| 摘要 |
A diaphragm pump operated by vacuum pressure and having a switching arrangement to control the continuous alternations between the intake stroke caused by vacuum pressure and the working stroke caused during venting by a spring after the end of each stroke. The switching arrangement consists of a crack-open valve between vacuum pressure chamber and a space continually connected to atmosphere, and a plunger, fastened to the diaphragm; the length of the plunger is variable through a spring clutch. The special action of the switching arrangement is based on the fact that the plunger requires a larger force for cracking the valve than afterwards for keeping it open. This is accomplished by having a differential pressure, act in the closing direction on the valve, and eliminating this force after opening, causing the spring-loaded plunger to extend to its full length and to keep open the valve during the entire working stroke of the diaphragm. |
