METHOD FOR FINDING A TARGET CONVEYING CAPACITY OF A PUMPING SYSTEM

Abstract

A method of finding a target conveying capacity of a pumping includes a temperature-control flow through a temperature-control channel carried out according to a control variable by using a throttle as an actuating element such that a temperature-control volume flow remains substantially constant. A conveying flow of the pumping system is measured, and a pump starting from a starting conveying capacity independent of the control of the temperature-control volume flow is driven such that a conveying capacity of the pumping system is reduced to a reduced conveying capacity. Then, a check is made to find whether the conveying flow remains substantially constant and, if this is the case, the reduced conveying capacity is determined to be the target conveying capacity or. If this is not the case despite the control of the temperature-control volume flow, the starting conveying capacity is determined to be the target conveying capacity.

Claims

1. A method for finding a target conveying capacity of a pumping system having at least one pump for conveying a temperature-control medium through at least one temperature-control channel of a molding tool by means of the at least one pump, wherein a) a control at least of one temperature-control volume flow through the at least one temperature-control channel is carried out according to a control variable by using at least one throttle as an actuating element such that the at least one temperature-control volume flow remains substantially constant, b) a conveying flow of the pumping system is measured, c) the at least one pump starting from a starting conveying capacity independent of the control of the at least one temperature-control volume flow is driven such that a conveying capacity of the pumping system is reduced to a reduced conveying capacity, and d) then it is checked whether the conveying flow remains substantially constant and, i. if this is the case, the reduced conveying capacity is determined to be the target conveying capacity or, ii. if this is not the case despite the control of the at least one temperature-control volume flow, the starting conveying capacity is determined to be the target conveying capacity.

2. A method for finding a target conveying capacity of a pumping system having at least one pump for conveying a temperature-control medium though at least one temperature-control channel of a molding tool by means of the at least one pump, wherein a) a control at least of one temperature-control volume flow through the at least one temperature-control channel is carried out according to a control variable by using at least one throttle as an actuating element such that the at least one temperature-control volume flow remains substantially constant, b) a conveying flow of the pumping system is measured, c) the at least one pump starting from a starting conveying capacity independent of the control of the at least one temperature-control volume flow is driven such that a conveying capacity of the pumping system is increased to an increased conveying capacity, and d) then it is checked whether the conveying flow remains substantially constant and, i. if this is not the case despite the control of the at least one temperature-control volume flow, the increased conveying capacity is determined to be the target conveying capacity or, ii. if this is the case, the starting conveying capacity is determined to be the target conveying capacity.

3. The method as claimed in claim 1, wherein the measurement of the conveying flow of the pumping system is carried out by means of a sensor upstream and/or downstream of the pumping system.

4. The method as claimed in claim 1, wherein the measurement of the conveying flow of the pumping system is carried out as part of the control of the at least one temperature-control volume flow.

5. The method as claimed in claim 1, wherein the process steps c) and d) including i. and ii. are carried out repeatedly, wherein in each case the target conveying capacity from the preceding implementation is used as the starting conveying capacity.

6. The method as claimed in claim 5, wherein the process is terminated if the case ii. occurs.

7. The method as claimed in claim 1, wherein the process is started, if this is caused by an operator by inputting a starting conveying capacity and/or if the conveying capacity of the pumping system over a predetermined time period experiences no change.

8. The method as claimed in claim 1, wherein a plurality of throttles is used in a plurality of temperature-control channels, wherein the throttles are preferably controlled independently of one another.

9. A pumping system for conveying a temperature-control medium through at least one temperature-control channel of a molding tool, in particular, operated as claimed in claim 1, with at least one pump as well as a drive device for driving the at least one pump, which has a signal input for the measured values of a volume flow sensor for sensing a conveying capacity of the pumping system, characterized in that the drive device is designed, to drive the at least one pump starting from a starting conveying capacity independent of a separate control at least of one temperature-control volume flow according to a control variable such that a conveying capacity of the pumping system is reduced to a reduced conveying capacity, and then to check whether the conveying flow remains substantially constant and, i. if this is the case, to determine the reduced conveying capacity to be a target conveying capacity or, ii. if this is not the case, to determine the starting conveying capacity to be the target conveying capacity.

10. A pumping system for conveying a temperature-control medium through at least one temperature-control channel of a molding tool, in particular, operated as claimed in claim 1, with at least one pump as well as one drive device for driving the at least one pump, which has a signal input for measured values of a volume flow sensor for sensing a conveying capacity of the pumping system, where the drive device is designed, to drive the at least one pump starting from a starting conveying capacity independent of a separate control at least of one temperature-control volume flow according to a control variable such that a conveying capacity of the pumping system is increased to an increased conveying capacity, and then to check whether the conveying flow remains substantially constant and, i. if this is not the case, to determine the increased conveying capacity to be a target conveying capacity or, ii. if this is the case, to determine the starting conveying capacity to be the target conveying capacity.

