DEVICE

TECHNICAL FIELD OF THE INVENTION

The present invention relates to brake systems for vehicles, and more particularly to a sensor device and a vehicle disc brake and a vehicle comprising the sensor device.

PRIOR ART Disc brakes are widely used to brake vehicles. For braking a vehicle, generally, 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 wear items within a disc brake, and the brake pads have a friction material contacting with the surface of the brake disc. With every use, the brake pads and the brake disc lose material, and over time, reach wear limit. If the brake pads and the brake disc are not replaced in time, it will affect braking performance and safety. The wear rate of the brake pads and the brake disc will vary based on various factors, such as the properties of the friction material, braking force and number of braking, etc. Therefore, a pad wear sensor is needed to obtain information on the wear condition in order to ensure the normal operation of the vehicle brake system. Electromechanical brake systems comprising disc brakes are all-electrical brake-by-wire systems in which the source of braking force is the rotational output of the motor and multiple brake parameters including brake pad wear are all related to the amount of rotation of the motor output.

Wear sensors suitable for this system are usually connected directly or indirectly to the motor or its transmission system. Therefore, in order to prevent mechanical damage caused by the sensor receiving rotational input beyond the measurement stroke and to provide a reference point for use in the control algorithm, a sensor design with an overrun protection structure is required.

OBJECT OF THE INVENTION

It is an object of the present invention to provide a sensor device which - can be used and/or easily adapted for different applications and/or

is more robust against a malfunction or damages.

Furthermore, an object of the invention is to provide an improved vehicle disc brake and an improved vehicle comprising a sensor device.

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

In aspects of the invention described herein, information about a wear condition can be measured by a sensor device which is capable of converting a rotary motion input into a linear motion output. For example, a sensor device may be configured to convert an input rotary motion, such as rotation of a brake force transmission unit, into linear motion of at least one driven screw by means of a transmission mechanism.

In this regard, for a sensor device which is capable of converting a rotary motion input into a linear motion output, e.g., via a screw mechanism, a drawback can arise if there is excessive rotational motion input, such that a linear motion output exceeds the maximum stroke of the screw mechanism. Such excessive or over rotation can break the screw mechanism, and cause the screw mechanism to be locked or destroyed. To overcome such drawbacks, the present invention provides a sensor device which can allow for excess rotation input and prevent the screw mechanism from breaking or being locked, and at the same time provide a reference point for use in a control algorithm.

In an aspect of the invention, a sensor device is provided. The sensor device comprises a rotary to linear motion conversion mechanism for converting an input rotational motion into an output linear motion. The sensor device further comprises an overrun protection structure that acts when the input rotational motion causes the linear motion to exceed its maximum stroke.

In an aspect according to any embodiment described herein, the rotary-linear motion conversion mechanism comprises a driving wheel that receives a rotational motion input and a rotationally locked driven screw that produces a linear motion output.

In an aspect according to any embodiment described herein, the overrun protection structure comprises an intermediate screw that is threadedly connected to the driven screw and forms a one-way ratcheting clutch with the driving wheel, wherein the one-way ratcheting clutch is configured to slip upon tightening of threads of the driven screw and the intermediate screw.

In an aspect according to any embodiment described herein, the driving wheel and the intermediate screw are configured with a plurality of ratchet teeth for engagement with a corresponding plurality of coupling parts distributed circumferentially, the plurality of ratchet teeth being included either on the driving wheel or the intermediate screw, wherein each tooth of the plurality of ratchet teeth is asymmetrical in a circumferential direction of the driving wheel or intermediate screw, each tooth having a steeper slope in one circumferential direction and a more moderate slope in the opposite circumferential direction.

In an aspect according to any embodiment described herein, the steeper slopes of the ratchet teeth are coupled to the coupling part when the threads of the driven screw and the intermediate screw are loosened, and the more moderate slopes of the ratchet teeth are coupled to the coupling part when the threads of the driven screw and the intermediate screw are tightened.

In an aspect according to any embodiment described herein, the sensor device may further comprise a receiver for detecting a position of a source disposed on the driven screw. In an aspect according to any embodiment described herein, the overrun protection structure may further comprise a spring which can compress the driven screw towards the driving wheel.

