HYDRAULIC SYSTEM AND METHOD FOR ADJUSTING A HYDRAULIC SYSTEM - Patent application

Abstract

The present invention provides a hydraulic device for the supply of at least one working unit, in particular in a plastic injection molding machine, which is improved in terms of functionality, energy, efficiency and economy. A hydraulic system for supplying a number of working units (3a, 3b), in particular in a plastic injection molding machine, comprises at least one control device (7), at least one valve adjustment and / or valve control device and a central drive (1). At least one of the working units (3a, 3b) is provided with a regulating valve (13a, 13b) having a regulating valve geometry. A number of pressure sensors (8) respectively detect at least one pressure before and after the regulating valve (13a, 13b), a load pressure (10a, 10b) of at least one of the working units (3a, 3b) and a system pressure (9). The hydraulic system is improved in terms of functionality, energy, efficiency and economy by virtue of the valve regulating and / or valve control having information about the regulating valve geometry of the at least one regulating valve (13a, 13b) and being configured to derive at least one actual volumetric flow rate value for each regulating valve (13a, 13b) from a relationship between the regulating valve geometry and at least one pressure difference resulting from the pressures detected before and after the regulating valve (13a, 13b), and by virtue of the control device (7) performing at least one pre-setpoint control for the central drive (1) from a volumetric flow rate setpoint value of at least one of the operating units (3a, 3b) and / or from the volumetric flow rate actual value of the at least one regulating valve (13a, 13b) in such a way that the system pressure (9) corresponds to at least the respectively highest load pressure (10a, 10b) of the operating units (3a, 3b).

Description

[Technical field]

[0001] (Related Applications) This application is related to and claims priority from German patent application No. 10 2021 104 398.0, filed on February 24, 2021, the disclosure content of which is hereby expressly incorporated in its entirety into this application.

[0002] FIELD OF THEINVENTION The invention relates to a hydraulic device for the supply of at least one working unit, in particular in a plastic injection molding machine, having the features of the preamble of claim 1 as well as to a method for controlling and / or regulating the hydraulic device having the features of the preamble of claim 9. [Background technology]

[0003] (Prior Art) Even in modern, for example electromechanically driven injection molding machines, hydraulic consumers or axes, such as ejectors, nozzle abutment functions, core pullers (core tensioning devices), closing nozzles, are still present and can be supplied with energy by the injection molding machine. On the one hand, for certain machine axes that operate most of the time only in force-regulated operation, such as for example in the nozzle abutment function, electromechanical drives are not proven for service life reasons, and on the other hand, especially in the tool area, hydraulic actuators offer significant structural and economic advantages due to their high power density and low installation effort. Likewise, for reasons of compatibility of new machines with existing tools, new machines that are electromechanically driven and operate in an energy-optimized manner also require an integrated hydraulic power supply.

[0004] DE 10 2009 020 111 A1 discloses a hydrostatic drive system with a load-sensing regulated pump and at least one consumer that can be controlled by means of a control valve. To regulate the pump's delivery volume, an electronic pressure difference regulation is provided, where a sensor device for detection forms a pressure difference between the (highest) load pressure of the consumers and the delivery pressure of the pump, whereby the control device regulates the pump in such a way that this pressure difference corresponds to a preset regulation difference. A preset (i.e. fixed) regulation pressure difference is thereby regulated between the load pressure (preferably the highest load pressure) and the delivery pressure of the pump. The input pressure, and thus the pressure difference at the regulating valve for the second or further consumer, is thereby dependent on the load pressure of the first or leading consumer and therefore cannot be kept constant. The volumetric flow rate of the second or further consumer is therefore not proportional to the opening cross section of the valve and therefore is not specified. This means that either a pressure compensator (pressure equalizer) is required for each regulating valve of the non-leading consumer, or the consumer needs feedback on the magnitude of the corresponding volume flow in order to distribute the volume flow to several consumers according to demand. It is not clear how the distribution of the volume flow according to demand is carried out. Only the sum of the volume flows should correspond to the demand of all consumers, so that the leading pressure difference (which collapses in the case of undersupply) is maintained.

[0005] DE 10 2015 201 318 A1 discloses a hydraulic control device for the pressure means supply of at least two hydraulic consumers. An adjustable hydropump can be changed in such a way that the pump pressure is above the highest load pressure of the simultaneously controlled hydraulic consumer by a predefined pump pressure difference. For this purpose, a pressure compensator is used for each regulating valve. The pump regulator is controlled in such a way that the different pressure drops in the pump lines are taken into account within the magnitude of the pump pressure difference and the individual pressure compensator assigned to the hydraulic consumer with the highest load pressure is at least approximately fully opened at different pressure drops in the pump lines.

[0006] EP 0 649 722 B2 discloses a hydraulic device for the supply of a working unit in a plastic injection molding machine with at least one consumer. With the aid of a pressure sensor, the actual pressure value is detected and compared with the pressure setpoint, thereby providing a setpoint for a regulating element of a regulating pump for additionally controlling the operating pressure gradient as load sensing. The maximum power of the regulating pump is preset by a frequency converter on the basis of a preset value for the respective injection cycle and depending on a further setpoint that is dependent on volume and pressure, the pump power of the regulating pump being actively adjustable below its maximum power via a first setpoint at the regulating element by a control device.

