EP1299644A1

EP1299644A1 - Hydraulic transformer

Info

Publication number: EP1299644A1
Application number: EP01953814A
Authority: EP
Inventors: Rudolf SCHÄFFER
Original assignee: Bosch Rexroth AG
Current assignee: Bosch Rexroth AG
Priority date: 2000-07-13
Filing date: 2001-06-28
Publication date: 2003-04-09
Anticipated expiration: 2021-06-28
Also published as: US20030113212A1; WO2002006669A1; US6887045B2; JP2004504535A; DE10034238A1; DE50105252D1; EP1299644B1

Abstract

The invention relates to a hydraulic transformer in which a plurality of displacers are guided in a displacer section. The travel of the displacer is determined by a lifting element, the pressure supply and discharge being controlled by a control element comprising at least three control grooves. According to the invention, either the displacer section, the lifting element or the control element can be driven while depending on the component driven the lifting element or the displacer section is positioned in such a way that it is freely adjustable, and the third, remaining component is positioned in such a way that it is fixed to the housing.

Description

description

hydrotransformer

The invention relates to a hydraulic transformer according to the preamble of patent claim 1.

A hydrotransformer is a unit in which an energy flow Q] _ x pi is converted into an energy flow 0_2 x P ₂ by hydraulic coupling of a hydraulic motor and a pump. In this case, only as much hydraulic energy is drawn from an existing pressure supply as is required to drive a consumer connected to the pump. Such hydraulic transformers can be designed as radial piston machines or as axial piston machines.

No. 3,188,963 shows a hydrotransformer designed as a swashplate machine, in which displacers guided in a rotatable cylinder are supported on a fixed swashplate. The angle of attack of the swash plate determines the piston stroke of the displacer. The pressure medium is supplied and removed via a control disc with four control kidneys, one pair of control kidneys each being assigned to the motor or the pump.

No. 3,079,864 discloses a hydrotransformer in a vane-cell construction. In this solution, a large number of displacers displaceable in the radial direction are mounted in a rotor and biased against a cam ring. The pressure medium supply and discharge takes place in a manner similar to the solution described above via a control disk arranged on the end face. From WO 97/31185 AI and the publication "A new old friend - the hydrotransformer", Siegfried Rotthauser, Peter Acht; O + P "Oil hydraulics and pneumatics" 42 (1998) No. 6; S. 374 ff. ^'Is the so-called INNAS hydraulic transformer, in which the transmission ratio, ie the ratio between the supply pressure and the load pressure of the consumer is changeable. For this purpose, the control disc is provided with three control kidneys, the position of which can be changed relative to the dead center positions of the displacers by rotating the control disc with respect to the swash plate of the axial piston machine. By adjusting the control disc, the torque balance above the swash plate is changed. To shut down the hydrotransformer, the control plate must be brought into a neutral position in which the sum of the moments acting on the swash plate is zero. The regulation for the exact setting of the angle of rotation position of the control disk required for a predetermined transmission ratio is comparatively complex.

In contrast, the invention has for its object to provide a hydrotransformer in which the setting of the transmission ratio is possible in a simple manner.

This object is achieved by a hydraulic transformer with the features of claim 1.

According to the invention, the hydrotransformer is provided with a displacement part receiving the displacer, a lifting element acting on the displacer in the stroke direction and a control element controlling the pressure medium supply to a tank connection, a working connection and a supply connection, one of these elements being able to be driven in rotation by means of a drive. Depending on the driven component, the displacer part or the lifting element is mounted in a housing of the hydrotransformer in such a way that it can set itself freely as a result of the reaction forces. The third component in each case, ie the non-driven or freely adjustable component, is fixedly mounted in the housing.

By driving one of the components, the transmission ratio is essentially determined by the speed of the drive, so that the adjustable pressure at the consumer is thus a function of the speed of the driven component and the available supply pressure. When the drive is switched off, the hydraulic transformer according to the invention immediately assumes an equilibrium position that is dependent on the supply pressure and the load pressure and in which no torques are effective due to the free movement of the second component - the hydraulic transformer is automatically retracted without the need for complex control as with the INNAS hydraulic transformer ,

The solution according to the invention allows an extremely simple setting of the transmission ratio as a function of the speed of the drive, the operational safety being significantly increased compared to the conventional solutions due to the automatic assumption of the equilibrium position when the drive is switched off.

