GB926885A - Electro-pneumatic compressed air brake - Google Patents

Abstract

926,885. Fluid-pressure brakes. KNORRBREMSE G.m.b.H. Nov. 13, 1959, No. 38600/59. Class 103 (1). An electro-pneumatic compressed air brake system for rail vehicles, comprises a manual pre-control valve 11 supervising the pressure in a pre-control circuit which controls through a relay valve 7 the pressure in main pipe 43 to regulate pressure in brake cylinder 65 by means of a control valve 135; pressure in the precontrol circuit in conjunction with the brake cylinder pressure actuates a switching device 59 supervising current flow in two circuits, one having an electrically-operated brake valve 175 and an electrically-operated holding valve 177 and the second including the holding valve, the arrangement being such that on energization of the first circuit the valve 175 causes brake cylinder 65 to be pressurized from source 1 by biasing control valve 135 and the holding valve 177 prevents venting of the brake cylinder. Supply pipe 1 is connected via pipe 3 to chambers 5, 9 of relay valve 7 and control valve 11, the lever 13 of which controls by cams and screws a quick-acting brake valve 17, an electric switch 21 and the tension of a spring 23 loading a diaphragm 25 having a valve seat 27. A valve 29, 31 controls admission of air to resetting chamber 33 connected to shut-off valve 35 connected to balancing reservoir 37 and chamber 39 of relay valve 7 which has diaphragm controlled valves 49, 51 and 47, 49. Pressures on opposite sides of shutoff valve 35 exist in chambers 55, 57 of pneumatic switch 59 which has a rod 61 controlling switches 77, 79 via a rod 71, the rod 61 being also connected to a diaphragm 69 under the influence of spring 67 and brake cylinder pressure in chamber 63. A current source 83 is connected to earth line 81 and via main switch 85 and line 87 to terminals 89 of switch 21, the output terminal 91 of which is connected to valve 35 and via switch 77 to the input of switch 79 and to a pressure-controlled switch 103. The other output 105 of switch 21 is connected to a further contact of switch 103. Outputs of switch 79 are connected to holding relay 113 and brake relay 119 respectively. Main air pipe 43 is connected via line 131 to chamber 133 of control valve 135, a diaphragm 137 separating the chamber 133 from a resetting chamber 141 connected to brake air reservoir 139, and controlling release valve 149 and valves 151, 159 and 161, 159, the valve chamber 157 being connected via pipes 165 to a double non-return valve, the piston 169 of which controls the connection of pipe 165 to pressurelimiting valve 171. A chamber 173 of non- return valve is connected to electromagnetic brake valve 175 and holding valve 177 which when energized connects chambers 173 to supply line 1 and shuts-off the venting port 179. The pressure-limiting valve 171 comprises a piston 183 subject to spring 187 on one side and brake cylinder pressure on the other side, a non-return valve 191 held closed by a spring 187 and open by flow from the brake cylinder 65 to non-return valve when sufficient brake cylinder pressure acts on the diaphragm 189. With the brake released valve member 29 engages both seats 27, 31; a control pressure exists in chamber 33 and the open valve 35 in chambers 55, 57 of switch 59, reservoir 37 and chamber 39 of relay valve 7, the valve members 47, 49, 51 being as shown and the control pressure exists in pipe 43, the quick-action valve 17 being closed. Control valve 135 is in the release position with valves 151, 155, open and valves 149, 139, 161 closed when reservoir 139 is charged with the control pressure. Brake cylinder 65 is vented via open valve 185 either via open valve 177 and port 179 or via chamber 155 of valve 135. Chamber 63 of switch 59 is vented, switch 77 is opened and switch 79 engages contact 109, switch 21 connects terminals 105 and 89 and switch 103 is opened and valve 37 not energized. Electric brake control.-For braking, lever 13 reduces compression on spring 23 and switch 21 briefly connects terminals 91, 89, outlet valve 29, 31 is opened to reduce pressure in the control circuit and valve 35 is closed. Diaphragm 53 moves to the left to close switch 77 and change-over switch 79 to engage terminal 115, causing relay 119 to be energized from the source 83 via switch 21 to close switch 127 and energize coils 201, 203 to open valve 175 and close valve 177 and supply compressed air from line 1 to chamber 173 of the non-return valve and to chamber 207 of controller 101 to close switch 103 and maintain switch 77 and valve 35 energized even when switch 21 has been switched back to terminals 105 and 89. The non-return valve closes off valve 135 and open its valve 193 to connect chamber 173 to valve 171 and to brake cylinder 65, valve 185 being held open until a maximum brake cylinder pressure is reached when piston 183 closes valve 185 against the spring action. Pressure in brake cylinder acts in chamber 63 of switch 59 to move rod 61 to the right until switch 79 engages terminal 109 to release relay 119 and energize holding relay 113 to close valve 175 and valve 177 is retained closed by energization of coil 205. Brake release.-Lever 13 compresses spring 23 to open valves 29, 31 to build up pressure in the pre-control circuit which in chamber 55 moves rod 61 to the right to open switch 77, relay 113 being de-energized to open valve 177 to vent brake cylinder 65 via valve 191 or 185 double non-return valve and the outlet 179. When fully released the switch 103 and thus valve 35 are opened. Pneumatic controlled braking.-Should source 83 fail or if switch 85 is opened the valve 35 remains open on braking so that the pressure drop in the pre-control circuit causes a pressure drop in pipe 43 by movement of diaphragm 41 and stem 47 of relay valve 7 to the right. Thus piston 137 of control valve 135 is moved to the right to close valve 151, 159 and open valve 159, 161 to supply air from reservoir 139 to the brake cylinder 69 via valve 159, 161 double non-return valve, valve 171, the flow continues until the drop in pressure in reservoir 139 and in chamber 141 corresponds to the pressure drop in the pipe 43 and chamber 133. Brake release.-Air pressures fed from pipe 1, valve 31, 29 to valve 7 and pipe 43 causing diaphragm 137 to move to the left, closing valve 159, 161 and opening valves 151, 159 and 149, the brake cylinder then being vented and air flows to charge reservoir 139 from pipe 43 via valve 149 until the regulation pressure is reached when diaphragm 137 moves slightly to the right to close valve 149. Rapid braking while electric control system is working.-The electric system supplies air to chamber 173 of the non-return valve via valve 175 as before. Simultaneously by opening valve 17, pipe 43 is vented and valve 135 supplies compressed air to input 167 of the non-return valve and due to piston 181 input 167 is connected to the brake cylinder. Pressure in the chamber 173 opens valve 193 and also feeds air to the brake cylinder 165 for rapid build-up of pressure. A valve not shown may be inserted in the line to chamber 5 to avoid compressed air being continuously released via valve 17. Release after quick-action braking.-Chambers 173 and 207 are vented by opening valve 177; switch 103 is open and valve 35 is de-energized and pressure from the pre-control circuit with valve 17 closed, operates relay 7 to recharge pipe 43. Failure of electric brake control during braking. With air under pressure in cylinder 63 the valve 35 is opened and the pre-controlled pressure lowers pressure in pipe 43 to operate the control valve 135 as before.