JP2002270349A - Ceramic heater device and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent cut-off part of a ceramic heater from separating and falling off wherein the heater is fixed by soldering in a metallic cylindrical body. SOLUTION: A tapered part 2t of a tip 2a in a tapering down state of the ceramic heater is formed, and a tip 3a of metallic cylindrical body 3 is made to exist in the tip side from the tapering down the starting point P1 of the tapered part 2t, and the heater 2 is arranged in the metallic cylindrical body 3. A gap of the inner peripheral face 3d of the metallic cylindrical body 3 and the outer peripheral face 2b of the heater 2. A soldered material layer 10 is also made to exist at the tip side from the starting point P1 of the tapering down of the tapered part 2t. A thick walled soldered material layer 10 existing at the tip side is made to have a slipping off prevention action.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic heater device, and more particularly, to a ceramic heater device used for a glow plug used for accelerating a start of a diesel engine or an ignition heater for an oil fan heater.

FIG. 10 shows a ceramic glow plug 101 for a diesel engine as an example of this type of ceramic heater device. In this apparatus, a round bar (column) -shaped ceramic heater 2 is provided inside a metal cylinder 3 (columnar holes), and a heater tip 2a is formed of a metal cylinder (hereinafter simply referred to as a cylinder). 3) are fixed so as to protrude from a front end 3a of the main body 3 and are held (fixed) in a cylindrical metal main body (hereinafter, also simply referred to as main body) 4 so as to protrude from the front end 4a. . For assembling this, for example, the ceramic heater 2 is fitted into the inside of the cylindrical body 3 with a gap, heated molten wax (not shown) is poured into the gap, and the cylindrical body 3 is formed by the poured brazing material layer 10. The ceramic heater 2 is tightened by using thermal expansion and cooling shrinkage to fix the ceramic heater 2 in the tubular body 3 in an airtight manner. Then, the cylindrical body 3 in which the ceramic heater 2 is integrated is fitted into the main body 4 with a gap similarly, and the molten wax 10 is poured into the gap to assemble.

The ceramic heater 2 has a heating element made of, for example, a conductive ceramic and formed in a folded shape (U-shape) or a refractory metal wire (shown in the figure) inside the heater tip 2a. Is buried. Terminals are provided at both ends of the U-shaped portion (ends of both legs) of the heating element and, if necessary, on a side surface of a portion near the rear end 2c of the ceramic heater 2 via a relay wire. 15 and 16 are brazed. Such a heater device includes a lead 1 for energization.
By applying a current through 5 and 16, the ceramic heater 2 is heated by resistance heating.

[0004]

In the above-mentioned conventional structure, the ceramic heater 2 fixed in the cylindrical body 3 by the brazing material layer is provided with a glow plug 101 thereafter.
In the manufacturing process and handling up to assembling, it is subjected to various external forces (impact due to drop, bending force at the time of attachment to the engine). Therefore, the ceramic heater 2
May be cut (broken) at the thick line portion S as shown in FIG. However, such a cut is not visible from the outside because it is inside the metal tubular body 3. For this reason, it may be incorporated into the engine (in the cylinder or the auxiliary combustion chamber) E as it is.

On the other hand, during combustion of the engine, the ceramic heater 2 is constantly exposed to a remarkable temperature change (thermal shock) and blast. Therefore, when the engine is running,
Due to the difference in thermal expansion between the metal tubular body 3 and the ceramic heater 2 due to vibration or temperature rise, relaxation (looseness) occurs between the two. On the other hand, since the inner peripheral surface 3d of the metal tubular body 3 has a constant inner diameter and is straight, if such relaxation occurs, FIG.
As described above, there is a problem that the cut portion of the ceramic heater 2 on the heater tip 2a side may be separated and fall into the combustion chamber of the engine E.

That is, since the brazing of the metal tubular body 3 and the main body 4 is made of metal for both parts, the joining strength is high and stable. Further, the inner peripheral surface 3 of the metal cylindrical body 3
Although the bonding strength between d and the brazing material layer 10 is high, the bonding strength between the outer peripheral surface 2b of the ceramic heater 2 and the brazing material layer 10 is relatively low because it is only in the shrink-fit state. The difference in thermal expansion coefficient from the brazing material is large. Therefore, the outer peripheral surface 2b of the ceramic heater 2
Relaxation (looseness) is likely to occur at the interface between the solder layer 10 and the brazing material layer 10. In particular, when cutting is performed near the distal end 3a of the metal tubular body 3, the force for holding the cut portion of the ceramic heater 2 is small, so that separation and dropping are likely to occur.

