Hydraulic device and method for regulating a hydraulic device

Abstract

The invention relates to a hydraulic device for supplying a plurality of work units (3a, 3b), in particular on a plastic injection molding machine, comprising at least one controller (7), at least one valve regulator and / or a valve controller, and a central drive (1). A regulating valve (13a, 13b) with a regulating valve geometry is provided on at least one work unit. A pressure sensor (8) detects at least one pressure both upstream and downstream of the regulating valve (13a, 13b), a load pressure (10a, 10b) of the at least one work unit (3a, 3b), and a system pressure (9). Since the valve regulator and / or the valve controller has stored information about the regulating valve geometry of the at least one regulating valve (13a, 13b) and is designed to derive at least one volume flow actual value of each regulating valve (13a, 13b) from the relationship between the regulating valve geometry and at least one pressure difference resulting from the detected pressures upstream and downstream of the regulating valve (13a, 13b), and the controller (7) is designed to derive at least one setpoint value feedforward control for the central drive (1) from the volume flow setpoint value of the at least one work unit (3a, 3b) and / or the volume flow actual value of the at least one regulating valve (13a, 13b) in such a way that the system pressure (9) at least corresponds to the associated maximum load pressure (10a, 10b) of the work unit (3a, 3b), the hydraulic device is improved in terms of functionality, energy, efficiency and economy.

Description

[0001] Cross-citation of related applications

[0002] This invention relates to and claims priority to German patent application 102021104398.0, filed on February 24, 2021, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] The present invention relates to a hydraulic device for supplying at least one working unit, particularly at least one working unit on a plastic injection molding machine, and to a method for open-loop control and / or closed-loop control of the hydraulic device. Background Technology

[0004] Even in modern (e.g., electromechanically driven) injection molding machines, hydraulically consumed devices or shafts (such as ejectors, nozzle contacts, core pullers, and closure nozzles) still exist and must be powered by the injection molding machine. On the one hand, in cases where specific machine shafts operate mostly only in force-controlled operations, such as in nozzle contact functions, electromechanical drives have proven unsuitable in terms of service life. On the other hand, particularly in the mold area, hydraulic actuators offer major structural and economic advantages due to their high power density and low installation costs. Similarly, for compatibility reasons between new machines and existing molds, new electromechanically driven and energy-optimized machines require integrated hydraulic power supplies.

[0005] DE102009020111A1 discloses a hydrostatic drive system comprising a pump with load-sensing control and at least one consumable device controllable by a control valve. An electronic pressure differential control is provided for closed-loop control of the pump's flow rate, wherein a sensor device for detection forms a pressure difference from the (maximum) load pressure of multiple consumable devices and the pump's supply pressure, and a control device adjusts the pump such that this pressure difference corresponds to a preset closed-loop control difference. Therefore, a preset (i.e., fixed) closed-loop control pressure difference between the load pressure (preferably maximum) and the pump's supply pressure is closed-loop controlled. Therefore, the input pressure, and thus the pressure difference at the closed-loop control valve for the second or other consumable device, depends on the load pressure on the first or dominant consumable device and thus cannot remain constant. Therefore, the flow rate of the second or other consumable device is not proportional to the cross-sectional area of ​​the valve opening and is therefore undefined. The corresponding closed-loop control valve for the non-dominant consumable device requires a corresponding pressure gauge, or the consumable device requires a return pipe sized to suit the flow rate to divide the flow rate among the consumable devices as needed. How the volumetric flow rate division is performed as needed is not obvious. Because the dominant pressure differential is maintained (and collapses in the event of insufficient supply), only the sum of the flow rates corresponds to the demand of all consuming devices.

[0006] DE102015201318A1 discloses a hydraulic control device for supplying compressed medium to at least two hydraulic consuming devices. The adjustable hydraulic pump is variable, such that the pump pressure is higher than the maximum load pressure of the simultaneously activated hydraulic consuming devices by a pump pressure differential. For this purpose, pressure gauges are used for each closed-loop control valve. Here, the closed-loop pump control device is activated such that, taking into account the different pressure drops in the pump line with respect to the magnitude of the pump pressure differential, and if different pressure drops exist in the pump line, the respective pressure gauges associated with the hydraulic consuming device having the highest load pressure are at least approximately fully open.

[0007] EP0649722B2 discloses a hydraulic device for supplying work units on a plastic injection molding machine having at least one consumable device. A pressure sensor detects an actual pressure value and compares it to a setpoint pressure value. As a result, a control variable for a closed-loop control member of the closed-loop control pump is transmitted as load sensing for corrective control of pressure drop in the operating pressure. The maximum output of the closed-loop control pump is predetermined by a frequency converter based on a predetermined value for the corresponding injection cycle, according to another control variable depending on the quantity and pressure. Pump outputs below the maximum output of the closed-loop control pump can be actively controlled by a controller at the closed-loop control member via a first control variable.

[0008] DE19680008C1 discloses an apparatus having at least one controlled hydraulically driven actuator, a hydraulic pump, and an open-loop or closed-loop control device. The open-loop or closed-loop control device acts on the electric drive of the hydraulic pump based on detected actuator data, and this is directed to the actuator through a conduit without a dissipation correction element (i.e., without a closed-loop control valve), but the load on the hydraulic pump does not change.

[0009] DE102011012714A1 discloses a hydraulic drive unit for an injection molding machine, wherein the flow rate of hydraulic fluid per unit time is measured by a measuring device and forwarded as a corresponding signal to an open-loop or closed-loop control unit, which calculates the position of the piston from it.

