WO2020020912A1

WO2020020912A1 - A disc brake and a sensor device

Info

Publication number: WO2020020912A1
Application number: PCT/EP2019/069845
Authority: WO
Inventors: Alvin Jason CHEN; Zenglai SONG; Anders Lindqvist; Anders Nilsson
Original assignee: Haldex Vie (Shanghai) Electromechanical Brake System Co., Ltd.; Haldex Brake Products Aktiebolag
Priority date: 2018-07-25
Filing date: 2019-07-23
Publication date: 2020-01-30
Also published as: CN110762144B; CN110762144A; DE112019003731T5

Abstract

The present invention discloses a vehicle disc brake and a wear sensor device (100) configured in the disc brake. The vehicle disc brake comprises a brake force transmission unit accommodated inside a disc brake housing (16) for converting rotation of a motor shaft into linear motion of a thrust plate. The sensor device (100) measures the travel distance of the thrust plate, wherein the sensor device (100) comprises a magnetic element driving unit (165) for converting rotation of the brake force transmission unit into motion of a magnetic element (160).

Description

A DISC BRAKE AND A SENSOR DEVICE

TECHNICAL FIELD OF THE INVENTION

The present invention relates to the field of brake systems for vehicles, and more particularly to a disc brake and a wear sensor device configured in the disc brake and/or attached to the disc brake.

BACKGROUND OF THE INVENTION

Disc brakes are widely used in brake vehicles. For braking a vehicle, two brake pads are pressed against a brake disc by a thrust plate installed in the disc brake to generate a braking force. In this regard, the brake pads and the brake disc are subject to wear within a disc brake, and the brake pads have a friction material contacting with the surface of the brake disc. The brake disc is usually made of a ferrous material. With every use, the brake pads and the brake disc lose material, and over time, wear affects braking performance and safety. The wear rate of the disc brake will vary based on various factors, such as the properties of the friction material of the brake pad, the amount and type of braking, etc. Therefore, it is desirable to obtain information on the wear condition in order to ensure the normal operation of the vehicle brake system. There are various conventional solutions for obtaining information on the wear condition, but these conventional solutions have various drawbacks. For example, the wear condition of a brake pad can be obtained by directly measuring the thickness of the brake pad via a potentiometer and a spring. However, over time, this method of measurement can fail due to vehicle vibration. Alternatively, brake pad wear might be measured by, e.g., arranging a wire or circuit that will be destroyed after the brake pad is worn to a certain extent so as to give a digital signal that a brake pad thickness threshold has been reached. However, this method of measuring the thickness of a brake pad only gives a binary signal when the critical threshold is reached and cannot serve to monitor the thickness of the brake pad over time. Therefore, there is a need to provide an improved technical solution which can measure the wear condition.

OBJECT OF THE INVENTION It is in particular the object of the present invention to provide a vehicle disc brake with a sensor device allowing a monitoring of the operation of the disc brake and/or the wear in the disc brake, the vehicle disc brake in particular being improved with respect to the constructional space,

the precision of monitoring the operation of the disc brake and/or

the precision of monitoring the wear in the disc brake.

SOLUTION

According to the present invention, the object of the invention is solved by the features of the independent claims. Additional preferred embodiments according to the invention are to be seen in the dependent claims.

DESCRIPTION OF THE INVENTION

To overcome the drawbacks of conventional solutions, the present invention provides a disc brake including a sensor device which can timely and reliably measure the wear condition of the disc brake.

In an aspect of the invention, a vehicle disc brake is provided. The disc brake may comprise a disc brake housing, a motor having a shaft, a thrust plate, and a brake force transmission unit accommodated inside the disc brake housing for converting rotation of the motor shaft into linear motion of the thrust plate, the vehicle disc brake further comprising a sensor device for measuring the travel distance of the thrust plate, wherein the sensor device comprises a magnetic element driving unit (in particular comprising a sensor transmission unit) for converting (which also covers transmitting) rotation of the brake force transmission unit into motion of at least one magnetic element. In an aspect of the invention, the brake force transmission unit may comprise a rotating element driven by the motor and threaded with the thrust plate. The rotating element may comprise, e.g., a screw or a ring attached to the screw.

In an aspect according to any embodiment described herein, the sensor device may further comprise a sensing element. In an aspect, the sensing element can be configured to measure the linear moving distance and/or rotation angle of the magnetic element.

