JP2021093352A - heater - Google Patents

Abstract

To provide a heater in which a lead pipe can be firmly fixed to a center shaft.SOLUTION: A heater comprises: a cylindrical main metal fitting; a heater element disposed inside of the main metal fitting in a state where its own front end portion protrudes from a front end of the main metal fitting, and includes a first external electrode and a second external electrode; a center shaft which is disposed inside of the main metal fitting in a state where its own rear end portion protrudes from a rear end of the main metal fitting, and electrically connected with the first external electrode; a lead pipe which is disposed between the main metal fitting and the center shaft in a state where its own rear end portion protrudes from the rear end of the main metal fitting, and electrically connected with the second external electrode; a soft insulator disposed between the rear end portion of the center shaft and the rear end portion of the lead pipe; and a ring disposed around the rear end portion of the lead pipe. The ring is caulked to the center shaft via the lead pipe and the insulator.SELECTED DRAWING: Figure 1

Description

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

A heater in which the tip of the heater element protrudes from the tip of the tubular main metal fitting, the central shaft is electrically connected to the first external electrode of the heater element, and the lead tube is electrically connected to the second external electrode of the heater element. Is known (Patent Document 1). The heater disclosed in Patent Document 1 is a rubber cylinder between the rear end of the center pole protruding from the rear end of the main metal fitting and the rear end of the lead tube in order to prevent a short circuit between the center pole and the lead tube. Shaped insulators are arranged. The rear end of the center pole is fixed to the reed tube by the rubber elasticity (restoring force) of the insulator compressed in its radial direction.

JP-A-2017-166758

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

The present invention has been made to solve this problem, and an object of the present invention is to provide a heater capable of strongly fixing a center pole to a lead tube.

In order to achieve this object, the heater of the present invention is arranged inside the main metal fitting with a tubular main metal fitting extending along the axis and its own tip protruding from the tip of the main metal fitting. A heater element having a first external electrode and a second external electrode is arranged inside the main metal fitting with its rear end protruding from the rear end of the main metal fitting, and is electrically connected to the first external electrode. A lead tube that is arranged between the main metal fitting and the central shaft with its rear end protruding from the rear end of the main metal fitting, and a lead tube that is electrically connected to the second external electrode, and the central shaft. It comprises a soft insulator placed between the rear end and the rear end of the lead tube and a ring placed around the rear end of the lead tube, the ring providing the lead tube and insulator. It is caulked and fixed to the fixed part of the central shaft via.

According to the first aspect, a soft insulator is placed between the rear end of the center pole and the rear end of the lead tube, and a ring is placed around the rear end of the lead tube. Since the ring is caulked and fixed to the fixing portion of the central shaft via the lead tube and the insulator, the central shaft can be strongly fixed to the lead tube as compared with fixing the central shaft to the lead tube by using rubber elasticity. As a result, even if a force in the axial direction is applied to the center pole when handling the heater, it is possible to prevent the center pole from shifting.

According to the second aspect, since the insulator has a tensile strength of 80 MPa or more, it is possible to make it difficult for the insulator sandwiched between the center pole and the lead tube to extend 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 central axis, so that the central axis can be more strongly fixed to the lead tube in addition to the effect of the first aspect.

According to the third aspect, the central shaft is provided with a large diameter portion having a diameter larger than that of the fixed portion on the tip side of the fixed portion to which the insulator is fixed. As a result, when the center pole is pulled toward the rear end side in the axial direction and the large diameter portion hits the insulator, the insulator sandwiched between the crimping portion and the large diameter portion is compressed in the axial direction, and the reaction force thereof. Therefore, it is possible to reduce the further deviation of the center pole toward the rear end side. Therefore, in addition to the effect of the first or second aspect, the amount of deviation of the center pole 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 pole is pulled toward the rear end side in the axial direction, the insulator sandwiched between the crimping portion and the large diameter portion is immediately compressed in the axial direction. Therefore, in addition to the effect of the third aspect, the amount of deviation of the center pole toward the rear end side can be further reduced.

