WO1996024768A1

WO1996024768A1 - Pump having a check valve arrangement

Info

Publication number: WO1996024768A1
Application number: PCT/SE1996/000136
Authority: WO
Inventors: Carl-Göran HELLSTRÖM
Original assignee: Hellstroem Carl Goeran
Priority date: 1995-02-06
Filing date: 1996-02-05
Publication date: 1996-08-15
Also published as: AU4683096A; SE9500416D0; SE504043C2; SE9500416L

Abstract

A pump including a head (10) and a cylindrical tube (34) extending from the head, an axially movable plunger (40) being accommodated in the tube and having a piston rod (42) extending through a guide means (36) in the head (10), the cylindrical tube (34) externally being surrounded by a tubular envelope (16), such that between the cylindrical tube and the envelope is formed a space (52) communicating with the interior of the cylindrical tube as well as with connecting means (19, 23) for supply and discharge, respectively, of fluid. The connecting means is provided with one check valve (20, 24) each and each check valve is turnable for reversing the relative flow direction of the associated connecting means such that the connecting means for supply of fluid becomes connecting means for discharge and the connecting means for discharge becomes connecting means for supply of fluid.

Description

PUMP HAVING A CHECK VALVE ARRANGEMENT

The present invention concerns a pump including a head and a cylindrical tube extending from the head, an axially movable plunger being accomodated in the tube and having a piston rod extending through a guide means in the head, the cylindrical tube externally being surrounded by a tubular envelope, such that between the cylindrical tube and the envelope is formed a space communicating with the interior of the cylindrical tube as well as with connecting means for supply and discharge, respectively, of fluid, the connecting means being provided with one check valve each. The invention also concerns a check valve device for use with a fluid pump.

From SE-B-444 349 is previously known a dose pump of the above kind. This pump has an inlet tube provided with a check valve and an outlet tube provided with a check valve, enabling liquid to be sucked in through the inlet tube and to be discharged through the outlet tube.

The dose pump according to SE-B-444 349 exhibits the limitation that the pumped liquid is always transported in the same direction, that is, from the inlet tube to the outlet tube. This, of course, involves a draw-back as regards the flexibility when using this pump, particularly in a closed system where, for instance, liquids detrimental to the environment are being handled.

The present invention has as its object to provide a pump that is essentially more flexible than the dose pump according to

SE-B-444 349, particularly as regards the direction of flow of the fluid passing through the pump. Also, when it comes to mixing/dosing different fluids with each other, the pump according to the present invention is extraordinary suitable.

According to the present invention this object is achieved by means of a pump having the characteristic features stated in the appended claims. Embodiments of the pump according to the present invention will be described hereinafter, reference being made to the attached drawings, wherein

Fig. 1 shows one embodiment of the pump according to the present invention;

Fig. 2 shows a removable unit of the pump according to Fig. 1;

Fig. 3a and 3b schematically show a shiftable check valve adapted to be included in a pump according to the present invention;

Fig. 4 shows the pump according to the present invention in the shape of a syringe for medical purposes; and Fig. 5 shows a dismountable unit of the syringe according to Fig. 4.

The pump according to Fig. 1 includes a head 10, in the embodiment shown including a connecting part 12 attached to the lower portion of the head, said connecting part 12 having an internal thread 14 adapted to co-operate with a suitable external thread of a bottle or the like. The connecting part 12 is rotatable in relation to the remainder of the head 10.

An external envelope 16 in shape of a cylindrical tube is internally connected to a lower portion of the head 10. At the end of the external envelope 16 turned away from the head 10 is mounted a housing 18 to which a first connecting means 19 is dismountably connected. According to the invention any one of the ends of the first connecting means 19 may be mounted in the housing 18 as indicated in Fig. 1. The first connecting means 19 includes i first check valve 20.

In the head 10 itself is made a radial aperture 22 to which a second connecting means 23 is dismountably connected. Like the first connecting means 19, according to the invention the second connecting means 23 is connectable with a selective end to the head 10. The first and the second check valve 20, 24, respectively, are similarly shaped, that ism a spherical ball 26 is activated by a spring 28 to bear on the seating.

The dismountable connection of the connecting means 19 and 23 to the pump may be achieved in any suitable way, for instance by means of some kind of quick coupling or threads.

At its upper portion, the head 10 is provided with an internally threaded hole 30.

A dismountable unit 32 of the pump shown in Fig. 2 includes a cylindrical tube 34 and a bushing 36, the upper end of the cylindrical tube 34 being connected to the lower end of the bushing 36. The bushing 36 is provided with an external thread 38 in an intermediate portion. In the cylindrical tube 34 is arranged a piston 40, which sealingly bears on the inside of the cylindrical tube 34. The piston 34 is connected to a piston rod 42 passing through the bushing 36 serving as a sealing guide for the piston rod 42.

