Patent GB-802272-A (GB)
Title: Improvements in or relating to electrical means for automatically controlling changespeed gearing
Inventor: MILLER ALBERT ARTHUR
IPC: F16H61/00
Filed: 1955-10-05
Abstract: 802,272. Change-speed control. SELF-CHANGING GEARS, Ltd. Jan. 4, 1957 [Oct. 5, 1956], No. 28392/55. Class 80 (2). A change-speed gear for a road or rail vehicle is operated automatically in response to output speed by electric relays 1P ... 4P, one for each ratio, which are energized in one direction only by an output-driven generator G1 or G2, in opposition to differing fixed voltages. Relay operation is thereby rendered more precise and operating differential reduced. Function summary.-Automatic shift speeds are raised with engine throttle opening. The throttle is temporarily closed during upshift only. Energizing of the first speed relay is in response to opening the engine throttle, and prior to engagement of first speed, the highest speed is temporarily engaged to take up play in the transmission. A manual drive-neutralhold master control-switch 25, provided with a key handle, prevents any upshift when in hold setting. Closed throttle stopping causes direct return to neutral from any gear ratio. In a continuous rail-car train control failure of any one of the speed responsive generators is indicated by warning lights, and a lock is provided for preventing movement of a forwardreverse control 14 during movement of the train. Where a manual override selector switch is provided (Fig. 3, not shown), the gear can only make one downshift step irrespective of the number of steps manually selected, such additional steps following under automatic control. Train control.-The control shown is for a rail-car having two engine-transmission units controllable from either end of the car and electrically coupled to other cars in a train. Each planetary gear (not shown) provides four speeds both forward and reverse, by reaction brakes operated pneumatically by solenoid valves (not shown) controlled by secondary relays 1S ... 4S, energized by primary relays 1P ... 4P, subject to speed-responsive energization by commutator-type D.C. generators G1, G2, driven by the output shafts of the respective transmissions. The negative poles of the generators G1, G2 are connected to the battery negative line 1 of the train, whilst their positive poles are connected through one-way rectifiers 36 to a line 35 feeding the primary relays 1P ... 4P in opposition to positive voltages tapped in adjustable ascending order from a potentiometer 3, connected respectively directly and indirectly to battery negative line 1 and positive line 12. The primary relays 1P &c. may be polarized, or, as shown, have one-way rectifiers 34, 36 in their generator-fed line. Of the secondary relays, only the first 1S is a single coil, the remainder 2SA, 2SB; 3SA, 3SB and 4SA, 4SB being of the two-coil type. All are battery-fed under control of the primary relays 1P &c., and each serves to close respective contacts 1S2, 2S2, 3S2, 482 energizing solenoid valves of the ratio-establishing brakes. The engine throttle is operated by motors TM, not described, energized through lines T1 ... T4 through a manual switch 24 having five positions T1<SP>1</SP> ... T4<SP>1</SP> and T5<SP>1</SP>, the last-named corresponding to idle, the other four to quarter, half, three-quarter and full throttle by energizing respectively the lines T1; T1 and T2; T2 and T3; T3 and T4. In the drawing all contacts operated by the respective relays are prefixed with the designation of the relay, contacts shown in the open position being closed and those shown closed being opened by energization of the respective relay. Operation: Start.-Movement of the manual switch 14 to forward or reverse, and the master control switch 25 to drive or hold, connects battery positive 12 to a line 38 energizing the secondary relay group. The first speed primary relay 1P becomes energized directly from battery positive 12 when the engine-throttle control 24 is moved from idle to any open setting, which energizes a relay F at all throttleopenings over quarter, or E at three-quarter or full throttle, which closes contacts E1 or F1 connecting battery positive 12 direct to the first, speed relay IP. The relay 1P then closes contacts 1P1 connecting battery positive 12 to the relay opposing-voltage potentiometer 3, and to the generator fields f1, f2. The primary relay 1P also closes contacts 1P4 for energizing the first speed secondary relay 1S through contacts 4S3, 3S3, 2S3, but before this can occur, the opening of charging contacts 1P3 and closing of discharge contacts 1P2 by the primary relay 1P causes a charged capacitor C5 to discharge through the relay coil 4SA momentarily introducing