JP2012023019A - Ceramic heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ceramic heater in which the slackness or slipping-off of a ceramic heating body is hard to occur even at high temperature, and having high reliability.SOLUTION: A ceramic heater 1 is equipped with a ceramic heating body 10 heating by energization, and heating body installing means 3 placing a heating portion at a tip end of the ceramic heating body 10 in an installed portion 60. The ceramic heater 1 comprises a heating body joining means 20 joining the ceramic heating body 10 and the heating body holding member 31 at a position on a base end side rather than a stress generating area ARin which stress is generated when an installing means side screw portion 302 provided on a heating body installing member 30 constituting the heating body installing means 3, an installing means side seal portion 314 provided on a heating body holding member 31 constituting the heating body installing means 3 by screwing with a installed side screw portion 611 provided on an installed portion 60, and an installed portion side tapered portion 612 provided on the installed portion 60 are made to abut on each other.

Description

  The present invention relates to a ceramic heater fixed to a flow path wall of a fluid to be heated and generating heat by energization to heat the fluid to be heated. For example, an ignition source of a combustion heater, a glow plug of a diesel engine, an exhaust gas purification device It is suitable as a heat source for temperature.

  As this type of ceramic heater, Patent Document 1 discloses that the above-mentioned hole is provided for a mounted part having a hole part in which a mounted part side tapered part whose inner diameter dimension is continuously reduced in the insertion direction is formed. A ceramic heater that is inserted into and attached to a part, has a heat generating part that generates heat when energized at one end side, and is electrically connected with an energization lead part for supplying current to the heat generating part at the other end side The ceramic heating element is bonded to an outer peripheral surface of the ceramic heating element, and the one end side of the ceramic heating element is exposed from one end and the other end side of the ceramic heating element is exposed from the other end. A mounting housing side sheath having a tapered shape corresponding to the attached portion side tapered portion of the hole portion in the attached portion on the outer peripheral surface of the housing. And the mounting portion that can be fixed to the hole portion are integrally formed, and when the housing is fixed to the hole portion by the mounting portion, the mounting means side seal portion is pressed and the mounted portion A ceramic heater is disclosed that is configured to abut on the side taper portion.

  Patent Document 2 discloses a ceramic heater having a rod-like shape and having a resistance heating element embedded in its own tip, and a metal fitting member attached to the outer peripheral surface of the ceramic heater in an interference fit state. A glow plug is disclosed in which a softer metal layer than the metal fitting member is formed between the metal fitting member and the ceramic heater.

The ceramic heating elements used in these ceramic heaters are known, for example, injection molding using conductive ceramics such as tungsten carbide (WC), molybdenum disilicide (MoSi ₂ ) and tungsten disilicide (WSi ₂ ). By forming a substantially U shape by the above method to form a resistance heating element, a pair of lead portions formed in a predetermined shape using a conductive material such as tungsten (W) is connected to both ends of the resistance heating element, These are covered with an insulating ceramic such as silicon nitride Si ₃ N ₄ and sintered together by a known method such as hot pressing, and then the tip of the lead embedded in the insulating ceramic is insulated by cutting. Is exposed to the surface of the insulating ceramic, plated to form terminal electrodes, and energized to the resistance heating element embedded in the insulating ceramic Is possible.
The ceramic heating element is formed through such a complicated process, and since it has high hardness after sintering and is not easy to cut, it is formed in a relatively simple columnar shape.
For this reason, in the prior art, the ceramic heating element formed in a substantially cylindrical shape is inserted into a metal housing or fitting member formed in a substantially cylindrical shape, and fixed by brazing, interference fitting, or the like. The heat generating portion is fixed to the attached portion so as to be exposed in the heated fluid.

At this time, as disclosed in Patent Document 1, airtightness is ensured by an attachment means side seal provided in the housing, and leakage of the heated fluid to the outside is prevented.
Furthermore, in the ceramic heater of Patent Document 1, the ceramic heating element and the housing are assembled by shrink fitting or the like, and a brazing material such as silver solder or copper brazing is poured into the gap between the ceramic heating element and the housing. The bonding strength is increased by brazing.

However, in the conventional ceramic heater as disclosed in Patent Document 1, a screw portion and a mounting means side seal are provided on the outer peripheral surface of the housing at a position facing the inner peripheral surface of the housing provided with a joint portion with the ceramic heating element. Are provided. For this reason, when a ceramic heater is mounted on a mounted portion such as a combustion heater or a combustion chamber of an internal combustion engine, the threaded portion is screwed to the mounted portion, and the mounting means side seal portion is mounted on the mounted portion. If it is in contact with the taper part on the part side and pressed by screw tightening, stress is generated inside the housing, which acts on the joint part of the housing, and there is a possibility that the joint force with the ceramic heating element may be reduced. It became clear by the inventors' earnest test.
Furthermore, when heating and cooling of the ceramic heater are repeated, the bonding force between the ceramic heating element and the housing gradually decreases, and the ceramic heating element may loosen or come off.

On the other hand, when the ceramic heating element is held by fitting through a soft metal layer formed by plating or the like between the ceramic heating element and the metal fitting member as disclosed in Patent Document 2, the soft metal layer It is possible to prevent the ceramic heating element from being damaged by suppressing the excessive interference fitting load during the manufacturing process, but the ceramic heating element and the metal fitting member are held by fitting. However, no joining means such as brazing is provided.
For this reason, when the ceramic heater is screwed to the mounted portion, the housing is compressed and slippage occurs between the ceramic heating element and the metal fitting member, and the ceramic heating element may loosen or come off. is there.
Furthermore, when energized, the fitting holding force is reduced due to the difference between the thermal expansion coefficient of the ceramic heating element and the thermal expansion coefficient of the metal fitting member, and the ceramic heating element is further loosened and pulled out compared to the case of joining by brazing. There is a possibility that it becomes easy to do.

  Therefore, in view of such circumstances, the present invention maintains the original bonding strength without deteriorating the bonding strength between the housing and the ceramic heating element when the ceramic heater is assembled to the mounted portion, and the ceramic heater even at high temperatures. It is an object of the present invention to provide a highly reliable ceramic heater in which a heating element does not easily loosen or come off.

