To provide the vacuum necessary for the operation of the vacuum brake booster, the car is equipped with a vacuum pump that creates a vacuum in addition to that available in the intake manifold or separately from it in the case when the natural vacuum created by the engine is not enough, for example, during cold start, intensive throttle dampers, driving in high altitude areas, 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 modes, a vacuum is created that exceeds the value necessary for the operation of the amplifier.
This disadvantage is devoid of an electric vacuum pump. A switch mounted on the vacuum pump is used to adjust the vacuum value. When a greater vacuum value is needed, the vacuum switch closes, while the relay windings close the contacts and connect the vacuum pump electric motor to ground, supplying it with a voltage of 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, due to which the pump run time is reduced. A check valve is used to prevent the air flow from moving in the wrong direction.
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