JP2002246147A - Spark plug with built-in pressure sensor, and method for mounting plug - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spark plug with a built-in pressure sensor, capable of easily positioning an extending position of a lead wire, drawn out from a pressure sensor in a peripheral direction in a predetermined position (direction), such as a knocking detecting device, and preventing occurrence of damages and breaking of the lead wire. SOLUTION: The spark plug includes a rotating lead wire support part 43 for supporting the lead wire 23 by a lead wire support part 41d arranged rotatably about an axis on a rear side of a main metal fitting 11 in the axial direction, when a side where a spark discharge gap g is positioned is a front side in an axial direction of the spark plug 1, formed in a predetermined position in a circumferential direction, and integrally rotating with the lead wire 23. A deflection part 23a is formed on the lead wire 23 for absorbing changes in the path length between the lead wire support part 41d and a lead wire coupling terminal (a sensor case) 21 on a side of a pressure sensor 20, which occurs as the rotating lead wire support part 43 rotates with the lead wire 23.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spark plug with a built-in pressure sensor for detecting a pressure in an engine room of an internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, by measuring the pressure (in-cylinder pressure) of a combustion chamber of an internal combustion engine, for example, knocking detection,
It detects the peak position of the combustion pressure, detects misfire, and the like, and is useful for controlling the operation of the internal combustion engine. In some cases, a pressure sensor provided with a piezoelectric element such as an annular piezoelectric ceramic is used for measuring the in-cylinder pressure. Such a pressure sensor is disposed on a metal shell of the spark plug, and is mounted by tightening a screw portion formed on the metal shell to a screw portion of the cylinder head. The spark plug is pushed up by the combustion pressure, and the tightening load on the cylinder head of the spark plug fluctuates. The electrical output generated by the piezoelectric element in response to the fluctuation of the load is taken out to the outside via a lead wire. Is measured.

As an example of a spark plug with a pressure sensor as described above, there is a type with a built-in pressure sensor as shown in FIG. 1 of JP-A-6-290853. In this type, a pressure sensor in which a piezoelectric element, an electrode plate, and the like are housed in a sensor case is integrally attached to a mounting seat of a metal shell, and a screw portion (male screw) at a tip portion of the metal shell is screwed into a screw portion (female) of a cylinder head. Screw). On the other hand, a pressure sensor alone type as shown in FIG. 8 of the above publication is also known. In this type, a piezoelectric element, an electrode plate, and the like are housed in a sensor case to form an integral pressure sensor, and a pressure sensor is disposed between a mounting seat (gasket) of a metal shell and a cylinder head to form a metal shell. Is mounted on the cylinder head by tightening it.

[0004]

In each case, in order to accurately measure the fluctuation of the in-cylinder pressure, a pressure sensor is disposed close to the combustion chamber on the back side of the cylinder head, and an electric sensor corresponding to the in-cylinder pressure is provided. The lead wire for extracting the target output extends to the side opposite to the pressure sensor arrangement side (combustion chamber side) with respect to the metal shell. By the way, in general, between the threaded portion (male thread) of the metal shell and the threaded portion (female thread) of the cylinder head, the starting position of threading in the circumferential direction varies for each internal combustion engine. Accordingly, even if the spark plug is screwed into the cylinder head with a predetermined torque by engaging the tightening tool with the hexagonal portion, the extension position of the lead wire taken out from the pressure sensor in the circumferential direction is a predetermined position (for example, a detecting device or The direction of installation of the control device, etc.) varies. For this reason, such a spark plug with a pressure sensor, for example, connects the lead wire to the outside (the top of the cylinder head).
After attaching the plug cap to take out the lead wire, an extra space and an attaching member are required to bypass the lead wire and wire it at a predetermined position, which may complicate the work process and increase the manufacturing cost. Further, if the margin length of the detour wiring and the space for arranging the detour wiring are not sufficient, the lead wire may be damaged or disconnected.

