Patent GB-1111246-A (GB)
Title: Electric control means for synchronised gear shifting in variable speed gear boxes
IPC: B60W30/18
Filed: 1965-11-04
Abstract: 1,111,246. Controlling vehicles. K. H. SCHMIDT. 4 Nov., 1965 [4 Nov., 1964; 6 July, 1965; 14 Oct., 1965], No. 46798/65. Heading B7H. [Also in Division F2] In a synchronized-shift motor vehicle changespeed control, a gear establishing signal is supplied to hydraulic or pneumatic gear-shift servomotor means 29 on balanced energization of a polarized differential relay 17 having two windings 20, 19 respectively energized from an output shaft driven electrical generator 6 and, through one of resistors 14, 14a, 14b corresponding respectively to the change-speed gear ratios, an input shaft driven electrical generator, and means are provided to lengthen the duration of the gear establishing signal to provide sufficient shifting time for the gear-shift servomotors. As shown, the gear-establishing signal is provided at the differential relay output 18 which on synchronism, is connected to a current source 25 through the closed switch 23 of the differential relay and a delayed release relay 36, the signal at 18 energizing a holding relay 37 having contacts 39 in parallel with the switch 23 so that the duration of the gear establishing signal is determined by the delayed release relay. Alternatively, the differential relay 17 may be connected to a monostable sweep circuit. The generators 4, 6 may be D.C., two-phase A.C., the resistors 14, 14a, 14b then being A.C., or, as shown, three-phase A.C. provided with rectifiers 7, 10. The differential relay may be A.C. The servomotor means 29 comprise cylinders the pistons of which are centralized into neutral positions when fluid is fed to both sides thereof through a line 50 controlled by an electromagnetic valve 52, and are moved for gear establishment when a selected cylinder side is vented through one of lines 53-55 controlled by electromagnetic valves 56-58. A switch means 5, shown schematically, is so moved by a gear shift means 42 that in the neutral position the delayed release relay 36 is actuated and in gear established positions, such as 43, 44, indicating means are energized. The control may be provided for more than the three ratios shown. In operation, first, the driver actuates a gear ratio selector switch 33 to close selected corresponding contacts in switches 13, 28 respectively to connect one of the resistors 14, 14a, 14b between the generator 4 and the winding 19 and to connect the output 18 to one of the electromagnet valves 56-58. Since a gear ratio is already established, the energization of the differential relay is not balanced and the switch 23 is open. The driver then momentarily actuates the main clutch pedal K to actuate a delayed release relay 47 to energize and open the electromagnetic valve to bring the changespeed gear to neutral in which the switch means S actuates the delayed release relay 36. The clutch is then re-engaged, it being noted that the further shift operation takes place with the clutch engaged. The input shaft speed is then adjusted automatically by a means 64 hereinafter described until synchronism is achieved whereupon the switch 23 closes and the selected one of the valves 56-58 is opened to establish a gear. The relay 36 has a longer releasing time than that of the relay 47. In the automatic input shaft speed adjusting means 64 of Fig. 2 (not shown), a bi-directional rotary servomotor acts, through toothed gearing and a spring-centred eccentric, on a lever interposed between the accelerator pedal and the engine fuel regulator, so as to actuate the latter independently of the driver. The direction of servomotor rotation is determined by two relays controlled by a changeover switch. In operation, a signal is fed to the means 64 at E 1  when the relay 36 is actuated in neutral, and a signal is fed to E 2  in dependence on the position of the differential relay armature 22 to actuate one or other of the servomotor relays in the means 64 to accelerate or decelerate the engine until the differential relay is balanced on synchronism, whereupon actuation of the holding relay 37 supplies a signal to E 3  to de-energize the means 64. The signals to E 1 , E 2 , E 3  may be mechanical, electrical or pneumatic-hydraulic. In Fig. 3 (not shown) the two servomotor relays of the means 64 respectively control a fluid pressure servomotor acting, through a lost motion connection, on the accelerator pedal, for input shaft acceleration, and a fluid-pressure servomotor acting on an input shaft brake. In the event that the means 64 is unable to accelerate the input shaft sufficiently for synchronism, the switch 33 is re-set to the next higher gear ratio position by a means R which is actuated to re-set by a means 94 acting through a line 93 and is rendered inoperative by the output signal at 18 acting through a line 95. In Fig. 5 (not shown), the re-setting means R comprises a main lever connected to the contact arm of the selector switch 33 and carrying a pivoted pawl spring loaded to engage fixed notches corresponding to gear ratio positions and released by a solenoid energized through the line 93. A follower lever also carries a pivoted, spring-loaded, notchengaging pawl which is released by a solenoid energized through the line 95. The main and follower levers are connected by a link including a lost-motion connection overcome by a spring so that upon downshift only of the selector switch, the follower lever remains one notch behind the corresponding position of the main lever. If synchronism is not achieved by input shaft acceleration, the main lever pawl is solenoid-released so that the selector switch contact arm is moved to the next higher gear position. On synchronism, solenoid-release of the pawl of the follower lever enables the latter to take up the main lever position. The means 94 comprises a delayed-action relay actuated in a predetermined limit position of the eccentric (Fig. 2, not shown) or accelerator pedal (Fig. 3, not shown) or by a voltage-sensitive relay connected to the output of the input shaft generator rectifier circuit (Fig. 4, not shown). To speed upshifting, the delay in releasing time of the relays 36, 47 is terminated by a switch 62 acting on said relays and actuated by driver-actuation of the selector switch 33. A delayed action relay 63 is provided to ensure successive respective release of the relays 47, 36. In an arrangement wherein two or more engines have respective individual changespeed gear-boxes, each driving one or more vehicle wheels or wheel axles, and the fuel supply is controlled from a single accelerator pedal G, means may be provided to prevent the accelerator pedal from being depressed before shift is complete in all the gear-boxes. In Fig. 6 changeover switches 117, 118 in series between a current source 126 and a relay 125 are connected to the switch means S of two of the above shifting circuits. In neutral the accelerator pedal, if released by the driver, is locked by a latch 129 acted on by a solenoid 132. When both gear-boxes are in the engaged condition the relay is energized to de-energize the solenoid and to permit a spring 131 to withdraw the latch and release the pedal.