Further, in such a ceramic heater device, there is a ceramic heater device in which a ceramic heater is press-fitted and held in a metal tubular body 3 instead of a device fixed by a brazing material layer. However, in the case of the press-fitting, when the ceramic heater is cut as described above, there is a problem that the cut portion is separated or dropped as in the case of the brazing material layer. Further, not only in the brazing material layer structure or the press-fitting structure, there is a possibility that such cutting of the ceramic heater may occur after being incorporated into the engine, but in such a case, there is a similar problem.

The present invention has been made in view of the above-mentioned problems in the conventional ceramic heater device such as a glow plug, and an object thereof is to fix a ceramic heater in a metal cylindrical body by brazing or press-fitting. It is an object of the present invention to prevent the cut portion of the ceramic heater from separating and falling off.

[0009]

In order to solve the above-mentioned problems, the invention according to claim 1 provides an axial ceramic heater in a metal cylindrical body, and a heater tip of the metal cylindrical body. In a ceramic heater device having a structure arranged so as to protrude from a tip, a tapered portion having a tapered shape is formed at the tip of the ceramic heater, and the metal tubular body is located closer to the tip than a tapered starting point of the tapered portion. The ceramic heater is disposed in the metal cylindrical body with the tip of the ceramic heater being present, and a brazing material is interposed between the inner peripheral surface of the metal cylindrical body and the outer peripheral surface of the ceramic heater to fix them together. The brazing material layer is also present on the tip side of the tapered portion from the tapered starting point.

[0010] By the above means, there is a brazing material layer present on the tip side from the tapered starting point of the tapered portion. Even if the ceramic heater is loose in the metal cylindrical body, such a brazing material layer is in a shape to engage with the tapered portion when trying to slide over the metal cylindrical body toward the distal end side. It acts as a retainer. That is, when the ceramic heater is cut at the rear end side from the tapered start point of the tapered portion, for example, even if relaxation occurs at the interface between the outer peripheral surface and the brazing material layer at the front end side from the cut portion, the tapered portion is cut off. The brazing material layer existing on the tip side from the tapering start point is formed thick on the surface of the tapered portion. Since this is engaged with the tapered portion and acts as a stopper, the cut end portion of the ceramic heater is prevented from falling off the metal tubular body. Thus, in the case where the present invention is embodied as a glow plug, for example, the ceramic heater is cut into the metal tubular body, and when the ceramic heater and the metallic tubular body are operated while being incorporated into the engine. Even if relaxation occurs with the body, the cut portion of the ceramic heater is prevented from falling into the auxiliary combustion chamber of the engine. It is appropriate that the taper angle of the tapered portion is about 10 minutes to 5 degrees.

The invention according to claim 2 has a structure in which a shaft-shaped ceramic heater is disposed in a metal tubular body such that the heater tip protrudes from the tip of the metal tubular body. In a ceramic heater device, in which both are fixed by interposing a brazing material between an inner peripheral surface of the metal cylindrical body and an outer peripheral surface of the ceramic heater, the ceramic heater includes: A small-diameter portion having a smaller diameter than other portions in the metal tubular body is formed in a portion in the metal tubular body and corresponding to a portion near the tip of the metal tubular body, and is interposed in the small-diameter portion. The ceramic material layer is provided so as to prevent the ceramic heater from slipping out of the metal tubular body toward the distal end.

[0012] The small diameter portion may be,
A straight portion having a straight shape toward the tip may be used, or a tapered portion having a tapered shape may be used. In the present invention, the small diameter portion includes a constriction or a circumferential groove formed around the axis. If such a small-diameter portion is present, the brazing material layer enters into the small-diameter portion, and the ceramic heater acts to prevent the metal heater from slipping to the distal end side with respect to the metal tubular body.

[0013] In any of the above means, the brazing material layer acting as a retaining member is constituted by the difference between the maximum outer diameter and the minimum outer diameter of the ceramic heater located near the front end of the metal tubular body. However, this difference is 10 μm to 30 μm.
It is good to be in the range of 0 μm. If this difference is smaller than 10 μm, the retaining function becomes insufficient, while 300 μm
If the temperature exceeds the limit, the molten wax may not reach the gap between the inner peripheral surface of the metal cylindrical body and the outer peripheral surface of the ceramic heater due to the capillary phenomenon (does not fill), and there is a risk of causing a fixing failure due to the brazing material layer. Because there is.

