JPH09293581A - Positive thermistor heating element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance reliability in current carrying by stacking heater units in the height direction, housing in a frame body together with an elastic body, and pressure-welding a heat radiating body of the heater unit and a heater core with the elastic body so as to closely come in contact each other. SOLUTION: A plurality of positive thermistors 1 are arranged in a flat state, and an electrode plate 2 is fixed to both main surfaces with a conductive adhesive 3 to form a heater core. The electrode plate 2 is extended from the end part of the heater core so as to project to the outside of a frame body 5. A meandering heat radiating body 4 is brought into contact with the upper and lower surfaces of the heater core to form a heater unit. The heater units are stacked, a plate spring 6 is overlapped on the uppermost part, and they are housed in the frame body 5, and the heater core and the heat radiating body 4 are pressure-welded with the plate spring 6 so as to closely come in contact each other to form a positive characteristic thermistor heat generating element. Electric power is supplied from the electrode plate 2 bonded to the positive thermistor 1, the contact part of the heater core and the heat radiating body 4 is only heat conduction, and thereby, stable heat generating state is maintained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a PTC thermistor heating element for heating a fluid such as air such as a warm air heater.

[0002]

2. Description of the Related Art Since a positive temperature coefficient thermistor is a semiconductor ceramic whose resistance value rises rapidly at a certain temperature, it has a self-temperature control action. When a voltage is applied to it and it is used as a heating element, its surface temperature rises. It is generally well known that it is a convenient heating element because it does not change much and does not overheat. Further, when this heating element is used as a heater for heating a fluid such as air, it does not glow red even when the passage of the fluid is stopped, and can be used as a safe heater. In order to increase the input power of the heating element and increase the amount of heat generation, the effect is enhanced by bringing the radiator into close contact with the PTC thermistor and further increasing the surface area of the radiator. The conventional PTC thermistor heating element has the following structure. That is, the heater core is formed by accommodating a plurality of positive temperature coefficient thermistors in a planar shape in a frame. Then, a radiator is brought into contact with both main planes of the PTC thermistor in the heater core to form a heater unit. Then, a plurality of these heater units are stacked and housed in a frame, and a leaf spring is inserted in the gap between the uppermost heater unit and the frame, and the heater core and the radiator are pressure-contacted in a dot shape to form the positive temperature coefficient thermistor heating element. I was making up.

When a voltage is applied to the PTC thermistor via the radiator of the PTC thermistor heating element having the above structure, the PTC thermistor generates heat. The generated heat is transmitted to the radiator, and if a fluid such as air is applied to the radiator from one direction, warm air can be obtained from the opposite side.

[0004]

However, in the above-mentioned conventional configuration, since the current is supplied to the positive temperature coefficient thermistor through the heat radiator which is pressed into contact with the spot, when the leaf spring is thermally deteriorated, the heat radiator and the positive temperature coefficient thermistor are deteriorated. However, there is a problem in that the pressure contact force of is weakened and the reliability against energization is reduced.

The present invention has been made to solve the above-mentioned problems, and an object thereof is to provide a highly reliable positive temperature coefficient thermistor heating element.

[0006]

To achieve this object, a positive temperature coefficient thermistor heating element of the present invention has a heater core in which electrode plates for electric input are fixed to both main planes of a plurality of positive temperature coefficient thermistors with an adhesive. A plurality of heater units, each of which has a heat radiator in contact with its main plane, are stacked in the height direction and housed in a frame together with an elastic body. With this elastic body, the heat radiator and the heater core of each heater unit are pressed together. It has a structure.

With this configuration, the voltage is applied to the positive temperature coefficient thermistor not from the point contact portion with the heat radiator but from the electrode plate bonded and fixed to the surface, so that a highly reliable positive temperature coefficient thermistor heating element can be obtained. To be

[0008]

A positive temperature coefficient thermistor heating element according to a first aspect of the present invention comprises a plurality of positive temperature coefficient thermistors each having electrodes formed on both main planes arranged in a planar shape. A heater unit is formed by a heater core in which an electrode plate for electric input is fixed on a flat surface with an adhesive and a heat radiator that is in contact with both main planes of the heater core, and a plurality of heater units are stacked in the height direction to form a frame body. Further, an elastic body is inserted in the gap between the uppermost heater unit and the frame body, and the heat radiator and the heater core of each heater unit are brought into pressure contact with each other by this elastic body. Since the heat is dissipated from the electrode plate fixed to the positive temperature coefficient thermistor and the generated heat is dissipated from the heat radiator, even if the pressure is reduced due to the thermal deterioration of the elastic body, stable power is supplied to the positive temperature coefficient thermistor. Supply becomes possible, and high reliability.

The invention according to claim 2 of the present invention uses a plate spring made of stainless steel for the elastic body, and has excellent heat resistance and less thermal deterioration.

According to a third aspect of the present invention, a thin plate insulator having excellent thermal conductivity is inserted in a contact portion between the heater core and the radiator, so that the heater core contacts the heater core when energized. This is to prevent electrical conduction even if the upper and lower radiators are short-circuited.

According to a fourth aspect of the present invention, the insulator inserted between the heater core and the radiator is an alumina-based porcelain, which can be easily obtained industrially, and the insulation and the heat conduction can be improved. It has excellent sexuality.

