CN115956165A - Method for operating a hydraulic drive - Google Patents

Method for operating a hydraulic drive Download PDF

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Publication number
CN115956165A
CN115956165A CN202180045058.6A CN202180045058A CN115956165A CN 115956165 A CN115956165 A CN 115956165A CN 202180045058 A CN202180045058 A CN 202180045058A CN 115956165 A CN115956165 A CN 115956165A
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CN
China
Prior art keywords
hydraulic
ist
positionable
pump
revolutions
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CN202180045058.6A
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Chinese (zh)
Inventor
H·诺亚克
M·瓦勒尔
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Robert Bosch GmbH
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Robert Bosch GmbH
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Publication of CN115956165A publication Critical patent/CN115956165A/en
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B21/00—Common features of fluid actuator systems; Fluid-pressure actuator systems or details thereof, not covered by any other group of this subclass
    • F15B21/08—Servomotor systems incorporating electrically operated control means
    • F15B21/087—Control strategy, e.g. with block diagram
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B15/00—Fluid-actuated devices for displacing a member from one position to another; Gearing associated therewith
    • F15B15/20—Other details, e.g. assembly with regulating devices
    • F15B15/28—Means for indicating the position, e.g. end of stroke
    • F15B15/2815—Position sensing, i.e. means for continuous measurement of position, e.g. LVDT
    • F15B15/2838—Position sensing, i.e. means for continuous measurement of position, e.g. LVDT with out using position sensors, e.g. by volume flow measurement or pump speed
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B19/00—Testing; Calibrating; Fault detection or monitoring; Simulation or modelling of fluid-pressure systems or apparatus not otherwise provided for
    • F15B19/007—Simulation or modelling
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B7/00—Systems in which the movement produced is definitely related to the output of a volumetric pump; Telemotors
    • F15B7/005—With rotary or crank input
    • F15B7/006—Rotary pump input
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B19/00—Testing; Calibrating; Fault detection or monitoring; Simulation or modelling of fluid-pressure systems or apparatus not otherwise provided for
    • F15B19/002—Calibrating
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/205—Systems with pumps
    • F15B2211/20507—Type of prime mover
    • F15B2211/20515—Electric motor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/205—Systems with pumps
    • F15B2211/2053—Type of pump
    • F15B2211/20538—Type of pump constant capacity
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/205—Systems with pumps
    • F15B2211/2053—Type of pump
    • F15B2211/20546—Type of pump variable capacity
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/205—Systems with pumps
    • F15B2211/2053—Type of pump
    • F15B2211/20561—Type of pump reversible
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/205—Systems with pumps
    • F15B2211/2053—Type of pump
    • F15B2211/20569—Type of pump capable of working as pump and motor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/27—Directional control by means of the pressure source
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/305—Directional control characterised by the type of valves
    • F15B2211/3056—Assemblies of multiple valves
    • F15B2211/30565—Assemblies of multiple valves having multiple valves for a single output member, e.g. for creating higher valve function by use of multiple valves like two 2/2-valves replacing a 5/3-valve
    • F15B2211/3058—Assemblies of multiple valves having multiple valves for a single output member, e.g. for creating higher valve function by use of multiple valves like two 2/2-valves replacing a 5/3-valve having additional valves for interconnecting the fluid chambers of a double-acting actuator, e.g. for regeneration mode or for floating mode
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/63—Electronic controllers
    • F15B2211/6303—Electronic controllers using input signals
    • F15B2211/6306—Electronic controllers using input signals representing a pressure
    • F15B2211/6313—Electronic controllers using input signals representing a pressure the pressure being a load pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/63—Electronic controllers
    • F15B2211/6303—Electronic controllers using input signals
    • F15B2211/633—Electronic controllers using input signals representing a state of the prime mover, e.g. torque or rotational speed
