Electrical heating element, electrical heating device, and method for manufacturing an electrical heating device with such a heating element

Abstract

An electrical heating element for an electrical heating device is provided, wherein the electrical heating element is made from a coiled resistive wire with flat ribbon geometry and one or two connector assemblies, wherein the resistive wire with flat ribbon geometry is coiled into coils with an inner diameter, an outer diameter, and a distance between adjacent coils such that the flat side of the resistive wire with flat ribbon geometry runs parallel to the coil axis, and wherein the connector assemblies have at least one connection element that is in surface-area contact with a section of the resistive wire with flat ribbon geometry. In addition, an electrical heating device with such an electrical heating element and a method for manufacturing such an electrical heating device are also provided.

Claims

1. An electrical heating element for an electrical heating device, the electrical heating element comprising: a coiled resistive wire with a flat ribbon geometry and a connector assembly, wherein the resistive wire is coiled into coils with an inner diameter, an outer diameter, and a distance between adjacent coils wherein a flat side of the resistive wire runs parallel to a coil axis of the resistive wire, and wherein the connector assembly has at least one connection element that is in surface contact in one section of the resistive wire, a largest outer diameter of the connecting assembly being equal to the outer diameter of the coiled resistive wire.

2. The electrical heating element according to claim 1, a width of the resistive wire to is at least thirty percent (30%) of the inner diameter of the coils.

3. The electrical heating element according to claim 2, wherein the width of the resistive wire is equal to the outer diameter of the coils.

4. The electrical heating element according to claim 1, wherein a width of the resistive wire is at least twice as large as a thickness of the resistive wire.

5. The electrical heating element according to claim 1, wherein the distance between adjacent coils is less than a width of the resistive wire.

6. The electrical heating device according to claim 1, further comprising: a tubular metallic sheath having an interior, at least the coiled resistive wire is arranged within the tubular metallic sheath so that it is electrically insulated, at least in some sections, from the tubular metallic sheath.

7. An electrical heating element for an electrical heating device, the electrical heating element comprising: a coiled resistive wire with a flat ribbon geometry and a connector assembly, wherein the resistive wire is coiled into coils with an inner diameter, an outer diameter, and a distance between adjacent coils, wherein a flat side of the resistive wire runs parallel to a coil axis of the resistive wire, and wherein the connector assembly has at least one connection element that is in surface contact in one section of the resistive wire, the connector assembly has, as a connection element, a connector pin that is in surface contact with an inside of one of the coils of the resistive wire or in surface contact with an inside of a shaped end section of the resistive wire, wherein the connector assembly furthermore has a tube that is constructed of a material with a higher conductance value than a material from which the connector pin is constructed, the connector assembly has a tube opening adapted at least in some sections to an outer contour of the connector pin, so that an electrical surface contact is formed between the tube and the connector pin.

8. The electrical heating element according to claim 7, wherein an outer diameter of the connector pin is one of the inner diameter of the coils of the resistive wire and a bulge on an inside of the shaped end section of the resistive wire, wherein a direction of curvature of the bulge is a direction of curvature of the outer diameter of the connector pin.

9. The electrical heating element according to claim 8, wherein the connector pin is in an electrical surface contact with an entire inner surface of at least one of the coils of the resistive wire.

10. The electrical heating element according to claim 7, wherein the connector pin is one of welded and soldered to one of a section of an inner surface of the coils of the resistive wire and the inside of the shaped end section of the resistive wire.

11. The electrical heating element according to claim 7, wherein the connector pin is constructed of nickel.

12. The electrical heating element according to claim 7, wherein the connector pin includes a first connector pin and a second connector pin, the second connector pin constructed of a material with a higher conductance value than a material from which the first connector pin is constructed, the connector pin is arranged inside the tube from the side facing away from the coiled resistive wire.