The invention according to claim 5 has a structure in which a shaft-shaped ceramic heater is disposed in a metal tubular body such that the heater tip protrudes from the tip of the metal tubular body. In a ceramic heater device, in which both are fixed by interposing a brazing material between an inner peripheral surface of the metal cylindrical body and an outer peripheral surface of the ceramic heater, the ceramic heater includes: A concave portion is formed on the outer peripheral surface of a portion which is located in the metal cylindrical body and corresponds to a portion near the tip of the metal cylindrical body, and the brazing material layer interposed in the concave portion is formed by the ceramic heater by the metal heater. The present invention is characterized in that it is provided so as to function to prevent the tubular body from slipping out when it slides toward the distal end side. In the above description, the ceramic heater is provided with the small-diameter portion, but the configuration described in the present claim may be adopted.

Further, the invention according to claim 6 has a structure in which a shaft-shaped ceramic heater is disposed in a metal tubular body such that the heater tip protrudes from the tip of the metal tubular body. In the ceramic heater device, a tapered portion having a tapered shape is formed at the tip of the ceramic heater, and the ceramic heater is formed such that the tapered starting point of the tapered portion is located at a position closer to the tip of the metal tubular body. The metal cylindrical body is press-fitted into the cylindrical body, and the tip of the metal cylindrical body is tapered at the tapered portion.

With this configuration, the shaft-shaped ceramic heater can be arranged so that the tip of the heater protrudes from the tip of the metal tubular body without being fixed by the brazing material layer. In addition, since the distal end of the metal cylindrical body is tapered at the tapered portion, the distal end is engaged with the tapered portion, and acts as a stopper. Therefore, even if the tip of the ceramic heater is cut as described above, it is possible to prevent the ceramic heater from falling off from the metal tubular body. Moreover, with such a structure, a ceramic heater device having a retaining action can be easily formed by providing an appropriate press-in allowance and press-fitting the ceramic heater into the metal cylindrical body from the tip end side at a predetermined depth. .

That is, according to a preferred aspect of the present invention, a preferable method is to provide a shaft-shaped ceramic heater in a metal tubular body such that the heater tip projects from the tip of the metal tubular body. In manufacturing the ceramic heater device having a structure in which the ceramic heater is press-fitted from the tip, a tapered portion having a tapered shape is formed at the tip of the ceramic heater, and the tapered starting point of the tapered portion is the metal cylindrical shape. It is to press-fit the ceramic heater into the metal tubular body to a position not exceeding the tip of the body.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described in detail with reference to FIGS. FIG. 1 shows a cross section of a main part of a glow plug 1 for a diesel engine in this example as a ceramic heater device. As will be described in detail later, the ceramic heater 2 has a tapered round bar shape (shape having a circular cross section), and a metal tubular body 3 in which the ceramic heater 2 is inserted and fixedly arranged by a brazing material layer. And a main body 4 holding a metal tubular body 3 in which the heater 2 is integrated. The ceramic heater 2 is inserted into the metal cylindrical body 3 in a gap-fitting manner with its tip (the lower end in FIG. 1) 2a protruding from the part, and is fixed by a silver solder 10. Then, the integrated metal tubular body 3 is formed such that the portion near the rear end 3c is fitted into the reduced diameter portion 5 where the inner peripheral surface 4d near the front end 4a of the main body 4 is slightly reduced in diameter. It is interpolated, fixed with silver brazing 10, and assembled to the main body 4. In the figure,
Reference numerals 15 and 16 denote current-carrying leads, which are connected to terminals led out to the side surface near the rear end 2c of the ceramic heater 2. The heater is configured to generate heat at the end of the heater by applying a current through the conducting leads 15 and 16. Such a basic configuration is the same as a conventional glow plug.

On the other hand, the ceramic heater 2 constituting the glow plug 1 of the present embodiment has a cylindrical portion 6 having a straight, same-diameter circular cross section, and a tip 2a from the end of the cylindrical portion 6 (the lower end in FIG. 1). The tapered portion 2t has a trapezoidal shape and a tapered shape. In this example, the ceramic heater 2 has a diameter of 3.5 mm and a length of 45 mm.
12mm from the front end to the rear end side
In this range, the tapered portion 2t has a tapered shape. However, the taper angle θ of the tapered portion 2t is
For example, it is 30 minutes, and the tip 2a is formed in a hemispherical shape. In addition, such a ceramic heater 2
Although not shown, a resistance heating element (wire) made of a conductive ceramic or a high melting point metal is embedded and sintered and formed in a ceramic substrate made of a ceramic insulator such as silicon nitride.