In an aspect, the sensor device described herein may comprise a sensor body, and one or more sensor transmission units and/or transmission units. In an aspect, the sensor body may comprise a housing that may house the magnetic element driving unit, the magnetic element, and the sensing element.

In an aspect, the one or more transmission units may comprise an axial transmission unit configured for transmitting rotation motion from the brake force transmission unit to the magnetic element driving unit. The axial transmission unit may, e.g., comprise a shaft or rod configured to engage with the rotating element of the brake force transmission unit, e.g., a screw or ring attached to the screw. The axial transmission unit may engage with the rotating element of the brake force transmission unit via, for example, a toothed mesh with a ring gear, or frictional engagement with a rubber ring.

The vehicle disc brake according to any embodiment described herein may be configured such that the one or more transmission units are configured for radial or non-radial transmission of rotation from the sensor axial transmission unit to the magnetic element driving unit. For example, the vehicle disc brake may comprise a radial transmission unit, such as a toothed belt, for transmitting rotation motion from the axial transmission unit to the magnetic element driving unit. The axial transmission unit may comprise a gear configured to mesh with the radial transmission unit, and the magnetic element driving unit may comprise a driving gear configured to mesh with the radial transmission unit.

Preferably, the transmission unit serves for the following alternative or cumulative functions: a) It is possible that the transmission unit has a transmission ratio that increases or decreases the rotation of the rotating element, the ring, shaft or rod or of the brake force transmission unit to the movement in particular of the driving gear of the sensor device. b) Furthermore, it is possible that the transmission unit transfers the movement of the rotating element, the ring, the rod or the shaft or of the brake force transmission unit or of any other component moving therewith (so the movement at a first location) to the movement of a gear or of the driving gear of the sensor device (so a movement at a second location) such that the transmission unit is able to compensate or bridge an offset between these locations which might be an axial and/or radial offset. c) It is also possible that the transmission unit converts a first motion type into a second motion type, e.g. a rotary motion into a translatory motion and/or a rotation about a first axis into a rotation about a second axis and/or a movement along a first axis into a movement along a second axis.

It is e.g. possible that the transmission unit is an axial transmission unit, wherein a rotating shaft transmits the movement of the brake force transmission unit inside the brake housing to the outside of the same and/or the sensor transmission unit is radial transmission unit which comprises a toothed belt or at least two meshing gears that transmits or transmit the rotation about a first axis to a rotation about a second parallel axis.

The vehicle disc brake according to any embodiment described herein may comprise an axial transmission unit that includes a gear configured to mesh with the magnetic element driving unit, and the magnetic element driving unit may comprise a driving gear configured to mesh with the gear of the axial transmission unit.

In an aspect according to any embodiment described herein, the magnetic element driving unit may further comprise a driven screw. The magnetic element may be mounted on the driven screw. In an aspect according to an embodiment described herein, the magnetic element driving unit comprises a driving gear, and wherein the magnetic element is mounted to the driven screw and rotates with it. However, within the frame of the invention the magnetic element might also be mounted to the driving gear. In an aspect according to any embodiment of the vehicle disc brake described herein, the disc brake may further comprise a brake disc and a brake pad, wherein the rotating element of the brake force transmission unit is configured to rotate to allow the thrust plate to move toward and away from the brake disc, and the one or more sensor transmission units and/or transmission unit(s) are configured to drive the magnetic element to motion by a predetermined ratio of the distance that the thrust plate travels to press the brake pad against and/or release from the brake disc, such that a linear moving distance or rotation angle of the magnetic element is consistent with a distance of axial travel of the thrust plate by the predetermined ratio.

In an aspect according to any embodiment of the vehicle disc brake described herein, the sensing element may be configured to measure the motion of the magnetic element. In some embodiments, the sensing element may be configured to measure the motion of the magnetic element based on the change of the magnetic flux caused by movement of the magnetic element.

In an aspect according to any embodiment of the vehicle disc brake described herein, the sensor device may comprise a fixing plate for fixing the sensor housing to the disc brake housing. The sensor housing may be mounted to an outer surface of the disc brake housing such that the sensor housing is fixed outside of the disc brake housing or may be fixed inside of the disc brake housing and/or in a pocket defined by the disc brake housing.

