JP5869412B2 - Spark plug - Google Patents

Description

  The present invention relates to a spark plug having a configuration in which a center electrode is inserted into a terminal.

  An igniter plug used for a gas turbine engine, a diesel engine, a burner igniter, or the like generally includes a center electrode and a terminal electrically connected to the center electrode, and the ignition cord connector is connected to the terminal. Connected.

  In the conventional igniter plug, the electrical connection (conductivity) between the center electrode and the terminal is realized by physical contact. Specifically, the electrical connection between the center electrode and the terminal has been realized by inserting the end of the rod-shaped center electrode into the hole formed in the terminal (Patent Document 1).

JP-A-1-283788

  In the technology for realizing the electrical connection between the center electrode and the terminal by physical contact, when the contact surface of the center electrode or the terminal is rough, there is a problem that the contact resistance increases because the contact area is small. there were. Further, when the contact surface of the center electrode or the terminal is oxidized, the contact resistance is increased, and there is a possibility that conduction is poor.

  Such a problem may occur not only in an igniter plug but also in any spark plug having a configuration in which a center electrode is inserted into a terminal, such as a spark plug.

  An object of this invention is to improve the electroconductivity between the center electrode and terminal in a spark plug.

SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.
[Mode 1] Spark plug,
A central electrode having a connection at one end;
A terminal having a hole, and wherein the connection portion is inserted in the hole;
With
The connection part and the terminal are electrically connected to each other through a conductive part having conductivity,
In at least a part of the entire circumference of the portion where the terminal and the connection portion overlap in the radial direction, the diameter of the connection portion is smaller than the diameter of the hole,
The conductive portion is disposed in a gap formed by a difference between the diameter of the connection portion and the diameter of the hole,
The terminal has a cutout portion formed in a radial direction in a part of the inner peripheral surface of the hole,
The spark plug is characterized in that the gap is formed between the cutout portion and an outer peripheral surface of the connection portion.
[Mode 2] A spark plug,
A central electrode having a connection at one end;
A terminal having a hole, and wherein the connection portion is inserted in the hole;
With
The connection part and the terminal are electrically connected to each other through a conductive part having conductivity,
The terminal has a first end surface in which the insertion port of the connection portion in the hole is formed, and a second end surface located on the opposite side in the insertion direction of the connection portion with respect to the first end surface. And
The spark plug is a through hole that allows the first end surface and the second end surface to communicate with each other.

[Application Example 1] A spark plug,
A central electrode having a connection at one end;
A terminal having a hole, and wherein the connection portion is inserted in the hole;
With
The spark plug is characterized in that the connection portion and the terminal are electrically connected to each other through a conductive portion having conductivity.

  According to the spark plug of Application Example 1, since the connection portion and the terminal are electrically connected via the conductive portion, the conductivity between the center electrode and the terminal can be improved. In addition, by adopting such a configuration, even when the contact surface of the center electrode or the terminal is rough, the center electrode (connection portion) and the terminal can be electrically connected through the conductive portion. .

Application Example 2 In the spark plug according to Application Example 1,
In at least a part of the entire circumference of the portion where the terminal and the connection portion overlap in the radial direction, the diameter of the connection portion is smaller than the diameter of the hole,
The spark plug according to claim 1, wherein the conductive portion is disposed in a gap formed by a difference between a diameter of the connection portion and a diameter of the hole.

  With such a configuration, the conductive portion is arranged in the gap formed by the difference between the diameter of the connection portion and the diameter of the hole, and therefore, the central electrode (connection portion) and the conductive portion arranged in the gap The terminal can be electrically connected. Moreover, the displacement of the position of the connecting portion in the hole can be suppressed by the conductive portion by arranging the conductive portion in the gap.

Application Example 3 In the spark plug according to Application Example 2,
In all of the entire circumference, the diameter of the connecting portion is smaller than the diameter of the hole,
The spark plug is characterized in that the air gap is formed between the connection portion and the hole over the entire circumference.

  With such a configuration, the terminal and the connection portion can be electrically connected via the conductive portion over the entire circumference of the portion where the terminal and the connection portion overlap in the radial direction. Can be increased.

Application Example 4 In the spark plug according to Application Example 2,
The terminal has a cutout portion formed in a radial direction in a part of the inner peripheral surface of the hole,
The spark plug is characterized in that the gap is formed between the cutout portion and an outer peripheral surface of the connection portion.

  With such a configuration, even if there is no difference between the diameter of the connecting portion and the diameter of the hole (that is, the inner peripheral diameter of the terminal) in other portions except the notched portion, the notched portion and the connecting portion The connection portion and the terminal can be electrically connected through the conductive portion disposed in the gap between the outer peripheral surface of the first and second outer peripheral surfaces.

Application Example 5 In the spark plug according to Application Example 4,
The spark plug according to claim 1, wherein the cutout portion is formed as a slit in the terminal that allows communication between an inner peripheral surface facing the hole and an outer peripheral surface of the terminal.

  With such a configuration, when the conductive portion is formed, the base material of the conductive portion can be filled into the hole through the slit, and many conductive portions can be arranged in the hole. Therefore, the electrical conductivity between the center electrode (connection portion) and the terminal can be greatly improved.

[Application Example 6] In the spark plug according to Application Example 4 or Application Example 5,
The spark plug according to claim 1, wherein a ratio of a length of the cutout portion along the insertion direction to a length inserted into the hole of the connection portion is 50% or more.

  With such a configuration, the conductive portion can be arranged in a longer range along the insertion direction in the hole. Therefore, the electrical conductivity between the center electrode (connection portion) and the terminal can be greatly improved.

Application Example 7 In the spark plug according to any one of Application Examples 1 to 6,
The terminal has a first end surface in which the insertion port of the connection portion in the hole is formed, and a second end surface located on the opposite side in the insertion direction of the connection portion with respect to the first end surface. And
The spark plug is characterized in that the second end surface is circular.

  With such a configuration, the area of the second end face can be increased. Therefore, in the configuration in which the second end surface is used as a contact surface with the connector of the ignition cord, the area of the contact surface can be increased, and the contact resistance between the terminal and the connector of the ignition cord can be reduced. Can do.

Application Example 8 In the spark plug according to any one of Application Examples 1 to 7,
The terminal has a first end surface in which the insertion port of the connection portion in the hole is formed, and a second end surface located on the opposite side in the insertion direction of the connection portion with respect to the first end surface. And
The spark plug according to claim 1, wherein the hole is a through hole that allows the first end surface and the second end surface to communicate with each other.

  With such a configuration, when the spark plug is manufactured, the base material of the conductive part is disposed around the central electrode or the connection part. The air to be discharged can be discharged from the through hole, and the hole can be easily filled with the base material of the conductive portion. Therefore, since many electroconductive parts can be arrange | positioned in a hole, the electrical contact area of a center electrode (connection part) and a terminal can be enlarged.