Then, such a ceramic heater 2
Is inserted into a metal-made (for example, SUS430) cylindrical body (length: 20 mm) 3 which is a straight pipe having a certain thickness and has a cylindrical shape. The tapered portion 2t is positioned on the tip side of the tapered starting point P1 with a dimension of L1 and is brazed by silver brazing. In this way, the portion closer to the tip 2a has a predetermined length (10 m in this example).
m) Projected. The brazed brazing material layer 10 is also present on the outer peripheral surface of the cylindrical portion 6 and on the outer peripheral surface of the tapered portion 2t on the distal end side from the tapered starting point P1, and has a thick wall on the distal end side than the tapered starting point P1. Has become. The cylindrical body 3 has an inner diameter of 3.6 mm and a thickness of 0.7 mm in this example at room temperature.

As described above, in the present embodiment, the brazing material layer 10
In the outer peripheral surface of the straight cylindrical portion 6 on the rear end side of the tapered portion 2t of the tapered portion 2t of the ceramic heater 2 at the rear end side, the thickness T1 is substantially constant at 50 μm. However, on the peripheral surface of the tapered portion 2t, the thickness becomes larger corresponding to the tapered taper toward the distal end side, and becomes maximum at the distal end 3a of the metal cylindrical body 3, and the maximum thickness T2 is about 80 μm in this example. It has been. That is, as shown in FIG. 1, when cut along a plane passing through the axis G, the tapered portion 2t
In the cross-sectional view, the brazing material layer 10 has a wedge shape in which the inner diameter is smaller and the wall thickness is thicker toward the tip end side,
The movement of the ceramic heater 2 toward the front end is regulated.

For this reason, when the ceramic heater 2 is cut, for example, as indicated by the line S in FIG. 1 and is directly mounted in the sub-combustion chamber E of the diesel engine and is operated, the operation is as follows. That is, in this embodiment,
Due to the thermal shock and blast caused by the operation of the engine, the brazing material layer 1
0 and the interface with the outer peripheral surface of the ceramic heater 2 are separated,
Even if the front end 2a side of the ceramic heater 2 tries to slide toward the front end side with respect to the metal cylindrical body 3, the brazing material layer 10 having a wedge-shaped cross section existing in the tapered portion 2t functions to prevent the slipping. For this reason, even if the tip of the ceramic heater 2 is cut in this way and the brazing material layer 10 is loosened, the tip of the cut portion falls into the sub-combustion chamber E as in the related art. There is no such thing as. Also,
The same is true even if such a cut occurs after assembly to the engine. As described above, in the present embodiment, the brazing material layer 10 fixed at the tapered portion 2t acts to prevent the ceramic heater 2 from coming off toward the front end side, so that the front end portion of the ceramic heater 2 is prevented from being separated or dropped. There is an effect that it can be done.

In this embodiment, the larger the taper angle θ of the tapered portion 2t is, and the larger the dimension of the brazing material layer 10 existing in the tapered portion 2t in the direction of the axis G is, the larger the retaining function is. However, the taper angle θ and the brazing material layer 1
As the dimension in the direction of the axis G of 0 becomes larger, the gap between the outer peripheral surface 2b of the tapered portion 2t of the ceramic heater 2 before brazing and the inner peripheral surface 3d of the metal cylindrical body 3 becomes larger on the distal end side. For this reason, the wetting and spreading of the molten wax due to the capillary phenomenon during the pouring operation of the molten wax is hindered, and there is a risk that the wax does not sufficiently reach the leading end side from the tapered starting point P1 of the tapered portion 2t. On the other hand, the taper angle θ
The smaller the is, the lower the retaining action is. The taper angle θ is preferably set in the range of 10 minutes to 5 degrees, depending on the distance L1 from the tapered starting point P1 of the tapered portion 2t to the tip end surface 3a of the metal cylindrical body 3 along the axis G direction. .
If a sufficient pull-out preventing action cannot be expected, the portion of the metal tubular body 3 near the distal end 3a may be caulked so as to reduce the diameter or narrow down, and then brazing.

