JP2017117733A - Spark plug - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spark plug capable of being attached to a desired attachment direction in a low cost, while holding sealing performance of an internal combustion.SOLUTION: A spark plug 100 includes: a spark plug main body; an attachment direction confirmation display 107; a sealing member 108; and an elastic member 109. When attaching the spark plug 100 to a cylinder head with an elastic force, the elastic member 109 tights the spark plug 100 up to a predetermined tightening torque, and thereafter, maintains the predetermined tightening torque even when the spark plug is rotated in at least one more time. Thus, since the spark plug 100 can be rotated after the spark plug 100 is attached to the cylinder head with a regulation torque, the attachment direction of the spark plug 100 can be adjusted so that the spark plug 100 is set to a predetermined direction, and, for example, a ground electrode 103f becomes the predetermined direction.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a spark plug attached to an engine, and more particularly to a spark plug that can be attached in a desired attachment direction.

  Conventionally, the spark plug attached to the engine has the following points to be improved. In recent years, in order to improve fuel efficiency of internal combustion engines such as automobile engines, the internal combustion engines have been driven by lean burn or direct fuel injection. In such an internal combustion engine (hereinafter also simply referred to as an engine), it is desired to improve the ignitability of a spark plug (hereinafter also simply referred to as a plug) and to reliably ignite an air-fuel mixture.

  By the way, in the conventional engine, the phase of the female screw formed in the plug mounting hole formed in the cylinder head and the male screw formed in the mounting screw portion of the metal shell of the plug is not particularly defined. Therefore, when the plug is screwed into the plug mounting hole, the circumferential position of the outer electrode fixed to the tip of the mounting screw exposed in the cylinder cannot be determined. That is, by the combination of the cylinder head and the plug, the circumferential position of the outer electrode can be any position within a range of 360 degrees.

  However, in the case of driving by lean burn or direct fuel injection, a rich (high fuel ratio) mixture flow (swirl) that can be ignited is formed, and the discharge region between the center electrode and the outer electrode of the plug is formed. Since the swirl is designed to pass therethrough, if the fixed position of the outer electrode is on the upstream side of the swirl, it is difficult for the rich air-fuel mixture to flow into the discharge region, and misfire is likely to occur. Therefore, in this case, the engine can be driven only in a range where the A / F (Air / Fuel) value is relatively small, and the fuel consumption is reduced.

  Therefore, there is a conventional spark plug that fixes the circumferential position of the outer electrode of the spark plug with respect to the cylinder head so as not to disturb the flow of the air-fuel mixture. Such a spark plug will be described using a spark plug 10 attached to the engine shown in FIGS. FIG. 5 is a partially broken sectional view and a bottom view of the spark plug 10 according to the present embodiment. The spark plug 10 is a so-called one-pole type in which only one outer electrode 16 is formed, and is sealed by a plug seat surface 14s that forms a plane provided between the main body 12 and the tip 15 of the metal shell 11. Is a so-called flat sheet type.

  The plug 10 includes a center electrode 17 extending in the vertical direction (axial direction) in the figure, an insulator (insulator) 18 surrounding the periphery, and a metal shell 11 that holds the lower part in the figure. Is a main body portion 12 provided with an upper proximal end main body portion 13 and a lower distal end side main body portion 14 in the figure, and is smaller in diameter than the distal end side main body portion 14 and on the axial distal end side (lower in the drawing) And a distal end 15 extending. Unlike the normal spark plug, the distal end portion 15 is not formed with a male screw and has an outer peripheral surface that is substantially cylindrical. The outer electrode 16 is fixed to the distal end surface 15a of the distal end portion 15 by the fixing portion 16a. The tip of the outer electrode 16 extends toward the center of the ring-shaped tip surface 15a as shown in FIG. 5B, and is bent into a substantially L shape as shown in FIG. A gap is formed.

  Further, a ring-shaped gasket 19 is attached to the plug seat surface 14s, and a connection terminal 9 connected to the center electrode 17 is disposed at the base end (upper end in the figure).

