JPH0358157B2 - - Google Patents

Abstract

1. Electrical heater for heating a gaseous or liquid medium, with a holding device for receiving a resistance-wire coil (8, 9), the holding device consisting of individual heater elements (1) of circular cross-section, which are placed on top of one another in the axial direction and in which there are, in regions located opposite one another, recesses (7) in which the resistance-wire coil (8, 9) is located, and the outer walls (4) of the heater elements (1), when these are placed on top of one another, complementing each other to form a closed cylindrical outer wall of the holding device, characterized in that in the heater elements (1) there are webs (5) which extend radially inwards from the outer walls to a central region and have the recesses (7) for receiving the resistance-wire coil (8, 9), and which between themselves determine axial flow channels (10) for the medium to be heated, in that in the central region of the heater there is at least one further axial flow channel (14a, 14b, 14c) which is closed at the downstream end of the heater, and in that on at least one of the downstream heater elements (1e, 1f) at least one radially extending passage (17) is formed between the further axial flow channel (14a, 14b, 14c) and the axial channels (10) located between the webs (5).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electric heater assembly (hereinafter simply referred to as "heater assembly"). The heater assembly includes a plurality of disk-shaped heater elements stacked one on top of the other, adjacent sets of heater elements defining annular channels between the elements, each channel having a resistive wire connected thereto. A portion of the coil is included and a plurality of resistance wire coil portions are connected in series with each other.

Heater assemblies of the type described above are known, for example US-A-1514857 and FR
-A-931619. In these heater assemblies, series connected resistance wire coil sections are mounted between individual disc-shaped heater body elements whose cylindrical outer surfaces are formed with slit openings. This allows contact between the resistance wire coil and the fluid to be heated. In these known heater assemblies, fluid flow around the resistance wire coil is relatively restricted, so that even if the resistance wire coil is heated to its maximum temperature, the heating output is relatively low. Put it away. For example, the following is already known from the above-mentioned FR-A1268738. That is, a resistance wire coil is mounted spirally in a single plane on a star-shaped carrier so that fluid flow occurs perpendicular to this plane. However, such a configuration is unsuitable for raising the temperature of the medium to be heated to a high temperature.

It is an object of the present invention to provide a heater assembly of the type already mentioned, which is capable of realizing a high temperature output despite its compact size.

This object is achieved by the features of claim 1.

In the heater assembly according to the invention, it is provided that the fluid to be heated, such as a gas, a mixture of gases, air or a liquid, passes through the resistance wire coil sections in a plane extending approximately perpendicular to the axis of the resistance wire coils. Features. As a result, good fluid flow can be achieved around the resistance coil wire, and efficient heat exchange can be achieved. This resistance wire coil therefore provides a high temperature output at a given temperature, which allows for a relatively compact structure. Despite its compact construction, the heater assembly provides relatively low fluid resistance and allows the resistance wire coil to be mounted on a radial wall section, which occupies only a small portion of the cross-sectional area of the penetration. In addition, the low fluid resistance makes it possible to realize a power-saving and low-noise blower, which makes it desirable to apply the heater assembly of the present invention to home appliances and hobby appliances.

Additionally, in the heater assembly described above, the introduced fluid flows continuously around the individual resistor wire coil sections, thereby repeatedly heating the fluid to be heated to extremely high temperatures. becomes. However, due to the increased temperature of the fluid throughout the length of the heater assembly, portions of the wire coil downstream of the flow are cooled to a lower temperature than those upstream. This is because the fluid flowing around that area is already at a high temperature. In order to obtain maximum power over the entire length of the resistance wire coil, it is necessary to maintain this coil at a uniform temperature. This is achieved by the constituent elements of the second claim (hereinafter referred to as the claim) described below. By forming a radial passageway between a channel and an axial opening (hereinafter referred to as axial opening) defined by a radial wall portion in the heater element in the downstream direction of fluid flow. , the portion of the resistive wire coil adjacent to the end of the downstream heater assembly can be kept at a suitable temperature, and an additional relatively low temperature fluid can be supplied (i.e., ambient temperature,
or lower), so that these heater parts are no longer heated to high temperatures.
This reduction in heat load is due not only to the supply of lower temperature fluid to the resistance wire coil section, but also because the flow rate is increased by the additional supply of fluid.