13. An electrical heating element for an electrical heating device, the electrical heating element comprising: a coiled resistive wire with a flat ribbon geometry and a connector assembly, wherein the resistive wire is coiled into coils with an inner diameter, an outer diameter, and a distance between adjacent coils, wherein a flat side of the resistive wire runs parallel to a coil axis of the resistive wire, and wherein the connector assembly has at least one connection element that is in surface contact in one section of the resistive wire, wherein the connector assembly is comprised of two connector assemblies, each of the connector assemblies including a connection element and a tube, the tube having an inside that is in an electrical surface contact with an outside of a shaped end section of the resistive wire, the shaped end section inserted into the tube, wherein the tube is constructed a material with a higher conductance value than a material from which the resistive wire is constructed.

14. The electrical heating element according to claim 13, wherein the shaped end section is formed as an extension of the coils of the resistive wire and is comprised of end coils, the shaped end section having a reduced outer diameter compared to the outer diameter.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) The foregoing summary, as well as the following detailed description of the preferred invention, will be better understood when read in conjunction with the appended drawings.

(2) For the purpose of illustrating the preferred invention, there are shown in the drawings embodiments which are presently preferred. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown. In the drawings:

(3) FIG. 1a is a coiled resistive wire with flat ribbon geometry in accordance with a first preferred embodiment of the present invention,

(4) FIG. 1b is a cross section view through the coiled resistive wire with flat ribbon geometry from FIG. 1a,

(5) FIG. 2a is a side elevational and partial cross sectional view of a barrel for providing the wire to form the coiled resistive wire with flat ribbon geometry of FIG. 1a,

(6) FIG. 2b is a detailed and magnified cross sectional view of the coiled resistive wire with flat ribbon geometry taken from within shape A of FIG. 2a,

(7) FIG. 3a is a cross-sectional view of an area of an electrical heating element for a first configuration of the connector assembly in accordance with another preferred embodiment of the present invention,

(8) FIG. 3b is an exploded view of the configuration of the connector assembly from FIG. 3a,

(9) FIG. 4a is a cross-sectional view of an area of an electrical heating element for a second configuration of a connector assembly in accordance with an additional preferred embodiment of the present invention,

(10) FIG. 4b is an exploded view of the configuration of the connector assembly from FIG. 4a,

(11) FIG. 5a is a cross-sectional view of an area of an electrical heating element for a third configuration of a connector assembly in accordance with another preferred embodiment of the present invention,

(12) FIG. 5b is an exploded, side perspective view of the configuration of the connector assembly from FIG. 5a,

(13) FIG. 6a is a cross-sectional view of an area of an electrical heating element for a fourth configuration of a connector assembly in accordance with an additional preferred embodiment of the present invention,

(14) FIG. 6b is an exploded, side perspective view of the configuration of the connector assembly from FIG. 6a,

(15) FIG. 7a is a cross-sectional view of an area of an electrical heating element for a fifth configuration of a connector assembly in accordance with a further preferred embodiment of the present invention,

(16) FIG. 7b is an exploded, side perspective view of the configuration of the connector assembly from FIG. 7a,

(17) FIG. 8a is a side perspective view of an area of an electrical heating element for a sixth configuration of a connector assembly in accordance with another preferred embodiment of the present invention,

(18) FIG. 8b is an exploded, side perspective view of the configuration of the connector assembly from FIG. 8a,

(19) FIG. 9a is a cross section through an electrical heating device before the compacting process in accordance with an additional preferred embodiment of the present invention,

(20) FIG. 9b is a cross section through the electrical heating device from FIG. 9a after a compacting process, and

(21) FIG. 10 is another example option for providing a coiled resistive wire with flat ribbon geometry in accordance with a preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

(22) FIG. 1a shows a coiled resistive wire 10 with flat ribbon geometry, as it could be used in a preferred embodiment of a heating element according to the invention; FIG. 1b shows a section through the coiled resistive wire 10 with flat ribbon geometry from FIG. 1a, wherein a series of sizes with which the flat ribbon geometry and the coiled arrangement can be characterized are shown. The essentially rectangular cross-sectional surfaces Q can be seen with a long extent direction that defines a width B and a short extent direction that defines a height H. The individual coils W, which each run around a dashed coil axis Aw, have an outer diameter D1 and an inner diameter D2 and adjacent coils W are distanced from each other by a distance S.

