EP1523224A1 - Electrical heating cartridge - Google Patents

Abstract

An electric heating cartridge (1), especially for heating liquids and/or gaseous media, comprises at least one positive temperature coefficient element (10), two electrodes (9), and an insulating element (8) that electrically insulates a housing (2). The insulating element consists of a polyimide film. The cartridge has at least two heat conducting members.

Description

The invention relates to an electric heating cartridge, in particular for heating of liquid and / or gaseous media, with at least one PTC element, the two At least one PTC element associated electrode bodies, which in a relative to the electrode bodies by at least one insulating electrically isolated housing body received under a bias compressed are.

Cartridges of this type are characterized by their small construction and thus, that they are both heating and temperature control at the same time. These Dual function is achieved through the use of PTC elements (Positive-Temperature-Coefficient), so-called PTC thermistors, achieved. A PTC element has the property only to heat up to a predetermined limit temperature. From this limit temperature The electrical resistance increases suddenly, so that the PTC element is not continues to heat. PTC elements are therefore self-regulating and require no additional Temperature control. It is possible to use PTC elements for different electrical To produce voltages and different limit temperatures. By a structurally simple design, which is essentially the actual PTC element and includes two electrode body, and a simple power supply via a zweiadriges cable is the relatively small design of the heating cartridges to realize.

Due to the properties described have heating cartridges of the type mentioned various applications, such as in the industry, medical technology or else in the household. They are used, for example, in laminators, inhalers and in used in automotive engineering.

A heating cartridge of the prior art, for example, in DE 202 12 580th U1 described. In the heating cartridge DE 202 12 580 U1, the power supply takes place over the housing body of the heating cartridge. For this reason, the Heating cartridge not for use in electrically conductive or electrically dissociating Media.

Another heating cartridge is described in DE 197 37 241 C2. Here are two PTC elements with two electrode bodies, which together in several insulating elements are embedded, received biased in a housing body made of metal. The Insulating elements are in this case made of an elastic metal oxide, which is pre-pressed are and bias the components within the housing body.

A disadvantage of the immersion heater of DE 197 37 241 C2 is that the metal oxide itself temperature-dependent expands, so that different depending on the temperature Preload forces are generated. As a result, the heated by the heating cartridge to the to be heated medium emitted heat energy at different Temperatures.

The invention is therefore an object of the invention to provide a heating cartridge, wherein the at the medium to be heated heat energy also at Temperature variations is substantially constant.

This object is achieved according to the invention for the aforementioned heating cartridge solved that the housing body as a biasing spring element is designed.

This solution is structurally simple and such a running heating cartridge can be produced inexpensively.

By applied by the housing body bias the Components compressed within the housing body. This is ensure that the heat conduction surfaces of the housing body and the inner Components abut each other and thereby deliver a previously calculated Heat energy can be transferred to the medium to be heated. Because of that Contrary to the prior art now the housing body serves as a spring element, can be generated over wide temperature ranges, a uniform biasing force. Surprisingly, the temperature dependence of the housing body seems produced biasing force to be less pronounced than in the embodiment of Insulator as spring elements. One reason could be the low wall thickness lie the housing body. This ensures a secure concern of Wärmeleitflächen of the components to each other.

The thus improved heating device may be different from each other independent and each for themselves advantageous developments to be further developed as explained below.

Thus, in an advantageous embodiment of the housing body made of an elastic Material be designed. This has the advantage that the housing body elastic is deformable and thereby generates the bias in the interior of the housing body can be.

To give the housing body a particularly advantageous form, the Housing body be made substantially cup-shaped. This requires the Heating cartridge according to the invention are closed only on one side, resulting in reduce the cost of mounting the heating cartridge and the number of items. The substantially cup-shaped housing body may also consist of a be made thin-walled material, e.g. by deep drawing. This will be the one the housing body elastic and on the other he can thereby generated Better conduct heat energy to the outside. The shape of the pot-shaped housing body is not limited and may e.g. cylindrical, but also four-, six- or octagonal be executed.