The structure of claim 3 improves temperature averaging in the flow direction. The large cross-sectional area of the passage in the downstream direction allows large volumes of relatively cold fluid to pass through, resulting in
The resistance wire coil section in the downstream direction (already cooled to some extent by the preheated fluid) is made larger than the preceding coil section in the direction of flow by the additionally supplied large volume of cold fluid. cooled at a rate.

According to claim 4 of the invention, the area of the cross section of the radial passage can be varied by stacking the heater elements on top of each other. That is, this cross-sectional area is obtained by combining two adjacent passages to form a single passage with a double cross-section.

Furthermore, according to the embodiment of claim 5 of the present invention,
Since the heater element with radial passages is engaged only in the region of the central core and in the region of the cylindrical outer wall, the total area of the cross section between the cylindrical outer wall and the central core A single radial passageway may be formed that communicates with all of the openings.

Also, according to claim 6 of the present invention, similarly,
It is characterized in that each part of the resistance wire coil is maintained at a substantially constant temperature. This feature can also be combined with the structure of claim 2.

Furthermore, the embodiment of claim 7 allows a simple electrical connection of the individual resistance wire coil sections without the use of special mounting elements for the resistance wire coil.

The present invention will be described in detail below with reference to the drawings.

FIG. 1 represents a heater assembly in which a stack of seven heater elements 1 is provided. The heater elements 1 are held assembled by a clamp member 2 extending through the center thereof. This heater assembly is mounted on a mounting unit 3 formed by an annular flange.

The heater elements 1 having the various shapes shown in numbers 4a, 4b, 5a, 5b, 6a and 6b are manufactured from ceramic material or other heat-resistant materials. The element 1 is provided with a cylindrical outer wall 4 connected to a central core 6 by a plurality of radial walls 5 . In the stacked state, the elements 1 form a cylindrical enclosure closed by the outer wall 4. The radial wall 5 has a relatively small width in the circumferential direction, which serves to reduce air resistance to the flow of air axially through the heater assembly. The axial edge of this radial state wall 5 is formed by a substantially semicircular recess 7.
In the stacked state of the heater elements 1, the axially adjacent recesses 7 cooperate with each other to form a circumferentially extending annular channel, which is a resistance wire of the type shown in FIG. Configured to receive individual portions 8 of the coil. FIG. 7 depicts the configuration as the resistance wire coil is mounted in the heater assembly. The individual sections 8 of this resistance wire coil are connected in series by connections 9. This connection 9 extends perpendicularly to the plane defined by the coil section 8 . Since this coil portion 8 does not extend around a complete circle, the aforementioned connections 9 are angular and staggered. Within the heater assembly, these portions also include axial channels 10 defined by pairs of adjacent radiating walls 5.
(angular and staggered) extending inward;
Terminal parts 11a, 11b of resistance wire coil
extends axially outwardly of the heater assembly as shown in FIGS. 1 and 2. A third axially extending lead 11c is connected to the appropriate portion of this resistance wire coil. This allows the creation of a predetermined tap that divides the voltage across the resistive wire coil and is used, for example, to energize a low voltage blower motor.

FIG. 2 shows the upstream end of the heater assembly. Air is introduced into twelve axial channels 10. The channels 10 are defined between the radial wall sections 5, allowing air to flow around the individual sections 8 of the resistance wire coil, and from these channels 10 in the downstream direction of the heater assembly. can leak out. This results in the diameter of the individual windings of the resistance wire coil being made slightly smaller than the radial dimension of each of the channels 10.
Thus, a large heat output can be obtained even with a relatively small heater assembly. Also, by aligning the radial wall portions 5 of successive heater elements 1 with each other in the axial direction, the channel 10
The resistance to the air flowing through it can be made as small as possible. For such alignment of the wall portions 5, mark grooves 12 (see FIG. 6a) are formed in each heater element 1. Furthermore, the heater element 1 can also be formed with mutually engageable projections and recesses. These allow assembly in a predetermined arrangement direction. In this example, the central opening 13 for receiving the clamping element 2 can be rectangular in cross-section, so that in cooperation with the clamping element, which also has a rectangular shape, the individual heater elements can be angularly deflected. This can prevent This clamping member can be formed by a bolt and nut.

