JP7407669B2 - heater - Google Patents

Description

The present invention relates to a heater that generates heat when energized.

A heater in which a tip of a heater element protrudes from the tip of a cylindrical metal shell, a center shaft is electrically connected to a first external electrode of the heater element, and a lead pipe is electrically connected to a second external electrode of the heater element. is known (Patent Document 1). In order to prevent a short circuit between the center shaft and the lead pipe, the heater disclosed in Patent Document 1 has a rubber cylinder installed between the rear end of the center shaft protruding from the rear end of the metal shell and the rear end of the lead pipe. A shaped insulator is placed. The rear end of the center shaft is fixed to the lead pipe by the rubber elasticity (restoring force) of the insulator itself, which is compressed in the radial direction.

Japanese Patent Application Publication No. 2017-166758

However, since the rubber elasticity of the insulator that fixes the lead tube to the center shaft is relatively weak, if a force in the axial direction is applied to the center shaft when handling the heater, the center shaft may shift, causing a short circuit or disconnection.

The present invention was made to solve this problem, and an object of the present invention is to provide a heater whose center shaft can be firmly fixed to the lead pipe.

In order to achieve this object, the heater of the present invention includes a cylindrical metal shell extending along the axis, and a heater disposed inside the metal shell with its tip protruding from the tip of the metal shell. A heater element including a first external electrode and a second external electrode, which is disposed inside the metal shell with its rear end protruding from the rear end of the metal shell, and is electrically connected to the first external electrode. a lead pipe that is arranged between the metal shell and the center shaft with its rear end protruding from the rear end of the metal shell and electrically connected to the second external electrode; A soft insulator disposed between the rear end portion and the rear end portion of the lead tube, and a ring disposed around the rear end portion of the lead tube. It is caulked and fixed to the fixing part of the center shaft through the center shaft.

According to the first aspect, a soft insulator is disposed between the rear end of the center shaft and the rear end of the lead tube, and a ring is disposed around the rear end of the lead tube. Since the ring is caulked and fixed to the fixed part of the center shaft via the lead tube and the insulator, the center shaft can be fixed to the lead tube more strongly than when the center shaft is fixed to the lead tube using rubber elasticity. As a result, even if a force in the axial direction is applied to the center shaft when handling the heater, the center shaft can be prevented from shifting.

According to the second aspect, since the insulator has a tensile strength of 80 MPa or more, the insulator sandwiched between the center shaft and the lead tube can be made difficult to stretch in the axial direction. As a result, the lead tube can be made more difficult to shift in the axial direction with respect to the center shaft, so in addition to the effect of the first aspect, the center shaft can be more firmly fixed to the lead tube.

According to the third aspect, the center shaft is provided with a large-diameter portion having a larger diameter than the fixed portion on the distal end side of the fixed portion to which the insulator is fixed. As a result, when the center shaft is pulled toward the rear end in the axial direction and the large diameter part hits the insulator, the insulator sandwiched between the crimp part and the large diameter part is compressed in the axial direction, so the reaction force This makes it possible to reduce further displacement of the center shaft toward the rear end. Therefore, in addition to the effects of the first or second aspect, the amount of deviation of the center shaft toward the rear end side can be reduced.

According to the fourth aspect, the rear end facing surface of the large diameter portion is in contact with the insulator. Therefore, when the center shaft is pulled toward the rear end in the axial direction, the insulator sandwiched between the crimp portion and the large diameter portion is immediately compressed in the axial direction. Therefore, in addition to the effects of the third aspect, the amount of deviation of the center shaft toward the rear end side can be further reduced.

According to the fifth aspect, an electrically insulating cylindrical support member is disposed between the metal shell and the lead pipe and between the metal shell and the ring. The rear end of the large diameter portion is located closer to the rear end than the tip of the support member. As a result, the insulator is deformed by caulking and fixing the ring to the center shaft, and the deformed insulator spreads radially outward along the large diameter part, even when the lead tube is pushed radially outward by the insulator. , the support member reduces deformation of the lead pipe. Therefore, in addition to the effects of the third or fourth aspect, short circuits between the lead pipe and the metal shell can be prevented.