SUMMARY OF THE INVENTION An object of the present invention is to easily align the extension position of a lead wire taken out from a pressure sensor in a circumferential direction with a predetermined position (direction) of, for example, a knocking detection device, and to damage or break the lead wire. Another object of the present invention is to provide a spark plug with a built-in pressure sensor, which is unlikely to generate pressure.

[0006]

In order to solve the above-mentioned problems, a spark plug with a built-in pressure sensor according to the present invention uses a pressure sensor connected to a lead wire by a lead wire joint to a metal shell of the spark plug. A spark plug with a built-in pressure sensor attached to a cylinder head of an internal combustion engine by a screw formed at the tip of the metal shell, wherein a spark discharge gap is located forward in the axial direction of the spark plug. As a side, the lead wire is rotatably arranged around the axis behind the metal shell in the axial direction, and supports the lead wire at a lead wire support portion formed at a predetermined position in the circumferential direction. A rotating lead supporting portion that rotates together with the rotating lead supporting portion, and the rotating lead supporting portion rotates together with the lead. Occurring, in order to absorb a change in path length between the lead wire support part and the pressure sensor side of the lead wire connecting portion, wherein the portion bending to the lead line is formed.

Thus, the rotary lead wire support is rotated in a state where the pressure sensor disposed on the metal shell is attached to the cylinder head together with the lead wire. Then, the bent portion of the lead wire bends (extends), so that the lead wire for extracting the electrical output from the pressure sensor can be easily aligned with the circumferentially extending position in the lead wire support portion. At this time, since the lead wire is largely bypassed and wiring is not required, the space can be saved, the working process can be simplified, and the manufacturing cost can be reduced. In addition, it is possible to prevent the lead wire from being damaged or disconnected. Further, since the length of the lead wire taken out from the lead wire support portion is minimized at any time, the lead wire is not obstructed.

[0008]

Embodiments of the present invention will be described below with reference to the embodiments shown in the drawings. As an outline of the spark plug with a built-in pressure sensor of the present invention, a pressure sensor 20 to which a lead wire 23 is connected by a lead wire connecting portion 21 is described.
Is disposed on the metal shell 11 of the spark plug 10, and the spark plug 1 with the built-in pressure sensor is attached to the cylinder head CH of the internal combustion engine by a screw 11 a formed at the tip of the metal shell 11, in the axial direction of the spark plug 10. In the lead wire supporting portion 41d which is disposed rotatably around the axis in the axial direction behind the metal shell 11 with the side where the spark discharge gap g is located as the front side, and formed at a predetermined position in the circumferential direction. Lead wire 23
And a rotating lead wire support portion 43 that rotates integrally with the lead wire 23 while supporting the lead wire 23. In order to absorb a change in the path length between the lead wire supporting portion 41d and the lead wire connecting portion (sensor case) 21 on the pressure sensor 20 side caused by the rotation of the rotary lead wire supporting portion 43 together with the lead wire 23. The lead 23 has a bent portion 23a.

In the lead wire support portion 41d, the lead wire 23 is connected to the rotary lead wire support portion 43 so as to be unable to move relative to the rotary lead wire support portion 43 in the axial direction.
It is formed between the rotary lead supporting portion 43 and the lead connecting portion 21. In addition, there is a cylindrical body 41 that covers the rotary lead supporting portion 43 from the outside, and the lead wire 23 is disposed inside the cylindrical body 41.

More specifically, FIG. 1 is a partial sectional view showing a state in which a spark plug according to a first embodiment of the present invention is attached to a cylinder head, and FIG. 2 is a view taken along the line XX of FIG. It is sectional drawing. The spark plug 1 with a built-in pressure sensor includes a spark plug 10 and a pressure sensor 20 integrally attached to a metal shell 11 of the spark plug 10.
And

