Patent GB-1212742-A (GB)
Title: Equipment for effecting synchronous gear changing in variable speed gear boxes for motor vehicles
Inventor: BILDAT BENNO
IPC: F16H61/04
Filed: 1968-04-26
Abstract: 1,212,742. Change-speed control. K. H. SCHMIDT. 26 April, 1968 [27 April, 1967], No. 20010/68. Heading F2D. In an electric synchronizing control for a motor vehicle change-speed gear wherein a gear establishing signal is produced on balanced energization of a polarized differential relay 16 having windings 10, 11, respectively energized from an input driven generator 1 through resistors 12 ... 14 corresponding to the gear ratios and an output driven generator 2, the differential relay 16 additionally operates a change-over switch 25 which selectively energizes engine accelerating and decelerating means V +, V - to facilitate synchronism and a blocking circuit 28 blocks or prevents production of the gear establishing signal for a predetermined time when synchronism is attained during engine acceleration. As shown, on synchronism the differential relay 16 closes a switch 17 to complete a circuit 20 from a source 18 through a delayed release relay 24, a blocking switch 30 and selector switch 19 to the selected gear establishing line 21 ... 23. The devices V +, V - may automatically accelerate and decelerate the engine or may indicate to the driver that acceleration or braking of the engine is necessary. If the engine speed is too low the differential relay 16 moves the switch 25 to the position shown in which the device V + is energized for engine acceleration and a relay 29 is energized to open the blocking switch 30. When the engine speed has risen sufficiently to produce synchronism the differential relay closes the switch 17 and begins changing-over the switch 25, whereupon a time delay capacitor 33 maintains the relay 29 energized and the switch 30 open to block the gear establishing signal. If synchronism still exists after a predetermined time the switch 30 closes and the gear establishing signal is transmitted to the selected line 21 ... 23 to establish the gear ratio. If due to inertia the engine speed continues increasing after synchronism the changeover switch 25 engages contact 27 to energize the device V - for engine deceleration and a relay 34 which short-circuits the capacitor 33 and closes the switch 30 so that when synchronism is again established the gear establishing signal is transmitted to the selected line 21 . . . 23. The generators 1, 2 may be three-phase A.C. provided with rectifiers 3, 4. In Fig. 2 (not shown) a three position change-over switch (25) has a centre contact which is closed at synchronism to energize a relay (36) and close a switch in the gear establishing circuit. The outer contacts (26, 27) of the change-over switch (25) energize relays (35, 37) to complete the circuits to the devices (V+, V -) and blocking circuit (28). In Fig. 3 (not shown), a gear establishing circuit includes a switch (39) opened by a relay (40) when the change-over switch (41) engages contacts (26a, 27a) to complete circuits to the engine accelerating and decelerating devices V +, V - . When, at synchronism, the switch (41) is intermediate contacts (26a, 27a) the switch (39) is closed for gear establishment. The relay (40) is maintained energized through an auxiliary circuit (46) for a predetermined time after synchronism when the latter is attained during engine acceleration. In Fig. 4 (not shown), the circuits to the devices (V+, V - ) are completed through relays (48, 49) otherwise the circuit is similar to Fig. 3. The electromechanical relays may be replaced by electronic switching circuits (e.g. transistor circuits).