It is a sectional view of a heater in a 1st embodiment. FIG. 2 is an enlarged cross-sectional view of the heater of the portion indicated by II in FIG. 1. FIG. FIG. 3 is a sectional view of the heater taken along line III-III in FIG. 2; It is a sectional view of the heater in a 2nd embodiment. FIG. 5 is a cross-sectional view of the heater in which the portion indicated by V in FIG. 4 is enlarged. FIG. 5 is a cross-sectional view of the heater in which the portion indicated by VI in FIG. 4 is enlarged. It is a sectional view of a heater in a 3rd embodiment.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a sectional view including an axis O of a heater 10 according to a first embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view of the heater 10, showing the portion indicated by II in FIG. In FIGS. 1 and 2, the lower side of the page is referred to as the tip side of the heater 10, and the upper side of the page is referred to as the rear end side of the heater 10 (the same applies to FIGS. 3 to 6). As shown in FIG. 1, the heater 10 includes a metal shell 11, a heater element 20, a center shaft 30, a lead pipe 40, an insulator 50, and a ring 51.

The metal shell 11 is a substantially cylindrical metal member (eg, carbon steel, stainless steel, etc.) that extends along the axis O. A male thread 12 is formed on the outer peripheral surface of the metal shell 11 . The male thread 12 engages with a screw hole formed in a mating member (not shown) to be heated. A tool engaging portion 13 is formed in the metal shell 11 on the rear end side of the male thread 12 . The tool engaging portion 13 is a portion into which a tool such as a wrench is engaged when tightening the screw 12 into a screw hole of a mating member.

The outer cylinder 16 is a substantially cylindrical metal member (for example, stainless steel, etc.) that extends along the axis O. The outer cylinder 16 is joined to the tip 14 of the metal shell 11. The outer cylinder 16 holds the heater element 20 with the distal end 27 of the heater element 20 protruding toward the distal end side. In this embodiment, the heater element 20 and the outer cylinder 16 have a press-fit structure.

The heater element 20 is a substantially cylindrical member extending along the axis O. The heater element 20 includes a base 21 and a resistor 22 embedded in the base 21. The base body 21 is made of an approximately cylindrical insulating ceramic. In this embodiment, the tip of the base body 21 is formed into a spherical crown shape. The insulating ceramic that constitutes the base body 21 has, for example, silicon nitride as its main component. The resistor 22 is made of conductive ceramic and contains, for example, tungsten carbide and silicon nitride. The resistor 22 includes a heating element 23 embedded in the tip side of the base body 21 and bent along the tip side of the base body 21, and a pair connected to the rear end side of the heating element 23 and extending along the axis O toward the rear end side. A lead portion 24 is provided. The heating element 23 is arranged at the tip 27 of the heater element 20.

One lead portion 24 is provided with a first external electrode 25 exposed on the outer peripheral surface of the base 21 . The other lead portion 24 is provided with a second external electrode 26 exposed on the outer circumferential surface of the base body 21 on the distal end side of the first external electrode 25 . The first external electrode 25 and the second external electrode 26 are made of the same material as the lead part 24. The first external electrode 25 and the second external electrode 26 are located inside the metal shell 11 .

Since the cross-sectional area of the heating element 23 is narrower than the cross-sectional area of the lead part 24, even if the material of the conductive ceramic that forms the heating element 23 is the same as the material of the conductive ceramic that forms the lead part 24, the resistance of the heating element 23 can be reduced. The resistance can be made larger than the resistance of the lead portion 24. As a result, the amount of heat generated by the heating element 23 can be made larger than that of the lead portion 24, so that the heating element 23 can be selectively made to generate heat. Note that instead of making the cross-sectional areas of the heating element 23 and the lead part 24 different, a material having a resistivity larger than that of the lead part 24 is used for the heating element 23, so that the heating element 23 selectively generates heat. Of course it is possible.

The center shaft 30 is a metal cylindrical member extending along the axis O. The tip portion 31 of the center shaft 30 is disposed inside the metal shell 11 on the rear end side of the heater element 20 with a gap from the heater element 20 . The rear end portion 32 of the center shaft 30 protrudes from the rear end 15 of the metal shell 11. A fixing portion 33 is provided at the rear end portion 32 (see FIG. 2) of the center shaft 30. The lead tube 40 and the insulator 50 are fixed to the fixed part 33 by a ring 51. The center shaft 30 is provided with a large diameter portion 34 having a larger diameter than the fixing portion 33 on the distal end side of the fixing portion 33 . The large diameter portion 34 continues to the tip 31 of the center shaft 30. The rear end-facing surface 35 of the large diameter portion 34 is a conical surface whose diameter decreases toward the rear end side.

