EP3375251B1 - Method for producing an electrical heater - Google Patents

Description

The invention relates to a method for producing an electric heater, which has at least one heating element with at least one contact surface and at least one electrical resistance element which is arranged between the contact surface and a mating contact surface of a displaceable arranged to the heating element holding member, wherein the holding element with a contact pressure is pressed against the resistance element to hold it to the radiator.

State of the art

Methods for producing an electric heater are known from the prior art. In particular electrical resistance elements, such as PTC (Positive Temperature Coefficient, PTC) elements are installed in a radiator. PTC elements heat up when a supply of electrical energy. As the temperature of the PTC element increases, its electrical resistance increases and the electrical power consumption of the PTC element decreases as it approaches a maximum temperature and associated maximum electrical resistance. Because of this, the PTC element is used as a self-regulating heating element, which protects against overheating. The radiator is usually a metallic hollow body, which receives a part of the heat supplied from the PTC element and to an environment, such as air, transmits. For contacting and fastening of the PTC element to the radiator usually electrically conductive materials, in particular metal components, are used. It is known that these allow efficient heat transfer from the PTC element to the radiator. The PTC element is Usually arranged on a heat-absorbing contact surface of the radiator and pressed by a mating contact surface of at least one retaining element against the contact surface of the radiator. This results in not exactly flat contact surface and / or mating contact surface areas where no direct physical contact and thus no heat exchange takes place. If heat does not flow evenly from the PTC element to the radiator, the PTC element can reach a higher temperature in some areas, which reduces the electrical current and decreases the maximum power.

From the publication EP 2 346 304 A1 For example, a method of manufacturing an electric heater having a heater and an electrical resistance element is apparent. It is provided that a pressing force is exerted by the compression of a tongue and groove connection of a holding element in order to hold the resistance element to the radiator.

Disclosure of the invention

According to the invention, it is provided that the contact force is increased at least in some areas so far that the resistance element breaks into at least two fragments. The inventive method with the features of claim 1 has the advantage that by breaking or crushing the electrical resistance element, the surface of the electrical resistance element, which is in thermal contact with the radiator, is increased. This allows in particular a uniform heat transfer from the electrical resistance element to the radiator. Free spaces or gaps which lie between the electrical resistance element and the contact surface of the heating element are better filled by the breakage of the resistance element. By distributing the broken parts of the resistive element between the contact surface and the mating contact surface, a larger contact area of the electrical resistance elements with the contact surface is achieved. Thus, the electrical resistance element substantially has an improved temperature distribution. The electric Heating thus becomes more efficient by passing more electrical energy used to heat the resistive element to the radiator. In order to break the electrical resistance element, the otherwise disturbing, in particular production-related unevennesses on the contact surface and / or mating contact surface are utilized. This creates a break that is individually adapted to the radiator.

According to the invention, it is provided that the contact surface and / or the mating contact surface is provided or produced with at least one breaking projection. The advantage of this development is that this allows a targeted breaking, in particular simplified. In particular, the electrical resistance element is broken so that the distribution of the fractured parts is equal or nearly equal. The crushing projection can be arranged arbitrarily on the contact surface and / or the mating contact surface. Depending on the area which is to break preferentially under the contact force, a position of the breaking projection is selected. Optionally, a plurality of crushing projections on the contact surface and / or the mating contact surface can be attached. The breaking projection preferably has a sharp, in particular pointed edge, in order to maximize the contact pressure on the electrical resistance element at the predetermined breaking point. The crushing projection is preferably formed integrally on the contact surface or the mating contact surface. The crushing projection or a plurality of crushing projections can be attached, for example, by a milling in the contact surface and / or the mating contact surface. The crushing projections are preferably arranged web-shaped. This makes it possible, for example, to attach parallel crushing projections. Preferably, the respective breaking projection on the contact surface or the mating contact surface is formed by a projection projecting from the otherwise substantially flat contact surface or mating contact surface. Alternatively or additionally, crushing projections are preferably formed by one or more, in particular adjacent recesses in the contact surface and / or the mating contact surface, preferably introduced through a bore, milling and / or etching in the contact surface and / or counter-contact surface. This forms at the edges of the respective recess crushing protrusions out, between which lies the respective recess.

