ES2226677T3 - TUBULAR RADIATOR. - Google Patents

Abstract

Heating body has casing tube (12), heating element (14) embedded in insulating material (16), connecting elements (18), and protection element (28) mounted in end of casing tube and in thermal contact with heating element. Protective element resistance varies with heating element temperature. Element is PTC or NTC element forming component of measurement circuit independent of heating circuit for detection of resistance change.

Description

Tubular Radiator

The invention relates to a tubular radiator according to the preamble of claim 1 and claim 5.

Such tubular radiators are used, by example, in washing machines and in this case serve to heat the water of wash or wash water. For this purpose they have in the inside the wash tank through a passage in the wall of the Cuba.

In addition to tubular radiators it is necessary in modern washing machines a control device capable of record the temperature of the wash water so that it is possible a control or a regulation of the water temperature. To this end, the wall of the tank has other steps, or the flange of Radiator assembly has one step, to install the devices for recording the water temperature of the laundry. In addition, the Tubular radiator itself requires control in the case of malfunction, especially in case heat the tubular radiator even if there is no wash water in the tank (dry operation of the tubular radiator).

Due to the need to have to anticipate so much the tubular radiator as well as different control elements of the temperature inside the washer tank, the tank It has a series of steps. In addition to the corresponding higher cost of manufacturing, it is necessary to seal these steps well, which in turn time increases the production costs of the washing machine. Also due to the installation of the temperature control elements, it is An additional cost of assembly is necessary.

By European patent application O O86 465, it knows a tubular radiator of the type indicated above, in which it has disposed at the end of the envelope tube an element of safety in the form of a fuse, a PTC element (coefficient temperature positive), a sensor for the electronic circuit or a thermostat as a tubular radiator overload insurance. He Overload insurance serves to disconnect the power supply from current to the tubular radiator in the case of operation in dry. For this purpose, the security element is connected electrically and in series with the heating wire propeller to through a connecting stud and a tubular piece. The element safety form, therefore, an integral part of the circuit electric heating and is powered by electric current by the same. This known solution provides reliable protection against catastrophes in the event of a malfunction, especially in the case of dry running. Without However, a separate provision is still necessary for one or more fluid temperature recording elements a heat with the limitations described above.

By European patent application EP-A-2-
0 456 216, a tubular radiator is known in which the temperature control element is constituted by a ring that encloses the connecting stud and rests on the inner wall of the envelope tube.

In addition, by the European patent application
0 660 644, a tubular radiator is known in which a temperature sensor is disposed at the end of the tubular radiator envelope tube near its inner wall. This solution requires, due to the location of the temperature sensor near the inner wall of the envelope tube, a larger diameter, which in turn increases the passage in the tank and also increases the sealing problems. In addition, an increasingly compact construction is currently being sought in tubular radiators, which is not possible with this solution.

The objective of the present invention is to create a tubular radiator of the type indicated above which, with a compact construction and reliable protection against catastrophes allow a reduction in the number of steps in the tank, despite the existing control of pouring water temperature.

This objective is achieved with the characteristics of claim 1 and claim 5. In the other claims 1 to 4 and 6 to 13 give advantageous configurations of the invention.

Due to the use of an element of safety, which modifies its resistance value based on the temperature and is installed at the end of the envelope tube of the tubular radiator, it is possible to achieve with one and the same constructive component, in addition to the protection against catastrophes, also a regulation or a temperature control of the fluid or pouring water to be heated. Because the safety element is disposed at the unheated end of the envelope tube and, therefore, during operation the heat transmitted from the heating element to the heating element security is evacuated by the fluid to be controlled, the element of security is cooled by the fluid and thus acquires the temperature of the fluid. With each modification of the temperature it is modified also the resistance value of the safety element what is Registered by the control circuit separated from the circuit heating. Based on this modification of the resistance value is possible to find out the temperature of the fluid to be controlled.

However, additionally, the element of safety is in thermal conduction contact with the element of heating. Because of this, in case of catastrophe, that is, if not there is the fluid or cooling medium of the safety element, the heat generated by the heating element is transmitted directly to the security element. Because of this, the value of resistance is modified more quickly than in the case of normal operation, and as a consequence a case of catastrophe and a disconnection of the radiator can be performed tubular.

