GB1152852A - Improvements in or relating to Braking Systems for Vehicles - Google Patents

Abstract

1,152,852. Automatic brake control; warning devices. SUMITOMO ELECTRIC INDUSTRIES Ltd. 10 May, 1966 [17 June, 1965; 18 Oct., 1965; 25 Dec., 1965; 15 March, 1966], No. 20574/66. Headings F2E and F2F. A method of automatically operating the parking brake of a vehicle comprises detecting whether or not the vehicle is moving and detecting movement of the accelerator and/or clutch pedal beyond a predetermined limit and employing the resulting information to operate the parking brake when the vehicle is stationary and the accelerator pedal is in an impressed position and/or the clutch pedal is in a pressed position. The parking brake operating system comprises a servo unit 24 coupled to the brake through transmission members 28, 29, 33, 36 also operable by a hand brake lever 42. The servo-unit is supplied from a vacuum source 23 by an electro-magnetic valve 13, 15, which connects pipes 17, 18 when the coil 13 is energized. An electromagnetic valve 137 is provided to vary the speed of operation of the servo. The circuit includes a switch 9 opened by a vehicle movement detector when the vehicle is in motion in either direction; a switch 10 operable by the accelerator pedal to open on acceleration movement thereof; a switch 11 which opens when the clutch pedal is not pressed; a switch 45 which closes, together with switch 143, when the brake pedal movement is excessive; and a switch 144 which closes when the pressure in the hydraulic line is excessive. Operation.-With the vehicle at rest and the ignition key inserted at 2, switches 9 and 10 are closed and current flows through the coil 7 of relay 8, to close switch 6, and through coil 13 to apply the brake servo. Depression of the clutch pedal to select gear closes switch 11, depression of the accelerator opens switch 10. As the clutch is engaged switch 11 opens to deenergize brake valve coil 13 and release the brake to permit the vehicle to move, switch 9 then opening to de-energize coil 7 and open contacts 6, to prevent reapplication of the brake by the clutch or accelerator switches while the vehicle is in motion. If, when running, the clutch is disengaged and the service brake applied, contacts 6 close as the vehicle stops and coil 13 is energized to operate servo 24. If a fault in the service brake system allows excessive movement of the brake pedal, switches 45, 143 close to energize the coil 13 and apply the brakes, the switch 143 energizing coil 140 to remove the restricting valve 138 (which may alternatively be in the supply pipe 18) and allow the servo 24 to be applied rapidly irrespective of the operation of the switch 9, i.e. while the vehicle is moving. When the vehicle is parked the hand brake lever (42) is applied, the device 4 switched to 'L' and the key removed from 2. Re-insertion of the key to start the engine will then energize brake coil 13 through line 46 to maintain the braking irrespective of the condition of switches 10, 11, to act as an anti-theft device. Indicators.-A lamp 20 in parallel with coil 13 gives indication that the brake is applied.