It is preferably provided that the contact force is only partially increased until the resistance element breaks. The advantage here is that it is purposefully controlled which regions of the contact surface and / or the mating contact surface are pressed against each other and thus which regions of the electrical resistance element are to be broken. The pressing force is generated, for example, by a device which acts on the contact surface and / or the mating contact surface and, for example, has contact pressure elements which are arranged along a bearing surface of the device on the contact surface and / or mating contact surface. Thus, both the thermal contact and the contact pressure for comminution of the electrical resistance element is generated. In order for the device to exert the contact force in certain regions, the contact pressure elements are designed in particular as individually controllable push rods which are arranged perpendicular to the contact surface and / or the mating contact surface.

Particularly preferably, it is provided that the contact force is increased in succession in different areas, so that the resistance element is broken in succession in these areas. As a result, the electrical resistance element is deliberately broken successively at different locations. The contact force acts, for example, simultaneously on two different areas of the contact surface and / or the mating contact surface. After breaking the electrical resistance element in these two areas, the contact pressure is increased at another point. This makes it possible for an already broken region of the electrical resistance element to be subjected again to a contact force and broken again.

According to a preferred embodiment of the invention it is provided that the contact surface and / or the mating contact surface are each formed by a contact element, which in particular has a higher elasticity than the heating element or the holding element. The advantage of this development is that thus the production of the contact surface and / or the mating contact surface is simplified because the contact element is manufactured as a separate part and to the contact surface and / or the mating contact surface is attached. In particular, material which has preferred properties, such as a certain material hardness or elastic deformability, is used sparingly. Due to the preferably increased elasticity, the contact surface and / or the mating contact surface adapts to the contour of the electrical resistance element when the contact surface moves in the direction of the mating contact surface. Thus, the contact contact surface of the electrical resistance element, which bears against the contact surfaces and / or mating contact surfaces, further increases, which in turn ensures improved heat transfer.

It is particularly preferably provided that the respective contact element is made of an electrically and / or thermally conductive material. The advantage here is that thus the transmission of electrical energy and / or heat energy is additionally improved and more efficient. The electrical energy is transmitted, for example, from the contact element to the electrical resistance element to operate it. For example, the contact element is made of metal or of electrically and / or thermally conductive plastic.

It is preferably provided that the respective contact element with a comb-shaped Anpressgeometrie, which forms the crushing projections, is formed. This has the advantage that parallel fault lines are generated. Preferably, the comb-shaped Anpressgeometrie exerts only partially a contact pressure on the electrical resistance element to ensure a targeted breaking. It is also advantageous that the electrical resistance element is first pressed into the latter by the preferably elastic deformability of the contact element and then, if a mechanical load on the electrical resistance element is too large, this is deliberately broken by the crushing projections. The contact contact surface of the electrical resistance element, which is in electrical and / or thermal operative connection with the contact element, is thus maximized.

Particularly preferably, it is provided that the contact pressure is generated by a clamping device and / or by an electromagnetic pulse transformation. This ensures in particular that the contact force is transmitted uniformly to the electrical resistance element. The clamping device can press, for example, with an adjustable, constant force on the holding element. If necessary, the pressing force is increased by the clamping device continuously or at least gradually to provide for breaking of the resistive element. After a successful break, the clamping device returns to a state where it presses with the adjustable contact pressure on the retaining element. Alternatively, the clamping device remains in the state in which it has generated the breakage of the electrical resistance element. Optionally, the clamping device is screwed to the radiator and / or retaining element. For example, by increasing the contact pressure of the clamping device with a tightening of the screw connection and decreasing it with a loosening of the screw connection, a targeted adjustment of the contact force is thereby made possible. The electromagnetic pulse transformation achieves individual deformation of the individual regions of the contact surface and / or the mating contact surface as well as of the electrical resistance element. For the electromagnetic pulse transformation, it is necessary that the contact surface and / or the mating contact surface and the electrical resistance element consist of an electrically conductive material. For example, in advance the electrical resistance element and the contact element can be pressed against each other without contact. For this purpose, in particular an electrical coil is needed and a powerful, pulsed magnetic field needed. The contact pressure can then be carried out without mechanical contact between the electrical resistance element and the contact element. The magnetic field acts in the electromagnetic pulse transformation unhindered by the material of the heater and / or the holding element. Thus, it becomes possible to obtain the largest possible surface area of the electrical resistance element that is pressed against the contact surface and / or the mating contact surface.

According to a preferred development of the invention, it is provided that a PTC element is used as the resistance element. The advantages of the PTC element have already been explained above.

The electric heater according to the invention with at least one radiator having the features of claim 9 is characterized in that the resistance element is broken in at least two fragments by an increased contact pressure. This results in the already mentioned advantages. Further advantages and preferred features will become apparent from the foregoing and from the claims.

