GB1454702A - Transmission - Google Patents

Abstract

1454702 Variable-speed gear ORSHANSKY TRANSMISSION CORP 16 May 1974 [17 May 1973 19 Feb 1974 15 March 1974] 21919/74 Heading F2D A torque-splitting variable-ratio power transmission for a motor vehicle or industrial drive comprises a planet gear having one element, e.g. carrier 17, connected to input 11; two output elements, e.g. ring 20 and sun 21, selectively clutchable to output 12; and a reaction element, e.g. sun 22, invariably connected by speed varying means, such as an hydrostatic gear 33, 36, or variable friction gear, to one, e.g. sun 21 of the said two output elements, the input, output and reaction elements being coaxial. Fig. 2 provides four forward and two reverse speed ranges between aligned input and output shafts 11, 12 by synchronously clutching either of two output members, ring 20 and sun 21 of an intermeshed planet train to output 12, with intervening cycling of a hydrostatic gear comprising pump-motor units 33, 36 invariably connected respectively through wheels 31, 30 and 35, 34 to a reaction sun 22 and the output sun 21. The planet carrier 17 is fast to input 12, and reduced and reverse ranges are provided by an output train 40 having intermeshed planets carried by the final output shaft 12. For range I the ring gear 20 is clutched at 50 to a sun 41 of the output train, a ring 45 of which is held by a brake 47. The hydrostatic gear 33, 36 is then cycled to produce output speeds increasing to a maximum and simultaneously reducing the speed of the idle sun 21 to synchronism, at which point range II is entered by engaging a clutch 53, connecting sun 21 to rear sun 41, and then disengaging clutch 50. Output speed is again increased by cycling the hydrostatic gear 33, 36, now backwards to reduce the speed of the reaction sun 22, thus increasing the speed of the output sun 21 and simultaneously reducing the speed of the idle output ring 20 which finally synchronises with that of the final output shaft 12, whereupon range III is entered by engaging a clutch 54 to connect the ring 20 direct to output 12, releasing the brake 47 and clutch 53. Recycling the hydrostatic gear 33, 36 now increases the speed of the ring 20 whilst reducing that of the idle sun 21 eventually to synchronism, whereupon range IV is entered by releasing the clutch 54 and engaging a clutch 55 connecting the sun 21 direct to output 12. Output speed is now increased to a maximum by recycling the hydrostatic gear. The two reverse ranges are the same as the forward ranges I and II except that the brake 47 is released and a brake 48 applied to a second rear ring gear 46. In Fig. 7, not shown, the front ring gear becomes the input member and the planet carrier an output member, and one hydrostatic unit is a fixed displacement one. Fig. 8, not shown, uses the same arrangement, but dispenses with the clutches 53, 54 of Fig. 2, the sun 41 being fast to the output sun 21. The output train is a simple sun-ring-planet train with one brake. Three ranges are provided and reverse is obtained in the first range by extending the adjustment of the hydrostatic gear. In Fig. 9, not shown, the reaction sun 22 of Fig. 2 is replaced by a reaction ring (87), the hydrostatic gear connects that ring (87) to the output ring (86) which is clutchable by a single clutch (104) to output 12, the output sun (85) being fast to the sun (89) of the simple sun-ring- planet output train, which has output-carried planets and a single brake (94) for the ring. Only two forward ranges are provided by the clutch and brake, reverse is again obtained by adjusting the hydrostatic gear beyond the maximum range speeds. Fig. 11, not shown, is similar to Fig. 9, not shown, except that the hydrostatic gear is replaced by a simple toric disc and roller friction gear, an idler being interposed between one disc and the reaction ring gear to accommodate the direction reversal of the friction gear. In this case neither friction disc can reach the stationary condition included by the hydrostatic gear. Fig. 12, not shown, has a similar friction gear arrangement to Fig. 11, not shown, but has the additional clutch of Fig. 8, not shown, to provide three ranges. Fig. 13, not shown, is a two-range gear suitable for a passenger car. The primary train is the same as that in Fig. 2, but the hydrostatic pump-motor units are arranged separately on diametrically opposite sides of a two output clutch unit, no output planet train being used. In a first range the output sun 21, in addition to driving the shaft (148) of one pump-motor unit, (150) also drives back mechanically from that same shaft (148) through a wheel pair (151, 152), and one (154) of the clutches to the output shaft 12, whilst in the second range the output ring gear 20 drives the output shaft 12 directly through the other clutch (144). The other pump motor unit (160) is drivingly connected through a wheel pair (157, 156) to the reaction sun 22 as in Fig. 2, and both units take reaction in the second range, there being a double torque-split. For reverse, one hydrostatic unit (150) is held at full displacement whilst the other (160) is put over centre. Fig. 16, not shown, uses the same arrangement as Fig. 2, shown, but substitutes dog clutches and brakes for the friction ones 50, 53, 54, 54 and 47, 48 of Fig. 2 and adds a friction or synchronized positive brake (133) for the hydrostatic input shaft 32 and a similar clutch (137) between input 11 and the output ring 20 to lock up the planet train. This additional brake establishes positive zero speed for the reaction gear 22 at the end of ranges I, II and IV and thus provides exact synchronizing at range change points to avoid any loss of synchronism due to leakage on the hydrostatic look produced by zeroizing the pump-motor unit 33. The additional clutch (137) locks up the planet gear when all its elements are rotating at substantially equal speeds at the changeover points from range I to II and III to IV, thereby again obtaining absolute synchronizing independently of hydraulic leakage. In Fig. 17, not shown, the lock-up clutch (137) of Fig. 16, not shown, is arranged between the output sun 21 and planet carrier; in Fig. 18, not shown, between the output sun 21 and ring 20, in Fig. 19, not shown, between reaction sun 22 and the planet carrier, and in Fig. 20, not shown, between the wheel 30 and output sun shaft 28. The Specification includes graphs showing the speeds of all the members of the gear throughout all the speed ranges, and also percentages of hydraulic and mechanical torques transmitted and of hydraulic torque re-circulated. Ratio ranges provided range from 15 to 1 for a truck to 6 to 1 for a passenger car, and include overdrive ratios. Teeth 25 on the input member 11 provide a power take-off for auxiliary drives.