US20200080727A1

US20200080727A1 - Insert, exhaust manifold, heat exchanger device and cooking appliance

Info

Publication number: US20200080727A1
Application number: US16/566,022
Authority: US
Inventors: Maximilian Wenninger; Manfred Lichtenstern; Marco Märtin
Original assignee: Rational AG
Current assignee: Rational AG
Priority date: 2018-09-10
Filing date: 2019-09-10
Publication date: 2020-03-12
Also published as: DE102018122050A1

Abstract

The invention relates to an insert for an exhaust manifold of a heat exchanger device for a cooking appliance comprising a support for two or more pipe sockets having at least one expansion slit, a first cover for the at least one expansion slit on the support, an insulation comprising a support insulation on the first cover and a pipe socket insulation around at least a portion of the pipe socket, and a second cover at least on the pipe socket insulation. It further relates to an exhaust manifold with such an insert, a heat exchanger device with such an exhaust manifold, and a cooking appliance with such a heat exchanger device.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of priority to German Patent Application No. 10 2018 122 050.2, filed Sep. 10, 2018, which is hereby incorporated by reference in its entirety for all purposes.

BACKGROUND

The present invention relates to an insert, an exhaust manifold into which the insert can be inserted, a heat exchanger device with the exhaust manifold together with inserted insert, and a cooking appliance with the heat exchanger device.
Numerous heat exchangers for cooking appliances are known in the prior art. For example, EP 0 856 705 B1 discloses a heat exchanger device for a cooking appliance with a radial fan impeller, a burner, and at least one heat exchanger tube associated with the burner that surrounds the fan impeller.
Heat exchangers that work in cooperation with a plurality of blowers are also already known. For instance, FR 2 710 401 A1 discloses a combustion system in which a heat exchanger tube is arranged around at least two blowers. The intention there is for the heat exchanger tube to be changed from a circular shape to a shape resembling the numeral eight upon a change from one blower to two blowers.
EP 1 843 101 B1 describes a heat exchanger device for a cooking system of a cooking appliance that comprises a large-diameter tubular section forming a combustion chamber and two small-diameter tubes extending at least partially parallel to one another, an exhaust manifold being arranged in the form of a connecting double truncated cone between the large-diameter tubular section and the two small-diameter tubes. With two blowers, such a small-diameter tube can encircle a first fan, while the other small-diameter tube can encircle both fans together.
Very high temperatures are required in cooking appliances, which results in special loads on heat exchanger devices. It has been found, for instance, that in previous exhaust manifolds that are used between a combustion chamber and two or more heat exchanger tubes in a heat exchanger device, excessively high heat transfer takes place to the outside via pipe sockets to the heat exchanger tubes. This results in embrittlement in the material of the exhaust manifold, which is usually steel, which reduces the strength of the material and can thus lead to severe damage. In addition, high voltages occur within a heat exchanger device, particularly in the vicinity of the exhaust manifold, and these voltages can ultimately result in the destruction of the heat exchanger device.
The high temperatures can be lowered in principle, for example by

- reducing the heating output, which also reduces the capacity and even the cooking performance of the device;
- increasing the air ratio of the combustion, resulting in a leaner combustion and the disadvantage that the efficiency of the heat exchanger decreases and higher gas blower output is necessary;
- enlarging the combustion chamber, resulting in a larger space requirement, which is difficult to implement with compact device dimensions;
- using more thermally stable material, which entails not only high costs, especially when nickel-based alloys are used, but also difficulties in processing, particularly due to poor formability; and
- providing improved cooling from the outside, which leads to very elaborate constructions that are extremely complex, especially if little installation space is available.

