DE102012006290A1 - hydrotransformer - Google Patents

Abstract

The invention relates to a hydraulic transformer. The invention is based on the objective of the construction of a hydrotransformer with very high efficiency, good start-up behavior and good controllability in particular of the used mainly as an engine and secondary-controlled sub-machine of a hydrotransformer. The desired aim is with a hydraulic transformer with two hydrostatic submachines, wherein at least one sub-machine is a hydrostatic axial piston machine in swash plate construction with a drive shaft on which a flange is rotatably mounted, with a swash plate on which a driven over the drive shaft or Flanscheibe rotor disk is rotatably mounted, and with a plurality of distributed between the flange and the rotor disk and distributed about the axis of the drive shaft displacement units, each comprising a cylinder sleeve and a projecting into the cylinder sleeve piston with a ball head and a protruding into the cylinder sleeve ball joint head. During operation, the pistons more or less dive into the cylinder sleeve. The rod ends are located on the flange disc and the pistons on the rotor disc.

Description

The invention relates to a hydraulic transformer, which consists in principle of a hydraulic motor and a hydraulic pump, which are connected to each other via a drive shaft. With a hydraulic transformer, a low inlet pressure can be converted into a high outlet pressure at low flow rate and a high inlet pressure at low flow rate into a low outlet pressure at high flow rate. The roles of pump and motor can usually also be reversed to recover potential or kinetic energy. Fields of application of hydrotransformers are hydraulic networks designed as constant pressure networks and low-loss operation of hydraulic cylinders on such networks. Hydraulic cylinders can then be operated and be supplied by the working as a pump part machine with pressure medium, even if the load pressure does not match the pressure in the pressure network. Conversely, when lowering a load carried by a hydraulic cylinder, energy can be recovered even if the load pressure does not match the pressure in the pressure network. Throttle controllers or load-sensing controllers can be replaced.

The principle of hydrotransformers is state of the art. In general, hydrotransformers are built on the basis of swashplate engines, because this type inherently better positioning dynamics of the adjustment than, for example, the bent axis design. Hydrotransformers are known from a number of publications. That's how it shows DE 32 02 015 C2 a hydraulic transformer, which consists of two attached axial piston machines in swash plate design. From the DE 196 54 567 A1 Hydraulic transformers in swash plate design are known in which the two part of the machine, the swash plate is common.

At one of the WO 2003/058035 A1 known hydrotransformer, the control of the pressure medium flows via a control disk, which is adjustable relative to the swash plate of an axial piston machine. By adjusting the control disk relative to the swash plate, the relative position of the control kidney with respect to the dead center of the axial piston machine can be changed. This allows the realization of a secondary control with adjustable displacement units, which in contrast to resistance controls throttle losses practically do not occur.

Also known is a hydrotransformer based on the "floating cup design". This type of hydraulic machine is for example in the WO 2004/055369 A1 shown.

The known solutions based on swash plate design have the disadvantage that the engine has a large internal friction in itself at low speeds, or when starting from a standstill due to the inherent shear forces on the working piston. This has the consequence that the controllability is insufficient, especially in the range of low speeds for use in hydrotransformers. Due to this insufficient quality controllability is a low-jerk or jerk-free startup of a consumer with such a hydrotransducer not possible, or only with great additional effort. In addition, occur due to the aforementioned piston lateral forces on large friction losses. As a result, the efficiency of the entire arrangement becomes poor.

Theoretically, a hydrotransformer could also be represented using a hydrodynamic machine of the oblique-axis type, which in principle has a good start-up behavior. However, the oblique-axis design has the disadvantage that for the adjustment of the stroke inherently very large masses must be moved, namely the whole cylinder block. The suitability of this design as a secondary-controlled motor is therefore limited.

