EP0179793B1

EP0179793B1 - Hydraulic piston pump for pumping liquids

Info

Publication number: EP0179793B1
Application number: EP85901662A
Authority: EP
Inventors: Evald Isaksson
Original assignee: Individual
Current assignee: Individual
Priority date: 1984-04-09
Filing date: 1985-04-01
Publication date: 1987-12-02
Also published as: DK564285A; NO157875C; NO854946L; NO157875B; SE439807B; WO1985004691A1; DK564285D0; DE3561110D1; EP0179793A1; SE8401969D0

Abstract

The pump has a first pumping means (1) to be immersed into the liquid that is to be pumped, and a second means, driving pumping means (2), adapted to drive the first pumping means. The driving pumping means has a cylinder chamber (7) which, via a conduit, for instance a bendable hose (3), communicates with the first pumping means. The cylinder chamber (7) has two mutually displacable pistons (9, 12) which, when subjected to a predetermined mutual displacement, allows liquid to flow from the cylinder chamber (7) to a discharge outlet (6) on the pump. The outer piston (9) is sealed against the cylinder chamber (7), whereas the inner piston (12) seals against the outer piston (9) only via a circular edge (20) thereon. The lower pumping means (1) has a main piston (39) which can be urged downwardly by the pistons (9, 12) in the driving pumping means against the action of a spring (41). When the pressure from the pistons in the driving pumping means ceases, the main piston will, by means of said spring (41), urge liquid up through the hose (3) and the cylinder chamber (7) to the discharge outlet.