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/665—Methods of control using electronic components
    • F15B2211/6651—Control of the prime mover, e.g. control of the output torque or rotational speed
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/665—Methods of control using electronic components
    • F15B2211/6656—Closed loop control, i.e. control using feedback
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/665—Methods of control using electronic components
    • F15B2211/6657—Open loop control, i.e. control without feedback
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/705—Output members, e.g. hydraulic motors or cylinders or control therefor characterised by the type of output members or actuators
    • F15B2211/7051—Linear output members
    • F15B2211/7053—Double-acting output members
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/75—Control of speed of the output member
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/76—Control of force or torque of the output member
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/765—Control of position or angle of the output member
    • F15B2211/7656—Control of position or angle of the output member with continuous position control
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/775—Combined control, e.g. control of speed and force for providing a high speed approach stroke with low force followed by a low speed working stroke with high force, e.g. for a hydraulic press

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Fluid-Pressure Circuits (AREA)

Abstract

The invention relates to a method for operating a hydraulic drive (100 a) comprising a hydraulic pump (120) driven by an electric motor (110) with a variable number of revolutions and a hydraulic consumer (130) connected to the hydraulic pump (120), the hydraulic pumpThe pressure load is provided with a positionable element (132), wherein the model (200) of the hydraulic drive (100 a) and the number of revolutions (n) of the hydraulic pump (120) are based ist ) Or the number of revolutions, to determine a position and/or speed estimate (x) of a position (x) or a speed of a positionable element (132) for the hydraulic consumer (130) ist ) And wherein the position and/or velocity estimate (x) is based ist ) A hydraulic drive (100 a) is operated.

Description

Method for operating a hydraulic drive
Technical Field
The invention relates to a method for operating a hydraulic drive, comprising a hydraulic pump driven by an electric motor with a variable number of revolutions and a hydraulic consumer connected to the hydraulic pump, wherein the hydraulic consumer has a positionable element; the invention further relates to an arithmetic unit and a computer program for implementing the method.
Background
An electro-hydraulic shaft relates to a hydraulic drive having a motor, a hydraulic pump and a hydraulic cylinder, wherein, for example, an electrical or electronic adjustment of the position of the cylinder or of its piston is possible. Such electrohydraulic shafts are used, for example, in so-called deep-drawing presses, injection molding machines or other molding machines, as are used, for example, for heavy loads or for the movement of machine parts.
In many cases, separate force-position control is provided in such electrohydraulic shafts, i.e., force control or position control takes place, for example, as a function of operating points. Instead of a force control, a pressure control can also be provided, which is based on the equivalence of the relationship between the force and the pressure in the hydraulic cylinder, for example, via the pressure-acting surface.
In such a regulation, for example, a valve for a change in the volume flow of hydraulic liquid in the cylinder can be used. Adjustment of the number of revolutions of the motor driving the hydraulic pump can also be achieved. The hydraulic pump can be designed in particular as a fixed displacement pump with a fixed delivery rate per working cycle or as a variable displacement pump with a variable delivery rate.
Disclosure of Invention
According to the invention, a method for operating a hydraulic drive, an arithmetic unit and a computer program for carrying out the method are proposed, which have the features of the independent claims. Advantageous embodiments are the subject matter of the dependent claims and of the following description.
The invention relates to a method for operating a hydraulic drive comprising a hydraulic pump, in particular a fixed displacement pump, which is driven by an electric motor with a variable number of revolutions, and a hydraulic consumer connected to the hydraulic pump, the hydraulic consumer having a positionable element. The hydraulic load with the positionable member is preferably a hydraulic cylinder with a piston as the positionable member.
