Terminal device for a tubular heating device with integrated fuse

Abstract

A terminal device for connecting a heating apparatus with an electricity supply, in particular for a tubular heating apparatus for household appliances, wherein the heating apparatus includes at least one electric resistance heating element, comprises a mounting and reception section arranged for being electrically connected with the electric resistance heating element of the heating apparatus, a connector section arranged for being electrically connected on its one end side with an electrical power supply and on its other end side with the mounting and reception section, and a thermal fuse unit for detecting an excess temperature of the heating apparatus, which is in heat transfer contact with at least the mounting and reception section and which is connected in the electric supply circuit for supplying the electric resistance heating element of the heating apparatus with electricity. The mounting and reception section comprises a cavity for receiving the thermal fuse unit.

Claims

1. A terminal device for connecting a heating apparatus, in particular a tubular heating apparatus for household appliances, with an electricity supply wherein the heating apparatus includes at least one electric resistance heating coil, comprising: a conical mounting and reception section made of a material of good heat transfer and high electrical connectivity arranged for being electrically connected with the electric resistance heating coil by inserting the mounting and reception section inside the electric resistance heating coil; a connector section arranged for being electrically connected on a first end side with the electricity supply and on a second end side opposite the first end side along a central axis of the conical mounting and reception section with the mounting and reception section; and a thermal fuse unit for detecting an excess temperature of the heating apparatus, which is in heat transfer contact with at least the mounting and reception section and which is connected in an electricity supply circuit for supplying the electric resistance heating element of the heating apparatus with electricity; wherein the mounting and reception section comprises a cavity; wherein the thermal fuse unit is completely recessed in the cavity; wherein the thermal fuse unit comprises at least one thermo-sensitive pellet element which is provided for melting and cutting-off the electricity supply of the electric resistance heating element of the heating apparatus when the temperature of the mounting and reception section exceeds a predetermined temperature; wherein the cavity comprises an end panel and the thermo-sensitive pellet element is in direct contact with the end panel of the cavity of the mounting and reception section; wherein the end panel is a wall of the cavity that is perpendicular to a central axis of the cavity and to the central axis of the conical mounting and reception section; wherein the connector section fits inside of the cavity of the mounting and reception section and has a tapered end.

2. The terminal device according to claim 1, wherein the mounting and reception section is formed in one piece.

3. The terminal device according to claim 1, wherein the mounting and reception section is formed by a mounting section component and a reception section component wherein the outer diameter of the reception section component is at least substantially equal to or less than the outer diameter of the mounting section component.

4. The terminal device according to claim 3, wherein the mounting section component comprises at its end facing to the reception section component at least one centering element.

5. The terminal device according to claim 1, wherein the thermal fuse unit comprises at least one movable contact element being arranged in the electricity supply circuit for the electric resistance heating element of the heating apparatus and being urged against the thermo-sensitive pellet element by means of a first elastic element.

6. The terminal device according to claim 1, wherein the thermal fuse unit comprises a movable contact element being arranged in the electricity supply circuit for the electric resistance heating element of the heating apparatus and being urged against the connector section by means of a second elastic element.

7. The terminal device according to claim 5, wherein the movable contact element has elastic properties.

8. The terminal device according to claim 5, wherein the movable contact element has an outer diameter larger than the inner diameter of the cavity, wherein an outer circumferential edge area of the movable contact element can be bent such that the outer circumferential edge area of the movable contact element has a plane contact area with the inner circumferential surface of the cavity.

9. The terminal device according to claim 3, wherein the first and the second elastic element are arranged on both sides of the movable contact element.

10. The terminal device according to claim 5, wherein the connector section comprises a first side end for being connected with the electricity supply for the electric resistance heating element of the heating apparatus and a second side end for being connected with the movable contact element.

11. The terminal device according to claim 1, wherein the connector section comprises on its side end facing to the thermal fuse unit when the terminal device is assembled, a contacting portion having an outer diameter being smaller than the inner diameter of the cavity, and on its free end an end face forming an electrical contacting surface for the movable contact element.

12. The terminal device according to claim 11, wherein the contacting portion is provided on its outer circumferential surface at least partially with an electrically insulating covering.

13. The terminal device according to claim 1, wherein the mounting and reception section and the connector section are assembled together by positive locking.

