CN113007055A - Method for operating a variable speed variable displacement pump - Google Patents

Method for operating a variable speed variable displacement pump Download PDF

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Publication number
CN113007055A
CN113007055A CN202011508905.1A CN202011508905A CN113007055A CN 113007055 A CN113007055 A CN 113007055A CN 202011508905 A CN202011508905 A CN 202011508905A CN 113007055 A CN113007055 A CN 113007055A
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China
Prior art keywords
soll
speed
value
variable
target
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CN202011508905.1A
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Chinese (zh)
Inventor
M·瓦勒
S·贝克
T·森德尔巴赫
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Robert Bosch GmbH
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Robert Bosch GmbH
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B1/00—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders
    • F04B1/12—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinder axes coaxial with, or parallel or inclined to, main shaft axis
    • F04B1/26—Control
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B1/00—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders
    • F04B1/12—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinder axes coaxial with, or parallel or inclined to, main shaft axis
    • F04B1/26—Control
    • F04B1/30—Control of machines or pumps with rotary cylinder blocks
    • F04B1/32—Control of machines or pumps with rotary cylinder blocks by varying the relative positions of a swash plate and a cylinder block
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B1/00—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders
    • F04B1/12—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinder axes coaxial with, or parallel or inclined to, main shaft axis
    • F04B1/26—Control
    • F04B1/30—Control of machines or pumps with rotary cylinder blocks
    • F04B1/32—Control of machines or pumps with rotary cylinder blocks by varying the relative positions of a swash plate and a cylinder block
    • F04B1/324—Control of machines or pumps with rotary cylinder blocks by varying the relative positions of a swash plate and a cylinder block by changing the inclination of the swash plate
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
    • F04B49/06—Control using electricity
    • F04B49/065—Control using electricity and making use of computers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
    • F04B49/20—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00 by changing the driving 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
    • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/02—Systems essentially incorporating special features for controlling the speed or actuating force of an output member
    • F15B11/04—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed
    • F15B11/042—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed by means in the feed line, i.e. "meter in"
    • F15B11/0423—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed by means in the feed line, i.e. "meter in" by controlling pump output or bypass, other than to maintain constant speed
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B2203/00—Motor parameters
    • F04B2203/02—Motor parameters of rotating electric motors
    • F04B2203/0209—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
    • F15B2211/20—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
    • F15B2211/20546—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
    • F15B2211/27—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
    • F15B2211/60—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
    • F15B2211/6309—Electronic controllers using input signals representing a pressure the pressure being a pressure source supply 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
    • F15B2211/63—Electronic controllers
    • F15B2211/6303—Electronic controllers using input signals
    • F15B2211/6333—Electronic controllers using input signals representing a state of the pressure source, e.g. swash plate angle
    • 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
    • F15B2211/6652—Control of the pressure source, e.g. control of the swash plate angle
    • 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
    • F15B2211/6653—Pressure 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
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/665—Methods of control using electronic components
    • F15B2211/6654—Flow rate 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
    • F15B2211/60—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
    • F15B2211/70—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

Abstract

The invention relates to a method for operating a variable-speed control pump, in which method a delivery means (122) that can be controlled in the displacement per operating cycle is driven by means of a variable-speed drive (121), wherein, within the scope of regulation, a target speed value (n) for the speed of the drive is predefinedsoll) And a target value (alpha) of a characteristic variable for determining the displacement per working cyclesoll) Regulating at least one parameter to a target value (p)soll) Wherein the target value (alpha) of the characteristic quantity for determining the displacement of each working cycle is changedsoll) The target rotational speed value (n) is adapted by a pre-controlsoll）。

Description

Method for operating a variable speed variable displacement pump
Technical Field
The invention relates to a method for operating a variable-speed control pump, in which a delivery means that is adjustable in the displacement per operating cycle is driven by means of a variable-speed drive, and to an electrohydraulic system.