In addition, the electric heater according to the invention is characterized in that the contact surface and / or the mating contact surface each have at least one breaking projection. This results in the already mentioned advantages. Further advantages and preferred features will become apparent from the foregoing and from the claims.

Figur 1

eine vereinfachte Schnittdarstellung einer elektrischen Heizung gemäß eines Ausführungsbeispiels,

Figur 2

die elektrische Heizung in einer vereinfachten Draufsicht,

Figur 3

die elektrische Heizung gemäß einem weiteren vorteilhaften Ausführungsbeispiel in einer vereinfachten Schnittdarstellung und

Figur 4

das vorteilhafte Ausführungsbeispiel in einer vereinfachten Draufsicht.

In the following, the invention will be explained in more detail with reference to the drawing. Show this

FIG. 1

2 is a simplified sectional view of an electric heater according to an exemplary embodiment,

FIG. 2

the electric heater in a simplified plan view,

FIG. 3

the electric heater according to a further advantageous embodiment in a simplified sectional view and

FIG. 4

the advantageous embodiment in a simplified plan view.

FIG. 1 shows in a simplified representation of an electric heater 1, which has a radiator 2 with a contact surface 3, a holding element 4 with a mating contact surface 5 and a dashed electrical resistance element 6, in particular a PTC element. The PTC element 6 is arranged to transfer heat in particular to the contact surface of the radiator 2 between the contact surface 3 and the mating contact surface 5. The PTC element 6 is preferably designed as a plate or plate element, wherein a plate plane extends at least substantially parallel to the contact surface 3 and the mating contact surface 5.

To operate the PTC element 6, this is supplied, for example by an electrically conductive contact with the contact surface 3 with electrical energy. With a supply of electrical energy, the PTC element 6 heats up. As the temperature of the PTC element 6 rises, its electrical resistance increases. As soon as the PTC element 6 of a maximum Temperature and thus approaches a maximum resistance, its electrical power consumption decreases.

On the outer side 28 of the heating element 2 and the outer side 29 of the holding element 4, a contact pressure, which presses the contact surface 3 and the mating contact surface 5 against each other and in FIG. 1 is shown with an arrow. The contact surface 3 and / or the mating contact surface 5 have a plurality of irregularities which form crushing projections 7.

To generate the contact force, for example, a device not shown here is used, which is arranged along the outer sides 28 and 29 in particular in the form of a clamping device and along the outer sides 28 and 29 individually controllable pressing elements. By the contact force generated thereby, the PTC element 6 is securely held on the radiator 2.

By pressing the pressing force is applied uniformly to the PTC element 6 according to a first embodiment. The contact force is increased or reduced until the PTC element 6 breaks at at least one point. In the present case, the PTC element 6 is comminuted into four fragments 8, 9, 10, 11.

Optionally, it is provided that the contact force is only partially increased, for example, by only one of the pressing elements is actuated. By increasing the contact force, for example, only to the area 37, essentially only the fragments 8, 9 are generated, while the rest of the PTC element 6 is present unbroken. Subsequently, it is preferably provided that the contact pressure in the region 38 is increased beyond the holding force, so that in this case the fragments 10 and 11 are generated. Thus, in this case, the PTC element 6 is broken successively in different sections, which may result in advantageous fracture patterns.

In particular, it is provided that the contact force is increased simultaneously on at least two different areas of the contact surface 3 and the mating contact surface 5. This is purposefully controlled, which areas of the contact surface. 3 and / or the mating contact surface 5 are to be pressed onto each other and thus, which areas of the PTC element 6 to be broken.

It is advantageous that thus the surface of the PTC element 6, which is in thermal contact with the contact surface 3 of the heating element 2, ie the contact contact surface, is increased. As a result, in particular, the heat transfer from the PTC element 6 to the radiator 2 is improved. This thus increases the efficiency of the electric heater 1 because the electric energy used for heating the PTC element 6 is transferred to the radiator 2 more efficiently.

FIG. 2 shows the electric heater 1 in a simplified plan view. The FIG. 2 has the radiator 2 and the holding element 4. Between these, shown in dashed lines, the PTC element 6 is arranged. The PTC element 6 has broken edges 13, 14, 15 at the points where it was broken. These are present wavy and uneven. The breaking edges 13, 14, 15 are substantially as predefined by the crushing projections 7.

FIG. 3 shows the electric heater 1 according to a further advantageous embodiment in a simplified plan view. The contact surface 3 of the heating element 2 in this case has rupture projections 7 in the form of a comb-shaped Anpressgeometrie 16. The break projections 7 are presently designed so that they are incorporated, for example, as by a milling parallel webs or combing teeth 17 in the mating contact surface 2.

