Patent GB-218260-A (GB)
Title: Improvements in and relating to grinding or pulverizing apparatus
IPC: B02C25/00
Filed: 1924-05-29
Abstract: 218,260. Raymond Bros. Impact Pulverizer Co.., (Assignees of Raymond, F. I.). June 26, 1923, [Convention date]. Fluid-actuated valves; valves controlled by pilot or relay valves.-A multiple-way slide valve is actuated by suction acting on a diaphragm to open successively a series of ports leading to pneumatics actuating detents controlling pawl and ratchet feed mechanism of a grinding and pulverizing mill. The device comprises a web enclosed in a casing 72 having at one end a flexible annular diaphragm 73 secured to a central plate 75 formed with a projection 80 which is secured to a pin 99 in the forked end 81 of the arm 82 of a bell-crank lever 83 pivoted to the base 85 of the casing 72. The vacuum chamber 76 between the diaphragm and the end section 77 of the casing communicates with the interior of the mill casing through a pipe 78. A spring 86 is attached to the upper end of the arm 82 and to the casing 72, and the horizontal arm 91 of the lever carries weights 94. A slide-valve 101 consisting of upper and lower plates 102, 103 secured together, is connected by a rod 100 to the pin 99 and slides in a channelled guideplate 104 secured to the web 70. The ports 66 - - 69 in the web communicate with ports 106 - - 109 in the plate 104, and a pipe leads from a port 110 in the web to a nozzle which extends into the discharge pipe of the mill near the fan. The valve 101 is formed with communicating chambers 115 - - 119, the first of which communicates, for all positions of the valve, with a duct 110 through an opening 120 in the plate 103, which is formed with ports 121 - - 124 leading from the chambers 116 - - 119 and adapted to communicate in accordance with the position of the valve with the ports 106 - - 109 respectively. Through ports 125 - - 129 are provided in the valve for venting the ducts 66 - - 69 and the pawl-controlling pneumatics connected therewith. As the vacuum in the mill increases, the valve 101 moves from right to left and the ducts 66 - - 69 are evacuated consecutively, the evacuation of each duct being continued until the next succeeding one of the series has been effected; one pawl is always active until the next succeeding pawl has been released and engaged with its ratchet so that there is no interruption of the feed. In a modification, the controller for governing the application of the suction to the pneumatic is arranged to ensure quick action by the pneumatic so that the pawl will be snapped into and out of engagement with its ratchet instantaneously, and to give the regulating-mechanism a lag so that the pawl will not be moved into and out of engagement with every slight variation of the vacuum in the mill. The controller 159, Fig. 11, comprises a casing in sections 160, 161, 162 with flexible diaphragms 163, 164 clamped between the sections. A pipe 158 communicates with a chamber 165 formed by a web 166 within the section 160 and is connected by a flexible pipe to the pneumatic. A pipe 167 leads from a suction nozzle in the discharge pipe of the mill near the fan to a chamber 169 formed by a web 170 in the section 161. Openings 171, 173 in the diaphragm 163 put the chamber 172 above the diaphragm into communication with the chambers 169, 174 respectively, and a pipe 175 connects the upper end of the nozzle in the discharge pipe with a chamber 176 below the diaphragm 164. Filter discs 181 are secured by means of a nut 182 to the top of the section 160, and the space 183 below the filter communicates by a duct 185 with a chamber 184 directly above the diaphragm 164. A depending stud 187 on a plate 186 secured to the diaphragm 164 bears on one end a lever 190 loosely and pivotally supported by a link 192a on a stud 192. The other end of the lever is formed with a seat 191 for a spring 193 adjustable by means of a screw 195. A valve 202 has a limited movement in an annular recess 203 in a guide-stem 201 secured by a screw 200 to the diaphragm plate 186, and is normally held at the bottom of the recess bv a spring 204, The valve-seat 207 on the lower web 206 of the section 161 has an opening 208 for the stem 201. A valve 211 having a seating 20 in the upper web 209 of the section 160 is, in its lower position, adapted to engage with a seat 212 on the web 166. The valve 211 is supported on the upper diaphragm 163. When the mill becomes overloaded, the increased suction in the chamber 176 of the controller acts upon the diaphragm 164 and pulls down the valve-stem 201 and, when the upper shoulder of the recess 203 comes against the valve 202, the valve will be unseated; as soon as the pressure on the underside of the valve is relieved, the spring 204 will move the valve quickly against the lower shoulder of the recess 203, fully opening the port between the chambers 174, 184 to allow atmospheric.air to enter the chamber 174 so that the pressure under the diaphragm 163 will be greater than that above it and the valve 211 will therefore be raised against its upper seat 210 shutting off the pawl-lifting pneumatic from the atmosphere and putting it in communication with the vacuum chamber 172. When normal vacuum is re-established within the mill, the spring 193 will rock the lever 190 and bring the valve 202' to its seat, thereby equalizing the pressures on opposite sides of the diaphragm 163 so that the valve 211 is moved to its lower seat and the vacuum shut off from the pawl-lifting pneumatic.