DE2620515C3 - Cast metal heat exchangers, in particular central heating boilers - Google Patents

Description

The invention relates to a cast metal heat exchanger in the preamble of the claim 1 designated Art.

Such a heat exchanger is known from German patent application W10 186X / 36c. The individual links are in contact with one another with their feed and discharge sections composed, with their end faces opposite said connections as well as their Ribs are spaced apart. These distances are also necessary because otherwise the tight connection of the sections mentioned would not allow to be established. If, however the rejection of individual links results in contact outside of the specified sections, corresponding forces act on the connection, which could cause it to leak.

Furthermore, according to DE-PS 6 19 247, a feed water preheater known with individual tubular bodies that can be connected to each other, and each of which consists of two individual tubes cast in one piece; two tubes are included common ribs to increase the heat transfer. They can be attached separately at the front Connection lines provided for two adjacent pipes.

In a central radiator known from GB 7 83 423, several members can also be used as pour a whole, with these limbs to form a radiator, which both along its Length and along its width for the purpose of air flow remains open.

Starting from the state of the art referred to in the introduction, the invention is based on the object to develop the heat exchanger further so that the risk of warping its individual Links is significantly reduced, ensuring a tight connection between all links should be and the leak test is simplified in a finished heat exchanger.

All this is made possible by the proposal according to the characterizing part of claim 1, which still is further developed by the proposal of claim 2.

To illustrate the invention, reference is made to the perspective, which relates to an exemplary embodiment Reference drawing.

In this drawing three members 2 of a central heating boiler 1 are shown, the usual ribs 6 have. The links are provided in their four corner points with passages 8, so that one

ίο can form continuous water circulation, which to the Example is provided in a central heating system It is essential that between the individual Linking 2 of the central heating boiler 1 after the casting no more connection work.

! 5 must be taken because the boiler is a single Casting forms, in particular, a lateral limitation of the flue gas flow achieve because the end walls are either very tight or at least tightly closable. The kettle can So fill the entire interior of the furnace, with only the passages 8 for the to connect circulating water with each other and to be connected to the circulation system.

In the drawing, the boiler is partially with the for Purpose of the casting necessary cores shown. So you can see a right end core 11 and two Intermediate cores 13 and 14. Following the latter intermediate cores, further cores can also be found connect, since for the sake of clarity only part of the entire exchanger is shown is. Furthermore, the intermediate core 13 is shown partially in section around a water cavity core 15 as well as the link 2 located in between to make it appear. The water void core 15 is provided with core eyes 16 which, on the one hand, seal into cavities in the end cores 11 and, on the other hand fit together. Furthermore, these are receiving centering projections, not shown Cavities 18 can be seen, so that all cores are well centered with respect to one another when the casting mold is assembled are arranged, wherein the Urnvangsränder 19 of the end and intermediate cores are sealing against each other. While the water cavity core IS has smooth walls, the other cores 11, 13, 14 delimiting ribs 21, which when pouring the metal, so usually the cast iron, from. that of the boiler is produced, determine the shape for the ribs 6.

The peripheral edges of the end and intermediate cores define upper sprues 25 which are in the bottom 26 of a groove-shaped pouring pool 27 are located. During casting, the liquid metal comes out of this Channel 27 through the openings 25 in the mold.

In practice it has been shown that in some cases during casting due to insufficient ventilation the shape of gas accumulations in it and, as a result, casting bubbles can arise.

You can solve the problem without fundamentally changing the heat exchanger in that near the upper edge in each intermediate and end core, a gas discharge duct 29 is arranged through which the gases produced during casting and combustion of the casting mold parts are discharged can. In the illustrated embodiment, the water cavity cores are near the top with

h5 provided a gas exhaust duct 30, which is in Extends the longitudinal direction of the water cavity core and extends transversely thereto through the core eyes 16 Channels 31 connects.

As soon as the trigger system 29, 30 and 31 does not yet lead to the desired success, it is possible to remove the Gases still take the following additional measures:

a) the ribs of the links are ^{interrupted to about 2} Ii of their height, whereby they form a channel 32 formed by various core sand. If necessary, a gas discharge duct comparable to ducts 29 and 30 can be arranged in this duct. In order to be able to discharge both gas via this channel, the following are also: ι ο

b) openings 33 are provided in the end walls 34 of the boiler.

The measures mentioned under a) and b) are only taken in special cases, because the measure mentioned under a) reduces the heating surface ΐϊ and the measure mentioned under b) makes it necessary to seal the heat exchanger on the flue gas side after casting with loose plates , whereby the intended effect of the invention is partially canceled.

The casting mold cores are made from a mixture of sand and synthetic resin manufactured, e.g. B. by suitable matrices. Of course, the surfaces are designed in such a way that that the cores can be easily detached from the matrices

The mixture has such a composition and strength that no changes in shape occur before the poured metal is solidified, wherein the synthetic resin is burned after the solidification of the metal and the Residue can easily be removed from the cast kettle. After pressing with water once Under pressure, the boiler can be checked for watertightness, in contrast to the boiler construction from individual members, each of which must be pressed individually before they are connected with nipples or the like get connected. Then the boiler as a whole must be pressed again to check whether the Connect the links to one another with a good seal.

1 sheet of drawings

Claims (2)

Patent claims: 1. Cast metal heat exchanger, especially one with circulating water or the like Medium-working, heated central heating boiler with at least two externally ribbed boilers Hollow links through which water or a similar medium flows and the smoke gases are flowed around, with the members forming side walls extending over the entire length of the tank, characterized in that the links (2) at their end edges with them over the entire Shell width extending end walls (34) provided and including them as a whole (1) are poured. 2. Heat exchanger according to claim 1, characterized in that it is on the water side and flue gas side, except for the passages for water and gas, sealed off from the ambient air is poured.