The operation of such hydraulic drives is typically controlled by adjusting or, if necessary, also only controlling the position or, if necessary, the speed of the positionable member on the one hand and the pressure exerted on or, if necessary, the force exerted by the hydraulically loaded positionable member on the other hand. For completeness, it should furthermore be mentioned that: pressure regulation and force regulation are equivalent in hydraulic loads, since the pressure across the active surface is correlated with the force. As explained at the outset, separate force-position regulation can be provided here, i.e. force or pressure regulation or position or speed regulation (or in each case only control if necessary) can take place, for example, as a function of the operating point. As also already explained, valves for changing the volume flow of the hydraulic medium in the hydraulic consumer can be used in such a regulation, for example. Furthermore or alternatively, an in particular secondary regulation of the number of revolutions of a motor driving the hydraulic pump can be achieved, which is associated with, in particular even identical to, the number of revolutions of the pump.
For proper operation of such hydraulic actuators, it is necessary for the variables involved, i.e., in particular the position or the speed of the positionable element and the actual value of the pressure or the force. This can be detected or measured by means of corresponding sensors, which are arranged at suitable positions on the hydraulic load.
However, this is disadvantageous in that the cost of such sensor devices and their integration into the hydraulic drive is high. This high cost is undesirable in most cases, especially in simple applications of hydraulic drives.
Against this background, it is proposed: the position and/or speed estimate of the position or speed of the positionable element for the hydraulic consumer is determined on the basis of a model of the hydraulic drive and the number of revolutions or revolutions of the hydraulic pump (which is associated with the number of revolutions or revolutions of the electric motor as explained and can also be used synonymously for this), as a result of which or on the basis of which the hydraulic drive is subsequently operated, more precisely in particular by using the position and/or speed estimate as an actual value for adjusting the positionable element of the hydraulic consumer.
By adjusting the pressure exerted on or by the hydraulically loaded positionable member in particular here. The position and/or the speed of the positionable element of the hydraulic consumer is then preferably controlled on the contrary, but can equally be adjusted within the scope of the invention.
The model may be, for example, a physical model of a hydraulic drive, in which all relevant geometries of the particular hydraulic drive are taken into account. From this it is possible to calculate, for example: during the rotation of the pump, the hydraulic medium is conveyed to the hydraulic consumer in a small amount and the positionable element is moved by a small amount. In particular, dynamic effects can also be taken into account here. A type of model-based sensor system is thus provided which is sufficient for the requirements without a physical sensor. In this case, the observer is also referred to, by means of which the estimated value is determined. In a simple embodiment, the amount variation is produced as the product of pump rotation and delivered amount, and the position variation is produced as the quotient of the amount variation and the cylinder cross-sectional area.
In this way, a particularly simple, cost-effective and robust solution for a hydraulic drive, such as an electrohydraulic actuator or shaft, as explained above, is provided, which is furthermore plug-and-play operable, i.e. more or less simple to create and apply, and which is furthermore simple to handle in the case of service and thus enables a wide range of applications. The proposed method of using the model is sufficiently accurate, in particular for simple applications with dynamics and precision, if necessary limited, such as, for example, lifting shafts (Hubachsen), clamping shafts (Klemmachsen) or accessories.
When using the estimated values for position and/or velocity (i.e. position and/or velocity estimated values), it is furthermore possible to determine values or actual values for the pressure exerted on the positionable element or the force exerted by the positionable element by means of the sensor. In this case, it is conceivable, for example, to use a respective pressure sensor on each of the two sides of the differential cylinder of the hydraulic consumer.
However, it is also preferred that, in addition, a model for the hydraulic drive determines a pressure or force estimate for the pressure or force, in particular when using or on the basis of the actual value of the torque (or, if necessary, the corresponding current) of the electric motor, wherein the hydraulic drive is then operated on the basis of the pressure or force estimate, i.e. the pressure or force estimate can be used, for example, as the actual value for the aforementioned regulation. A pressure or force sensor is then not necessary at least at the location concerned. This makes it possible to provide a still simpler and also more advantageous solution, as is sufficient, for example, for use in adjusting drives or lifting shafts or lifting tables.
