Load splitting hydromechanical transmission

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Load splitting hydromechanical transmission


Abstract
A hydromechanical drive has an input shaft connected permanently to the input of a variable volume hydraulic pump and to the planet carrier of a transmission amount. The pump turn drives a motor which in turn rotates the sun gear of the summing transmission which has a first planetary gear that meshes with the sun gear and with a respective ring gear and a second planetary gear meshing with the first planetary gear and a crown respectively. An output of the planetary gear transmission has a planet carrier connected to the ring gear of the second transmission planetary gear and a planet carrier sum permanently connected to the output shaft of the unit and can be connected via a clutch that can be open to the ring gear of the first planetary gear transmission sum. Furthermore, this transmission has a first output planetary gear meshing with the respective sun gear and with a respective ring gear and a second planetary gear meshing with the respective first planetary gear and with its own ring gear. The brakes can stop any transmission sprockets output. This transmission output may be replaced by a gearbox constant mesh gearbox. Therefore the force applied to the input shaft of the transmission is divided and fed to the summing transmission in part directly and in part mechanically through the hydrostatic transmission consists of the pump and motor.

Description
Field of the Invention
The present invention refers to a hydromechanical transmission . More particularly, this invention relates to a transmission of the type usable division load a piece of heavy duty equipment such as a crane or a tractor such .
Background of the Invention
The first motor or engine of a heavy piece of construction equipment or the like, normally has an output that rotates at a constant speed or velocity which at best can be varied within a predetermined relatively small range . Therefore, it is standard practice to provide a variable speed drive from an engine output as the first and the load to be operated , which may be the vehicle's wheels , a winch , or other peripheral device .A hydromechanical transmission described in SAE Publication 72 07 September 24, 1972 . It has two forward speeds and one reverse speed , and comprises a hydraulic transmission and gear . Hydraulic transmission comprises a pair of hydraulic machines , a pump and a motor, one of which is of variable volume. The mechanical transmission comprises a planetary gear transmission of four axes. This arrangement is configured for load sharing so that is possible with a limited variable speed or fixed input shaft unit for a continuously variable speed on the output shaft .In this arrangement the speed of forward and reverse under purely hydrostatic drive , which is actually no cargo division and all the force transmitted from the input shaft to the output shaft of the drive is transmitted through the hydrostatic pump - and - motor assembly. Obviously, the driving force transmission capacity of a unit of this type is limited at least in the two low-speed ranges by the hydrostatic assembly capacity .Therefore it is necessary in such a system, either to provide an extremely heavy mounting the pump - and - engine , or to reduce the maximum speed in both forward and reverse low gear so that the product of the velocity sometimes the pair, which determines the capacity of the disk, remains low and within the range of hydrostatic subset . For this reason the unit or be quite expensive as a result of having a large pump assembly - and - hydrostatic motor , or only provide a low gear and reverse very slow.Another disadvantage of this system is that the jumps of the vehicle when it started in forward and reverse. This action is the result of the inertia of the pump - and - motor. An axial piston pump is normally used and is normally constantly driven by the input shaft of the transmission. Thus, when the output shaft of the drive must stop the pump swash plate is aligned perpendicular to the pump shaft so that even though the pump is driven by the input shaft , it will act as an pump and motor of the hydrostatic subset not work. Only when the swash plate is tilted by a relatively large angle is the motor inertia to be overcome in order to start spinning and , therefore , drive the output shaft. As a result start and stop nervous assumes such a unit .Objects of the InventionTherefore, it is an object of the present invention to provide an improved hydromechanical unit .Another object is to provide a unit of the type described above which can be produced at relatively low cost and which provides relatively high output speed and high torque in all transmission ranges .A further object is to provide such a unit whose output shaft can be started without problems and smoothly from standstill .Another object is to provide an improved method of operating such a unit .
