WO2009027188A1

WO2009027188A1 - Ptc-apparatus

Info

Publication number: WO2009027188A1
Application number: PCT/EP2008/060296
Authority: WO
Inventors: Werner Kahr; Jan Ihle
Original assignee: Epcos Ag
Priority date: 2007-08-27
Filing date: 2008-08-05
Publication date: 2009-03-05
Also published as: DE102007040407A1

Abstract

A PTC apparatus is specified with several PTC heating elements (1a, 1b), wherein one first part of the PTC heating elements (1a) has a first reference temperature (T1) which differs from a second reference temperature (T2) of the remaining PTC heating elements (1b) of the apparatus.

Description

PTC device

The invention relates to a PTC arrangement, in which the usual electrical components for current peaks to be reduced when switching.

From the document DE 10 2005 042 560 A1, a PTC heating coil is known in which the individual heating modules have different resistance values and can be controlled separately from one another.

An object to be solved is to provide an array of PTC elements having a small difference between inrush current and operating current.

This object is achieved by a PTC arrangement according to claim 1.

The PTC arrangement has several PTC elements. Of these PTC elements, at least a first part has a first reference temperature T _Re fi different from at least a second reference temperature T _Re f2 of the remaining PTC elements in that T _Re f2 is greater than T _Re fi.

The reference temperature of a PTC element is approximately equal to the temperature at which twice the minimum resistance value is reached.

In a preferred embodiment, approximately half of the PTC elements have a first reference temperature. The remaining PTC elements of the assembly have a second reference temperature that is higher than the first reference temperature.

In a preferred embodiment, the difference between the first reference temperature and the second reference temperature is preferably at least 10 ^° C. At a smaller difference, the effect achieved by the arrangement is smaller or disappears when the difference is too small.

Preferably, the number of PTC elements having the second higher reference temperature is approximately equal to the number of PTC elements having the first lower reference temperature.

In a preferred embodiment, the PTC elements having the higher second reference temperature and the PTC elements having the lower first reference temperature are preferably arranged in alternating order. The alternating order of PTC elements with high and low reference temperatures results in optimal distribution of the PTC elements so that there are no large local areas with uneven heat development. The alternating sequence ensures the most uniform heating possible.

When electrical components occur when switching on unwanted current peaks. Due to the current peaks, the electrical feeds and thus the line cross-sections, or additional components for control must be designed much stronger, resulting in significant additional costs. By arranging high and low reference temperature PTC elements, a small difference between the inrush current and the operating current can be achieved. The inrush current is the current that is applied to the PTC elements at power-up, and the operating current is the current that is applied to the PTC elements as the device continues to turn on. In contrast to an arrangement with PTC elements, in which all PTC elements have the same reference temperature, the best possible ratio of inrush current to operating current is thus achieved. If the ratio of the number of PTC elements shifts in favor of the PTC elements with a higher reference temperature or in favor of the PTC elements with a lower reference temperature, the ratio of PTC elements with high reference temperature to PTC elements with low reference temperature is not more at the optimum, which increases the difference between turn-on and operating current. An uneven distribution of high reference temperature PTC elements and low reference temperature PTC elements increases the inrush current of the device.

In a conventional arrangements of PTC elements with PTC elements with the same reference temperature, the inrush current is significantly greater than the operating current applied in the further course of time, so that in many applications undesirable current peaks occur when switching on. Due to the current peaks, the electrical feeds and thus the line cross-sections, or additional components for control must be designed much stronger, resulting in significant additional costs. The above-described arrangement of PTC elements with high and low reference temperature, a difference between the turn-on and operating current is achieved, which is lower than in an arrangement in which all PTC elements have the same reference temperature.

Preferably, the inrush current is greater than or equal to the operating current. By the above-described arrangement of PTC elements with high reference temperature and PTC elements with low reference temperature, it is possible to approximate the inrush current approximately to the operating current, so that the inrush current is preferably equal to or at least approximately as large as the operating current.

