PTC HEATING ELEMENT AND A PTC HEATING MODULE

Abstract

A PTC heating element for a PTC heating module for a vehicle is disclosed. The PTC heating element includes a PTC thermistor having two main surface that, in a thickness direction of the PTC thermistor, are located opposite one another and spaced apart from one another. Two electrically conductive contact layers are applied to the two main surfaces of the PTC thermistor. A total quotient between a total geometrical area of the two contact layers and a total geometrical area of the two main surfaces is substantially below 1 and substantially above 0, e.g., between 0.05 and 0.85.

Claims

1. A PTC heating element for a PTC heating module for a vehicle, comprising: a PTC thermistor having two main surfaces, the two main surfaces in a thickness direction of the PTC thermistor are located opposite one another and spaced apart from one another, two electrically conductive contact layers that are each applied to the two main surfaces of the PTC thermistor, wherein a total quotient between a total geometrical area of the two contact layers and a total geometrical area of the two main surfaces is substantially below 1 and substantially above 0.

2. The PTC heating element according to claim 1, wherein the total quotient is between 0.1 and 0.8.

3. The PTC heating element according to claim 1, wherein respective quotients between respective geometrical areas of the two contact layers and respective geometrical areas of the main surfaces assigned to these differ from one another in the two contact layers.

4. The PTC heating element according to claim 1, wherein a distance of the two contact layers from one another, at least in some interior regions of the PTC thermistor, is greater than a thickness of the PTC thermistor.

5. The PTC heating element according to claim 1, wherein the two contact layers do not overlap in the thickness direction of the PTC thermistor at least in some interior regions of the PTC thermistor.

6. The PTC heating element according to claim 1, wherein at least one of the two contact layers has a comb structure including contact strips that are arranged spaced apart from one another and parallel to one another, and wherein the contact strips are contiguous on one side or both sides.

7. The PTC heating element according to claim 6, wherein at least one of: the contact strips of the comb structure of the at least one of the two contact layers are arranged at an uneven distance from one another, the contact strips of the comb structure of the at least one of the two contact layers have at least one of a width and a length that deviates from one another, and a width of at least one of the contact strips is smaller or greater than its distance from at least one of the adjacent contact strips.

8. The PTC heating element according to claim 6, wherein: the two contact layers each have the comb structure, wherein the respective comb structures are applied to the two main surfaces of the PTC thermistor such that the contact strips of the two comb structures are parallel to one another, and at least some of the contact strips of one of the comb structures do not locate opposite to any contact strips of the other of the comb structures.

9. The PTC heating element according to claim 1, wherein at least one of the two contact layers has a volute structure.

10. A PTC heating module for a vehicle, comprising: at least one PTC heating element, the at least one PTC heating element including: a PTC thermistor having two main surfaces that are located opposite one another and spaced apart from one another in a thickness direction of the PTC thermistor, two electrically conductive contact layers that are each applied to the two main surfaces of the PTC thermistor, wherein a total quotient between a total geometrical area of the two contact layers and a total geometrical area of the two main surfaces is between 0.05 and 0.85, wherein one of the two contact layers of the at least one PTC heating element is connected to a positive terminal contact and the other of the two contact layers of the at least one PTC heating element is connected to to a negative terminal contact in an electrically conductive manner.

11. The PTC heating module according to claim 10, wherein the total quotient is between 0.1 and 0.8.

12. The PTC heating module according to claim 10, wherein the total quotient is between 0.2 and 0.7.

13. The PTC heating module according to claim 10, wherein the total quotient is between 0.2 and 0.5.

14. The PTC heating module according to claim 10, wherein the total quotient is between 0.3 and 0.5.

15. The PTC heating module according to claim 10, wherein at least one of the two contact layers has a comb structure including a plurality of contact strips arranged spaced apart from one another and parallel to one another.

16. The PTC heating module according to claim 15, wherein the plurality of contact strips of the comb structure are arranged at an uneven distance from one another.

17. The PTC heating module according to claim 15, wherein the plurality of contact strips of the comb structure have at least one of a width and a length that deviates from one another.

18. The PTC heating module according to claim 15, wherein a width of at least one of the plurality of contact strips of the comb structure is smaller or greater than its distance from an adjacent one of the plurality of contact strips.

19. The PTC heating element according to claim 1, wherein the total quotient is between 0.05 and 0.85.

20. The PTC heating element according to claim 19, wherein the total quotient is between 0.2 and 0.7.

Description

[0026] Preferred exemplary embodiments of the invention are shown in the drawings and are explained in more detail in the following description, wherein same reference numbers relate to same or similar or functionally same components.

