WO2011107190A1

WO2011107190A1 - Control device and method for controlling a torque of a drive shaft of a hydrostatic machine

Info

Publication number: WO2011107190A1
Application number: PCT/EP2011/000339
Authority: WO
Inventors: Michael Brand; Karl-Heinz Vogl
Original assignee: Robert Bosch Gmbh
Priority date: 2010-03-05
Filing date: 2011-01-26
Publication date: 2011-09-09
Also published as: CN102782321A; EP2542779B1; CN102782321B; DE102010020004A1; EP2542779A1

Abstract

The invention relates to a method and device for controlling a torque of a drive shaft (4) of a hydrostatic machine (5). The hydrostatic machine (5) has an adjusting device for setting the displacement volume of the hydrostatic machine (5). The method comprises the following steps: A target torque is specified and a set displacement volume of the hydrostatic machine (5) is detected. A volumetric flow rate into or out of the adjusting device is controlled by means of a control valve (19) on the basis of a force difference between a control force and a force acting on the control valve (19) in the opposite direction in order to set the displacement volume. The control force is determined according to the detected displacement volume and the detected target torque. The force acting on the control valve (19) in the opposite direction is a hydraulic force, which is produced by the pressure acting on the high-pressure side of the hydrostatic machine (5).

Description

Control device and method for controlling a torque of a drive shaft of a hydrostatic

machine

The invention relates to a control device and a method for controlling a torque of a drive shaft of a hydrostatic machine.

In a regenerative drive system, a variable in its stroke volume hydrostatic machine is arranged in an open circuit. The hydrostatic machine can be driven in pump mode via a drive shaft

Hydraulic fluid from a tank or a

Promote low-pressure accumulator in a high-pressure accumulator. If energy is required in the regenerative drive system, the hydrostatic machine is operated with pressure medium from the high-pressure accumulator as a motor and the

Drive shaft driven. The delivery or displacement volume of the hydrostatic machine should always be adjusted so that given a pressure of the high-pressure accumulator, a predeterminable braking or acceleration torque is present on the drive shaft of the hydrostatic machine.

In the German patent application DE 10 2006 058 357 AI is a control device for a regenerative

Drive system described. To set the

Torque of the shaft of the hydrostatic machine, the high pressure of the high pressure accumulator is detected by a sensor and given to a control device. The

Control device calculated from a requested

Braking torque and the detected high pressure to be adjusted delivery volume of the pump. The stroke volume of

hydrostatic machine is adjusted by means of a control piston of a control device. The volume flows in and out of the actuator are on a

Control valve set. The control valve is this, so controlled by a control signal that at the hydrostatic machine sets the calculated delivery volume. Such so-called electro-proportional

Controls that take into account the measured system high pressure are generally known.

Such an electroproportional adjustment in

Dependence of a measured high pressure and the

requested braking torque has the disadvantage that expensive high-pressure sensors must be used. Furthermore, it is no longer possible in a failure of the high pressure sensor, the requested braking torque on the

hydrostatic machine. Therefore, expensive and fail-safe high-pressure sensors or at least one redundant high-pressure sensor must be used.

The object of the invention is to eliminate the disadvantages of the prior art. In particular, it is an object of the invention, a control method and a

To find control device for controlling the present at the drive shaft of the hydrostatic machine torque that do not require the operation of a high pressure sensor and / or their functionality even in case of failure

For example, monitoring high-pressure sensor is further ensured.

The object is achieved by the method according to claim 1 and by the inventive

Control device according to claim 11 solved.

The method according to the invention regulates the torque of a drive shaft of a hydrostatic machine. The

Hydrostatic machine has an adjusting device for adjusting the stroke volume of the hydrostatic machine. The method comprises the following steps: First, a setpoint torque is specified and a set stroke volume of the hydrostatic machine is detected. to

Control of the torque of the drive shaft is a

Volume flow in or out of the actuator by means regulated by a control valve. The volume flow is based on a force difference between a

Control force and an opposite to the control force acting on the control valve acting force regulated. The opposite acting, on the control valve

acting force is generated by the pressure applied to the high pressure side of the hydrostatic machine high pressure and counteracts the control force. The size of the control force is set as a function of the detected stroke volume and the predetermined and detected setpoint torque.

The control device according to the invention is

basically for controlling a torque of a

Drive shaft of a hydrostatic machine suitable, wherein the stroke volume of the hydrostatic machine is adjusted by means of a pressure medium-loaded adjusting device. The control device has a control valve for controlling a volume flow in or out of the

Adjusting device, e.g. a control pressure chamber of

Actuator, for adjusting the stroke volume.

Furthermore, the control device has a

A target torque setting device for setting a target torque and a Hubvolumenerfassungsvorrichtung for detecting a set stroke volume of

hydrostatic machine on. The volume flow through the control valve is adjustable with respect to the direction and preferably also the height on the basis of a force difference between a control force and a force acting in the opposite direction to the control valve force. A control surface of one side of the control valve is for

Generation of the counteracting force connected to the high pressure side of the hydrostatic machine. The control device further has a control device which is suitable for specifying the magnitude of the control force as a function of the detected stroke volume and the predetermined setpoint torque.

An advantage of the solution according to the invention is that the stroke volume of the hydrostatic machine automatically to the High pressure, which drives the hydrostatic machine or against which promotes the hydrostatic machine, is adjusted so that the target torque of the drive shaft of the hydrostatic machine remains virtually unchanged.

By taking into account the setpoint torque and the set stroke volume in determining the

Control force will automatically adjust the stroke volume to the

preset setpoint torque is set by feedback of the currently set stroke volume of the hydrostatic machine. The pressure of the high pressure side goes through the direct admission of the control valve in the

Control, without having to measure the high pressure by vulnerable sensors. In addition, the target torque is given and the set stroke volume as a control variable easy to capture. In addition, such a control has the advantage that e.g. existing, pressure-controlled pumps by the control of the invention for torque control can be used. The dependent claims relate to advantageous

Further developments of the invention.

