DE1188406B - Infinitely adjustable hydrostatic axial piston transmission - Google Patents

Description

Infinitely adjustable hydrostatic axial piston transmission gear The invention relates to a continuously adjustable hydrostatic axial piston transmission transmission with one drive and one output shaft each and with at least three individual hydrostatic axial piston units, in particular but not exclusively on motor vehicles with high-speed engines.

For motor vehicles of the type mentioned, in particular for those with an engine power of about 80 to 100 hp, gearboxes are required whose maximum gear ratios at maximum engine speeds of about 5000 rpm are approximately between 1: 3.2 and 1: 3.8 lie.

With regard to the space-limited installation conditions and with regard to to the necessary high speeds it is necessary that the units of the Both the hydraulic pump and the hydraulic motor are relatively small Have dimensions so that the maximum permissible sliding speed on the Control mirror sealing surfaces and also the permissible limits of the piston centrifugal force and the centrifugal moments exerted thereby are not exceeded.

Since the pressure of the working fluid for reasons of noise and the compression loss can not be increased arbitrarily, offers itself on this Ways, i.e. by further increasing the pressure of the transmission fluid, no possibility to achieve smaller installation dimensions.

It has therefore already been planned to design the pump and motor as double units in order to reduce the diameter of the pump drum and the motor drum. The units here were provided allerdinas with pivoting drums to reach erun- Durchmesserverrin-to C a because of the relation to a swash plate means possible larger pivoting angles that.

In another known two individual gear motors are provided, disposed completely from each other separated and C are connected in parallel to a single pump. Both motors work together on a common output shaft. However, the design here is such that the pump unit is driven by an electric motor which, conversely, can also be driven as a generator. From here, the motor units working in parallel should serve to start up a larger internal combustion engine. Once this burning of-smotor itself rotates and can output power, is intended to 2 are then driven as a generator in the reverse direction of the serving previously as a starter electric motor, in which case the hydrostatic motors now behind the other in series, so no longer in parallel operation, as the pump and the pump now work as a motor. In this known transmission, a large torque with a low drive power needs to be transmitted only briefly in order to start the internal combustion engine. Here, however, there is no problem of small structural dimensions, which cannot be solved at all with the known system, if only because no common distributor piece is provided or even possible for the hydrostatic units.

In another known transmission, three individual hydrostatic axial piston units are combined to form a differential. The purpose of this known transmission, however, is to drive two or more shafts separately from one another at a variable speed from a vehicle engine transversely to the transmission drive shaft and thereby save the gear wheel differential that is common in motor vehicles. It may appear possible that with very low powers and very low speeds, as was the case in the early days of motor vehicle construction, correspondingly large cylinder drums of hydrostatic motors could still be arranged directly on the wheel shafts. In modern motor vehicle drives with large powers and speeds to be transmitted, it would be necessary, in addition to the differential, to provide further gear ratios between the drive shafts of the hydrostatic motors and the wheel drive shafts, which would again illusory the gain hoped for by the known transmission. It is also noted in connection with this known transmission that the pistons of the hydrostatic units work via connecting rods on inclined drive pulleys, which have to transmit the full torque exerted by the hydrostatic unit to the drive shaft via a cardan joint. Such universal joints, however, are not suitable for working with high operating pressures of the liquid, so that for this reason alone the performance that can only be achieved with higher pressures cannot be transmitted.

Another known transmission with three or more hydrostatic axial piston units is designed so that in each case the same number of pumps and motors work on both one and the other shaft of the transmission. The swash plates of both groups of units are adjustable, but the design of the piston units requires pivot axes on the rotating drive shafts, namely within the swash plate. As a result, as in constructions with cardan joints, the permissible fluid pressure is very limited, so that for this reason alone no high-performance transmission can be obtained. This applies all the more so since the forces of the pistons of each two opposite and mutually working drums not compensate for the proposed there, each common swash plate, but viehnehr sum. The essential features that the cylinder drums of the hydrostatic units rotate with the respective drive shafts of these units and that the individual axial piston units are also connected to a common distributor piece are missing here, so that a compact design cannot be achieved. Since the well-known gearbox is used as a locomotive gearbox, i.e. only as a gearbox for heavy machinery construction, the question of construction costs and the use of space does not matter here either.

There are also known transmissions, two parallel to each other working hydrostatic motors are provided. The pump cylinder drums this one However, gearboxes rotate about axes that are not related to the axes of the motor cylinder drums run parallel. How it turned out in practice and how also mathematically can be proven, result from such a design method proportionately large structural dimensions of the overall transmission.