In an aspect of the invention according to all embodiments described herein, a vehicle is provided, wherein the vehicle comprises a vehicle disc brake as described herein. By providing the vehicle disc brake as described herein, the present invention can provide simple and easy installation, repair, and maintenance of the sensor device and the vehicle disc brake, and provide a compact structure and design freedom for the sensor device and vehicle disc brake. In addition, the sensor device of the present invention uses a non-contact sensing element, which is not influenced by the vibration caused by operation of the vehicle. Thus, the sensor device described herein can avoid the disadvantages of prior devices, such as measurement failure or measurement inaccuracy caused by vibration when the vehicle is operated. Further, the sensor device described herein can provide real time feedback of wear of a disc brake, and is not limited to a single threshold, critical value warning of wear. Advantageous developments of the invention result from the claims, the description and the drawings.

The advantages of features and of combinations of a plurality of features mentioned at the beginning of the description only serve as examples and may be used alternatively or cumulatively without the necessity of embodiments according to the invention having to obtain these advantages.

The following applies with respect to the disclosure - not the scope of protection - of the original application and the patent: Further features may be taken from the drawings, in particular from the illustrated designs and the dimensions of a plurality of components with respect to one another as well as from their relative arrangement and their operative connection. The combination of features of different embodiments of the invention or of features of different claims independent of the chosen references of the claims is also possible, and it is motivated herewith. This also relates to features which are illustrated in separate drawings, or which are mentioned when describing them. These features may also be combined with features of different claims. Furthermore, it is possible that further embodiments of the invention do not have the features mentioned in the claims which, however, does not apply to the independent claims of the granted patent.

The number of the features mentioned in the claims and in the description is to be understood to cover this exact number and a greater number than the mentioned number without having to explicitly use the adverb "at least". For example, if an element is mentioned, this is to be understood such that there is exactly one element or there are two elements or more elements. Additional features may be added to these features, or these features may be the only features of the respective product.

The reference signs contained in the claims are not limiting the extent of the matter protected by the claims. Their sole function is to make the claims easier to understand. BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings in which like reference numerals refer to similar elements and in which:

Fig. 1 is a schematic partial structural sectional view of a disc brake comprising a sensor device.

Fig. 2 is a schematic partial structural sectional view of a disc brake comprising a sensor device and connected to a motor.

Fig. 3 is a schematic structural sectional view of a sensor device.

Fig. 4 is a schematic structural sectional view of a sensor device configured to be accommodated in a pocket inside a disc brake housing.

Fig. 5 is a schematic structural sectional view of a sensor device configured to transmit a rotation of an axial transmission unit directly to a magnetic element driving unit.

Fig. 6 is a schematic structural sectional view of a sensor device according to another embodiment in which two magnetic elements are used.

Fig. 7 is a schematic structural sectional view of a sensor device according to another embodiment in which a magnetic element is directly mounted on a driving gear.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The present invention will now be described in detail with reference to some embodiments thereof as illustrated in the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art, that the present invention may be practiced without some or all of these specific details. In other instances, well known process steps and/or structures have not been described in detail in order to not unnecessarily obscure the present invention. In addition, in the detailed description of the embodiments, directional terminology, such as "above", "below”, "top", "bottom", "front", "rear", "side", "left", "right", "forward", "trailing", etc., is configured with reference to the orientation of the Figure(s) being described. Because components of embodiments of present invention can be positioned in a number of different orientations, the directional terminology is configured for purposes of illustration and is in no way limiting.

Referring to Figs. 1 -5, Fig. 1 is a partial structural sectional view of an exemplary vehicle disc brake 10 including a sensor device 100 according to the present invention. The vehicle disc brake

10 includes a disc brake housing 16, a motor 5 with a motor shaft 6 (only schematically indicated by a box in Fig. 2), a thrust plate 1 1 , and a brake force transmission unit 13. A pair of brake pads 200 may be attached to or biased towards a brake disc 201 by the thrust plate 1 1. The brake pad or pads 200 may be made of any suitable material, and may be placed between the thrust plate

1 1 and the brake disc 201 by any suitable means.