It is particularly advantageous that the control force

at least partially a hydraulic force. To assist the control force, e.g. a spring force acting in the same direction with the control force on the control valve to simultaneously ensure a defined rest position of the control valve. The control force then consists of an adjustable component and a fixed

predetermined component, which is generated by the spring. In particular, it is advantageous that the

hydraulic force as adjustable component of

Control force is generated by the setting of an opening pressure of a pressure relief valve.

In a preferred embodiment, the

Control force depending on the ratio

predetermined target torque generated to the detected displacement. By such a ratio of given Target torque and the detected stroke volume a negative feedback of desired torque to displacement is achieved. Thereby, when the desired torque is changed, and thus when the control force is changed, it is achieved that the control force is adjusted in the opposite direction as a result of the resulting change in the stroke volume and the feedback of this stroke volume.

It is beneficial to have the control force in a first

Operating mode and a second operating mode in each case to regulate differently. The first mode of operation could be, for example, the pump mode and the second mode of operation could be the motor mode of the hydrostatic machine.

This allows the regulation to different

Requirements of the regulation for the first and second operating modes.

Thus, it is particularly advantageous to predetermine an adjustable component of the control force, for example the hydraulic component of the control force, in a first operating mode proportional to the ratio of the predefined setpoint torque to the detected stroke volume.

Accordingly, the control device is suitable for specifying the control force in a first operating mode proportional to the ratio of the preset setpoint torque to the detected displacement. So will at one

Enlargement of the specified torque in

Pumping operation and the associated increase in the stroke volume, the control force reduced by the negative feedback of the increasing stroke volume again. Due to the indirect proportionality of the control force to the detected stroke volume is a negative feedback of the

Control force achieved with the set stroke volume. It is also advantageous that the adjustable

Component of the control force in turn has two shares in a second mode of operation. The first share is indirectly proportional to the absolute amount of the

Ratio of preset target torque to the recorded stroke volume. The second component depends on the difference between the setpoint torque and the actual torque of the drive shaft. Preferably, the second portion is direct

proportional to said difference. The

Control device is suitable, the control force

according to the two shares. By the first portion is achieved for feedforward, that also at

Swinging the hydrostatic machine over the

Zero-stroke volume (defined here as the neutral position of the hydrostatic machine) towards a maximum

Suction volume of the hydrostatic machine in the

Motor operation is already adjusted in the correct direction when changing the setpoint torque. It is also ensured by the first share continues to feedback the currently set stroke volume of the hydrostatic machine. However, since the first share only a qualitative adjustment of the stroke volume of

hydrostatic machine for a given displacement and setpoint torque in engine operation, is controlled only by the second, superimposed share on the exact adjusted stroke volume value of the hydrostatic motor.

It is particularly advantageous that the actual torque of the drive shaft of the hydrostatic machine from the displacement and the on the high pressure side of the

hydrostatic machine prevailing high pressure is determined. It is also advantageous to estimate the high pressure based on the control force or the adjustable component of the control force, for example, a hydraulic control pressure of the control force. The control device is suitable for the actual torque and the high pressure

described to determine. The actual torque can be calculated by the set stroke volume and the prevailing high pressure. Instead of the high pressure directly to

measured, this is estimated with the control pressure, which counteracts the high pressure on the control valve. The control pressure is directly proportional to that

High pressure, as the control signal always following the high pressure is regulated. In order to cope with the short-term difference between the actual torque and the Sol1 torque that arises when the setpoint torque changes, the high pressure is estimated with a filtered control pressure. The control device is suitable, the

High pressure due to a filtered control pressure

estimate. By such a calculation of the control force, it is not necessary to measure the high pressure. It is also advantageous to additionally detect the high pressure by a simple pressure sensor and to monitor the control signal for specifying the control force on the basis of the detected high pressure. The control device is suitable for monitoring the control force or the control pressure of the hydraulic part of the control force on the basis of a high pressure measured with a pressure sensor.

It is also advantageous that in the first

Operating mode and in the second operating mode the

Attack direction of the control force and the opposing force on the control valve is reversed. By dispensing with the spring acting on the control pressure, this may e.g. be achieved by a shuttle valve. By such a reversal of the control direction in the second operating mode, i. The engine operation of the hydrostatic machine can be the same in both operating modes

Control system can be used for the control signal. In such an embodiment, the control signal and thus the predetermined control force is always direct

proportional to the torque to be adjusted and

indirectly proportional to the detected stroke volume or to their respective absolute amounts.

In a preferred embodiment, the control valve has a first connection connected to a high-pressure side of the hydrostatic machine, a second connection connected to a low-pressure accumulator or tank, and a third having a control pressure chamber

Actuator connected connection. The Control valve is preferably continuously between a first, the first port connecting to the third port position and a second, the second

Sliding connection with the third connection connecting position. Such a control valve allows a

simple control of the volume flow in and out of the actuator on the basis of a force difference.

It is also advantageous that for the production

at least one component of the control force a

Control surface of the control valve is connected to a control pressure line and this component of the control force on the control pressure by the control device is adjustable. In particular, it is advantageous that the

Control pressure line for adjusting the control pressure is connected to a pressure relief valve whose

Opening pressure is adjustable by the control device. It is particularly easy and failsafe that

Control force at least partially, for example, in addition to the additional component of a spring force through which

Setting a control pressure at one end of the

Adjust control valve. It is still here

advantageous that the control pressure line is connected via a throttle directly to the high pressure side of the hydrostatic machine.

It is also advantageous that the

A control valve having a first and a second control surface and a shuttle valve, wherein in a first position of the shuttle valve, the first control surface of the control valve with the high pressure side of the hydrostatic machine and the second,

opposite acting control surface of the control valve is connected to the control pressure line. In a second position of the shuttle valve, the second control surface of the control valve is connected to the high pressure side of

hydrostatic machine and the first control surface of the control valve connected to the control pressure line. With such a shuttle valve, the flow direction the control with identical force difference between high pressure-dependent force and control force to be reversed. The control device is suitable for

Change in the first operating mode in the first position and in the second operating mode to bring the shuttle valve in the second position. This has the advantage that the

Control algorithm can be maintained for the control force in the second operating mode as well as in the first operating mode. As described above in connection with the first mode of operation, is the predefined

Control force proportional to the quotient of setpoint torque and adjusted stroke volume.