SUMMARY OF THE INVENTION
These objects are achieved according to the present invention in a unit of the general type described above but which comprises a gear -type transmission load adding or division has an input connected to the output side of the hydrostatic transmission , one input member mechanically connected to the input shaft of the transmission, and at least one output element. According to the present invention in all ranges and speeds divides the output force applied to the input shaft of the unit and part is fed through the hydrostatic transmission part and adding directly to the transmission , by what at any time hydrostatic transmission needs to carry all the load.According to this invention, the hydromechanical unit further includes a transmission output having at least an output element connected directly to the output shaft and a pair of input elements that can be connected to the output elements of the transmission amount. Therefore the force applied to the input shaft of the unit is first divided and passed partly through the hydrostatic transmission , and then recombined in the transmission of all, and thereafter applied to the transmission output that can step up or down as needed by the particular machine with the unit.This system can thus provide an output speed continuously adjustable through all ranks . While the transmission capacity of the hydrostatic load need not be more than about half , and usually no more than one third of the overall transmission capacity of the drive force . As a result, it is possible to reduce the unit size and cost largely without sacrificing in any way the ability or flexibility.In fact, it is possible to operate the system according to the present invention so that in a neutral mode or gear when the input shaft is being driven and the output shaft is at rest throughout the hydrostatic transmission , including engine it is operated at a relatively high speed , driving the transmission element in a direction the sum of respective input while the input shaft of the transmission drives the other input element of the transmission in the opposite direction by adding , so that the two movements are canceled. As a result all the hydrostatic transmission is in motion when the vehicle is being started , so a soft start is possible , allowing the operator of a piece of equipment that has such a unit to control their piece of equipment with an extremely fine touch, thus avoiding expensive and potentially dangerous accident .According to another feature of the present invention, the output transmission has a pair of output of one of which rotates in a direction opposite to each other no matter which actuates one of the input elements of the transmission output . According to this invention, the control means can switch between these output elements to rotate the output shaft in either direction, thus producing a very simple one reverse . All the advantages described above apply to first gear , which is to use the separation charge so that a relatively small set of hydrostatic can be used , are present in this backing .According to other features of the present invention , the transmission output is planetary type and has a planetary gear which is one of its inputs , a planet carrier which constitutes the other of its inputs , a first planetary gear meshes with the sun gear and constituting one of its output , and a second planetary gear meshing with the first planetary gear - but not with the sun gear - and which constitutes the other of the output elements , and a pair of independently rotating ring gears meshing with each of the respective planetary gears . The brake control means includes ring gears for . According to this invention , one brake is closed and the other is open for trips brake low range forward and reverse for the brake is closed and the other open brake .According to this invention, the control means further includes a clutch that connects the planet carrier of the transmission output to one of the output elements of the summing transmission , the planetary gear transmission of this output is connected to the other element transmission output of the adder . Therefore to offset the high range forward clutch is closed, thereby connecting the drive shaft directly to the output planet carrier transmission which in turn is connected to another element of the transmission output sum . In this position, the second or the output of the transmission is almost ineffective , because the two ring gears are allowed to rotate freely relative to each other so that even though the sun gear is still being driven by the element transmission output summing the planetary carrier can rotate freely in any direction. The direction of rotation of the planet carrier is, of course , determined by the other element of transmission output sum .According to yet another feature of this invention, adding the transmission is in itself a planetary gear transmission of four areas , which has a sun gear continuously driven by the output of the hydrostatic transmission , and a planet carrier continuously driven shaft transmission input . This in turn planet carrier carries a pair of planetary gears, one of which meshes with the corresponding gear and the other of which does not fit with the sun gear , but only engages with another planet gear . Each ring gear meshing with a respective one of the planetary gears are the two output elements. As mentioned above the ring gear can be connected through the clutch to the planet carrier of the transmission output and the other gear ring is connected permanently to the sun gear of the transmission output .It is also possible according to this invention to provide easily the transmission gear reducer output . In this case, the output shaft can be connected to any of various gears . One of thse pinions is driven continuously by the output element of the summing transmission , one of these pinions is connected to the other output of the summing transmission , and another of these pinions is connected to a reverse gear to this other output the summing transmission. The connection to the mentioned third pinion is made to reverse, while connecting with others is made for low end and high end .Also within the scope of this invention to provide a clutch or other connection directly and positively couples the output shaft of the drive to the input shaft thereof. When a connection of this type is the interconnection lines of the hydraulic pump and motor are outwardly biased in order to be effective depressurized , thus avoiding the system voltage .The system according to the present invention can be made very compact. The use of the planetary gear also allows a concentric arrangement of the various devices and the gears so that a relatively vibration-free can be produced . What is more the strength of startup can be reduced by approximately 15 %, since the system is operated so that the pump and motor can be operated at a relatively high speed , while the output shaft is held in a stalemate.