Description

The present invention relates to a hydraulic piston pump for pumping liquids, including a first pumping means designed to be immersed in the liquid, a second pumping means, here referred to as the driving pumping means, designed to drive the immersed pumping means, the immersed pumping means communicating via a conduit with a cylinder chamber being arranged in the driving pumping means, the cylinder chamber being provided with a valve capable of opening a connection between the cylinder chamber and a discharge outlet on the piston pump, the driving means being arranged by means of a driving piston to displace, during a driving phase, a quantity of the liquid from the cylinder chamber down through said conduit to the immersed pumping means, the immersed pumping means being arranged to displace, during a pumping phase, the liquid that is to be pumped in the opposite direction, up through said conduit by means of a working piston.
Such known pumps, see for instance the Swedish patent specification No. 7903469-0, can be provided with a bendable hose constituting the connection between the immersed pumping means and the cylinder chamber in the driving pumping means. The liquid column in the hose is thereby used as a «pump rod•. The driving piston of the driving pumping means urges the liquid downwards in the hose, the liquid pressure thereby acting on the working piston of the immersed pumping means. When the pressure from the driving piston ceases, the liquid will be displaced upwards through the hose by means of the working piston.
The known pumps have, however, several disadvantages. Among other things they provide a slow liquid pumping because the driving piston of the driving pumping means slows down the liquid flow in the pumping direction. Known embodiments of the driving piston of the driving pumping means do not provide any optimal sealing function of the piston valve, because an improved sealing function would slow down the pump stroke.
The object of the invention is, therefore, to provide a hydraulic pump of the kind described by way of introduction wherein the above disadvantages have been remedied.
This purpose is achieved by having provided the piston pump in accordance with the invention with the characteristics indicated in Claim 1.
Further advantages of the invention are apparent from the appended description and from the sub Claims which define further developments of the invention.
The invention is described in greater detail below with reference to the accompanying drawing, which shows a preferred embodiment of the invention.
Figs. 1 and 2 show a first and a second pump phase, respectively, of a driving pumping means in accordance with the invention. Figs. 3, 4 and 5 show a first, a second and a third pump phase, respectively, of the pumping means that is to immersed in the liquid in accordance with the invention.
The piston pump in accordance with the invention includes a first pumping means 1 adapted to be immersed to a lower level from where liquid is to be pumped, and a driving pumping means 2 located at a higher level, usually above the soil, whereto the liquid is to be pumped. The means 1 and 2 communicate with each other by means of a conduit, which can be in the shape of a tube or, as in the embodiment shown, in the shape of a bendable hose 3.
The driving pumping means 2, see figs. 1 and 2, includes a pump house 5 mounted on a base plate 4, the pump house being provided with a discharge outlet in the shape of a tube 6. The hose 3 merges in a vertical cylinder chamber 7 in a cylinder 8 mounted on the base plate 4. A hollow sleeve-shaped first piston 9 is adapted to reciprocate in the cylinder chamber 7. The piston 9 is sealed against the wall of the cylinder chamber 7 by means of a sealing ring 10, for instance an 0-ring, which is inserted in a groove in the wall of the cylinder chamber 7.
The inner wall of the .steeve-shaped piston 9 forms a vertical cylinder chamber 11 for a driving piston 12. This piston has a head 13 located outside the piston sleeve 9, the head 13 having a larger diameter than the cylinder chamber 11. The head 13 is via a schematically shown crank rod 14 operatively connected to a sleeve- shaped crank handle 15. This crank handle is mounted on a driving shaft 16, which, in a way not shown, can be driven for instance manually or electrically. The driving shaft 16 is designed, by means of an engaging heel 17, to displace the crank handle 15 by means of a corresponding heel 18 on the crank handle 15.
The shell surface of the piston 12 being located closest to the head 13 is surrounded by a sealing ring 19, for instance in the shape of an O-ring. This ring is adapted to seal against the upper edge 20 on the piston 9. The edge 20 is bevelled inwardly about 45°, the sealing ring 19 thereby being compressed by the head 13 inwardly and downwardly against the centre of the pistons, so that a very good sealing function is achieved, the sealing function being dependent of the pressure of the head 13 against the piston 9.
The piston 12, which has the shape of a hollow cylindrical sleeve, has in its upper sleeve portion just below the head 13 a number of holes or channels 21 for liquid passage and adapted to be blocked or openened, respectively, by the piston 9.
The piston has downwardly a base in the form of a metal disc 22 being screwed against the piston 9. The disc has a central through hole 23 for a metal pin screw 25, the diameter of which is less than that of the hole 23, and a number of through holes 25 for the liquid passage circumferentially disposed around the hole 23.
The piston 9 thereby constitutes a valve capable of opening a connection between the cylinder chamber 7 and the discharge outlet 6.
The pin screw 24 has one end screwed into a threaded hole in the head 13. A metal nut 26 is screwed on to the other end of the pin screw 24. The nut has a larger diameter than the hole 23, the nut 26 thereby being capable of displacing the disc 22 and the piston 9 when the piston 12 has moved upwards a predetermined distance, as is apparent from fig. 2.
The purpose of the nut 26 is to displace the piston sleeve 9 upwards to a predetermined working level/stroke distance, and also to constitute an adjustment device capable of adjusting the capacity of the pump, since this is dependent of the stroke distance of the piston.
The piston 9 and associated components are suitably made of stainless steel, whereas the cylinder 8 and the piston 12 suitably is made of a plastic material.
The sealing ring 10 serves as a sliding sealing during the movement of the piston 9 in the cylinder 8, and it, therefore, gives a certain resistance against the movement of the piston 9. The sealing ring 19, however, serves as a kind of engagement sealing, i. e. it does not prevent any movement of the piston 12 relative to the cylinder 11. A certain amount of play may even be allowed between the piston 12 and the cylinder 11 such that the piston 12 can move unbraked in the cylinder.
The immersed pumping means is shown in figs. 3-5. It includes a pump house 27 which upwards communicates with the driving pumping means 2 via the above-mentioned conduit in the shape of the hose 3.
The pump house 27 which is in the form of a vertical tube includes a stationary vertical cylinder 28 with a sleeveshaped piston 29. This piston is sealed against the wall of the cylinder 28 by means of a sealing ring 30, for instance a V-ring, which is inserted into a groove in the wall of the cylinder 28. A sleeve-shaped piston 31 which serves as a valve is adapted to reciprocate in the sleeveshaped piston 29.
The space above the cylinder 28 constitutes a pressure chamber 32 which together with the pressure from the liquid column of the hose 3 acts on the piston 31 via a head 33 in its upper end. The pistons 29 and 31 are movable relative to each other against the action of a spring 34, one end of which is secured to the piston 29 and the other end of which is secured to the piston 31.
The shell surface of the piston 31 which is located closest to the head 33 is surrounded by a sealing ring 35, for instance in the shape of an 0- ring. This O-ring is adapted to seal against the upper edge of the piston 29, which edge is bevelled in the same way as the edge 20 of the piston 9 of the driving pumping means.
The piston 31 has in its upper sleeve-shaped portion, just below the head 33, a number of through holes 36 (two of which are shown) for liquid passage. The sleeve-shaped piston 29 has in its lower portion a number of through holes 37 (four of which are shown) for liquid passage.
The wall of the cylinder 28'has a horizontal channel 38 which connects the interior of the cylinder 28 with the liquid that surrounds the pump house. The channel 38 thereby constitutes an excess stream valve which prevents the piston 29 from moving down through the cylinder 28, and prevents any formation of such a high pressure that the pump may be damaged.
A further piston 39, below called the working piston or the main piston, has an upwardly directed head 40 which engages the lower edge of the piston 29 by means of a strong spring 41 acting on the underside of the piston 39. The head 40 is rigidly attached to the main piston 39 by means of a vertical neck 42 along which a horizontal circular valve disc 43 is displacable. The disc 43 is adapted to open and close, respectively, a number of (two of which are shown) through vertical liquid passage channels 44 in the main piston 39.
The spring 41 can be prestressed such that the weight of the liquid column of the hose 3 somewhat exceeds the spring force in the rest position of the pump. Since adjustment devices for such prestressing are well-known to those skilled in the art, they are not shown or described here.
The operation of the piston pump is as follows. When the driving piston 12 during a driving phase is urged downwards by the crank rod 14, see fig. 1, liquid is urged from the cylinder chamber 7 downwards in the direction of the arrows 45 through the hose 3, so that the piston 31 of the lower pumping means 1 is urged downwards by a force which is depicted by an arrow 46 in fig. 3. The piston 29 thereby presses the main piston 39 downwardly. When this is pressed downwardly, the liquid below the main piston 39 displaces the valve disc 43 upwardly, see fig. 3, such that liquid can stream upwards through the channels 44 in the direction of the arrows 47 to a space between the main piston 39 and the cylinder 28.
When the piston 12 has passed its lower dead point it will be released by the release of the crank handle 15 from the driving shaft 16. The downwardly directed pressure from the piston 12 thereby ceases, and the spring 41 can - during the so called pump phase - press the piston 39 upwards such that the liquid in the space between the piston 39 and the cylinder 28 presses the valve disc 43 downwards, and is itself pressed through the holes 37 into and through the piston 29, out through the holes 36 of the upwards moving piston 31, and upwards through the hose 3 in the direction of the arrows 48, see fig. 4. Thereafter the liquid passes in the direction of the arrows 49 in fig. 2 into the pistons 9 and 12, causing the piston 12 to momentarily move upwards in an unbraked way, since it has been released and is not braked by any sealing element, such that liquid can rapidly be discharged through the outlet 6.
The main piston 39 then continues its movement upwards into engagement with the cylinder 28, see fig. 5, the operation sequences then being repeated when the piston 12 descends, such that a downwardly directed pressure, depicted by an arrow 50 in fig. 5, again acts on the piston 31.
It is apparent that the described piston pump may be modified by replacing the sealing rings with other conventional sealing elements. Furthermore, the valve disc 22 may, instead of being threaded against the piston 9, rather have the same diameter as the piston 9 and be threaded on to the pin screw 24, thus replacing the nut 26.
From the description above it is apparent that the pump has the following advantages.
Liquid can effectively and instantly be pumped independently of the position of the driving device, when the piston 12 has passed its lower dead point since the driving device has then been released.
A high and constant effect is achieved at every pump stroke/piston stroke irrespectively of the pump speed.
A very effective sealing can be achieved between the pistons 9 and 12 and between the piston 9 and the cylinder 8 without this preventing the liquid passage in the pumping direction.
The pump capacity can easily be set in dependence of the prevailing liquid source.
The pistons 29 and 39 of the lower pumping means need not be mechanically interconnected.
The piston 29 can not be urged out of its cylinder 28 because of the excess stream valve 38. This also prevents the pump from being burst due to an excess overpressure.
The piston 31 can serve as a liquid damper when it closes, because it is braked by the roof of the pressure chamber 32 before the piston 31 has entirely returned to its rest position, the liquid stream thereby successively decreases.
The valve 31 can be made of a resin and thereby serve as a mechanical damper.

