JPH07282964A - Cartridge heater - Google Patents

Abstract

(57) [Summary] [Objective] To provide a cartridge heater capable of stably exhibiting the self-temperature control function of a positive temperature coefficient thermistor element. [Constitution] The heater includes electrodes 31a, 31 to which terminals 49a, 49b are attached via lead wires 33a, 33b.
b is a positive temperature coefficient thermistor element 35a having a narrower width.
~ 35d (PTC) is inserted into the polyimide tube 37 to form a heat generating portion 39, and the heat generating portion 39 is housed in a metal tube 41 so that heat conduction between the tube 37 and the metal tube 41 can be improved. After filling the powdery powder 45, the plug 5
1 through the insertion holes 59a and 59b, respectively.
It is formed by inserting b and inserting the plug body 51 into the metal tube 41. Further, a vent hole 61 is formed in the plug body 51. Therefore, the outside air flows from the vent hole 61 to the electrode 3
Reach each PTC through the gap between 1a and 31b,
It is possible to prevent the resistance value of C from decreasing due to lack of oxygen.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a cartridge heater.

[0002]

2. Description of the Related Art Conventionally, a positive temperature coefficient thermistor element (hereinafter referred to as "PT
C)) has been developed to provide a cartridge heater having a self-temperature control function (self-protection function) of not exceeding a predetermined temperature.

Conventionally, as a cartridge heater using such a PTC, for example, an actual development 55
As disclosed in Japanese Patent Laid-Open No. 53896/1993, a PTC to which a lead wire is connected is housed in a bottomed metal tube, and the bottomed metal tube is filled with a silicone resin or the like to obtain the PTC.
It has been proposed to ensure insulation and thermal conductivity between the bottomed metal tube and the bottomed metal tube.

[0004]

Here, PTC is a ceramic semiconductor whose main component is barium titanate (BaTiO ₃ ), and when exposed to a reducing gas, it is reduced and conduction electrons are generated inside. Therefore, the conduction electrons have a property that the resistance value does not increase even at a high temperature and the self-temperature control function is impaired.

Even when the PTC is hermetically sealed and brought to a high temperature state, oxygen is not supplied to the PTC, and the PTC becomes in a state similar to a reducing atmosphere. Therefore, in the above-mentioned conventional cartridge heater, since oxygen is not supplied to the PTC,
Not only does the resistance value of the PTC stop increasing at high temperatures, but in the worst case, the PTC may cause a short circuit failure.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a cartridge heater capable of stably exhibiting the self-temperature control function of the PTC.

[0007]

SUMMARY OF THE INVENTION That is, according to the present invention as set forth in claim 1 for achieving the above object, a positive temperature coefficient thermistor element, and a width wider than the positive temperature coefficient thermistor element are formed, An electrode sandwiching the characteristic thermistor, and a heating portion provided with an insulating material which is provided around the surface of the electrode and holds the positive temperature coefficient thermistor element in a sandwiched state,
A bottomed metal tube that accommodates the heat generating portion, a conductive member that is connected to the electrode and is taken out through an opening of the bottomed metal tube, and an insertion hole through which the conductive member is inserted. A stopper for closing the opening of the bottom metal tube,
Further, the gist of a cartridge heater is characterized in that, in addition to the insertion hole, a vent hole that communicates the inside and outside of the bottomed metal tube is formed in the plug body.

According to a second aspect of the present invention, in the cartridge heater according to the first aspect, the heating portion is provided between a plurality of positive temperature coefficient thermistor elements and each of the positive temperature coefficient thermistor elements. And a plurality of electrodes for sequentially sandwiching the respective positive temperature coefficient thermistor elements, and a cartridge heater characterized by the above.

Further, according to a third aspect of the present invention, in the cartridge heater according to the first or second aspect, the cartridge has a plurality of the vent holes formed therein. The main point is the heater.

[0010]

In the cartridge heater according to claim 1 configured as described above, the plug body is provided in the opening of the bottomed metal tube, and the insertion hole of the plug body The conductive member connected to the electrode of the heat generating portion housed in the bottomed metal tube is taken out.