A spark plug 1 with a built-in pressure sensor is provided with a plug hole P formed in a cylinder head CH of an internal combustion engine.
In the innermost part of H, the pressure sensor 20 is
At the same time, the screw portion 11a (male screw) at the tip of the metal shell 11 of the spark plug 10 is attached by tightening the screw portion (female screw) of the cylinder head CH. High voltage supply unit 30
When a high voltage generated in the ignition coil unit IC is applied to the spark plug 10 through the, a spark discharge is generated in the combustion chamber CR to burn the air-fuel mixture. Combustion chamber C at this time
The pressure of R (in-cylinder pressure) is measured by the pressure sensor 20 to perform, for example, knock detection, combustion pressure peak position detection, misfire detection, and the like, which is used for operation control of the internal combustion engine. In the following description, the side of the spark plug 1 with a built-in pressure sensor facing the combustion chamber CR is referred to as “front side” (or “front end side”), and the side facing the opposite direction is referred to as “rear side” (or “rear end”). Side)).

In the spark plug 10, an insulator 12 made of a ceramic sintered body such as alumina or aluminum nitride is provided inside a cylindrical metal shell 11.
Is fitted, and a leg portion 12 b formed on the tip end side of the insulator 12 protrudes forward from the metal shell 11. on the other hand,
The rear portion of the insulator 12 protrudes from the rear end of the metal shell 11 to form a corrugation portion 12a on the rear end side, and the terminal electrode 13 protrudes rearward from the rear end. A center electrode 14 electrically connected to the terminal electrode 13 projects forward from the tip of the leg portion 12b. The other end of the ground electrode 15 having one end joined to the tip of the metal shell 11 is bent back to the side,
The side faces the front end face of the center electrode 14 to form a spark discharge gap g. The metal shell 11 includes, from the front side, a screw portion 11a for mounting the spark plug 10 to the cylinder head CH, a gasket 11b for sealing a leak of combustion gas, a mounting seat portion 11c having a pressure sensor 20 fixed to a seat surface, and It has a hexagonal portion 11d to which a tool such as a plug wrench is fitted for screwing the screw portion 11a.

A sensor case 21 having an L-shaped cross section of the pressure sensor 20 is installed between the mounting seat 11c (seat surface) of the metal shell 11 and the gasket 11b, and is concentrically joined to the mounting seat 11c. I have. The inside of the sensor case 21 as a lead wire coupling portion is formed by laminating an annular plate packing, a piezoelectric element, an electrode plate, and an insulating plate from below (front) as in the conventional case, and is filled with resin or silicone rubber or the like. (Not shown). Terminal 2 formed on outer peripheral edge of annular electrode plate
A lead wire 23 extends rearward from 2.

In the high voltage supply section 30, a high voltage generated at the high voltage terminal HV of the ignition coil unit IC is supplied to the terminal electrode 13 of the spark plug 10 via a conductive spring 31 which is a conductive member. The insulating members 42 and 45 made of rubber (for example, silicon rubber) cover the entire high-voltage supply unit 30, in particular, the high-voltage terminal HV and the terminal electrode 13, and have a function of insulating.

The plug cap 40 mounted on the spark plug 1 with a built-in pressure sensor is provided with the insulating member 42,
45, a cylindrical body 41, a rotary lead wire support 43, and a support 44. The metal tubular body 41 is
On its front side, a regular hexagonal metal shell engaging portion 41b is formed concentrically with the hexagonal portion 11d of the metal shell 11, and on the rear side, the screw portion 11a of the metal shell 11 is screwed into the screw of the cylinder head CH. A regular hexagonal tool engagement portion 41c is formed in which a fastening tool for fastening to the portion is concentrically engaged. An intermediate portion excluding both end portions 41b and 41c constitutes a cylindrical main body portion 41a. Therefore, when the fastening tool such as the plug wrench is engaged with the tool engagement portion 41c, the cylindrical body 41 rotates integrally with the metal shell 11.