In the solution with an engine according to the floating cup design, which is in principle less friction than the swashplate type, the regulation of the transformer function takes place in contrast to the conventional hydrotransformer not by the classic stroke adjustment of the piston engines, but by rotating control mirrors with three kidney ports. The mode of operation corresponds to a hydraulic phase control. A disadvantage is the high noise and pulsation development of this arrangement.

The invention is based on the objective of the construction of a hydraulic transformer with high efficiency, good start-up behavior and slow running good controllability in particular of the used mainly as a motor and secondary-controlled sub-machine of a hydraulic transformer.

The desired aim is with a hydraulic transformer with two hydrostatic submachines, wherein at least one sub-machine is a hydrostatic axial piston machine in swash plate construction with a drive shaft on which a flange is rotatably mounted, with a swash plate on which a driven over the drive shaft or Flanscheibe rotor disk is rotatably mounted, and with a plurality of distributed between the flange and the rotor disk and distributed about the axis of the drive shaft displacers, each having a cylinder sleeve and a projecting into the cylinder sleeve piston with a ball head and into the cylinder sleeve encompassing projecting spherical condyle. The rod ends are located on the flange disc and the pistons on the rotor disc. During operation, the pistons more or less dive into the cylinder sleeves, while the rod ends and the cylinder sleeves are pivoted relative to each other only against each other. The axis of a piston and the passing through the centers of the ball heads of the pistons and the rod ends axis of the associated cylinder sleeve intersect only at small angles, piston and cylinder sleeve are therefore aligned with respect to their axes almost to each other, so that the pistons are formed with a large diameter can.

In the from the WO 2003/058035 A1 or from the DE 10 2007 011 441 A1 known hydrostatic axial piston machines, in which the displacement units also have cylinder sleeves, in each of which a while moving along a cylinder sleeve moving piston and a joint head, the torque is generated on the piston (engine operation considered), which also the hub in the cylinder sleeves To run. This has in particular the disadvantage that the pistons have at their foot compared to the diameter at their head only a small diameter, since the foot space for the more or less obliquely inclined cylinder sleeves must be free. The pistons are weakened. In contrast, the torque is generated at the condyle, while the piston makes the stroke in a hydrostatic axial piston according to the invention.

Because of the spherical ends of the pistons and the rod ends, it is also possible to speak of a hydrostatic axial piston machine with double-ball thruster (DKT) in the case of the axial piston machine used as part of a hydrotransformer.

Advantageous embodiments of a hydrotransformer according to the invention can be found in the dependent claims.

Thus, a preferred embodiment is that the drive shaft of the at least one sub-machine is mounted on both sides of the flange in pivot bearings and that the rotor disk between the flange and the one pivot bearing is arranged and has a central passage for the drive shaft.

The rotor disk preferably has a flat sliding surface with respect to a sliding partner fixed in the direction of rotation of the drive shaft and is centered relative to the sliding partner, this centering of the rotor disk and the sliding partner advantageously being effected by a centering collar on one part and a centering rotation on the other part.

Preferably, the inclination of the sliding partner relative to the axis of the drive shaft is variable, so that the stroke paths of the piston and thus the displacement volume of the axial piston machine is variable. In particular, the sliding partner, in contrast, the rotor disk rotates a fixed in the direction of rotation of the drive shaft swash plate, which then like the rotor disk has a central passage for the drive shaft and whose inclination with respect to the axis of the drive shaft is changeable.

In a particularly advantageous manner, in a hydrotransformer according to the invention with the at least one axial piston machine with a double-ball thruster, the displacer spaces thereof are alternately fluidically connected to two working ports during operation via the flange disk and a distributor plate against which the flange disk rests. After that, therefore, the commutation of the displacement between high pressure and low pressure on the rod ends, the flange and a distributor plate instead, which may also be a housing part. The rod ends therefore have a central bore for the commutation. This central bore may be larger in diameter than in the pistons, since the rod ends need not be as tightly constricted on their foot as the pistons. Thus, large flow cross sections with only small line losses are possible even if these volume flows are not conducted via the rotor disk. The fact that the volume flows do not flow over the rotor disk makes the construction easier, especially when the rotor disk is adjustable in its inclined position.

