EP1353131B1 - Electric heater, especially for a vehicle - Google Patents

Description

The invention relates to an electric heater, which is particularly suitable for use in a motor vehicle. Although the invention will be described below with a view to use on a motor vehicle, it should be noted that the electric heating device according to the invention can also be used for heating processes on other devices.

Electric heaters are now widely used, for example in motor vehicles and air conditioning systems and the like, for. B. in the case of a motor vehicle to heat the vehicle interior.

Usually, the heating of the vehicle interior takes place essentially via the waste heat of the internal combustion engine, which is delivered to the cooling circuit. From there, part of the waste heat can be released via a heat exchanger to the air flowing into the vehicle interior.

However, the exhaust heat of the engine is fully available only when the engine has reached its operating temperature, so that the heating of the vehicle interior on exhaust heat of the engine, especially at the beginning of rides, can be perceived as insufficient.

The problem is compounded by the fact that with the development of more economical engines less waste heat is generated, which is available for heating the vehicle interior.

Therefore, it has become known in the art to provide additional heaters, which are used in the air duct and release heat to the air flowing into the vehicle interior. By such additional heaters z. B. in the cold season or z. B. directly after the start of the motor vehicle when (still) cold engine users in a considerably shorter time a pleasant room temperature can be provided.

So z. B. from the EP 0 901 311 A2 an electric heater according to the preamble of claim 1, in which a heating block is provided with a plurality of heating elements. A control device is designed as a plug-in module and can be plugged into the heating elements.

Such connectors have the disadvantage that the contact between the control device and heating elements can be partially or even completely resolved by vibration or the like over time.

Starting from the cited prior art, therefore, the object of the present invention to provide a heating device is available, in which the electrical contact is ensured in the long term substantially.

The electric heater according to the invention is the subject of claim 1. Preferred developments are the subject of the dependent claims.

The electric heating device according to the invention comprises at least one heating device and at least one power device. The power device is in electrical contact with the at least one first and at least one second contact means of a contact device Heating device. The contact device is designed such that a firm connection of the first and the second contact means can be produced.

A fixed connection between the first and the second contact means of the contact device ensures a permanent electrical contact of power device and heater. Such a strong bond provides significantly improved contact and aging resistance and resistance to vibration release.

It is z. B. the first contact means permanently electrically connected to a power device and z. B. the second contact means permanently with a heater. A fixed connection of the first and the second contact means then ensures an electrical connection between the power device and the heater.

Due to the improved contacting between the contact means of the contact device, an improvement of the contact resistance between the first and the second contact means of the contact device is also achieved. The lower electrical contact resistance also reduces the power loss at the contact device. This results in a lower contact temperature.

Due to the lower losses, this leads to an increased efficiency of the overall process. Furthermore, the improved contacting causes increased reliability.

The electric heater according to the invention can further increase the life of an electric heater, since corrosion-related aging of the contact device are largely avoided, because by the solid compound of Contact means, the contact surfaces of the contact means are protected against environmental influences such as dust and moisture substantially effective.

In addition, the connection of the contact device is form-fitting and rigid.

A form-fit producible connection of the first and second contact means of the contact device is very advantageous because positive connections are resistant to aging and generally less easily solved by vibration and the like, as such frictional connections, as are known in the art.

The use of a rigid connection is also advantageous.

In a preferred development of the invention, the connection to the contact device of the first and the second contact means is designed to be detachable. A releasably designed connection of the contact device is advantageous because it allows an exchange of individual heaters or power devices, without it being necessary to replace the entire electric heater in case of failure of a heater or power device.

Furthermore, the connection of the first and the second contact means can be produced via at least one fastening device which is taken from a group of fastening devices which comprises screw devices, riveting devices and lever clamping devices.

Preferably, at least one fastening device or essentially all fastening devices is designed as a screw device. Screw devices have many advantages. Screw devices can be removed and refastened almost as often as desired, without the strength of the screw connection deteriorating. Furthermore, screw devices have the advantage that the strength of the connection via the screw torque is adjustable, so that precisely defined connection forces can be produced.

In comparison, in the connectors known in the prior art, the connection forces are dependent on the number of connections made, since in general the mated parts can loosen over time. Screw connections are not subject to such aging phenomena.

Riveting devices are also very advantageous because they also allow a firm and reliable connection of the two contact means of the contact device. A riveting can z. B. be separated again by drilling. Then, by using a new riveting the connection can be restored in a consistent quality. As with a screw device, the connection force of a riveting device is adjustable. This can be z. B. by the choice of the length of the riveting done (and also the diameter, etc.).

