Description:Complete Specification:
The following specification describes and ascertains the nature of this invention and the manner in which it is to be performed:

Field of the invention:
[0001] The present invention relates a system, controller, and method to determine wear of brake pads in a vehicle.

Background of the invention:
[0002] In conventional art, there are concepts to measure brake pad wear different ways such as simulation, using active pressure generation or using dedicated wear depth sensors. However, each of those are either inaccurate or costly.

[0003] A patent literature GB2202016 discloses brake-monitoring device. A brake-monitoring device for a brake system of an automotive vehicle equipped with an electronic anti-lock system comprises two microprocessors which have input signals formed by a clock signal, wheel speed signals as well as a brake-actuating signal. A programmable and erasable memory unit is connected to at least one of the microprocessors from which it receives the most important data indicative of the degree of wear of the brake system and thus memorizes the history of the brake system since the last erasure. At least one of the microprocessors determines from the contents of the memory unit the degree of wear of the individual components of the brake system and issues an alarm signal when a predetermined degree of wear is reached.

Brief description of the accompanying drawings:
[0004] An embodiment of the disclosure is described with reference to the following accompanying drawing,
[0005] Fig. 1 illustrates a hydraulic braking system and a controller to determine wear of brake pads in a vehicle, according to an embodiment of the present invention;
[0006] Fig. 2 illustrates other stages of hydraulic braking circuit, according to an embodiment of the present invention;
[0007] Fig. 3 illustrates wear detection of the brake pads in brakes and graphs for the same, according to an embodiment of the present invention, and
[0008] Fig. 4 illustrates a flow diagram of a method for determining wear of brake pads in the vehicle, according to the present invention.

Detailed description of the embodiments:
[0009] Fig. 1 illustrates a hydraulic braking system and a controller to determine wear of brake pads in a vehicle, according to an embodiment of the present invention. The hydraulic braking system 100 comprises a brake lever which is either a hand lever 102 or a foot pedal 126 (shown in dotted circle). The brake lever 102, 126 is connected to a master cylinder 106 with maser piston (not shown) in association with a reservoir 104 storing brake fluid. The master cylinder 106 is fluidly connected to an entry valve 110, an exit valve 120, an accumulator 122 and a pump 124. The outlet of the pump 124 is connected upstream of the entry valve 110 to complete the return path back to the reservoir 104. Further, a pressure sensor 112 is connected to the hydraulic line 114 between the entry valve 110 and the exit valve 120, and the same hydraulic line 114 is fluidly connected to the brakes 116. Although not numbered, there are several filters connected such as before and/or after entry valve 110, the exit valve 120 and the pump 124. Further, a one way valve is provide in between the accumulator 122 and the pump 124. The pump 124 is run by a motor 108. The brakes 116 are mounted to arrest movement of a disk 138 fixed to a wheel 118 of the vehicle.

[0010] The entry valve 110 and the exit valve 120 are electronically controlled valve such as electromagnetic or solenoid valve. However, it may be some other type of electronically controlled valve as well and not limited by the electromagnetic valve.

[0011] According to an embodiment of the present invention, the controller 130 to determine wear of brake pads 136 in the vehicle is provided. The vehicle comprises the hydraulic braking system 100 for actuation of the brake pads 136, which comprises the master cylinder 106, with master piston, fluidly connected with the entry valve 110, followed by the exit valve 120 and the accumulator 122. The brake pads 136 are held by calipers 140 which is/are operated by brake fluid through the hydraulic line 114 between the entry valve 110 and the exit valve 120. The pressure sensor 112 is positioned on/to the hydraulic line 114. The controller 130 is connected to the entry valve 110, the exit valve 120 and the pressure sensor 112, characterized in that, the controller 130 configured to control operation of the entry valve 110 and the exit valve 120 in a predetermined manner upon detection of a trigger condition. The controller 130 then determines level of the wear of the brake pads 136 based on pressure measurement during the operation. The determined level of wear is then provided as output through output device 128 such as but not limited to instrument panel, a wirelessly connected communication device, a light, a sound, a haptic sensor, and the like.

[0012] According to the present invention, the trigger condition comprises fluid pressure increase/rise in fluid pressure to a threshold value when the entry valve 110 is open and the exit valve 120 is closed. The increase in fluid pressure is due to manual pressing of the brake lever 102, 126 by an operator. The increased fluid pressure is shown by the dashed line in the hydraulic braking system 100 which also represents first stage of the operation.

