JPH10189223A - Ptc heater unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the following property of the surface temperature of a heating plate to the change of the surrounding temperature and suppress the generation of the uneven temperature in the surface temperature by specifying heat conductivity, operation temperature of a PTC element, and the ratio of the area of the PTC element to the area of the heating plate. SOLUTION: The heat conductivity of a heating plate 5 coming in contact with a heater unit through an insulating plate 6 is specified to 100w/m.K or less, the operating temperature (Curie point) of a PTC element 1 is specified to 200 deg.C or more, and the ratio of the area of the PTC element 1 to the area of the heating plate 5 is specified to 30% or more. Even when the surrounding temperature has declined, the surface temperature of the non-contact part with the PTC element 1 is rarely dropped, and the surface temperature following capability of the heating plate 5 to the change of the surrounding temperature is good. As the PTC element, a ceramic material of (Ba, Pb)TiO3 is preferable, and as the heating plate, an iron base material such as stainless steel is preferable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a PTC heater unit provided with a PTC element which comes into contact with a heat sink via an insulating plate.

[0002]

2. Description of the Related Art When a voltage is directly applied to a PTC element,
The temperature rises due to self-heating, the electrical resistance also rises at the same time, the current is limited, the further heating is controlled and the temperature is kept almost constant, and the electric smoke evaporator for insecticide and disease prevention and It is used as a heater unit such as a humidifier.

FIG. 1 is a longitudinal sectional view of a PTC heater unit using a PTC element, and FIG. 2 is an exploded perspective view of the PTC heater unit. The PTC heater unit has two PTC elements 1 provided with electrodes 1a on both surfaces. The conductive inner spring 3 is interposed between the lower surface of the PTC element 1 and the ceramic case 2, and the terminals 3 of the inner spring 3 are arranged at intervals.
a protrudes from the lower part of the ceramic case 2. PTC
An upper surface of the element 1 has an electrode plate 4 having a terminal 4a extending downward.
And the terminal 4 a is projected from the lower part of the ceramic case 2. The electrode plate 4 and the heating plate 5 serving as a receiving tray are brought into contact with each other via an insulating plate 6, and the ceramic case 2 is fixed by a fixing bracket 7.
Is attached to the heating plate 5. As the heating plate 5, a copper or aluminum metal plate having high thermal conductivity is used in order to obtain as large an output as possible.

[0004]

SUMMARY OF THE INVENTION However, PTC
Since the PTC heater unit incorporating the element makes the PTC element as small as possible, when a copper or aluminum heating plate having a high thermal conductivity is used, the surface temperature of the heating plate cannot follow the change in the ambient temperature. In addition, there is a problem that the surface temperature is not constant, and the surface temperature of the heating plate becomes uneven.

An object of the present invention is to provide a PTC heater unit in which the surface temperature of the heating plate follows the change in the ambient temperature, and the surface temperature does not vary.

[0006]

A PTC heater unit according to the present invention is a PTC heater unit having a PTC element that comes into contact with a heating plate via an insulating plate, wherein the thermal conductivity of the heating plate is 100 w / m · K or less. Along with PT
The operating temperature of the C element is set to 200 ° C. or more, and the area of the PTC element is set to 30% or more of the area of the heating plate.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The reason for using a PTC element having an operating temperature (Curie point) of 200 ° C. or higher in the PTC heater unit of the present invention is as follows.
When the thermal conductivity of the heating plate that contacts the heater unit via the insulating plate is set to 100 w / m · K or less, the operating temperature is set to 200 ° C. or more, so that the surface temperature of the metal plate with respect to a change in the ambient temperature is reduced. This is because followability can be ensured.