[0027] It shows, in each case schematically

[0028] FIG. 1 a view of a PTC heating element according to the invention;

[0029] FIG. 2 a sectional view of the PTC heating element shown in FIG. 1 through a section plane A-A shown in FIG. 1;

[0030] FIGS. 3 and 4 plan views of main surfaces of the PTC heating element shown in FIG. 1;

[0031] FIG. 5 a plan view of a main surface of the PTC heating element in a further embodiment;

[0032] FIG. 6 a sectional view of the PTC heating element shown in FIG. 5 through a section plane B-B shown in FIG. 5;

[0033] FIG. 7 a plan view of a main surface of the PTC heating element in a further embodiment;

[0034] FIG. 8 a sectional view of the PTC heating element shown in FIG. 1 through a section plane C-C shown in FIG. 7;

[0035] FIG. 9 a plan view of a main surface of the PTC heating element in a further embodiment;

[0036] FIG. 10 a sectional view of the PTC heating element shown in FIG. 9 through a section plane D-D shown in FIG. 9;

[0037] FIG. 11 a view of the arrangement of both contact layers of the PTC heating element in a further embodiment;

[0038] FIG. 12 a sectional view of the PTC heating element shown in FIG. 11 through a section plane E-E shown in FIG. 12.

[0039] FIG. 1 shows a view of a PTC heating element 1 according to the invention for a PTC heating module for a vehicle. The PTC heating element 1 comprises a PTC thermistor 2, which is produced for example from a PTC ceramic. Here, the PTC thermistor 2 is cuboid and has two main surfaces 3a and 3b, which in a thickness direction DR are located opposite one another and spaced apart from one another. A distance of the two main surfaces 3a and 3b from one another defines a thickness D.sub.PTC of the PTC thermistor 2. Furthermore, the PTC thermistor 2 has four lateral surfaces 5 which, to both its main surfaces 3a and 3b and in pairs are perpendicular to one another. The lateral surfaces 5 connect the main surfaces 3a and 3b on the edge side with one another and, together with these, demarcate the PTC thermistor 2 towards the outside. FIG. 2 now shows a sectional view of the PTC heating element 2 shown in FIG. 1 through the section plane A-A. FIGS. 3 and 4 show plan views of the main surfaces 3a and 3b of the PTC heating element 1 shown in FIG. 1.

[0040] Furthermore, the PTC heating element 1 comprises two electrically conductive contact layers 4a and 4b which are applied to the respective main surfaces 3a and 3b of the PTC thermistor 1. The respective contact layer 4a and 4b respectively is contiguous but does not completely cover the respective main surface 3a and 3b respectively of the PTC thermistor 2. The respective contact layer 4a and 4b respectively has a geometrical area F.sub.4A and F.sub.4B respectively and the respective main surface 3a and 3b respectively has a geometrical area F.sub.3A and F.sub.3B respectively. A quotient Q.sub.A and Q.sub.B respectively of the respective geometrical area F.sub.4A and F.sub.4B respectively and of the respective geometrical area F.sub.3A and F.sub.3B is below 1 and above 0. Thus the following applies:

Q.sub.A=F.sub.4A/F.sub.3A and 0<Q.sub.A<1

Q.sub.B=F.sub.4B/F.sub.3B and 0<Q.sub.B<1.

[0041] A total geometrical area F.sub.4 of the contact layers 4a and 4b is then the sum of the two areas F.sub.4A and F.sub.4B. Then, a total geometrical area F.sub.3 of the main surfaces 3a and 3b is the sum of the geometrical areas F.sub.3A and F.sub.3B. A total quotient Q between the total geometrical areas Fa and F.sub.3 is substantially below 1 and substantially above 0. Thus the following applies:

Q=F.sub.4/F.sub.3=(F.sub.4A+F.sub.4B)/(F.sub.3A+F.sub.3B) and 0<Q<1.

[0042] By way of the contact layers 4a and 4b, the PTC heating element 1 can be incorporated in an electrical supply circuit and supplied with voltage. Accordingly, the contact layers 4a and 4b are then each assigned a positive terminal and a negative terminal. In this direction DR between the two electrically conductive contact layers 4a and 4b the PTC thermistor 2 is arranged so that the PTC heating element 1 forms a condenser in the supply circuit.

[0043] The two contact layers 4a and 4b—see in particular FIG. 3 and FIG. 4—each have a comb structure 6a and 6b. In this exemplary embodiment, the comb structures 6a and 6b are configured so that the respective quotient Q.sub.A and Q.sub.B respectively is equal to 0.5. Accordingly, the total quotient Q is also equal to 0.5. However it is also conceivable that the two quotients Q.sub.A and Q.sub.B deviate from one another and/or from 0.5. It is also conceivable that the total quotient Q deviates from 0.5. The respective comb structure 6a and 6b respectively then comprises multiple contact strips 7a and 7b respectively, which are each contiguous on one side. The contact strips 7a and 7b respectively are arranged parallel to one another and spaced apart from one another. The two contact layers 4a and 4b and the two comb structures 6a and 6b respectively are applied to the main surfaces 3a and 3b in such a manner that the contact strips 7a and the contact strips 7b—see in particular FIG. 2—are orientated parallel to one another. Furthermore, the contact strips 7a and the contact strips 7b do not overlap in the thickness direction DR. To this end, the two comb structures 6a and 6b are arranged rotated relative to one another about a centre axis MA of the PTC thermistor 1 by 180°. The centre axis MA is orientated parallel to the thickness direction and passes through the centre of the respective PTC thermistor 2.