[0013] According to an embodiment of the present invention, the controller 130 refers to computing devices/units comprising components such as memory element such as Random Access Memory (RAM) and/or Read Only Memory (ROM), Analog-to-Digital Converter (ADC), Digital-to-Analog Convertor (DAC), clocks, timers, and a processor (such as Central Processing Unit (CPU)) (capable of implementing machine learning) connected with each other and to other components through communication bus channels. The components mentioned are just for understanding and may have more or less components as per requirement. The memory element of the controller 130 is prestored with logics or instructions or programs or applications or thresholds or values which is accessed by the processor as per the defined routines. The internal components of the controller 130 are not explained for being state of the art, and the same must not be understood in a limiting manner. The controller 130 is capable to communicate through wired and wireless means such as but not limited to Global System for Mobile Communications (GSM), 3G, 4G, 5G, Wi-Fi, Bluetooth, Ethernet, serial networks, Universal Serial Bus (USB) cable, micro-USB, and the like. The controller 130 is possible to be provided in the form of Application Specific Integrated Circuits (ASIC), Field Programmable Gate Arrays (FPGA), System-in-Package (SiP) and the like.

[0014] Fig. 2 illustrates other stages of hydraulic braking circuit, according to an embodiment of the present invention. In order to control operation of the entry valve 110 and the exit valve 120, the controller 130 configured to close the entry valve 110 when the trigger condition is met. The entry valve 110 is closed in order to maintain constant pressure between the entry valve 110 and the exit valve 120. The controller 130 measures a first pressure between the entry valve 110 and the exit valve 120 and stores in a memory element. The first pressure is measured using the pressure sensor 112. The constant pressure is shown by the dashed line in sub-figure 200 which also represents the second stage of the operation. In a third stage of the operation represented by sub-figure 210, the controller 130 opens the exit valve 120 and allows filling of the accumulator 122 with the brake fluid, again shown by the dashed line. The accumulator 122 is of a predetermined fixed volume as per the design requirement. The controller 130 again measures a second pressure using the pressure sensor 112 after the accumulator 122 is filled, and stores in the memory element of the controller 130. The controller 130 now calculates pressure drop based on difference between the first pressure and second pressure, and determines level of wear of brake pads 136 based on the pressure drop in comparison to standard pressure difference pre-stored in the memory element of the controller 130. The standard pressure difference is pressure difference for a new brake pad 136 without any wear. The hydraulic braking system 100 is an Anti-lock Braking System (ABS) without active pressure generation. Further, once the controller 130 has measured the second pressure, the pump 124 is operated (curved arrow) through the motor 108 to suck the brake fluid from the accumulator 122 and supply back to the master cylinder 106.

[0015] Fig. 3 illustrates graphical assessment of wear of the brake pads, according to an embodiment of the present invention. A first graph 306 is shown for a first brake 302 without any wear in the brake pads 136. Similarly, a second graph 308 is shown for a second brake 304 with worn out brake pads 136. The thickness of the brake pads 136 of the second brake 304 is less in comparison to the thickness of the brake pad 136 of the first brake 302. It is clear that in the first brake 302, the flow of brake fluid (represented by arrow) is towards the chamber 134 occupied by a piston 132. The volume is low as the brake pads 136 are new. Further, the volume from the master cylinder 106 till the chamber 134 is considered, however only the volume of chamber 134 is shown for simplicity in understanding. However, the piston 132 is displaced further when the brake pads 136 are worn out, as shown in the second brake 304, and thereby increases the volume in the chamber 134. The pressure drop in the first brake 302 is more in comparison to the pressure drop in the second brake 304. The same relationship is used by the controller 130 to predict/estimate the level of the wear of brake pads 136. Thus, different levels of wear is estimated/ determined by the controller 130 based on the measured pressure drop.

[0016] In both the first graph 306 and the second graph 308, the y-axis indicates volume, and the X-axis indicates time in respective suitable units. Now with reference to both the first graph 306 and the second graph 308, at a first event 310 of manually pressing brake lever 102, 126 the pressure in the hydraulic circuit rises (as shown in Fig 1). At second event 312 of meeting the triggering condition, the controller 130 closes the entry valve 110 to keep the constant pressure downstream. The controller 130 simultaneously measures the first pressure. At a third event 314 of opening the exit valve 120, the pressure drops based on the corresponding volume in the chamber 134. The volume decrease in the first brake 302 is higher in comparison to the volume decrease in the second brake 304. At the event 316 when the accumulator 122 is filled and pressure is stabilized, the controller 130 measures the second pressure and proceeds with calculation of pressure reduction to estimate wear of the brake pads 136.

