| 摘要 |
PROBLEM TO BE SOLVED: To provide a back flow prevention device for an oil supply pipe capable of putting a back flow amount of fuel into a scope of allowable control with high precision. SOLUTION: This back flow prevention device for an oil supply pipe is provided with a first oil supply pipe 400 connected to an oil supply port, a second oil supply pipe 500 which is connected to a fuel tank and is made of an elastic material, and a check valve 100 storing a valve element 200 inside a valve case 300. The valve case 300 has an insertion cylindrical part 320 inserted into the first oil supply pipe 400, a guide cylindrical part 310 surrounding the valve element 200, and an annular collar part 330 formed therebetween. The insertion cylindrical part 320 of the check valve is inserted into an end part of the first oil supply pipe 400, and the second oil supply pipe 500 is externally inserted into outer periphery of the first oil supply pipe 400 to connect the oil supply port with the fuel tank. If fuel flows backward from the fuel tank into the oil supply port, the valve element 200 comes into contact with a valve seat to block a flow passage, and a part where the collar part 330 bites inner periphery of the second oil supply pipe 500 prevents fuel leakage.
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