Patent GB-489337-A (GB)
Title: Improvements in means for eliminating vibration in internal-combustion engine crankshafts and the like
IPC: F16F15/14
Filed: 1937-01-22
Abstract: 489,337. Vibration dampers. BRISTOL AEROPLANE CO., Ltd., and FEDDEN, A. H. R. Jan. 22, 1937, No. 2001. [Class 108 (iii)] [Also in Group XXVI] An internal-combustion engine crank-web has masses thereon which oscillate in circumferential and longitudinal directions respectively with respect to the crank-shaft axis to eliminate selected orders of torsional and longitudinal vibrations. In the construction shown in Fig. 1, the crank-web 30 has a T- shaped portion 31 ; the horizontal part carries the mass for damping torsional vibrations and the leg part 32 carries the mass for damping longitudinal vibrations. The torsional mass is made in halves 35 connected by bolts 36 and axles 38, 39, and is suspended from the web 31 on axles 40, 41 by links 46, 47. Roller bearings surround the axles 38 ... 41. A U- shaped body 53 slung from the leg 32 by two parallel cranked suspension shafts 55 eliminates longitudinal vibrations. Washers 65, 66 shaped to oscillate with the shafts are arranged between the body 53 and the leg 32. Rings 67...70 locate the bearing-rolls 56, and split collars 72 locate the rings. Channel-shaped members 74, 75 limit the oscillations. In a modification of this construction, Fig. 6 (not shown), the longitudinal mass forms part of the torsional mass which is a single forging suspended by links. At its lower end it is formed with two limbs between and from which the longitudinal mass is slung. In this construction, the part 31 is provided with leaf springs to limit the shock of impact between it and the oscillating mass. In the construction shown in Fig. 9, the longitudinal mass 87 is suspended in the torsional mass which is suspended on crank-pins 115 on short shafts 116, 117 carried by the part 31. All bearings are provided with rollers. The torsional mass 123 may be extended below on one side. Abutments 105, 106 limit the vibrations. Their upper faces limit the torsional mass vibrations, and the lower faces, the longitudinal-mass vibrations. In a further construction, Fig. 13 (not shown), the crankweb is formed with two parallel extensions which support between them in roller bearings a flat trunnioned block from which is suspended in roller bearings on a pair of short crank-shafts the torsional mass. A selected component of longitudinal vibration is eliminated by the vibration of the trunnioned block and the torsional mass in the manner of a simple pendulum about the axis of the trunnions, and the torsional vibration is damped by rocking of the torsional mass alone on the crank pins. In a modification of the arrangement shown in Fig. 1, the crank-web and torsional mass are each provided with oblong holes in which are mounted pivot pins as described in Specification 460,088. Similarly the longitudinal mass is slung by pivot pins from the leg 32. A modification of the arrangement shown in Fig. 9 is described according to which the crank-shafts are replaced by pivot pins. The surface of the oblong holes may be reinforced by case-hardened inserts 184, Fig. 22. Preferably the crank balanceweights of both crank-webs are employed as vibration dampers. One crank-web may carry a mass to eliminate one order of torsionalvibration and the other crank-web a weight to eliminate another order. Each crank-web may also carry a mass which eliminates a selected order of longitudinal vibration. Preferably the longitudinal masses eliminate the same order of vibration. In the arrangement shown in Fig. 23, the masses 80 and 181, 182 eliminate the first and 4¢ order respectively of torsional vibration as found in 9-cylinder, radial cylinder engines, and the weights 87 and 53 both eliminate the 4¢ order of longitudinal vibration. According to the Provisional Specification, in a construction similar to one referred to above, Fig. 13 (not shown), pivot pins carry the weights, and the positions of the longitudinal and oscillating masses are reversed, the outer elements controlling the torsional vibrations. Similarly in a construction similar to that shown in Fig. 23, the position of the masses is reversed. Specifications 444,222 and 478,962 also are referred to.