  In the first invention, a ceramic heating element that is connected to an energization device provided outside via an energization line and generates heat by energization, and a heat generating portion located on the tip side thereof are mounted in a heated fluid inside the attached portion. In the ceramic heater comprising the heating element mounting means for mounting, the mounted portion includes a mounted portion side screw portion and a mounted portion side tapered portion, and the heating element mounting means is the mounting means. A side screw part, an attachment means side seal part, a heating element insertion hole for inserting the heating element inside, and a heating element joining means for joining the heating element and the heating element attachment means, The heating element is held and fixed in the heating element insertion hole, and the attachment portion side taper portion is attached to the attachment portion side seal portion by screwing the attachment portion side screw portion and the attachment means side screw portion. The heating element joining means above Characterized in that provided on the base end side than the attachment means sealing section (claim 1).

  In the second invention, the heating element mounting means is disposed on the outer peripheral side and mounted on the mounted portion, and the heating element mounting member is disposed on the inner peripheral side and directly holds the ceramic heating element. The heating element mounting member includes a mounting portion side screw portion, a tightening portion for tightening the screw portion, and the heating element holding member to the mounted portion. And the heating element holding member includes a heating element insertion hole for inserting and holding the ceramic heating element on the inner peripheral side, and a flange portion protruding in the outer diameter direction at one end. One surface of the flange portion is a pressure receiving portion that receives pressure from the pressing portion, and the other surface is the attachment means side seal portion that contacts the attached portion side taper portion. Item 2).

  In a third aspect of the invention, the heating element mounting means is made of a cylindrical member, and has a heating element insertion hole through which the ceramic heating element is inserted on the inner peripheral side, and the mounting means on the outer peripheral side. A side screw portion and a tightening portion for tightening the screw portion, and the mounting means side seal portion includes a substantially conical taper-shaped ridge surface continuously reducing in diameter in the insertion direction, The joining means is arranged further on the proximal end side than the most proximal end side of any one of the attachment member side screw portion and the proximal end portion of the attachment means side seal portion (Claim 3).

  In the fourth invention, the ceramic heating element joining means is a brazing material infiltrated into the gap between the ceramic heating element and the heating element mounting means.

  In a fifth aspect of the invention, the heating element mounting means includes at least a substantially cylindrical heating element holding member and a substantially cylindrical energizing line protection member provided to protect the energizing line, and the energizing line. The distal end portion of the protective member is fixed to the heating element holding member, and the conductive wire is drawn out from the proximal end side of the conductive wire protective member through the sealing member made of an insulating elastic member. The proximal end side of the electric wire protection member is caulked and fixed over the entire circumference together with the sealing member (claim 5).

  In 6th invention, the cylindrical part of the said heat generating body holding member and a conduction wire protection member are fixed by laser welding over the perimeter (Claim 6).

According to the first invention, when the ceramic heater is assembled to the attached portion, a tensile stress is generated in the vicinity of the seal portion. However, the ceramic heater is disposed closer to the proximal end than the attachment means side seal portion. Since this stress does not act on the heating element joining means, the ceramic heater can be attached to the attached portion while maintaining the joining strength at the time of manufacture.
Therefore, a high bonding strength is maintained even when hot, there is no possibility that the ceramic heating element will come off from the ceramic heater, and a highly reliable ceramic heater can be realized.
In addition, since the hot bonding strength is increased, the range of selection of the use environment is widened, and the versatility of the ceramic heater can be expanded.
Furthermore, since the joining means is provided on the base end side with respect to the attachment means-side seal portion, the joining means is substantially separated from the fluid to be heated and is hardly affected by the fluid to be heated. Also, durability can be improved.

According to the second invention, when the ceramic heater is assembled to the mounted portion, the stress generated between the mounting side screw portion and the mounted portion side screw portion is applied only to the heating element mounting member. It does not act on the heating element holding member provided separately from the heating element mounting member.
In addition, according to the present invention, compared to the case where the heating element mounting member and the heating element holding member are integrally formed, the joining range of the heating element joint portion is increased without causing the ceramic heating element to be elongated. It is possible to make the length longer, further suppressing the decrease in the bonding force of the bonding means, and realizing a highly reliable ceramic heater.
In addition, since the heating element mounting member and the heating element holding member are composed of a plurality of cylindrical members, workability when the ceramic heater is assembled to the mounted portion is good.

  According to the third aspect of the invention, the heating element joining means has a base end further than a base end portion located on a more base end side of the base end portions of the mounting means side screw portion and the mounting means side seal portion. When the ceramic heater is assembled to the attached portion and the attaching means side screw portion and the attached portion side screw portion are screwed together, the attaching means side screw is mounted. Stress generated at the site where the mounting portion is formed, or stress generated at the site where the mounting means side seal portion is formed when the mounting means side seal portion is brought into contact with the mounted portion side taper portion. In any case, the ceramic heater can be mounted on the mounted portion while maintaining the bonding strength at the time of manufacture without acting on the heating element bonding means, and there is no possibility that the ceramic heating element will come off, and a highly reliable ceramic. Realization of heater That.

  According to the fourth invention, the ceramic heating element and the heating element mounting means are fixed by fitting, and the gap between them is joined by the brazing material, so that the ceramic heating element is heated only by fitting. Compared to the case where it is held on the body mounting means, the bonding strength is increased, and there is no possibility that the stress generated when the ceramic heater is assembled to the mounted portion will act on the brazed portion, and the brazing strength. Therefore, a highly reliable ceramic heater can be realized.

According to the fifth aspect of the present invention, the energizing line protection member is used to attach the energizing line for energizing the heating element to the externally exposed combustion exhaust passage or the like where water, water, etc. are used in severe environments. In this case, it is possible to realize a robust and more reliable ceramic heater by preventing water and the like from being applied to the connecting portion between the heating element and the conducting wire.
In the present invention, when the heating element mounting member and the heating element holding member are provided separately, the energization line is added to the proximal end side of the energization line protection member via the sealing member. Since it is tightened and fixed, when the ceramic heater is assembled to the mounted portion, the connection state between the heating wire and the heating element due to twisting of the heating wire is prevented, and high reliability is maintained. Is also possible.
Further, in this case, the energization line does not get in the way, and the workability when the ceramic heater is assembled to the attached portion is improved.

