Abstract: A rectilinear motion proportional solenoid assembly includes a cylindrical housing containing an electromagnetic coil having a longitudinal coaxial bore. The housing contains magnetic material for providing a flux path for the magnetic field produced by the coil. A generally cylindrical magnetic pole piece element is inserted into the bore and a movable armature assembly of magnetic material is supported within the bore for movement along the longitudinal axis of the coil by a pair of thin, flexible suspension springs. One of the springs is located within the bore adjacent to one end of the magnetic pole piece whereat an axial gap between the pole piece and the armature is formed. A second spring is located within the housing within the vicinity of a radial air gap between the armature and the housing.

Abstract: A tube securing mechanism for retaining a resilient tube on a rigid tube connector, for use in a patient breathing circuit of a respirator. In one embodiment of the invention, the tube securing mechanism is a clamp (22) having a circular band (30) with a peripheral break in it, and two integral arcuate portions (32 and 34) hinged to the band and to each other, to form a toggle mechanism by means of which the clamp is opened and closed. A pair of integral teeth (50) on the band and another pair (52) on one of the arcuate portions of the clamp, engage each other to protect the hinges of the clamp from unnecessary stress. In another embodiment of the invention, a tube (10) has two internal annular features (64 and 66) that are complementary to corresponding annular features (60 and 62) on a connector (12'), to hold the tube more securely on the connector.

Abstract: A diaphragm (40) for use in an exhalation valve (20) in a respirator. The diaphragm is tapered in thickness to provide substantially reduced vibration and noise. The diaphragm flexes and peels up from its valve seat (32) to provide the improved operation at low flow rates through the valve.

Abstract: A pressure switch having a movable bellows (14) in a pressure chamber (12), a first electrical contact (16) movable with the bellows, a three-dimensional cam (18) and a second electrical contact (20) resiliently biased to follow the cam. In the preferred embodiment of the invention, the cam has a radius that linearly increases with the angular position of the cam, and is tapered toward one end for all regions about its periphery except at a point of maximum radius. Calibration at low pressure is effected by rotating the cam to its maximum-radius point, applying a standard low pressure to the chamber (12) and rotating the chamber about a threaded coupling (26) until the contacts (16) and (20) are at the point of closing. Calibration at high pressure is effected by rotating the cam to its minimum-radius point, applying a standard high pressure to the chamber, and adjusting the axial position of the cam until the contacts are at the point of closing.