JP5227121B2 - Ceramic heater and method for manufacturing ceramic heater - Google Patents

Description

  The present invention relates to a ceramic heater including a straight rod-shaped insulating base made of an insulating ceramic and a heating resistor embedded in the insulating base, and a method for manufacturing such a ceramic heater. In particular, the heating resistor is embedded in the distal end portion of the insulating base and is made of conductive ceramic. The heating portion generates heat when energized, and the heating base is embedded in the insulating base and extends from the heating portion to the proximal side in the axial direction. The present invention relates to a ceramic heater having a lead portion for energizing the portion, and a method for manufacturing such a ceramic heater.

  2. Description of the Related Art Conventionally, a ceramic heater having a straight rod-like insulating base made of an insulating ceramic and a heating resistor embedded in the insulating base is known. As the form of the heating resistor, it is embedded in the distal end portion of the insulating base and is made of conductive ceramic. The heating portion generates heat when energized, and the heating base is embedded in the insulating base and extends from the heating portion to the base end side to energize the heating portion. Some of them have a lead portion. Furthermore, as a form of the heat generating part, it is formed in a U-shaped bent shape, and an intermediate part located between the two end parts is arranged in a posture that is on the front end side with respect to the two end parts. There is something. For example, such a ceramic heater is disclosed in FIG. About the conventional heat generating part, the width H was made into the form larger than the thickness t.

JP 2006-24394 A

  However, in the heat generating part having a U-shape as described above, the current density during energization is biased. Specifically, since current tends to flow inside the heat generating portion at the shortest distance, a larger amount of current flows in the inner portion of the U-shaped heat generating portion than in the outer portion. That is, the current density is higher in the inner part of the heat generating portion, and the current density is lower in the outer part. Therefore, in such a heat generating part, the heat generation temperature is also biased, the heat generation temperature is higher in the inner part, and the heat generation temperature is lower in the outer part.

  In ceramic heaters, there is a demand to reduce power consumption as much as possible while maintaining the temperature reached by the heater. In order to realize low power consumption of such a heating resistor, it is preferable to reduce the cross-sectional area of the heat generating portion and generate heat locally. However, in the heat generating part having a U-shape, the heat generation temperature is biased as described above. Therefore, if the cross-sectional shape of the heat generating part is similarly reduced and the cross-sectional area is reduced, the energization durability of the heat generating part is reduced. Tend to decline. For this reason, the cross-sectional area of the heat generating portion has to be increased to some extent, and it has been difficult to achieve both the current-carrying durability of the heat generating portion and the low power consumption of the heat generating resistor.

  The present invention has been made in view of the present situation, and a ceramic heater capable of ensuring the current-carrying durability of the heat generating portion even if the cross-sectional area of the heat generating portion of the heat generating resistor is reduced, and such a ceramic heater. It relates to the manufacturing method.

  The solution is made of an insulating ceramic, a straight rod-shaped insulating base extending in the axial direction from its base end to the tip, and embedded in the tip of the insulating base, made of a conductive ceramic, and energized. A ceramic heater comprising: a heat generating part that generates heat; and a heating resistor that is embedded in the insulating base and extends from the heat generating part to the base end side in the axial direction and energizes the heat generating part. The heat generating part is bent back in a U shape along a virtual reference plane including the axis, and has a form in which each cross section perpendicular to the extending direction in which the heat generating part extends is the same as each other. An intermediate portion located between the end portions is arranged in a posture that is closer to the tip end side in the axial direction than the two end portions, and a dimension in a direction orthogonal to the virtual reference plane of the heat generating portion is set to a thickness t ( mm) and the above A ceramic heater in which the heat generating portion is configured to satisfy t> H when the dimension of the heat portion along the virtual reference plane and perpendicular to the extending direction is defined as a width H (mm). is there.

  In the ceramic heater of the present invention, when the width of the U-shaped heat generating portion is H (mm) and the thickness is t (mm), the heat generating portion is configured to satisfy t> H. By adopting such a form for the heat generating portion, the bias of current density at the time of energization in the heat generating portion can be made smaller than before. This is because, as described above, in the heat generating part having a U-shape, a larger amount of current flows in the inner part than in the outer part, so that the current density is higher in the inner part and lower in the outer part. However, in the ceramic heater of the present invention, since the heat generating portion has a form in which the width H is smaller than the thickness t, the current density is more uneven than the heat generating portion of the conventional ceramic heater in which t <H. Can also be reduced. For this reason, the deviation of the heat generation temperature of the heat generating portion can be made smaller than before, and the current-carrying durability of the heat generating portion can be improved as compared with the conventional case. Therefore, it is possible to ensure the energization durability of the heat generating portion while reducing the cross-sectional area of the heat generating portion and reducing the power consumption of the heat generating resistor.

  In addition, by adopting the above-described form of the heat generating portion, the portion of the heat generating portion that is heated to the maximum temperature can be positioned relatively on the front end side than the conventional heat generating portion where t <H. it can. For this reason, the site | part which becomes the highest temperature among the front-end | tip parts of the insulation base | substrate of a ceramic heater can also be located relatively on the front end side rather than before. Therefore, for example, when this ceramic heater is used for a glow plug, the startability of the engine can be improved by heating the tip side to a higher temperature.

This will be specifically described with reference to FIG. FIG. 31 is a longitudinal sectional view of the tip portion of the ceramic heater cut along a plane that includes the axis AX and is perpendicular to the virtual reference plane HH. In FIG. 31, the outer shapes of the ceramic heater (t> H) of the present invention and the conventional ceramic heater (t ′ <H ′) are made to coincide with each other, and the heating resistor 15 according to the present invention and the heating resistor 55 according to the prior art are matched. The positions of the heat generating portions 15h and 55h are shown so that they can be compared.
In the ceramic heater according to the present invention, the heat generating portion 15h has the above-described configuration, so that the portion 15hx of the heat generating portion 15h that is heated to the maximum temperature, that is, the portion 15hx that has the highest current density, It can be moved to the tip side (downward in the figure) from the portion 55hx that is the maximum temperature of the heat generating portion 55h.

In addition, assuming that the cross-sectional area of the cross section perpendicular to the extending direction of the heat generating portion 15h is equal to that of the conventional heat generating portion 55h, the radial direction from the heat generating portion 15h to the surface of the insulating base 13 (the left-right direction in FIG. 31). Can be made smaller than the distance in the radial direction from the conventional heat generating portion 55 h to the surface of the insulating base 13.
Thereby, the temperature difference between the heat generating portion 15h and the surface of the insulating base 13 can be reduced. If the surface temperature of the insulating base 13 is made the same as that of the prior art, the heat generation temperature at the heat generating portion 15h can be lowered as compared with the conventional heat generation portion 15h, and as a result, the durability of the heat generating portion 15h can be reduced. Can be improved.

Examples of the “ceramic heater” include a ceramic heater used for a glow plug and a ceramic heater used for heating a sensor portion of a gas sensor.
The “heat generating resistor” only needs to have a heat generating portion and a lead portion that satisfy the above requirements, and the heat generating portion is made of conductive ceramic, but the lead portion is made of, for example, conductive ceramic, Or you may consist of metal materials, such as a tungsten wire.

Examples of the cross section of the “heat generating portion” include a semicircular shape, an elliptical shape, an oval shape, a rectangular shape, a trapezoidal shape, and a polygonal shape.
The “width H” of the heat generating portion refers to the maximum width of the heat generating portion. Therefore, when the width of the heat generating portion is different in the thickness direction, the maximum value of the dimension is “width H”.
The “thickness t” of the heat generating portion indicates the maximum thickness of the heat generating portion. Therefore, when the thickness of the heat generating portion is different in the width direction, the maximum value of the dimension is “thickness t”.

  Furthermore, in the above ceramic heater, the heating resistor may be a ceramic heater made entirely of a conductive ceramic.

  It is conceivable that the lead portion of the heating resistor is made of a metal material such as a tungsten wire for the purpose of reducing its resistance. However, tungsten wire or the like may cause a reaction at the interface with the insulating substrate. In addition, since the tungsten wire or the like has a thermal expansion coefficient larger than that of the conductive ceramic constituting the heat generating portion, the strength may decrease at the connection portion between the tungsten wire or the like and the heat generating portion.

On the other hand, in the present invention, the entire heating resistor is formed of a conductive ceramic. For this reason, the problem at the time of using a tungsten wire etc. as mentioned above does not arise.
If the entire heating resistor is made of conductive ceramic, the resistance of the lead portion tends to be larger than when a tungsten wire or the like is used for the lead portion. For such a ceramic heater, in order to generate heat in a concentrated manner at the heat generating portion, it is desired to reduce the cross-sectional area in order to increase the resistance of the heat generating portion. Therefore, if the above-described invention is applied, even if the cross-sectional area of the heat generating part is reduced, the current-carrying durability of the heat-generating part can be ensured. Can be achieved.

  The “heating resistor” only needs to be made of a conductive ceramic as a whole, and examples thereof include those made of a conductive ceramic having the same composition. Alternatively, it may be made of a plurality of types of conductive ceramics, such as changing the composition of the conductive ceramic between the heat generating portion and the lead portion.

Furthermore, in the above ceramic heater, the heating resistor is entirely made of conductive ceramic having the same composition, and the lead portion has a straight bar shape extending in the axial direction, and each of the lead portions is orthogonal to the axial direction. A pair of rod-shaped portions having the same shape in cross section, and a connecting portion that is located between the rod-shaped portion and the end of the heat generating portion and connects the two, and the dimension in the axial direction And a pair of connecting portions smaller than the rod-shaped portion and the heat generating portion, and the cross-sectional area of the cross-sectional area of the heat-generating portion is Sh (mm ² ), and the cross-sectional area of the cross-section of the rod-shaped portion of the lead portion is Is Sr (mm ² ), the heating resistor may be a ceramic heater configured to satisfy 1 / 25.5 ≦ Sh / Sr ≦ 1 / 2.6.

The cross-sectional area of the cross section of the heat generating part is Sh (mm ² ), and the cross-sectional area of the cross section of the rod-like part of the lead part is Sr (mm ² ). In the case where the heating resistor has a configuration satisfying Sh / Sr <1 / 25.5, the ratio of the cross-sectional area Sh of the cross section of the heat generating resistor to the cross-sectional area of the cross section of the insulating base is too small. The surface temperature in the cross section may vary greatly from position to position.
On the other hand, in the case where the heating resistor satisfies the form Sh / Sr> 1 / 2.6, the cross-sectional area of the heating portion is too large, so that the power consumption increases. In general, the heat generating resistor has a larger coefficient of thermal expansion than the insulating substrate, and among the heat generating resistors, the heat generating portion particularly generates more heat. For this reason, when the cross-sectional area Sh of the heat generating portion is increased, the stress due to the difference in thermal expansion coefficient is also increased, the heat generating portion is easily damaged, and there is a possibility that the energization durability is lowered.

