Patent Application
20210061066
This application claims priority to European Application No. 19195306.6 filed on Sep. 4, 2019, the contents of which are hereby incorporated by reference in its entirety.
The invention relates to a heating element. The invention also relates to a heating assembly with at least one such heating element and also to a motor vehicle with at least one air-conditioning device with such a heating element.
A heating assembly for a motor vehicle, in particular an electrically drivable road motor vehicle or preferably a hybrid road motor vehicle, in particular a battery-operated vehicle, usually has a number of PTC heating elements (PTC: Positive Temperature Coefficient) made up of one or more heating bodies (also PTC thermistors) comprising ceramic PTC resistors. By means of the PTC heating elements, a fluid, in particular interior air or a temperature control fluid, can be heated as desired. Particularly at the heating bodies, it is intended that their electrical resistance changes in dependence on the temperature. As a result, a temperature that varies only little is obtained at the heating bodies independently of the prescribed boundary conditions, such as for example operating voltage or nominal resistance.
In particular in the case of electrically drivable road motor vehicles or preferably hybrid road motor vehicles, a heating assembly or a PTC heating element may be fed by the traction storage battery or an additional storage battery used there primarily for drive propulsion. Operating voltages which are provided at the heating assembly or at the PTC heating element in this case usually lie in a voltage range of between 150 V and 400 V. In future, even voltages of up to 800 V will be required. Because of the relatively high operating voltages, however, extensive electrical insulation of the heating assembly and/or the PTC heating elements from one another is required, in order to avoid short-circuits and in order to protect occupants of the motor vehicle. For this purpose, it is often necessary to make all of the electrically conducting and externally exposed elements of the heating assembly or the PTC heating elements potential-free and/or to maintain a minimum constructional gap between individual PTC heating elements, which is intended to prevent a short-circuit between these elements. These are technically also referred to as air gaps or creepage distances, which are to be provided between the PTC heating elements. These minimum distances may be up to 4 mm or more, so that a heating assembly equipped with PTC heating elements is relatively large. In keeping with the times, it is desirable also to optimize heating assemblies equipped with PTC heating elements; in particular, there is a desire to create and provide a relatively compact heating assembly, for example in order to be able to satisfy today's relatively demanding vehicle package requirements.
DE 20 2011 110 647 U1 describes an electrical vehicle heating device which has plate-shaped PTC heating elements, which are in each case made up of a number of layers connected to one another with a material-bonding effect. In order to keep the air gaps and creepage distances relatively small, it is intended to provide the PTC heating elements additionally with insulating bodies, the insulating bodies being arranged with a material-bonding effect on electrically conductive functional bodies for the electrical contacting of the heating elements.
Relatively good electrical insulation with respect to the outside is provided by the known insulating bodies. However, the connection of the functional bodies to the insulating structures is inadequate, in particular against the background of increasing operating voltages, because for example the fatigue strength is reduced due to different coefficients of linear expansion of the materials paired or parts joined together.
The object of the invention is therefore to provide an improved or at least a different embodiment of a heating element and a heating assembly equipped with it.
In the case of the present invention, this object is achieved in particular by the subjects of the independent claim(s). Advantageous embodiments are the subject of the dependent claims and the description.
The basic idea of the invention is that of providing a functional separation, to be specific meeting the requirements demanded of the known functional bodies better than before, in that the functional bodies are divided on the basis of their functions into different functional body parts. This has the advantage that the individual functional body parts of the functional body in each case only have to perform a single function or a group of selected functions. This makes it possible to adapt functional body parts specifically to the respective functions. In the present case, it can therefore also be stated that the known functional bodies are optimized by functional separation.