14. A tubular heating apparatus, in particular for household appliances, comprising: a tubular casing; at least one electric resistance heating element embedded within an insulating material being provided within the tubular casing; and a terminal device according to claim 1 for connecting the at least electric resistance element of the heating apparatus with an electricity supply.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

(1) In the drawings:

(2) FIG. 1 shows a side view of a first exemplary embodiment of a terminal device according to the invention

(3) FIG. 2a illustrates a conical mounting section and a cylindrical reception section of the terminal device shown in FIG. 1;

(4) FIG. 2b shows a cylindrical connector section of the terminal device shown in FIG. 1;

(5) FIG. 3a illustrates a three-dimensional perspective and exploded view of the terminal device shown FIG. 1 including a thermal fuse unit;

(6) FIG. 3b shows a three-dimensional perspective and exploded view of the thermal fuse unit depicted in FIG. 3a in more detail;

(7) FIG. 3c illustrates in greater detail a cross-sectional side view of a part of the reception section marked by circle A in FIG. 2a and including the thermal fuse unit of the inventive terminal device;

(8) FIG. 4 shows a two-component layout according to a second exemplary terminal device according to the invention.

DETAILED DESCRIPTION

(9) A first example of a terminal device 10 for a heating apparatus (not shown) according to the invention will be described in the following with reference to FIGS. 1 to 3c.

(10) As can be seen from FIG. 1, terminal device 10 having center axis M, shows the exterior appearance of a spear or a crossbow bolt, respectively. It comprises a conical mounting section 20 forming the tip of the spear, a cylindrical middle or reception section 30 being a first part of the shaft of the spear, and a cylindrical end or connector section 40 forming the second or remaining part of the shaft of the spear. Moreover, as also can be seen from FIG. 1, the combined axial lengths of mounting section 20 and reception section 30 together is almost equal to the axial length of connector section 40 wherein the axial length of mounting section 20 is shorter than the axial length of reception section 30.

(11) Conical mounting section 20 shown in greater detail in FIG. 2a, is used for connecting a heating element (not shown) of the heating apparatus, in particular an electric resistance heating element with terminal device 10 and via terminal device 10 with a power source or electricity supply, respectively (not shown). Conical mounting section 20 is formed by a right cone 22 which is symmetrically to central axis M of terminal device 10 and which comprises tip 24. At the end of cone 22 facing in the opposite direction to tip 24 of cone 22 or facing in the direction of reception section 30, respectively, a cylindrical transition portion 26 is integrally arranged with cone 22 which provides a transition from cone 22 to reception section 30. Cylindrical transition portion 26 has an at least substantially circular cross-section and a diameter which is a bit greater than the diameter of the base of right cone 22. Conical mounting section 20 is made from a material of good heat transfer property and high electrical conductivity, like copper or steel.

(12) If the heating element is formed by an electric resistance heating wire being bent in the shape of a spiral or coil, respectively, with an inner diameter larger than the outer diameter of the tip area of cone 22, the coil can be slid on cone 22 with several windings and can be fixed to cone 22 or conical mounting section 20, respectively, for instance by welding, such as laser welding or any other suitable connection or attachment method.

(13) Reception section 30 shown also in greater detail in FIG. 2a, is integrally formed with cylindrical transition portion 26 or conical mounting section 20, respectively. In such a case, mounting section 20 and reception section 30 can be combined to one element and can be designated as a mounting and reception section 20, 30. However, in different examples, mounting section 20 and reception section 30 may also be designed as separate components joined together by suitable connection means (cf. FIG. 4), or might include parts comprising or consisting of non-conducting material. In the present embodiment, reception section 30 is made from a material of good heat transfer characteristic and high electrical conductivity, like copper or steel.

(14) Reception section 30 has a cylindrical shape with an at least substantially circular cross-section and with segments having different cylindrical diameters as shown in FIGS. 1 and 2a. Reception section 30 comprises on its free end 32 facing to connector section 40, a cavity 34. Cavity 34 has a circular cross-section and extends from end 32 of reception section 30 inside reception section 30. Furthermore, cavity 34 opens towards the outside. Inside cavity 34, a thermal fuse unit 50 can be arranged as explained below in conjunction with FIGS. 3a to 3c.

(15) As can in particular be seen from FIG. 3c, cavity 34 comprises in axial direction when starting from free end 32, a first longitudinally extending mounting segment 34a and a second longitudinally extending housing segment 34b following mounting segment 34a. Housing segment 34b ends at the end panel 34c extending at least substantially vertical to central axis M. Both segments 34a, 34b have at least substantially circular cross-sections. As can further be seen from FIG. 3c, the inner diameter of mounting segment 34a is a bit larger than the inner diameter of housing segment 34b although the outer diameter of reception section 30 in the area remains unchanged. In other words, the wall thickness of reception section 30 in the area of mounting segment 34a is less than in the area of housing segment 34b. As also can be seen from FIG. 3c, the axial length of mounting segment 34a is shorter than the axial length of housing segment 34b.