  On the other hand, in the ceramic heater of the present invention, the heating resistor is configured to satisfy 1 / 25.5 ≦ Sh / Sr ≦ 1 / 2.6. When the heating resistor satisfies Sh / Sr ≦ 1 / 25.5, it is possible to suppress the surface temperature from greatly varying from position to position in the cross section of the insulating base. Further, when the heating resistor satisfies Sh / Sr ≦ 1 / 2.6, power consumption can be sufficiently reduced.

  Another solution is an insulating ceramic made of an insulating ceramic, extending in the axial direction from its base end to its tip, and a straight rod-like insulating base, and a heat generation that is embedded in the tip of the insulating base and generates heat when energized. Two cross-sections that are bent back in a U shape along a virtual reference plane including the axis and that have the same cross-sectional shape perpendicular to the extending direction in which they extend. An intermediate portion located between the end portions is disposed in a posture that is closer to the tip end side in the axial direction than the two end portions, and embedded in the insulating base, and from the heat generating portion to the axial direction A heating method for producing a ceramic heater comprising a lead resistor extending to the base end and energizing the heat generating portion, the heat generating resistor being entirely made of a conductive ceramic, comprising a non-fired insulating ceramic, And the main surface A resistor-corresponding recess having an opening shape corresponding to the heating resistor, the resistor-corresponding recess including at least a heating portion-corresponding recess having a U-shaped opening corresponding to the heating portion. A non-fired substrate press-molding step of press-molding an unfired insulating substrate that becomes a part of the insulating substrate after firing, wherein the depth of the heat generating portion corresponding recess is t1 (mm), and the heat generating portion corresponding recess An unsintered substrate press for forming the resistor-corresponding recess including the heat-generating-corresponding recess in a form satisfying t1> H1, where the distance between the inner opening edge and the outer opening edge of the sheet is defined as an opening width H1 (mm) An unfired conductive ceramic paste is printed and filled into the resistor-corresponding recesses of the unfired insulating substrate by a molding process and screen printing, and the unfired heating part that becomes the heating part after firing, and the lead after firing. A printing step of forming an unsintered heating resistor that is a part or the whole of the heating resistor after firing, comprising an unsintered lead part that is at least a part of the part, wherein the main When the dimension perpendicular to the surface is the thickness t2 (mm), and the dimension of the unfired heat generating portion along the main surface and perpendicular to the extending direction is the width H2 (mm) , After the firing using the printing process for forming the unfired heating resistor including the unsintered heating part in a form satisfying t2> H2, and the unfired insulating substrate and the unsintered heating resistor after the printing process. Forming a non-fired ceramic heater to be the ceramic heater, firing the fired ceramic heater, and forming the ceramic heater.

  In the manufacturing method of the present invention, in the unfired substrate press-molding step of press-molding the unfired insulating substrate that becomes a part of the insulating substrate after firing, the depth of the recess corresponding to the heat generating portion that forms a U-shaped opening is set to t1 ( mm), and when the opening width is H1 (mm), the resistor-corresponding concave portion including the heat-generating portion-corresponding concave portion satisfying t1> H1 is formed. And in the printing process of printing and forming the unsintered heating resistor that becomes a part or all of the heating resistor after firing on the unsintered insulating base having the resistor-corresponding recess in such a form, the width of the unsintered heating part H2 (mm) and a thickness of t2 (mm), an unsintered heating resistor including an unsintered heating part in a form satisfying t2> H2 is formed.

  If an unfired heat generating portion having such a form is formed, the heat generating portion after firing is also formed in a form satisfying t> H, where the width is H (mm) and the thickness is t (mm). As described above, such a heat generating part can make the current density unevenness during energization smaller than before. For this reason, the deviation of the heat generation temperature of the heat generating portion can be made smaller than before, and the current-carrying durability of the heat generating portion can be improved as compared with the conventional case. Therefore, it is possible to ensure the energization durability of the heat generating portion while reducing the cross-sectional area of the heat generating portion and reducing the power consumption of the heat generating resistor.

  In addition, as described above, the heat generating portion can position the portion of the heat generating portion that is heated to the maximum temperature relatively to the tip side of the conventional heat generating portion where t <H. . For this reason, the site | part which becomes the highest temperature among the front-end | tip parts of the insulation base | substrate of a ceramic heater can also be located relatively on the front end side rather than before. Therefore, for example, when this ceramic heater is used for a glow plug, the startability of the engine can be improved by heating the tip side to a higher temperature.

In addition, the formation method of the “unfired ceramic heater” in the present invention is not particularly limited as long as the above requirements are satisfied. For example, an unfired body corresponding to the remainder of the insulating substrate is formed by placing ceramic particles containing ceramic powder, a binder, etc. on the main surface of the unfired insulating substrate after the printing process, and performing press working or the like. Thus, there is a method of forming an unfired ceramic heater.
Further, an unfired ceramic heater is formed by separately forming an unfired insulator corresponding to the remainder of the insulating substrate and integrating it with the main surface of the unfired insulating substrate after the printing process. There is also a method. In this case, an unfired heating resistor that becomes the remainder of the heating resistor after firing can be formed on a separately formed unfired insulating substrate.

  Furthermore, in the method for manufacturing the ceramic heater described above, in the unfired substrate press molding step, the wall surface forming the heat generating portion corresponding recess extends from the inner opening edge in the depth direction of the heat generating portion corresponding recess. A taper angle that occurs between the inner wall surface and the virtual opening edge orthogonal surface that passes through the inner opening edge and that is orthogonal to the main surface as it advances in the depth direction. A method of manufacturing a ceramic heater formed on a tapered surface that is 5 degrees or more and 20 degrees or less.

In the production method of the present invention, in the unfired substrate press molding step, the inner wall surface of the wall surfaces constituting the heat generating portion corresponding concave portion having a U-shaped opening shape has a taper angle of 0.5 ° or more as described above. Therefore, the mold release after pressing is good and the productivity can be improved.
On the other hand, since the inner wall surface is a tapered surface having a taper angle of 20 degrees or less as described above, the heat generating portion after firing has a sufficient volume of the inner portion. For this reason, since the current density at the time of energization does not increase in this inner portion, the energization durability of the heat generating portion can be sufficiently ensured.

(Embodiment 1)
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a glow plug 100 using a ceramic heater 101 according to this embodiment. 2 and 3 show the entire ceramic heater 101. FIG. FIG. 4 shows a cross-sectional view of the ceramic heater. 5 and 6 show the vicinity of the tip 101s of the ceramic heater 101. FIG. 7 and 8 show the vicinity of the tip of the heat generating portion 105h of the heat generating resistor 105. FIG.

  As shown in FIG. 1, the glow plug 100 according to the first embodiment has a ceramic heater 101 that generates heat due to energization on the tip side in the axis AX direction (downward in FIG. 1, also simply referred to as the tip side hereinafter). Have. As shown in FIGS. 2 and 3, the ceramic heater 101 extends in the axis AX direction from a base end 101k (upper in FIGS. 2 and 3) to a front end 101s (lower in FIGS. 2 and 3). It has a straight rod shape (specifically, a cylindrical shape). The total length (length in the axis AX direction) of the ceramic heater 101 is 42 mm, and the outer diameter is 3.3 mm. The ceramic heater 101 has a heating resistor 105 that generates heat by energization embedded in a cylindrical insulating base 103.

  Of these, the insulating base 103 is made of an insulating ceramic (specifically, a silicon nitride ceramic). The insulating base 103 has a straight rod shape extending from the base end portion 103k corresponding to the base end portion 101k of the ceramic heater 101 to the front end portion 103s corresponding to the front end portion 101s of the ceramic heater 101 (specifically, the axial direction AX). A cylindrical shape). The distal end portion 103s is a hemispherical portion 103sa that is located at the forefront and forms a hemispherical shape with a radius of r = 1.5 (mm), and an axially proximal end side (hereinafter simply referred to as a proximal end side) of the hemispherical portion 103sa. And a cylindrical part 103sb having a cylindrical shape with a diameter of R = 2r = 3.0 (mm) and a length in the axis AX direction of r = 1.5 (mm) (see FIG. 5 and FIG. 5). (See also FIG. 6). Therefore, the length of the entire tip portion 103s in the axis AX direction is 2r = 3.0 (mm). Since the insulating base 103 (ceramic heater 101) has a cylindrical shape extending in the direction of the axis AX, the maximum width in the direction perpendicular to the axis AX is the diameter R.

  The heating resistor 105 embedded in the insulating base 103 is integrally composed of a heating part 105h and a pair of lead parts 105r1 and 105r2 connected to the heating part 105h. The heating resistor 105 is made of a conductive ceramic (specifically, tungsten carbide). Of these, the heat generating portion 105h (see FIGS. 5 to 8) has a shape bent back in a U shape along the virtual reference plane HH including the axis AX. Note that the virtual reference plane HH is a plane along the plane of the paper in FIGS. 2 and 5, and a plane orthogonal to the plane of the paper through the axis AX in FIGS. 3 and 6. In FIG. 4, the surface extends in the left-right direction and is orthogonal to the paper surface.

  The heat generating portion 105h has a form (a uniform form in the extending direction ES) in which each cross section YD perpendicular to the extending direction ES in which the heat generating part 105h extends is the same (see FIGS. 7 and 8). In the U-shaped heat generating portion 105h, the two end portions 105hk1 and 105hk2 are located on the base end side, and the intermediate portion 105hs located between the two end portions 105hk1 and 105hk2 is the two end portions 105hk1. , 105hk2 is arranged in a posture located on the tip side.

Assuming that the dimension of the heat generating portion 105h in the direction orthogonal to the virtual reference plane HH is the thickness t (mm), in the first embodiment, the thickness t = 0.50 (mm). Further, when the dimension of the heat generating portion 105h in the direction along the virtual reference plane HH and perpendicular to the extending direction ES is defined as the width H (mm), in the first embodiment, the width H = 0.300 (mm). It is. Therefore, the heat generating portion 105h is configured to satisfy t> H.
Specifically, as shown in FIGS. 7 and 8, the heat generating portion 105h includes a first main surface 105ha, a second main surface 105hb parallel to the first main surface 105ha, an inner side surface 105hc and an outer side surface that are orthogonal to each other and connect them. 105 hd. The heat generating portion 105h has a rectangular shape in which each cross section YD orthogonal to its own extending direction ES satisfies t> H. The cross-sectional area Sh of each transverse section YD of the heat generating portion 105h is 0.15 mm ² . Further, the length Y3 in the axial direction of the heat generating portion 105h is 1.45 mm (see FIG. 3).