[0010] Currently, in other existing technologies, two basic variations regarding the supply of fluid power in a manner integrated into an injection molding machine are conventional.

[0011] The first variation for pure tandem core puller or short shaft function is implemented using a so-called servo-controlled constant pump and a simple shaft sequence valve. In this way, multiple shafts can be operated sequentially and in a manner suited to the needs of the pump and servo motor drive unit, which is adapted to the shaft consuming devices for energy optimization. Further known from the prior art are hydraulic systems in which multiple consuming devices or shafts are simultaneously supplied by the same pressure or volumetric flow source. The volumetric flow from the source is diverted among the consuming devices. So-called flow divider valves or internal gear flow dividers are used, for example, for static flow diversion.

[0012] The second variant (e.g., for high-power machines with multiple simultaneous and highly dynamic demands on fluid power supply) is typically implemented using a constant-pressure supply via a hydraulic accumulator (or a large-size constant-pressure pump) and closed-loop volumetric pressure control valves on individual consumption devices. If the source provides pressure and volumetric flow on demand, a specific challenge arises in dynamically allocating the volumetric flow. To avoid impacting axial movement or axial force in the case of multiple shafts connected in parallel, a system pressure / stored pressure with a large reserve is provided. This results in correspondingly unfavorable behavior from an energy perspective, as the power of unwanted overpressure multiplied by the required volume in the closed-loop control valve must be converted into heat in the carrier medium. Since injection molding machines are widely available, the second variant with molds having only sequential movement cannot perform the energy-optimized cycle according to the first variant, and conversely, the first variant cannot serve molds with simultaneous core ejector movements. Proportional flow control valves can be used, for example, for dynamically allocating, each proportional flow control valve associated with a corresponding consumption device.

[0013] Other configurations are known from the prior art, in which multiple first-variant servo pumps are installed, or multiple first-variant servo pumps are added as needed. However, these configurations have considerable commercial disadvantages regarding overall energy balance, and for certain operating points, from an energy perspective, they are in some cases worse than constant-pressure systems (frequent changes in output, frequent acceleration and deceleration of the drive, and high demands on pressure maintenance). The flexibility of these configurations is also very limited because the short-axis synchronization specifications are fixed invariably when the machine is set up.

[0014] The solutions known in the prior art have the following effect: the consumable devices affect each other to such an extent that this may be related to their use and therefore may also have an adverse effect on the quality of the injection molded parts to be manufactured. Summary of the Invention

[0015] Based on the prior art, the object of the present invention is to provide a hydraulic device for supplying at least one working unit, particularly at least one working unit in a plastic injection molding machine, wherein the hydraulic device is improved in terms of functionality, energy, efficiency and cost-effectiveness.

[0016] This objective is achieved by the hydraulic device and method of the present invention.

[0017] Features individually specified in the claims are combinable, where this is technically meaningful, and can be supplemented by explanatory factual material from the description and details from the drawings, which indicate further variations of the invention.

[0018] A hydraulic system for supplying multiple work units, particularly in plastic injection molding machines used for processing plastics and other plasticizable materials, comprises at least one controller, at least one closed-loop valve control and / or open-loop valve control, and a central actuator. The controller may include closed-loop valve control and / or open-loop valve control, and vice versa. For each work unit, at least one closed-loop control valve, preferably an electronic and / or digital closed-loop control valve, is provided having a control valve geometry (e.g., a spool valve geometry). The closed-loop control valve may be, for example, a continuously adjustable valve or a proportional valve, which controls the volumetric flow rate to the work unit. Furthermore, a pressure sensor, such as a pressure transducer, is provided to detect at least one pressure upstream and downstream of the closed-loop control valve, the load pressure of the work unit, and the system pressure for each closed-loop control valve. In principle, it is also permissible for only one work unit to be equipped with a closed-loop control valve, while other work units are activated, for example, via sequential valves. Preferably, for each work unit, at least one digital closed-loop control valve with a spool valve geometry and integrated closed-loop valve control and / or open-loop valve control may be provided. Closed-loop control valves can take the form of, for example, continuously adjustable valves, which control the volumetric flow rate of the working unit.

[0019] To advantageously improve upon existing solutions in terms of functionality, energy efficiency, and cost-effectiveness, closed-loop valve controls and / or open-loop valve controls include stored knowledge of the control valve geometry of the closed-loop control valve, for example in the form of control characteristics, volumetric flow rate signal characteristics, or the function "opening cross-section = f (stroke)", or the geometry of the valve slide block, and are configured to derive at least one actual value of the volumetric flow rate for each closed-loop control valve from the relationship between the control valve geometry and at least one pressure difference obtained from the detected upstream and downstream pressures of at least one closed-loop control valve. The controller is configured to derive at least one setpoint pre-control for the central actuator from the setpoint of the volumetric flow rate of at least one or more working units and / or from the actual value of the volumetric flow rate of at least one closed-loop control valve, such that the system pressure at least corresponds to the maximum load pressure of at least one working unit. In this context, system pressure at least corresponding to the maximum load pressure means that the system pressure is greater than or equal to the load pressure, and may even exceed the load pressure, for example, a certain value. In this way, advantageously, for example, a pressure gauge is not required.