It is also possible that a lever clamping device or the like is used for fixed connection of the first and the second contact means. With a lever clamping device in the context of this invention is in this case a clamping device to understand that exerts an increased clamping force by using a lever or the like. Preferably, such a lever clamping device is designed such that an eccentric or the like is provided, so that a reliable safeguard against unintentional release by vibrations or the like is ensured.

With such lever clamping devices can be applied reliably and reproducibly a certain clamping force. By adjusting, for example, the lever or the distances of the parts to be clamped, the clamping force can be accurately adjusted so that on the one hand ensures that the clamping force is high enough and on the other hand ensures that damage to the clamped parts is omitted.

Such clamping devices are very advantageous. In contrast to the connectors known in the prior art, a precisely defined force is applied to the parts to be clamped in a lever clamping device after bringing together the parts to be clamped, so that the contact means of the contact device are firmly and reproducibly firmly connected.

In a preferred development of the invention, at least one heating device is provided, which is taken from a group of heating devices which comprises resistance heating devices and PTC heating devices.

Positive temperature coefficient (PTC) ceramic heating elements are preferred since they have a quasi-built-in fuse due to their positive temperature characteristic.

Therefore, it is preferable that at least one resistance heater is at least one PTC heater. Most preferred are substantially all Heating devices designed as a PTC heater, as z. B. in the EP 0 901 311 A2 are described.

It is also preferred that in addition to PTC heaters also or only resistance heaters are provided.

In a preferred embodiment of the invention, the materials for the contact means are selected such that galvanic corrosion is substantially completely or at least largely avoided.

The contact surfaces of the first and of the second contact means are adapted to one another in all the embodiments described above in such a way that a relatively large contact surface of the two contact means is made possible. In this case, the contact surfaces may be convex, concave, flat or otherwise shaped, as long as it is ensured that the two contact means abut each other over a substantial part of their surface, if there is a firm connection of the contact device.

Such surface and shape matching is very advantageous because it increases the cross-sectional area of the electrical current. As a result, the area-related current density is reduced, which also leads to a reduction of the contact resistance at the contact device. This in turn results in a lower contact device temperature, and a smaller power loss at the contact device, or it can be reduced at a constant current density, the number of connection points, which increases the reliability.

In a preferred embodiment of the invention, the contact means of the contact device are designed such that an automatic connection of the two contact means can be produced. For example, the contact means may be shaped such that in a fastening device provided as a screw device (or also riveting device) Holes for the screw means are arranged behind the contact means so that the contact means and the contact means are arranged in total of their outer shape so that an insertion of a screw in the holes of the contact means easily possible.

This is advantageous because it allows a simpler automatic connection of the contact means and the contact device. If complicated and multi-layered movements and handles are necessary, an automatic connection of the contact means is made more difficult, which ultimately leads to higher production costs.

In a preferred development of the invention, a plurality of heating devices and / or power devices is provided, wherein a contact device can be provided for each heating device.

Preferably, a corrugated fin device or the like is provided on at least one heating device in order to improve the heat transfer to the heating medium.

Preferably, the electric heater is provided for operation with a gas as the heating medium and more preferably for air as the heating medium. However, it is also possible that the heating device according to the invention is operated with a liquid as a heating medium to which the heating power of the heater is delivered.

Preferably, at least one power device comprises a control device which controls the heat output of at least one heating device. Particularly preferably, a control device is provided for substantially every power device.

It is possible that, for example, a heating system consisting of several heating devices is controlled simultaneously and / or that each individual heating device is controlled separately. A separate control of each heater increases the control options of the heater and allows a more accurate adjustment to predetermined conditions.

Further advantages and possible applications of the present invention will now be described with reference to embodiments with reference to the figures.

