EP1110429B1 - Electric heating device and method for operating an electric heating device - Google Patents

Abstract

The invention relates to an electric heating device for heating a fluid, especially an air current, comprising a supporting device configured for accommodating a heating spiral. The inventive heating device comprises a plurality of support elements which can be axially joined to one another to produce at least one continuous, axially extending flow channel for the fluid. The inventive heating device also comprises an electric temperature probe which is provided on the outlet side and whose supply lines are led to a connecting module that is situated on an inlet side and arranged on the heating device. The connecting module which can be connected to control electronics supports an electronic memory module that is individually assigned to the heating device. Said memory module is configured for the non-volatile storage of individual measured and test values of the heating device, including storage of an individual test value of the temperature probe at a working temperature.

Description

The present invention relates to an electric heater according to the preamble of claim 1 and a method of operating a heater.

A generic device in the form of an electrical Radiator is known from the applicant's EP 0 123 698 B1. For the first time this device showed one out of one A plurality of radiator elements with a circular cross section composite radiator, which is a continuous, offers cylindrical outer surface, while in the interior of the cylindrical body axial flow channels for an air flow as well as crossing these flow channels Spiral elements made of heating wire material are provided. in the The result was with this device from the prior art already a compact arrangement can be realized, which with regard to Fluid heating and flow properties for that Fluid has advantageous properties.

However, in this device in particular Multi-stage, piece-wise construction of a heating coil as a production technology complex and in the control or in Heating behavior proved to be problematic. That's how it comes about in particular by the between successive annular spiral segments thermal bridges, and beyond is the voltage drop along the chain of the successive Helical segments problematic.

Furthermore, the radiator is cylindrical in this publication Body with i.w. homogeneous outer surface described in particular, however, the heat-insulated assembly of this body for example in a plastic housing of a hot air blower turns out to be difficult and manually complex.

From DE-A-4 343 256 a hot water device is known which has a temperature error detection circuit. The Circuit is equipped with control electronics. The The heater of the water heater is switched off when the Deviation of the actual temperature from the target temperature one exceeds a certain value and this definitely does not occur an operational functioning of the described Water heater is attributable.

Finally, generic, known radiators have the Disadvantage on that, due to assembly or unavoidable Scattering in the material used, tolerances of the heating coils etc. a control of the heating coil up to the theoretical possible limit load or not close to it is otherwise numerous within a series produced Devices become prematurely unusable due to overheating.

The object of the present invention is therefore a generic Heating device with regard to its heating properties, their mechanical and assembly properties as well with regard to their maximum drive power improve.

The task is performed by the heater with the features of claim 1 and the method with the Features of claim 8 solved.

Advantageously, it enables the invention provided electronic storage device, for which preferred Modular heating device specifically measured, to record individual parameters directly on the module and for a later, electronic operation control in the device, for example a hot air blower to deliver. According to the invention it is provided that in particular an individual temperature sensor measured value according to Test measurement of the relevant heating module stored in the memory is so that one to be connected to the heating module Control electronics then taking this individual into account Worth the device completely and up to the performance limit can control without causing any disadvantage Effects on the life of the heating coil due to overload comes. The memory module also offers advantageously the possibility of further, for example or to specify parameters specific to the supply network, so an upstream, universally oriented control electronics then by means of these values the user an individual on his needs as well as on the respective Local conditions, such as the network frequencies of a certain one Landes, offering tailored device without that, for example, an end user is tedious and / or prone to errors Settings.

As a result, especially for high-quality devices, the Ease of use and the power density of generic Heaters increased significantly.

Advantageous developments of the invention are in the subclaims described.

So it is particularly preferred that the connectable according to the invention Control electronics in such a way that the user the specification of one to be selected for the fluid to be heated Target temperature allows, then the invention Device by the output side according to the invention provided temperature sensor, the regulation of the Activation until this preset temperature is reached. This is done in an otherwise known manner usual control processes, which are particularly preferred on digital Level using a current temperature reading (obtained by the temperature sensors) on the one hand and the On the other hand, the default value can be realized.

It is also particularly preferred to also have a current actual or a target speed of the necessary for the fluid transport Include fan motor. Through a comprehensive regulation based on both the engine and temperature parameters on the one hand, it increases operational safety Way of ensuring that overheating, due to low engine speed, cannot occur, and on the other hand, reaching becomes more predetermined Set temperatures, if necessary, by reducing the Airflow ensured. Since, as mentioned, the present Invention the maximum use of heating options or the heating potential of the heating device, appears especially for the operation in the border area this regulation is particularly useful and advantageous.

