Hydraulic device and method for adjusting a hydraulic device - Patents.com

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 February 24, 2021, the disclosure content of which is hereby expressly incorporated in its entirety into this application.

[0002] FIELD OF THE INVENTION 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 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 2. 10 The present invention relates to a method for controlling (open loop control) and / or regulating (closed loop control) a hydraulic system, the method comprising the features of the generic phrase of the present invention. [Background technology]

[0003] (Prior Art) Even in modern, electromechanically driven injection molding machines, hydraulic consumers or axes, such as ejectors, nozzle abutment functions, core pullers, and closing nozzles, still exist and can be supplied with energy by the injection molding machine. On the one hand, for certain machine axes that operate only in force-regulated mode most of the time, such as the nozzle abutment function, electromechanical drives are not proven for service life reasons. On the other hand, especially in the tool area, hydraulic actuators offer significant structural and economic advantages due to their high power density and minimal installation effort. Similarly, 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 using a control valve. To regulate the pump's delivery volume, an electronic pressure difference regulation device is provided. A sensor device for sensing generates a pressure difference between the (highest) load pressure of multiple consumers and the pump's delivery pressure. The control device then sets the pump so 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 pump's delivery pressure. The input pressure, and thus the pressure difference across the regulating valve for the second or further consumer, depends on the load pressure of the first or leading consumer and cannot be kept constant. The volumetric flow rate of the second or further consumer is therefore not proportional to the valve's opening cross section and therefore is not specific. This means that a pressure compensator (pressure equalizer) is required for each regulating valve of the non-dominant consumers, or the consumers need feedback on the magnitude of the corresponding volume flow in order to distribute the volume flow among 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 event of a supply shortage) is maintained.

[0005] DE 10 2015 201 318 A1 discloses a hydraulic control device for supplying pressure to at least two hydraulic consumers. An adjustable hydropump can be adjusted so that the pump pressure exceeds the highest load pressure of the simultaneously controlled hydraulic consumers by a predetermined pump pressure difference. For this purpose, a pressure compensator is used for each regulating valve. The pump regulator is controlled so that 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 nearly fully open at different pressure drops in the pump lines.

[0006] EP 0 649 722 B2 discloses a hydraulic system for supplying a working unit in a plastic injection molding machine with at least one consumer. Using a pressure sensor, the actual pressure is detected and compared with a target pressure, thereby providing a setpoint (manipulated variable) for a regulating element of a regulating pump for additionally controlling the operating pressure gradient as load sensing. The maximum power output of the regulating pump is preset by a frequency converter based on a preset value for each injection cycle and dependent on a further setpoint dependent on volume and pressure. The pump power output of the regulating pump can be actively adjusted below its maximum power output by a control device via a first setpoint at the regulating element.

[0007] DE 196 80 008 C1 discloses an apparatus comprising at least one controlled and hydraulically driven actuator, a hydraulic pump and a control / regulation device, which acts on the electrical drive of the hydraulic pump based on detected actuator data, the hydraulic pump being connected to the actuator by a predetermined line without a dissipative setting element, i.e. without a regulating valve, 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 hydraulic fluid flow volume per time unit is measured using a measuring device and transmitted as a corresponding signal to a control or regulating unit, which calculates the piston position from the 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 variations 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. This means that multiple shafts can be operated in tandem and in a demand-adapted, energy-optimized manner by a pump-servomotor drive unit that is adapted to the shaft consumers. Furthermore, hydraulic systems are known from the prior art in which multiple consumers or shafts are simultaneously supplied by the same pressure or volumetric flow source. The volumetric flow of the supply source is distributed to the multiple consumers. Static distribution is achieved, for example, using so-called flow distributor valves or internal gear flow dividers.