The advantage here is that, in contrast to the embodiment in FIG. 2 the crushing projections 7 are selectively mounted, for example, to obtain an equal or nearly equal distribution of the fractured part of the PTC element 6. In the present case, virtually parallel break edges 18, 19, 20, 21 are produced in the PTC element 6.

The crushing projections 7 preferably have sharp, in particular tapered, contact edges in order to maximize the contact pressure on the PTC element 6 at the point at which the fracture takes place.

FIG. 4 shows the advantageous embodiment in a simplified sectional view, wherein the PTC element 6 is present between the radiator 2 and the holding element 4 in a broken by the applied contact force state.

The contact surface 2 in this case has rupture projections 7 in the form of the comb-shaped Anpressgeometrie 16. The comb-shaped Anpressgeometrie 16 is formed in the form of a contact element 22 which is preferably attached to the contact surface 3 cohesively, for example by welding or by a coating process.

The contact element 22 is preferably made of an electrically and / or thermally conductive n, in particular soft-n material, in order to additionally improve the transmission of electrical and / or thermal energy. In addition, the contact element 22 preferably has a higher elasticity than the radiator 2. For this purpose, the contact element 22 is made for example of aluminum or a conductive plastic.

Due to the higher elasticity of the contact element 22, when the contact surface 3 is pressed against the mating contact surface 5, both the PTC element 6 is broken and the individual fragments 31 to 34 of the PTC element 6 are inserted into the comb teeth 17, so that the comb teeth 17 deform and adapt to the contour of the fragments 31 to 34. Thus, in particular, the area of the PTC element 6 in thermal contact with the radiator 2 is increased, thereby improving the heat transfer efficiency.

According to an exemplary embodiment not shown here, crushing projections 7 are additionally or alternatively formed by the side edges of one or more adjacent recesses in the contact surface 3 and / or the mating contact surface 5 delimiting a respective recess. The PTC element 6 then rests on the side or outer edges of the respective depression in such a way that it bridges the recesses. Once a force on the overlying PTC element 6, for example in the region of the depression the contact surfaces 3 by the mating contact surface 3, which in particular there has at least one breaking projection 7, is applied, it breaks in particular in the middle.

Claims (9)

1. Method for producing an electrical heater (1) which has at least one heating body (2) with at least one contact surface (3) and has at least one electrical resistance element (6) which is arranged between the contact surface (3) and a mating contact surface (5) of a holding element (4) which is arranged such that it can move in relation to the heating body (2), wherein the holding element (4) is pressed against the resistance element (6) with a contact-pressure force in order to hold the said resistance element on the heating body (2), characterized in that the contact surface (3) and/or the mating contact surface (5) is provided or produced with at least one breaking projection (7), and in that the contact-pressure force is increased, at least in regions, to such an extent that the resistance element (6) breaks into at least two pieces (8 to 11, 31 to 34).
2. Method according to one of the preceding claims, characterized in that the contact-pressure force is increased, only in regions, until the resistance element (6) breaks.
3. Method according to either of the preceding claims, characterized in that the contact-pressure force is increased in different regions in succession, so that the resistance element (6) is broken in these regions in succession.
4. Method according to one of the preceding claims, characterized in that the contact surface (3) and/or the mating contact surface (5) are formed by in each case one contact element (22) which has, in particular, a higher elasticity than the heating body (2) or the holding element (4).
5. Method according to Claim 4, characterized in that the respective contact element (2) is produced from an electrically and/or thermally conductive material.
6. Method according to Claim 4, characterized in that the respective contact element (22) is designed with a comb-like contact-pressure geometry (16) which forms the breaking projections (7).
7. Method according to one of the preceding claims, characterized in that the contact-pressure force is generated by a clamping device (23) and/or by electromagnetic pulse deformation.
8. Method according to one of the preceding claims, characterized in that a PTC element is used as the resistance element (6).
9. Electrical heater having at least one heating body (2) which has at least one contact surface (3), having at least one electrical resistance element (6) and having at least one holding element (4) which has a mating contact surface (5) and is arranged such that it can move in relation to the heating body (2), wherein the resistance element (6) is held between the contact surface (3) and the mating contact surface (5), wherein the holding element (4) is pressed against the resistance element (6) by a contact-pressure force in order to hold the said resistance element on the heating body (2), characterized in that the contact surface (3) and/or the mating contact surface (5) each have at least one breaking projection (7), and in that the resistance element (6) is broken into at least two pieces (8 to 11, 31 to 34) due to an increased contact-pressure force.

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