  The pair of lead portions 105r1 and 105r2 connected to the heat generating portion 105h are integrally configured by rod-like portions 105rc1 and 105rc2, connecting portions 105re1 and 105re2, and electrode portions 105rd1 and 105rd2 (see FIGS. 2 to 6). .

Of these, the rod-shaped portions 105rc1 and 105rc2 have a straight rod shape extending in the axis AX direction, and each cross section perpendicular to the axis AX direction has a uniform shape (specifically, a semi-cylindrical shape) in the axis AX direction. . The rod-shaped portions 105rc1 and 105rc2 are connected to the end portions 105hk1 and 105hk2 of the heat generating portion 105h through connecting portions 105re1 and 105re2 described later, respectively, and extend to the base end portion 103k of the insulating base 103. .
The axial direction length Y1 of each rod-shaped part 105rc1, 105rc2 is 39.2 mm (see FIG. 3). Further, the cross-sectional area Sr of the cross section of each of the rod-like portions 105rc1 and 105rc2 is 1.45 mm ² . Therefore, the ratio of the cross-sectional areas Sh and Sr of the heat generating portion 105h and the rod-like portions 105rc1 and 105rc2 satisfies 1 / 25.5 ≦ Sh / Sr ≦ 1 / 2.6. Specifically, Sh / Sr = 1 / 9.7.

  The connecting portions 105re1 and 105re2 are located between the rod-like portions 105rc1 and 105rc2 and the end portions 105hk1 and 105hk2 of the heat generating portion 105h and connect the two. The connection portions 105re1 and 105re2 have the same cross-sectional area at the tip as the cross-sectional area Sh of the heat generating portion 105h, while the cross-sectional area of the base end is equal to the cross-sectional area Sr of the rod-like portions 105rc1 and 105rc2. And the connection part 105re1 and 105re2 are made into the form which a cross-sectional area becomes large gradually as it progresses from the front end side to the base end side. The length Y2 of the connecting portions 105re1 and 105re2 in the axis AX direction is 0.9 mm (see FIG. 3). Therefore, when viewed in the direction of the axis AX, the connecting portions 105re1 and 105re2 are shorter than the rod-like portions 105rc1 and 105rc2 and the heat generating portion 105h.

  The electrode portions 105rd1 and 105rd2 extend from the predetermined positions of the rod-shaped portions 105rc1 and 105rc2 to the outer periphery of the insulating base 103, and are used for electrical connection with the outside. The electrode portions 105rd1 and 105rd2 have a substantially rectangular parallelepiped shape. Among these, one electrode part 105rd1 is arrange | positioned at the base end part 103k of the insulation base | substrate 103, and it is exposed to the exterior of the ceramic heater 101 while connecting to one rod-shaped part 105rc1. The other electrode portion 105rd2 is disposed at a predetermined position slightly on the distal end side of the base end portion 103k of the insulating base 103, is connected to the other rod-shaped portion 105rc2, and is exposed to the outside of the ceramic heater 101. .

  The overall resistance value of the heating resistor 105 is 350 mΩ. Of the heating resistance value 105, the resistance value of the heating portion 105h is 125 mΩ, and the resistance values of the lead portions 105r1 and 105r2 are 225 mΩ.

Next, other parts of the glow plug 100 will be described (see FIG. 1). The glow plug 100 includes a cylindrical metal shell 120 that holds the proximal end portion of the ceramic heater 101 described above. The metal shell 120 is located on the distal end side, and includes a heater holding member 123 that holds the ceramic heater 101 and a metal shell body 121 that is located on the proximal end side of the heater holding member 123.
Among these, the metal shell main body 121 has a cylindrical shape extending from the base end portion 121k to the tip end portion 121s in the direction of the axis AX. A tool engaging portion 121e having a hexagonal cross section for engaging a tool such as a torque wrench when the glow plug 100 is attached to the diesel engine is formed at the base end portion 121k of the metal shell main body 121. In addition, a screw part 121f for attachment is formed on the outer periphery of the metal shell body 121 on the tip side of the tool engagement part 121e.

  Inside the metal shell main body 121, a rod-shaped metal terminal shaft 125 for supplying electric power to the ceramic heater 101 from the base end side is disposed in a state of being electrically insulated from the metal shell main body 121. . Between the metal shell body 121 and the metal terminal shaft 125, an O-ring 127 for airtight sealing and watertight sealing is arranged on the base end side of the shelf 121g formed on the inner periphery of the metal shell body 121. Has been. A cylindrical insulating bush 129 through which the energizing terminal shaft 125 is inserted is disposed between the metal shell body 121 and the metal terminal shaft 125 on the proximal end side of the O-ring 127. The insulating bush 129 is pressed to the tip end side by a terminal fitting 133, which will be described later, and compresses the O-ring 127 with the shelf 121g.

  The heater holding member 123 has a cylindrical shape, and a base end portion 123k is welded to a front end portion 121s of the metal shell main body 121. The proximal end portion of the ceramic heater 101 is inserted and fixed to the heater holding member 123. Specifically, the ceramic heater 101 is press-fitted into and held by the heater holding member 123 such that the front end portion 101s and the base end portion 101k protrude.

The base end portion 125k of the metal terminal shaft 125 inserted through the metal shell main body 121 protrudes toward the base end side from the metal shell main body 121. A terminal fitting 133 is attached to the base end portion 125k via the insulating bush 129.
On the other hand, the leading end 125s of the metal terminal shaft 125 is inserted into a cylindrical connection ring 135 and welded thereto. The connection ring 135 is press-fitted with the base end portion 101k of the ceramic heater 101 on the other side, and one electrode portion 105rd1 (not shown in FIG. 1) provided on the base end portion 101k is electrically connected to the connection ring 135. Connected. Thereby, one electrode part 105rd1 of the ceramic heater 101 and the metal terminal shaft 125 are electrically connected. The other electrode portion 105rd2 (not shown in FIG. 1) of the ceramic heater 101 is electrically connected to the heater holding member 123 that holds the ceramic heater 101, and thus the metal shell 120.

  As described above, in the ceramic heater 101 of the first embodiment, when the width of the U-shaped heat generating portion 105h is H (mm) and the thickness is t (mm), the heat generating portion 105h has t> It is set as the form which satisfy | fills H. By adopting such a configuration for the heat generating portion 105h, the bias of current density during energization in the heat generating portion 105h can be made smaller than in the prior art. This is because the U-shaped heat generating portion 105h has a larger current flowing in the inner portion (inner side surface 105hc side portion) than in the outer portion (outer side surface 105hd side portion) as described above. The density is high, and the current density is lower in the outer portion. However, in the first embodiment, since the heat generating portion 105h has a form in which the width H is smaller than the thickness t, this current density is more uneven than the heat generating portion of the conventional ceramic heater where t <H. Can also be reduced. For this reason, the deviation of the heat generation temperature of the heat generating portion 105h can be made smaller than before, and the energization durability of the heat generating portion 105h can be improved as compared with the conventional case. Therefore, it is possible to ensure the energization durability of the heat generating portion 105h while reducing the cross-sectional area Sh of the heat generating portion 105h and realizing low power consumption of the heat generating resistor 105.

  Further, by adopting the above-described form of the heat generating portion 105h, the portion of the heat generating portion 105h that is heated to the maximum temperature is positioned relatively distal to the conventional heat generating portion where t <H. be able to. For this reason, the site | part used as the maximum temperature among the ceramic heaters 101 can also be located in the front end side relatively rather than before. In particular, since the ceramic heater 101 is a glow plug heater, the startability of the diesel engine can be improved by heating the tip side to a higher temperature.

In the first embodiment, the entire heating resistor 105 is made of a conductive ceramic. For this reason, there are problems when a metal material such as a tungsten wire is used for the lead portions 105r1 and 105r2 (such as a reaction at the interface with the insulating base 103 or a decrease in durability at the connection portion with the heat generating portion 105). Does not occur.
If the entire heating resistor 105 is formed of conductive ceramic, the resistance of the lead portions 105r1 and 105r2 tends to be larger than when tungsten wires or the like are used for the lead portions 105r1 and 105r2. In order to heat the ceramic heater 101 in a concentrated manner at the heat generating portion 105h, it is desired to reduce the cross-sectional area Sh in order to increase the resistance of the heat generating portion 105h. Therefore, if the heat generating portion 105h is configured as described above, the energization durability of the heat generating portion 105h can be ensured even if the cross sectional area Sh of the heat generating portion 105h is reduced. Therefore, it is possible to reduce the power consumption of the heating resistor 105 while ensuring the energization durability of the heating portion 105h.

In the first embodiment, the cross-sectional area of the cross section YD of the heat generating part 105h is Sh (mm ² ), and the cross-sectional area of the cross sections of the rod-like parts 105rc1 and 105rc2 of the lead parts 105r1 and 105r2 is Sr (mm ² ). At this time, the heating resistor is configured to satisfy 1 / 25.5 ≦ Sh / Sr ≦ 1 / 2.6. By setting the heating resistor 105 to satisfy the form Sh / Sr ≧ 1 / 25.5, it is possible to suppress the surface temperature from greatly varying from position to position in the cross section of the insulating base 103. On the other hand, the power consumption can be sufficiently reduced by making the thermal resistor 105 satisfy the form Sh / Sr ≦ 1 / 2.2.6.

Next, a method for manufacturing the ceramic heater 101 and the glow plug 100 will be described. First, a method for manufacturing the ceramic heater 100 will be described (see FIGS. 9 to 22).
First, in the first unfired substrate forming step, ceramic particles containing insulating ceramic powder, a binder, and the like are press-molded with a mold, and the first unfired insulating substrate 151 that becomes a part of the insulating substrate 103 after firing. (See FIGS. 9 to 12).

  The first unsintered insulating base 151 has a shape corresponding to one of the insulating base 103 divided into two on the virtual reference plane HH so that the longitudinal sectional view shown in FIG. 2 can be seen. Specifically, as shown in FIGS. 9 to 12, the first unsintered insulating base 151 has a substantially semi-cylindrical shape having a first main surface 151a. The first main surface 151a is provided with a first resistor corresponding recess 151j having a shape corresponding to the heating resistor 105. The first resistor-corresponding recess 151j has a U-shaped opening corresponding to the heating portion 105h of the heating resistor 105 and a first heating portion corresponding to the lead portions 105r1 and 105r2. It consists of a lead corresponding recess 151jb.

