JP2010073313A - Spark plug - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spark plug which strikes a spark between a central electrode chip and a ground electrode chip even under a high-speed air flow to ignite a fuel air mixture and allow a flame to expand in a fine manner. <P>SOLUTION: The spark plug 1 includes a central electrode 4 having the central electrode chip 8 fixed thereto, and a ground electrode 5 having the ground electrode chip 9 fixed thereto opposite to the central electrode chip 8. The central electrode chip 8 are composed of a plurality of electrode chips 8a, 8b, and 8c; and/or the ground electrode chip 9 are composed of a plurality of electrode chips 9a, 9b, and 9c. The electrode chips 8a, 8b, and 8c and 9a, 9b, and 9c are arranged from the position of the front end 5b of the ground electrode 5 toward the side 5a of the ground electrode 5 in such a way that their lengths are determined to be smaller as they heads from the position of the front end 5b of the ground electrode 5 toward the side 5a of the ground electrode 5. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a spark plug, which is suitable for a spark plug used for an internal combustion engine for automobiles.

  For example, as shown in the attached FIG. 9, a soak plug used for an internal combustion engine for automobiles has a center electrode tip 6 and a ground electrode tip 7 made of noble metal fixed to a center electrode 4 and a ground electrode 5, respectively. Sparks are generated between the electrode tips 6 and 7 to ignite and burn the mixed airflow.

  In recent years, regulations on fuel consumption and exhaust gas have been strengthened every year, and as a means to meet these requirements, the mixed airflow in the internal combustion engine has been accelerated, and this mixed airflow is grounded as shown in FIG. In a state of flowing as a high-speed air flow in the side portion side direction of the electrode 5, the spark E emitted from the center electrode tip 6 is caused to flow by the high-speed air flow and land on the bent portion 5 c portion of the ground electrode 5. That is, no spark E is generated between the electrode tips 6 and 7. Therefore, since the flame of the air-fuel mixture ignited by the spark E is generated near the bent portion 5c of the ground electrode 5, the flame is difficult to spread and cannot be burned sufficiently.

  Patent Document 1 below describes a spark plug provided with a ground electrode chip 61 in addition to the ground electrode chip 60 facing the center electrode chip 50 in FIGS. 2, 7 and 8. 61 is not in the direction of the ground electrode 40 but in a direction orthogonal to the ground electrode 40, and is disposed only on the axis of the center electrode tip 50, and on the side of the ground electrode 40 from the center electrode tip 50. Since it is not arranged, when the high-speed air current flows in the direction of the ground electrode 40, the spark also lands on the ground electrode 40.

Further, in Patent Document 2 below, a spark plug having a structure in which a gap 4e is formed in the ground electrode 4 is described in FIG. The sparks land on the bent portion of the ground electrode 4 and cannot solve the above problem.
JP 2002-237366 A Sho 55-121290

  The present invention has been made in view of the above points, and at least one of a center electrode tip and a ground electrode tip is constituted by a plurality of tips, and the plurality of electrode tips are arranged from the front end side of the ground electrode. While arranging to the side part side of the ground electrode and setting the length of the plurality of electrode tips as they go from the tip side of the ground electrode to the side part side of the ground electrode, Even if the spark from the center electrode tip is likely to flow to the bent portion of the ground electrode, the deterioration of combustion is suppressed by capturing the spark with the ground electrode tip on the side of the ground electrode, and the high-speed air flow It is an object of the present invention to provide a spark plug capable of obtaining the best combustion by always generating a spark at an electrode tip on the tip end side of the ground electrode under the condition where no ground is present.

The invention according to claim 1 is a spark plug in which a center electrode tip is electrically fixed to a center electrode and a ground electrode tip is electrically fixed to a ground electrode so as to face the center electrode tip,
The center electrode chip or / and the ground electrode chip is composed of a plurality of chips,
In addition, the plurality of electrode tips are arranged from the front end side of the ground electrode to the side portion side of the ground electrode, and the length of the plurality of tips is from the front end side of the ground electrode to the ground electrode. It is characterized by being set shorter as going to the side.

  According to the above configuration, in the normal state, the best combustion can be obtained by generating a spark between the two electrode tips on the tip side of the ground electrode. Under high-speed airflow, the spark emitted from the center electrode tip is Even if it is likely to be swept through the bent portion, it is possible to prevent deterioration of combustion by catching a spark with the electrode tip on the side of the ground electrode.