The lead wire 23 of the pressure sensor 20 is
1 and is taken out from the lead wire supporting portion 41d formed at the rear end of the tubular body 41. Further, the bent portion 23a of the lead wire is connected to the rotary lead wire support portion 4 described later.
3 and the lead wire coupling portion 21. A winding support portion 43b (see FIG. 2) around which the bending portion 23a is wound is disposed between the rotary lead wire support portion 43 and the lead wire coupling portion 21. Tool engaging portion 41c of cylindrical body 41
To the cylindrical body 4
When the metal shell 1 and the metal shell 11 are integrally rotated and tightened, since the lead wire 23 passes through the inside of the tubular body 41, a metal mesh (shield wire) such as stainless steel covering the lead wire 23 is used. There is no scraping of the inner wall of the plug hole PH. In addition, since the rotating lead wire support portion 43 and the support body 44 are made of resin, they can be lightweight and easily manufactured.

As shown in FIG. 2, the insulation member 42 (45) accommodates and holds the lead wire 23 over substantially the entire length thereof in the longitudinal direction, and has a function of determining the circumferential position of the lead wire 23a. (45a) is formed. The lead wire positioning portion 42a (45a) couples the circumferential position of the lead wire 23 in the longitudinal direction such that relative movement in the longitudinal direction is impossible. Therefore, when the rotating lead supporting portion 43 is rotated to position the extending position of the lead wire 23 in the circumferential direction, the rotational force acts directly on the leading end position of the lead wire withdrawal from the pressure sensor 20 to lead the lead wire. 23 can be prevented from occurring and contact failure can be prevented. Note that the lead wire positioning portion 42a may be formed at least at one location in the longitudinal direction of the insulating member 42.

A support 44 is provided on the rear side of the metal shell 11 so as to be non-rotatable around the axis. The rotary lead wire support 43 is connected to the support 44 so as to be rotatable around the axis. A winding support portion 43b around which the rotating lead wire support portion 43 and the support body 44 wind the bending portion;
44b, and the lead wire 23 is wound around them. The outer peripheral surface of at least one of the rotating lead wire support portion 43 and the support 44 is provided with a housing recess 43b as a winding support portion for winding and housing the lead wire.
4b is provided.

More specifically, as shown in FIG. 3, the rotary lead wire support 43 and the support 44 are provided with connecting portions 43a and 44a for connecting each other. Specifically, the convex connecting portion 43a is provided on the rotary lead wire supporting portion 43 side.
However, a concave coupling portion 44 a is provided on the support body 44 side, and is rotatable about the axis of the rotary lead wire support portion 43. Thereby, the rotary lead wire support can be easily and surely rotated. Then, between the rotary lead wire support portion 43 and the lead wire coupling portion 21 (see FIG. 1),
A bent portion 23a (see FIG. 4) of the lead wire 23 is formed, and is formed as storage recesses 43b and 44b for storing the bent portion 23a (see FIG. 4) of the lead wire 23. For this reason, the rotary lead wire support portion 43 and the support member 44 have a diameter D1 substantially equal to the inner diameter of the cylindrical body 41, whereas the storage recesses 43b and 44b have a diameter smaller than the diameter D1 by the thickness of the lead wire 23. D2. This allows
The bent portion 23a (see FIG. 4) is set between the inner wall of the cylindrical body 41 and the storage recesses 43b and 44b, so that the lead wire 23 is not damaged.

The storage recesses 43b, 44b are provided with lead wire guides 43c, 44c for guiding the storage of the lead wire 23. Lead wire guide 4
3c and 44c are inclined surfaces 4 for guiding the lead wires 23 taken out from the lead wire positioning portions 42a and 45a provided on the insulating members 42 and 45 without damaging them.
3d and 44d are provided. An extruding portion 43e for turning the lead wire 23 in the direction in which the lead wire 23 is to be moved is provided in the lead wire guide portion 43c on the rotary lead wire support portion 43 side.
It has.