It is also particularly preferred for the user to use a numerical one Output unit for immediate temperature display (optional target and / or actual temperature), because in particular professional users such information, about the temperature actually reached, may need for their work. It is further preferred to display this temperature with a time-dependent Switch mode.

It is also advantageous that the memory chip according to the invention for storing an electronic identifier for a Mains frequency with which to operate the heating device and / or for a temperature display format (degrees Celsius, degrees Fahrenheit) for processing by the control electronics is writable.

In an advantageous further development, the special design of the web-shaped sections simultaneous guiding and holding of a continuously spiral, coiled heating element, which in this way simply assembled and evenly heated, and by that Fluid can flow around. Especially in the temperature limit range the device according to the invention, which at a Melting temperature of the temperature coils exceeded such a training is advantageous and increases lifespan and operational reliability of one with the invention Heating device realized device the state of the art. At the same time, however proven, constructive realization of the flow channels between adjacent, radially extending struts a ceramic body between an outer ring section and an inner midsection that continues preferred, additional channels for supply lines or the like. can have obtained.

It is preferred that the spiral heating coil is consistently trained and generally about the extends the entire length of the flow channel, or else Spiral heating coil in several parts in the axial direction and is separately controllable.

Furthermore, in order to increase the heating power, it is further preferred two heating coils with different outside diameters, which are arranged along the same axis, by the invention Guide heater, being in this If the web-shaped sections each have two neighboring sections Have recesses for an inside or outside spiral. Such a heating coil arrangement is further preferred, which leads to the desired increase in heating output, through separate, individual control of the individual helices adjustable in performance, both described Versions with two over the entire channel length of the flow channel extending individual helices have proven, as well, in succession in the direction of flow arranged, double spiral pieces, which are controlled separately become.

Particularly advantageous according to a further embodiment the invention also has the cylindrical outer surface in each case a raised edge at the end, realized by corresponding ring heels on end pieces of the carrier elements. This creates a particularly simple and manufacturing technology cheap with an insulator or the like. material Wrapped receptacle, which then provides good thermal insulation the arrangement thus created in a surrounding Device housing ensures.

The inventive design of the web-shaped sections according to the spiral course or the spiral pitch the heating coil (s) it is necessary the individual support elements during assembly particularly precise to each other align so that the spiral course of the spiral is not interrupted becomes. This necessary alignment of the support elements Relative to each other is facilitated by the training provided centering pieces that have a non-rotating Allow assembly of the individual support elements.

According to a further preferred development, the connected to the heating coil or the temperature sensor Control electronics that a power control on a predetermined electrical power value, in particular the maximum power or slightly below the maximum power horizontal electrical power value, regulated becomes. More specifically, according to this advantageous Embodiment realized control means that the Speed of the fan motor provided in the context of the invention automatically influence (increase) that the heating the predetermined power value, e.g. 5/6 of the maximum power, receives. Such is particularly advantageous Embodiment when front nozzles with a small opening diameter in connection with the present electrical Heater at the outlet end of the flow channel be used, in particular by a Attachment nozzle with a very small diameter is the one emitted by the device The amount of heating energy drops and due to the training Readjustment of the fan speed, only dependent from the absorbed heating power, compensated could be.

Fig. 1:

eine perspektivische Ansicht eines Heizkörpers gemäß einer ersten Ausführungsform der Erfindung mit einer Mehrzahl scheibenförmiger Heizkörperelemente in montiertem Zustand (best mode);

Fig. 2:

eine Perspektivansicht einer zur Verwendung in der Anordnung gemäß Fig. 1 einsetzbaren, eingängigen, stufenlosen Heizwendel;

Fig. 3:

einen Längsschnitt durch ein gebläseseitiges Endstück der Heizelementanordnung gemäß Fig. 1;

Fig. 4:

einen Längsschnitt durch ein Mittelstück der Anordnung gemäß Fig. 1 entsprechend einer Schnittansicht gemäß der Schnittlinie IV-IV in Fig. 6;

Fig. 5:

einen Längsschnitt durch ein auslassseitiges Endstück der Anordnung gemäß Fig. 1;

Fig. 6:

eine Draufsicht auf ein scheibenförmiges Heizkörperelement der Anordnung gemäß Fig. 1;

