Valve Operation and Air Flow

In the figure below, divided by the diaphragm, the part above X is charged with atmospheric air pressure, and the part below X is charged with tank pressure. Also, the part above Y is charged with tank pressure, and the part below Y is charged with canister pressure.

If the atmospheric air pressure port is A, tank pressure port is B, and canister pressure port is C, the airflows according to pressure difference from each port as shown in the table below.

Fig 1: Identifying Pressure Control Solenoid Valve Components

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PRESSURE CONDITION AND FLOW REFERENCE

Condition of pressure	Flow
A < B (solenoid OFF)	B → C
B < C (solenoid OFF)	C → B
Solenoid ON	B ↔ C

When A < B (solenoid OFF)

Fig 2: Air Flow When A < B (Solenoid OFF)

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When B < C (solenoid OFF)

Fig 3: Air Flow When B < C (Solenoid OFF)

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When Solenoid is ON

Fig 4: Air Flow When Solenoid ON

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