| 摘要 |
<p>A valve (1) for controlled ventilation of an inflatable sleeve of blood pressure measuring equipment comprises within a housing (3) a generally cylindrical rubber-elastic flow control body (7) with an axial bore (7a) forming part of a flow path (15) through the housing (3) from an inlet (3a) to an outlet (9). The body (7) is held at its ends and has on a circumferential surface portion thereof intermediate its ends an annular recess (7b) forming part of a pressure chamber (19). The chamber (19) is connected to the flow path (15) between inlet (3a) and bore (7a) by a branch duct (17). On ventilation of the sleeve, air under pressure is exhausted from the sleeve through inlet (3a) to the pressure chamber (19) and in dependence on the pressure difference between the inlet (3a) and outlet (9), the pressure in the chamber (19) deforms the control body (7) so as to constrict bore (7a). This varies the resistance to flow along the flow path (15) and causes the pressure in the sleeve to reduce, over a certain pressure range, at an approximately constant rate. <IMAGE></p> |