The lead pipe 40 is a metal cylindrical member extending along the axis O. The lead pipe 40 is disposed on the radially outer side of the center shaft 30 and on the radially inner side of the metal shell 11 with a gap between the metal shell 11 and the center shaft 30 . The tip portion 41 of the lead tube 40 is located on the outside of the first external electrode 25 of the heater element 20 in the radial direction. The rear end portion 42 of the lead pipe 40 protrudes from the rear end 15 of the metal shell 11.

The first member 43 is a metal cylindrical member extending along the axis O. The first member 43 is disposed inside the distal end portion 41 of the lead tube 40 in the radial direction with a gap between the first member 43 and the lead tube 40 . The first member 43 electrically connects the tip 31 of the center shaft 30 and the first external electrode 25 of the heater element 20 . In this embodiment, the heater element 20 and the first member 43 have a press-fit structure, and the first member 43 is directly connected to the first external electrode 25.

The second member 44 is a metal cylindrical member extending along the axis O. The second member 44 is disposed on the distal side of the first external electrode 25 of the heater element 20 and on the inside of the metal shell 11 in the radial direction, with a gap between the second member 43 and the metal shell 11 . The second member 44 electrically connects the tip 41 of the lead tube 40 and the second external electrode 26 of the heater element 20 . In this embodiment, the heater element 20 and the second member 44 have a press-fit structure, and the second member 44 is directly connected to the second external electrode 26.

A soft insulator 50 is arranged between the rear end 32 of the center shaft 30 and the rear end 42 of the lead tube 40 to separate the center shaft 30 and the lead tube 40 from each other. The tip 50a of the insulator 50 is located closer to the tip than the rear end 15 of the metal shell 11. The tip 50a of the insulator 50 is separated from the rear end 36 of the large diameter portion 34 of the center shaft 30.

Examples of the material of the insulator 50 include flexible mica containing mica such as peelable mica and laminated mica, and adhesive (reinforcing material if necessary), engineering plastic, and super engineering plastic. Examples of engineering plastics include polyacetal (POM) and polyamide (PA). Examples of super engineering plastics include polyphenylene sulfide (PPS) and polyetheretherketone (PEEK). The insulator 50 has a cylindrical shape with a continuous circumference, a sheet wrapped around the center shaft 30 with a cut in a part of the circumference, and a sheet wrapped around the center shaft 30 with a cut at both ends in the circumferential direction. A superimposed version of the above is used.

The ring 51 is a metal member that surrounds the rear end portion 42 of the lead tube 40 from the outer periphery. The ring 51 includes a crimping part 52, a first flange 53 extending radially outward from the tip of the crimping part 52, and a second flange 54 projecting radially outward from the rear end of the crimping part 52. It is equipped with. The ring 51 is fixed to the rear end portion 42 of the lead tube 40 by physical pressure from the crimp portion 52 .

Due to the physical pressure applied to the crimp portion 52, at least a portion of the crimp portion 52 is plastically deformed inward in the radial direction. As a result, at least a portion of the crimp portion 52 is in close contact with the rear end portion 42 of the lead pipe 40. The shape of the ring 51 may be an annular ring whose entire circumference is continuous, or a C ring in which a part of the circumference is cut.

The support member 55 is a cylindrical member disposed on the metal shell 11 and surrounding the lead pipe 40, and has electrical insulation properties. The rear end of the flange of the support member 55 is located closer to the rear end than the rear end 15 of the metal shell 11, and the tip 55a of the support member 55 is located closer to the front end than the rear end 15 of the metal shell 11. The rear end facing surface 35 of the large diameter portion 34 is located inside the support member 55 in the radial direction, and the distal end 55 a of the support member 55 is located on the distal side of the rear end 36 of the large diameter portion 34 . The support member 55 is inserted into the rear end 15 of the metal shell 11, and movement of the support member 55 toward the distal end side is restricted by the metal shell 11.

Examples of the material of the support member 55 include flexible mica, engineering plastic, and super engineering plastic. The support member 55 separates the lead pipe 40 from the metal shell 11 in the radial direction. Furthermore, the support member 55 is interposed between the metal shell 11 and the ring 51 to separate the ring 51 from the metal shell 11 in the axial direction. The support member 55 can electrically insulate between the metal shell 11 and the lead pipe 40 and between the metal shell 11 and the ring 51.

