GB772153A - Improvements in or relating to a speed-responsive electromagnetic switch control - Google Patents

Abstract

772,153. Magnetic fluid couplings. EATON MANUFACTURING CO. March 5, 1955, No. 6555/55. Class 35. A magnetic fluid coupling for a motor vehicle is energized in dependence on the throttle setting and is fed with a small reverse current to disconnect it. Controlling current passes from a battery 1, through ignition switch 7, switch 45 which closes when a gear is engaged, and switch 47 which closes as soon as the accelerator pedal 46 is moved, to energize relay B. Current then passes through contacts B1. B2 and a resistance controller 43 operated by the accelerator pedal to the clutch coil 39 to take up the drive. The primary winding 3 of the ignition coil 5 is fed through an interrupter 9 in the usual way, and in addition impulses are fed through a rectifier 33 and adjustable resistor 49 to the coil A of a relay 37, this coil being shunted by a condenser 35. As the engine speed rises, the frequency of impulses passing through the coil A becomes sufficient to operate the relay and close the contacts A1, A2. Contacts A2 serve to shunt the switch 47 to prevent de-energization of the coupling when the throttle is closed at speed. Contacts A1 close a by-pass circuit, including a resistor R1 and an additional winding AA on the relay 37, to prevent the release of the throttle pedal weakening the coupling field excessively. The coil AA acts in opposition to the coil A so as to reduce the differential of the relay 37, i.e. increase its sensitivity to changes in engine speed. The adjustable resistor 49 through which the relay is energized, may be controlled manually, or as shown, in dependence on the throttle position. Alternatively the relay coil A may be tapped. Demagnetization of the coupling on opening of contacts B1, B2 is produced by small current fed from the battery through resistors R2, R3, and through the coil 39 in verse direction. Specifications 671,219, 677,534 and 742,545 are referred to.