Application Example 9 In the spark plug according to Application Example 3,
The terminal has an end surface in which an insertion port of the connection portion in the hole is formed.
The spark plug according to claim 1, wherein a ratio of a length of the conductive portion along the insertion direction to a length inserted in the hole of the connection portion is 50% or more.

  With such a configuration, many conductive portions can be arranged in the hole, so that the electrical contact area between the center electrode (connection portion) and the terminal can be increased.

Application Example 10 In the spark plug according to any one of Application Examples 1 to 9,
Comprising an insulator having a receiving hole into which at least a part of the terminal is inserted;
The spark plug according to claim 1, wherein the conductive portion is disposed between an outer peripheral surface of the terminal and the insulator in the accommodation hole.

  With such a configuration, the airtightness between the terminal and the insulator (the airtightness between the outer peripheral surface of the terminal and the inner peripheral surface of the accommodation hole) can be improved by the conductive portion.

Application Example 11 In the spark plug according to Application Example 10,
The spark plug is characterized in that an uneven portion is formed on at least one of an inner peripheral surface of the housing hole and an outer peripheral surface of the terminal inserted into the housing hole in the insulator.

  With such a configuration, the contact area with the conductive portion can be increased on at least one of the inner peripheral surface of the accommodation hole and the outer peripheral surface of the terminal. Therefore, the adhesion between at least one of the inner peripheral surface of the accommodation hole and the outer peripheral surface of the terminal and the conductive portion can be improved, and the airtightness between the terminal and the insulator can be greatly improved.

  In addition, this invention can be implement | achieved in various aspects, for example, can be implement | achieved with forms, such as a manufacturing method of a spark plug.

It is sectional drawing which shows the structure of one Embodiment of the igniter plug to which the ignition plug of this invention is applied. It is explanatory drawing which expands and shows a part of igniter plug shown in FIG. It is explanatory drawing which shows typically the formation procedure of a conductive seal part. It is explanatory drawing which shows the result of the electroconductivity evaluation test of the igniter plug of 1st Example. It is explanatory drawing which shows the result of the electroconductivity evaluation test of the igniter plug of 2nd Example. It is explanatory drawing which shows the result of the electroconductivity evaluation test of the igniter plug of 3rd Example. It is explanatory drawing which expands and shows the arrangement | positioning part of the terminal in the igniter plug of 4th Example. It is explanatory drawing which shows the result of the electroconductivity evaluation test of the igniter plug of 4th Example. It is explanatory drawing which expands and shows the arrangement | positioning part of the terminal in the igniter plug of 5th Example. It is explanatory drawing which shows the result of the electrical conductivity evaluation test of the igniter plug of 5th Example, and the igniter plug of a 1st, 2nd comparative example. It is sectional drawing which expands and shows the junction part of the terminal and connection line in the igniter plug of the modification 1. FIG. 10 is an enlarged cross-sectional view illustrating a joint portion between a terminal and a connection line in an igniter plug according to Modification 2; 12 is an explanatory diagram illustrating another example of Modification 2. FIG. It is explanatory drawing which expands and shows the arrangement | positioning part of the terminal in the igniter plug of the modification 3. It is explanatory drawing which expands and shows the arrangement | positioning part of the terminal in the igniter plug of the modification 4. It is explanatory drawing which expands and shows the arrangement | positioning part of the terminal in the igniter plug of the modification 5. FIG.

A. Embodiment:
FIG. 1 is a cross-sectional view showing a configuration of an embodiment of an igniter plug to which the ignition plug of the present invention is applied. FIG. 2 is an explanatory diagram showing an enlarged part of the igniter plug shown in FIG. In FIG. 2, the configuration of the region Ar in FIG. 1 is enlarged. The igniter plug 100 of the present embodiment is an ignition device used in, for example, an aircraft gas turbine engine, a diesel engine, a burner igniter, or the like, and is a so-called retractable surface type igniter plug.

  As shown in FIG. 1, the igniter plug 100 includes a metal shell 50, a first insulator 40, a terminal 20, a center electrode 10, a conductive seal portion 30, a second insulator 70, and a ground electrode 60. And an outer cylinder 80.

  The metal shell 50 is formed in a hollow cylindrical shape from a metal such as carbon steel, and constitutes a housing of the igniter plug 100.

  The 1st insulator 40 is a cylindrical member comprised with the ceramic sintered compact, and the through-hole 41 is formed along the axis line OL. In the through hole 41, the terminal 20, the center electrode 10, and the like are accommodated. The first insulator 40 includes a terminal accommodating portion 42, a seal accommodating portion 43, a first step portion 44, and a second step portion 45.

  The terminal accommodating portion 42 is disposed at the center portion in the longitudinal direction (the direction along the axis OL) in the first insulator 40. The terminal accommodating part 42 accommodates a part of the terminal 20 (cylindrical part 21 to be described later), a part of the center electrode 10 (a connecting line 11 to be described later), and a part of the conductive seal part 30. A female screw is formed on the inner peripheral surface of the terminal accommodating portion 42.

  The seal housing portion 43 is disposed adjacent to the terminal housing portion 42, and a part of the conductive seal portion 30, a connection wire 11 described later, and a part of the center electrode 10 (a thick wall portion 12 described later). And house.

  The first step portion 44 shown in FIG. 1 is disposed on the tip side of the seal housing portion 43 (the side of the igniter plug 100 where the ground electrode 60 is disposed among the ground electrode 60 and the second insulator 70). Yes. The first step portion 44 is a portion whose inner diameter is tapered along the longitudinal direction. The second step portion 45 is disposed adjacent to the terminal housing portion 42 on the side opposite to the seal housing portion 43. The second step portion 45 has an inner diameter that tapers along the longitudinal direction.

  The terminal 20 has conductivity, and electrically connects a connector of an ignition cord (not shown) and the center electrode 10. The terminal 20 can be configured using, for example, brass as a base material. The terminal 20 has a tubular portion 21 and a flange portion 22. The cylindrical portion 21 has a cylindrical shape extending along the axis OL and is accommodated in the terminal accommodating portion 42. The cylindrical portion 21 has a male screw formed on the outer peripheral surface, and the male screw and a female screw formed in the terminal accommodating portion 42 are screwed together. The flange portion 22 is located on the rear end side of the tubular portion 21 (the side of the igniter plug 100 where the second insulator 70 is disposed among the ground electrode 60 and the second insulator 70). , Is formed in a shape that can be engaged with a predetermined tool. The bowl-shaped portion 22 includes a contact surface S1 and a shoulder-shaped portion 25. The contact surface S1 contacts an unillustrated connector for an ignition cord in an engine or the like. The plan view shape of the contact surface S1 (the shape when viewed from the front end side or the rear end side along the axis OL) is a shape that engages with a predetermined tool. In the present embodiment, a regular hexagonal shape is adopted as the planar view shape of the contact surface S1, but it is not limited to a regular hexagonal shape, and other shapes can be adopted according to the shape of a predetermined tool. The shoulder 25 is tapered at the same angle as the second step 45 described above, and is in contact with the second step 45.