[0020] This value can be preset manually and / or automatically, for example, automatically by a controller. It can also be preset based on parameters of the injection molding process. The stored information can take the form of algorithms, functions, and / or control characteristics in, for example, electronic and / or digital memory. In principle, it is conceivable that the stored information already exists in closed-loop and / or open-loop control valves, or is manually input or automatically recalled, for example, via a network connection.

[0021] Preferably, for each closed-loop control valve, the corresponding volumetric flow rate (e.g., the corresponding standardized volumetric flow rate, for example in liters per minute) is obtained from a specific pressure differential and a specific setting of the valve. In this way, the closed-loop control valve can be used to preferably set the standardized operating commands and / or flow rates of the working unit independently of the system pressure and / or the load pressure of the working unit. Further advantageously, since the closed-loop control valve does not need to be readjusted, calibration tasks are eliminated during maintenance.

[0022] As an example, two types of valves are used, where the first valve has a nominal maximum volumetric flow rate of, for example, 180 liters / minute, and the second valve has a nominal maximum volumetric flow rate of, for example, 140 liters / minute. In this example, with linearization characteristics and a 50% control variable, the first valve will be adjusted to a volumetric flow rate of 90 liters / minute, and with a 50% control variable, the second valve will be adjusted to a volumetric flow rate of 70 liters / minute, provided that sufficient supply pressure is present.

[0023] In this context, the term "standardization," used for standardizing volumetric flow rate and / or standardizing flow velocity, means that the setpoint value for the volumetric flow rate and / or flow is preset to, for example, 80 liters per minute, so that both valves are adjusted to a volumetric flow rate of 80 liters per minute regardless of pressure fluctuations and the nominal maximum volumetric flow rate. Therefore, the result is that the flow rate or volumetric flow rate is standardized according to the control variables and independent of the load pressure and system pressure. Therefore, preferably, the result is that, for example, when using different valves or actually if other system components are replaced, no new closed-loop / open-loop controls need to be implemented.

[0024] In principle, variables other than volumetric flow rate or flow rate can also be standardized, as long as the corresponding related variables can be set in a standardized manner and scaled through operation commands.

[0025] In this context, the term "standardized operating command" refers to, for example, a command that can set a standardized volumetric flow rate and / or flow rate. For example, a variable to be standardized can be mapped to (standardized to) a volumetric flow rate, such as in liters per minute, so that the desired volumetric flow rate can be set or controlled by closed-loop control (e.g., by characteristics), regardless of the valves used (system and load pressure).

[0026] Advantageously, in the case of pre-control based on the actual value of volumetric flow rate, appropriate pre-control can be performed even if the closed-loop control valve is undergoing closed-loop pressure control and therefore the volumetric flow rate of the closed-loop control valve does not (only) depend on the setpoint value of the volumetric flow rate.

[0027] In this way, the closed-loop control valve can advantageously correct the physically normalized flow rate at the working unit according to a predetermined setpoint value, regardless of system pressure and load pressure, and can perform pressure maintenance under quasi-static conditions of closed-loop pressure control, regardless of system pressure fluctuations. Needless to say, this applies only to fluid dynamics prerequisites primarily used to compensate for losses through the valve via a corresponding ΔP (as the pressure difference between system pressure and load pressure).

[0028] In this way, advantageously, the volumetric flow rate and / or pressure will not exceed the specific requirements of the entire working unit in terms of functionality, energy, efficiency, and cost-effectiveness. For this purpose, the volumetric flow rate and / or pressure of the central drive are divided among the working units. In doing so, advantageously, the influence of the working units on each other is minimized, and the volumetric flow rate and / or pressure of each working unit can always be limited by closed-loop control and / or independently of other working units.

[0029] Typically, when using this type of closed-loop control valve and corresponding controller, the advantageous result is that the entire pressure supply has significantly faster adjustability and dynamic response.

[0030] For example, for at least two simultaneous, unaffected work unit movements, an optimal system pressure is achieved by creating a superposition through a central drive and correspondingly activating the central drive via closed-loop control by a controller. This optimal system pressure corresponds to the maximum pressure requirement of at least two simultaneously operable work units, and the closed-loop control has calibration for the amount of superposition (motor speed) and system pressure.

[0031] Preferably, the closed-loop control valve controls each of the multiple working units. As a result, advantageously, accurate and precise pre-control of the setpoint values ​​can be achieved for all working units even when they move simultaneously, and this contributes to the quality of the injection-molded parts to be produced.

[0032] Preferably, the closed-loop valve control and / or open-loop valve control have stored information about the hydraulic medium used, advantageously allowing for accurate and precise pre-control of the setpoint value. For example, viscosity plays a significant role in laminar flow within the valve slide clearance and has an impact on volumetric flow applied near the zero point (overlap edge). Preferably, the closed-loop valve control and / or open-loop valve control store information such as the exact relationship between pressure or pressure differential, the setting of the closed-loop control valve, and the volumetric flow rate associated with the hydraulic medium used.

[0033] For example, in injection molding machines, hydraulic fluid is typically distributed to the working units via compressible volume components (such as hoses). This results in a certain hydraulic storage action or capacity that helps the system overcome sudden changes in load, such as when a working unit passes an abutment element, or in the closed-loop control dynamics at a second working unit, without affecting the working unit itself being controlled. Similarly, the compressible dead volume of the central actuator and controller (always present in the actual equipment) can rapidly and energy-efficiently reduce and increase the volumetric throughput of the pressure supply by observing the system pressure directly at the pressure supply, with its dynamics being slower than those of the closed-loop control valves in response to pressure / quantity.