According to the fifth aspect, an electrically insulating tubular support member is arranged between the main metal fitting and the lead pipe and between the main metal fitting and the ring. The rear end of the large diameter portion is located on the rear end side of the tip of the support member. As a result, the insulator is deformed by caulking the ring to the central shaft, and the deformed insulator spreads radially outward along the large diameter portion, and even if the insulator pushes the lead tube outward in the radial direction. , The support member reduces the deformation of the lead tube. Therefore, in addition to the effect of the third or fourth aspect, a short circuit between the lead tube and the main metal fitting can be prevented.

It is sectional drawing of the heater in 1st Embodiment. It is sectional drawing of the heater which enlarged the part shown by II of FIG. It is sectional drawing of the heater in line III-III of FIG. It is sectional drawing of the heater in 2nd Embodiment. It is sectional drawing of the heater which enlarged the part shown by V of FIG. It is sectional drawing of the heater which enlarged the part shown by VI of FIG. It is sectional drawing of the heater in 3rd Embodiment.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a cross-sectional view including an axis O of the heater 10 according to the first embodiment of the present invention. FIG. 2 is a cross-sectional view of the heater 10 in which the portion shown by II in FIG. 1 is enlarged. In FIGS. 1 and 2, the lower side of the paper surface is referred to as the front end side of the heater 10, and the upper side of the paper surface 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 main metal fitting 11, a heater element 20, a center pole 30, a lead tube 40, an insulator 50, and a ring 51.

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

The outer cylinder 16 is a substantially cylindrical metal member (for example, stainless steel or the like) extending along the axis O. The outer cylinder 16 is joined to the tip 14 of the main metal fitting 11. The outer cylinder 16 holds the heater element 20 in a state where the tip portion 27 of the heater element 20 is projected toward the tip side. In the present embodiment, the heater element 20 and the outer cylinder 16 have a press-fitting structure.

The heater element 20 is a substantially columnar member extending along the axis O. The heater element 20 includes a base 21 and a resistor 22 embedded in the base 21. The substrate 21 is made of a substantially columnar insulating ceramic. In this embodiment, the tip of the substrate 21 is formed in a spherical crown shape. The insulating ceramic constituting the substrate 21 contains, for example, silicon nitride as a main component. The resistor 22 is made of a conductive ceramic and contains, for example, tungsten carbide and silicon nitride. The resistors 22 are a pair of a heating element 23 that is embedded in the tip end side of the substrate 21 and bent along the tip end of the substrate 21, and a pair that is connected to the rear end side of the heating element 23 and extends along the axis O toward the rear end side. The lead portion 24 of the above 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 substrate 21. The other lead portion 24 is provided with a second external electrode 26 exposed on the outer peripheral surface of the substrate 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 portion 24. The first external electrode 25 and the second external electrode 26 are located inside the main metal fitting 11.

Since the cross-sectional area of the heating element 23 is narrower than the cross-sectional area of the lead portion 24, even if the material of the conductive ceramic constituting the heating element 23 is the same as the material of the conductive ceramic constituting the lead portion 24, the resistance of the heating element 23 is increased. It can be 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 the amount of heat generated by the lead portion 24, so that the heating element 23 can be selectively generated. Instead of making the cross-sectional areas of the heating element 23 and the lead portion 24 different, a material having a specific resistance larger than that of the lead portion 24 is used for the heating element 23 to selectively generate heat of the heating element 23. Of course it is possible.

The center pole 30 is a metal columnar member extending along the axis O. The tip portion 31 of the center pole 30 is arranged inside the main metal fitting 11 with a gap from the heater element 20 on the rear end side of the heater element 20. The rear end portion 32 of the center pole 30 projects from the rear end 15 of the main metal fitting 11. A fixing portion 33 is provided at the rear end portion 32 (see FIG. 2) of the center pole 30. The lead tube 40 and the insulator 50 are fixed to the fixing portion 33 by the ring 51. The center pole 30 is provided with a large diameter portion 34 having a diameter larger than that of the fixed portion 33 on the tip end side of the fixed portion 33. The large diameter portion 34 is continuous to the tip portion 31 of the center pole 30. The rear end facing surface 35 of the large diameter portion 34 is a conical surface whose diameter is reduced toward the rear end side.

