Braking system and method for a vehicle

Patent metadata

Field	Value
Publication number	US-2016332610-A1
Application number	US-201514899822-A
Country	US
Kind code	A1
Filing date	Feb 4, 2015
Priority date	Feb 4, 2014
Publication date	Nov 17, 2016
Grant date	—

Abstract

A control system for a vehicle includes an electric drive system associated with a first set of wheels (e.g., rear wheels) of a vehicle and a drive system control unit configured to control the electric drive system to selectively provide electric motive power to the first set of wheels to propel the vehicle and electric retarding to slow the vehicle. The system further includes a friction brake system having a first friction brake unit associated with the first set of wheels and a second friction brake unit associated with a second set of wheels (e.g., front wheels) of the vehicle. The drive system control unit is further configured, in at least one mode of operation, to independently control the first and second friction brake units to concurrently apply different levels of friction braking to the first and second sets of wheels, to reduce wear unevenness.

First claim

What is claimed is:

1 . A control system, comprising:
an electric drive system associated with a first set of wheels of a vehicle; a drive system control unit configured to control the electric drive system to selectively provide electric motive power to the first set of wheels to propel the vehicle and electric retarding to slow the vehicle; and a friction brake system having a first friction brake unit associated with the first set of wheels and a second friction brake unit associated with a second set of wheels of the vehicle; wherein the drive system control unit is further configured, in at least one mode of operation, to control the friction brake system to sequentially apply plural different first braking pressures to the first set of wheels, and concurrent with the first braking pressures, respectively apply plural second braking pressures to the second set of wheels, wherein the respective first braking pressures and the second braking pressures are different from one another and are applied non-proportionally.

2 . The system of claim 1 , further comprising:
a brake pedal position transducer associated with a brake pedal of the vehicle, wherein the brake pedal position transducer is electrically connected to the drive system control unit and is configured to provide a signal to the drive system control unit indicative of a position of the brake pedal; wherein the drive system control unit is configured, responsive to at least one of the position of the brake pedal being moved from an unactuated position of the brake pedal to stopping within a designated range of the unactuated position or a rate of change of a movement of the brake pedal being below a designated threshold, to determine one or more of the first braking pressures and one or more of the second braking pressures, and control the friction brake system to automatically apply the one or more of the first braking pressures to the first set of wheels and the one or more of the second braking pressures to the second set of wheels, the first and second braking pressures including non-zero braking pressures.

3 . The system of claim 2 , wherein the drive system control unit is configured, responsive to the at least one of the position of the brake pedal being moved from the unactuated position of the brake pedal to stopping within the designated range or the rate of change of the movement of the brake pedal being below the designated threshold, to control the electric drive system to provide the electric retarding to the first set of wheels concurrent with the one or more of the first braking pressures being applied to the first set of wheels and the one or more of the second braking pressures being applied to the second set of wheels.

4 . The system of claim 2 , wherein:
the drive system control unit is configured to determine: a first wear of the first friction brake unit based at least in part on brake pressures and speeds at which the first friction brake unit is applied over a first time period of operation of the vehicle; and a second wear of the second friction brake unit based at least in part on brake pressures and speeds at which the second friction brake unit is applied over the first time period; and the drive system control unit is configured to control the first braking pressures and the second braking pressures for a total wear of the first braking unit to be no more than 10% different from a total wear of the second braking unit over a second time period that is at least as long as the first time period.

5 . The system of claim 4 , wherein the first set of wheels comprises rear wheels of the vehicle and the second set of wheels comprises front wheels of the vehicle.

6 . The system of claim 4 , wherein the designated range is 25% of a total travel distance of the brake pedal from the unactuated position to a fully actuated position of the brake pedal.

7 . The system of claim 4 , wherein a gross vehicle operating weight of the vehicle is at least 250 metric tons.

8 . The system of claim 2 , further comprising a friction brake control unit, wherein:
the system is configured for the drive system control unit to control the first and second brake units when the at least one of the position of the brake pedal is moved from the unactuated position of the brake pedal to stopping within the designated range of the unactuated position or the rate of change of the movement of the brake pedal is below the designated threshold; and the system is further configured for the friction brake control unit to control the first and second brake units, to apply a third braking pressure to the first set of wheels and a fourth braking pressure to the second set of wheels, respectively, the third and fourth braking pressures being greater than the first and second braking pressures and based at least in part on the position of the brake pedal or the rate of change of the movement of the brake pedal, when at least one the position of the brake pedal is moved from the unactuated position of the brake pedal to stopping outside the designated range of the unactuated position or the rate of change of the movement of the brake pedal is above the designated threshold.

9 . The system of claim 2 , wherein the first set of wheels comprises rear wheels of the vehicle and the second set of wheels comprises front wheels of the vehicle.

10 . The system of claim 2 , wherein the designated range is 25% of a total travel distance of the brake pedal from the unactuated position to a fully actuated position of the brake pedal.

11 . The system of claim 2 , wherein a gross vehicle operating weight of the vehicle is at least 250 metric tons.

12 . The system of claim 1 , further comprising:
a brake pedal position transducer associated with a brake pedal of the vehicle, wherein the brake pedal position transducer is electrically connected to the drive system control unit and is configured to provide a signal to the drive system control unit indicative of a position of the brake pedal; wherein the drive system control unit is configured, responsive to at least one of the position of the brake pedal being moved from an unactuated position of the brake pedal to stopping within a designated range of the unactuated position or a rate of change of a movement of the brake pedal being below a designated threshold, to determine one or more of the second braking pressures, control the friction brake system to automatically sequentially apply the one or more of the second braking pressures to the second set of wheels, and concurrently with the second braking pressures being applied to the second set of wheels and the first braking pressures being zero, control the electric drive system to provide the electric retarding to the first set of wheels.

13 . The system of claim 12 , wherein the first set of wheels comprises rear wheels of the vehicle and the second set of wheels comprises front wheels of the vehicle.

14 . The system of claim 12 , wherein the designated range is 25% of a total travel distance of the brake pedal from the unactuated position to a fully actuated position of the brake pedal.

15 . The system of claim 12 , wherein a gross vehicle operating weight of the vehicle is at least 250 metric tons.

16 . The system of claim 1 , further comprising:
a friction brake control unit configured to control application of the first and second friction brake units at least partially in response to a position of a brake pedal of the vehicle; and a brake pedal position transducer associated with the brake pedal of the vehicle, wherein the brake

Assignees

• Gen Electric

Inventors

• Wolff Jeffrey
• Young Henry
• Brown Timothy
• Vallejo Carlos
• Cillessen Sean
• Nedley Kenneth
• Bench Larry

Classifications

• B60T13/586

  the retarders being of the electric type · CPC title

• B60T1/10

  by utilising wheel movement for accumulating energy, e.g. driving air compressors · CPC title

• B60T13/662 Primary

  characterised by specified functions of the control system components · CPC title

• B60T13/588

  both fluid and mechanical assistance or drive · CPC title

• B60T7/042

  by electrical means, e.g. using travel or force sensors · CPC title