Further, the heat conductivity of the heating plate which contacts the PTC heater unit having the PTC element via the insulating plate is set to 100 w / m · K or less, and the area of the PTC element is 30% of the area of the heating plate. The above area ratio is
If the thermal conductivity of the heating plate exceeds 100 w / m · K and the area ratio is less than 30%, the surface temperature of the heating plate is greatly reduced due to a large amount of heat radiation when the ambient temperature is reduced, and P
Temperature unevenness occurs between the contact portion and the non-contact portion with the TC element, and the followability of the surface temperature of the metal plate to changes in the ambient temperature is deteriorated.
It does not become the same as the surface temperature of the contact portion with the TC element. On the other hand, if the thermal conductivity of the heating plate is set to 100 w / m · K or less and the area ratio of the PTC element to the area of the heating plate is set to 30% or more, even when the ambient temperature decreases, P
There is almost no drop in the surface temperature of the portion not in contact with the TC element, and the followability of the surface temperature of the metal plate to changes in the ambient temperature is good.

As a PTC element having an operating temperature of 270 ° C. or more, there is a ceramic material of (Ba, Pb) TiO 3, and as a heating plate having a thermal conductivity of 100 w / m · K or less,
Iron-based materials such as stainless steel are preferable, and ceramic materials can also be used.

[0010]

【Example】

Example A stainless steel pan with a diameter of 70 mm and a Curie point of 27
PTC element 2 of 40 mm × 20 mm × 3 mm at 0 ° C.
1 were assembled as shown in FIG. 1 (area ratio: 42
%). When 100 V was applied, the whole output was 30 W at room temperature of 20 ° C. On the other hand, the surface temperature of the saucer was 240 ° C. In this state, the ambient temperature is 20 °
When the temperature was changed from C to 0 ° C, the output changed by 5%, the surface temperature was 240 ° C, the temperature was not uneven, and the same heating temperature was maintained. The ratio with the maximum current was about 1.5 times.

Comparative Example 1 An aluminum pan having a diameter of 70 mm and a 40 mm diameter
Two PTC elements of × 20 mm × 3 mm were assembled as shown in FIG. 1 (area ratio: 42%). When 100 V was applied, the total output was 33 watts at room temperature of 20 ° C.
Surface temperature of the saucer is 240 ° C
20 ° C from the temperature to 220 ° C
Since the output did not change even when the temperature changed from 0 ° C to 0 ° C, the surface temperature also decreased by 10 ° C to 210 ° C. The ratio to the maximum current was about 1.3 times.

Comparative Example 2 A stainless steel pan having a diameter of 70 mm and a 25 mm
A PTC element of φ × 3 mm and two PTC elements were assembled as shown in FIG. 1 (area ratio: 25%). A test similar to the above was performed, but the overall output dropped to 26 w, and the surface temperature of the saucer was 240 ° C. at the highest point. °
There was a place where only C rose. On the other hand, there was a change to the ambient temperature, but only a change of about 2%,
When the surface temperature was changed from 20 ° C to 0 ° C, the surface temperature decreased by 15 ° C from 240 ° C to 225 ° C.
The ratio with the maximum current was three times or more.

[0013]

【The invention's effect】

(1) The PTC heater unit of the present invention has a heating plate with a thermal conductivity of 100 w / m · K or less and a PT
By setting the operating temperature of the C element to 200 ° C. or more and the area of the PTC element to 30% or more with respect to the area of the heating plate, the surface temperature of the heating plate can follow the ambient temperature well. Eliminate temperature unevenness in temperature.

The PTC heater unit of the present invention can use a material such as stainless steel that is not restricted by the environmental atmosphere used.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a PTC heater unit using a PTC element.

FIG. 2 is an exploded perspective view of a PTC heater unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 PTC element 1a Electrode 2 Ceramic case 3 Internal spring 3a Terminal of internal spring 4 Electrode plate 4a Terminal of electrode plate 5 Heating plate 6 Insulating plate 7 Fixing metal

Claims (1)

[Claims] 1. A PTC that contacts a heating plate via an insulating plate.
In the PTC heater unit having the element, the heat conductivity of the heating plate is set to 100 w / m · K or less,
Set the operating temperature of the TC element to 200 ° C or higher, and
P in which the area of the element is 30% or more of the area of the heating plate
TC heater unit.