| 摘要 |
914,343. Respiratory apparatus. PYE Ltd. Feb. 4, 1960 [Feb. 6, 1959], No. 4296/59. Class 81 (2). A respirator in which the duration of expiration and inspiration is controlled by an electronic timing circuit includes an over-riding trigger device controlling the timing circuit to cause the respirator to change its respiratory phase if the patient makes an attempt at voluntary respiration. Respiratory gas is supplied continuously through a change-over valve 2 to an inspiratory bellows 1 and thence through an inspiratory control valve 4 to a face mask 5. Expired air is drawn into an expiratory bellows 7 by way of an expiratory control valve 6. The inspiratory and expiratory valves each comprise a poppet valve 4a, 6a and a non-return valve 4b, 6b. The poppet valves are both connected to the armature 9 of a solenoid 10 which is energized by an electronic timing circuit, e.g. a multivibrator, to open the expiratory valve during the expiratory part of the respiratory cycle. The solenoid is de-energized under the control of the timing circuit or when the timing circuit is out of use to permit the opening of the inspiratory valve by a spring 12. The expiratory and inspiratory bellows are connected between a fixed plate 29 and a plate 13 which is pivotally connected by arms 14, 15 to the chassis of the apparatus. Inflation of the inspiratory bellows causes the expiratory bellows to expand, thus creating a negative pressure which induces exhalation. The negative pressure is controlled by a variable orifice 27. In the event that the patient inspires during the expiratory part of the respiratory cycle, an adjustable trigger mechanism comprising a pressure-sensitive diaphragm 24 and a microswitch 25 operates to switch the respiratory cycle to the inspiratory part. If desired, the change-over valve may be operated so that the gas supply by-passes the inspiratory bellows and the inspiratory valve and a manual control bag 22 may be inserted between the mask and the expiratory valve. Specification 914,342 is referred to. |
