JP7475314B2 - heater - Google Patents

Description

The disclosed embodiment relates to a heater.

Conventionally, heaters have been known in which a rod-shaped core material is covered with a sheet-shaped ceramic. These heaters have a heating resistor that generates heat when electricity is passed through them, and are used as heat sources for oxygen sensors, heat-generating devices, etc.

JP 2015-197953 A JP 2019-67696 A

However, there was room for improvement, for example, in terms of achieving radial miniaturization while maintaining the desired performance.

One aspect of the embodiment has been made in consideration of the above, and aims to provide a heater that can be made smaller in the radial direction.

The heater according to one aspect of the embodiment includes a rod-shaped core material, a heating resistor, a first layer, and a second layer. The heating resistor is located on the surface of the core material. The first layer has a first region and a second region, and covers the core material. The first region is located on the core material. The second region is located on the heating resistor. The second layer is located on the surface of the first layer, including the surface of the second region. No element pattern is located between the first layer and the second layer.

According to one aspect of the embodiment, it is possible to provide a heater that can be made compact in the radial direction.

FIG. 1 is a perspective view showing a heater according to an embodiment. FIG. 2 is a plan view of the heater according to the embodiment. FIG. 3 is a cross-sectional view taken along line III-III shown in FIG. FIG. 4 is a cross-sectional view taken along line IV-IV shown in FIG. FIG. 5 is an enlarged plan view of a region V shown in FIG. FIG. 6 is a cross-sectional view taken along line VI-VI shown in FIG. 7 is a cross-sectional view taken along line VII-VII shown in FIG. FIG. 8 is a cross-sectional view taken along line VIII-VIII shown in FIG. FIG. 9 is a plan view of a heater according to a first modified example of the embodiment. FIG. 10 is a plan view of a heater according to the second modification of the embodiment. FIG. 11 is a cross-sectional view taken along line XI-XI shown in FIG. 12 is a cross-sectional view taken along line XII-XII shown in FIG. FIG. 13 is a cross-sectional view of a heater according to a third modified example of the embodiment.

Below, an embodiment of the heater disclosed in the present application will be described with reference to the attached drawings. Note that the present disclosure is not limited to the embodiments shown below. It should be noted that the drawings are schematic, and the dimensional relationships and ratios of each element may differ from reality. Furthermore, there may be parts in which the dimensional relationships and ratios differ between the drawings.

<Embodiment>
First, a heater according to an embodiment will be described with reference to Fig. 1 to Fig. 4. Fig. 1 is a perspective view showing the heater according to the embodiment. Fig. 2 is a plan view of the heater according to the embodiment. Fig. 3 is a cross-sectional view taken along line III-III shown in Fig. 2. Fig. 4 is a cross-sectional view taken along line IV-IV shown in Fig. 2.

As shown in Figures 1 to 4, the heater 1 according to the embodiment includes a core material 10, a heating resistor 20, a first layer 30, and a second layer 40.

As shown in FIG. 2, the heater 1 has one end 1A and the other end 1B located at both ends in the longitudinal direction. The one end 1A is the tip end side of the heater 1, and the other end 1B is the rear end side of the heater 1.

For ease of understanding, Figs. 1 to 4 show a three-dimensional Cartesian coordinate system including a Z-axis extending along the length of the heater 1. Such a Cartesian coordinate system may also be shown in other drawings used in the following explanations.

The core material 10 has a rod shape. The core material 10 may have, for example, a cylindrical shape. The material of the core material 10 is, for example, an insulating ceramic. The material of the core material 10 may be, for example, alumina, silicon nitride, or aluminum nitride.

The length of the core material 10, i.e., the overall length of the heater 1, can be, for example, about 5 mm to 30 mm. The diameter of the core material 10 can be, for example, about 1 mm to 5 mm. The shape of the core material 10 is not limited to a cylindrical shape, and can be, for example, an elliptical cylindrical shape or a rectangular cylindrical shape.