Fig. 7 bis Fig. 10:

Teilschnitte der Strebenbereiche gemäß Schnittlinien VII bis X in Fig. 6;

Fig. 11:

eine Doppelwendelanordnung mit einer innenliegenden und einer außenliegenden Heizwendel zur Verwendung in einer Heizvorrichtung gemäß einer zweiten Ausführungsform der Erfindung;

Fig. 12:

eine alternative Ausführungsform zur Wendelanordnung der Fig. 11 mit einer vorderen (stromabwärts gelegenen) sowie einer hinteren (stromaufwärts gelegenen, jeweils bezogen auf ein Gebläse) Heizwendelanordnung aus innenliegender und außenliegender, parallelgeschalteter Heizwendel;

Fig. 13:

eine Perspektivansicht der Heizvorrichtung gemäß der zweiten Ausführungsform zur Aufnahme der Heizwendelanordnung gemäß Fig. 11 bzw. Fig. 12;

Fig. 14:

eine Draufsicht auf ein scheibenförmiges Heizelement der Anordnung gemäß Fig. 13;

Fig. 15:

eine Schnittansicht entlang der Schnittlinie XV-XV in Fig. 14;

Fig. 16 bis Fig. 19:

Teilschnitte eines Strebenbereichs entlang der Schnittlinien XVI bis XXI in Fig. 14 mit dem Verlauf der Wendelkanäle in Streben des Heizkörperelements der Fig. 14 und

Fig. 20:

ein Blockschaltbild eines Heissluftgebläses mit elektrischen Steuer- und Funktionskomponenten zur Steuerung und zum Betrieb der Heizanordnungen gemäß Fig. 1 bzw. Fig. 13.

Further advantages, features and details of the heating device according to the invention result from the following description of preferred exemplary embodiments and from the drawings; these show in

Fig. 1:

a perspective view of a radiator according to a first embodiment of the invention with a plurality of disc-shaped radiator elements in the assembled state (best mode);

Fig. 2:

2 shows a perspective view of a single-start, stepless heating coil which can be used in the arrangement according to FIG. 1;

Fig. 3:

a longitudinal section through a blower end piece of the heating element arrangement according to FIG. 1;

Fig. 4:

a longitudinal section through a center piece of the arrangement of Figure 1 corresponding to a sectional view along section line IV-IV in Fig. 6.

Fig. 5:

a longitudinal section through an outlet end piece of the arrangement of FIG. 1;

Fig. 6:

a plan view of a disc-shaped radiator element of the arrangement of FIG. 1;

7 to 10:

Partial sections of the strut areas according to section lines VII to X in Fig. 6;

Fig. 11:

a double coil arrangement with an internal and an external heating coil for use in a heating device according to a second embodiment of the invention;

Fig. 12:

an alternative embodiment to the coil arrangement of Figure 11 with a front (downstream) and a rear (upstream, each based on a blower) heating coil arrangement of internal and external, parallel-connected heating coil.

Fig. 13:

a perspective view of the heating device according to the second embodiment for receiving the heating coil arrangement according to FIG. 11 and FIG. 12;

Fig. 14:

a plan view of a disk-shaped heating element of the arrangement shown in FIG. 13;

Fig. 15:

a sectional view taken along section line XV-XV in Fig. 14;

16 to 19:

Partial sections of a strut area along the section lines XVI to XXI in FIG. 14 with the course of the spiral channels in struts of the heating element of FIGS. 14 and

Fig. 20:

13 shows a block diagram of a hot air blower with electrical control and functional components for controlling and operating the heating arrangements according to FIG. 1 and FIG. 13.

The heater of the first embodiment shown in FIG. 1 consists of a plurality of cylinders strung together disc-shaped radiator elements 10 (nine elements in the embodiment of Fig. 1), each as in 6 shows an annular outer region (outer ring) 12, a disc-shaped inner region 14 and a plurality connecting the outer ring 12 and the inner region 14, have radially extending struts 16.

A single radiator element 10, as in the sectional view 4, has an outer diameter of approx. 35 mm and is approx. 9 mm deep. For additional orientation of the elements next to each other according to FIG. 1 is the jacket side a marking groove 31 is provided, which at correctly seated individual elements 10 to the in Fig. 1 shown, continuous line pattern added.