The brake force transmission unit 13 is configured to drive the thrust plate 11 towards and away from a brake disc 201 , so that the one or more brake pads 200 may be pressed against the brake disc 201 or move away from the brake disc 201. In an exemplary embodiment, the brake force transmission unit 13 is configured for converting rotation of the motor shaft 6 into linear motion of the thrust plate 1 1. The brake force transmission unit 13 may, for example, comprise a rotating element 14 driven directly or indirectly (e.g. via a planetary gear set) by the motor 5. For the shown embodiment the brake force transmission unit 13 is a screw drive or spindle drive wherein a screw 15 which is driven directly or indirectly (e.g. via a planetary gear set) by the motor 5 is threaded with the thrust plate 1 1. Here, the thrust plate 1 1 is fixed against rotation. A ring 1 1 1 may be attached to the rotating element 14, in particular to the screw 15 (where the ring 1 11 can be attached externally to an outer circumference of the screw 15). It is e.g. possible that the ring 1 11 is internally attached to the rotating element 14 or screw 15, in particular by attaching the ring 11 1 to a recess 17 of the rotating element 14 or screw 15.

According to the present invention, as shown in Figs. 1-5, the sensor device 100 included in the vehicle disc brake 10 is configured to measure the travel distance of the thrust plate 11 using non- contact sensing elements, so as to reliably monitor and measure the wear of the brake disc 10 and the brake pad(s) 200 attached to thrust plate 1 1. Specifically, every use will make brake pads 200 and the brake disc 201 lose material, and over time the thrust plate 1 1 will operate further from its starting position in order to press the remaining material of a brake pad 200 against the brake disc 201. By measuring the rotation angle of the rotating element 14, and considering the parameters of the transmission thread between the rotating element 14 and the thrust plate 11 , the moving distance of the thrust plate 1 1 in the vehicle disc brake 10 can be calculated and obtained. The sensor device 100 described herein can provide a precise and/or continuous measurement of wear condition of a disc brake 10.

The sensor device 100 of the present invention comprises a magnetic element driving unit 165 for converting the rotation of the brake force transmission unit 13 or of a driving gear of the sensor device into a preferably linear motion of a magnetic element 160. Referring to Figs. 1-5, in one or more exemplary embodiments, the magnetic element driving unit 165 of the sensor device 100 may, for example, be part of a sensor body 101. The sensor body 101 may further include the magnetic element 160, a sensing element 170, and a sensor housing 190 for housing the magnetic element driving unit 165, the magnetic element 160, and the sensing element 170. The magnetic element driving unit 165 is configured to drive the magnetic element 160 to motion when the brake rotating element 14 in the brake force transmission unit 13 rotates. For example, a rotary motion to linear motion converting sensor transmission unit 175 may comprise a driving gear 132 and a driven screw 140 screwed with the driving gear but fixed against rotation (forming a screw drive), and the magnetic element 160, such as a magnet, may be mounted to the driven screw 140 to convert the rotational motion of the driving gear 132 into a linear motion of the driven screw 140, thereby driving the magnetic element 160 to also move linearly. The sensing element 170, such as a hall sensor, is configured to measure the moving distance of the magnetic element

160 according to the change of the magnetic flux caused by the movement of the magnetic element 160.

In any embodiment, the driven screw 140 may comprise a rotational lock engaged with the sensor housing 190 such that the driven screw 140 does not rotate along with the driving gear 132. Instead, the driven screw 140 moves linearly. Preferably, the driving gear 132 and the driven screw 140 form a screw drive. The rotational lock can be configured as an anti-rotation pin 195 that can be inserted and guided in the sensor housing 190. Alternatively, the driven screw 140 can be configured to have a tab that engages with the sensor housing 190.

As can be understood from the embodiments of the present invention, due to its driving connection with the rotating element 14 or ring 1 1 1 of the brake force transmission unit 13, the driving gear 132 of the sensor transmission unit 175 of the sensor device 100 rotates when the rotating element 14 or ring 1 11 in the brake force transmission unit 13 rotates. Meanwhile, the sensor transmission unit 175 transmit the rotational movement of the driving gear 132 to the driven screw 140 in the magnetic element driving unit 165. In operation, when the driving gear 132 rotates, the magnetic element 160 moves linearly under the action of the intermeshing threads of the driving gear 132, the driven screw 140, and the limit of rotational lock.

The number of magnetic elements 160 is not limited to one, and may be other numbers. For example, in the embodiment of FIG. 6, two magnetic elements 160 are shown. The use of two magnetic elements 160 can further improve the detection accuracy and detection range.