Background
The pump on which the invention is based has a delivery mechanism with a variable displacement per working cycle (so-called hydraulic piston machines, for example axial piston machines), which is driven by means of a drive with a variable rotational speed. In the operation of such pumps, the volume flow and/or the delivery pressure (i.e. the pressure difference between the inlet and the outlet) are usually controlled by appropriate adaptation of the displacement and the rotational speed of the delivery means, i.e. such pumps have two degrees of freedom in the control.
For example, a method is known from EP 2192309B 1, in which a pump of this type is operated by controlling the pressure or the pressure medium quantity by controlling the volume setting of the pump. Here, the rotational speed deviation of the drive device is taken into account.
Disclosure of Invention
According to the invention, a method and an electrohydraulic system are proposed with the features of the independent claims. Advantageous embodiments are the subject matter of the dependent claims and the following description.
The invention relates to the operation of variable-speed control pumps, such as in particular axial piston pumps with, for example, two-point or proportional control, in which a variable-speed delivery mechanism is driven by means of a variable-speed drive, such as, for example, an electric motor, during the displacement of each operating cycle. For adjusting the conveying device, a so-called wobble plate can be provided in such an adjusting pump, for example.
In the operation of such a control pump, usually within the scope of regulation, at least one variable, such as, for example, a pressure, is regulated to a target value (of the at least one variable) by specifying a target value for the rotational speed of the drive and a target value for a characteristic variable for determining the displacement of each operating cycle.
Preferably, said at least one parameter is selected from: a pressure and/or volume flow of a medium, such as, for example, oil, with which the pump is operated (or is used as a working medium); a force generated directly or indirectly through the medium; and the position of an element moving directly or indirectly through the medium. In particular, the force and position can relate not only to a system with a regulating pump and a drive, but also to a higher-order system in which the regulating pump is used together with the drive, for example an electro-hydraulic shaft or in general an electro-hydraulic system.
The characteristic quantity determining the displacement per working cycle, such as in the case of the axial piston pump with wobble disk mentioned, can be referred to as the wobble angle. In this example, the oscillation angle is adjusted by changing the adjustment angle (Anstellwinkel) of the oscillating disc, thereby changing the stroke of the individual pistons in the delivery mechanism of the pump and thus the displacement per working cycle.
Depending on the circumstances, it has been shown that a control pump with a specific, in particular low, displacement per operating cycle is suitable and in particular energy-efficient to operate. This is based on-at least at constant pressure-the reduction in torque required. If, during operation, a demand for a change or adaptation of the displacement in each operating cycle is identified and caused — by way of a corresponding characteristic variable such as the pivot angle, the (Nachregelung) rotational speed needs to be readjusted in order to maintain, as is usually desired, (as high as possible) constantly at least one variable to be regulated, such as the pressure.
However, it has now been found that such a change or adaptation of the displacement in each operating cycle has an adverse effect on the (higher-order) variable to be controlled or its actual value, so that a readjustment of the at least one variable is required in this case or the corresponding regulator must intervene. As can be appreciated, this is based on the fact that the rotational speed dynamics of the drive are usually not sufficient to compensate for the displacement adjustment per working cycle correspondingly quickly, which may result, for example, in a pressure disturbance (Druckeinbruch).
Within the scope of the present invention, it is now proposed that, when changing the target value of the characteristic variable for determining the displacement volume per operating cycle, the target value of the rotational speed (and preferably also the target value of the torque) is adapted by a pilot control as a function of the dynamics or speed of the adjustment of the conveying means, in particular also as a function of the operating point. By this pre-control of the rotational speed target value, in particular in parallel with the change or adaptation of the displacement volume per operating cycle, a readjustment of the rotational speed and thus also a possible pressure disturbance can be prevented. Thus, the (superordinate) regulator does not have to intervene at all, but the at least one parameter concerned remains constant. This is particularly effective if the change or adaptation of the rotational speed of the drive takes place or can take place more quickly than the change or adaptation of the displacement volume per working cycle.
