GB742225A - Improvements in or relating to spirometers - Google Patents

Abstract

742,225. Spirometers. NAAMLOOZE VENNOOTSCHAP PHILIPS' GLOEILAMPENFABRIEKEN. Nov. 20, 1953 [Nov. 25, 1952], No. 32251/53. Class 81(2). A spirometer comprising a reaction member set into rotation by the air blown into the meter and a time-indicator acting independent of the amount of air being blown in is characterised in that a member is provided which records the amount of air being blown in in relationship to the time taken. The meter shown comprises two interengaging parts-a closure member 2 housing a blade wheel 8, a magnetic brake 9, a shaft 10, transmission system 12 and locating member 13 and a cylindrical drum 1 housing a recording member and a time-indicator. The latter comprises a clockwork driven disc 25 journalled in the drum and supporting a shaft 22 which lightly engages the disc without being anchored thereto and, at its upper end, carries, freely rotatable relative thereto, a frame consisting of members 15, 17 with guides 16 rigidly secured thereto. A slide member 18 carrying a recording stylus 19 is slidable over the guides 16 such motion longitudinally of the drum being imparted by a flexible tube 27 which slides over the shaft 22 and at one end is connected to the disc 25 at 28 and at the other end is connected to the member 18 such that the member and tube are rotatable relatively. When use of the meter is required the member 2 is removed from the drum and the latter lined with recording paper. The clockwork is then wound up, a key engaging the disc shaft 26 from without the drum, so that the tube 27 is wound on the disc and the member 18 moved to its lowest position. The member 2 is then secured to the drum the locating member engaging member 15 and a temporary mouthpiece 11 is provided. The patient then blows causing the wheel 8, frame and members 18 to rotate the rotation of member 17 setting off the clockwork by the removal of a pawl which hitherto has prevented such rotation. The member 18 and stylus 19 is thus caused to simultaneously rotate and move upwards the latter movement having linear relationship with time -whilst the former movement has linear relationship with the amount of air blown in. A curve is thus drawn on the recording paper. When the member 18 has reached its highest position the clockwork is stopped by the interengagement of a lever 30 and a projection 29 on the disc 25. The stylus 19 is pivotally mounted on the member 18 and is caused to swing away from the drum wall by a projection 31 at the highest position of the member 18 whilst a projection 32 causes it to engage the recording paper at the lowest position of the member 18.