The lead tube 40 is a metal tubular member extending along the axis O. The lead pipe 40 is arranged on the outside of the center pole 30 in the radial direction and on the inside of the main metal fitting 11 in the radial direction with a gap from the main metal fitting 11 and the center pole 30. The tip 41 of the lead tube 40 is located outside the first external electrode 25 of the heater element 20 in the radial direction. The rear end portion 42 of the lead pipe 40 projects from the rear end 15 of the main metal fitting 11.

The first member 43 is a metal tubular member extending along the axis O. The first member 43 is arranged inside the tip portion 41 of the lead tube 40 in the radial direction with a gap from the lead tube 40. The first member 43 electrically connects the tip portion 31 of the center pole 30 and the first external electrode 25 of the heater element 20. In the present embodiment, the heater element 20 and the first member 43 have a press-fitting structure, and the first member 43 is directly connected to the first external electrode 25.

The second member 44 is a metal tubular member extending along the axis O. The second member 44 is arranged on the tip side of the heater element 20 with respect to the first external electrode 25 and inside the main metal fitting 11 in the radial direction with a gap from the first member 43 and the main metal fitting 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 the present embodiment, the heater element 20 and the second member 44 have a press-fitting structure, and the second member 44 is directly connected to the second external electrode 26.

A soft insulator 50 that separates the center pole 30 and the lead pipe 40 is arranged between the rear end portion 32 of the center pole 30 and the rear end portion 42 of the lead pipe 40. The tip 50a of the insulator 50 is located closer to the tip than the rear end 15 of the main metal fitting 11. The tip 50a of the insulator 50 is separated from the rear end 36 of the large diameter portion 34 of the center pole 30.

Examples of the material of the insulator 50 include mica such as peeling mica and aggregated mica, flexible mica containing an adhesive (reinforcing material if necessary), engineering plastics, and super engineering plastics. Engineering plastics include, for example, polyacetal (POM) and polyamide (PA). Examples of super engineering plastics include polyphenylene sulfide (PPS) and polyetheretherketone (PEEK). The shape of the insulator 50 is a tubular shape having a continuous entire circumference, a sheet wound around the center pole 30 to provide a cut in a part of the circumference, and a sheet wound around the center pole 30 at both ends in the circumferential direction. The one in which the above is overlapped is used.

The ring 51 is a metal member that surrounds the rear end portion 42 of the lead pipe 40 from the outer circumference. The ring 51 includes a crimping portion 52, a first flange 53 protruding outward in the radial direction from the tip of the crimping portion 52, and a second flange 54 protruding outward in the radial direction from the rear end of the crimping portion 52. And have. The ring 51 is fixed to the rear end portion 42 of the lead pipe 40 by the physical pressure of the crimping portion 52.

Due to the physical pressure applied to the crimping portion 52, at least a part of the crimping portion 52 is plastically deformed inward in the radial direction. As a result, at least a part of the crimping portion 52 is in close contact with the rear end portion 42 of the lead pipe 40. As the shape of the ring 51, an annular shape having a continuous entire circumference, a ring having a cut in a part of the circumference such as a C ring, or the like is used.

The support member 55 is a tubular member arranged on the main metal fitting 11 and surrounding the lead pipe 40, and has electrical insulation. The rear end of the flange of the support member 55 is located closer to the rear end side than the rear end 15 of the main metal fitting 11, and the tip 55a of the support member 55 is located closer to the front end side than the rear end 15 of the main metal fitting 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 tip 55a of the support member 55 is located closer to the tip side than the rear end 36 of the large diameter portion 34. The support member 55 is inserted into the rear end 15 of the main metal fitting 11, and the movement of the support member 55 to the front end side is restricted by the main metal fitting 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 tube 40 from the main metal fitting 11 in the radial direction. Further, the support member 55 is interposed between the main metal fitting 11 and the ring 51 to separate the ring 51 from the main metal fitting 11 in the axial direction. The support member 55 can electrically insulate between the main metal fitting 11 and the lead pipe 40 and between the main metal fitting 11 and the ring 51.

