Patent ID: 8273985

Claim:
A junction box ( 100 ), mainly comprising a base ( 1 ) and a cover ( 2 ) snap-fitted into the base ( 1 ), being characterized in that, the cover ( 2 ) is further provided with a ventilation valve ( 3 ), and the ventilation valve ( 3 ) comprises a first hollow cylinder ( 31 ), a second hollow cylinder ( 32 ) and a waterproof air-permeable membrane ( 33 ), therein the first hollow cylinder ( 31 ) being disposed on an inner surface of the cover ( 2 ) and faces towards the base ( 1 ), the first hollow cylinder ( 31 ) having a first inner bore ( 313 ) and a bottom ( 312 ), the bottom ( 312 ) being provided with an open area ( 311 ), the first inner bore ( 313 ) being larger in area than the open area ( 311 ), the first inner bore ( 313 ) being formed with a first thread ( 314 ) on a bore wall thereof, and the bottom ( 312 ) being formed with an annular flange ( 315 ) that is protruded axially on the outside of the open area ( 311 ); the second hollow cylinder ( 32 ) being formed with a second thread ( 324 ) on an outer surface thereof to be threaded into the first thread ( 314 ) so that the second hollow cylinder ( 32 ) is received in the first hollow cylinder ( 31 ), the second hollow cylinder ( 32 ) having a first end ( 321 ), a second end ( 322 ) and a second inner bore ( 323 ) extending through the first end ( 321 ) and the second end ( 322 ), an annular groove ( 325 ) being disposed axially at the first end ( 321 ) corresponding to the annular flange ( 315 ) of the first hollow cylinder ( 31 ), and the annular groove ( 325 ) being larger in width than the annular flange ( 315 ); the waterproof air-permeable membrane ( 33 ) being disposed between the first end ( 321 ) of the second hollow cylinder ( 32 ) and the bottom ( 312 ) of the first hollow cylinder ( 31 ), and being adhered to the first end ( 321 ) of the second hollow cylinder ( 32 ); and the annular flange ( 315 ) comprising two projections ( 3151 , 3152 ) being fixed at two ends of the annular flange ( 315 ) respectively, the projections ( 3151 , 3152 ) extending into the annular groove ( 325 ), and a specific distance (D) being formed between the top of the annular flange ( 315 ) and the top of the annular groove ( 325 ), with the specific distance (D) being smaller than an axial feeding amount (S 1 ) of the first thread ( 314 ) when being threaded by one turn.