[0034] If the closed-loop valve control and / or open-loop valve control are preferably located within or on the closed-loop control valve, it is advantageous to improve the modularity of the equipment construction. As a result, the closed-loop control valve advantageously "identifies" itself, so that calibration is not required when the closed-loop control valve changes. However, in principle, the closed-loop valve control and / or open-loop valve control can also be located in different locations, such as within or on the controller. It is also conceivable that the controller is or includes the closed-loop valve control and / or open-loop valve control.

[0035] Preferably, at least one temperature sensor, such as a temperature detector, is provided, which results in the advantageous and accurate prediction of the viscosity of the hydraulic medium, and thus more accurate flow. More preferably, at least one temperature sensor is provided for each closed-loop control valve. Advantageously, this results in the more accurate determination of the viscosity of each working unit branch.

[0036] Since injection molding machines are typically constructed individually and in a modular fashion, it is also advantageous to enhance the modularity of the equipment construction if the pressure sensor is preferably located in or on the closed-loop control valve. If, for example, the valve is replaced due to reconfiguration, further reconfiguration is advantageously unnecessary.

[0037] In principle, preferably, each closed-loop control valve may have a pressure sensor, a temperature sensor, and / or closed-loop valve controls and / or open-loop valve controls.

[0038] Preferably, the control valve geometry of the closed-loop control valve is the spool geometry of the valve slider. As a result, and given that such geometry is known, reliable, cost-effective, and energy-efficient closed-loop control is possible in terms of dividing the supply flow, such as volumetric flow rate.

[0039] Furthermore, this objective is achieved through the method of the present invention. To improve upon existing solutions in terms of functionality, energy efficiency, and cost-effectiveness, and for open-loop and / or closed-loop control of a hydraulic device (used to supply multiple working units, particularly multiple working units on a plastic injection molding machine, the hydraulic device including at least one controller and a central actuator (e.g., a pump)), at least one closed-loop control valve is provided at each of at least one working unit. For each closed-loop control valve, at least one pressure difference is determined from at least one pressure detected upstream and downstream of the closed-loop control valve; at least one actual value of the volumetric flow rate for each closed-loop control valve is derived from the relationship between the control valve geometry and the pressure difference of the closed-loop control valve; and at least one setpoint pre-control for the central actuator is derived from the setpoint value of the volumetric flow rate of at least one working unit and / or the actual value of the volumetric flow rate of at least one closed-loop control valve, such that the system pressure at least corresponds to the maximum load pressure of the working unit. In this context, system pressure at least corresponding to the maximum load pressure means that the system pressure is greater than or equal to the load pressure, and may even exceed that load pressure, for example, a certain value.

[0040] Preferably, the operating commands for standardizing at least one closed-loop control valve and / or the flow rate and / or volumetric flow rate of the working unit are set independently of the system pressure and / or load pressure of at least one working unit, so that advantageously, the desired volumetric flow rate can be set or controlled according to characteristics via closed-loop control. Thus, the result is, for example, that the flow rate or volumetric flow rate is standardized according to the control variables.

[0041] Preferably, the closed-loop control valve controls the pressure of each of the multiple working units. As a result, advantageously, accurate and precise pre-control of the setpoint values ​​can be achieved for all working units, even when the working units are moving simultaneously, and this contributes to the quality of the injection-molded parts to be produced.

[0042] To advantageously provide rapid adjustability and precise flow rate delivery, time control and / or real-time pre-control of the setpoint value are preferably utilized. For example, setpoint pre-control can be performed in real-time using the working unit's time control based on the setpoint value of the volumetric flow rate of the working unit and / or based on the actual value of the volumetric flow rate of the closed-loop control valve. In this context, the term "time coordination" means that the setpoint value of the volumetric flow rate is available to the working unit at a specific point in time through setpoint pre-control. For example, setpoint pre-control can advantageously provide appropriate setpoint pre-control in real-time based on the actual value of the volumetric flow rate, even if the closed-loop control valve is undergoing closed-loop pressure control and therefore the volumetric flow rate of the closed-loop control valve does not (only) depend on the setpoint value of the volumetric flow rate.

[0043] To advantageously identify leaks at a work unit, preferably, at least one cycle integral of the standardized volumetric flow rate controlled by the closed-loop control valve is performed over at least one work unit cycle. The presence of a leak can then be determined from the integral, for example, by comparison with previous work unit cycles.

[0044] To advantageously identify wear on the valve mechanism, such as at the control edge or in the case of leakage through the piston, for at least one cycle of machine operation, the actual value of the volumetric flow rate of the closed-loop control valve is preferably continuously monitored, evaluated, and correlated with the actual volumetric flow rate. For example, conclusions about wear can be drawn by comparing it with earlier working cell cycles.

[0045] For advantageously energy-optimized operation, and for improvements applied to simultaneous or greater dynamic and reproducible demands, at least one closed-loop control valve preferably operates as a switching valve during the tandem movement of at least one working unit, and / or as a load-sensing closed-loop control valve during the simultaneous movement of the working units. Advantageously, the working units can therefore be directly operated by the controller and the central unit during the injection molding cycle. For example, the closed-loop control valve is switched to maximum flow or closed by the controller as a switching valve. Since there is no fluid mechanical pressure gauge, substantially the same energy efficiency as a purely tandem pump system with sequential valves for the working units is advantageously achieved in tandem operation.