[0012] The second variant, for high-power machines with simultaneous, highly dynamic demands on the hydraulic power supply, often uses a constant-pressure supply, implemented via multiple hydraulic accumulators (or large, fixed-pressure pumps) and flow-pressure regulating valves at each consumer. When the supply source must provide pressure and volumetric flow according to demand, special challenges arise for the dynamic distribution of volumetric flow. To avoid adverse effects on the axial motion or axial force of multiple parallel-connected axes, a high system / accumulator pressure reserve is provided. This results in a correspondingly energy-unfavorable behavior because the unnecessary power, calculated from the required amount multiplied by the excess pressure in the regulating valve, must be converted into heat in the carrier medium. Since injection molding machines are typically purchased with tools that have exclusively sequential motions, the second variant is not capable of operating the energetically optimal cycle corresponding to the first variant, and vice versa. The first variant cannot operate tools with simultaneous core-puller motions. 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 needed. However, these configurations have significant commercial drawbacks, as 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 synchronism specification is permanently fixed in the machine design.

[0014] The known solutions of the prior art result in the consumers influencing one another to a great extent, which is application-related 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 and by the claims 10 The problem is solved by a method having the following features: That is, according to the first aspect of the present invention, 1. A hydraulic device for the supply of a plurality of working units, in particular in a plastic injection molding machine for processing plastics or other plasticizable materials, comprising at least one control device, at least one valve adjustment and / or valve control, and a central drive, At least one of the operating units is assigned at least one regulating valve having a regulating valve geometry and is provided with a plurality of pressure sensors, each of which is configured to detect at least one pressure across the regulating valve, a load pressure of the operating unit, and a system pressure, the valve adjusting unit and / or the valve control unit have information about the regulating valve geometry of the regulating valves and are configured to derive at least one actual volume flow rate value for each regulating valve from a relationship between the regulating valve geometry and at least one pressure difference obtained from pressures sensed before and after the regulating valve, the control device is configured to perform at least one pre-setpoint control for the central drive from a volumetric flow target value of at least one of the operating units and / or from at least one actual volumetric flow value of at least one of the regulating valves, such that the system pressure corresponds to at least the highest load pressure of the operating unit; A hydraulic device is provided, characterized in that: More specifically, in the first aspect, 1. A hydraulic device for the supply of a plurality of working units, in particular in a plastic injection molding machine for processing plastics or other plasticizable materials, comprising at least one control device, at least one valve adjustment and / or valve control, and a central drive, At least one of the operating units is assigned at least one regulating valve having a regulating valve geometry and is provided with a plurality of pressure sensors, each of which is configured to detect at least one pressure across the regulating valve, a load pressure of the operating unit, and a system pressure, the valve adjusting unit and / or the valve control unit have information about the regulating valve geometry of the regulating valves and are configured to derive at least one actual volume flow rate value for each regulating valve from a relationship between the regulating valve geometry and at least one pressure difference obtained from pressures sensed before and after the regulating valve, The control device is configured to perform at least one pre-setpoint control for the central drive from a volumetric flow target value of at least one of the operating units and at least one actual volumetric flow value of the at least one regulating valve so that the system pressure corresponds to at least the highest load pressure of the operating unit; Using the regulating valve, a standardized set command and / or a standardized through-flow rate and / or a standardized volumetric flow rate of at least one of the operating units can be set independently of the system pressure and / or the load pressure of at least one of the operating units; It is characterized by: Further, according to a second aspect of the present invention, 1. A method for controlling and / or regulating hydraulic devices for the supply of several working units in a plastic injection molding machine, in particular for processing plastics and other plasticizable materials, comprising at least one control device and a central drive, the method comprising: at least one of the working units is respectively assigned at least one regulating valve having a regulating valve geometry, - for each of said regulating valves, at least one pressure difference is determined from at least one sensed pressure before and after said regulating valve, respectively; - at least one actual volume flow rate value is derived for each regulating valve from the relationship between the regulating valve geometry and the pressure difference across the regulating valve; - at least one pre-setpoint control for the central drive is carried out from at least one volumetric flow setpoint of at least one of the operating units and / or at least one actual volumetric flow value of at least one of the regulating valves in such a way that the system pressure corresponds to at least the highest load pressure of the operating unit; A method is provided that includes: More specifically, in the second aspect, 1. A method for controlling and / or regulating hydraulic devices for the supply of several working units in a plastic injection molding machine, in particular for processing plastics and other plasticizable materials, comprising at least one control device and a central drive, the method comprising: at least one of the working units is respectively assigned at least one regulating valve having a regulating valve geometry, - for each of said regulating valves, at least one pressure difference is determined from at least one sensed pressure before and after said regulating valve, respectively; - at least one actual volume flow rate value is derived for each regulating valve from the relationship between the regulating valve geometry and the pressure difference across the regulating valve; - at least one pre-setpoint control for the central drive is carried out from at least one volumetric flow setpoint of at least one of the operating units and at least one actual volumetric flow value of at least one of the regulating valves in such a way that the system pressure corresponds to at least the highest load pressure of the operating unit; using at least one regulating valve, a normalized set command and / or a normalized through-flow rate and / or a normalized volumetric flow rate of at least one of the operating units is set independently of the system pressure and / or the load pressure of at least one of the operating units; It is characterized by: It should be noted that the reference numerals used in the claims of this application are intended solely to facilitate understanding of the present invention and are not intended to limit the present invention to the illustrated forms.

