Brake system with shift out of park support
A method for controlling brake pressure during a shift of a vehicle out of park may include determining that a first status condition is met when the vehicle is in park with an electric parking brake applied, determining that a second status condition is met when the vehicle is not moving, responsive to detecting a shift of the vehicle out of park when the first and second status conditions are both met, directing a build-up of brake pressure until a brake pressure target is reached, and holding the brake pressure at the brake pressure target until a release condition is met.
1. A vehicle control system comprising:
a gear selector operably coupled to a transmission of the vehicle to shift the vehicle between various states including at least drive, reverse and park;
a braking torque module operably coupled to brake hardware of the vehicle to provide braking force or braking torque to the brake hardware based on a brake pedal position;
an electric park brake; and
a hold controller operably coupled to a sensor network of the vehicle to receive vehicle status information to:
determine that the vehicle is in park on a slope with the electric parking brake applied;
determine that the vehicle is not moving;
responsive to detecting a shift of the vehicle out of park, direct a build-up of brake pressure until a brake pressure target is reached, the brake pressure target being a larger of a brake pressure requested by a driver of the vehicle based on a brake pedal input and a hold pressure required to hold the vehicle based on a current vehicle state; and
holding the brake pressure at the brake pressure target until a release condition is met,
wherein the current vehicle state comprises an amount of slope and an estimation of vehicle mass.
2. The vehicle control system of claim 1 , wherein the release condition comprises receiving a driver input indicating a pressure release request.
3. The vehicle control system of claim 1 , wherein the release condition comprises elapse of a predetermined period of time.
4. The vehicle control system of claim 3 , wherein the predetermined period of time is a delay time to handover to another braking function.
5. The vehicle control system of claim 1 , wherein the brake pressure target is determined based at least in part on a fixed value defined based on vehicle type, as defined by vehicle model or modification.
6. The vehicle control system of claim 1 , wherein the hold pressure is determined from a table mapping the amount of slope and the estimation of vehicle mass to an estimated holding force.
7. A vehicle control system comprising:
a gear selector operably coupled to a transmission of the vehicle to shift the vehicle between various states including at least drive, reverse and park;
a braking torque module operably coupled to brake hardware of the vehicle to provide braking force or braking torque to the brake hardware based on a brake pedal position;
an electric park brake; and
a hold controller operably coupled to a sensor network of the vehicle to receive vehicle status information to:
determine that the vehicle is in park on a slope with the electric parking brake applied;
determine that the vehicle is not moving;
responsive to detecting a shift of the vehicle out of park, direct a build-up of brake pressure until a brake pressure target is reached, the brake pressure target being selected at least in part based on an amount of slope of the vehicle and an estimation of vehicle mass; and
holding the brake pressure at the brake pressure target until a release condition is met,
wherein the brake pressure target is determined based at least in part on a fixed value defined based on vehicle type, as defined by vehicle model or modification.
8. The vehicle control system of claim 7 , wherein the release condition comprises receiving a driver input indicating a pressure release request.
9. The vehicle control system of claim 7 , wherein the release condition comprises elapse of a predetermined period of time.
10. The vehicle control system of claim 7 , wherein the brake pressure target is a larger of a brake pressure requested by a driver of the vehicle based on a brake pedal input and a hold pressure required to hold the vehicle based on a current vehicle state.
11. The vehicle control system of claim 10 , wherein the hold pressure is determined from a table mapping the amount of slope and the estimation of vehicle mass to an estimated holding force.
12. The vehicle control system of claim 11 , wherein the current vehicle state comprises the amount of slope and the estimation of vehicle mass.
13. A vehicle control system comprising:
a gear selector operably coupled to a transmission of the vehicle to shift the vehicle between various states including at least drive, reverse and park;
a braking torque module operably coupled to brake hardware of the vehicle to provide braking force or braking torque to the brake hardware based on a brake pedal position;
an electric park brake; and
a hold controller operably coupled to a sensor network of the vehicle to receive vehicle status information to:
determine that the vehicle is in park on a slope with the electric parking brake applied;
determine that the vehicle is not moving;
responsive to detecting a shift of the vehicle out of park, direct a build-up of brake pressure until a brake pressure target is reached;
holding the brake pressure at the brake pressure target until a release condition is met; and
releasing the brake pressure at a selected release rate responsive to the release condition being met,
wherein the brake pressure target is a larger of a brake pressure requested by a driver of the vehicle based on a brake pedal input and a hold pressure required to hold the vehicle based on a current vehicle state.
14. The vehicle control system of claim 13 , wherein the release condition comprises receiving a driver input indicating a pressure release request or elapse of a predetermined period of time.
15. The vehicle control system of claim 13 , wherein the current vehicle state comprises an amount of slope and an estimation of vehicle mass.
16. The vehicle control system of claim 15 , wherein the hold pressure is determined from a table mapping the amount of slope and the estimation of vehicle mass to an estimated holding force.
17. The vehicle control system of claim 16 , wherein the hold pressure is determined based at least in part on a fixed value defined based on vehicle type, as defined by vehicle model or modification.