Claims

1. Hydraulic piston pump for pumping liquids, including a first pumping means (1), below referred to as the immersed pumping means, designed to be immersed in the liquid, a second pumping means (2), below referred to as the driving pumping means, designed to drive the immersed pumping means, the immersed pumping means communicating via a conduit (3) with a cylinder chamber (7) being arranged in the driving pumping means, the cylinder chamber being provided with a valve capable of opening a connection between the cylinder chamber and a discharge outlet (6) on the piston pump, the driving pumping means being arranged by means of a driving piston (12) to displace, during a driving phase (fig. 1), a quantity of the liquid from the cylinder chamber down through said conduit (3) to the immersed pumping means, and the immersed pumping means being arranged to displace, during a pumping phase (fig. 2), the liquid that is to be pumped in the opposite direction, up through said conduit by means of a working piston (39), characterized in that the valve is a hollow piston (9) adapted to reciprocate in the cylinder chamber (7), said driving piston (12) being adapted to reciprocate within said hollow piston, said connection comprising at least one channel (21) within the driving piston (12), said channel having a first end communicating with the cylinder chamber (7) and a second end communicating with the discharge outlet (6), the hollow piston (9) being capable of - due to a relative displacement between the pistons (9, 12) - releasing and closing, respectively, said second end of the channel (21), i. e. open or close said connection, the driving piston (12) being capable of - by influence of the liquid that is pumped during the pumping phase by the working piston (39) - moving upwards and being displaced in relation to the hollow piston (9) such that said second end of the channel (21) is released and said connection opened.

2. Piston pump in accordance with Claim 1, characterized in an adjustable stop means (24, 26) for limiting the relative movements of the pistons (9, 12).

3. Piston pump in accordance with any foregoing Claim, characterized in that the driving piston (12) is arranged to displace the hollow piston (9) during a predetermined portion of its movement.

4. Piston pump in accordance with any foregoing Claim, characterized in that the hollow piston (9) is sealed against the wall of the cylinder chamber (7).

5. Piston pump in accordance with any foregoing Claim, characterized in that the driving piston (12) is sealed against the hollow piston only via a circular edge (20) thereon.

6. Piston pump in accordance with any foregoing Claim, characterized in that the driving piston (12) is operatively connected to a driving means (16).

7. Piston pump in accordance with Claim 6, characterized in that the capability of the driving piston (12) to move upwardly is improved by a release device (17, 18) in the driving device, the release device being arranged to release the driving piston (12) from the driving device when the driving piston has reached its maximum stroke distance.