[0046] To advantageously optimize the dynamics and energy consumption of each cycle, the derivation of the setpoint pre-control is preferably adapted to self-optimization via a cycle learning observer. For example, the superposition of pressures in the system loop can be adapted to optimize the dynamics and energy consumption / cycle via self-optimization via a cycle learning observer, while observing the quantities of closed-loop control in the working unit loop, particularly the pressure overshoot and undershoot occurring in the working unit loop.

[0047] Preferably, regarding repetitive cyclic movements during uninterrupted operation, the controller can generate one or more observers, such as digital observers, in real time to perform real-time or cyclic monitoring of the status of the central drive, peripheral devices, and working units. Advantageously, this results in very accurate leak identification.

[0048] Further advantages will become apparent from the following description of the dependent claims and preferred exemplary embodiments. Features individually mentioned in the claims are combinable, where this is technically meaningful, and can be supplemented by explanatory factual material from the description and details from the drawings, which indicate further variations of the invention. Attached Figure Description

[0049] The invention will now be explained in more detail with reference to exemplary embodiments shown in the accompanying drawings, in which: Figure 1 A hydraulic device with two working units is shown. Figure 2 Showing from Figure 1 A hydraulic device with two closed-loop control valves. Figure 3 Showing from Figure 1 A hydraulic device with a closed-loop control valve. Figure 4a The graph shows the volumetric flow rate over time for two working cells without pre-control, according to the prior art. Figure 4b Showing from Figure 4a The curve with pre-control, and Figure 5 A schematic flowchart of the method is shown. Detailed Implementation

[0050] The invention will now be explained in more detail by way of example with reference to the accompanying drawings. However, the exemplary embodiments are examples and are not intended to limit the inventive concept to a particular arrangement. Before describing the invention in detail, it should be noted that the invention is not limited to the corresponding structural parts of the apparatus and the corresponding method steps, as these structural parts and methods can vary. The terminology used herein is intended only to describe particular embodiments and is not intended to be limiting. Furthermore, where the singular or indefinite article is used in the specification or claims, the singular or indefinite article also refers to a plurality of these elements unless the overall context clearly indicates otherwise.

[0051] Figure 1 A hydraulic unit is shown for supplying multiple working units (two working units 3a and 3b in an exemplary embodiment, such as ejectors, nozzles, core pullers, or nozzle shut-off devices), particularly multiple working units on a plastic injection molding machine. The hydraulic unit has at least one controller 7, at least one closed-loop valve control and / or open-loop valve control, and a central actuator 1. The controller 7 may include closed-loop valve controls and / or open-loop valve controls, and vice versa. This plastic injection molding machine is used to process plastics and other plasticizable materials, including, for example, ceramics, metals, and / or powder compositions.

[0052] like Figure 1 As shown, the central drive 1 may include a pump 4 (such as a constant flow pump), a motor 5 (such as a servo motor), and a motor controller 6. However, in principle, additional working units 3a and 3b may also be provided. Figure 1 In this system, for each working unit 3a and 3b, there are corresponding switching valves 12a and 12b and corresponding closed-loop control valves 2a and 2b. Figure 1 In the exemplary embodiments, the closed-loop control valves 2a and 2b take the form of, for example, electronic and / or digital closed-loop flow control valves, p / Q valves with electric pressure gauge functions, proportional valves, or continuously adjustable valves, which control the volumetric flow rate to the working units 3a and 3b through closed-loop control.

[0053] For each closed-loop control valve 2a, 2b, pressure sensor 8 detects at least one pressure upstream and downstream of the corresponding closed-loop control valve 2a, 2b, the load pressures 10a, 10b of the working units 3a, 3b, and the system pressure 9. These pressures can preferably be transmitted to the controller 7 and / or the closed-loop valve control and / or the open-loop valve control, preferably via a connection 21 such as a bus. However, other connections 21 are also conceivable in principle, such as a wireless network. The closed-loop control valves 2a, 2b are preferably in contact with the controller 7 and the central actuator 1 and / or the closed-loop valve control and / or the open-loop valve control via connection 21.

[0054] The closed-loop valve control and / or open-loop valve control has stored information about the control valve geometry of the closed-loop control valves 2a and 2b. This stored information may take the form of, for example, control characteristics, volumetric flow rate signal characteristics, or the function “cross-section of opening = f(stroke)”, or actually the geometry of the valve slider. In principle, this stored information is conceivable to already exist in the closed-loop valve control and / or open-loop valve control, or to be manually entered or automatically retrieved (e.g., via a network connection). The closed-loop valve control and / or open-loop valve control is configured to derive at least one actual value of the volumetric flow rate for each closed-loop control valve 2a and 2b from the relationship between the control valve geometry and at least one pressure difference obtained from pressures detected upstream and downstream of at least one closed-loop control valve 2a and 2b.

[0055] Typically, multiple closed-loop control valves are provided, even when... Figure 3 Only one p / Q valve is provided as the closed-loop control valve 2a, and a switching valve 12a plus a switching valve 12b are provided in the central drive circuit for pure series motion.

[0056] Even in this case, not all work units (or in) Figure 3 Even with only one working unit equipped with a closed-loop control valve, the device and method according to the invention can be advantageously implemented. One working unit can be supplied, for example, by switching valves. This could be a working unit that closes the nozzle; however, the switching process of this working unit has a systemic effect on other working units. For example, if this is in pressure-maintaining mode, pre-control requires a minimum pressure for such simultaneous actuation.