The seal member 56 is a ring-shaped member surrounding the lead pipe 40 and is disposed between the tip of the support member 55 and the inner peripheral surface of the metal shell 11. In this embodiment, the seal member 56 is an O-ring, and electrically insulates between the metal shell 11 and the lead pipe 40. Since the sealing member 56 is arranged in a compressed state, the space between the metal shell 11 and the lead pipe 40 is hermetically sealed.

In this embodiment, the ring 51 also serves as an external terminal of the heater 10. Therefore, when a voltage is applied between the rear end 32 of the center shaft 30 of the heater 10 and the ring 51, the resistor 22 of the heater element 20 is energized, and the heating element 23 generates heat.

Due to the physical pressure of the plastically deformed crimp portion 52 (ring 51), the portion of the lead pipe 40 that is radially inside the crimp portion 52 is pushed and plastically deformed radially inward. Since the insulator 50 is soft, it deforms from its natural state when force is applied. Therefore, due to the physical pressure of the plastically deformed lead pipe 40, the insulator 50 deforms inward in the radial direction and presses against the fixing portion 33 of the center shaft 30. That is, the ring 51 is caulked and fixed to the fixing portion 33 of the center shaft 30 via the lead pipe 40 and the insulator 50.

As a result, the center shaft 30 can be more strongly fixed to the lead tube 40 than when the lead tube 40 is fixed to the center shaft 30 using only the elasticity of the insulator 50. As a result, even if a force is applied to the center shaft 30 in the axial direction when handling the heater 10, such as when attaching the heater 10 to an internal combustion engine (not shown), the center shaft 30 can be prevented from shifting in the axial direction.

The insulator 50 preferably has a tensile strength of 80 MPa or more at room temperature (15° C. to 25° C.). This is because the center shaft 30 is fixed to the lead pipe 40 via the insulator 50. The tensile strength of the insulator 50 material is measured according to ASTM D638:2003. A dumbbell-shaped test piece with a distance between gauge lines of 50 mm is used to measure the tensile strength.

The insulator 50 preferably has a tensile strength of 250 MPa or less at room temperature. This is to prevent the force applied to the insulator 50 from becoming excessive when fixing the center shaft 30 to the lead tube 40 via the insulator 50, and to reduce deformation of the lead tube 40 and the center shaft 30.

FIG. 3 is a sectional view of the heater 10 taken along the line III--III in FIG. As shown in FIG. 3, the insulator 50 is interposed between the lead tube 40 pressed by the crimp portion 52 of the ring 51 and the fixing portion 33 of the center shaft 30 without being crushed excessively. The radial thickness of the insulator 50 interposed between the lead pipe 40 and the fixed part 33 ensures an insulation distance between the lead pipe 40 and the fixed part 33, so that short circuits of the heater 10 can be prevented. .

The crimp portion 52 has an annular cross section perpendicular to the axis O, and presses the lead pipe 40 inward in the radial direction over the entire circumference. As a result, the insulator 50 is pushed radially inward over the entire circumference due to plastic deformation over the entire circumference of the lead pipe 40, and the insulator 50 is in contact with the entire circumference of the fixed portion 33 of the central shaft 30. Therefore, the load applied to the insulator 50 can be dispersed compared to a case where a part of the circumference of the lead pipe 40 is plastically deformed and a part of the circumference of the insulator 50 is pushed radially inward. Therefore, elongation and damage of the insulator 50 can be suppressed.

In this embodiment, the insulator 50 has a tensile strength of 80 MPa or more. This makes it more difficult for the insulator 50 to stretch in the axial direction, making it difficult for the rear end 42 of the lead tube 40 to shift in the axial direction with respect to the rear end 32 of the center shaft 30. Since the center shaft 30 can be more firmly fixed to the lead pipe 40, displacement of the center shaft 30 in the axial direction due to the load applied to the heater 10 can be suppressed.

When the ring 51 is caulked and fixed, when the insulator 50 is sandwiched between the lead pipe 40 pushed inward by the plastic deformation of the crimping part 52 and the center shaft 30, the insulator 50 is compressed in the radial direction and expanded in the axial direction. . An axial force is applied to the center shaft 30 due to the friction of the insulator 50 extending in the axial direction. Since the insulator 50 has a tensile strength of 80 MPa or more, it is possible to suppress the elongation of the insulator 50 in the axial direction and reduce the displacement of the center shaft 30 in the axial direction due to friction of the insulator 50.