Appropriately, in a hydraulic transformer according to the invention with the at least one axial piston machine with double-ball thruster whose piston or the rod ends to the displacement spaces open recesses for gap compensation. It is not only that of the two components hollow, through which the commutation takes place, but also the other.

Preferably, in a hydraulic transformer according to the invention with the at least one axial piston machine with double-ball thruster, the inclination of the rotor disk with respect to the axis of the drive shaft is variable. The hydrostatic axial piston machine is thus preferably a machine which can be adjusted in its displacement volume (stroke volume or displacement per revolution). In particular, the inclination of the rotor disc from a position in which the stroke of the piston in the cylinder sleeves is zero, after is pivotable in opposite directions. This is also referred to as a hydromachine which can be pivoted over zero or over a zero position. As a motor, such a machine allows to reverse the direction of rotation of the output shaft only by the adjustment above zero and thus realize a two-quadrant operation and, for example, driving forward and driving backward a vehicle. If the hydraulic machine can then also be operated as a pump, then one has a four-quadrant operation with the possibility of positive and negative torques and rotation in opposite directions.

According to a particularly preferred development, a hydrotransformer according to the invention has two sub-machines, both of which are designed as hydrostatic axial piston machines with a double-ball thruster.

The start-up behavior of the hydrotransformer is very good due to the double-ball thruster used (no piston lateral forces, direct pressure torque conversion). Thus, the arrangement is very well suited for the sensitive start of a consumer. Due to the principle of the positive displacement principle, high efficiencies can be achieved over the entire operating range. The adjustment of the stroke volume of the secondary-controlled engine of the hydraulic transformer is done classically by means of a swivel cradle as in the swash plate design and thus ensures good controllability of the connected consumer. The noise and pulsation development lies in the area of classic piston engines, for example a swashplate engine.

In the drawings, a hydraulic system with a hydraulic transformer and an axial piston machine according to the invention used as part of the hydrotransformer machine are shown with a double-ball engine as a circuit diagram. With reference to the drawings, the invention will now be explained in more detail.

Show it

1 a longitudinal section through the axial piston machine and

2 the circuit diagram with hydrotransformer.

The axial piston machine shown is constructed on the basis of an axial piston machine in swash plate design and intended for use as a hydraulic motor, but also as a hydraulic pump.

The displacement chambers of the axial piston engine shown are each made of a cylinder sleeve 31 , a condyle 32 and a piston 33 educated. Rod end and piston are each formed at the ends which form the boundary of the displacement, spherical. As a result, in addition to the sealing function, the kinematically necessary joint function is simultaneously imaged. In addition, this arrangement has the advantage that the joint function is carried out both on the side of the joint head, as well as on the side of the piston in principle (ball in tube) with a hydrostatic discharge of 100 percent. Thus, the highly loaded joints of the hydraulic machine are designed due to the principle friction.

In addition, this arrangement has the advantage that all elements are inherently positively connected to each other. As a result, it is entirely possible to dispense with a non-positive connection of the joint head with the cylinder sleeve, or the cylinder sleeve with the piston (for example by means of springs). The positive displacement principle is characterized by friction due to the principle. Due to the positive connection of the displacer is in principle the suitability for high speeds.

The condyle and piston have recesses that allow for gap compensation between the balls and the pressure-expanding cylinder sleeve. The recess is designed so that the remaining gap between the cylinder sleeve and condyle, or cylinder sleeve and piston under pressure targeted constant, or under pressure becomes smaller, or under pressure becomes larger under pressure by the ball expands depending on the pressure. This makes it possible to specifically influence the leakage through this column.