Other known transmissions consist of only two hydrostatic ones Units, one pump and one motor unit, connected to a common distributor are connected. Here, too, it can be demonstrated mathematically that in relation very large structural dimensions of the transmission for the power to be transmitted are required if the maximum permissible sliding speed on the control plate sealing surfaces should not be exceeded and no subdivision of the hydrostatic units is done in at least three or more units.

On the other hand, gears have also become known in which a subdivision of the hydrostatic pump and motor units into several individual units has been made, but here are also several different spatially from each other separate control plate provided so that a common distributor piece is missing. This design also leads, as can be proven mathematically, to large structural dimensions of the overall transmission.

Despite the numerous known design proposals, it has been so far failed to achieve the desired small installation dimensions for a hydrostatic transmission to achieve without at the same time other significant disadvantages taken into account had to be. For example, if the pivoting drums of known gears are sufficient be made small, so they need for the swivel housing in conjunction with the oil supply lines relatively large swivel spaces, and above all then the Oil routing from the pump in question to the engine is cumbersome and complicated.

The invention is based on the object to provide a continuously variable hydrostatic Axialkolbenübersetzungsgetriebe as high-power transmission having dimensions so small structural waste that it can be installed without difficulty, for example in motor vehicles with high-speed motors.

The object set is achieved according to the invention by the combination of the following individually known features, namely: 1. that a common distributor piece is provided for at least three hydrostatic units, 2. that at least two hydrostatic units are arranged that work on a common shaft, and 3. that the cylinder drums of the hydrostatic units are arranged concentrically to the respective drive shafts of the units and rotate with them in a rotationally fixed manner.

To justify the combinatorial effect of the features 1 to 3 listed above, the following is explained. Feature 1. contains the instruction to provide at least three hydrostatic units, i. H. thus to divide the hydrostatic part of the transmission into at least three or any more hydrostatic units. This division makes it possible to arrange these units in a certain spatial manner with respect to one another. A particularly favorable arrangement is achieved by the instruction of feature 2, according to which at least two hydrostatic units are to be arranged so that they work on a common shaft. If, according to feature 3, the cylinder drums of the hydrostatic units are arranged concentrically to the respective drive shafts of these units and rotatably connected to them, one obtains such a compact design with regard to the juxtaposition according to feature 2 of the individually divided according to feature 1 hydrostatic units so that they can all be connected to a common manifold according to feature 1 . The interaction of these features according to the invention results in an extremely compact design of the transmission.

In addition, there are also significant advantages that are mathematical can be proven, namely once a significant increase in performance, on the other hand, a robust and reliable way of working and also proportionate low manufacturing costs because the manufacturing costs as well as the material costs let them be considerably degraded. From the basic idea of the subdivision of the hydrostatic Units and their arrangement on a common manifold results themselves in this context the possibility that is so very important for practice, the whole Manufacture and assemble gearboxes according to the "modular principle", at the same time a very versatile design in terms of the arrangement of the individual hydrostatic units or structural units in adaptation to the given space conditions is achieved.

In other words, the following should be stated to better illustrate the explained basic idea of the invention: None of the invention is to be seen in the arrangement of a single distributor piece for at least three, in practice mostly for a large number of cylinder drums of the hydrostatic units. On this common distributor piece for liquid operating medium, preferably oil, not only are the control plates of the cylinder drums attached, which rotate concentrically with their drive shafts and are non-rotatably connected to them, but they also contain the necessary lines or other organs that are normally used in hydrostatic transmissions conventional type are arranged spatially separated from the control plate. Another feature can be seen in the fact that in connection with this, in particular, several cylinder drums arranged axially parallel to one another and connected to the common distributor piece act on a common drive shaft. In the context of the invention, there is also the knowledge that hydrostatic high-performance units and hydrostatic high-performance transmissions in compact construction with low weight can only be created if the individual units are divided into several units and can act together on the respective unit drive shaft. In hydrostatic transmissions, consisting of a pump and motor unit, at least the unit that has to generate the larger torques should consist of several cylinder drums, all of which are arranged with their control plates on a single distributor and act together on a drive shaft.

Due to the per se known division of the engine part is also at non-swiveling aggregate drums not only significantly reduce the size of the Drum diameter, but above all a considerable reduction in space requirements achieved for a unit than a useless space requirement for pivoting the drum is not needed. The proposal according to the invention, the drums arranged in parallel To let drive shafts rotate, with the control mirrors of the units at a common, fixed oil distribution piece are arranged, allows a large number of cheaper Constructions or drum arrangements in which the unit drums in the desired Obtained extent smaller dimensions and at the same time the oil supply in not so far is simplified to the extent that can be achieved. The working fluid is only through standing Components supplied. This makes the performance management particularly simple, and the required precise machining of the sliding surface and control grooves is with the least Effort possible.