When a current is applied to the electrode of the heat generating portion through the conductive member, the PTC (positive temperature coefficient thermistor element) generates heat, and the heat is transmitted through the electrode and the insulating material provided around the surface of the electrode. Is released from the surface of the bottomed metal tube to the outside world.
Here, in the cartridge heater according to the first aspect of the present invention, since the vent is formed in the plug body so as to communicate the inside and outside of the bottomed metal pipe, outside air can enter the inside of the bottomed metal pipe. Has become.

In addition, since the heat generating portion is formed by sandwiching the PTC between electrodes having a width wider than that of the PTC and surrounding the surface of the electrode with an insulating material, the outside air that has entered through the vent hole of the plug body is prevented. , The PTC can be easily reached through the gap between the electrodes. Therefore, according to the cartridge heater of the first aspect, even if the PTC generates heat, sufficient oxygen can be supplied to the PTC, and the resistance value of the PTC does not increase at a high temperature, and the self-temperature control is performed. It is possible to prevent harmful effects such as impaired function. And PT
It is possible to prevent a failure such as short circuit of C.

According to the cartridge heater of the first aspect, between the bottomed metal tube and the heat generating portion (insulating material),
Even when a filler such as insulating powder having good thermal conductivity is interposed, the insulating material provided around the electrodes prevents the filler from entering the gap between the electrodes. Oxygen that has entered through the ventilation holes of the body is surely PTC
Can be supplied to.

Next, in the cartridge heater according to the second aspect, the heat generating portion includes a plurality of PTCs and the respective PTs.
And a plurality of electrodes which are provided between the Cs and sequentially sandwich the PTCs. Therefore, according to the cartridge heater of the second aspect, more heat can be released as the PTC increases, and the number of gaps between the electrodes sandwiching the PTC also increases. Therefore, the outside air that has entered through the vent holes of the stopper easily circulates in the bottomed metal pipe,
Oxygen can be uniformly supplied to the PTC.

Further, in the cartridge heater described in claim 3, in the cartridge heater described in claim 1 or 2, a plurality of vent holes are formed in the plug body. Therefore, according to the cartridge heater described in claim 3, it becomes possible to supply more oxygen to the PTC in the bottomed metal tube.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. The present invention is not limited to the following embodiments, and includes all embodiments that can be conceived by those skilled in the art without departing from the gist of the present invention.

First, FIG. 1 is a vertical sectional view of a cartridge heater according to an embodiment, and FIG. 2 is a horizontal sectional view taken along the line BB in FIG. As shown in FIGS. 1 and 2, the cartridge heater according to the present embodiment includes electrodes 31a and 31b made of aluminum alloy which also have a heat dissipation function, and the electrodes 31a and 31b.
lead wires 33a and 3 attached to a and 31b, respectively
3b and the P for heat generation sandwiched between the electrodes 31a and 31b
TC35a, 35b, 35c, 35d and a thermoplastic polyimide having high insulation and thermal conductivity are formed into a bottomed tube shape, and the electrodes 31a, 31b are PTC35a-.
A polyimide tube 37 as an insulating material inserted while sandwiching 35d, and a bottomed metal tube (hereinafter, simply referred to as a metal tube) 41 as a cartridge for accommodating a columnar heat generating section 39 made of the above-mentioned members, Bottom part 4 of metal tube 41
1a, a ceramic plate 43 having a recess 43a into which the bottom of the polyimide tube 37 is fitted, and a boron nitride powder filled in a gap between the outer surface of the polyimide tube 37 and the inner peripheral surface of the metal tube 41. Heat conduction powder 45
And a silicone seal 47 filled so that the heat conductive powder 45 does not leak from the metal tube 41, and the lead wires 33a, 3
3b and electrode terminals 49a and 49b as conductive members which are connected to respective ends of the metal tube 41 and are taken out from the opening 41b of the metal tube 41 and connected to a power supply line (not shown), and the electrode terminals 49a and 49b are inserted therethrough. It is composed of an insulative plug body 51 for closing the opening 41b of the metal tube 41 and a mounting screw plug 53 welded to the outer periphery of the metal tube 41 near the opening 41b.

