Patent GB-1202994-A (GB)
Title: Improvements in braking devices for self-propelled vehicles
IPC: B60T8/28
Filed: 1968-08-09
Abstract: 1,202,994. Braking-pressure control devices. FRANCAISE DU FERODO SOC. ANON. 9 Aug., 1968 [10 Aug., 1967], No. 38242/68. Heading F2F. A vehicle braking device comprises an hydraulic actuating element and a braking corrector interposed between the actuating element and at least one of the brakes, the braking corrector being responsive to the instantaneous deceleration of the vehicle and to the dynamic loading applied to the corresponding wheel, so that the braking force is a function of these factors; the function specified is the sum of a product term (deceleration multiplied by loading), linear terms (deceleration and loading, separately), all qualified by constants, and a constant term. As shown in Figs. 1 to 3 and 5, the braking corrector includes a pressure converter 34 interposed between pipe 19 from a master cylinder 10 and pipe 22 leading to the rear brakes 23, 24 of a vehicle. The pressure converter 34 includes a ball valve 41, Fig. 5, urged to closure by a spring 42 in the inlet region 20A, and located so as to be unseated when appropriate by a piston 36 having a finger 38, to provide communication between inlet 20A and outlet 20B through a chamber 37. Valve actuation.-The position of piston 36 is governed by a U-section element 46 hinged at 47 to the converter housing 34 and carrying a finger 45; the element 46 is integral with a tube 33, forming a lever 52, Fig. 2, on which is disposed a slidable weight 53, separately supported. The weight 53 is suspended by a yoke 57, Fig. 3, from a loop 59 carried by the frame or coachwork 60, Fig. 2, of the vehicle, while housing 34 is carried by the housing 44 of the rear axle. The position of weight 53 along tube 33, and hence its moment about the hinge 47, is thus dependent on the load on the rear axle. The angular position of the tube 33 and weight 53 in the vertical plane through the arrow 66, Fig. 2, is dependent on the deceleration of the vehicle. A spring 49 is set so that normally the valve 41 is just open. When the brake pedal 12 is depressed the deceleration caused by the front brakes results in the pivoting of the lever 33-46 by the weight 53 and consequent opening of valve 41 and application of the rear brakes. When the outlet pressure in chamber 37 is sufficient to force piston 36 back against the action of the weight 53, the valve closes. Modifications-weight, tube and suspension.- Instead of having a sleeve 53A, Fig. 2, the weight 53 may be provided with a washer (67), (Fig. 8, not shown), having a down-turned inner periphery clear of tube 33. At uniform speeds the weight may slide up or down, as before, but on tilting of tube 33 during deceleration, the weight 53 tips slightly and is thereupon prevented from further downward movement by the wedging action of the washer. The lower end of tube 33, below a weightarresting pin 57A, Fig. 2, may have secured to it a flat blade (69), (Fig. 9, not shown), transverse to the vehicle axis, the air flow acting on this blade introducing a vehicle-speed parameter; it acts in the opposite sense to the weight 53 and thus serves to reduce the braking moment exerted on the rear wheels at high speeds. The loop 59, Fig. 2, may be elongated, Fig. 10, (not shown), the top of the yoke 57 then being accommodated in a roller (70) which follows the forward displacement of weight 53 during braking; the response of the mechanism is thus modified. The weight 53 may be replaced, and the lever 52 modified, by the features shown in Fig. 11, where two rollers interconnected by a spindle 76 roll on a horizontal path 78 parallel to the longitudinal axis of the vehicle and provided in a cage 77 pivoted at 79 to a bearer 77A solid with the vehicle chassis 60; the spindle 76 bears against a lever 80. In Fig. 15, applicable to a vehicle having an hydraulic or pneumatic suspension system, the lever of the braking corrector is formed jointly by a cylinder element 105A into which the suspension pressure (representative of the load on the rear axle of the vehicle) is conveyed through an opening 106, and by a piston element 105B suspended by a spring 107 and carrying the weight 53. The cylinder element has journals 110 for articulation on the housing of the pressure converter.