| 摘要 |
890,238. Change-speed control. LUCAS (INDUSTRIES) Ltd., JOSEPH. Aug. 23, 1960 [Sept. 1, 1959], No. 29746/59. Addition to 841,706. Class 80 (2). [Also in Group XL (c)] The electrical control for an overdrive or other change-speed gear in a motor car of the parent Specification, acting in dependence of engine speed by electrical impulses derived from the primary coil 1 of the usual ignition circuit having a contact-breaker 3 and a spark-reducing condenser 4, the impulses being applied through a smoothing inductance 8 to two clipping diodes 6, 7, is modified by the use of a two-stage transistor amplifier circuit 14, 19 controlling a solenoid 20, actuating a switch 20a effecting ratio shifts. Impulses from the clipping diodes 6, 7 are applied through a capacitor 9 to a pumping diode circuit 10, 11 connected through a resistor 15 to the base of the transistor 14. A potentiometer 18 connected across the negative and positive terminals 2, 5 of an accumulator energizing circuit supplies a bias in opposition to the impulses fed from the pumping diodes 10, 11. On starting the car from rest, the base of the transistor 14 is so biased that the transistor supplies current through a resistor 16 and thereby biases the base of the transistor 19 to prevent transmission of current therethrough. With increase in engine speed, the bias of the base of the transistor 14 changes, so that ultimately this transistor ceases to conduct. The bias of the base of the transistor 19 is then so changed that it transmits current, thereby energizing a solenoid 20 to close the switch 20a and effect a ratio upshift. Switching-on the transistor 19 increases the potential drop across a resistor 13 connected between the accumulator terminal 5 and the emitter of the transistor, thereby ensuring that the transistor 14 remains in a non-conducting condition. The solenoid 20 also controls switches 20b, 20c in circuits between the accumulator terminal 5 and the potentiometer 18, a switch 23 being opened by the car accelerator pedal to change the bias produced by the potentiometer 18 and prevent establishment of overdrive until a suitably high speed has been achieved, while a further accelerator pedal controlled switch 22 assists the switch 20c to prevent " hunting." A switch 20d closed on energization of the solenoid 20 is included in a circuit having a switch 24 closed when the car throttle is released, so that the base of the transistor 14 is then maintained at the potential of the positive battery terminal 5 however low the engine speed. To control change-speed gearing giving more than two ratios, two or more diode pumps and pairs of transistors may be provided for controlling a corresponding number of solenoids 20 &c. |