Here, the metal tube 41 is formed in a bottomed cylindrical shape, and is made of a material having excellent thermal conductivity and rollability, for example, stainless steel (SUS316L or the like). The electrodes 31a and 31b have the same shape,
Made of an aluminum alloy having a diameter of about 2/3 of the inner diameter of the metal tube 41 and about 2/3 of the length of the metal tube 41 (for example, JI
A metal column of S standard 6063-T4) is formed by being divided into two substantially in the axial direction, and its cross section has a substantially semicircular shape. Then, as shown in FIG.
The widths of a and 31b are formed to be slightly wider than the widths of the PTCs 35a to 35d, and grooves 55 for inserting the lead wires 33a and 33b are formed on the outer peripheral surfaces of the curved surfaces thereof, respectively.
a and 55b are formed to reach both ends in a direction orthogonal to the arc direction of the curved surface. In addition, each electrode 31a, 31b
PTCs 35a to 35 are provided on the outer peripheral surfaces of the flat surfaces, respectively.
The shallow grooves 57a and 57b for positioning by sandwiching d are
It is formed in the axial direction. In addition, each such electrode 3
1a and 31b are formed by casting to form the grooves 55a, 55b and 5
7a and 57b are preliminarily provided.

On the other hand, the PTCs 35a to 35d are ceramic semiconductors formed by mixing a small amount of yttrium or the like with barium titanate and sintering it, and are heat generating materials whose resistance suddenly increases when the temperature exceeds a predetermined temperature. That is, a general thermistor whose resistance value decreases as the temperature rises is referred to as a negative characteristic thermistor, whereas it is a positive characteristic thermistor and is a heating material having its own temperature control function.

The PTCs 35a to 35d are connected to the electrode 3
It is formed in a rectangular plate shape having a length shorter than the lengths of 1a and 31b and a width narrower than the length of the diameter of the arc of the electrodes 31a and 31b as shown in FIG. In addition, the PTC 3 contacting each of the electrodes 31a and 31b
Each surface of 5a to 35d is coated with a metal having a high conductivity, such as silver, to prevent an increase in contact resistance between them and to prevent joules in contact portions between the electrodes 31a and 31b and the PTCs 35a to 35d. Prevents heat generation.
As the PTCs 35a to 35d, for example, PTC thermistor elements manufactured by Murata Manufacturing Co., Ltd. are used.

The inner diameter of the polyimide tube 37 is
The electrodes 31a and 31b are formed to have substantially the same outer shape as the PTCs 35a to 35b are sandwiched. On the other hand, each of the electrode terminals 49a and 49b is made of metal and formed into a rod shape, and the end portions on the side connected to the lead wires 33a and 33b are formed into a tubular shape. That is, the end portions of the lead wires 33a and 33b are inserted into the tubular end portions and crimped, so that the lead wires 33a and 33b can be electrically connected. The lead wires 33a and 33b are made of nickel alloy.

Then, such electrode terminals 49a, 4
The plug 51 for inserting 9b to close the opening 41b of the metal tube 41 is made of an insulating elastic material such as silicone rubber, and as shown in FIG. It has a cylindrical shape with an outer diameter, and is provided with a flange portion 51a larger than the inner diameter of the metal tube 41 at its end. 3A and 3B show the appearance of the plug body 51. FIG. 3A is a plan view thereof and FIG. 3B is a side view thereof.

Then, as shown in FIG. 3 (A), the plug 5
1 is formed with insertion holes 59a and 59b through which the electrode terminals 49a and 49b are inserted, respectively.
A vent hole 61 is formed in the axial direction of the central position of 59b, that is, the center of the plug 51.