Preferably, the leakage of the hydraulic medium is also taken into account in the model of the hydraulic drive, as may occur, for example, in the hydraulic consumers, pumps and hydraulic lines. The leakage quantity is also related to the displacement, if necessary also the speed, which is passed through the positionable element. This makes the operation or regulation of the hydraulic drive more accurate even in the absence of a sensor. As already mentioned, different types of operation can be distinguished in particular here. Thus, for example, leakage of the hydraulic medium can be taken into account individually (i.e. with different factors if necessary) for the removal and/or the removal of the displaceable element and/or the removal of the retraction and/or the return. Recuperation here represents the operation of the differential cylinder, wherein the two cylinder chambers are hydraulically connected and filled with hydraulic medium by the additionally supplied volume flow. The cylinder is moved out here because the moving-out force via the (larger) piston surface exceeds the moving-in force via the (smaller) annular surface at approximately the same pressure. In the event of a removal, the oil pushed out of the annular chamber is guided into the piston chamber. This volume flow now no longer has to be delivered by a "normal" (or customary) volume flow source (pump/valve). Effectively, a "normal" volume flow source only has to deliver hydraulic medium to the face (= piston face — annular face) as well, so that a significantly smaller volume flow from the "normal" source is required, or a significantly higher displacement speed of the displacement can be achieved with the maximum volume flow of the "normal" source. So-called "fast moving-line" is also referred to herein.
It is furthermore preferred that the position and/or speed estimate is corrected, in particular repeatedly (for example at regular time intervals or in dependence on the total displacement traveled by the positionable member), by moving the hydraulically loaded positionable member closer to the reference position. In such reference positions, such as for example the end position or the end stop (i.e. when the positionable element is completely moved in or out or reaches a mechanical stop or a position which is otherwise accurately detectable), the position of the positionable element is known per se on the basis of, for example, its geometry. Reaching the end stop can be detected, for example, by the motor torque and optionally by a pressure sensor (if present). Any reference position can be recognized, for example, by a simple detector (switch contact). It is appropriate to set such a position to a bit state which is reached as often as possible, for example in each cycle.
If the position estimate differs from the actual value at such a reference position, which drift is largely not prevented in practice even with accurate models, a correction can be carried out, i.e. the estimate can be reset. In particular, a drift of the estimated value due to leakage can also be compensated particularly well with such a correction.
The arithmetic unit according to the invention, for example a control unit of an electrohydraulic spindle, is designed in particular by means of program technology for carrying out the method according to the invention.
The implementation of the method according to the invention in the form of a computer program or a computer program product with program code for carrying out all method steps is also advantageous, since this results in particularly low costs, in particular if the control device implemented is also used for further tasks and is therefore available anyway. Suitable data carriers for providing the computer program are in particular magnetic, optical and electrical memories, such as for example hard disks, flash memories, EEPROMs, DVDs and others. But also downloads of the program via a computer network (internet, intranet, etc.) are possible.
Further advantages and design aspects of the invention result from the description and the drawings.
It is clear that the features mentioned above and those yet to be explained below can be used not only in the respective combinations indicated, but also in other combinations or individually, without departing from the scope of protection of the present invention.
Drawings
The invention is schematically illustrated according to embodiments in the drawings and will be described in detail hereinafter with reference to the drawings.
Fig. 1a and 1b show schematically a hydraulic drive which is suitable for carrying out the method according to the invention.
Fig. 2 schematically shows a model of a hydraulic drive, as it can be used in the method according to the invention in a preferred embodiment.
Detailed Description
Fig. 1a schematically shows a hydraulic drive 100a, in which the method according to the invention can be implemented, as will also be explained below. The hydraulic drive 100a has an electric motor or drive 110 with a variable number of revolutions, which is connected to a hydraulic pump 120, for example, via a coupling 115. The hydraulic pump 120 is, for example, an axial piston pump realized as a fixed displacement pump with a fixed delivery volume per working cycle. The hydraulic pump 120 can be driven with variable number of revolutions by means of the electric motor 110.