The cylinder drums are a further embodiment of the invention at least two motors of the motor part with a common oil supply, which over a double-sided control plate takes place, coaxially to each other on a common Drive shaft angeord-C, net. According to the invention, this common drive shaft can Be the output shaft with which the coaxially arranged motor drums are non-rotatably connected circulate.

This arrangement eliminates the otherwise necessary transmission links between the motor and the output shaft, and by between the two drums provided axial double-sided control plate, the oil supply is structurally further simplified and operationally safer.

As a continuation of the concept of the invention, the pump can also be replaced by two smaller pumps, which, like the motors , can either be arranged on parallel drive shafts with their control mirrors on the common oil feed piece, depending on the particular installation conditions, or those with mutually coaxial piston drums and an oil feed in between via a double-sided Control mirror can be executed.

It is an already known measure that permits also a reduction of the aggregates, hydraulic axial-piston with a - achieving interoperability planetary gear - frequently fig double. The planetary gear transmits part of the power to be transmitted directly mechanically, the other part hydraulically to the output shaft via the continuously adjustable hydrostatic transmission.

The advantage of such an arrangement is that the input torque is transmitted directly mechanically to the output shaft independently of the respective reduction ratio and that only an additional torque has to act on the output shaft from the hydraulic transmission. For the reductions of 1: 3.2 and 1: 3.8 cited as examples, the torque to be transmitted by the hydraulic gear does not need to be 3.2 or 3.8 times as great as with the reduction ratio of 1: 1, but only about 2.2 to 2.8 times as large.

Since this power split for the underlying of the invention Task is particularly useful, are those shown in the drawings Embodiments of the invention provided with upstream planetary gear, although the arrangement proposed according to the invention also without power split is possible and advantageous in certain cases.

Fig. 1 shows an embodiment of the transmission according to the invention with two motors and an eccentric pump in longitudinal section; F i g. 2 shows a plan view of the transmission according to FIG. 1 in section along the input or output shaft in FIG. 1; F i g. 2 a shows a cross section to FIG. 1 according to section line Ha-Ha; F i g. 3 shows a side view of the transmission according to FIG. 1 with the side cover removed for the purpose of demonstrating the adjusting mechanism; F i g. 4 shows a longitudinal section through a transmission according to another exemplary embodiment of the invention, in which two motors that are coaxial with one another and pumps of the same design are provided; F i g. 5 shows a cross section through the transmission according to FIG. 1 with double motors and single pump; F i g. 6 shows a cross section through the transmission according to FIG. 4, along the line AA with twin motors and twin pumps; F i g. 7 shows a cross section through a transmission similar to the transmission according to FIG. 1, but with two single pumps next to each other; F i g. 8 shows a cross section through a transmission similar to the transmission according to FIG. 4, but with two double pumps lying next to one another; F i g. 9 shows a section along the line BB in FIG. 8th; F i g. 10 shows a further exemplary embodiment of the invention, in which two motors which are coaxial with one another and, next to them, a third motor coaxially with a single pump are provided, in a view; F i g. 11 shows a section through the transmission according to FIG. 10 after the line CC; F i g. 12 shows a vertical section through the transmission according to FIG. 10 after the line DD.