Next, the procedure for manufacturing such a cartridge heater of this embodiment will be described with reference to FIG. First, one ends of the lead wires 33a and 33b are connected to one ends of the electrode terminals 49a and 49b (not shown in FIG. 4) by crimping. Then, as shown in FIG. 4, the other end of each lead wire 33a, 33b is connected to each electrode 31
The lead wires 33a and 33b are attached to the electrodes 31a and 31b by inserting them into the grooves 55a and 55b of a and 31b and applying external force to the electrodes 31a and 31b.

Next, the shallow groove 57 of each electrode 31a, 31b is formed.
The PTCs 35a to 35b are aligned and positioned on a and 57b, and the columnar body thus formed is inserted to the bottom of the polyimide tube 37 to form a cylindrical heating portion 39.
To form. On the other hand, as shown in FIG.
The ceramic plate 43 is placed on the bottom portion 41a of the metal plate 1, and the screw plug 53 is attached to the outer peripheral surface of the metal tube 41 near the opening portion 41b. The screw plug 53 is attached by welding the edge portion of the screw plug 53 to the outer peripheral surface of the metal tube 41.

Then, after the heating portion 39 formed as described above is inserted into the metal tube 41 through the opening portion 41b,
The gap between the metal tube 41 and the polyimide tube 37 is filled with the heat conductive powder 45 to a predetermined position. Then, the silicone seal 47 is injected from the opening 41b so that the filled thermal conductive powder 45 does not leak.

Thereafter, pressure is applied from the outer circumference of the metal pipe 41 toward the axial direction on the bottom portion 41a side of the portion where the screw plug 53 is welded to the metal pipe 41 to compress and reduce the diameter of the metal pipe 41. Then, since the heat conduction powder 45 is compacted in the metal tube 41 by this diameter reduction, the electrodes 31a, 31b and the like are firmly fixed, and the PTCs 35a-35d and the electrodes 31a, 31b are brought into contact with each other due to the displacement of the PTCs 35a-35d. In addition to preventing defects, the heat generated by the PTCs 35a to 35d is efficiently conducted to the metal tube 41.

After performing such compression reduction,
As shown in FIG. 1, the electrode terminals 49a and 49b are respectively inserted into the two insertion holes 59a and 59b formed in the plug body 51, and the plug body 51 is inserted into the metal pipe 41 from the opening 41b.
The flange portion 51a is inserted to a position where it comes into contact with the end portion of the metal pipe 41. And after that, the opening 41b of the metal pipe 41
Pressure is applied from the outer circumference in the axial direction to the opening 4
The inner diameter of the metal tube 41 near 1b is reduced.

Then, the inner peripheral surface of the metal tube 41 comes into close contact with the outer peripheral surface of the plug body 51, and the insertion holes 59a, 5 of the plug body 51 are formed.
The inner peripheral surface of 9b comes into close contact with the outer peripheral surfaces of the electrode terminals 49a and 49b. As a result, each electrode terminal 49
The opening 41b of the metal tube 41 is closed with the a and 49b protruding outward, and the cartridge heater of this embodiment is completed.

In the cartridge heater of this embodiment having such a structure, when each electrode terminal 49a, 49b is connected to the power supply line, the P sandwiched by each electrode 31a, 31b is formed.
An electric current flows through the TCs 35a to 35d to generate heat. And
The heat is transmitted to the metal tube 41 through the electrodes 31a and 31b, the polyimide tube 37, and the heat conductive powder 45, and is radiated from the surface of the metal tube 41 to the outside. And
Due to the characteristics of the PTCs 35a to 35d, when the temperature reaches a predetermined temperature, the resistance value suddenly increases and the amount of flowing current decreases, so that the entire cartridge heater does not overheat.

Here, in the cartridge heater of the present embodiment, in addition to the insertion holes 59a and 59b into which the electrode terminals 49a and 49b are inserted, the vent hole 61 that communicates the inside and outside of the metal tube 41 is formed in the plug body 51. Metal tube 4 because it is formed
Outside air can enter the inside of 1.