[0017] According to the present invention, a working of the controller 130 and the hydraulic braking system 100 is envisaged. Assume a vehicle, such as motorcycle, is equipped with brakes 116, i.e. front brake and rear brake with the hydraulic braking system 100. The motor 108 is either common or separate, however each of the front brake and the rear brake are provided with independent hydraulic braking system 100. Now consider, the rider/driver switches ON the vehicle by inserting the key (or keyless entry). An instrument panel of the vehicle shows option to evaluate the status of brake pads 136 independently for front brake and rear brake as one of a diagnostic features. The rider selects the option and activates the diagnosis. The vehicle is standstill, and the rider is instructed to press the brake lever 102, 126. When the rider presses the brake lever 102, 126, the fluid pressure in the hydraulic braking system 100 increases and is detected by the controller 130 through the pressure sensor 112. Once the threshold pressure is reached, the controller 130 electronically closes the entry valve 110. Since, the exit valve 120 is initially in closed position, the fluid pressure in the hydraulic line 114 remains constant. The controller 130 measures the first pressure and saves in the memory element. It is to be noted that, the fluid pressure detected as soon as the entry valve 110 is closed can also be considered as the first pressure.

[0018] The controller 130 now electronically opens the exit valve 120 and allows the accumulator 122, positioned downstream of the exit valve 120, to be filled with the pressurized brake fluid. Once the pressure is stabilized after filling the accumulator 122, the controller 130 measure the second pressure. The controller 130 now calculates the pressure drop/difference and compares with the look-up table saved in the memory element, and determines the level of wear of brake pads 136. It is to be noted that, a model is also usable in place of the look-up table, where the model contains the relationship between the pressure drop and the corresponding wear level.

[0019] According to the present invention, the applicable vehicle are but not limited to as a two-wheeler such as scooter, motorcycle, a three-wheeler such as autorickshaw, a four wheeler such as cars, multi-wheel vehicles, off-road vehicles, etc.

[0020] According to an embodiment of the present invention, the hydraulic braking system 100 to determine wear in brake pads 136 is disclosed. The hydraulic braking system 100 comprises the master cylinder 106 fluidly connected with the entry valve 110, followed by the exit valve 120 and the accumulator 122. The brake pads 136 are held by calipers 140 which is operated by brake fluid through the hydraulic line 114 between the entry valve 110 and the exit valve 120. A pressure sensor 112 is positioned on/to the hydraulic line 114. The system 100 also comprises the controller 130 connected to the entry valve 110, the exit valve 120 and the pressure sensor 112, characterized in that, the controller 130 configured to control operation of the entry valve 110 and the exit valve 120 in the predetermined manner upon detection of the trigger condition. The controller 130 further determines level of the wear of the brake pads 136 based on pressure measurement during the operation. The determined level is provided as output to output device 128 such as but not limited to instrument panel, the wirelessly connected communication device (such as smartphone, smart watch, etc.), the light indicator, the sound, the haptic sensor, and the like.

[0021] According to the present invention, the trigger condition comprises fluid pressure increase/rise in fluid pressure to the threshold value when the entry valve 110 is open and the exit valve 120 is closed. The increase in fluid pressure is due to manual pressing of the brake lever 102, 126 by the operator.

[0022] Further in the system 100, in order to control operation of the entry valve 110 and the exit valve 120, the controller 130 configured to close the entry valve 110 when the trigger condition is met. The entry valve 110 is closed in order to maintain constant pressure between the entry valve 110 and the exit valve 120. The controller 130 measures the first pressure between the entry valve 110 and the exit valve 120 and stores in the memory element of the controller 130. The controller 130 opens the exit valve 120 and allows filling of the accumulator 122 with the brake fluid. The accumulator 122 is of predetermined/fixed volume. The controller 130 again measures the second pressure after the accumulator 122 is filled. The controller 130 now calculates pressure drop based on difference between the first pressure and second pressure, and determines level of wear of brake pads 136 based on the pressure drop in comparison to standard pressure difference pre-stored in the memory element of the controller 130. The standard pressure difference is pressure difference for the new brake pad 136 without any wear. The hydraulic braking system 100 is the Anti-lock Braking System (ABS) without active pressure generation. Once the controller 130 has measured the second pressure, the pump 124 is operated through the motor 108 to suck the brake fluid from the accumulator 122 and supply back to the master cylinder 106 for next cycle.