By controlling the speed of the drive, the different transmission ratios can be set in an extremely simple manner. With a constant pressure ratio, the flow rate of the hydrotransformer is proportional to the set speed. The basic concept according to the invention can be implemented both in the case of hydraulic transformers in the axial and in the radial construction.

Depending on the requirements, the driven, the fixed and the self-adjusting component can be implemented in the following preferred variants.

In a particularly advantageous exemplary embodiment, the displacer part accommodating the displacer is fixedly mounted in the housing, while the control element can be driven by the drive and the lifting part is rotatably mounted in the housing. Due to the fixed displacement part, the masses to be accelerated are significantly lower compared to the conventional solution, in which the displacers must be accelerated with the associated rotor, so that a more precise and faster setting of the transmission ratio is possible with minimized losses.

In a second variant, the control element is fixed and the displacer part is rotatably mounted in the housing, while the lifting part acting on the displacer is suspended.

In a third alternative, the displacement part is driven while the control element is fixed and the lifting element is rotatably mounted in the housing.

In particularly preferred embodiments, the hydraulic transformer is designed in an axial piston design (swash plate) or as a vane cell machine.

Other advantageous developments of the invention are the subject of the further subclaims. Preferred exemplary embodiments of the invention are explained in more detail below with the aid of schematic drawings. Show it:

Figures 1 and 2 basic sections through a hydraulic transformer according to the invention in axial piston design;

Figure 3 is a development of the hydraulic transformer from Figure 1 to explain the operation and

Figures 4, 5 an embodiment of a hydraulic transformer according to the invention as a vane machine in two different operating states.

1 to 3 show a first exemplary embodiment of a hydraulic transformer 1 according to the invention, which is designed in an axial piston design. FIG. 1 shows a greatly simplified longitudinal section through a hydraulic transformer 1, in which a plurality of cylinder spaces 4 running in the axial direction are formed in a drum 2 along a pitch circle. In the illustrated embodiment, a total of 18 cylinder spaces are formed in the drum 2. A piston-shaped displacer 6 is guided in each cylinder space 4, the piston foot of which is supported directly or via sliding shoes on an inclined surface 8 of a swash plate 10. The cylinder spaces 4 open via control openings 12 in the end face 14 of the drum 2 facing away from the swash plate 10.

The total of 18 control openings 12 are assigned three control kidneys 16, 17, 18 of a control disk 20 which is sealingly mounted on the end face 14. The three control kidneys 16, 17, 18 are provided with a supply Final P, a work port A or a tank port T connected, which are indicated in Figure 2.

According to the invention, either the swash plate 10, the drum 2 or the control mirror 20 is assigned its own drive, by means of which this component can be set in rotation. Depending on the driven component, either the drum 2 or the swash plate 10 are freely adjustable in a housing, not shown, of the hydrotransformer 1, while the respective third component is fixed in the housing.

In the exemplary embodiment shown in FIG. 1, it is assumed that the control mirror 20 can be driven by its own drive 22 with speed control. In this embodiment, the drum 2 is rotatably mounted in the housing - i.e., the term "drum" does not necessarily define a rotatable mounting of this component in the housing. In this exemplary embodiment, the swash plate 10 is rotatably mounted in the housing, the rotational angle position being set as a function of the moments transmitted to the inclined surface 8 via the displacers 6.

This torque is dependent on the pitch circle radius on which the displacers 6 are arranged and on the pressure acting on the supply connection (high pressure) and on the working connection (load pressure). At a constant pressure ratio, the delivery volume is proportional to the speed of the control mirror 20, which can be set via the drive control of the drive 22.

When the drive 22 is switched off, the swash plate takes up

10 automatically enters an equilibrium position in which the sum of the moments acting on them is zero - the hydrotransformer becomes, for example, at a power failure is reduced to zero so that there is no pressure medium supply to the work connection. This is a considerable safety advantage of the hydrotransformer according to the invention.

Since the comparatively heavy drum 2 with the displacers 6 does not rotate in the described embodiment, the moving masses are relatively small compared to conventional solutions with a rotating drum, so that a higher speed level can be set.