  Furthermore, the base end side main body portion 13 is located on the base end side (upper side in the drawing) than the base end side main body central portion 13b having a slightly larger diameter and the internal structure, and is an insulator. A caulking portion 13 a that prevents the 18 from coming out upward is provided, and a second caulking portion 13 c that is similarly located on the distal end side and fixes the insulator 18 is provided. In addition, a protrusion 14t is provided at one of the side surfaces 14b of the distal end side main body 14. For this reason, the front end side main body portion 14 is provided with a key groove 36 (not shown) that fits the protrusion 14t in a plug mounting hole 32 (not shown) formed in the cylinder head 30 (not shown). The distal end side main body corresponding part 34 (not shown) can be fitted only at one place in the circumferential direction.

  As shown in FIG. 6B, the head main body 31 of the cylinder head 30 (not shown) includes a plug mounting hole 32 penetrating between the head upper surface 31a (not shown) and the combustion chamber surface 31b (not shown). Further, screw holes 37a to 37d (not shown) for screwing the plug fitting 20 (not shown) are formed in the surrounding head upper surface 31a. In addition, the distal end side main body corresponding portion 34 (not shown) located between the insertion portion 33 and the distal end corresponding portion 35 (not shown) is free to play when the spark plug 10 is inserted. It is the part that is inserted into the fitting shape. Here, the seal surface 34a that hits the boundary between the tip-side main body corresponding portion 34 and the tip-corresponding portion 35 is a surface on which the gasket 19 of the plug 10 comes into contact and seals. Further, a key groove 36 (not shown) is formed in the distal end side main body corresponding portion 34 with a width and a depth suitable for the protrusion 14 t of the plug 10.

  The fixture main body 21 (not shown) of the plug fixture 20 is made of metal, and includes a flange portion 23 for fixing the plug fixture 20 to the cylinder head 30 having the plug fixture 20 and a substantially cylindrical tubular portion 22. . Attachment holes 27a to 27d are formed in the flange portion 23 at positions corresponding to the screw holes 37a to 37d of the cylinder head 30, respectively. As shown in FIG. 6B, the cylindrical portion 22 has an outer peripheral surface 22b that is slightly smaller in diameter than the insertion portion 33 of the cylinder head 30, and a distal end surface 22a at the distal end (lower end in the figure). In order to make it possible to press the upper surface 14 a of the distal end side main body portion 14 of the plug 10, the inner peripheral surface 22 c is made larger in diameter than the proximal end side main body portion 13.

  Next, assembly of the plug 10 and the plug fixture 20 to the cylinder head 30 will be described. Note that the cylinder head 30 is fastened to the engine block by a known method. First, as shown in FIG. 6B, the plug 10 is inserted into the plug mounting hole 32 of the cylinder head 30. At this time, since the projecting portion 14t is formed on the distal end side main body portion 14 (see FIG. 5) of the plug 10, it is not normally fitted completely. Therefore, the plug 10 is rotated around the axis O. Then, when the protrusion 14t is positioned in the key groove 36 formed in the front end side body corresponding part 34, for example, when the protrusion 14t is positioned on the right side in FIG. The plug 10 is fitted to the cylinder head 30. That is, in the plug 10, the position (angle) at which the front end side main body portion 14 of the plug 10 and the front end side main body corresponding portion 34 of the plug mounting hole 32 are fitted to each other by the protrusion 14 t and the key groove 36 is 360 degrees in one round. Are limited to one place. As a result, the gasket 19 comes into contact with the seal surface 34a.

