GB821903A - Improvements in or relating to pilot operated fluid flow control valves - Google Patents

Abstract

821,903. Valves. HAYS MANUFACTURING CO. July 16, 1957 [Aug. 6, 1956], No. 22540/57. Class 135. [Also in Group XXXV] A main valve closure 16, which embodies a resilient washer 23, is maintained on a seat 24 by fluid pressure in the inlet 14 leaking past the surface 65 of a piston 17 and into a chamber 66 thereabove, the piston 17 being integral with the closure 16 and, since the area above the piston is greater than that below, the closure is forced on to its seat. Upon energizing a solenoid 39 an iron plunger 52 is lifted to open an orifice 61 through the piston 17 and relieves the pressure in chamber 66 whereby the piston 17 rises and the main closure is unseated. The closure 16 has a V-shaped slot 20 to gradually cut-off the fluid flow as the valve closes and thus eliminate water hammer. An aperture 25 in the seat partition 11 enables a small flow of liquid to take place at all times to ensure that the thermostat in an air conditioning installation is maintained at a representative temperature. The plunger 52 slides in a non-magnetic tube 34 soldered to the valve bonnet 31 and having a counterbore 38 at the lower end whilst at the upper end of the tube is a stop member which comprises a tubular copper shading coil 47 and a solid metallic shading pole 49. In the bottom of the bore 53 is a rubber or plastic member 54 impregnated with magnetic particles, which member in the elevated position of the plunger 52 receives the coil 47 and pole 49, the latter attracting the member 54 between alternating current cycles in the solenoid 39 to hold the plunger 52 against vibration, the rubber or plastic serving as a buffer and a magnetic path. On the lower end of the plunger 52 is a rubber tip 59 of larger diameter than the plunger having a pilot valve closure 60 cooperating with the orifice 61 in the piston 17, the tip 59 abutting the bonnet 31 and tube 34 when the solenoid 39 is energized, thereby reducing noise.