The control device according to the invention is particularly advantageous for regenerative drive systems that the

High pressure side of the hydrostatic machine with a

Connect high-pressure accumulator and in which a

durchschwenkbare hydrostatic machine is used.

The control device is also for

Power controller, which adapt the torque of the drive shaft of a hydrostatic machine to the load pressure, advantageous.

In the following an embodiment of the invention will be described with reference to the drawing. The drawing shows:

Fig. 1 is a schematic representation

hydraulic circuit diagram of a

Embodiment of a regenerative

Brake system with the control device according to the invention;

Fig. 2 is a simplified sectional view of the

adjustable hydrostatic machine according to the first embodiment;

Fig. 3 is a block diagram of the control device of

Embodiment; Fig. 4 is a diagram for explaining the generation of a control pressure generation signal;

Fig. 5A is a time chart of the target and actual torque of the drive shaft of the hydrostatic machine, which is controlled by the control method according to the invention;

FIG. 5B shows an associated time profile of the high pressure and the control pressure of a control valve; FIG.

Fig. 5C also a corresponding time course of the

Swivel angle of the hydrostatic machine; and FIG. 6 shows a process flow diagram of the method according to the invention for controlling the torque of the shaft of the hydrostatic machine.

Fig. 1 shows a regenerative drive system 1 according to a first embodiment. The regenerative

Drive system 1 has an axial piston machine 5, a high-pressure accumulator 3 and an inventive

Control device for controlling a torque of a drive shaft 4 of an axial piston machine 5.

The axial piston machine 5 is in an open circuit on a low pressure side via a first working line 6 with a tank volume 7 or alternatively with a

Low pressure accumulator connected. The axial piston machine 5 is connectable to the high-pressure accumulator 3 on the high-pressure side via a second working line 8. This arrangement ensures that the second

Working line 8 Always high-pressure in operation and the first working line 6 Always low-pressure in operation.

An exemplary constructive realization of a

Axial piston machine unit 2 shown in Fig. 2. The

Axial piston machine unit 2 has the adjustable Axial piston machine 5 as one in its stroke volume

adjustable hydrostatic machine and one

Adjusting device for adjusting the pivot angle of the axial piston machine 5. The adjusting device has in the first embodiment, two adjusting pistons 9 and 10, each in an actuating cylinder 11 and 12 in

Are guided longitudinally movable.

Fig. 2 shows in the illustrated step, only the second actuating piston 10 and the second actuating cylinder 12. The two adjusting pistons 9 and 10 are connected to the in the

Housing of the hydrostatic machine 5 rotatably mounted swash plate 13 of the axial piston machine 5 coupled. The position of the adjusting pistons 9 and 10 determines the pivot angle of the swash plate 13 and thus the set

Displacement. The axial piston machine 5 is of hers

Neutral position (stroke volume = 0) starting infinitely adjustable in the positive and negative directions, so that the axial piston machine 5 can be used both in positive pivoting angles in pumping operation as well as negative pivoting angles in engine operation. In the exemplary embodiment, the swash plate 13 is adjustable from a minimum swivel angle of -18 ° to an absolute maximum same swivel angle of + 18 ° seen. The

Axial piston machine 5 has no stable zero position and is held by the spring force of a spring 17 in a pressureless state at maximum positive pivoting angle.

The first actuating piston 9 and the first actuating cylinder 11 form a first actuating pressure chamber 14 and the second

Control piston 10 and the second actuating cylinder 12 form a second actuating pressure chamber 15. Alternatively, an adjusting device with only one actuating piston, which limits two actuating pressure chambers in one actuating cylinder, could be used. Furthermore, the actuator could so

be formed such that the axial piston machine 5 is in the zero-stroke position or other rest position in the pressureless state. The first and second control pressure chambers 14 and 15 of the first embodiment are each acted upon by a first and second control pressure line 23, 16 with a pressure. The second adjusting pressure chamber 15 is permanently connected via the second actuating pressure line 16 to the second working line 8. Therefore, in the second actuating pressure chamber 15 during operation of the axial piston machine 5, the pressure of the high pressure side acts. The second actuating piston 10 is acted upon in addition to a hydraulic force caused by the pressure in the second actuating chamber 15 by the rectified force of the spring 17.

As long as the control pressure chambers 14 and 15 are depressurized, the second actuating piston 10 is pushed out in the direction of the second actuating cylinder 12 and thus forces the

Swash plate 13 in a maximum adjustable positive swivel angle. The cross-section of the first actuating cylinder 11 and thus the area of the first actuating piston 9 pressurized in the first actuating pressure chamber 14 is greater than the cross section of the second actuating cylinder 12. The area ratio is selected such that the pressure prevailing in the second operating line 8 during operation

Push up and at the same pressure in the first

Stelldruckkammer 14, the hydraulic force on the first actuating piston 9 in each adjustment position is greater than the hydraulic force plus the spring force on the second actuating piston 10 and the axial piston machine 5 in

Direction of the maximum negative swivel angle pivoted.

The axial piston machine unit 2 is provided with a

Valve block 18 of the control device according to the invention connected. The valve block 18 has a control valve 19 for controlling the volume flow in and out of the first

Setting pressure chamber 14 on. The control valve 19 is a 3/2-way valve. A first connection of the control valve 19 is connected via a first supply line 20 with a

High pressure line 21 is connected, which is connected to the high pressure leading second working line 8. The first connection of the control valve 19 is thus with the high pressure side of the axial piston machine 5 and with the High-pressure accumulator 3 connected. The second connection of the control valve 19 is connected via a tank line 22 with the

Tank volume 7 of the axial piston machine unit 2 connected. The third connection of the control valve 19 is connected via the first control pressure line 23 via a first throttle 24 to the first control pressure chamber 14. The first

Throttle 24 limits the possible volume flow and thus the adjustment speed. A control valve piston of the control valve 19 can be brought into two end positions. The control valve 19 is continuously adjustable from the first end position to a second end position of the control piston. In the first end position, the first port is the third port of the

Control valve 19 connected. In this position, the first actuating pressure chamber 14 is connected to the high-pressure leading first working line 8. In the second position, the second port is the third port

connected. In this position becomes the first

Adjusting pressure chamber 14 connected to the tank 7 and the first adjusting pressure chamber 14 relaxed in the tank volume.