fourth speed at contacts 4S2 to take up transmission play, and also opening contacts 4S3 to prevent energizing of the first speed secondary relay 1S until the relay 4SA is deenergized, whereupon the closing contacts 4S3 energize the relay 1S which energizes the first speed. solenoid valve at contacts 152. During these actions the engine throttle is temporarily idled by the secondary relay 1S and primary relay 1P opening charging contacts 1S5 and 1P5, and closing discharge contacts 1S4 to discharge a capacitor C1 through a relay G, contacts G1 of which energize a relay D, which, with G, opens contacts D2, D4, G2, G4, breaking all throttle-opening lines T1 ... T4 until discharge of the capacitor is completed. Subsequent vehicle movement causes the outputdriven generators G1, G2 to maintain energization of the primary relay 1P even if the throttle is returned to idle. Upshift. At a predetermined vehicle speed in first gear, voltage of the generators G1, G2, acting through a contact HI, previously closed by a relay H, energized (or alternatively deenergized) when the master control switch 25 is set in drive, energizes the second speed primary relay 2P. This opens contacts 2P3 to maintain reduced energization of the first speed primary relay 1P through a resistor R6, and closes contacts 2P4 energizing the second speed secondary relay coil 2SA, which closes the second speed contacts 2S2 and opens 2S3 to de-energize the first speed secondary relay 1S for opening the first speed contacts 1S2. During shift the engine throttle is temporarily idled by the opening of charging contacts 2S5, 2P5 and closure of discharge contacts 2S4 of a capacitor C2 which energizes the relays G, D for momentary closure of the engine throttle as above described. The remaining upshifts 2-3 and 3-4 are similar. Shift speeds are raised with increased throttle opening by increasing the potentiometer relay-opposing voltage by shorting first a resistor R3 by contacts F5, closed by the relay F which is energized at all throttle openings above quarter and secondly by shorting also a resistor R2 by contacts E5 closed by the relay E energized only at threequarter and full throttle. Upshift inhibitor.-In hold setting of the master manual control, the hold relay H is deenergized to open contacts HI, H2, H3, inserting resistors R9 &c. in the generator circuits of those primary relays above those for the speed actually in engagement, and to close contacts H4, shorting the resistors R2, R3 to increase the potentiometer relay-opposing voltage. Upshift cannot then occur. Downshift.-Differs from upshift in that there is no accompanying throttle closure since the capacitor charge circuit of the succeeding lower speeds is broken at the contacts. 1P5 &c. by the maintained energization of the corresponding primary relays. Direct return to neutral on throttle closure is provided by contacts F2 which close when the relay F is de-energized by throttle closure, to maintain supply to whichever secondary relay is energized until the vehicle comes to rest and the primary relay contacts 1P1 open, de-energizing the secondary relay group for direct return to neutral. Failure warning.-If the voltage of either generator G1 or G2 falls below normal during running in third or fourth speed at at least quarter throttle, double coil relays JA, JB; KA, KB, across the rectifiers 36 of the respective generators, are energized through contacts F4, 4P1 ; F3, 3P1 (closed by throttle and primary relays F, 4P, 3P), to close contacts J1, permanently lighting lamps LB in the control cabin, and contacts J2, K2 lighting train lamps TL. Contacts J3 disconnect the faulty generator. Modifications.-Fig. 2 (not shown) is a simplified form for a road vehicle having four speeds and one reverse. One generator only is used, and the throttle-controlled resistor in the relay opposing voltage line is steplessly variable. A manual forward, neutral, reverse switch is used, and the arrangement is such that if during running, this switch is moved from F to N or R, the shift relays will continue to be energized after neutralizing and the appropriate ratio will be re-engaged when the lever is returned to F. Reverse itself cannot be engaged until the vehicle stops. Fig. 3 (not shown) has a manual override selector switch with contact studs for automatic, five forward speeds and reverse. The secondary relays control making-contacts between the switch studs of the manual speeds and breaking-contacts between the studs and the secondary relays, to ensure that on a manual downshift the gear can only shift down one ratio irrespective of the number of steps down selected by the switch, further downshifts to the step manually selected being in accordance with the automatic control.