Brief Description of the Drawings
. Figure 1 is a schematic view of the unit according to the present invention;. Figure 2 is a diagram illustrating the operation of the unit of Fig . 1 , and. Figure 3 is a schematic view of another unit according to this invention.specific descriptionAs shown in the figure. January 1 unit 1 according to this invention basically comprises a housing 26 in which an input shaft 3 and a coaxial output shaft 9 are articulated . A motor 27 , typically diesel type , is connected to the input shaft 3 and a load 28 , typically constituted by the wheels of a vehicle, is connected to the shaft 9
 The shaft 3 carries an input gear meshing with a first gear carried on satellite 4 a shaft 36 parallel to axis 3 . The other end of this shaft 36 serves to drive axial piston pump variable volume 1 which has a control element or the swash plate indicated schematically at 32. The pump 1 is connected through hydraulic conduits 41 and 42 to a fixed-volume hydraulic motor 2 having an output element 34 carries a gear 10 which meshes with and drives a gear 11 of a planetary gear transmission sum or addition of load 30 .Also bears on the shaft 36 is a gear 5 which meshes with a gear 35 carried on an axle tube 7 coaxial with axis 3 and 9 and to carry on its end opposite the planet carrier 16 of the transmission 30. As the motor 27 rotates the input shaft 3 of the pump 1 will be driven continuously and the planet carrier 16 will also be operated continuously . The speed at which the sun gear 11 is driven , however , determined by the position of the control element 32 .Summing transmission or adding load - 30 comprising at least two planetary gears 12 and 13. The planetary gear 12 meshes with the sun gear 11 and ring gear 14. The planetary gear 13 meshes with the planet gear 12 and ring gear 15. Therefore the gears 12 and 13 will always rotate in opposite directions.The output shaft 9 is permanently and rigidly connected to a planet carrier 25, a transmission output 31 having a sun gear 20 connected through a tube axis 33 and the element 37 to the ring gear of the planetary gear 15 13. The planetary carrier 25 is also connected at 38 to one side of a clutch 17 connected to the ring gear 14 of the planetary gear 12. The planet carrier 25 carries a planet gear 23 meshing with the sun gear 20 and a planetary gear 24 meshing with the planet gear 23 so that once again the planetary gears 23 and 24 rotate in opposite directions. Finally, the transmission 31 includes ring gears 21 and 22 , respectively , which meshes with the planetary gears 23 and 24. Brakes 18 and 19 of the housing 26 can arrest the respective crowns 21 and 22.Furthermore, the input shaft 3 carries on its end remote from motor 27 a clutch 8, which may be connected through an intermediate shaft 6 directly to the output shaft 9. This shaft 6 passes concentrically and coaxially through the axis of tube 7 and 33.The unit described above operates in the manner shown in Fig . 2, the scrolling speed for a vehicle which incorporates the unit is shown in abscissa and the rotational speeds of the various elements of the drive are displayed on the ordinate axis . The drive is movable from a first end that starting low speed and a second range II for high-speed travel in a reverse gear R. As illustrated in the graph, the input shaft 3 rotates normally at a continuous speed , so that the axis of the tube 7 and the planet carrier 16 is also continuously rotating at a constant speed . For travel in the low range the clutch 17 is open to disconnect the planet carrier 25 ring gear 14 , the brake 18 is closed to stop the ring gear 21 and the brake 19 is open to allow free rotation the ring gear 22. To maintain the output shaft 9 at a standstill, it is necessary that the sun gear 20 and therefore ring gear 15 , to be stationary , such as when the sun gear 20 rotates , the planetary gears 23 will be forced to orbit and the planet carrier 25 will light. This stop is achieved by high-speed reverse rotation of the pump 1 through the appropriate tilt back his control element 32 so that even if the planet carrier 16 is being driven in one direction, the sun gear 11 can be rotated in the opposite direction , which has the net effect of the orbit around the sun gear 13 inside the ring gear 15 without rotating the ring gear 15. This action will rotate the ring gear 14 to a relatively high speed , which have no effect on the transmission and the ring gear 14 is not connected by the clutch 17 to elsewhere.The swash plate 32 swing forward in a neutral start rotating smoothly and increase the speed of rotation of the ring gear 15 , and therefore , begin to rotate the output shaft 9. As the output shaft 9 is connected through the planet carrier 25 and the inner planet gear 23 to the sun gear 20, the rate of increase of its speed of rotation is much smaller than the ring gear 15 which in turn is much smaller than that of the sun gear 11 directly driven by the motor 2. In fact, when the motor 2 is in complete deadlock , with the swash plate 32 located