JP6437865B2 - heater - Google Patents

Description

  The present invention relates to a heater.

  As a heater used in a gas range, an in-vehicle heating device, an oil fan heater, a glow plug of an automobile engine, or the like, a heater in which a heating element is provided inside a ceramic body is known. An example of the heater is a ceramic heater disclosed in Patent Document 1.

  The heater disclosed in Patent Document 1 includes a cylindrical ceramic body, a heating resistor embedded in the ceramic body, and an energization cutoff mechanism (temperature fuse) connected to the heating resistor. Therefore, the heater can cut off the power supply to the heating resistor when the temperature rises due to, for example, emptying.

Japanese Patent Laid-Open No. 9-289073

  However, in the heater described in Patent Document 1, when the heater is used to rapidly raise the temperature, even if an abnormality such as emptying occurs, the operation of the thermal fuse is delayed and the heater is damaged. There was a fear.

A heater according to one aspect of the present invention includes a rod-shaped ceramic body, a heating resistor embedded at least on a front end side of the ceramic body, and the heating resistor fitted to a rear end side of the ceramic body. A metal cylinder electrically connected to the metal cylinder, the metal cylinder having an extending portion extending rearward from the rear end surface of the ceramic body, and an inner peripheral surface of the extending portion. A part of the thermal fuse is provided on the side , and the extending portion is thick so that at least a part of the rear end surface side of the ceramic body increases in thickness toward the inner peripheral surface side, and the ceramic body The rear end surface is in contact with the end surface of the extending portion .

  According to the heater based on one aspect of the present invention, heat can be quickly transferred from the ceramic body to the thermal fuse via the metal cylinder by providing the above configuration. Therefore, the thermal fuse can be operated quickly.

It is sectional drawing which shows the heater concerning one Embodiment of this invention. It is a perspective view of the heater shown in FIG. FIG. 2 is a partially transparent perspective view of the heater shown in FIG. 1. It is a perspective view which shows a ceramic body among the heaters shown in FIG. FIG. 2 is a partially transparent perspective view showing a metal cylinder in the heater shown in FIG. 1. It is a perspective view which shows a temperature fuse among the heaters shown in FIG. FIG. 2 is a partially transparent perspective view showing a metal case in the heater shown in FIG. 1.

As shown in FIG. 1, the heater 10 of this embodiment includes a rod-shaped ceramic body 1, a heating resistor 2 embedded in the ceramic body 1, and a metal cylinder 3 electrically connected to the heating resistor 2. And a thermal fuse 4 attached to the metal cylinder 3. The heater 10 of this embodiment includes a metal case 5 that covers a part of the ceramic body 1, the metal tube 3, and the thermal fuse 4. The heater 10 is used for, for example, a gas range, an in-vehicle heating device, an oil fan heater 10 or a glow plug.

<Ceramic body 1>
The ceramic body 1 is a member in which the heating resistor 2 is embedded. The ceramic body 1 has, for example, a rod shape. Examples of the rod shape include a columnar shape and a quadrangular prism shape. The ceramic body 1 is made of an electrically insulating ceramic such as insulating ceramic, nitride ceramic, or carbide ceramic. Specifically, the ceramic body 1 is made of alumina ceramic, silicon nitride ceramic, aluminum nitride ceramic, silicon carbide ceramic, or the like.

The ceramic body 1 made of silicon nitride ceramic can be obtained by the following method. Specifically, for example, 5 to 15% by mass of a rare earth element oxide such as Y ₂ O ₃ , Yb ₂ O ₃ or Er ₂ O ₃ as a sintering aid with respect to silicon nitride as a main component; the amount of SiO ₂ contained in the _Al 2 _{O 3} and sintering of 5-5% by weight amount such that 1.5 to 5 wt% is mixed SiO ₂ that has been adjusted. And the ceramic body 1 which consists of silicon nitride ceramics can be obtained by baking at the temperature of 1650-1780 degreeC after shape | molding in a predetermined shape. For the firing, for example, hot press firing can be used.

  When the shape of the ceramic body 1 is a rod shape, more specifically, when the shape is a quadrangular prism shape, the length of the ceramic body 1 is set to 20 to 100 mm, for example. Moreover, the cross section of the ceramic body 1 is set to a square having a thickness of 1 to 6 mm and a width of 2 to 40 mm, for example.

<Heat-generating resistor 2>
The heating resistor 2 is a member that generates heat when a voltage is applied thereto. The heating resistor 2 is embedded at least on the tip side of the ceramic body 1. When a voltage is applied to the heating resistor 2, a current flows and the heating resistor 2 generates heat. The heat generated by this heat generation is transmitted through the inside of the ceramic body 1, and the surface of the ceramic body 1 becomes high temperature. And a to-be-heated material can be heated when heat | fever transfers with respect to a to-be-heated material from the surface of the ceramic body 1. FIG. Examples of the object to be heated include light oil supplied to the interior of an automobile diesel engine, water for warm water heating, and the like.