SUMMARY

It is therefore the object of the present invention to provide an insert for an exhaust manifold of a heat exchanger device for a cooking appliance that overcomes the disadvantages of the prior art.
This object is achieved according to the invention by an insert for an exhaust manifold of a heat exchanger device for a cooking appliance comprising a support for two or more pipe sockets having at least one expansion slit, a first cover for the at least one expansion slit on the support, an insulation comprising a support insulation on the first cover and a pipe socket insulation around at least a portion of the pipe socket, and a second cover at least on the pipe socket insulation.
A provision can be made that the first cover comprises a first foil, particularly a first steel foil, and/or the second cover comprises a second foil, particularly a second steel foil, and/or covers the complete insulation.
With the invention, in turn, it is proposed that the first and/or second steel foil consist of a high-temperature-resistant steel and/or have a thickness of 0.1 to 0.2 mm and/or have an embossing.
In addition, a provision can be made that the first and/or second foil is welded, preferably at the edges of the pipe socket.
Furthermore, the invention proposes that the insulation be a high-temperature insulation and/or be formed in one or more parts and/or enclose at least the ends of the pipe socket that face toward the support.
Embodiments of the invention can also be characterized in that the support is embodied in the manner of a plate, preferably a circular plate and/or in the form of a support plate.
In this case, the pipe socket openings can be arranged on a circumference around the center of the circular plate and/or each have a circular shape.
A provision can be made, in turn, that the expansion slit extends between pipe socket openings and comprises, in particular, expansion slit portions that extend radially outward from the center in which they meet.
According to the invention, it is preferred that three pipe sockets be provided, and that the expansion slit have three expansion slit portions, each of which extends between two pipe socket openings in the support.
It is also an object of the present invention to provide an improved exhaust manifold. This is achieved through an exhaust manifold of a heat exchanger device for a cooking appliance with two or more pipe sockets that are designed for attaching a respective pipe, and a manifold portion that is designed for attaching to a combustion chamber and for supporting the pipe socket, wherein the exhaust manifold is designed to receive an insert according to the invention, and wherein each of the pipe sockets of the insert extends at least partially into one of the pipe sockets of the exhaust manifold as soon as the insert is inserted into the exhaust manifold and the support of the insert is located between the combustion chamber and the downstream end of the manifold section.
Furthermore, the invention provides a heat exchanger device for a cooking appliance comprising an insert according to the invention in an exhaust manifold according to the invention.
Finally, a cooking device comprising at least one blower with an impeller in a blower chamber and a heat exchanger device according to the invention is also proposed, wherein the two or more tubes of the heat exchanger device are arranged at least partially around the impeller.
The invention provides an especially powerful, efficient, inexpensive, and yet compact cooking appliance.

BRIEF DESCRIPTION OF THE DRAWINGS

Additional features and advantages of the invention will become apparent from the following description of exemplary embodiments with reference to a schematic drawing. In the drawing:

FIG. 1 shows a partial perspective view of a heat exchanger device according to the invention with an exhaust manifold on a combustion chamber;

FIGS. 2 to 5 c show views for illustrating the structure of an insert according to the invention for the exhaust manifold of FIG. 1;

FIG. 6 shows an exploded view of the exhaust manifold of FIG. 1 and the insert of FIG. 5a ; and

FIG. 7 shows a sectional view through the heat exchanger device of FIG. 1 with the insert of FIG. 5 c.

