Patent GB-1460817-A (GB)
Title: Split torque type hydrostatic transmission
IPC: F16H47/04
Filed: 1974-03-28
Abstract: 1460817 Variable speed gear AISIN SEIKI KK and TOYOTA JIDOSHA KOGYO KK 28 March 1974 [28 March 1973 23 May 1973 31 May 1973 3 July 1973 4 July 1973 (2)1 13859/74 Heading F2D A torque-splitting hydrostatic-mechanical gear, driving a final output shaft 4 from an input 2, comprises a planet gear 30, the torque reaction of which is controlled by a fixed positive displacement pump-motor 5 in circuit 72 with a variable positive displacement swash-plate type pump-motor 6, driven by the input shaft 2, between which latter and the planet gear 30 is arranged a forward-neutral-reverse gear 10, controlled by a lever 20, the second pump-motor 6 being capable of adjustment to positive and negative outputs on each side of zero in accordance with the selected direction of drive, so that the first pump 5 provides torque reaction for both forward and reverse drives. In addition the hydraulic gear is used to synchronize the reverse gear. In Fig. 1 the reverse gear 10 includes inputdriven forward and reverse gear trains 11, 14 and 12, 13, 15, clutchable by a sliding clutch 21, actuated by the FNR lever 20, to a countershaft 17, driving an aligned intermediate shaft 3 through meshing wheels 22, 23. The intermediate shaft 3 is the input shaft of the planet gear 30 which comprises suns 31, 32, fast on the shaft 3 and output shaft 4 respectively, a reaction sun 33 and a reaction carrier 40 for stepped planets 36, 37, 38. The sun 33 and carrier 40 are selectively connectible to the reaction pump-motor 5 on a fixed axis countershaft 51 through concentric sleeves, meshing wheel pairs 35, 54 and 42, 55, and selective clutches 51, 52 respectively, which provide high and low ranges of operating ratios. Synchronizing.-The hydrostatic gear 5, 6 is used for synchronizing entry into forward and reverse as well as range change, for which purpose the connecting lines 70, 71 of the pumpmotors 5, 6 can be short circuited, to break the hydrostatic drive, by a by-pass valve 60, actuated by a cam 68, turned mechanically by the FNR lever 20, to be in the open position, shown, when the lever is in the neutral setting, and also opened by engine speed responsive pressure 75 acting at 63 and supplied by a pump 73, constantly input driven and also serving to provide make-up for the hydrostatic pumpmotors 5, 6 through a restrictor 79, relief valves 80, 81 and non-return valves 77 &c. The synchronizing sequence for a shift by the lever 20 from N to F, with stationary output 4 is as follows. In N the by-pass valve 60 is closed by the lever 20 acting on the cam 68. The low range clutch 51 is first engaged and the pumpmotor 6 adjusted to maximum displacement in the positive direction. With clockwise input rotation at 1 the input pump-motor 6 is driven counterclockwise and hydraulically drives the reaction pump-motor 5 in the same direction. With initially stationary output 4 the reaction pump-motor 5 drives the sun 33 clockwise and the reversing countershaft 17 counterclockwise, which, with suitable gear ratios, synchronizes with the similar rotation of the input driven wheel 14, so that the reversing clutch 21 can be clutched synchronously thereto for forward drive F. Similar conditions obtain for synchronizing the reverse clutched wheel 15, but here the pump-motor 6 is set for maximum output in the negative direction to give clockwise rotation to the reaction pump-motor 5. Subsequent to engaging either F or R the lever 20 opens the by-pass valve 60 at 68, disabling the hydrostatic drive until, by accelerating the engine speed above idle, pressure from the engine-driven pump 73, acting at 63, again closes the by-pass valve 60, to provide a split-torque drive to output 4 through the hydrostatic gear 5, 6 and planet gear 30. Drive to output 4 then occurs at increasing speed ratios as the displacement of the input pump-motor 6 is reduced from maximum to zero, at which point the reaction pump-motor 5 acts as a stationary reaction member, and further increase by increasing displacement of the pumpmotor 6 to a maximum negative value. At this point the low and high range clutches 51, 52 can be changed over synchronously, (with a suitable choice of gear ratios) and the output speed can be further increased by reducing the displacement of the pump-motor 6 again to zero and then increasing it to a positive maximum. Modifications.-In Fig. 2, not shown, the bypass valve 60 is omitted, the hydrostatic circuit between the pump-motors 5, 6 being permanently closed. The planet gear comprises two trains in parallel and used singly in the respective ranges. Both trains have suns and ring gears, the rear sun (131) and front carrier (137) being fast to the planetary input 3; the front ring (139) and rear carrier (132) to output 4; whilst the front sun (136) and rear ring (134) form the two reaction members for selective connection to the reaction pump-motor 5. Fig. 3, not shown, modifies Fig. 2, not shown, by changing the planetary connections. The rear carrier (132A) and front sun (136A) are fast to input 3; the front carrier (137A) and rear ring (134A) to output 4; and the two reaction members are the front ring (139A) and rear sun (131A). Fig. 4, not shown, again modifies Fig. 2, not shown, by arranging the range-selecting clutches (151, 152) concentric with the planetary input and output shafts 3, 4, and connected through a common single meshed wheel pair (144B, 146B) with the reaction pump-motor 5. This same arrangement is used in Fig. 8 (not shown), but with a different planet train, of the overlapping type, having a common output carrier (236), planets having two steps meshing respectively an input sun (231) of the rear train, and reaction ring (235) and sun (232) of the front. In Figs. 13 and 14, not shown, the planet gear consists of two sun ring trains, the front one (335) a simple train, the rear (341) having intermeshed planets. All the planets are on a common output carrier (340), the rear ring (339) being input, the two suns (331, 336) together form one reaction member, the front ring (333) the other. Fig. 13, not shown, has a single common drive (144B, 146B) to range clutches (151, 152) concentric with the input and output shafts 3, 4, whilst Fig. 14, not shown, uses the two -train reaction connection as in Fig. 1. Figs. 15 to 17, not shown, all use the same simple and intermeshed planet trains as Fig. 13, not shown, but with planetary connections differing as follows. Fig. 15, not shown, front carrier and rear sun to output 4, rear carrier to input 3, rear sun and front ring one reaction member, front sun the other. Fig. 16, not shown, front carrier and rear ring to output, rear sun to input, common carrier one reaction member, front sun the other, Fig. 17, not shown, front carrier and rear sun to output, rear ring input, rear carrier and front sun one reaction member, front ring the other. In Fig. 21, not shown, the range selector clutches (450), with their two gear wheels (455, 457), are mounted on the shaft (53) of the pumpmotor 5 and mesh gear wheels (456, 458) on shafts (443, 444) concentric with the planetary input shaft, which is a sleeve (3A) between the two reaction shafts (443, 444). The front sun ring train (436) has intermeshed planets, the rear (441) is a simple sun-ring train. Input 3A is to the front ring, output rear carrier, one reaction member the front sun and rear ring, the other the rear sun. Fig. 24, (not shown), is similar, but the two range selector clutches (451A, 452A) are now arranged on opposite ends of the main gear concentric with the main shafts. Fig. 25, (not shown), has a similar arrangement but uses two identical sun-ring planet trains. Fig. 26, (not shown), is similar to Fig. 25, (not shown), but the range selector clutches are on the countershaft of the pump-motor 5 and the reverse gear 10 has a sliding wheel instead of the double clutch.