Here, a method of brazing the ceramic heater 2 in this embodiment to the metal tubular body 3 will be described with reference to FIG.
This will be described with reference to FIG. In FIG. 3, both support jigs used for brazing are omitted. As shown in FIG. 3A, the ceramic heater 2 is inserted into the cylindrical body 3 in a clearance fitting manner, and the tip 2a is held so as to protrude by a predetermined length. That is, the distal end 3a of the metal cylindrical body 3 is positioned at a distance L1 from the tapered starting point P1 of the tapered portion 2t to the distal end side. Then, under this condition, a molten wax (silver wax) is poured into the gap. By doing so, as shown in FIG. 3B, the brazing material is interposed between the inner peripheral surface 3d of the metal tubular body 3 and the outer peripheral surface 2b of the ceramic heater 2 and both are fixed. An outer peripheral surface 2b of the cylindrical portion 6,
It also exists on the tip end side of the tapered portion 2t with respect to the taper start point P1. It is preferable that the molten glass is applied and baked on the peripheral surface (surface) of the ceramic heater 2 in order to improve the wettability of the molten wax.

Next, a second embodiment of the present invention will be described in detail with reference to FIG. However, the glow plug 21 of the present embodiment is to be said to be a modification of the above embodiment, and there is no essential difference. Therefore, the same reference numerals are given to the same portions, and only the differences will be described.

In the above-described embodiment, the tip of the ceramic heater 2 is formed in a tapered shape, whereas in the present embodiment, the metal cylindrical member 3 of the ceramic heater 2 is formed.
A small-diameter portion 2s having a diameter D2 smaller than the diameter D1 of the other portion (column portion) 6 is formed in a portion of the metal cylindrical body 3 corresponding to the portion near the tip 3a. However, the small-diameter portion 2s has a coaxial (concentric) circular cross section with another portion, that is, a large-diameter cylindrical portion 6 near the rear end, and forms a straight portion that is straight toward the front end 2a. Incidentally, in the present embodiment, the diameter D1 of the large diameter portion 6 is 3.5 mm, while the diameter D2 of the small diameter portion 2s is 3.3 mm, and the metal cylindrical body 3 is the same as that described above. . Therefore, the thickness T1 on the outer peripheral surface of the large diameter portion 6 of the brazing material layer 10 is about 50 μm, while the thickness T2 on the outer peripheral surface of the small diameter portion 2s is about 150 μm.

In this embodiment as well, when the ceramic heater is cut along the line S, even if the interface between the fixed brazing material layer 10 and the outer peripheral surface of the ceramic heater 22 is loosened. The same operation and effect as those of the above embodiment are obtained. That is, since the brazing material layer 10 existing on the outer peripheral surface of the small diameter portion 2s and within the range of the dimension L along the axis G functions to prevent the cut portion of the ceramic heater 22 from coming off, the falling off is prevented.

In this embodiment, since a distinct step portion having a different diameter is formed at the boundary point P2 between the large-diameter portion 6 and the small-diameter portion 2s, the retaining function is larger than that in the above-described embodiment. The small-diameter portion 2s may not be straight but may be a tapered portion having a tapered shape as shown by a two-dot chain line N in FIG. In this case, the taper angle is preferably set in the range of 10 minutes to 45 degrees. However, in any case, the small diameter portion 2s is preferably provided coaxially (concentrically) with the large diameter portion. Further, if the small diameter portion 2s is too thin, a poor filling of the brazing material will be caused. Therefore, a solder having a thickness and a blocking function within a range in which an appropriate retaining function can be obtained in a range where there is no such failure. It is preferable to set the dimension L1 of the material layer. In the case where a sufficient pull-out preventing action cannot be expected, even in this case, the portion of the metal cylindrical body 3 near the tip end 3a may be caulked so as to reduce or narrow the diameter, and then fixed by the brazing material layer. .

Next, another embodiment of the present invention will be described with reference to FIG. However, the glow plug 31 of this embodiment is to be said to be a modification of the above embodiment, and there is no essential difference. Therefore, the same portions are denoted by the same reference numerals, and only the differences will be described.

That is, in the above-described embodiment, the small-diameter portion 2s of the ceramic heater 22, which is located in the metallic tubular body and corresponds to the portion of the metallic tubular body 3 near the tip 3a, has a smaller diameter than the other portions. Is a straight section which is coaxial (concentric) with the other part, that is, the large diameter part 6 near the rear end, and which is straight toward the front end. On the other hand, in the present embodiment, as shown in FIG. 5, the small diameter portion 32s has a circumferential groove or a constriction around the axis.