The seal member 56 is a ring-shaped member that surrounds the lead pipe 40, and is arranged between the tip of the support member 55 and the inner peripheral surface of the main metal fitting 11. In the present embodiment, the seal member 56 is an O-ring and electrically insulates between the main metal fitting 11 and the lead pipe 40. Since the seal member 56 is arranged in a compressed state, the main metal fitting 11 and the lead tube 40 are 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 portion 32 of the center pole 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.

The physical pressure of the plastically deformed crimping portion 52 (ring 51) pushes the radial inner portion of the crimping portion 52 in the lead pipe 40 and plastically deforms it inward in the radial direction. Since the insulator 50 is soft, it deforms from its natural state when a force is applied. Therefore, due to the physical pressure of the plastically deformed lead tube 40, the insulator 50 is deformed inward in the radial direction and presses the fixing portion 33 of the central shaft 30. That is, the ring 51 is caulked and fixed to the fixing portion 33 of the center pole 30 via the lead tube 40 and the insulator 50.

As a result, the center pole 30 can be strongly fixed to the lead tube 40 as compared with fixing the lead tube 40 to the center pole 30 by using only the elasticity of the insulator 50. As a result, even if a force is applied to the center pole 30 in the axial direction when the heater 10 is handled, such as when the heater 10 is attached to an internal combustion engine (not shown), it is possible to prevent the center pole 30 from being displaced 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 pole 30 is fixed to the lead tube 40 via the insulator 50. The tensile strength of the material of insulator 50 is measured according to ASTM D638: 2003. A dumbbell-shaped test piece having a distance between marked lines of 50 mm is used for measuring 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 the center pole 30 is fixed to the lead tube 40 via the insulator 50, and to reduce the deformation of the lead tube 40 and the center pole 30.

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

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

In the present embodiment, the insulator 50 has a tensile strength of 80 MPa or more. As a result, the insulator 50 can be made more difficult to extend in the axial direction, so that the rear end portion 42 of the lead tube 40 can be made less likely to shift in the axial direction with respect to the rear end portion 32 of the center pole 30. Since the center pole 30 can be more strongly fixed to the lead pipe 40, it is possible to prevent the center pole 30 from being displaced in the axial direction due to the load applied to the heater 10.

When the insulator 50 is sandwiched between the lead pipe 40 pushed inward by the plastic deformation of the crimping portion 52 and the center pole 30 when the ring 51 is crimped and fixed, the insulator 50 is compressed in the radial direction and extends in the axial direction. .. An axial force is applied to the center pole 30 by 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 axial deviation of the center pole 30 due to the friction of the insulator 50.

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

The rear end 36 of the large diameter portion 34 of the center pole 30 is located on the rear end side of the tip 55a of the support member 55. As a result, the insulator 50 is deformed by caulking the ring 51 to the central shaft 30, and the deformed insulator 50 spreads radially outward along the large diameter portion 34, and is led outward by the insulator 50 in the radial direction. Even if the tube 40 is pushed, the support member 55 reduces the deformation of the lead tube 40. Therefore, it is possible to prevent a short circuit between the lead tube 40 and the main metal fitting 11.

The first flange 53 of the ring 51 hits the rear end of the support member 55 fixed between the main metal fitting 11 and the lead pipe 40. Since the movement of the support member 55 toward the tip end side is restricted by the main metal fitting 11, it is possible to prevent a gap from being formed 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 to the rear end of the support member 55 can be reduced as compared with the case where the first flange 53 is not provided. As a result, the effect of suppressing wear and breakage of the support member 55 in contact with the ring 51 can be improved, so that a gap between the support member 55 and the ring 51 can be further reduced.

Since the ring 51 crimped and fixed to the central shaft 30 via the lead pipe 40 and the insulator 50 is difficult to move in the axial direction, it is possible to secure a crushing allowance for the seal member 56 by the support member 55 and the main metal fitting 11. As a result, the compressed state of the seal member 56 is maintained, so that the airtightness of the seal member 56 can be ensured.

