CARBURATORE CON VALVOLA A SCORRIMENTO AZIONATA DA PRESSIONE NEGATIVA

PROBLEM TO BE SOLVED: To provide a constant vacuum slide throttle valve type carburetor having a simple constitution, a reduced manufacturing cost, a slide throttle calve movement swift and excellent in acceleration performance, and a high air suction efficiency. SOLUTION: A negative pressure chamber 14 is disposed on the upper side of a diaphragm 5 and an atmospheric pressure chamber 13 is disposed on the lower side of the diaphragm 5 by connecting an upper cover 4 to an upper end wall of a carburetor body 6 with a diaphragm 5 placed between them. A cup-shaped slide throttle valve 22 is supported in a liftable manner in a cylindrical part 17 crossing perpendicularly with an intake passage 33 of the carburetor body 6. The upper end of a negative pressure actuating valve 26 inserted into the slide throttle valve 22 is connected to the diaphragm 5. The stroke of the negative pressure actuating valve 26 is smaller than than of the slide throttle valve 22. Accordingly, only slide throttle valve 22 is actuated in a small opening range, and the slide throttle valve 22 and the negative pressure actuating valve 26 are integrally actuated in an opening range exceeding the small opening range. A lower end flange 26a of the negative pressure actuating valve 26 is inserted into the slide throttle valve 22. A spring 2a is interposed between a upper end cover plate 23 of the slide throttle valve 22 and the lower end flange 26a of the negative pressure actuating valve 26.