The heating resistor 20 is located on the surface of the core material 10. The heating resistor 20 is a member that generates heat when electricity is passed through it. The heating resistor 20 may include a high resistance conductor including, for example, tungsten, molybdenum, etc. The heating resistor 20 has a predetermined pattern shape and appropriately heats the heater 1.

The first layer 30 is positioned so as to cover the core material 10. As shown in FIG. 3, the first layer 30 has a first region 30a and a second region 30b. The first region 30a is positioned on the core material 10. The second region 30b is positioned on the heating resistor 20.

The material of the first layer 30 is, for example, an insulating ceramic. The material of the first layer 30 may be, for example, alumina, silicon nitride, or aluminum nitride. The composition of the first layer 30 may be the same as or different from the composition of the core material 10.

The thickness of the first layer 30 can be, for example, about 0.1 mm to 0.4 mm. Also, as shown in FIG. 3, the first layer 30 may have end faces 31, 32 that are spaced apart from each other along the circumferential direction of the core material 10. The distance between the end faces 31, 32 can be, for example, about 0.1 mm to 1 mm. By spaced apart the end faces 31, 32 in this manner, for example, stress generated at the end faces 31, 32 of the first layer 30 can be dispersed, making the first layer 30 less likely to peel off.

The second layer 40 is located on the first layer 30. The second layer 40 is located so as to cover a portion of the first region 30a and the surface of the second region 30b.

The material of the second layer 40 is, for example, an insulating ceramic. The material of the second layer 40 may be, for example, alumina, silicon nitride, or aluminum nitride. The composition of the second layer 40 may be the same as or different from the composition of the core material 10 and/or the first layer 30.

The thickness of the second layer 40 can be, for example, about 0.1 mm to 0.4 mm. Also, as shown in FIG. 3, the second layer 40 may have end faces 41, 42 that are spaced apart from each other along the circumferential direction of the core material 10. The distance between the end faces 41, 42 can be, for example, about 0.1 mm to 1 mm. By spaced apart the end faces 41, 42 in this manner, for example, stress generated at the end faces 41, 42 of the second layer 40 can be dispersed, making the second layer 40 less likely to peel off.

By positioning the second layer 40 on the first layer 30, the first layer 30 is less likely to peel off, even if, for example, the diameter of the core material 10 is reduced. In addition, by positioning the second layer 40 on the first layer 30, the desired voltage resistance can be ensured, even if, for example, the thickness of the first layer 30 is reduced. Therefore, the heater 1 according to the embodiment can be made smaller in the radial direction.

As shown in FIG. 3, the heater 1 may have a groove 80 extending along the length of the core material 10. The groove 80 includes the end faces 31 and 32 of the first layer 30 and the end faces 41 and 42 of the second layer 40, and is a portion where the heating resistor 20 is not located and the core material 10 is exposed.

The groove portion 80 may also be positioned such that the circumferential end of the second layer 40 extending along the length of the core material 10 has a step with the surface of the first layer 30. That is, the end face 31 of the first layer 30 and the end face 41 of the second layer 40 may be positioned apart from each other. Similarly, the end face 32 of the first layer 30 and the end face 42 of the second layer 40 may be positioned apart from each other.

In this way, the end faces of the first layer 30 and the second layer 40 located along the circumferential direction of the core material 10 are positioned apart from each other in the circumferential direction, so that the stress generated, for example, on the end faces 31, 32 of the first layer 30 and the end faces 41, 42 of the second layer 40 can be dispersed, making the first layer 30 and/or the second layer 40 less likely to peel off.

As shown in FIG. 4, the heater 1 may also include a pad 50 located on the rear end side. The pad 50 is located on the surface of the first layer 30, and its end is sandwiched between the first layer 30 and the second layer 40. The pad 50 is electrically connected to the heating resistor 20 via a conductor 60 that penetrates the second region 30b of the first layer 30. The conductor 60 may be, for example, a via or a through hole. The pad 50 is connected to a lead 70, which allows power to be supplied to the heater 1 from a power supply device (not shown). By positioning the pad 50 and the lead 70 on the rear end side of the heater 1, for example, deterioration due to heat generation of the heater 1 can be reduced. Note that a land (not shown) may be located between the first layer 30 and the second layer 40.