The hydrotransformer can be operated with higher dynamics than an INNAS hydotransformer with the same drive torque.

As mentioned in the introduction to the description, the invention is in no way limited to a driven control mirror 20 with a fixed drum 2 and freely adjustable swash plate 10 - in principle, the two other components, ie the swash plate 10 or the drum 2, can also be driven via the drive 22, while the other two components are fixed or rotating in the configuration shown in Table 1 in the housing.

According to Table 1, all combinations can be realized with the exception of the combination in which the control mirror can be freely rotated or the swash plate is fixed in the housing. In doing so, the The term "swash plate" also covers the axial piston designs with a swash plate or inclined axis.

FIG. 3 shows a schematic development of the hydrotransformer 1 shown in FIG. 1, from which the interaction of the individual components can best be seen, the relative arrangements of the individual components being shown during a complete rotation of the control mirror 20 by 360 °. The control curve which defines the stroke movement of the displacers 6 and is defined by the inclined surface 8 adjusts itself automatically due to the disturbed torque balance depending on the rotational angle position of the control disk 20 and the pressures applied to the connections P, A and T. The drum 2 is fixed relative to the control mirror 20 and the swash plate 10.

When the drive 22 is switched off, i.e. when the control mirror 20 is at a standstill, the swash plate 10 with the inclined surface 8 acting as a control curve adjusts itself in such a way that the torque acting on the swash plate 10 is zero. The equilibrium position shown in FIG. 3 is established when the pressure at the supply connection is approximately the same as at the work connection (load pressure). At a negligible load pressure at the working connection A, the swash plate 10 will shift to the left from the illustration according to FIG. 3 until the displacers 6, which are subjected to high pressure via the control kidneys 18, are arranged in the valley of the control curve formed by the inclined surface 8.

When the control disk 20 is driven in the direction of the arrow, the displacement spaces 6 which are operatively connected to the supply connection P are successively acted upon by the supply pressure, so that the oblique Disk 10 is moved to the left due to the compressive force component FJJ acting in the horizontal direction.

In the exemplary embodiment described above, the hydraulic transformer is designed in the form of an axial piston. However, the invention is not limited to axial piston machines but can also be used with other displacement principles, for example with radial piston machines, cycloid gears, vane machines etc.

FIGS. 4 and 5 show greatly simplified sections through a second exemplary embodiment of a hydrotransformer 1, which is designed in the vane cell design. Such a vane unit has a rotatably mounted rotor 28, which is provided on the circumference with radial recesses in which radially displaceable vanes 30 are guided. The end portions of the vanes 30 projecting radially from the rotor 28 are supported on a cam ring 32 which is offset from the rotor 28 by the eccentricity dimension e. As shown in FIGS. 4 and 5, the cam ring 32 surrounds the rotor 28 with the vanes 30. Two adjacent vanes 30 and the mutually facing peripheral walls of the cam ring 32 and the rotor 28 define displacement spaces 34, which on the one hand have a control mirror 36 on the end face and on the other hand are limited by an end plate, not shown. Similar to the exemplary embodiment described above, the control mirror 36 has three control kidneys 16, 17 and 18 which are assigned to the tank connection T, the working connection A and the supply connection P. Via these control kidneys, the aforementioned displacement spaces 34 can thus be connected to the supply connection, the work connection or the tank connection, depending on the relative position of the components. In the exemplary embodiment shown in FIGS. 4 and 5, the rotor 28 with the vanes 30 practically corresponds to the drum 2 with the displacers 6, the cam ring 32 corresponds to the swash plate 10. The control mirror 36 with the control kidneys 16, 17 forming the end at the end , 18 is practically identical in terms of function to the control mirror 20 from FIGS. 1 to 3. With these assignments, the variants according to Table 1 can also be transferred to vane cell units.

In the exemplary embodiment shown in FIGS. 4 and 5, the control mirror 36 with the control kidneys 16, 17, 18 is fixedly mounted in the housing of the hydraulic transformer 1 (not shown), while the rotor 28 with the blades 30 can be driven by a drive with speed control. Alternatively, the "rotor" can also be fixed in the housing. The cam ring 32 is mounted in the housing in such a way that it can align itself in a specific rotational angle position with respect to the rotor 28 depending on the reaction forces. In other words, this free adjustability essentially comprises the adjustment by a wobbling movement of the cam ring 32.