To increase the life of the heating cartridge according to the invention and their possible area of use to increase, the housing body in an advantageous Training of a corrosion resistant material, e.g. a metal, made his. To also use the heating cartridge for aggressive liquid media can, the housing body also also made of an acid-resistant material be made.

Furthermore, the at least one insulating element in an advantageous embodiment a relative to the housing body inelastic plastic film, in particular from a polyimide film to be made. This material is especially good because it has a offers good electrical insulation and on the other hand is particularly thermally conductive. The Polyimide film may be, for example, a Kapton film. By doing that Insulating element is executed inelastic with respect to the housing body, the Preload passed well on the electrode body and the PTC element. The Design as a thin-walled film enhances the inelasticity of the Insulating element, so that the spring force almost exclusively from the housing body can be generated.

In a further advantageous embodiment, the electrode body can each one Have contact element through which the electrode body to a voltage source can be connected. The contact elements can be used as a welding contact or as a plug can be made to provide a good connectivity. The Electrode bodies are also usually made of a thermally conductive material, in particular a metal.

In an advantageous development, the heating cartridge according to the invention can at least have two heat conductive pressure body, which has a spring force of the Housing body in the direction of at least one PTC element transmitting are formed. This has the advantage that the pressure bodies from a cost-effective, easy to manufacture thermally conductive material, e.g. extruded aluminum, can be made and so fill the housing body, transfer heat and the Guide the spring force inwards. The cost-effective components, such as PTC element, Electrode body and insulating can thereby smaller and thereby be material-saving, which leads to the reduction of material costs. The Pressure bodies can in particular between the housing body and the PTC element be arranged. You can also sandwich the PTC element. Furthermore, the pressure bodies can be designed as electrode body. You can in a development also be surrounded by the insulating.

Furthermore, the width of a stack of the pressure bodies, the at least one Insulating element, the electrode bodies and the at least one PTC element in one advantageous development be greater than the clear width of the housing body. As a result, during insertion of the stack in the housing body during the Assembly of the heating cartridge of the housing body elastically expanded. Through this Elastic widening will provide the desired preload inside the heating cartridge generated. Due to the size of the excess of the width of the stack and the clear Width of the housing body, the size of the bias voltage can be predetermined. Around ensure that the preload force is substantially or almost exclusively is generated by the housing body is, taking into account the respective thicknesses, the Elasticity of the pressure body smaller dimensioned than that of the housing body. Due to the higher elasticity, the pressure hull under the action of the biasing force therefore remain in the Essentially undeformed.

In a further advantageous embodiment, the heating cartridge can be at least one Have closure element through which the housing body substantially fluid-tight is closed. As a result, an insert of the heating cartridge according to the invention in liquid or gaseous media possible. The interior of the housing body of the heating cartridge according to the invention is thus also protected against contamination, which makes it possible to use it even in very dirty environments.

In addition, the closure element in a further advantageous embodiment be made of a permanently elastic material, in particular an elastomer. This is advantageous because permanently elastic material is resistant to aging and also at Temperature fluctuations neither break nor become porous. For use in corrosive, alkaline and / or acidic fluids, the closure element accordingly be designed corrosion and / or acid resistant.

In a further advantageous embodiment, the housing body with a Locking means be configured, in which the closure element with a corresponding Counter-latch engages positively. As a result, the closure element is simple Way fixed in the housing body. Furthermore, by the outside use the locking means of the housing body e.g. in a tubular receiving device be attached. By the locking means of the housing body and thus the Heating cartridge held by friction or positive engagement in the receiving device.

To prevent the components inside the case body from moving secure, the closure element can in an advantageous development with a Be holding means designed which is formed axially securing the pressure body.

In a further advantageous embodiment, the heating cartridge can be at least one Connection element, through which the electrode body with a voltage source are connectable. This creates an easy way, the Supply heating element according to the invention with electricity. Furthermore, the at least a connecting element also be designed as a fastening element and the Keep the heating cartridge in the medium to be heated. This allows the heating cartridge e.g. when heating a liquid medium directly and without receiving device in be attached to this, held by the connection element.

