A printed circuit board assembly for a wheel speed sensor unit

Abstract

A printed circuit board assembly (100) for a wheel speed sensor unit (125) is disclosed. The printed circuit board assembly (100) includes a curved rectangular printed circuit board (PCB) (105) disposed in between a housing (155) and a spacer shaft (160) of the wheel speed sensor unit (125). The curved rectangular PCB (105) includes a circular through hole (115). The printed circuit board assembly (100) includes a circular magnet (110) fixed inside the circular through hole (115) of the curved rectangular PCB (105). The printed circuit board assembly (100) includes a sensor (120) mounted on the curved rectangular PCB (105). The sensor (120) is mounted proximate and coaxial to the circular magnet (110).

Description

202400192TITLEA PRINTED CIRCUIT BOARD ASSEMBLY FOR A WHEEL SPEED SENSOR UNITThe following specification particularly describes the nature of this invention and the manner in which it is to be performed.FIELD OF THE INVENTION:

[0001] The present disclosure relates to a wheel speed sensor unit, and in particular, to a printed circuit board assembly used in a wheel speed sensor unit.BACKGROUND TO THE INVENTION:

[0002] A wheel speed sensor unit is used to measure speed of a front wheel and a rear wheel of a vehicle, for example an electric scooter or an internal combustion engine (ICE) motor bike. Typically, the wheel speed sensor unit is implemented in vehicles having anti-lock braking system (ABS). By measuring the front wheel speed and the rear wheel speed, the ABS avoids wheel locking and slip of the vehicle. A wheel speed sensor unit includes a sensing element, a cable, and a connector. Typically, the wheel speed sensor unit uses a hall sensor to sense the wheel speed. The sensing element is positioned adjacent to the bearing on the wheel shaft to sense the rotation of the shaft and determine the wheel speed.

[0003] The wheel speed sensor unit includes a printed circuit board (PCB) assembly. A current sensor is attached to the PCB assembly. Further, a magnet is placed behind the current sensor. Typically, the magnet is molded over the sensor. It is to be noted that there is no specific location or position meant for fixing the magnet on the PCB. This leads to non-uniform manufacturing process of the PCB assembly. Further, the magnet is not placed coaxial to the sensor. Since the magnet and the sensor are not coaxial, there is insufficient flux to sense by the sensor, leading to erroneous sensor reading. Furthermore, the PCB extends in a 360 degreefashion along the circular wheel shaft. Having 360 degree PCB consumes excess space in the wheel speed sensor unit.

[0004] There is a need for a compact PCB assembly that has provision for better flux density to pass through so that the sensor in a wheel speed sensor unit can sense the wheel speed accurately.SUMMARY OF THE INVENTION:

[0005] This summary is provided to introduce a selection of concepts in a simple manner that is further described in the detailed description of the disclosure. This summary is not intended to identify key or essential inventive concepts of the subject matter nor is it intended for determining the scope of the disclosure.

[0006] An objective of the present disclosure is to provide a compact PCB assembly that has provision for better flux density to pass through so that the sensor in a wheel speed sensor unit can sense the wheel speed accurately.

[0007] Accordingly, a printed circuit board assembly for a wheel speed sensor unit is disclosed. The printed circuit board assembly includes a curved rectangular printed circuit board (PCB) disposed in between a housing and a spacer shaft of the wheel speed sensor unit. The curved rectangular PCB includes a circular through hole. The printed circuit board assembly includes a circular magnet fixed inside the circular through hole of the curved rectangular PCB. The printed circuit board assembly includes a sensor mounted on the curved rectangular PCB. The sensor is mounted proximate and coaxial to the circular magnet.

[0008] To further clarify advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof, which is illustrated in the appended figures. It is to be appreciated that these figures depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. The invention will bedescribed and explained with additional specificity and detail with the accompanying figures.BRIEF DESCRIPTION OF THE FIGURES:

[0009] The invention will be described and explained with additional specificity and detail with the accompanying figures in which:

[0010] Figure 1A illustrates a perspective exploded view of a printed circuit board assembly of a wheel speed sensor unit, in accordance with an embodiment of the present disclosure;

[0011] Figure IB illustrates a perspective exploded view of the wheel speed sensor unit, in accordance with an embodiment of the present disclosure;

[0012] Figure 1C illustrates a side sectional view of the wheel speed sensor unit, in accordance with an embodiment of the present disclosure;

[0013] Figure ID illustrates a front sectional view of a curved rectangular printed circuit board of the printed circuit board assembly, in accordance with an embodiment of the present disclosure; and

[0014] Figures 2A and 2B illustrate a side perspective view of the curved rectangular printed circuit board of the printed circuit board assembly, in accordance with an embodiment of the present disclosure.