The inner region 14 has a plurality i.w. circular Breakthroughs 18 on each other, in the arrangement of FIG. 1 are in alignment and can thus be moved through the Radiator arrangement of FIG. 1 extending longitudinally, continuously Form channels. More specifically, they prefer Radiator elements made of ceramic material 10 a square opening 19 in the center of the inner region 14, through which one in FIG. 1 only schematically indicated, square-shaped clamping element 20 can be performed and so for a firm, twist-proof hold of the plurality of elements 10 ensures. In addition, are on the disc-shaped interior 14 each radiator element 10 four conical projections arranged in the form of centering tips 22 around the center, which in each assigned center holes an adjacent element in the arrangement of FIG. 1 intervene and so for an exact positioning of the individual Elements to each other.

On both sides of the majority of the radiator elements 10 in FIG. 1 end pieces are provided, namely an entry-side (Blower side) end piece 24, which is a blower motor to convey a fluid (preferably air) through the radiator arrangement through, sitting next to each other, as well as on the opposite End of an outlet end piece 26. Both End pieces 24, 26 limit the radiator arrangement in this way of Fig. 1, being, as is apparent from the comparison the longitudinal sections through the individual elements 10, 24, 26 of FIGS. 3 to 5 results in both the entry-side End piece 24 and the outlet end piece 26 each a ring heel to their respective, external Have end face. A ring shoulder 28 of the outlet side End piece 26 forms a somewhat smaller one Outside diameter as a ring shoulder 30 of the inlet side End piece 24. The ring shoulders 28, 30 create a bordered on both sides by an edge Outer surfaces of the respective radiator elements 10 formed Sheath section, which for wrapping with an insulating film is trained and provided. More specifically allows this arrangement, insulating film compact, accurate position and mechanically reliable on the radiator arrangement of Fig. 1 to apply without this Precautions for guiding or attaching the insulating film should be hit.

The catchy and stepless heating coil shown in FIG. 2 32 runs inside the radiator arrangement of FIG Fig. 1, namely the coiled sections of the Heating coil 32 by at a suitable point in the struts 16th of the radiator elements 10 formed recesses or Breakthroughs. This mechanism results from the Sequence of the partial sectional views according to FIGS. 7 to 10, which the course of a formed in the respective strut 16 Show recess 34. 7 to 10, the Course over a circumferential angle of about 120 ° of the radiator element 10 of FIG. 6 show how the Recess 34 or the remaining web 16 in the circumferential direction successive striving so continuously change or move that the helix shape or the spiral course is continuously followed and the in the heating element 10 inserted heating coil 32 through the sequence of struts in the circumferential direction and continuously guided and supported in a spiral along its slope becomes. Overall, each disc-shaped radiator element thus forms 10 a support for a full turn the helix 32 so that by putting a plurality together of radiator elements 10 a correspondingly long Helix can be held and guided. As in FIG. 2 shown, both an outlet-side feed line 36 as well as an inlet-side supply line 38 by appropriate Openings 18 of the radiator element 10 lengthways the direction of extension of the radiator arrangement of FIG. 1 to the end of the connection, with the openings 18, as shown in FIG. 6, also suitable for this in a radial direction Have openings in the direction.

In addition, the arrangement of the radiator elements 10 with the openings in the interior of the individual elements Channels for additional lines, for example for one thermocouple which can be provided on the outlet-side end piece 26, on, the feed lines then in a corresponding manner at the entry end with associated evaluation electronics can be connected.

The one shown in FIG. 2 runs in the ready-to-use device Wendel, performed in the manner described above, in Area of the struts 16 between the outer ring 12 and the inner area 14 of a respective radiator element. This ensures that air flowing in the direction of arrow 42 in that entry-side end of the radiator arrangement of FIG. 1 enters through the outer ring 12 and inner region 14 limited, hollow cylindrical area is guided with optimized attack surface can flow around the coil and so with the best efficiency from the arrangement, to an outlet temperature from e.g. 600 ° heated, can escape.

Due to the stepless formation of the heating coil, it takes place above also an even, bridgeless heating of these Helix and thus the air flow instead, which in particular the life of the device can be increased considerably can. Finally, according to the further training, it is also possible towards the exit end of the arrangement - there already warmed air flows - a lower winding or to provide the helix density of the helix than on the entry side, with, more preferably, along this variation the spiral expansion can also take place continuously.