[0007] DE 196 80 008 C1 discloses an apparatus with at least one controlled hydraulically driven actuator, a hydraulic pump and a control / regulation device which acts on the electrical drive of the hydraulic pump on the basis of detected actuator data, the hydraulic pump being connected to the actuator by means of a defined line and without dissipative setting elements, i.e. without regulating valves, but without load exchange of the hydraulic pump.

[0008] DE 10 2011 012 714 A1 discloses a hydraulic drive unit for an injection molding machine, in which the flow volume of hydraulic liquid per time unit is measured with the aid of a measuring device and transmitted as a corresponding signal to a control or regulating unit, which calculates the position of the piston from said signal. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] German Patent Application Publication No. 102009020111 [Patent Document 2] German Patent Application Publication No. 102015201318 [Patent Document 3] European Patent No. 0649722 [Patent Document 4] German Patent Invention No. 19680008 [Patent Document 5] German Patent Application Publication No. 102011012714 Summary of the Invention [Problem to be solved by the invention]

[0010] In the existing further prior art, there are in fact essentially two basic variants of hydraulic power supplies integrated into injection molding machines.

[0011] A first variant for a purely serial core puller or countershaft function is realized using so-called servo-electrically regulated constant pumps and simple shaft-actuated valves. Several shafts can thus be operated in tandem and in a demand-adapted, energy-optimized manner by a pump-servomotor-drive unit adapted to the shaft consumers. Furthermore, hydraulic systems are known from the prior art in which several consumers or shafts are supplied simultaneously by the same pressure or volumetric flow source. The volumetric flow of the source is distributed to the several consumers. The static distribution takes place, for example, by means of so-called flow distribution valves or internal gear flow dividers.

[0012] The second variant, for example for high-power machines with simultaneous high dynamic demands on the hydraulic power supply, is often realized with a constant pressure supply, via several hydraulic accumulators (or large capacity-determined constant pressure pumps) and flow-pressure-regulating valves at the individual consumers. If the supply source has to provide pressure and volume flow on demand, special demands arise for the dynamic distribution of the volume flow: a system pressure / accumulator pressure with a high reserve is provided to avoid the axial movements or axial forces being influenced when several axes are connected in parallel. This leads to a correspondingly energetically unfavorable behavior, since the unnecessary power, calculated from the required amount multiplied by the excess pressure in the regulating valve, has to be converted as heat into the carrier medium. As injection molding machines are generally purchased, the second variant is not in a position to run the energetically optimal cycle corresponding to the first variant with tools with exclusively sequential movements, and vice versa, the first variant cannot operate tools with simultaneous core puller movements. Dynamic distribution can be achieved, for example, by means of proportional flow regulating valves, each of which is assigned to one consumer.

[0013] There are also other configurations in the prior art in which multiple servo pumps of the first variant are installed or provided as required. However, these configurations have significant commercial drawbacks, and the overall energy balance at a given operating point requirement is in part energetically inferior to a constant pressure system (frequent power changes, frequent starts and stops of the drives, high demands on the pressure maintenance function). These configurations are also very limited in terms of their flexibility, because the countershaft synchronicity specifications are permanently fixed in the machine design.

[0014] The known solutions of the prior art result in the consumers in influencing one another to a great extent, which is application-relevant and therefore also impairs the quality of the injection-molded parts to be produced.

[0015] (Summary of the invention) Based on this prior art, the problem underlying the present invention is to provide a hydraulic device for the supply of at least one working unit, in particular in a plastic injection molding machine, which is improved in terms of functionality, energy, efficiency and economy. [Means for solving the problem]

[0016] The problem is solved by a hydraulic device having the features of claim 1 as well as by a method having the features of claim 9.

[0017] Advantageous further configurations are the subject of the dependent patent claims. The features recited individually in the patent claims can be combined with one another in a technically meaningful manner and can be supplemented by what is described in the present specification and by details from the drawings, which show further implementation variations of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, a mode for carrying out the invention will be described.

[0019] In particular in plastic injection molding machines for processing plastics and other plasticizable materials, the hydraulic device for the supply of several working units comprises at least one control device, at least one valve regulation (valve regulation device: valve closed loop control device) and / or valve control (valve control device: valve open loop control device) and a central drive. The control device can comprise the valve regulation and / or the valve control, or the valve regulation and / or the valve control can comprise the control device. For each working unit, at least one regulating valve with a regulating valve geometry (structural shape of the regulating valve: for example a spool geometry), preferably an electronic and / or digital regulating valve, is provided. The regulating valve can be configured, for example, as a continuous valve (continuously adjustable valve) or as a proportional valve for regulating the volumetric flow rate to the working unit. Furthermore, several pressure sensors, for example pressure recorders, are provided, which for each regulating valve respectively detect at least one pressure before and after the regulating valve, the load pressure of the working unit and the system pressure. Basically, it is also possible that only one of the operating units is equipped with a regulating valve, whereas the remaining operating units are actuated, for example, by means of a switching valve. At least one digital regulating valve, preferably with a spool geometry and with an integrated valve regulating and / or valve control, can be provided for each operating unit. The regulating valve can be configured, for example, as a continuous valve, which regulates the volumetric flow rate to the operating unit.