[0015] Further, skilled artisans will appreciate that elements in the figures are illustrated for simplicity and may not have been necessarily drawn to scale. Furthermore, in terms of the construction of the system, one or more components of the system may have been represented in the figures by conventional symbols, and the figures may show only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the figures with details that will be readily apparent to those of ordinary skill in the art having benefit of the description herein.DESCRIPTION OF THE INVENTION:

[0016] For the purpose of promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the figures and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated system, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates.

[0017] It will be understood by those skilled in the art that the foregoing general description and the following detailed description are exemplary and explanatory of the invention and are not intended to be restrictive thereof.

[0018] In the present disclosure, relational terms such as first and second, and the like, may be used to distinguish one entity from the other, without necessarily implying any actual relationship or order between such entities.

[0019] The terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process or method that comprises a list of steps does not include only those steps but may include other steps not expressly listed or inherent to such process or method. Similarly, one or more devices or sub-systems or elements or structures or components proceeded by "comprises... a" does not, without more constraints, preclude the existence of other devices or other sub-systems or other elements or other structures or other components or additional devices or additional sub-systems or additional elements or additional structures or additional components. Appearances of the phrase “in an embodiment,” “in another embodiment” and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the artto which this invention belongs. The system, methods, and examples provided herein are illustrative only and not intended to be limiting.

[0021] Embodiments of the present disclosure includes a printed circuit board assembly of a wheel speed sensor unit.

[0022] Figure 1A illustrates a perspective exploded view of a printed circuit board assembly (100) of a wheel speed sensor unit (125), in accordance with an embodiment of the present disclosure. The printed circuit board assembly (100) for a wheel speed sensor unit (125) includes a curved rectangular printed circuit board (PCB) (105) disposed in between a housing (155) and a spacer shaft (160) of the wheel speed sensor unit (125) as illustrated in Figure IB. The curved rectangular PCB (105), also called as quadrature PCB, includes a circular through hole (115). The printed circuit board assembly (100) includes a circular magnet (110) fixed inside the circular through hole (115) of the curved rectangular PCB (105). Figure ID illustrates a front sectional view of the curved rectangular printed circuit board (105) and the circular through hole (115). Figures 2A and 2B illustrate a side perspective view of the curved rectangular printed circuit board (105) and the circular through hole (115) of the printed circuit board assembly (100).

[0023] The printed circuit board assembly (100) includes a sensor (120) mounted on the curved rectangular PCB (105). The sensor (120) is mounted proximate and coaxial to the circular magnet (110). The mounting of the sensor (120) proximate and coaxial to the circular magnet (110) increases the magnetic flux density. In one embodiment, the circular magnet (110) is a circular neodymium magnet. The circular magnet (110) can be any magnet having circular shape that can be fitted into the circular through hole (115).

[0024] The printed circuit board assembly (100) includes a space between the housing (155) and the spacer shaft (160). The space between the housing (155) and the spacer shaft (160) of the wheel speed sensor unit (125) is filled with epoxy material. The epoxy material prevents ingress of contaminants and water. Theepoxy material holds the printed circuit board assembly (100) in position. In one embodiment, a plastic molding is done instead of epoxy filling.

[0025] Figure IB illustrates a perspective exploded view of the wheel speed sensor unit (125), in accordance with an embodiment of the present disclosure. The wheel speed sensor unit (125) includes a seal (130), the housing (155), and the spacer shaft (160). The seal (130) is mounted on the housing (155). The spacer shaft (140) has a knurling on the outer diameter, this helps to fix the housing position accurately by overmolding process. The housing (155), the spacer shaft (160), and the PCB (155) together forms the wheel speed sensor body.

[0026] The wheel speed sensor unit (125) includes a sensor cable (145). The wheel speed sensor unit (125) includes a sensor connector (150). The sensor cable (145) transmits the sensed speed to a controller. The wheel speed sensor unit (125) includes an impulse ring (135). The impulse ring (135) is coupled to a bearing (140) as illustrated in Figure 1C.

