GB1312797A - Vehicle braking systems - Google Patents

Abstract

1312797 Photo-electric control of braking system, liquid level indication GIRLING Ltd 22 July 1971 [11 Aug 19701 38544/70 Headings G1A G1H [Also in Division F2] In an anti-skid braking system in which the braking pressure is relieved when the deceleration of the braked wheel exceeds a predetermined value an optical signal generating means transmits light pulses from a source to a photo-electric cell at a frequency dependent on the speed of rotation of the braked wheel and an electric current generated by the cell energizes the means controlling the braking pressure. Each wheel has an apertured or transparent modulator 1 which interrupts the light falling on the cell, the light singals being transmitted for example via light transmitting cables 5, 7, Fig.3. Instead of separate light sources at each wheel a common light source 6 comprising a lamp 8 energized by a battery 3 may be used, the light being transmitted to the wheels by cables 7 and returned to the control module 4 by cables 5 and warning lamps 10, 11, 12 indicating failure of the module 4 and indicating fluid level in reservoirs for the braking system are included. The cables 5, may be D-section units assembled in a single cable so that light passes down one half of a cable and is reflected back in the other half. In another embodiment Fig. 4 light from a source 16 is transmitted to each wheel by cables 17 and a photo-electric cell on each wheel feeds a current via electrical cables 18 to the module 4. A further light-transmitting cable 21 is formed at its free end with a reflective or refractive surface formed by a mirror or prism 22 and a similar cable 23 connected to a warning device 24 for indicating fluid level in a reservoir 25 has a mirror or prism 26, a float 27 normally preventing light from being transmitted from one to the other until fluid level falls below a predetermined value. The modulator 1 may, as in Fig. 5 for example, comprise a rotatable cup-shaped member having a peripheral skirt 28 with identical notches 29 and teeth 30 between them straddled by a U-shaped fitting 31 carrying light-transmitting cables 34, 35, or maybe a flat disc 44, Fig.12 having reflecting and non-reflecting surfaces 45, 46. Alternatively, the disc may be transparent or translucent and with teeth 50 having reflective surfaces 51, 52 Fig.15 or opaque with similar teeth. The light source, which may be a lamp or a solid state device, and detector may be positioned adjacent the modulator skirt, light guides being absent, Fig. 10, and Fig. 11 (not shown). Optical fibre bundles may be used some of which send light to and some from the area of the modulator. Two light cables may monitor the same modulator.