The center shaft 30 is provided with a large diameter portion 34 closer to the tip than the fixed portion 33 to which the insulator 50 is fixed. The large diameter portion 34 is located closer to the tip than the insulator 50 and has a larger diameter than the fixed portion 33. As a result, when the center shaft 30 is pulled toward the rear end in the axial direction and the large diameter portion 34 hits the insulator 50, the insulator 50 is sandwiched between the crimp portion 52 and the rear end facing surface 35 of the large diameter portion 34. is compressed in the axial direction. Due to the reaction force, further displacement of the center shaft 30 toward the rear end side can be reduced. Therefore, the amount of displacement of the center shaft 30 toward the rear end side can be reduced.

The rear end 36 of the large diameter portion 34 of the center shaft 30 is located closer to the rear end than the tip 55a of the support member 55. As a result, the insulator 50 is deformed by caulking and fixing the ring 51 to the center shaft 30, and the deformed insulator 50 spreads outward in the radial direction along the large diameter portion 34, and is led outward in the radial direction by the insulator 50. Even if the tube 40 is pushed, the support member 55 reduces deformation of the lead tube 40. Therefore, a short circuit between the lead pipe 40 and the metal shell 11 can be prevented.

The first flange 53 of the ring 51 is in contact with the rear end of a support member 55 fixed between the metal shell 11 and the lead pipe 40. Since the movement of the support member 55 toward the distal end side is restricted by the metal shell 11, it is possible to prevent a gap from forming between the support member 55 and the ring 51.

Since the first flange 53 provided on the ring 51 is in contact with the support member 55, the pressure applied by the ring 51 to the rear end of the support member 55 can be reduced compared to a case where the first flange 53 is not provided. As a result, the effect of suppressing wear and damage of the support member 55 with which the ring 51 is in contact can be improved, so that it is possible to further prevent a gap from forming between the support member 55 and the ring 51.

Since the ring 51 caulked and fixed to the center shaft 30 via the lead pipe 40 and the insulator 50 is difficult to move in the axial direction, the crushing margin of the seal member 56 by the support member 55 and the metal shell 11 can be secured. This maintains the compressed state of the seal member 56, so that airtightness by the seal member 56 can be ensured.

A second embodiment will be described with reference to FIGS. 4 to 6. In the first embodiment, a case has been described in which the rear end facing surface 35 of the large diameter portion 34 of the center shaft 30 and the insulator 50 are separated. In contrast, in the second embodiment, a case will be described in which the rear end facing surface 63 of the large diameter portion 62 of the center shaft 61 is in contact with the insulator 50. Note that the same parts as those described in the first embodiment are given the same reference numerals, and the following description will be omitted.

FIG. 4 is a sectional view including the axis O of the heater 60 in the second embodiment. FIG. 5 is an enlarged cross-sectional view of the heater 60, showing the portion indicated by V in FIG. FIG. 6 is an enlarged cross-sectional view of the heater 60, showing a portion indicated by VI in FIG.

As shown in FIGS. 4 and 5, the heater 60 includes a metal shell 11, a heater element 20, a center shaft 61, a lead pipe 40, an insulator 50, and a ring 51. The center shaft 61 is a metal cylindrical member extending along the axis O. The center shaft 61 is provided with a large diameter portion 62 having a larger diameter than the fixing portion 33 on the distal end side of the fixing portion 33 . The rear end facing surface 63 of the large diameter portion 62 is an annular plane perpendicular to the axis O. The rear end facing surface 63 (the rear end of the large diameter portion 62 ) is located inside the support member 55 in the radial direction, and the tip 55 a of the support member 55 is located on the distal side of the rear end facing surface 63 of the large diameter portion 62 . Located in The rear end facing surface 63 is in contact with the tip 50a of the insulator 50.

As shown in FIG. 6, the distal end portion 64 of the center shaft 61 is provided with a fitting portion 65 that fits into the first member 43. As shown in FIG. The distal end portion 64 is provided with a distal end facing surface 66 at a position at the rear end of the fitting portion 65 . When the fitting portion 65 is fitted into the first member 43, the first member 43 cannot advance beyond the distal end facing surface 66 toward the rear end side. Therefore, positioning of the first member 43 on the center shaft 61 becomes easy.