[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 the contents described in the present specification and by details from the drawings, which will show further implementation variations of the invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] The present invention can have the following configurations. (Form 1) A hydraulic device for the supply of several working units, in particular in a plastic injection molding machine for processing plastics and other plasticizable materials, comprising at least one control device, at least one valve adjustment and / or valve control, and a central drive, At least one of the operating units is assigned at least one regulating valve having a regulating valve geometry and is provided with a plurality of pressure sensors, each of which is configured to detect at least one pressure across the regulating valve, a load pressure of the operating unit, and a system pressure, the valve adjusting unit and / or the valve control unit have information about the regulating valve geometry of the regulating valves and are configured to derive at least one actual volume flow rate value for each regulating valve from a relationship between the regulating valve geometry and at least one pressure difference obtained from pressures sensed before and after the regulating valve, The control device is configured to perform at least one pre-setpoint control for the central drive from a volumetric flow target value of at least one of the operating units and / or from at least one actual volumetric flow value of at least one of the regulating valves so that the system pressure corresponds to at least the highest load pressure of the operating unit. (Form 2) It is preferred that, using the regulating valve, a standardized set command and / or a standardized through flow rate and / or a standardized volumetric flow rate of at least one of the operating units can be set independently of the system pressure and / or the load pressure of at least one of the operating units. (Form 3) Preferably, each of the working units is assigned one of the regulating valves. (Form 4) It is preferable that the valve adjustment unit and / or the valve control unit be provided within the adjustment valve or attached to the adjustment valve. (Form 5) Preferably, the valve adjustment and / or the valve control has information about the hydraulic medium used. (Form 6) At least one temperature sensor is provided, preferably at least one temperature sensor for each of the regulating valves, and preferably the at least one temperature sensor is provided within or attached to the regulating valve. (Form 7) The pressure sensor is preferably provided within the regulating valve or attached to the regulating valve. (Form 8) Preferably, the regulating valve geometry of the regulating valve includes a spool geometry of a valve spool. (Form 9) 1. A method for controlling and / or regulating hydraulic devices for the supply of several working units in a plastic injection molding machine, in particular for processing plastics and other plasticizable materials, comprising at least one control device and a central drive, the method comprising: at least one of the working units is respectively assigned at least one regulating valve having a regulating valve geometry, - for each of said regulating valves, at least one pressure difference is determined from at least one sensed pressure before and after said regulating valve, respectively; - at least one actual volume flow rate value is derived for each regulating valve from the relationship between the regulating valve geometry and the pressure difference across the regulating valve; - from at least one volumetric flow target value of at least one of said operating units and / or from at least one volumetric flow actual value of at least one of said regulating valves, at least one pre-target value control for said central drive is carried out in such a way that the system pressure corresponds to at least the highest load pressure of said operating unit. (Form 10) It is preferred that, using at least one of the regulating valves, the normalized set command and / or normalized through flow rate and / or normalized volume flow rate of at least one of the operating units is set independently of the system pressure and / or the load pressure of at least one of the operating units. (Form 11) Preferably, each said regulating valve controls the pressure of each said working unit. (Form 12) Pre-setpoint control is preferably time-controlled and / or takes place in real time. (Form 13) Preferably, a periodic integration of the normalized volume flow regulated by the regulating valve is carried out over at least one work unit cycle. (Form 14) Preferably, the actual volume flow rate of the regulating valve is continuously monitored, evaluated and correlated with the actual volume flow rate during at least one periodic machine operation. (Form 15) Preferably, at least one of the regulating valves is operated as a changeover valve in the case of serial movement of the working units and / or as a load-sensing regulating valve in the case of simultaneous movement of the working units. (Form 16) The implementation of pre-setpoint control is preferably self-optimizing and adaptive using a periodically learning observer.