With reference to FIGS. 11 to 19, a described second embodiment of the present invention, considered the best embodiment in this respect becomes.

The one shown in Fig. 13 assembled in perspective view second embodiment, analogous to the first embodiment, from a series of individual radiator elements 44 to each other by means of a marking line 46 are aligned and on both ends by a connection side End piece 48 or an outlet side End piece 50 are limited. Again, both form here End pieces 48, 50 an edge for an intermediate, continuous outer surface, which in the above Way can be wrapped with insulating paper. Geometric the arrangement of FIG. 13 differs from the device 1 by a slightly larger outer diameter the middle radiator elements 44, namely in described embodiment about 45 mm, and by a slightly different arrangement of one inside 52 respective individual element lying openings 54 for the Supply lines to the heating elements.

More specifically, as shown in FIGS. 11 and 12, this embodiment provides that one (FIG. 11) and two (alternative embodiment FIG. 12) double helix (s) for heating the air flow between the inner region and the outer ring section of the respective one Care radiator elements 44. 15 through a central radiator element 44 (with a diameter of 45 mm, the element is approximately 8 mm thick in the exemplary embodiment shown), struts 58 which connect the ring section 56 to the inner region 52 can be in the region of the struts 58 connect, two helices with different helix diameters are guided, and the struts 58 have correspondingly helically extending or circumferentially stepped recesses 60 for this purpose. As the sequence of FIGS. 16 to 19 along the circumferential direction of FIG. 14 illustrates, the slope of an inside spiral 59, recognizable by inner recesses 60 _a , is also less than the slope of an outer spiral 61, guided in associated, outer recesses 60 _b in the respective struts 58. Here too, however, it is realized according to the invention that the coils can be guided continuously and continuously; in the case of the exemplary embodiment in FIG. 12, however, in two sections, which are divided into a front, outlet-side double spiral section 62 and a rear, fan-side (inlet-side) double spiral section 64 and each consist of a parallel connection of the inner and outer helix. The fluid is in turn supplied from the direction of the connections or feed lines to the coils.

As the plan view of an element 44 in FIG. 15 illustrates, is the number of supply lines due to the double spiral heating higher, and the number increases accordingly of the openings 54 provided in the interior area 52. As well as 14 or 15 can be seen, takes place analogously 6, an alignment of neighboring ones Radiator elements 44 to each other for the arrangement of 13 by means of truncated cone-shaped elevations 66, distributed around the circumference, provided on the ring portion 56 are and in the illustrated, not radially symmetrical Arrangement a clear fixation of the individual elements define each other in the circumferential direction.

In the assembled state of FIG. 13, the arrangement shown takes the radiator elements either the one-piece double spiral 11, or the divided double helix of Fig. 12, with appropriate interconnection or control of these helix arrangements each have two power levels can be activated: With regard to the Fig. 11 would only activate a first (low) heating level the inner heating coil 59, and on one second, higher heating level would then be the parallel connection both heating coils 59, 61 are activated.

In contrast, in Fig. 12 there is both the rear and the front double helix section 64, 62 each already from a parallel connection of the corresponding resistance heating elements, and accordingly a first heating level would the activation of one of the two double spiral sections provide, then at full load in a second To activate the heating level of the other in addition.

Point on the inlet side (i.e. directed towards the fan motor) the above-described embodiments one in the Fig. connection head, not shown, which, in addition to suitable Plug pins for connecting the respective radiator to the associated electronics, an EEPROM as with the electrical and test data of a respective device Storage element carries. More specifically are in this electronic memory module individual data with regard to heating type (one-stage / two-stage, one coil or two coils), temperature parameters (e.g. display in Degrees Celsius or degrees Fahrenheit), further adjustment values (concrete temperature behavior) and production data saved. At the end opposite this connection head a thermocouple (not shown in the figures) sits on the outlet side, whose temperature information is then also about the connection head can be tapped.

With reference to the block diagram of FIG. 20, the electrical circuitry and the control or signal flow during operation of the above-described embodiments are described below, the electronics 68 shown in FIG. 20 on a suitable carrier, for example a circuit board, in the housing of a hot air blower is included and communicates electrically with the connections on the heating module 70 (more precisely: the connection head on the arrangements shown in FIGS. 1 and 13). In the figures, the complexes "electronics" 68 and "heating module" 70 are delimited from one another by dashed lines, the electronics 68 also including the fan motor 72 in the form of a brushless DC motor (which in the assembled state causes air to flow through the Arrangements described), a motor control unit 74 for the electronic control of the motor 72 and for detecting an actual speed of the motor n _is , which has corresponding semiconductor components, a switching power supply and a control ASIC for the motor and in the manner to be described below by one central, processor-controlled control loop is controlled. A heating control unit 76 has triacs for switching the heating coil and optocouplers for zero-crossing detection in order to be able to determine the switch-on time with sufficient accuracy.