On the other hand, no element pattern is located between the first layer 30 and the second layer 40. Here, the element pattern refers to a member having a purpose other than conduction, such as a heater pattern and a sensor pattern, and does not include low-resistance wiring patterns made of copper foil, such as pads 50 and lands. In this way, by not having an element pattern located between the first layer 30 and the second layer 40, peeling between the first layer 30 and the second layer 40 due to heat generation of the element pattern due to current flow is less likely to occur.

Also, as shown in FIG. 4, the end of the second layer 40 located on the rear end side of the core material 10 may have a step between it and the surface of the first layer 30. By positioning the end of the second layer 40 in this manner, for example, the stress generated on the end face on the rear end side of the second layer 40 can be dispersed, making the second layer 40 even less likely to peel off. Also, as shown in FIG. 4, it becomes easier to expose a part of the pad 50, making it easier to connect, for example, to the lead 70.

Next, the heater 1 according to the embodiment will be further described with reference to FIGS. 5 to 8. FIG. 5 is an enlarged plan view of region V shown in FIG. 2. FIG. 6 is a cross-sectional view taken along line VI-VI shown in FIG. 5. FIG. 7 is a cross-sectional view taken along line VII-VII shown in FIG. 5. FIG. 8 is a cross-sectional view taken along line VIII-VIII shown in FIG. 5.

As shown in FIG. 5, the heating resistor 20 has a first portion 201 and a second portion 202 that run along the length of the core material 10, and a third portion 203 that is located at the tip side of the core material 10 and connects the first portion 201 and the second portion 202.

In addition, the end 203e of the third portion 203 located at the tip side of the core material 10 extends in a direction along the end faces of the first layer 30 and the second layer 40 located at the tip side of the core material 10, i.e., in the Y-axis direction. This improves the thermal uniformity at the tip side of the heater 1, for example.

Also, as shown in Figures 6 to 8, the second region 30b of the first layer 30 located on the heating resistor 20 may protrude in the radial direction compared to the first region 30a of the first layer 30 where the heating resistor 20 is not located. By positioning the first layer 30 in this manner, it is possible to provide the first layer 30 with a consistent thickness throughout.

Also, as shown in Figures 7 and 8, when viewed in a cross section parallel to the longitudinal direction of the core material 10 including the third portion 203 of the heating resistor 20, the surface of the second layer 40 may protrude. Specifically, the region 40b of the second layer 40 located above the second region 30b may protrude in the radial direction compared to the region 40a of the second layer 40 located above the first region 30a. By having the region 40b protrude in this manner, for example, the bonding strength between the first layer 30 and the second layer 40 can be increased.

<Modification 1>
Next, various modified examples of the embodiment will be described with reference to Figures 9 to 13. In the various modified examples described below, the same parts as those in the embodiment will be denoted by the same reference numerals, and duplicated descriptions may be omitted.

Figure 9 is a cross-sectional view of a heater according to a first modified example of the embodiment. The heater 1 shown in Figure 9 differs from the heater 1 according to the embodiment in that the second layer 40 is not located on the surface of the first layer 30 including the third portion 203 of the heating resistor 20. As such, the second layer 40 is not located on the surface of the first layer 30 located on the third portion 203 located on the tip side of the heater 1, and this improves, for example, the temperature rise rate on the tip side of the heater 1.

<Modification 2>
Fig. 10 is a plan view of a heater according to Modification 2 of the embodiment, Fig. 11 is a cross-sectional view taken along line XI-XI shown in Fig. 10, and Fig. 12 is a cross-sectional view taken along line XII-XII shown in Fig. 10.