Provided for this purpose is a heating element, in particular a PTC heating element, for heating a fluid, preferably air or temperature control fluid, which is preferably used on an electrically drivable motor vehicle. Specifically, the heating element has a heating body for converting electrical energy into thermal energy. Such heating bodies, in particular PTC heating bodies, may be operated in particular by means of an operating voltage, in particular DC voltage, of 400 V. For example, the operating voltage is provided at the heating element or on the heating body by means of a voltage supply system provided in the vehicle. The voltage supply system is for its part preferably fed by a traction storage battery. Furthermore, the heating body or the entire heating element may be designed in the form of a plate. This may mean that the heating body or the entire heating element defines two main directions of extent and a narrow direction of extent oriented transversely thereto, the heating body or the heating element always extending less far in the direction of the narrow direction of extent than in the direction of the two main directions of extent or than at least in the direction of a single main direction of extent. Furthermore, the heating body may be produced from a ceramic material. In any event, the heating body has two large heating areas oriented opposite one another. The term “large area” means in this connection that the heating body may have a peripheral side area bounding it, which connects the large areas to one another, the side area being designed to have a smaller surface area than the large areas. Preferably, the large heating areas are formed parallel or substantially parallel to one another. The heating element also has at least one insulating body for electrical insulation. The insulating bodies are also preferably produced from a ceramic material and preferably designed in the form of a plate, like the heating body. The heating element also has at least one functional body for providing an electrical conducting function, in particular an electrical conductivity, and for providing a bonding function, in particular the capability of forming a joining connection, in particular with a material-bonding, form-fitting and/or force-fitting effect, the functional body having large functional body areas oriented opposite one another. Preferably, the large functional body areas are formed parallel or substantially parallel to one another. Furthermore, the functional body may also preferably be designed in the form of a plate, like the heating body. In particular, the functional bodies, the insulating bodies and the heating body may in each case provide a thermal conducting function, in particular a thermal heat conductivity. It is also provided that in each case a pair of functional bodies are arranged on the heating body, so that in each case at least one large heating area lies substantially with its full surface area or with its full surface area against a large functional body area, in particular a large functional body area facing away from the insulating body, of the respective functional body, in particular in a physically and electrically contacting manner without any gap. The term “contacting” should be understood here as meaning that an electrically conductive intermediate layer may also be arranged between a functional body and the heating body, so that a functional body is not necessarily arranged in physical contact with the heating body, but in any event the electrical contact persists. Furthermore, an insulating body is arranged on at least one functional body, in such a way that the insulating body lies substantially with its full surface area or with its full surface area against a large functional body area facing away from the heating body of the respective functional body, in particular in a physically and at least thermally contacting manner without any gap. As a result, the functional body is preferably arranged, in particular fixed, with a material-bonding and/or force-fitting effect between the insulating body and the heating body in the manner of a sandwich or in the manner of a layer. It is essential to the invention that the functional body is of a two-part or multi-part design. It should also be mentioned in this connection that the term “multi-part” means two or more parts, for example three or four or more parts. By separating the functional body, it is possible to design different parts of the functional body differently on a functional basis, for example by a structural or material adaptation. In other words, a functional separation may be brought about by the separation of the functional body into two or more parts, so that for example one part can be optimized with respect to one function and another part can be optimized with respect to another function.
In particular, as a result a description is also given of an exemplary embodiment in which the heating element comprises exactly two functional bodies and exactly two insulating bodies. Preferably here, a large functional body area of a single functional body is in each case arranged on the two large heating areas of the heating body, substantially with its full surface area or with its full surface area. Also preferably, an insulating body is arranged on each functional body, in order to electrically insulate the respective functional body.
Expediently, for providing an electrical conducting function, in particular over a surface area, at least one functional body has at least one electrically conducting conductor structure part. For example, the conductor structure part is produced from an electrically conducting material, in particular from a silver or copper material. For example, the conductor structure part comprises sinterable electrical wire layers. By means of the conductor structure part, each functional body on the one hand can be electrically connected to the heating body. On the other hand, each functional body or insulating body may for example comprise a socket connector, on which the respective conductor structure part is arranged, while forming a contacting area. Preferably, the operating voltage necessary for operation can be fed in at the contacting areas, for example by means of the voltage supply system. This has the effect that the heating body can be supplied with electrical energy and therefore can be operated. It should also be mentioned that, in addition to the electrical conducting function, the conductor structure parts also provide a heat conducting function, so that heat can flow from the heating body through the conductor structure part.
Furthermore, for providing a bonding function, at least one functional body may have at least one bonding structure part. By means of the bonding structure part, the respective functional body can be fixed on the one hand on the heating body and/or on the other hand on the respective insulating body, in particular in a bonding manner, with a material-bonding and/or force-fitting and/or form-fitting effect. As a result, the heating element may altogether be provided as a joined-together structural unit. The bonding structure part is for example an adhesive or a glass solder or some other electrically non-conducting material. It should also be mentioned that, in addition to the bonding function, the bonding structure parts also provide a heat conducting function, so that heat can flow from the heating body through the bonding structure part.
In particular, the large heating area lying against the large functional body area on the heating body side may be electrically contacted by the conductor structure part over 0.1% to 50%, preferably 1% to 35%, of its surface area. This ensures that the heating body is electrically contacted over a sufficient percentage of its surface area to be able to provide the desired thermal function of the heating element unrestrictedly. This can likewise be achieved by a common contact area between the large functional body area on the heating body side and the large heating area being contacted by the conductor structure part over 0.1% to 50%, preferably 1% to 35%, of its surface area, in order to provide an electrical contacting area of 0.1% to 50%, preferably 1% to 35%.
Also in particular, the conductor structure part may form 0.1% to 50%, preferably 1% to 35%, of the volume of the functional body. It is also conceivable that the conductor structure part forms 0.1% to 50%, preferably 1% to 35%, of the surface area of the large functional body area on the heating body side and/or of the surface area of the large functional body area on the insulating body side. Also in this way, the electrical contacting of the heating body that ensures the desired operation of the heating element is ensured.