More specifically, the control unit 76 works with the first Heating line 78 and a second heating line 80 together (in In the case of the embodiment of FIG. 1, the second is omitted heating section; in the case of Fig. 12 for the second embodiment the heating strands mean the inner or outer heating coil 59, 61, and in the case of Fig. 12 the front or rear double helix section 62, 64).

The heating module 70 is in the implementation of the embodiments 13 or 13 dimensioned such that the Surface temperature of the heating wire for the coils close is at its melting point, so it's for maintenance an operating period to be guaranteed is necessary, that each individually made heating arrangement on the respective hottest point is measured by a test device, whereupon the specific properties of the Heating for electronic control or parameterization of the operating procedure can. For this reason, the aforementioned EEPROM is a reference number 82 in the block diagram of FIG. 20, immediately provided on the heating module and contains the respective product-specific ones Data as follows:

After the measurement on a test station, the main one is Measured value of a thermocouple voltage also on Heating module provided, realized as a Cr-Ni-Cr thermocouple Thermocouple 84 at a temperature of e.g. 600 ° C (maximum, desired operating temperature) at each hottest place saved. In addition, in the following technical information is stored in the memory chip: An expert for the supply network or the network frequency of an intended operating country, as follows the control for the motor unit when operating on a 50 Hz network changed in a 60 Hz network. Beyond that a value for the room temperature is given, which at a Temperature measurement without heating operation is displayed (Display offset); there is an indicator of whether one Central control unit to be explained later the temperature values to be output for the temperature display in degrees Celsius or degrees Fahrenheit are further advanced controller parameters for various Engine speed ranges are saved, which is the central Control unit used for engine control, and it finds a default using the specified parameters Control the inertia of a display control instead. Further the memory module 82 contains a reference temperature value for temperature compensation using a compensation measuring element 86 (thermocouple 84 created as Thermovoltage a measured value relative to a reference junction. However, since this reference point when operating the device is heated by means of the compensation measuring element 86, e.g. an NTC, the temperature of this cold junction be measured to the resulting error to compensate).

Other parameters individually assigned to a heating module are details of a type of heating (one or two heating lines), Duration of an ad to be set by a user Temperature setpoint (instead of a permanent one displayed actual temperature value), an automatic speed reduction at high temperature values and other status information. As a result, the specifically programmed Memory block 82 all heating and temperature relevant Parameters ready to connect the connected electronics 68 to provide the basis for an engine and heating control, which makes maximum use of the load capacity of the heating coils and still no unintended wear of the material causes. In this individually created for each heating module As mentioned, the memory chip is the most important Information the specifically measured thermocouple voltage of the Ni-CrNi element 84 at maximum operating temperature.

The heating unit 70 is operated by one in the electronics module 68 provided central control unit according to the specifications of the user or those stored in the memory module 82 Parameters controlled, the control unit in which Fig. 20 indicated by the dashed line 88, the has the following functional components (these can both be implemented by dedicated hardware circuits, as is immediately clear to the person skilled in the art, or else functionalities a microcontroller with the appropriate software or the like. Processor element). A comparison and Test module 89 receives the parameter data of EEPROM 82 from the heating module and also loads more from one separate EEPROM 90 read parameters and specifications.

After performing a comparison and plausibility check after the start of operation of the hot air device shown in FIG. 20, the in the event of a critical error to switch off the Heating and for issuing a service message on a display module 92 (display module with associated output controller) heating and motor control starts, being already checked at this point is whether a heater is plugged into the device, which one Configuration this heater has and what specific Temperature parameters measured with this heater and saved have been.