In a further advantageous embodiment, the closure element at least have a sealed opening, through each of which a connection element extends. This has the advantage that the PTC element can be supplied with power, without the inventive heating cartridge is leaking. Alternatively, the Closing element may be formed as a part of a plug-in, in the For example, a plug element for powering the heating cartridge can be inserted. Advantageously, the plug-in connection for use of the immersion heater in liquids executed fluid-tight.

In the following, the invention will be described by way of example with reference to the accompanying drawings explained. The different features can be independent of each other be combined, as above in the individual advantageous embodiments has already been explained.

Fig. 1

eine Ausführungsform der erfindungsgemäßen elektrischen Heizpatrone in einer schematischen Perspektivansicht;

Fig. 2

die Ausführungsform der elektrischen Heizpatrone aus Fig. 1 im Vollschnitt;

Fig. 3

die Ausführungsform der elektrischen Heizvorrichtung aus Fig. 1 in einer Explosionsdarstellung.

Show it:

Fig. 1

an embodiment of the electric heating element according to the invention in a schematic perspective view;

Fig. 2

the embodiment of the electric heating cartridge of Figure 1 in full section.

Fig. 3

the embodiment of the electric heater of FIG. 1 in an exploded view.

1 shows an embodiment of the electric heating cartridge 1 according to the invention with a housing body 2 and two connection elements 3. The housing body 2 is in Fig. 1 by way of example pot-shaped, whereby the heating element 1 at the bottom of the 4 Housing body 2 is automatically closed. The housing body 2 is cylindrical and thus z. B. in a tubular receiving device in a plug E insertable. The heating cartridge 1 can be up to a flange-shaped stop 5 are inserted into the receiving device. Below the stop 5 is located on the housing body 2, a locking means 6 in the form of a hollow bead. By the Locking means 6, the heating cartridge 1 is fixed in the receiving device. The fixation can be achieved in that the outer diameter of the locking means 6 is greater as the inner diameter of the receiving device, whereby the heating cartridge 1 is frictionally fixed in the receiving device. But it is also conceivable that the Receiving device has a recess into which the locking means 6 positively snaps into place and thus fixes the heating cartridge 1. The locking means 6 is shown in Fig. 1 by way of example the entire circumference of the housing body 2 shown circumferentially. But it is also possible that the locking means 6, for example, only partially on the Scope of the housing body 2 is executed.

The two connection elements 3, e.g. in the form of a plug-in, exit at the top the housing body 2 for connecting the heating element 1 to a voltage source (not shown) out. By connecting elements 3 is also a Another possibility for mounting the heating element according to the invention 1. This is the Connection elements 3 made of a flexible material bendable. The Connection elements 3 serve in this embodiment as fastening elements and the Heating cartridge 1, hanging on the connecting elements 3, directly in the zu placed in a heated medium. By manually bending the connection elements 3, the position of the heating cartridge 1 can be varied.

So that the heating cartridge 1 can also be used for heating aggressive media, is the housing body 2 made of a corrosion and acid resistant material, e.g. one Metal, made.

Fig. 2 shows an example of the embodiment of the heating cartridge 1 according to the invention Fig. 1 in full section 1, whereby the components in the interior of the housing body 2 in built-in state become visible. In this case, the inventive Heating cartridge 1 inside the housing body 2 a stack of two pressure bodies 7, an insulating member 8, two electrode bodies 9 and a PTC element 10. Das im Essentially designed as a thin, preferably rectangular plate shaped PTC element 10 performed with the largest possible plate surface to the greatest possible Form heat conduction surface. The PTC element 10 is in one position within the housing body 2, in which it can take the greatest possible length. This position is, for example, in a housing body with a circular cross section Diameter and in a body with polygonal cross-section a diagonal.