On the piston rod 42 is mounted an abutment 44, which is displaceable along the piston rod 42, suitably in that an internal thread of the abutment 44 co-operates with an external thread of the piston rod 42. The abutment 44 has as its object to limit the stroke of the piston 40 at upward displacement of the piston rod 42 in that the abutment 44 comes to bear against the lower end of the bushing 36. For adjustment of the abutment 44 the piston rod 42 is retracted such that the abutment 44 bears on the bushing 36. Friction between the abutment 44 and the bushing 36 then results in that the position of the abutment 44 can be adjusted by rotation of the piston rod 42, whereas the friction prevents the abutment 44 from participating in the rotation. By adjustment of the position of the abutment 44 the fluid volume of each stroke of the piston 40 can be varied, and further the piston rod 42 may be graduated such that the fluid volume of one piston stroke may be read. In this connection it should be pointed out that if for instance three pumps work in parallel, a desired mixture may be obtained by suitable adjustment of the fluid volume per piston stroke of the respective pumps.

In the embodiment shown in Figs. 1 and 2, the piston rod 42 is provided in its end turned away from the piston 40 with a handle 46 which allows manual operation of the piston rod 42. However, the invention is in no way limited to manual operation of the piston rod 42 as will be further illustrated below.

The unit shown in Fig. 2 is mounted in the pump by threading the external thread 38 in the internal thread 30 until a collar 48 of the bushing 36 bears on the head 10. The dismountable unit then occupies its correct position in the pump and the cylindrical tube 34 extends along the inner side of the envelope 16, the end of the cylindrical tube 34 turned away from the bushing 36 not extending all the way to the housing 18 but leaving there a gap 50. The external envelope 16 and the cylindrical tube 34 have such mutual diameter relation that between them is formed a space 52. It shall be noted that the space 52 communicates with both check valves 20 and 24.

The pump described above operates as follows. In the mounting position of the check valves 20 and 24 shown in Fig. 1, fluid transport takes place from the check valve 20 to the check valve 24. As indicated by an arrow 54, fluid is sucked in through the check valve 20 when the piston 40 is displaced upwardly in Fig. 1 by means of the piston rod 42 and the handle 46. hereby, fluid will fill the cylindrical tube 34 to a degree corresponding to the displacement of the piston 40 upwards. The subsequent step in the fluid transport involves displacement of the piston 40 downwards in Fig. 1, fluid enclosed in the cylindrical tube 34 then being pushed up in the space 52 between the cylindrical tube 34 and the envelope 16, see arrows 56 and 58, since discharge through the check valve 20 cannot take place, and further out through the check valve 24 which allows outward flow of fluid in the direction of arrow 60. Thereby, fluid has been pumped from the check valve 20 to the check valve 24.

By turning the connection means with the check valves, the turned connecting means then having reference numerals 19a and 23a and the associated check valves having reference numerals 20a and 24a in Fig. 1, it is made possible to pump fluid the opposite way through the pump according to the present invention. Due to the pump 40 being displaced upwardly in Fig. 1, fluid is sucked in through the check valve 24 in the direction of arrow 62 and further into the space 52 between the envelope 16 and the cylindrical tube 34, whereafter the fluid fills the cylindrical tube 34 to a certain degree depending on the displacement of piston 40. Next step in the fluid transport involves displacement of the piston 40 downwards in Fig. 1 so that fluid enclosed within the cylindrical tube 34 is pushed out through the check valve 20a in the direction of arrow 64. Thereby fluid has been transported from the check valve 24a to the check valve 20a.

Within the scope of the present invention one can also contemplate using another kind of check valve that does not have to be turned, but rather allowing simple shifting of the direction of flow permitted, either manually or automatically. In this regard, reference is made to Figs. 3a and 3b which schematically show a connecting means 9 having a shiftable check valve 70.

The check valve 70 according to Figs. 3a and 3b includes a valve housing 72 having connecting sockets 74 and 76 adapted to be connected to the pump according to the present invention. In a valve housing 72 is arranged a first spherical ball 78 which is provided with a through hole 80 in which check valve means is arranged. This means includes a second spherical ball 82 having substantially smaller diameter than the first ball 78. A valve seat 84 arranged in the through hole 80 is adapted to receive the second ball 82 in the closed position of the check valve. The spring 86 is supported at one of its ends by a support 88 which is arranged in the through hole 80. The other end of the spring 86 bears on the second ball and urges it with a certain force towards the valve seating 84. At the position of the check valve 70 shown in Fig. 3a, fluid may pass through the valve in the direction of arrow 90, the second ball 82 then being displaced from the valve seating 84 by pressure influence from the fluid overcoming the spring force. Fluid then passes through the check valve in the direction of arrow 90.

