Diaphragm pump for dosing a fluid capable of automatic degassing and an according method

Abstract

A diaphragm pump, in particular for use as a detergent dosage pump, comprises a pump head, a fluid chamber adjacent to the pump head, a diaphragm defining a wall of the fluid chamber and reciprocatingly movable, at least a suction check valve and a dosing check valve, a control unit, and a detector unit for detecting a fluid inside the fluid chamber. The diaphragm pump according to the invention offers increased process reliability.

Claims

1. A diaphragm pump, for use as a detergent dosage pump, comprising: a pump housing, the pump housing comprising a rigid wall and a flexible wall; a fluid chamber defined within the pump housing between the rigid wall and the flexible wall and having a fluid path inside the fluid chamber; a diaphragm defining the flexible wall of the fluid chamber, the diaphragm being reciprocatingly movable; and a detector unit for detecting a fluid inside the fluid chamber, the detector unit comprising: a pair of electrodes located outside the fluid chamber, thereby outside the fluid path inside the fluid chamber, and being positioned within the pump housing proximate the rigid wall and closer to the rigid wall than the flexible wall, and the pair of electrodes generating an electric field inside the fluid chamber and the fluid inside the fluid chamber functioning as a dielectric separating the pair of electrodes; a first oscillator connected to the pair of electrodes and having an oscillation frequency, the oscillation frequency of the first oscillator being affected by a dielectric constant of the fluid inside the fluid chamber functioning as the dielectric separating the pair of electrodes.

2. The diaphragm pump according to claim 1, further comprising at least one suction check valve and a dosing check valve.

3. The diaphragm pump according to claim 1, wherein the diaphragm is reciprocatingly movable by a driver.

4. The diaphragm pump according to claim 1, wherein the detector unit is configured to send a signal to stop the diaphragm from moving when a gas build-up is detected in the fluid chamber by the detector unit.

5. The diaphragm pump according to claim 1, wherein the detector unit comprises a second oscillator with a sensor element.

6. The diaphragm pump according to claim 1, wherein the pair of electrodes located outside the fluid chamber do not interfere with the flexure of the flexible wall.

7. The diaphragm pump according to claim 1, wherein a degassing valve connected to the fluid chamber is provided.

8. The diaphragm pump according to claim 1, wherein the pair of electrodes comprises a first electrode and a second electrode, and the pair of electrodes are positioned such that the electric field extends from the first electrode through a first portion of the rigid wall, from the first portion of the rigid wall through the fluid chamber, from the fluid chamber through a second portion of the rigid wall, and from the second portion of the rigid wall to the second electrode.

9. The diaphragm pump according to claim 1, wherein the diaphragm pump further comprises a comparator for comparing a frequency of the first oscillator to predefined threshold frequencies; and the frequency of the first oscillator is affected at least by the dielectric constant of the fluid inside the fluid chamber.

10. The diaphragm pump according to claim 9, wherein the comparator comprises a storage.

11. The diaphragm pump according to claim 9, wherein the comparator measures a frequency corresponding to at least one of (i) a volume of the fluid present in the fluid chamber and (ii) the dielectric constant of the fluid present in the fluid chamber.

12. The diaphragm pump according to claim 9, wherein if the predefined threshold frequencies define a lower threshold and/or an upper threshold for the measured frequency of the first oscillator; and if the measured frequency of the first oscillator is outside the lower threshold and/or upper threshold, the comparator sends a detection signal to a controller, the detection signal indicative of a need for degassing the fluid chamber.

13. A method for detecting gas inside a fluid chamber of a diaphragm pump, comprising the steps of: providing the diaphragm pump for use as a detergent dosage pump, comprising: a pump housing, the pump housing comprising a rigid wall and a flexible wall; the fluid chamber defined within the pump housing between the rigid wall and the flexible wall and having a fluid path inside the fluid chamber; a diaphragm defining the flexible wall of the fluid chamber and reciprocatingly movable; a suction check valve; a dosing check valve; and a detector unit for detecting a fluid inside the fluid chamber, the detector unit comprising: a pair of electrodes located outside the fluid chamber, thereby outside the fluid path inside the fluid chamber, and being positioned within the pump housing proximate the rigid wall and closer to the rigid wall than the flexible wall, and the pair of electrodes generating an electric field inside the fluid chamber and the fluid inside the fluid chamber functioning as a dielectric separating the pair of electrodes; a first oscillator connected to the pair of electrodes and having an oscillation frequency, the oscillation frequency of the first oscillator being affected by a dielectric constant of the fluid inside the fluid chamber functioning as the dielectric separating the pair of electrodes; starting a dosing cycle by dosing at least part of the fluid inside of the fluid chamber; starting a suction cycle, after at least partly dosing the fluid; and monitoring the fluid chamber by measuring a frequency of at least the first oscillator, and if detected, indicating of a gas build up inside the fluid chamber.