A current thermal voltage output by the thermocouple 84 is amplified via an amplifier unit 94 and fed to an A / C converter 96 as the actual temperature T _ist . N addition _to a speed set value of the A / C converter of the central control unit 88 also receives an externally specified by the operator temperature setpoint T _set as well. Furthermore, a compensation temperature T _{comp of} the compensation measuring element 86 is read in. Finally, the AD converter 96 also receives the current engine speed n _is the engine control unit 74, wherein the actual engine speed n _is monitored by means of an error detection unit 98, which is connected downstream of an engine control unit 100. If, for example, the speed of the motor should drop too much, for example due to dirt or foreign bodies on the paddle wheel, and thus no longer allow the necessary air to flow through the heating element, the central control unit 88 switches off the heating lines 78 and, if applicable, 80 and outputs them on the display unit 92 a corresponding error or service message.

One in bidirectional data exchange with the engine control unit 100 shown temperature control unit 102 is implemented as a digital PI controller. An interaction between engine control 100 and temperature control 102 takes place in this respect through mutual influence, than an increase in engine speed, a change in Control behavior for the temperature causes, and an increase the temperature a decrease in the engine speed because the air flow rate of the fan motor is so large that the temperature control without an automatic lowering of the Engine speed is not able at high set temperatures would be to set the required temperature.

Accordingly, the user can preselect a desired temperature value of the hot air escaping from the device by specifying a target temperature, which is displayed on the display unit 92 in the form of a digital, multi-digit (e.g. 7-segment display) display, and it is then controlled by the central unit Control unit 88 according to the currently recorded actual temperature value T _, the control output for the heating is increased until the predetermined target value is reached. The temperature is then kept at the desired level by means of a control loop. Depending on the specification, the display module 92 makes it possible to display the setpoint set by the operator for a predetermined time since the actuation of an actuating element until switching back to a display mode for an actual actual temperature T _ist .

In the manner described, it is thus possible to use a single-strand heating module (embodiment of FIG. 1) a hot air device with an output of about 1,700 watts realize while a two-strand apparatus (Fig. 13) a heating power of about 3,400 watts at, as described above, compact dimensions and long life in Continuous operation, enables.

According to a further preferred embodiment of the present invention finds a control of the one or two-strand heating coils with minimization of any Network disturbances and network perturbations take place. To this end is the total load for each heating branch during complete half-waves of the supply voltage switched, where, depending on a particular switching pattern, a gradual provision of services through control this indicates the on or off half-periods Switching pattern can be done. More specifically, one is Switching pattern within a predetermined time period T = k x 3,000 / [mains frequency in Hz], where k is a integer, natural number> = 2 and the switching pattern remains constant within each period T. For a network frequency of 50 Hz is a time period T = 60 ms or an integer multiple of it, and within that 60 ms each half-wave becomes single or double-stranded switched so that the total, switched DC power component remains zero within a period. While four possible with only one heating element Switching stages (0, 1/3, 2/3, full) arise with a heating system with two independently switched Strands (but during the same period T) total seven power levels by varying the switching pattern for whole, switched half-waves.

According to a further preferred embodiment of the present Invention is provided a scheme that in particular when using a small nozzle Diameter before the fluid outlet ensures that through such a nozzle reducing the outlet cross section emitted heating energy does not decrease.

This training is based on the knowledge that that of the present electric heater a workpiece transportable (heat) energy quantity i.w. of the electrical power supplied and of that Fan wheel generated dynamic pressure in the heating element depending is; the dynamic pressure is a measure of how much Fluid (air) at a predetermined outlet cross section can be transported by the fan wheel. at decreasing speed of the fan wheel decreases (in practical Realization almost proportional) the dynamic pressure inside the heating element and thus on the workpiece transferable amount of heat energy at constant temperature. A user now uses a front nozzle with a very small diameter (i.e. a correspondingly small Outlet cross section), the amount of energy released by the device decreases again, because of the reduction in cross-section the nozzle with the internal pressure kept constant Air volume drops and according to the controller the power consumption the heating coil reduced, since it is now with a smaller electrical power the required temperature can adjust.

Subject of the further development described by means of the fan wheel control concept it is now, automatically Increase the fan speed so that the heating averages e.g. 5/6 of the maximum electrical heating power receives. As long as the current engine speed value is below the actually set target speed and the control the heating coil does not exceed 5/6 of the maximum output must be used for temperature control a control loop in the central control unit the speed automatically to the maximum possible product Air volume and electrical heating output increased or adjusted.

Would, for example, at a preset, maximum target speed and a temperature of 600 ° C by the user the central control unit (micro-controller) otherwise the Reduce engine speed to a fixed, preset value, the normal operation of the invention The maximum possible speed value at the heater required temperature, would be used here small front nozzle the electrical power consumed decrease because the amount of air delivered drops and thus the Temperature control reduces the electrical output of the heater.

