US-12623644-B2 - Vehicle brake system

Abstract

A vehicle includes wheels, brakes to control speeds of the wheels, and a hydraulic fluid source in fluid communication with the brakes. The vehicle includes a computer storing instructions to determine that speeds of the wheels are zero and actuate the hydraulic fluid source to provide hydraulic fluid to a first set of one or more of the brakes at a first pressure sufficient to maintain the vehicle body at a present position and to provide hydraulic fluid at a volumetric rate to one or more of the brakes not in the first set, and, while providing hydraulic fluid at the volumetric rate to a brake not in the first set, detect second pressures of the brake not in the first set. The instructions include instructions to determine a volume-pressure curve for the brake not in the first set based on the volumetric rate and the second pressures.

Inventors

• Matthew Johnson
• Colton Knopf
• Daniel Joseph Dunn

Assignees

• FORD GLOBAL TECHNOLOGIES, LLC

Dates

Publication Date

20260512

Application Date

20220422

Claims (20)

1. 1 . A vehicle, comprising: a vehicle body; a plurality of wheels supported by the vehicle body; a plurality of brakes operatively coupled to the wheels to control speeds of the wheels; a hydraulic fluid source in fluid communication with the brakes; and a computer having a processor and a memory storing instructions executable by the processor to: determine that speeds of the wheels are zero; after determining the speeds of the wheels are zero, actuate the hydraulic fluid source to provide hydraulic fluid to a first set of one or more of the brakes at a first pressure sufficient to maintain the wheels at the speed of zero and to provide hydraulic fluid at a volumetric rate to one or more of the brakes not in the first set; while providing hydraulic fluid at the volumetric rate to a brake not in the first set, detect second pressures of the brake not in the first set; and based on the volumetric rate and the second pressures, determine a volume-pressure curve defining brake pressure as a function of hydraulic fluid volume delivered to the brake not in the first set.
2. 2 . The vehicle of claim 1 , wherein the instructions include instructions to actuate the hydraulic fluid source to provide hydraulic fluid to the brake not in the first set based on the volume-pressure curve for the brake not in the first set.
3. 3 . The vehicle of claim 1 , wherein the instructions include instructions to: after determining the volume-pressure curve for the brake not in the first set, provide hydraulic fluid to a second set of one or more of the brakes at the first pressure sufficient to maintain the wheels at the speed of zero and to provide hydraulic fluid at a volumetric rate to a brake not in the second set, while providing hydraulic fluid at the volumetric rate to the brake not in the second set, detecting third pressures of the brake not in the second set, and determine a second volume-pressure curve for the brake not in the second set based on the volumetric rate and the third pressures.
4. 4 . The vehicle of claim 3 , wherein the first set and the second set are different.
5. 5 . The vehicle of claim 1 , wherein the hydraulic fluid source includes a pump and a plurality of valves operatively coupled between the pump and the brakes to control fluid flow from the pump to the brakes.
6. 6 . The vehicle of claim 5 , wherein the instructions to actuate the hydraulic fluid source to provide hydraulic fluid to the first set of one or more of the brakes at the first pressure include instructions to: while a first set of one or more of the valves connecting the pump to the first set of one or more of the brakes are at an open position, actuating the pump to provide hydraulic fluid to the first set of one or more of the brakes at the first pressure, and then, actuating the first set of valves to a closed position.
7. 7 . The vehicle of claim 6 , wherein the instructions include instructions to actuate the pump to provide hydraulic fluid at the volumetric rate to the brake not in the first set and detect the second pressures of the brake not in the first set while the first set of valves are at the closed position.
8. 8 . The vehicle of claim 1 , wherein each of the brakes includes a disc, and brake pad, and a caliper operative to control movement of the brake pad relative to the disc.
9. 9 . The vehicle of claim 8 , wherein the volume-pressure curve includes a first portion corresponding to movement of the pad prior to contact with the disc and a second portion subsequent to the pad contacting the disc.