At the two plate surfaces of the PTC element 10 are two electrode bodies 9 at. The two electrode bodies 9 are substantially as thin, preferably rectangular plates are formed and have at least the same plate surface as that PTC element 10 so that they PTC element 10 on the entire plate surface with Supply electricity and dissipate the generated heat well. The electrode body 9 are each via a connection element 3 with a voltage source (not shown) connected. In Fig. 2, only one of two connection elements 3 is shown, since the other connection element 3, the second electrode body with the voltage source connects, not shown in the heating cartridge 1 is located. The connection elements 3 and the electrode body 9 may be configured in one piece.

To the electrode body 9 together with the PTC element 10 around that is compared to the housing body 2 inelastic, film-shaped insulating 8. The insulating element. 8 Insulates the electrode body 9 and the PTC element 10 electrically opposite to the But to a good heat conduction from the PTC element 10 or the electrode bodies 9 to ensure the pressure bodies 7 is the insulating member 8 made of a thermally conductive material. In the exemplary embodiment in FIG. 2, the insulating element 8 is made of a polyimide film, in particular from a Kapton film.

The PTC element 10, the electrode body 9 and the insulating body 8 are between the sandwiched two semicircular pressure bodies 7. The pressure body 7 are for good heat transfer from a thermally conductive material, e.g. out Aluminum, manufactured and are completely on the electrode bodies 9 and on the Insulating element 8 at. The stack 7, 8, 9, 10 is located inside the housing body 2 and is under a bias, since the width of the stack is greater than the clear Width of the housing body 2, whereby the wall of the housing body 2 elastic is deflected outwards and thereby the bias in the interior of the Housing body 2 is created. The bias presses the two pressure body 7 in one Direction of action F together. The pressure bodies 7 in turn push the insulating element 8, the electrode body 9 and the PTC element 10 centered together. By the Compression by the bias in the interior of the housing body 2 is For example, air gaps that may be through Manufacturing tolerances of the individual components or by different Thermal expansions arise, be reliably pushed away, creating a good Heat conduction is ensured within the heating cartridge 1 according to the invention.

As shown in Fig. 2, the housing body 2 at the upper end of a Closing element 11 is closed. The closure element 11 seals the Housing body 2 fluid-tight, so that e.g. a fluid to be heated not in the interior the heating cartridge 1 can get. The closure element 11 has a widening, in the installed state positively in the locking means 6 of the housing body. 2 engages and fixes the closure element 11. Furthermore, the closure element has 11 a stop flange 12, which in the installed state to the stop 5 of Housing body 2 applies. To further improve the sealing effect, that is Closure element 11 made of a permanently elastic plastic, namely an elastomer, manufactured. The elastomer also offers the advantage that the closure element Temperature fluctuations compared to dimensionally stable, does not age and therefore not is leaking. The elastomer can also be cast directly into the housing body 2 and harden therein, whereby an optimal positive engagement with the inner surface of the Housing body 2 is reached. The closure element 11 has two sealed Openings through which the connection elements 3 lead. Alternatively, the Closing element 11 form a part of a fluid-tight connector in itself, in the one counterpart of the connector for powering the heating element is pluggable. The connecting elements 3 are also by the Closing element 11 sealed. The closure element 11 may be suitable for use in corrosive media be made of a corrosion resistant material.

In order to prevent slippage of the pressure body 7 in the interior of the housing body 2, is on the closure member 11, a holding means 13 executed. In the installed state limits the holding means 13, the pressure body 7. The pressure body 7 are thus in their axial position on one side by a shoulder at the end of the housing body. 2 and fixed on the other side by the holding means 13 of the closure element 11.

At the bottom 4 of the housing body 2 is located between the housing body 2 and the Pressure bodies 7 an air-filled space, which forms an insulating layer and a Heat emission down, for example, when heating a solid, reduced.