  As shown in FIG. 2, a connection line accommodation hole 23 is formed along the axis OL over a part of the cylindrical portion 21 and the flange portion 22. In the present embodiment, the connection line accommodation hole 23 does not reach the contact surface S <b> 1 and does not penetrate the terminal 20. The connection line accommodation hole 23 accommodates a later-described connection line 11 and a conductive seal portion 30.

  The center electrode 10 is a rod-like member having conductivity, and includes a thick portion 12 and a connection line 11 on the rear end side. The thick portion 12 is a portion that connects the connection line 11 and other portions in the center electrode 10, and has a larger outer diameter than the other portions of the center electrode 10. The thick portion 12 is tapered at the same angle as the first step portion 44 described above, and is in contact with the first step portion 44. The connection line 11 is a thin rod-like member extending along the axis OL and is connected to the thick portion 12. The center electrode 10 and the connection line 11 have conductivity, and can be configured using, for example, Kovar as a base material. The outer diameter of the connecting wire 11 is substantially the same as the inner diameter of the connecting wire housing hole 23 described above. However, as shown in FIG. 2, a slight gap p <b> 1 is formed between the outer peripheral surface of the connection line 11 and the inner peripheral surface of the connection line accommodation hole 23. The length in the radial direction of the gap p1 (the total length of the two parts separated across the connection line 11) can be 0.2 m or more. In other words, the difference between the inner peripheral diameter of the connection line accommodation hole 23 and the outer peripheral diameter of the connection line 11 (hereinafter referred to as “diameter difference”) can be 0.2 mm or more. As shown in FIG. 1, the distal end side of the center electrode 10 is accommodated in an axial hole (a through hole extending along the axis OL) of the second insulator 70.

  As shown in FIG. 2, the conductive seal portion 30 is disposed in the seal housing portion 43 and the terminal housing portion 42. Specifically, the conductive seal portion 30 is disposed in the seal housing portion 43 so as to fill other regions except the connection line 11 and the thick portion 12. In addition, the conductive seal portion 30 is an area on the seal accommodating portion 43 side in the terminal accommodating portion 42, and is disposed so as to fill other areas excluding the connecting wire 11 and the tubular portion 21. Specifically, the front end side of the gap between the portion of the outer peripheral surface of the tubular portion 21 where the blade-like portion 24 is not formed and the inner peripheral surface of the terminal accommodating portion 42, or the front end side of the aforementioned gap p1 The seal accommodating portion 43 is disposed so as to fill the gap. The conductive seal portion 30 has conductivity and high airtightness, and can be formed using, for example, conductive glass powder as a base material. As the conductive glass powder, for example, powder obtained by mixing copper powder and calcium borosilicate glass powder can be employed.

  In the present embodiment, the connecting line 11 has an axial line OL of the conductive seal portion 30 disposed (filled) in the gap p1 with respect to the length d2 along the axial line OL of the portion inserted into the connecting line accommodation hole 23. The ratio of the length d1 along (hereinafter referred to as “filling length d1”) can be, for example, 16.7% or more, and preferably 50% or more.

  FIG. 3 is an explanatory view schematically showing a procedure for forming the conductive seal portion. As shown in FIG. 3, the center electrode 10 is inserted into the through hole 41, and the through hole 41 is in contact with the thick portion 12 of the center electrode 10 and the first step portion 44 of the first insulator 40. The conductive glass powder 30a is filled. At this time, the conductive glass powder 30a is filled in the seal housing portion 43 and the tip side portion of the terminal housing portion. Next, when the terminal 20 is inserted into the through-hole 41, a part of the conductive glass powder 30 a that has already been filled is accommodated in the outer peripheral surface of the cylindrical part 21 and the part where the blade-like part 24 is not formed. It will enter the gap between the inner peripheral surface of the portion 42 and the gap p1 described above. Thereafter, the terminal 20 is pushed into the tip side using a predetermined tool, and then the entire first insulator 40 is heated (for example, heated to 900 ° C. to 1000 ° C.), so that the filled conductive glass powder 30a is The conductive seal portion 30 is formed.

  The second insulator 70 shown in FIG. 1 is a cylindrical member made of a ceramic sintered body, like the first insulator 40. A shaft hole is formed in the second insulator 70 along the axis OL, and the second insulator 70 accommodates the center electrode 10 in this shaft hole. A part of the rear end side of the second insulator 70 is inserted into the front end side of the through hole 41 described above.

  The ground electrode 60 shown in FIG. 1 is a substantially cylindrical member that houses the second insulator 70 therein, and is formed of a metal such as low carbon steel. The rear end of the ground electrode 60 is connected to the front end of the metal shell 50. When a high voltage is applied between the center electrode 10 and the ground electrode 60, a discharge occurs between the tip 65 of the ground electrode 60 and the tip 13 of the center electrode 10, and the tip of the ground electrode 60 is discharged. Sparks are emitted in the form of plasma from the formed opening.

  In the igniter plug 100 of the present embodiment having the above-described configuration, since the conductive seal portion 30 having conductivity is disposed so as to fill between the center electrode 10 (connection line 11) and the terminal 20, the center The conductivity between the electrode 10 and the terminal 20 can be improved. Further, even when the outer peripheral surface of the connecting wire 11 or the inner peripheral surface of the cylindrical portion 21 is rough, the connecting wire 11 (center electrode 10) and the cylindrical portion 21 (terminal 20) are connected by the conductive seal portion 30. It can be electrically connected.

  The connection line 11 described above corresponds to the connection portion in the claims. In addition, the conductive seal portion 30 is connected to the connection portion in the claims, the connection line receiving hole 23 is the hole in the claims, the contact surface S1 is the second end surface in the claims, and the terminal 20 is opposite to the contact surface S1. The end face corresponds to the first end face in the claims, and the through hole 41 (terminal accommodating portion 42) corresponds to the accommodating hole in the claims.

B. Example:
B1. First embodiment:
Based on the embodiment described above, ten igniter plugs 100 (samples) were manufactured, and the conductivity of each igniter plug 100 was evaluated. Specifically, the contact resistance of each sample was measured, and it was evaluated that the greater the resistance value, the lower the conductivity, and the smaller the resistance value, the higher the conductivity. In the igniter plug 100 according to the first embodiment, the above-described difference in diameter is 0.2 mm, and the filling length with respect to the length d2 along the axis OL of the portion of the connecting wire 11 housed in the connecting wire housing hole 23. The ratio of d1 was 16.7%. As a comparative example, ten igniter plugs without the conductive seal portion 30 were manufactured, and the conductivity of these was also evaluated.