The security element that brings the two together functions - insurance in case of catastrophe and control of the pouring water temperature - is installed at the end of the tubular radiator envelope tube. Because of this I don't know you need, in addition to the passage for the tubular radiator, no other step on the wall of the washing tank or on the heating flange, So the production costs of the washing machine are reduced.

Finally, the proposed solution allows a arrangement of the security element so as a minimum approximately concentric to the axis of the envelope tube, due to which achieves a particularly compact construction of the tubular radiator Especially, it is possible to reduce the diameter with with respect to the tubular radiator known by the request for European patent 0 660 644.

As an element that modifies its value of resistance depending on the temperature can be provided one or several NTC elements or one or more PTC elements. Two elements of this type can be arranged, for example, in a tubular radiator at whose two ends of the envelope tube have been installed such security elements.

In addition, to achieve a compact construction, it can be provided that the security element is connected to the connecting element thermoconductively, but electrically insulated through a tubular part or an open sleeve. Here, the security element can be arranged inside of the tubular part coaxially in front of the connecting element. The connection element can be here a connection stud on whose end that faces the end of the envelope tube the tubular piece is fitted at the end of which also faces the end of the envelope tube has in turn the element of security. Because of this, as already indicated, the Tubular radiator diameter with good reaction behavior of the security element in case of catastrophe.

To be able to arrange the security element with electrical insulation of the tubular part, which serves as a connection from the heating element to the heating circuit, it has resulted advantageous if the security element is housed inside a bushing with electrical insulation facing the envelope of the cap Here it may be sufficient to isolate the security element simply with the help of ambient air. However, as in this case any small change of position can lead to a electrical contact with the inner surrounding wall of the cap, it is more advantageous if the security element is embedded in the inside of the bushing in an electrical insulation material.

In principle, the tubular part can be configured to serve directly as an electrical connection With the heating circuit. There is also the possibility of manufacture the bushing with a material of good conductivity electrical, so that it performs the function of connection with the heating circuit Since, as already indicated at In principle, the security element must also perform the catastrophic disconnection, it is also advantageous that the envelope of the bushing is made of a material with sufficient thermal conductivity, preferably of good conductivity thermal

To facilitate the assembly of the element security, it is advantageous that the connection element has in the end facing the front end of the envelope tube, a empty space open to the outside, in which the safety element with electrical insulation against the element of connection. To also isolate here again the element of Electrically safe connection element, it is possible to provide that the security element is housed in the empty space of the connection element inside insulation sealing resin electrical which however is thermoconductive enough. Alternatively, the security element can be housed in the empty space of the connecting element by means of a bushing electrical insulation that however is enough thermoconductive or good thermoconductivity.

The measuring circuit may be designed, by one side, like a resistance measuring circuit that measures directly changing the resistance in the safety element by means of an ohmmeter. There is also the possibility that the measurement circuit is a circuit that records modifications of current and / or voltage in the safety element due to its change of resistance

Other advantageous configurations as well as two Exemplary embodiments of the invention are explained below with help of the attached figures, in which:

- Figure 1 is a partial longitudinal section to scale increased through one end of a tubular radiator according to the invention, in a first exemplary embodiment.

- Figure 2, is a partial longitudinal section to scale increased through one end of the tubular radiator according to the invention, in a second exemplary embodiment.

The tubular radiator 10 represented only partially in figure 1 has a casing tube 12 with a circular cross section. The two front ends 12a of the Envelope tube 12 are open to the outside. It should be noted that in figure 1 only one of the two ends is shown front 12a.

The envelope tube 12 of the tubular radiator 10 it can be curved in any desired way, for example in the form of horseshoe, W-shaped, etc. As a material for the envelope tube 12 a material is used with sufficient or good thermal conductivity, for example stainless steel or aluminum.

As you can see in figure 1, inside of the heating tube 12 a heating element is arranged in shape of a helix heating wire 14 made of a material of resistance wire that heats with the passage of current. The helix heating wire 14 is embedded in a material 16 of electrical insulation but thermally conductive, as per example magnesium oxide. This insulation material 16 is compact, preferably, before full radiator assembly tubular 10.

The heating wire in helix 14 is connected conductively electrically and thermally at both ends 14a with a connection element in the form of a connection stud 18. The connection stud 18 has a first segment 18a directed towards the helix of the heating wire 14 and shaped as a tapered reduction tip in the direction of the wire propeller heater 14. The largest diameter of this first segment 18a corresponds essentially to the inside diameter of the propeller of the heating wire 14.

