This application claims priority to German Application 10 2018 205 279.4 filed on Apr. 9, 2018, the contents of which are hereby incorporated by reference in its entirety.
The present invention relates to a PTC thermistor module for a temperature control device, which has at least two PTC thermistor elements. The invention relates, furthermore, to a method for producing such a PTC thermistor module and a temperature control device with at least one such PTC thermistor module.
Temperature control devices are used for controlling the temperature of a fluid or an object. For generating heat and therefore for heating in the temperature control device, it is known to use PTC thermistor elements, which have an increasing electrical resistance with increasing temperature. Such PTC thermistor elements, also designated as PTC elements, are advantageous in particular owing to their self-regulating characteristic. Such PTC thermistor elements are usually combined in PTC thermistor modules, wherein in the respective module usually a row of PTC thermistor elements is provided, to which an electrical voltage is applied during operation, in order to generate heat within the respective PTC thermistor element. The heat generated in the respective PTC thermistor element is usually discharged via sides of the respective PTC thermistor module facing away from one another and is used for the purpose of heating in the temperature control device. For this, generally heat-conducting plates are used, which are in heat-exchanging contact with the sides of the PTC thermistor elements which are facing away from one another, i.e. for example with an upper side and with an underside, facing away therefrom, of the respective PTC thermistor element, and which therefore discharge the generated heat and make it available for the temperature control device.
In particular owing to the electrical operation, in such PTC thermistor modules a range of safety factors are to be taken into consideration. This includes the electrical protection with respect to the exterior, which requires an electrical insulation of the PTC thermistor module. The protection from liquids, in particular the penetration of liquids into the interior of the PTC thermistor module, is to be prevented. These requirements are usually solved in that the PTC thermistor module is provided with further components which respectively at least partly fulfil a corresponding requirement, wherein these components are applied or respectively fastened to one another, in particular glued or pressed. For example, electric leads and the PTC thermistor elements are generally glued. In addition, the heat-conducting plates are applied to the electric leads, in particular glued. Also in an associated temperature control device, the respective PTC thermistor module is usually glued with further components of the temperature control device, which include for example frame parts, rib structures and suchlike.
This leads to a reduced transport of the heat generated by the PTC thermistor elements to the required locations in the temperature control device, which negatively impairs the efficiency of the PTC thermistor module. In addition, the applying of various components to one another harbours the danger that these do not form a uniform or flat abutment, so that the transport of heat between these components is also reduced. In particular, air pockets and uneven areas can form between these components, wherein the air pockets, in addition to a poor thermal conductivity, offer scope for electrical short-circuits and for the penetration of liquids.
These disadvantages are increased with increasing operating voltages of the PTC thermistor modules, because more and/or larger components come into use to fulfil the safety requirements. This applies, for example, to PTC thermistor modules which are used in electrically or at least partially electrically operated motor vehicles, in which the respective PTC thermistor module is operated with increasingly high electric voltages, in particular with the on-board electrical system voltage of the motor vehicle, which can be a few 100 V, for example 800 V.
The present invention is therefore concerned with the problem of indicating, for a PTC thermistor module with at least two PTC thermistor elements and for a method for producing the PTC thermistor module and for a temperature control device with such a PTC thermistor module, improved or at least alternative embodiments which are distinguished in particular by an increased safety and/or an improved efficiency.
This problem is solved according to the invention by the objects of the independent claims. Advantageous embodiments are the subject of the dependent claims.
The present invention is based on the general idea of receiving PTC thermistor elements of a PTC thermistor module in a receiving body which is electrically insulating but, at the same time, has good thermal conductivity, which encompasses the PTC thermistor elements in a circumferential direction. The receiving of the PTC thermistor elements in the receiving body leads in particular to a prevention or at least reduction of air pockets within the PTC thermistor module, so that the heat transmission within the PTC thermistor module and therefore from the PTC thermistor elements at outer surfaces of the PTC thermistor module is improved, and consequently the efficiency of the PTC thermistor module is increased. In addition, hereby in addition to an improved electrical insulation, also a prevention or at least reduction of the penetration of liquids into the PTC thermistor module is achieved, so that with the improved efficiency also the operational reliability of the PTC thermistor module, and namely also with the receiving body, is improved. In accordance with the idea of the invention, the PTC thermistor module has at least two PTC thermistor elements, which are arranged spaced apart from one another by separation sections, in particular along a row. The PTC thermistor module has, in addition, at least two electric lines, spaced apart from each other, for the electrical supply of the PTC thermistor elements, which are in electrical contact with the PTC thermistor elements. The PTC thermistor elements are received in the electrically insulating receiving body, which surrounds or respectively encompasses the PTC thermistor elements in a closed manner in a circumferential direction. The receiving body is therefore a body enveloping the PTC thermistor elements in a closed manner in circumferential direction, which body accordingly can also be designated as an electrically insulating enveloping body.