In the case of the transmissions shown in the drawings, the drive takes place via the drive shaft 1, the pinion 2 of which meshes with the planetary gears 3 , which in turn mesh with the internally toothed gear 4. The wheel 4 is fastened to the bearing and end cover 6 of the gear housing 7 by means of screws 5. The planetary gears 3 of the first planetary gear are rotatably supported together with the planetary gears 8 of the second planetary gear on the axle journal 9 in the common planetary gear carrier 10 . The planet gears 8 mesh on the inside with the sun gear 11, which is keyed onto the output shaft 12, and mesh on the outside with the internally toothed gear 13 which is rotatably mounted on the output shaft 12. The gear wheel 13 is also provided with external teeth which mesh with the wheel 14 of the pump output shaft 15 . The shaft 15 is rotatably mounted in the bearings 16 and 16 ' in the gear housing 7 or the control disk 17. The cylinder drum 18 of the pump 19 is non-rotatably mounted on the shaft 15. The pistons 20 work against the swash plate 22, which is rotatably mounted on ball bearings in the swivel housing 21. The swivel housing 21 is swivel-mounted on pins 23 in the gear housing 7. The cylinder drum 18 is provided in the usual way with openings 24 on the control side, via which the cylinder spaces 25 are connected to the control grooves 26 and via the bores 27 to the bores 28 . The bores 28 serve as suction and pressure lines between the pump unit 19 and the motor units 29 and 30 and are hydraulically connected to the corresponding cylinder chambers of these motor units in the same way as with the cylinder chambers 25 of the pump. The oil is supplied between the two motors 29 and 30 via a control plate arranged on both sides in such a way that in the case of the one shown in FIG. 1 employment of the two motor swash plates ensures that the motors work in parallel. The adjustment of the pump and motor swash plates takes place hydraulically via a hydraulic servomotor 31, which is also arranged coaxially to the transmission output shaft 12 and which consists of the piston 32 and cylinder 33 . The pegs 34 attached to the cylinder 33 are inserted in aidal slidable links 35, which in turn are connected via the pegs 36, the crank drive 37 with the transverse lever 39 pivoted on the peg 38 of the gear housing 7 and via the pegs 40, the crank drive 41 with the coulisse 42 are kinematically connected to actuation of the pump swash plate, in such a way that to the right takes place at a displacement of the scenes 35 a displacement of the scenes 42 to left and vice versa. In addition, the links 35 and 42 are provided with recesses 43 and 44 into which the pins 45 engage, which are provided on the pivot arms 46 of the swash plate pivot housing 21. This adjustment arrangement ensures a simultaneous adjustment of the pump swash plates and the motor swash plates in a simple manner. The links 35 and 42 are guided in guides 47 and 48 of the gear housing 7 and held by the screwed-on closure 49.

In Fig. 4, the pump 19 is replaced by two smaller pumps 50 and 51 , the piston drums 52 of which are arranged on the continuous pump drive shaft 53 coaxially to one another and to the pump drive shaft 53 and, like the motor drum, are hydraulically connected to the bores 28 via double-sided control plates. Like F i g. 6 shows, this arrangement increases the installation cross-section compared to an arrangement according to FIG. 1, whose installation cross-section F i g. 5 shows reduced in size. Depending on the particular installation conditions, this is of great importance.

Finally, with two single pumps arranged next to one another in one of the FIGS. 1 corresponding transmission or in the case of double pumps in one of FIGS. 4 corresponding gear installation cross-sections, as shown in FIG. 7 and 8 are shown.

For these designs, it is further proposed according to the invention to mount the swash plates lying next to one another in a single continuous swivel housing 54 or 55 . As a result, the installation dimensions are reduced in width, especially when, according to FIGS. 8 and 9, the diameter of the support pins 56 are made larger than the swash plate diameter, which is easily possible given the small size of the double pumps provided next to one another.

Depending on the particular installation conditions in the individual case, each of the various arrangements described can be advantageous. The arrangements according to FIGS. 5 and 7 are wider in their upper part, but shorter in length. The arrangements according to FIGS. 6 and 8 are narrower in their upper part, but longer.

The in the F i g. The embodiment shown in FIGS. 10, 11 and 12 represents a gear arrangement in which the space below the output shaft has been kept free as far as possible.

In Fig. 10 it can be seen that the hydraulic units, of which only the swash plate swivel housing 57 of a motor and the swash plate swivel housing 21 of the pump with their pivot pins 23 can be seen in this view, are all located above the output shaft 12.

F i g. 11 shows the arrangement of the units in detail. The motors 29 and 30 are arranged on a common drive shaft 58 parallel to the output shaft 12. A third motor 59 is arranged coaxially with the pump 19 housed on the driven side.

The cylinder drum 18 of the pump 19 is non-rotatably mounted on the pump shaft 60. The pump shaft 60 is supported in the bearings 61 and 61 ' and is driven by the drive shaft 1 via the simple planetary gear 62 connected upstream in this embodiment and the gear wheel 63 keyed onto the pump shaft 60 . The pump shaft 60 runs in a hollow shaft 64 to which the cylinder drum 65 of the motor 59 is connected in a rotationally fixed manner. Gears 66, 67 are seated on the two motor shafts 58 and 64 and mesh with a gear 68 attached to the output shaft 12. The oil is supplied to the two motors 29 and 30 via the control disc 17, which is provided with a double-sided control plate, and to the motor 59 and the pump 19 via the control disc 17 ', which is also provided with a double-sided control plate. The two control disks 17 and 17 ' can optionally also be combined to form one component.