Fig. 1

eine erfindungsgemäße elektrische Heizvorrichtung in einer ersten Ausführungsform in einer perspektivischen Ansicht vor Herstellung einer festen Verbindung;

Fig. 2

ein Paar Kontaktstellen in einer vergrößerten Darstellung gemäß dem Ausführungsbeispiel nach Fig. 1 bei geöffneter Verbindung;

Fig. 3

die erfindungsgemäße Heizvorrichtung aus dem Ausführungsbeispiel nach Fig. 1 bei geschlossener fester Verbindung;

Fig. 4

eine feste Verbindung der Kontaktstellen gemäß Fig. 3 in vergrößerter Darstellung;

Fig. 5

eine feste Verbindung eines weiteren Ausführungsbeispiels der vorliegenden Erfindung;

Fig. 6

eine gelötete Verbindung gemäß einem weiteren Ausführungsbeispiel der vorliegenden Erfindung;

Fig. 7

eine Steckverbindung aus dem Stand der Technik in geöffneter Stellung; und

Fig. 8

die Steckverbindung aus dem Stand der Technik gemäß Fig. 7 in zusammengestecktem Zustand.

Show:

Fig. 1

an electrical heater according to the invention in a first embodiment in a perspective view before making a solid connection;

Fig. 2

a pair of contact points in an enlarged view according to the embodiment according to Fig. 1 with open connection;

Fig. 3

the heater according to the invention from the embodiment according to Fig. 1 when the connection is closed;

Fig. 4

a fixed connection of the contact points according to Fig. 3 in an enlarged view;

Fig. 5

a fixed connection of another embodiment of the present invention;

Fig. 6

a soldered connection according to another embodiment of the present invention;

Fig. 7

a connector of the prior art in the open position; and

Fig. 8

the connector of the prior art according to Fig. 7 in mated condition.

In the Fig. 1 shown additional heater 1 has a heating block 2 and a control device 4. At the in Fig. 1 shown perspective view heating block 2 and control device 4 are arranged spatially separated from each other.

The control device 4 has power devices 5 in the form of control electronics, which serve to control the heating elements 3 of the heating block 2.

For application with power contact points 6 are provided on the control device 4. The contact points 6 of the control device are brought together with the contact points 7 of the heating block and a firm connection between the contact points 6 and 7 is established.

In Fig. 2 an enlarged view of the contact points 6 of the control device and the contact points 7 of the heating block 2 is shown.

In Fig. 3 the heating device according to the invention is shown in the form of an additional heater 1 in assembled state. As a fastening device for the preparation of the fixed connection between the contact points 6 and contact points 7 are preferably self-tapping screws 9, which are carried out through holes or holes 13 in the contact points 6 and holes 14 in the contact points 7 and then screwed, so that the contact points 6 and 7 enter a firm and rigid connection, which is also form-fitting in this example.

The screws 9 are stretched or drilled in the embodiment with a predetermined and sufficiently high torque, so that a release by vibrations during operation and the like is reliably prevented.

Due to the bolt force, the contacting contact areas of the contact elements 6 and 7 to each other pressed so that a large contact surface is formed. This results in that the average current density in the contact surfaces and the contact resistance at the contact devices 8 is relatively low. As a result, the power loss at the transition points of the contact devices is reduced overall, so that the contact temperature decreases.

Among other things, these measures also increase the service life of the connection and the auxiliary heater as a whole, since possible sources of error are avoided.

In comparison, in the FIGS. 7 and 8 a conventional connector, as is known in the art. The contact points 6a and 7a are plugged together to make the contact, wherein at the contact point 7a a resilient plate is provided which exerts a certain pressure on the contact point 6a. However, this spring action can be with frequent plugging and unplugging the connection.

In addition, the areas in contact are relatively small overall, since under some circumstances, only at the kink of the spring plate, a contact.

Taking into account still further the declining spring effect in successive connections, so there is a total of the contact device known in the prior art, a relatively small contact surface, resulting in a relatively high transition resistance. As a result, the contact temperature is high and the power loss at the transition large.

In contrast, in the contact device 8 according to the invention Fig. 1 to 4 the contact resistance is small and the power loss low. Furthermore, in which in the FIGS. 7 and 8 illustrated prior art example solve the connection by z. B. by vibrations during operation in a motor vehicle Connection force wears off and the connection between the heater or heating element and the control electronics triggers.

That in the Fig. 1 to 4 illustrated embodiment of the additional heater according to the invention, however, has a positive connection of the contact elements 6 and 7, so that in principle a release by release of the spring action of a spring element 15 as in the prior art is avoided (at least with suitable screw torque).

At the in Fig. 5 illustrated embodiment, the heating block and the control device is carried out substantially the same as in the Fig. 1 to 4 illustrated embodiment.

In particular, the heating block with the heating elements and the control device with the power devices are constructed identically to those in FIG Fig. 1 to 4 illustrated embodiment.