Further, the rotary lead supporting portion 43 and the support 44 have connecting portions for connecting to the insulating members 42 and 45, respectively. More specifically, the protrusions 43f, 44f, which are elements of the connecting portion provided on the rotary lead wire support 43 and the support 44, and the recesses 42 of the insulating members 42, 45.
b and 45b are connected to each other. At the same time, the insulating members 42, 45
Claw portions 43g and 44g for preventing the detachment of the insulating member 42 in the axial direction by engaging with the claw receiving portion concave portions 42c and 45c provided in the concave concave portions 42b and 45b. , 45 are prevented. Although not shown, since the rotary lead support 43 and the insulating member 42 rotate together about the axis, another claw may be provided at a position intersecting the claw 43g. Also in this case, another claw receiving portion is provided on the side of the insulating member 42 that receives the claw portion.

FIG. 4 is a view conceptually showing the movement of the lead wire 23 when the lead wire 23 is arranged on the rotary lead wire support portion 43 and the support 44. FIG. 4A shows that the spark plug 10 with the pressure sensor (see FIG. 1) is inserted into the plug hole P.
H (see FIG. 1), the rotating lead support 4
3 shows the positional relationship between the support 3 and the support 44. Lead wire 2
3 is a lead wire guide portion 44c extending from the lead wire positioning portion 45a of the insulating member 45 along the inclined surface 44d of the support 44.
Pass through. Then, in the lead wire accommodating portions 43b and 44b, the bending portion 23a of the lead wire 23 makes one rotation from the support body 44 to the rotary lead wire support portion 43. One rotation of the lead wire 23 is performed on the inclined surface 4 of the rotary lead wire support portion 43.
3d, the lead wire positioning portion 4 of the insulating member 42
2a.

When the spark plug 10 with pressure sensor (see FIG. 1) is fixed to the plug hole PH (see FIG. 1),
The insulating member 42 and the rotating lead supporting portion 43
3 will be rotated to place it in a predetermined position.
In the present embodiment, the bending portion 23a of the lead wire 23 is relatively deformed rightward because it rotates to the left, but is not deformed rightward than the pushing portion 43e because it is pushed out by the pushing portion 43e. The bent portion 23a of the lead wire 23 is driven to the left.

FIG. 4 (b) shows the lead wire 2 in a state where the insulating member 42 and the rotary lead wire support 43 have been rotated substantially once.
3 shows the state of the bending portion 23a. In this case, the bending portion 23a of the lead wire 23 is housed in the concave portions 43b and 44b.
By deforming the lead wire 23 into a substantially U-shape, the bent portion 23a of the lead wire 23 wound in advance can be stored. In addition, the bent portion 23 of the lead wire 23
a is not necessarily deformed into a substantially U-shape, but may be deformed into another shape.

Next, the connecting portions 43a and 44a of the rotating lead supporting portion 43 and the supporting member 44 have rotation restricting means for preventing the rotating lead supporting portion 43 from rotating more than one rotation around its axis. Is provided. Specifically, as shown in FIG. 5A, a boss 43h as a rotation restricting means is provided at a part of the tip of the convex coupling portion on the rotary lead wire support portion side. Also, a boss receiving portion 44 is provided at the concave coupling portion 44a on the support body 44 side against the boss 43h.
h is provided.

Then, as shown in FIG. 5 (b), when the convex connecting portion 43a is fitted into the concave connecting portion 44a and rotates around its axis, the boss 43 does not rotate up to a maximum.
h comes into contact with the boss receiving portion 44h, and prevents further rotation in the same direction. In the present embodiment, in a state where the bending portion 23a of the lead wire 23 (see FIG. 4) is wound by one turn, the rotating lead wire support portion 43 is bent against the support member 44 by the bending portion 23a of the lead wire 23 (see FIG. 4). 4) so that the boss 43h and the boss receiving portion 44 do not rotate in the extending direction.
h is arranged. Therefore, when the lead wire 23 taken out of the cylindrical body 41 (see FIG. 1) is moved to a predetermined position, the insulating member 42 and the rotating lead wire supporting portion 43 are bent at the bent portion 23a of the lead wire 23 (see FIG. 4). It is adjusted by rotating in the direction of eliminating (loosening) winding.