In Fig. 12 shows the position of the motor 59 and the pump 19 above the drive shaft 12 as well as the power split via the simple planetary gear 62 connected upstream according to the invention. The inner sun gear 69 of the planetary gear is firmly seated on the drive shaft 1. The planet gears 70 and 70 ' on the planet web 71 firmly connected to the output shaft 12 mesh with the inner sun gear 69 and an internally toothed outer sun gear 72. The outer sun gear 72 has an outer ring gear 73, which drives the gear 63 and thus also the pump shaft 60.

Another convenient way of arranging the individual units is, according to the invention, several motors, for example three, and one or more pumps, all of which rotate as individual units around drive shafts arranged parallel to one another, in order to arrange the output shaft in such a way that the individual units with their Seal control mirrors on a common fixed oil supply piece, through which the output shaft is passed if necessary. This arrangement has the advantage of an extremely short construction, especially when all hydraulic units are arranged on the same side of the oil supply piece.

Overall, the application of the invention results in transmission types, due to the small drum diameter together with the simple, space-saving oil guide have installation cross-sections as they are for use in motor vehicles, especially passenger cars, are indispensable if such transmissions because of their special advantages are used in place of the previously common gear shift transmission should be. Due to the numerous suggested combinations in the arrangement of the individual units can be used to determine the course of the diameter of the gearbox housing as well as adapt the axial extension largely to the given requirements.

Claims (2)

Patentanspräche: 1. Infinitely variable hydrostatic axial piston transmission gear with a respective input and output shafts and having at least three individual hydrostatic axial piston, in particular for motor vehicles with high-speed motors, characterized d urch the following combination of itself known features, namely: 1. that a common liquid distributor is provided for at least three hydrostatic units, tr 2. that at least two hydrostatic units are arranged, which work on a common shaft, and 3. that the cylinder drums of the hydrostatic units are arranged concentrically to the respective drive shafts of these units and rotatably with them circumnavigate connected. 2. Transmission according to claim 1, characterized in that the cylinder drums (29, 30) of at least two motors of the motor part with a common oil supply (28), which takes place via a double-sided control plate, arranged coaxially to one another on a common drive shaft (12) and with this are rotatably connected. 3. Transmission according to claims 1 and 2, characterized in that the two coaxially arranged motors (29, 30) are arranged coaxially to the output shaft (IL2) and are non-rotatably connected to the output shaft. 4. Transmission according to claims 1 to 3, characterized in that the pump part (19 to 25) consists of only one pump. 5. Transmission according to claims 1 to 3, characterized in that the pump part consists of several pumps seated on parallel drive shafts and working parallel to one another (F i g. 7 and 8). 6. Transmission according to claims 1 to 3, characterized in that the pump part consists of two parallel working, coaxially to each other on a common drive shaft (53) arranged pumps (50, 51) with a common oil supply (28) , which via a double-sided control plate on the common oil feed piece (17) takes place. 7. Transmission according to claims 1 and 6, characterized in that the pump part consists of several double pumps arranged on parallel drive shafts and working parallel to one another (F i g. 7 and 8). 8. Transmission according to claims 1 and 2, characterized in that on a common oil supply piece (17, 17 ') two motors (29,30) coaxially to each other on a common drive shaft (58) and one consisting of a pump (19) and a motor Aggregate are arranged coaxially to one another with a double-sided control plate on the common oil supply piece (FIG . 11). 9. Transmission according to claims 1, 5 and 7, characterized in that the juxtaposed swash plates are mounted in a continuous common swivel housing (54, 55). 10. Transmission according to claims 1 and 9, characterized in that the support pins (56) are designed to be larger than the swash plate diameter. 11. A transmission according to claims 1 to 10, characterized in that for the adjustment of the motor swash plates and the pump swash plates laterally attached and mutually independent movable links are provided, in the recesses of which the C pins located on the pivot levers of the Schwenkcrehäuse engage, the links kinematically are connected to one another in such a way that they are displaced simultaneously by a common adjusting element, preferably an adjusting cylinder or servomotor ( FIG. 3). 12. Transmission according to claims 1 to 11, characterized in that a hydraulic servomotor consisting of piston and cylinder is provided for the common adjustment. 13. Transmission according to claims 1 to 12, characterized in that the servomotor is provided with a hollow piston and is also arranged coaxially to the output shaft. Considered publications: German Patent Nos. 841 101, 856 849, 820 694; USA. Patent Nos. 1227 055, 1263 180, 2036437, 2173856, 2541292.