US-12623389-B2 - Hydraulic device and method for regulating a hydraulic device

US12623389B2US 12623389 B2US12623389 B2US 12623389B2US-12623389-B2

Abstract

The invention relates to a hydraulic device for supplying a plurality of work units ( 3 a, 3 b ), in particular on a plastics injection moulding machine, said device comprising at least one controller ( 7 ), at least one valve regulator and/or one valve controller and a central drive ( 1 ). A regulating valve ( 13 a, 13 b ) with a regulating-valve geometry is provided on at least one of the work units ( 3 a, 3 b ). Pressure sensors ( 8 ) detect at least one pressure both upstream and downstream of the regulating valve ( 13 a, 13 b ), the load pressure ( 10 a, 10 b ) of at least one of the work units ( 3 a, 3 b ), and the system pressure ( 9 ). Since the valve regulator and/or the valve controller has knowledge about the regulating-valve geometry of the at least one regulating valve ( 13 a, 13 b ) and is designed to derive, from a relationship between the regulating-valve geometry and at least one pressure difference resulting from the pressures detected upstream and downstream of the regulating valve ( 13 a, 13 b ), at least one volume flow rate actual value per regulating valve ( 13 a, 13 b ), and the controller ( 7 ) is designed to derive, from the volume flow rate setpoint values of the at least one work unit ( 3 a, 3 b ) and/or the volume flow rate actual values of the at least one regulating valve ( 13 a, 13 b ), at least one setpoint value feedforward control for the central drive ( 1 ) in such a way that the system pressure ( 9 ) corresponds at least to the relevant highest load pressure ( 10 a, 10 b ) of the work units ( 3 a, 3 b ), the hydraulic device is improved in terms of functionality, energy, efficiency and economy.

Inventors

Eberhard Duffner
Walter Fest

Assignees

ARBURG GMBH + CO KG

Dates

Publication Date: 20260512
Application Date: 20220221
Priority Date: 20210224

Claims (17)

1 . A hydraulic device for supplying a plurality of work units, comprising a controller, at least one of a closed-loop valve control or an open-loop valve control, and a central drive, wherein there is associated with at least one of the work units at least one closed-loop control valve having a control valve geometry, wherein pressure sensors are provided which are configured to detect for each closed-loop control valve at least one pressure upstream and downstream of the closed-loop control valve, a load pressure of the work units and a system pressure, wherein the at least one of the at least one of the closed-loop valve control or the open-loop valve control has knowledge of the control valve geometry of the closed-loop control valves and is configured to derive at least one actual value of volumetric flow for each closed-loop control valve from a relationship between the control valve geometry and at least one pressure difference that results from a pressure detected upstream and a pressure detected downstream of the closed-loop control valves, and wherein the controller is configured to derive, from a setpoint of volumetric flow of the at least one of the work units and from the at least one actual value of volumetric flow of the at least one closed-loop control valve, at least one setpoint pre-control for the central drive, such that the system pressure corresponds at least to a maximum load pressure of the work units, wherein the closed-loop control valves can be used to set at least one of standardized operation commands, standardized flow rates, or standardized volumetric flows, of the at least one of the work units independently of the system pressure and the load pressure of the at least one of the work units.
2 . Hydraulic device as claimed in claim 1 , wherein the respective closed-loop control valve is associated with each work unit ( 3 a , 3 b ).
3 . Hydraulic device as claimed in claim 1 , wherein the closed-loop valve control or the open-loop valve control is provided in or on the closed-loop control valve ( 2 a , 2 b , 13 a , 13 b ).
4 . Hydraulic device as claimed in claim 1 , wherein the closed-loop valve control or the open-loop valve control has knowledge of the hydraulic medium used.
5 . Hydraulic device as claimed in claim 1 , wherein at least one temperature sensor is provided, preferably in that at least one temperature sensor is provided for each closed-loop control valve ( 2 a , 2 b , 13 a , 13 b ), and in that the at least one temperature sensor is provided in or on the closed-loop control valve ( 2 a , 2 b , 13 a , 13 b ).
6 . Hydraulic device as claimed in claim 1 , wherein the pressure sensors ( 8 ) are provided in or on the closed-loop control valve ( 2 a , 2 b , 13 a , 13 b ).
7 . Hydraulic device as claimed in claim 1 , wherein the control valve geometry of the closed-loop control valves ( 2 a , 2 b , 13 a , 13 b ) comprises the slide-valve geometry of the valve slide.
8 . Hydraulic device as claimed in claim 1 , wherein the hydraulic device is a hydraulic device on a plastics injection molding machine for processing plastics and other plasticizable materials.
9 . A method for open-loop or closed-loop control of a hydraulic device for supplying a plurality of work units as claimed in claim 1 , wherein for each closed-loop control valve at least one pressure difference is determined from at least one detected pressure upstream and downstream of the closed-loop control valve, at least one actual value of volumetric flow for each closed-loop control valve is derived from a relationship between the control valve geometry and the pressure difference of the closed- loop control valve, at least one setpoint pre-control for the central drive is derived from at least one setpoint of volumetric flow of the at least one of the work units and the at least one actual value of volumetric flow of the at least one closed-loop control valve, such that a system pressure corresponds at least to a maximum load pressure of the work units, wherein the at least one closed-loop control valve is used to set at least one of standardized operation commands or standardized flow rates or standardized volumetric flows of the at least one of the work units independently of the system pressure and the load pressure of the at least one of the work units.
10 . Method as claimed in claim 9 , wherein a respective closed-loop control valve controls the pressure of each work unit.
11 . Method as claimed in claim 9 , wherein the setpoint pre-control is carried out with time control or in real time.
12 . Method as claimed in claim 9 , wherein at least one cyclic integration of the standardized volumetric flows that are controlled by the closed-loop control valves is carried out over at least one work unit cycle.
13 . Method as claimed in claim 9 , wherein the actual values of volumetric flow of the closed-loop control valves are continuously monitored, evaluated and correlated with the actual values of volumetric flow for at least one cyclic machine operation.
14 . Method as claimed in claim 9 , wherein the at least one closed-loop control valve is operated as a switching valve during serial movements of the work units.
15 . Method as claimed in claim 9 , wherein the at least one closed-loop control valve is operated as a load-sensing closed-loop control valve during simultaneous movements of the work units.
16 . Method as claimed in claim 9 , wherein a derivation of the setpoint pre- control is adapted with self-optimization by a cyclically learning observer.
17 . Method as claimed in claim 9 , wherein the hydraulic device supplies a plurality of work units on a plastics injection molding machine for processing plastics and other plasticizable materials.