Expediently, the conductor structure part may be formed by a conductor path assembly comprising at least one electrically conductive conductor path for providing a surface-area electrical conducting function. The conductor path is in this case made of a silver material, a copper material and/or in a sinterable form. Furthermore, the conductor path assembly may preferably have a single electrically conductive conductor path or alternatively have a number of conductor paths that are electrically conductively separated from one another. It is also conceivable that the conductor path assembly has a number of conductor paths connected electrically conductively to one another with a material-bonding effect.
For the purpose of describing the conductor structure parts or conductor path assemblies or conductor paths, it should also be mentioned that the heating element preferably defines a Cartesian coordinate system, to be specific by a main axis, which is defined by the respective main direction of extent of the heating element, also by a transverse axis, which is defined orthogonally in relation to the main axis and orthogonally in relation to a surface normal of a large heating area, and also by a vertical axis, which is defined orthogonally in relation to the transverse axis and orthogonally in relation to the main axis.
Also expediently, the conductor path or the conductor paths of a conductor path assembly may define a comb-shaped, grid-shaped, cross-grid-shaped, meander-shaped or zig-zag-shaped conductor path pattern. In particular in the case of the comb-shaped design of a conductor path assembly, a surface-area electrical contacting of the heating body is achieved by a multiplicity of relatively narrow conductor paths parallel to one another, as in the case of a comb.
According to a preferred design, it is expediently provided that the respective conductor path pattern forms 0.1% to 50%, preferably 1% to 35%, of the surface area of the large functional body area on the heating body side. This has the advantage that a relatively closely or relatively widely meshed conductor path pattern can be provided, whereby for example the electrical contacting, in particular electrical contacting over a relatively large surface area, is possible.
Furthermore, one or more conductor paths may have a cross-sectional area which is oriented transversely in relation to its respective main direction of extent and is substantially rectangular or polygonal and constant or variable along the main direction of extent. In this case, the cross-sectional area may be wider in particular in the region of a socket connector of the heating element than in the region of a free end of the heating element arranged at a distance from the socket connector. This has the advantage that force effects on the heating element caused by thermal linear expansion are compensated.
Furthermore, it should also be mentioned that the conductor structure parts may be printed, adhesively bonded, sintered, soldered or stamped onto an insulating body or the heating body.
Preferably formed between the respective conductor structure parts or conductor path assemblies or conductor paths are imaginary clearances, in which the bonding structure parts are inserted. It is preferred here if a bonding structure part is formed as complementing and supplementing the conductor structure part. In this case, the bonding structure part may preferably be arranged on the conductor structure part with a material-bonding and/or force-fitting and/or form-fitting effect. This has the advantage that the functional body comprises exactly two parts, to be specific a conductor structure part and a bonding structure part. Altogether, in this way a relatively good electrical contacting of the heating body and a relatively good connection or bonding between the heating body, the functional body and the insulating body can be provided.
Expediently, the large heating area lying against the large functional body area on the heating body side may be connected in a bonding manner by the bonding structure part over 50% to 99.9%, preferably 65% to 99%, of its surface area, and the insulating body may be connected in this way over 50% to 100% of its surface area. This has the advantage that the heating body, the functional body and the insulating body form a relatively fixed subassembly, for example the components are undetachably fixed to one another.
Expediently, the bonding structure part may form 50% to 99.9%, preferably 65% to 99%, of the volume of the functional body. Also expediently, the bonding structure part may form 50% to 99.9%, preferably 65% to 99%, of the surface area of the large functional body area on the heating body side and/or of the surface area of the large functional body area on the insulating body side. In any event, it is preferred if the bonding structure part and the conductor structure part form 100% of the functional body.
According to a further idea, a common contact area between the large functional body area on the heating body side and the respective large heating area may be formed by the bonding structure part over 50% to 99.9%, preferably 65% to 99%, of its surface area, in order to fix an insulating body and the conductor structure part on the heating body with a material-bonding, force-fitting and/or form-fitting effect, so that an electrical contact between the conductor structure part and the heating body is established.
In particular, the bonding structure part may be formed by a bonding path assembly comprising at least one bonding path with a bonding effect for providing a bonding function, the bonding path assembly comprising exactly one single bonding path or a number of bonding paths that are separate from one another. Preferably, the bonding path assembly may comprise a number of bonding paths connected to one another with a material-bonding effect. A bonding path may preferably be produced from an electrically nonconducting adhesive or an electrically nonconducting glass solder or an electrically conducting material.
It is also provided in particular that the bonding path or the bonding paths of a bonding path assembly define a comb-shaped, grid-shaped, cross-grid-shaped, meander-shaped or zig-zag-shaped bonding path pattern, preferably like the conductor structure part.