In the heater 60, when the center shaft 61 is pulled toward the rear end in the axial direction, the insulator 50 sandwiched between the crimp portion 52 and the rear end facing surface 63 of the large diameter portion 62 is immediately compressed in the axial direction. Ru. Therefore, compared to the case where the rear end facing surface 63 of the large diameter portion 62 of the center shaft 61 and the insulator 50 are separated, the amount of displacement of the center shaft 61 toward the rear end can be further reduced.

A third embodiment will be described with reference to FIG. In the second embodiment, a case has been described in which the rear end facing surface 63 of the large diameter portion 62 of the center shaft 61 is an annular plane perpendicular to the axis O. In contrast, in the third embodiment, a case will be described in which the rear end facing surface 73 of the large diameter portion 72 of the center shaft 71 is a conical surface. Note that the same parts as those described in the first embodiment are given the same reference numerals, and the following description will be omitted.

FIG. 7 is a sectional view including the axis O of the heater 70 in the third embodiment. Similar to FIG. 2, FIG. 7 is an enlarged cross-sectional view of the heater 70 of the portion indicated by II in FIG.

As shown in FIG. 7, the heater 70 includes a metal shell 11, a heater element 20, a center shaft 71, a lead pipe 40, an insulator 50, and a ring 51. The center shaft 71 is a metal cylindrical member extending along the axis O. The center shaft 71 is provided with a large diameter portion 72 having a larger diameter than the fixing portion 33 on the distal end side of the fixing portion 33 . The rear end-facing surface 73 of the large diameter portion 72 is a conical surface whose diameter decreases toward the rear end side. The rear end facing surface 73 is located inside the support member 55 in the radial direction, and the tip 55a of the support member 55 is located closer to the front end than the rear end 74 of the large diameter portion 72 (the rear end of the rear end facing surface 73). To position. The tip 50a of the insulator 50 is located closer to the tip than the tip 75 of the rear end facing surface 73. That is, the rear end facing surface 73 of the large diameter portion 72 is in contact with the insulator 50 .

In the heater 70, when the center shaft 71 is pulled toward the rear end in the axial direction, the insulator 50 sandwiched between the crimp portion 52 and the rear end facing surface 73 of the large diameter portion 72 is immediately compressed in the axial direction. Ru. Therefore, compared to the case where the rear end facing surface 73 of the large diameter portion 72 of the center shaft 71 and the insulator 50 are separated, the amount of displacement of the center shaft 71 toward the rear end can be further reduced.

The present invention will be explained in more detail with reference to examples, but the present invention is not limited to these examples.

Various sample numbers with different tensile strengths of the insulator 50 were prepared. 1-4 was manufactured based on the heater 10 of the first embodiment. In sample 1, the insulator 50 was a sheet of hard unfired mica (a type of flexible mica) wound around the center shaft 30, and the tensile strength of the insulator 50 was 250 MPa. Sample 2 was a tube made of PPS (a type of super engineering plastic) as the insulator 50, and the tensile strength of the insulator 50 was 140 MPa. In sample 3, the insulator 50 was a tube of PEEK (a type of super engineering plastic), and the tensile strength of the insulator 50 was 90 MPa. In sample 4, the insulator 50 was a polyolefin tube, and the tensile strength of the insulator 50 was 20 MPa.

The tensile strength of the insulator 50 was measured in accordance with ASTM D638:2003. A dumbbell-shaped test piece with a distance between marked lines of 50 mm was used to measure the tensile strength. Sample No. A list of 1-4 is shown in Table 1.

サンプルＮｏ．１－４の主体金具１１のおねじ１２を、金属製のブロック（図示せず）のねじ穴に規定トルクで締め付けた後、引張試験機を用いて、ブロックに対して中軸３０の後端部３２を軸線方向に引っ張り、荷重を測定する引張試験を行った。荷重が増加すると、絶縁体５０が著しく変形し始め、その変形速度が荷重の負荷速度（引張速度）より大きくなると、一時的に荷重が低下する。荷重が低下し始めたときを、中軸３０が軸線方向にずれたときとみなし、荷重が低下し始める直前の荷重を記録した。その荷重が２３００Ｎ以上はＡ、荷重が２０００Ｎ以上２３００Ｎ未満はＢ、荷重が２０００Ｎ未満はＣと評価した。