  FIG. 4 is an explanatory diagram showing the results of the conductivity evaluation test of the igniter plug of the first embodiment. In FIG. 4, the upper part shows the test result of the igniter plug 100 of the embodiment, and the lower part shows the test result of the igniter plug of the comparative example. In FIG. 4, “maximum” indicates the contact resistance of the sample having the largest resistance value among the ten samples. In FIG. 4, “minimum” indicates the contact resistance of the sample having the smallest resistance value among the ten samples. In FIG. 4, “average” indicates an average contact resistance value of 10 samples. In FIG. 4, “Good” indicates the number of samples having a resistance value equal to or less than a predetermined threshold among the ten samples. In this embodiment, 40 milliohms is adopted as the predetermined threshold value.

  As shown in FIG. 4, the resistance value of the first example was less than or equal to the resistance value of the comparative example for any of “maximum”, “minimum”, and “average”. The number of samples that were “good” in the first example was larger than the number of samples that were “good” in the comparative example. From this evaluation result, it became clear that the conductivity was improved by providing the conductive seal portion 30.

B2. Second embodiment:
Based on the above-described embodiment, seven igniter plugs 100 having different filling lengths d1 were manufactured, and the conductivity of each igniter plug 100 was evaluated. Specifically, the filling length d1 is 0 mm (sample 1), 1 mm (sample 2), 2 mm (sample 3), 3 mm (sample 4), 4 mm (sample 5), 5 mm (sample 6), 6 mm ( Sample 7) was manufactured and evaluated. In any sample 1-7, the length (length d2 in FIG. 2) of the part accommodated in the connection line accommodation hole 23 among the connection lines 11 along the axis OL was 6 mm. Accordingly, in each of the samples 1 to 7, the ratio of the filling length d1 to the length d2 along the axis OL of the portion of the connection line 11 accommodated in the connection line accommodation hole 23 is 0% (sample 1). ), 16.7% (Sample 2), 33.3% (Sample 3), 50% (Sample 4), 66.7% (Sample 5), 83.3% (Sample 6), 100% (Sample 7) ) In addition, the above-mentioned diameter difference was 0.2 mm. The conductivity evaluation method in the second example was the same as in the first example. In the second example, the influence of the filling length d1 on the conductivity was evaluated.

  FIG. 5 is an explanatory diagram showing the results of the conductivity evaluation test of the igniter plug of the second embodiment. In FIG. 5, “Sample No.” and “filling length” indicate the sample number and the filling length d1 of each sample, respectively. In FIG. 5, “ratio” means the ratio of the filling length d <b> 1 to the length d <b> 2 along the axis OL of the portion of the connection line 11 accommodated in the connection line accommodation hole 23. In FIG. 5, “Evaluation” indicates the evaluation result of conductivity. Specifically, in FIG. 5, “◎” indicates that the evaluation was the highest, and that the contact resistance was 20 milliohms or less. In FIG. 5, “◯” indicates the second highest evaluation, which means that the contact resistance is larger than 20 milliohms and smaller than 40 milliohms. In FIG. 5, “×” indicates that the evaluation was the lowest, and the contact resistance was 40 milliohms or more.

  As shown in FIG. 5, the other samples 2 to 7 other than the sample 1 were relatively high in evaluation because the contact resistance was smaller than 40 milliohms. In particular, Samples 4 to 7 had the highest contact resistance of 20 milliohms or less. From this evaluation result, the ratio of the filling length d1 to the length d2 along the axis OL of the portion accommodated in the connection line accommodation hole 23 is preferably 16.7% (16.7%) or more, It became clear that it was more preferable to be 50% or more. When the ratio of the filling length d1 to the length d2 along the axis OL of the portion accommodated in the connection line accommodation hole 23 in the connection line 11 is high, the connection line 11 (center electrode 10) and the cylindrical portion 21 ( It is presumed that the electrical contact area with the terminal 20) has increased and the contact resistance has decreased.

B3. Third embodiment:
Based on the above-described embodiment, five igniter plugs 100 having different diameter differences were manufactured, and the conductivity of each igniter plug 100 was evaluated. Specifically, the diameter differences are 0 mm (sample 8), 0.1 mm (sample 9), 0.2 mm (sample 10), 0.5 mm (sample 11), and 1.0 mm (sample 12), respectively. And evaluated. The ratio of the filling length d1 to the length d2 along the axis OL of the portion accommodated in the connection line accommodation hole 23 in the connection line 11 was 16.7% for all the samples 8 to 12. . The conductivity evaluation method in the third example was the same as in the first example. In the third example, the influence of the diameter difference on the conductivity was evaluated.

  FIG. 6 is an explanatory view showing the results of the conductivity evaluation test of the igniter plug of the third embodiment. In FIG. 6, “sample No.” and “diameter difference” indicate the sample number and diameter difference of each sample, respectively. In FIG. 6, “Evaluation” indicates the evaluation result of conductivity. Specifically, in FIG. 6, “◯” indicates that the evaluation is high, and that the contact resistance is a value smaller than 40 milliohms. In FIG. 6, “x” indicates that the evaluation was low and that the contact resistance was 40 milliohms or more.

  As shown in FIG. 6, the other samples 10 to 12 except for the samples 8 and 9 were highly evaluated with contact resistances lower than 40 milliohms. From this evaluation result, it became clear that the difference in diameter (the difference between the inner peripheral diameter of the connecting wire accommodation hole 23 and the outer peripheral diameter of the connecting wire 11) is preferably 0.2 mm or more. When the diameter difference is large, the gap p1 is increased, and the amount of the conductive seal portion 30 filled in the gap p1 is increased. Therefore, it is presumed that the electrical contact area between the connecting wire 11 (center electrode 10) and the cylindrical portion 21 (terminal 20) is increased, and the contact resistance is reduced. However, if the diameter difference exceeds 1.0 mm, the positional relationship between the terminal 20 and the connecting wire 11 may be greatly shifted during manufacture.

  In addition, as in the third embodiment, by setting the diameter difference to be 0.2 mm or more, the conductive seal portion 30 is provided on the entire circumference of the portion where the connecting wire 11 and the cylindrical portion 21 overlap in the radial direction. Since it can arrange | position, in all the perimeters of this site | part, the connection wire 11 and the cylindrical part 21 can be made to contact electrically, and electroconductivity can be improved significantly.

B4. Fourth embodiment:
Based on the above-described embodiment, 10 igniter plugs (samples) were manufactured, and the conductivity of each igniter plug was evaluated. However, the igniter plug of the fourth embodiment is different from the igniter plug 100 of the first embodiment in that the connection line accommodation hole penetrates the terminal 20.

