JPS6436309A - Pressure counter-weight - Google Patents

Abstract

PURPOSE:To enable a device to be operated even with quite a few amount of differential pressure, by holding the difference or the ratio of pressure by emitting a few amount of gas A from a first small hole and gas B from a second small hole in a section where the first and second holes are closed by a needle. CONSTITUTION:A gas quantity that flows from a space between the outer wall of the needle 20 and the inner wall of an outer cylinder 10 which constitutes accumulators 24 and 25 to bleed-off ports (small holes) 15 and 16 is set inversely proportional to a distance between the front end of the needle 20 and the bleed-off ports 15 and 16. When the pressure in either accumulator 24 (25) is increased a little, the needle 20 is pressed to another side 25 (24), then, the gas quantity in the bleed-off is increased, and the pressure is decreased, thereby, the needle 20 is returned to its original position. A bleed-off quantity can be enough to be set at the 1% of a quantity to be consumed outside a pressure counter-weight at the time of balancing the pressure. Also, when the pressure on either side is increased abnormally, since the needle 20 approaches to the bleed-off port 15 (16), the bleed-off quantity is increased quickly, then the pressure drops, and simultaneously, since the accumulator 25 (24) is sealed from another side completely, the needle 20 is returned to its original position quickly, then, balancing is recovered. In such a way, it is possible to keep the balancing of the pressure even when micro abnormal differential pressure is generated.