  The invention according to claim 2 is characterized in that the cross-sectional area of the plurality of electrode tips is set to be smaller from the tip end side of the ground electrode toward the side portion side of the ground electrode.

  According to the above configuration, by reducing the cross-sectional area of the electrode tip, even when a spark is generated in both electrode tips on the side of the ground electrode, a spark is generated in both electrode tips on the tip side of the ground electrode. Nearly equivalent combustion can be obtained.

  The invention according to claim 3 is characterized in that the plurality of electrode tips are arranged in a line from the tip end side of the ground electrode to the side portion side of the ground electrode.

  According to the above configuration, the structure can be simplified and the effects of claims 1 and 2 can be further enhanced.

  Hereinafter, a first embodiment of the present invention will be described with reference to FIG. The spark plug 1 of the present invention is applied to an internal combustion engine for automobiles, and is inserted into a screw hole provided in an engine head (not shown) that defines a combustion chamber of the internal combustion engine so as to be fixed. It has become.

  The spark plug 1 has a cylindrical mounting bracket 2 made of a conductive steel material or the like, and the mounting bracket 2 includes a mounting screw portion 2a for fixing to an engine block (not shown). An insulator 3 made of alumina or the like is fixed inside the mounting bracket 2, and the upper end portion of the insulator 3 is provided so as to be exposed from the upper end portion of the mounting bracket 2.

  A center electrode 4 is fixed to the shaft hole of the insulator 3, and the center electrode 4 is insulated and held with respect to the mounting bracket 2. The center electrode 4 is, for example, a cylindrical body made of a metal material having excellent thermal conductivity such as Cu as an inner material and a metal material having excellent heat resistance and corrosion resistance such as a Ni-based alloy as an outer material, and an upper end portion of which is an insulator. 3 is provided so as to be exposed and extend from the upper end portion of 3.

  On the other hand, the ground electrode 5 is welded and fixed to the mounting bracket 2 at its side portion 5a, bent in the middle to form a bent portion 5c, and the tip portion 5b following the bent portion 5c extends so as to face the center electrode 4. .

  A center electrode tip 8 made of a noble metal such as iridium is bonded and fixed to the upper end portion of the center electrode 4. The center electrode tip 8 is composed of a plurality of, in this example, three pin-shaped electrode tips 8a, 8b and 8c. The number may be set to 2 or more as necessary.

  The plurality (three) of center electrode tips 8a, 8b, and 8c are set such that the height (length) of the center electrode tips 8a, 8b, and 8c decreases from the position of the center electrode 4 toward the side portion 5a of the ground electrode 5, and the cross-sectional area thereof. Is also set smaller from the position of the center electrode 4 toward the side portion 5a of the ground electrode 5. Further, as shown in FIG. 1C, a plurality of (three) center electrode chips 8a, 8b, 8c are arranged in a line as the arrangement state goes from the position of the center electrode 4 toward the side portion 5a of the ground electrode 5. Is arranged.

  Similarly to the center electrode tips 8a, 8b, 8c, the tip portion 5b of the ground electrode 5 is also provided with the same number (three) of ground electrode tips 9a, 9b, 9c made of noble metal such as platinum at the opposed positions. Is fixed.

  The heights (lengths) of the ground electrode tips 9a, 9b, and 9c are set to be shorter from the position of the tip portion 5b of the ground electrode 5 toward the side portion 5a, and the cross-sectional area thereof is also the tip of the ground electrode 5 As shown in FIG. 1B, the arrangement state of the plurality (three) of ground electrode chips 9a, 9b, and 9c is reduced to the ground electrode 5 as the distance from the part 5b to the side 5a is increased. Are arranged in a line from the position of the tip 5b toward the side 5a.

  According to the spark plug 1 configured as described above, when the mixed airflow is at a normal speed, the spark F is generated between the center electrode tip 8a having the smallest air gap and the ground electrode 9a. Combustion is obtained.

  When the mixed airflow flows in the direction of the side 5a of the ground electrode 5 at a high speed, the spark G flows in the direction of the side 5a of the ground electrode 5, but the portion close to the side 5a of the ground electrode 5 Since the center electrode tip and the ground electrode tip are arranged, it is possible to prevent a spark from flying to the portion 5a. Further, the cross section of the center electrode tip and the cross section of the ground electrode tip are on the side portion 5a of the ground electrode 5a. Since it becomes smaller as it gets closer, there is less cooling loss of the combustion gas by the electrode, so that deterioration of combustion can be minimized.