Moreover, the columnar body formed by sandwiching the PTCs 35a to 35d between the electrodes 31a and 31b having a wider width is inserted into the polyimide tube 37 to form the heat generating portion 39, and the heat generating portion 39 is connected to the metal tube. Since it is housed in 41, the outside air that has entered the metal tube 41 through the vent hole 61 of the plug 51 can easily be discharged from the gap S between the electrodes 31a and 31b formed as shown in FIG.
5a to 35d will be reached.

Therefore, according to the cartridge heater of this embodiment, even if the PTCs 35a to 35d generate heat, the PTC3
It becomes possible to supply sufficient oxygen to 5a to 35d, and it is possible to prevent such a problem that the resistance value of the PTCs 35a to 35d does not increase at a high temperature and the self-temperature control function is impaired. And PTC35a-3
It is possible to prevent a failure such as short-circuiting of 5d.

Further, according to the cartridge heater of the present embodiment, the metal tube 41 and the heat generating portion 39 (polyimide tube 3
Although the heat conducting powder 45 is interposed between the heat conducting powder 45 and the electrode 7a), the heat conducting powder 45 is prevented by the polyimide tube 37 surrounding the electrodes 31a, 31b.
Since it is prevented from entering the gap S between the 1b, the oxygen entering from the vent hole 61 of the plug body 51 is surely removed from the PTC3.
5a to 35d can be supplied.

On the other hand, according to the cartridge heater of this embodiment, the heat conduction powder 4 is formed by the polyimide tube 37.
5 is a contact surface between the electrodes 31a and 31b and the PTCs 35a to 35d, that is, a shallow groove 57 formed in the electrodes 31a and 31b.
a, 57b are prevented from entering the electrodes 31a, 3b.
It is possible to prevent the heat dissipation efficiency from being deteriorated due to the decrease in the contact property between the 1b and the PTCs 35a to 35d.

Further, in the cartridge heater of this embodiment, the electrodes 31a and 31b and the metal tube 41 are pre-insulated by the polyimide tube 37. Therefore, the material of the heat conductive powder 45 is a heat conductive material. Only good ones will be enough. That is, in this embodiment, the boron nitride powder is used as the heat conductive powder 45, but it is possible to use a metal powder such as copper or aluminum. Then, for example, when copper powder is used as the heat conductive powder 45, there is an advantage that the heat conductivity is better and the cost is lower than that of the boron nitride powder.

Furthermore, in the cartridge heater of this embodiment, a polyimide tube 37 made of thermoplastic polyimide is used as an insulating material that is provided around the surfaces of the electrodes 31a and 31b. Therefore, according to the cartridge heater of the present embodiment, there is no fear of cracks in the polyimide tube 37 due to stress when the metal tube 41 is reduced in diameter and compressed.

In the cartridge heater of the above embodiment, four PTCs 35 are provided between the electrodes 31a and 31b.
Although a to 35d are arranged in a column, the number can be appropriately set according to the length of the heat generating portion of the cartridge heater and the length of each PTC. Further, in the cartridge heater of the above embodiment, the shallow grooves 57a and 57b for positioning the PTCs 35a to 35d are formed on the flat side surfaces of the electrodes 31a and 31b.
The PTCs 35a to 35d may be sandwiched without forming the a and 57b.

On the other hand, in the cartridge heater of the above-described embodiment, one set of electrodes 31a and 31b is used to form one row of PTC 35a.
35d was sandwiched between the electrodes and PTC
Can be set to any number, for example, as shown in FIG. 5, four electrodes 131a, 131b, 131c, 131
d, four PTCs 135a, 135b, 135c, 1
The 35d may be sequentially sandwiched. In FIG. 5, reference numerals 133a, 133b, 133c, 133d denote lead wires attached to the electrodes 131a to 131d, respectively, and 155a, 155b, 155c, 155d are
Grooves for fixing the lead wires 133a to 133d are shown, respectively.

In this case, as shown in FIG. 6 (A), the plug 1 for closing the opening 41b of the metal tube 41.
In the 51, four insertion holes 159a to 159d may be formed corresponding to the electrode terminals (not shown) connected to the four lead wires 133a to 133d, respectively. Incidentally, FIG.
In (A), reference numeral 161 is the same vent hole as the vent hole 61 shown in FIG.