  The heat generating portion corresponding concave portion 151ja having a U-shaped opening shape includes a bottom surface 151jab, an inner wall surface 151jac, and an outer side surface 151jad. The bottom surface 151jab is parallel to the first main surface 151a and has a U-shaped form in plan view. The inner wall surface 151jac is a surface that forms the inner side of the heat generating portion corresponding recess 151ja, and is orthogonal to the first main surface 151a and the bottom surface 151jab and connects the first main surface 151a and the bottom surface 151jab. The inner wall surface 151jac is curved in a U shape when viewed from the first main surface 151a side (see FIG. 9). The outer wall surface 151jad is a surface constituting the outer side of the heat generating portion corresponding recess 151ja, and is orthogonal to the first main surface 151a and the bottom surface 151jab and connects the first main surface 151a and the bottom surface 151jab. When viewed from the first main surface 151a side (see FIG. 9), the outer wall surface 151jad is curved in a U-shape at equal intervals from the inner side surface 151jac.

  In addition, in this heat generating portion corresponding recess 151ja, the dimension from the first main surface 151a to the bottom surface 151jab is set to a depth t1 (mm). The distance between the inner opening edge 151jaf1 where the first main surface 151a and the inner wall surface 151jac intersect and the outer opening edge 151jaf2 where the first main surface 151a and the outer wall surface 151jad intersect is defined as an opening width H1 (mm). . Then, this heat generating part corresponding | compatible recessed part 151ja is made into the form which satisfy | fills t1> H1. Specifically, the depth t1 = 0.48 (mm) and the opening width H1 = 0.3 (mm). And the heat generating part corresponding | compatible recessed part 151ja is made into the rectangular shape where each cross section orthogonal to an extending direction of itself satisfy | fills t1> H1 (refer FIG. 12).

  Next, a first metal mask MM1 having a first through hole TC1 is prepared (see FIG. 13). The first through hole TC1 has an opening shape corresponding to the entire first resistor corresponding recess 151j of the first unsintered insulating base 151. Specifically, the first through hole TC1 includes a first heating portion corresponding hole TC1a having a U-shaped opening corresponding to the heating portion corresponding recess 151ja of the first resistor corresponding recess 151j, and the first resistance. The body corresponding recess 151j includes a first lead corresponding hole TC1b having an opening corresponding to the first lead corresponding recess 151jb.

In the first printing step, the first metal mask MM1 is placed on the first main surface 151a of the first unfired insulating base 151 in alignment. Thereafter, the first unfired conductive ceramic paste DP1 is printed and filled in the first resistor corresponding recess 151j and the first through hole TC1 by the squeegee SK (see also FIGS. 14 and 15). Note that the first unfired conductive ceramic paste DP1 is made of ceramic powder, binder, solvent, and the like made of 70% by weight of conductive ceramic powder and 30% by weight of insulating ceramic powder.
Thereby, the 1st unbaking heating resistor 161 used as a part of heating resistor 105 after baking is formed. The first unsintered heating resistor 161 includes an unsintered heating part 161h that becomes the entire heating part 105h after firing, and a first unsintered lead part 161r that becomes part of the lead parts 105r1 and 105r2 after firing.

  As shown in FIG. 15 corresponding to FIG. 12, in the unfired heat generating portion 161h, the dimension in the direction orthogonal to the first main surface 151a is defined as thickness t2 (mm). A dimension in a direction along the first main surface 151a and perpendicular to the extending direction of the first main surface 151a is defined as a width H2 (mm). Then, the unfired heat generating portion 161h is configured to satisfy t2> H2. Specifically, the thickness t2 = 0.5 (mm) and the width H2 = 0.3 (mm). The unsintered heat generating portion 161h has a rectangular shape in which each cross section perpendicular to its own extending direction satisfies t2> H2.

  On the other hand, in the second unfired substrate press molding step, ceramic particles containing insulating ceramic powder, binder, and the like are press-molded with a mold, and the second unfired insulation that becomes the remainder of the insulating substrate 103 after firing. A base 153 is formed (see FIGS. 16 to 18). The second unsintered insulating base 153 has a shape corresponding to the other of the insulating base 103 divided into two on the virtual reference plane HH so that the cross-sectional view shown in FIG. 2 can be seen. Specifically, as shown in FIGS. 16 to 18, the second unsintered insulating base 153 has a substantially semi-cylindrical shape having a second main surface 153 a. The second main surface 153a is provided with a second resistor corresponding recess 153j having a shape corresponding to the heating resistor 105. The second resistor-corresponding recess 153j is composed only of the second lead-corresponding recess 153jb having an opening corresponding to the lead portions 105r1 and 105r2 of the heating resistor 105, and does not have a portion corresponding to the heating portion 105h.

  Next, a second metal mask MM2 having a second through hole TC2 is prepared (see FIG. 19). The second through hole TC2 has an opening shape corresponding to the entire second resistor corresponding recess 153j of the second unsintered insulating base 153. Since the second resistor-corresponding recess 153j is composed of only the second lead-corresponding recess 153jb as described above, the second through hole TC2 has an opening shape corresponding to the second lead-corresponding recess 153jb. It consists only of part TC2b.

  Then, in the second printing step, the second metal mask MM2 is positioned and placed on the second main surface 153a of the second unfired insulating base 153. Thereafter, the second unfired conductive ceramic paste DP2 is printed and filled into the second resistor corresponding recess 153j and the second through hole TC2 by the squeegee SK (see also FIG. 20). As a result, the second unfired heating resistor 163 that becomes the remainder of the heating resistor 105 after firing is formed. The second unfired heating resistor 163 is composed of only the second unfired lead portion 163r that becomes the remainder of the lead portions 105r1 and 105r2 after firing, and there is no portion corresponding to the heat-generating portion 105h after firing. In the first embodiment, the same material as the first unfired conductive ceramic paste DP1 is used as the second unfired conductive ceramic paste DP2.

  Next, in the firing step, first, the first main surface 151a of the first unfired insulating base 151 after the first printing step, and the second main surface 153a of the second unfired insulating base 153 after the second printing step, Thus, an unfired ceramic heater 170 that becomes the ceramic heater 101 after firing is formed (see FIGS. 21 and 22). Specifically, the unfired ceramic heater 170 is formed by pressing and integrating the first unfired insulating base 151 and the second unfired insulating base 153 using a mold. As a result, an unfired insulating base 171 that becomes the insulating base 103 after firing is formed from the first unfired insulating base 151 and the second unfired insulating base 153. Further, from the first unfired heating resistor 161 and the second unfired heating resistor 163, the unfired heat generating portion 173h corresponding to the fired heat generating portion 105h and the unfired corresponding to the fired lead portions 105r1 and 105r2. An unfired heating resistor 173 made of the lead portion 173r is formed.

  Subsequently, in order to remove binder components and the like from the unfired ceramic heater 170, the unfired ceramic heater 170 is temporarily fired at a predetermined temperature (for example, about 800 ° C.) in a nitrogen atmosphere. Then, the ceramic heater 101 is obtained by performing hot press firing at a predetermined temperature (for example, 1800 ° C.) in a nitrogen atmosphere. The firing shrinkage of hot press firing shrinks to about ½ after firing in the press direction, but hardly shrinks in other directions. In the first embodiment, hot press firing is performed with the direction orthogonal to the paper surface in FIG. 3 as the pressing direction. For this reason, the shapes shown in FIGS. 8 and 12 have almost no change before and after firing. Thereafter, the ceramic heater 101 is subjected to processing such as polishing to complete the ceramic heater 101 shown in FIG.

As described above, in the method for manufacturing the ceramic heater 101 according to the first embodiment, in the first unfired substrate press-molding step of press-molding the first unfired insulating substrate 151 that becomes a part of the insulating substrate 103 after firing. , Including a heat generating portion corresponding recess 151ja in a form satisfying t1> H1, where the depth of the heat generating portion corresponding recess 151ja having a U-shaped opening is t1 (mm) and the opening width is H1 (mm). A resistor-corresponding recess 151j is formed.
Then, the first non-fired heating resistor 161, which becomes a part of the heating resistor 105 after firing, is printed and formed on the first non-fired insulating base 151 having the first resistor-corresponding recess 151j having such a configuration. Perform the printing process. In this step, when the width of the first unsintered heat generating portion 161 is H2 (mm) and the thickness is t2 (mm), the first unsintered heat generating resistor including the unsintered heat generating portion 161h satisfying t2> H2 is satisfied. 161 is formed.

  If the unfired heat generating portion 161h having such a form is formed, the heat generating portion 105h after firing also satisfies t> H, as described above, where the width is H (mm) and the thickness is t (mm). Formed into a form. As described above, such a heat generating portion 105h can make the current density unevenness during energization smaller than in the past. For this reason, the deviation of the heat generation temperature of the heat generating portion 105h can be made smaller than before, and the energization durability of the heat generating portion 105h can be improved as compared with the conventional case. Therefore, it is possible to ensure the energization durability of the heat generating portion 105h while reducing the cross-sectional area Sh of the heat generating portion 105h and realizing low power consumption of the heat generating resistor 105.

  Moreover, since the heat generating part 105h after firing can position the part of the heat generating part 105h that generates heat at the highest temperature relative to the tip side of the conventional part, the part of the ceramic heater 101 that has the highest temperature is also conventional. It can be located relatively on the tip side. In particular, since the ceramic heater 101 is a glow plug heater, the startability of the diesel engine can be improved by heating the tip side to a higher temperature.

  Next, a method for manufacturing the glow plug 100 will be described. First, the ceramic heater 101 is manufactured by the above manufacturing method (heater manufacturing process). In addition, other members constituting the glow plug 100 such as the metal shell main body 121, the heater holding member 123, the connection ring 135, the metal terminal shaft 125, the O-ring 127, the insulating bush 129, and the terminal metal fitting 133 are also prepared. Next, the glow plug 100 is assembled using these members to obtain the glow plug 100 shown in FIG. 1 (plug assembly process).

(Embodiment 2)
Next, a second embodiment will be described. In the ceramic heater 101 of the first embodiment, the shape of each cross section YD orthogonal to the extending direction ES of the heat generating portion 105h extending in a U shape is rectangular (see FIG. 8). On the other hand, in the ceramic heater 201 of the second embodiment, the shape of each cross section YD orthogonal to the extending direction ES of the heat generating portion 205h extending in a U shape is a trapezoid (inverted trapezoid) (see FIG. 23). .

  Moreover, in the manufacturing method of the ceramic heater 101 of the said Embodiment 1, among the 1st resistor corresponding | compatible recessed parts 151j provided in the 1st non-baking insulation base | substrate 151, the shape of the cross section of the heat generating part corresponding | compatible recessed part 151ja is made into the rectangular shape ( (See FIGS. 12 and 15). On the other hand, in the manufacturing method of the ceramic heater 201 according to the second embodiment, the shape of the cross section of the heat generating portion corresponding recess 251ja among the first resistor corresponding recesses 251j provided in the first unfired insulating base 251 is trapezoidal ( Inverted trapezoidal shape) (see FIG. 24). Other than that, the second embodiment is the same as the first embodiment, and the description of the same parts as the first embodiment is omitted or simplified.

