CA2180939A1

CA2180939A1 - Pump piston

Info

Publication number: CA2180939A1
Application number: CA 2180939
Authority: CA
Inventors: Klaus Zimmer-Vorhaus
Original assignee: Individual
Current assignee: ZIMMER VORHAUS KLAUS
Priority date: 1994-11-11
Filing date: 1995-11-13
Publication date: 1996-05-23
Also published as: WO1996015371A1; CN1140484A

Abstract

A pump piston (1) comprises a cup-shaped body (2). The piston (1) is reciprocated in a cylinder to pump liquids. The side wall (3) of the piston (1) is configured to allow the side wall (3) to expand during the pump discharge stroke to seal against the cylinder. The side wall (3) could be tapered from the base (4) to the free end (6), or have spiral cuts (7, 8, 9) from the free end (6) to adjacent the base (4), which are angled radially outwardly and away from the free end (6), or vertical cuts (20) which are substantially tangential to the inner surface of the cup-shaped body (2).

Description

2 1 8 0 ~ 3 q PCI/AU95/00752 Pump Piston The presenl invention relates to pislons for pumps and in particular to a piston for a water pump.

Pump pistons rec;,)rocate along a cylinder and require sealing between the 5 walls of the cylinder and the side walls of the piston. This sealing normally takes the form of piston rings located around the outer wall of the piston. The present invention seeks to provide a piston with an integral sealing means.

In one broad form the invention co",prises a pump piston adapled to pump liquids in a cylinder co"~prisi"~a.

a cup-sha~ed body made from a flexible material having a side wall extending from a base ter",i"ati"g in a lip at the free end; wherein said side wali is so configured that the side wall ex~an~is during the discharge stroke to seal againsl the cylinder.

In anull)er form the invention comprises a pump piston adapted to pump 15 liquids comprising a cup-shaped body made from a flexible material having a side wall extending from a base terminating in a lip at the free end; and at least one cut exte,1di,)9 through the material of the side wall and beginning at the lip of the side wall and spiralling around the side wall towards Sl~Slllul ~ S~IEET (R~le 26) the base of the cup-shapecl body fo~ iny a sealing means which during the d;scharge stroke moves radially outwardly to seal agai"sl the cylinder.

The invention will now be desc, il~ed by way of example with r~ere"ce to the acco"")anying draw;ngs in which:

5 Figure 1 illustrates a prospective view of a piston in accor~lance with one ernbodin,ent of the ~,rese,-t invention;

Figure 2 iiluslldtes a half sectional view of the piston illuslrale-l in figure 1;

Figure 3 illusl,dtes a part sectional view of the side wall of the piston illusl~al6d in figure 1;

10 Figure 4 illuslrales a side view of the piston illustrated in figure 1;

Figure 5 illusl,ates a plan view of the elllbodi,~enl illuslraled in above figures showing an exaggerated movement of the sealing arms;

Figure 6 illu~ll ales the same sectional view as that of figure 3 but shown during the pumping stroke;

15 Figure 7 illusl,dles a further elllbodi.l~eul of the present invention;

SU~Slll u l ~ SHEET (Rule 26) wo 96/lS371 2 1 8 0 9 3 9 pcrlAug5loo7s2 Figure 8 illusl~ales cross sectional view of another e"~bodi",ent of the present invention;

Figure 9 illustlales a pers~e~i~/e view of a,)otller e,nL,o~i",ent of the prese"l inventiG", 5 Figure 10 illusbdles a plan view of the piston shown in figure 9;

Figure 11 illu:jlr~tes a double acting piston accon:Ji"y to ar,otl)er er"bodi",e~ ll of the ,c rt:senl in\,ention figure 12 illusl,ales sche",alically an appalat~Js for cutting the spiral cuts; and figure 13 illusll dles a further view of the appar~lus shown in figure 12.

10 A pump piston (1 ) as shown in figures 1 to 6 com,urises a cup-shaped body (2) having a side wall (3) from a base (4). A central bore (5) eklends through the base (4) to receive the drive rod (not shown) to rec;prucate the piston in the cylinder. Located around the lip (6) of the side wall (3) are three cuts ( 7 8 & 9 ) which extend completely through the side wall (3). Each cut (7 8 & 9) spirals 15 from the lip (6) to ~- 5 ce"t the base (4) as shown in figures 2 and 4 and as shown in fisure 3 the cuts (7 8 & 9) are angled outwardly and away from the lip (6) at any suitable angle not necessary the angle shown in figures 3 & 6.

SUBSTITUTE SHE~T ~e 26) WO96/1S371 2 1 8 0 9 3 ~ PCT/AU9S/007S2 In use the cuts (7 8 & 9) form seali,~g fin~ers (10 11 & 12) which as shown in figures 5 & 6 pivot radially outwardly from the piston (1 ) during the pump discharge stroke, as a result of the axial vector (13) and the radial vector (14) of the fluid pressure. The cut surface (15) of finger (10) slides on the cut surface 5 (16) of the side wall (3) fo"ni"g a seal.