Several turns of the wire propeller heater 14 that follow directly to the free end of the wire propeller heater, they are tightly pressed together so closely that They are in touch. These turns are fixed on the stud of connection 18 by means of a suitable procedure, such as welding or similar.

The connection stud 14 also has a second segment 18b with an essentially cylindrical shape. He second segment cylinder 18b may have an outside diameter greater than the inside diameter of the helix of the heating wire 14 but smaller than its outer diameter. Because the diameter outside of the second segment 18b of the connection stud 18 is greater than the inside diameter of the helix of the heating wire 14 and the largest outside diameter of the first segment 18a of the connection stud 18 corresponding to the inside diameter of the heating wire propeller 18, a stopper of positioning of the heating wire propeller 14.

Since the helix of the heating wire 14 is extends only to connection stud 18 and not all the length of the envelope tube 12 forms one end not heating of the tubular radiator 10. The function of this end is not heated explained below in connection with the mode of operation of the tubular radiator 10 according to the invention.

The connection stud 18 is made of a material with sufficient or good thermal conductivity, as per copper example. However, it can also be of a material lower thermal conductivity such as steel, with the condition that sufficient conductivity is ensured electric

The first segment 18a as well as mostly the second segment 18b of the connection stud 18 are wrapped virtually entirely by insulating material 16. With the in order to prevent the penetration of moisture inside the tube envelope 12 to avoid the danger of insulating material 16 lose its electrical insulation characteristic, it has been arranged a resin insulating disc 20 in the area of the end of the second segment 18b of the connecting stud 18 that faces the outside or in the opposite direction of the wire propeller heater 14. This insulating disc 20 seals the material insulator 16 outwardly against moisture. He insulation disc 20 can be prefabricated on the connection stud 18 or melt in liquid state during tubular radiator assembly 10, preferably after compaction, where it hardens at the end of the insulating material 16 directed outwards.

As you can see in figure 1, a part of the second segment 18b of the connection stud 18 protrudes from the insulation disc 20 towards the open end of the radiator tubular 10. In this protruding part a piece has been fitted tubular 22 or a bushing with opening of a material of sufficient or good thermal conductivity such as the copper. The end of the tubular piece 22 facing the heating wire propeller 14 can rest on the disk of insulation 20. The tubular part 22 has been fitted onto the connection stud 18 so that there is a surface Enough of current and heat transition.

The tubular part 22 serves to connect the propeller of heating wire 14 with heating circuit no shown in Figure 1. For this purpose, the tubular part 22 is connected in electrical conductivity with a connection plate 24 arranged at right angles to the axis of the casing tube in the free end of the envelope tube 12 outside the end 12a. The connection plate 24 can also be aligned axially with the axis of the casing tube.

The electrical connection between the tubular part 22 and the connection plate 24 is made through an element of closure 26 inserted in the end of the wrapping tube 12a, in a plane located behind the plane represented in the drawing so It can't be recognized. The closure element 26 is made of heat-resistant plastic, ceramic or porcelain material or analogues and has a first segment 26a directed towards the helix of the heating wire 14 and having an outside diameter that corresponds to the inner diameter of the casing tube 12. As you can see in figure 1, the first segment 26a is embedded in its whole at the end of the wrap tube 12a.

The closing element 26 has a second essentially cylindrical segment 26b facing direction contrary to the helix of the heating wire 14 and that can have an outside diameter greater than the outside diameter of the tube envelope 12. The transition from the first to the second segment 26a, 26b of the closure element 26 forms a stop that serves its positioning In the same way, also the end of the first segment 26a of the closure element 26 facing the propeller of the heating wire 14 can serve as a positioning stop against the insulation disk 20. In principle, there is also the possibility that the two segments 26a, 26b are separated between yes, so that the closure element 26 is composed of two parts

The closing element 26 also has a through hole 26c whose axis essentially coincides with the shaft of the surrounding tube. In this hole 26c the tubular piece 22.

In addition, it is necessary to point out that the element of closure 26 may be designed not only as an element Prefabricated as described, it can also be cast in liquid state at the end of the envelope tube 12a after assembly of the other parts of the tubular radiator 10, where hardens later.

As can also be seen in Figure 1, the tubular piece 22 protrudes from the free end of the second segment 18b of connection stud 18. At this free end it has been introduced a security and control element 28. The element of safety and control 28 consists of a cylindrical bushing 28a made of a material with sufficient or good thermal conductivity such as copper, iron or steel, and whose end, which looks towards the helix of the heating wire 14, it is closed. The bushing 28a of the safety and control element 28 has an outside diameter that corresponds to the inside diameter of the tubular part 22 and the inner diameter of the hole 26c of the closure element 26.