The ceramic heater 201 of the second embodiment is different from the first embodiment only in the form of the heat generating part 205h. Like the heat generating part 105h of the first embodiment, the heat generating part 205h is bent back in a U shape along the virtual reference plane HH including the axis AX, and each of the heat generating parts 205h is orthogonal to its own extending direction ES. The cross section YD has the same form (a uniform form in the stretching direction ES).
On the other hand, as shown in FIG. 23, the heat generating portion 205h includes a first main surface 205ha, a second main surface 205hb parallel to the first main surface 205ha, an inner side surface 205hc and an outer side surface 205hd connecting them. And the shape of each cross section YD orthogonal to the extending | stretching direction ES of the heat generating part 205h makes trapezoid.

Specifically, the inner side surface 205hc is a tapered surface that goes outward (outer side surface 205hd side) as it goes from the first main surface 205ha to the second main surface 205h. The taper angle θ1 generated between the inner side surface 205hc and the virtual orthogonal plane HV11 passing through the inner edge 205hf1 of the first main surface 205ha and orthogonal to the first main surface 205ha is 0.5 degrees or more and 20 degrees or less. Specifically, the taper angle θ1 = 10 (degrees).
The outer side surface 205hd is a tapered surface that goes inward (inner side surface 205hc side) as it goes from the first main surface 205ha to the second main surface 205h. The outer side surface 205hd has a taper angle θ2 between 0.5 degrees and 20 degrees, which is generated between the outer surface 205hf2 of the first main surface 205ha and the virtual orthogonal surface HV21 orthogonal to the first main surface 205ha. Specifically, the taper angle θ2 = 10 (degrees).

Further, the thickness t of the heat generating portion 205h is 0.50 (mm), and the width H is 0.381 (mm). Therefore, the heat generating portion 205h is also configured to satisfy t> H as a whole. The cross-sectional area Sh of the cross section YD of the heat generating part 205h is equal to the cross-sectional area Sh (= 0.15 mm ² ) of the cross section YD of the heat generating part 105h of the first embodiment.

Similarly to the first embodiment, such a ceramic heater 201 is configured such that the heat generating portion 205h satisfies t> H. For this reason, the bias of the current density at the time of energization in the heat generating portion 205h can be made smaller than before. Therefore, the deviation of the heat generation temperature of the heat generating portion 205h can be made smaller than before, and the energization durability of the heat generating portion 205h can be improved as compared with the conventional case. Therefore, it is possible to ensure the energization durability of the heat generating portion 205h while realizing low power consumption.
In addition, since the portion of the heat generating portion 205h that generates heat at the highest temperature can be positioned on the distal end side relative to the conventional one, the portion of the ceramic heater 201 that has the highest temperature is also relatively on the distal end side than the conventional one. Can be positioned. Thereby, the startability of a diesel engine can be improved. In addition, the same parts as those of the first embodiment have the same effects as those of the first embodiment.

The ceramic heater 201 having such a heat generating portion 205h is manufactured as follows. That is, first, the first green substrate forming step is performed, and the first green substrate 251 is press-molded (see FIG. 24).
The first resistor-corresponding recess 251j provided in the first unsintered insulating base 251 has a U-shaped opening corresponding to the heating portion 205h and an opening corresponding to the lead portions 105r1 and 105r2. It comprises a first lead corresponding recess 151jb having a shape.

The heat generating portion corresponding recess 251ja includes a bottom surface 251jab, an inner wall surface 251jac, and an outer wall surface 251jad. The bottom surface 251jab is parallel to the first main surface 251a and has a U-shaped form in plan view.
The inner wall surface 251jac is a surface that connects the first main surface 151a and the bottom surface 151jab and constitutes the inside of the heat generating portion corresponding recess 151ja. The inner wall surface 251jac is a tapered surface toward the outer opening edge 251jaf2 side (outer wall surface 251jad side) as it proceeds in the depth direction (bottom surface 151jab side). This inner wall surface 251jac has a taper angle θ11 generated between the virtual opening edge orthogonal surface HW1 passing through the inner opening edge 251jaf1 and orthogonal to the first main surface 251a is 0.5 degrees or more and 20 degrees or less. Specifically, the taper angle θ11 = 10 (degrees).

  The outer wall surface 251jad is a surface that connects the first main surface 151a and the bottom surface 151jab and constitutes the outer side of the heat generating portion corresponding recess 151ja. The outer wall surface 251jad is a tapered surface toward the inner opening edge 251jaf1 side (inner wall surface 251jac side) as it proceeds in the depth direction (bottom surface 151jab side). The outer wall surface 251jad has a taper angle θ21 generated between the virtual opening edge orthogonal surface HW2 passing through the outer opening edge 251jaf2 and orthogonal to the first main surface 251a is 0.5 degrees or more and 20 degrees or less. Specifically, the taper angle θ21 = 10 (degrees).

  The depth t1 of the heat generating portion corresponding recess 251ja is 0.48 (mm), and the opening width H1 is 0.381 (mm). Accordingly, the heat generating portion corresponding concave portion 251ja has a shape satisfying t1> H1, specifically, a trapezoidal shape in which each cross section orthogonal to its extending direction satisfies t1> H1. By adopting such a configuration for the heat generating portion corresponding concave portion 251ja, the mold release after pressing becomes good, and the productivity can be improved.

Next, a first printing step is performed to form a first unfired heating resistor 261 that becomes a part of the heating resistor 105 after firing (see FIG. 24). The first unsintered heating resistor 261 includes an unsintered heating part 261h that becomes the entire heating part 105h after firing, and a first unsintered lead part 161r that becomes a part of the lead parts 105r1 and 105r2 after firing. Among these, the unfired heat generating portion 261h is configured to satisfy t2> H2. Specifically, the unsintered heat generating portion 261h has a thickness t2 = 0.50 (mm), a width H2 = 0.382 (mm), and each cross section perpendicular to its own stretching direction is t2> H2. The trapezoidal shape is satisfied.
Thereafter, similarly to the first embodiment, the ceramic heater 201 is completed by performing the second unfired substrate forming step, the second printing step, the unfired heater forming step, the firing step, and the like.

  As described above, in the method of manufacturing the ceramic heater 201 according to the second embodiment, in the first green substrate press molding process, the depth of the heat generating portion corresponding recess 251ja having the U-shaped opening shape is t1 (mm) and the opening width. Is H1 (mm), the first resistor corresponding recess 251j including the heat generating portion corresponding recess 251ja satisfying t1> H1 is formed. Then, in the first green insulating base 251 having the first resistor-corresponding recess 251j having such a configuration, in the first printing step, the width of the green heat generating portion 261h is H2 (mm) and the thickness is t2 (mm). Then, the unsintered heating resistor 261 including the unsintered heating part 261h in a form satisfying t2> H2 is formed.

  If the unfired heat generating portion 261h having such a configuration is formed, the heat generating portion 205h after firing also satisfies t> H as described above, where the width is H (mm) and the thickness is t (mm). Formed into a form. Such a heat generating portion 205h can make the current density unevenness during energization smaller than in the past. For this reason, the deviation of the heat generation temperature of the heat generating portion 205h can be made smaller than before, and the energization durability of the heat generating portion 205h can be improved as compared with the conventional case. Therefore, it is possible to ensure the durability of energization of the heat generating portion 205h while reducing the cross-sectional area of the heat generating portion 205h and reducing the power consumption of the heat generating resistor 205.

In the second embodiment, in the first unfired substrate press-molding step, the inner wall surface 251jac of the wall surfaces constituting the heat generating portion corresponding recess 251ja has a taper angle θ11 of 0.5 degrees or more as described above (specifically 10 degree), the mold release after pressing is good, and the productivity can be improved.
On the other hand, since the inner wall surface 251jac is a tapered surface with a taper angle θ11 of 20 degrees or less (specifically, 10 degrees), the heat-generating part 205h after firing has its inner part (part on the inner side face 205hc side). ) Is sufficiently secured. For this reason, since the current density at the time of energization does not increase so much in this inner portion, the energization durability of the heat generating portion 205h can be sufficiently ensured.
In addition, the same parts as those of the first embodiment have the same effects as those of the first embodiment.

(Embodiment 3)
Next, a third embodiment will be described. In the ceramic heater 201 of the second embodiment, the shape of each cross section YD perpendicular to the extending direction ES of the heat generating portion 205h extending in a U shape is a trapezoid, and the taper angle is θ1 = θ2 = 10 (degrees). (See FIG. 23). In contrast, in the ceramic heater 301 of the third embodiment, the shape of each cross section YD orthogonal to the extending direction ES of the heat generating portion 305h extending in a U shape is a trapezoid, and the taper angle is θ1 = θ2 = 0.5. (Degree) (see FIG. 25). Further, the width H of the heat generating portion 305 is changed in order to make the cross-sectional area Sh of the heat generating portion 305 h equal to that of the first and second embodiments. Other than that, the second embodiment is the same as the first or second embodiment, and therefore, the description of the same parts as the first or second embodiment is omitted or simplified.

  As shown in FIG. 25, the heat generating portion 305h of the ceramic heater 301 according to the third embodiment includes a first main surface 305ha, a second main surface 305hb parallel to the first main surface 305ha, and an inner side surface 305hc and an outer side surface 305hd connecting them. Has been. And the shape of each cross section YD orthogonal to the extending | stretching direction ES of the heat generating part 305h makes trapezoid shape (reverse trapezoid shape). Specifically, the taper angle θ1 generated between the inner side surface 305hc and the virtual orthogonal plane HV12 passing through the inner edge 305hf1 of the first main surface 305ha and orthogonal to the first main surface 305ha is 0.5 degrees or more and 20 degrees. It is a tapered surface that: Specifically, the taper angle θ1 = 0.5 (degrees). In addition, the outer side surface 305hd has a taper angle θ2 generated between the virtual orthogonal surface HV22 that passes through the outer edge 305hf2 of the first main surface 305ha and is orthogonal to the first main surface 305ha, and is between 0.5 degrees and 20 degrees. Tapered surface. Specifically, the taper angle θ2 = 0.5 (degrees).

Further, the thickness t of the heat generating portion 305h is 0.50 (mm), and the width H is 0.304 (mm). Accordingly, the heat generating portion 305h also has a configuration that satisfies t> H as a whole. The cross-sectional area Sh of each transverse section YD of the heat generating portion 305h is equal to the cross-sectional area Sh (= 0.15 mm ² ) of the transverse section YD of the heat generating portions 105h and 205h of the first and second embodiments. The ceramic heater 301 having such a heat generating portion 305h is manufactured in the same manner as in the second embodiment.