[0019] In particular, in plastic injection molding machines for processing plastics and other plasticizable materials, a hydraulic system for supplying a plurality of operating units includes at least one control device, at least one valve regulating device (valve closed-loop control device) and / or valve control device (valve open-loop control device), and a central drive. The control device can include the valve regulating device and / or valve control device, or the valve regulating device and / or valve control device can include the control device. For each operating unit, at least one regulating valve with a regulating valve geometry (e.g., 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 a proportional valve for regulating the volumetric flow to the operating unit. Furthermore, a plurality of pressure sensors, for example pressure recorders, are provided for each regulating valve, respectively, detecting at least one pressure before and after the regulating valve, the load pressure of the operating unit, and the system pressure. In principle, it is also possible for only one of the operating units to be equipped with a regulating valve, while the remaining operating units are controlled, for example, by means of switching valves. At least one digital regulating valve, preferably with a spool geometry and with integrated valve adjustment and / or valve control, can be provided for each operating unit. The regulating valve can be configured, for example, as a continuous valve for adjusting the volume flow to the operating unit.

[0020] Advantageously, in order to achieve improvements over the solutions existing in the prior art in terms of functionality, energy, efficiency, and economy, the valve regulating unit and / or the valve control unit have 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 are configured to derive at least one actual volume flow value for each regulating valve from the relationship between the regulating valve geometry and at least one pressure difference obtained from the pressures sensed before and after the at least one regulating valve. The control device is configured to perform at least one setpoint pre-control for the central drive from at least one volume flow setpoint of the operating unit or from volume flow setpoints of multiple operating units and / or from the volume flow actual value of the at least one regulating valve, so that the system pressure corresponds at least to the highest load pressure of at least one operating unit. (Regarding pre-control: Pre-control pre-sets a value, which provides a starting point or a reference for the expected adjustment range for further adjustment.) In this context, the system pressure at least corresponding to the highest load pressure means that the system pressure can be greater than or equal to the load pressure and can also exceed the load pressure, for example, by a predetermined value. This means that, for example, one or more pressure compensators are advantageously not required.

[0021] The values ​​can be preset, for example, manually and / or automatically, for example, by a control device. They can also be preset depending on the parameters of the injection molding process. The information can be present in an electronic and / or digital memory, for example, as an algorithm, function, and / or control characteristic curve. In principle, the information can already be present in the valve adjustment and / or valve control and can be 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 valve setting. This means that using the regulating valve, a normalized setting command and / or through-flow rate of the operating unit can be preferably set independently of the system pressure and / or the load pressure of the operating unit. This further advantageously eliminates the need to re-set the regulating valve, thereby eliminating the need for compensation (adjustment) tasks during maintenance.

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

[0024] In this context, "normalized" means that for a normalized volume flow rate and / or normalized throughflow rate, if a preset target value for the volume flow rate and / or throughflow 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 throughflow rate is obtained depending on the setpoint (manipulated variable), or a normalized volume flow rate that is independent of the load pressure and system pressure. This preferably results in no need to install new adjustment / control units, for example, when using different valves or replacing other system components.

[0025] Furthermore, if the scaled and correspondingly assigned numerical value (quantity) can be normalized and set via a setting command, normalization may be performed for a numerical value (quantity) that is fundamentally different from the volumetric flow rate or the through flow rate.