  According to the sixth aspect of the present invention, a ceramic heater that is more robust and more reliable can be realized.

Sectional drawing which shows the outline | summary of the ceramic heater in the 1st Embodiment of this invention. The expanded sectional view which shows the principal part of the ceramic heater in the 1st Embodiment of this invention. The characteristic view which shows the effect with respect to the high temperature pull-out strength of the brazing | contacting part of the ceramic heater in the 1st Embodiment of this invention with a comparative example. Explanatory drawing which shows the outline | summary of the manufacturing method of the ceramic heater in the 1st Embodiment of this invention. Explanatory drawing following FIG. Explanatory drawing which shows the attachment method of the ceramic heater in the 1st Embodiment of this invention. Sectional drawing which shows the modification of the ceramic heater in the 1st Embodiment of this invention. Sectional drawing which shows the other modification of the ceramic heater in the 1st Embodiment of this invention. Sectional drawing which shows the ceramic heater in the 2nd Embodiment of this invention. Sectional drawing which shows the other modification of the ceramic heater in the 2nd Embodiment of this invention. Sectional drawing which shows the outline | summary of the ceramic heater in the 3rd Embodiment of this invention. Sectional drawing which shows the modification of the ceramic heater in the 3rd Embodiment of this invention. Sectional drawing which shows the outline | summary of the ceramic heater in the 4th Embodiment of this invention. Sectional drawing which shows the outline | summary of the conventional ceramic heater shown as a comparative example.

With reference to FIG.1 and FIG.2, the ceramic heater 1 in the 1st Embodiment of this invention is demonstrated. In the present invention, the energization device side (not shown) connected to the ceramic heater 1 is referred to as a base end side, and the attached portion 60 side where the ceramic heater 1 is inserted and fixed is referred to as a front end side.
The ceramic heater 1 according to the present embodiment is mounted and fixed so that the heat generating part is exposed to the heated fluid in the attached part 60 to which the ceramic heater 1 is attached, and an energization line is connected to an unillustrated energizing device provided outside. 114 and 124 are connected to generate heat when energized, and are used to heat the heated fluid 600 in the attached portion 60.
For example, combustion exhaust discharged from an internal combustion engine is heated to be used as a heat source for regeneration of an exhaust purification device, or used as an ignition source for a combustion heater that heats cooling water in a diesel vehicle having a cold district specification. It is suitable for assisting the ignition of the.

  The ceramic heater 1 serves as a heating element mounting means for placing the ceramic heating element 10 that generates heat upon energization and the heating section located on the tip side of the ceramic heating element 10 in the heated fluid 600 in the mounted section 60. A mounted portion side screw portion provided on the mounted portion 60 side, which is configured by the provided housing 3 and the brazed portion 20 provided as a heating element joining means for joining the ceramic heating element 10 and the housing 3. 611 and the attaching means side threaded portion 302 provided on the housing 3 side are screwed together to attach the attaching means side seal portion 314 provided on the housing 3 side to the attached portion side tapered portion 612 provided on the attached portion 60 side. The heating element 10 can be held in an airtight manner in the attached portion 60 by being brought into contact with each other, and the brazing contact portion 20 is provided on the base end side of the attachment means side seal portion 314 of the housing 3. And it is characterized in and.

  Further, in the present embodiment, the housing 3 is screwed with the mounted portion 60 and the heating element mounting member 30 for maintaining airtightness, the heating element holding member 31 for bonding the ceramic heating element 10, and the ceramic heat generation. The mounting means side screw portion 302 provided on the heating element mounting holding member 30 is configured by a plurality of cylindrical members together with the conductive line protection member 32 for protecting the conductive lines 114 and 124 for energizing the body 10. The attachment means side seal portion 314 provided in the heating element holding member 31 that directly holds the heating element 10 when screwed to the attachment portion side screw portion 611 provided in the portion 60 is attached to the attachment portion 60. This prevents the internal stress generated when pressed by the portion-side taper portion 612 from acting on the brazing contact portion 20 and maintains a high bonding strength.

  According to the present invention, it is possible to assemble the brazed portion 20 to the mounted portion 60 without lowering the initial joining strength, and the hot joining strength becomes high. The versatility of the ceramic heater 1 can be expanded.

Furthermore, since the position of the brazing contact portion 20 provided as the heating element joining means is provided on the proximal end side with respect to the stress generation region AR _STR , the brazing contact portion 20 is substantially separated from the heated fluid 600. Thus, it becomes difficult to be affected by the properties and temperature of the heated fluid 600 such as oxidation or reduction of the brazing contact portion 20, and the durability of the ceramic heater 1 can be improved.
Here, the stress generation region AR _STR in the present invention means that when the attachment means side screw portion 302 provided on the heating element attachment member 30 is screwed to the attached portion side screw portion 611 provided on the attached portion 60, A region where tensile stress is generated when the attachment means side seal portion 314 provided on the heating element holding member 31 directly holding the heating element 10 is pressed by the attached portion side tapered portion 612 provided on the attached portion 60. In this embodiment, as shown in FIG. 2, a region partitioned by an alternate long and short dash line corresponds.

A more specific configuration of the housing 3 provided as the heating element mounting means in the present embodiment will be described in detail.
The heating element attachment member 30 is formed of a metal material such as stainless steel in a substantially cylindrical shape to form an attachment portion base 300. On the inner peripheral side of the heating element attachment member 30, a heating element holding member 31, a conductive wire protection member 32, a ceramic heating element 10 and A holding member insertion hole 304 is provided to be inserted concentrically, a hexagonal portion (tightening portion) 301 for tightening the attachment means side screw portion 302 is provided on the proximal end side, and an outer peripheral side on the distal end side is provided on the outer peripheral side. An attachment means side screw portion 302 (male screw) for screwing to the attached portion 60 is provided, and a pressing portion 303 for pressing the pressure receiving portion 313 of the heating element holding member 31 is provided at the most distal end portion.