By rotating the first ball 78 through 180° in the plane of the paper of Fig. 3a, the possible flow direction through the check valve is reversed, the rotation through 180° then corresponding to the turning described in connection with Fig. 1. Such rotation of the first ball 78 through 180° may take place either manually or, for instance, by means of some kind of remote control in an electrical, automatical or pneumatical manner, it being directly realized that such rotation may take place easier and faster than the turning described above.

A further advantage of the check valve shown is that by turning through 90° in the plane of the paper from the position shown in Fig. 3a to the position shown in Fig. 3b, the valve is entirely closed, that is, it is not possible for fluid to pass through the valve at all.

As regards the connecting means shown in Figs. 3a and 3b, connection to the pump suitably takes place in a corresponding manner as the check valves according to Fig. 1, that is, by means of some kind of quick coupling or threads.

The check valve described in Figs. 3a and 3b has a displacement means in the shape of a spherical ball. However, the invention is in no way limited to such shape, but also other kinds of displacement means are conceivable within the scope of the present invention. Thus, in stead of the spherical ball one can contemplate another rotatably shiftable means, for instance cylindrical as in laboratory equipment of glass. The application of the present invention shown in Figs. 4 and 5 refers to a syringe for medical use. Principally, the syringe 10' according to Fig. 4 has the same construction as the pump 10 according to Fig. 1, and the dismountable unit 32' according to Fig. 5 has the same construction as the dismountable unit according to Fig. 2.

As the check valves 20' and 24' are arranged in Fig. 4, fluid is sucked in through the check valve 24' and discharged through the check valve 20' thereafter to pass through the cannula 92'.

Also in the application in the shape of a syringe, there is a need to enable reversal of the flow direction through the syringe, this taking place in a corresponding manner as in the embodiment according to Figs. 1 and 2, that is, by shifting or turning the check valves so that the possible flow direction therethrough is reversed. Thereby, the syringe may be used, for instance, for different kinds of sampling, that is, fluid is sucked in through the cannula 92 * and discharged through the radial aperture 22'.

It is general for the present invention that the piston rod 42; 42' can be automatically displaced, for instance electromechanically. Then the arrangement should be such that when no current is fed to the electromagnet, the piston rod 42; 42' is blocked against displacement.

Within the scope of the invention one can also conceive that the piston rod 42; 42' is spring loaded. This has been indicated in Fig. 1 in that a compression spring 42 has been drawn between the bushing 36 and the handle 46. This spring strives to transfer the piston rod 42 to its upper end position, that is, where the abutment 44 press against the bushing 36.

As an alternative to the compression spring 43, a pressure spring 45 also indicated in Fig. 1 may be arranged between the piston 40 and the housing 18. The invention is in a way limited to the embodiments described but may be freely varied within the scope of the appended claims.

Claims

C L A I M S

1. Pump including a head (10; 10') and a cylindrical tube (34; 34') extending from the head, an axially movable plunger (40; 40*) being accomodated in the tube and having a piston rod (42; 42') extending through a guide means (36; 36') in the head (10; 10'), the cylindrical tube (34; 34') externally being surrounded by a tubular envelope (16; 16'), such that between the cylindrical tube and the envelope is formed a space (52; 52 ' ) communicating with the interior of the cylindrical tube as well as with connecting means (19, 23; 69; 19', 23') for supply and discharge, respectively, of fluid, the connecting means being provided with one check valve (20, 24; 70) each c h a r a c t e r i z e d i n that each check valve is tumable for reversing the relative flow direction of the associated connecting means such that the connecting means for supply of fluid becomes connecting means for discharge and the connecting means for discharge becomes connecting means for supply of fluid.

2. Pump according to claim 1, c h a r a c t e r i z e d i n that each connecting means (19,23) with its associated check valve (20,24) is tumable per se.

3. Pump according to claim 1, c h a r a c t e r i z e d i n that the check valve (70) of each connecting means is arranged in a shiftable means (78) for reverse of the flow direction through the associated connecting means.

4. Pump according to claim 2, c h a r a c t e r i z e d i n that the reversable means is a body (78) rotatable within the connecting means through 180° and having a through hole (80) in which a check valve is located and which may be put in communication with a channel through the connecting means.

5. Pump according to claim 4, c h a r a c t e r i z e d i n that the rotatable body (78) is adjustable into a position where the through hole has no connection with the channel through the connecting means.

6. Reversable check valve device for use in a fluid pump, c h a r a c t e r i z e d b y a connecting body (72) having inlet and outlet for fluid and a rotatable valve body (78) rotatably arranged in the connecting body and having a through channel (80) in which is arranged a check valve, the valve body being rotatable between at least two positions separated by 180° in which the through channel communicates with the inlet and the outlet.