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

[0027] Advantageously, pre-control based on the actual volume flow rate can also provide appropriate pre-control 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 target value.

[0028] The regulating valve is therefore advantageously able to regulate the physically normalized throughflow rate in the operating unit according to a preset setpoint, independently of the system pressure and the load pressure, and in the quasi-static pressure regulation state, to perform the pressure maintenance function independently of fluctuations in the system pressure. Of course, this is only valid insofar as the hydrodynamic assumption for compensating for losses through the valve is given by the corresponding delta p as the differential pressure between the system pressure and the load pressure.

[0029] Advantageously, therefore, in terms of functionality, energy, efficiency, and economy, no more volumetric flow and / or pressure is provided than is exactly required for the sum of the operating units. For this purpose, the volumetric flow and / or pressure of the central drive is distributed to the operating units. Advantageously, the influence of the operating units on one another is limited to a minimum, and it is always possible to adjust and / or limit the volumetric 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 the simultaneous movement of at least two working units that do not interact with each other, an optimal system pressure is achieved, which is achieved 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 with appropriate system-related adjustment functions 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 of 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 have information about the hydraulic medium used, which preferably results in accurate and precise pre-setpoint control. For example, in the gap of the valve spool, viscosity plays an important role for laminar flow, which in turn affects the volume flow rate near the zero point (overlap edge) in relation to the application. The valve adjustment and / or valve control preferably know (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, which depends on the hydraulic medium used.

[0034] In injection molding machines, for example, hydraulic fluid distribution to the operating units is often achieved via compressible volumes, e.g., hoses, thereby providing a certain hydraulic reservoir or hydraulic capacity to the system. A direct load jump, e.g., due to a collision, is directed to one operating unit, and the regulating dynamics of a second operating unit do not affect even the operating unit to be controlled. Similarly, in practical installations, the always-present compressible dead volume of the central drive and control unit allows the pressure supply to be directly monitored by the pressure supply and to be lowered (including a decrease from a higher level to a lower level, stopping) or raised (including an increase or rise from a lower level to a higher level, starting) in response to the pressure / volume, with slower dynamics than a regulating valve, in a timely and energy-efficient manner.

[0035] Advantageously, for improved modularity in the installation design, the valve adjustment and / or valve control are preferably arranged within 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. However, in principle, the valve adjustment and / or valve control can also be arranged elsewhere, for example, within 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 viscosity prediction of the hydraulic medium to be carried out and 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 of each working unit branch.

[0037] Since injection molding machines are often individually constructed in a modular manner, it is also advantageous to provide an increased modularity in the plant design by providing a pressure sensor in or attached to the regulating valve, and if the valve is replaced, for example, due to a remodel, it is advantageously not necessary to carry out further remodeling measures.

[0038] In principle, and preferably, each regulating valve can have a pressure sensor, a temperature sensor and / or a valve adjustment and / or 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, so that knowledge of this geometry advantageously enables a reliable, economical and energy-efficient regulation of the volume flow, e.g. in the sense of the delivery flow distribution.

[0040] Furthermore, the problem is solved by the following claims: 10To improve upon the solutions existing in the prior art in terms of 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 (open-loop control) and / or regulating (closed-loop control) a hydraulic device for supplying a plurality of operating units, wherein at least one pressure difference is determined for each regulating valve from at least one detected pressure across 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 across the regulating valve, and at least one setpoint pre-control for the central drive is carried out from the volumetric flow rate setpoint 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 to at least 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 the load pressure and may exceed the load pressure, for example by a predetermined value.

[0041] Preferably, at least one regulating valve is used to set the normalized setpoint and / or throughflow and / or volumetric flow of the operating unit independently of the system pressure and / or the load pressure of the at least one operating unit, so that, for example, a desired volumetric flow can be advantageously set or adjusted according to a predefined characteristic curve, i.e., a normalized throughflow or volumetric flow is obtained as a function of the setpoint (manipulated variable).