Thus, in the brazing material layer 10 in which the brazing material is interposed between the outer peripheral surface of the ceramic heater 32 and the inner peripheral surface of the metal cylindrical body 3 to fix them, this small-diameter portion ( What is present in the (circumferential groove) 32s functions to prevent the ceramic heater 32 from falling off, similarly to the above embodiment. Thickness (depth of peripheral groove) of small diameter portion 32s and small diameter portion (peripheral groove) 3
The width of 2 s may be set to a size necessary for the brazing material layer that has entered there to perform a retaining function.

Next, a fifth embodiment of the present invention will be described with reference to FIGS. 6 and 7. The glow plug 41 of the present embodiment is also a modification of the above embodiment, and there is no essential difference. Therefore, the same parts are given the same reference numerals,
Only the differences will be described. That is, as shown in the figure, for example, instead of the circumferential groove-shaped small diameter portion 32s provided in the ceramic heater 32 of the above-described embodiment, for example, four hemispherical concave portions 42s are provided around the axis G, for example, four. They are provided at equal angular intervals.

In this embodiment, of the brazing material layer 10 in which the brazing material is interposed between the outer peripheral surface of the ceramic heater 42 and the inner peripheral surface of the metal tubular body 3 to fix them together, What exists in the concave portion 42s functions to prevent the ceramic heater from coming off.

Each of the above embodiments has
The ceramic heater has a structure in which a ceramic heater is fitted in a gap in the metal cylindrical body 3 and is integrated by pouring a molten wax into the gap and fixing the gap. A part of the fixed brazing material layer is used to prevent the ceramic heater from coming off. That is the effect. Therefore, a step of pouring a molten wax into the assembly is required. Hereinafter, a sixth embodiment of the present invention which does not require the fixing by the brazing material will be described with reference to FIGS.

The glow plug 61 of the present embodiment does not require brazing of the ceramic heater and the metal tubular body,
The point that the ceramic heater 2 is formed by press-fitting the ceramic heater 2 into the metal cylindrical body 3 is essentially different from the embodiment of claim 1, but the other points are basically different from the embodiment. Absent. Therefore, the differences will be mainly described, and the same reference numerals will be given to the common parts, and the description thereof will be appropriately omitted.

In this embodiment, a ceramic heater 2 in the shape of a tapered round bar, a metal cylindrical body 3 in which the ceramic heater 2 is press-fitted and arranged, and a metal cylindrical body in which the ceramic heater 2 is integrated It is composed of a main body 4 and the like which hold the ceramic heater 2 through the main body 3. The ceramic heater 2 is integrated by projecting a portion near the tip 2 a and press-fitting the metal heater 3 into the metal cylindrical body 3. The integrated metal cylindrical body 3 moves the portion near the rear end 3c to the inner peripheral surface 4d near the front end 4a of the main body 4.
Is inserted into the reduced diameter portion 5 having a slightly reduced diameter so as to fit in a gap, and the silver solder 10 is poured into the gap and fixed by the brazing material layer.

The ceramic heater 2 constituting the glow plug 1 of this embodiment is the same as that shown in FIG. Such a ceramic heater 2 is made of a straight metal pipe and has a cylindrical shape (for example, SUS430).
Made into a tubular body (length 20 mm) 3
Is projected a predetermined length (10 mm in this example). And, the tapered starting point P1 of the tapered portion 2t is the metal cylindrical body 3
Are arranged at the rear end side of the front end 3a with a dimension of L1. That is, although the ceramic heater 2 is press-fitted from the tip 2a side, the press-fitting is stopped at a point where the tip 3a of the metal tubular body 3 is located in the middle of the tapered portion 2t.

As a result, as shown in FIG. 8, the portion of the metallic cylindrical body 3 near the distal end 3a that is closer to the distal end than the tapered starting point P1 of the tapered portion 2t is the tapered portion 2t.
It has a tapered shape that fits easily. That is, when cut along a plane passing through the axis G, in the tapered portion 2t, the portion of the metal tubular body 3 near the tip 3a has a smaller inner diameter toward the tip 3a, and the tip of the ceramic heater 2 Restricts movement to the side.

Therefore, also in this embodiment, the ceramic heater 2 is cut as shown by a line S in FIG. 8, for example, and is attached to the sub-combustion chamber E of the diesel engine as it is.
When the vehicle is driven, the same operation and effect as those of the above embodiments are obtained. That is, in the present embodiment, the inner peripheral surface of the metal cylindrical body 3 and the ceramic heater 2
When the tip 2a side of the ceramic heater 2 tries to slide to the tip side with respect to the metal tubular body 3 at the tapered portion 2t, the portion near the tip 3a of the metallic tubular body 3 comes first. Since it is in the shape of a pocket, stop it from falling out. For this reason, it is possible to prevent the tip side of the cut portion of the ceramic heater 2 from falling into the sub-combustion chamber E.