The rod ends 32 are at the flange disc 34 attached and convert the hydraulic forces from the displacement in a torque on the drive shaft 35 , With their axes, the rod ends are parallel to the axis of the drive shaft. The centers of the ball heads of the rod ends 32 So all are in the same plane perpendicular to the axis of the drive shaft. Using two retaining rings 44 are the rod ends 32 and the cylinder sleeves held together so that between them only a pivoting movement takes place. The pistons 33 are on the rotor disk 36 attached and perform relative to the cylinder sleeves 31 a lifting movement. The axes of the pistons 33 extend in accordance with the variable inclination of the rotor disk obliquely to the axis of the drive shaft.

The rotor disk becomes synchronous with the speed of the flange disk 34 through a driving bolt 37 , which is inserted in a bore of the drive shaft and engages in slots on a collar of the rotor disc, taken along, wherein during rotation, a pivoting movement between the drive shaft and the rotor disk takes place. The entrainment can be done for example via gimbal joint, a constant velocity joint, or the like. The rotor disk is on the swivel cradle (swash plate) 38 for example, rotatably supported by means of a hydrostatic bearing or by means of a rolling bearing. The centering of the rotor disk on the swashplate takes place via a centering collar 54 on the swashplate and a centering turn 55 on the rotor disk.

The shoot shaft 35 is on both sides of the flange disc 34 using tapered roller bearings 56 and 57 in the ground 58 a housing pot 59 and in a housing cover 51 rotatably mounted. The rotor disk 36 and the swash plate 38 are between the flange disc 34 and the tapered roller bearing 56 , ie between the flange disc 34 and the floor 58 of the housing pot 59 arranged and each have a central passage 48 . 49 to the passage of the drive shaft 35 , The drive shaft protrudes through the ground 58 to the outside and has a stub shaft outside to be coupled with a driving or driven machine part.

The stroke adjustment of the piston takes place, as in a classic swashplate construction, by means of an adjustment system, which is designed as a sleeve, first adjusting piston 40 with a large effective area, which is controlled by a valve not shown in detail, and an adjusting piston 41 small active surface, which is constantly acted upon by the high pressure at a working port. The adjusting pistons are single-acting pistons and work, opposite to each other with respect to the pivot axis of the swash plate. With the adjusting piston 41 acts in the same direction a return spring 42 by which a rest position of the swash plate is specified.

The slant may be from a zero position in which it occupies a position in which the pistons 33 do not perform a stroke, to be pivoted in opposite directions. One speaks also of an adjustment over zero or from a Durchschwenken. Thus, the hydrostatic machine is suitable for use as an open-loop variable speed motor and for secondary control, ie for regulating the speed or the torque of the machine regardless of the currently occurring high pressure, not only changed the direction of rotation, but also switched from the engine operation in pump mode can be. Secondary control is opposed to the primary control, in which the flow rate of the pump, so the primary unit is specified. In a secondary control, the pump is usually pressure controlled, but the pressure setting may be variable.

The commutation takes place via a high-pressure channel and a low-pressure channel, which is not shown in more detail on the housing cover 51 located connection points to a distributor plate 52 Lead between the flange disc 34 and the housing cover 51 is arranged rotationally fixed with respect to the housing cover. Between the flange disc 34 and the distributor plate 52 There is a sliding pair. In the distributor plate two arcuate recesses, not shown, are formed, each of which is one of the channels in the housing cover 51 is open and with those during rotation of the flange 34 individual channels 53 in the flange, which by a condyle 32 through each lead to a displacement, get into coverage.

The arrangement according to the embodiment allows a continuous drive shaft 35 and thus a drive through and the arrangement of several machines in a row. Such a drive-through is also possible if, in a variant of the axial piston machine shown, the flange disk 34 near the ground and the rotor disk and the swash plate are close to the lid or when the stub shaft is on the cover side.

The commutation of the displacer is carried out as in conventional hydrostatic axial piston machine in swash plate construction by a distributor plate 52 , as well as the flange disc 34 , As a result, an adjustment is possible regardless of the requirements of the commutation and the hydrostatic bearing of the flange. There are large swivel angle and a swing through feasible.

