Pilot Valve

Pilot Valve

Outline
^ The pilot valve reduces line pressure and adjusts to the pilot pressure. Pilot pressure is adjusted to the fixed pressure irrelevant of driving conditions and operates as a signal pressure for each solenoid valve.

Operation
^ Spring force is applied to the bottom end of the valve and moves the valve upward. Conversely, pilot pressure (9) is applied to the top end of the valve and pushes the valve downward. Pilot pressure (9) and spring force maintain the balance. By this balance, line pressure (5) is depressurized and adjusted to the fixed pilot pressure. When pilot pressure (9) is lower than the spring force, the pilot valve moves upward and opens line pressure oil passage (5). This forces the line pressure to flow through oil passage (5) to oil passage (9) and pressurizes pilot pressure (9). Pressurized pilot pressure (9) moves the valve downward and closes the oil passage of the line pressure (5). This causes the pilot pressure to not pressurize.
^ When pilot pressure (9) is greater than the spring force, the valve moves downward and opens drain port (X). This causes pilot pressure (9) to depressurize. When pilot pressure (9) is depressurized, the force to push the valve downward decreases and the valve moves up and drain port (X) closes. This causes the pilot pressure to not depressurize. Thus, pilot pressure (9) is adjusted to the fixed pressure according to the balance with the spring force.