  Furthermore, the plug 10 is fixed using the plug fixing tool 20 described above. First, as shown in FIG. 6B, the cylindrical portion 22 of the plug fixture 20 is inserted into the plug mounting hole 32. Since the outer peripheral surface 22 b of the cylindrical portion 22 is slightly smaller in diameter than the insertion portion 33, it can be inserted in a loose fit, and the distal end surface 22 a of the cylindrical portion 22 is the upper surface of the distal end side main body portion 14 of the plug 10. 14a abuts. At this time, the insulator 18 on the proximal end side of the plug 10 is inserted and held in the center of the insulator holding member 24 inside the cylindrical portion 22, and the connection terminal 9 is connected to the elastic terminal 25. .

  Next, the orientation of the flange portion 23 of the plug fixture 20 is adjusted so that the mounting holes 27a to 27d are fitted to the screw holes 37a to 37d, and the plug fixtures using bolts BLa to BLd as shown in FIG. 6A. 20 is fixed to the head upper surface 31 a of the cylinder head 30. Thereby, the front end side main body portion 14 of the plug 10 is pressed by the front end surface 22a through the cylindrical portion 22, and a seal between the gasket 19, the seal surface 14s, and the stepped portion 34a can be performed. At this time, since the distal end side main body portion 14 is uniformly pressed in the circumferential direction by the cylindrical portion 22, the sealing can be surely performed (see Patent Document 1 above).

JP 2007-168620 A

  The above-mentioned conventional spark plug has the following points to be improved. The spark plug 10 has a protrusion 14t, the plug fixture 20 has a cylindrical portion 22 having a predetermined length, and the cylinder head 30 has a key groove 36. Further, the spark plug 10 does not have a screw portion for attaching to the cylinder head 30. That is, the spark plug 10, the plug fixture 20, and the cylinder head 30 are special parts and need to be specially manufactured. For this reason, there is a point to be improved that it is very costly to adjust the mounting direction of the spark plug 10 using the spark plug 10, the plug fixture 20, and the cylinder head 30.

  Therefore, an object of the present invention is to provide a spark plug that can be mounted in a desired mounting direction at a low cost while maintaining the hermeticity of the internal combustion engine.

  Means for solving the problems in the present invention and the effects of the invention will be described below.

  An ignition plug according to the present invention is an ignition plug attached to an internal combustion engine, and includes an ignition plug body having a screw portion screwed into an ignition plug attachment hole of the internal combustion engine, a seal inserted into the screw portion and in contact with the engine A member, and an elastic member that is inserted into the screwing portion and disposed between the seal member and the spark plug body.

  Thus, when the spark plug is attached to the internal combustion engine, the spark plug can be attached in a desired direction while maintaining the hermeticity of the internal combustion engine.

1 is a front view including a partial cross section of a spark plug 100 which is an embodiment of a spark plug according to the present invention. It is a figure which shows the attachment state of the spark plug 100, A shows before adjusting the direction of the ground electrode 103f, B shows after adjusting the direction of the ground electrode 103f, respectively. It is a figure which shows the attachment state of the spark plug 100, A shows before adjusting the direction of the ground electrode 103f, B shows after adjusting the direction of the ground electrode 103f, respectively. It is a figure which shows the other Example of the spark plug which concerns on this invention. It is a figure which shows the conventional spark plug. It is a figure which shows the conventional spark plug.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  A spark plug 100 as an embodiment of the spark plug according to the present invention will be described with reference to FIG. In FIG. 1, the front view of the partial cross section of the spark plug 1 is shown. In FIG. 1, along the direction of the central axis J100 of the spark plug 100, the lower side is the electrode side of the spark plug 100, and the upper side is the terminal side.

  The spark plug 100 includes a spark plug body, an attachment direction confirmation display 107, a seal member 108, and an elastic member 109. In the spark plug body, the spark plug 100 includes an insulator 101, a metal shell 103, an electrode 105, and an airtight holding portion 106 (not shown). The spark plug body is the same as the conventional one. The insulator 101 is made of an insulator and has a cylindrical shape. The metal shell 103 is disposed on the outer periphery of the insulator 101 on the electrode side. The electrode 105 is disposed in a shaft hole 101b (described later) of the insulator 101.