The advantages of a hydrostatic axial piston machine according to the invention, in particular the hydrostatic axial piston machine described as an exemplary embodiment, are to be considered as follows:
Direct, lateral force-free conversion of the hydraulic force of the displacer into torque;
significantly better start-up behavior as a hydraulic motor in comparison with swashplate constructions, better start-up behavior than bent-axis constructions; significantly extended conversion range (practically usable swivel range) compared to bent-axis constructions;
Consumption reduction of hydraulic machines;
Machine can swing (in addition to the above properties), thereby suitability as a hydraulic motor in the open circuit (secondary control);
Cost reduction, since open circuit requires fewer components than closed loop;
In principle, the machine can be driven through (multiple arrangement as with swashplate constructions possible).

To the hydraulic system according to 2 includes a double-acting hydraulic cylinder 60 , in this case a synchronous cylinder, with which a load m is movable. The pressure medium paths between a hydraulic unit 61 a tank 62 and the two cylinder chambers 63 and 64 are with a 4/3-way valve 65 controllable, which has a pressure connection, a tank connection and two consumer connections. In a spring-centered middle position of the directional control valve 65 the two consumer connections are shut off. The pressure connection is connected to the tank connection. The directional control valve can be brought into a working position by driving a Doppelhubelektromagneten in which a cylinder chamber is connected to the pressure port and the other cylinder chamber to the tank port.

The hydro unit 61 is a unit with a constant displacement, which can be operated in both directions both as a hydraulic pump and as a hydraulic motor. It has two working ports, one of which is connected to the pressure port of the directional control valve 65 and the other with one through a wire 66 symbolized hydraulic network with impressed pressure (constant pressure network 66 ) connected is.

The hydro unit 61 forms with a second hydraulic unit 70 a hydrotransformer that allows the hydraulic cylinder 60 to operate on the constant pressure network without throttling losses and also to feed energy back into the pressure network. The hydro unit 70 is adjustable in its displacement above zero and with a first working port with the tank 62 and with the second working connection with the line 66 , so connected to the constant pressure network. The hydro unit can be operated both as a hydraulic pump and as a hydraulic motor, although different than in the hydraulic unit 61 always at the same working port opposite the other working port the higher pressure is present. Constant pressure network does not mean that the pressure in the line 66 kept at a certain pressure. The pressure can change quite a bit. It rather means that in the line 66 a pressure is applied and the hydrotransformer is controlled so that the hydraulic cylinder 60 the desired movement is obtained. In order to avoid rapid pressure changes and to store energy, a hydraulic accumulator is usually connected to the constant pressure network.

With the help of a 2/2-way valve 75 can the two hydrounits 61 and 70 be separated from the constant pressure network.

The engines of the two hydro units 61 and 70 are about a wave 71 mechanically connected, so both have always the same speed. This speed is provided by a speed sensor 73 recorded and sent to a control device 74 given that contains both hydraulic and electrical components and of which the hydraulic unit 70 is adjusted so that a desired speed is present. This is because the hydro unit 71 has a constant displacement, a measure of the over the hydraulic unit 61 the hydraulic cylinder 60 inflowing or for the over the hydro unit 61 from the hydraulic cylinder 60 flowing away pressure medium quantity and thus a measure of the travel speed of the hydraulic cylinder.

There are several cases to distinguish. In a first case, let the hydraulic cylinder under positive load (direction of the force caused by the load is opposite to the direction of movement) be extended at a certain speed, the load pressure being higher than the pressure in the line 66 may be. In this case, the hydro unit 61 as a pump with a speed corresponding to the desired speed of the hydraulic unit operating as a hydraulic motor 70 driven. If the speed drops a bit, this is done by the speed sensor 73 captured and the hydro unit 70 is swung a little further. If the speed is too high, so the hydraulic unit 70 something back. By the hydro unit 61 the pressure is increased from the level prevailing in the constant pressure network to the load pressure.