As shown in figures 1 & 5 the ri"yers overlap each other which assists in the flexibility of the ri"9er~ and hence their sealing action. Cut 7a--7b ex~e,1ds appro,~imately 160 around the piston (1), with the lowest point 7b being apl~ro~timalely 45 behind the top cut 8a of the next cùt 8a-8b. This paller, 10 being ,epeale~J around the piston (1), preferably angle of the cuts is approxin,alely 5. However any suitable slagger or overlap depending on the ",aleridl of construction can be used.

The invention is suitable for a double acting piston (17) shown in figure 7 where the construction of the ri"~ers is the same as the other embodiment.

1~ A further embodiment is shown in figure 8 in which the piston (18) has the side wall (19) tapering to the lip (6). The n,alerial of construction is chosen to have a suitable flexibility to allow the side wall to expand outwardly during the pump stroke to seal against the wall of the cylinder.

SUB~ SHEET (Rule26) WO 96/lS371 2 1 8 ~ 9 3 9 PCI/AU95/007S2 -A variation of the piston in figure 8 is shown in figures 9 & 10 in which vertical cuts (20) are made at a number of positions around the side walls (19). Theses cuts (20) are s~ t~nlially ta.,gential to the inner surface (21 ) of the side ~Nalls (19). Thus during the pumping or .lis~,arge stroke the thus r~r -,ed ringer~ (22) 5 slide radially outwardly across each other and seal ag~i"st the cylinder and tl ,emselves.

A double acting cylinder (23) is shown in figure 11 which is constructed n the same ",ar,ner as that of figures 9 &10.

Depe"ding on the ",alerial of construction which for example can be of any 10 suitable plastics such as high density polypropylene there can be any number of cuts from one two etc. upwards to effect sealing provided that the fingers exhibit the required degree of flexibility.

An ap~.ara~us to make the spiral cuts of the pistons illustrated in figures 1 to 7 is shown in figure 12 and 13. The a,cparatlJs cor"p, ises a cutter blade holder (23) 15 having a number of blades (24). A piston cel ItHny pin (25) is located in the center of the blades. The piston blank (26) is slid over the centring pin (25) which mates ~UBSTITUTE SHEET (RULE 26) WO96/lS371 ~ 3 0 ~ 3 9; PCI/AU9S/00752 in the central bore (5) of the piston blank (26). The piston blank (26) iS lotated in the direclion of arrow 27, and the blades (24) cut the spiral cuts (7, 8 & 9).

It should be obvious to people skilled in the art that ,noJiricalions and alterations can be made to the before desc,il~ed ~ o~i",enls without departing from the scope and spirit of the presenl invention SUBS~ B SH~T ~Rule 26)

Claims

1. A pump piston, adapted to pump liquids in a cylinder, comprising:
a cup-shaped body made from a flexible material having a side wall extending from a base terminating in a lip at the free end; wherein said side wall is so configured that the side wall expands during the discharge stroke, to sealagainst the cylinder.

2. A pump piston comprising:
a cup-shaped body made from a flexible material having a side wall extending from a base terminating in a lip at the free end; and at least one cut extending through the material of the side wall, and beginning at the lip of the side wall and spiralling around the side wall towards the base of the cup-shaped body, forming a sealing means which during the discharge stroke, moves radially outwardly to seal against the cylinder.

3. A pump piston according to claim 2, wherein the at least one cut is angled radially outwardly and away from the free end of the cup-shaped body.

4. A pump piston according to claim 3, wherein the at least one cut is angled radially outwardly and away from the free end of the cup-shaped body at an angleof approximately 5°.

5. A pump piston according to any one of claims 2 to 4, wherein there is a plurality of cuts which are staggered around the side wall forming fingers whichoverlap the adjacent finger.

6. A pump piston according to claim 5, wherein there are three cuts.

7. A pump piston, adapted to pump liquids in a cylinder, comprising a cup-shaped body made from a flexible material having a side wall extending from a base terminating in a lip at the free end; wherein said side wall tapers from the base to the lip, so that the side wall expands during the discharge stroke, to seal against the cylinder.

8. A pump piston according to claim 7, further comprising a plurality of axiallycuts, around the periphery of the cup-shaped body, extending from the lip to adjacent the base, and being substantially tangential to the inner surface of the side wall.

9. A pump piston according to any one of the previous claims wherein the material of construction is high density polypropylene.

10. A pump piston according to any one of the preceding claims wherein the piston is double acting.

11. A pump piston substantially as herein before described with reference to figures 1 to 6, figure 7, figure 8, figures 9 and 10, or figure 11 of the accompanying drawings.