[0023] Fig. 4 illustrates a flow diagram of a method for determining wear of brake pads in the vehicle, according to the present invention. The vehicle comprises hydraulic braking system 100 which comprises the master cylinder 106 fluidly connected with the entry valve 110, followed by the exit valve 120 and the accumulator 122. The brake pads 136 are held by calipers 140 which is operated by brake fluid received from the hydraulic line 114 between the entry valve 110 and the exit valve 120. The pressure sensor 112 is positioned on the hydraulic line 114. Further, the controller 130 is connected to the entry valve 110, the exit valve 120 and the pressure sensor 112. The method, characterized by, a step 402 which comprises controlling operation of the entry valve 110 and the exit valve 120 in the predetermined manner upon detection of the trigger condition. A step 404 comprises determining level of the wear of the brake pads 136 based on pressure measurement during the operation.

[0024] In the step 402, the triggering condition comprises fluid pressure increasing to the threshold value when the entry valve 110 is open and the exit valve 120 is closed. The fluid pressure is increased by pressing the brake lever 102, 126 by the operator. The step 402 of controlling operation of the entry valve 110 further comprises a step 406 which comprises, closing the entry valve 110 when the trigger condition is met. The entry valve 110 is closed in order to maintain constant pressure between the entry valve 110 and the exit valve 120. The step 408 comprises measuring the first pressure between the entry valve 110 and the exit valve 120 and storing in the memory element. A step 410 comprises opening the exit valve 120 and filling the accumulator 122 with the brake fluid. The accumulator 122 is of the predetermined volume. A step 412 comprises measuring the second pressure after the filling the accumulator 122.

[0025] The step 404 of determining level of the wear of brake pads 136 comprises, further steps. A step 414 comprises calculating pressure drop based on difference between the first pressure and second pressure. A step 416 comprises determining wear of brake pads 136 based on the pressure drop in comparison to standard pressure difference pre-stored in the memory element of the controller 130. The standard pressure difference is pressure drop/difference for the new brake pad 136. The hydraulic braking system 100 is the Anti-lock Braking System (ABS) with built-in pressure sensor 112 and with/without active pressure generation.

[0026] According to the present invention, the controller 130, the hydraulic braking system 100 and method for detecting wear of brake pad 136 for vehicles equipped with ABS unit with pressure sensors 112 is provided. Thus, wear is determinable in mid-segment vehicles equipped with ABS with inbuilt pressure sensor 112 without any additional hardware. With increase in wear of brake pad 136, the hydraulic volume in the hydraulic braking system 100 from the piston in the master cylinder 106 to the piston 132 in the caliper 140 also increases. Due to change in the volume, the pressure drop changes upon controlled operation of the entry valve 110 and the exit valve 120, which is used to estimate the level of wear of brake pads 136. The present invention is usable for all vehicle types using ABS with pressure sensor 112. There is no additional hardware cost for existing vehicle as it is retrofittable. Further, the present invention is useful for riders/drivers who are not sure how to assess wear of brake pads 136 on their vehicle.

[0027] It should be understood that embodiments explained in the description above are only illustrative and do not limit the scope of this invention. Many such embodiments and other modifications and changes in the embodiment explained in the description are envisaged. The scope of the invention is only limited by the scope of the claims.
 
, Claims:We claim:
1. A controller (130) to determine wear of brake pads (136) in a vehicle, said vehicle comprises a hydraulic braking system (100) which comprises a master cylinder (106) fluidly connected with an entry valve (110), followed by an exit valve (120) and an accumulator (122), said brake pads (136) are held by calipers (140) which is operated by brake fluid received from a hydraulic line (114) between said entry valve (110) and said exit valve (120), a pressure sensor (112) positioned on said hydraulic line (114), said controller (130) connected to said entry valve (110), said exit valve (120) and said pressure sensor (112), characterized in that, said controller (130) configured to
control operation of said entry valve (110) and said exit valve (120) in a predetermined manner upon detection of a trigger condition, and
determine level of said wear of said brake pads (136) based on pressure measurement during said operation.

2. The controller (130) as claimed in claim 1, wherein said trigger condition comprises increase in fluid pressure to a threshold value when said entry valve (110) is open and said exit valve (120) is closed, wherein increase in said fluid pressure is due to pressing of said brake lever (102, 126) by an operator.