Due to the smaller difference between inrush current and operating current, a higher power dissipation can be achieved using the arrangement of high and low reference temperature PTC elements. Due to the smaller difference between inrush current and operating current, a higher operating current is preferably achieved with the same starting power.

The power extraction of an array of PTC elements is equivalent to the electrical power required for the amount of heat generated in the operating state.

The switch-on power is the electrical power that occurs during the switch-on process. It is equivalent to the amount of heat necessary to bring the assembly from ambient temperature to operating temperature.

Compared to an arrangement with PTC elements with the same reference temperature, the described arrangement with PTC Elements with high and low reference temperature preferably a reduced inrush current at the same operating current.

In a preferred embodiment, the arrangement can be made with PTC elements with high and low reference temperature with a smaller number of components, while still achieving the same residual electrical power. The electrical residual power refers to the power that emits the device after switching on heat. Due to the reduced number of PTC elements, the inrush current can be significantly reduced. By balanced mixing of PTC elements with different reference temperature, the inrush current can be significantly reduced. In comparison to an arrangement consisting only of PTC elements with a lower reference temperature, the number of PTC elements used can be reduced to approximately 80% in order to achieve the same residual power.

This reduces the number of PTC elements and thus the total surface area of the PTC elements. In heating applications in which the elements have thermal and electrical contact with a metal strip as found in heating coils, the area of the entire heating coil, and thus also the area of heat transfer, is the same.

The inrush current is thus lower due to the reduced number and the different reference temperature than in an arrangement consisting only of PTC elements with a lower reference temperature. In a preferred embodiment, the PTC arrangement is arranged in an electrically non-conductive positioning frame having a plurality of cavities. The PTC heating elements are arranged in the cavities, wherein the PTC heating elements are fastened with at least one flat electrical conductor. The flat electrical conductor is preferably applied to the positioning frame. Preferably, the flat electrical conductor is glued to the positioning frame, so that each individual cavity is sealed moisture-proof. The planar electrical conductor is not glued to the PTC heating elements, so that they are flexible in the cavities in the lateral direction. By preferably two-sided coverage of the PTC heating elements by means of flat electrical conductors a stress-free mechanical attachment and contacting is possible, while a maximum of flexibility is achieved.

The arrangement will be described below with reference to

Embodiments and the associated figures explained in more detail.

The drawings described below are not to be considered as true to scale. Rather, for better representation, individual dimensions can be enlarged, reduced or distorted.

Elements that are equal to each other or that perform the same function are denoted by the same reference numerals.

FIG. 1 shows the time profile of the current consumption of a PTC arrangement with PTC elements each having a different reference temperature and 80% of the number of PTC elements in comparison with a PTC element. Arrangement with PTC elements with the same reference temperature when measured at 25 ^° C. ambient temperature.

FIG. 2 shows the time profile of the current consumption of a PTC arrangement as in FIG. 1 during a measurement at 0 ^° C. ambient temperature.

Figure 3 shows the time course of the current consumption of a PTC device as in Figure 1, when measured at -20 ⁰ C ambient temperature.

Figure 4 shows the time course of the current consumption of a PTC arrangement with PTC elements each having a different reference temperature for the same number of PTC elements in comparison with a PTC arrangement with PTC elements with the same reference temperature in a measurement at 25 ⁰ C ambient temperature.

FIG. 5 shows the time profile of the current consumption of a PTC arrangement as in FIG. 4 during a measurement at 0 ^° C. ambient temperature.

Figure 6 shows the time course of the current consumption of a PTC device as in Figure 4, when measured at -20 ⁰ C ambient temperature.

FIG. 7 shows a schematic exploded view of the PTC arrangement in a positioning frame in three-dimensional representation FIG. 8 shows an exemplary arrangement of the PTC elements with different reference temperature.

