Pic. 2.214. VSV (vacuum valve): 1 - atmosphere; 2 - on the actuator; 3 - from the vacuum reservoir
Valve (pic. 2.214) controls the vacuum that is supplied to the actuator on a signal (ACIS) electronic engine control unit.
Vacuum tank
The vacuum reservoir, equipped with an internal check valve, creates a reserve of vacuum that is applied to the actuator to keep the intake air control valve fully closed even in low vacuum conditions.
Inlet control valve closed (VSV enabled)
Pic. 2.215. Scheme of operation of the inlet control valve in position «closed»
The engine ECM activates the VSV to increase the duration of the pulsation cycle, while the vacuum acts on the diaphragm of the actuator. The control valve closes. As a result, the effective length of the intake manifold is increased, and the intake efficiency in the low and medium speed range is improved due to the influence of the intake air flow dynamics, thus increasing the engine power.
Inlet control valve open (VSV off)
Pic. 2.216. Scheme of operation of the inlet control valve in position «open»
The ECM shuts down the VSV to reduce the duration of the pulsation cycle, while the actuator diaphragm is exposed to atmospheric air and the control valve opens. When the control valve is open, the effective length of the intake manifold is reduced and peak intake efficiency shifts to the high engine speed region, thus providing more power in this region.