GB1247495A - Brake control device for preventing a rotating wheel from locking when the wheel is braked - Google Patents

Abstract

1,247,495. Anti-skid braking systems. U. C. EKENBERG, M. J. O. HOLST, and R. E. NORDSTROM. 25 April, 1969, No. 21280/69. Addition to 1,247,049. Heading F2F. The device of the main invention is modified by incorporating frequency-increasing means for causing the oscillation-frequency of the brake-releasing means to exceed the driving- pulse frequency. As shown in Fig. 1, when the frequency of oscillation of the sensing device 1 equals the resonance frequency of the spring-mass system 2, 3, cam member 20 raises and lowers cam follower 21; in the raised position, port 7a in valve body 5 is obturated by sealing gasket 16, so brake fluid inlet 13 is shut off by sealing gasket 7 and the wall of the valve body from outlet 14 leading to the brakes. At the same time, the effective volume of chamber 10 is increased by the raising of the valve body 5 with its open-ended bore 18. Thus the braking force acting on the wheel is first stabilized and then released. This cycle is repeated until the wheel speed rises above the critical value giving rise to the resonance. The brake is then applied again until the critical speed is again reached, whereupon the cycle re-commences. It will be observed that the frequency of oscillation of valve body 5 is twice that of the sensing device 1. In Fig. 2 the heavy mass 3 takes the form of an oscillatory disc having a pivoted link connection 26, 27, 28 with a control rod 4 having a reduced end co-operating with spring-loaded ball-valve 8, 7, passage 7a, chambers 10 and 9, and inlet 13 and outlet 14 in well-known manner. In Fig. 3 (not shown), the rod 4 is spring- loaded outwards, and has at its end a spherical cam-follower co-operating with a protuberance on the edge of the disc 3. In Fig. 5 (not shown), the spring-loaded rod 4 ends in an abutment plate co-operating with a spherical body on the edge of the disc. In Fig. 6 (not shown), the disc axis is parallel with rod 4, and a roller at the end of rod 4 co-operates with a protuberance on the flat surface of the disc. In Fig. 4b spring 2 is a torsion spring below and coaxial with the disc 3, slot 20 in disc 3 co-operating with roller 21 on rod 4. In Fig. 7 a stiff resilient blade 41 is attached to the periphery of disc 3 (acted upon by spring 2). Blade 41 extends through guide means 42 to a link system 43 connected to rod 4. If blade 41 should crack, the brake fluid supply to the valve will close ball valve 8. The frequency of the mechanical pulses generated by the wheel or shaft may be reduced during powerful braking, to bring about antilock brake release sooner, by the device shown in Figs. 8a, 8b. Toothed wheel 33, Fig. 8a, having secured to it an annular mass 34 (forming a flywheel unit) is rotatable on bearing 31 about input shaft 30. A second shaft 32, carrying freely-rotatable planet wheels 35, is rigidly attached to shaft 30. A second toothed wheel 36 is adapted to rotate in relation to shaft 30 by means of a friction clutch 38. A cam surface 37 on this second toothed wheel 36 co-operates with sensing device 1, Fig. 8b. In operation, during normal running and light braking, all the parts rotate at the same speed as the input shaft 30. On powerful braking, however, the flywheel unit 33, 34 will over-run shaft 30, and through planet wheels 35 will impart a reverse relative movement to toothed wheel 36, which will thus rotate at a lower speed than shaft 30. The frequency imparted to sensing device 1 will thus be reduced.