In one embodiment, referring to FIG. 7, the magnetic element driving unit 165 might comprise a driving gear 132 directly containing or holding the magnetic element 160. For example, the magnetic element 160 can be mounted to the driving gear 132 and rotate with it, without having a driven screw 140. The magnetic element 160 such as a magnet can take the form of a diametrically polarized disc, for sensing a hall effect. In addition, the driving gear 132 can also interact with a rotary reduction, such as a planetary gear train on which a magnet is mounted, to further reduce or increase the magnet element’s rotational output. A sensing element 170, such as a hall sensor, can be mounted on a PCB in a parallel or vertical plane to the disc, and can be supported on the sensor housing 190.

In exemplary embodiments as shown in Figs. 3-5, the sensor device 100 further comprises at least one transmission unit 177, here an axial transmission unit 176 and a radial transmission unit 120. By the axial transmission unit 176 the rotational movement of the rotating element 14 is reduced or increased according to the transmission ratio of the axial transmission unit 176 and/or the movement is transferred in axial direction, in particular from the inside of the disc brake housing 16 to the outside of the disc brake housing 16. By the radial transmission unit 120 the rotational movement is reduced or increased according to the transmission ratio of the radial transmission unit 120 and/or the axis of rotation is transferred to a parallel axis of rotation. The axial transmission unit 176 and the radial transmission unit 120 are interposed in mechanical series connection between the rotating element 14 and the magnetic element driving unit 165. The transmission units 177 are configured for transmitting the rotational motion of the rotating element 14 of the brake force transmission unit 13 to the magnetic element driving unit 165 housed in the sensor housing 190. The axial transmission unit 176 may, for example, be a shaft or rod 1 13 configured to engage with the rotating element 14 (e.g. the screwl 5) in the brake force transmission unit 13 or the ring 1 11 attached to the rotating element 14 or screw 15. The shaft or rod 113 may, for example, mesh with an internal or external gear of the rotating element 14, or the shaft or rod 1 13 may mesh with an internal or external gear of ring 1 11 attached to the rotating element 14 or screw 15. Alternatively, the ring 1 11 may be a synchronous ring without teeth, made of a material suitable for a synchronous ring, such as rubber, and the shaft or rod 1 13 may be configured to engage with the ring 1 11 via a frictional engagement without teeth. By the shaft or rod 1 13 the movement inside the brake housing 16 is transmitted to the outside through the axial transmission unit 176, and the length and end size of the shaft or rod 113 can be freely designed to facilitate engagement with the inner or outer diameter of various rotating parts inside the housing 16 without requiring additionally leaving space beforehand, thus making the overall structure of the disc brake 10 more compact.

The vehicle disc brake 10 according to the present invention can be configured to transmit rotation of the axial transmission unit 176 to the magnetic element driving unit 165 via radial transmission unit 120. For example, as shown in Figs. 1-4, the vehicle disc brake 10 of the present invention may further comprise a radial transmission unit 120 for transmitting rotation of the axial transmission unit 176 to the magnetic element driving unit 165. In the exemplary embodiments of FIGs 1-4, the axial transmission unit 176 comprises a gear 131 configured to mesh with the radial transmission unit 120, and the rotary to linear sensor transmission unit 175 comprises the driving gear 132 configured to mesh with the radial transmission unit 120. In these embodiments, the radial transmission unit 120 may, for example, be a toothed belt. In the case where the radial transmission unit 120 is used, the mounting position of the sensor body 101 on the housing 16 can be freely selected, thereby avoiding disadvantageous positions and further enhancing the degree of design freedom.

Alternatively, the vehicle disc brake 10 according to the present invention can be configured to directly transmit rotation of the axial transmission unit 176 to the magnetic element driving unit 165. For example, as shown in Fig. 5, the axial transmission unit 176 may include a gear 131 configured to directly engage with a driving gear 132 of the magnetic element driving unit 165. In an aspect according to any embodiment described herein, the sensing element 170 is mounted near the magnetic element 160, e.g., attached to a printed circuit board 185. In an aspect, the sensing element 170 may be mounted on the housing 190 and in the magnetic field of the magnetic element 160. The driving gear 132, the driven screw 140, the magnetic element 160, and the sensing element 170 in the sensor device 100 may all be disposed within the sensor housing 190. A change in the position of the magnetic element 160 causes the magnetic flux to change. The sensing element 170 can measure the position of the magnet 160 based on the changing magnetic flux.

