| 摘要 |
<p>PURPOSE:To simplify construction by providing a plurality of passages in a cylinder so as to automatically change connection in series or in parallel in a suction system containing two suction pumps through a mechanical means, in case of sliding movement of the piston in the cylinder. CONSTITUTION:A pressure chamber 18 formed with a diaphragm and cylinder 12 communicated with the pressure chamber 18 through a rod hole 19 are provided in a casing 11, and a bobbin-like piston 31 on which a recessed part 32 of small diameter is formed on the center part is arranged in the cylinder 12. A rod 33 formed with a groove part 34 in the axial direction and into one body with the piston 31 is projected into the pressure chamber 18 through rod hole 19 and fixed to a diaphragm 41. First-fifth passages 101-105 are formed in the casing 11, the first passage 101 is connected to a vessel of which inner pressure is to be reduced, the second and fourth passages 102, 104 are respectively connected to the suction port 1A and the discharge port 1B of a first pump 1, the third passage 103 is connected to the suction port 2A of a second pump 2, and the fifth passage 105 is connected to the atmosphere.</p> |
