Vacuum brake booster (Opel Insignia A)

To provide the vacuum required for the brake booster to operate, the vehicle is equipped with a vacuum pump that creates a vacuum in addition to or separately from that in the intake manifold when the natural vacuum created by the engine is insufficient, such as during cold starts, heavy throttle operation, driving the vehicle at high altitudes, or using a turbocharger.

The mechanical vacuum pump is driven by the camshaft. The performance of such a pump depends on the engine speed, which means that under certain engine operating conditions, a vacuum is created that exceeds the value required for the booster to operate.

An electric vacuum pump does not have this drawback. To regulate the vacuum value, a switch installed on the vacuum pump is used. When a higher vacuum value is required, the vacuum switch is closed, and the relay windings close the contacts and connect the vacuum pump electric motor to ground, supplying it with 12 V. When the required vacuum value is reached, the switch opens and the pump stops.

A diffuser installed between the intake manifold and the vacuum booster increases the vacuum value, thereby reducing the pump operating time. A check valve is used to prevent the air flow from moving in the wrong direction.

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