Pressure control valve

In a pressure control valve provided with a valve body, comprising:

• a relief poppet for permitting and preventing communication between:
• a pressure supply port formed in one of opposite end portions of said valve body;
• and a relief port formed in an intermediate portion of said valve body, said relief poppet being slidably mounted in said valve body;
• a sleeve-like piston poppet for permitting communication between:
• a back-pressure chamber formed in said valve body;
• and said pressure supply port, said sleeve-like piston poppet being slidably mounted in said relief poppet;
• and
• a pilot poppet movably inserted in a passage formed in said valve body in a downstream side of said back-pressure chamber, said pilot poppet being separated from a seat portion of said passage to permit communication between:
• said back-pressure chamber;
• and a low-pressure supply port (formed in the other of said opposite end portions of said valve body) when pressurized fluid in said back-pressure chamber increases in pressure to a valve greater than or equal to a predetermined pressure, the improvement wherein:
• a large-diameter portion of said piston poppet is larger in cross-sectional area than an area of an aperture defined by said seat portion of said passage formed in said valve body;
• and
• an annular opening area is defined between:
• a conical inner peripheral surface of said passage, which conical inner peripheral surface extends from said seat portion of said passage toward said back-pressure chamber, said conical surface decreasing in diameter from said seat portion toward said back-pressure chamber;
• and an outer peripheral surface of said pilot poppet, which outer peripheral surface is oppositely disposed in a diametrical direction from said conical inner peripheral surface of said passage so as to face the same, said annular opening area gradually reducing its cross-sectional area toward said seat portion of said passage to form a throttle portion for restricting the flow of said pressurized fluid passing through said passage.