Patent GB-1209322-A (GB)
Title: Infinitely variable transmission system
IPC: F16D65/22
Filed: 1967-06-30
Abstract: 1,209,322. Infinitely variable gearing; vibration dampers. NATIONAL RESEARCH DEVELOPMENT CORP. 18 June, 1968 [30 June, 1967], No. 30376/67. Headings F2D and F2S. A transmission system comprises at least one roller 8, Fig. 1, contacting the toroidal surfaces of input and output discs 1, 6, a tiltable mounting for each roller, a ball bearing 4 through which the force urging the input and output discs together is applied, means for selectively coupling the cage to a vehicle final drive and alternatively leaving the cage uncoupled and means for alternatively, respectively, disconnecting and connecting the output disc from or to the vehicle final drive. The input shaft 2 drives disc 1, which is loaded by spring 14, a space 13 being filled with fluid. Balls 7 run in tracks in race 5 and output disc 6, the latter being connected via a drum 27 to clutch discs 28. Ball cage 15 is connected through a ring 16 and sleeve 18 to a toothed ring 19 and also drives a drum member 30 and clutch discs 29 through a uni-directional clutch 35. Pressure fluid introduced into chamber 40 urges a pressure disc against clutch discs 28, 29 and a thrust ring 36, the latter being connected to the drum 27 through a uni-directional clutch 43. Drum 30 is connected to toothed ring 33. A dog member 26, having internal teeth 34 and connected to the output shaft 20, can be engaged with toothed rings 19 or 33. The mechanism for tilting the rollers 8 is described in Specification 979,062 with an actuator 66 having automatic control as described in Specification 1,078,791 with modifications. Operation "First regims, neutral".-Because of the differing track diameters between disc 6 and race 5 the latter has to rotate faster than the disc to keep the ball cage 15 stationary (i.e. neutral ratio). This occurs when the rollers 8 are tilted to give an output/input ratio of slightly lower than 1:1. "First regime, forward or reverse".-In the geared neutral condition of the first regime forward or reverse drive is obtained by altering the ratio of the variable unit in the appropriate direction. Automatic changes are made by a driver control linked to the engine fuel control. To ensure movement in the required direction a pre-selector control is provided to change the sense of interaction between the driver control and the ratio controlling member of the variable unit. The pre-selector also provides an alternative connection to clutch 35 when reverse is required since the direction of relative rotation of its parts is in the non-engaging direction when cage 15 rotates anti-clockwise, sleeve 34 being linked to the pre-selector control so that dogs 34 and 19 are engaged when reverse is pre-selected. The preselector has a neutral position in which the output shaft is disconnected from the transmission system to enable the vehicle to be towed. "First regime, manoeuvre".-For rapid interchange between forward and reverse the preselector has a "manoeuvre" position in which engagement of clutch 28, 29 is prevented and "neutral", "forward" or "reverse" can be selected without changing over dogs 34 from engagement with dogs 19 to engagement with dogs 33, the engagement of clutch 28, 29 being inhibited. "Second regime, direct drive".-Space 40 is pressurized to engage clutch 28, 29 to give a direct drive between disc 6 and output shaft 20 via dogs 33, 34. Initially shaft 20 tends to speed up but the variable ratio is quickly lowered until the speeds of disc 6 and cage 15 correspond, clutch 35 being disengaged as the speed of cage 15 is reduced during the ratio reduction. The system includes a radial oscillation damper consisting of a toroidal sheath 72, Fig. 3, filled with silicone putty and retained within a metal channel 69 by a hollow ring 74. In another embodiment the sheath (72), Fig. 4 (not shown), is bonded to inner and outer rings (78, 79). In a further embodiment a strip moulding (81), Fig. 5 (not shown), having open pockets (82) interconnected by channels (83) is bonded to inner and outer rings (78, 79).