[0020] Advantageously, in order to achieve an improvement over the solutions existing in the prior art in terms of functionality, energy, efficiency and economy, the valve regulating and / or valve control has information about the regulating valve geometry of the regulating valves, such as the geometry of the valve spool, for example as a control characteristic curve, a volume flow-signal characteristic curve or a function "opening cross section = f (stroke Hub)", and is configured to derive at least one actual volume flow value for each regulating valve from a relationship between the regulating valve geometry and at least one pressure difference resulting from the pressures sensed before and after the at least one regulating valve. The control device has an arrangement for performing at least one setpoint pre-control (setpoint pre-control Sollwertvorsteuerung) for the central drive from at least one volume flow setpoint of the working unit or from volume flow setpoints of several working units and / or from the volume flow actual value of the at least one regulating valve, such that the system pressure corresponds at least to the highest load pressure of the at least one working unit. (Regarding precontrol: With precontrol, values ​​are preset, which provide a starting point or a reference for the adjustment range to be expected for further adjustment.) In this context, the system pressure at least corresponds to the highest load pressure means that the system pressure is greater than or equal to the load pressure and can also exceed the load pressure, for example by a predefined value, i.e. advantageously, one or more pressure compensators, for example, are not required.

[0021] The values ​​can be preset, for example, manually and / or automatically, for example by a control device. The values ​​can also be preset depending on the parameters of the injection molding process. The information can be present, for example as algorithms, functions and / or control characteristic curves, in an electronic and / or digital storage device. In principle, it is also conceivable that the information is already present in the valve adjustment and / or valve control device and is entered manually or provided automatically, for example via a network connection.

[0022] Preferably, for each regulating valve, a corresponding volumetric flow rate, preferably a corresponding normalized volumetric flow rate, for example in l / min (liters per minute), is obtained from the determined pressure difference and the determined setting state of the valve. This means that with the regulating valve, a normalized setting command and / or a through flow rate of the operating unit can preferably be set independently of the system pressure and / or the load pressure of the operating unit. This further advantageously eliminates the need for a new setting of the regulating valve, so that compensation (adjustment) tasks during maintenance are eliminated.

[0023] For example, two types of valves are used, where the first valve has a nominal maximum volumetric flow rate of, for example, 180 l / min and the second valve has a nominal maximum volumetric flow rate of, for example, 140 l / min. In the linearized characteristic curve, in this example, assuming sufficient supply pressure, the first valve is regulated to a volumetric flow rate of 90 l / min at a setpoint (operating variable) of 50% and the second valve is regulated to a volumetric flow rate of 70 l / min at a setpoint (operating variable) of 50%.

[0024] In this context, normed (or standardized) means that for a normalized volume flow rate and / or normalized through flow rate, if a setpoint value preset for the volume flow rate and / or through flow rate is, for example, 80 l / min, both valves are adjusted to such a volume flow rate of 80 l / min, independent of pressure fluctuations and independent of the nominal maximum volume flow rate. This means that a normalized through flow rate depending on the setpoint (operating variable) or a normalized volume flow rate independent of the load pressure and the system pressure is obtained. As a result, preferably, no new adjustment / control units have to be implemented, for example, when using different valves or when replacing other system components.

[0025] Furthermore, normalization may be performed for values ​​(quantities) that are fundamentally different from the volumetric flow rate or the through-flow rate, provided that the scaled and correspondingly assigned values ​​(quantities) can be set in a normalized manner via a setting command.

[0026] In this context, a normalized set command is a command with which, for example, a normalized volume flow rate and / or a normalized through-flow rate can be set, for example, the value to be normalized can be expressed (normalized) as a volume flow rate, for example in l / min (liters per minute), so that the desired volume flow rate can be set or adjusted, for example by means of a predefined characteristic curve, independently of the valve used (system pressure and load pressure).

[0027] Advantageously, precontrol based on the actual volume flow rate can also carry out appropriate precontrol when the regulating valve is in a pressure regulation state and therefore its volume flow rate does not depend (only) on the volume flow rate setpoint.

[0028] The regulating valve can thus advantageously regulate the physically normalized throughflow rate in the operating unit according to a preset setpoint value, independent of the system pressure and the load pressure, and in the quasi-static case of pressure regulation, can perform the pressure maintenance function independent of fluctuations in the system pressure. Of course, this is only valid insofar as the hydrodynamic assumptions for compensating for losses through the valve are given by the corresponding delta p as the pressure difference between the system pressure and the load pressure.

[0029] Advantageously, therefore, no more volume flow and / or pressure is provided than exactly required for the sum of the operating units in terms of functionality, energy, efficiency and economy, for which the volume flow and / or pressure of the central drive is distributed to the multiple operating units, whereby advantageously the action (influence) of the operating units on one another is limited to a minimum and it is always possible to adjust and / or limit the volume flow and / or pressure of each operating unit independently of the other operating units.

[0030] Typically, the use of such regulating valves and corresponding controls advantageously provides much faster adjustability and dynamic response of the total pressure supply.

[0031] For example, for at least two simultaneous working unit movements that are not influenced by one another, an optimal system pressure is realized, which is realized by superposition using a central drive, i.e. the superposition corresponds to the maximum pressure demand of at least two simultaneously operable working units and is achieved by corresponding drive control of the central drive using a control device having a system-related appropriate adjustment function for quantity (motor speed) and system pressure.

[0032] Preferably, one regulating valve is assigned to each of the multiple operating units, which advantageously allows accurate and precise pre-setpoint control to be achieved for all operating units even when multiple operating units are moving simultaneously, which contributes to the quality of the injection-molded parts to be produced.

[0033] Preferably, the valve adjustment and / or valve control has information about the hydraulic medium used, so that preferably an accurate and precise pre-setpoint control is obtained. For example in the gap of the valve spool, viscosity plays an important role for laminar flows, which in application affects the volume flow rate near the zero point (overlap edge). The valve adjustment and / or valve control preferably knows (as information) the exact relationship between the pressure or pressure difference, the setting of the regulating valve and the setting of the volume flow rate, depending on the hydraulic medium used.