  The heating resistor 2 has a folded portion on the tip side of the ceramic body 1, and both ends are drawn out to the side surface of the ceramic body 1. The heating resistor 2 drawn out to the side surface of the ceramic body 1 is connected to an electrode pattern 21 drawn around in the circumferential direction of the ceramic body 1 as shown in FIGS. In addition, in the heater 10 of this embodiment, the electrode pattern 21 is provided over the perimeter. 2 and 3, the metal case 5 is omitted.

  The heating resistor 2 contains, for example, a carbide such as tungsten (W), molybdenum (Mo), or titanium (Ti), nitride, silicide, or the like as a main component. When the ceramic body 1 is made of silicon nitride ceramic, it is preferable that the main component of the heating resistor 2 is made of tungsten carbide. Thereby, the thermal expansion coefficient of the ceramic body 1 and the thermal expansion coefficient of the heating resistor 2 can be brought close to each other.

<Metal cylinder 3>
The metal cylinder 3 is a member for transferring the heat of the ceramic body 1 to the thermal fuse 4. Also,
The metal cylinder 3 also has a role of electrically connecting one end of the heating resistor 2 and the thermal fuse 4. As shown in FIGS. 1 to 3, the metal cylinder 3 is fitted to the rear end side of the ceramic body 1 and is electrically connected to the heating resistor 2 via the electrode pattern 21. The metal cylinder 3 has an extending portion 32 extending rearward from the rear end surface of the ceramic body 1.

  In the heater 10 of the present embodiment, as shown in FIG. 5, the metal cylinder 3 includes a ceramic body holding portion 31, an extending portion 32, and a thermal fuse holding portion 33. The ceramic body holding part 31 is located on the tip side of the metal cylinder 3. The ceramic body holding portion 31 has an inner peripheral shape and size that match the outer peripheral shape and size of the ceramic body 1 so that the ceramic body 1 can be fitted. In this embodiment, the ceramic body holding part 31 is cylindrical corresponding to the ceramic body 1 having a columnar shape. Further, the thermal fuse holding part 33 is located on the rear end side of the metal cylinder 3. The shape and size of the inner circumference of the thermal fuse holding portion 33 matches the shape and size of the outer circumference of the thermal fuse 4 so that the thermal fuse 4 can be fitted. In the present embodiment, the thermal fuse holding portion 33 is cylindrical, corresponding to the thermal fuse 4 being cylindrical.

  The extending portion 32 is positioned so as to connect the ceramic body holding portion 31 and the thermal fuse holding portion 33. The outer peripheral surface of the extending portion 32 is continuous with the outer peripheral surface of the ceramic body holding portion 31 and the outer peripheral surface of the thermal fuse holding portion 33. The extending portion 32 is thick so that the thickness increases toward the inner peripheral surface. The ceramic body 1 is provided so that the ceramic body 1 is applied to the portion where the thickness is increased. Similarly, the thermal fuse 4 is provided so as to attach the thermal fuse 4 to the thickened portion. Further, the surface of the portion where the thickness is increased is a flat surface. And on this flat surface, the electrical connection between the thermal fuse 4 and the metal cylinder 3 is performed.

  The metal cylinder 3 is preferably made of a metal that can withstand a high temperature environment. Specifically, SUS430 or the like can be used. The metal cylinder 3 is formed by pressing or cutting. The metal cylinder 3 may be subjected to surface processing such as nickel boron plating.

<Thermal fuse 4>
The thermal fuse 4 is a member for interrupting the flow of current when abnormal heat generation occurs. The thermal fuse 4 is a rod-shaped member as shown in FIG. 6, and is inserted and attached to the metal tube 3 as shown in FIGS. A part of the thermal fuse 4 is provided in the extending portion 32 of the metal cylinder 3. More specifically, the connecting portion at the tip of the thermal fuse 4 is connected to the extending portion 32 of the metal cylinder 3. The thermal fuse 4 has a tip connecting portion joined to the extending portion 32 of the metal tube 3 by welding or the like. As welding, for example, spot welding can be used.

<Metal case 5>
The metal case 5 is a member for protecting the metal cylinder 3 and the thermal fuse 4. The metal case 5 also has a role of electrically connecting the other end of the heating resistor 2 and an external power source. As shown in FIG. 7, the metal case 5 is a cylindrical member. In the present embodiment, the metal case 5 is a cylindrical member. As shown in FIGS. 1 and 7, the metal case 5 has a reduced diameter portion 51 whose inner diameter is smaller than the inner diameter of other portions on the distal end side, and the reduced diameter portion 51 is a ceramic body. One electrode pattern 21 is electrically connected. The metal case 5 is made of, for example, a metal having excellent heat resistance such as stainless steel, heat resistant steel, Fe—Ni—Cr alloy or nickel alloy. In addition, a gap is formed between the inner peripheral surface of the metal case 5 other than the reduced diameter portion 51 and the outer peripheral surface of the metal tube 3, whereby the metal case 5 and the metal tube 3 are electrically connected. Is electrically insulated.

