Diaphragm pump for dosing a fluid and an according method

Abstract

A diaphragm pump (10), in particular for use as a detergent dosage pump, comprises a pump housing (12) with at least a first check valve (14) and a second check valve (16), a fluid chamber (18), a diaphragm (20) defining a wall of the fluid chamber (18) and reciprocatingly movable, driving means (28) with a driving shaft (30) for reciprocating said diaphragm (20), a control unit (36), wherein the driving means (28) is connected to the diaphragm (20) by an eccentric (26) and a con rod (24), wherein the driving means (28) is configured as a gearless drive to directly reciprocate the diaphragm (20). The diaphragm pump (10) according to the invention offers increased cost efficiency and further it is possible to increase the dosing capabilities of the diaphragm pump (10).

Claims

1. A method for dosing a fluid, comprising the steps of: (a) providing a diaphragm pump comprising: (i) a pump housing with at least a first check valve and a second check valve; (ii) a fluid chamber; (iii) a diaphragm defining a wall of the fluid chamber which is reciprocatingly movable, (iv) a driving means with a driving shaft for reciprocating said diaphragm, the driving means is connected to the diaphragm by an eccentric and a con rod, the driving means being bidirectional, defining a first direction and a second direction opposite the first direction, the driving means driving in the first direction when driving the diaphragm through a dosing cycle and a suction cycle, a start of the dosing cycle and a start of the suction cycle each corresponding to a respective defined position of the diaphragm (v) a sensor, and (vi) a control unit; (b) constantly detecting an absolute angular position of the driving means so as to determine a current position of the diaphragm and a nearest one of the respective defined positions, and (c) directly reciprocating the diaphragm based on the detected absolute angular position from the current position to the respective defined position along a shortest way, whereby the driving means drives the diaphragm in the first direction if the shortest way to the nearest one of the respective defined positions is via the first direction, and the driving means drives the diaphragm in the second direction if the shortest way to the nearest one of the respective defined positions is via the second direction.

2. The method according to claim 1, further comprising the steps of moving the diaphragm to the respective defined position at the beginning of the dosing cycle, or after completing a suction cycle for filling the fluid chamber.

3. The method according to claim 1, further comprising the step of modulating the driving speed in order to provide a constant volumetric flow of the fluid.

4. The method according to claim 1, further comprising the step of controlling the length of the dosing cycle in order to dose at least a part of the fluid with a basically constant volumetric flow for a given time.

5. The method according to claim 1, comprising the step of modulating the driving speed during the suction cycle in a way to avoid outgassing in the fluid.

6. The method according to claim 1, comprising the step of changing a driving speed in order to lengthen or shorten the suction and/or dosing cycle.

7. A diaphragm pump for use as a detergent dosage pump, comprising: (a) a pump housing with at least a first check valve and a second check valve; (b) a fluid chamber; (c) a diaphragm defining a wall of the fluid chamber which is reciprocatingly movable; (d) a motor with a driving shaft for reciprocating said diaphragm, the motor being connected to the diaphragm by an eccentric and a con rod, the motor being configured to directly reciprocate the diaphragm, the motor being configured to drive the diaphragm through a dosing cycle or a suction cycle, a start of the dosing cycle and a start of the suction cycle each corresponding to a respective defined positions of the diaphragm, the motor being bidirectional, defining a first direction and a second direction opposite the first direction, the motor driving in the first direction when driving the diaphragm through a dosing cycle and a suction cycle; and (e) a sensor arranged to constantly detect an absolute angular position of the motor so as to determine a current position of the diaphragm and a nearest one of the respective defined positions, wherein upon power up of the diaphragm pump, the motor directly drives the diaphragm based on the detected absolute angular position from the current position to one of the respective defined positions along a shortest way, the motor driving the diaphragm in the first direction if the shortest way to the nearest one of the respective defined positions is via the first direction, the motor driving the diaphragm in the second direction if the shortest way to the nearest one of the respective defined positions is via the second direction.

8. The diaphragm pump according to claim 7, wherein the motor is a hybrid stepping motor.

9. The diaphragm pump according to claim 7, wherein the eccentric is directly attached to the driving shaft of the motor.

10. The diaphragm pump according to claim 7, further comprising an indicating means connectable to the motor and/or the eccentric, and the sensor being configured to detect the indicating means.

11. The diaphragm pump according to claim 10, wherein the indicating means is a reflective surface arranged on at least a part of the peripheral area and/or a face side of the motor and/or the eccentric.

12. The diaphragm pump of claim 10, wherein the motor drives the diaphragm immediately after power up of the diaphragm pump through the dosing cycle until the sensor no longer detects the indicating means.