In an aspect according to any embodiment described herein, the sensor device may further comprise a housing which has an anti-rotation structure that prevents rotation of the driven screw. In an aspect according to any embodiment described herein, the rotary to linear motion conversion mechanism of the sensor device may comprise a radial transmission mechanism comprising a primary wheel that receives a rotational motion input.

In an aspect according to any embodiment described herein, the radial transmission mechanism may comprise a transmission belt that couples with the primary wheel and the driving wheel. In an aspect according to any embodiment described herein, the radial transmission mechanism may comprise a tensioner that maintains the tension of the transmission belt.

In an aspect of the invention according to all embodiments described herein, a vehicle disc brake is provided, wherein the vehicle disc brake comprises a sensor device as described herein.

In another aspect of the invention, a vehicle is provided, the vehicle comprising a vehicle disc brake that comprises the sensor device as described herein.

The sensor device of the present invention has a simple and compact structure and can prevent the screw mechanism from breaking or being locked.

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

In the following, the invention is further explained and described with respect to preferred exemplary embodiments illustrated in the drawings.

Fig. 1 is a schematic partial structural view of a disk brake comprising a sensor device according to the present invention.

Fig. 2 is a schematic structural view of a sensor device 1 according to the present invention. Fig. 3 is a schematic exploded perspective view of a sensor device according to the present invention. Fig. 4 is a schematic exploded perspective view of an overrun protection structure of the sensor device according to the present invention.

Fig. 5 is a schematic structural view of a sensor device configured to be accommodated in a pocket inside a disc brake housing according to the present invention. Fig. 6 is a schematic structural view of a sensor device configured to connect the primary wheel directly to the driving wheel.

Fig. 7 is a schematic structural view of a tensioner of the sensor device according to the present invention.

DESCRIPTION OF THE DRAWINGS The present invention will now be described in detail with reference to a few 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 -4, Fig. 1 is a partial structural diagram 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 with a motor shaft (not shown), a thrust plate 1 1 , and a brake force transmission unit. A brake or brake pads 200 may be attached to the thrust plate 1 1. The brake pad or pads may be made of any suitable material, and may be placed between the thrust plate and the brake disc by any suitable means. The brake force transmission unit is configured to drive the thrust plate 11 towards and away from a brake disc 201 , so that the one or more brake pads may press against the brake disc or move away from the brake disc. In an exemplary embodiment, the brake force transmission unit is configured for converting rotation of the motor shaft into linear motion of the thrust plate 11. The brake force transmission unit may, for example, comprise a rotating element 13 driven directly or indirectly by the motor and threaded with the thrust plate 11. The rotating element may comprise, for example, a screw or a ring 111 attached to a screw.

According to the present invention, as shown in Figs. 1-3, the sensor device 100 included in the vehicle disc brake may be configured to measure the amount of rotation of the brake force transmission unit using non-contact sensing elements, and calculate the moving distance of the thrust plate 11 in combination with information such as known thread parameters so as to reliably monitor and measure the wear of the brake disc and the brake pad attached to thrust plate 11. Specifically, in the absence of braking demand, the thrust plate 11 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 , the brake force transmission unit drives the thrust plate 11 to move brake pads 200 towards the brake disc 201 so as to eliminate the brake clearance, and thereby braking effect can be achieved. In this regard, with the use over a period of time, the brake pads and the brake disc will gradually lose material and wear out. According to an aspect of this invention, the total wear value V of the brake pads and the brake disc 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 brake system at any wear value V can be characterized, thus optimizing the braking function.

The sensor device 100 of the present invention obtains the moving distance of the thrust plate in the vehicle disc brake by measuring the rotation angle of the rotating element 13, and combining the parameters of the transmission thread between the rotating element 13 and the thrust plate 11. The sensor device described herein can thereby provide a precise measurement of wear condition of a brake.

In this regard, as shown in Figs. 2-3, the sensor device 100 of the present invention includes a rotary to linear motion conversion mechanism for converting an input rotational motion into an output linear motion. For example, as shown in Fig. 2, the rotary to linear motion conversion mechanism can include a driving wheel 132 that receives a rotational motion input and a rotationally locked driven screw 140 that produces a linear motion output. In one or more exemplary embodiments, a source 160 may be positioned on the driven screw 140, and the sensor device 100 may include a receiver 170 for sensing the position of the source 160. The driven screw 140 may be configured to drive the source 160 to linear motion when, e.g., the brake rotating element 13 in the brake force transmission unit rotates. The receiver 170 may be configured to measure the moving distance of the source 160. In an exemplary embodiment, the source can be, for example, a magnetic source or a light source. In embodiments, when the source is a magnetic source, the receiver 170 can be a Hall element.