The heating element holding member 31 is made of a metal material such as stainless steel and is formed in a substantially cylindrical shape having both ends opened and a flange portion 312 projecting in the outer diameter direction at one end, and the heating element holding member base 310 is formed. A heating element insertion hole 311 for inserting the ceramic heating element 10 inside is provided at the center thereof, and a flange part 312 that protrudes in a substantially bowl shape toward the outer diameter direction is provided at the tip side. The base end side surface, which is one surface of the flange portion 312, has a horizontal plane orthogonal to the central axis of the ceramic heater 1, and is pressure-receiving that is pressed by the pressing portion 303 toward the attached portion 60. The attachment means side seal portion 314 having a substantially conical taper-shaped ridge surface continuously reducing in the insertion direction is provided on the tip side surface which is the other surface of the flange portion 312. ing.
Of the inner peripheral wall of the heating element insertion hole 311, a brazing portion 20 is formed in a portion located on the proximal side from the flange portion 312, and the ceramic heating element 10 is joined using a brazing material such as silver brazing or copper brazing. Has been.

  In addition, in order to clarify the formation position of the brazing contact portion 20, the brazing contact portion 20 is shown by a thick line in the figure, but actually, the inner peripheral wall of the heating element insertion hole 311 and the ceramic heating element 10 For example, it is formed of a brazing material that penetrates into an extremely narrow gap of about 0.1 to 0.2 mm, for example, and has a very thin film thickness.

  The energization wire protection member 32 is formed of a metal material such as stainless steel in a substantially cylindrical shape to form an energization wire protection base 320, and the tubular portion 310 of the heating element holding member 31 is inserted into the distal end side. A sealing member 33 into which a pair of energization wires 114 and 124 connected to an external energization control device is inserted is inserted into the base end portion 322 by welding and fixing to the heating element holding member 31. It is crimped and sealed over the entire circumference.

The ceramic heating element 10 includes a substantially U-shaped resistance heating element 100 built in the distal end side of the heat-resistant insulating portion 101 formed in a substantially columnar shape, and a pair of heat generations for conducting the resistance heating element 100 and the outside. The body lead portions 110 and 120 and the heating element electrode portions 111 and 121 that are electrically connected to the heating element lead portions 110 and 120 and are drawn to the surface of the heat-resistant insulating portion 101 are configured.
For the resistance heating element 100, a known conductive ceramic material such as molybdenum disilicide MoSi ₂ , silicon carbide SiC, tungsten carbide WC or the like is used, and for the heat resistant insulating portion 101, a known resistance such as silicon nitride Si ₃ N ₄ is used. An insulating ceramic material is used, and a known conductive metal material such as tungsten W is used for the heating element leads 110 and 120.

The ceramic heating element 10 is formed by forming the resistance heating element 100 and the pair of heating element lead portions 110 and 120 into a desired shape by a known method such as injection molding, and then the resistance heating element 100 and the heating element lead portions 110 and 120. Are disposed at desired positions, and these are integrally covered with the heat-resistant insulating portion 101 and integrally fired at 1700 ° C. to 1800 ° C. by a known molding method such as hot pressing, and then the outer shape is formed. Cutting into a desired shape, the tips of the heating element lead portions 110 and 120 are exposed on the surface of the heat resistant insulating portion 101, and the tips of the heating element lead portions 110 and 120 are heated by a known method such as plating. Body electrode portions 111 and 121 are formed.
Ring-shaped electrode connection fittings 112 and 122 are fitted to the heating element electrode portions 111 and 121, respectively, and the brazing material heated and melted in a slight gap between the heating element electrode portions 111 and 121 and the electrode connection fittings 112 and 122. Is infiltrated and brazed to ensure conduction.

Furthermore, the conductive wire terminal portions 113 and 123 are connected to the electrode connecting fittings 112 and 122, respectively, and the conductive wires 114 and 124 are drawn to the outside by being connected thereto.
Note that a spacer 211 formed of an insulating material such as alumina in a substantially annular shape is inserted between the electrode connection fittings 112 and 122 and the upper end of the cylindrical portion 310 of the heating element holding member 31, so that electrical insulation and heat insulation are achieved. Is secured.

The sealing member 33 is made of an elastic member such as silicon rubber, and holds and fixes the current-carrying wires 114 and 124 and seals the proximal end side of the current-carrying wire protection member 320 to prevent entry of water or the like from the outside. Blocking.
Since the conductive wires 114 and 124 are crimped and fixed on the proximal end side of the conductive wire protection member 320 via the sealing member 33, the conductive wires 114 and 124 are attached when the ceramic heater 1 is assembled to the attached portion 60. The force in the peeling direction does not act on the connection portions (111 to 113, 121 to 123) between the conductive wires 114 and 124 and the heating element 10 due to twisting of the wire, and the connection state between the conductive wires 114 and 124 and the heating element 10 is deteriorated. Can be prevented and high reliability can be maintained.
In addition, since the heating element mounting member 30 and the heating element holding member 31 are provided separately, workability when the ceramic heater 1 is assembled to the mounted portion 60 is also improved.

The attached portion 60 is provided with a heater attaching hole portion 610, the ceramic heater 1 is inserted, and an attached portion side screw portion 611 (female screw portion) is formed on the inner periphery of the heater attaching hole portion 610. A substantially mortar-shaped attached portion side tapered portion 612 whose inner diameter is continuously reduced in the insertion direction is formed on the distal end side of the heater attachment hole portion 610. When the ceramic heater 1 is attached, The provided attachment means side seal portion 314 and the attached portion side tapered portion 612 provided on the attached portion side come into contact with each other to ensure airtightness and prevent the heated fluid 600 from flowing out.
The flange portion 312 has sufficient strength that the pressure receiving portion 313 and the attachment means side seal portion 314 are sandwiched between the pressing portion 303 and the attached portion side taper portion 612 and are not deformed by the compressive force when pressed. The attachment means side seal portion 314 is inclined so that the inclination angle of the attachment means side seal portion 314 is in line contact with the circumference at a position close to the outer periphery of the flange portion 312 when contacting the attached portion side tapered portion 612. The attachment portion side tapered portion 612 is formed at an angle that is looser than the inclination angle.