  Such a ceramic heater 301 is also configured such that the heat generating portion 305h satisfies t> H, as in the first embodiment. For this reason, the bias of the current density at the time of energization in the heat generating portion 305h can be made smaller than before. Therefore, the deviation of the heat generation temperature of the heat generating portion 305h can be made smaller than before, and the energization durability of the heat generating portion 305h can be improved as compared with the conventional case. Therefore, it is possible to ensure the energization durability of the heat generating portion 305h while realizing low power consumption.

  Further, since the inner side surface 305hc and the outer side surface 305hd of the heat generating portion 305h are tapered surfaces with a taper angle θ1 = θ2 = 0.5 (degrees), a resistor corresponding concave portion including a corresponding heat generating portion corresponding concave portion is formed. In this case, the mold release after pressing becomes good and the productivity can be improved. On the other hand, the heat generating portion 305h has a sufficient volume of the inner portion (the portion on the inner side surface 305hc side). For this reason, since the current density at the time of energization does not increase in this inner portion, it is possible to sufficiently ensure the energization durability of the heat generating portion 305h. In addition, the same parts as those in the first or second embodiment have the same effects as those in the first or second embodiment.

(Embodiment 4)
Next, a fourth embodiment will be described. In the ceramic heater 201 of the second embodiment, the shape of each cross section YD perpendicular to the extending direction ES of the heat generating portion 205h extending in a U shape is a trapezoid, and the taper angle is θ1 = θ2 = 10 (degrees). (See FIG. 23). On the other hand, in the ceramic heater 401 of the fourth embodiment, the shape of each cross section YD orthogonal to the extending direction ES of the heat generating portion 405h extending in a U shape is trapezoidal, and the taper angle is θ1 = θ2 = 25 (degrees). (See FIG. 26). Further, the width H of the heat generating portion 405h is changed in order to make the cross-sectional area Sh of the heat generating portion 405h equal to that of the first to third embodiments. Other than that, since it is the same as in the first to third embodiments, the description of the same parts as in the first to third embodiments will be omitted or simplified.

  As shown in FIG. 26, the heat generating portion 405h of the ceramic heater 401 according to the fourth embodiment includes a first main surface 405ha, a second main surface 405hb parallel to the first main surface 405ha, an inner side surface 405hc and an outer side surface 405hd connecting them. Has been. And the shape of each cross section YD orthogonal to the extending | stretching direction ES of the heat generating part 405h makes trapezoid shape (reverse trapezoid shape). Specifically, the inner side surface 405hc is a tapered surface having a taper angle θ1 generated between the virtual principal plane HV13 passing through the inner edge 405hf1 of the first main surface 405ha and orthogonal to the first main surface 405ha, and forming 25 degrees. is there. The outer side surface 405hd is a tapered surface having a taper angle θ2 formed between the virtual main surface HV23 that passes through the outer edge 405hf2 of the first main surface 405ha and is orthogonal to the first main surface 405ha, and forms 25 degrees.

Further, the thickness t of the heat generating portion 405h is 0.53 (mm), and the width H is 0.510 (mm). Therefore, the heat generating portion 405h is also configured to satisfy t> H as a whole. The cross-sectional area Sh of each cross section YD of the heat generating portion 405h is equal to the cross-sectional area Sh (= 0.15 mm ² ) of the cross section YD of the heat generating portions 105h, 205h, 305h of the first to third embodiments. The ceramic heater 301 having such a heat generating portion 305h is manufactured in the same manner as in the second embodiment.

Such a ceramic heater 401 is also configured such that the heat generating portion 405h satisfies t> H as in the first embodiment. For this reason, the bias of the current density at the time of energization in the heat generating portion 405h can be made smaller than before. Therefore, the deviation of the heat generation temperature of the heat generating portion 405h can be made smaller than before, and the energization durability of the heat generating portion 405h can be improved than before. Therefore, it is possible to ensure the durability of energization of the heat generating portion 405h while realizing low power consumption.
In addition, since the inner side surface 405hc and the outer side surface 405hd of the heat generating portion 405h are tapered surfaces, when forming the resistor corresponding concave portion including the corresponding heat generating portion corresponding concave portion, the mold release after pressing becomes good and the production is improved. Can be improved. In addition, the same parts as in the first to third embodiments have the same effects as the first to third embodiments.

(Embodiment 5)
Next, a fifth embodiment will be described. In the ceramic heater 201 of the second embodiment, the shape of each cross section YD perpendicular to the extending direction ES of the heat generating portion 205h extending in a U shape is a trapezoid, and the taper angle is θ1 = θ2 = 10 (degrees) ( (See FIG. 23). On the other hand, in the ceramic heater 501 of the fifth embodiment, the shape of each cross section YD orthogonal to the extending direction ES of the heat generating portion 505h extending in a U shape is a trapezoid, and the taper angle is θ1 = θ2 = 5 (degrees). (See FIG. 27). In addition, the thickness t and the width H of the heat generating portion 505 are changed in order to make the cross-sectional area Sh of the heat generating portion 505h equal to that of the first to fourth embodiments. The rest is the same as in the first to fourth embodiments, and the description of the same parts as in the first to fourth embodiments is omitted or simplified.

  As shown in FIG. 27, the heat generating portion 505h of the ceramic heater 501 of Embodiment 5 includes a first main surface 505ha, a second main surface 505hb parallel to the first main surface 505ha, an inner side surface 505hc and an outer side surface 505hd connecting them. Has been. And the shape of each cross section YD orthogonal to the extending | stretching direction ES of the heat generating part 505h makes trapezoid shape (reverse trapezoid shape). Specifically, the inner side surface 505hc has a taper angle θ1 generated between the virtual principal plane HV14 passing through the inner edge 505hf1 of the first main surface 505ha and orthogonal to the first main surface 505ha, and is 0.5 degrees or more and 20 degrees. It is a tapered surface that: Specifically, the taper angle θ1 = 5 (degrees). The outer side surface 505hd is a tapered surface that has a taper angle θ2 between 0.5 degrees and 20 degrees that is formed between the virtual principal plane HV24 that passes through the outer edge 505hf2 of the first main surface 505ha and is orthogonal to the first main surface 505ha. It is. Specifically, the taper angle θ2 = 5 (degrees).

Further, the thickness t of the heat generating portion 505h is 0.75 (mm), and the width H is 0.262 (mm). Therefore, the heat generating portion 505h also has a configuration that satisfies t> H as a whole. The cross-sectional area Sh of each cross section YD of the heat generating portion 505h is equal to the cross-sectional area Sh (= 0.15 mm ² ) of the cross section YD of the heat generating portions 105h, 205h, 305h, and 405h of the first to fourth embodiments. The ceramic heater 501 having such a heat generating portion 505h is manufactured in the same manner as in the second embodiment.

  The ceramic heater 501 is also configured such that the heat generating portion 505h satisfies t> H, as in the first embodiment. For this reason, the bias of the current density at the time of energization in the heat generating portion 505h can be made smaller than before. Therefore, the deviation of the heat generation temperature of the heat generating portion 505h can be made smaller than before, and the energization durability of the heat generating portion 505h can be improved than before. Therefore, it is possible to ensure the durability of energization of the heat generating portion 505h while realizing low power consumption.

  Further, since the inner side surface 505hc and the outer side surface 505hd of the heat generating portion 505h are tapered surfaces having a taper angle θ1 = θ2 = 5 (degrees), when forming a resistor corresponding concave portion including a corresponding heat generating portion corresponding concave portion. Moreover, the mold release after pressing becomes good, and the productivity can be improved. On the other hand, the volume of the inner part (the part on the inner side surface 505hc side) of the heat generating part 505h is sufficiently secured. For this reason, since the current density at the time of energization does not increase in this inner portion, the energization durability of the heat generating portion 505h can be sufficiently ensured. In addition, the same part as the said Embodiment 1-4 has an effect similar to the said Embodiment 1-4.

(Embodiment 6)
Next, a sixth embodiment will be described. In the ceramic heater 201 of the second embodiment, the shape of each cross section YD perpendicular to the extending direction ES of the heat generating portion 205h extending in a U shape is a trapezoid, and the taper angle is θ1 = θ2 = 10 (degrees) ( (See FIG. 23). On the other hand, in the ceramic heater 601 of the sixth embodiment, the shape of each cross section YD orthogonal to the extending direction ES of the heat generating portion 605h extending in a U shape is trapezoidal, but one of the taper angles is θ1 = 5. (Degrees) and the other taper angle is made different from θ2 = 10 (degrees) (see FIG. 28). Further, the thickness t and the width H of the heat generating portion 605 are changed in order to make the cross-sectional area Sh of the heat generating portion 605 h equal to those of the first to fifth embodiments. The rest is the same as in the first to fifth embodiments, and therefore, the description of the same parts as in the first to fifth embodiments is omitted or simplified.

  As shown in FIG. 28, the heat generating portion 605h of the ceramic heater 601 according to the sixth embodiment includes a first main surface 605ha, a second main surface 605hb parallel to the first main surface 605ha, an inner side surface 605hc connecting these, and an outer side surface 605hd. Has been. And the shape of each cross section YD orthogonal to the extending | stretching direction ES of the heat generating part 605h makes trapezoid shape (reverse trapezoid shape). Specifically, the inner side surface 605hc has a taper angle θ1 generated between the virtual principal plane HV15 passing through the inner edge 605hf1 of the first main surface 605ha and orthogonal to the first main surface 605ha, and is 0.5 degrees or more and 20 degrees. It is a tapered surface that: Specifically, the taper angle θ1 = 5 (degrees). The outer side surface 605hd is a tapered surface that has a taper angle θ2 between 0.5 degrees and 20 degrees that is formed between the virtual principal plane HV25 passing through the outer edge 605hf2 of the first main surface 605ha and orthogonal to the first main surface 605ha. It is. Specifically, the taper angle θ2 = 10 (degrees).

Further, the thickness t of the heat generating portion 605h is 0.5 (mm), and the width H is 0.367 (mm). Therefore, the heat generating portion 605h is also configured to satisfy t> H as a whole. The cross-sectional area Sh of each cross section YD of the heat generating portion 605h is equal to the cross-sectional area Sh (= 0.15 mm ² ) of the cross section YD of the heat generating portions 105h, 205h, 305h, 405h, and 505h of the first to fifth embodiments. The ceramic heater 601 having such a heat generating portion 605h is manufactured in the same manner as in the second embodiment.

  Such a ceramic heater 601 is also configured such that the heat generating portion 605h satisfies t> H, as in the first embodiment. For this reason, the bias of the current density at the time of energization in the heat generating portion 605h can be made smaller than before. Therefore, the deviation of the heat generation temperature of the heat generating portion 605h can be made smaller than before, and the energization durability of the heat generating portion 605h can be improved as compared with the conventional case. Therefore, it is possible to ensure the durability of energization of the heat generating portion 605h while realizing low power consumption.