(23) In particular, in the shown coiled resistive wire 10 with flat ribbon geometry, it can be seen that the width B of the resistive wire 10 with flat ribbon geometry corresponds approximately to the coil outer diameter D1, the width B of the resistive wire 10 with flat ribbon geometry is approximately five-times (35X) larger than its height H, and the distance S between adjacent coils W is less than the width B of the resistive wire W with flat ribbon geometry, more precisely, approximately twenty-five percent (25%) of the width B.

(24) FIGS. 2a and 2b illustrate schematically one option for manufacturing the coiled resistive wire with flat ribbon geometry. Here, on a barrel 21, a resistive wire with flat ribbon geometry is realized, which was manufactured in this shape as an endless material, which can be realized, for example, on a not-shown mandrel with the desired coil inner diameter, in order to manufacture the coiled resistive wire 20 with flat ribbon geometry. For this procedure, however, significant forces are sometimes needed for the coiling, which is clear, in particular, in the detailed view of FIG. 2b on the cross section Q, which deviates differently than in the partially open area of FIG. 2a from an ideal rectangular form on all side lines and at the corners, but still has nearly identical width and thickness.

(25) FIGS. 3a and 3b show one option for manufacturing the surface-area contact between the coiled resistive wire 105 with flat ribbon geometry and a connector assembly 106 for an electrical heating element 100 shown in sections. In this example, the connector assembly 106 consists on one hand from the connector pin 106a made from nickel as the connection element, whose diameter is adapted to the inner diameter D2 of the coiled resistive wire 105 with flat ribbon geometry, and on the other hand from the tube 106b made from, for example, copper, whose tube opening 107 likewise corresponds to the inner diameter D2 of the coiled resistive wire 105 with flat ribbon geometry and whose outer diameter is adapted to the outer diameter D2 of the coiled resistive wire 105 with flat ribbon geometry. One section of the connector pin 106a is pushed into the interior of the coiled resistive wire 105 with flat ribbon geometry so far that it almost completely passes through two coils and is welded to these coils, as the schematically shown weld seams 108 are intended to illustrate. For increasing the conductance value, the rest of the connector pin 106a is pushed into the tube 106b; here, e.g., a press-fit contact can be formed.

(26) The variant shown in FIGS. 4a and 4b differs in that the connector assembly 106 there has, as an additional component, a second connector pin 106c that is made from copper and is adapted to the inner diameter of the tube 106b and is pushed due to contact with the connector pin 106a from the side facing away from the coiled resistive wire with flat ribbon into the tube 106b and further improves the conductance value of the connector assembly 106. Because this is substantially the only difference, identical reference symbols are otherwise used and refer to the description for FIGS. 3a and 3b.

(27) FIGS. 5a and 5b illustrate another option for manufacturing, for an electrical heating element 200 shown section-wise, the surface-area contact between the coiled resistive wire 205 with flat ribbon geometry and a connector assembly 206, which consists, in this example, only from a tube, the connection element, made, for example, from copper. Here, one end section 205a of the coiled resistive wire 205 with flat ribbon geometry is shaped so that it is adapted to the tube opening 207 of the tube, and the electrical surface-area contact is manufactured in that the end section is inserted into the tube opening 207 and compacted.

(28) FIGS. 6a and 6b show an alternative to the embodiment of FIGS. 5a and 5b. Here there is also, for electrical heating element 200 shown section-wise, a surface-area contact between the coiled resistive wire 205 with flat ribbon geometry and a connector assembly 206, which consists of the tube, the connection element, made only from, for example, copper.

(29) The difference consists substantially only in that the end section 205b of the coiled resistive wire 205 with flat ribbon geometry is adapted to the tube opening 207 of the tube such that, in this end section, the coil outer diameter is reduced such that it corresponds to the diameter of the tube opening 207 of the tube. The electrical surface-area contact can be manufactured in that the end section 205b of the coiled resistive wire with flat ribbon geometry is inserted into the tube opening 207 and compacted.

