US20150308455A1

US20150308455A1 - Wall ring for an axial fan

Info

Publication number: US20150308455A1
Application number: US14/430,481
Authority: US
Inventors: Thomas Heli; Peter Riegler; Jörg Günther; Jochen Häfner
Original assignee: Ebm Papst Mulfingen GmbH and Co KG
Current assignee: Ebm Papst Mulfingen GmbH and Co KG
Priority date: 2012-10-08
Filing date: 2013-09-16
Publication date: 2015-10-29
Also published as: DE102012109546A1; EP2904272A1; CN104736852B; EP2904272B1; CN104736852A; WO2014056677A1; ES2699953T3

Abstract

The present invention relates to a wall ring for receiving in particular an axial fan, comprising an annular body with a flow inlet opening and a flow outlet opening and a central longitudinal axis X-X as well as an annular wall extending between both openings. The annular wall has a cavity which is enclosed by an outer wall and an inner wall, in which an electrical heating element may be secured at least over a partial area of the periphery of the annular wall. The annular body consists of at least two partial bodies which are formed by a division of the annular body in a separating plane that extends perpendicular to its longitudinal axis and are detachably connected to one another.

Description

The present invention relates to a wall ring for receiving, in particular, axial fans, comprising an annular body having a central longitudinal axis, with a flow inlet opening and a flow outlet opening as well as with a ring wall running between the two openings.
Axial fans are used, among other things, for applications at very low temperatures. Here, there is a risk that ice will form and thus that the fan wheel blade will freeze onto the wall ring. Typical applications in which this risk exists include heat pumps, evaporators in cold-storage rooms and the like. In order to prevent such a freezing from occurring, it is a known procedure to install a heating element in the form of an electric resistance heater on the wall ring and to use it as a heater. A drawback here is the great amount of energy that has to be supplied in order to heat the wall ring all the way through so as to prevent ice formation on the inside of the wall ring or else to melt off any ice that might have formed there. Here, a high heat release to the surroundings takes place and the heat that enters into the cold-storage room in this manner has to be subsequently removed once again from the cold-storage room. As a result, such a wall ring heater is not energy-efficient.
The present invention is based on the objective of avoiding the above-mentioned disadvantages and reducing the formation of ice on the inside of the wall ring.
According to the invention, this is achieved in that the ring wall has a hollow space which is enclosed by an outer wall and an inner wall, and in which an electric heating element can be attached at least over part of the circumference of the ring wall, and in that the annular body of the wall ring consists of at least two partial bodies that are formed by dividing the annular body along a separation plane running perpendicular to the longitudinal axis and that are removably joined to each other.
The wall ring according to the invention is made of plastic so that, already due to the inner hollow space and the double wall as well as due to the material used (plastic) for the wall ring according to the invention, ice formation on the inside of the wall ring is reduced without the use of a heating element since the air space in the interior as well as the outer wall provide insulation vis-a-vis the environment. In addition, the configuration according to the invention makes it possible to install heating tape in the hollow space formed between the outer wall and the inner wall, whereby the heating tape is in contact with the inner wall of the ring wall. Advantageously, the hollow space formed between the outer wall and the inner wall is dimensioned in such a way that its volume is at least twice as large as the volume of the advantageously used heating tape that serves as an electric resistance heater. In this manner, an optimal insulation effect towards the outside is achieved. Since the wall ring according to the invention is configured in two partial bodies that are inserted into each other in the axial direction, that is to say, in the direction of the longitudinal axis, and then joined to each other, especially screwed together, it is easy to retrofit the wall ring according to the invention with a heating element.

Additional advantageous embodiments of the invention are contained in the subordinate claims and are explained in greater detail with reference to the embodiment shown in the accompanying drawings. The following is shown:

FIG. 1 a perspective view of a wall ring according to the invention, with an installed axial fan in the direction of its inlet opening,

FIG. 2 an exploded view of the wall ring according to the invention as shown in FIG. 1,

FIG. 3 a section along the sectional line III-III in FIG. 1,

FIG. 4 a perspective view of the wall ring according to the invention as shown in FIG. 1, in the direction of its outflow opening, when its partial body is not in the installed state.

