A brake control device to be applied to a vehicle having a hydraulic brake generating a hydraulic braking force, which is a braking force converted from a fluid pressure to a wheel of the vehicle, and an electric parking brake generating an electric braking force, which is a braking force different from the hydraulic braking force, on the wheel by a wheel brake mechanism driven by a motor. The brake control device includes an electric parking brake controller for determining a current target value, which is a target value of an electric current through the motor, by using a target braking force, and for controlling the electric parking brake by using the current target value. The electric parking brake controller is configured to estimate the fluid pressure in the hydraulic brake by using a current detection value, which is a detection value of an electric current through the motor.

A vacuum brake booster includes: at least one movable wall, which separates a working chamber and a vacuum chamber in the vacuum brake booster from one another, and a control valve unit, which is coupled to the at least one movable wall, the control valve unit comprising a guide sleeve and an actuation piston guided displaceably in the control valve unit, which actuation piston is actuatable by way of a force input member which can be coupled in particular to a brake pedal, the actuation piston having at least one first valve seat, which in the open state is used to connect the working chamber to the ambient atmosphere.

A vacuum brake booster includes: at least one movable wall, which separates a working chamber and a vacuum chamber in the vacuum brake booster from one another, and a control valve unit, which is coupled to the at least one movable wall, the control valve unit comprising a guide sleeve and an actuation piston guided displaceably in the control valve unit, which actuation piston is actuatable by way of a force input member which can be coupled in particular to a brake pedal, the actuation piston having at least one first valve seat, which in the open state is used to connect the working chamber to the ambient atmosphere.

A vehicle air-conditioning device is provided for controlling a vehicle air-conditioning of a vehicle in accordance with a control method. The air-conditioning compressor is stopped for a first time period after a brake pedal transitions from an operated state to a non-operated state when negative pressure inside a vacuum servo is insufficient relative to a predetermined pressure while an air-conditioning compressor is operating, and The air-conditioning compressor is stopped for a second time period after the acceleration pedal has come to be in a non-operated state when an acceleration pedal is operated before the first time period elapses.

A vehicle air-conditioning device is provided for controlling a vehicle air-conditioning of a vehicle in accordance with a control method. A negative pressure, which is generated in an intake passage of the internal combustion engine by a vacuum servo that assists a brake pedal force, is estimated based on an atmospheric pressure and a pressure inside the intake passage. When a predetermined condition is established that includes a state in which the estimated negative pressure inside the vacuum servo is insufficient relative to a predetermined pressure during operation of the air-conditioning compressor, the air-conditioning compressor is stopped during a first time period, the air-conditioning compressor is operated during a second time period regardless of the predetermined condition after the first time period has elapsed, and operation of the air-conditioning compressor is controlled in accordance the states of the predetermined condition being established after the second time period has elapsed.

A vehicle air-conditioning device is provided for controlling a vehicle air-conditioning of a vehicle in accordance with a control method. A negative pressure, which is generated in an intake passage of the internal combustion engine by a vacuum servo that assists a brake pedal force, is estimated based on an atmospheric pressure and a pressure inside the intake passage. When a predetermined condition is established that includes a state in which the estimated negative pressure inside the vacuum servo is insufficient relative to a predetermined pressure during operation of the air-conditioning compressor, the air-conditioning compressor is stopped during a first time period, the air-conditioning compressor is operated during a second time period regardless of the predetermined condition after the first time period has elapsed, and operation of the air-conditioning compressor is controlled in accordance the states of the predetermined condition being established after the second time period has elapsed.

A method of securing brake booster negative pressure is provided. The method includes operating a purge pump that is connected to a canister having evaporation gas absorbed thereon and a brake booster and determining whether the evaporation gas is injected into an intake pipe by the operation of the purge pump. Whether a negative pressure of the brake booster is insufficient is determined and when the evaporation gas is being injected into the intake pipe and the negative pressure is insufficient, a degree of opening of a valve provided in a line connecting the canister and the purge pump is adjusted.

This vehicle braking control device executes automatic braking control to adjust a braking torque on the basis of a vehicle target deceleration value corresponding to a distance between the vehicle and an object in front of the vehicle, and executes anti-skid control to suppress excessive wheel slip by adjusting the braking torque on the basis of a wheel speed. The braking control device calculates an actual deceleration value corresponding to the target deceleration value, and executes feedback control on the basis of the target deceleration value and the actual deceleration value such that the actual deceleration value approaches the target deceleration value. The configuration is such that a control gain of the feedback control is reduced when anti-skid control is executed. Further, the configuration may be such that execution of feedback control is prohibited when anti-skid control is executed.

A vehicle braking system includes an assistance device, having a vacuum pump driven by an engine for communicating vacuum to a chamber of the assistance device. A control valve is interposed along a fluid line between the pump and the chamber. The control valve is in its first operative condition, where the inlet side of the vacuum pump communicates with the chamber, when the pressure within the chamber is above a predetermined value; and is in its second operative condition, where the inlet side of the vacuum pump communicates with the atmosphere, when pressure within the chamber is below a predetermined value. In this second condition the pump intakes air from and feeds air into the atmosphere, thereby reducing the energy consumption by the engine required for driving the pump during stages where, within the chamber there is a vacuum sufficient for the regular operation of the braking system.

Systems and methods for operating a vehicle that includes an engine that may be automatically stopped and started are described. In one example, an engine may be automatically stopped in response to a brake booster vacuum threshold level that is adjusted responsive to vehicle speed so that opportunities to automatically stop an engine may be increased, thereby conserving fuel.