In the embodiment shown in Fig. 7 in which the magnetic element 160 is directly mounted on the driving gear 132, the sensing element 170 is also mounted near the magnetic element 160, e.g., attached to a printed circuit board 185. In an aspect, the sensing element 170 may be mounted on the sensor housing 190 and in the magnetic field of the magnetic element 160. The driving gear 132, the magnetic element 160, and the sensing element 170 in the sensor device 100 may all be disposed within the housing 190. The rotation of the magnetic element 160 causes its magnetic field to also rotate with the magnetic element 160. The sensing element 170 can measure the amount of change in the rotation angle of the magnetic element 160 based on the change in the magnetic flux caused by the rotation of the magnetic field of the magnetic element 160.

The sensor device 100 described herein may be configured for measuring the wear condition of a disc brake 10. In the absence of a braking demand, the thrust plate 1 1 needs to maintain an appropriate distance from the brake disc 201 to avoid unnecessary friction between the brake pad 200 and the brake disc 201 during normal running of the vehicle. The distance is herein called brake clearance BC. In braking, as shown in Fig. 1 , a brake force transmission unit 13 drives the thrust plate 1 1 to move brake pads 200 towards the brake disc 201 so as to eliminate the brake clearance, and thereby a braking effect can be achieved. In this regard, with the use over a period of time, the brake pads 200 and the brake disc 201 will gradually lose material and wear out. According to an aspect of this invention, the total wear value V of the brake pads 200 and the brake disc 201 can be obtained by, e.g., measuring the distance D that the thrust plate 11 travels to press a brake pad 200 against the brake disc 201 , i.e. V = D-BC. Thereby, the dynamic performance of the disc brake 10 at any wear value V can be characterized, thus optimizing the braking function. When the wear value V approaches or exceeds a predetermined value, it can be known that the wear is enough to endanger the normal braking operation of the vehicle and even cause the brake to fail. And, when the wear of the disc brake 10 reaches such predetermined value, it is necessary to replace the brake pads 200 or the brake disc 201 in time so as to ensure the normal brake function of the vehicle.

However, if the distance D that the thrust plate 1 1 needs to travel becomes larger as the wear increases, the brake response time becomes longer, which will affect the braking performance, especially when the braking occurs while driving. Therefore, the brake clearance can be maintained at a constant value by increasing a gap adjustment mechanism or controlling the rotation of the motor.

In the case where the brake clearance BC is maintained at a constant value, the distance that the thrust plate 1 1 is to move each time the braking force is applied is always the brake clearance BC. When the total wear value V = 0, the stroke initial position Po where the thrust plate 1 1 is located is defined as a reference point. The position of the magnetic element 160 corresponding to the position Po is p_o. The stroke initial position of the thrust plate 11 at any total wear value V is P, while the position of the magnetic element 160 is p. When the thrust plate 11 moves by a distance BC to generate a braking force, the distance that the magnetic element 160 moves by a predetermined ratio is be. As the total wear value V gradually increases, the stroke initial position

P of the thrust plate 11 also gradually moves toward the brake disc 201 to keep the brake clearance BC constant, and DR = P - Po = V, and the position p of corresponding magnetic element 160 also changes with it. By the known transmission ratio of the transmission members of the sensor device 100 (for example, the transmission ratio from the ring 111 to the driven screw 140) plus the measured Dr = p - p_o of the magnetic element 160, the DR of the thrust plate 1 1 can be calculated. Thus, the total wear value V is obtained. According to the preset performance parameters of the brake disc 201 and the brake pad 200, such as the wear rate, combined with the total wear value V, the wear values of the brake disc 201 and the brake pad 200 can be calculated respectively. Similarly, when the magnetic element driving unit 165 is the driving gear 132, the stroke initial position Po of the thrust plate 1 1 corresponds to the initial angle of the magnetic element 160, and DR can be calculated from measured amount of change of initial angle of the magnetic element 160 and the transmission ratio from the ring 111 to the driving gear 132.

