EP0713009B1

EP0713009B1 - Diaphragm pump

Info

Publication number: EP0713009B1
Application number: EP95308267A
Authority: EP
Inventors: Peter Clarke
Original assignee: Clarke Brendon; Clarke Carl; Clarke Cheryl; Clarke Edit; Clarke Rene
Current assignee: Clarke Brendon; Clarke Carl; Clarke Cheryl; Clarke Edit; Clarke Rene
Priority date: 1994-11-17
Filing date: 1995-11-17
Publication date: 2005-07-20
Anticipated expiration: 2015-11-17
Also published as: DE69534315D1; EP0713009A3; ES2245452T3; DE69534315T2; EP0713009A2; GB9423174D0

Description

The present invention relates to a diaphragm pump. The diaphragm pump of the present invention has particular, but not exclusive, application to the field of sewage pumping.
Sewage comprises a liquid medium carrying a large amount of solid material in suspension and often comprises pockets of gas such as methane or air.
The presence of gas pockets in the sewage can often impair the pump's efficiency due to compressibility of the gas.
US Patent 2351304 discloses a fluid transfer apparatus comprising a casing, a flexible diaphragm peripherally supported on said casing and co-operating therewith to form a pump chamber above said diaphragm, inlet and outlet passages in the top of said casing, valves located in the passages with the seat of the inlet valve inclined with respect to a horizontal plane, the portion of said inlet valve seat at highest elevation being adjacent said outlet valve with at least a portion of the latter being located above the portion of the inlet valve which is at highest elevation whereby indrawn relatively light fluid or gases that would otherwise tend to collect immediately below said inlet valve will pass to said outlet valve and escape therethrough, there being no intervening structure to interfere with such flow.
US 1834957 discloses an open discharge pump having a pump structure forming a water passageway and comprising a member the upper wall of which is horizontal and the lower wall of which has a portion parallel to the horizontal flow of water and another portion contiguous to the first inclining upwardly until it is in horizontal alignment with the upper wall, the latter portion together with the upper wall and the lateral walls of the member forming a horizontal outlet, said structure also comprising a spout member having an apertured base joined to the first member in proximity to the edges of said outlet, said spout member having upper and lower walls shaped so as to provide a substantially direct water passageway through the structure and to discharge the outflowing water substantially horizontally, and a discharge valve horizontally seated within said structure against the edges of said outlet and hinged longitudinally of the edge of the outlet formed by the upper wall to provide free passage for outflow of water and sedimentary material, the lower wall of said spout sloping upwardly for a predetermined distance to keep the valve submerged at all times and the inclined portion of the lower wall of said member and the inclined lower wall of said spout causing the mean operating position of the valve to be substantially parallel to the flow of water through said outlet.
US Patent 3358610 discloses a diaphragm pump having a dished casing and one wall comprised by a flexible diaphragm clamped over a rim of the casing. An extension on the casing off to one side of and spaced from the rim carries a pivotally mounted handle having a portion extending over and secured to the diaphragm. The diaphragm can thus be easily removed to give unobstructed access to the interior of the pump. The casing has inlet and outlet valves whose axes are disposed at a substantial angle to each other, and the diaphragm moves substantially along the bisector of that angle.
US Patent 2811929 discloses a diaphragm pump of the discharge and suction stroke type having a pump body having a wall partly defining a pumping chamber provided with a valved liquid inlet and a valved liquid outlet, and means to initiate and resiliently to increase the rate of flow of liquid out of said chamber.
The present invention has an object of providing a pump designed to allow it to purge itself of the gas pockets during normal operation.
The invention provides a diaphragm pump in accordance with claim 1 of the appended claims.
An exemplary embodiment of the present invention is described with reference to the accompanying drawing, referred to as Figure 1, which shows a cross-sectional view of a diaphragm pump in accordance with the present invention.
Referring to Figure 1, a diaphragm pump suitable for pumping sewage is generally designated 10 and comprises a chamber 12 in the form of an elongate hollow body having openings at opposite ends, which is mounted for use on a support structure 1 by legs 13. The opening at the left-hand end of the chamber serves as an inlet 14 and the one at the opposite, righthand ends serves as an outlet 16. The inlet and outlet 14, 16 are constructed to convey fluid therethrough in a direction indicated by arrows F. It will be noted that the pump is constructed and its mounting arranged such that the arrows F extend horizontally and that the outlet 16 is at a greater height than the inlet 14.
The inlet and outlet 14, 16 are each provided with annular connection flanges 18. The connection flanges 18 are right-angled flanges in that they occupy a plane at right-angles to the arrows F and serve as the means by which an inlet valve assembly 24, including a one-way inlet valve 25, and an outlet valve assembly 26, including a one-way outlet valve 27 are connected to the chamber 12.
It will be appreciated that the use of right-angled flanges 18 in this manner permits the connection of the valve assemblies 24, 26 to the chamber 12 such that the central axes of the valve assemblies conveniently and readily extend horizontally.
The pump 10 also includes an aperture 30 in an upper surface of the chamber 12 between the inlet 14 and the outlet 16, and a flexible diaphragm 40. The flexible diaphragm 40 includes an inner region 42 and an outer region 44, the latter sealing against the surface of the chamber surrounding the aperture 30, thereby closing-off the aperture 30. The volume enclosed by the diaphragm 40 and the chamber 12 may be thought of as a fluid passageway 50 providing fluid communication between the inlet and outlet. From an inspection of Figure 1, it may be seen that the plane of the diaphragm 40, illustrated by the line X-X¹, slopes upwardly from the horizontal by a small angle as does a portion 12a of the upper surface of the chamber neighbouring the outlet 16 by approximately the same angle. The pump 10 also includes a driving means 100 which is operable to reciprocate the inner region 42 of the diaphragm to and fro within the chamber in a direction indicated by the arrow D (which is orthogonal to the line X-X¹).
In use, the driving means 100 reciprocates the inner region 44 of the diaphragm to and fro within the chamber 12. During the upstroke, the outlet valve 27 is closed and fluid is sucked into the passageway 50 via inlet valve 25. During the downstroke, the inlet valve 25 is closed and fluid is expelled from the outlet valve 27.
In use, there is a tendency for pockets of gas to collect in the chamber 12 in the region of the diaphragm 40. Air pockets form as a result of leaky pipe work or air being sucked in with the sewage during the previous upstroke. Methane pockets form as a consequence of the chemical breakdown of the sewage. These pockets have an adverse affect on the pump efficiency.
The differential height between the inlet 14 and outlet 16 and the upwardly sloping nature of the upper surface of the passageway 50, which in the described embodiment includes the diaphragm 40 and the upper surface portion 12a, promote the passage of the gas pocket to the outlet 16. Further, the angling of the diaphragm 40 relative to the horizontal such that it 'faces' the outlet ensures that a component of its motion during reciprocation takes place in the flow direction of fluid expelled from the outlet (indicated by arrow F). In this manner, the reciprocation of the diaphragm can propel the pockets of gas towards the outlet 16 and expel them therefrom.
In other embodiments (not illustrated), the angling of the diaphragm 40 can be further accentuated such that there is a differential in slope between for example, the diaphragm 40 and the portion 12a, whereby the above-mentioned propulsion effect is exaggerated.
Although the present invention has been described with heavy emphasis on a sewage pump, the principles of the present invention can also be employed in other fields where other media are pumped.

