Control arrangement and method for controlling a sensorless membrane pump
A control arrangement and method for controlling a sensor-free diaphragm pump are disclosed. The control arrangement comprises a control-fluid inlet for connection to a first control-fluid reservoir having a pressure level which is elevated in relation to a reference pressure, a control-fluid outlet for connection to a second control-fluid reservoir having a pressure level which is reduced in relation to a reference pressure, a control-fluid connection for connection of a control-fluid line for the sensor-free diaphragm pump, wherein the control-fluid inlet is connected via a first proportional valve to a collecting point, and the control-fluid outlet is connected via a second proportional valve to the collecting point, wherein a mass flow sensor is arranged between the collecting point and the control-fluid connection. A control unit is in signal communication to the first proportional valve, the second proportional valve and the mass flow sensor.
1 . A control arrangement for controlling a sensor-free diaphragm pump, the control arrangement comprising:
a control-fluid inlet for connection to a first control-fluid reservoir having a pressure level which is elevated in relation to a reference pressure;
a control-fluid outlet for connection to a second control-fluid reservoir having a pressure level which is reduced in relation to a reference pressure;
a control-fluid connection for connection to a control-fluid line for the sensor-free diaphragm pump, wherein the control-fluid inlet is connected via a first proportional valve to a collecting point, and the control-fluid outlet is connected via a second proportional valve to the collecting point, and wherein a mass flow sensor is arranged between the collecting point and the control-fluid connection; and
a control unit in signal communication with the first proportional valve, the second proportional valve, and the mass flow sensor, wherein the control unit is configured to control a control fluid flow based on data detected by the mass flow sensor, wherein for controlling the control fluid flow based on the data detected by the mass flow sensor the control unit is adapted to actuate the first proportional valve of the control arrangement for enabling throughflow, and conveying a first volume of a control fluid, close the first proportional valve when the first volume of a control fluid to be conveyed has been reached, actuate the second proportional valve for enabling throughflow, and conveying a second volume of a control fluid, and close the second proportional valve when the second volume of a control fluid to be conveyed has been reached,
wherein the control unit is further configured to determine the volumes to be conveyed of the control fluid, wherein determining the volumes to be conveyed comprises:
detecting a mass flow rate of the control fluid based on the data detected by the mass flow sensor,
deducing a volumetric flow rate from the mass flow rate, and
deducing a volume of the conveyed control fluid from the volumetric flow rate.
2 . The control arrangement as claimed in claim 1 , further comprising:
a pressure sensor arranged between the collecting point and the control-fluid connection.
3 . The control arrangement as claimed in claim 2 , wherein the pressure sensor is an absolute pressure sensor.
4 . The control arrangement as claimed in claim 3 , further comprising a temperature sensor and a temperature sensor interface for signal exchange with the temperature sensor for receiving data from the temperature sensor.
5 . The control arrangement as claimed in claim 4 , wherein the control unit is signal-connected to the pressure sensor and to the temperature sensor and to the temperature sensor interface.
6 . The control arrangement as claimed in claim 1 , wherein the control unit has a communication interface for data exchange with an external communication unit.
7 . A diaphragm pump arrangement having a sensor-free diaphragm pump and having the control arrangement as claimed in claim 1 .
8 . A bioreactor having the diaphragm pump arrangement as claimed in claim 7 .
9 . A bioreactor, the bioreactor comprising the diaphragm pump arrangement as claimed in claim 7 and a pressure sensor arranged between the collecting point and the control-fluid connection.
10 . A diaphragm pump for use with the control arrangement as claimed in claim 1 , wherein the diaphragm pump is free of a distance sensor for detecting a position of a diaphragm of the diaphragm pump.
11 . A bioreactor having the diaphragm pump as claimed in claim 10 .
12 . A bioreactor, the bioreactor comprising the diaphragm pump as claimed in claim 10 and a pressure sensor arranged between the collecting point and the control-fluid connection.
13 . A method for controlling a diaphragm pump with the control arrangement as claimed in claim 1 , the method comprising the steps of: actuating the first proportional valve of the control arrangement for enabling throughflow, and conveying the control fluid; closing the first proportional valve when the first volume to be conveyed has been reached; actuating the second proportional valve for enabling throughflow, and conveying the control fluid; and closing the second proportional valve when the second volume to be conveyed has been reached.
14 . The method as claimed in claim 13 , further comprising the step of determining the volume to be conveyed of the control fluid.
15 . The method as claimed in claim 14 , wherein determining the volume to be conveyed of the control fluid comprises the steps of:
detecting the mass flow rate of the control fluid;
deducing the volumetric flow rate from the mass flow rate; and
deducing the volume of the conveyed control fluid from the volumetric flow rate.
16 . The method as claimed in claim 13 , further comprising the steps of:
detecting a pressure of the control fluid; and
actuating the first or the second proportional valve in such a way that a predefined target pressure of the control fluid is not exceeded or a predefined target-pressure range is complied with or a predefined pressure gradient is complied with.
17 . The method as claimed in claim 13 , comprising the step of determining end positions of a diaphragm of the sensor-free diaphragm pump.
18 . The method as claimed in claim 17 , wherein determining the end positions of the diaphragm of the sensor-free diaphragm pump comprises the steps of:
conveying the control fluid at a predefined initialization volumetric flow rate;
detecting a pressure gradient of the control fluid; and
establishing a presence of an end position of the diaphragm when the pressure gradient changes.