[0034] The distribution of hydraulic medium, for example in injection molding machines, to the operating units is often realized via compressible volumes, for example via hoses, whereby a certain hydraulic storage effect or hydraulic capacity assists the system. A direct load jump, for example due to a collision, is directed to one operating unit, and the regulating dynamics in the second operating unit do not even affect the operating unit to be controlled. Similarly in real installations, the always-present compressible dead volume of the central drive and control unit allows the pressure / volume response to the direct observation of the system pressure in the pressure supply, which can be lowered (including reduction from a higher level to a lower level, stop) or raised (including increase or rise from a lower level to a higher level, start) in time and energy-efficiently in the volumetric conveying, with slower dynamics than a regulating valve.

[0035] Advantageously, for improved modularity in the plant design, the valve adjustment and / or valve control are preferably arranged in or attached to the regulating valve. As a result, the regulating valve advantageously "knows" itself, so that no calibration is required when replacing the regulating valve. In principle, however, it is also possible for the valve adjustment and / or valve control to be arranged elsewhere, for example in or attached to the control device. It is also conceivable that the control device is or includes the valve adjustment and / or valve control.

[0036] Preferably, at least one temperature sensor, for example a temperature recorder (device), is provided, which advantageously allows a precise prediction of the viscosity of the hydraulic medium to be carried out and thus a more accurate throughflow rate to be obtained.Furthermore, preferably, at least one temperature sensor is provided for each regulating valve, which advantageously allows a more accurate determination of the viscosity for each working unit branch.

[0037] Since injection molding machines are often constructed individually and modularly, it is also advantageous to provide an increased modularity in the plant construction, preferably with a pressure sensor in or attached to the regulating valve. If the valve is replaced, for example, due to a retrofit, it is advantageously not necessary to carry out further retrofit measures.

[0038] In principle, but preferably, each regulating valve can have a pressure sensor, a temperature sensor and / or a valve adjustment and / or a valve control.

[0039] Preferably, the regulating valve geometry (constructive geometry of the regulating valve) of the regulating valve relates to the spool geometry of the valve spool, whereby knowledge of this geometry advantageously enables a reliable, economical and energy-efficient regulation of the volume flow rate, e.g. in the sense of the delivery flow distribution.

[0040] The problem is further solved by a method having the features of claim 9. In order to improve the solutions existing in the prior art with regard to functionality, energy, efficiency and economy, in particular in a plastic injection molding machine with at least one control device and a central drive, for example a pump, at least one of the operating units is provided with at least one regulating valve for controlling and / or regulating a hydraulic device for the supply of a plurality of operating units, wherein at least one pressure difference is determined for each regulating valve from at least one detected pressure respectively before and after the regulating valve, at least one actual volumetric flow rate value is derived for each regulating valve from the relationship between the regulating valve geometry and the pressure difference of the regulating valve, and at least one setpoint pre-control for the central drive is carried out from the volumetric flow rate setpoint value of the at least one operating unit and / or the volumetric flow rate actual value of the at least one regulating valve in such a way that the system pressure corresponds at least to the highest load pressure of the operating unit. In this context, the system pressure at least corresponds to the highest load pressure means that the system pressure is greater than or equal to that load pressure and may also exceed that load pressure, for example by a predetermined value.

[0041] Preferably, by means of at least one regulating valve, the normalized set command and / or the throughflow and / or the volume flow of the operating unit is set independently of the system pressure and / or the load pressure of the at least one operating unit, so that, for example, a desired volume flow can be advantageously set or adjusted according to a predefined characteristic curve, i.e., a normalized throughflow or volume flow is obtained depending on, for example, a set quantity (operating quantity).

[0042] Preferably, each regulating valve controls the pressure of each of the multiple operating units, which advantageously allows accurate and precise pre-setpoint control to be achieved for all operating units even when multiple operating units are moving simultaneously, which contributes to the quality of the injection-molded parts to be produced.

[0043] For the advantageously rapid adjustability and precise provision of the throughflow rate, the pre-setpoint control is preferably time-controlled and / or in real time. For example, the pre-setpoint control is time-controlled (harmonized) with the operating unit based on the volume flow rate setpoint of the operating unit and / or in real time based on the volume flow rate actual value of the regulating valve. In this context, time-controlled (harmonized) means that a volume flow rate setpoint is provided for the operating unit at a given time point by means of the pre-setpoint control. For example, the pre-setpoint control is based on the volume flow rate actual value in real time and can advantageously provide an appropriate pre-setpoint control even when the control valve is in a pressure regulation state and therefore its volume flow rate does not depend (only) on the volume flow rate setpoint.

[0044] In order to advantageously detect a leakage in the working unit, a periodic integration of the normalized volume flow regulated by the regulating valve is preferably carried out over at least one working unit cycle, in which case the presence or absence of a leakage is detected, for example, in comparison with the previous working unit cycle.

[0045] To advantageously detect wear in the valve mechanism, e.g. wear on the control edge or in the case of leakage through the piston, the actual volume flow rate of the regulating valve is preferably continuously monitored, evaluated and correlated with the actual volume flow rate during at least one periodic machine run, so that, for example, a comparison with previous work unit cycles can be made and a wear state can be derived.