The second embodiment will be described with reference to FIGS. 4 to 6. In the first embodiment, the case where the rear end facing surface 35 of the large diameter portion 34 of the center pole 30 and the insulator 50 are separated from each other has been described. On the other hand, in the second embodiment, the case where the rear end facing surface 63 of the large diameter portion 62 of the center pole 61 is in contact with the insulator 50 will be described. The same parts as those described in the first embodiment are designated by the same reference numerals, and the following description will be omitted.

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

As shown in FIGS. 4 and 5, the heater 60 includes a main metal fitting 11, a heater element 20, a center pole 61, a lead tube 40, an insulator 50, and a ring 51. The center pole 61 is a metal columnar member extending along the axis O. The center pole 61 is provided with a large diameter portion 62 having a diameter larger than that of the fixed portion 33 on the tip end side of the fixed 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 (rear end of the large diameter portion 62) is located inside the support member 55 in the radial direction, and the tip 55a of the support member 55 is on the tip 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 tip portion 64 of the center pole 61 is provided with a fitting portion 65 that fits into the first member 43. The tip portion 64 is provided with a tip facing surface 66 at the position of the rear end of the fitting portion 65. When the fitting portion 65 fits into the first member 43, the first member 43 cannot advance to the rear end side of the front end facing surface 66. Therefore, positioning of the first member 43 on the center pole 61 becomes easy.

In the heater 60, when the center pole 61 is pulled toward the rear end side in the axial direction, the insulator 50 sandwiched between the crimping portion 52 and the rear end facing surface 63 of the large diameter portion 62 is immediately compressed in the axial direction. To. Therefore, the amount of displacement of the center pole 61 toward the rear end side can be further reduced as compared with the case where the rear end facing surface 63 of the large diameter portion 62 of the center pole 61 and the insulator 50 are separated from each other.

The third embodiment will be described with reference to FIG. 7. In the second embodiment, the case where the rear end facing surface 63 of the large diameter portion 62 of the center pole 61 is an annular plane perpendicular to the axis O has been described. On the other hand, in the third embodiment, the case where the rear end facing surface 73 of the large diameter portion 72 of the center pole 71 is a conical surface will be described. The same parts as those described in the first embodiment are designated by the same reference numerals, and the following description will be omitted.

FIG. 7 is a cross-sectional view including the axis O of the heater 70 according to the third embodiment. FIG. 7 is a cross-sectional view of the heater 70 in which the portion shown by II in FIG. 1 is enlarged as in FIG.

As shown in FIG. 7, the heater 70 includes a main metal fitting 11, a heater element 20, a center pole 71, a lead tube 40, an insulator 50, and a ring 51. The center pole 71 is a metal columnar member extending along the axis O. The center pole 71 is provided with a large diameter portion 72 having a diameter larger than that of the fixed portion 33 on the tip end side of the fixed portion 33. The rear end facing surface 73 of the large diameter portion 72 is a conical surface whose diameter is reduced 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 closer to the tip side than the rear end 74 (rear end of the rear end facing surface 73) of the large diameter portion 72. 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 pole 71 is pulled toward the rear end side in the axial direction, the insulator 50 sandwiched between the crimping portion 52 and the rear end facing surface 73 of the large diameter portion 72 is immediately compressed in the axial direction. To. Therefore, the amount of displacement of the center pole 71 toward the rear end side can be further reduced as compared with the case where the rear end facing surface 73 of the large diameter portion 72 of the center pole 71 and the insulator 50 are separated from each other.

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

Various sample numbers having different tensile strengths of the insulator 50. 1-4 were made based on the heater 10 of the first embodiment. Sample 1 was obtained by winding a sheet of hard unfired mica (a type of flexible mica) around a center pole 30 to form an insulator 50, and the tensile strength of the insulator 50 was 250 MPa. In Sample 2, a tube of PPS (a kind of super engineering plastic) was used as an insulator 50, and the tensile strength of the insulator 50 was 140 MPa. In Sample 3, a PEEK (a type of super engineering plastic) tube was used as an insulator 50, and the tensile strength of the insulator 50 was 90 MPa. In Sample 4, a polyolefin-based tube was used as an insulator 50, and the tensile strength of the insulator 50 was 20 MPa.