The security and control element 28 is found inserted in the tubular part 22 so that there is a sufficiently large thermal contact surface between the outer contour of the security and control element 28 and the inner contour of the tubular piece 22, but the element of safety and control 28 does not come into contact with the free end of the second segment 18b of connection stud 18. In this context it should be noted that by selecting the depth of penetration of the safety and control element 28 can be regulated exactly the sensitivity to the temperature of the propeller of the heating wire or the temperature of the medium.

In order to get a good contact thermal conductivity between tubular part 22 and bushing 28a of the safety and control element, the tubular part 22 may be equipped with flexible needles not shown. In the event that the tubular piece 22 be a split bushing, this bushing can have an inside diameter slightly smaller than the diameter outside of bushing 28a of the safety and control element so that the split bushing rests flexibly on the bushing 28a of the safety and control element.

Inside the security element and control 28 an NTC element 28b has been arranged which can also be a PTC element. The NTC element 28b is embedded in a mass 28c of electrical insulation that, however, has enough thermal conductivity, for example in a resin mass. Because the element NTC 28b is in contact with thermal conductivity with the heating wire propeller 14 through the mass 28c thermally conductive, bushing 28a thermally conductive, the tubular piece 22 and the connection stud 18, however it is electrically insulated in front of the heating circuit.

The NTC element 28b made in the form of a sphere or pill and that, if appropriate, can be coated with a layer of electrical insulation, is connected through two lines of 28d separate connection with a safety and control circuit or of measurement not shown. The two connection lines 28d leave of the bushing 28a at the end facing the opposite direction from the heating wire propeller 14 and are joined with others corresponding elements of the safety and control circuit. He safety and control circuit is separated from the circuit heating. It can be made as a measuring circuit of the resistance or as a measuring circuit that measures the fall of current intensity or voltage change in the NTC element 28b due to a change in resistance.

As you can see in figure 1, the bushing 28a slightly protrudes from the closure element 26 and the part that Excel has a larger diameter. This way you get, from again, a positioning stop that determines the position of the bushing 28a when inserted into tubular part 22. However, there is also the possibility that the bushing 28a ends inside of the closure element 26 and that only the lines of connection 28d. In this case, the hole 26c can be closed so adequate.

The operating mode of the security element and control is as follows:

During normal operation of the radiator tubular 10, the power supply of the wire propeller heating 14 is done through the heating circuit, of so that the propeller becomes incandescent. The heat generated by the heating wire propeller 14 is transmitted through the insulation material 16 to casing tube 12 and from this to fluid to heat, in most cases water. Because the safety and control element 28 is connected in conductivity thermal with the heating wire propeller 14 through the connection stud 18 and tubular part 22, also heats up the NTC element 28b. Due to its material characteristics it thus modifies its resistance value. This is registered by the safety and control circuit.

During this normal operation, the end of the unheated wrapping tube 12a is surrounded and cooled by the fluid to heat. Because the fluid cools the end 12a not heated, the security and control element 28 acquires, as minimum, the temperature of the fluid to be heated. He heat transmitted by thermal conduction from the propeller of the heating wire 14 to the security and control element 28 is evacuated by the cooling fluid, so that the element of security and control 28 has at least approximately fluid temperature and record. Since the value of element resistance NTC 28b changes in a defined way in temperature function (in most cases so proportional) also the safety and control circuit can record the temperature of the fluid throughout the entire spectrum operational Through a corresponding programming of a control device not shown, it can be determined that the Operation has no defects. In addition, it can be controlled or regulate the fluid temperature. If necessary, this too maintenance and / or operation personnel can be indicated with help of a corresponding indicating device.

Additionally, with the solution according to the invention it is possible to indicate on the indicating device eventually the formation of scale in the tubular radiator 10. In the case of scale formation in the tubular radiator 10, a reduction in the capacity of cooling by the surrounding fluid, which modifies the temperature recorded by the security and control element 28. This modification is essentially expressed in a change in the value of output or basic value, where, however, the increase in temperature and, therefore, the change in the resistance value of the NTC element 28b against the state without inlays remain same. If this change of the basic value is registered by the control device mentioned above, the control device already mentioned can indicate it to the user so that the latter you can take the corresponding measures, such as the Elimination of scale.

