Air Control Valve

Air control valve contains three valves which, depending upon engine operation, directs air from air pump to either air injection nozzles or thermal reactor. In addition, should air become trapped due to a malfunction, a safety valve opens and directs air pump air to the air cleaner to prevent damage to the system. Operational conditions of air control valve are as follows:

Fig 1: Exhaust Emission Control

Courtesy of MAZDA MOTORS CORP.

1. During normal engine operation air from the air pump flows into the air control valve and passes through the check valve to the air injection nozzles. When engine speed exceeds 4000±200 RPM, an electronic control box actuates the solenoid which shuts off vacuum to air control valve vacuum chamber. Spring pressure opens the air cut valve which shuts off air to air injection nozzles and allows the air from the air pump to pass to the thermal reactor cooling circuit.
2. During periods of deceleration when engine speed is below 4000±200 RPM, the coasting valve of the deceleration control system shuts off vacuum to the air control valve vacuum chamber. This causes spring pressure to open air cut valve, which in turn shuts off air to air injection nozzles and allows the air from the air pump to pass to the thermal reactor cooling circuit.
3. The relief valve is controlled by air pressure in the air injection system. When air pressure exceeds 1.3-2.0 lbs./sq.in. (0.11-0.14 Kg./sq. cm) valve opens and directs a quantity of air through the thermal reactor cooling system. This action maintains a constant pressure of air flowing to the air injection nozzles.