In FIGS. 1 to 4, the same parts or functionally equivalent parts are always designated with the same reference numerals. Even if certain features of the wall ring according to the invention or of its components that have been described and/or that can be derived from the drawings are only described in conjunction with one embodiment, the features are nevertheless also essential according to the invention, irrespective of said embodiment, either as an individual feature or else in combination with other features of the embodiment, and are construed as belonging to the invention.
As shown in the figures, a wall ring according to the invention consists of an annular body 1 having a central longitudinal axis X-X, with a flow inlet opening 2 and with a flow outlet opening 3. The annular body 1 according to the invention has a ring wall 4 that is situated between the two openings 2, 3 and that has a circular cross section that is perpendicular relative to the central axis X-X. In the embodiment shown, there is an axial fan 6 inside the wall ring according to the invention. This axial fan 6 consists of an electric motor 7, which is arranged centrally in the central longitudinal axis X-X and to which an impeller 8 with fan blades 9 is connected.
According to the invention, the ring wall 4 consists of an outer wall 11 and an inner wall 12 that enclose a hollow space 13 between them.
As can be seen especially in FIGS. 2 and 3, the annular body 1 according to the invention is subdivided by means of a division perpendicular to the central longitudinal axis X-X into two partial bodies 14, 16, namely, a partial body 14 that encompasses the flow outlet opening 2, and a partial body 16 that encompasses the flow outlet opening 3. Since the division is perpendicular to the longitudinal axis X-X, these two partial bodies 14, 16 can be axially joined together and axially moved apart from each other. The annular body 1 according to the invention is made of plastic. Owing to the configuration of the hollow space in the ring wall 4 and owing to the use of plastic as the material, the annular body 1 already has a thermally insulating effect since, on the one hand, condensation and frost occur on a plastic surface to a lesser degree than on a metal surface and, on the other hand, the hollow space 13 has a thermally insulating effect.
As can be seen especially in FIG. 3, the outer wall 11 and the inner wall 12 of the two partial bodies 14, 16 have complementary stepped profiles 22, 23 on their outer wall sections 17, 18 as well as on their inner wall sections 19, 21 at their abutting ends, so that there is overlapping in the area of the stepped profiles 22, 23. In this manner, a seal is created between the outer wall sections 17, 18 and the inner wall sections 19, 21 in the area of their abutting ends, and a mutual positional fixation is likewise created. The outer wall sections 17, 18 and the inner wall sections 19, 21 of the partial bodies 14, 16 are each of different lengths so that the outer wall sections 17, 18 have different lengths and the inner wall sections 19, 21 likewise have different lengths, namely, in such a way that a longer outer wall section 17 is opposite from a shorter inner wall section 19, while the shorter outer wall section 18 is opposite from a longer inner wall section 21. As can be seen especially in FIG. 3, it is advantageous according to the invention for the inner wall 12 to have a convex curvature, so that a flow profile is created, whereby in the apex of the curvature, a very small rise in the curvature is formed at both sides of the apex. The outer wall 11 is advantageously made as a flat wall profile running parallel to the longitudinal axis X-X. As can also be seen from FIGS. 2, 3 and 4, it can be provided according to the invention that, inside the hollow space 13, there is an electric heating element 24 that, in the embodiment shown here, is configured as a heating tape, whereby it is advantageously an electric resistance heating element. The electric heating element 24 is arranged in such a way that it is in contact with the inside of the inner wall 12 facing the hollow space 13.
Advantageously, in the transition area between the outer wall section 17 and the inner wall section 19, and especially between the outer wall section 18 and the inner wall section 21, that is to say, at least on one of the partial bodies 14, 16, advantageously on both of the partial bodies 14, 16, there are fastening journals 26 that run axially parallel to the longitudinal axis X-X, that are arranged along the circumference, and that, together with the appertaining inner wall section 19, enclose a gap whose width is greater than or equal to the thickness of the heating element 24 that is to be used. Here, when the two partial bodies 14, 16 are in the installed state, their fastening journals 26 are arranged along the circumference so as to be offset relative to each other, and their length is advantageously greater than the width of the especially tape-like heating element 24. In order for the tape-like heating element 24 to be installed, it is slipped under the fastening journals 26 which then affix them axially and circumferentially. For this purpose, it is particularly advantageous for the fastening journals 26 to overlap the heating element 24 on both sides on its lengthwise edges that run circumferentially.
The two partial bodies 14, 16 are advantageously removably joined to each other by means of several screws 27 that are arranged along the circumference and that run axially in the direction of the longitudinal axis X-X. Moreover, it is advantageous according to the invention for a circumferential mounting flange 28 to be shaped onto one of the partial bodies 14, 16, in the present embodiment onto the partial body 14 that encompasses the inlet opening 2. This mounting flange 28 is formed by an edge web projecting radially relative to the longitudinal axis X-X. On this mounting flange 28, there are preferably four fastening tabs 29 that are uniformly distributed on the circumference and that have holes through which the corresponding fastening elements can be inserted. The electric motor 7 is held by means of a preferably flat protective wire grill 31, especially made of metal, whereby the protective wire grill 31 is attached by means of struts 32 to the partial body 14 on the circumference of the flow inlet opening 2.
In the embodiment shown, a rectangular housing 33 is shaped onto the annular body 1 between two fastening tabs 29, and said housing 33 is made up of two housing sections 34, 35, whereby the one housing section 34 is shaped onto the partial body 14 while the other housing section 35 is shaped onto the partial body 16.
The housing 33 has a side wall section that runs parallel to a tangent on the flow inlet opening 2 or on the flow outlet opening 3 and that is joined to the appertaining partial bodies 14, 16 via wall sections that run perpendicular to the side wall section. On the one hand, the electric connection line 37 of the electric motor 7 passes through the housing 33 from the partial body 14 or from the housing section 34 to the outside, namely, via drilled holes in the partial body 16 or in the housing section 35, preferably parallel to the longitudinal axis X-X that first runs along the protective grill 31, and on the other hand, the housing 33 serves to establish the contact of the electric heating element 24 to an electric power line 38 that is inserted into the housing 33 parallel to the longitudinal axis X-X. The housing 33 is closed by means of screw elements that are screwed in from the back, that is to say, from the side where the flow outlet opening 3 is located. The screwing in of the fastening screws 27 takes place in the same manner.
According to the invention, it can also be advantageous if a covering cap 39 in the center of the protective grill 31 is attached to the electric motor 7 through an opening in the protective grill 31, said covering cap 39 serving as protection against splashing water during a cleaning procedure. In particular, this cover 39 is preferably removably attached by means of a latched connection.
The two-part wall ring according to the invention, which is made of plastic and which has an integrated hollow chamber, reduces the tendency to ice formation in fans that are installed in cooling equipment and evaporators, it also reduces the heat input into the heat exchanger, and ice formation is prevented by means of the heating element 24, which can also be installed subsequently. The metal protective grill 31 which, according to the invention, is not curved, that is to say, it is flat, can also be easily cleaned mechanically if ice formation occurs.
The invention is not limited to the embodiments shown and described, but rather, it encompasses all embodiments that have the same effect as set forth in the invention. Moreover, the invention is not yet limited to the feature combinations defined in the claims, but rather, it can also be defined by any other desired combination of certain features among all of the individual features altogether disclosed. This means that fundamentally speaking, practically any individual feature of the independent claims can be left out or replaced by at least one individual feature disclosed in another place in the application. Consequently, the claims are only to be understood as an initial attempt at formulating an invention.

