| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent occurrence of noises caused by repetitive opening and closing of a valve body of a pressure control valve. SOLUTION: A valve chamber 33 housing a valve body 4 which closes a valve chamber side opening 32a of a canister port chamber 32 is divided into a first chamber 331 containing a valve surface 4a of the valve body 4 as a chamber wall surface, and a second chamber 332 containing a back surface 4b as a chamber wall surface. The chambers 331, 332 are respectively communicated with a fuel tank port chamber 31. Especially, the second chamber 332 is communicated with the fuel tank port chamber 31 through a throttle flow passage 4023. When negative pressure inside the fuel tank port chamber 31 is increased and the valve body 4 is opened, air is flowed from the canister port chamber 32 to the fuel tank port chamber 31. Even in the case that the negative pressure on an immediately downstream part of the valve body 4 is lowered, at this time, valve closing is retarded by decreasing the speed of negative pressure reduction at the back surface 4b of the valve body 4 due to function of the throttle flow passage 4023. Short cycle closing of the valve body 4 is thus avoided.</p> |