According to the cartridge heater thus constructed, more heat can be released as PTC increases, and as shown in FIG.
The number of gaps between the electrodes sandwiching C also increases. Therefore, the outside air that has entered through the vent holes 161 of the plug 151 can easily circulate in the metal tube 41, and the PTCs 135a to 135d can be easily circulated.
Oxygen can be uniformly supplied to the.

Further, as in the above-mentioned respective embodiments, the plug 5
The number of vent holes 61, 161 formed in 1, 151 is not limited to one, and as shown in FIG.
In addition, four ventilation holes 162a to 162d may be additionally provided. Then, by increasing the number of vent holes in this manner, it becomes possible to supply more oxygen to the PTC in the metal tube 41.

On the other hand, in the cartridge heater of the above embodiment, the metal tube 41 has a bottomed cylindrical shape, but a fin for heat radiation may be attached to the outer periphery of the metal tube 41 after compression and diameter reduction. The metal tube 41 is not limited to the cylindrical shape,
For example, a triangular prism shape, a quadrangular prism shape, or a cylindrical shape having an elliptical cross section may be used.

In the cartridge heater of the above embodiment, the lead wires 33a, 3 to the electrodes 31a, 31b are also provided.
3b is attached to the grooves 55a and 55b by the lead wire 33.
Although it was performed by inserting and crimping a and 33b, instead of crimping, use various connecting means capable of ensuring conductivity between the electrodes 31a and 31b and the lead wires 33a and 33b. You can

Furthermore, in the cartridge heater of the above-mentioned embodiment, the bottomed tubular polyimide tube 37 is used as the insulating material for insulating the electrodes 31a and 31b from the metal tube 41. However, the present invention is not limited to this, and for example, an insulating sheet formed in a sheet shape may be wound around the electrodes 31a and 31b.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a cartridge heater of an embodiment.

FIG. 2 is a cross-sectional view showing a cartridge heater according to an embodiment.

FIG. 3 is an external view of a plug body in the cartridge heater of the embodiment.

FIG. 4 is an explanatory diagram illustrating a manufacturing procedure of the cartridge heater of the embodiment.

FIG. 5 is a cross-sectional view showing a cross section of a cartridge heater of another embodiment.

FIG. 6 is an external view of a plug body in a cartridge heater of another embodiment.

[Explanation of symbols]

31a, 31b, 131a-131d ... Electrodes 35a-35d, 135a-135d ... Positive characteristic thermistor element (PTC) 37 ... Polyimide tube 39 ... Exothermic part 4
1 ... Bottomed metal tube 41b ... Opening 45 ... Thermal conductive powder 49a, 4
9b ... Electrode terminals 51, 151 ... Stoppers 59a, 59b, 159a-1
59d ... Insertion hole 61, 161, 162a-162d ... Vent hole S ...
gap

Claims (3)

[Claims] 1. A positive temperature coefficient thermistor element, electrodes having a width wider than that of the positive temperature coefficient thermistor element and sandwiching the positive temperature coefficient thermistor, and the positive temperature coefficient thermistor element surrounding the surface of the electrode. A heat generating part provided with an insulating material for holding the heat generating part in a sandwiched state, a bottomed metal tube accommodating the heat generating part, and a conductive member connected to the electrode and taken out from an opening of the bottomed metal tube to the outside. A plug body that has an insertion hole through which the conductive member is inserted, and that closes the opening of the bottomed metal pipe, and further comprises a plug body for the bottomed metal pipe separate from the insertion hole. A cartridge heater characterized in that a vent hole is formed to communicate the inside and the outside. 2. The cartridge heater according to claim 1, wherein the heat generating portion is provided between a plurality of positive temperature coefficient thermistor elements and each of the positive temperature coefficient thermistor elements, and sequentially sandwiches the positive temperature coefficient thermistor elements. And a plurality of electrodes for controlling the cartridge heater. 3. The cartridge heater according to claim 1, wherein a plurality of the vent holes are formed in the plug body.