Description

CROSS REFERENCE TO RELATED APPLICATIONS The present application relates to and claims priority from German patent application 10 2021 104 398.0, filed on Feb. 24, 2021, the disclosure content of which is hereby incorporated by reference in its entirety. TECHNICAL FIELD The disclosure relates to a hydraulic device for supplying at least one work unit, in particular on a plastics injection molding machine and to a method for open-loop control and/or closed-loop control of a hydraulic device. BACKGROUND Even in modern—for example electromechanically driven—injection molding machines, hydraulic consumers or axes, such as ejectors, nozzle contact, core pullers, and shut-off nozzles, continue to be present and have to be supplied with energy by the injection molding machine. On the one hand, in the case of certain machine axes which most of the time work only in force-controlled operation, such as in the case of a nozzle contact function, an electromechanical drive has not proved suitable in terms of service life, and on the other hand, in particular in the mold area, hydraulic actuators offer major structural and economic advantages because of their high power density and low cost of installation. Similarly, for reasons of the compatibility of new machines with existing molds, an integrated supply of hydraulic power is required for new electromechanically driven and energy-optimized machines. DE 10 2009 020 111 A1 discloses a hydrostatic drive system that has a pump with load-sensing control and at least one consumer that is controllable by a control valve. An electronic pressure difference control is provided for closed-loop control of the flow volume of the pump, wherein a sensor device for detecting a pressure difference from the (maximum) load pressure of a plurality of consumers and the feed pressure of the pump is provided, wherein the control device adjusts the pump such that the pressure difference corresponds to a pre-set closed-loop control difference. Thus, a pre-set (that is to say fixed) closed-loop control pressure difference between a load pressure (preferably the maximum) and the feed pressure of the pump is closed-loop controlled. Thus, the input pressure and hence the pressure difference at the closed-loop control valve for the second or further consumers depend on the load pressure on the first or leading consumer, and so cannot be kept constant. The flow rate of the second or further consumer is thus not proportional to the cross section of opening of the valve and is thus not defined. Either a respective pressure gage is needed for the respective closed-loop control valve of the non-leading consumers, or the consumer needs a return conduit of a size appropriate to the flow rate in order to divide up the flow rate between the consumers as necessary. It is not apparent how dividing up the volumetric flows as necessary is performed. Only the sum of the flow rates is to correspond to the needs of all the consumers, because the leading pressure difference is maintained (and collapses in the event of under-supply). DE 10 2015 201 318 A1 discloses a hydraulic control arrangement for supplying compressed medium to at least two hydraulic consumers. An adjustable hydraulic pump is variable such that the pump pressure lies above, by a pump pressure difference, the maximum load pressure of the simultaneously activated hydraulic consumers. For this purpose, pressure gages are used for each closed-loop control valve. Here, the closed-loop pump control device is activated such that pressure drops in the pump conduit which differ in respect of the size of the pump pressure difference are taken into account, and the individual pressure gage that is associated with the hydraulic consumer having the highest load pressure is at least approximately completely opened if there are differing pressure drops in the pump conduit. EP 0 649 722 B2 discloses a hydraulic device for supplying a work unit on a plastics injection molding machine having at least one consumer. A pressure sensor detects actual pressure values and compares them with a setpoint pressure value, as a result of which a control variable for the closed-loop control member of the closed-loop control pump is delivered, for the purpose of a correcting control of the drop in operating pressure, as load sensing. The maximum output of the closed-loop control pump is predetermined by the frequency converter, on the basis of values predetermined for the respective injection cycle, in dependence on a further control variable that depends on quantity and pressure, wherein the pump output of the closed-loop control pump below its maximum output is actively controllable by the controller at the closed-loop control member, by the first control variable. DE 196 80 008 C1 discloses a device having at least one controlled hydraulically driven actuator, a hydraulic pump and an open or closed-loop control device. The open or closed-loop control device acts on the elect