The tensile strength of the insulator 50 was measured according to ASTM D638: 2003. A dumbbell-shaped test piece having a distance between marked lines of 50 mm was used for measuring 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 screws 12 of the main metal fittings 11 of 1-4 to the screw holes of the metal block (not shown) with the specified torque, use a tensile tester to tighten the rear end of the center shaft 30 with respect to the block. A tensile test was performed in which 32 was pulled in the axial direction to measure the load. When the load increases, the insulator 50 begins to be significantly deformed, and when the deformation speed becomes larger than the load speed (tensile speed) of the load, the load temporarily decreases. The time when the load started to decrease was regarded as the time when the center pole 30 was displaced in the axial direction, and the load immediately before the load started to decrease was recorded. The load was evaluated as A when the load was 2300 N or more, B when the load was 2000 N or more and less than 2300 N, and C when the load was less than 2000 N.

As shown in Table 1, sample No. In 1-3, the load was 2000 N or more (evaluation 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, the sample No. before the tensile test was performed. When a voltage was applied between the center pole 30 and the ring 51 of 1-3, the heating element 23 normally generated heat. On the other hand, the sample No. before the tensile test was performed. When a voltage was applied between the center pole 30 of 4 and the ring 51, a short circuit was formed. According to this example, it was clarified that the heater 10 using the insulator 50 having a tensile strength of 80 MPa or more can strongly fix the center pole 30 to the lead tube 40.

Although the present invention has been described above based on the embodiments, the present invention is not limited to this embodiment, and it is easy to make various improvements and modifications within a range that does not deviate from the gist of the present invention. It can be inferred.

In the embodiment, the case where the ring 51 also serves as the external terminal of the heaters 10, 60, and 70 has been described, but the present invention is not necessarily limited to this. Of course, it is possible to provide an external terminal electrically connected to the lead tube 40 separately from the ring 51. In this case, the heater element 20 generates heat by applying a voltage between the separately provided external terminal and the center poles 30, 61, 71.

In the embodiment, the case where the cross section of the crimping portion 52 of the ring 51 perpendicular to the axis O is annular has been described, but the present invention is not necessarily limited to this. For example, it is naturally possible to make the cross section of the crimping portion 52 perpendicular to the axis O into a polygonal cylinder such as an ellipse, a triangle, or a hexagon. Further, when there is a cut in a part of the crimping portion like a C ring, a physical pressure is applied to the crimping portion so that the uncut portions come close to each other, and a part of the circumference of the lead pipe 40 is plastically deformed. Let me.

The physical pressure applied to the insulator 50 by the crimping portion 52 via the lead pipe 40 may be non-uniform in the circumferential direction of the insulator 50. Further, inside the crimping portion 52 in the radial direction, the physical pressure of the insulator 50 becomes non-uniform in the circumferential direction, so that the center poles 30, 61, 71 and the lead pipe 40 are partially between the insulator 50. There may be a gap in the space.

In the embodiment, the case where the ring 51 is provided with the first flange 53 and the second flange 54 has been described, 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, the case where the rear end facing surfaces 36 and 73 of the large diameter portions 34 and 72 of the center poles 30 and 71 are conical surfaces has been described, but the present invention is not necessarily limited to this. Of course, it is possible to make the rear end facing surfaces 36, 73 into a spherical band instead of the rear end facing surfaces 36, 73 of the conical surface.

In the embodiment, the case where 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 poles 30, 61, 71 has been described, but is not necessarily limited to this. It is not something that can be done. Of course, it is possible to provide a large diameter portion so that the rear end facing surface is set on a part of the entire circumference of the center poles 30, 61, 71. Examples of such a large-diameter portion include one or a plurality of protrusions partially protruding from the outer circumference of the center poles 30, 61, 71, and a tooth profile intermittently provided on the outer circumference of the center poles 30, 61, 71. ..

