Braking arrangement and method for adjusting brake pressure in a braking arrangement including an anti-lock brake system

1 . A braking arrangement for a vehicle, comprising:

a source of pressurized air for supplying pressurized air;

a wheel comprising a tire and a first pneumatic brake arrangement, the first pneumatic brake arrangement including a brake chamber and a brake;

an anti-lock brake valve (ABV) in a line between the brake chamber and the source of pressurized air, the ABV opening to connect the brake chamber to the source of pressurized air and closing to disconnect the brake chamber from the source of pressurized air; and

an electronic control unit (ECU) configured to open and close the ABV during an anti-lock braking operation, the ECU being configured to open the ABV during the anti-lock braking operation in response to a pressure at an inlet port of the ABV and a slippage between the tire and a road surface;

wherein the ECU is configured to adjust an opening timing of the ABV relative to a pressure wave generated in the line when the ABV closes, the adjustment being a function of an estimated friction coefficient between the tire and the road surface, such that:

in a first mode, the ECU opens the ABV when the pressure wave is at or arriving at the inlet port; and

in a second mode, the ECU opens the ABV when the pressure wave is moving away from the inlet port.

2 . The braking arrangement of claim 1 , the braking arrangement comprising a sensor configured to estimate a friction level between the tire and a surface on which the tire is driven, wherein the ECU is configured to set or adjust the rate at which pressure in the brake chamber is increased during the anti-lock braking operation by adjusting opening timing of the ABV as a function of an estimated friction level.

3 . The braking arrangement of claim 2 , wherein the ECU is configured to, prior to adjusting the rate at which pressure in the brake chamber is increased during the anti-lock braking operation by adjusting opening timing of the ABV as a function of an estimated friction coefficient, open and close the ABV during the anti-lock braking operation according to a predetermined opening timing of the ABV established as function of a predetermined friction coefficient.

4 . The braking arrangement of claim 3 , wherein the ECU is configured to increase the rate at which pressure in the brake chamber is increased during the anti-lock braking operation in response to an estimation by the sensor of the estimated friction coefficient above the predetermined friction coefficient.

5 . The braking arrangement of claim 4 , wherein the ECU is configured to decrease the rate at which pressure in the brake chamber is increased during the anti-lock braking operation in response to the estimated friction coefficient below the predetermined friction coefficient.

6 . The braking arrangement of claim 3 , wherein the ECU is configured to decrease the rate at which pressure in the brake chamber is increased during the anti-lock braking operation in response to the estimated friction coefficient below the predetermined friction coefficient.

7 . The braking arrangement of claim 1 , wherein the ECU is configured to increase the rate at which pressure in the brake chamber is increased during the anti-lock braking operation by adjusting opening timing of the ABV in a first mode so that a pressure wave generated in the line upstream of the inlet port to the ABV when the ABV closes and above a pressure at which air is supplied at the inlet port to the ABV by the source of pressurized air is at, or approaching or arriving at the inlet port to the ABV when the ABV is opened.

8 . The braking arrangement of claim 7 , wherein opening timing of the ABV in the first mode is a function of length of the line between the inlet port to the ABV and a rebound point at which the pressure wave generated in the line upstream of the inlet port to the ABV stops traveling upstream away from the inlet port to the ABV and starts traveling downstream toward the ABV.

9 . The braking arrangement of claim 7 , wherein the ECU is configured to decrease the rate at which pressure in the brake chamber is increased during the anti-lock braking operation by adjusting opening timing of the ABV in a second mode so that the pressure wave generated in the line upstream of the inlet port to the ABV when the ABV closes is moving away from the inlet port to the ABV is opened and a pressure below the pressure at which air is supplied at the inlet port to the ABV by the source of pressurized air is present at the inlet port to the ABV.

10 . The braking arrangement of claim 9 , wherein the ECU is configured to adjust opening timing of the ABV in the first mode when a friction coefficient between the tire and a surface in contact with the wheel is above a first predetermined friction level.

11 . The braking arrangement of claim 10 , wherein the ECU is configured to adjust opening timing of the ABV in the second mode when a friction coefficient between the tire and a surface in contact with the tire is below a second predetermined friction level.