  In the present invention, since the ceramic heating element 10 and the heating element holding member 31 are not joined within the range where the flange portion 312 is formed, the attachment means side seal portion 314 and the attachment portion side taper portion 612 are connected to each other. Even if contact occurs and stress concentration occurs, the brazing contact portion 20 is not affected, and high airtightness between the attachment means side seal portion 314 and the attached portion side taper portion 612 can be ensured.

As shown in FIG. 2, when the heating element mounting member 30 is screwed, the flange 312 is pressed by the heating element mounting member 30, and the pressing portion 303 on the distal end side of the heating element mounting member 30 and the flange 312. The pressure receiving portion 313 is in contact with each other, and the attachment means side seal portion 314 of the flange portion 312 is in contact with the attached portion side tapered portion 612 of the attached portion 60, thereby ensuring airtightness.
On the other hand, internal stress is generated in the flange portion 312 due to the load from the pressing portion 303 and the attached portion side taper portion 612, but the brazing portion 20 is more than the most proximal end position of the pressing portion 303. Furthermore, since it is provided at the position on the base end side, it is not affected by the stress generated in the flange 312.

Further, stress is also generated in the attaching means side screw portion 302 during tightening. In the present embodiment, the heating element mounting member 30 and the heating element holding member 31 are provided separately, and thus the attaching means. The stress generated in the side screw portion 302 does not act on the brazed portion 20.
For this reason, the bonding strength between the heating element holding portion 31 and the ceramic heating element 10 is not lowered, and the ceramic heater 1 can be fixed to the mounted portion 60 while maintaining the initial bonding strength.

Further, in the present embodiment, in addition to the above-described effects, the use environment such as wetness from the outside, stone splashing, etc. is severe by configuring the conducting wire protection member 32 with a metal material formed in a substantially cylindrical shape. When the combustion exhaust passage or the like is the attached portion 60, the heating element electrode portions 111 and 121, the electrode fittings 112 and 122, the energizing wire terminal portions 113 and 123, etc. are prevented from being wetted, A more reliable ceramic heater 1 can be realized.
Further, in the present embodiment, since the heating element mounting member 30 is provided separately from the heating element holding member 31, in order to assemble the heating element holding member 31 to the mounted portion 60, When the attaching means side screw portion 302 is screwed to the attached portion side screw portion 611, the energization wires 114 and 124 held by the energization wire protection member 32 are not twisted, and the assembly work is easy. Unnecessary load is not generated at the connecting portion between the conductive wires 114 and 124 and the ceramic heating element 10, and there is no possibility of disconnection or the like.

Here, problems of the conventional ceramic heater 1z shown as a comparative example will be described with reference to FIG.
The ceramic heater 1z has a heater mounting hole portion 610z with respect to the mounted portion 60z having the heater mounting hole portion 610z formed with the mounted portion side tapered portion 612z whose inner diameter dimension is continuously reduced in the insertion direction. A pair of ceramic heaters that are inserted into and attached to a heating element, have a resistance heating element 100z that generates heat upon energization on the distal end side exposed to the fluid to be heated, and a pair of elements for energizing the resistance heating element 100z on the proximal end side. The ceramic heating element 10z to which the heating element lead portions 110z and 120z are electrically connected and the outer peripheral surface of the ceramic heating element 10z are joined, and the tip end side of the ceramic heating element 10z is exposed from one end on the heated fluid side, and the other end A housing 30z that covers the ceramic heating element 10z so that the proximal end side of the ceramic heating element 10z is exposed. The mounting means side seal portion 314z having a tapered shape corresponding to the attachment portion side taper portion 612z of the heater attachment hole portion 610z in the attachment portion 60z and the attachment portion provided in the heater attachment hole portion 610z are provided on the outer peripheral surface of the attachment portion 30z. An attachment means side screw portion 302z (male screw) that can be fixed to the attachment portion side screw portion 611z (female screw) is integrally formed, and the housing 30z is fixed to the heater attachment hole portion 610z by the attachment means side screw portion 302z. Further, the attachment means side seal portion 314z is pressed and comes into contact with the attached portion side taper portion 612z.

In addition, the ceramic heating element 10z and the housing 30z are arranged such that a brazing material is disposed in the heating element insertion hole 304z of the housing 30z and the space CV _30z of the housing 30z, and the base side of the ceramic heating element 10z. Then, the spacer 211z is fitted, the spacer 211z is disposed in the space CV _30z , and further, from the base end side of the ceramic heating element 10z, an annular shape is formed on the heating element electrode portion 111z of the ceramic heating element 10z until it contacts the spacer 211z. The electrode connecting fitting 112z is fitted, a brazing material is disposed on the upper end surface thereof, and the annular electrode connecting fitting 122z is fitted on the heating element electrode portion 121z exposed at the base end portion of the ceramic heating element 10z, and the brazing material is provided on the end face. And by heat-treating them, the brazing material arranged in each part melts and the gaps between the members Flow, by which hardens, the ceramic heating element 10z, housing 30z, electrode fittings 112z, is joined to the 122z.
For this reason, as shown in this drawing, most of the brazing contact portion 20z between the ceramic heating element 10z and the housing 30z is between the screw portion 302z provided on the housing 30z and the attachment means side seal portion 314z. It is located in the stress generation region AR _STR , and when the ceramic heater 1z is attached to the attached portion 60z, the internal stress generated by screwing acts on the brazed portion 20z, and the original joining secured at the time of manufacture is achieved. It has been found that there is a possibility that the power may be reduced.

Further, as in the ceramic heater 1z shown as the comparative example, there is a portion where a part of the brazing contact portion 20z deviates from the stress generation region AR _STR. Therefore, when the ceramic heater 1z is assembled to the attached portion 60z, the joining force is increased. The part which falls and the part by which the joining force at the time of manufacture is maintained exist unevenly.
As described above, when a non-uniform portion of the joining strength is generated in the brazed portion 20z, the thermal expansion coefficient of the housing 30z and the thermal expansion coefficient of the ceramic heating element 10z are repeated when the energization and stop of the ceramic heater 1z are repeated. The stress generated due to the difference acts intensively on the portion where the bonding strength of the brazing portion 20z is reduced, the bonding strength further decreases, and the bonding force between the ceramic heating element 10z and the housing 30z gradually decreases, There is a possibility that the ceramic heating element 10z may loosen or come off.