(30) The variant of the electrical heating element 200 shown in FIGS. 7a and 7b differs in two essential aspects from the variant of FIGS. 6a and 6b:

(31) First, here, the end section 205c of the coiled resistive wire 205 with flat ribbon geometry is also adapted to the tube opening 207 of the tube such that, in this end section, the coil outer diameter is reduced such that it corresponds to the diameter of the tube opening 207 of the tube.

(32) The transition of the coil outer diameters is here shaped, however, so that the transition is not between two coils, but instead between a coil 205d, whose coil outer diameter is different at the opposing edges of the coil.

(33) Second, in addition to the tube 206a, the connector assembly 206 has a connector wire 206c made from a material with electrically good conductive characteristics and the coil inner diameter in the end section 205c of the coiled resistive wire 205 is dimensioned such that the connector wire 206c can be inserted into the coils of the end section 205c of the coiled resistive wire 205 with flat ribbon geometry. Then the tube 206a of the connector assembly 206 can be pushed on the outside onto the end section 205c of the coiled resistive wire 205 and the contact can be manufactured by a compacting process, so that the tube 206a and the connector wire 206c form the connection elements.

(34) In principle, these two changes with respect to the embodiment of FIGS. 6a and 6b are dependent on each other and can be used individually for modifying the embodiment. Thus, the transition to the end section 205a of the coiled resistive wire 205 with flat ribbon geometry can be realized without the connector wire 206c in the embodiment according to FIGS. 6a and 6b with a coil that is shaped like the coil 205d. Likewise, the end section 205b from FIGS. 6a and 6b can be shaped so that the coils belonging to the end section have an open inner diameter that allows the use of a connector assembly 206 with the tube 206a and the connector wire 206c.

(35) The embodiment of FIGS. 8a and 8b shows another variant. The electrical heating element 300 according to this variant has a connector assembly 306 that consists only of one connector pin as the connection element, which can be made, for example, from nickel, and also a coiled resistive wire 305 with flat ribbon geometry, whose end section 305a is shaped to be able to form an electrical surface-area contact with the connector assembly 306.

(36) To realize this, the shaped end section 305a of the coiled resistive wire 305 with flat ribbon geometry is provided with a bulge 305b on its inside, where the direction of curvature of the bulge 305b corresponds to the direction of curvature of the outer diameter of the connector pin of the connector assembly 306 and is adapted to this outer diameter.

(37) FIGS. 9a and 9b show an electrical heating device 1 before and after the compacting process. The electrical heating device 1 has a tubular metallic sheath 2, in whose interior an electrical heating element 4, which consists of a coiled resistive wire 5 with flat ribbon geometry and connector assemblies 6, 7, is inserted section-wise and is electrically isolated with electrically isolating material 3, e.g., magnesium oxide, from the tubular metallic sheath 2. The flat side of the flat ribbon runs parallel to the not-shown coil axis. The electrical surface-area contact between the coiled resistive wire 5 and the connector assemblies is realized by means of connector pins 6a, 7a, which are part of the connector assemblies 6, 7, and were described in essentially the same way as above with reference to FIGS. 3a, 3b. One difference, however, is that there is no welding here, but instead a press-fit contact is formed in the compacting process.

(38) FIG. 10 shows another example option for providing a coiled resistive wire 405 with flat ribbon geometry. This configuration starts with a tubular resistive wire 401, in which a helical-line-shaped groove 403 passing through the tube wall is cut with a laser 402, in order to generate the coils 404.

(39) It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the present invention as defined by the appended claims.

LIST OF REFERENCE SYMBOLS

(40) 1 Electrical heating device 2 Metallic sheath 3 Electrically insulating material 4,100,200,300 Electrical heating element 5,10,20,105,205,305,405 Resistive wire 6,7,106,106,206,206,306 Connector assembly 6a,7a,106a Connector pin 21 Barrel 106b,206b Tube 106c Second connector pin 107,207 Tube opening 108 Weld seam 205a,205b,205c,305a End section 205d Coil 206c Connector wire 305b Bulge 401 Tubular resistive wire 402 Laser 403 Helical groove 404 Coil Q,Q Cross-sectional surface area B Width D1 Outer diameter D2 Inner diameter H Height S Distance W Coil Aw Coil axis