The conductive members 31 for supplying a high voltage to the spark plug 1 with a built-in pressure sensor are provided on the connecting portions 43a and 44a of the rotary lead supporting portion 43 and / or the supporting member 44.
Insulating means 46 for crimping the rotary lead support 43 and the support 44 is provided to insulate the rotary head support 43 from the cylinder head CH and / or the lead wire 23. Specifically, as shown in FIG. 6, a concave portion 43i is formed on a side surface of the convex coupling portion 43a of the rotary lead wire supporting portion 43, and an O-ring 46 as an insulating means is disposed in the concave portion 43i. When the O-ring 46 comes into contact with the inner surface of the concave coupling portion 44a of the support body 44, the plug hole PH (see FIG. 1) and the lead are formed from the conductive spring 31 (see FIG. 1) which is a conductive member. Leakage to the line 23 (see FIG. 1) is prevented. In this embodiment, the O-ring 4
Although 6 is provided only at one location, it may be provided at a plurality of locations. Although not shown, it is also possible to arrange the O-ring 46 at the concave coupling portion 44 a of the support 44. In this case, the concave portion is provided in the concave coupling portion 44 a of the support 44.

Next, a method of mounting the spark plug 1 with a built-in pressure sensor on the cylinder head CH of the internal combustion engine will be described. First, the insulating member 42 and the rotating lead wire support 4
3 and the support 44 and the insulating member 45 are connected. Then, the rotary lead support 43 and the support 44 are fitted together, and the positional relationship between the boss 43h and the boss receiving portion 44h is adjusted. Then, the lead wire 23 of the pressure sensor 20
Is wound by one rotation of the housing recesses 43b and 44b of the rotary lead wire support portion 43 and the support body 44. Then, the lead wire 23 is connected to the lead wire positioning portions 42 of the insulating members 42 and 45.
a, while being held and held in the cylindrical body 41, is pushed into the inside of the cylindrical body 41, and the leading end of the lead wire 23 coming out of the rear end lead wire supporting portion 41d of the cylindrical body 41 is connected to the high voltage terminal HV housing space (high at the time of assembly). (A space for accommodating the voltage terminal HV). In addition, the metal shell engaging portion 4 at the front end of the cylindrical body 41.
1b is the hexagonal portion 11 of the metal shell 11 of the spark plug 10
a.

A tool (for example, a plug wrench) for tightening the screw portion 11a is fitted to the tool engaging portion 41c of the tubular body 41 and tightened. When the tightening is completed, if the extension position of the lead wire 23 taken out from the pressure sensor 20 in the circumferential direction is different from the predetermined position, the insulating member 42 (rotary lead wire support portion 43) is rotated to the predetermined position. Adjustment (alignment) of the extension position of the lead wire 23 is completed only by the operation to be performed.

The embodiment of the present invention has been described above.
The present invention is not limited to this, and improvements based on the knowledge of those skilled in the art can be appropriately added without departing from the scope described in each claim.

[Brief description of the drawings]

FIG. 1 is a partial sectional view showing a state in which a spark plug or the like of the present invention is attached to a cylinder head.

FIG. 2 is a sectional view taken along the line XX of FIG. 1;

FIG. 3 is an enlarged view of a rotary lead supporting portion and a support.

FIG. 4 is a view conceptually showing movement of a lead wire when the lead wire is arranged on a rotating lead wire support portion and a support.

FIGS. 5A and 5B are an enlarged perspective view and a cross-sectional view of a convex connecting portion of the rotary lead wire supporting portion and a concave connecting portion of the support.