As may be understood from the embodiments described herein, the rotation of the rotating element 14 of the brake force transmission unit 13 of the present invention simultaneously causes the magnetic element 160 of the pad wear sensor device 100 to motion. Under the action of the intermeshing threads of the driving gear 132, the driven screw 140, and the limit of rotational lock, the rotary motion of the driving gear 132 is converted into a linear motion of the driven screw 140. The magnet element 160 mounted on the driven screw 140 linearly moves by a certain distance under force of the driven screw 140. Alternatively, in the case that only the driving gear 132 exists, the magnetic element 160 rotates with the driving gear 132. The linear motion or rotation motion of the magnetic element 160 causes a change in the magnetic flux around the sensing device

170. The sensing device 170 can measure the amount of change in the motion of the magnetic element 160 based on the change in the magnetic flux due to the motion of the magnetic element 160. This amount of change can reflect the distance traveled by a thrust plate 1 1 , and thus the stroke of each brake can be calculated using the known transmission ratio. Moreover, since the rotation of the rotating element 14 directly determines the position of the thrust plate 1 1 , the sensor device 100 can detect the wear state of the disc brake 10 according to the obtained position information of the thrust plate 1 1 in addition to obtaining the stroke of a single brake.

As a result, the sensor device 100 can measure the wear of the disc brake 10 in real time and continuously and can feedback the measurement result to the vehicle control system such that the disc brake 10 can be more accurately controlled for better brake performance and maintain brake functionality by signaling for replacement of worn brake pads 200 and/or brake disc 201.

In an aspect according to any of the embodiments discussed herein, the sensor device 100 may further include a fixing element such as fixing plate 180. The sensor body 101 may be mounted on the fixing plate 180 and be further fixed to the disc brake housing 16 of the disc brake 10. For example, the sensor body 101 may be mounted such that it is external of the disc brake housing 16, such as shown in FIGs 2-3. Alternatively, the sensor body 101 can be configured such that it fits within a pocket 20 of the disc brake housing 16, e.g., as shown in Fig. 4. The mounting form using a pocket 20 can use the remaining space inside the housing 16 while still maintaining the convenience of easy loading and unloading the sensor body 101 from the outside. As described herein, the present invention may obtain the position of the magnetic element 160 by measuring the change of the magnetic flux from the magnetic element 160 so as to obtain the wear condition of the disc brake 10. In this regard, the wear sensor formed by the sensor device 100 of the present invention uses a non-contact sensing element 170, which is not subject to the vibration caused by vehicle operation. In addition, optical non-contact sensors (such as infrared sensors, laser sensors, etc.) may be used to detect the motion of the driving gear 132 or the driven screw 140 according to different precision requirements and product sizes. Thus, the sensor device 100 of present application advantageously can avoid the measurement failure or measurement inaccuracy caused by vibration. Moreover, the wear sensor formed by the sensor device 100 of the present invention can obtain real-time information of brake wear, and is not limited to a single measurement of a critical threshold value wear. In addition, the present invention also provides a vehicle, such as an automobile, a truck etc., including the sensor device 100 described above or a disc brake 10 having the above-described sensor device 100.

It will be apparent to those skilled in the art that various modifications and variations can be made to the embodiments described herein without departing from the spirit and scope of the claimed subject matter. Thus, it is intended that the specification covers modifications and variations of the various embodiments described herein, provided such modification and variations come within the scope of the appended claims and their equivalents.

LIST OF REFERENCE NUMERALS motor

motor shaft

disc brake

thrust plate

brake force transmission unit

rotating element

screw

disc brake housing

recess

pocket

sensor device

sensor body

ring

shaft or rod

radial transmission unit

belt

gear

driving gear

driven screw

magnetic element

magnetic element driving unit

sensing element

sensor transmission unit

axial transmission unit

transmission unit

fixing plate

PCB

sensor housing

anti-rotation pin

brake pad

brake disc

Claims

1 . A vehicle disc brake (10) comprising a disc brake housing (16), a motor (5) with a motor shaft (6), a thrust plate (1 1 ), and a brake force transmission unit (13) accommodated inside the disc brake housing (16) for converting rotation of the motor shaft (6) into linear motion of the thrust plate (1 1 ), the vehicle disc brake (10) further comprising a sensor device (100) for measuring the travel distance of the thrust plate (1 1 ), wherein the sensor device (100) comprises a magnetic element driving unit (165) for converting or transmitting a rotation of the brake force transmission unit (13) into motion of at least one magnetic element (160).

2. The vehicle disc brake (10) according to claim 1 , wherein the brake force transmission unit (13) comprises a rotating element (14) driven by the motor (5) and threaded with the thrust plate (1 1 ).