10. 10 . The vehicle of claim 1 , wherein the instructions include instructions to, in response to determining the speeds of the wheels are zero and before actuating the hydraulic fluid source to provide hydraulic fluid to the first set of one or more of the brakes at the first pressure, predict that the speeds of the wheels will be zero for a predetermined amount of time.
11. 11 . A vehicle, comprising: a vehicle body; a plurality of wheels supported by the vehicle body; a plurality of brakes operatively coupled to the wheels to control speeds of the wheels; a hydraulic fluid source in fluid communication with the brakes; and a computer having a processor and a memory storing instructions executable by the processor to: determine the vehicle is in a park mode; in response to determining the vehicle is in the park mode, actuate the hydraulic fluid source to provide hydraulic fluid at a volumetric rate to one of the brakes, while providing hydraulic fluid at the volumetric rate to the one of the brakes, detect pressures of the one or more of the brakes; and based on the volumetric rate to the one of the brakes and the pressures of the one or more of the brakes, determine a volume-pressure curve defining brake pressure as a function of hydraulic fluid volume delivered to the one of the brakes.
12. 12 . The vehicle of claim 11 , wherein the instructions include instructions to actuate the hydraulic fluid source to provide hydraulic fluid to the one of the brakes based on the volume-pressure curve for the one of the brakes.
13. 13 . The vehicle of claim 11 , wherein the instructions include instructions to: after determining the volume-pressure curve for the one of the brakes, provide hydraulic fluid to a second of the brakes at the volumetric rate, while providing hydraulic fluid at the volumetric rate to the second of the brakes, detect second pressures of the second of the brakes, and determine a second volume-pressure curve for the second of the brakes based on the volumetric rate and the second pressures.
14. 14 . The vehicle of claim 11 , wherein the hydraulic fluid source includes a pump and a plurality of valves operatively coupled between the pump and the brakes to control fluid flow from the pump to the brakes.
15. 15 . The vehicle of claim 14 , wherein the instructions to actuate the hydraulic fluid source to provide hydraulic fluid at a volumetric rate to the one of the brakes includes instructions to command a valve of the plurality of valves corresponding to the one of the brakes to an open position and valves of the plurality of valves corresponding to another one or more of the brakes to a closed position.
16. 16 . The vehicle of claim 11 , wherein each of the brakes includes a disc, and brake pad, and a caliper operative to control movement of the brake pad relative to the disc.
17. 17 . The vehicle of claim 16 , wherein the volume-pressure curve includes a first portion corresponding to movement of the pad prior to contact with the disc and a second portion subsequent to the pad contacting the disc.
18. 18 . A method, comprising: determining that speeds of wheels of a vehicle are zero; after determining the speeds of the wheels are zero, actuating a hydraulic fluid source to provide hydraulic fluid to a first set of one or more of the brakes at a first pressure sufficient to maintain the vehicle body at a present position and to provide hydraulic fluid at a volumetric rate to one or more of the brakes not in the first set; while providing hydraulic fluid at the volumetric rate to a brake not in the first set, detecting second pressures of the brake not in the first set; based on the volumetric rate to the brake not in the first set and the second pressures of the brake not in the first set, determining a volume-pressure curve for the brake not in the first set; and actuating the brake not in the first set based on the volume-pressure curve.
19. 19 . The method of claim 18 , wherein actuating the hydraulic fluid source to provide hydraulic fluid to the first set of one or more of the brakes at the first pressure includes, while a first set of one or more valves connecting a pump to the first set of one or more of the brakes are at an open position, actuating the pump to provide hydraulic fluid to the first set of one or more of the brakes at the first pressure, and, then, actuating the first set of valves to a closed position.
20. 20 . The method of claim 18 , wherein the volume-pressure curve includes a first portion corresponding to movement of a brake pad prior to contact with a brake disc and a second portion subsequent to the brake pad contacting the brake disc.