On a first control surface of the control piston of the

Control valve 19 acts on a first hydraulic force and the second control surface of the control piston in

opposite direction, a second hydraulic force as the first adjustable component of the control force. For this purpose, the first control surface is connected via a second supply line 29 to the high-pressure line 21, so that there always the high pressure of the second working line 8 acts. On the second side of the control valve piston of

Control valve 19 acts on the force of a spring 25 adjustable in its bias of the control valve 19 plus the second hydraulic force as adjustable component. The second hydraulic force plus the spring force form the force acting on the second control surface of the control valve piston

Control force. The bias of the spring 25 of the control valve 19 remains constant during operation, so that in operation, the control force only by the change of the second

hydraulic force so set the control pressure becomes. If the first hydraulic force is greater than the control force, then the control valve 19 goes into the first

Position. Is the control force greater than the first

hydraulic force, the control valve 19 goes to the second position. The transmitted volume flow at given pressure conditions at the ports in the first and second position depends on the force difference between the first hydraulic force and the

Tax force.

A third supply line 26 connects to generate the second hydraulic force, the second control surface of the control valve piston of the control valve 19 with a

Control pressure line 27. The control pressure line 27 is connected via a second throttle 28 to the high pressure line 21st

connected and opens at its end remote from it in the tank line 22. The first and the second supply line 20 and 29 are connected upstream of the second throttle 28 with the high-pressure line 21.

In the control pressure line 27 is a

Pressure relief valve 30 is arranged. On a

Control surface of the pressure relief valve 30 acts a dependent of the control pressure as a first component of the control force third hydraulic force. In the opposite direction 30, the force of an adjustable in its bias spring 31 of the pressure relief valve 30 acts in the closing direction. Exceeds at vanishing

Control of the control pressure in the control pressure line 27 by the bias of the spring 31 of the

Pressure relief valve 30 set opening pressure, so opens the pressure relief valve 30. So is the

Control pressure in the control pressure line 27 upstream of the pressure relief valve 30 depending on the set opening pressure of the pressure relief valve 30 is set. This opening pressure is predetermined by the bias of the spring 31 of the pressure relief valve 30 and the opposing force of an electromagnet 32. The opening pressure and thus the set control pressure in the control pressure line 27 can be reduced by increasing the energization of the electromagnet 32.

Furthermore, the first control pressure line 23 between the first throttle 24 and the third port of

Control valve 19 is connected via a connecting line 33 to the tank line 22. The connecting line 33 has a third throttle 34. In the second working line 8, a check valve 35 for separating the high-pressure accumulator 3 from the high-pressure line 21, the second setting pressure chamber 15 and the axial piston machine 5 is arranged to prevent leakage. The

Shut-off valve 35 is for this purpose by energizing or non-energizing another solenoid 36 of the

Lock valve 35 to open or close.

Furthermore, the regenerative drive system 1, a further pressure relief valve 37, a Nachsaugventil 38 and a storage discharge valve 39. The further

Pressure limiting valve 37 opens when exceeding a maximum allowable pressure through the high pressure in the second working line 8 to the tank volume 7 out. About the suction valve 38 is in the case of an empty

High-pressure accumulator 3 in engine operation from the tank 7 nachgesagt. The storage discharge valve 39 empties the high-pressure accumulator 3 as a result of an electrical discharge signal.

The control device further includes

electronic control unit 40 as a control device, which via a first control connection 41 with the

Electromagnet 32 of the pressure limiting valve 30 and a second control connection 42 with the other

Electromagnet 36 of the check valve 35 and a third control connection 43 is connected to the storage discharge valve 39. Furthermore, the control unit 40 via a fourth control connection 44 with a

Target torque setting device 45, for example, connected to an accelerator pedal or a drive lever. The Solldrehmomentvorgabevorrichtung 45 gives that at the

Drive shaft 4 to be set torque as an electrical signal to the control unit 40. The torque to be set on the drive shaft 4 is also referred to below as the desired torque. The controller 40 is connected via a fifth control link 46 to a swing angle detector as a stroke volume detecting device. Of the

Swivel angle detector detects the set

Swivel angle a of the swash plate 13 of

Axial piston machine 5 and outputs this as an electrical signal to the controller 40th

The swivel angle detector is shown in Fig. 2 and designated there by "47." The set swivel angle a is tapped on the second actuating piston 10 in the illustrated embodiment

Control piston 10, a sensor element 48 of the

Pivoting angle detector 47 mounted, which moves with the second actuating piston 10 in the longitudinal direction thereof. In the range of motion of the sensor element 48 is a

Position detecting device 49 fixedly attached to the housing of the axial piston machine unit 2. The

Position detecting device 49 detects contactless the position of the sensor element 48 and thus the position of the second element connected to the sensor element 48

Control piston 10. The position detection device 49 converts the detected position of the second control piston 10 in a set the pivot angle a of

Swashplate indicating signal and sends it over the fifth control connection 46 to the control unit 40. The invention is not on the one described here

Hubvolumenerfassung limited. Rather, every other mechanical, magnetic, electrical or optical

Hubvolumenerfassung the axial piston machine 5 also possible.

3 shows a block diagram of the control 50 of the control device according to the invention. The controller 50 has the swing angle detector 47, the

Target torque setting device 45 and the controller 40 on. The controller 40 includes a

Operating mode detector 51 and first and second control pressure setting sections 52 and 53. The

Operation mode detector 51 determines whether the

Axial piston machine 5 in pumping operation as the first

Operating mode or in motor mode as the second

Operating mode is located. This may be in the first one

Embodiment, for example, be determined from the sign of the swivel angle a or if the

Swivel angle a to zero is the sign of the setpoint torque T to be set. Of the

Operating mode detector 51 is suitable to receive via the input 54 of the control unit 40, the pivot angle a and the input 55, a signal representing the target torque T signal. The operation mode detector 51 is connected to both control pressure command sections 52 and 53 and to a check valve control 62. Of the

Operation mode detector 51 is adapted to the target torque T and the pivot angle a to the first

To give control pressure setting section 52 when the

Axial piston machine 5 is in pumping operation or to give the second control pressure specification section 53 when the axial piston machine 5 is in engine operation.