[0046] Advantageously for an energy-optimized operation, as well as for improvements in the application of simultaneous requirements or for increased requirements on dynamics and reproducibility, preferably at least one regulating valve is operated as a changeover valve in the serial movement of at least one operating unit and / or at least one regulating valve is operated as a load-sensing regulating valve in the simultaneous movement of several operating units. Thus, advantageously, several operating units can be operated directly in the injection molding cycle using a control device and a central drive. For example, the regulating valve is switched by the control device as a changeover valve to the maximum throughflow or closed. Due to the absence of a hydromechanical pressure compensator, it is therefore possible to achieve in the serial operation approximately the same energy efficiency as a purely serial pump system with connecting valves for the operating units.

[0047] For advantageous optimization of the dynamics and energy consumption per cycle, the implementation of the pre-setpoint control is preferably adapted in a self-optimizing manner using a periodically learning observer. For example, the pressure superposition in the system circuit can be adapted in a self-optimizing manner to an optimal state of dynamics and energy consumption per cycle using a periodically learning observer under the observation of the regulation quality in the working unit circuit, in particular under the observation of pressure overshoots / undershoots occurring in the working unit circuit.

[0048] Preferably, in order to carry out real-time or periodic condition monitoring of the central drive, the peripherals and the working units, the control device can configure one or more observers, e.g. digital observers, in real time, for repetitive periodic movements in continuous operation, which advantageously allows very precise detection of the leakage rate.

[0049] Further advantages are evident from the subclaims and from the following description of preferred embodiments. The features recited individually in the claims can be combined with one another in a technically meaningful manner and can be supplemented by the contents described in the specification and by details from the drawings, which show further implementation variations of the invention.

[0050] The invention will now be described in detail with reference to a number of embodiments thereof as illustrated in the accompanying drawings. [Brief description of the drawings]

[0051] [Figure 1] FIG. 1 shows a monohydraulic device with two working units. [Diagram 2] FIG. 2 shows a hydraulic device corresponding to FIG. 1 with two regulating valves. [Diagram 3] FIG. 2 shows a hydraulic device corresponding to FIG. 1 with one regulating valve. [Figure 4a] FIG. 1 shows a graph of volumetric flow rate versus time for two working units without pre-control according to the prior art. [Figure 4b] FIG. 4b shows a graph corresponding to FIG. 4a with pre-control. [Diagram 5] FIG. 1 shows a schematic method chart. EXAMPLES

[0052] Description of the Preferred Embodiments The present invention will now be described in detail using examples in conjunction with the accompanying drawings. However, these examples are merely illustrative and should not be construed as limiting the concept of the invention to a specific device. Before describing the present invention in detail, it is pointed out that the present invention is not limited to each component of the device and each method step of the method, because these components and methods can be modified. Furthermore, the concepts or terms used herein are defined only to describe specific embodiments and are not used as limitations. In addition, when the singular or indefinite article is used in the present specification or claims, the elements may be in the plural unless the overall context clearly indicates otherwise (correspondingly, the singular also represents the plural in Japanese translations).

[0053] In Fig. 1, a hydraulic unit for the supply of several working units, in this embodiment two working units 3a, 3b, such as ejectors, nozzles, core pullers or closing nozzles, is shown, in particular in a plastic injection molding machine, with at least one control device 7, at least one valve regulation device (valve closed loop control device) and / or valve control device (valve open loop control device) and a central drive 1. The control device 7 can comprise the valve regulation device and / or the valve control device, or the valve regulation device and / or the valve control device can comprise the control device 7. Such plastic injection molding machines are used for processing plastics and other plasticizable materials, such as ceramic, metallic and / or powdery materials.

[0054] The central drive 1 can have a pump 4, for example a constant pump (metering pump), a motor 5, for example a servomotor, and a motor control 6, as shown in Fig. 1. In principle, however, it is also possible for further operating units 3a, 3b to be provided. In Fig. 1, each operating unit 3a, 3b is provided with a respective switching valve 12a, 12b and a respective regulating valve 2a, 2b. The regulating valves 2a, 2b in the exemplary embodiment of Fig. 1 are, for example, configured as electronic and / or digital flow regulating valves, p / Q valves with electrical pressure compensation, proportional valves or continuous valves (continuously adjustable valves), which regulate the volumetric flow rates to the operating units 3a, 3b.

[0055] A number of pressure sensors 8 detect for each regulating valve 2a, 2b at least one pressure before and after the corresponding regulating valve 2a, 2b, the load pressures 10a, 10b of the working units 3a, 3b and the system pressure 9. These pressures can be transmitted to the control device 7 and / or the valve adjustment and / or the valve control, preferably via a connection 21, for example a bus. In principle, however, other connections 21, for example wireless networks, are also conceivable. Via the connections 21, the regulating valves 2a, 2b are preferably in connection with the control device 7 and the central drive 1 and / or the valve adjustment and / or the valve control.

[0056] The valve adjusting and / or valve control has information about the regulating valve geometry (constructive geometry of the regulating valve) of the regulating valves 2a, 2b. This information can be provided, for example, as a control characteristic curve, a volume flow-signal characteristic curve or a function "opening cross-section=f(strokeHub)" or also in the form of the geometry of the valve spool. In principle, it is also conceivable that this information is already present in the valve adjusting and / or valve control and is entered manually or provided automatically, for example via a network connection. The valve adjusting and / or valve control is configured to derive at least one actual volume flow value for each regulating valve 2a, 2b from a relationship between the regulating valve geometry and at least one pressure difference resulting from the pressure sensed before and after the at least one regulating valve.

