MEMBRANE FLUID PUMP

Abstract

A membrane fluid pump includes a rotatable drive shaft. The shaft is equipped with a number of eccentrics arranged axially along the shaft. The membrane fluid pump further comprises a set of connecting rods connected to each of the eccentrics. Each connecting rod is attached between one of the eccentrics on the shaft and a corresponding membrane so that each of the connecting rods is arranged to transfer a rotating movement of the shaft to a reciprocating movement pattern of the corresponding membrane. Each of the eccentrics and the connecting rods are arranged such that all of the membranes will reciprocate with a phase shift evenly distributed over a 360 degree rotation of the drive shaft, and wherein all of the eccentrics are rotationally offset to each other with an angle so that they are evenly distributed over a 360 degree rotation of the drive shaft.

Claims

1. A membrane fluid pump comprising: a drive shaft rotatable within said membrane fluid pump, a plurality of eccentrics arranged axially along the drive shaft, a set of connecting rods being connected to each eccentric, wherein each connecting rod of said set of connecting rods is attached between one of said plurality of eccentrics on said drive shaft and a corresponding membrane, so that each of said connecting rods is arranged to transfer a rotating movement of said drive shaft to a reciprocating movement pattern of the corresponding membrane, wherein each eccentric and said connecting rods are arranged such that all of said membranes will reciprocate with a phase shift evenly distributed over a 360 degree rotation of said drive shaft, and wherein all of said eccentrics are rotationally offset to each other with an angle so that they are evenly distributed over a 360 degree rotation of said drive shaft.

2. (canceled)

3. The membrane fluid pump according to claim 1, wherein the connecting rods of each set of connecting rods are arranged to reciprocate from a same axial position along said drive shaft.

4. The membrane fluid pump according to claim 1, wherein each of said eccentrics has a ball or a sleeve bearing between said drive shaft and said set of connecting rods attached to that eccentric.

5. The membrane fluid pump according to claim 1, further comprising a pump head including an inlet valve and an outlet valve or a valve combining inlet and outlet valve functionality for each membrane fluid pump.

6. The membrane fluid pump according to claim 5, where said each inlet valve and outlet valve are opening and closing by the fluid flow that the said membrane induces when moving in the reciprocating movement pattern.

7. The membrane fluid pump according to claim 5, where said each inlet valve and outlet valve are opening and closing as an active mechanism.

8. The membrane fluid pump according to claim 5, wherein opening and closing of each inlet valve and outlet valve is in response to a predetermined pressure difference threshold.

9. The membrane fluid pump according to claim 8, including membrane inlets and outlets in communication with corresponding inlet and outlet valves, wherein the plurality of membrane inlets and outlets are connected such that the fluid pressure change produced by each of said reciprocating membranes contributes to the opening and closing of said inlet and outlet valves.

10. A plurality of membrane fluid pumps according to claim l, wherein the drive shafts of at least two of the plurality of membrane fluid pumps are connected in series so as to increase the total number of membranes.

11. The plurality of membrane fluid pumps according to claim 10, wherein the drive shafts of at least two of the plurality of membrane fluid pumps are connected in series by a gearbox to permit the drive shafts of the at least two of the plurality of membrane fluid pumps connected in series to have different rotational speeds.

12. The membrane fluid pump according claim 8, wherein the flow rate of the membrane fluid pump is controlled by enabling and disabling opening and closing inlet and outlet valves of different membranes.

13. The membrane fluid pump according to claim 1, wherein rotation of the drive shaft and the eccentrics arranged axially along the drive shaft produce a membrane stroke for respective membranes, and a flow rate of the membrane fluid pump is controlled by changing an offset of at least some eccentrics thereby changing a displacement volume for respective membrane strokes.

14. The membrane fluid pump according to claim 5, wherein the pump head includes a pump head cavity and a flow rate of the membrane fluid pump is controlled by changing a dead volume of the pump head cavity.

15. The membrane fluid pump according to claim 9, wherein at least one of the membrane inlets and outlets from all membranes are interconnected via a cavity so as to reduce interference between opening and closing of inlet valves and outlet valves in said pump heads.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The above objects, as well as additional objects, features and advantages of the present invention, will be more fully appreciated by reference to the following illustrative and non-limiting detailed description of preferred embodiments of the present invention, when taken in conjunction with the accompanying drawings, wherein:

[0024] FIG. 1 is schematic view of the cross section of one of the sets of connecting rods of a membrane fluid pump according to the present invention.

[0025] FIG. 2 is schematic view of a cross section along the drive shaft of the membrane fluid pump of the present invention showing the principle of the invention.

[0026] FIG. 3 is perspective view showing two neighbouring connecting rods in the direction of the drive shaft. The two visible connecting rods belong to two different connecting rod sets.

[0027] FIG. 4a is a representation of the pulsation of the output flow from a pump according to the prior art.