DETAILED DESCRIPTION

FIG. 1 shows the portion of a heat exchanger device 1 according to the invention that is located in the region between a combustion chamber 10 and heat exchanger tubes; in the present case, three heat exchanger tubes 41, 42, 43 (shown only in portions) to which combustion gases are fed from the combustion chamber 10 via a manifold 20 are used. The heat exchanger tubes 41, 42, 43 then extend in the usual manner around one or two impellers, with reference being made by way of example to EP 1 843 101 B1, which was mentioned at the outset.
As a link between the combustion chamber 10 and the tubes 41, 42, 43 of the heat exchanger device 1, the exhaust manifold 20 comprises—in addition to three pipe sockets 21, 22 and 23—a manifold section 24 for distributing the combustion gases to the pipe sockets 21, 22, 23. According to the invention, an insert 30 is inserted into the exhaust manifold 20.
The structure of the insert 30 will be described below with reference to FIGS. 2 to 5 c.
As can be seen from FIG. 2, the insert 30 comprises a support 310, which can be a circular support plate bearing three pipe sockets 331, 332 and 333 and have an expansion slit 320 between these same pipe sockets 331, 332, 333. This expansion slit 320, in turn, has three expansion slit portions 320 a, 320 b, 320 c that extend outward from the center of the circular support plate in the manner of a star. Neither the pipe sockets 331, 332, 333 nor the elongation slit portions 320 a, 320 b, 320 c are disposed uniformly in the circumferential direction of the circular support plate. Rather, the distance between the pipe sockets 331 and 333 is greater than that between the pipe sockets 331 and 332 or the pipe sockets 332 and 333.
The expansion slit 320 enables the support 310 to expand in a low-stress manner at high temperatures and thus prevents the support 310 from being destroyed by the flow of hot combustion gases from the combustion chamber 10 when used in a cooking appliance.
As is shown in FIG. 3, the expansion slit 320 is provided with a thin cover in the form of a support steel foil 340. The support steel foil 340 thus prevents flow through the expansion slit 320.
According to FIG. 4, a high-temperature insulation in the form of a support insulation 350 is provided on the support steel foil 340 and pipe socket insulations 351, 352, 353. This insulation is protected by the support steel foil 340 from contact with hot combustion gases and, in turn, reduces heat transfer in the vicinity of the exhaust manifold 20 from within the combustion chamber 10 directly into the area outside of the heat exchanger device 1—i.e., into a blower chamber of a cooking appliance. The temperatures at the exhaust manifold 20 can thus be reduced. Even a thin insulation is sufficient and efficiently provides for a reduction in the temperatures of the support 310. The insulation can be embodied as a single part or as multiple parts.
It can be seen in FIG. 5a that the insulation is covered with an additional covering in the form of a steel foil, more precisely a support steel foil 360 and pipe socket steel foils 361, 362, and 363. This second cover serves to protect the insulation during assembly, i.e., while attaching the tubes 41, 42, 43 of the heat exchanger device. To wit, there is a risk that the insulation will be crushed or otherwise destroyed during assembly, since insulation is traditionally a fibrous material, which is very fragile. The pipe socket steel foil 361, 362, 363 is welded at its edges to the pipe socket 331, 332, 333 and thereby maintains the shape of the insulation, specifically as shown in the sectional view of FIG. 5 b.
To protect the insulation during assembly, it is sufficient in principle if only the pipe socket steel foil 361, 362, 363 is provided, as shown in FIG. 5 c.
The steel foil is made of a steel that is resistant to high temperatures and has a thickness in the range of 0.1 mm to 0.2 mm. Advantageously, the steel foil also has an embossing (not shown) in order to enable the steel foil to be shaped better and better absorb thermal expansion.
The insert 30, for example in the form shown in FIG. 5a , can be used in the exhaust manifold 20 as shown in FIG. 6, so that the pipe sockets 331, 332, 333 extend at least partially into the pipe sockets 21, 22, 23 and the support 310 forms an upper, downstream boundary for the combustion gases from the combustion chamber 10.
The sectional view of FIG. 7 now shows the portion of the inventive heat exchanger device 1 of FIG. 1 with its details on the insert 30 in the version shown in FIG. 5c . Accordingly, in addition to the expansion slit 320, the support 310 also comprises three pipe socket openings 321, 322, 323 to the pipe sockets 331, 332, 333. The support steel foil 340 and the support insulation 350 are arranged between the support 310 and the manifold section 24. In addition, the pipe socket insulation 353 and the pipe socket steel foil 363 are arranged between the pipe socket 333 and the tube 43 of the heat exchanger device 1, for example.
The insert 30 in the exhaust manifold 20 protects the critical region of a heat exchanger device 1 from high temperatures during operation.
The features disclosed in the foregoing description, in the claims, and in the drawings can be essential both individually and in any combination for the implementation of the invention in its various embodiments.