Fig. 3 shows the electric heating element 1 of the invention according to FIGS. 1 and 2 in one Exploded view. The electric heating cartridge 1 comprises the housing body 2, in the two semi-circular pressure body 7 are added. Between the two Pressure bodies 7 is the PTC element 10, which on each side of a Electrode body 9 is surrounded, and both are enclosed by the insulating element 8. In Fig. 3 it can be seen that the insulating element 8 in this exemplary illustration pocket-shaped around the PTC element 10 and the electrode body 9 around is. This ensures electrical insulation of the electrode body 9 and the PTC element 10 on five sides. PTC element 10 and the electrode body 9 are in the Insertion direction E inserted into the pocket-shaped insulator 8. The Electrode bodies 9 each comprise a contact element 14, on which the Connection element 3 is attached. The connection is usually done by soldering or welding, but also a pluggable connection is conceivable.

As shown in Fig. 3, the heating cartridge 1 by the closure member 11 after completed at the top. The individual components are used in the assembly of the Heating cartridge 1 introduced in the insertion direction E in the housing body 2.

In another embodiment of the heating cartridge 1 according to the invention, it is possible a tubular, open on both sides housing body to be used on both Side has a closure element. Here, in each case a connection element 3 from both sides of the housing body through the openings of the closure elements eleventh stepping out. This embodiment may be advantageous to the inventive Heating cartridge, for example, in a fluid flow from two sides through the two Hang connecting elements 3 and without receiving device.

In another modification, the insulating element 8 between the pressure bodies 7 and arranged the housing body 2, wherein the pressure bodies do not touch and as Electrode body can be configured. Finally, instead of two pressure hulls also a single pressure body or a plurality of pressure bodies used become.

Claims (16)

Electric immersion heater (1), in particular for heating liquid and / or gaseous media, with at least one PTC element (10), two electrode bodies (9) assigned to the at least one PTC element (10), which are arranged opposite one another in relation to the electrode bodies ( 9) by at least one insulating element (8) electrically insulated housing body (2) are received compressed under a bias voltage, characterized in that the housing body (2) is designed as a bias voltage generating spring element. Electric immersion heater (1) according to claim 1, characterized in that the housing body (2) is made of an elastic material. Electric immersion heater (1) according to claim 1 or 2, characterized in that the housing body (2) is made substantially pot-shaped. Electric heating element (1) according to one of the above claims, characterized in that the housing body (2) is made of a corrosion-resistant material. Electric immersion heater (1) according to one of the above claims, characterized in that the at least one insulating element (8) is made of a plastic film inelastic with respect to the housing body, in particular of a polyimide film. Electric immersion heater (1) according to one of the above claims, characterized in that the electrode bodies (9) each have a contact element (14) through which the electrode bodies (9) can be connected to a voltage source. Electric immersion heater (1) according to one of the preceding claims, characterized in that the immersion heater (1) has at least two heat-conducting pressure bodies (7) which bias the housing body (2) in the direction of the at least one PTC element (10). are formed transmissively. Electric immersion heater (1) according to claim 7, characterized in that the width of a stack of the pressure bodies (7), the at least one insulating element (8), the electrode bodies (9) and the at least one PTC element (10) is greater than the clear width of the housing body (2). Electric immersion heater (1) according to claim 7 or 8, characterized in that the at least two pressure bodies (7) are made of aluminum. Electric immersion heater (1) according to one of the above claims, characterized in that the heating element (1) has at least one closure element (11), by which the housing body (2) is substantially fluid-tightly sealed. Electric immersion heater (1) according to claim 10, characterized in that the housing body (2) with a latching means (6) is designed, in which the closure element (11) engages positively with a mating catch. Electric heating element (1) according to claim 10 or 11, characterized in that the closure element (11) is made of a permanently elastic material, in particular an elastomer. Electric immersion heater (1) according to any one of claims 10 to 12, characterized in that the closure element (11) with a holding means (13) is designed, which is formed axially securing the pressure body (7). Electric heating cartridge (1) according to one of the above claims, characterized in that the heating cartridge (1) comprises at least one connecting element (3), which is designed as a fastening element, by which the heating cartridge (1) can be attached in the medium to be heated , Electric heating device (1) according to claim 10, characterized in that the closure element (11) has at least one sealed opening, through each of which a connection element (3) extends. Electric heating device (1) according to one of the above claims, characterized in that the pressure bodies (7) are made less resilient with respect to the biasing force than the housing body (2).

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