Description

BACKGROUND Vehicles typically includes a braking system that resists the motion of the vehicle to thereby slow and/or stop the vehicle. The braking system may include friction brakes such as disc brakes, drum brakes, band brakes, and so on; regenerative brakes; any other suitable type of brakes; or a combination. The braking system is in communication with and receives input from the computer and/or a human operator. The human operator may control the braking subsystem via, e.g., a brake pedal. The braking system may be actuated based on a volume-pressure curve that indicates a relationship between volume provided to a brake and pressure at such brake. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a vehicle with a plurality of brakes. FIG. 2 is a partial cross section of one of the brakes. FIG. 3 is a schematic of a hydraulic fluid source for the brakes. FIG. 4 is a block diagram of components of the vehicle. FIG. 5 is an example illustration of a volume-pressure curve. FIG. 6 is a schematic of a neural network for determining a portion of the volume-pressure curve. FIG. 7 is a flow chart illustrating a process for determining the volume pressure curve and controlling the brakes. DETAILED DESCRIPTION A vehicle includes a vehicle body and a plurality of wheels supported by the vehicle body. The vehicle includes a plurality of brakes operatively coupled to the wheels to control speeds of the wheels. The vehicle includes a hydraulic fluid source in fluid communication with the brakes. The vehicle includes a computer having a processor and a memory storing instructions executable by the processor to determine that speeds of the wheels are zero. The instructions include instructions to, after determining the speeds of the wheels are zero, actuate the hydraulic fluid source to provide hydraulic fluid to a first set of one or more of the brakes at a first pressure sufficient to maintain the vehicle body at a present position and to provide hydraulic fluid at a volumetric rate to one or more of the brakes not in the first set. The instructions include instructions to, while providing hydraulic fluid at the volumetric rate to a brake not in the first set, detect second pressures of the brake not in the first set. The instructions include instructions to determine a volume-pressure curve for the brake not in the first set based on the volumetric rate and the second pressures. The instructions may include instructions to actuate the hydraulic fluid source to provide hydraulic fluid to the brake not in the first set based on the volume-pressure curve for the brake not in the first set. The instructions may include instructions to, after determining the volume-pressure curve for the brake not in the first set, provide hydraulic fluid to a second set of one or more of the brakes at the first pressure sufficient to maintain the vehicle body at a present position and to provide hydraulic fluid at a volumetric rate to a brake not in the second set. The instructions may include instructions to, while providing hydraulic fluid at the volumetric rate to the brake not in the second set, detecting third pressures of the brake not in the second set. The instructions may include instructions to determine a second volume-pressure curve for the brake not in the second set based on the volumetric rate and the third pressures. The first set and the second set may be different. The hydraulic fluid source may include a pump and a plurality of valves operatively coupled between the pump and the brakes to control fluid flow from the pump to the brakes. The instructions to actuate the hydraulic fluid source to provide hydraulic fluid to the first set of one or more of the brakes at the first pressure may include instructions to while a first set of one or more of the valves connecting the pump to the first set of one or more of the brakes are at an open position, actuating the pump to provide hydraulic fluid to the first set of one or more of the brakes at the first pressure, and, then, actuating the first set of valves to a closed position. The instructions may include instructions to actuate the pump to provide hydraulic fluid at the volumetric rate to the brake not in the first set and detect the second pressures of the brake not in the first set while the first set of valves are at the closed position. Each of the brakes may include a disc, and brake pad, and a caliper operative to control movement of the brake pad relative to the disc. The volume-pressure curve may include a first portion corresponding to movement of the pad prior to contact with the disc and a second portion corresponding to subsequent the pad contacting the disc. The instructions may include instructions to, in response to determining the speeds of the wheels are zero and before actuating the hydraulic fluid source to provide hydraulic fluid to the first set of one or more of the brakes at the first pressure, predict that the vehicle body will be