[0057] In FIG. 3, only one p / Q valve as regulating valve 2a, one switching valve 12a and additionally one switching valve 12b are provided in the central drive train for purely serial movement, but in principle several regulating valves are usually provided.

[0058] The device according to the invention and the method according to the invention can also be used advantageously if not all of the operating units are equipped with an adjusting valve, or in FIG. 3, only one of the operating units is equipped with an adjusting valve. One of the operating units can be supplied (hydraulic or fluid) via a switching valve, for example. This operating unit can be, for example, the operating unit of a closing nozzle, but the switching process systematically affects the other operating units. If, for example, this operating unit is in pressure maintenance mode, the precontrol requires a minimum pressure for this simultaneous operation.

[0059] The valve adjustment and / or valve control unit knows the exact relationship between pressure and the setting state of the regulating valve 2a, 2b, so that the valve adjustment and / or valve control unit has the information which pressure is associated with which setting state of the regulating valve or which setting state of the regulating valve is associated with which pressure.

[0060] 1, the regulating valves 2a, 2b are configured as electronic and / or digital proportional valves, having a valve adjustment and / or valve control unit and information about the regulating valve geometry of the regulating valves 2a, 2b, including the valve spool geometry. The regulating valves 2a, 2b derive an actual volumetric flow rate, preferably a normalized actual volumetric flow rate, from the relationship between the regulating valve geometry and the pressure difference and transmit this actual volumetric flow rate to the control device 7.

[0061] The control device 7 is arranged to derive at least one setpoint pre-control for the central drive 1 from the volumetric flow setpoints of the working units 3a, 3b and / or the volumetric flow actuals of the regulating valves 2a, 2b in such a way that the system pressure 9 corresponds to at least the highest load pressure of the working units 3a, 3b, i.e. the system pressure can be the same as the load pressure or higher by a predefined value than the load pressure.

[0062] Thus, the at least one regulating valve 2a, 2b can regulate a physically normalized throughflow rate, for example in l / min (liters per minute), in the operating units 3a, 3b, corresponding to a preset desired value and independent of the system pressure 9 and the load pressure 10a, 10b, and in the case of a quasi-static pressure regulation state, can perform a pressure maintenance function independent of fluctuations in the system pressure. Of course, this is only valid insofar as the hydrodynamic prerequisites for compensating losses through the valve are given by the corresponding delta p as the pressure difference between the system pressure 9 and the load pressure 10a, 10b. Thus, by means of the at least one regulating valve 2a, 2b, the normalized set command and / or the normalized throughflow rate and / or the normalized volumetric flow rate of the operating units 3a, 3b are set independent of the system pressure 9 and / or the load pressure of the at least one operating unit.

[0063] This will be explained in more detail with an example.

[0064] For example, two types of valves are used, where the first valve has a nominal maximum volumetric flow rate of, for example, 180 l / min and the second valve has a nominal maximum volumetric flow rate of, for example, 140 l / min. With the linearized characteristic curve, in this example, the first valve is adjusted to a volumetric flow rate of 90 l / min at a setpoint (operating variable) of 50% and the second valve is adjusted to a volumetric flow rate of 70 l / min at a setpoint (operating variable) of 50%, assuming sufficient supply pressure.

[0065] In this context, normed (or standardized) means that for a normalized volume flow rate and / or normalized through flow rate, if a setpoint value preset for the volume flow rate and / or through flow rate is, for example, 80 l / min, both valves are adjusted to such a volume flow rate of 80 l / min, independent of pressure fluctuations and independent of the nominal maximum volume flow rate. This means that a normalized through flow rate depending on the setpoint (operating variable) or a normalized volume flow rate independent of the load pressure and the system pressure is obtained. As a result, preferably, no new adjustment / control units have to be implemented, for example, when using different valves or when replacing other system components.

[0066] Furthermore, normalization may be performed for values ​​(quantities) that are fundamentally different from the volumetric flow rate or the through-flow rate, provided that the scaled and correspondingly assigned values ​​(quantities) can be set in a normalized manner via a setting command.

[0067] In this context, a normalized set command is a command with which, for example, a normalized volume flow rate and / or a normalized through-flow rate can be set, for example, the value to be normalized can be expressed (normalized) as a volume flow rate, for example in l / min (liters per minute), so that the desired volume flow rate can be set or adjusted, for example by means of a predefined characteristic curve, independently of the valve used (system pressure and load pressure).

[0068] In a further preferred embodiment, the valve adjustment and / or valve control has information about the hydraulic medium used, such as its viscosity, so that depending on the medium used, a corresponding pressure and a corresponding valve setting are obtained, which advantageously results in a more accurate pre-control.

[0069] In order to advantageously avoid the need for a new calibration when replacing the regulating valve 2a, 2b, 13a, 13b, in another preferred embodiment the valve adjustment and / or valve control is provided in or attached to the regulating valve 2a, 2b, 13a, 13b.

[0070] In a further preferred embodiment, at least one temperature sensor is provided, more preferably at least one temperature sensor, for example a temperature recorder, for each regulating valve 2a, 2b, 13a, 13b. Advantageously, measuring the temperature of the hydraulic medium allows for a more accurate prediction of the viscosity and thus a more accurate throughflow rate.

[0071] In a further preferred embodiment, the pressure sensor 8 is provided in or attached to the regulating valve 2a, 2b, 13a, 13b, which provides advantages in the case of machine retrofitting, i.e. no special retrofitting has to be carried out.