Further, the operation mode detector 51 is adapted to notify the particular operation mode of the check valve controller 62, i. to drive the electromagnet 36. The first or second control pressure setting section 52 and 53 calculates a control pressure and converts the calculated control pressure into a control pressure signal including the control pressure signal

calculated control pressure by setting the

Opening pressure on the pressure relief valve 30 sets. The control pressure signal is applied to the output 56 of the controller 40 from either the first or the second control pressure setting section 52 or 53 and applied to the solenoid 32 via the first control connection 41. The control pressure signal (or the calculated, underlying control pressure) takes into account the proportion of the spring 25 to the control force. For simplicity, the force of the spring 25 is neglected below and only the adjustable component of the control force, so considered the control pressure.

The first control pressure setting section 52 is at

Determination of the first operating mode by the

Operating mode detector 51 is active and calculates a

Control pressure p, which is directly proportional to the ratio of target torque T to pivot angle a. Of the

Control pressure p of the first control pressure setting section 52 is calculated to be

T

Ρ = Κ -,

a

where K, is a first constant

The second control pressure specification step 53 is active in the second operating mode and described in more detail in FIG. 4. The output control signal is calculated from a first pressure component p _x and a second pressure component p ₂ . The first component p _i is directly proportional to the absolute value of the ratio of the swivel angle a to the desired torque T. Should the moment T of the drive shaft be negative for the motor operation and positive for the pump operation, then the absolute value is also unnecessary, since in motor operation the tilt angle

is also negative. The first component p _x is in a Vorsignalregelung 57 to

calculated, where K _{2 is} a second constant. The second component p ₂ regulates the first component. For this purpose, a difference between the setpoint torque T and the actual torque 7 _{to is determined} in a differential element 58, amplified in an amplifier 59 and added to the first component p _x . The actual torque T _{bl is} calculated in the actual torque estimation 60 from the swivel angle a and the high pressure driving the axial piston machine 5. Since the control pressure p is always regulated so that he High pressure of the high pressure line 21 corresponds approximately or at least immediately follows, the high pressure with the predetermined control pressure p = p _l + p ₂ can be estimated.

Thus, the actual torque T _bt in the actual torque estimation 60 is calculated

^T ht ⁼ ^ 3 ^{a '} Pm ·

Since the control pressure p deviates from the high pressure briefly in the event of a rapid change in the setpoint torque T, the control pressure p in the correction device 61 undergoes filtering or smoothing before processing in the actual torque estimation 60. The

Correction device 61 may further or alternatively include logic used in borderline cases, e.g. when the actuator is at the stop, the control pressure p is correctly evaluated. The first component p of the control pressure p can also be controlled by more complex regulators, e.g. a PI controller, be readjusted.

The control unit 40 also has the

Lock valve control 62, which in the operation of the

Drive system 1 for filling or emptying the

High-pressure accumulator 3, the electromagnet 36 of the

Block valve 35 energized via the second control connection 42 to the high-pressure accumulator 3 with the second

Working line 8 to connect. Furthermore, the

Lock valve control 62 suitable to close the check valve 35 when the operation mode detector 51 detects neither a pump nor a motor operation and the

Axial piston machine 5 is set to zero displacement. The controller 40 also includes a

Emptying signal generator 63, for example, in the maintenance or repair case via the third control connection 43 can give a signal to the storage discharge valve 39 to empty the high-pressure accumulator 3.

FIGS. 5A, 5B and 5C show an exemplary time course of essential quantities of FIG Control method of the regenerative drive system 1. Fig. 5A shows the time course of the target torque T as a solid curve as given for example by a driver and the actual torque T _bl as a dashed curve. Fig. 5B shows the pressure-time diagram of the control pressure p as a solid line and the high pressure in the high-pressure accumulator 3 and at

opened check valve 35 in the second

Working pressure line 8 as a dashed line. 5C shows the time course of the set and detected pivot angle a of the axial piston machine 5.

The inventive method is based on the exemplary time course shown in FIG. 5 in connection with the method steps for regulating the torque on the drive shaft 4 of the axial piston machine 5 of FIG

Drive system 1 in Fig. 6 described.

At the time t ₀ , the axial piston machine 5 is set to the pivoting angle 0 °. This is realized, for example, by closing the check valve 35 and controlling the actuator by a state machine not shown in FIG. Since the check valve 35 is closed, there is no high pressure in the second working line 8. The high-pressure accumulator 3, however, is biased for example to 100 bar.

At the time t, should be braked with the drive system 1. The target torque setting device 45 outputs, in a first step Sl, a brake torque of the drive shaft 4, i. a positive setpoint torque. In step S2, the standing at about 0 ° swivel angle of

Swash plate 13 detected. The detected pivot angle a and the detected target torque T are applied to the

Operating mode detector 51 passed. Of the

Operating mode detector 51 detects in a third

Step S3, the operation mode. Since the swivel angle is almost 0 °, the operating mode of the

future operating mode, ie from the sign of the Target torque T determined. Since the target torque T is positive here in the example, the axial piston machine 5 is to be operated in pumping mode, ie in the first operating mode. In a fourth step S4, the check valve 35 is energized to connect the high-pressure accumulator 3 now with the second working line 8 when a pump or engine operation is detected. Otherwise, in an idle state, when the axial piston machine 5 is at zero stroke volume or should be adjusted, the energization of the electromagnet 36 of the check valve 35 is interrupted.

As a result of the connection, the high pressure in the second working line 8 rises to the 100 bar of the

High-pressure accumulator 3. The operation mode detector 51 outputs the target torque T and the pivot angle a to the first control pressure setting section 52 when the

Operation mode detector 51, the first operating mode

finds. The first control pressure setting section 52, as described, sets a control pressure p in a step S5, which is proportional to the ratio of the target torque T and the swing angle α. The control pressure p is initially almost infinitely large due to the finite setpoint torque and almost vanishing pivot angle a in the denominator. The control pressure p is therefore limited and set to a predefined maximum value. The calculated control pressure p is converted into a control pressure signal and given to the output 56 of the controller 40.