The heater 1 according to the second modification has an outer region 203a located on the tip side of the core material 10, and an inner region 203b located on the rear end side of the core material 10 from the outer region 203a, in the third portion 203 of the heating resistor 20. The first layer 30 is located on the surface of the outer region 203a. The first layer 30 and the second layer 40 are overlappingly located on the surface of the inner region 203b.

The first portion 201 and the second portion 202 of the heating resistor 20 are more likely to reach high temperatures than the third portion 203, so by overlapping the first layer 30 and the second layer 40, for example, the durability of the heater 1 is increased. On the other hand, since the second layer 40 is not located on the tip side of the heater 1, for example, the temperature rise rate on the tip side of the heater 1 is improved.

Also, as shown in Figures 11 and 12, the surface of the inner region 203b, i.e., the portion 401 of the second layer 40 located on the inner region 203b, may protrude in the radial direction of the core material 10 from the surface of the outer region 203a, i.e., the first layer 30 located on the outer region 203a. As a result, according to the heater 1 of this modified example, for example, the bonding strength between the first layer 30 and the second layer 40 can be increased.

<Modification 3>
Fig. 13 is a cross-sectional view of a heater according to a third modified example of the embodiment. The heater 1 shown in Fig. 13 differs from the heater 1 shown in Fig. 3 in that the heater 1 has a groove portion 80 in which the width of the end faces 41, 42 of the second layer 40 is larger than the width of the end faces 31, 32 of the first layer 30. In the heater 1, the end faces of the first layer 30 and the second layer 40 located along the circumferential direction of the core material 10 are located apart from each other in the circumferential direction, so that, for example, stress generated on the end faces 31, 32 of the first layer 30 and the end faces 41, 42 of the second layer 40 can be dispersed, and therefore the first layer 30 and/or the second layer 40 are less likely to peel off.

As described above, the heater 1 according to the embodiment includes a rod-shaped core material 10, a heating resistor 20, a first layer 30, and a second layer 40. The heating resistor 20 is located on the surface of the core material 10. The first layer 30 has a first region 30a and a second region 30b, and covers the core material 10. The first region 30a is located on the core material 10. The second region 30b is located on the heating resistor 20. The second layer 40 is located on the surface of the first layer 30, including the surface of the second region 30b. No element pattern is located between the first layer 30 and the second layer 40. This allows the heater 1 to be made smaller in the radial direction.

In addition, in the heater 1 according to the embodiment, one end face and the other end face of the first layer 30 located along the circumferential direction of the core material 10 are located apart. Also, one end face and the other end face of the second layer 40 located along the circumferential direction of the core material 10 are located apart. This makes it possible to disperse the stress that is applied to the end faces of the first layer 30 and the second layer 40.

In addition, in the heater 1 according to the embodiment, one end face of the first layer 30 and the second layer 40 located along the circumferential direction of the core material 10 are located apart from each other in the circumferential direction. This makes it possible to disperse the stress that is applied to the end faces of the first layer 30 and the second layer 40.

The heating resistor 20 according to the embodiment has a first portion 201 and a second portion 202 that run along the length of the core 10, and a third portion 203 that is located at the tip of the core 10 and connects the first portion 201 and the second portion 202. When viewed in a cross section that includes the third portion 203 and is parallel to the length of the core 10, the surface of the second layer 40 protrudes. This allows the heater 1 to be made smaller in the radial direction.

The heating resistor 20 according to the embodiment has a first portion 201 and a second portion 202 along the length of the core material 10, and a third portion 203 located at the tip side of the core material 10 and connecting the first portion 201 and the second portion 202. The third portion 203 has an outer region 203a located at the tip side of the core material 10, and an inner region 203b located closer to the rear end of the core material 10 than the outer region 203a. The first layer 30 is located on the surface of the outer region 203a, and the first layer 30 and the second layer 40 are overlappingly located on the surface of the inner region 203b. This allows the heater 1 to be made smaller in the radial direction.

