Patent GB-753486-A (GB)
Title: Improvements in or relating to apparatus for the preselective control of the delivery of liquid from a liquid metering unit
IPC: B67D7/30
Filed: 1953-06-25
Abstract: 753,486. Petrol pumps. GAUNT, J. G. June 17, 1954 [June 25, 1953], No. 17706/53. Class 116 The desired volume of petrol to be delivered from a petrol pump is preselected by an operator at a remote location controlling push-buttons operating switches in an electric circuit, the arrangement being such that after preselecting a given volume, that volume may be delivered by removing the nozzle of the petrol pump from its holster and opening the manually-operated nozzle valve, the electric circuit thereafter being controlled by switches operated by movement of the pump register to stop delivery after the selected volume has been delivered. Flow-reducing means are arranged to reduce the rate of delivery when the volume delivered reaches a predetermined amount less than the selected volume. In one form, Figs. 3 and 6, a shaft 18 driven by the hands of the pump so as to be rotated one revolution per unit volume (gallon) carries adjustably a cam member 24 having cam faces 33, 35 engaging respectively the cam-operated contacts of switches 36, 37, and a further cam 23 is loosely mounted on the shaft and is coupled by a pin and slot connection to cam member 24 permitting lost motion, cam 23 actuating a switch 38. The cam faces 35, 23 are so arranged that when petrol is being delivered the switches 37, 38, connected in series, Fig. 6, are both closed during the last three twentieths of each gallon delivered, while when the pump hands are zeroized to prepare for a fresh delivery the lost-motion connection prevents switches 37 and 38 from being closed together during the reverse movement. The switch 36 is opened only if the hands are within a twentieth of a gallon each side of zero or any complete gallon and serves to illuminate, through a relay 73, an indicator lamp 85 marked "turn pump hands to zero" whenever the hands are outside the range mentioned, so that if delivery is stopped manually before completion of delivery of a set number of gallons warning is given that the hands must be reset. Resetting of the hands is unnecessary after delivery of any complete number of gallons and may be carried out merely for convenience. The pump is selectively driven by a main motor wired to a plug 48 and a subsidiary motor wired to a plug 41. The main motor drives the pump at normal speed while switching over from main to subsidiary motor reduces the speed of the pump, the subsidiary motor being connected through a freewheel device with the main motor. Power is supplied from a plug 39 through a cut-out 42 and normally closed contacts 44, 49 of relays 45, 47 respectively to the plug 48, the circuit being completed through the usual pump switch which is closed when the nozzle is lifted off its hook. The control circuit is fed from a transformer and rectifier 52 one side of which is earthed, the transformer having also a five volt winding for the various indicating lamps. The circuit comprises a four-bank uniselector prepared by energization of a stepping coil 56 and actuated upon de-energization of coil 56 by spring means to move the arms 59, 61, 63 and 65 simultaneously clockwise, one step. The uniselector is reversible whereby when the circuit to coil 56 is completed through contacts 57, arm 63 of the uniselector, and earthed bank 62 of contacts by depression of a resetting switch 66 closing contacts 71, the uniselector arms motor anticlockwise to their starting positions. At such time the pump motors will normally be cut off by relay 45 being energized and opening contacts 44. Relay 45 is maintained energized during resetting through contacts 70 of the resetting switch. Further contacts 72 are opened by depression of the resetting switch to isolate the coil 56 from switches 37 and 38 during resetting. A relay 81 was energized while arm 63 was on any of the earthed contacts 62, illuminating a lamp 84 marked "reset before next delivery." After resetting relay 81 is deenergized and after the pump hands have been set to zero if necessary (see above) a circuit is completed through a lamp 86 marked "set next delivery" and contacts 75 of relay 73. This circuit is broken by contacts 80 of a relay 76 arranged in parallel with coil 56 if the latter is energized, a circuit being instead completed through lamp 85 through contacts 79. As a further precaution, if current passes through coil 56 for more than a predetermined time the contact breaker 42 is opened by its heating coil being connected through contacts 77 of relay 76 to the five volt supply. The electric preselection of a fresh delivery is carried out by a series of switches 67, 68, 69 &c. to any desired number according to the number of uniselector positions, these switches being mounted in a remote control box together with a series of corresponding indicator lamps 87, 88, 89 &c., the resetting switch 66, the lamps 84, 85 and 86 and the cut-out 