FIG. 1 shows a time profile of the current consumption of two different PTC arrangements. The curve 10a shows the time profile of the current consumption of a PTC arrangement with PTC elements with high and low reference temperature. Compared to a PTC arrangement having only PTC elements with the same reference temperature, only 80% of the area of PTC elements is used in the PTC arrangement shown in the curve 10a. The curve 10a has its maximum of the inrush current at 23.8 A. In the further course of time, the curve drops to an operating current of 18.1 A. The curve 10b shows the time profile of the current consumption of a PTC arrangement with PTC elements with the same reference temperature. The curve 10b has its maximum of the inrush current at 26.9 A. In the further course of time, the curve drops to an operating current of 16.9 A. The inrush current of the curve 10a is smaller than the curve 10b by 2.9A. The operating current after 60 s is 1.2A higher in the curve 10a compared to curve 10b. The measurement was carried out at a constant 25 ^° C. ambient temperature.

The reference temperature for this and the following measurements in Figures 2 to 6 were 140 ⁰ C and 170 ⁰ C in an array of PTC elements with different reference temperature, or at 140 ⁰ C in an arrangement with the same PTC elements with the same reference temperature.

The applied voltage was 13.5 V for each measurement with a resistance of the PTC elements of 8.2 ± 0.3 ohms. In the measurements in FIGS. 1 to 3, with a possible maximum population of 17 PTC elements, only 12 PTC elements were used for equipping with PTC elements with different reference temperatures, and 15 of 17 possible for the arrangement with PTC elements with the same reference temperature , In the measurements in FIGS. 4 to 6, 17 PTC elements each were used.

FIG. 2 shows the time profile of the current consumption of two different PTC arrangements. The curve 10a shows the time profile of the current consumption of a PTC arrangement with PTC elements with high and low reference temperature. Compared to a PTC arrangement having only PTC elements with the same reference temperature, only 80% of the area of PTC elements is used in the PTC arrangement shown in the curve 10a. The curve 10a has its maximum of the inrush current at 23.8 A. In the further course of time, the curve drops to an operating current of 20.9 A. The curve 10b shows the time profile of the current consumption of a PTC arrangement with PTC elements with the same reference temperature. The curve 10b has its maximum of the inrush current at 26.9 A. In the further course of time, the curve drops to an operating current of 19.7 A. The inrush current of the curve 10a is smaller than the curve 10b by 2.9A. The operating current after 60 s is 1.2A higher in the curve 10a compared to curve 10b. The measurement was carried out at a constant 0 ⁰ C ambient temperature.

FIG. 3 shows a time profile of the current consumption of two different PTC arrangements. The curve 10a shows the time profile of the current consumption of a PTC Arrangement with PTC elements with high and low reference temperature. Compared to a PTC arrangement having only PTC elements with the same reference temperature, only 80% of the area of PTC elements is used in the PTC arrangement shown in the curve 10a. The curve 10a has its maximum of the inrush current at 23.8 A. In the further course of time, the curve drops to an operating current of 22.8 A. The curve 10b shows the time profile of the current consumption of a PTC arrangement with PTC elements with the same reference temperature. The curve 10b has its maximum of the inrush current at 26.9 A. In the further course of time, the curve drops to an operating current of 22.8 A. The inrush current of the curve 10a is smaller than the curve 10b by 2.9A. The operating current after 60 s is identical to the curve 10b in the curve 10a. The measurement was performed at a constant ambient temperature -20 ⁰ C.

In FIGS. 1 to 3, the curves 10a for a PTC arrangement in which PTC elements with a high and a low reference temperature are used exhibit a lower inrush current and after 60 s a somewhat higher operating current than the curves 10b. The lower inrush current is achieved by the smaller number of PTC elements in a PTC arrangement using high and low reference temperature PTC elements.

