| 摘要 |
The invention relates to a pump of the type comprising a cylindro-conical body (1) defining a metering chamber (10) closed at its bottom portion by an inlet valve (11) and at its top portion by a moving piston (2) co-operating with resilient return means (3) while being carried axially by a nozzle tube (4) having a top end that projects outside the pump body and having a bottom end that is provided with at least one delivery orifice (40), the pump being characterized in that said piston (2) is slidably mounted firstly about the tube (4) between a closure position closing the delivery orifice (40) and an open position in which said orifice is fully open, and secondly in sealed peripheral contact with the inside wall of said chamber (10) between a top end-of-stroke abutment and a bottom end-of-stroke abutment; the coefficient of friction between the piston (2) and the tube (4) being less than the coefficient of friction between said piston (2) and the inside wall of the body (1). |