(First Embodiment) A positive temperature coefficient thermistor heating element in an embodiment of the present invention will be described below with reference to FIG.

FIG. 1 is a perspective view of a PTC thermistor heating element according to an embodiment of the present invention. In FIG. 1, 1 is a PTC thermistor, 2 is an electrode plate, 3 is an adhesive, 4 is a radiator, and 5 is a heat sink. Is a frame, and 6 is a leaf spring.

In the above-mentioned components, first, four positive temperature coefficient thermistors 1 adjusted to obtain an output of 100 W with one element at the time of heat generation at a switching temperature of 220 ° C. are arranged in a plane, and aluminum is formed on both main planes thereof. The electrode plate 2 made of the above material was fixed with a conductive adhesive 3 to form a 400 W heater core. At this time, since the electrode plate 2 also serves as a conductive path, the electrode plate 2 is extended from the end portion of the heater core in different directions in the upper and lower surfaces so as to protrude to the outside of the frame body 5 made of a heat resistant resin. After a meandering radiator 4 made of aluminum is brought into contact with the upper and lower surfaces of the heater core to form a heater unit, the heater units are stacked in three stages, and a leaf spring 6 made of stainless steel is placed on the uppermost part of the heater unit in the frame body 5. It was inserted and housed so that the heater core and the radiator 4 were pressed against each other by the leaf spring 6 to form a 1200 W positive temperature coefficient thermistor heating element.

The operating principle of the PTC thermistor heating element constructed as described above will be described below.

When a voltage of 100 V is applied to each electrode plate 2, a voltage is applied to the PTC thermistor 1 and the PTC thermistor 1 generates heat. The generated heat is transmitted to the heat-dissipating body 4 that is pressed against it, and when air is passed through it, warm air can be obtained. At this time, the radiator 4 of the PTC thermistor heating element is heated to a temperature of about 140 ° C. When the leaf spring 6 which receives this heat is repeatedly used for a long time, the spring property gradually deteriorates and the pressing force decreases, but the positive temperature coefficient thermistor heating element of the present invention supplies power to the positive temperature coefficient thermistor 1. Since it is performed from the bonded electrode plate 2 and the contact portion between the heater core and the radiator 4 is only for heat conduction, the pressing force of the plate spring 6 is reduced and the positive temperature coefficient thermistor 1 and the electrode plate 2 as in the conventional example. It is possible to maintain a stable heat generation state without increasing contact resistance with.

(Embodiment 2) A heater unit is formed by inserting a grid-shaped insulator made of alumina-based porcelain into the contact portion between the electrode plate 2 and the radiator 4 of the heater core having the structure of Embodiment 1. In the same manner as in the first embodiment, the 1200 W positive temperature coefficient thermistor heating element was housed in the frame 5.

In the PTC thermistor heating element having the above-described structure, since the electric power is supplied to the PTC thermistor 1 from the electrode plate 2, even if an insulator is inserted between the heater core and the radiator 4, it is used as a heating element. Since the inserted insulator made of alumina-based porcelain has high electrical insulation and excellent thermal conductivity, the generated heat of the heater core is transmitted to the radiator 4 without any loss. The function of the characteristic thermistor heating element is not impaired. Further, even if a foreign substance is inserted from the outside during energization and the upper and lower radiators 4 are short-circuited, they are not electrically short-circuited and a safe positive temperature coefficient thermistor heating element can be provided.

In Embodiments 1 and 2 of the present invention, the positive temperature coefficient thermistor 1 having a switching temperature of 220.degree.
Although the heater unit of 00W was formed and used at 100V, the switching temperature and the operating voltage can be changed according to the required specifications. Further, although the alumina insulator is inserted between the heater core and the radiator 4 in the second embodiment, the radiator 4 is an electrical insulator instead of the insulator and has excellent thermal conductivity. However, the same effect can be obtained.

[0020]

As described above, according to the present invention, electric power is supplied to the positive temperature coefficient thermistor through the electrode plate fixed to the positive temperature coefficient thermistor. It is possible to provide a positive temperature coefficient thermistor heating element having high properties.

[Brief description of drawings]

FIG. 1 is a perspective view of a PTC thermistor heating element according to an embodiment of the present invention.

[Explanation of symbols]

 1 Positive Characteristic Thermistor 2 Electrode Plate 3 Adhesive 4 Heat Dissipator 5 Frame 6 Plate Spring

Claims (4)

[Claims] 1. A heater core in which a plurality of positive temperature coefficient thermistors having electrodes formed on both main planes are arranged in a plane and electrode plates for electric input are fixed to both main planes of the positive temperature coefficient thermistor with an adhesive. A heater unit is formed by a radiator that is in contact with both main planes of the heater core, a plurality of the heater units are stacked in the height direction and housed in a frame body, and further elastic in the gap between the uppermost heater unit and the frame body. A positive temperature coefficient thermistor heating element characterized in that a body is fitted and a heat radiating body and a heater core of each heater unit are brought into pressure contact with each other by this elastic body. 2. The positive temperature coefficient thermistor heating element according to claim 1, wherein the elastic body is a leaf spring made of stainless steel. 3. A thin plate insulator having excellent thermal conductivity is inserted in a contact portion between the heater core and the radiator.
The positive temperature coefficient thermistor heating element described in. 4. The insulator is an alumina-based porcelain.
The positive temperature coefficient thermistor heating element described.