Sample No. After tightening the male screw 12 of the metal shell 11 of 1-4 to the specified torque into the screw hole of a metal block (not shown), use a tensile tester to tighten the rear end of the center shaft 30 against the block. A tensile test was conducted by pulling No. 32 in the axial direction and measuring the load. When the load increases, the insulator 50 begins to deform significantly, and when the rate of deformation becomes greater than the loading rate (tensile rate) of the load, the load temporarily decreases. The time when the load started to decrease was regarded as the time when the center shaft 30 shifted in the axial direction, and the load immediately before the load started to decrease was recorded. A load of 2300N or more was evaluated as A, a load of 2000N or more and less than 2300N was evaluated as B, and a load of less than 2000N was evaluated as C.

As shown in Table 1, sample No. Test No. 1-3 had a load of 2000 N or more (rating A or B), which was a satisfactory result. On the other hand, sample No. In No. 4, the load was less than 2000 N (evaluation C). In addition, sample No. before performing the tensile test. When a voltage was applied between the center shaft 30 and the ring 51 of 1-3, the heating element 23 generated heat normally. On the other hand, sample No. before performing the tensile test. When a voltage was applied between the center shaft 30 of 4 and the ring 51, a short circuit occurred. According to this example, it has been revealed that the heater 10 using the insulator 50 having a tensile strength of 80 MPa or more can firmly fix the center shaft 30 to the lead pipe 40.

Although the present invention has been described above based on the embodiments, the present invention is not limited to these embodiments in any way, and it is easily understood that various improvements and modifications can be made without departing from the spirit of the present invention. This can be inferred.

In the embodiment, a case has been described in which the ring 51 also serves as the external terminal of the heaters 10, 60, and 70, but the ring 51 is not necessarily limited to this. It is of course possible to provide an external terminal electrically connected to the lead pipe 40 in addition to the ring 51. In this case, the heater element 20 generates heat by applying a voltage between a separately provided external terminal and the center shafts 30, 61, 71.

In the embodiment, a case has been described in which the cross section of the crimp portion 52 of the ring 51 perpendicular to the axis O is annular, but the present invention is not necessarily limited to this. For example, it is of course possible to make the cross section of the crimp portion 52 perpendicular to the axis O into a polygonal cylinder shape such as an ellipse, a triangle, or a hexagon. In addition, if there is a cut in a part of the crimped part like a C-ring, physical pressure is applied to the crimped part to plastically deform a part of the circumference of the lead pipe 40 so that the parts without the cut come closer to each other. let

The physical pressure that the crimp section 52 applies to the insulator 50 via the lead pipe 40 may be non-uniform in the circumferential direction of the insulator 50. Furthermore, on the inside of the crimp portion 52 in the radial direction, the physical pressure of the insulator 50 becomes non-uniform in the circumferential direction, resulting in a partial gap between the center shafts 30, 61, 71 or the lead pipe 40 and the insulator 50. It does not matter if there is a gap between the two.

In the embodiment, a case has been described in which the ring 51 is provided with the first flange 53 and the second flange 54, but the present invention is not necessarily limited to this. Of course, it is possible to omit at least one of the first flange 53 and the second flange 54.

In the embodiment, a case has been described in which the rear end facing surfaces 36, 73 of the large diameter portions 34, 72 of the center shafts 30, 71 are conical surfaces, but the present invention is not necessarily limited to this. Instead of the rear end facing surfaces 36, 73 being conical surfaces, it is of course possible to make the rear end facing surfaces 36, 73 spherical.

In the embodiment, a case has been described in which the rear end facing surfaces 36, 63, 73 of the large diameter portions 34, 62, 72 are continuous over the entire circumference of the center shafts 30, 61, 71, but this is not necessarily the case. It's not something you can do. Of course, it is possible to provide a large diameter portion on a portion of the entire circumference of the center shafts 30, 61, 71 so that the surface facing the rear end is set. Such large diameter portions include, for example, one or more protrusions partially protruding from the outer periphery of the center shafts 30, 61, 71, tooth profiles provided intermittently on the outer peripheries of the center shafts 30, 61, 71, etc. .

In the third embodiment, a case has been described in which the tip 50a of the insulator 50 is located closer to the tip than the tip 75 of the rear end facing surface 73, but the present invention is not necessarily limited to this. It is of course possible to arrange the insulator 50 on the center shaft 71 so that the tip 50a of the insulator 50 is located at the tip 75 of the rear end facing surface 73, so that the insulator 50 is in contact with the rear end facing surface 73. .

