GB1109691A - Improvements in or relating to arrangements for detecting icing conditions - Google Patents

Abstract

1,109,691. Detecting icing conditions. SANGAMO WESTON Ltd. May 4, 1965 [May 5, 1964], No.18665/64. Heading G1X. An arrangement for detecting conditions in which ice is liable to be formed on surfaces e.g. roadways comprises a conical flexible moisture absorbent element 10, which is periodically subjected to a displacing force, means also being provided for detecting whether the element is sufficiently stiffened to resist the displacing force. The periphery of the element 10, which is preferably of a woven fabric, is secured to a plate 11, while its apex is connected to the upper end of a cylindrical weight rod 16 by means of a cap 17. A nose 22 at the lower end of the rod 16 bears on a cam disc 23 rotated by a motor 27. A depression 24 is formed in the disc 23 which periodically e.g. every 5 or 6 minutes, allows the weight rod 16 to fall by a predetermined amount. If the element 10 has absorbed sufficient moisture and is sufficiently frozen, the weight rod 16 will not fall but will remain in the position shown in Fig. 1. The rod 16 carries a stirrup member 30, having side limbs 29, one on each side of the rod 16, and mounted on pins 28, the limbs being connected by a junction limb 31. Each limb 29 has an extension as 33, for engagement with a corresponding abutment on a rocker plate 42 pivoted on a pin 43. As the nose 22 passes the depression 24, a radially extending cam surface on the disc 23 engages a bell crank lever (not shown) to engage the limb 31 and push the member 30 to the left as viewed in Fig. 1. The abutments on the rocker plate 42 are at different heights and arranged to be actuated by this movement by one or the other of the extensions on the limbs 29 depending on whether the rod 16 has fallen or not. If the element 10 is frozen and the rod does not fall, then the plate 42 is moved to actuate and hold actuated a micro-switch (not shown). If the rod does fall, then the plate 42 is moved to disengage the switch. The detector may be provided with a suitable screen, as 49, if desired. In another embodiment, the element 10 is displaced by cam actuation of a lever, whose fulcrum point is changed if the element is frozen, thus causing switch contacts to be actuated. In a further alternative arrangement the element 10 is a strip of material pivotally suspended at its upper end and periodically subjected to a deflecting force mid-way along its length. If the element is frozen its lower end operates switch contacts to actuate a relay, and means are provided to hold the relay actuated until the next deflection of the element.