In step S7, the control pressure signal via the first control connection 41 to the electromagnet 32 of the

Pressure relief valve 30 transmitted, causing the

Opening pressure of the pressure limiting valve 30 is set to the calculated maximum control pressure. In step S8, the volume flow into or out of the first control pressure chamber 14 the pressure conditions and thus the force difference on both sides of

Control valve piston of the control valve 19 adapted. By the opening of the check valve 35 is located on the first side of the control valve piston of the high pressure of

High-pressure accumulator 3 on. By setting the

Opening pressure of the pressure limiting valve 30 is a maximum control pressure on the second side of the

Regulating piston on. Then, the control valve piston is moved from the neutral position in the direction of the second position. The first actuating pressure chamber 14 is connected to the tank volume 7 and hydraulic fluid flows from the first actuating pressure chamber 14 into the tank 7.

Therefore, the first actuating piston 9 in the first

Actuator 11 is pressed and the axial piston machine 5 is adjusted in the direction of larger positive pivot angle, i. in the direction of larger production volume.

The control steps S1 to S5 or S6 are repeated as long as the control is in operation. A loop duration is much shorter than the adjustment of the

Swash plate 13 of the axial piston machine 5. Thus, in the first embodiment, the adjustment of

Axial piston machine 5 e.g. 100 milliseconds and the

Loop duration 5 milliseconds. The loop will

within the adjustment time of the axial piston machine 5 from a minimum pivoting angle to a maximum

Go through the swivel angle 20 times. The loop duration is an order of magnitude below the adjustment time of the

Axial piston machine 5. Simultaneously, in steps S7 and S8, the volume flow in or out of the first

Adjusting pressure chamber 14 adapted to the high pressure and the control pressure.

Now that the pivot angle of the axial piston machine 5 in

Direction greater positive swivel angle is adjusted, in steps Sl to S5, the control pressure to the

T

amended pivot angle according to ρ = Κ _ι · - adapted. By a

the larger the pivot angle a of the control pressure p is lowered until the control force of the first hydraulic motor and corresponding to the actual torque T _bl -Torque the target T has reached. As soon as the swivel angle a is positive, the promotes Axial piston machine 5 hydraulic fluid in the

High-pressure accumulator 3 and so steadily increases the pressure prevailing in the second working line 8 high pressure. Of the

Control pressure p is readjusted to the high pressure, so that there is a balance between the first hydraulic force and the control force. In the example shown, the predetermined setpoint torque T is steadily raised, so that the control pressure p remains greater than the high pressure.

At time t ₂ , the setpoint torque T is set constant with about 120 Nm until time t _} . The high pressure continues to increase during pumping. Due to the increasing high pressure in the high pressure line 21, the control valve 19 is moved in the direction of the first position and by a pressure medium flow into the first control pressure chamber 14 into the pivot angle a is reduced. Due to the constant adaptation of the pivot angle a to the increasing high pressure and the feedback of the changed pivot angle a, this steadily decreases. By the

Feedback the pivot angle a in the determination of the control pressure p, the control pressure p stabilized below the growing high pressure. At the time t ₃ , the setpoint torque T is started to increase steadily again. Then also the pivot angle a of the axial piston machine 5 increases steadily and the control pressure p is above the high pressure

adjusted. At the time t ₄ drives the

Axial piston machine 5 at the maximum tilt angle a against a stop. The control pressure p increases due to the further increasing setpoint torque T on.

Due to the constant maximum pivot angle a, the control pressure p increases in direct proportion to the target torque T and is no longer adapted to the high pressure. Therefore, the control valve piston of

Control valve 19 moves in the direction of the second position and the first actuating pressure chamber 14 with the tank. 7

connected. The high pressure in the high-pressure accumulator 3 increases now by the constant pumping action on and slowly follows the increasing control pressure p.

At the time t _s , the setpoint torque T is kept constant at about 330 Nm until the time ί _Ί . Of the

Control pressure p stabilizes at about 280 bar and the high pressure continues to rise until time t ₆ until it reaches the control pressure p. By further increasing the high pressure in the high pressure accumulator 3 at a constant setpoint torque T, the high pressure acting in the high pressure line 21 presses the control valve 19 in the direction of the first position and causes a volume flow in the first control pressure chamber. 1 The swivel angle a is smaller, whereby the regulated in dependence of the swivel angle a control pressure p increases again and so the

High pressure follows.

From the time t ₇ , the target torque T is steadily reduced again. As a result, the control pressure p decreases and the swivel angle a continues to reduce. By the

Feedback of the sinking pivot angle a, the control pressure p is controlled below the high pressure. At the time t ₈ , the high pressure reaches the opening pressure of the pressure limiting valve 37, which is why the high pressure does not rise further despite the further pumping operation.

From the time t ₉ , the target torque is reduced more slowly. The swivel angle a also slows down to 0 °. At the time t ₁₀ , the setpoint torque T reaches a minimum setpoint torque, below which no control of the torque of the drive shaft 4 takes place any more and the setpoint torque T is suddenly increased to zero. For very small desired torques T are very small tilt angle a at the

Axial piston machine 5 and small pivot angle a lead by the inverse relationship to very large control pressures. Therefore, the regulation for small target torques would tend to oscillate. The control is to absolute target torques T greater than one to limiting the minimum nominal torque. Such a minimum nominal torque could also be used to detect a rest position of the axial piston machine 5. At the time t ₁₀ , the rest position is detected and the check valve 35 is closed. The swivel angle a is held at 0 ° by a state machine.

At the time t _u an acceleration torque, ie a negative target torque T, is specified. In the

Steps Sl to S4, the swivel angle a are detected, the setpoint torque is read in, the operating mode is established and the check valve 35 is opened. Of the

State machine is turned off when a motor or pump operation is detected. The axial piston machine 5 should now be operated in engine operation. As a result, the operation mode detector 51 outputs the target torque T and the swivel angle a to the second one

Control pressure setting section 53 described in conjunction with FIG. 4. In step S6, the second control pressure generation 53 calculates the control pressure p and outputs a control pressure p adjusting signal to the electromagnet 32 of the pressure relief valve 30. As a result of the predetermined acceleration torque results in the first portion p _{x of} the control pressure to zero, since the pivot angle a is still is at zero and a second portion of the control pressure greater than zero, since the actual torque is still at zero and a target torque is less than zero specified. This reduces the

Control pressure p and the axial piston machine 5 is in

Direction negative swing angle a swung until the actual torque 7 ^, to the target torque T

has settled. In order to adjust the further falling target torque T on the drive shaft 4, the

Control pressure p below the high pressure and continues the pivot angle a in the direction of larger

Swallow volume. By the engine operation it comes to a steady discharge of the high pressure accumulator 3, whereby the axial piston machine 5 driving high pressure decreases.