In addition, the inner region 203b according to the embodiment has a surface that protrudes in the radial direction of the core material 10 more than the outer region 203a. This can increase the bonding strength between the first layer 30 and the second layer 40.

In addition, in the heater 1 according to the embodiment, the end 203e of the third portion 203 located on the tip side of the core material 10 extends in a direction along the end faces of the first layer 30 and the second layer 40 located on the tip side of the core material 10. This improves the thermal uniformity on the tip side of the heater 1.

In addition, in the heater 1 according to the embodiment, the end of the second layer 40 located on the rear end side of the core material 10 has a step between it and the surface of the first layer 30. This allows the heater 1 to be made smaller in the radial direction.

The heater 1 according to the embodiment has a groove 80 that extends along the length of the core material 10 and exposes the core material 10 without the heating resistor 20 being located therein. The circumferential end of the second layer 40, which is located in the groove 80 and extends along the length of the core material 10, has a step between it and the surface of the first layer 30. This makes it possible to disperse stresses generated at the end faces 41, 42 of the first layer 30 and the second layer 40, making the first layer 30 and/or the second layer 40 less likely to peel off.

The heater 1 according to the embodiment also includes a pad 50 located on the surface of the first layer 30, with an end portion sandwiched between the first layer 30 and the second layer 40. This makes the pad 50 less likely to peel off.

Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above embodiments, and various modifications are possible without departing from the spirit of the present disclosure.

Further advantages and other aspects may be readily derived by those skilled in the art. Therefore, the broader aspects of the disclosure are not limited to the specific details and representative embodiments shown and described above. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and equivalents thereof.

REFERENCE SIGNS LIST 1 heater 10 core material 20 heating resistor 30 first layer 30a first region 30b second region 40 second layer 50 pad 60 conductor 80 groove 201 first portion 202 second portion 203 third portion

Claims (10)

A rod-shaped core material;
A heating resistor located on the surface of the core material;
a first layer covering the core material, the first layer having a first region located on the core material and a second region located on the heating resistor;
a second layer located on a surface of the first layer including a surface of the second region;
A heater, wherein no element pattern is located between the first layer and the second layer. One end surface and the other end surface of the first layer located along the circumferential direction of the core material are spaced apart from each other,
The heater according to claim 1 , wherein one end surface and the other end surface of the second layer positioned along the circumferential direction of the core material are positioned apart from each other. The heater according to claim 1 or 2, wherein one end faces of the first layer and the second layer positioned along a circumferential direction of the core material are spaced apart from each other in the circumferential direction. the heating resistor has a first portion and a second portion along a longitudinal direction of the core material, and a third portion located at a tip side of the core material and connecting the first portion and the second portion,
4. The heater according to claim 1, wherein a surface of the second layer protrudes when viewed in a cross section including the third portion and parallel to a longitudinal direction of the core material. the heating resistor has a first portion and a second portion along a longitudinal direction of the core material, and a third portion located at a tip side of the core material and connecting the first portion and the second portion,
The third portion has an outer region located on a tip side of the core material and an inner region located on a rear end side of the core material relative to the outer region,
The first layer is located on a surface of the outer region,
5. The heater according to claim 1, wherein the first layer and the second layer are positioned so as to overlap each other on a surface of the inner region. The heater according to claim 5 , wherein the inner region has a surface that protrudes in a radial direction of the core material more than the outer region. The heater according to claim 5 or 6, wherein an end of the third portion located on the tip side of the core extends in a direction along end faces of the first layer and the second layer located on the tip side of the core. 8. The heater according to claim 1, wherein an end of the second layer located on a rear end side of the core material has a step between itself and a surface of the first layer. a groove extending along the length of the core material, the groove being free from the heating resistor and exposing the core material;
A heater as described in any one of claims 1 to 8, wherein a circumferential end of the second layer located in the groove portion and extending along the longitudinal direction of the core material has a step between it and the surface of the first layer. 10. A heater according to claim 1, further comprising a pad located on the surface of the first layer, the pad having an end sandwiched between the first layer and the second layer.

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