13. The diaphragm pump of claim 10, wherein the motor drives the diaphragm immediately after power up of the diaphragm pump through the suction cycle until the sensor begins detecting the indicating means.

14. The diaphragm pump of claim 10, wherein the indicating means extends about 180 degrees along a peripheral surface of the driving shaft and/or the eccentric.

15. The diaphragm pump according to claim 10, wherein the sensor is integrated into a control unit.

16. The diaphragm pump of claim 10, wherein the direction in which the diaphragm is driven by the motor is based on the indicating means being detectable by the sensor.

17. The diaphragm pump according to claim 7, wherein the con rod is directly attached to the diaphragm by a bolted connection.

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. 1 shows a sectional drawing of a diaphragm pump according to the present invention;

(3) FIG. 2 shows a perspective view of a further embodiment of the diaphragm pump according to the present invention.

(4) The illustration in FIG. 1 shows an embodiment of the present invention. In FIG. 1 a diaphragm pump 10 is shown, comprising a pump housing 12. Inside the pump housing 12 two first check valves 14 and two second check valves 16 are located, wherein the first check valves 14 enable a fluid (not shown) to enter into a fluid chamber 18. During a dosing cycle the fluid is expelled from the fluid chamber 18 and moves through the opened second check valves 16, while the first check valves 14 are locked. One wall of the fluid chamber 18 is defined by a diaphragm 20, wherein the diaphragm 20 comprises a connector 22 which is connected to a con rod 24. The con rod 24 is attached to an eccentric 26, wherein the eccentric 26 is attached to a driving shaft 30 of a driving means 28 for reciprocating the diaphragm 20. The con rod 24 is attached to the eccentric 26 by a ball bearing 42 for reducing the friction when the diaphragm pump 10 is operating. The eccentric 26 comprises a face side 40, which faces away from the driving shaft 40 and towards a control unit 36 for controlling the operating of the diaphragm pump 10. An indicating means 32 is arranged on the face side 40 of the eccentric 26, facing a sensor 34 mounted on the control unit 36, in order to determine the angular position of the driving means 28. The driving means 28 in form of a stepper motor as well as the control unit 36 are arranged inside a casing 38, wherein the casing 38. The indicating means 32 on the face side 40 of the eccentric 26 may be configured to correspond to a dosing cycle or a suction cycle of the diaphragm pump 10, for example by being designed in a semi circle. This enables the sensor 34 on power up of the diaphragm pump 10 to detect whether the diaphragm 20 is positioned in a dosing cycle or a suction cycle. The control unit 36 may then rotate the driving shaft 30 and thus the diaphragm 20 until the sensor detects the end or the beginning of the indicating means, stopping the driving means 28. Thus, the control unit 36 may move the diaphragm 20 in a defined position, for example the beginning of the dosing cycle. The diaphragm pump 10 may be scaled in order to be able to dose about 6 liters/hour of a fluid, preferably about 15 liters/hour, more preferred about 50 liters/hour, most preferred about 80 liters/hour. The driving means may accordingly provide a torque of about 0.1 Nm, preferably about 5 Nm, most preferred about 6 Nm. The pressure for dosing the fluid may accordingly be about 0.2 bar, preferably about 2 bar, most preferred about 10 bar.

(5) A further embodiment of the invention is shown in FIG. 2. The diaphragm pump 10 comprises a first check valve 14 and a second check valve 16 inside a pump housing 12, wherein the first check valve 14 opens on a suction cycle in order to permit a fluid to enter the fluid chamber (not shown) whilst the second check valve 16 is closed. During a dosing cycle the first check valve 14 is closed and the second check valve 16 opened in order for the fluid to leave the fluid chamber. The diaphragm (not shown) is driven by a driving means 28 in form of a stepper motor. Attached to the driving shaft (not shown) is an eccentric 26, which extends axially further than the driving shaft. The eccentric 26 comprises on a face side 40 the indicating means 32, wherein the indicating means 32 is designed in a semi circle shaped area, covering about half of the total face side 40 of the eccentric 26. The indicating means 32 is for example a reflective paint, wherein the indicating means 32 corresponds to a cycle, the suction cycle or the dosing cycle, of the diaphragm pump 10. Thus a sensor 34 integrated into the control unit 36 (shown detached) may determine if the diaphragm is in the position of a dosing cycle or a suction cycle, or at the beginning or end of a cycle. The control unit 36 is shown in a disassembled position.

(6) 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

(7) 10 diaphragm pump 12 pump housing 14 first check valve 16 second check valve 18 fluid chamber 20 diaphragm 22 connector 24 con rod 26 eccentric 28 driving means 30 driving shaft 32 indicating means 34 sensor 36 control unit 38 casing 40 face side 42 ball bearing