  FIG. 7 is an explanatory view showing, in an enlarged manner, a terminal arrangement portion in the igniter plug of the fourth embodiment. In FIG. 7, in the igniter plug of the fourth embodiment, the same region Ar as the region Ar shown in FIG. 2 is enlarged. As shown in FIG. 7, in the igniter plug of the fourth embodiment, the connection line accommodation hole 23a passes through the terminal 20 in the direction along the axis OL. Therefore, as shown in FIG. 7, an opening 26 is formed in the contact surface S1. In the fourth embodiment, the inner diameter of the connection line accommodation hole 23a is uniform on the rear end side.

  The conductivity evaluation method in the fourth example was the same as that in the first example. In the fourth example, the diameter difference was 0.5 mm. Further, the ratio of the filling length d1 to the length d2 along the axis OL of the portion of the connection line 11 accommodated in the connection line accommodation hole 23 was 100% in any sample. In 4th Example, the influence with respect to the electroconductivity of the presence or absence of the penetration in the connecting wire accommodation hole 23a was evaluated. As a comparative example, 10 igniter plugs 100 were manufactured and evaluated under the same conditions as in the first example. In this comparative example, the connection line accommodation hole 23 does not penetrate the terminal 20.

  FIG. 8 is an explanatory view showing the results of the conductivity evaluation test of the igniter plug of the fourth embodiment. In FIG. 8, the upper part shows the test result of the igniter plug of the example, and the lower part shows the test result of the igniter plug of the comparative example. The meanings of “maximum”, “minimum”, “average”, and “good” in FIG. 8 are the same as those in FIG.

  As shown in FIG. 8, the resistance value of the fourth example was lower than the resistance value of the comparative example for any of “maximum”, “minimum”, and “average”. Further, the number of “good” samples in the fourth example was larger than the number of “good” samples in the comparative example. According to this test result, it was revealed that the conductivity was improved by forming the connection line accommodation hole as a through-hole penetrating the terminal 20 like the connection line accommodation hole 23a of this example. This is presumed to be due to the following reason. In the fourth embodiment, when the conductive seal portion 30 shown in FIG. 3 is formed, when the terminal 20 is inserted into the through hole 41 and the connection line 11 is inserted into the connection line accommodation hole 23a, the connection line accommodation hole 23a. The air existing inside is discharged from the opening 26, and the conductive glass powder 30a enters into the connection wire accommodation hole 23a. Therefore, when the conductive seal portion 30 is formed, the electrical contact area between the connecting wire 11 and the terminal 20 is increased, and it is estimated that the conductivity is improved. On the other hand, in the first embodiment, when the connection wire 11 is inserted into the connection line accommodation hole 23a when the conductive seal portion 30 is formed, the air present in the connection line accommodation hole 23a becomes a resistance. Thus, the conductive glass powder 30a does not enter the connection wire accommodation hole 23a. Therefore, when the conductive seal portion 30 is formed, the electrical contact area between the connecting wire 11 and the terminal 20 is smaller than that in the fourth embodiment, so that it is estimated that the conductivity is reduced. The

B5. Example 5:
Based on the above-described embodiment, one igniter plug was manufactured, and the igniter plug 100 was evaluated for conductivity and high temperature airtightness. However, the igniter plug of this embodiment is different from the igniter plug 100 of the first embodiment in that there are two types of seal members that are accommodated (filled) in the seal accommodating portion 43.

FIG. 9 is an explanatory view showing, in an enlarged manner, a terminal arrangement portion in the igniter plug of the fifth embodiment. In FIG. 9, in the igniter plug of the fifth embodiment, the same region Ar as the region Ar shown in FIG. 2 is enlarged. As shown in FIG. 9, in the igniter plug of the fifth embodiment, two types of seal members are stacked and arranged in the seal housing portion 43. Specifically, the glass seal portion 31 is disposed on the front end side, and the conductive seal portion 30 is disposed on the rear end side in layers. The glass seal part 31 is formed of a glass base material having high high temperature airtightness. As such a substrate, for example, a glass substrate having a softening point (temperature at which the surface starts to melt) of 600 ° C. or higher and an expansion coefficient of 5.0 × 10 ⁻⁶ (/ ° C.) in a temperature range from room temperature to 380 ° C. Material can be adopted. The two-layer structure as shown in FIG. 9 is filled with the powder that becomes the base material of the glass seal portion 31 before the conductive glass powder 30a is filled in the formation procedure of the conductive seal portion 30 shown in FIG. Subsequently, it can implement | achieve by filling with the conductive glass powder 30a.

  In addition to the igniter plug of the fifth embodiment described above, as a comparative example, an igniter plug (first comparative example) in which only the conductive seal portion 30 is omitted from the igniter plug of the fifth embodiment, and an igniter of the fifth embodiment. One igniter plug (second comparative example) in which the conductive seal portion 30 and the glass seal portion 31 were omitted from the plug was manufactured. Then, together with the igniter plug of the fifth example, the igniter plugs of the first and second comparative examples were evaluated for conductivity and high temperature airtightness.

  The conductivity evaluation method in the fifth example was the same as that in the first example. The evaluation of the high temperature tightness in the fifth example was performed by measuring the tightness using an air tightness tester. Specifically, under a predetermined temperature and pressure (740 ° C. and 3.4 MPa) environment, air is sent from the front end side of the through hole 41 to measure the amount of air leakage from the rear end side of the through hole 41, The smaller the leakage amount, the higher the high-temperature airtightness, and the higher the leakage amount, the lower the high-temperature airtightness. In the igniter plug of the fifth embodiment, the diameter difference is 0.5 mm, and the filling length d1 with respect to the length d2 along the axis OL of the portion of the connection line 11 accommodated in the connection line accommodation hole 23 is shown. The ratio of was 100%.

  FIG. 10 is an explanatory view showing the results of the conductivity evaluation test and the high temperature airtightness test of the igniter plug of the fifth example and the igniter plugs of the first and second comparative examples. In FIG. 10, “conductivity” indicates the evaluation result of conductivity, “high temperature airtightness” indicates the evaluation result of high temperature airtightness, and “total” indicates the comprehensive evaluation of conductivity and high temperature airtightness. Results are shown. Specifically, in the evaluation result of “conductivity”, “◯” indicates that the evaluation was high, and that the contact resistance was a value smaller than 40 milliohms. Moreover, in the evaluation result of “conductivity”, “x” indicates that the evaluation was low, and that the contact resistance was 40 milliohms or more. In the evaluation result of “high temperature airtightness”, “◯” indicates that the evaluation was high, and the air leakage amount was a value lower than 5 cc per minute. Moreover, in the evaluation result of “high temperature airtightness”, “x” indicates that the evaluation was low, and the amount of air leakage was 5 cc or more per minute. In the evaluation result of “Comprehensive”, “○” indicates the highest evaluation, “△” indicates the second highest evaluation, and “×” indicates the lowest evaluation. Show. The evaluation result of “total” was set to be higher as the number of high evaluations in the evaluation result of conductivity and the evaluation result of high temperature airtightness was higher.