The target rotational speed value and/or a target value that is adapted to the target rotational speed value and/or a target value of a characteristic variable for determining the displacement volume per operating cycle is preferably predefined using a model, in which the speed of the control of the conveying means is taken into account, and particularly preferably using a model-predictive control (using such a model). Model-predictive control (MPC in english is "model predictive control") makes possible a particularly simple and precise and therefore also effective control, in particular because the non-linear behavior of the electrohydraulic system with the control pump and the drive present here can be mapped particularly well.
The model predicted regulation is a regulation scheme that has been applied in industry. By predicting the future system behavior in each sampling step, i.e. in a specific time interval, a very high quality of regulation is achieved. Contrary to traditional regulation schemes, input, output and state constraints can be explicitly (exploret) considered. The effect of changing the regulator parameters on the system characteristics is typically very intuitive. In order to implement a computationally expensive regulation scheme for fast electromechanical systems, schemes such as moving-Blocking for reducing optimization parameters at the prediction level or other schemes such as explicit model-predictive regulation may be used.
In the case of the model mentioned, the speed of the adjustment of the conveying means is preferably taken into account using at least one of the following parameters: a maximum possible displacement per working cycle, a minimum possible displacement per working cycle, a pressure of a medium used to operate the regulating pump, an actual value of a rotational speed of a drive, a viscosity of the medium, and a mechanical and/or electrical parameter of a regulating system of the regulating pump. The maximum possible displacement and the minimum possible displacement per working cycle may also be considered as a quotient.
These parameters usually influence the speed of the adjustment of the conveying means to different extents, that is to say how fast or slow the adjustment is carried out after a manipulation. Depending on the current speed of the adjustment of the delivery mechanism (also referred to as the wobble angular speed in the case of an axial piston pump with a wobble disk), the switching of the displacement change per operating cycle takes place faster or slower, which also has an effect on the equalization of the rotational speeds of the drive. When the displacement of each working cycle is adjusted slowly, i.e. when the dynamics or the speed are low, for example, a smaller or smaller increase in the rotational speed than when the speed is high is required.
In the model mentioned, the speed of the adjustment of the conveying means is preferably taken into account as the actual value of the model for determining the characteristic variable of the displacement per operating cycle. In particular, a rotational speed correction value (for example, an added rotational speed value) for adapting to the rotational speed target value can be determined from such a modeled actual value.
Preferably, when the target value of the characteristic variable for determining the displacement per operating cycle is changed, the target value of the rotational speed is further adapted according to at least one optimization criterion, which is selected in particular from the group consisting of: the noise generated by the regulated pump, the efficiency of the regulated pump, and the load on the drive (Auslastung). This enables further optimization of the operation, in particular when the pump is operated at partial load.
Depending on whether, for example, a swing-out or swing-in process of the control pump (or the wobble plate) is to be initiated, target trajectories for the rotational speed and the necessary change torque are expediently determined as a function of the wobble direction (i.e. in the direction of the higher or lower displacement), system parameters, further component parameters and/or the current state of the (electrohydraulic) system. At the same time, the changing hydraulic torque is then directly controlled, for example, as a function of the current pressure and the model of the change in the delivery volume of the pump.
In addition to the preliminary control of the rotational speed, it is preferably provided that, when the target value of the characteristic variable for determining the displacement volume per operating cycle is changed, the target value of the torque for the drive is also adapted by the preliminary control as a function of the dynamics or speed of the adjustment of the conveying means, in particular also as a function of the operating point. In particular, the product of the modeled actual value of the characteristic variable for determining the displacement per operating cycle and the actual pressure can be taken into account, i.e. in particular the modeled value of the hydraulic torque is pre-controlled. The above-mentioned points are then also suitable for torque pilot control. The pre-control of the torque value is particularly advantageous when the torque controller is disposed below the (indirect) rotational speed controller during operation of the electric drive.
The computing unit according to the invention, for example a control and/or regulation unit for a variable-speed control pump having a variable-speed drive, is provided in particular in terms of programming for carrying out the method according to the invention.