Furthermore, the hydraulic pump 120 is connected to a hydraulic consumer 130, which is here a cylinder 131 with a positionable element 132 in the form of a piston. The hydraulic pump 120 is connected on both ends with cylinders 131, so that movement of the piston 132 in both directions is possible, depending on the direction of rotation of the hydraulic pump 120. The electric motor 110 can be operated via an arithmetic unit 150 embodied as a control unit, if necessary via further components, such as an inverter or a frequency converter. The hydraulic drive 100a can thus be used as an electrohydraulic spindle.
For operating the hydraulic drive 100a, the position x of the piston or the positionable element 132 can be controlled or, if necessary, adjusted according to the method according to the invention in a preferred embodiment. For this purpose, control unit 150 may, for example, predetermine setpoint value x for position x soll 。
For adjusting the position x, the current actual value x ist Such as may be necessary. The actual value x ist Instead of detection or measurement by means of sensors or displacement sensors, the actual value x is estimated by means of the observer 155 ist Is a position estimate. Here, a model of the hydraulic-based drive (as will be explained further below with reference to fig. 2) and the current number of revolutions n of the electric motor 110 of the hydraulic pump 120 or in the same sense as this ist Calculating the actual value x ist . Here, for example, it is possible to calculate or estimate: which number of revolutions is necessary for which duration-or which number of revolutions-in order to move the piston by a determined displacement. Accordingly, the electric motor can be operated using, for example, the current I as a manipulated variable for the secondary regulation of the rotational speed.
As already explained above, the pressure exerted on the piston 132 can also be set. For this purpose, the actual value p of the pressure ist It is necessary that the actual value of the pressure in the hydraulic drive 100a, however-as in position-is not determined by means of sensors or pressure gauges, but is likewise determined, for example, by means of an observer 155, i.e., based on a model and the torque M of the electric motor 110 ist (the torque is obtained from the current forming the torque, if necessary).
To correct for example the position estimate, the piston may be moved to a reference position x R The piston reaches a stop (in this case: is moved completely in), for example mechanically. The reference position x R For example, can be stored in the control unitSo that the position estimate, if calculated for this according to the model, is compared with the reference position x R Or the associated position values are different, the position estimate may be corrected.
In this way, a particularly simple and robust control or regulation of the hydraulic drive can thus be achieved without cost-intensive sensors, which is also sufficiently accurate at least for simple applications.
Fig. 1b schematically shows a hydraulic drive 100b, in which the method according to the invention can also be implemented. In contrast to the hydraulic drive 100a according to fig. 1a, two pressure sensors 140, 141 are provided, by means of which the pressure p in the pressure medium on the a side of the cylinder 131 can be measured A Or pressure p on the B side of the cylinder 131 B . These pressure values are then supplied to the control unit 150 and used there as actual values in the control or regulation. In contrast to the method explained with reference to fig. 1a, the estimate is therefore only determined for the position, but no longer for one or more pressures. Reference may furthermore be made to the description of fig. 1 a.
In this way, simple and robust control or regulation of the hydraulic drive can also be achieved at least in part without cost-intensive sensors, which is also sufficiently accurate for applications that are slightly more complex than the variant according to fig. 1 a.
Fig. 2 schematically shows a model 200 of a hydraulic drive, as it can be used or used in a method according to the invention in a preferred embodiment, and which takes into account leaks in particular. The delivery flow V through the pump by the number n of revolutions of the electric motor 110 g Causing a volume flow Q of hydraulic medium of a hydraulic pump P 。
Volume flow Q into the cylinder Z In principle, the volume flow Q of the hydraulic pump P However, minus the leakage volume flow Q leak The leakage volume flow is lost on the basis of leakage, for example in the pump or in the line. The leakage volume flow Q leak Now the leakage factor k and the number of revolutions n of the electric motor (or pump) are related.