In a second case, let the hydraulic cylinder be extended at a certain speed under positive load, with the load pressure being lower than the pressure in the line 66 may be. In this case, the hydro unit works 61 as a hydraulic motor and drives the hydro unit 70 at. This is compared to the first case pivoted above zero and promotes the operation as a pump pressure fluid from the tank into the pressure network, the conveyed pressure medium quantity is smaller than that of the hydraulic unit 61 swallowed pressure medium quantity. The hydro unit 61 drives the hydro unit 70 with a given by the difference between the network pressure and the load pressure and by the constant displacement volume torque. Because the pressure difference across the hydro unit 70 greater than the pressure difference across the hydraulic unit 61 must the stroke volume of the hydraulic unit 70 be set so that it is smaller than the constant stroke volume of the hydraulic unit 61 ,

In a third case, let the hydraulic cylinder under negative load (direction of the force caused by the load is the direction of movement rectified) be retracted at a certain speed, the load pressure being higher than the pressure in the line 66 may be. In this case the hydro unit works 61 also as a hydraulic motor and drives the hydro unit 70 at. The direction of rotation of the hydraulic unit 61 and thus the wave 71 the direction of rotation in the first and in the second case is opposite. The hydro unit 70 is pivoted in the same direction as in the first case and promotes in operation as a pump pressure fluid from the tank into the pressure network. Energy is being recovered.

In a fourth case, the hydraulic cylinder may be retracted at a certain speed under negative load, the load pressure being lower than the pressure in the line 66 may be. In this case, the hydro unit works 61 as a hydraulic pump and is powered by the engine operated hydro unit 70 driven. The direction of rotation of the hydraulic unit 61 and thus the wave 71 the direction of rotation in the first and in the second case is opposite. The hydro unit 70 is pivoted relative to the first case from the zero position in the opposite direction. Energy is recovered again, because more hydraulic fluid from the hydraulic cylinder in the line 66 flows as this through the hydraulic unit 70 is removed.

According to the invention, the two hydrounits 61 and 70 out 2 as axial piston machines with double ball engines accordingly 1 educated. The out of the housing of the machine according to 1 outstanding stub shaft of the drive shaft 35 serves the coupling of the two units 61 and 70 together. But for coupling it is preferably corrugated and not with the 1 provided obvious feather. In the second unit, the in 1 apparent stub shaft missing. Their housing cover 51 has a central opening into which projects the drive shaft of the second unit with a corrugation. The two drive shafts can then be rotatably connected to one another with an attached coupling bushing.

Of course, there is an advantage even if only one of the two units 61 and 70 an axial piston machine with a double-ball thruster is.

The two hydrounits 61 and 70 can also be integrated with each other, wherein, for example, in a so-called back-to-back arrangement, a common housing consists of two housing pots and a common middle part.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 3202015 C2 [0002]
• DE 19654567 A1 [0002]
• WO 2003/058035 A1 [0003, 0010]
• WO 2004/055369 A1 [0004]
• DE 102007011441 A1 [0010]

Claims (10)