12 . The braking arrangement of claim 9 , wherein the ECU is configured to adjust opening timing of the ABV in the first mode or the second mode as a function of wheel slip information and braking pressure and torque.

13 . The braking arrangement of claim 7 , wherein the ECU is configured to adjust opening timing of the ABV in the first mode when a friction coefficient between the tire and a surface in contact with the tire is above a first predetermined friction level.

14 . The braking arrangement of claim 1 , wherein the ECU is configured to decrease the rate at which pressure in the brake chamber is increased during the anti-lock braking operation by adjusting opening timing of the ABV in a mode so that a pressure wave generated in the line upstream of the inlet port to the ABV when the ABV closes is moving away from the inlet port to the ABV is opened and a pressure below the pressure at which air is supplied at the inlet port to the ABV by the source of pressurized air is present at the inlet port to the ABV.

15 . The braking arrangement of claim 14 , wherein the ECU is configured to adjust opening timing of the ABV in the second mode when a friction coefficient between the tire and a surface in contact with the tire is below a second predetermined friction level.

16 . A method for changing performance of a braking arrangement for a vehicle, the vehicle and braking arrangement comprising a source of pressurized air for supplying pressurized air, a wheel comprising a tire and a first pneumatic brake arrangement, the first pneumatic brake arrangement including a brake chamber and a brake, and an anti-lock brake valve (ABV) in a line between the brake chamber and the source of pressurized air, the ABV opening to connect the brake chamber to the source of pressurized air and closing to disconnect the brake chamber from the source of pressurized air, the method comprising:

opening and closing the ABV during an anti-lock braking operation to supply and stop supplying, respectively, air from the source of pressurized air to the brake chamber; and

opening the ABV during the anti-lock braking operation in response to a pressure at an inlet port of the ABV and a slippage between the tire and a road surface;

wherein the method is adjusting an opening timing of the ABV relative to a pressure wave generated in the line when the ABV closes, the adjustment being a function of an estimated friction coefficient between the tire and the road surface, such that:

in a first mode, opening the ABV when the pressure wave is at or arriving at the inlet port; and

in a second mode, opening the ABV when the pressure wave is moving away from the inlet port.

17 . The method of claim 16 , wherein the vehicle and the braking arrangement comprise a sensor configured to estimate a friction level between the tire and a surface on which the tire is driven, the method comprising adjusting the rate at which pressure in the brake chamber is increased during the anti-lock braking operation by adjusting opening timing of the ABV as a function of an estimated friction level.

18 . The method of claim 17 , further comprising, prior to adjusting the rate at which pressure in the brake chamber is increased during the anti-lock braking operation by adjusting opening timing of the ABV as a function of an estimated friction coefficient, opening and closing the ABV during the anti-lock braking operation according to a predetermined opening timing of the ABV established as function of a predetermined friction coefficient.

19 . The method of claim 18 , further comprising increasing the rate at which pressure in the brake chamber is increased during the anti-lock braking operation in response to an estimation by the sensor of the estimated friction coefficient being above the predetermined friction coefficient.

20 . The method of claim 18 , further comprising decreasing the rate at which pressure in the brake chamber is increased during the anti-lock braking operation in response to the estimated friction coefficient being below the predetermined friction coefficient.

21 . The method of claim 16 , further comprising increasing the rate at which pressure in the brake chamber is increased during the anti-lock braking operation by adjusting opening timing of the ABV in a first mode so that a pressure wave generated in the line upstream of the inlet port to the ABV when the ABV closes and above a pressure at which air is supplied at the inlet port to the ABV by the source of pressurized air is at, or approaching, or arriving at the inlet port to the ABV when the ABV is opened.

22 . The method of claim 16 , further comprising decreasing the rate at which pressure in the brake chamber is increased during the anti-lock braking operation by adjusting opening timing of the ABV in a second mode so that the pressure wave generated in the line upstream of the inlet port to the ABV when the ABV closes is moving away from the inlet port to the ABV is opened and a pressure below the pressure at which air is supplied at the inlet port to the ABV by the source of pressurized air is present at the inlet port to the ABV.