[0072] The embodiment of Fig. 2 substantially corresponds to the embodiment of Fig. 1, but in Fig. 2 the switching valves 12a, 12b are not provided. The regulating valves 13a, 13b of Fig. 2 are configured there, for example, as continuous valves with a directing function (continuously adjustable valves).

[0073] The embodiment of Fig. 3 corresponds substantially to the embodiment of Fig. 1, but in Fig. 3 only one p / Q valve as regulating valve 2a and one switching valve 12a and additionally one switching valve 12b are provided in the central drive train for purely serial movement, so that in this case only one regulating valve 2a is assigned to one working unit 3a.

[0074] In FIG. 4a, the throughflow in cubic meters per second is plotted against time in seconds for two working units 3a, 3b without precontrol according to the prior art. First, the first working unit 3a accelerates with a high load pressure until at time point E1 the second working unit 3b accelerates with a lower load pressure. The acceleration of the second working unit 3b also leads to a diagrammatically exaggerated bend in the throughflow of the first working unit 3a, since the second working unit 3b also requires a corresponding throughflow. At time E2 the first working unit 3a slows down, so that the first working unit 3a requires a smaller throughflow, which can be seen as an "overshoot" in the second working unit 3b. The two working units 3a, 3b therefore act strongly (against) each other, which leads to errors in the working process and to errors in the quality of the injection-molded parts.

[0075] In Fig. 4b a graph similar to Fig. 4a is shown, but with pre-setpoint control of the central drive 1 by the control device 7. It can be seen that at the time points E1 and E2 the two working units 3a, 3b have less mutual influence.

[0076] 5 shows a schematic block diagram of a method for controlling and / or regulating a hydraulic system for the supply of several operating units 3a, 3b, in particular in a plastic injection molding machine with at least one control device 7 and a central drive 1, where at least one, preferably all, of the operating units 3a, 3b are each provided with at least one regulating valve 2a, 2b, 13a, 13b. In step 50, at least one pressure difference is determined for each regulating valve 2a, 2b, 13a, 13b from at least one detected pressure respectively across the regulating valve 2a, 2b, 13a, 13b. In a further step 51, at least one actual volumetric flow rate value is derived for each regulating valve 2a, 2b, 13a, 13b from the relationship between the regulating valve geometry and the pressure difference across the regulating valve 2a, 2b, 13a, 13b. In step 52, from the volume flow setpoint value of the at least one operating unit 3a, 3b and / or the volume flow actual value of the regulating valve 2a, 2b, 13a, 13b, at least one setpoint precontrol for the central drive 1 is performed in such a way that the system pressure 9 corresponds to the highest load pressure 10a, 10b of at least one operating unit 3a, 3b and / or exceeds this highest load pressure by a predefined value, which value can for example be entered manually or be provided automatically, for example via a network.

[0077] In a preferred embodiment, the pre-setpoint control is time-controlled and / or occurs in real time.

[0078] To advantageously detect the amount of leakage, in a further preferred embodiment, a periodic integration of the normalized volume flow regulated by the regulating valves 2a, 2b, 13a, 13b is performed over at least one working unit cycle, which detects whether more hydraulic medium has been used, which can indicate the amount of leakage.

[0079] In a further preferred embodiment, in order to advantageously detect wear in the valve mechanism, e.g. wear in the control edges or in the valve mechanism in the case of leakage through the pistons, the actual volume flow values ​​of the regulating valves 2a, 2b, 13a, 13b are continuously monitored, evaluated and correlated with at least one periodic actual volume flow value during machine operation.

[0080] In a preferred embodiment, the regulating valves 2a, 2b, 13a, 13b are operated as switching valves 12a, 12b to perform serial movement of the working units 3a, 3b and / or as load sensing regulating valves to perform simultaneous movement of the working units 3a, 3b.

[0081] In a further preferred embodiment, the calculation of the pre-setpoint control is adapted in a self-optimizing manner using a periodically learning observer, by means of which an optimal state of dynamics and energy consumption / cycle can advantageously be obtained, i.e. the pressure superposition in the system circuit can be adapted in a self-optimizing manner under observation of the regulation quality in the working unit circuit, in particular under observation of pressure overshoots / undershoots occurring in the working unit circuit.

[0082] Obviously, the teachings herein are susceptible to considerable variation, modification, and adaptation, provided they fall within the scope and range of equivalents of the appended claims. [Explanation of symbols]

[0083] 1 Central Drive Unit 2a Adjustment valve 2b Adjustment valve 3a Unit of Work 3b Unit of Work 4. Pump 5 Motor 6 Motor control unit 7 Control device 8. Pressure Sensors 9 System Pressure 10a Load pressure 10b Load pressure 11 Volume flow rate / Volume flow 12a Switching valve 12b Switching valve 13a Adjustment valve 13b Adjustment valve 20 Dead Volume 21 Connection section (connection system) 50 steps 51 Steps 52 Steps