  The insulator 101 has a cylindrical portion 101a and a shaft hole 101b. The cylinder part 101a has a terminal side cylinder part 101a1, a large diameter cylinder part 101a2, an intermediate cylinder part 101a3, and a leg long part 101a4 which are formed in order from the terminal side toward the electrode side. The terminal side cylinder portion 101a1 has a length that is about half of the entire length of the insulator 101. The large-diameter cylindrical portion 101a2 is formed to protrude outward from the terminal-side cylindrical portion 101a1. The intermediate cylinder portion 101a3 is formed to have an outer diameter that is the same as that of the terminal-side cylinder portion 101a1 and is smaller in diameter toward the center than the large-diameter cylinder portion 101a2. The long leg portion 101a4 is formed with a smaller diameter toward the center than the intermediate tube portion 101a3.

  The shaft hole 101b is formed so as to penetrate the insulator 101 along the central axis J100 of the insulator 101.

  The metal shell 103 has a cylindrical shape. The metal shell 103 is disposed outside the large-diameter cylindrical portion 101a2, the intermediate cylindrical portion 101a3, and most of the long leg portions 101a4 of the insulator 101. The metal shell 103 includes a screw portion 103a, a seat portion 103b, a tool engaging portion 103c, a caulking portion 103d, an internal protrusion 103e, and a ground electrode 103f. The screw portion 103 a is formed on the outer peripheral surface of the metal shell 103. The spark plug 100 is attached at a predetermined position by screwing the screw portion 103a into an attachment hole of an internal combustion engine, a fuel cell reformer or the like. The seat portion 103b is formed on the terminal side of the screw portion 103a so as to protrude outward.

  The tool engaging portion 103c is formed on the electrode side of the seat portion 103b. The tool engaging portion 103c has a hexagonal cross section for engaging a tool such as a wrench when attaching the spark plug 100 to a cylinder head or the like of the internal combustion engine. The caulking portion 103d is formed on the terminal side of the tool engaging portion 103c, that is, on the terminal side end of the metal shell 103 so as to bend toward the center.

  The internal protrusion 103e is formed on the inner peripheral surface of the metal shell 103. The insulator 101 is locked to the metal shell 103 by the internal protrusion 103e. The insulator 101 is inserted from the terminal side to the electrode side with respect to the metal shell 103 until the intermediate cylinder portion 101a3 engages with the internal protrusion 103e of the metal shell 103, and the terminal side opening of the metal shell 103 is opened. The portion is fixed to the metal shell 103 by caulking the portion radially inward, that is, by forming a caulking portion 103d.

  The ground electrode 103f is disposed at the electrode side end of the screw portion 103a, that is, the electrode side end of the metal shell 103. The ground electrode 103f has a column shape. The ground electrode 103f has an L shape bent at an intermediate portion. One end of the ground electrode 103f is connected to the electrode side end of the screw portion 103a, and the other end is disposed so as to face the tip of the center electrode 105a (described later). A spark discharge interval 103f1 is formed between the tip of the center electrode 105a and the tip of the ground electrode 103f. In the spark discharge interval 103f1, a spark discharge is performed between the tip of the center electrode 105a and the tip of the ground electrode 103f.

  The electrode 105 includes a center electrode 105a, a terminal electrode 105b, a resistor 105c, and glass seal portions 105d and 105e. The center electrode 105a has a cylindrical shape. The center electrode 105a is disposed on the electrode side of the shaft hole 101b, and is fixed so that the tip protrudes outward from the tip of the leg long portion 101a4 of the insulator 101. The terminal electrode 105b is disposed on the terminal side of the shaft hole 101b, and is fixed so as to protrude outward from the terminal-side cylinder portion 101a1 of the insulator 101.