  Further, the inner side surface 605hc and the outer side surface 605hd of the heat generating portion 605h are tapered surfaces. In particular, in the sixth embodiment, the two taper angles θ1 and θ2 are made different from each other so that the outer taper angle is relatively large as θ2 = 10 (degrees). When forming the resistor-corresponding recess, the mold release after pressing becomes good, and the productivity can be particularly improved. On the other hand, since the inner taper angle is relatively small as θ1 = 5 (degrees), the heat generating portion 605h has a sufficient volume of the inner portion (the portion on the inner side surface 605hc side). For this reason, since the current density at the time of energization does not increase in the inner portion, the energization durability of the heat generating portion 605h can be sufficiently ensured. In addition, the same part as the said Embodiments 1-5 has an effect similar to the said Embodiments 1-5.

(Comparative form 1)
Next, the first comparative form will be described. In the ceramic heater 101 of the first embodiment, the shape of each cross section YD orthogonal to the extending direction ES of the heat generating portion 105h extending in a U shape is a rectangular shape satisfying t> H (see FIG. 8). On the other hand, in the ceramic heater according to comparative example 1, the shape of each cross section YD orthogonal to the extending direction ES of the heat generating portion 805h extending in a U shape is a rectangular shape satisfying H> t (see FIG. 29). . Other than that, the second embodiment is the same as the first embodiment, and the description of the same parts as the first embodiment is omitted or simplified.

  As shown in FIG. 29, the heat generating portion 805h of the comparative form 1 includes a first main surface 805ha, a second main surface 805hb parallel to the first main surface 805ha, and an inner side surface 805hc and an outer side surface 805h connecting them. And in each cross section YD orthogonal to the extending | stretching direction ES of the heat generating part 805h, thickness t is 0.15 (mm) and width H is 1.000 (mm). Therefore, unlike the first to fifth embodiments, the heat generating portion 805h is configured to satisfy H> t.

(Comparative form 2)
Next, the second comparative form will be described. In the ceramic heater 201 of the second embodiment, the shape of each cross section YD perpendicular to the extending direction ES of the heat generating portion 205h extending in a U shape is a trapezoidal shape satisfying t> H (see FIG. 23). On the other hand, in the ceramic heater according to Comparative Example 2, the shape of each cross section YD orthogonal to the extending direction ES of the heat generating portion 905h extending in a U shape is a trapezoidal shape satisfying H> t (see FIG. 30). . Other than that, the second embodiment is the same as the second embodiment, and the description of the same parts as the second embodiment is omitted or simplified.

As shown in FIG. 30, the heat generating portion 905 h of the comparative form 2 includes a first main surface 905 ha, a second main surface 905 hb parallel to the first main surface 905 ha, and an inner side surface 905 hc and an outer side surface 905 hd that connect them. And the shape of each cross section YD orthogonal to the extending | stretching direction ES of the heat generating part 905h makes trapezoid shape (reverse trapezoid shape). Specifically, the inner side surface 905hc is a tapered surface having a taper angle θ1 of 10 degrees generated between the first main surface 905ha and the virtual orthogonal surface HV15 that passes through the inner edge 905hf1 of the first main surface 905ha and is orthogonal to the first main surface 905ha. . The outer side surface 905hd is a tapered surface having a taper angle θ2 of 10 degrees generated between the first main surface 905ha and the virtual orthogonal surface HV25 orthogonal to the first main surface 905ha through the outer edge 905hf2.
Further, the thickness t of the heat generating portion 905h is 0.20 (mm), and the width H is 0.780 (mm). Accordingly, the heat generating portion 905h is configured to satisfy H> t, as in the first comparative example.

(Example)
Subsequently, the result of the test conducted in order to verify the effect of this invention is demonstrated. As Examples 1 to 7, as shown in Table 1, seven types of ceramic heaters were prepared in which the thickness t, width H, and taper angles θ1 and θ2 of the heat generating portion were changed. Specifically, as Example 1, the ceramic heater 101 of Embodiment 1 was prepared. Further, as Example 2, the ceramic heater 201 of the second embodiment was prepared. Further, as Example 3, the ceramic heater 301 according to the third embodiment was prepared. Further, as Example 4, the ceramic heater 401 according to the fourth embodiment was prepared. As Example 5, the ceramic heater 501 of the fifth embodiment was prepared. Furthermore, as Example 6, a ceramic heater having a thickness t = 0.50 (mm), a width H = 0.340 (mm), and a taper angle θ1 = θ2 = 5 (degrees) was prepared. As Example 7, a ceramic heater having a thickness t = 0.50 (mm), a width H = 0.468 (mm), and a taper angle θ1 = θ2 = 20 (degrees) was prepared.

  Further, as Comparative Examples 1 and 2, as shown in Table 1, two types of ceramic heaters were prepared in which the thickness t, width H, and taper angles θ1 and θ2 of the heat generating portion were changed. Specifically, as Comparative Example 1, the ceramic heater of Comparative Example 1 was prepared. Further, as Example 2, the ceramic heater of Comparative Example 2 was prepared.

  About the ceramic heater of each Examples 1-7 and Comparative Examples 1 and 2, an energization durability test was done. Specifically, a voltage at 1000 ° C. is applied after 1 second of energization, and the voltage is maintained until 1400 ° C. thereafter. When the temperature reaches 1400 ° C., the energization is turned off, and the ceramic heater is forcibly cooled with air for 30 seconds. This cycle was repeated. Then, after 15,000 cycles, after 30,000 cycles, after 50,000 cycles, after 75,000 cycles, after 100,000 cycles, the resistance value of the heating resistor is examined, and the resistance value is before the test starts. When the resistance value changed by 10% or more, it was judged as rejected (NG).

  As a result, the ceramic heaters of Comparative Examples 1 and 2 were already rejected when 15,000 cycles were completed. On the other hand, although the ceramic heater 401 of Example 4 failed at the time of finishing 50,000 cycles, it was good until after 30,000 cycles. Moreover, the ceramic heaters of Examples 1 to 3 and 5 to 7 other than these were good even after 100,000 cycles were performed.

From this, it can be seen that the current-carrying durability is improved by changing the form of the heat generating part to a form satisfying t> H. In addition, it can be seen that by setting the taper angles θ1 and θ2 to 20 degrees or less, the energization durability is further improved.
As a result of investigating the cause of the resistance value change, Cr agglomeration and Er migration were observed in the heat generating portion in the heat generating resistor whose resistance value changed significantly. In some cases, cracks were observed in the heat generating part. It is considered that the current flow concentrates on the inner part of the heat generating part and that the inner part is located closer to the inside of the ceramic heater, so that the internal temperature rises to cause such a problem.

  Next, 50 ceramic heaters of Examples 1 to 7 and Comparative Examples 1 and 2 were manufactured, and the yield in the first unsintered insulating base press molding process was examined. Specifically, the yield was determined by judging pass / fail by the shape of the recess corresponding to the heat generating portion after pressing. In addition, the ceramic heater of the comparative form 1 is excluded from this investigation because an unfired heating part is formed on the main surface of the first unfired substrate.

  As a result, the taper angle θ1 = θ2 = 0 (degrees), that is, in the ceramic heater 101 of Example 1 in which the inner side surface and the outer side surface are not tapered surfaces, the yield was 32%. Moreover, in the ceramic heater 301 of Example 3 with the taper angle θ1 = θ2 = 0.5 (degrees), the yield was 94%. Moreover, in the ceramic heaters (Examples 2, 4 to 7 and Comparative Examples 1 and 2) having the taper angles θ1 and θ2 of 5 degrees or more, the yield was 98% to 100%. From this, it can be seen that the yield is significantly improved by setting the taper angles θ1 and θ2 to 0.5 degrees or more, more preferably 5 degrees or more.

  From the above test results, in order to improve the yield while sufficiently securing the energization durability of the heat generating portion, the heat generating portion is configured to satisfy t> H and the taper angles θ1, θ2 are used. It is good to set it as the form which becomes 0.5 degree or more and 20 degrees or less.

In the above, the present invention has been described with reference to the first to sixth embodiments. However, the present invention is not limited to the above-described first to sixth embodiments, and may be appropriately modified and applied without departing from the gist thereof. Needless to say, it can be done.
For example, in the first embodiment and the like, the first unsintered insulating base 151 is formed, and the first unsintered heating resistor 261 is printed on the first unsintered insulating base 151, while the second unsintered insulating base 153 is formed separately from these. In addition, the second unfired heating resistor 263 is printed and formed thereon. Thereafter, these are integrated to form an unfired ceramic heater 170.

However, a method in which the second unfired heating resistor 263 is not formed may be employed. That is, the first unsintered heat generating resistor corresponding to the entire fired heating resistor is formed on the first unsintered insulating substrate, and the second unsintered heating resistor is not formed on the first unsintered heating base. (2) A method of forming an unfired ceramic heater by stacking and integrating unfired insulating substrates.
Furthermore, a method in which the second unsintered insulating base 153 is not separately formed may be employed. That is, a portion corresponding to the second unsintered insulating substrate is formed by placing ceramic particles on the first main surface of the first unsintered insulating substrate on which the first unsintered heating resistor is formed by printing. Is formed directly to form an unfired ceramic heater.

