GB780666A - A system for effecting automatic control of a vehicle power transmission system - Google Patents

Abstract

780,666. Controlling change-speed gearing. LUCAS (INDUSTRIES), Ltd., J. Nov. 16, 1955 [Nov. 27, 1954; Feb. 14, 1955], Nos. 34438/54 and 4275/55. Class 80 (2). In a motor vehicle, automatic control of top gear (overdrive or direct drive) is effected by an electric generator a, driven by the engine or by the vehicle, whose voltage varies with speed and which is connected, through a rectifier b where necessary, to a relay winding c in series with a variable resistance d controlled by the accelerator or by engine suction so as to be increased with increased throttle opening, a normally-open switch h adapted to be closed by the relay c, a normally closed switch g adapted to be opened by kick-down of the accelerator, and a gear-changing electromagnet i adapted to be energized from a separate source under the control of a switch s operated by the relay c,'the switches g, h being arranged in series so that, when both are closed, they short-circuit at least the major part of the resistance d. Below a certain speed, dependent on the amount of the resistance d in series with the winding c and hence on the throttle opening, the current in the winding c is insufficient to operate the switch s and the magnet i remains deenergized. Above that speed, switch s is operated to energize magnet i, so as to bring top gear into operation, and switch h is closed, so as to hold top gear until the speed falls sufficiently to render the relay c ineffective or until kickdown of the accelerator. The resistance d may be varied by a sliding contact, or, as shown, by normally-closed short-circuiting switches f<SP>1</SP>, f<SP>2</SP> ... adapted to be opened'successively as throttle opening increases. Switch s may be a normally-open switch in series with the magnet i. As shown, however, it is a two-way switch and the magnet i is associated with a normallyopen switch m adapted to be closed by an electromagnet n and with a normally-closed switch p adapted to be opened when the throttle is closed. Normally-closed switches q, rare operable at will or during reverse drive to render the magnet i inoperative. With switch s positioned as shown, magnet n is shortcircuited and magnet i de-energized. When switch s is moved to its other position by the relay c, magnet n is energized to close the switch m, and thus energize magnet i. A signal lamp t is arranged in parallel with magnet i. Instead of being operated by winding c, switch h may be actuated by magnet n or by magnet i.