[0027] The impulse ring (135) is a sheet metal consisting of a number of slots. The PCB assembly (100) includes the sensor (120) for sensing the wheel speed. Typically, the sensor (120) is a hall effect sensor. When the outer ring of the bearing (140) rotates, the impulse ring (135) rotates past the sensor (120) designed to respond to the magnetic field variation generated by each change in polarity. The sensor (120) then supplies a signal whose frequency is a function of the number of polarity changes per second. It is thus possible to measure the rotational movement of one ring relative to the other. Typically, the impulse ring (135) is a sheet metal attached to the outer ring of the bearing (140).

[0028] In the present disclosure, the PCB (105) is a circular curved PCB unlike the 360 degree PCB in existing wheel speed sensor units. The circular curved PCB (105) is also known as quadrature PCB. In the present disclosure, there is a single slot or through hole for the circular magnet (110). The sensor (120) includes two lugs to mount on the PCB assembly (100). The sensor (120) with the two lugs will be soldered to the PCB assembly (100).

[0029] There are many advantages of the printed circuit board assembly (100). The printed circuit board assembly (100) is a compact PCB assembly that enable better flux density to pass through so that the sensor (120) in the wheel speed sensor unit (125) can sense the wheel speed accurately. Further, the printed circuit board assembly (100) provides provision for fixing the circular magnet (110). Having a fixed position for the circular magnet (110) helps in uniform manufacturing process of the PCB assembly (100). Further, the circular magnet (110) is placed coaxial to the sensor (120). Since the circular magnet (110) and the sensor (120) are coaxial, there is sufficient flux to sense, leading to accurate sensor reading. Furthermore, the PCB (105) has a compact shape, i.e., a curved rectangular shape. The curved rectangular shaped PCB (105) consumes less space in the wheel speed sensor unit (125).

[0030] While specific language has been used to describe the disclosure, any limitations arising on account of the same are not intended. As would be apparent to a person skilled in the art, various working modifications may be made to the method in order to implement the inventive concept as taught herein.

[0031] The figures and the foregoing description give examples of embodiments. Those skilled in the art will appreciate that one or more of the described elements may well be combined into a single functional element. Alternatively, certain elements may be split into multiple functional elements. Elements from one embodiment may be added to another embodiment. For example, orders of processes described herein may be changed and are not limited to the manner described herein. Moreover, the actions of any flow diagram need not be implemented in the order shown; nor do all of the acts necessarily need to be performed. Also, those acts that are not dependent on other acts may be performed in parallel with the other acts. The scope of embodiments is by no means limited by these specific examples. Numerous variations, whether explicitly given in the specification or not, such as differences in structure, dimension, and use of material, are possible. The scope of embodiments is at least as broad as given by the following claims.

Claims

WE CLAIM:

1. A printed circuit board assembly (100) for a wheel speed sensor unit (125), the printed circuit board assembly (100) comprising:a curved rectangular printed circuit board (PCB) (105) disposed in between a housing (155) and a spacer shaft (160) of the wheel speed sensor unit (125), wherein the curved rectangular PCB (105) comprises a circular through hole (115);a circular magnet (110) fixed inside the circular through hole (115) of the curved rectangular PCB (105); anda sensor (120) mounted on the curved rectangular PCB (105), wherein the sensor (120) is mounted proximate and coaxial to the circular magnet (HO).

2. The printed circuit board assembly (100) as claimed in claim 1, wherein mounting the sensor (120) proximate and coaxial to the circular magnet (110) increases the magnetic flux density.

3. The printed circuit board assembly (100) as claimed in claim 1, wherein the circular magnet (110) is a circular neodymium magnet.

4. The printed circuit board assembly (100) as claimed in claim 1, wherein a space between the housing (155) and the spacer shaft (160) of the wheel speed sensor unit (125) is filled with epoxy material.

5. The printed circuit board assembly (100) as claimed in claim 4, wherein the epoxy material prevents ingress of contaminants and water.

6. The printed circuit board assembly (100) as claimed in claim 4, wherein the epoxy material holds the printed circuit board assembly (100) in position.

7. The printed circuit board assembly (100) as claimed in claim 1, whererin the wheel speed sensor unit (125) comprises:a seal (130) mounted on the housing (155);an impulse ring (135);a sensor cable (145); anda sensor connector (150).

8. The printed circuit board assembly (100) as claimed in claim 7, wherein the impulse ring (135) is coupled to a bearing (140).

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