The invention also relates to an electrohydraulic drive system, such as, for example, an electrohydraulic shaft, comprising a variable-speed control pump having a variable-speed drive, and to a computer unit 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 executing all method steps is also advantageous, since this results in particularly low costs, in particular when the implemented controller is also used for further tasks and is therefore already present. Suitable data carriers for providing the computer program are, inter alia, magnetic memories, optical memories and electrical memories, like for example a hard disk, flash memories, EEPROMs, DVDs etc. The program may also be downloaded via a computer network (internet, intranet, etc.).
Drawings
Other advantages and design aspects of the invention will appear from the description and the accompanying drawings.
It goes without saying that the features mentioned above and those yet to be explained below can be used not only in the respectively specified combination, but also in other combinations or alone without leaving the scope of the invention.
The invention is illustrated schematically by means of embodiments in the drawings and will be described in detail below with reference to the drawings.
FIG. 1 schematically illustrates an electro-hydraulic system capable of operating in accordance with the present invention.
Fig. 2 schematically shows the sequence of the method according to the invention as a preferred embodiment of the control loop.
Fig. 3 schematically shows the process of the method according to the invention as a further preferred embodiment of the control loop.
Detailed Description
In fig. 1, an electrohydraulic system 100 is schematically illustrated, as the present invention can be based on. The electrohydraulic system 100 has an actuator in the form of a hydraulic cylinder 110 with a piston 111 that is movable along the x-axis and is actuated by a variable-speed control pump 120. A hydraulic circuit 130 with, for example, oil as a medium or working medium is arranged between the variable speed control pump 120 and the hydraulic cylinder 110.
The variable-speed control pump 120 has a variable-speed drive in the form of an electric motor 121 and a delivery mechanism 122 and is in particular an axial piston pump in the form of a wobble plate. By adjusting the angle of the wobble plate, the so-called wobble angle, the displacement of the conveying mechanism can be varied in each working cycle.
The control and/or regulating unit 140 is provided in terms of program technology for carrying out a preferred embodiment of the method according to the invention and specifies a target rotational speed value nsollAnd a target value of the rocking angle alphasollAs a target value for a characteristic quantity for determining the displacement per working cycle. For controlling the control variables, the actual values n are each setistAnd alphaistIs sent to the mobile station. This can be done, for example, using conventional sensors.
In FIG. 2, a regulation back of a method according to a preferred embodiment of the invention or according to the invention is shownThe control loop can be implemented in a control and/or regulation unit using program technology. In this case, the pressure p in the hydraulic circuit 130 is set in the (superimposed) control circuit as an exampleist(as it is shown, for example, in FIG. 1) to a target value psoll。
For this purpose, a target rotational speed value n' for the rotational speed of drive device 121 is determined or specified as a control variable by a control device, which is in this case embodied as PI control device 150sollOr nsoll(the difference between these target values will be described later) and a target value α for the rocking angle as a characteristic parameter for determining the displacement volume of each duty cyclesoll. The target values for the rotational speed and the pivot angle are then correspondingly converted in the drive 121 or the conveying device 122. The pivoting angle adjustment of the drive 121 and the transport mechanism 122 generally reacts to a target preset value as a function of the PT1 characteristic with a corresponding time constant T1 or T2. The actual value obtained here, i.e. the actual value n of the rotational speedistAnd the actual value of the wobble angle alphaistThen, a volume flow Q is determined, and then a corresponding actual value p for the pressure of the medium in the hydraulic circuit 130 is determined in the hydraulic circuit 130, taking into account the compression factor and the volume of the compressed mediumist. This is achieved by means of a hydraulic torque M to be overcomehydThe rotational speed of the drive is correspondingly influenced.