However, the limit stroke of the rotary to linear motion conversion mechanism depends on the length of the screw connection between the driving wheel 132 and the driven screw 140. When the control system is abnormal or in maintenance work such as replacing the brake disc or the brake pads, the driving wheel 132 may accept excessive rotary input, and the threaded connection may be disengaged, locked or even damaged when the limit stroke is exceeded.

To overcome the problems of excessive rotation, the sensor device of the present invention includes an overrun protection structure configured to act when the rotational motion of the driving wheel 132 causes the linear motion of the driven screw 140 to exceed its maximum stroke.

In an embodiment, the overrun protection structure comprises an intermediate screw 136 that is threadedly connected to the driven screw 140 and forms a one-way ratcheting clutch with the driving wheel 132, wherein the one-way ratcheting clutch is configured to slip upon tightening of threads of the driven screw 140 and the intermediate screw 136.

As shown in Figs. 2-4, the driving wheel 132 and the intermediate screw 136 can be configured with a plurality of ratchet teeth 1321 for engagement with a corresponding plurality of coupling parts 1361 distributed circumferentially. The plurality of ratchet teeth 1321 can be included either on the driving wheel or the intermediate screw, wherein each tooth of the plurality of ratchet teeth 1321 is asymmetrical in a circumferential direction of the driving wheel 132 or intermediate screw 136. Each tooth has a steeper slope 1322 in one circumferential direction and a more moderate slope 1323 in the opposite circumferential direction. The coupling parts can be, for example, a hole or a recess. The intermediate screw 136 has an internal thread that is engageable with the external thread of the driven screw 140. The driving wheel 132 rotates the intermediate screw 136 together by a plurality of ratchet teeth thereon, and the intermediate screw 136 further drives the driven screw 140 to motion linearly. When the threads of the driven screw 140 and the intermediate screw 136 are loosened, the steeper slopes 1322 of the ratchet teeth 1321 are coupled to the coupling part 1361. When the threads of the driven screw 140) and the intermediate screw 136 are tightened, the more moderate slopes 1323 of the ratchet teeth 1321 are coupled to the coupling part 1361 so that the driven screw and the intermediate screw can be prevented from being locked due to over- tightening of the screw. Specifically, when the thread between the driven screw and the intermediate screw is screwed to a certain extent, the more moderate slope 1323 of the ratchet teeth 1321 slips in the coupling part 1361 , thereby preventing the driven screw and the intermediate screw from being locked or destroyed due to over-tightening.

In an exemplary embodiment, the overrun protection structure described herein further includes a spring 133 that presses the driven screw 140 toward the driving wheel 132. In one embodiment, the spring 133 is disposed between the driven screw 140 and a housing 190. When the threads of the driven screw 140 and the intermediate screw 136 are unscrewed such that the driven screw 140 is nearly disengaged from the intermediate screw, the pressure applied by the spring 133 to the driven screw 140 can prevent the driven screw 140 from being disengaged from the intermediate screw 136.

In an exemplary embodiment to form the rotationally locked driven screw 140, the sensor device 100 can further include an anti-rotation structure that prevents rotation of the driven screw 140. For example, the driven screw can have a groove 141 extending in the direction of rotation axis, and a bar extending in the same direction or a pin extending radially into the groove may be provided on a housing 190.

In an embodiment, the sensor device 100 can include a rotary to linear conversion mechanism as described herein, wherein the rotary to linear conversion mechanism comprises a radial transmission mechanism. In an example, the radial transmission mechanism can include a primary wheel 131 that receives a rotational motion input, such as rotational motion input from a motor or a brake force transmission unit. The primary wheel 131 can be further coupled to the driving wheel 132 such that the driving wheel 132 can receive rotational motion input. The sensor device 100 of the present invention can thus be configured to take a rotational motion of a motor or a brake force transmission unit as input. In an exemplary embodiment, the sensor device 100 comprises a rod 113, one end of which is connected to the rotating element 13 that is described herein, for example to a ring 111 of the rotating element 13. The other end of the rod 113 may be coupled to the primary wheel 131 to transmit the rotational motion of the rotary member 13 to the primary wheel 131 , whereby the primary wheel 131 can accept rotational motion of the rod 113 as input. The driving wheel 132 can include teeth, and the primary wheel 131 can be a gear which can directly mesh with teeth of the driving wheel 132 so as to transmit rotational motion to the driving wheel 132, or the radial transmission mechanism between the primary wheel 131 and driving wheel 132 can further include a transmission belt 120 that engages the primary wheel 131 and the driving wheel 132, wherein the primary wheel 131 and the driving wheel 132 can be gears or belt wheels with or without teeth. Correspondingly, the transmission belt 120 can also be a toothed belt or a belt without teeth.