11. The pumping system as claimed in claim 9, wherein a distributor is provided for distributing the conveying flow to severalpreferably parallel-connectedtemperature-control channels.

12. The pumping system as claimed in claim 11, wherein in each of the temperature-control channels a throttle is provided as an actuating element for the control of the at least one temperature-control volume flow.

13. A molding machine with a pumping system as claimed in claim 9.

14. The molding machine as claimed in claim 13, wherein the drive device is integrated into a central machine control of the molding machine or is designed separately from the central machine control.

15. The molding machine as claimed in claim 13, wherein a control device for control of the at least one temperature-control volume flow is integrated into the central machine control of the molding machine or is designed separately from the central machine control.

16. A temperature-control device with a pumping system as claimed in claim 9.

Description

[0057] Further advantages and details of the invention result by means of the figures as well as the associated figure descriptions.

[0058] FIG. 1 shows a rough overview of a pumping system according to the present invention together with a molding tool,

[0059] FIG. 2 shows a more detailed depiction of the embodiment according to FIG. 1 as well as

[0060] FIG. 3 a flow diagram for illustration of the method according to the present invention.

[0061] In FIG. 1 the pumping system 7, the distributor 1 as well as the molding tool 6 are depicted schematically. The pumping system 7 conveys temperature-control medium (for example, water, if necessary with additives) through the flow line 5 of the temperature-control channels through the molding tool 6 and back via the return line 4 of the temperature-control channels. Of course, the system can also be designed to be open, that is, with a tank. The drive device 8 is connected with the pumping system 7 via an interface 9. The drive device 8 drives the pumps 10 (see FIG. 2) of the pumping system 7 via the interface 9. Moreover, measured values are transmitted by volume flow sensors 11 (see also FIG. 2) via the interface 9 to the drive device 8. A control device 2 is assigned to the distributor 1. There is also an interface 3, via which the control device 2 receives measured values of the volume flow sensors in the temperature-control channels. The control device 2 uses the measured values of the volume flow sensors as returned variables for the control of the temperature-control volume flows. Throttles serve thereby as actuating elements, which are arranged in the temperature-control channels and are controlled independently from the pumping system and from one another.

[0062] In FIG. 2 the blocks from FIG. 1 are depicted in more detail.

[0063] In the present case the pumping system 7 has a pump 10 as well as volume flow sensors 11 for sensing the conveying flow of the pumping system 7.

[0064] Instead of the volume flow sensors 11, alternatively or additionally, upstream and downstream pressure sensors and/or temperature sensors could be used. Of course, any sensors can be used for sensing the conveying flow, which measure one or several variables, which are in a known physical and/or mathematical relationship to the conveying flow.

[0065] The measurement of the conveying capacity of the pumping system 7 can take place, for example, via the electrical power consumption of the drives of the pumps 10. Of course, it is also readily possible to measure both the conveying flow of the pumping system 7 as well as the pressure drop and to calculate the conveying capacity therefrom.

[0066] In the distributor 1 it is depicted how the flow line 5 of the temperature-control channels is divided into here purely by way of example four temperature-control channels. In the distributor 1, moreover, the return lines 4 are combined again into a single return line 4 and fed to the pumping system 7.

[0067] In the return line 4, moreover, the measuring devices and actuating elements (throttles) are provided for the control of the temperature-control volume flows. These are provided together with the reference sign 12. (The temperature-control volume flows themselves are used as control variables.)

[0068] In this embodiment the pumping system is part of a temperature-control device which is not depicted.

[0069] In FIG. 3 a flow diagram is depicted, which illustrates a method according to the present invention. In the initial state, a speed-regulated (alternatively: controlled) pump is operated, for example, with a starting conveying capacity (n.sub.(0)=100%).

[0070] Then the optimization is startedeither by an operator or automatically. It is noted that the first iteration of the method is carried out, or more generally that the method is in the iteration step i+1. This is indicated by i=i+1.

[0071] Then the conveying capacity is reduced by decreasing the rotational speed of the drive for the pump 10 by n. It is then checked whether the conveying flow V.sub.(i) experiences a reduction in the respective step. If this is not the case, a further iteration of the method can be started. If this is already the case, the optimization has ended and the rotational speed in the previous step is used to establish the target conveying capacity.

[0072] Of course, the method according to the present invention can be carried out not only with speed-controlled pumps. The changes of the conveying capacity of the pumping system can also take place with variable displacement pumps (then controlled and/or regulated according the pump speed and/or pump adjustment angle) or by switching off pumps of the pumping system.