If the pivot angle or, in general, the displacement volume should now be changed within each operating cycle of the conveying means, for example for efficiency reasons, then at the same time or in parallel therewith, the adjusted current speed 165 of the conveying means is adapted by means of a predictive control to the target rotational speed value n' determined or predefined by the regulator 150sollTo obtain a (matched) target value n of the rotational speedsollAnd then continues to use the target rotational speed. This takes place, in particular, in the context of a model-predictive regulation 160 using a corresponding model (often also referred to as "digital twin" digitaltrin ") for regulating the pump.
In particular, different parameters are also taken into account here. For speed 165, for example, the maximum possible swing angle is relative to the minimum possible swingThe ratio or quotient of the angles (or the corresponding quotient of the displacements) can be used to determine a matched target rotational speed value, which in turn can be dependent on the current pivot angle, which is used here (by means of a model) as an estimate or a calculated value α ×istTo be considered.
Also the type of adjustment or adjustment system used for the swing angle affects the speed. Thus, for example, an electronic pivot angle adjustment can be provided, wherein a magnetic force is generated by means of an electric current, which magnetic force counteracts a (mechanical) spring force in the adjustment cylinder.
In this way, the rotational speed is simultaneously adapted to the pivot angle and no pressure changes are carried out in the hydraulic circuit 130, so that no intervention is required on the (upper) regulator 150. It is to be noted here that, as (upper) variable to be controlled, instead of the pressure, for example, the position x of the element or piston 111 according to fig. 1 can also be used.
In fig. 3, a control loop of a method according to another preferred embodiment of the invention or according to the invention is shown, as it can be implemented in a control and/or regulation unit in procedural terms. In this case, the pressure p in the hydraulic circuit 130 is again used as an exampleist(as it is shown, for example, in FIG. 1) to a target value psoll。
For this purpose, a target rotational speed value n for the rotational speed of the drive 121 is determined or predefined as a control variable by a controller, here likewise embodied as PI controller 150soll. By subtracting the actual value of the rotation speed n, taking into account the correction term or the pre-control term n, which will be explained lateristFrom a target value n of the rotational speedsollCalculating the error e of the rotation speednAnd the rotational speed error is supplied to a rotational speed controller 151 (likewise embodied here as a PI controller) which outputs a target torque MsollAnd affects the drive 121, which in turn is modeled with PT1 characteristics. The electrical drive torque M of the pump 120 is then generated therefromA。
Likewise, the delivery mechanism 122 is predefined with a pivot angle α as a characteristic variable for determining the displacement volume per operating cycle, the pivot angle adjustment of the delivery mechanism being modeled in turn by the PT1 characteristic, from which the pivot angle (or corresponding volume variable) α is determined.
Taking into account the hydraulic moment M to be overcomehydFrom the driving torque MATo derive the effective torque M of the pump 120effThe effective torque acts on the rotational speed. The hydraulic torque M is therebyhydAs described above, this is obtained as the product of the volume variable α and the actual pressure, which can be weighted or gained, if necessary, by the P-element.
From the speed of rotation nistThe product with the volume variable α yields a volume flow Q which can be weighted or gained by the P-element if necessary and then yields the corresponding actual pressure P in the hydraulic circuit 130, taking into account the compression factor and the volume of the compressed mediumist。
If the pivot angle α or the displacement volume should now be changed, for example for efficiency reasons, in each working cycle of the delivery mechanism, then at the same time or in parallel therewith the correction term or the precontrol term n is adapted by the precontrol to the target speed n first determined by the controller 150 or specified in advancesoll. The precontrol term Δ n is determined, in particular in the context of the model-predicted regulation 160, using a corresponding model (often also called "digital twinning") for regulating the pump (the reaction of its oscillation angle to the oscillation angle preset value α within the block 160 is modeled by the PT1 characteristic). In the present example, the modeled actual yaw angle derived therefrom is routed via the P-link for weighting or gain and is linked as an added rotational speed value Δ n to a rotational speed target value nsoll. At the same time, the multiplication of the modeled actual pivot angle (or volume) by the actual pressure is guided via the P-element and is used as the added torque value MhydIs received to the torque target value Msoll。
By means of the described modes, the effects determined in the hydraulic circuit can be taken into account in the case of a matching or variation of the transmission ratio (i.e. the pivot angle). The gain of the open-loop control loop can be changed byThe adaptation of the gain kp in the pressure controller 150 is adapted (begignen), a change in the volumetric flow Q of the medium can be adapted by adapting the rotational speed of the pump (by Δ n) and a change in the hydraulic torque can be adapted by adapting the target torque for the drive (by M)hyd) To cope with it. This can be taken into account in the mentioned models or in the regulation of the model predictions accordingly. In contrast to the example of fig. 2, the hydraulic torque is therefore additionally pre-controlled in this case.