The electrically insulating characteristic of the receiving body is expediently configured such that it has a specific electrical resistance of at least 108 Ω·cm. Therefore, an electrical insulation of the PTC thermistor elements is guaranteed or at least improved through the receiving body, also at high operating voltages of the PTC thermistor module, for example at voltages of at least 60 V, in particular at up to 800 V and more.
The receiving body is preferably embodied so as to be solid, i.e. not as a hollow body. This leads to an improved electrical insulation and to an improved heat transmission by means of the receiving body. In addition, air pockets in the PTC thermistor module, in particular between the receiving body and the PTC thermistor element, are therefore at least reduced.
Embodiments are preferred in which the receiving body lies, preferably flat, against at least one circumferential side of the respective PTC thermistor element, particularly preferably against at least two circumferential sides of the respective PTC thermistor element, wherein circumferential sides of the respective PTC thermistor element are the outer surfaces of the PTC thermistor element following one another in circumferential direction. Hereby, at said circumferential sides, a preferably flat contact exists between the receiving body and the PTC thermistor elements, which improves the heat transmission between the PTC thermistor elements and the receiving body and at least reduces air pockets between the receiving body and the PTC thermistor elements. Consequently, both the efficiency is raised, and also the operational reliability is increased. Embodiments are conceivable here, in which the receiving body lies against two opposite circumferential sides of the respective PTC thermistor element. The resting of the receiving body on the respective circumferential side is preferably flat. Here, the receiving body can lie directly against at least one of the circumferential sides.
The electrical contact between the respective line and the PTC thermistor elements is preferably realized by an abutting of the respective line against the respective PTC thermistor element. The abutting is advantageously flat and/or air-free. Particularly preferably, the abutting is direct, i.e. the respective line lies directly against the respective PTC thermistor element. The abutting of the respective line against the PTC thermistor elements leads, on the one hand, to the electrical current flowing in an improved manner between the lines and the PTC thermistor elements. In addition, hereby an improved heat transmission is present between the PTC thermistor elements and the lines. Furthermore the, in particular direct, abutting of the respective line against the PTC thermistor elements leads to air pockets between the PTC thermistor elements and the lines being prevented or at least reduced.
Embodiments are preferred, in which the respective line lies with an associated line section against at least one circumferential side of the respective PTC thermistor element, wherein the lines and the line sections of the different lines are, furthermore, spaced apart from one another.
Embodiments prove to be advantageous, in which the receiving body surrounds, in particular encompasses, at least one of the electric lines in circumferential direction. This means that the receiving body surrounds not only the PTC thermistor elements, but also at least one of the electric lines in circumferential direction, preferably in a closed manner. Particularly preferably, the receiving body lies here against at least one of the sides of the respective line which do not lie against the PTC thermistor element, in particular against the side of the respective line facing away from the PTC thermistor elements, wherein a direct abutting is preferred. Hereby, on the one hand, an additional fixing of the respective electric line in the PTC thermistor module and/or on the PTC thermistor elements, can be dispensed with. Furthermore, by means of the receiving body, at the same time an electrical insulation of the electric lines takes place, wherein this preferably takes place without air pockets, i.e. the receiving body lies directly against the respective electric line. When both lines are surrounded, in particular encompassed, by the receiving body, an interaction between the two lines outside the PTC thermistor elements, i.e. in particular short-circuits and suchlike, is also prevented or at least reduced, so that the operational reliability is further improved and/or the PTC thermistor module can be operated with a higher voltage.
In advantageous embodiments, at least one of the separation sections between two adjacent PTC thermistor elements is filled at least partly, particularly preferably entirely, by the receiving body. The receiving body can therefore, in the manner of a matrix, have mounts for the respective PTC thermistor element, wherein the mounts are spaced apart from one another. It is particularly preferred here if the receiving body lies in the separation sections against at least one of the face sides, delimiting the separation section, of at least one PTC thermistor element, preferably of both PTC thermistor elements, wherein the face side is an outer surface of the PTC thermistor element. Advantageously, the abutting is flat. Particularly preferably, the receiving body lies directly against at least one of the face sides, preferably both face sides. Therefore, an electrical insulation is also created between the PTC thermistor elements which are spaced apart from one another, which, in addition, prevents or at least reduces air pockets, wherein this, again, takes place with the same receiving body. At the same time, also, a form-fitting fixing of the PTC thermistor elements is achieved.
Through the, in particular direct, abutting of the receiving body against the PTC thermistor element or respectively the respective line, a heat transmission within the PTC thermistor module is improved, so that the efficiency of the PTC thermistor module is increased.
The receiving body has expediently a sufficient thermal conductivity for the transmission of heat occurring in the PTC thermistor elements during operation. Preferably, the receiving body has a thermal conductivity of at least 5 W/mK, particularly preferably of at least 20 W/mK, for example between 20 W/mK and 300 W/mK.