  Specific numerical examples of the height, cross-sectional area, and arrangement position of the center electrode tips 8a, 8b, and 8c and the ground electrode tips 9a, 9b, and 9c in the first embodiment will be described. Specific numerical values of height, cross-sectional area, and arrangement position are the same for the center electrode tips 8a, 8b, 8c and the ground electrode tips 9a, 9b, 9c, and are described for the ground electrode tips 9a, 9b, 9c.

  By setting the height (A) of the ground electrode tip 9c closest to the side 5a side of the ground electrode 5 to 0.4 mm or more, deterioration of combustion can be prevented. The height (B) of the ground electrode tip 9a on the distal end side of the ground electrode 5 is 0.6 mm or more to ensure wear resistance (life), and 1.0 mm or less to ensure heat resistance. Further, the step (C) of each ground electrode tip is 0.15 mm or more, and a spark can be preferentially emitted by an electrode tip close to the tip side of the ground electrode 5.

The total cross-sectional area of the ground electrode tips 9a, 9b, 9c is 0.4 mm ² or more to ensure the durability, and the cross-sectional area ratio of the adjacent electrode tips is 3: 2, that is, 9a: 9b: 9c is 9: 6: It is set to 4 and the combustion in the sparks at each electrode tip is equivalent.

  Further, the arrangement position (D) of the ground electrode tips 9a, 9b, 9c, that is, the distance (D) from the side portion 5a of the ground electrode 5 to the electrode tip 9c on the side of the first side 5a is 2 mm or more and the first side portion 5a. Sufficient combustion is ensured in the flying between the center electrode tip 8c on the side and the ground electrode tip 9c.

  Next, second to fifth embodiments of the present invention will be described with reference to FIGS. In the second to fifth embodiments, only differences from the first embodiment will be described.

  In the second embodiment shown in FIG. 2, only the center electrode tips 8a, 8b, and 8c have the same height. The relationship between the cross-sectional area and the arrangement position is the same as that in the first embodiment.

  The third embodiment shown in FIG. 3 is an example in which only the heights of the ground electrode chips 9a, 9b, 9c are the same. The relationship between the cross-sectional area and the arrangement position is the same as that in the first embodiment.

  In the second and third embodiments, since the height of one of the center electrode tip and the ground electrode tip is set to be the same, as in the case described in the first embodiment, the center of the mixed airflow is normal. When the mixed airflow is at a high speed between the electrode tip 8a and the ground electrode tip 9a and the airflow flows from the front end 5b of the ground electrode 5 to the side 5c, the center electrode tip 8b or 8c and the ground electrode tip 9b or 9c can prevent a spark from flowing to 5c and suppress deterioration of combustion.

  In the fourth embodiment shown in FIG. 4, the center electrode tip 8 has a single structure as in the prior art, and the ground electrode tip 9 has the same configuration as in the first embodiment, that is, the height of the ground electrode tips 9a, 9b, 9c. The relationship between the cross-sectional area and the arrangement position is the same as that in the first embodiment.

  In the fifth embodiment shown in FIG. 5, the ground electrode tip 9 has a single structure as in the prior art, and the center electrode tip 8 has the same configuration as in the first embodiment, that is, the height of the center electrode tips 8a, 8b, and 8c. The relationship between the cross-sectional area and the arrangement position is the same as that in the first embodiment.

  In the fourth embodiment, the center electrode tip is set to a conventional single structure, and as in the case of the first embodiment, the center electrode tip 8 and the ground electrode tip 9a when the mixed air flow is at a normal speed. The sparks F can be blown between them to obtain the best combustion, and when the mixed air flow is at a high speed, the ground electrode tip 9b or 9c prevents the spark G from flowing to the side portion 5c of the ground electrode 5 and the deterioration of the combustion. Can be suppressed. In the fifth embodiment, the ground electrode tip is set to a conventional one structure. Similarly to the case described in the first embodiment, the center electrode tip 8a and the ground electrode tip 9 are obtained when the mixed air flow is at a normal speed. The spark F can be blown between them to obtain the best combustion, and when the mixed air flow is at a high speed, the center electrode tip 8b or 8c prevents the spark G from flowing to the side portion 5c of the ground electrode 5 and the deterioration of the combustion. Can be suppressed. In addition, in the fourth and fifth embodiments, since one electrode chip has a single structure, the manufacturing process of the electrode chip is easy and inexpensive.