The speed control provided according to the training would with the same settings in normal operation (i.e. without Intent) work in the same way, however when using an attachment nozzle with a small cross-section cause the control unit to set the turbine speed increased until about 5/6 (sample value) of the total Heating power is reached on average, or the target speed is equal to the actual speed.

In this way, effective and control engineering easy to implement way of usually using the Use of narrow outlet nozzles connected to effect one Compensated for the reduction in the available heating energy become.

As a result, the control circuit variants described are possible together with one of the above Exemplary embodiments for the heating module, a heating device for a fluid, especially a hot air blower, to create which is extremely powerful with an even more compact design, high heating outputs with a precise temperature control, which is extremely user-friendly Way with one to be set by the user Set temperature works to combine. Heizmodulspezifische In this context, parameters and temperature data allow maximum tax benefits without the lifespan of the highly stressed heating strands.

Claims (10)

1. Electrical heating device for heating a fluid, particularly an airflow, having a supporting device designed so as to receive at least one heating coil (32), said supporting device having a plurality of support elements (10; 44) which can be added to each other in axial direction and are designed for producing at least one continuous, axially extending flow channel for the fluid,
   characterized by
   an electrical temperature probe (84) provided for at the exit side, the supply lines (40) of which are led to a connecting module located at the entry side of the heating device, the end module which is connectable with a control electronics supporting an electronic storage component (82) which is individually allocated to the heating device and provided for keeping individual measured values and test values of the heating device in a non-volatile way, including an individual test value of the temperature probe at a working temperature.
2. Device according to claim 1, characterized in that the supply lines of the electrical temperature probe are led in axial direction through allocated openings (18; 54) of the support elements (10; 44) to the connecting module.
3. Device according to claim 1 or 2, characterized in that the control electronics (68) connected with the at least one heating coil is designed for controlling a desired fluid temperature that can be preset by a user, depending on the individual test value and a current temperature signal of the temperature probe (84).
4. Device according to one of the claims 1 to 3, characterised in that the control electronics is designed for recording a rotational speed of a fan motor (72) moving the fluid through the heating device and for electronically controlling the fluid temperature, depending both on a real actual speed and on a preselectable desired speed of the fan motor.
5. Device according to one of the claims 1 to 4, characterised by a display unit (92) connected with the control electronics, which is designed for the numerical display of a current actual temperature and/or a desired fluid temperature of the fluid that is preselectable by a user, and displaying the temperatures in degree Celsius or degree Fahrenheit preferably in dependence of a parameter stored in a memory module (82), further, a manually operable unit being preferably provided for preselecting a desired temperature for the fluid, the display unit (92) being designed so as to display, for a predetermined period of time, the desired temperature as a reaction to the manual operation of the preselection unit and, thereupon, to change over and display the actual temperature.
6. Device according to one of the claims 1 to 5, characterised in that web-shaped portions (16; 58) of the support elements (10; 44), defining the flow channel, are provided with recesses (34; 60) for holding and guiding the at least one spiral heating coil, which recesses, succeeding one another along a circumferential direction of the support elements, are designed and dimensioned in such a way that the recesses formed in a plurality of adjacent support elements continuously follow a constantly ascending gradient of the heating coils.
7. Device according to claim 6, characterised in that the web-shaped portions of the support elements are designed for holding and guiding two heating coils (59, 61) which are arranged axially to each other, show spiral diameters of different sizes and preferably can be controlled separately by means of electrical operating voltage.
8. Process for operating an electrical heating device according to one of the claims 1 to 7, characterised in that the control of the at least one heating coil of the electrical heating device is effected with alternating current by switching the latter on or off with full half-periods and for full, switched half-waves in each case, a switching-on and off pattern being formed in such a way that within successive periods of time T = k x 3,000/f with k = integral natural number ≥ 2 and f = frequency of the alternating current, the established direct current component becomes zero.
9. Process according to claim 8, characterised in that within the same period of time T two heating coils are switched independently of each other, the cumulative established direct current component of the two heating coils becoming zero.
10. Process according to claim 9, characterised in that an internal and an external heating coil of two spiral heating coils are switched, which are aligned along a common axis, or in that a downstream as well as an upstream twin-coil are switched, which are arranged along a common axis.

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