Claims (12)

1. A method for operating a variable-speed control pump (120), in which method a delivery means (122) that can be controlled in the displacement per operating cycle is driven by means of a variable-speed drive (121), wherein, within the scope of regulation, a target speed value (n) for the speed of the drive is predefinedsoll) And a target value (alpha) of a characteristic variable for determining the displacement per working cyclesoll) Regulating at least one parameter to a target value (p)soll），
Wherein the target value (alpha) of the characteristic quantity for determining the displacement of each working cycle is changedsoll) The target rotational speed value (n) is adapted by pre-controlling the adjusted speed (165) of the conveying means (121)soll）。
2. Method according to claim 1, wherein the target rotational speed value (n) is predefined using a modelsoll) And/or adapting the target value of the rotational speed (n)soll) And/or predetermining a target value (alpha) of a characteristic variable for determining the displacement of each working cyclesoll) Taking into account in the model the speed of adjustment of the conveying means (121).
3. Method according to claim 2, wherein the target rotational speed value (n) is predefined using model-predictive regulation (160)soll) And/or adapting the target value of the rotational speed (n)soll) And/or predetermined for determining eachTarget value (alpha) of a characteristic variable of the displacement of a working cyclesoll）。
4. A method according to claim 2 or 3, wherein in the model the adjusted speed (165) of the transport mechanism (121) is taken into account using at least one of the following parameters: maximum possible displacement per working cycle, minimum possible displacement per working cycle, pressure of the medium used to operate the regulating pump, actual value of the rotational speed of the drive (n)ist) The viscosity of the medium and mechanical and/or electrical parameters of a regulating system regulating the pump (120).
5. Method according to any one of the preceding claims, wherein, within the range of modulation, modulation to the target value (p) is carried outsoll) Is selected from:
the pressure and/or volume flow of the medium used to operate the regulating pump, the force generated directly or indirectly by the medium and the position (x) of the element (111) moved directly or indirectly by the medium.
6. Method according to any one of the preceding claims, wherein the target value (α) of the characteristic quantity for determining the displacement per working cycle is variedsoll) The target rotational speed value (n) is then adapted according to at least one optimization criterionsoll) Said optimization criterion is in particular selected from: noise generated by the conditioning pump (120), efficiency of the conditioning pump (120), and load of the drive device (121).
7. Method according to any one of the preceding claims, wherein the target value (α) of the characteristic quantity for determining the displacement per working cycle is variedsoll) The target torque value (M) for the drive (121) is adjusted by pre-controlling the speed (165) of the conveyor (121) as a function of the adjustmentsoll）。
8. Method according to one of the preceding claims, in which method an axial piston pump is used as the regulating pump (120), in particular with two-point regulation or proportional regulation.
9. A computing unit (140) arranged for performing the method according to any of the preceding claims.
10. An electro-hydraulic system (100) comprising a variable-speed regulating pump (120) having a variable-speed drive (121) and a computing unit (140) according to claim 9.
11. A computer program which, when implemented on a computing unit (140), causes the computing unit (140) to perform the method according to any one of claims 1 to 8.
12. A machine-readable storage medium having stored thereon a computer program according to claim 11.
CN202011508905.1A 2019-12-20 2020-12-18 Method for operating a variable speed variable displacement pump Pending CN113007055A (en)

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