The effects of the present invention will be described with reference to FIG. This figure shows that the ceramic heater 1 of the present invention and, as a comparative example, the conventional ceramic heater 1z shown in FIG. After fixing with the tightening torque of m, change the heating temperature, pull up the ceramic heating element, measure the pulling strength (N) when the pull-out occurs, and change the bonding strength of the brazing joint in a high temperature environment It is the result of investigation.
When the ceramic heater is fixed with a tightening torque of 20 N · m, in the conventional structure, a tensile force of about 6 kN acts as an axial force on the joint portion between the housing and the ceramic heater.
In the case of a ceramic heater with a conventional structure shown as a comparative example in this figure, there is a pullout strength of about 12 kN in a no-load state at room temperature, and a safety factor of 2 is secured, but a tightening of 20 N · m After applying the torque, it has been found that the pull-out strength decreases to 6 kN even at room temperature, and may decrease to 2 kN at 250 ° C., which is the use environment temperature of the ceramic heater.
On the other hand, as shown in the drawing as an example, it was confirmed that the ceramic heater of the present invention hardly changed the pull-out strength before and after application of a tightening torque of 20 N · m.

An example of a method for manufacturing the ceramic heater 1 according to the first embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 4A, the ceramic heating element 10, the spacer 211, and the electrode connection fittings 112 and 122 are sequentially assembled to the heating element holding member 31 formed in a substantially cylindrical shape. It is disposed at a position where it can be electrically connected to the heating element electrode portions 111 and 121, the spacer 211 is in contact with the electrode connection fitting 112, and one end of the heating element holding member 31 is held in contact with the spacer 211, As shown in FIG. 4B, with the top of the ceramic heating element 10 turned upside down, a brazing material such as silver brazing is placed in the gap CV31 formed between the ceramic heating element 10 and the heating element holding member 31. And is melted by heating in the gap formed between the heating element holding member 31 and the ceramic heating element 10 from the pressure receiving portion 313 of the flange 312 to the position where the spacer 211 is disposed. The brazing material impregnated, flange portion 312 is joined to only a predetermined brazing range stress generated does not act when it is pressed, to form a brazed portion 20.

Further, the heating element electrode portions 111 and 121 and the electrode connection fittings 112 and 122 are appropriately brazed so that the brazing material penetrates into the respective gaps, heated and brazed, and further the electrode connection fittings. The conducting wire terminal portions 113 and 123 of the conducting wires 114 and 124 are connected to the 112 and 122, respectively.
In addition, the brazing range is formed by previously forming a metallized layer (not shown) as a base in the necessary range on the ceramic heating element 10 by Ni plating, Cr plating, vapor deposition, etc., and the heat generation of the ceramic due to wetting of the brazing material and the metallized layer. The range of the brazing material flowing in the gap between the body 10 and the heating element holding member 31 can also be controlled.

  Next, as shown in FIG. 5A, the ceramic heating element 10 to which the conductive wires 114 and 124 are connected via the electrode connection fittings 112 and 122 and the conductive wire terminal portions 113 and 123 and the solder provided in a predetermined range. The distal end portion 321 of the conductive wire protection member 32 formed in a substantially cylindrical shape is inserted into the cylindrical portion 310 of the heating element holding member 31 joined by the contact portion 20, and the proximal end portion of the conductive wire protection member 32 is inserted. A sealing member 33 made of an insulating elastic member such as silicon rubber is attached to 322, a pair of conducting wires 114 and 124 are pulled out from the sealing member 33, and the tip 321 holds the heating element over the entire circumference. The member 31 is fixed to the cylindrical portion 310 by laser welding or the like, and the energizing wire protection member 32 is caulked and fixed over the entire circumference along with the sealing member 33 in the caulking portion 323 on the proximal end side.

Next, a method for assembling the ceramic heater 1 in this embodiment will be described with reference to FIG.
The ceramic heating element 10, the heating element holding member 31, and the energizing wire protection member 32 are integrated into a ceramic heater mounting hole 610 provided in the mounting portion 60, and the tip of the ceramic heating element 10 is heated. Exposed in the fluid 600, a substantially cylindrical heating element mounting member 30 is inserted from the proximal end side of the energizing wire protection member 32, and a mounting means side screw portion 302 (male screw) provided on the outer peripheral surface of the heating element removing member 30. ) Is screwed to the attached portion side screw portion 611 (female screw) provided in the heater attaching hole 610 in the attached portion 60.
When the heating element mounting member 30 is fixed to the heater mounting hole 610, the pressure receiving portion 313 of the flange 312 provided in the heating element holding member 31 is pressed by the pressing portion 303 provided at the tip of the heating element mounting member 30. The attachment means side seal part 314 facing the pressure receiving part 313 is pressed and comes into contact with the attached part side taper part 612. Thus, the ceramic heater 1 according to the first embodiment of the present invention shown in FIG. 1 is assembled to the attached portion 60.
At this time, the internal stress generated in the flange portion 312 does not act on the brazed portion 20 where the heating element holding member 31 and the ceramic heating element 10 are bonded, so that it is bonded at the time of assembly like a conventional ceramic heater. There is no risk of a decrease in strength.

A modification 1a of the ceramic heater according to the first embodiment of the present invention will be described with reference to FIG. In the said embodiment, the housing 3 is comprised by the heat generating body attachment member 30, the heat generating body holding member 31, and the conduction wire protection member 32, and the example which comprised the conduction wire protection member 32 by the metal material formed in the substantially cylindrical shape. Although shown, in the present embodiment, the housing 3a is configured by the heating element mounting member 30, the heating element holding member 31a, and the conduction line protection member 32a, and a simple heat-shrinkable tube is used as the conduction line protection member 32a. The difference is the configuration.
In this embodiment, it is not necessary to weld the conducting wire protection member 32 and the heating element holding member 31 or to crimp the base end portion 322 of the conducting wire protection member 32 as in the above-described embodiment.
The ceramic heater 1a according to the present embodiment is suitable for an ignition source of a combustion heater that is used in an environment where there is no risk of being exposed to water. Also in this embodiment, similarly to the above-described embodiment, the tightening torque when assembled to the attached portion 60 does not act on the brazing contact portion 20, and high bonding strength can be maintained.