14. The method according to claim 13, further comprising the steps of measuring a frequency of a second oscillator, and storing the measured frequency of the second oscillator as a reference frequency.

15. The method according to claim 13, further comprising a degassing valve operatively connected to the fluid chamber.

16. The method of claim 13, wherein the pair of electrodes located outside the fluid chamber do not interfere with the flexure of the flexible wall.

17. The method of claim 13, wherein the pair of electrodes comprises a first electrode and a second electrode, and the pair of electrodes are positioned such that the electric field extends from the first electrode through a first portion of the rigid wall, from the first portion of the rigid wall through the fluid chamber, from the fluid chamber through a second portion of the rigid wall, and from the second portion of the rigid wall to the second electrode.

18. The method according to claim 13, further comprising the step of comparing the measured frequency with predefined threshold frequencies.

19. The method according to claim 18, wherein the frequency measured of the first oscillator varies periodically.

20. The method according to claim 19, further comprising, detecting the gas buildup if a frequency change occurs faster relative to the periodically varying frequency of the first oscillator.

Description

DESCRIPTION OF THE FIGURES

(1) Additional details, features, characteristics and advantages of the object of the invention are disclosed in the figures and the following description of the respective figures, whichin exemplary fashionshow one embodiment and an example of a dispensing system according to the invention. In the drawings:

(2) FIG. 1A shows a block diagram of a diaphragm pump according to an embodiment;

(3) FIG. 1B shows a schematically illustration of a diaphragm pump according to the present invention

(4) FIG. 2 shows an example of an altered frequency for a fluid inside the fluid chamber;

(5) FIG. 3 shows an example of an altered frequency for a gas present inside the fluid chamber.

(6) The illustration in FIGS. 1A and 1B show an embodiment of the present invention. In FIG. 1B a diaphragm pump 10 is shown. The diaphragm pump 10 comprises a pump head 12 with channels leading to a suction check valve 14, opening during a suction cycle and blocking during a dosing cycle, and a dosing check valve 16, blocking during a suction cycle and opening during a dosing cycle. In the pump head 12 a fluid chamber 18 is arranged, with one wall being defined by a diaphragm 20. The diaphragm is reciprocatingly moveable by a driving means (not shown) via a con rod 22, which is attached to the diaphragm 20. Inside the pump head 12 a first sensor element 24 is located adjacent to the surface of the pump head 12 next to the fluid chamber 18 and in the direction of the dosing check valve 16. The first sensor element 24 comprises two plane electrodes 26 for contactless detecting a gas inside the fluid chamber 18. The first sensor element 24 is a capacitance based sensor element of a first oscillator means (not shown). Depending on the dielectric constant and/or the amount of fluid, in particular liquid, inside the fluid chamber 18, the frequency of the first oscillator means varies and may change periodically according to a dosing and/or suction cycle of the diaphragm pump 10. The electrodes 26 generate an electrical field 28, which reaches at least partially into the fluid chamber 18. Hence a gas can be detected inside the fluid chamber 18, in particular in the area of the electric field 28 inside the fluid chamber 18, when a sudden, not periodic, change in frequency occurs.

(7) In FIG. 2 a diagram of a measured frequency of the oscillator means is shown, wherein the frequency of about 173 kHz comprises a square wave form, corresponding to a liquid present inside for example the fluid chamber 18. The measured frequency of the oscillator means shown in FIG. 3 also comprises a square wave form but with a frequency of about 287 kHz, corresponding to air present for example inside the fluid chamber 18. Thus, when a gas builds up inside the fluid chamber a significant difference in the frequency is provided and this significant difference may be detected by a comparator means, in particular by comparing the measured frequency to threshold frequencies, and may thus be used for detecting a gas inside the fluid chamber.

(8) The particular combinations of elements and features in the above detailed embodiments are exemplary only; the interchanging and substitution of these teachings with other teachings in this and the patents/applications incorporate by reference are also expressly contemplated. As those skilled in the art will recognize, variations, modifications, and other implementations of what is described herein can occur to those of ordinary skill in the art without departing from the spirit and the scope of the invention as claimed. Accordingly, the foregoing description is by the way of example only and is not intending as limiting. In the claims, the wording comprising does not exclude other elements or steps, and the identified article a or an does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. The inventions scope is defined in the following claims and the equivalents thereto. Furthermore, reference signs used in the description and claims do not limit the scope of the invention as claimed.

LIST OF REFERENCE SIGNS

(9) 10 diaphragm pump 12 pump head 14 suction check valve 16 dosage check valve 18 fluid chamber 20 diaphragm 22 con rod 24 first sensor element 26 electrode 28 electric field