  As shown in FIG. 10, regarding the conductivity, the igniter plug of the fifth example was highly evaluated and also highly evaluated compared to the igniter plugs of the first and second comparative examples. This is presumed to be the same reason as the igniter plug 100 of the first embodiment. As for the high temperature airtightness, the igniter plug of the fifth example was highly evaluated as in the first comparative example. This is because the contact portion between the center electrode 10 (thick portion 12) and the first insulator 40 (first step portion 44), whose airtightness is easily broken, is sealed by the glass seal portion 31 having high temperature airtightness. It is estimated that this is because In the overall evaluation, the igniter plug of the fifth example had the highest evaluation. This is because, in the seal housing portion 43, the conductive seal portion 30 having conductivity is disposed on the rear end side where high electrical conductivity is required, and the high temperature air-tightness is provided on the front end side where high air tightness is required. This is presumed to be the result of arranging the glass seal portion 31.

C. Variation:
The present invention is not limited to the above-described examples and embodiments, and can be carried out in various modes without departing from the gist thereof. For example, the following modifications are possible.

C1. Modification 1:
FIG. 11 is an enlarged cross-sectional view illustrating a joint portion between a terminal and a connection line in the igniter plug according to the first modification. FIG. 11 shows a cross section perpendicular to the axis OL of the igniter plug of Modification 1 as viewed from the front end side to the rear end side of the igniter plug. FIG. 11A shows a cross section of the igniter plug of the first example in the first modification. FIG. 11B shows a cross section of the igniter plug of the second example in the first modification.

  As shown in FIG. 11A, in the igniter plug of the first example in the first modification, there is no difference in diameter between the point where the connection line 11a has the notch part f1 and the other part excluding the notch part f1. The point is the same as the igniter plug 100 of the above embodiment and the first example except for the above point. The connection line 11a of the first example in Modification 1 includes two notches f1 on the outer peripheral surface. These two notches f1 are extended from the seal housing part 43 to the terminal housing part 42 along the axis OL in the connection line 11a. Further, these two cutouts f1 are arranged at axial positions with the axis OL as the central axis. As shown in FIG. 11A, the conductive seal portion 30 is disposed in the gap between each notch portion f <b> 1 and the inner peripheral surface of the tubular portion 21.

  When there is a gap between the outer peripheral surface of the connecting wire 11a and the inner peripheral surface of the tubular portion 21 due to deformation or the like accompanying use in a high temperature environment, or the inner surface of the connecting wire 11a or the inner portion of the tubular portion 21 Even when the contact resistance is high due to the roughness of the peripheral surface, the electrical connection between the connecting wire 11a and the cylindrical portion 21 is established through the conductive seal portion 30 filled in the notch f1. Can be secured. Therefore, according to the 1st example in the modification 1, the electrical conductivity between the center electrode 10 and the terminal 20 can be improved.

  As shown in FIG. 11 (b), the igniter plug of the second example in Modification 1 has a difference in diameter between the point where the cylindrical portion 21a has the notch portion f2 and the other portions excluding the notch portion f2. The igniter plug 100 is the same as the igniter plug 100 of the above-described embodiment and the first example except for the above. The cylindrical portion 21a of the first example in Modification 1 includes two notches f2 on the inner peripheral surface. These two notches f2 extend along the axis OL on the inner peripheral surface of the cylindrical portion 21a. Further, these two notches f2 are arranged at axial positions with the axis line OL as the central axis. As illustrated in FIG. 11B, the conductive seal portion 30 is disposed in the gap between each notch portion f <b> 2 and the outer peripheral surface of the connection line 11.

  When there is a gap between the outer peripheral surface of the connecting wire 11 and the inner peripheral surface of the cylindrical portion 21a due to deformation or the like accompanying use in a high temperature environment, or the inner surface of the connecting wire 11 or the inner portion of the cylindrical portion 21a Even when the contact resistance is high due to the roughness of the peripheral surface, the electrical connection between the connecting wire 11 and the cylindrical portion 21a is made through the conductive seal portion 30 filled in the notch f2. Can be secured. Therefore, according to the 2nd example in the modification 1, the electrical conductivity between the center electrode 10 and the terminal 20 can be improved.

  As can be understood from the first and second examples of the first modified example and the third embodiment, the cylindrical portion (21, 21a) and the connecting line (11a, 11) are located in the radial direction. In at least a part of the entire circumference, the outer diameter of the connection line is smaller than the inner diameter of the cylindrical portion, and the conductive seal portion 30 is formed by a difference between the outer diameter of the connection line and the inner diameter of the cylindrical portion. The spark plug of the present invention can be applied to any igniter plug formed in the above. Note that the two notches f1 of the first example in the first modification are arranged at the position of the axis object with the axis OL as the central axis, but instead of this, any arbitrary part that is not an axis object It can also be placed in position. The same applies to the two cutout portions f2 of the second example in the first modification. Further, in the first and second examples in the first modification, the number of the notch portions f1 and the notch portions f2 is two each, but may be an arbitrary number.

C2. Modification 2:
FIG. 12 is an enlarged cross-sectional view showing a joint portion between a terminal and a connection line in an igniter plug according to Modification 2. FIG. 12 shows a cross section perpendicular to the axis OL of the igniter plug of Modification 12 as viewed from the front end side to the rear end side of the igniter plug.

  As shown in FIG. 12, the igniter plug according to the modified example 2 is different from the above embodiment and the first embodiment except that the cylindrical portion 21b has a slit SL and there is no diameter difference in other portions except the slit SL. This is the same as the igniter plug 100 of one embodiment. The cylindrical part 21b in the modification 2 is provided with two slits SL. In the second example of the first modification described above, the cylindrical portion 21 is provided with the notch f2 on the inner peripheral surface, but the notch f2 does not penetrate the cylindrical portion 21 in the radial direction. It was. On the other hand, the igniter plug of Modification 12 is provided with a notch that penetrates the cylindrical portion 21b in the radial direction, that is, a slit SL. These two slits SL are arranged at positions that are axially targeted with respect to the axis OL. As shown in FIG. 12, the region surrounded by the slit SL and the outer peripheral surface of the connection line 11 and the inner peripheral surface of the first insulator 40 (terminal accommodating portion 42) not shown in FIG. A seal portion 30 is disposed.

  Even in such a configuration, the same effects as those of the igniter plug of the first modification described above can be obtained. Further, since the slit SL penetrates the cylindrical portion 21b in the radial direction, when the connecting wire 11 is inserted into the connecting wire accommodating hole 23a when the conductive seal portion 30 shown in FIG. The conductive glass powder 30a enters the connecting wire accommodation hole 23 from the outer peripheral surface side of the shaped portion 21b. Therefore, a large amount of the conductive glass powder 30 a can be filled in the connection line accommodation hole 23 to increase the electrical contact area between the connection line 11 and the terminal 20.