  The resistor 105c has a cylindrical shape. The resistor 105c is disposed between the center electrode 105a and the terminal electrode 105b in the shaft hole 101b. Thereby, the resistor 105c electrically connects the center electrode 105a and the terminal electrode 105b. The glass seal portions 105d and 105e are disposed inside the shaft hole 101b of the insulator 101 so as to sandwich the resistor 105c. The glass seal portions 105d and 105e have conductivity. The glass seal portions 105d and 105e are disposed at both ends of the resistor 105c to electrically connect the center electrode 105a and the terminal electrode 105b.

  The airtight holding unit 106 includes a plate packing 106a and a ring member 106b. The plate packing 106a has an annular shape. The plate packing 106 a is disposed between the internal protrusion 103 e of the metal shell 103 and the intermediate cylinder portion 101 a 3 of the insulator 101. The plate packing 106a maintains the airtightness in the combustion chamber, and the fuel gas entering the gap between the leg long portion 101a4 of the insulator 101 exposed to the combustion chamber and the inner peripheral surface of the screw portion 103a of the metal shell 103 leaks to the outside. To prevent. The ring member 106b has an annular shape. The ring member 106b is disposed between the metal shell 103 and the insulator 101 so that one end thereof is along the inner peripheral surface of the caulking portion 103d. The ring member 106b keeps the metal shell 103 and the insulator 101 in close contact with each other by caulking to maintain airtightness.

  The attachment direction confirmation display 107 is a metallic convex object disposed on the metal shell 103 of the spark plug 100, specifically, the terminal side upper surface of the seat 103b. When the spark plug 100 is attached, by confirming the position of the attachment direction confirmation display 107, the attachment direction of the spark plug 100, that is, the direction of the ground electrode 103f can be confirmed. The attachment direction confirmation display 107 is formed integrally with the metal shell 103.

  The seal member 108 is a so-called gasket and has an annular shape. The seal member 108 is inserted into the screw portion 103a and disposed at the boundary between the screw portion 103a and the seat portion 103b. The seal member 108 keeps the metal shell 103 and the engine in close contact when the metal shell 103 is attached to the engine, and thus maintains the airtightness of the combustion chamber of the engine.

  The elastic member 109 is made of a heat resistant synthetic resin having a predetermined elastic force. The elastic member 109 has an annular shape. The elastic member 109 is inserted into the screw portion 103 a of the metal shell 103 and is disposed between the seal member 108 and the seat portion 103 b of the metal shell 103. The elastic member 109, together with the seal member 108, allows the direction of the ground electrode 103f to be adjusted while maintaining the mounting torque of the spark plug 100 with respect to the cylinder head at a predetermined value in order to maintain the airtightness of the combustion chamber. It is a member.

  When the spark plug 100 is attached to the cylinder head by elastic force, the elastic member 109 tightens the spark plug 100 to a predetermined tightening torque and then rotates the spark plug at least once after the tightening torque. Maintain torque. As a result, the spark plug 100 can be rotated after the spark plug 100 is attached to the cylinder head with a specified torque, so that, for example, the ground electrode 103f is in a desired direction so that the spark plug 100 takes a desired direction. Thus, the mounting direction of the spark plug 100 can be adjusted.

  Next, a method of using the spark plug 100 will be described with reference to FIGS. First, a case where the ignition plug 100 is attached in a direction in which the combustion state of the air-fuel mixture is formed in a uniform region with respect to the ignition plug 100 will be described as a desired direction in which the ignition plug 100 is attached. As shown in FIG. 2A, when the spark plug 100 is mounted with a predetermined tightening torque, the direction of the ground electrode 103f in the spark plug 100 with respect to the flow a2 of the fuel mixture is not appropriate, and the spark plug 100 Even if the fuel combustion region R10 of the ground electrode 103f is biased, the spark plug 100 is rotated by a necessary angle α so that the direction of the ground electrode 103f is an appropriate direction with respect to the mixture flow a2. Thus, as shown in FIG. 2B, a uniform combustion region R100 can be formed in the cylinder. Note that the rotation angle α of the spark plug 100 is less than one revolution, that is, less than one revolution of the spark plug 100. The appropriate direction of the ground electrode 103f with respect to the air-fuel mixture flow a2 is a state in which the combustion state of the fuel spreads substantially evenly around the central axis J100 of the spark plug 100 when viewed from the electrode side of the spark plug 100. Say.