perpendicular to the axis of rotation of the axial piston pump 1, a vehicle or other load being operated by the drive will be moving. Forward displacement of the swash plate 32 beyond the locking point is smoothly and continuously increase the rotational speeds of the sun gear 15 and the output shaft 9, similarly , while decreasing the rotation speed the ring gear 14.Once the swash plate 32 is all the way forward, an automatic controller will simultaneously close the clutch 17 and brake 18 open , so that both the ring gears 21 and 22 can rotate freely in the housing 26 , but the output shaft 9 is coupled directly through the planet carrier 25 to the ring gear 14. The various gear ratios and speeds are , of course, such that at this point of change of the two sides of the clutch 17 move synchronously and there is little force on the effective angular ring gear 21 so that the change gear can make almost imperceptibly without appreciable wear of the parts of the unit. To increase the speed in the range II of the swash plate 32 moves from the full forward position back through the neutral position to the full back position as shown in Fig . Two . Concomitant result of this is a simultaneous and parallel increasing rotational speeds for the output shaft 9 and the ring gear 14 coupled directly to it. While the rotation speed of the sprocket 15 steadily decrease, but because the two ring gears 21 and 22 can rotate freely in the housing 26 this has no effect on the transmission operation . Assuming that the speed of the transmission output to be 1.0 lines switching point approximately one quarter of the distance between the stop position and the full speed position .As shown in the graph of FIG . 2 to the maximum speed in the range II input shaft 3 and the output shaft 9 are rotating synchronously . At this point the clutch 8 can be closed and a valve that can be opened pressure regulating 40 between lines 41 and 42 can be opened to pressurize hydraulic subset 1, 2 . Thereafter the speed of the motor 27 directly to the speed of the shaft 9 . This system is used to run on the roads, or lift a relatively light load with minimum wear away.When the vehicle is stationary , ie the oscillating plate 32 all the way back to the output shaft 9 is stopped, the unit is placed in reverse by simply closing the brake 19 , the brake 18 is open to the left and left clutch 17 disengaged . As the swash plate 32 is then moved back into the forward position the action is substantially identical to the rank I, except that a reversing speed for the shaft 9 is made ​​through the interposition of the second gearwheel 24 in the unit. As a result, the shaft 9 will swing back to an ever increasing rate with the forward tilting of the swash plate 32 , while the ring gear 15 rotates faster steeper than that of the shaft 9, but on a slope still considerably less than the increase in speed of the sun gear 11 as determined by the position of the swash plate 32 . The gear 24 is larger in diameter than gear 23 so that the R position has a maximum speed that is somewhat higher, equal to approximately half the maximum speed in the range II , the maximum speed in the range I the forward direction .It is observed that all the various controls can be operated easily by a single lever. A crank cam type can operate the swash plate 32 with appropriate switches or valves that control the opening and closing of the clutch 17 and brake 18 and 19.The arrangement of FIG . 3 is functionally identical to that of FIG . 1 except that the transmission 31 is replaced by a continuous transmission mesh stepdown 131. To this end, the ring gear 14 is connected through an element 138 to a gear 137 which meshes with a pinion itself carried on a shaft 139 106 offset from the shaft 3. The ring gear 15 is connected through an extension shaft 133 to a pair of pinions 134a and 135a . The sprocket 134a in turn meshes with another gear which forms the second half of a second part of the gear train and the pinion 134 meshes with another pinion 135a itself meshing with another gear 135b to form a gear train of three parts 134b 135c 135 . An output shaft 109 can be connected through a clutch 117 to the sprocket 139 through a clutch 119 and the pinion 134b through a clutch 118 to the sprocket 135c .Further, the shaft 106 is connected through gears 136 directly to the input shaft 3 and the other clutch 108 can lock the axles 106 and 109 together.In the arrangement of FIG . 3 trips at low speed in first gear is obtained by closing the clutch 118, travel second forward gear is obtained by closing the clutch 117 talons 118 and 119 open . Reverse gear is obtained by closing the clutch 119. Finally direct coupling of the shafts 106 and 109 is possible with the clutch 108. The transmission 131 of Fig . 3 can be provided in the unit of Fig . 1 for a PTO variable speed if desired. Again, the various gear ratios and shift points are calculated so that , when two portions are coupled together via a clutch that move synchronously .

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