  In the example shown in FIG. 12, the cross-sectional area of the two slits SL (that is, the cross-sectional area of the conductive seal portion 30) with respect to the cross-sectional area of the cylindrical portion 21b can be about 10%. Moreover, although two SL in the modification 2 was arrange | positioned in the position of an axis object mutually, it can replace with this and can also be arrange | positioned in the arbitrary positions which do not become an axis object.

  FIG. 13 is an explanatory diagram illustrating another example of the second modification. FIGS. 13A, 13B, 13C, and 13D are all cross-sectional views similar to FIG. In the example of FIG. 13A, the number of slits SL formed in the cylindrical portion 21c is four. In the example of FIG. 13B, the number of slits SL formed in the cylindrical portion 21d is eight. As can be understood from these examples, the number of slits SL formed in the cylindrical portion can be an arbitrary number. In addition, since the electrical contact area of the connecting wire 11 and the cylindrical part increases as the number of slits SL increases, the conductivity can be improved.

  In the example of FIG. 13C, the number of slits formed in the cylindrical portion 21e is eight, which is the same as in FIG. 13B, but in FIG. 13C, the slit width is not uniform. Absent. Specifically, in the example of FIG. 13C, two types of slits, a first slit SL1 having a small width and a second slit SL2 having a large width, are provided in the cylindrical portion 21e. The aforementioned “width of the slit” means the length in the direction perpendicular to the radial direction in each slit. In the example of FIG. 13C, the width of the first slit SL1 and the width of the second slit SL2 are both shorter than the length of the outer diameter of the connection line 11.

  In the example of FIG. 13D, four slits SL3 are formed in the cylindrical portion 21f. Since the four slits SL3 are connected to each other at a portion close to the connection line 11, they can be regarded as one cross-shaped slit. The width rs of the four slits SL3 shown in FIG. 13 (d) is longer than the length r1 of the outer diameter of the connection line 11. Even in such a configuration, the same effects as in FIGS. 12 and 13A to 13C can be obtained. However, as shown in FIG. 13D, when the width of the slit SL3 is larger than the outer diameter of the connection line 11, the portion other than the slit SL3 is reduced in the cylindrical portion 21f, so that the overload resistance performance is reduced. It will be. Therefore, when the conductive seal portion 30 shown in FIG. 3 is formed, it is impossible to give an appropriate pressing weight when the terminal 20 is inserted into the through hole 41. Therefore, the width of the slit provided in the cylindrical portion is preferably smaller than the outer diameter of the connection line 11.

  In addition, it is preferable that the ratio of the length of the slit of the direction along the axis line OL with respect to the length inserted in the connection line accommodation hole 23 of the connection line 11 is 50% or more. With such a configuration, the conductive seal portion 30 can be disposed in a long range along the axis OL in the connection line accommodation hole 23, and the conductivity between the connection line 11 and the terminal 20 can be greatly improved. it can.

C3. Modification 3:
FIG. 14 is an explanatory view showing, in an enlarged manner, a terminal arrangement portion in the igniter plug of the third modification. In FIG. 14, in the igniter plug of Modification 3, the same region Ar as the region Ar shown in FIG. 2 is enlarged. The igniter plug of Modification 3 is different from the igniter plug of the fourth embodiment in that the inner diameter of the connection line receiving hole is not uniform on the rear end side, and the other configuration is the same as that of the igniter plug of the fourth embodiment. is there.

  As shown in FIG. 14, the connection line accommodation hole 23z of the igniter plug of Modification 3 has a front end side portion 23x and a rear end side portion 23y. The distal end side portion 23x has substantially the same shape as the connection line accommodation hole 23 in the first embodiment, and has an inner diameter that is the same as the inner diameter of the connection line accommodation hole 23 in the first embodiment. The rear end side portion 23y has a smaller inner diameter than the front end side portion 23x. Therefore, the opening 26a formed in the contact surface S1 of the bowl-shaped portion 22 is smaller than the opening 26 of the fourth embodiment shown in FIG.

  The igniter plug of Modification 3 having such a configuration has the same effect as the igniter plug of the fourth embodiment. In addition, by making the rear end side (rear end side portion 23y) of the connection line accommodating hole 23z smaller than the front end side (front end side portion 23x), the opening 26a in the contact surface S1 is the fourth embodiment. It can be made smaller than Therefore, in the contact surface S1, the contact area with the connector (not shown) can be increased as compared with the fourth embodiment, and the contact resistance can be reduced.

C4. Modification 4:
FIG. 15 is an explanatory view showing, in an enlarged manner, a terminal arrangement portion in the igniter plug of Modification 4. In FIG. 15, in the igniter plug of Modification 4, the same region Ar as the region Ar shown in FIG. The igniter plug of Modification 4 is different from the igniter plug 100 of the first embodiment in that an internal thread is not formed on the inner peripheral surface of the terminal accommodating portion 42a, and the other configuration is the igniter plug of the first embodiment. The same as 100.

  As shown in FIG. 15, in the igniter plug of the modification 4, the male screw of the cylindrical part 21 is not screwed. Therefore, when the conductive seal part 30 shown in FIG. 3 is formed, the cylindrical part 21g is connected to the terminal accommodating part 42a. When inserted into the conductive glass powder 30a, the conductive glass powder 30a can easily enter between the male screw of the tubular portion 21 and the inner peripheral surface of the terminal accommodating portion 42a. As a result, in the finished product of the igniter plug, the conductive seal portion 30 can be disposed between the male screw of the tubular portion 21 and the inner peripheral surface of the terminal accommodating portion 42a. Therefore, the adhesiveness of the conductive seal portion 30 to the first insulator 40 can be improved, and the high temperature airtightness of the igniter plug can be improved. In Modification 4, the portion formed on the outer peripheral surface of the cylindrical portion 21 is not limited to the male screw, and a portion having an arbitrary uneven shape (corresponding to the uneven portion in the claims) can be employed.

C5. Modification 5:
FIG. 16 is an explanatory view showing, in an enlarged manner, a terminal arrangement portion in the igniter plug of Modification 5. In FIG. 16, in the igniter plug of Modification 5, the same region Ar as the region Ar shown in FIG. 2 is enlarged. The igniter plug of Modification 5 is different from the igniter plug 100 of the first embodiment in that the external thread is not formed on the outer peripheral surface of the cylindrical portion 21g, and the other configuration is the igniter plug 100 of the first embodiment. Is the same.

