Patent GB-419906-A (GB)
Title: Improvements in and relating to the control of variable speed transmission mechanismin power systems
Filed: 1934-01-16
Abstract: 419,906. Variable-speed gearing. BRITISH THOMSON-HOUSTON CO., Ltd., Crown House, Aldwych, London.-(Assignees of Prince, D. C.; 150, Guernsey Road, Swarthmore, Pennsylvania, U.S.A.) Jan. 16, 1934, No. 1606. Convention date, Jan. 18, 1933. [Class 80 (ii).] Step-by-step variable-speed gearing for a vehicle is automatically controlled by a centrifugal governor driven by the driven shaft and subject to a bias dependent on the setting of the accelerator pedal, the governor serving to impart axial movement to power-driven cams, which control the speed-changing mechanism. During a speed-change, the main-clutch is disengaged through an engine-suction servodevice operated by an electrical relay, and the throttle is set to the idling position. Means are provided for overriding the automatic action to provide for manual operation of the speedgear and the main-clutch, and such means, in one form, also locks a free-wheel tail-clutch. In the form shown in Fig. 1, the controlling- means, through electric switches, operated by the power-driven cams, energize solenoids which directly move the gear-strikers, but in that of Fig. 2 the solenoids act only as relays which remove stops from the path of the strikers to allow them to be operated by the engaging- movement of the main-clutch control. In the form shown in Fig. 1, gear-strikers 12, 13 are resiliently connected through springs 41, 42 and 29 with solenoid plunger-slides 39, 26. Three operative solenoid-coils 45, 46 and 31 are provided, the slide 13 being manually operated for reverse by a hand-lever 86 which, when operative, opens the entire electrical circuit through contacts 94. There is also a separate solenoid 85, in series with each striker solenoid, which neutralizes the strikers prior to a change by lifting up a transverse bar 77 which turns horseshoe-arms 74, 75 and 64 about fixed pivots 72, 73 and 65, to move and hold the strikers in the neutral position. The horseshoe-arms also yieldably carry latches 61, 38, which, when the neutralizing solenoid is released, engage shoulders or notches such as 62 on the solenoid-slides 39, 26 and retain the slides in the selected positions. The arrangement is such that when the neutralizing and a selected striking solenoid have been energized the former directly neutralizes and holds the strikers 12, 13 and unlatches the slides 39, 26 to allow one of them to be operated by the selected solenoid. At the end of its travel, the slide 39 or 26 opens a switch such as 50 to cut off the current and de-energize the solenoids. The horseshoe-arms then release the strikers 12, 13 to allow one of them to be operated by the spring 41, 42 or 29, which has been compressed by movement of the slide 39 or 26, both of which are simultaneously latched in position by return of the latches 61, 38. In order to prevent undesired movement of the slides 39, 26 before latching, their solenoidplungers are surrounded by short-circuited damping-coils 47 or copper sleeves. In order to provide for manually neutralizing the gear prior to starting the vehicle, the reversing-lever 86 is connected through a link 90 with the horseshoe-arm 64, the lever 86 being also connected with the striker 13 through a pin-and slot connection, a link 91 and a floating connecting-link 88. The striker-solenoids 45, 46 and 31 are energized from a battery 157 through spring-loaded toggle-switches 123, 141 actuated selectively by a cam sleeve 115 rotating with the driven-shaft 109 and slidable axially thereon under the control of a centrifugal governor 110 and a forked ]ever 147, connected through a tension - spring 148 with the accelerator-pedal 96, depression of which opposes the outward movement of the governor. Each switch 123, 141 is operated by a pair of connected axially-spaced freely-pivoted arms 119, 120 and 133, 134 adapted to be engaged one at a time by cams 113, 114 on the sleeve 115. In the first-speed position shown, the cam 113 engages the arm 119 and the live switcharm 123 engages a contact 124 leading to the solenoid 31. Increase of speed causes the cam 113 to move into engagement with and tilt the arm 120 to move the switch-arm onto the contact 132 leading, through the second switcharm 141 and a contact 142 to the second-gear solenoid 45. Further movement of the camsleeve 115 causes the second cam 115 to pass, without effect, the arm 133 to engage and tilt the arm 134, the cam 113 having no further effect. The contact 145, leading to the thirdspeed solenoid 46, is then brought in. The solenoid leads pass through a throw-over switch 176 for permitting manual operation by means of a switch 183. The main-clutch operating-shaft 22, which can be operated by a pedal 23, is connected, through pin-and-slot 21<a> with the piston or diaphragm of a cylinder 14 connected, through a valve 17, with the induction-pipe 10 of the engine. The clutch control-valve 17 comprises