The receiving body can be produced basically in any desired manner, in so far as it is electrically insulating and encompasses the PTC thermistor elements in circumferential direction.
Embodiments are particularly preferred, in which the PTC thermistor elements are embedded into the receiving body. In the mounted state of the PTC thermistor module, the PTC thermistor elements are therefore securely integrated in the receiving body, in particular are fixed therein in a form-fitting and/or force-fitting manner. This makes it possible, on the one hand, to further prevent or at least reduce air pockets and, on the other hand, to increase the heat transmission within the PTC thermistor module.
It is conceivable to produce the receiving body in one piece and made from a single material, or respectively monolithically. Therefore, it is possible to carry out a more precise adaptation of the receiving body to the PTC thermistor elements and/or to the lines. In addition, hereby the risk of air pockets is further reduced and the heat transmission is further improved.
Embodiments are conceivable, in which the receiving body is constructed in several parts, wherein the parts of the receiving body, in the mounted state of the PTC thermistor module, are fixed to each other. This enables a more flexible installation of the PTC thermistor module.
Embodiments are to be considered in which the receiving body has two half-shells which follow one another in circumferential direction and extend along the PTC thermistor elements. This enables a simplified installation of the PTC thermistor module. For example, the PTC thermistor elements can be arranged in one of the half-shells and can be closed by the other half-shell such that the half-shells encompass the PTC thermistor elements in circumferential direction. It is also conceivable to arrange at least one of the lines in one of the half-shells before closing.
Embodiments are advantageous, in which the receiving body forms the outer surface of the PTC thermistor module, with which parts which are separate from the PTC thermistor module, for example an associated temperature control device exchange heat or respectively with which a fluid flowing around the PTC thermistor module exchanges heat. It is expedient here if the receiving body fixes the PTC thermistor elements and the lines.
Embodiments are also conceivable, in which the PTC thermistor module has a tubular body which forms the outer surface of the PTC thermistor module. The tubular body is, for example made from a metal or from a metal alloy and lies preferably directly and flat against the receiving body. This means that the tubular body encompasses the receiving body in circumferential direction and lies against the receiving body. With the tubular body, a mechanical stability of the PTC thermistor module is improved. In addition, it is hereby possible to protect the receiving body.
Embodiments prove to be advantageous, in which the receiving body is produced by a sintering method. The receiving body is advantageously sintered from a ceramic powder, with ceramic grains also being included, in particular a ceramic. This enables a simple production of the receiving body or respectively of the PTC thermistor module. In addition, consequently, accurately fitting formations of the receiving body are possible.
The production of the receiving body by the sintering method can comprise the production of several parts of the receiving body, for example the half-shells, or the production of the single-piece and monolithic receiving body.
For the latter variant, it proves to be advantageous if the PTC thermistor elements are arranged into a tool and the tool is subsequently filled with the ceramic powder and this is sintered for the production of the receiving body.
After the arranging of the PTC thermistor elements therein, the tool is filled with the ceramic powder such that after the sintering of the ceramic powder for producing the receiving body, no or at least reduced air pockets are present.
It is conceivable here, before the sintering of the ceramic powder, preferably also before the filling of the tool with the ceramic powder, that at least one of the lines, preferably both lines, is/are arranged into the tool. Therefore, in addition to the compact construction of the PTC thermistor module, air pockets between the receiving body and the at least one line are also prevented or at least reduced.
It shall be understood that, in addition to the PTC thermistor module, also a temperature control device belongs with the PTC thermistor module to the scope of this invention. The PTC thermistor module is used here for heating an object or a fluid, for example air.
It is conceivable to provide several PTC thermistor modules, spaced apart from one another, in a flow chamber of the temperature control device, which PTC thermistor elements are flowed around by a fluid during operation and thus heat the fluid. In the flow chamber, between adjacent PTC thermistor modules respectively at least one rib structure can be arranged, which is able to be flowed through for the fluid and therefore improves a heat transmission between the PTC thermistor module and the fluid.
Further important features and advantages of the invention will emerge from the subclaims, from the drawings and from the associated figure description with the aid of the drawings.
It shall be understood that the features mentioned above and to be explained further below are able to be used not only in the respectively indicated combination, but also in other combinations or in isolation, without departing from the scope of the present invention.
Preferred example embodiments of the invention are illustrated in the drawings and are explained further in the following description, wherein the same reference numbers refer to identical or similar or functionally identical components.
There are shown, respectively diagrammatically
A temperature control device 1, as is illustrated in
In the example shown in
In
Another example embodiment of the PTC thermistor module 2 can be seen in
A further example embodiment of the PTC thermistor module 2 is shown in
In
Number | Date | Country | Kind |
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102018205279.4 | Apr 2018 | DE | national |