In aspects in accordance with any of the embodiments discussed herein, the sensor device 100 may also include a fixing element, such as a fixing plate 180. The sensor device can be fixed to the housing 16 of the disc brake 10 by the fixing plate. For example, as shown in Figs. 1-3, the sensor device 100 can be mounted such that it is external to the disc brake housing. Alternatively, as shown in Fig. 5, the sensor device 100 can be configured to be accommodated in a pocket inside a disc brake housing. The mounting form using a pocket can use the remaining space inside the housing 16 while still maintaining the convenience of easy loading and unloading the sensor device from the outside.

Alternatively, as shown in Fig. 6, the vehicular disc brake 10 may be configured to connect the primary wheel 131 directly to the driving wheel 132 without the use of the drive belt 120.

As shown in Fig. 7, in embodiments where the radial transmission mechanism includes a transmission belt 120, the radial transmission mechanism may further include a tensioner 135 that maintains the tension of the transmission belt 120. In an exemplary embodiment, the tensioner 135 may include a tensioning wheel 1351 , a leaf spring 1352 and a mounting bracket 1353. One end of the leaf spring 1352 is fixed on the mounting bracket 1353, and the other end is connected with the tensioner 1351 to apply pressure to the tensioner 1351 , so that the tensioner 1351 abuts against the transmission belt 120 to prevent the belt from loosening or detached from the primary wheel 131 and the driving wheel 132. The mounting bracket 1353 is mounted on the fixing plate 180. In operation of a disc brake, it is desirable to maintain the brake clearance BC at a constant value, such that the distance that the thrust plate 11 is to move each time before the braking force is applied is always the brake clearance BC. In electromechanical braking systems, control algorithms are often used to accomplish this. For example, 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 source 160 corresponding to the position Po is po. Then, the stroke initial position of the thrust plate at any total wear value V is P, while the position of the source 160 is p. When the thrust plate moves by a distance BC to close the gap between the brake pads and the brake disc, the distance that the source 160 moves by a predetermined ratio is be. In this regard, 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 to keep the brake clearance BC constant, and DR= P-Po=V, and the position p of corresponding source 160 also changes with it.

Thus, it can be seen that when the total wear value V=0, the stroke initial position Po of the thrust plate 11 is a key parameter in the control algorithm of the electromechanical brake system. The overrun protection structure resets the sensor position, and the starting point can be used as a reference for calibrating Po.

The present invention also provides a vehicle disc brake 10, such as shown in Fig. 1. The disc brake may include a brake disc 201 , a thrust plate 11 , a motor, and a transmission mechanism. The brake disc may be, for example, the brake disc 201 as shown in Fig. 1 , wherein the transmission mechanism converts the rotational motion output by the motor into a linear motion that pushes the thrust plate toward or away from the brake disk. The disc brake further comprises the above-described sensor device of the present invention. The sensor device takes the rotational motion of the motor or the transmission mechanism as its input.

The present invention also provides a vehicle, such as an automobile, a truck etc., including the sensor device described above or a disk brake having the above-described sensor device.

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

10 disc brake

11 thrust plate

13 rotating element

16 disc brake housing

100 sensor device

111 screw or ring

113 rod

120 transmission belt

131 primary wheel

132 driving wheel

1321 ratchet teeth

1322 steep slope

1323 moderate slope

133 spring

135 tensioner

1351 tensioning wheel

1352 leaf spring

1353 mounting bracket

136 intermediate screw

1361 coupling parts

140 driven screw

141 groove

160 source

170 receiver

180 fixing plate

190 housing

200 brake pad

201 brake disc