EP0117969B2 - Dosing piston pump with diaphragm - Google Patents

Abstract

1. Piston-diaphragm metering pump (1) with mechanico-hydraulic, mechanico-pneumatic or electrical drive and with a metering piston (2) constructed as plunger piston as well as a forward conveying diaphragm (3) for the metering of an additive liquid into the inoculation point of a main liquid duct, in particular into a water duct, and an exchangeable insert part (13) subject to wear, characterized thereby, that the exchangeable insert part (13) subject to wear contains the elements pump suction valve (6), metering non-return valve (10) and piston seal element (17), which are subject to significant wear.

Description

The invention relates to a piston diaphragm metering pump with mechanical-hydraulic, mechanical-pneumatic or electric drive and with a metering piston designed as a plunger and a pre-delivery membrane for metering an additional liquid into the injection point of a main liquid line, in particular into a water line, and with a pump suction valve, a pre-delivery chamber and an exchangeable wear part insert housed in the lower part of the pump, which contains the dosing cylinder space, a piston sealing element which is fixed in position and allows the latter to be separated from the pre-delivery space, and a dosing check valve.

A piston diaphragm metering pump of the aforementioned type is known from FR-A 21 20 945. Metering pumps of this type are used because, on the one hand, due to the high performance of the pre-delivery membrane, good ventilation and suction and, on the other hand, due to the small metering piston in relation to the membrane area in connection with an elastic sealing element, preferably as an O-ring, exact metering even with different viscosities and Pump back pressure must be guaranteed. From practice, however, it is known that the performance of piston pumps with small dosing quantities depends very much on the function of the sealing elements designed as a compression O-ring, suction and pressure valve. Should wear-promoting products be dosed with the help of such pumps, is it is necessary to replace the sealing elements at relatively short intervals. In pumps of this type used up to now, the replacement of the functional elements subject to wear is associated with extensive dismantling of the overall pump, which has to be adjusted again after mounting because of the respective metered quantity. This is also no different with the aforementioned pump known from FR-A 21 20 945, especially since here the wear part insert and the pump suction valve arranged separately from it, which is also at risk of wear, can be replaced only with great difficulty, since in particular also for replacing the wear part insert Pump must be dismantled as far as possible. Furthermore, this pump must be readjusted after changing the use of wearing parts to adjust the metering quantity.

Even with a non-generic plunger pump according to DE-C 330 902, which has neither a pre-delivery membrane nor a pre-delivery chamber and which is provided with a pump cylinder containing both a suction valve and a pressure valve and also a piston sealing element, the latter can only be removed from the pump housing surrounding it with difficulty be removed, because the plunger that constantly protrudes into the pump cylinder would first have to be removed from it, and this in turn would require disassembly of this plunger from the crankshaft driving it.

The invention has for its object to improve a piston diaphragm metering pump of the type mentioned in such a way that a simple, quick and safe repair of the pump with regard to its most essential parts subject to wear and tear is possible without additional readjustment of the metered amount when wear occurs. The disassembly and assembly should be carried out in such a way that the position of the sealing element assigned to the dosing piston is clearly retained exactly without readjustment.

Starting from a generic piston diaphragm metering pump, this object is achieved according to the invention in that the wear part insert also the pump suction valve, which is subject to substantial wear, and a the latter contains a press-fit ring which defines it, together with these parts as well as the metering check valve and the piston sealing element forms a structural unit which holds together even when not installed, and such a wear part insert is in direct contact with an application edge which is present in the lower part of the pump and ensures a precisely defined relative position of the piston sealing element and metering piston , as well as the latter for any replacement in the opposite direction to the dosing piston.

It is achieved by the invention that the replacement of the wear part insert can be carried out easily, quickly and safely and that no readjustment of the pump is required. By combining and assembling the functional elements that are most important for the function of the pump, but most exposed to wear in the wear part insert, it is possible to restore the pump to the required accuracy with a few simple steps by replacing the wear part insert after wear has occurred. Because of the contact edge on the lower part of the pump assigned to the wear part insert, the relative position of the piston sealing element to the metering piston remains exactly the same after each replacement of the wear part insert.

Design features of the invention are characterized in the dependent claims.

Further details of the invention are explained on the basis of the enclosed, schematic drawing of an exemplary embodiment.

The metering pump shown in section in the drawing and designated as a whole by 1 has a metering piston 2 designed as a plunger and having a pre-delivery membrane. In the context of interest here, when the dosing piston 2 moves in the direction of the arrow 4, dosing liquid is sucked in via the suction pipe 5. When the metering piston 2 is moved back in the direction of the arrow 9, the metering liquid present in the metering cylinder chamber 7 is expelled into the metering line 12 via the metering check valve 10, which is in particular designed as a ring valve. Such a configuration of the pump 1 makes it possible to deliver the pre-delivery quantity not only through a separate suction channel directly into the pre-delivery space 8, but also through the metering cylinder space 7. This makes one special quick and safe self-venting and thus a quick and exact dosing.