All heater elements 1 except the last heater element 1g at the end in the downstream direction have three axial through holes 14a, 14b in the core portion.
and 14c. This hole 14a opens passages 15a, 15b extending diagonally outward, and these passages are open to the adjacent axial channel 10. This axial through-hole 14a serves to pass the terminal lead 11a of the resistance wire coil through it in cooperation with the diagonal channels 15a, 15b.

The through holes 14a, b and c also allow cool air to be supplied through the radiating passage 17 to the downstream portion 8 of the resistance wire coil. Without such a "fresh air supply", the resistance wire sections 8 in the downstream direction would be heated to a higher temperature than those in the upstream direction. The reason for this is that the air in this downstream section has already been heated to a certain temperature. However, this downstream "fresh air supply" allows a substantially uniform temperature to be achieved across the resistance wire coil combination. As diagrammatically illustrated in FIG. 3, the flow of air within the heater assembly can be seen. Each heater element 1
Displayed with the same characters as in the figure. Heater element 1a
~1d have the same shape and the radial passage 17
does not form. These heater elements 1 are
This is illustrated in detail in Figures a and 4b. The heater elements 1e and 1f are also formed in the same shape, but have a different shape from the heater elements 1a to 1d described above. That is, radial passages 17 are formed on both of these end faces. These passages 17 are connected to the axial hole 14
a, b, c, the region of the radial wall section 5 and the axial channel 10 extending between them. Through these passages 17, air flows from the axial holes (referred to as axial holes) 14a, 14b, 14c towards the axial (axial) channel 10, thereby discharging the already heated air. Becomes mixed. The air flowing through these radial channels 17 is ensured by closing the axial holes 14a, b, c by the last downstream heating element 1g. This heater element 1g is different from the heater element 1a because it does not have shaft holes 14a, b, and c.

FIG. 3 further shows that individual heater elements 1a
~ represents the characteristics of the configuration of 1g. As already explained, the radial passages 17 are connected to each heater element 1.
Formed on each end face of e and 1f. Since no radial passage is formed in the heater element 1d that contacts one end surface of the heater emerent 1e, a cross-sectional passage having a single width is formed between these heater elements. Since radial passages are formed at the end faces of heater elements 1e and 1f that are in contact with each other, the cross-sectional area of the radial passages thus obtained is twice the area of the passage between heater elements 1e and 1d. becomes. As a result, the resistance wire coil section 8 located between heater elements 1e and 1f is cooled more efficiently than the adjacent upstream section 8 between heater elements 1d and 1e. Furthermore, it is also possible to provide a radial passage of an appropriate height in the last heater element 1g in the downstream direction and to appropriately control the temperature of the resistance wire coil at this location.

Also, under the following conditions, radial passage 1
The area of the cross section 7 can also be changed appropriately. That is, the heater elements 1e and 1f having radial passages on both ends are replaced by a heater element having radial passages formed only on one of the ends. In this case, such a type of heating element is mounted on the last "closed" heating element 1d, with its radial passage side facing downstream. The next heater element is also installed in the same arrangement direction, and the next heater element is also reversed, so that the radial passage side of this element faces the passage of the heater element that precedes it, and as a result, this passage It has an area twice as large as the area of the cross section of the previous heater element. In such a combination, it is necessary to cover the last-mentioned heating element with something like a disc. The axial air supply holes 14a, b, and c can be closed by this disc-like member. Otherwise, other suitable measures need to be taken to have the same effect.