As shown in FIGS. 9A and 9B, such a press-fitting structure of the ceramic heater 2 into the metal cylindrical body 3 is a straight tube made of metal (for example, SUS4).
It can be obtained only by press-fitting the tip 2a from the heater tip 2a side into the cylindrical body (length 20 mm) 3 so as to protrude the tip 2a by a predetermined length (10 mm in this example). That is, in this press-fitting, the tapered starting point P of the tapered portion 2t
Press-fit until the distal end 3a of the metal tubular body 3 is positioned with the dimension of L2 closer to the distal end side than 1. By doing this,
The portion of the metal cylindrical body 3 around the large-diameter cylindrical portion 6 is greatly deformed by the press-fitting allowance and expanded in diameter. However, the diameter is not so greatly expanded on the tip end side from the tapered starting point P1 of the tapered portion 2t. Is relatively tapered. In this example, the cylindrical body 3 has an inner diameter of 3.35 mm and an outer diameter of 5 mm before press-fitting.
(Thickness: 0.825 mm) was used.

Also in the present embodiment, as the taper angle θ of the tapered portion 2t is larger, the taper angle of the tip of the metal cylindrical body is larger, so that the retaining action is larger. But,
If the taper angle θ is too large, press fitting cannot be performed smoothly. On the other hand, as the taper angle θ is smaller, the press-fitting becomes smoother, but it is necessary to ensure a longer length of the tapered portion 2t. Along with the press-fit allowance or axis G direction necessary for airtightness,
Depending on the distance L2 from the tapered starting point P1 of the tapered portion 2t to the distal end surface 3a of the metal cylinder 3, the material of the metal cylinder, etc., the taper angle θ in the case of such a press-fitting structure is 10 It is preferable to set the range from minutes to 2 degrees.

In the press-fitting structure such as this embodiment, as described above, the press-fitting depth is set to a predetermined value and press-fitting is performed to integrate the ceramic heater into the metal cylindrical body. At the same time, the retaining of the ceramic heater can be automatically obtained. Moreover, since the metal cylindrical body 3 to be used may be a straight cylinder, the production efficiency is good. Further, in the case where the fixing of the ceramic heater 2 to the metal tubular body 3 is performed by press fitting as in the present embodiment,
Since the step of applying glass to the outer peripheral surface of the ceramic heater 2, the step of brazing, and the step of plating the metal tubular body 3 are not required, the manufacturing process is simplified and the manufacturing cost is reduced.

In each of the above embodiments, the case where the ceramic heater device is embodied as the glow plug is exemplified.
The application example is not limited to this. It can be applied to various heaters other than oil heaters for ignition of oil fan heaters.

[0044]

As is apparent from the above description, according to the ceramic heater device of the present invention, when this is embodied as a glow plug, for example, the ceramic heater remains cut in the metal cylindrical body. The cut portion can be prevented from falling into the engine even when the cut portion is incorporated into the engine and then operated. The same applies to a case where a disconnection occurs after being incorporated into the engine. Further, even when the present invention is applied to an ignition heater of an oil fan heater, there is an effect that separation and dropping of a cut portion can be prevented.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a main part of a ceramic heater device (glow plug) according to an embodiment of the present invention, and an enlarged cross-sectional view of a main part thereof.

FIG. 2 is an enlarged view of the glow plug of FIG. 1 as viewed from a front end surface side.

FIG. 3 is a cross-sectional view for explaining a step of brazing by inserting a ceramic heater forming the glow plug of FIG. 1 into a metal cylindrical body, where A is a cross-sectional view of a set state before brazing, and B is Sectional view after brazing.

FIG. 4 is a cross-sectional view of a main part of an embodiment of a ceramic heater device (glow plug) according to the present invention, and an enlarged cross-sectional view of a main part thereof.

FIG. 5 is a cross-sectional view of a main part of an embodiment of a ceramic heater device (glow plug) according to the present invention and an enlarged cross-sectional view of the main part.

FIG. 6 is a cross-sectional view of a main part of an embodiment of a ceramic heater device (glow plug) according to the present invention, and an enlarged cross-sectional view of the main part.

FIG. 7 is a sectional view taken along line AA in FIG. 6;

FIG. 8 is a cross-sectional view of a main part of an embodiment of a ceramic heater device (glow plug) according to the present invention, and an enlarged cross-sectional view of the main part.