Figures 4 to 6 have a slightly different population with PTC elements, as shown in Figures 1 to 3. Thus, in Figures 4 to 6 for the different curves instead of the reference numerals 10a and 10b, the reference numerals IIa and IIb are used. FIG. 4 shows the time profile of the current consumption of two different PTC arrangements. The curve 10a shows the time profile of the current consumption of a PTC arrangement with PTC elements with high and low reference temperature. Compared with FIGS. 1 to 3, PTC arrangements in which the area is identical are used both in the two illustrated curves 10 and 10b. The curve 10a has its maximum of the inrush current at 30.3 A. In the further course of time, the curve sinks to an operating current of 17.5 A from. The curve 10b shows the time profile of the current consumption of a PTC arrangement with PTC elements with the same reference temperature. The curve 10b has its maximum of the inrush current as the curve 10a at 30.3 A. In the further course of time, the curve drops to an operating current of 15.6 A. The inrush current of the curve 10a is identical to the curve 10b. The operating current after 60 seconds is 1.1A higher in the curve 10a compared to curve 10b. The measurement was carried out at a constant 25 ^° C. ambient temperature.

FIG. 5 shows the time profile of the current consumption of two different PTC arrangements. The curve 10a shows the time profile of the current consumption of a PTC arrangement with PTC elements with high and low reference temperature. Compared with FIGS. 1 to 3, PTC arrangements are used both in the two illustrated curves 10 and 10b in which the surface is identical. The curve 10a has its maximum of the inrush current at 30.3 A. In the further course of time, the curve drops to an operating current of 21.3 A. The curve 10b shows the time profile of the current consumption of a PTC arrangement with PTC elements with the same reference temperature. The curve 10b has its maximum of the inrush current as well as the curve 10a at 30.3 A. In the further course of time, the curve drops to an operating current of 19.1 A. The inrush current of the curve 10a is identical to the curve 10b. The operating current after 60 seconds is 1.4A higher in the curve 10a compared to curve 10b. The measurement was carried out at a constant 0 ⁰ C ambient temperature.

FIG. 6 shows the time profile of the current consumption of two different PTC arrangements. The curve 10a shows the time profile of the current consumption of a PTC arrangement with PTC elements with high and low reference temperature. Compared with FIGS. 1 to 3, PTC arrangements in which the area is identical are used in both illustrated curves 10 and 10b. The curve 10a has its maximum of the inrush current at 30.9 A. In the further course of time, the curve sinks to an operating current of 26.3 A from. The curve 10b shows the time profile of the current consumption of a PTC arrangement with PTC elements with the same reference temperature. The curve 10b has its maximum of the inrush current slightly lower than the curve 10a at 30.3 A. In the further course of time, the curve drops to an operating current of 22.5 A. The operating current after 60 s is 3.8 A higher in curve 10a compared to curve 10b. The measurement was performed at a constant ambient temperature -20 ⁰ C.

In FIGS. 4 to 6, the curves 10a for a PTC arrangement in which PTC elements with a high and low reference temperature are used exhibit an approximately identical inrush current and after 60 s a slightly higher operating current than curves 10b. Since in the two, in the curves 10a and 10b shown PTC arrangement used the same number of PTC elements and the inrush current is approximately equal.

FIG. 7 shows a three-dimensional exploded view of the heating module. The positioning frame 2 of the heating module has a plurality of cavities 3, which are preferably distributed uniformly over the entire length of the positioning frame 2. The cavities 3 serve to receive a plurality of PTC heating elements 1. The cavities 3 preferably have a rectangular shape. The PTC heating elements 1 preferably also have a rectangular shape. The circumference of the PTC heating elements 1 is preferably slightly smaller than the circumference of the cavity 3. The PTC heating elements 1 thus have no contact with the edge region of the cavities 3, so that the PTC heating elements Ia, Ib within the cavity 3 in lateral Direction are movable. On the positioning frame 2, planar electrical conductors 4 are applied on both sides. The sheet-like electrical conductors 4 are preferably applied to the planar surfaces of the positioning frame 2 via a bond. The positioning frame 2 has on both sides a narrow web 5, which serves to guide the flat electrical conductor 4. The width of the planar electrical conductor 4 corresponds approximately to the width of the free planar surface of the positioning frame 2 between the webs arranged on both sides 5.