With reference to FIG. 8, another modification 1b will be described. In the present embodiment, the housing 3b is constituted by the heating element mounting member 30, the heating element holding member 31b, and the energizing wire protection member 32b, and one heating element electrode portion 111b (ground electrode side) of the ceramic heating element 10b generates heat. The body holding member 31b is directly connected to the inner peripheral wall 311b via the brazing contact portion 20b.
With such a configuration, the heating element electrode portion 111b is grounded via the housing 3b, and therefore, the negative (GND) side electrode connection fitting 112, the conductive wire terminal portion 113, and the conductive wire 114 are respectively connected. Can be eliminated, and the manufacturing is further simplified.
In addition, since the size of the ceramic heating element 10b can be reduced, the mountability is improved and the manufacturing cost can be reduced.
Also in this embodiment, it is the same as that of the said embodiment that there is no possibility of causing the fall of the joint strength of the brazing part 20 at the time of an assembly | attachment.

With reference to FIG. 9, the ceramic heater 1c in the 2nd Embodiment of this invention is demonstrated. In the above embodiment, the housing 3 is constituted by a plurality of members including the heating element mounting member 30, the heating element holding member 31, and the conductive wire protection member 32 as a fixing means for assembling the ceramic heating element 10 to the mounted portion 60. However, the present embodiment is different in that the housing 3c is integrally formed in a substantially cylindrical shape.
However, when the ceramic heater 1c is assembled to the mounted portion 60c, the brazing portion 20c as a joining means is formed at a position where the generated stress does not act, and the heating element mounting member 30c and the ceramic heating element 10 are joined. By doing so, the point of suppressing a decrease in bonding strength during assembly is common.

The housing 3c in the present embodiment is formed of a metal material such as stainless steel in a substantially cylindrical shape, and a metal material such as stainless steel is formed in a substantially cylindrical shape to form an attachment portion base 300c. A heating element insertion hole 304c to be inserted is provided, a hexagonal portion (clamping portion) 301c for tightening the attachment means side screw portion 302c is provided on the proximal end side, and a distal end side outer periphery is provided on the attached portion 60c. An attaching means side screw portion 302c (male thread) for screwing is provided, and a substantially conical taper-shaped ridge surface continuously reducing in the insertion direction is provided on the proximal end side of the attaching means side screw portion 302c. The attaching means side seal part 314c which has is provided.
Further, a brazing portion 20c is formed as a ceramic heating element joining means in a portion of the inner peripheral wall of the heating element insertion hole 304c, which is located on the base end side with respect to the attachment means side seal portion 314c. The ceramic heating element 10 is joined using the brazing material.

The ceramic heater 1c has a heater mounting hole portion 610c with respect to the mounted portion 60c having the heater mounting hole portion 610 formed with the mounted portion side taper portion 612c whose inner diameter dimension is continuously reduced in the insertion direction. It is designed to be inserted and attached.
In this embodiment, by forming the brazing portion 20c at a position closer to the base end side than the attachment means side seal portion 314c, the attachment means side screw portion 302c is attached to the attachment portion side screw portion 611c of the attachment portion 60c. There is no possibility that the stress generated when screwing is applied to the brazing portion 20c, and a highly reliable ceramic heater can be realized as in the above embodiment. Further, in the present embodiment, the brazing portion 20c is provided on the proximal end side with respect to the attachment means side seal portion 314c, so that the brazing portion 20c is relatively distant from the resistance heating element 100. For this reason, in the brazing portion 20c, the heat received by the heating element mounting portion 30c and the ceramic heating element 10 is relatively low, and is less susceptible to the stress caused by the difference in thermal expansion coefficient. realizable.

With reference to FIG. 10, a modification 1d of the ceramic heater in the second embodiment of the present invention will be described.
The ceramic heater 1d in the present embodiment is the same as the ceramic heater 1c described above in that the housing 3d is integrally formed in a substantially cylindrical shape. However, the attachment means side seal is attached to the distal end side of the attachment means side screw portion 302d. parts 314d and differences that were formed, the point having a brazed portion 20d on the base end side of the stress generating areas AR _STR are common.
Even in such a configuration, as in the above embodiment, the stress generated when the attachment means side screw portion 302d is screwed to the attached portion side screw portion 611d of the attached portion 60c is applied to the brazed portion 20d. There is no risk of acting, and a highly reliable ceramic heater can be realized as in the above embodiment.

With reference to FIG. 11, the ceramic heater 1e in the 3rd Embodiment of this invention is demonstrated.
In the present embodiment, the housing 3e is configured by the heating element mounting member 30, the heating element holding member 31e, and the energizing wire protection member 32, and the inner diameter of the heating element insertion hole 311e of the heating element holding member 31e is formed as the flange 312e. This is different from the first embodiment in that the diameter is increased in the region and the gap CV _31e between the ceramic heating element 10 and the inner peripheral wall of the heating element insertion hole 311e is widened.
By adopting such a configuration, the flange 312e, which is the stress generation region AR _STR , and the ceramic heating element 10 are completely separated from each other, and it is possible to reliably suppress a decrease in the bonding strength of the brazed portion 20e during assembly. It becomes possible.
Further, when the brazing portion 20e is formed, a brazing material is disposed in the gap CV _31e , heated and melted, and penetrated into a predetermined range of the gap between the ceramic heating element 10 and the cylindrical portion 310. The brazing material does not remain in the portion where the flange portion 312e is formed, and it is possible to reliably prevent the internal stress generated in the flange portion 312e from acting on the brazing contact portion 20e.