[0057] The closed-loop valve control and / or open-loop valve control store information about the exact relationship between pressure and the settings of closed-loop control valves 2a and 2b. As a result, the closed-loop valve control and / or open-loop valve control know which pressure causes which setting of the closed-loop control valve, and vice versa.

[0058] exist Figure 1In an exemplary embodiment, the closed-loop control valves 2a and 2b include closed-loop valve controls and / or open-loop valve controls, as well as stored information on the control valve geometry of the closed-loop control valves 2a and 2b (including the geometry of the valve slider), and are in the form of electronic and / or digital proportional valves. The closed-loop control valves 2a and 2b derive the actual value of the volumetric flow rate, preferably a standardized actual value of the volumetric flow rate, from the relationship between the control valve geometry and the pressure difference, and transmit this actual value of the volumetric flow rate to the controller 7.

[0059] The controller 7 is configured to derive at least one setpoint pre-control for the central actuator 1 from the setpoint values ​​of the volumetric flow rates of the working units 3a and 3b and / or the actual values ​​of the volumetric flow rates of the closed-loop control valves 2a and 2b, such that the system pressure 9 corresponds at least to the maximum load pressure of the working units 3a and 3b. Therefore, the system pressure can be equal to the load pressure or even greater than the load pressure by a certain value.

[0060] In this way, at least one closed-loop control valve 2a, 2b can correct the physically normalized flow rate (e.g., in liters per minute) at working units 3a, 3b according to a predetermined setpoint value, regardless of system pressure 9 and load pressures 10a, 10b, and can perform a pressure maintenance function under quasi-static conditions of closed-loop pressure control, regardless of system pressure fluctuations. It goes without saying that this applies as long as the fluid dynamics prerequisites are primarily used to compensate for losses through the valves via the corresponding ΔP between system pressure 9 and load pressures 10a, 10b. In this way, at least one closed-loop control valve 2a, 2b can be used to set the normalized operating commands and / or normalized flow rates and / or normalized volumetric flow rates of working units 3a, 3b independently of system pressure 9 and / or the load pressure of at least one working unit.

[0061] Examples should be used to explain this in more detail.

[0062] As an example, two types of valves are used, where the first valve has a nominal maximum volumetric flow rate of, for example, 180 liters / minute, and the second valve has a nominal maximum volumetric flow rate of, for example, 140 liters / minute. In this example, with linearization characteristics and a 50% control variable, the first valve will be adjusted to a volumetric flow rate of 90 liters / minute, and with a 50% control variable, the second valve will be adjusted to a volumetric flow rate of 70 liters / minute, provided that sufficient supply pressure is present.

[0063] In this context, the term "standardization" for standardizing volumetric flow rate and / or standardizing velocity means that the setpoint value for volumetric flow rate and / or velocity is preset to, for example, 80 liters / minute, and both valves are adjusted to this volumetric flow rate of 80 liters / minute regardless of pressure fluctuations and the nominal maximum volumetric flow rate. Therefore, the result is that the flow rate or volumetric flow rate is standardized according to the control variables and independent of the load pressure and system pressure. Therefore, preferably, the result is that, for example, when using different valves or actually if other system components are replaced, no new closed-loop / open-loop controls need to be implemented.

[0064] In principle, variables other than volumetric flow rate or flow rate can also be standardized, as long as the corresponding related variables can be set in a standardized manner and scaled through operation commands.

[0065] In this context, the term "standardized operating command" refers to, for example, a command that can set a standardized volumetric flow rate and / or velocity. For instance, a variable to be standardized can be mapped to (standardized to) a volumetric flow rate, such as in liters per minute, so that the desired volumetric flow rate can be set or controlled by closed-loop control (e.g., by characteristics), regardless of the valves used (system and load pressure).

[0066] In a further preferred exemplary embodiment, the closed-loop valve control and / or the open-loop valve control have stored information about the hydraulic medium used (such as the viscosity of the hydraulic medium). That is, based on the medium, corresponding pressure and valve settings are generated, advantageously resulting in more precise pre-control.

[0067] Therefore, advantageously, when the closed-loop control valves 2a, 2b, 13a, 13b are replaced, recalibration is not required. In a further preferred exemplary embodiment, the closed-loop valve control and / or the open-loop valve control are disposed in or on the closed-loop control valves 2a, 2b, 13a, 13b.

[0068] In a further preferred exemplary embodiment, at least one temperature sensor is provided, and more preferably, at least one temperature sensor, such as a temperature detector, is provided for each closed-loop control valve 2a, 2b, 13a, 13b. Advantageously, measuring the temperature of the hydraulic medium yields accurate predictions of its viscosity, and thus more accurate flow.

[0069] In a further preferred exemplary embodiment, the pressure sensor 8 is disposed in or on the closed-loop control valves 2a, 2b, 13a, 13b, thereby obtaining the advantage of reconfiguring the machine so that special reconfiguration measures are not required.

[0070] Figure 2 The exemplary implementations are basically corresponding to Figure 1An exemplary implementation, wherein in Figure 2 Switching valves 12a and 12b are not present. Figure 2 The closed-loop control valves 13a and 13b are, for example, continuously adjustable valves with directional function.

[0071] Figure 3 The exemplary implementations are basically corresponding to Figure 1 An exemplary implementation, wherein in Figure 3 In this configuration, only one p / Q valve is provided as the closed-loop control valve 2a, and a switching valve 12a plus a switching valve 12b are provided in the central drive circuit for purely series motion. Therefore, in this case, the closed-loop control valve is associated with only one working unit 3a.