According to the invention, the individual parts of the pump 1 which are mainly exposed to wear are combined in a separate wear part insert 13. This should contain the pump suction valve or ball check valve 6 consisting of O-ring seal 14, retaining ring 15 and ball 16 and the metering check valve 10, which is preferably designed as a ring valve with a small dead space. It is also important to integrate the piston sealing element 17 into the insert 13. By combining the above-mentioned sealing elements which are important for the function of the pump but are most exposed to wear in the wear part insert 13, it is possible to replace the pump as a cartridge in a few simple steps trained insert 13 to function again with the required accuracy after wear.

It is essential for the invention that the change of the insert 13 does not require any readjustment of the pump 1. The insert 13 therefore contains a piston guide element 18, which is preferably to be engaged in the insert body via a bead 19 and serves to fix the piston sealing element 17 which is essential for the function of the pump 1. Furthermore, the body of the pump 1 is to contain a guide 20, preferably designed as a bore, with a contact edge 21 in the pump lower part 22 that is precisely aligned with the metering piston 2. The contact edge 21 must be aligned such that the guide 20 receives the insert 13 including the piston sealing element 17 exactly in the correct position relative to the metering piston 2 without further adjustment. On the outer surface of the insert 13, sealing elements 23 and 24, in particular O-rings, are expediently provided, which seal the metering line against the pre-delivery chamber 8 or atmosphere.

The assembly of the insert 13 according to the invention is facilitated because means for fixing the ball check valve 6 are also provided in the non-installed state. In the exemplary embodiment, a press-in ring 25, a sealing element 26 and an intermediate disk 27 serve to fix the retaining ring 15 of the ball 16 also towards the rear.

Reference list

1

= Pump

2nd

= Piston

3rd

= Pre-conveyor membrane

4th

= Arrow

5

= Suction pipe

6

= Ball check valve

7

= Dosing cylinder space

8th

= Advance conveyor

9

= Arrow

10th

= Metering check valve

11

= Arrow

12th

= Dosing line

13

= Wear part insert

14

= O-ring seal

15

= Retaining ring

16

= Ball

17th

= Piston sealing element

18th

= Piston guide element

19th

= Bead (18)

20th

= Leadership

21

= Contact edge

22

= Lower part of pump

23

= Sealing element

24th

= Sealing element

25th

= Press ring

26

= Sealing element

27

= Washer

Claims (6)

1. Piston-diaphragm metering pump (1) with mechanico-hydraulic, mechanico-pneumatic or electrical drive and with a metering piston (2) constructed as plunger piston as well as a forward conveying diaphragm (3) for the metering of an additive liquid into the inoculation point of a main liquid duct, in particular into a water duct, as well as with a pump suction valve (6), a forward conveying chamber (8) and an insert part (13) subject to wear, which is exchangeably accommodated in the pump lower part (22) and which contains the metering cylinder chamber (7), a piston seal element (17) permitting the latter to be separated from the forward conveying chamber (8) and fixed in its position in the insert (13), and a metering non-return valve (10), characterised thereby that the insert part (13) subject to wear also contains the pump suction valve (6) subject to a significant wear as well as a final press-in ring (25) firmly lying therein, forms by not only these parts (6, 25) but also the metering non-return valve (10) and the piston sealing element (17) a sub-assembly cohering together even in the non-incorporated state, and such an insert part (13) subject to wear directly bears against a bearing edge (21), which is present in the pump lower part (22) and ensures an exactly defined relative position of piston seal element (17) and metering piston (2), and for possible removal is to be withdrawn from the bearing edge in direction opposed to the metering piston (2).
2. Pump according to claim 1, characterised thereby that the pump suction valve (6) contained in the insert (13) is a ball valve, which consists of a ball (16), a retaining ring (15) and an O-ring (14).
3. Pump according to claim 1 or 2, characterised thereby, that the metering non-return valve (10) contained in the insert (13) is constructed as ring valve with small dead space.
4. Pump according to one or more of the claims 1 to 3, characterised thereby, that the piston seal element (17) contained in the insert (13) is constructed as O-ring, which is fixed in the insert (13) by a piston guide element (18) preferably to be detented therein.
5. Pump according to one or more of the claims 1 to 4, characterised thereby that a guide (20), which is preferably formed as a bore, in the lower pump part (22) is associated with the insert (13).
6. Pump according to one or more of the claims 1 to 5, characterised thereby that the insert (13) contains the metering duct (12) towards the forward conveying chamber (8) and the sealing elements (23, 24), preferably as 0-rings, sealing off the atmosphere.

Images