Patent GB-727757-A (GB)
Title: Improvements in or relating to electric motor control apparatus for multi-speed transmission gears
IPC: H02P7/03
Filed: 1952-12-19
Abstract: 727,757. Controlling change-speed gearing. BOSCH GES., R. Dec. 19, 1952 [Dec. 21, 1951], No. 32203/52. Class 80 (2) [Also in Group XXXVII]. A reversible electric motor 10 having oppositely wound field windings 11, 12 drives a control shaft for actuating the gear changing mechanism of a vehicle, the control gear for the motor comprising an electromagnetic switch 14, a manual switch 15, and a switching device 16. Two interrupter switches 27, 28, are included in the device 16 and are actuated in sequence by a cam wheel 35 which is coupled to the electric motor and has separate cam surfaces for each interrupter. Projections on the cam surfaces are offset in relation to one another and correspond to the several gear positions of the vehicle (six forward, one reverse, and a neutral position). Sliding contacts 39, 41 carried on a common arm, co-operate with arcuate contacts 42, 43, whilst another sliding contact 40 on the arm co-operates with contact segments 44, 44a. In the position shown, the gear IV. is in engagement, the switches 27, 28 being actuated by the projections X, A. At the same time the indicating lamp IV is energized due to the engagement of the contact 40 with one of the segments 44. In order to change to gear-position V for example, the lever 49 is moved manually to close contacts 52, 53, a circuit then being completed from battery 18 to the hold-on coil 58 and coil 22 of switch 14. The actuating lever may therefore be released and the motor 10 is started in the direction corresponding to the excitation of the field winding 12. The cam wheel 35 rotates clockwise together with the motor to close firstly the switch 27, energization of the coil 21 of the switch 14 being prevented by relay 25. The switch 28 is then closed to short circuit the hold-on coil 58 and to complete a circuit to the coil 22 independently of the switch 15. When cam B afterwards opens the switch 28, the motor is disconnected. Should the cam-wheel over-run the desired stopping-point, the switch 27 moves past cam C and is closed so that the motor is started in the reverse direction to return the cam-wheel towards the desired position. Further over-run will again cause the motor to reverse until the proper position for the intended gear change has been reached. The contact 40 is now in contact with the segment 44 which is connected to the indicating lamp V. The segment 42 disengages the contact 39 to prevent further energization of the motor for the purpose of effecting an upward gear change when the gear-position VI has been reached. The segment 43 acts similarly during a downward gear-changing operation when the neutral or reverse position has been attained. A change through several gear positions may be effected by retaining the manual switch 15 closed until the desired position is indicated by a signal lamp. In order to engage the reverse gear from the neutral position in which contacts 40, 44a, are in engagement, it is necessary to close hand switch 61. Closure of contacts 50, 51, will then cause the motor to engage the reverse gear. The switch 15 may have operating coils for moving the arm 47 in addition to the hold-on coils 57, 58, Fig. 2 (not shown). The speed of the motor may be reduced as it approaches a stopping position of the cam wheel 35 by the parallel connection of a resistor across the armature of the motor in dependence upon the position of the cam wheel, Fig. 3 (not shown). The switching device 16 has a motordriven shaft 73 integral with a cup shaped plate member 74 upon which are arranged the cams 36, 37, the switches 27, 28, being mounted on pins 88, 89. A switch disc 75 is supported on a stud 76 with which it is moved and is urged against a contact plate 79 mounted on casing 70. A pin 80 projects from the centre of the plate 79 and is received in a hole 81 in the switch disc which is thereby rotated about the pin 80 when the shaft 73 turns. The switch disc is provided with three sliding contacts (corresponding to the contacts 39, 40, 41) disposed at different distances from the pin 81. The plate 79 has contact surfaces corresponding to the contacts 42, 43, 44 and 44a, Fig. 7 (not shown).