[0072] exist Figure 4a The graph illustrates the variation of flow rates (in cubic meters per second) over time (in seconds) for two working units 3a and 3b without pre-control, according to the prior art. First, working unit 3a accelerates under high load pressure until time point E1, at which point the second working unit 3b accelerates under lower load pressure. Due to the acceleration of the second working unit 3b, a bend appears in the flow rate of the first working unit 3a (shown schematically enlarged), as the second working unit 3b now also requires a corresponding flow rate. At time point E2, the first working unit 3a decelerates, resulting in the first working unit requiring a smaller flow rate, which can be seen as "overshoot" in the second working unit 3b. Therefore, the two working units 3a and 3b significantly influence each other, potentially leading to errors during the operation and variations in the quality of the injection-molded parts.

[0073] Figure 4b It shows the relationship with Figure 4a A similar graph, but with pre-control of the setpoint of the central drive 1 by the controller 7. It can be seen that at time points E1 and E2, the influence of the two working units 3a and 3b on each other is significantly smaller.

[0074] Figure 5A schematic flowchart of a method for open-loop and / or closed-loop control of a hydraulic system for supplying multiple working units 3a, 3b, particularly multiple working units on a plastic injection molding machine, is shown. The hydraulic system has at least one controller 7 and a central actuator 1, wherein at least one closed-loop control valve 2a, 2b, 13a, 13b is located at at least one working unit, preferably at all working units 3a, 3b. In step 50, for each closed-loop control valve 2a, 2b, 13a, 13b, at least one pressure difference is determined from at least one pressure detected upstream and downstream of the closed-loop control valve 2a, 2b, 13a, 13b. In a further step 51, for each closed-loop control valve 2a, 2b, 13a, 13b, at least one actual value of the volumetric flow rate is derived from the relationship between the geometry of the closed-loop control valve and the pressure difference of the closed-loop control valve 2a, 2b, 13a, 13b. In step 52, at least one setpoint pre-control for the central drive 1 is derived from the setpoint values ​​of the volumetric flow rates of at least one working unit 3a, 3b and / or the actual values ​​of the volumetric flow rates of closed-loop control valves 2a, 2b, 13a, 13b, such that the system pressure 9 corresponds at least to the maximum load pressures 10a, 10b of the working units 3a, 3b and / or exceeds those maximum load pressures by a certain value. This value can be, for example, manually input or have an automatic relationship, such as via a network.

[0075] In a preferred exemplary embodiment, time control and / or real-time pre-control of the setpoint value are utilized.

[0076] To advantageously identify leaks, in a further preferred exemplary embodiment, a cyclic integral of a standardized volumetric flow rate controlled by closed-loop control valves 2a, 2b, 13a, 13b is performed on at least one working unit cycle. The integral can then reveal whether more hydraulic fluid has been used, indicating the presence of a leak.

[0077] In a further preferred exemplary embodiment, in order to advantageously identify wear of the valve mechanism, such as at the control edge or in the case of leakage through the piston, for at least one cyclic machine operation, the actual values ​​of the volumetric flow rates of the closed-loop control valves 2a, 2b, 13a, 13b are continuously monitored, evaluated, and correlated with the actual values ​​of the volumetric flow rates.

[0078] In order to perform the series movement of working units 3a and 3b, in a preferred exemplary embodiment, closed-loop control valves 2a, 2b, 13a, and 13b operate as switching valves 12a and 12b, and / or in order to perform the simultaneous movement of working units 3a and 3b, the closed-loop control valves operate as load-sensing closed-loop control valves.

[0079] In a further preferred exemplary embodiment, the calculation of the setpoint pre-control is adapted to self-optimization via a cyclic learning observer. Advantageously, the optimal values ​​of dynamics and energy consumption for each cycle can be obtained via the cyclic learning observer. Thus, the superposition of pressures in the system loop can be adapted to self-optimization while observing the quantities of closed-loop control in the working unit loop, particularly the overshoot and undershoot of pressures occurring in the working unit loop.

[0080] It goes without saying that this description is open to the most diverse modifications, alterations and adjustments that fall within the scope of equivalents of the appended claims.