9 is a cross-sectional view for explaining a process of press-fitting the ceramic heater forming the glow plug of FIG. 8 into a metal tubular body and assembling the same, wherein A is an explanatory cross-sectional view before press-fitting, and B is tightening after press-fitting. Sectional drawing of a fitting state.

FIG. 10 is a sectional view of a main part of a conventional glow plug.

FIG. 11 is an explanatory view showing a state in which a heater tip is cut and separated in FIG. 10;

[Explanation of symbols]

1, 21, 31, 41, 61 glow plug (ceramic heater device) 2, 22, 32, 42 ceramic heater 2a tip of ceramic heater 2b outer peripheral surface of ceramic heater 2t taper portion 2s, 22s, 32s small diameter portion (straight portion) Reference Signs List 3 metal cylindrical body 3a tip of metal cylindrical body 3d inner peripheral surface of metal cylindrical body 10 brazing material layer (silver brazing) 42s concave portion on outer peripheral surface of ceramic heater P1 taper start point of tapered portion D1 ceramic heater Outer diameter of cylindrical part D2 Outer diameter of small diameter part of ceramic heater

Continued on the front page (72) Inventor Katsuhisa Yabuta 14-18, Takatsuji-cho, Mizuho-ku, Nagoya Japan F-term (reference) 3K092 PP16 PP20 QA01 QB03 QB24 RA10 RD02 RD18 RD46 VV40

Claims (7)

[Claims] 1. A ceramic heater device having a structure in which a shaft-shaped ceramic heater is disposed in a metal tubular body such that a heater tip protrudes from a tip of the metal tubular body. Forming a tapered portion having a tapered taper at the tip, and disposing the ceramic heater inside the metal tubular body by making the tip of the metal tubular body exist more distally than the tapered starting point of the tapered portion; A brazing material is interposed between the inner peripheral surface of the metal cylindrical body and the outer peripheral surface of the ceramic heater to fix them, and this brazing material layer is also present on the tip side from the tapered starting point of the tapered portion. A ceramic heater device. 2. A ceramic heater device having a structure in which a shaft-shaped ceramic heater is disposed in a metal tubular body so that a heater tip projects from a tip of the metal tubular body. In the ceramic heater, the brazing material is interposed between the inner peripheral surface of the cylindrical body and the outer peripheral surface of the ceramic heater, and both are fixed. Forming a small-diameter portion having a smaller diameter than other portions in the metal tubular body at a portion corresponding to a portion near the tip of the metal tubular body, and forming a brazing material layer interposed at the small-diameter portion, A ceramic heater device, wherein a ceramic heater is provided so as to prevent the metal tubular body from slipping out to the tip end side when the ceramic heater attempts to slide out. 3. The ceramic heater device according to claim 2, wherein the small-diameter portion is a straight portion that is straight toward the tip. 4. The ceramic heater device according to claim 2, wherein the small diameter portion is a tapered portion having a tapered shape. 5. A ceramic heater device having a structure in which a shaft-shaped ceramic heater is disposed in a metal tubular body so that a heater tip protrudes from a tip of the metal tubular body. In the ceramic heater, the brazing material is interposed between the inner peripheral surface of the cylindrical body and the outer peripheral surface of the ceramic heater, and both are fixed. A concave portion is formed on the outer peripheral surface of a portion corresponding to a portion near the front end of the metal cylindrical body, and the ceramic heater slides the brazing material layer interposed in the concave portion toward the front end side with respect to the metal cylindrical body. A ceramic heater device, wherein the ceramic heater device is provided so as to function as a stopper when trying to come off. 6. A ceramic heater device having a structure in which a shaft-shaped ceramic heater is disposed in a metal tubular body so that a heater tip projects from a tip of the metal tubular body. Forming a tapered tapered portion at the tip, press-fitting the ceramic heater into the metal tubular body so that the tapered starting point of the tapered portion is located at a position closer to the tip of the metal tubular body; A ceramic heater device wherein the tip of a metal cylindrical body is tapered at the tapered portion. 7. When manufacturing a ceramic heater device having a structure in which a shaft-shaped ceramic heater is disposed in a metal tubular body so that the heater tip projects from the tip of the metal tubular body. A taper portion having a tapered shape is formed at the tip of the ceramic heater, and the tapered portion of the tapered portion does not exceed the tip of the metal tubular body. A method for manufacturing a ceramic heater device, comprising press-fitting into a body.