LIST OF REFERENCE NUMBERS

1 heat exchanger device
10 combustion chamber
20 exhaust manifold
21, 22, 23 pipe socket
24 manifold section
30 insert
41, 42, 43 tube
310 support
320 expansion slit
320 a, 320 b, 320 c expansion slit portion
321, 322, 323 pipe socket opening
331, 332, 333 pipe socket
340 support steel foil
350 support insulation
351, 352, 353 pipe socket insulation
360 supporting steel foil
361, 362, 363 pipe socket steel foil

Claims

What is claimed is:

1. An insert (30) for an exhaust manifold (20) of a heat exchanger device (1) for a cooking appliance, comprising

a support (310) for two or more pipe sockets (331, 332, 333) that has at least one expansion slit (320);

a first cover for the at least one expansion slit (320) on the support (310);

an insulation comprising a support insulation (350) on the first cover and a pipe socket insulation (351, 352, 353) around at least a portion of the pipe socket (331, 332, 333); and

a second cover at least on the pipe socket insulation (351, 352, 353).

2. The insert (30) as set forth in claim 1, characterized in that

the first cover comprises a first foil, particularly a first steel foil (340), and/or

the second cover comprises a second foil, particularly a second steel foil (360, 361, 362, 363), and/or covers the complete insulation.

3. The insert (30) as set forth in claim 2, characterized in that

the first and/or second steel foil consists of a high-temperature-resistant steel and/or has a thickness of 0.1 to 0.2 mm and/or has an embossing.

4. The insert (30) as set forth in claim 2 or 3, characterized in that

the first and/or second foil is welded, preferably at the edges of the pipe socket (331, 332, 333).

5. The insert (30) as set forth in any one of the preceding claims, characterized in that the insulation is a high-temperature insulation and/or embodied in a single or multiple parts and/or ensheathes the ends of the pipe socket (331, 332, 333) facing toward the support (310) or encloses the pipe socket (331, 332, 333) as well as the first cover.

6. The insert (30) as set forth in any one of the preceding claims, characterized in that

the support (320) is embodied in the manner of a plate, preferably a circular plate and/or in the form of a support plate.

7. The insert (30) as set forth in claim 6, characterized in that

the pipe socket openings (321, 322, 323) are arranged on a circumference around the center of the circular plate and/or each have a circular shape.

8. The insert (30) as set forth in any one of the preceding claims, characterized in that

the expansion slit (320) extends between pipe socket openings (321, 322, 323) and comprises, in particular, expansion slit portions (320 a, 320 b, 320 c) that extend radially outward from the center of the circular plate of the support (320) in which they meet.

9. The insert (30) as set forth in any one of the preceding claims, characterized in that

three pipe sockets (331, 332, 333) are provided, and

the expansion slit (320) has three expansion slit portions (320 a, 320 b, 320 c), each of which extends between two expansion slit openings (321, 322, 323) in the support (310).

10. An exhaust manifold (20) of a heat exchanger device (1) for a cooking appliance, comprising

two or more pipe sockets (21, 22, 23) that are designed for attaching a respective tube (42, 43); and

a manifold portion (24) that is designed for attaching to a combustion chamber (10) and for supporting the pipe socket (21, 22, 23),

characterized in that

wherein the exhaust manifold (20) is designed to receive an insert (30) as set forth in any one of the preceding claims, and wherein each of the pipe sockets (331, 332, 333) of the insert (30) extends at least partially into one of the pipe sockets (21, 22, 23) of the exhaust manifold (20) as soon as the insert (30) is inserted into the exhaust manifold (20) and the support (310) of the insert (30) is located between the combustion chamber (10) and the downstream end of the manifold section (25).

11. A heat exchanger device (1) for a cooking appliance, comprising an insert (30) as set forth in any one of claims 1 to 8 in an exhaust manifold (20) as set forth in claim 10.

12. A cooking appliance, comprising at least one blower with an impeller in a blower chamber and a heat exchanger device (1) as set forth in claim 11, characterized in that

the two or more tubes (42, 43) are disposed at least partially about the impeller.