FIG. 4 shows an equilibrium position which arises when the pressure at the supply connection P is approximately equal to the pressure at the consumer connection A. The two control kidneys 17 and 18 are then arranged symmetrically to the axis of symmetry 38 containing the two dead center positions of the wings 30.

If the load pressure at the working connection A is approximately equal to the pressure at the tank connection T, then the in

Figure 5 shown an equilibrium position in which the control kidney connected to the supply port P. 18 is arranged symmetrically to the axis of symmetry 38 defining the dead center positions.

When the rotor 28 is driven by the speed-controlled drive, the torque balance acting on the cam ring is disturbed in the same way as in the exemplary embodiment described at the outset, so that it is rotated in the direction of its new equilibrium position as a function of the pressure ratio at the working port A and at the consumer port P , Due to the rotating movement of the rotor 28, the lifting ring 32 also performs a wobble movement. With a constant transmission ratio between the supply connection P and the working connection A, the flow rate is proportional to the speed of the rotor 28. In accordance with the above-described exemplary embodiment, one could alternatively also drive the cam ring 32 or the control mirror 36, whereby the component which is freely set in the direction of the equilibrium position always either the rotor 28 or the cam ring 32 must be. Otherwise, the function corresponds to that in FIGS

5 shown hydrotransformer that of Figures 1 to 3, so that further explanations can be omitted.

It is essential in the invention that one of the components determining the pressure ratio, i.e. the displacement part (rotor 28, drum 2), the lifting element (lifting ring 32, swash plate 10) or the control element (control mirror 20, 36) can be driven in a speed-controlled manner, while - depending on the driven component - the displacement part or the lifting element is freely adjustable, while the third, remaining component is firmly accommodated in the housing.

Disclosed is a hydrotransformer in which a plurality of displacers are guided in one displacement part is. The stroke of the displacers is determined via a lifting element, the pressure medium supply and discharge being controlled via a control element with at least three control grooves. According to the invention, either the displacement part or the lifting element or the control element can be driven, while - depending on the driven component - the lifting element or the displacement part is freely adjustable, and the third, remaining component is accommodated in a housing-fixed manner.

LIST OF REFERENCE NUMBERS

hydrotransformer

drum

Zy1inderbohrung

displacement

Schrägseheibe

Steuerδffnung

face

kidney control

A control plate

drive

rotor

wing

lifting ring

displacer

A control plate

axis of symmetry

Claims

Expectations

1. A hydrotransformer with a plurality of displacers (6, 30) guided in a displacer part (2, 28) and limiting a volume-displaceable displacer volume, which are supported on a lifting element (10, 32), the pressure medium supply and discharge via a control element ( 20, 36) with at least three control kidneys (16, 17, 18) which can be connected to a work connection (A), a supply connection (P) or a tank connection (T), characterized in that the components Displacement part (2, 28), lifting element (10, 32) and control element (20, 36) can be driven in a rotating manner by means of a drive (22), while the second component, with the exception of the control element (20, 36), can be rotated as a result of the reaction forces and the third component, except for the lifting part (2, 28), is fixedly mounted in a housing of the hydrotransformer (1).

2. Hydrotransformer according to claim 1, wherein the displacement part (2, 28) is fixed and the lifting part (10, 32) is rotatably mounted and the control element (20, 36) is driven.

3. Hydrotransformer according to claim 1, wherein the control element (20, 36) fixed and the displacer (2, 28) is rotatably mounted and the lifting part (10, 32) is driven.

4. Hydrotransformer according to claim 1, wherein the control element (20, 36) is fixed and the lifting element (10, 32) is rotatably mounted and the displacement part (2, 28) is driven.

5. Hydrotransformer according to one of the preceding claims, wherein the drive (22) is assigned a speed control.

6. Hydrotransformer according to one of the preceding claims, wherein it is designed in an axial piston design and the control element is a control mirror (20), the lifting element is a swash plate or swash plate (10) and the displacement part is a drum (2) with displacers (6).

7. Hydrotransformer according to one of the claims 1 to 5, wherein it is designed as a vane unit and the control element is a control mirror (36), the displacement part, a rotor (28) with radially guided vanes (30) and the lifting element is a cam ring (32) ,