In the case of a defect, for example in the case of a dry operation (ie if the tubular radiator 10 is working even if there is no fluid to heat), the temperature inside the envelope tube 12 increases greatly speed because there is no refrigerant fluid that extract the heat generated. At this rapid and sharp increase in temperature also follows the resistance value of the NTC element 28b, so it is also possible to register it by the circuit of Security and control. With it you can disconnect then The heating circuit.

In Figure 2, a second example of 10 'tubular radiator version. The difference of this one with the first exemplary embodiment explained with reference to figure 1, it consists in that instead of the tubular piece 22 and the bushing 28a, the connection stud 18 'is longer and has in its second segment 18b 'an empty space 18c open to the outside in the direction opposite to the helix of the heating wire 14. Inside of the empty space 18c the element of safety and control 28 composed of the NTC element 28b and the mass 28c thermally conductive. The NTC element 28b in turn is connected to the safety and control circuit through lines connection 28d. The remaining structure of this 10 'tubular radiator and its operating mode correspond to the first execution example described in relation to figure 1.

Claims (13)

1. Tubular radiator for fluid heating with at least one casing tube (12), with at least one heating element (14) embedded in an electrical insulating material (16) and arranged inside the casing tube (12), with connection elements (18) arranged at the end (12a) of the casing tube (12) and through which the heating element (14) is connected to an electric current source, and with at least , a safety element (28b) disposed at the end of the casing tube (12a) that is in contact with thermal conductivity with the heating element (14) and which is an element that changes its resistance as a function of the temperature of the element of heating (14), safety element that is an integral part of a measuring circuit separate from the heating circuit, measuring circuit with which the change of resistance of the safety element (28) can be recorded, characterized by that the safety element (28b) is embedded inside a bushing (28a) in an electrical insulating material but with thermal conductivity, bushing (28a) that is connected to a connecting element (18) through a piece tubular (22). 2. Tubular radiator according to claim 1, characterized in that the material of the bushing (28a) is a material with sufficient thermal conductivity. 3. Tubular radiator according to claim 1 or 2, characterized in that the shell of the bushing (28a) forms part of the connection of the heating element with the electric heating source. 4. Tubular radiator according to one of claims 1 to 3, characterized in that the connecting element is a connecting stud (18) at whose end (18b) facing the end of the casing tube (12a) the tubular part has been fitted (22) at whose end, which also faces the end of the casing tube (12a), the bushing (28a) has been fitted. 5. Tubular radiator for fluid heating with at least one casing tube (12), with at least one heating element (14) embedded in an electrical insulating material (16) and arranged inside the tube envelope (12), with connection elements (18) arranged at the end (12a) of the envelope tube (12) and through which the heating element (14) is connected to an electrical source, and with at least a safety element arranged at the end of the casing tube (12a) that is in contact with thermal conductivity with the heating element (14) and which is an element that changes its resistance as a function of the temperature of the heating element (14), safety element that is an integral part of a measurement circuit separate from the heating circuit, a measurement circuit that can record the resistance change of the safety element (28), characterized in that the connection element (18 ) has at its end facing the front end (12a) of the casing tube (12) an empty space (18c) open to the outside in which the electrically insulated but thermally insulated safety element (28b) is housed towards the element connection (18). 6. Tubular radiator according to claim 5, characterized in that the safety element (28b) is housed in the empty space (18c) of the connection element (18) by means of molten resin (28c) of electrical insulation but of thermal conductivity. 7. Tubular radiator according to claim 5, characterized in that the safety element is housed in the empty space (18c) of the connection element (18) with the help of an electrically insulating but thermally conductive bushing. 8. Tubular radiator according to one of claims 5 to 7, characterized in that the connection element is a connection stud (18). 9. Tubular radiator according to one of claims 1 to 8, characterized in that the measurement circuit is a resistance measurement circuit. 10. Tubular radiator according to one of claims 1 to 8, characterized in that the measuring circuit is a circuit for measuring the current drop. 11. Tubular radiator according to one of claims 1 to 8, characterized in that the measuring circuit is a circuit for measuring voltage changes. 12. Tubular radiator according to one of claims 1 to 11, characterized in that the safety element is a PTC element. 13. Tubular radiator according to one of claims 1 to 11, characterized in that the safety element is an NTC element (28b).