5a and 5b show the shape of the radial passage 17 within the heater element 1e in detail. In the figure, the radial passage 17 includes the axial hole 14a,
b, c, and the entire surface between the inner core part 18 and the area of the radial wall element 5, rather than being formed as a relatively narrow channel extending between one of the axial channels 10 and the adjacent axial channel 10. It is the one that occupies the As a result, the inner core part 18 and the outer peripheral wall 19 of the heater element 1e have only a full length, and the part extending between them has a reduced thickness. The heater elements thus stacked only contact their inner core portions 18 and along their annular outer walls 4. The relatively large surface area of the radial channels thus obtained ensures a nearly uniform supply of fresh air. This is ensured throughout the resistance wire coil section 8.

In the illustrated embodiment, each of the heater elements has axial holes 14a, b, and c spaced apart by an angle of 120 degrees. Of course, three or more holes can be formed. In other embodiments, the core is formed of no material other than the material in which the axial holes are formed, but with radial wall sections and axial air passageways similar to the arrangement for mounting resistance wire coils.

The spacing between the windings of the resistance wire coil may also be varied in order to maintain the temperature of the resistance wire coil substantially constant over its entire length.
This can be easily done as follows. That is, when installing the resistance wire coil portions on the heater element, this is achieved by appropriately stretching these coil portions in the downstream direction using one's hand. The larger the space between successive windings, the more
The thermal load on the resistance wire coil is reduced. Even without the additional fresh air supply mentioned above,
With this method, a suitable averaging of the temperatures is already achieved. However, by combining the two methods described above, it is possible to accurately regulate the temperature of a resistance wire coil over its entire length in a heater assembly of very compact construction, where the resistance wire coil Operating at extremely high temperatures.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the completed assembly of the heater assembly of the present invention, FIG. 2 is a diagram showing the upstream end of the heater assembly of FIG. 1, and FIG. 3 is a diagram of the heater assembly of FIG. 1. 4a and 4b are cross-sectional views of the heater assembly of FIG. 1, and FIGS. 5a and 5b are top sectional views of the second heater element, FIGS. 6a and 6b. The figure is a top cross-sectional view of the third element, and FIG. 7 is a perspective view of the resistance wire coil. 1... Heater element, 5... Radial wall, 7
... recess, 8 ... resistance wire coil, 10 ... axial channel, 17 ... radial passage.

Claims (1)

[Scope of Claims] 1 A plurality of disc-shaped heater elements 1 stacked on top of each other and adjacent pairs of these heater elements form an annular channel between them, each channel 7 having a resistance wire. In an electric heater assembly in which a plurality of these resistance wire coil sections are housed and which heat a fluid by electrically connecting a plurality of these resistance wire coil sections to each other in series, said stacked heater elements 1 close the A radially extending wall portion 5 forming a cylindrical envelope 4 and defining an axially extending channel 10 is provided between said envelope 4 and the core portion 6. An electric heater assembly characterized in that said annular channel 7 is formed adjacent to said radial wall portion to which said resistance wire coil portion 8 is attached. 2 in the core portion 6 at least one axially shaped aperture 14a having a closed end adjacent the downstream end of the heater assembly;
14b, 14c, and at least one radial passage 17 is formed in at least one of the heater elements 1e, 1f in the downstream direction.
extending between the axial openings 14a, 14b, 14c and the axial channel 10 defined by the radial wall portion 5. Heater assembly. 3. At least two radial passages 17 are provided which are continuous in the direction of fluid flow, and one of these passages in the downstream direction has a larger cross-sectional area than the one in the upstream direction. The heater assembly according to any one of Items 1 to 2. 4. The heater assembly according to claim 3, wherein the radial passage 17 is formed adjacent to an end surface of the heater element 1 in the axial direction. 5. The radial passage 17 is formed by forming the heater element with a reduced thickness so as to substantially surround the distance between the cylindrical enclosure 4 and the core portion 6. A heater assembly according to any one of claims 1 to 4. 6. Any one of claims 1 to 5, characterized in that the space between the windings of the resistance wire coil is increased in the direction of fluid flow.
The heater assembly described in section. 7 forming a closely closed ring by each section 8 of said resistance wire coil and staggering connections 9 between successive sets of adjacent coil sections 8 circumferentially into adjacent heater elements 1; 6. A heater assembly according to any one of claims 1 to 5, characterized in that it extends through an axial channel (10) arranged therein.