Patent GB-1438839-A (GB)
Title: Apparatus for producing variable amplitude vibratory force
IPC: E01C19/28
Filed: 1973-10-15
Abstract: 1438839 Vibrated rollers KOEHRING CO 15 Oct 1973 [19 Oct 1972] 47977/73 Heading A1B [Also in Division F2]  A compacting device comprises a roller rotatably mounted on a support and a rotatable eccentric mounted within the roller for rotation about the roller axis independently of the roller to produce a variable amplitude vibratory force upon rotation, the eccentric comprising two eccentric fluid chambers rotatable about a common axis of rotation and adjustable valve means interconnecting the chambers for controlling the amount of fluid transfer within them upon rotation of the eccentric. In the embodiment shown in Figure 1, the roller 20 is mounted for rotation between a pair of support arms 22, 24 by means of bearing assemblies 26, 28 and shaft portions 30, 32. The bearing assemblies include conventional bearing arrangements (not shown) to permit roller 20 to rotate relative to support arms 22, 24 and to permit rotation of shaft portions 30, 32 relative to the roller. The rotatable eccentric 50 is mounted on shaft portions 30, 32 for rotation about the axis of the roller 20, a fluid motor (not shown) being coupled to one of the shaft portions to impart rotation to the eccentric 50. The eccentric 50 includes a fluid chamber 54 comprising a hollow cylinder 56 closed by end plates 58, 60 connected to the shaft portions 30, 32 by sleeves 62, 66 and pins 64, 68, also a fluid chamber 70 comprising a rectangular housing 72 and end walls 74, 76 mounted in fluid-tight engagement on the outer surface of cylinder 56 at a position diametrically opposed to the axis of cylinder 56 in relation to the roller axis. Chamber 54 acts as a fluid reservoir to supply fluid to eccentric chamber 70. A control valve 80 includes an inlet tube 82 rotatably mounted in a passage provided in a valve block 84 secured to end plate 58, the inlet tube 82 including a bent portion 86 (Figure 2) having an inlet orifice 88 movable between various radial positions within cylinder 56 by means of a handle 90, while a conduit 94 extends from the lower end of valve block 84 to a fluid inlet 96 provided in housing 72 of eccentric chamber 70. A baffle plate 98 mounted within the reservoir chamber 54 serves to restrict fluid movement within the chamber during rotation of the eccentric. Fluid transferred from the reservoir chamber 54 to the eccentric chamber 70 during rotation drains into the reservoir chamber 54 upon termination of the rotation via a pair of ball check valves 101, 102. These valves are closed during rotation as their balls 106 are driven by centrifugal force into contact with the valve seats. A predetermined amount of fluid is initially supplied to reservoir chamber 54 and, upon operation of the fluid motor (not shown), rotatable eccentric 50 is rotated about the axis of the vibratory roller 20. The fluid in reservoir chamber 54 then adopts the configuration indicated by the shaded region 108 in Figure 2 as a result of the centrifugal forces exerted on the fluid, the size of this region 108 being limited by the position of the valve inlet orifice 88 and the excess fluid being transferred via conduit 94 to eccentric chamber 70 where it adopts the configuration indicated by the shaded region 110. The fluid in this region constitutes an eccentric weight that is rotated about the axis of roller 20. The amplitude of the vibratory force produced by this rotation can be precisely adjusted by rotating handle 90 of control valve 80 to change the position of inlet orifice 88 of tube 82 in reservoir chamber 54 to vary the amount of fluid transferred to eccentric chamber 70.