A modification 1f of the ceramic heater according to the third embodiment of the present invention will be described with reference to FIG. In the above embodiment, the housing 3e is constituted by the heating element mounting member 30, the heating element holding member 31e, and the energizing wire protection member 32, and the inner diameter of the heating element insertion hole 311e of the heating element holding member 31e is formed as the flange 312e. In the present embodiment, the diameter of the housing 3f is increased and the gap CV _31e between the ceramic heating element 10 and the inner peripheral wall of the heating element insertion hole 311e is widened. The conductive wire protection member 32f is configured to further expand the gap CV _31f between the ceramic heating element 10 and the inner peripheral wall of the heating element insertion hole 311f, thereby forming the heating element holding member 31f in a cylindrical shape, and the conduction wire protection member 32f. The point which provided the collar part 312f so that it may continue to the front-end | tip part of this.
Even with such a configuration, the same effects as those of the above-described embodiment are exhibited.

With reference to FIG. 13, the ceramic heater 1g in the 4th Embodiment of this invention is demonstrated. In the above embodiment, a comparatively small ceramic heater used as an ignition source of a combustion heater or a heating source of combustion exhaust has been described as an example. However, in this embodiment, a combustion chamber or auxiliary combustion of a diesel engine is used. A case will be described in which the chamber is a mounted portion 60g and is used as a long glow plug for assisting ignition.
Also in this embodiment, the basic configuration is the same as in the above embodiment, in which the brazing portion 20g is formed at a position outside the stress generation region AR _STR .
In the embodiment described above, the conductive wire 124 is used for connection from the heating element electrode portion 121 to the outside. However, in the present embodiment, a substantially cylindrical electrode connection fitting 122g is fitted to the heating element electrode portion 121. The middle shaft 123g is connected to the electrode connection fitting 122g to form a metal material in a substantially rod shape. Although the heating element mounting member 30g is formed in a long shape, the basic structure is the same as that of the heating element mounting member 30 shown in the embodiment.
Moreover, in this embodiment, low melting glass etc. are used as the sealing member 33g so that it can oppose the pressure rise at the time of combustion.

  The present invention is not limited to the above-described embodiment, and is generated when the ceramic heater is fixed to the mounting portion by providing the joint between the ceramic heating element and the heating element holding member at a position outside the stress generation region. Changes can be made as appropriate without departing from the gist of the present invention that eliminates the influence of stress and suppresses the reduction in bonding force.

DESCRIPTION OF SYMBOLS 1 Ceramic heater 10 Ceramic heating element 100 Resistance heating element 101 Heat resistant insulation part 110, 120 Heating element lead part 111, 121 Heating element electrode part 112, 122 Electrode connection metal fitting 113, 123 Conducting wire terminal part 114, 124 Conducting line 20 Low Joint (heating element joining means)
211 Spacer 3 Housing (heating element mounting means)
30 Heating element mounting member 300 Mounting portion base 301 Hexagonal portion (tightening portion)
302 Mounting means side thread (male thread)
303 Pressing part 304 Holding member insertion hole 31 Heating element holding member 310 Heating element holding part base (tubular part)
311 Heating element insertion hole 312 collar (stress generation region)
313 Pressure receiving portion 314 Mounting means side seal portion 32 Conductive wire protection member 320 Conductive wire protection base 321 End portion 322 Sealing portion 323 Clamping portion 33 Sealing member 60 Mounted portion 610 Heater mounting hole portion 611 Mounted portion side screw portion (Female thread)
612 Tapered part on attached side (seal contact part)
600 Heated fluid

JP 2001-28292 A JP 2003-56848 A

Claims (6)

A ceramic heating element that is connected to an external energization device via an energization wire and generates heat by energization, and a heating element for placing the heating element located on the tip side in the heated fluid inside the mounted part In a ceramic heater comprising an attachment means,
The attached part includes a attached part side screw part and an attached part side tapered part,
The heating element mounting means includes a mounting means side screw portion, a mounting means side seal portion, a heating element insertion hole into which the heating element is inserted, and heat generation for joining the heating element and the heating element mounting means. Body joining means,
While holding and fixing the heating element in the heating element insertion hole,
By screwing the attached portion side screw portion and the attaching means side screw portion, the attaching portion side seal portion is brought into contact with the attached portion side tapered portion,
A ceramic heater characterized in that the heating element joining means is provided on the base end side with respect to the attachment means side seal portion. A plurality of heating element mounting members including a heating element mounting member disposed on the outer peripheral side and mounted on the mounted portion, and a heating element holding member disposed on the inner peripheral side and directly holding the ceramic heating element. Made of a cylindrical member,
The heating element mounting member includes the mounting means side screw portion, a tightening portion for tightening the screw portion, and a pressing portion that presses the heating element holding member in the direction of the mounted portion.
The heating element holding member includes a heating element insertion hole for inserting and holding the ceramic heating element on the inner peripheral side, and a flange portion protruding in the outer diameter direction at one end,
2. The ceramic according to claim 1, wherein one surface of the flange portion is a pressure receiving portion that receives pressure from the pressing portion, and the other surface is the attachment means side seal portion that contacts the attached portion side taper portion. heater. The heating element mounting means is a cylindrical member,
On its inner peripheral side, it has a heating element insertion hole for inserting the ceramic heating element,
On the outer peripheral side, the mounting means side screw portion, and a tightening portion for tightening the screw portion,
As the attachment means-side seal portion, comprising a substantially conical taper-shaped ridge surface continuously reducing in diameter in the insertion direction,
The heating element joining means is disposed further on the base end side than the most base end side of either the mounting means side screw portion or the base end portion of the mounting means side seal portion. Ceramic heater.   The ceramic heater according to any one of claims 1 to 3, wherein the ceramic heating element joining means is made of a brazing material that is infiltrated into a gap between the ceramic heating element and the heating element mounting means. The heating element mounting means includes at least a substantially cylindrical heating element holding member and a substantially cylindrical energization line protection member provided to protect the energization line,
The leading end of the energizing wire protection member is fixed to the heating element holding member,
Withdrawing the conductive wire to the outside through a sealing member made of an insulating elastic member from the base end side of the conductive wire protection member,
The ceramic heater according to any one of claims 1 to 4, wherein a base end side of the energization wire protection member is caulked and fixed over the entire circumference together with the sealing member.   The ceramic heater according to claim 5, wherein the cylindrical portion of the heating element holding member and the energizing wire protection member are fixed by laser welding over the entire circumference.

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