From the time t _n , the target torque T is set constant until about the time t ₁₃ at about -150 Nm. Due to the slowly falling high pressure, the control valve 19 is displaced in the direction of the second position and the first actuating pressure chamber 14 is connected to the tank 7. Thereupon, the swivel angle a changes in the direction of a smaller absorption volume, although the swivel angle a would have to be adjusted in the direction of the maximum absorption volume. By the readjustment of the control pressure p over the second portion p ₂ , this is corrected and the pivot angle a in

Direction of maximum absorption volume changed.

From the time t ₁₃ , the amount of the predetermined setpoint torque T decreases again steadily until the time t ₁₄ . As a result, the control pressure p increases due to the larger first portion p ₁ and the axial piston machine 5

pivoted in the direction of smaller swallow volume, i. in the direction of neutral. By the smaller one

Swivel angle a, the control pressure p is reduced, so that the control pressure p is set below the high pressure. The deviation between the control pressure p and the high pressure is greater in engine operation than in

Pumping operation, since at the negative angles the spring 17 is compressed more and so a larger

Counterforce generated on the actuator. From time t, the amount of the target

Torque T increases again and the proportion p of the control cam and thus the control pressure p decreases. The available high pressure is no longer sufficient to apply the target torque T and the

Axial piston machine 5 adjusted due to the first

Throttle 24 and the low pressure high, the swivel angle a not fast enough to maximum displacement. The amount of the swivel angle a is increased until the axial piston machine 5 reaches the stop at maximum absorption volume at the time t ₁₅ . Then the amount of the actual torque T _bl drops and the control pressure p drops rapidly due to the large difference between the setpoint torque and the actual torque. At the time t _{] 6} , the target torque T is slowly back to zero

reduced and the first portion of the control pressure?, increases due to the decreasing absolute target torque T and the second portion of the control pressure p ₂ increases due to the smaller difference between the target and actual torque T, T _bl . Thereupon, the control pressure p increases, thus retracting the swivel angle a in the direction of zero. When the target torque T approaches the actual torque T _bt at the time t ₁₇

stabilizes the control pressure p and the actual torque T _bl decreases with the target torque T to zero. At the time t ₁₈ , the high-pressure accumulator 3 is emptied and the pressure in the second working line 8 drops suddenly. Due to the lack of pressure in the control pressure line 27 and the high pressure line 21st

the flow control of the control valve 19 no longer works and the axial piston machine 5 is by the already mentioned state machine on a

Pivoting angle a kept at 0 °. First, the axial piston machine 5 pivots via the spring force 17 via neutral into pumping operation. The then rebuilt pressure allows the use of the state machine. The invention is not limited to that described

Embodiment limited. The first and the second operating mode could alternatively also by the

Exchange of the attack side of the control force and the first hydraulic force to the control valve 19 can be realized by a shuttle valve. This could be the

Control pressure p in each case as in the first

Operating mode of the embodiment described to

T

ρ = Κ _ι · - be calculated.

a The inventive method and the control device according to the invention are not limited to the

Use in regenerative drive systems. Rather, basically every hydrostatic machine whose

Torque is to be specified according to the invention

adjustable. Thus, the invention is also applicable to power regulators, which are torque regulators per se, when a torque is to be specified. In place of

Pressure in the high-pressure accumulator can then occur the pressure caused by a hydraulic resistance, such as the load pressure in a load moved by a hydraulic cylinder or by a connected one

Pressure relief valve specific pressure. Furthermore, it is also possible to control hydrostatic machines whose high pressure side changes. Here only has to change the respective high pressure working line with a

Control surface of the control valve 19 are connected.

Furthermore, the invention can only one

Operating mode or more than two modes of operation.

In the described embodiment, only the

Motor and pumping operation for one direction of rotation of the

Drive shaft 4 and a direction provided. Thus, the first operating mode could also include the motor operation in the reverse direction of the shaft 4, if the hydrostatic machine, for example, in a

is arranged closed circuit. In this case, only the high-pressure line 21 must be connected to the corresponding high-pressure working line, so that

within the first operating mode one more

Operation mode case distinction would have to take place, the control of the control pressure p would remain the same. Of the

Switching between the working lines could be done through a shuttle valve, which automatically opens a

high-pressure side working line with the first side of the control valve 19 connects. Possibly. Signs of the desired torque and the swivel angle must be taken into account so that the control pressure always remains positive.

Accordingly, the second mode of operation could also be the Pumping operation in the reverse direction of the drive shaft 4 include. Such an embodiment would

have a total of four operating modes, but the

basically retained.

It would also be conceivable to apply the regulation according to the invention to the deceleration and acceleration of a hydromotor-driven winch, e.g. the catapult-like acceleration and deceleration of the vehicles of a roller coaster with a hydromotor driven winch and a rope.

Furthermore, the invention finds in a start / stop automatic a particularly advantageous application. Thus, when restarting an internal combustion engine of the

regenerative drive system 1 is given a starting torque to the control device according to the invention and the setting angle of the axial piston machine 5 is automatically set to the correct position for generating the

Starting torque provided. Thus, a regenerative hydraulic starter can be realized with the invention particularly simple.

A fan could be driven by an inventively controlled hydraulic motor, which is supplied from a pressure line with pressure medium. The pressure line is supplied by a constant motor and so a certain pressure, which can vary, maintained. To the

Pressure line could still be connected to a hydraulic accumulator.

The invention is applicable to all hydrostatic machines. The control of the control pressure can at each rest position of the actuator in the unpressurized state, such as a central rest position at a

Zero-stroke volume, to be adjusted.

