeth 112 (ie the axis around which the teeth 112 are distributed).
[0060] In step E3 , the upper part of the mold is then placed on the lower part to close the mold, and then in step E4 , the overmolding plastic material is injected into the closed mold, thereby forming the body 114 which is overmolded both on the attachment portion 116B and on all or part of the metal teeth 112 .
[0061] In another manufacturing method in which step E2 is absent, both the body 114 and the fixing element 116 may be formed by injecting material into a mold to form a one-piece component having the desired shape.
[0062] When the teeth are pre-positioned in the lower cavity of the mold, substantially offset from the axis to make it easier to insert these teeth into the tool, the amount by which the teeth 112 are offset from the center when positioned in the mold can be defined by the size of the mold cone. Thus, a relatively large cone size means that the tooth 112 can be comfortably kept at a distance from its V, making it easier to pre-insert and then into its final position. When the mold is closed, the molding cavity in the upper part of the mold slides via its cone over a portion of the edge angle on the large diameter side of the tooth 112 (this edge angle relates to the face opposite to the functional face of the target 110) until a point that slightly blunts this (non-functional) edge angle, so that the side surface of each tooth 112 is in contact therewith and is thus positioned on the V-shaped bearing face of the mold, thereby ensuring a good positioning of the tooth 112 relative to the axis of the shaft 20, and doing so with very good repeatability. This positioning is important, especially in terms of induction technology. This method makes it possible to avoid damaging the functional edge angles of the teeth 112, which are preferably sharp edges around the functional faces.
[0063] The target 110 according to the invention makes it possible to achieve a precise positioning of each tooth 112 relative to the sensor 120 along the axis of the shaft 20 and in two other directions.
[0064] During the press-fit mounting of the target 110 on the end of the shaft, an insertion tool (not depicted but known per se) abuts against the fixing element 116 and then allows a push-fit without damaging the plastic part of the target 110 .
Claims
1. A target (110) for an axle (20) of a motor vehicle (1), the target (110) being configured to be mounted on a free end (20A) of the axle (20) and comprising at least one metal tooth (112); a body (114) supporting the at least one metal tooth (112); and a fixing element (116) comprising an insert portion (116A) configured to be at least partially mounted on the end (20A) of the axle (20), the body (114) being at least partially overmolded around the at least one tooth (112), the target being a target wherein: The body (114) includes a retaining wall (114C) for tightly pressing the at least one tooth against the surface of the cavity on the functional surface side of the target so as to ensure the flatness of the at least one tooth (112).
2. The target (110) of claim 1, wherein: The fixing element (116) comprises an attachment portion (116B) which is different from the insertion portion (116A) and is provided with at least one relief (116B1), and the body (114) is overmolded around the attachment portion (116B).
3. The target (110) of claim 2, wherein: The attachment portion (116B) has a circular shape.
4. The target (110) according to any one of claims 2 or 3, wherein: At least one concavo-convex portion (116B1) of the attachment portion (116B) is a rib, a notch or a stripe.
5. The target (110) of claim 1, wherein: The fixing element (116) and the body (114) are obtained from the same overmolding material.
6. The target (110) according to any one of the preceding claims, wherein: The body (114) defines at least one opening (114B) through the body (114) distal to the fixing element (116) to allow the target (110) to be inserted into the end (20A) of the shaft (20) using an insertion tool.
7. The target (110) according to any of the preceding claims, comprising a plurality of teeth (112), preferably two, three, four or five teeth (112), overmolded in the body (114).
8. A target (110) as claimed in the preceding claim, wherein: The teeth (112) are evenly distributed.
9. A motor vehicle (1) comprising a drive shaft (20) provided with a target (110) as claimed in any one of the preceding claims.
10. A method for manufacturing a target (110) according to any one of claims 1 to 8, the method comprising the following steps: The at least one metal tooth (112) is positioned in a lower portion of a mold, an upper portion of the mold is placed on the lower portion, and at least a portion of the body (114) is molded around the at least one metal tooth (112).