  In the heater 10 of the present embodiment, the metal cylinder 3 has an extending portion 32 that extends rearward from the rear end surface of the ceramic body 1, and a portion of the thermal fuse 4 is provided in the extending portion 32. ing. As a result, heat can be transferred from the ceramic body 1 to the thermal fuse 4 through the metal cylinder 3 satisfactorily. Therefore, when the ceramic body 1 reaches an abnormally high temperature, the current flowing through the heating resistor 2 can be cut off immediately by operating the thermal fuse 4. As a result, the reliability of the heater 10 can be improved.

  Further, since a part of the thermal fuse 4 is provided on the inner peripheral surface side of the extending portion 32, the ceramic body 1 and the ceramic fuse 1 are compared with the case where the thermal fuse 4 is provided outside the outer peripheral surface. The thermal fuse 4 can be arranged nearby. As a result, heat can be more easily transferred to the thermal fuse 4.

  Further, the extending portion 32 is thick so that at least a part of the rear end surface side is increased in thickness toward the inner peripheral surface side, and the rear end surface of the ceramic body 1 is in contact with the end surface of the extending portion 32. Thereby, heat can be transmitted to the extending portion 32 not only from the outer peripheral surface of the ceramic body 1 but also from the end surface. As a result, heat can be more easily transferred to the thermal fuse 4.

  Further, in the portion of the extended portion 32 where the temperature fuse 4 is provided, the metal cylinder 3 and the thermal fuse 4 are electrically connected, and the thermal fuse 4 is connected to the extended portion 32. A part is located on the extension of the ceramic body 1. It should be noted that the position on the extension of the ceramic body 1 means that when the connecting portion of the thermal fuse 4 that is joined to the flat surface of the metal cylinder 3 extends the outer shape of the ceramic body 1 as it is, it is within the extension region. Means to be located in Thereby, the size of the heater 10 in the circumferential direction can be reduced.

  Furthermore, the thickness of the metal fuse 3 is increased so that the thickness of the connecting portion of the thermal fuse 4 connected to the extended portion 32 is located on the extended line of the central axis of the ceramic body 1. Thereby, the thermal fuse 4 can be attached without considering the direction of the ceramic body 1. Therefore, the thermal fuse 4 can be easily attached.

  Further, a part of the extended portion 32 is thickened so that the thickness increases toward the inner peripheral surface side, and a part of the thermal fuse 4 is in contact with the extended portion 32. Thereby, the heat transmitted to the extended portion 32 can be quickly transmitted to the thermal fuse 4.

1: Ceramic body 2: Heating resistor 21: Electrode pattern 3: Metal cylinder 31: Ceramic body holding part 32: Extension part 33: Thermal fuse holding part 4: Thermal fuse 5: Metal case 51: Reduced diameter part 10: Heater

Claims (4)

A rod-shaped ceramic body, a heating resistor embedded at least on the front end side of the ceramic body, and a metal tube fitted to the rear end side of the ceramic body and electrically connected to the heating resistor The metal cylinder has an extending portion extending rearward from the rear end surface of the ceramic body, and a part of the thermal fuse is provided on the inner peripheral surface side of the extending portion. And
The extending portion is thick so that at least a part of the rear end surface side of the ceramic body increases in thickness toward the inner peripheral surface side, and the rear end surface of the ceramic body is in contact with the end surface of the extending portion. The heater characterized by having. In the portion of the extended portion where the thermal fuse is provided, the metal tube and the thermal fuse are electrically connected, and the connecting portion of the thermal fuse to the extended portion is The heater according to claim 1 , wherein the heater is located on an extension of the ceramic body. The thermal fuse is thick so that the thickness increases on the inner peripheral surface side of the metal cylinder so that the connecting portion with the extended portion of the thermal fuse is located on the extended line of the central axis of the ceramic body. The heater according to claim 2 . A rod-shaped ceramic body, a heating resistor embedded at least on the front end side of the ceramic body, and a metal tube fitted to the rear end side of the ceramic body and electrically connected to the heating resistor The metal cylinder has an extending portion extending rearward from the rear end surface of the ceramic body, and a part of the thermal fuse is provided on the inner peripheral surface side of the extending portion. And
  In the portion where the thermal fuse is provided in the extended portion, the metal tube and the thermal fuse are electrically connected, and
  The thermal fuse is thick so that the thickness increases on the inner peripheral surface side of the metal cylinder so that the connecting portion with the extended portion of the thermal fuse is located on the extended line of the central axis of the ceramic body. The heater as described.

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