  Next, as a desired direction for attaching the spark plug 100, a case where the ground electrodes 103f are attached in the same direction in the plurality of spark plugs 100 will be described. As shown in FIG. 3A, when the spark plug 100 is attached to a multi-cylinder engine, even if the direction of the ground electrode 103f in each spark plug 100 is different at the stage where the spark plug 100 is attached with a predetermined tightening torque, By rotating the required angle α1, angle α2, and angle α3 for each spark plug 100, the direction of the ground electrode 103f of each spark plug 100 can be adjusted as shown in FIG. 3B. Thereby, the combustion region in each cylinder can be optimized, and the variation in the ignition state between the cylinders can be made uniform. Note that the rotation angles α1, α2, and α3 of each spark plug 100 are less than one revolution, that is, less than one revolution of each spark plug 100.

[Other embodiments]
(1) Elastic member 109: In Example 1 described above, the elastic member 109 is formed of a heat-resistant synthetic resin. However, the elastic member 109 is not limited to the illustrated example as long as it has a predetermined elastic force. For example, as shown in FIG. 4, an elastic member 209 formed by a metal ring washer having a cross section and a convex shape below may be used. Moreover, you may make it form an elastic member with what has predetermined elastic force, such as a nonwoven fabric.

  (2) Attachment direction confirmation display 107: In the above-described first embodiment, the attachment direction confirmation display 107 is a metal protrusion disposed on the metal shell 103 of the spark plug 100. As long as it can be confirmed from the outside, it is not limited to the example. For example, it may be a hole, a concave groove, a planar straight line display, a symbol display, a character display, or the like.

  In addition, the attachment direction confirmation display 107 is arranged on the upper surface on the terminal side of the seat 103b of the metal shell 103, but is not limited to the example as long as it can be confirmed from the outside. For example, it may be displayed on the surface of the terminal side cylinder portion 101a1 of the insulator 101, or may be displayed on the upper surfaces of the tool engagement portion 103c and the crimping portion 103d of the metal shell 103.

  Further, an attachment direction confirmation display may be arranged also in the vicinity of an attachment hole of the ignition plug 100, for example, an internal combustion engine such as a cylinder head to which the ignition plug 100 is attached. Thereby, for example, by attaching the ignition plug 100 so that the attachment direction confirmation display 107 of the ignition plug 100 and the attachment direction confirmation display of the internal combustion engine face each other, the direction of the ground electrode 103f of the ignition plug 100 is changed in advance. It can be easily adjusted in a predetermined direction, for example, a direction in which a uniform combustion state is obtained with respect to the air-fuel mixture flow.

  The spark plug according to the present invention can be used, for example, in a passenger car engine.

DESCRIPTION OF SYMBOLS 100 Spark plug 101 Insulator 101a Tube part 101a1 Terminal side cylinder part 101a2 Large diameter cylinder part 101a3 Intermediate cylinder part 101a4 Leg long part 101b Shaft hole 103 Main metal fitting 103a Screw part 103b Seat part 103c Tool engagement part 103d Clamping part 103e Internal protrusion Part 103f Ground electrode 103f1 Spark discharge interval 105 Electrode 105a Center electrode 105b Terminal electrode 105c Resistor 105d Glass seal part 105e Glass seal part 106 Airtight holding part 106a Plate packing 106b Ring member 107 Mounting direction confirmation display 108 Seal member 109 Elastic member

Claims (1)

A spark plug attached to an internal combustion engine,
A spark plug main body having a screw portion screwed into the spark plug mounting hole of the internal combustion engine;
A seal member inserted into the threaded portion and in contact with the engine;
An elastic member inserted into the threaded portion and disposed between the seal member and the spark plug body;
With spark plug.

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