(16) Connector section 40 shown in greater detail in FIG. 2b, has, in consecutive order from bottom to top, a contacting portion 42, a middle portion 44 and a connecting portion 46 wherein middle portion 44 connects contacting portion 42 with connecting portion 46 in an integrally manner. Contacting portion 42 can be arranged at least partially inside cavity 34 when terminal device 10 is assembled. Of course, two or all three portions 42, 44, 46 can be designed as separate components and can be assembled together to form connector section 40. Additionally, connector section 40 or its components, respectively, are made from a material of good heat transfer characteristic and high electrical conductivity, like copper or steel.

(17) As can be seen from FIGS. 3b and 3c, contacting portion 42 comprises, in consecutive order from left to right, a first pin segment 42a, a fixing segment 42b and a second pin segment 42c which are formed in one piece. First pin segment 42a, fixing segment 42b and second pin segment 42c have at least substantially circular cross-sections. However, the outer diameter of first pin segment 42a is a bit smaller than the outer diameter of second pin segment 42c whereas the outer diameter of fixing segment 42b is relatively large compared to the outer diameters of first and second pin segments 42a, 42c. Moreover, the axial length of fixing segment 42b is shorter that the axial lengths of first and second pin segments 42a, 42c wherein the axial length of first pin segment 42a is shorter than the axial length of second pin segment 42c. At least first pin segment 42a and fixing segment 42b are arranged inside cavity 34 when terminal device 10 is assembled. The transitions between first pin segment 42a, fixing segment 42b and second pin segment 42c have one or several chamfers.

(18) First pin segment 42a, fixing segment 42b and second pin segment 42c are all integral to each other. Of course, two or all segments 42a, 42b, 42c can be designed as separate components and can be assembled to the connector section 40. Additionally, contacting portion 42, or its components, respectively, middle portion 44 and connecting portion 46 are made from a material of good heat transfer characteristic and high electrical conductivity, like copper or steel.

(19) Furthermore, contacting portion 42 is at least substantially completely encased at its outer circumferential surface by an electrically isolating covering 43. The free frontal end 42aa of first pin segment 42a and preferably a short further area of first pin segment 42a extending towards fixing segment 42b as can be seen in FIG. 3b, which are oriented in the direction towards mounting section 20 and which form an electrical contacting surface, are not covered by covering 43 so that an electrically conducting contact between contacting portion 42 or connector section 40, respectively, and thermal fuse unit 50, in particular a movable contact element 54 of thermal fuse unit 50, can be established as described below. Covering 43 can be made from a plastic material having a sufficient electrically insulating property as well as a sufficient resistance against heat, like poly(p-phenylene sulfide), polyether ether ketones or ceramics.

(20) Covering 43 follows the outer contour of contacting portion 42. In other words, the outer diameter of covering 43 is in the area of fixing segment 42b larger than in the area of first and second pin segments 42a, 42c. By the larger outer diameter of fixing segment 42b of contacting portion 42 compared to the outer diameters of first as well as second pin segments 42a, 42c of connector portion 42, covering 43 is axially fixed. Covering 43 can be mounted to contacting portion 42 in several ways, for example by spraying.

(21) In the area of second pin segment 42c, covering 43 has a declining tapered contour extending from fixing segment 42b to the end of second pin segment 42c facing to middle portion 44. The outer diameter of covering 43 in the area of fixing segment 42b is at least substantially equal to the inner diameter of mounting segment 34a of cavity 34. The wall thickness of covering 43 in the area of first pin segment 42a of contacting portion 42 is smaller than the wall thickness of covering 43 in the area of fixing segment 42b and second pin segment 42c of contacting portion 42. Thus, when contacting portion 42 of connector section 40 is mounted inside cavity 34, there is a space between the outer circumferential surface of first pin segment 42a or covering 43, respectively, and the inner circumferential surface of housing segment 34b of cavity 34.

(22) The free end of connecting portion 46 is formed by a contact pin 46a for providing an electrical connection between terminal device 10 and thus the heating apparatus as well as an electrical power source or electricity supply, respectively. The electrical connection can, for example, be formed by a plug connection. When terminal device 10 is built in the heating apparatus, connecting portion 46 lies outside the sheath of the heating device whereas contacting portion 42 and middle portion 44 are at least partially arranged inside said sheath. Moreover, at the end of middle portion 44 facing to connecting portion 46, there is arranged a riffle area 44a extending at least substantially completely around the circumference of middle portion 44 and provides a fixing area for a sealing element (not shown) which is attached to connector section 40 when mounted to the heating apparatus.