3. The vehicle disc brake (10) according to claim 2, wherein the rotating element (14) comprises a screw (15) or a ring (1 1 1 ) attached to a screw (15).

4. The vehicle disc brake (10) according to any one of claims 1 -3, wherein the sensor device (100) comprises a sensor body (101 ) and one or more sensor transmission units (175) and/or transmission units (177).

5. The vehicle disc brake (10) according to claim 4, wherein the sensor body (101 ) comprises a sensor housing (190) which houses the magnetic element driving unit (165), the magnetic element (160) and a sensing element (170), the sensing element (170) being configured to measure the linear moving distance or rotation angle of the magnetic element (160).

6. The vehicle disc brake (10) according to claim 5, comprising an axial transmission unit (176) configured for transmitting rotational motion from the brake force transmission unit (13) to the magnetic element driving unit (165) housed in the sensor housing (190).

7. The vehicle disc brake (10) according to claim 6, wherein the axial transmission unit (176) comprises a shaft or rod (1 13) configured to engage with the rotating element (14), the screw (15) or the ring (1 1 1 ) attached to the screw (15).

8. The vehicle disc brake (10) according to claim 7, wherein the shaft or rod (1 13) is configured to mesh with the screw (15) or ring (1 1 1 ) attached to the screw (15) via a toothed mesh with an external or internal gear of the screw (15) or ring (1 1 1 ).

9. The vehicle disc brake (10) according to claim 7, wherein the shaft or rod (1 13) is configured to engage with a ring (1 1 1 ) attached to the screw (15) via frictional engagement without teeth.

10. The vehicle disc brake (10) according to claim any one of claims 6 to 9, wherein the magnetic element driving unit (165) further comprises a driving gear (132) and a driven screw (140) that convert rotational motion into a linear motion, and wherein the magnetic element (160) is mounted to the driven screw (140).

1 1 . The vehicle disc brake (10) according to any one of claims 6 to 9, wherein the magnetic element driving unit (165) comprises a driving gear (132), and wherein the magnetic element (160) is mounted to the driving gear (132) and rotates with it.

12. The vehicle disc brake (10) according to any one of claims 6-1 1 , further comprising a radial transmission unit (120) for transmitting the rotational motion from the axial transmission unit (176) to the magnetic element driving unit (165) housed in the sensor housing (190).

13. The vehicle disc brake (10) according to claim 12, wherein the radial transmission unit (120) comprises a toothed belt (125).

14. The vehicle disc brake (10) according to claim 12, wherein the axial transmission unit (176) comprises a gear (131 ) configured to mesh with the radial transmission unit (120), and the magnetic element driving unit (165) comprises a driving gear (132) configured to mesh with the radial transmission unit (120).

15. The vehicle disc brake (10) according to claim 10, wherein the magnetic element driving unit (165) comprises a rotational lock.

16. The vehicle disc brake (10) according to claim 15, wherein the rotational lock is a pin (195) or a tab configured to be engaged with the sensor housing (190).

17. The vehicle disc brake (10) according to any one of claims 6-16, wherein the disc brake (10) further comprises a brake disc (201 ) and a brake pad (200), and the rotating element (14) is configured to rotate to allow the thrust plate (1 1 ) to move towards and away from the brake disc (10), characterized in that the sensor transmission unit (175) and the at least one transmission unit (177) are configured to drive the magnetic element (160) to motion by a predetermined ratio of the distance that the thrust plate (1 1 ) travels to press the brake pad (200) against the brake disc (201 ), such that a linear moving distance or rotation angle of the magnetic element (160) is consistent with a distance of axial travel of the thrust plate (11 ) by the predetermined ratio.

18. The vehicle disc brake (10) according to claim 17 wherein the sensing element (170) is configured to measure the motion of the magnetic element (160) based on the change of the magnetic flux caused by movement of the magnetic element (160).

19. The vehicle disc brake (10) according to claim 17, characterized in that the sensor device (100) further comprises a fixing plate (180) for fixing the sensor housing (190) to the disc brake housing (16).

20. The vehicle disc brake (10) according to claim 19, wherein the sensor housing (190) is mounted on an outer surface of the disc brake housing (16).

21. The vehicle disc brake (10) according to claim 19 wherein the sensor housing (190) is fixed in a pocket (20) defined by the disc brake housing (16).

22. A vehicle comprising the vehicle disc brake (10) of any of the preceding claims.