[0028] FIG. 4b is a representation of the pulsation of the output flow from the pump according to FIG. 2 and FIG. 3.

[0029] FIG. 5 is table showing different possible configurations for an optimized multi membrane pump according to the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

[0030] FIG. 1 is schematic view of the cross section of one of the sets of connecting rods 3, 4 of a membrane fluid pump 1 according to the invention. The connecting rods 3, 4 reciprocate with a phase shift evenly distributed over a 360 degree rotation of the drive shaft 2. As there are three connecting rods 3, 4 in the embodiment of FIG. 1, the individual connecting rods 3, 4 with their respective membranes 3, 4 will be phase shifted 120 degrees apart from each other. Each connecting rod 3, 4, of the set of connecting rods 3, 4 is arranged to drive a separate membrane 3, 4. The connecting rods 3, 4 of the set of connecting rods 3, 4 are fastened to an eccentric 7 offset to drive shaft 2. The connecting rods 3, 4 are evenly distributed around the circumference of the eccentric to accomplish a reciprocating movement for each connecting rod 3, 4 phase shifted 120 degrees to the next.

[0031] FIG. 2 shows the membrane pump 1 of the present invention in a cross section along the drive shaft 2 showing the principle of the invention with having two connecting rod sets 3, 4 arranged to actuate their respective membranes 3, 4 in counter phase to each other, i.e. with a phase shift of 180 degrees. The drive shaft is connected to a motor 8 for driving the pump. As can be seen in FIG. 2 when one connecting rod 3 of one connecting rod set is in its upper end position upwards, the neighbouring connecting rod 4 in the direction of the drive shaft 2 is in its lower end position thereby eliminating any the combined mass movement in the radial direction to the drive shaft 2.

[0032] The connecting rods 3, 4 of each of the first set of connecting rods 3 and the second set of connecting rods 4 are arranged to reciprocate from the same position along the length of said drive shaft but phase shifted 180 degrees to eliminate any average mass movement in the radial direction of the drive shaft. FIG. 2 further shows the motor 2 driving the membrane fluid pump.

[0033] The skilled person realizes from the claims and the summary of the invention that the embodiment of FIG. 2 could be extended with further sets of connecting rods. Any number of sets of connecting rods attached to the drive shaft may be arranged to reciprocate with a phase shift evenly distributed over a 360 degree rotation of the drive shaft. Each connecting rod is arranged to drive a separate membrane, and the number of sets of connecting rods is then chosen to be equal to the number of connecting rods in each set of connecting rods. If the different sets of connecting rods are driven out of phase in relation to each other with 360 degrees divided by said number of sets of connecting rods the average mass movement in the direction of the drive shaft will be eliminated.

[0034] FIG. 3 is perspective view showing two neighbouring connecting rods 3, 4 in the direction of the drive shaft 2 of the fluid membrane pump 1. The two visible connecting rods belong to two different connecting rod sets attached to two different eccentrics 7. The membranes (not shown) are placed over the holes 5, 6 and are driven by the connecting rods 3, 4 in counter phase to each other to eliminate any average mass movement in the radial direction to the drive shaft. FIG. 3 reveals a further advantage of the present invention. All chambers angled in the same direction, in the configuration of FIG. 2 and FIG. 3 two of the six chambers, may be serviced by removing one single cylinder head or lid.

[0035] FIG. 4a shows a representation of the pulsation of the output flow from a pump according to the prior art. The solid lines show the pulses induced by the eight membranes of CN210326534Y, while the dashed line represent the combined average flow. FIG. 4b shows the pulsation of the output flow from the pump according to FIG. 2 and FIG. 3. As can be seen the pulsation is much smother from the pump according to the present application than from the prior art pump. The reason for this is that the membranes of CN210326534Y only pump at 90 and 180 degrees, leaving half a revolution of the crank shaft without any induction of pulses by the membranes.

[0036] FIG. 5 shows different possible embodiments of the pump according to the present invention. The possible embodiments are marked in the table with a box and grey background. All the combinations of the table would produce a functioning pump, but only the combinations marked with a box and grey background achieve all advantages of the invention, i.e. a pulsation free pump where the reciprocation of the pistons and membranes are neutralized so that no net mass movement is present during rotation. In other words, the centre of mass is always kept along the centre axis of the drive shaft 2 during operation of the pump. FIG. 5 shows that this configuration is possible with [0037] three rods per eccentric and two eccentrics, [0038] four rods per eccentric and three eccentrics, and [0039] five rods per eccentric and four eccentrics.
The advantages shown above in accordance with the invention is thus achieved by a pump according to what is described above having N rods and N1 eccentrics, when N>3.

[0040] It is understood that other variations in the present invention are contemplated and in some instances, some features of the invention can be employed without a corresponding use of other features. Accordingly, it is appropriate that the appended claims be construed broadly in a manner consistent with the scope of the invention.