[0081] List of reference numerals

[0082] 1 Central drive

[0083] 2a Closed-loop control valve

[0084] 2b Closed-loop control valve

[0085] 3a Working Unit

[0086] 3b Working Unit

[0087] 4 pumps

[0088] 5 motors

[0089] 6. Motor controller

[0090] 7 Controller

[0091] 8. Pressure sensor

[0092] 9. System Pressure

[0093] 10a load pressure

[0094] 10b Load pressure

[0095] 11. Volumetric Flow Rate

[0096] 12a Switching valve

[0097] 12b Switching valve

[0098] 13a Closed-loop control valve

[0099] 13b Closed-loop control valve

[0100] 20 dead volume

[0101] 21 Connections

[0102] 50 steps

[0103] 51 steps

[0104] 52 steps

Claims

1. A hydraulic device for supplying multiple work units (3a, 3b), the hydraulic device comprising at least one controller (7), at least one closed-loop valve control or open-loop valve control, and a central actuator (1), wherein, At least one closed-loop control valve (2a, 2b, 13a, 13b) having a control valve geometry is associated with at least one working unit, and wherein a pressure sensor (8) is provided, the pressure sensor being configured to detect for each closed-loop control valve (2a, 2b, 13a, 13b) at least one pressure upstream and downstream of the closed-loop control valve (2a, 2b, 13a, 13b), the load pressure (10a, 10b) of the working unit (3a, 3b), and the system pressure (9). Wherein, at least one of the closed-loop valve controls or at least one of the open-loop valve controls has stored information on the control valve geometry of the closed-loop control valves (2a, 2b, 13a, 13b), and is configured to derive at least one actual value of the volumetric flow rate for each closed-loop control valve (2a, 2b, 13a, 13b) from the relationship between the control valve geometry and at least one pressure difference obtained from pressures detected upstream and downstream of the closed-loop control valves (2a, 2b, 13a, 13b). The controller (7) is configured to derive at least one setpoint pre-control for the central drive (1) from the setpoint of the volumetric flow rate of at least one working unit (3a, 3b) and at least one actual value of the volumetric flow rate of the at least one closed-loop control valve (2a, 2b, 13a, 13b), such that the system pressure (9) corresponds at least to the maximum load pressure (10a, 10b) of the working unit (3a, 3b). The closed-loop control valves (2a, 2b, 13a, 13b) can be used independently of the system pressure (9) and the load pressure (10a, 10b) of the at least one working unit (3a, 3b) to set at least one of the standardized operating commands, standardized flow rates, or standardized volumetric flow rates of the at least one working unit (3a, 3b).

2. The hydraulic device according to claim 1, wherein, The corresponding closed-loop control valves (2a, 2b, 13a, 13b) are associated with each working unit (3a, 3b).

3. The hydraulic device according to claim 1, wherein, The closed-loop valve control or the open-loop valve control is disposed in or on the closed-loop control valve (2a, 2b, 13a, 13b).

4. The hydraulic device according to claim 1, wherein, The closed-loop valve control or the open-loop valve control has stored information about the hydraulic medium used.

5. The hydraulic device according to claim 1, wherein, At least one temperature sensor is provided for each closed-loop control valve (2a, 2b, 13a, 13b), wherein the at least one temperature sensor is disposed in or on the closed-loop control valve (2a, 2b, 13a, 13b).

6. The hydraulic device according to claim 1, wherein, The pressure sensor (8) is disposed in or on the closed-loop control valve (2a, 2b, 13a, 13b).

7. The hydraulic device according to claim 1, wherein, The control valve geometry of the closed-loop control valves (2a, 2b, 13a, 13b) includes the slide valve geometry of the valve slider.

8. The hydraulic device according to claim 1, wherein, The hydraulic device is a hydraulic device on a plastic injection molding machine used to process plastics and other plasticizable materials.

9. A method for open-loop or closed-loop control of a hydraulic device for supplying multiple working units (3a, 3b), the hydraulic device comprising at least one controller (7) and a central drive (1), wherein, At least one closed-loop control valve (2a, 2b, 13a, 13b) is associated with at least one working unit (3a, 3b) and includes a control valve geometry, wherein, - For each closed-loop control valve (2a, 2b, 13a, 13b), in each case, at least one pressure difference is determined from at least one pressure detected upstream and downstream of said closed-loop control valve (2a, 2b, 13a, 13b). - Derive at least one actual value for the volumetric flow rate for each closed-loop control valve (2a, 2b, 13a, 13b) from the relationship between the control valve geometry and the pressure difference between the closed-loop control valves (2a, 2b, 13a, 13b). - At least one setpoint pre-control for the central actuator (1) is derived from at least one setpoint of the volumetric flow rate of the at least one working unit (3a, 3b) and / or at least one actual value of the volumetric flow rate of the at least one closed-loop control valve (2a, 2b, 13a, 13b), such that the system pressure (9) corresponds at least to the maximum load pressure (10a, 10b) of the working unit (3a, 3b); wherein the at least one closed-loop control valve (2a, 2b, 13a, 13b) is used to set at least one of the standardized operating commands, standardized flow rates, or standardized volumetric flow rates of the at least one working unit (3a, 3b) independently of the system pressure (9) and the load pressure (10a, 10b) of the at least one working unit (3a, 3b).

10. The method according to claim 9, wherein, The corresponding closed-loop control valves (2a, 2b, 13a, 13b) control the pressure of each working unit (3a, 3b).

11. The method according to claim 9, wherein, The setpoint pre-control is performed using time control and / or in real time.

12. The method according to claim 9, wherein, At least one cyclic integral of the standardized volumetric flow rate controlled by the closed-loop control valves (2a, 2b, 13a, 13b) is performed on at least one working unit cycle.

13. The method according to claim 9, wherein, For at least one cyclic machine operation, the actual value of the volumetric flow rate of the closed-loop control valves (2a, 2b, 13a, 13b) is continuously monitored, evaluated, and correlated with the actual value of the volumetric flow rate.

14. The method according to claim 9, wherein, The at least one closed-loop control valve (2a, 2b, 13a, 13b) operates as a switching valve (12a, 12b) during the series movement of the working unit (3a, 3b).

15. The method according to claim 9, wherein, The at least one closed-loop control valve (2a, 2b, 13a, 13b) operates as a load-sensing closed-loop control valve during the simultaneous movement of the working unit (3a, 3b).

16. The method according to claim 9, wherein, The derivation of the setpoint pre-control is adapted to self-optimization through a cyclic learning observer.

17. The method according to claim 9, wherein, The hydraulic system supplies power to multiple work units on a plastic injection molding machine used for processing plastics and other plasticizable materials.

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