GB299363A - Improvements in fluid pressure engines for operating and controlling doors - Google Patents

Abstract

299,363. National Pneumatic Co., (Assignees of Rowntree, H.). Oct. 24, 1927, [Convention date]. Operating and controlling doors hydraulically and pneumatically. - A fluid pressure engine having double-acting pistons for actuating doors is provided with a valve for controlling the admission and exhaust of fluid to and from the ends of the cylinder including a valve chamber connected by passages and by means of said valve to the pressure and exhaust ends of the cylinder, the said chamber having an exhaust port and a second valve actuated by said fluid pressures and adapted to open the exhaust port when the ratio of said fluid pressures reaches a pre-determined amount. In the arrangement shown, the supply of pressure fluid to an exhaust from the doublepistons 4, 5 connected to the door is controlled by a rotary valve 15. This valve is rotatable by means of a lever 35 and is provided with throughports 18, 19 communicating with a chamber 22 that is supplied with operating pressure fluid through an inlet 24. The valve 15 is also provided with surface ports 16, 17 interconnected by a channel 21. With the valve 15 positioned as shown, operating pressure fluid passes through the port 19 and passages 33, 11 to the righthand side of the piston 5 to cause the pistons to move to the left-hand end of the cylinder 1. At the same time pressure fluid on the other side of the piston 4 is forced through the channels 12 and 34, ports 17, 16 and pipe 25 into the chamber 23, to cause the piston 28 to move to the right and open the exhaust valve 30. Should the door meet with an obstruction so as to stop the movement of the pistons 4, 5, pressure fluid will exhaust from the chamber 23 until the pressure in the chamber 22, acting on the piston 27, is able to move the differential pistons 27, 28 to the left and close the exhaust valve 30. When the obstruction is removed and the pistons 4, 5 resume the movement to the left the pressure in the chamber 23 is increased until the exhaust valve 30 is again opened.