FIG. 8 shows a partial view of the positioning frame 2 from above. The cavities 3 are distributed uniformly over the entire length of the positioning frame 2. The positioning frame 2 has a narrow web 5 on both sides on the edge. The PTC heating elements Ia with high Reference temperature Tl and the PTC heating elements Ib with low reference temperature T2 are arranged alternately in the cavities 3 of the positioning frame 2. The alternating order of PTC elements with high and low reference temperatures results in optimal distribution of the PTC elements so that there are no large local areas with uneven heat development. The alternating sequence ensures the most uniform heating possible. In order to achieve the most homogeneous possible heat distribution, it is advantageous to choose a changing order of the reference temperatures in the PTC elements for the assembly.

Although only a limited number of possible developments of the invention could be described in the embodiments, the invention is not limited to these. It is in principle possible to use a different shape of the positioning frame for the arrangement or to arrange the elements in a staggered position to each other. The invention is not limited to the number of schematically illustrated elements.

The description of the objects and methods disclosed herein is not limited to the individual specific embodiments. Rather, the features of the individual embodiments - as far as technically reasonable - can be combined with each other. LIST OF REFERENCE NUMBERS

1 PTC element

Ia PTC element with high reference temperature

Ib PTC element with low reference temperature

10a, IIa course of current consumption of a PTC arrangement with

PTC elements with high and low

Reference temperature 10b, IIb Course of current consumption of a PTC arrangement with

PTC elements with the same reference temperature Tl high reference temperature T2 low reference temperature

2 positioning frames

3 cavity

4 flat electrical conductors

5 footbridge

Claims

claims

1. PTC arrangement comprising a plurality of PTC heating elements (Ia, Ib), wherein a first part of the PTC heating elements (Ia) has a first reference temperature (Tl), which differs from a second reference temperature (T2) of the remaining PTC heating elements (Ib) of the arrangement differs.

2. PTC arrangement according to claim 1, wherein the first half of the PTC heating elements (Ia) has a first reference temperature (Tl) which is greater than the second reference temperature (T2) of the remaining PTC heating elements (Ib) of the arrangement.

3. PTC arrangement according to one of the preceding claims, wherein the difference between the first reference temperature

(Tl) and the second reference temperature (T2) is at least 10 ° Celsius.

4. PTC arrangement according to one of the preceding claims, wherein the number of PTC heating elements (Ia) with the first higher reference temperature (Tl) is preferably the number of PTC heating elements (Ib) with the second lower reference temperature (T2).

5. PTC arrangement according to one of the preceding claims, wherein the PTC heating elements (Ia) with the higher first reference temperature (Tl) and the PTC heating elements (Ib) with the low second reference temperature (T2) are arranged in an alternating sequence.

6. PTC arrangement according to one of the preceding claims, which is a small difference between an inrush current, the when switching on, and an operating current that is applied a short time after switching on.

7. PTC arrangement according to one of the preceding claims, which has an inrush current which is greater than or equal to the operating current.

8. PTC arrangement according to one of the preceding claims, wherein the difference between the turn-on and operating current is lower than in an arrangement in which all PTC heating elements (Ia, Ib) have the same reference temperature (Tl, T2).

9. PTC arrangement according to one of the preceding claims, which has a higher power output by the lower difference between inrush current and operating current than in an arrangement in which all PTC heating elements (Ia, Ib) have the same reference temperature (Tl, T2).

10. PTC arrangement according to one of the preceding claims, with an electrically non-conductive positioning frame (2) having a plurality of cavities (3) and with a plurality of PTC heating elements

(Ia, Ib), which are arranged in the cavities (3), wherein the PTC heating elements (Ia, Ib) are covered by at least one flat electrical conductor (4), which is applied to the positioning frame (2), wherein the planar electrical conductors (4) and the positioning frame (2) are connected to each other such that each individual cavity (3) is sealed moisture-proof.