| 摘要 |
<p>PCT No. PCT/SE91/00342 Sec. 371 Date Jan. 7, 1992 Sec. 102(e) Date Jan. 7, 1992 PCT Filed May 15, 1991 PCT Pub. No. WO91/17651 PCT Pub. Date Nov. 28, 1991.A pulsator has two valve devices (1, 2), each of which is adapted to alternately subject a pulsation space to two different pressures. In order to avoid the two valve devices (1, 2) from disturbing each other during the alternations between the two pressures a third valve device (23) is arranged, for closing communication between one of the valve devices and the lower one of said two pressures, when the other valve device is operated to alternate the pressure in the pulsation space from the lower one to the higher one of said two pressures.</p> |