registering bars 18, 19, the lower 19 of which has a bleed-slot 19<a> and is connected directly with the enginethrottle 11. The latter also has a pin-and-slot connection 101 with the accelerator-pedal 96, through a link 102 adapted to be operated by a solenoid 152 in series with the gear-neutralizing solenoid 85. When any striker-solenoid is energized to make a gear-change, current passes also through this clutch-throttle solenoid 152, which opens the valve 17 to declutch and simultaneously closes the engine-throttle 11 to an idling position. The solenoids are so proportioned that the clutch-throttle solenoid 152 takes the major voltage-drop so that while the clutch is being disengaged the gear-solenoids are inoperative. Complete disengagement of the clutch short-circuits the clutch-throttle solenoid 152 through contacts 162, and the consequent voltage-rise in the gear-solenoids effects the change. The valve 17 is then closed to re-engage the clutch, and the throttle reopened by a spring 108 weaker than the return-spring of the accelerator-pedal. The relay-operated form shown in Fig. 2 comprises strikers 187, 188 pivotally engaged by levers 206, 207 pivoted at 210, 211 on radius arms 212, 218 which turn with concentric shafts 213, 214 carrying arms 216, 219 having a pin-andslot engagement with a forked link 225 moved by the clutch-operating shaft 200. The levers 206, 207 are moved bodily outwards by disengagement of the clutch by engine-suction power 189 or by pedal 201 and when the clutch engages are moved inwardly by springs 217, 220 to an extent determined by four selectivelyoperable interlocked stops 227, 228, 249 and 250 which can engage the levers on either side of their pivots 210, 211 and so cause forward or rearward movement of the strikers 187, 188. The stops 227 &c. slide in C-brackets 231, 253 under the influence of electromagnets 239, 248, 261 and 270, the stops of each pair being interconnected by pivoted bridges 256 which, for interlocking the pairs, operate on the inturned ends 273 of a sliding bar 271. The upper ends of the bridges 256 operate pairs of spring-loaded pivoted switch-arms 267, 268 to cut off the current when the stop has been moved to an operative position. With both stops of one pair projecting an equal distance, the lever 206 or 207 assumes a vertical position and moves the striker to neutral. This movement can be effected by a hand-lever 375 as well as by the springs 217, 220. Energizing a striker-magnet, such as 239, projects the stop 227, withdraws the stop 228 and moves the stops 249, 250 through the interlocking bar 271 to a position corresponding to neutral, so that the striker 187 engages first-speed. The following parts are the same as in Fig. 1, viz. the governor 278, its connection 344 with the accelerator-pedal 347, the cam-operated toggleswitches 294, 315, the suction control-valve 192, and the throw-over switch 373 for manual control 366. The electromagnet 248 for reverse is energized directly through a manual switch 302 which breaks the connection 303 between the toggle-switches and the battery 299. By pulling out a button 363, a switch 301, making connection with the toggle-switches, is opened ; a free-wheel tail-clutch is blocked by a controlwire 362 and the suction valve 192 is closed by operating its upper slide 193, thereby overriding the automatic clutch and engine-idling action. The clutch-throttle electromagnet 300, in series with each striker-magnet, now acts on the suction-valve 192 and engine-throttle 186 in a different manner by means comprising a pivoted armature 357, integral with a hook 355, which latches an arm 353, mounted on a stationary pivot 340 and urged outwardly by a tension spring 331, connecting an arm 339, secured to it, with a further arm on a fixed pivot 333 and serving to support the end of a link 335, connected with the engine-throttle 186. In the retracted position shown, the arm 353 bridges contacts 309, to complete the circuit of the magnet 300. When the magnet 300 is energized to release the arm 353, the spring 331 throws it outwardly, thereby immediately breaking the magnet-circuit. In so doing, the spring 331 moves beyond the pivotal centre 333 and thereby pulls the link 335 outwardly, to close the engine-throttle 186 to an idling position and simultaneously open the suctionvalve 192 to disengage the main-clutch. In the meantine, the striker-magnets have had no effect, since, with the main-clutch engaged, the stops 227 &c. were held by the levers 206, 207, acted on by the springs 217, 220. The main clutch now disengages and causes an arm 358, on its operating-shaft 200, to push the arm 353 under the armature-latch and again complete the circuit to the striker magnets, through the contacts 309. Since the stops 227 &c. have been freed by disengagement of the main-clutch, the striker-magnets can now move them to the selected position, under control of the toggle switches 294, 315. In the meantime, return movement of the arm 353 causes the spring 331 to open the engine-throttle to its origina