[0042] Preferably, each regulating valve controls the pressure of each of the multiple operating units, which advantageously allows accurate and precise pre-setpoint control 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 advantageously rapid adjustment of the throughflow rate and for precise provision, the pre-setpoint control is preferably time-controlled and / or performed in real time. For example, the pre-setpoint control is time-controlled (harmonized) using the operating unit based on the volume flow rate setpoint of the operating unit and / or is performed in real time based on the actual volume flow rate of the regulating valve. In this context, time-controlled (harmonized) means that a volume flow rate setpoint is provided to the operating unit at a predetermined time point using the pre-setpoint control. For example, the pre-setpoint control is based on the actual volume flow rate in real time, and can advantageously provide 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] To advantageously detect leakage in the operating unit, a periodic integration of the normalized volume flow regulated by the regulating valve is preferably carried out over at least one operating unit cycle, with the integration being compared, for example, with the previous operating unit cycle, to determine whether or not there is a leakage.

[0045] To advantageously detect wear in the valve mechanism, for example 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 the wear state can be derived.

[0046] For energy-optimized operation and improved application of simultaneous requirements or increased demands on dynamics and reproducibility, at least one regulating valve is preferably operated as a switching valve in the serial operation of at least one operating unit, and / or at least one regulating valve is operated as a load-sensing regulating valve in the simultaneous operation of several operating units. Thus, several operating units can be advantageously operated directly in the injection molding cycle using a control device and a central drive. For example, the regulating valve can be switched by the control device as a switching valve to maximize the throughflow or to close. Therefore, due to the absence of a hydromechanical pressure compensator, it is possible to achieve approximately the same energy efficiency in serial operation 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 self-optimized and adapted using a periodically learning observer. For example, the pressure superposition in the system circuit can be self-optimized and adapted to the optimal state of dynamics and energy consumption per cycle using a periodically learning observer based on the observation of the regulation quality in the working unit circuit, in particular the pressure overshoots / undershoots occurring in the working unit circuit.

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

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

[0050] The invention will now be described in detail with reference to several embodiments shown in the accompanying drawings. [Brief explanation of the drawings]

[0051] [Figure 1] FIG. 1 shows a hydraulic device with two working units. [Figure 2] FIG. 2 shows a hydraulic device corresponding to FIG. 1 with two regulating valves. [Figure 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. [Figure 5] FIG. 1 shows a schematic method chart. [Example]

[0052] DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention will now be described in detail by way of examples with reference to the accompanying drawings. However, these examples are merely illustrative and should not be construed as limiting the inventive concept to any particular apparatus. Before describing the present invention in detail, it should be noted that the present invention is not limited to each component of the apparatus or each method step, since these components and methods may vary. Furthermore, the concepts and terms used herein are defined solely for the purpose of describing particular embodiments and are not intended to be limiting. In addition, where the singular or indefinite article is used in this specification or claims, it is understood that the plural of these elements may be used unless the context of the whole clearly dictates otherwise. (Note that, correspondingly, the singular also represents the plural in Japanese translations.)

[0053] 1 shows a hydraulic unit for supplying a number of working units, in this example two working units 3a, 3b, such as ejectors, nozzles, core pullers or closing nozzles, 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 to process plastics and other plasticizable materials, such as ceramic, metallic and / or powdery substances.

[0054] As shown in Fig. 1, 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. In principle, however, further operating units 3a, 3b can also 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. In the exemplary embodiment of Fig. 1, the regulating valves 2a, 2b are configured, for example, 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 to the operating units 3a, 3b.

[0055] A plurality 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 valve control, preferably via a connection 21, for example a bus. In principle, however, other connections 21, for example a wireless network, are also conceivable. Via the connections 21, the regulating valves 2a, 2b are preferably in communication with the control device 7 and the central drive 1 and / or the valve adjustment and / or valve control.

[0056] The valve adjusting and / or valve control unit has information about the regulating valve geometry (structural shape 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(stroke Hub)" or 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 unit and is entered manually or provided automatically, for example via a network connection. The valve adjusting and / or valve control unit is configured to derive at least one actual volume flow value for each regulating valve 2a, 2b from the 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.

