| 摘要 |
The vacuum cleaner has two suction pumps (2,3), and an automatic controller that regulates vacuum and flow. The automatic controller has a flow control (4,12) that controls activation of the first and second suction pumps (2,3). The pumps are activated successively when the control vane (12) is in an initial position then in an intermediate position. A flow monitoring circuit (28,5) controls a valve (13-20) which can couple the two suction pumps either in series or in parallel, increasing suction or flow respectively. The position of the valve is controlled (30) by a piston (34) displaced by a bellows (42) controlled by pressure differential in the suction circuit. Movement of the bellows controls the balance of series and parallel coupling of the two suction circuits. |
