EP0117969B1 - 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 a 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 a replaceable wear part insert.

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. However, it is known from practice 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. If wear-promoting products are to be metered with the aid of such pumps, it is necessary to replace the sealing elements at relatively short intervals. In pumps used up to now, the replacement of the functional elements with wear and tear is associated with extensive dismantling of the entire pump, which has to be adjusted again after mounting because of the respective metered quantity.

The pump known from FR-A 2120 945, which has a wear part insert, also has the disadvantage that the functional elements, which are mainly subject to wear, are only partially arranged on this wear part insert and the pump therefore generally also has to be largely dismantled to restore functionality. Furthermore, this pump must be readjusted to change the dosing quantity after changing the wear part insert.

The invention is based on the general task of allowing simple, quick and safe repair of the pump when the wear occurs, in particular without additional readjustment of the metered quantity. Disassembly and assembly should, in particular, be carried out in such a way that the position of the sealing element assigned to the metering piston is clearly retained exactly without readjustment. The solution according to the invention is characterized in that the wear part insert contains the elements pump suction valve, metering check valve and piston sealing element which are subject to substantial wear. According to a further embodiment of the invention, the wear part insert should contain a piston guide element to be snapped into the insert body, which at the same time fixes the position of the piston sealing element which is particularly exposed to wear. The insert should also be assigned a contact edge in the lower part of the pump, to which the piston sealing element is to be precisely aligned with the aid of the piston guide element when mounting the insert.

The invention ensures that the insert can be changed easily, quickly and safely and, in particular, that no readjustment of the pump is required. By combining, according to the invention, the functional elements in the wear part insert that are important for the function of the pump, but are most exposed to wear, it is possible to replace the pump with the required accuracy with a few simple steps by replacing the insert, which is designed as a cartridge, for example, after wear has occurred to make it work. Because of the contact edge on the lower part of the pump which is preferably assigned to the insert body and because of the defined position of the piston sealing element guaranteed by the piston guide element, its relative position to the metering piston remains clearly exactly maintained after each replacement of the insert.

The interchangeable wear part insert according to the invention is intended to contain, in addition to the aforementioned elements, above all the pump suction valve and the metering check valve, in particular also the sealing elements which seal the metering line against the pre-feed chamber of the pump or the atmosphere. For the handling of the insert part, it is favorable if means are provided not only on the piston side for a piston guide element to be locked in place but also on the suction side for mutual fixing of the individual parts to be replaced. In particular, a press-in ring with a sealing element for fixing the suction valve in the insert body is advantageous even when it is not installed.

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 generally designated 1 has a metering piston 2 designed as a plunger piston with a pre-delivery membrane. In the context of interest here, when the metering piston 2 moves in the direction of the arrow 4, metering liquid is sucked in via the suction pipe 5, the ball check valve, which is denoted overall by 6, and the metering cylinder chamber 7 into the pre-delivery chamber 8 of the pump. When the metering piston 2 is moved back in the direction of the arrow 9, metering liquid present in the metering cylinder space 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 delivery chamber 8, but also through the metering cylinder room 7. This is a special which enables quick and safe self-venting and thus 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 in a few simple steps by, for example, replacing the Cartridge 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 is used 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 so 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 if 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 symbol list

• 1 = pump
• 2 = piston
• 3 = pre-conveyor membrane
• 4 = arrow
• 5 = suction pipe
• 6 = ball check valve
• 7 = dosing cylinder space
• 8 = pre-conveying space
• 9 = arrow
• 10 = metering check valve
• 11 = arrow
• 12 = dosing line
• 13 = wear part insert
• 14 = O-ring seal
• 15 = retaining ring
• 16 = ball
• 17 = piston sealing element
• 18 = piston guide element
• 19 = bead (18)
• 20 = leadership
• 21 = contact edge
• 22 = lower part of the pump
• 23 = sealing element
• 24 = sealing element
• 25 = press ring
• 26 = sealing element
• 27 = washer

Claims (10)

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, characterised 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.

2. Pump according to claim 1, characterised thereby, that the insert (13) contains a pump suction valve (6) constructed as ball valve consisting of retaining ring (15), 0-ring (14) and ball (16).

3. Pump according to claim 1 or 2, characterised thereby, that the insert (13) contains a metering non-return valve (10) 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 insert (13) contains a piston seal element (17) constructed as O-ring.

5. Pump according to one or more of the claims 1 to 4, characterised thereby, that the insert (13) contains a piston guide element (18) preferably to be detented in the insert body (13).

6. Pump according to one or more of the claims 1 to 5, characterised thereby, that a guide (20) preferably formed as a bore and a bearing edge (21) in the lower pump part (22) are associated with the insert (13) and that guide (20) and bearing edge (21) assure an exactly defined relative position of piston seal element (17) and piston (2).

7. Pump according to one or more of the claims 1 to 6, 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 O-rings, sealing off the atmosphere.

8. Pump according to one or more of the claims 1 to 7, characterised by a press-in ring (25) with sealing element (26) for the fixing of the non-return ball valve (6) in the insert (13) also in the uninstalled state.

Images