As already statedAlso, it has been shown that: leakage or leakage volume flow Q leak Depending on the way in which the cylinder is moved, this can be taken into account in the model 200 in that the leakage factor is selected differently depending on the situation, the number of revolutions being multiplied by the leakage factor in order to obtain the actual leakage volume flow Q leak . Thus, for example, the coefficient k is used for the removal of the cylinder out Using the coefficient k for the shifts in And the coefficient k is used for the removal of the recovery recu . These coefficients can be determined for the respective application, for example on a test bench. Examples for such coefficients are for better elucidation: k is a radical of formula out = 0.7% * V g ，k in And k = 3.5%. Vg recu = 2.4%. Vg. In practice, these coefficients are typically related to the specific pump, if necessary to valves, hydraulic medium, operating pressure, cylinder seals, etc. In this way, the operation of the hydraulic drive can be improved again.

Claims (14)

1. Method for operating a hydraulic drive (100 a, 100 b) comprising a hydraulic pump (120) driven by an electric motor (110) with a variable number of revolutions and a hydraulic consumer (130) connected to the hydraulic pump (120) and having a positionable element (132),
wherein a model (200) of the hydraulic drive (100 a, 100 b) and a number of revolutions (n, n) of the hydraulic pump (120) are used as a basis ist ) Or the number of revolutions, to determine a position and/or speed estimate (x) for the position (x) or speed of the positionable element (132) of the hydraulic consumer (130) ist ) And is and
wherein the position and/or velocity estimate (x) is based on ist ) Operating the hydraulic drive (100 a, 100 b).
2. Method according to claim 1, wherein the position and/or velocity estimate (x) ist ) Is used as an actual value for the adjustment of the positionable element (132) of the hydraulic load (130).
3. Method according to claim 2, wherein the position and/or the speed of the positionable member (132) of the hydraulic load (130) and/or the pressure exerted on the positionable member (132) of the hydraulic load (130) and/or the force exerted by the positionable member (132) of the hydraulic load (130) are adjusted by means of said adjustment.
4. A method according to claim 2 or 3, wherein the position (x) and/or the speed of a positionable member (132) of the hydraulic load (130) is controlled.
5. Method according to one of the preceding claims, wherein a pressure and/or force estimate (p) for the pressure exerted on the positionable element (132) of the hydraulic load (130) or the force exerted by the positionable element (132) of the hydraulic load (130) is ascertained on the basis of a model (200) of the hydraulic drive (100 a) in addition ist ) And wherein the pressure and/or force estimate (p) is based on ist ) Operating the hydraulic drive (100 a).
6. Method according to any of the preceding claims, wherein a secondary regulation of the number of revolutions (n) of the hydraulic pump (120) is performed.
7. The method according to one of the preceding claims, wherein a leakage of hydraulic medium is taken into account in a model (200) of the hydraulic drive (100 a, 100 b).
8. The method according to claim 7, wherein the removal of the positionable element (132) and/or the movement in and/or the removal of the recovery individually for the hydraulic load (130) takes into account leakage of the hydraulic medium.
9. The method of any one of the preceding claims, whereinIn particular repeatedly correcting said position and/or velocity estimate (x) ist ) By moving a positionable member (132) of the hydraulic load (130) closer to a reference position (x) R ）。
10. The method according to any one of the preceding claims, wherein a fixed displacement pump or a variable displacement pump is used as the hydraulic pump (120).
11. The method according to any one of the preceding claims, wherein the hydraulic drive (100 a, 100 b) is used for an electro-hydraulic shaft.
12. Arithmetic unit (150) configured to implement the method according to one of the preceding claims.
13. Computer program which, when executed on said arithmetic unit (150), causes said arithmetic unit (150) to implement the method according to any one of claims 1 to 11.
14. A machine-readable storage medium having stored thereon a computer program according to claim 13.
CN202180045058.6A 2020-06-25 2021-06-23 Method for operating a hydraulic drive Pending CN115956165A (en)

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