  The cross-sectional shape of the center electrode tip 8 and the ground electrode tips 9a, 9b, 9c in the first to fifth embodiments is circular, but the cross-sectional shape may be rectangular as shown in FIG. You may make it polygonal, such as a hexagon and an octagon. In this case, as in the case of the first to fifth embodiments, the cross section is set smaller as it goes to the side portion 5a side of the ground electrode 5, and specific numerical values may be set to the values described in the first embodiment. .

  7 and 8 show an example of a manufacturing method in which the ground electrode tips 9a, 9b, and 9c are fixed to the tip portion 5b of the ground electrode 5 by welding.

  In FIG. 7, three ground electrode chips having the same length are produced, and a deep hole is made in the surface facing the center electrode of the tip portion 5 b of the ground electrode 5 as the depth goes to the side portion 5 a side of the ground electrode 5. The ground electrode tips are inserted into the holes, and then the ground electrode tips are fixed to the tip 5b of the ground electrode 5 by welding to form the ground electrode tips 9a, 9b, 9c. In this case, the hole corresponding to the ground electrode tip 9a located at the front end side 5b of the ground electrode 5 does not necessarily need to be formed. Further, the depth of each hole may be set to be the height of the ground electrode tips 9a, 9b, 9c described in the numerical example of the first embodiment. This manufacturing method can also be applied to the case where the center electrode tips 8a, 8b, and 8c are formed.

  In FIG. 8, an E-shaped ground electrode chip body in which three ground electrode chips of the same length are connected on one side is produced, and the connected portion of the ground electrode chip body is the center of the tip 5b of the ground electrode 5 The ground electrode tips 9a, 9b, and 9c are formed by fixing to the electrode facing surface by welding and then cutting the tip side so that each ground electrode tip becomes shorter as it goes to the side 5a side of the ground electrode 5. . This manufacturing method can also be applied when forming the center electrode tips 8a, 8b, and 8c. According to this manufacturing method, only one welding is required, and the manufacturing time can be shortened.

1 shows a first embodiment of a spark plug according to the present invention, where (a) is a front view of the main part, (b) is a bottom view of the ground electrode 5 part, and (c) is a top view of the center electrode 4 part. . It is a principal part front view which shows 2nd Embodiment of the spark plug which becomes this invention. It is a principal part front view which shows 3rd Embodiment of the spark plug which becomes this invention. It is a principal part front view which shows 4th Embodiment of the spark plug which becomes this invention. It is a principal part front view which shows 5th Embodiment of the spark plug which becomes this invention. It is a bottom view which shows the other example of ground electrode chip | tip 9a, 9b, 9c. It is a figure which uses for the manufacturing method of joining fixation to the ground electrode 5 of the ground electrode chip | tip 9a, 9b, 9c. It is another figure with which it uses for the manufacturing method of joining fixation to the ground electrode 5 of the ground electrode chip | tip 9a, 9b, 9c. It is a principal part front view of the spark plug with which it uses for the conventional description.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Spark plug 2 Mounting bracket 3 Insulator 4 Center electrode 5 Ground electrode 5a, 5b, 5c The side part, front-end | tip part, bending part of the ground electrode 5 8 Center electrode chip | tip 8a, 8b, 8c Each center which comprises the center electrode chip | tip 8 Electrode chip 9 Ground electrode chip 9a, 9b, 9c Each ground electrode chip E, F, G that constitutes the ground electrode chip 9

Claims (3)

A spark plug in which a center electrode tip is fixed to the center electrode tip and a ground electrode tip is fixed to the ground electrode facing the center electrode tip,
The center electrode chip or / and the ground electrode chip is composed of a plurality of electrode chips,
The plurality of electrode tips are arranged from the front end side of the ground electrode to the side portion side of the ground electrode, and the length of the plurality of electrode tips from the front end side of the ground electrode is the ground electrode. The spark plug is characterized by being set shorter as it goes to the side.   2. The spark plug according to claim 1, wherein a cross-sectional area of each of the plurality of electrode tips is set to be smaller from a tip end side of the ground electrode toward a side portion side of the ground electrode. 3. The spark plug according to claim 1, wherein the plurality of electrode tips are arranged in a line from a tip end side of the ground electrode to a side portion side of the ground electrode.

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