Detecting air in a brake master cylinder and bleeding the brake master cylinder of a hydraulic power brake system
AssigneeRobert Bosch GmbH
InventorsErwin Reinke, Otmar Bussmann, Carsten Thierer, Kevin Wodrich, Ralf Kinder, Tim-Philipp Jesse
Life of this patent
Estimating the term…
Abstract
In order to detect air in a brake master cylinder within a hydraulic power brake system, a brake master cylinder pressure on actuation of the brake master cylinder is compared with a comparison pressure which prevails in the brake master cylinder when it is air-free. For bleeding, brake fluid is conveyed with a power brake pressure generator through the in this case non-actuated brake master cylinder into a pressureless brake fluid reservoir, where air escapes from the brake fluid.
Claims19
A method for a hydraulic power brake system, the hydraulic power brake system including a brake master cylinder, a brake fluid reservoir with which the brake master cylinder communicates in a non-actuated state and does not communicate in an actuated state, a pressure sensor, a power brake pressure generator, an isolation valve via which the brake master cylinder is connected to a brake circuit of the power brake system, and a power valve via which the power brake pressure generator is connected to the brake circuit of the power brake system, the method comprising:
- measuring, on actuation of the brake master cylinder and using the pressure sensor, a brake master cylinder pressure;
- comparing the measured brake master cylinder pressure with a comparison value for brake master cylinder pressure which prevails in the actuated brake master cylinder when it is air-free;
- and
- in response to a deviation of the measured master cylinder pressure from the comparison value, bleeding the brake master cylinder in a state of the hydraulic power brake system in which the brake master cylinder is non-actuated, the isolation valve is open, and the power valve is open, the bleeding being performed by the power brake pressure generator conveying brake fluid through the brake master cylinder into the brake fluid reservoir.
A method for a hydraulic power brake system, the hydraulic power brake system including a brake master cylinder, a brake fluid reservoir with which the brake master cylinder communicates in a non-actuated state and does not communicate in an actuated state, a power brake pressure generator, an isolation valve via which the brake master cylinder is connected to a brake circuit of the power brake system and a power valve via which the power brake pressure generator is connected to the brake circuit of the power brake system, the method comprising:
- periodically bleeding the brake master cylinder by:
- placing the hydraulic power brake system into a state in which the brake master cylinder is non-actuated, the isolation valve is open, and the power valve is open;
- and
- conveying, by the power brake pressure generator, brake fluid through the brake master cylinder into the brake fluid reservoir.
A hydraulic power brake system comprising:
- a brake master cylinder;
- a brake fluid reservoir with which the brake master cylinder communicates in a non-actuated state and does not communicate in an actuated state;
- a power brake pressure generator;
- an isolation valve via which the brake master cylinder is connected to a brake circuit of the power brake system;
- and
- a power valve via which the power brake pressure generator is connected to the brake circuit of the power brake system;
- wherein:
- the hydraulic power brake system is configured to bleed the brake master cylinder either:
- periodically;
- or
- in response to a determined deviation of a measured master cylinder pressure from a comparison value for brake master cylinder pressure that prevails in the brake master cylinder when the brake master cylinder is actuated and air-free, the measured master cylinder pressure being obtained by using a pressure sensor of the hydraulic power brake system to measure the brake master cylinder pressure on actuation of the brake master cylinder;
- and
- the bleeding of the brake master cylinder is performed by:
- placing the hydraulic power brake system into a state in which the brake master cylinder is non-actuated, the isolation valve is open, and the power valve is open;
- and
- conveying, by the power brake pressure generator, brake fluid through the brake master cylinder into the brake fluid reservoir.
Dependencies are inferred from the claim text.