[0057] In FIG. 3, only one p / Q valve as regulating valve 2a, one switching valve 12a and 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 and method according to the invention can also be used advantageously when not all of the operating units are equipped with an adjusting valve, or when only one of the operating units in Fig. 3 is equipped with an adjusting valve. One of the operating units can be supplied (with hydraulic pressure or fluid) via a switching valve, for example. This operating unit can be, for example, a closing nozzle operating unit, but its switching process systematically affects other operating units. For example, if 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 of the regulating valve 2a, 2b, so that the valve adjustment and / or valve control unit has information about which pressure is associated with which setting of the regulating valve or which setting 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 valve adjusting and / or valve control units 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 configured to derive at least one setpoint pre-control for the central drive 1 from the setpoint volumetric flow rates of the working units 3a, 3b and / or the actual volumetric flow rates 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 predetermined value than the load pressure.

[0062] Thus, at least one regulating valve 2a, 2b can adjust a physically normalized throughflow rate, for example in l / min (liters per minute), in the operating units 3a, 3b corresponding to a preset target 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 hydraulic assumption for compensating for losses through the valve is given by the corresponding delta p as the pressure difference between the system pressure 9 and the load pressure 10a, 10b. Therefore, by means of at least one regulating valve 2a, 2b, the normalized set command and / or normalized throughflow rate and / or normalized volumetric flow rate of the operating units 3a, 3b can be set independently of the system pressure 9 and / or the load pressure of at least one operating unit.

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

[0064] For example, suppose two types of valves are used, one with a nominal maximum volumetric flow rate of, say, 180 l / min and the other with, say, 140 l / min. The linearized characteristic curve, in this example, assuming sufficient supply pressure, would regulate the first valve to a volumetric flow rate of 90 l / min at a setpoint (operating variable) of 50% and the second valve to a volumetric flow rate of 70 l / min at a setpoint (operating variable) of 50%.

[0065] In this context, "normalized" means that for a normalized volume flow rate and / or normalized throughflow rate, if a preset target value for the volume flow rate and / or throughflow 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 throughflow rate is obtained depending on the setpoint (manipulated variable), or a normalized volume flow rate that is independent of the load pressure and system pressure. This preferably results in no need to install new adjustment / control units, for example, when using different valves or replacing other system components.

[0066] Furthermore, if the scaled and correspondingly assigned numerical value (quantity) can be normalized and set via a setting command, normalization may be performed for a numerical value (quantity) that is fundamentally different from the volumetric flow rate or the through flow rate.

[0067] In this context, a normalized setting command is a command (instruction) by which a normalized volumetric flow rate and / or a normalized through-flow rate can be set, for example. For example, the value (quantity) to be normalized can be expressed (normalized) as a volumetric flow rate, for example in l / min (liters per minute), so that the desired volumetric flow rate can be set or adjusted, for example, by 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 more accurate pre-control.

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

[0070] In a further preferred embodiment, at least one temperature sensor is provided, more preferably at least one temperature sensor, such as a temperature recorder, for each of the regulating valves 2 a, 2 b, 13 a, 13 b. Advantageously, measuring the temperature of the hydraulic medium allows for a more accurate prediction of the viscosity and therefore a more accurate flow 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 is advantageous 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, and the regulating valves 13a, 13b of Fig. 2 are configured there, for example, as continuous valves with a directional function (continuously adjustable valves).

[0073] The embodiment of Fig. 3 substantially corresponds to the embodiment of Fig. 1, but in Fig. 3 only one p / Q valve as regulating valve 2a, one switching valve 12a and 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] FIG. 4a shows a graph plotting the throughflow rate in cubic meters per second against time in seconds for two operating units 3a, 3b without pre-control according to the prior art. First, the first operating unit 3a accelerates with a high load pressure until, at time E1, the second operating unit 3b accelerates with a lower load pressure. Because the second operating unit 3b also requires a corresponding throughflow rate, the acceleration of the second operating unit 3b results in a schematically exaggerated bend in the throughflow rate of the first operating unit 3a. At time E2, the first operating unit 3a decelerates, requiring a lower throughflow rate, which can be seen as an "overshoot" in the second operating unit 3b. The two operating units 3a, 3b therefore act strongly against each other, which can lead to errors in the operating process and the quality of the injection-molded parts.