Claims

A diaphragm pump (10) mounted for use comprising:

a chamber (12) opening at opposite end portions to provide an inlet (14) and an outlet (16), and including an aperture (30) defined in a surface of the chamber (12) between the inlet (14) and outlet (16), the inlet (14) and outlet (16) being constructed to convey fluid therethrough in a generally horizontal direction and the outlet (16) being disposed at a greater height than the inlet (14);

a flexible diaphragm (40) having an inner region (42) and an outer region (44), the outer region (44) sealing against the surface of the chamber (12) surrounding the aperture (30) to close off the aperture (30), the chamber (12) and the diaphragm (40) thereby defining a passageway (50) providing fluid communication between the inlet (14) and outlet (16);

a one-way inlet valve (25) coupled to the inlet (14) and a one-way outlet valve (27) coupled to the outlet (16);

the inner region (42) of the diaphragm (40) being reciprocatable within the chamber (12), whereby on reciprocation of the inner region (42) fluid is drawn in via the inlet valve (25) and expelled via the outlet valve (27),

characterised in that:

the diaphragm (40) is angled such that the plane of the diaphragm (40) faces the outlet (16);

the upper surface defining the passageway (50) slopes upwardly from the horizontal from generally midway between the inlet (14) and outlet (16) to adjacent the outlet (16); and

the upper surface defining the passageway (50) includes the diaphragm (40) and the surface (12a) of the chamber (12) surrounding the aperture (30), and the plane of the diaphragm (40) slopes upwardly more steeply than does the surface (12a) of the chamber (12) surrounding the aperture (30).
A diaphragm pump (10) according to claim 1 characterised in that the central axes of the inlet (14) and outlet (16) are arranged to be parallel to and horizontally offset from one another.