TITLE

A device for detecting an wear of a break pad in a braking system in a vehicle

Field of the invention

This disclosure relates to a device for monitoring and detecting wear of a brake pad in a braking system in a vehicle.

Background of the invention:

A brake pad made of a friction absorbing material is pressed against a metal rotor, or disc, attached to a rotating axle or wheel. The disc moves with the wheel and the caliper remains stationery. A piston on one side of the disc pushes an inner brake pad until it makes contact with the braking surface. The piston pushes a caliper body with an outer brake pad so pressure is applied to both sides of the disc. The brake pads are intended to be slowly ablated during repeated braking applications. Wear-through of the brake pads can create an emergent brake failure. The resultant metal-to-metal contact can erode expensive parts. Brake pad sensors are used to inform vehicle operators of an impending wear-through. However, conventional brake pad sensor may induce noise and require replacement whenever the brakes are replaced. Such brake pad sensing systems may further require additional parts, can be time-consuming to install, and can be incompatible with original equipment manufacturer (OEM) components.

An US patent 6302241 discloses a brake pad wear sensor attached to a backing plate of a brake pad. The sensor comprises a metal arm extending to one side of the brake pad. A tab made from a dielectric material projects from a free end of the arm in the same direction that the brake pad extends from the backing plate. The dielectric material is selected so the tab wears at the same rate as the brake pad. A capacitance changes as the dielectric material wears away. The capacitance is used to indicate the remaining amount of brake pad life on a digital readout.

Brief description of the accompanying drawings:

An embodiment of the disclosure is described with reference to the following accompanying drawings;

Figure 1 illustrates a braking system in a vehicle in accordance with an embodiment of this invention; and

Figure 2 illustrates a flowchart for monitoring an uneven wear of a brake pad in a braking system in accordance another embodiment of with this invention.

Detailed description of the embodiments:

Figure 1 illustrates a device for detecting wear of a brake pad 12 in a braking system in a vehicle according to one embodiment of the invention. The braking system 10 comprises the brake pad 12 which is connected to a brake cylinder 14 for applying braking force to a wheel 24. The braking system 10 also comprises a brake line 26 connecting the brake cylinder 14 and a master cylinder 16.The braking system 10 comprises a motor 18 connected to the master cylinder 16 and a control unit 20 controlling the motor 18. The control unit 20 detects the wear of the brake pad 12 based on vibrations sensed at the motor 18 due to the movement of the brake pad 22 and the brake cylinder 14 when the vehicle is in motion.

Further the construction of the different components of the braking system 10 and the working of the braking system 10 is explained below.

The braking system 10 comprises a brake pedal 22 connected to the motor 18 and the control unit 20. When the vehicle 50 is in motion and when a user applies brake by pressing the brake pedal 22, the brake pad 12 gets into contact with the wheel 24 of the vehicle 50 and stops the movement of the vehicle 50. When the user presses the brake pedal 22, the braking system 10 transmits the force from the brake pedal 22 through an incompressible fluid. Since actual braking requires more force to stop the vehicle 50, the ^{— —}

braking system 10 uses additional components like the motor 18 to boost the force and to pump the fluid. Force applied at one point is transmitted to another point using the incompressible fluid. The brakes transmit the force to the wheel 24 through the brake pad 12.

In a hydraulic braking system, when the brake pedal 22 is pressed, a push-rod exerts force on a piston in the master cylinder 16, causing fluid from a fluid tank to flow into a pressure chamber. Due to this, a pressure is increased in the entire hydraulic system, forcing the fluid through the brake lines 26 to the brake cylinder 14 corresponding to each wheel 24. The brake cylinder pistons then apply force to the corresponding brake pad 12, pushing them against wheel 24. The friction between the brake pad 12 and the wheel 24 causes a braking torque to be generated, slowing the vehicle.

Figure 2 illustrates a flowchart of a method of detecting wear of a brake pad in a braking system according to one embodiment of the invention .The braking system 10 comprises a brake cylinder 14, a brake line 26, a master cylinder 16, a motor 18 and a control unit 20 as explained in the previous paragraphs. In step SI, vibrations at the motor 18 of the braking system 10 due to the vibrations of the brake pad 12 and the brake cylinder 14 are sensed. In step S2, the wear of the brake pad 12 is detected based on the sensed vibrations.

When the vehicle 50 is in motion and when the user presses the brake pedal 22, the force exerted at the brake pedal 22 is transferred to the brake pad 12 via the brake cylinder 14 and the brake line 26. The incompressible fluid present in the brake line 26 is used to transfer the brake force to the wheel 24 through the brake pad 12. During this process, due to the movement of the brake cylinder 14 and the brake pad 12, multiple vibrations are generated in the braking system 10. The vibrations produced by the brake pad 12 when stopping the wheel 24 are transferred to the motor side via the brake line 26. The motor 18 experiences high frequency harmonics due to these vibrations. The control unit 20 upon determining the high frequency harmonics at the motor 18, compares the frequency generated at the motor 18 with a predefined value. If the compared frequency is different from the predefined value, the control unit 20 detects the wear in the brake pad 12. When the control unit 20 determines the wear of the brake pad 12, it alerts the user via a human machine interface (HMI) present in a dashboard. When the brake pad 12 is in a healthy state (i.e. without the wear), the harmonics on the motor 18 due to a constant force at brake pedal 22 will be constant as there won't be any change in the frequency of load of the motor 18, due to the absence of the vibrations at the motor 18.

In one embodiment of the invention, the braking system 10 comprises an electronic stability control (ESP). Instead of the motor and the control unit, the ESP is used to detect the wear of the brake pad 12. The vibrations from the brake pad 12 that are transferred via the brake cylinder 14 and the brake line 26 are sensed at the ESP with the help of at least one sensor present in the system. The ESP is placed between the brake cylinder 14 and master cylinder 16, splitting the brake line 26 into two parts. The vibrations at the brake pad 12 are transferred through brake cylinder 14 and along a first part of brake line 26, to the ESP. The pressure sensor is attached to brake line 26, to measure the pressure and providing the values to the ESP. The ESP can then monitor the, and compare it to a predefined value. The ESP detects the wear of the brake pad based on the comparison result.

With the above device 40 and the method of detecting the wear of the brake pad 12, the brake pad state will be known to the user through the alert/warning. The alert can be an audio or video. No additional component is used in detecting the wear of the brake pad 12 which makes a cost effective solution.

It should be understood that embodiments explained in the description above are only illustrative and do not limit the scope of this disclosure. 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.