Back-up braking in electro-hydraulic (EHB) braking system

Abstract

An electro-hydraulic braking system of the type which operates normally in a brake-by-wire mode wherein hydraulic pressure is applied to braking devices at the vehicle wheels in proportion to the driver's braking demand as sensed electronically at a brake pedal (10), and which, if the brake-by-wire mode should fail, operates in a push-through mode wherein hydraulic pressure is applied to the braking devices at the vehicle wheels by way of a master cylinder (34) coupled mechanically to the brake pedal (10), the system including also an electric parking braking device for enabling the braking devices to be actuated for parking braking purposes but which is also arranged to be activated to supplement push-through braking in the event of failure of the brake-by-wire mode. Electro-hydraulic braking at the rear axle of the vehicle is allowed only when a control unit (13) of the electro-hydraulic braking system has confirmation that the electric parking device is in a satisfactory operational state.

Dependencies are inferred from the claim text.