42. The first three switches, for selecting one to three gallons. are connected to the second, third and fourth contacts of the bank 58 of uniselector contacts and to the first, second and third contacts of the bank 60, the remaining switches (not shown) being connected similarly. Lamps 87, 88, 89 &c. are correspondingly connected with the second, third, fourth &c. contacts of bank 64. Switches 67, 68, 69 &c. and switch 66 are all mechanically interlocked so that when one switch is depressed a previously depressed switch is released. In operation, e.g. switch 69 is depressed and thereby closed, this releasing the resetting switch 66. This de-energizes relay 45 closing contacts 44 to permit petrol to be dispensed. During delivery of the last three twentieths of each gallon a circuit is completed through coil 56 being broken as each exact gallon is delivered. This steps the uniselector clockwise, as explained above, arm 65 moving on to the appropriate contact 64 to indicate, through one of the lamps 87, 88, 89 &c., the number of gallons delivered. When the last three twentieths of the last gallon, i.e. the third gallon, is reached a further circuit is completed by the switches 37, 38 through relay 47, uniselector arm 61, contact 60a of bank 60, line 117 and contact 69 energizing relay 47 breaking the circuit through contacts 49 to the plug 48 of the main motor and establishing a circuit through contacts 46 to the plug 41 of the subsidiary motor, thus reducing the rate of flow. When contacts 38 now open the uniselector arms are stepped on to the final position to indicate three gallons being delivered, this completing a circuit through relay 45, arm 59, contact 58a of bank 58 and switch 69 to open contacts 44 so that delivery stop's at the three gallon mark, relay 47 at the same time being re-opened. Instead of having two motors, the flow may be reduced by one or more suitable valves between the pump and the nozzle, the valve being operated by relay 47 either to partially close, or to close fully but being provided with a by-pass allowing the reduced flow. In a modification, Figs. 8 and 10, a cam 140 is rotated by the pump hands once for every gallon and is provided with a recess 162 into which a follower roller 139 connected with a valve 128 can ride to cut off the flow gradually, the roller being prevented from entering the recess until just before delivery of the last gallon to be delivered by a latch 141 arranged to be withdrawn by a solenoid 142 at this moment. The solenoid 142 is adapted be de-energized by energization of a relay 147 consequent upon arm 156 of one uniselector bank reaching the contact 157 connected to the selected switch, i.e. switch 69. Stepping of the uniselector is affected by the camoperated contacts 38 only, contacts 37 being omitted, and the contacts 36 indicate the necessity for resetting as in the previous form. The resetting switch 149 is simplified since it is not necessary to maintain relay 147 energized once latch 141 has been released. The latch is automatically reset when the pump hands are zeroized, which is necessary after every delivery. A thermal cut-out 154 is arranged in series with the uniselector coil 56. The pump motor 166 is controlled solely by contacts 167, 168 closed when the nozzle is lifted off its hook. In a further modification, Fig. 11, the uniselector is omitted and a switch arm 170 is moved directly by suitable gearing from the pump hands over the contacts 171, 172 &c., the movement between adjacent contacts representing one gallon. Lamps 180, 181 &c. indicate the number of gallons delivered while upon reaching the contact 184 coupled to the depressed switch 69 relay 176, corresponding to relay 147 is energized. The pump motor 2 is controlled solely by contacts 183 controlled by relay 179 energized by closure of contacts 178 when the nozzle is lifted off its hook. In a still further form, Fig. 12, depression of switches 67, 68, 69 &c. is arranged to open instead of close the switches, and the cam 140 is replaced by a larger diameter cam adapted to make a complete revolution for the maximum number of gallons which can be delivered. In this case there is no latch 141 and the cam is merely set back an amount according to the number of gallons to be delivered by a stepping mechanism including a stepping coil 190, motoring contacts 218, pawl and ratchet gear 195, 194 driving shaft 196 on which the cam and a selector switch arm 197 are mounted, and relay contacts 208, the switch arm 197 coming to rest on the contact 223 corresponding to the switch 69 depressed, after which petrol can be delivered which returns the cam until follower 139 rides into the recess in the cam and closes the valve 128. The contacts 208 are not closed and thus do not permit the stepping mechanism to motor to a selected position if the hands were not zeroized since in that case contacts 206 are arranged to be open de-energizing a relay 207 to open contacts 208 and close contacts 210 in the circuit of lamp 211 marked "turn pump hands to zer