A method for determining a vacuum degree threshold is provided including: e acquiring the current altitude signal of a vehicle; when the current altitude signal is invalid, acquiring a vacuum degree threshold and a standard working time, which correspond to a historical altitude signal received by an electronic vacuum pump of the vehicle last time, the vacuum degree threshold includes a vacuum degree turn-on threshold value and a vacuum degree turn-off threshold; acquiring the actual working time of the vacuum degree threshold corresponding to the historical altitude signal of the electronic vacuum pump when the current working cycle is completed; and when the difference between the actual working time and the standard working time exceeds a preset range, updating, according to the difference, the vacuum degree threshold corresponding to the historical altitude signal, and taking the updated vacuum degree threshold as a target vacuum degree threshold of the next working cycle.

A method for determining a vacuum degree threshold is provided including: e acquiring the current altitude signal of a vehicle; when the current altitude signal is invalid, acquiring a vacuum degree threshold and a standard working time, which correspond to a historical altitude signal received by an electronic vacuum pump of the vehicle last time, the vacuum degree threshold includes a vacuum degree turn-on threshold value and a vacuum degree turn-off threshold; acquiring the actual working time of the vacuum degree threshold corresponding to the historical altitude signal of the electronic vacuum pump when the current working cycle is completed; and when the difference between the actual working time and the standard working time exceeds a preset range, updating, according to the difference, the vacuum degree threshold corresponding to the historical altitude signal, and taking the updated vacuum degree threshold as a target vacuum degree threshold of the next working cycle.

A hydraulic braking system has a vacuum brake booster, an ESC system with a hydraulic pump for generating braking force in a wheel-specific manner in a plurality of wheel brakes, an ESC control device for driving the hydraulic pump and a hydraulic pressure sensor for determining a hydraulic pressure in the hydraulic braking system. For electrified vehicles, an electric vacuum pump is provided for supplying the vacuum brake booster, wherein the ESC control device is designed to drive the electric vacuum pump logically and electrically.

A hydraulic braking system has a vacuum brake booster, an ESC system with a hydraulic pump for generating braking force in a wheel-specific manner in a plurality of wheel brakes, an ESC control device for driving the hydraulic pump and a hydraulic pressure sensor for determining a hydraulic pressure in the hydraulic braking system. For electrified vehicles, an electric vacuum pump is provided for supplying the vacuum brake booster, wherein the ESC control device is designed to drive the electric vacuum pump logically and electrically.

A system for forming a negative pressure in a negative pressure reservoir of a brake system includes, an engine having an intake manifold and a camshaft, a vacuum pump connected to the camshaft through a clutch device and generating a pump negative pressure, a turbocharger having a compressor supplying a compressed air to the engine, a pump negative pressure line connecting the vacuum pump and the negative pressure reservoir and supplying the pump negative pressure to the negative pressure reservoir, an intake negative pressure line connecting the negative pressure reservoir and the intake manifold and supplying the intake negative pressure of the intake manifold to the negative pressure reservoir, and a negative pressure source selection apparatus configured to control opening and closing of the pump negative pressure line and the intake negative pressure line based on operation of the turbocharger.

A system for forming a negative pressure in a negative pressure reservoir of a brake system includes, an engine having an intake manifold and a camshaft, a vacuum pump connected to the camshaft through a clutch device and generating a pump negative pressure, a turbocharger having a compressor supplying a compressed air to the engine, a pump negative pressure line connecting the vacuum pump and the negative pressure reservoir and supplying the pump negative pressure to the negative pressure reservoir, an intake negative pressure line connecting the negative pressure reservoir and the intake manifold and supplying the intake negative pressure of the intake manifold to the negative pressure reservoir, and a negative pressure source selection apparatus configured to control opening and closing of the pump negative pressure line and the intake negative pressure line based on operation of the turbocharger.

A vehicle driving device includes: an engine; a brake booster including a negative pressure chamber, the brake booster amplifying a brake pressure by a negative pressure determined corresponding to a pressure inside the negative pressure chamber; a power transmission clutch disposed between the engine and a driving wheel; and a negative pressure pump configured to drive by using at least one of a torque from the engine and a torque from the driving wheel, the negative pressure pump being configured to vary the negative pressure inside the negative pressure chamber. In the vehicle driving device included in a vehicle that performs freewheeling in a state where the power transmission clutch is released and the engine is stopped, the negative pressure pump includes a control chamber configured to reduce a capacity of the negative pressure pump as a magnitude of the negative pressure inside the negative pressure chamber increases.

A system for and a method of controlling driving of a continuously-operable electronic vacuum pump includes determining conditions for allowing and disallowing first and second electronic vacuum pumps to operate for each braking situation according to vehicle state information associated with braking. The first and second electronic vacuum pumps are driven individually or concurrently according to the determined braking situation. Thus, an optimal negative pressure optimal suitable for the vehicle state information is easily supplied to a booster.

A system for and a method of controlling driving of a continuously-operable electronic vacuum pump includes determining conditions for allowing and disallowing first and second electronic vacuum pumps to operate for each braking situation according to vehicle state information associated with braking. The first and second electronic vacuum pumps are driven individually or concurrently according to the determined braking situation. Thus, an optimal negative pressure optimal suitable for the vehicle state information is easily supplied to a booster.

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 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.