3. The controller (130) as claimed in claim 1, wherein in order to control operation of said entry valve (110) and said exit valve (120), said controller (130) configured to,
close said entry valve (110) when said trigger condition is met, said entry valve (110) is closed in order to maintain constant pressure between said entry valve (110) and said exit valve (120);
measure a first pressure between said entry valve (110) and said exit valve (120) and store in a memory element, said first pressure is measured using said pressure sensor (112);
open said exit valve (120) and allow filling of said accumulator (122) with said brake fluid, said accumulator (122) is of a predetermined volume, and
measure a second pressure using said pressure sensor (112) after said accumulator (122) is filled, and store in said memory element;
wherein, in order to determine wear of brake pads (136), said controller (130) configured to
calculate pressure drop based on difference between said first pressure and second pressure, and
determine level of wear of brake pads (136) based on said pressure drop in comparison to standard pressure difference pre-stored in said memory element, said standard pressure difference is pressure drop for brake pad (136) without wear.

4. The controller (130) as claimed in claim 1, wherein said hydraulic braking system (100) is an Anti-lock Braking System (ABS) with built-in pressure sensor (112) and without active pressure generation.

5. A hydraulic braking system (100) to determine wear in brake pads (136) of a vehicle, said hydraulic braking system (100) comprises a master cylinder (106) fluidly connected with an entry valve (110), followed by an exit valve (120) and an accumulator (122), said brake pads (136) are held by calipers (140) which is operated by brake fluid received from a hydraulic line (114) between said entry valve (110) and said exit valve (120), a pressure sensor (112) positioned on said hydraulic line (114), and a controller (130) connected to said entry valve (110), said exit valve (120) and said pressure sensor (112), characterized in that, said controller (130) configured to
control operation of said entry valve (110) and said exit valve (120) in a predetermined manner upon detection of a trigger condition, and
determine level of said wear of said brake pads (136) based on pressure measurement during said operation.

6. The system (100) as claimed in claim 5, wherein in order to control operation of said entry valve (110) and exit valve (120), said controller (130) configured to,
close said entry valve (110) when said trigger condition is met, said entry valve (110) is closed in order to maintain constant pressure between said entry valve (110) and said exit valve (120);
measure a first pressure between said entry valve (110) and said exit valve (120) and store in a memory element, said first pressure is measured using said pressure sensor (112);
open said exit valve (120) and allow filling of said accumulator (122) with said brake fluid, said accumulator (122) is of a predetermined volume, and
measure a second pressure using said pressure sensor (112) after said accumulator (122) is filled, and store in said memory element;
wherein, in order to determine wear of brake pads (136), said controller (130) configured to
calculate pressure drop based on difference between said first pressure and second pressure, and
determine level of wear of brake pads (136) based on said pressure drop in comparison to standard pressure difference pre-stored in said memory element, said standard pressure difference is pressure drop for brake pad (136) without wear.

7. A method for determining wear of brake pads (136) in a vehicle, said vehicle comprises hydraulic braking system (100) which comprises a master cylinder (106) fluidly connected with an entry valve (110), followed by an exit valve (120) and an accumulator (122), said brake pads (136) are held by calipers (140) which is operated by brake fluid through a hydraulic line (114) between said entry valve (110) and said exist valve (120), a pressure sensor (112) positioned on said hydraulic line (114), and a controller (130) connected to said entry valve (110), said exit valve (120) and said pressure sensor (112), characterized by, said method comprising the steps of:
controlling, by said controller (130), operation of said entry valve (110) and said exit valve (120) in a predetermined manner upon detection of a triggering condition, and
determining, by said controller (130), level of said wear of said brake pads (136) based on pressure measurement during said operation.

8. The method as claimed in claim 7, wherein said trigger condition comprises fluid pressure increasing to a threshold value when said entry valve (110) is open and said exit valve (120) is closed, wherein increase in said fluid pressure is by pressing of said brake lever (102, 126) by an operator.

9. The method as claimed in claim 7, wherein
controlling operation of said entry valve (110) comprises,
closing said entry valve (110) when said trigger condition is met, said entry valve (110) is closed in order to maintain constant pressure between said entry valve (110) and said exit valve (120);
measuring a first pressure between said entry valve (110) and said exit valve (120) and storing in a memory element, said first pressure is measured using said pressure sensor (112);
opening said exit valve (120) and filling said accumulator (122) with a brake fluid, said accumulator (122) is of predetermined volume, and
measuring a second pressure after said accumulator (122) is filled, and wherein
determining level of said wear of brake pads (136) comprises,
calculating pressure drop based on difference between said first pressure and second pressure, and
determining wear of brake pads (136) based on said pressure drop in comparison to standard pressure difference pre-stored in a memory element of said controller (130) said standard pressure difference is pressure difference for said brake pad (136) without wear.

10. The method as claimed in claim 7, wherein said hydraulic braking system (100) is an Anti-lock Braking System (ABS) with built-in pressure sensor (112) and without active pressure generation.