Methods and systems are provided for controlling an aspirator shut-off valve in an engine of a hybrid vehicle. One example method includes opening the aspirator shut-off valve following a shut-down command to the engine when engine speed is between a first engine speed and a second engine speed, the first engine speed being lower than an idle speed and the second engine speed occurring before an imminent engine stop. The example method further includes not opening the aspirator shut-off valve between the first engine speed and the second engine speed if an oxygen content of an emission control device is at or near a threshold.

Methods and systems are provided for controlling an aspirator shut-off valve in an engine of a hybrid vehicle. One example method includes opening the aspirator shut-off valve following a shut-down command to the engine when engine speed is between a first engine speed and a second engine speed, the first engine speed being lower than an idle speed and the second engine speed occurring before an imminent engine stop. The example method further includes not opening the aspirator shut-off valve between the first engine speed and the second engine speed if an oxygen content of an emission control device is at or near a threshold.

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 method of controlling vacuum pressure for vehicle braking may include checking whether a vehicle is idle or enters a deceleration state, comparing an engine vacuum pressure and a booster vacuum pressure of the vehicle with a preset reference value, checking whether a valve control system of the vehicle is operable when the engine vacuum pressure and the booster vacuum pressure are lower less than the preset reference value, controlling the valve control system when the valve control system is operable; and controlling an air conditioner (A/C) or an alternator of the vehicle when the valve control system is inoperable.

A brake control system for a vehicle, the brake control system including a master cylinder, a brake line for communicating brake fluid between the master cylinder and a brake, a fluid reservoir in fluid communication with the brake line during non-braking conditions, and means for selectively moving brake fluid into and/or out of the fluid reservoir. The means for selectively moving brake fluid into and/or out of the fluid reservoir includes means for removing gas from the fluid reservoir, and is configured to move brake fluid into the fluid reservoir, so that brake fluid is moved along the brake line in a direction towards the master cylinder, during non-braking conditions. Upon receiving a signal of an anticipated brake event, brake fluid may also be moved out of the fluid reservoir, so that brake fluid is moved along the brake line in a direction away from the master cylinder.

A brake control system for a vehicle, the brake control system including a master cylinder, a brake line for communicating brake fluid between the master cylinder and a brake, a fluid reservoir in fluid communication with the brake line during non-braking conditions, and means for selectively moving brake fluid into and/or out of the fluid reservoir. The means for selectively moving brake fluid into and/or out of the fluid reservoir includes means for removing gas from the fluid reservoir, and is configured to move brake fluid into the fluid reservoir, so that brake fluid is moved along the brake line in a direction towards the master cylinder, during non-braking conditions. Upon receiving a signal of an anticipated brake event, brake fluid may also be moved out of the fluid reservoir, so that brake fluid is moved along the brake line in a direction away from the master cylinder.

A vacuum generator/amplifier system for gas applications and a brake booster generation method uses a vacuum amplifier system including a multi-lumen defining member comprising a modified venturi geometry having a converging section leading to a throat (lumen segment of minimum ID diameter), followed by a straight section culminating in to a diverging section and a port for output vacuum which is located after the throat at the beginning of the straight section. The converging section has a sinusoidal shape leading to the point of convergence, also called the throat, with a minimum internal lumen diameter D, and generates an amplified vacuum at the output with a gain ratio of four to one, with substantially reduced parasitic losses, even at low flows.

A vacuum generator/amplifier system for gas applications and a brake booster generation method uses a vacuum amplifier system including a multi-lumen defining member comprising a modified venturi geometry having a converging section leading to a throat (lumen segment of minimum ID diameter), followed by a straight section culminating in to a diverging section and a port for output vacuum which is located after the throat at the beginning of the straight section. The converging section has a sinusoidal shape leading to the point of convergence, also called the throat, with a minimum internal lumen diameter D, and generates an amplified vacuum at the output with a gain ratio of four to one, with substantially reduced parasitic losses, even at low flows.

A compensation control system is provided for preventing braking inconvenience of a flex brake that compensates for brake hydraulic pressure only for initial braking when a brake mode is forcibly switched, thus allowing a driver to recognize a change in braking force, and thereby improving stability when a vehicle is driven. The control system forcibly switches the brake mode, selected by a driver when a booster system fails, into a normal brake mode, and compensates to reduce the magnitude of brake hydraulic pressure, which is to be reduced when the brake mode is forcibly switched, during initial braking.