Claims

1. A hydraulic device for the supply of a number of working units (3a, 3b) comprising at least one control device (7), at least one valve adjustment and / or valve control and a central drive (1), at least one of said working units (3a, 3b) is assigned at least one regulating valve (2a, 2b, 13a, 13b) having a regulating valve geometry and is provided with a number of pressure sensors (8), said pressure sensors (8) being configured for each said regulating valve (2a, 2b, 13a, 13b) to sense at least one pressure before and after said regulating valve (2a, 2b, 13a, 13b), a load pressure (10a, 10b) of said working unit (3a, 3b) and a system pressure (9), the valve regulating unit and / or the valve control unit have information about the regulating valve geometry of the regulating valves (2a, 2b, 13a, 13b) and are configured to derive at least one actual volumetric flow rate value for each regulating valve (2a, 2b, 13a, 13b) from a relationship between the regulating valve geometry and at least one pressure difference resulting from pressures sensed before and after the regulating valves (2a, 2b, 13a, 13b), the control device (7) is adapted to carry out at least one pre-setpoint control for the central drive (1) from a volumetric flow setpoint of at least one of the working units (3a, 3b) and from at least one actual volumetric flow value of at least one of the regulating valves (2a, 2b, 13a, 13b) in such a way that the system pressure (9) corresponds to at least the highest load pressure (10a, 10b) of the working units (3a, 3b), by means of said regulating valve (2a, 2b, 13a, 13b) a standardized set command and / or a standardized through-flow rate and / or a standardized volumetric flow rate of at least one of said working units (3a, 3b) can be set independently of said system pressure (9) and / or of a load pressure (10a, 10b) of at least one of said working units (3a, 3b), A hydraulic device characterized by:

2. each of said working units (3a, 3b) is assigned one of said regulating valves (2a, 2b, 13a, 13b); 2. The hydraulic device according to claim 1 .

3. The valve adjustment unit and / or the valve control unit are provided within the adjustment valve (2a, 2b, 13a, 13b) or attached to the adjustment valve (2a, 2b, 13a, 13b); 3. The hydraulic device according to claim 1 or 2, characterized in that

4. the valve adjustment and / or the valve control have information regarding the hydraulic medium used, The hydraulic device according to any one of claims 1 to 3, characterized in that

5. at least one temperature sensor is provided, and said at least one temperature sensor is provided in said regulating valve (2a, 2b, 13a, 13b) or associated with said regulating valve (2a, 2b, 13a, 13b); The hydraulic device according to any one of claims 1 to 4, characterized in that

6. At least one temperature sensor is provided for each of the regulating valves (2a, 2b, 13a, 13b), 6. The hydraulic device according to claim 5,

7. The pressure sensor (6) is provided in the regulating valve (2a, 2b, 13a, 13b) or attached to the regulating valve (2a, 2b, 13a, 13b); The hydraulic device according to any one of claims 1 to 6, characterized in that

8. The regulating valve geometry of the regulating valve (2a, 2b, 13a, 13b) includes a spool geometry of a valve spool; The hydraulic device according to any one of claims 1 to 7, characterized in that

9. The hydraulic system is a hydraulic system in a plastic injection molding machine for processing plastics or other plasticizable materials. The hydraulic device according to any one of claims 1 to 8, characterized in that

10. A method for controlling and / or regulating a hydraulic system for the supply of a number of working units (3a, 3b) comprising at least one control device (7) and a central drive (1), comprising: at least one of the working units (3a, 3b) is respectively assigned at least one regulating valve (2a, 2b, 13a, 13b) having a regulating valve geometry, - for each of said regulating valves (2a, 2b, 13a, 13b) at least one pressure difference is determined from at least one detected pressure respectively before and after said regulating valve (2a, 2b, 13a, 13b), at least one actual volume flow rate value is derived for each of the regulating valves (2a, 2b, 13a, 13b) from the relationship between the regulating valve geometry and the pressure difference across the regulating valves (2a, 2b, 13a, 13b), at least one pre-setpoint control for the central drive (1) is carried out from at least one volumetric flow setpoint of at least one of the working units (3a, 3b) and at least one actual volumetric flow value of at least one of the regulating valves (2a, 2b, 13a, 13b) in such a way that the system pressure (9) corresponds to at least the highest load pressure of the working units (3a, 3b), - by means of at least one said regulating valve (2a, 2b, 13a, 13b) the normalized set command and / or the normalized through-flow rate and / or the normalized volumetric flow rate of at least one of said working units (3a, 3b) is set independently of said system pressure (9) and / or of the load pressure (10a, 10b) of at least one of said working units (3a, 3b); The method comprising:

11. Each of said regulating valves (2a, 2b, 13a, 13b) controls the pressure of each of said working units (3a, 3b); The method according to claim 10, characterized in that

12. The pre-setpoint control is time-controlled and / or takes place in real time; 12. The method according to claim 10 or 11, characterized in that

13. a periodic integration of the normalized volume flow regulated by said regulating valve (2a, 2b, 13a, 13b) is carried out over at least one working unit cycle; The method according to any one of claims 10 to 12, characterized in that

14. - the actual volume flow values ​​of said regulating valves (2a, 2b, 13a, 13b) are continuously monitored, evaluated and correlated with at least one periodic actual volume flow value during machine operation, The method according to any one of claims 10 to 13, characterized in that

15. at least one of the regulating valves (2a, 2b, 13a, 13b) is operated as a changeover valve (12a, 12b) during serial movement of the working units (3a, 3b) and / or as a load-sensing regulating valve during simultaneous movement of the working units (3a, 3b); The method according to any one of claims 10 to 14, characterized in that

16. The implementation of pre-setpoint control is adapted in a self-optimizing manner using a periodically learning observer; The method according to any one of claims 10 to 15, characterized in that

17. The hydraulic device supplies a plurality of working units (3a, 3b) in a plastic injection molding machine for processing plastics or other plasticizable materials. The method according to any one of claims 10 to 16, characterized in that

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