(23) As can best be seen in FIGS. 3a to 3c, thermal fuse unit 50 is arranged between reception section 30 and connector section 40. In particular, thermal fuse unit 50 is provided inside cavity 34 of reception section 30. Thermal fuse unit 50 comprises, in consecutive order from right to left, a first compression spring 52, a movable contact element or movable contacting plate 54, a second compression spring 56 and a thermo-sensitive pellet element 58.

(24) First compression spring 52 which can, for example, be a coil spring, is arranged on the outer circumference of covering 43 in the area of first pin segment 42a of contacting portion 42 and is supported on its side facing to fixing segment 42b of contacting portion 42 on the shoulder between first pin segment 42a and fixing segment 42b. First compression spring 52 acts against contacting plate 54 which is made by an electrical conductive material with some bending capacity. Contacting plate 54 has the shape of a crown including prongs 54a. The outer diameter of contacting plate 54 is larger than the inner diameter of the inner circumferential wall of housing segment 34b of cavity 34 so that prongs 54a of contacting plate 54 forming its circumferential edge area are bent in the direction of connector section 40 as can be seen in FIGS. 3a to 3c, when thermal fuse unit 50 is mounted in cavity 34. Moreover, contacting plate 54 lies in close contact to free end 42aa of first pin segment 42a being not covered by covering 43. Through this, an electrical contact is formed from the electricity supply via connector section 40, in particular its contacting portion 42, contacting plate 54 and its prongs 54a to reception section 30 and mounting section 20 so that the electric resistance heating element of the heating apparatus can be supplied with electrical energy.

(25) On the side of contacting plate 54 being opposite to its side facing to first compression spring 52, second compression spring 56 which can also be formed by a coil spring, is provided. Second compression spring 56 is tensioned between contacting plate 54 and thermo-sensitive pellet element 58. First and second compression spring 52, 56 exert a pressure force to contacting plate 54 such that contacting plate 54 is held in its position shown in FIG. 3c.

(26) Pellet element 58 which comprises a thermo-sensitive material selected depending on required temperature and melting characteristics, and which is formed substantially cylindrical, abuts with its end facing in the opposite direction to second compression spring 56, against end panel 34c of cavity 34 and is urged against end panel 34c of cavity 34 by first and second compression springs 52, 56 via contacting plate 54. Thus, pellet element 58 is clamped or pressed between end panel 34c of cavity 34 and the shoulder of fixing segment 42b of contacting portion 42. By this design, heat can be transferred directly from conical mounting section 20 and/or reception section 30 to pellet element 58 without an intermediate element, such as a copper sheath, like in the prior art. Between thermo-sensitive pellet element 58 and second compression spring 56 as well as between second compression spring 56 and contacting plate 54 respective disk-shaped abutting elements 60 can be provided to provide a well defined abutting surface for first and second compression springs 52, 56.

(27) Alternatively or additionally, pellet element 58 can be electrically conductive or comprise an electrical conductor embedded therein. Thus, electrical contact between conical mounting section 20, reception section 30 and connector section 40 can be established via connecting portion 46, middle portion 44, contacting portion 42, in particular second pin segment 42c, fixing segment 42b and first pin segment 42a, as well as contacting plate 54, second compression spring 56 and pellet element 58. In a further example, a conducting wire can be embedded within pellet element 58. Said conducting wire can, for instance, electrically connect to conical mounting section 20 and reception section 30 with contacting plate 54 and/or with first compression spring 52. Current flowing through said conducting wire can support the melting of thermo-sensitive pellet element 58 in case of excess temperature, such that the cut-off time can further be reduced.

(28) However, in a different example, thermo-sensitive pellet element 58 is not electrically conductive and electrical contact between conical mounting section 20, reception section 30, connector section 40 and an electricity supply is only established by means of connecting portion 46, middle portion 44, contacting portion 42, in particular second pin segment 42c, fixing segment 42b and first pin segment 42a, contacting plate 54, reception section 30 and mounting section 20.