[0075] In Figure 4b, a graph similar to Figure 4a is shown, but with pre-setpoint control of the central drive 1 by the control device 7. It can be seen that at times E1 and E2, the two working units 3a, 3b interact less with each other.

[0076] 5 shows a schematic block diagram of a method for controlling (open-loop control) and / or regulating (closed-loop control) a hydraulic system for supplying a number of 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 across the regulating valve 2a, 2b, 13a, 13b. In a further step 51, at least one actual volumetric flow rate value for each regulating valve 2a, 2b, 13a, 13b is derived 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 volumetric flow setpoint of at least one operating unit 3a, 3b and / or the volumetric flow actual value of the regulating valve 2a, 2b, 13a, 13b, at least one setpoint pre-control for the central drive 1 is carried out so 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 predetermined value, which value can, for example, be entered manually or 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 carried out over at least one work unit cycle, which detects whether more hydraulic medium is being 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 on the control edge or in the valve mechanism in the event of leakage through the piston, the actual volume flow values ​​of the regulating valves 2a, 2b, 13a, 13b are continuously monitored, evaluated and correlated with the actual volume flow values ​​during at least one periodic 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, which advantageously allows for an optimum state of dynamics and energy consumption / cycle. This means that the pressure superposition in the system circuit can be adapted in a self-optimizing manner based on the observation of the regulation quality in the working unit circuit, in particular based on the observation of pressure overshoots / undershoots occurring in the working unit circuit.

[0082] Obviously, the teachings herein are susceptible to numerous modifications, variations and adaptations, provided they fall within the scope and range of equivalents of the appended claims. [Explanation of symbols]

[0083] 1 Central drive unit 2a Adjusting valve 2b Adjustment valve 3a Unit of Work 3b Unit of Work 4. Pump 5 motors 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 Adjusting valve 13b Adjusting valve 20 Dead Volume 21 Connection section (connection system) 50 steps 51 steps 52 steps

Claims

1. A hydraulic device for the supply of several 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 the operating units (3a, 3b) is assigned at least one regulating valve (2a, 2b, 13a, 13b) having a regulating valve geometry and is provided with a plurality of pressure sensors (8), the pressure sensors (8) being configured for each of the regulating valves (2a, 2b, 13a, 13b) to sense at least one pressure before and after the regulating valve (2a, 2b, 13a, 13b), a load pressure (10a, 10b) of the operating unit (3a, 3b) and a system pressure (9); the valve adjusting 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 volume 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 obtained from pressures sensed before and after the regulating valves (2a, 2b, 13a, 13b), the control device (7) is configured to perform 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 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), using the regulating valve (2a, 2b, 13a, 13b), a normalized set command and / or a normalized through-flow rate and / or a normalized volumetric flow rate of at least one of the working units (3a, 3b) can be set independently of the system pressure (9) and / or the load pressure (10a, 10b) of at least one of the working units (3a, 3b), A hydraulic device characterized by:

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

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

4. the valve adjustment unit and / or the valve control unit have information about 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 attached to 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, wherein:

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) comprises 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 being 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 several 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 operating 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 operating 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 volume flow rate of at least one of said working units (3a, 3b) is set independently of the system pressure (9) and / or the load pressure (10a, 10b) of at least one of said working units (3a, 3b); A method characterized by:

11. Each of the regulating valves (2a, 2b, 13a, 13b) controls the pressure of each of the working units (3a, 3b); The method of claim 10, wherein:

12. The pre-target value control is time-controlled and / or performed in real time; 12. The method according to claim 10 or 11, characterized in that:

13. at least one periodic integration of the normalized volume flow regulated by the 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 the actual volume flow values ​​during at least one periodic 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 switching valve (12a, 12b) in the serial movement of the working units (3a, 3b) and / or as a load-sensing regulating valve in the 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 self-optimizing and adaptive using a periodically learning observer; The method according to any one of claims 10 to 15, characterized in that

17. said hydraulic device serving to supply 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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