In the third embodiment, the case where the tip 50a of the insulator 50 is on the tip side of the tip 75 of the rear end facing surface 73 has been described, but the present invention is not necessarily limited to this. It is of course possible to arrange the insulator 50 on the center pole 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 of the center pole 61 (which includes the fitting portion 65) in the second embodiment is provided on the center poles 30 and 71 in place of the tip portions 31 of the center poles 30 and 71 in the first embodiment and the third embodiment. Of course it is possible. On the contrary, it is naturally possible to provide the tip portions 31 of the center poles 30 and 71 on the center pole 61 instead of the tip end portion 64 of the center pole 61 in the second embodiment.

In the embodiment, the case where the support member 55 is one member having a flange has been described, but the present invention is not necessarily limited to this. Of course, it is possible to combine a plurality of members to form the support member 55.

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

In the embodiment, the case where the substrate 21 of the heater element 20 is formed in a columnar shape has been described, but the present invention is not necessarily limited to this. The shape of the substrate 21 can be appropriately set according to the application. For example, it is naturally possible to make the cross section orthogonal to the axis O of the substrate into an elliptical shape, a polygonal shape, or the like. Further, the heater element is not limited to the one having a rod-shaped substrate. For example, it is naturally possible to use a so-called plate-shaped heater element in which a resistor is sandwiched between plate-shaped substrates.

There is no limitation on the use of the heaters 10, 60, 70 in the embodiment. Applications of the heaters 10, 60, 70 include, for example, a glow plug, a heater used for a Diesel particulate filter (DPF), a burner ignition heater, a gas sensor heating heater, and the like.

In the embodiment, the heater element 20 and the first member 43 and the second member 44 form a press-fitting structure, and the first external electrode 25 and the second external electrode 25 and the second external 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 or the second external electrode 26 of the heater element 20 with the first member 43 or the second member 44 by a conductive material such as a wire or a brazing material. Further, after providing a lead electrically connected to the first external electrode 25 and the second external electrode 26 on the surface of the substrate 21 made of insulating ceramic, the lead and the first member 43 and the second member 44 are electrically connected. Of course, it is possible to connect to the target.

10, 60, 70 Heater 11 Main metal fittings 14 Main metal fitting tip 15 Rear end of main metal fitting 20 Heater element 25 1st external electrode 26 2nd external electrode 27 Tip part 30, 61, 71 Central shaft 32 Rear end of central shaft 33 Fixed Part 34, 62, 72 Large diameter part 35, 63, 73 Rear end facing surface 36,74 Rear end of large diameter part 40 Lead pipe 42 Rear end of lead pipe 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)

Cylindrical main metal fittings extending along the axis and
A heater element that is arranged inside the main metal fitting with its tip protruding from the tip of the main metal fitting and has a first external electrode and a second external electrode.
A center pole that is arranged inside the main metal fitting with its rear end protruding from the rear end of the main metal fitting and is electrically connected to the first external electrode.
A lead tube is provided between the main metal fitting and the center pole with its rear end protruding from the rear end of the main metal fitting, and is electrically connected to the second external electrode. It ’s a heater,
A soft insulator disposed between the rear end of the center pole and the rear end of the lead tube.
A ring disposed around the rear end of the lead tube.
The ring is a heater that is caulked and fixed to a fixed portion of the center pole via the lead tube and the insulator. The heater according to claim 1, wherein the insulator has a tensile strength of 80 MPa or more. The heater according to claim 1 or 2, wherein the center pole is provided with a large diameter portion having a diameter larger than that of the fixed portion on the tip side of the fixed portion. The heater according to claim 3, wherein the rear end facing surface of the large diameter portion is in contact with the insulator. An electrically insulating tubular support member arranged between the main metal fitting and the lead pipe and between the main metal fitting and the ring is provided.
The heater according to claim 3 or 4, wherein the rear end of the large diameter portion is located on the rear end side of the tip of the support member.

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