It is also expedient if the respective bonding path pattern forms 50% to 99.9%, preferably 65% to 99%, of the surface area of the large functional body area on the heating body side, in order in particular to provide a relatively closely or relatively widely meshed bonding path pattern.
It is conceivable that the heating element may comprise a single functional body, which is wound around the heating body, so that a single contiguous large functional body area of the functional body is arranged on both large heating areas of the heating body substantially with its full surface area or with its full surface area, a pair of insulating bodies being arranged on the functional body in order to electrically insulate the functional body.
The heating body may also form or have an imaginary mirror plane or an imaginary mirror line, for example parallel to a coordinate plane defined by the vertical axis and the transverse axis, with respect to which the functional bodies, in particular the conductor structure parts and/or the bonding structure parts, are formed in a mirror-inverted or linear mirror-inverted manner. As a result, a diagonal and mirror-inverted arrangement as it were is provided with respect to the imaginary mirror plane or with respect to the imaginary mirror line. This has the advantage that a force effect of the heating body based on a thermal linear expansion can be compensated.
An intermediate layer may be arranged between one or all of the large heating areas and one or all of the large functional body areas. The intermediate layer is preferably of an electrically conductive design and preferably produced from a silver material or a silver alloy. For example, one or two or more layers of silver material are applied to the heating body. In this case, the electrical contacting of the heating body by means of the conductor structure parts takes place as it were through the intermediate layer. The intermediate layer has the advantage that the connection or contacting of the conductor structure parts and/or the bonding structure parts to the heating body is achieved more easily.
According to a further design, the insulating body and/or the heating body may have at least one open recess structured in the manner of a conductor path, in which a functional body is arranged, in particular a conductor structure part and/or a bonding structure part according to the previous description.
The invention comprises the alternative or additional further basic idea of providing a heating assembly, in particular PTC heating assembly, for heating a fluid. For this purpose, it is provided that the heating assembly is equipped with at least one heating element according to the previous description. Furthermore, the heating assembly has at least one circuit board designed for receiving and supplying power to heating elements, in particular a PCB (PCB: Printed Circuit Board). In this case at least one heating element may be operably arranged on the circuit board. As a result, a heating assembly by means of which fluid can be heated is provided.
Another basic idea of the invention, which can be realized in addition or as an alternative to the basic ideas mentioned further above, may be to equip a motor vehicle, in particular an electrically drivable road motor vehicle, preferably a hybrid motor vehicle, with an air-conditioning device which expediently serves for setting within a motor vehicle interior of the motor vehicle an air temperature that is prescribed or can be prescribed by a user. The air-conditioning device is equipped or can be equipped with at least one heating element and/or a heating assembly according to the previous description. The heating element and/or the heating assembly may in this case be used for example to maintain the temperature in the passenger compartment in the starting phase and in the driving phase of the motor vehicle, in particular when there are cold ambient temperatures.
Expediently, the heating element may be accommodated, in particular completely, in a housing, in particular a tubular housing. The housing is preferably produced from a ceramic material, is of a one-piece or multi-part form and additionally offers an electrical insulating effect, so that the heating element can additionally be insulated.
Preferably, each functional body is designed such that the respective conductor structure parts and bonding structure parts form a contiguous, uninterrupted body, in particular a relatively thin layer, for example 0.1 mm, 0.2 mm, 0.3 mm to 1 mm thick.
The heating bodies and/or the functional bodies and/or the insulating bodies and/or the intermediate layers may be formed in each case by a sheet-like, preferably layer-like, formation and expediently as relatively thin in each case, for example 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm to 1 mm thick.
To sum up, it remains to be stated: The present invention preferably relates to a heating element with a heating body for converting provided electrical energy into thermal energy. The heating element comprises at least one insulating body for electrical insulation and at least one functional body for providing an electrical conducting function and for providing a bonding function. In the assembled state, at least one functional body is arranged on the heating body, in order to electrically contact it. Furthermore, an insulating body is arranged on the respective functional body, in order to provide an electrical insulation of the functional body and of the heating body with respect to the outside. In this way, the heating body is preferably fixed between two functional bodies and two insulating bodies. It is essential to the invention that at least one functional body is of a two-part or multi-part design.
Further important features and advantages of the invention will emerge from the subclaims, from the drawings and from the associated description of the figures on the basis of the drawings.
It goes without saying that the features mentioned above and those still to be explained below can be used not only in the respectively specified combination but also in other combinations or on their own without departing from the scope of the present invention.
Preferred exemplary embodiments of the invention are shown in the drawings and will be explained in greater detail in the following description, with identical designations relating to identical or similar or functionally identical components.
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| Number | Date | Country | Kind |
|---|---|---|---|
| 19195306.6 | Sep 2019 | EP | regional |
