Hydraulic brake actuators and related methods

Abstract

Example hydraulic brake actuators and related methods are disclosed herein. An example hydraulic brake actuator includes a rotary valve disposed in a bore of a housing. The rotary valve includes a shaft rotatably disposed within a sleeve. The sleeve and the shaft have ports that align at certain rotational positions to create a flow path between the bore and an inner chamber of the shaft. The example hydraulic brake actuator also includes a pump coupled to the shaft to increase and decrease a pressure within the inner chamber of the shaft.

What is claimed is: 
     
         1 . A machine readable storage medium comprising instructions that, when executed, cause a machine to at least:
 activate a motor of a hydraulic brake actuator to pump fluid out of a brake until the brake is open;   activate the motor at a predetermined speed to pump fluid into the brake;   measure a pressure of the fluid in the brake; and   determine an amount of pad wear of the brake based on a run time of the motor until a threshold pressure is reached.   
     
     
         2 . The machine readable storage medium of  claim 1 , wherein the motor is activated to rotate a pump in a first direction to pump the fluid out of the brake and the motor is activated to rotate the pump in a second direction to pump fluid into the brake. 
     
     
         3 . The machine readable storage medium of  claim 1 , further including displaying the amount of pad wear via an infotainment system of a vehicle. 
     
     
         4 . The machine readable storage medium of  claim 3 , wherein the instructions, when executed, cause the machine to determine the amount of pad wear in response to activation of a pad check request from the infotainment system. 
     
     
         5 . The machine readable storage medium of  claim 1 , wherein the instructions, when executed, cause the machine to determine whether the brake is open based on a pressure of the fluid at an outlet of the hydraulic brake actuator. 
     
     
         6 . The machine readable storage medium of  claim 1 , wherein the instructions, when executed, cause the machine to, prior to determining the amount of pad wear, compare the pressure of the fluid in the brake to the threshold pressure and deactivate the motor when the pressure of the fluid in the brake meets the threshold pressure. 
     
     
         7 . The machine readable storage medium of  claim 1 , wherein the instructions, when executed, cause the machine to determine the amount of pad wear by determining a linear displacement of a brake piston of the brake based on the run time of the motor and comparing the linear displacement to a threshold displacement. 
     
     
         8 . The machine readable storage medium of  claim 1 , wherein the hydraulic brake actuator is coupled to the brake, the hydraulic brake actuator including a reservoir of the fluid. 
     
     
         9 . A method of checking a brake pad of a brake on a vehicle, the method comprising:
 activating a motor of a hydraulic brake actuator to pump fluid out of the brake until the brake is open;   activating the motor at a predetermined speed to pump fluid into the brake;   deactivating the motor when a pressure of the fluid in the brake meets a threshold pressure; and   determining, via a brake control system, an amount of pad wear of the brake pad based on a run time of the motor.   
     
     
         10 . The method of  claim 9 , further including displaying, via an infotainment system of the vehicle, the amount of pad wear. 
     
     
         11 . The method of  claim 9 , further including measuring the pressure of the fluid in the brake via a sensor at an outlet of the hydraulic brake actuator. 
     
     
         12 . The method of  claim 9 , wherein the determining of the amount of pad wear includes:
 determining a linear displacement of a brake piston of the brake based on the run time of the motor; and   comparing the linear displacement to a threshold displacement.   
     
     
         13 . An apparatus comprising:
 a vehicle brake including a brake pad;   a hydraulic brake actuator including a motor, a pump, and a reservoir; and   a brake control system to:   activate the motor to pump fluid out of the brake until the brake is open;   activate the motor at a predetermined speed to pump fluid into the brake;   determine a pressure of the fluid in the brake; and   determine an amount of pad wear of the brake based on a run time of the motor until a threshold pressure is reached.   
     
     
         14 . The apparatus of  claim 13 , further including an infotainment system to display the amount of pad wear. 
     
     
         15 . The apparatus of  claim 13 , further including a pad check request button, the brake control system to determine the amount of pad wear in response to activation of the pad check request button. 
     
     
         16 . The apparatus of  claim 13 , wherein the hydraulic brake actuator is coupled to the brake. 
     
     
         17 . The apparatus of  claim 13 , wherein an outlet of the hydraulic brake actuator is fluidly coupled to a fluid port on the brake, wherein the hydraulic brake actuator includes a pressure sensor at the outlet, and wherein the brake control system is to determine the pressure of the fluid in the brake based on a pressure of the fluid at the outlet measured by the pressure sensor. 
     
     
         18 . The apparatus of  claim 13 , wherein the pump is a bi-directional pump. 
     
     
         19 . The apparatus of  claim 18 , wherein the bi-directional pump is a radial piston pump. 
     
     
         20 . The apparatus of  claim 13 , wherein the brake is a disc brake or a drum brake.