  As shown in FIG. 16, in the igniter plug of Modification 5, the female screw of the terminal accommodating portion 42 is not screwed. Therefore, when forming the conductive seal portion 30 shown in FIG. When inserted into the conductive glass powder 30a, the conductive glass powder 30a easily enters between the outer peripheral surface of the cylindrical portion 21g and the female screw of the terminal accommodating portion 42. Therefore, it is possible to obtain the same effect as that of the fourth modification described above. In Modification 5, the portion formed on the inner peripheral surface of the terminal accommodating portion 42 is not limited to the female screw, and a portion having an arbitrary uneven shape (corresponding to the uneven portion in the claims) can be employed. . As can be understood from the fourth and fifth modifications, a portion having an uneven shape is formed on at least one of the outer peripheral surface of the cylindrical portion (21g, 21) or the inner peripheral surface of the terminal accommodating portion (42, 42b). The igniter plug of the present invention can be applied to the spark plug thus formed.

C6. Modification 6:
In the above-described embodiment, each example, and each modification, the planar view shape of the contact surface S1 in the bowl-shaped portion 22 is a regular hexagon, but can be a circle instead of a regular hexagon. For example, when a circle having the longest diameter among the distances between any two vertices of the regular hexagon in the above-described embodiment or the like is adopted as the planar view shape of the contact surface S1, the contact area is a regular hexagon. Larger than the example. Specifically, the area of the contact surface S1 in the case of a hexagon having the longest distance of 9.24 mm among the distances between the two apexes is 55.35 square millimeters, whereas the diameter is 9.24 mm. The area of the contact surface S1 in the case of a circle is 67.05 square millimeters.

C7. Modification 7:
In the above-described embodiment, each example, and each modification, the present invention is applied to the igniter plug. However, the present invention is not limited to the igniter plug, and a center electrode (connection line) such as a spark plug is inserted into the terminal. The spark plug of the present invention can be applied to any spark plug having the above configuration.

C8. Modification 8:
In the embodiment, each example, and each modification described above, the center electrode 10 includes the connection lines 11 and 11a. However, the connection lines 11 and 11a may be omitted. Also in this case, the spark plug of the present invention can be applied to any spark plug having a configuration in which the rear end side of the center electrode 10 is inserted into the terminal 20 (cylindrical portion).

C9. Modification 9:
In the modified examples 4 and 5, a screw thread (part having an uneven shape) is provided on at least one of the outer peripheral surface of the cylindrical portion (21g, 21) or the inner peripheral surface of the terminal accommodating portion (42, 42b). However, the connection line 11 may be provided with a portion having an uneven shape such as a screw thread. With such a configuration, the contact area between the connection line 11 and the conductive seal portion 30 can be increased, and the electrical contact area between the connection line 11 and the tubular portion 21 can be increased.

C10. Modification 10:
In the embodiment, each example, and each modification described above, the base material of the conductive seal portion 30 is a conductive glass powder, but the present invention is not limited to this. For example, a metal nanoparticle paste containing particles such as gold, silver, copper, and palladium can be used as the base material of the conductive seal portion 30. Further, for example, thermal grease (organic paste mixed with metal filler (particles of silver, copper, alumina, etc.)) can be used. That is, in general, any material having conductivity can be employed as the base material of the conductive seal portion 30 of the present invention.

DESCRIPTION OF SYMBOLS 10 ... Center electrode 11, 11a ... Connection line 12 ... Thick part 13 ... Tip part 20 ... Terminal 21,21a-21g ... Cylindrical part 22 ... Gutter-like part 23, 23a, 23z ... Connection line accommodation hole 23x ... Tip side Part 23y ... Rear end side part 24 ... Blade-like part 25 ... Shoulder-like part 26, 26a ... Opening 30 ... Conductive seal part 30a ... Conductive glass powder 31 ... Glass seal part 40 ... First insulator 41 ... Through-hole 42 , 42a ... terminal accommodating portion 43 ... seal accommodating portion 44 ... first step portion 45 ... second step portion 50 ... metal shell 60 ... ground electrode 65 ... tip portion 70 ... second insulator 80 ... outer cylinder 100 ... igniter plug S1 ... contact surface p1 ... gap f1, f2 ... notch OL ... axis SL, SL3 ... slit SL1 ... first slit SL2 ... second slit Ar ... region rs ... width

Claims (9)

A spark plug,
A central electrode having a connection at one end;
A terminal having a hole, and wherein the connection portion is inserted in the hole;
With
The connection part and the terminal are electrically connected to each other through a conductive part having conductivity,
In at least a part of the entire circumference of the portion where the terminal and the connection portion overlap in the radial direction, the diameter of the connection portion is smaller than the diameter of the hole,
The conductive portion is disposed in a gap formed by a difference between the diameter of the connection portion and the diameter of the hole,
The terminal has a cutout portion formed in a radial direction in a part of the inner peripheral surface of the hole,
The spark plug is characterized in that the gap is formed between the cutout portion and an outer peripheral surface of the connection portion. A spark plug,
A central electrode having a connection at one end;
A terminal having a hole, and wherein the connection portion is inserted in the hole;
With
The connection part and the terminal are electrically connected to each other through a conductive part having conductivity,
The terminal has a first end surface in which the insertion port of the connection portion in the hole is formed, and a second end surface located on the opposite side in the insertion direction of the connection portion with respect to the first end surface. And
The spark plug according to claim 1, wherein the hole is a through hole that allows the first end surface and the second end surface to communicate with each other. The spark plug according to claim 2 ,
The conductive portion is disposed in a gap formed by a difference between the diameter of the connection portion and the diameter of the hole,
In all of the entire circumference, the diameter of the connecting portion is smaller than the diameter of the hole,
The spark plug is characterized in that the air gap is formed between the connection portion and the hole over the entire circumference. The spark plug according to claim 1, wherein
The spark plug according to claim 1, wherein the cutout portion is formed as a slit in the terminal that allows communication between an inner peripheral surface facing the hole and an outer peripheral surface of the terminal. The spark plug according to claim 1 or 4 ,
The ratio of the length of the cutout portion along the insertion direction of the connection portion to the hole with respect to the length inserted into the hole of the connection portion is 50% or more. plug. The spark plug according to any one of claims 1 to 5,
The terminal has a first end surface in which the insertion port of the connection portion is formed in the hole, and a second end located on the opposite side in the insertion direction of the connection portion into the hole with respect to the first end surface. An end face,
The spark plug is characterized in that the second end surface is circular. The spark plug according to any one of claims 1 to 6,
The terminal has an end surface in which an insertion port of the connection portion in the hole is formed.
A ratio of the length of the conductive portion along the insertion direction of the connecting portion to the hole with respect to the length inserted into the hole of the connecting portion is 50% or more. . The spark plug according to any one of claims 1 to 7,
Comprising an insulator having a receiving hole into which at least a part of the terminal is inserted;
The spark plug according to claim 1, wherein the conductive portion is disposed between an outer peripheral surface of the terminal and the insulator in the accommodation hole. The spark plug according to claim 8,
The spark plug is characterized in that an uneven portion is formed on at least one of an inner peripheral surface of the housing hole and an outer peripheral surface of the terminal inserted into the housing hole in the insulator.

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