When applied to the regenerative drive system 1, which is driven by the axial piston machine 5, a disturbance acts, the first change in the regenerative drive system 1, a change in the hydraulic pressure in the second working line 8. By this pressure change, the hydraulic balance is changed at the control valve 19 and the axial piston machine 5 begins to

pivot. This process is recorded electronically and compensated as described. Advantageously, however, the occurrence of the disturbance variable can also be further processed and transmitted at an early point in time as information for a diesel engine as the drive motor of the regenerative drive system 1. This can happen, for example, via a bus connection. Thus, the diesel drive can adjust to the disturbance and it does not have the dead time to the occurrence of a

Speed deviation due to the disturbance to be waited. This time advantage is particularly beneficial for diesel engine adjustments, which due to tighter

Exhaust limits, can not react as dynamically. A disturbance is, for example, a change in the

Lastmoments by changing a to be mastered

Pitch .

The aforementioned embodiments and especially their individual aspects can be combined with each other in an advantageous manner.

Claims

claims

1. A method for controlling a torque of

Driving shaft (4) of a hydrostatic machine (5), wherein the hydrostatic machine (5) has an adjusting device for adjusting its stroke volume, the method comprising the following steps:

- detecting a predetermined setpoint torque (Sl, Sil);

- Detecting a set stroke volume of

hydrostatic machine (5) (S2, S12);

- regulating a volume flow into or out of the actuator by means of a control valve (19) for adjusting the displacement on the basis of a force difference between a control force and a force acting on the control valve (19) in the opposite direction (S9, S20);

characterized,

in that the force acting in the opposite direction to the control force on the control valve (19) is a

hydraulic power is by a on the

High-pressure side of the hydrostatic machine (5)

prevailing pressure is generated and contrary to the

Control force acts, wherein the size of the control force in dependence of the detected stroke volume and the detected target torque is set (S5, S6, S17).

2. The method according to claim 1,

characterized,

that the control force at least partially a

hydraulic power is.

3. The method according to claim 2,

characterized,

that the hydraulic force as an adjustable component of the control force by adjusting an opening pressure of a pressure relief valve (30) from the pressure of the

High pressure side is generated (S7, S18).

4. The method according to any one of claims 1 to 3, characterized,

that the control force in dependence on the ratio of detected predetermined target torque to the

detected stroke volume is generated.

5. The method according to claim 4,

characterized,

the control force in a first operating mode is proportional to the ratio of the detected setpoint torque to the detected displacement volume (S5, S17).

6. The method according to any one of claims 1 to 5,

characterized,

in that the adjustable component of the control force has at least two parts in a second operating mode

(S6), wherein the first proportion is indirectly proportional to the absolute value of the ratio of the detected target torque to the detected stroke volume and the second portion of a difference between the detected predetermined target torque and an actual torque of the drive shaft (4) of the hydrostatic Machine (5) depends.

7. The method according to claim 6,

characterized,

that the actual torque of the drive shaft (4) of the

hydrostatic machine (5) from one on the

High-pressure side of the hydrostatic machine (5)

prevailing high pressure and the detected stroke volume is calculated.

8. The method according to claim 7,

characterized,

that the magnitude of the pressure on the high pressure side is estimated based on the control force.

9. The method according to claim 8,

characterized,

that the control force is filtered or smoothed to estimate the high pressure.

10. The method according to any one of claims 1 to 9,

characterized ,

that in a first operating mode and in a second operating mode, the direction of attack of the control force and the opposite force is interchanged.

11. A control device for controlling a

Torque of a drive shaft (4) of a hydrostatic machine (5) having an adjusting device for adjusting the stroke volume of the hydrostatic machine (5), the control device comprising a control valve (19) for controlling a volume flow into the adjusting device or out of the adjusting device for Adjusting the stroke volume based on a force difference between a control force and a force acting in the opposite direction on the control valve (19), a

Torque setting device (45) for setting a target torque of the drive shaft (4) and a

Hubvolumenerfassungsvorrichtung (46) for detecting a set stroke volume of the hydrostatic machine (5),

characterized ,

in that, in order to produce the force acting in the opposite direction on the control valve (19), one side of the control valve (19) is connected to a high pressure side of the

hydraulic machine (5) is connected and that the control device comprises a control device (40, 66) which is adapted to specify the size of the control force depending on the detected displacement and the detected desired torque.

12. Control device according to claim 11,

characterized,

that the control valve (19) has a first with a

High-pressure side of the hydrostatic machine (5)

connected terminal, a second with a

Low pressure accumulator or tank (7) connected terminal and a third with a control pressure chamber (14) of the Actuator connected connection and the control valve (19) between a first, the first

Connection with the third connection connecting position and a second, the second connection to the third connection connecting position is adjustable.

13. Control device according to claim 11 or 12,

characterized,

in that for setting the control force, a control surface of the control valve (19) is connected or connectable to a control pressure line (27) and the control force is adjustable by means of the height of the control pressure acting there.

14. Control device according to claim 13,

characterized,

that the control pressure line (27) for adjusting the

Control pressure from the pressure of the high pressure side

Pressure limiting valve (30) whose opening pressure is adjustable.

15. Control device according to one of claims 11 to 14,

characterized,

a change-over valve (64) is provided, wherein in a first position of the shuttle valve (64) a control surface of the control valve (19) with a high-pressure side of

hydrostatic machine (5) and a second,

in a second position of the shuttle valve (64), the second control surface of the control valve (19) with the high pressure side of the hydrostatic machine (5) and the first

Control surface of the control valve (19) with the

Control pressure line (27) is connected, wherein the

Control device (66) is adapted to specify the control pressure of the control pressure line (27).

16. Control device according to one of claims 11 to 15, characterized ,

in that the control device (40, 66) for calculating the control force is set up according to one of Claims 4 to 9.

17. Control device according to one of claims 11 to 16,

characterized ,

in that the high-pressure side of the hydrostatic machine (5) is connected to a high-pressure accumulator (3) and the hydrostatic machine (5) is adjustable from a neutral position in two opposite directions.

18. Control device according to one of claims 11 to 17,

characterized,

in that a pressure sensor for detecting the high pressure is provided for monitoring the regulation of the regulating device