Patent GB-901131-A (GB)
Title: Improvements relating to electrically operated shift device for change-speed gears
Filed: 1960-06-02
Abstract: 901,131. Change-speed control. DAIMLERBENZ A.G. June 2, 1960 [June 18, 1959], No. 19556/60. Class 80 (2). A vehicle transmissionprovidesual for purely manual upshift and for manual downshift and automatic downshift to second gear in accordance with the input speed of the gear and accelerator position and also in accordance with input speed and braking. General.-The gearing is controlled by shift forks controlled by cam slots in a disc 46 driven through reduction gearing by a shaft 17 which is driven by a reversible electric motor 15. The main vehicle clutch assembly comprises an hydrodynamic clutch and a mechanical separating clutch which is disengaged by a lever 18 turned anticlockwise by a crank arm 16<SP>1</SP> on the shaft 17 abutting the end of the sleeve 16<SP>11</SP> pivoted to the lever 18 which is fast with a shaft 19. A vacuum motor 32 retains the clutch lever 18 in the disengaged position, vacuum being provided by the engine induction, and motor 32 being vented by an electromagnetic valve 33 which is released after one revolution of the shaft 17 by a cam thereon opening a switch 61 in its control circuit. A crank on the shaft 19 has a lost-motion connection with a lever 26 controlling the engine throttle and ensures the engines idle when the clutch is disengaged. An arm 35 mounted on the steering column 34 carries manual switches 36, 37 and 38 for upshift, downshift and reverse and carries a gear indicator 40. Upshift.-The switch 36 is momentarily closed, thus energizing relays 50, 65. Relay 65 closes a switch 63 which bridges the switch 36 and which also energizes a self-holding relay 54<SP>1</SP> which closes a switch 56<SP>1</SP>. Relay 50 releases a retaining pawl 51 from the cam-slotted disc 46 and closes switch 49 which completes a circuit, through the switch 56<SP>1</SP>, to a relay 59. Relay 59 actuates a switch 58 which moves to its dash line position and completes a circuit 47<SP>1</SP> so that the motor 15 is driven in its upshift direction. When the disc 46 leaves the previously engaged gear or neutral position, a switch 66 controlled by lobes on the disc opens, breaking the circuit to relays 50, 65 so that switches 49, 63 open and pawl 51 is biased to its disc engaging position. The motor 15 continues to be driven as switch 56<SP>1</SP> remains closed and switch 49 is bridged by a line 60. At the end of one revolution of shaft 17 line 60 is broken by the cam-operated switch 61, the motor stops and pawl 51 engages detents to retain the disc 46 in position. All the time that switch 36 is held closed upshift occurs through the gears. A relay 85 in the upshift control circuit opens a switch 84 in the downshift control circuit to ensure that upshift over-rides downshift. Downshift.-A governor control switch 74 in the downshift control circuit prevents downshift above a predetermined speed of the input shaft of the gear. (a) Manual.-Switch 37 is momentarily closed, thus energizing relays 71, 97. Relay 71 closes a switch 70 which bridges switch 37 and energizes a self-holding relay 54<SP>11</SP> which closes a switch 56<SP>11</SP>. Relay 97 moves a switch 69 to its dashed position, thus energizing the relay 50 to release the pawl from the disc 46 and close switch 49. Switch 58 is biased to its full-line position and a downshift motor circuit 47<SP>11</SP> is completed through switches 58, 56<SP>11</SP>, 49. When disc 46 leaves the previously-established gear position a switch 73 actuated by lobes on the disc is opened and breaks the circuit to relays 71, 97, so opening switch 70, and returning switch 69 to its original position. Motor circuit 47<SP>11</SP> is completed through bridging line 60 until the switch 61 opens. When in neutral the switch 73 is open to prevent further shift. (b) Automatic with speed.-A switch 77 is closed by the accelerator above its half-throttle position, and a governor switch 79 closes at input shafts speeds below 2000 r.p.m., thus energizing the relay 71 to complete the downshift circuit. A switch 78 operated by the disc 46 opens to prevent automatic downshift below second gear. (c) Automatic on braking.-The accelerator switch 77 is bridged by a switch 81 controlled by relay under the control of a brake-actuated switch 82 so that on braking when the speed falls below 2000 r.p.m. downshift to second gear occurs. (d) On starting the engine.-Operation of the starter closes a switch 95 which bridges the switch 37, thus downshifting until neutral is reached, whereupon a lobe 90 of the disc 46 actuates switch 86 to its alternative position in which the starter motor can be energized. Reverse.-Manual switch 38 bridging switches 37, 73 completes the downshift circuit and shift continues beyond neutral to a reverse position. In a modification, Fig. 3, the vehicle clutch is disengaged by a separate electric motor. In this case bridging line 60 with switch 61 is dispensed with and the clutch motor is controlled by a relay 91 branched off from the line to switch 49. Relay 91 also controls the valve 33 controlling engagement of the clutch. The windings 54<SP>1</SP>, 54<SP>11</SP> are connected to earth through a lead 92 by way of a switch 93 which is closed only when the clutch is open. The starter circuit is also modified, a relay 94 for downshift being connected in parallel with a circuit 87 which is completed by a switch 86 when the disc 46 is in its neutral position.