1 is a longitudinal sectional view of a glow plug according to Embodiment 1. FIG. 1 is a longitudinal sectional view of a ceramic heater according to Embodiment 1. FIG. It is the fragmentary longitudinal cross-sectional view seen from the direction orthogonal to FIG. 2 of the ceramic heater which concerns on Embodiment 1. FIG. FIG. 3 is a cross-sectional view of the ceramic heater according to Embodiment 1 taken along the line A-A ′ in FIG. 2. FIG. 3 is a partial enlarged cross-sectional view showing a tip portion of FIG. 2 of the ceramic heater according to the first embodiment. It is a partial expanded sectional view which shows the front-end | tip part of FIG. 3 of the ceramic heater which concerns on Embodiment 1. FIG. It is a top view which shows the front-end | tip vicinity of the heat generating part of a heat generating resistor among the ceramic heaters concerning Embodiment 1. FIG. FIG. 8 is a B-B ′ cross-sectional view of the heat generating portion of the heat generating resistor in the ceramic heater according to Embodiment 1 in FIG. 7. It is the top view seen from the 1st principal surface side of the 1st non-baking insulation base | substrate regarding the manufacturing method of the ceramic heater which concerns on Embodiment 1. FIG. FIG. 12 is a view showing a longitudinal section of the first unsintered insulating substrate, and is a C-C ′ longitudinal section view in FIGS. 9 and 11, regarding the method for manufacturing the ceramic heater according to the first embodiment. It is a figure which shows the cross section of a 1st non-baking insulation base | substrate regarding the manufacturing method of the ceramic heater which concerns on Embodiment 1, and is D-D 'transverse cross section in FIG.9 and FIG.10. FIG. 10 is a partially enlarged cross-sectional view showing the vicinity of the heat generating portion corresponding concave portion of the first resistor corresponding concave portion of the first unsintered insulating base, with respect to the method for manufacturing the ceramic heater according to the first embodiment. is there. It is explanatory drawing which shows a mode that the 1st non-baking electroconductive ceramic paste is printed by mounting a 1st metal mask on the 1st non-baking insulating base | substrate regarding the manufacturing method of the ceramic heater which concerns on Embodiment 1. FIG. Regarding the method for manufacturing a ceramic heater according to the first embodiment, the first unfired conductive ceramic paste is printed and filled in the first resistor-corresponding recess of the first unfired insulating base and the first through hole of the first metal mask. It is explanatory drawing which shows a mode. It is a figure which shows a mode that the unsintered heat generation part was printed-formed in the 1st heat_generation | fever corresponding recessed part etc. of the 1st resistor corresponding | compatible recessed part of a 1st unbaking insulated base regarding the manufacturing method of the ceramic heater which concerns on Embodiment 1. FIG. FIG. 13 is an explanatory diagram corresponding to FIG. 12. It is the top view seen from the 2nd main surface side of the 2nd non-baking insulation base | substrate regarding the manufacturing method of the ceramic heater which concerns on Embodiment 1. FIG. FIG. 19 is a view showing a longitudinal cross section of a second unsintered insulating substrate in the method for manufacturing a ceramic heater according to Embodiment 1, and is a cross-sectional view taken along line F-F ′ in FIGS. 16 and 18. It is a figure which shows the cross section of the 2nd non-baking insulation base | substrate regarding the manufacturing method of the ceramic heater which concerns on Embodiment 1, and is G-G 'sectional drawing in FIG.16 and FIG.17. It is explanatory drawing which shows a mode that the 2nd non-baking electroconductive ceramic paste is printed by mounting a 2nd metal mask on the 2nd non-fired insulating base | substrate regarding the manufacturing method of the ceramic heater which concerns on Embodiment 1. FIG. Regarding the method for manufacturing the ceramic heater according to the first embodiment, the second unfired conductive ceramic paste is printed and filled in the second resistor-corresponding concave portion of the second unfired insulating base and the second through hole of the second metal mask. It is explanatory drawing which shows a mode. It is explanatory drawing which shows a mode that the 1st unbaking insulation base | substrate after a 1st printing process and the 2nd unbaking insulation base | substrate after a 2nd printing process are match | combined regarding the manufacturing method of the ceramic heater which concerns on Embodiment 1. FIG. It is explanatory drawing which shows a mode that the unfired ceramic heater was formed by integrating the 1st unbaking insulation base | substrate, the 2nd unbaking insulation base | substrate, etc. regarding the manufacturing method of the ceramic heater which concerns on Embodiment 1. FIG. FIG. 9 is a transverse cross-sectional view of a heat generating portion of a heating resistor in a ceramic heater according to Embodiment 2, corresponding to FIG. 8 in Embodiment 1. FIG. 6 is an explanatory diagram showing a state in which an unfired heat generating portion is printed and formed in a first heat generating portion corresponding recess of a first resistor corresponding recess of a first unfired insulating base, with respect to a ceramic heater manufacturing method according to Embodiment 2. is there. FIG. 9 is a cross-sectional view of a heat generating portion of a heat generating resistor in a ceramic heater according to a third embodiment, corresponding to FIG. 8 in the first embodiment. FIG. 9 is a cross-sectional view of a heat generating part of a heat generating resistor in a ceramic heater according to a fourth embodiment, corresponding to FIG. 8 in the first embodiment. FIG. 9 is a cross-sectional view of a heat generating portion of a heating resistor in a ceramic heater according to Embodiment 5, corresponding to FIG. 8 in Embodiment 1. FIG. 9 is a cross-sectional view of a heat generating portion of a heating resistor in a ceramic heater according to Embodiment 6, corresponding to FIG. 8 in Embodiment 1. It is a cross-sectional view of the heat generating part of the heat generating resistor in the ceramic heater according to the comparative embodiment 1, and is a view corresponding to FIG. 8 in the first embodiment. It is a cross-sectional view of the heat generating part of the heat generating resistor in the ceramic heater according to the comparative example 2, and is a view corresponding to FIG. 8 in the first embodiment. It is explanatory drawing which shows the difference in the high temperature heat_generation | fever part of the ceramic heater which concerns on this invention, and the ceramic heater which concerns on a prior art.

Explanation of symbols

100 Glow plugs 101, 201, 301, 401, 501, 601 Ceramic heater 101s Tip 101k Base end 103 Insulating substrate 103s Tip 103k Base 105, 205, 305, 405, 505, 605 Heating resistors 105h, 205h , 305h, 405h, 505h, 605h, 805h, 905h Heat generating part 105hs Intermediate part 105hk1, 105hk2 End part 105r1, 105r2 Lead part 105rc1, 105rc2 Rod-like part 105re1, 105re2 Connecting part 151, 251 First unsintered insulating base 151a, 251a 1 main surface 151j, 251j 1st resistor corresponding recessed part 151ja, 251ja Heat generating part corresponding recessed part 151jab, 251jab Bottom surface 151jac, 251jac Inner wall surface 151jad, 251jad Outside Wall surface 151jaf1, 251jaf1 Inner opening edge 151jaf2, 251jaf2 Outer opening edge 151jb First lead corresponding recess 161, 261 First unfired heating element 161h, 261h Unfired heating part 161r First unfired lead part 170 Unfired ceramic heater AX Axis HH Virtual reference plane ES Stretching direction YD Cross section HW1, HW2 Virtual opening edge orthogonal plane Sh, Sr Cross section H, H2 Width H1 Opening width t, t2 Thickness t1 Depth θ1, θ2, θ11, θ21 Taper angle

Claims (5)

An insulating base made of insulating ceramic and extending in the axial direction from its base end to its tip,
Embedded in the distal end portion of the insulating base and made of conductive ceramic, and a heat generating portion that generates heat when energized, and embedded in the insulating base, extends from the heat generating portion to the proximal side in the axial direction, and energizes the heat generating portion. A heating resistor having a lead portion,
A ceramic heater comprising:
The heating part is
Bent back in a U-shape along a virtual reference plane including the axis, and
It has a form in which the form of each cross section orthogonal to the extending direction in which it extends is the same,
The intermediate part located between the two end parts is arranged in a posture that becomes the tip end side in the axial direction from the two end parts,
A dimension in a direction perpendicular to the virtual reference plane of the heat generating portion is a thickness t (mm),
When the dimension of the heat generating portion along the virtual reference plane and perpendicular to the extending direction is a width H (mm),
A ceramic heater in which the heat generating portion is configured to satisfy t> H. The ceramic heater according to claim 1,
The heating resistor is a ceramic heater made entirely of conductive ceramic. The ceramic heater according to claim 2,
The heating resistor is entirely made of a conductive ceramic having the same composition,
The lead portion is
A pair of rod-shaped portions having a straight rod shape extending in the axial direction and having a shape in which the cross-sectional shapes perpendicular to the axial direction are the same;
A connecting portion that is located between the rod-shaped portion and the end portion of the heat generating portion and connects the two, and a pair of connecting portions having a smaller dimension in the axial direction than the rod-shaped portion and the heat generating portion; Have
When the cross-sectional area of the cross section of the heat generating portion is Sh (mm ² ), and the cross-sectional area of the cross section of the rod-shaped portion of the lead portion is Sr (mm ² ),
The heating resistor is a ceramic heater configured to satisfy 1 / 25.5 ≦ Sh / Sr ≦ 1 / 2.6. An insulating base made of insulating ceramic and extending in the axial direction from its base end to its tip,
A heat generating portion embedded in the tip portion of the insulating substrate and generating heat by energization, each bent back in a U shape along a virtual reference plane including the axis, and each orthogonal to the extending direction in which it extends A heat generating portion having a configuration in which the cross-sectional shape is the same as each other, and an intermediate portion located between two end portions is disposed in a posture that is closer to the tip end side in the axial direction than the two end portions, as well as,
A lead portion embedded in the insulating base, extending from the heat generating portion to the base end side in the axial direction, and energizing the heat generating portion;
A heating resistor made entirely of conductive ceramic;
A method of manufacturing a ceramic heater comprising:
It is made of unsintered insulating ceramic, and is a concave portion corresponding to the main surface and a concave portion formed on the main surface, and having an opening shape corresponding to the heat generating resistor, and has a U shape corresponding to the heat generating portion. A non-fired substrate press-molding step of press-molding a non-fired insulating substrate that has a resistor-corresponding concave portion including at least a heat generating portion-corresponding concave portion having an opening shape and becomes a part of the insulating substrate after firing,
When the depth of the heat generating portion corresponding recess is t1 (mm) and the distance between the inner opening edge and the outer opening edge of the heat generating portion corresponding recess is the opening width H1 (mm), a form satisfying t1> H1 An unsintered substrate press-molding step for forming the resistor-corresponding recess including the heat-generating-corresponding recess;
At least one of the unsintered heat generating portion that becomes the heat generating portion after firing, and at least one of the lead portions after firing, is obtained by printing and filling the resistor-corresponding recess of the unsintered insulating substrate by screen printing. A printing step of forming an unsintered heating resistor comprising a non-sintered lead portion to be a part and forming part or all of the exothermic resistor after firing,
The dimension of the unfired heat generating part in the direction perpendicular to the main surface is a thickness t2 (mm), and the dimension of the unfired heat generating part in the direction perpendicular to the extending direction along the main surface of the unfired heat generating part. Is a width H2 (mm), a printing process for forming an unfired heating resistor including the unfired heating part in a form satisfying t2> H2,
A firing step of forming the ceramic heater by firing an unfired ceramic heater that becomes the ceramic heater after firing using the unfired insulating substrate and the unfired heating resistor after the printing step. When,
A method of manufacturing a ceramic heater comprising: It is a manufacturing method of the ceramic heater of Claim 4, Comprising:
In the green substrate press molding process,
Among the wall surfaces constituting the heat generating portion corresponding concave portion, the inner wall surface extending in the depth direction of the heat generating portion corresponding concave portion from the inner opening edge is a taper surface toward the outer opening edge side as proceeding in the depth direction, A method for manufacturing a ceramic heater, wherein a taper angle generated between a virtual opening edge orthogonal plane passing through the inner opening edge and orthogonal to the main surface is 0.5 degrees or more and 20 degrees or less.

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