[0044] In the PTC heating element 1 shown here, the geometrical area F.sub.4A and F.sub.4B respectively of the contact layers 4a and 4b is reduced compared with a conventional PTC heating element with an identical PTC thermistor, as a result of which the capacity of the PTC heating element 1 is also reduced.

[0045] Advantageously, compared with a conventional PTC heating element, capacity-related current and because of this also voltage peaks in the PTC heating element 1 can be reduced because of this. This effect is already noticeable in a value range of the total quotient Q between 0.1 and 0.8 and particularly intensively in a value range of the total quotient Q between 0.2 and 0.7. Here, the total quotient Q equal to 0.5 is merely chosen exemplarily. In addition, the contact layers 4a and 4b are evenly distributed over the respective main surfaces 3a and 3b as a result of which the heating output of the PTC heating element 1 is noticeably improved. This effect is noticeable in particular in a value range of the total quotient Q between 0.3 and 0.5. The total quotient Q equal to 0.5 is merely chosen exemplarily here.

[0046] FIG. 5 shows a plan view of the main surface 3a and 3b respectively of the PTC heating element 1 in a further embodiment. In FIG. 6, a sectional view of this PTC heating element 1 through a section plane B-B shown in FIG. 5 is shown. Here, the contact strips 7a and 7b respectively of the comb structure 6a and 6b respectively, deviating from FIG. 1 to FIG. 4, are contiguous on both sides. The comb structures 6a and 6b are each applied adjacent to two adjacent lateral surfaces 5. The comb structures 6a and 6b are identical and arranged rotated about the centre axis MA of the PTC thermistor 2 relative to one another by 180°—see in particular FIG. 6. Because of this, the contact strips 7a and 7b and the contact layers 4a and 4b respectively do not overlap in the thickness direction DR in the interior regions 8 of the PTC thermistor 2.

[0047] FIG. 7 shows a plan view of the main surface 3a and 3b respectively of the PTC heating element in a further embodiment. FIG. 8 shows a sectional view of the PTC heating element 1 through a section plane C-C shown in FIG. 7. Here, the respective comb structure 6a and 6b respectively is identical to the respective comb structure 6a and 6b respectively from FIG. 5 and FIG. 6, but is deviatingly arranged on the main surface 3a and 3b respectively. Here, the comb structures 6a and 6b are each applied adjacent to one of the lateral surfaces 5. The two comb structures 6a and 6b are arranged rotated relative to one another about the centre axis MA of the PTC thermistor 2 by 180°. Because of this, the contact strips 7a and 7b respectively do not overlap the contact layers 4a and 4b in the thickness direction DR in the interior regions 8 of the PTC thermistor 2.

[0048] FIG. 9 shows a plan view of the main surface 3a and 3b respectively of the PTC heating element 1 in a further embodiment. FIG. 10 shows a sectional view of this PTC heating element 1 through a section plane D-D shown in FIG. 9. Here, the two comb structures 6a and 6b are identical to one another, wherein one of the contact strips 7a and 7b respectively has a greater width than other contact strips 7a and 7b respectively. Here, the comb structures 6a and 6b are each applied centrally. The two comb structures 6a and 6b are arranged rotated about the centre axis MA of the PTC thermistor 2 relative to one another by 180°. Because of this, the contact strips 7a and 7b or the contact layers 4a and 4b do not overlap in the thickness direction DR in interior regions 8 of the PTC thermistor 2.

[0049] The quotients Q.sub.A and Q.sub.B with the PTC heating elements 1 in FIG. 5 to FIG. 10 each amount to 0.5. The total quotient Q also amounts to 0.5. The same advantages as in the PTC heating element 1 from FIG. 1 to FIG. 4 are achieved with the PTC heating elements 1 shown here.

[0050] FIG. 11 shows a view of the PTC heating element 1 in a further embodiment. In FIG. 11, the PTC thermistor 2 is shown transparently, so that the two contact layers 4a and 4b are visible. FIG. 12 shows a sectional view of this PTC heating element 1 through a section plane E-E shown in FIG. 12. In this embodiment, the respective contact layer 4a and 4b respectively each has the comb structure 6a and 6b respectively, which is similar to the respective comb structure 6a and 6b in FIG. 1 to FIG. 4. The quotient Q.sub.A and Q.sub.B as well as the total quotient Q however are each equal to 0.3 here. Here, the two comb structures 6a and 6b are arranged in such a manner that the respective contact strips 7a and 7b do not overlap in the thickness direction DR. To this end, the two comb structures 6a and 6b are arranged rotated relative to one another about the centre axis MA of the PTC thermistor 2 by 180°.

[0051] A distance DAB of the two contact layers 4a and 4b relative to one another is greater than the thickness D.sub.PTC of the PTC thermistor 2 here. Because of this, the effective current path for electrons is increased and the capacity of the PTC heating element 1 reduced. The capacity-related current and because of this also voltage peaks can accordingly be reduced. Accordingly, the thickness D.sub.PTC of the PTC thermistor 2 can also be reduced without its utilisation characteristics changing noticeably. This effect can be achieved in particular in the value range of the total quotient Q between 0.2 and 0.5. The total quotient Q equal to 0.3 is merely chosen exemplarily here.