LIST OF REFERENCE NUMERALS

1 annular body
2 flow inlet opening
3 flow outlet opening
4 ring wall
6 axial fan
7 electric motor
8 impeller
9 fan blade
11 outer wall
12 inner wall
13 hollow space
14 partial body
16 partial body
17 outer wall section
18 outer wall section
19 inner wall section
21 inner wall section
22 stepped profile
23 stepped profile
24 heating element
25 fastening journal
27 fastening screws
28 mounting flange
29 fastening tab
31 protective wire grill
32 strut
33 housing
34 housing section
35 housing section
37 electric connection line
38 power line
39 covering cap
X-X central longitudinal axis

Claims

1. A wall ring for receiving, in particular, an axial fan, comprising an annular body with a flow inlet opening and a flow outlet opening and having a central longitudinal axis, as well as with a ring wall running between the two openings, characterized in that the ring wall has a hollow space which is enclosed by an outer wall and an inner wall, and in which an electric heating element can be attached at least over part of the circumference of the ring wall, and in that the annular body consists of at least two partial bodies that are formed by dividing the annular body along a separation plane running perpendicular to its longitudinal axis and that are removably joined to each other.

2. The wall ring according to claim 1, characterized in that the outer wall sections and the inner wall sections of the two partial bodies have complementary stepped profiles at their abutting ends, so that there is overlapping in the area of the stepped profiles.

3. The wall ring according to claim 2, characterized in that the outer wall sections of the partial bodies are of different lengths from each other and the inner wall sections of the partial bodies are of different lengths from each other.

4. The wall ring according to one of claims 1, characterized in that the inner wall 12, which has a convex curvature, is configured as a flow profile.

5. The wall ring according to one of claims 1, characterized in that the outer wall is a flat wall profile running parallel to the longitudinal axis X-X.

6. The wall ring according to one of claims 1, characterized in that, in the transition area between the outer wall sections and the associated inner wall sections, on at least one of the partial bodies, advantageously on both of the partial bodies, there are fastening journals that run axially parallel to the longitudinal axis, that are arranged along the circumference, and that, together with the opposite inner wall section, enclose a gap whose width is greater than or equal to the thickness of the heating element that is to be used, especially a tape-like heating element.

7. The wall ring according to claim 6, characterized in that, when the fastening journals of the two partial bodies are in the installed state, they are arranged along the circumference so as to be offset relative to each other, and their length is greater than the width of an installed tape-like heating element.

8. The wall ring according to one of claim 1, characterized in that the two partial bodies are removably joined to each other by means of several screws that are arranged along the circumference and that run axially in the direction of the longitudinal axis.

9. The wall ring according to one of claims 1, characterized in that the annular body is made of plastic.

10. The wall ring according to one of claims 1, characterized in that the flow inlet opening is covered by a protective wire grill.

11. The wall ring according to claim 10, characterized in that the protective wire grill has radially running struts whose radially inner ends are joined to a motor mount and whose radially outer ends are joined to the associated partial body.

12. The wall ring according to claim 11, characterized in that a covering cap for the electric motor is removably attached in the center of the protective grill.

13. The wall ring according to one of claim 1, characterized in that a circumferential mounting flange that protrudes radially is shaped onto one of the partial bodies, especially onto the partial body that encompasses the inlet opening.

14. The wall ring according to claim 13, characterized in that fastening tabs are shaped onto the mounting flange.

15. The wall ring according to one of claim 1, characterized in that the connection line runs along the protective grill, enters the partial body and exits the partial body in the axial direction through drilled holes.