Hydrotransformer with two hydrostatic submachines ( 61 . 70 ), wherein at least one sub-machine is a hydrostatic axial piston machine with a housing ( 59 . 51 ), with a drive shaft ( 35 ), on which a flange disc ( 34 ) is arranged rotationally fixed, with a swash plate ( 38 ), on the one above the drive shaft ( 35 ) or the flange ( 34 ) entrained rotor disk ( 36 ) is rotatably mounted, and with several between the flange ( 34 ) and the rotor disk ( 36 ) and about the axis of the drive shaft ( 35 ) arranged displacer units, each having a cylinder sleeve ( 31 ) and one in the cylinder sleeve ( 31 ) projecting piston ( 33 ) with a ball head and into the cylinder sleeve ( 31 ) projecting spherical condyle ( 32 ), during operation the pistons ( 33 ) perform a stroke relative to the cylinder sleeves and wherein the rod ends ( 32 ) on the flange disc ( 34 ) and the pistons ( 33 ) on the rotor disk ( 36 ) are located. Hydraulic transformer according to claim 1, characterized in that the drive shaft ( 35 ) of the at least one hydrostatic axial piston machine on both sides of the flange disc ( 34 ) in pivot bearings ( 56 . 57 ) is mounted and that the rotor disc ( 36 ) between the flange disc ( 34 ) and the one pivot bearing ( 56 ) and a central passage ( 48 . 49 ) for the drive shaft ( 35 ) having. Hydraulic transformer according to claim 1 or 2, characterized in that the rotor disk ( 36 ) of the at least one hydrostatic axial piston machine a flat sliding surface relative to a in the direction of rotation of the drive shaft ( 35 ) fixed sliding partner ( 38 ) and with respect to the sliding partner ( 38 ) by centering means ( 54 . 55 ) is centered. Hydraulic transformer according to claim 3, characterized in that the centering of the rotor disc ( 36 ) and the sliding partner ( 38 ) by a centering collar ( 54 ) on one part ( 38 ) and a Zentriereindrehung ( 55 ) on the other part ( 36 ) he follows. Hydrotransformer according to any one of the preceding claims, characterized in that in the at least one hydrostatic axial piston machine ( 61 . 70 ) the displacement chambers via the flange ( 34 ) and a distributor plate ( 52 ), on which the flange disc ( 34 ), in operation are alternately fluidly connected to two working ports. Hydrotransformer according to any one of the preceding claims, characterized in that in the at least one hydrostatic axial piston machine ( 61 . 70 ) the pistons ( 33 ) and the rod ends ( 32 ) to the displacement spaces open recesses for gap compensation between them and the cylinder sleeves ( 31 ) to have. Hydrotransformer according to any one of the preceding claims, characterized in that in the at least one hydrostatic axial piston machine ( 70 ) the inclination of the rotor disc ( 36 ) with respect to the axis of the drive shaft ( 35 ) is changeable. Hydraulic transformer according to claim 7, characterized in that the rotor disk ( 36 ) with respect to one in the direction of rotation of the drive shaft ( 35 ) fixed swash plate ( 38 ) which turns a central passage ( 49 ) for the drive shaft ( 35 ) and whose inclination relative to the axis of the drive shaft ( 35 ) is changeable. Hydraulic transformer according to claim 7 or 8, characterized in that in the at least one hydrostatic axial piston machine ( 70 ) the inclination of the rotor disc ( 36 ) from a position in which the stroke of the pistons ( 33 ) in the cylinder sleeves ( 31 ) is null, changeable in opposite directions. Hydrotransformer according to any preceding claim, characterized in that both sub-machines are hydrostatic axial piston machines with a drive shaft ( 35 ), on which a flange disc ( 34 ) is arranged rotationally fixed, with a swash plate ( 38 ), on the one above the drive shaft ( 35 ) or the flange ( 34 ) entrained rotor disk ( 36 ) is rotatably mounted, and with several between the flange ( 34 ) and the rotor disk ( 36 ) and about the axis of the drive shaft ( 35 ) arranged displacer units, each having a cylinder sleeve ( 31 ) and one in the cylinder sleeve ( 31 ) projecting piston ( 33 ) with a ball head and into the cylinder sleeve ( 31 ) projecting spherical condyle ( 32 ), during operation the pistons ( 33 ) a stroke relative to the cylinder sleeves ( 31 ), whereby the rod ends ( 32 ) on the flange disc ( 34 ) and the pistons ( 33 ) on the rotor disk ( 36 ) and wherein in one of the hydrostatic axial piston machine, the inclination of the rotor disc ( 36 ) from a position in which the stroke of the pistons ( 33 ) in the cylinder sleeves ( 31 ) is null, changeable in opposite directions.

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