Tire pressure control valve

PURPOSE: To prevent damage to a diaphragm and to enhance airtightness by causing a relief force to work on a control piston via a movable pressure load surface so formed to separate a pressure chamber communicated with a valve connection from a relief chamber. CONSTITUTION: To increase tire pressure, compressed air is supplied to a first valve connection 15 so that a control piston 21, together with a valve member 26, is lifted from a valves seat 16 by pressure working on a first control surface 24. At the same time, pressure within a first chamber part 121 leading to a pressure chamber 33 works on a diaphragm 32 to press the diaphragm 32 rightward, As a result, a force in an opening direction is transmitted to a control piston 21 via a control rod 42 to assist the opening of the valve member 26, The compressed air is thereby supplied into a tire, and when the desired pressure is reached, the air is abruptly exhausted from the valve connection 15. Airtightness can be enhanced by this constitution since no a diaphragm is used in a chamber part on which the pressure within the tire works. COPYRIGHT: (C)1990,JPO