In contrast to the embodiment according to Fig. 1 However, in the embodiment according to Fig. 5 Rivets provided to establish a firm connection between the contact elements 6 and 7.

Rivets have the advantage that a separate solution by vibration and the like, as is possible in screws under circumstances, is substantially excluded. They also allow a certain predefined force to be applied to the connection, although this force can be better controlled using screws.

By applying the force to the contact elements 6 and 7 in the production of the riveted joint, the contact elements 6 and 7 are pressed against each other reliably, so that there is a large contact area. Thus, in this embodiment, too, a low contact resistance and thus ensures a low power loss at the contact device 8.

In the Fig. 5 Plotted contact surface 16 extends substantially over the contact region of the contact elements 6 and 7 and is not limited to a line, as may be the case in the prior art. In all embodiments, the contact surfaces 16 are adapted to each other so that they can abut each other.

In all embodiments, corrugated fins 12 are provided on the heating elements 3 to increase the heat-emitting surface.

In the embodiment gem. Fig. 6 the essential parts of the heater are again performed the same as in the embodiments according to Fig. 1 to 5 ,

In contrast to the embodiments according to Fig. 1 and 5 is provided as a fastening device here a solder joint 11 between the contact elements 6 and the contact elements 7. Also by soldering (or welding) is a reliable solid connection between the contact elements 6 and 7 ensures that is not solved by vibration and usual aging phenomena.

A solder joint is also relatively easily detachable by the contact point of the contact elements 6 and 7 is brought to the solder joint 11 to a correspondingly adapted temperature. As a result, it is possible with relatively little effort to produce and release the contact connection between the contact elements 6 and 7 as often as desired. Even such a connection is wear-free.

In summary, there are a number of advantages when using the additional heater according to the invention.

Aging of the contact due to corrosion, moisture, dust and other contaminants, as in the known in the prior art heaters according to FIGS. 7 and 8 is possible excretes when using the heating device according to the invention. Furthermore, a better contact between the heating elements and the control electronics is achieved, which causes a lower contact resistance and thus a lower power loss.

Overall, the number of parts can be reduced because the contact is improved. This achieves better reliability.

The power supply of the power electronics or the heating network is designed so that it can absorb the mechanical stress of the expansion of the various components.

Preferably, the connection in all embodiments according to the present invention is selected so that an automated connection can be established. Therefore, the joints are essentially freely accessible, so that the heating device according to the invention can be assembled by an inexpensive automatic assembly.

Claims (10)

1. Electric heating device (1) for a vehicle, comprising
   at least one heating means (3) and
   at least one power means (5) electrically connected to said heating means (3) by means of at least a first (6) and a second (7) contact device of a contact means (8),
   characterized in that
   said contact means (8) is configured such that a tight interconnection of said first (6) and second (7) contact devices is establishable, wherein
   the contact areas of said first (6) and second (7) contact devices are adopted to each other to achieve a big contact surface (16) of the abutting contact areas which extends over a considerable part of the area of said contact devices (6, 7),
   said interconnection of said contact devices at said contact means (8) is form-fitting and rigid, and
   said interconnection is establishable by at least one fastening means which is selected from a group of fastening means comprising screwing means (9), rivet means (10) and clamping lever means (11).
2. Heating device according to at least one of the preceding claims, characterized in that said at least one heating means (3) is selected from a group of heating means (3) comprising resistance heating means, PTC heating means and the like.
3. Heating device according to claim 2, characterized in that at least one resistance heating means and at least one PTC heating means are provided.
4. Heating device according to at least one of the preceding claims, characterized in that the materials of said contact devices (6, 7) are selected such that galvanic corrosion is avoided.
5. Heating device according to at least one of the preceding claims, characterized in that said contact devices (6, 7) of said contact means (8) are configured such that an automatic interconnection can be established.
6. Heating device according to at least one of the preceding claims, characterized in that a plurality of heating means (3) and/or a plurality of power means (5) are provided, wherein preferably the number of power means (5) is equal to the number of heating means (3).
7. Heating device according to at least one of the preceding claims, characterized in that corrugated-fin means (12) are provided at at least one heating means (3).
8. Heating device according to at least one of the preceding claims, characterized in that at least one power means (5) comprises a control means controlling the thermal output of at least one heating means (3).
9. Heating device according to at least one of the preceding claims, characterized in that one control means is provided for essentially every power means (5).
10. Heating device according to at least one of the preceding claims, characterized in that the heating medium is a gas, and preferably air.

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