(29) When thermal fuse unit 50 has been inserted into cavity 34 such that thermo-sensitive pellet element 58 abuts against end panel 34a of cavity 34, free end 32 of reception section 30 can be deformed such that it is crimped around the shoulder of covering 43 in the area of fixing segment 42b in order to form a positive locking between free end 32 and thus reception section 30 and fixing segment 42b and thus connector portion 40. Thermal fuse unit 50 is fixed inside cavity 34. Simultaneously, mounting section 20 and reception section 30 are joined with connector section 40 so that terminal device 10 is assembled and ready for use. However, any other suitable attachment procedure such as welding is also contemplated by a person skilled in the art.

(30) Next, it will be described how thermo-sensitive pellet element 58 ensures an electrical cut-off of the heating apparatus from an electrical power source upon detection of a predetermined excess temperature. Thermo-sensitive pellet element 58 is in direct contact with end panel 34c of cavity 34 of reception section 30. In other words, heat is directly transferred from conical mounting section 20 and/or reception section 30 to thermo-sensitive pellet element 58. In case that there is an excessive heat, i.e., the heating apparatus in which inventive terminal device 10 is mounted, reaches a temperature which is higher than a predetermined temperature, i.e., too high for a normal operation, this heat is directly transferred via mounting section 20 and/or reception section 30 to thermo-sensitive pellet element 58, without any additional heat conducting elements that would introduce heat transmission errors.

(31) Upon reaching a certain temperature which is preferably higher than the usual operating temperature, and is, for instance, 130° C., thermo-sensitive pellet element 58 starts to melt. As pellet element 58 melts, second compression spring 56 is not supported by pellet element 58 anymore and expands into the direction to end panel 34a of cavity 34. Due to the expansion, the pressure force applied by second compression spring 56 onto contacting plate 54 decreases. On the other side, first compression spring 52 still applies the same pressure force onto contacting plate 54. Now, the pressure force of first compression spring 52 applied to contacting plate 54 becomes higher than the pressure force of second compression spring 56 applied to contacting plate 54, such that contacting plate 54 moves towards the second compression spring 56 side and is thus separated from free end 42aa of first pin segment 42a. By moving contacting plate 54 away and apart from free frontal end 42aa of first pin segment 42a, the electrical connection between conical mounting section 20 and reception section 30 on the one side and connector section 40 on the other side is cut-off and thus also the connection between the electric resistance heating element and the electricity supply.

(32) In the following, a second exemplary terminal device 100 is described with reference to FIG. 4, which illustrates a schematic perspective view thereof. Components of the second embodiment having the same function as the respective component of the first embodiment described above in conjunction with FIGS. 1 to 3c are designated with the same reference number increased by 100. Moreover, only the differences between the first embodiment and second embodiment are explained in detail.

(33) Terminal device 100 comprises a conical mounting section component 120 and a reception section component 130 formed as separate elements. Reception section component 130 is formed as a sleeve having an at least substantially constant inner and outer diameter and being open at both ends. The outer diameter of reception section component 130 is at least substantially equal to the outer diameter of mounting component section 120 at least in the contact area of both components 120, 130.

(34) At the end facing to reception section component 130, mounting section component 120 comprises a cylindrical mounting and centering element 126 facing in the direction of not shown connector section 40 when terminal device 100 is assembled. Mounting element 126 has a smaller outer diameter than the circumferential outer diameter of reception section 130. Thermal fuse unit 50 (not shown) is in this example provided within the sleeve forming reception section component 130 which has an inner diameter at least substantially equal to the outer diameter of mounting and centering element 126. Thus, reception section component 130 can be slid on mounting and centering element 126 whereby it is centered and thus aligned against mounting section component 120. Subsequently, it can fixedly be connected with mounting section component 120 such that heat and/or electricity can be conducted from reception section component 130 to mounting section component 120, vice versa, for instance by laser welding or any other suitable welding technologies such as friction welding, or other attachment processes such as crimping, brazing, pressing and the like as known in the art. Reception section component 130 is preferably silver-coated or made of silver.

(35) Upon assembly, tubular reception section component 130 with thermal fuse unit 50 provided therein together with first pin segment 42a of contacting portion 42 of connector section 40 is slid over cylindrical mounting and centering element 126 and suitably connected thereto. Thermo-sensitive pellet element 58 is in contact with the end face of mounting and centering element 126. Moreover, prongs 54a of movable contacting plate 54 are in contact with the inner circumferential surface of reception section component 130.

(36) The various embodiments described above can be combined to provide further embodiments. Aspects of the embodiments can be modified, if necessary to employ concepts of the various patents, applications and publications to provide yet further embodiments

(37) These and other changes can be made to the embodiments in light of the above-detailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled. Accordingly, the claims are not limited by the disclosure.