FIG. 6 is an enlarged cross-sectional view of a rotary lead supporting portion and a support.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Spark plug with a built-in pressure sensor (spark plug with pressure sensor) 10 Spark plug 11 Metal shell 11a Screw part 20 Pressure sensor 23 Lead wire 23a Flexure part 40 Plug cap 41 Cylindrical body 41c Tool engagement part 41d Lead wire support part 42 Insulation Member 42a Lead wire positioning portion 42b Recess 43 Rotating lead support portion 43a Convex coupling portion 43b Storage recess 43c Lead wire guide 43d Inclined surface 43e Extruded portion 43f Convex portion 43g Claw portion 43h Boss 43i Depressed portion 44 Support body 44a Recessed shape Coupling portion 44b Storage recess 44c Lead wire guide 44d Inclined surface 44f Convex portion 44g Claw portion 44h Boss receiving portion 45 Insulating member 45a Lead wire positioning portion 45b Recess 45 Rotating lead wire support 46 O-ring

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01T 13/08 H01T 21/02 21/02 F02P 17/00 ER (72) Inventor Takahiro Suzuki Nagoya, Aichi 14-18 Takatsuji-cho, Mizuho-ku, Japan F-term (reference) 2F055 AA23 BB14 CC60 DD20 EE23 FF38 FF43 GG12 GG25 3G019 KA14 KA28 KB07 5G059 JJ25 KK03

Claims (9)

[Claims] 1. A pressure sensor having a lead wire connected by a lead wire connecting portion disposed on a metal shell of a spark plug, and a pressure sensor attached to a cylinder head of an internal combustion engine by a screw formed at a tip of the metal shell. A built-in spark plug, wherein in a direction of an axis of the spark plug, a side on which a spark discharge gap is located is a front side, and the spark plug is rotatably disposed around the axis on a rear side of the metal shell in the axial direction. A rotating lead supporting portion that rotates integrally with the lead while supporting the lead at a lead supporting portion formed at a predetermined position in the direction, and the rotating lead supporting portion is provided together with the lead. A change in a path length between the lead wire supporting portion and the lead wire connecting portion on the pressure sensor side caused by rotation is absorbed. , The pressure sensor internal spark plug, wherein a portion bending the lead wires are formed. 2. The lead wire support portion, wherein the lead wire is coupled to the rotary lead wire support portion such that the lead wire cannot move relative to the rotary lead wire support portion in an axial direction, and the bending portion is connected to the rotary lead wire support portion and the rotary lead wire support portion. 2. The spark plug with a built-in pressure sensor according to claim 1, wherein the spark plug is formed between the spark plug and a lead wire joint. 3. The spark plug with a built-in pressure sensor according to claim 1, further comprising a tubular body that covers the rotary lead wire supporting portion from the outside, wherein the lead wire is disposed inside the tubular body. 4. A supporting member is provided on the rear side of the metal shell so as to be non-rotatable around the axis, and the rotary lead wire supporting portion is coupled to the supporting member so as to be rotatable around the axis. 4. The spark plug with a built-in pressure sensor according to any one of items 3 to 3. 5. The spark plug with a built-in pressure sensor according to claim 1, wherein the rotary lead wire support and the support form a winding support for winding the flexure, and the lead wire is wound over the support. . 6. A spark plug with a built-in pressure sensor according to claim 1, wherein an accommodating recess for winding and accommodating the lead wire is provided on an outer peripheral surface of at least one of the rotary lead wire support portion and the support. . 7. Each of the couplings for coupling the rotary lead support and the support is configured to prevent the rotary lead support from rotating more than one rotation about its axis. 7. The spark plug with a built-in pressure sensor according to claim 1, further comprising a rotation restricting means. 8. The conductive member for supplying a high voltage to the spark plug with a built-in pressure sensor, and the cylinder head and / or the lead wire are provided on the rotary lead wire support portion and / or the connection portion of the support. The spark plug with a built-in pressure sensor according to any one of claims 1 to 7, further comprising insulation means for crimping the rotary lead wire support portion and the support body for insulation. 9. The lead wire after using a spark plug with a built-in pressure sensor according to any one of claims 1 to 8 to attach the spark plug with a built-in pressure sensor to a main body of an internal combustion engine by tightening with a screw action. A method of mounting a plug, comprising: rotating a support portion to take out the lead wire from a predetermined position in a circumferential direction.