The tip portion 64 (including the fitting portion 65) of the center shaft 61 in the second embodiment is provided on the center shaft 30, 71 instead of the tip portion 31 of the center shaft 30, 71 in the first embodiment or the third embodiment. Of course it is possible. On the contrary, it is of course possible to provide the distal end portions 31 of the central shafts 30 and 71 on the central shaft 61 instead of the distal end portion 64 of the central shaft 61 in the second embodiment.

In the embodiment, a case has been described in which the support member 55 is a single member having a flange, but the support member 55 is not necessarily limited to this. It is of course possible to configure the support member 55 by combining a plurality of members.

In the embodiment, a case has been described in which the sealing member 56 is an O-ring having a circular cross section, but the sealing member 56 is not necessarily limited to this. It is of course possible to make the cross section of the sealing member 56 rectangular or to provide it with a lip. The support member 55 and the seal member 56 may be integrated.

In the embodiment, a case has been described in which the base body 21 of the heater element 20 is formed in a cylindrical shape, but the base body 21 is not necessarily limited to this. The shape of the base body 21 can be set as appropriate depending on the purpose. For example, it is naturally possible to make the cross section perpendicular to the axis O of the base body into an elliptical shape, a polygonal shape, or the like. Furthermore, the heater element is not limited to one having a rod-shaped base. For example, it is naturally possible to use a so-called plate-shaped heater element in which a resistor is sandwiched between plate-shaped bases.

There are no restrictions on the uses of the heaters 10, 60, 70 in the embodiments. Examples of uses of the heaters 10, 60, and 70 include heaters used in glow plugs, diesel particulate filters (DPF), burner ignition heaters, gas sensor heaters, and the like.

In the embodiment, the heater element 20 and the first member 43 and the second member 44 have a press-fit structure, and the first external electrode 25 and the second external electrode of the heater element 20 press-fitted into the first member 43 and the second member 44 Although the case where the first member 43 and the second member 44 are directly connected to the electrode 26 has been described, the present invention is not necessarily limited to this. For example, it is naturally possible to connect the first external electrode 25 and second external electrode 26 of the heater element 20 and the first member 43 and second member 44 using a conductive material such as a wire or a brazing material. Further, after providing leads electrically connected to the first external electrode 25 and the second external electrode 26 on the surface of the base 21 made of insulating ceramic, the leads and the first member 43 and the second member 44 are electrically connected. Of course, it is possible to connect

10, 60, 70 Heater 11 Metal shell 14 Tip of metal shell 15 Rear end of metal shell 20 Heater element 25 First external electrode 26 Second external electrode 27 Tip portion 30, 61, 71 Center shaft 32 Rear end of center shaft 33 Fixation Parts 34, 62, 72 Large diameter portion 35, 63, 73 Surface facing rear end 36, 74 Rear end of large diameter portion 40 Lead tube 42 Rear end portion of lead tube 50 Insulator 51 Ring 55 Support member 55a Tip of support member 63 Rear end facing surface (rear end of large diameter part)
O axis

Claims (5)

a cylindrical main metal fitting extending along the axis;
a heater element that is disposed inside the metal shell with its tip protruding from the tip of the metal shell, and includes a first external electrode and a second external electrode;
a center shaft disposed inside the metal shell with its rear end protruding from the rear end of the metal shell, and electrically connected to the first external electrode;
a lead pipe disposed between the metal shell and the center shaft with its rear end protruding from the rear end of the metal shell, and electrically connected to the second external electrode. A heater,
a soft insulator disposed between the rear end of the center shaft and the rear end of the lead pipe;
a ring disposed around the rear end of the lead tube;
The ring is caulked and fixed to the fixed part of the center shaft via the lead pipe and the insulator. The heater according to claim 1, wherein the insulator has a tensile strength of 80 MPa or more. 3. The heater according to claim 1, wherein the center shaft is provided with a large-diameter portion having a larger diameter than the fixing portion on a distal end side of the fixing portion. The heater according to claim 3, wherein a rear end facing surface of the large diameter portion is in contact with the insulator. an electrically insulating cylindrical support member disposed between the metal shell and the lead pipe and between the metal shell and the ring;
The heater according to claim 3 or 4, wherein the rear end of the large diameter portion is located closer to the rear end than the tip of the support member.

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