JP2021124102A

JP2021124102A - cylinder head

Info

Publication number: JP2021124102A
Application number: JP2020020055A
Authority: JP
Inventors: 透大下; Toru Oshita; 亨允逆井; Kosuke SAKASAI
Original assignee: Honda Motor Co Ltd
Current assignee: Honda Motor Co Ltd
Priority date: 2020-02-07
Filing date: 2020-02-07
Publication date: 2021-08-30
Anticipated expiration: 2040-02-07
Also published as: JP7136820B2

Abstract

To improve cooling performance around an ignition plug by a structure that is comparatively easily manufactured.SOLUTION: A cylinder head 1 equipped with an attaching hole 12 of an ignition plug 101 and a cooling water passage, includes a communication hole 11 that opens to a surface of the cylinder head 1 and communicates with the cooling water passage, and a cap member 20 that blocks the communication hole 11. The cooling water passage includes a plug cooling passage portion patting by the periphery of the attaching hole 12. The communication hole 11 communicates with the plug cooling passage portion. The cap member 20 has a shaft portion that enter the plug cooling passage portion and decreases a channel cross-sectional area of the plug cooling passage portion. The plug cooling passage portion has a first inner wall surface on the attaching hole 12 side and a second inner wall surface on the opposite side, and forms a cooling water passage 14b between a side surface of the shaft portion and the first inner wall surface.SELECTED DRAWING: Figure 3

Description

本発明はエンジンのシリンダヘッドに関する。 The present invention relates to an engine cylinder head.

水冷式エンジンのシリンダヘッドには、内部に冷却水の通路（ウォータジャケット）が形成されており、冷却水を循環することで高温部位を冷却している。高温部位としては、例えば、排気ポート周辺や点火プラグ周辺が挙げられる。特許文献１には、重点的に冷却する部位において、冷却水の通路の流路断面積を小さくすることで流速を速め、冷却性能を向上する技術が提案されている。 A cooling water passage (water jacket) is formed inside the cylinder head of a water-cooled engine, and the high-temperature portion is cooled by circulating the cooling water. Examples of the high temperature portion include the vicinity of the exhaust port and the vicinity of the spark plug. Patent Document 1 proposes a technique for increasing the flow velocity and improving the cooling performance by reducing the cross-sectional area of the flow path of the cooling water passage in the portion to be cooled intensively.

特開２０１９−１５２３８号公報Japanese Unexamined Patent Publication No. 2019-15238

しかし、シリンダヘッドの内部に、その材料自体によって狭い通路を形成することは容易ではない。シリンダヘッドは一般に鋳造により製造されるが、狭い通路を砂型（中子）で形成しようとすると、砂型の強度上の問題が生じる。 However, it is not easy to form a narrow passage inside the cylinder head by the material itself. Cylinder heads are generally manufactured by casting, but attempting to form a narrow passage with a sand mold (core) causes problems with the strength of the sand mold.

本発明の目的は、砂型の断面積を大きくとることで砂型の強度を確保しつつ、点火プラグ周辺の流路断面積を小さくすることで冷却性能を向上することにある。 An object of the present invention is to improve the cooling performance by reducing the cross-sectional area of the flow path around the spark plug while ensuring the strength of the sand mold by increasing the cross-sectional area of the sand mold.

本発明によれば、
点火プラグの取付孔（１２）と、
冷却水通路（１４）と、
を備えたシリンダヘッド（１）において、
前記冷却水通路（１４）から前記シリンダヘッド（１）の表面に延び、該表面に開口した連通孔（１１）と、
前記連通孔（１１）を閉塞するキャップ部材（２０）と、を備え、
前記冷却水通路（１４）は、前記取付孔（１２）の周囲を通るプラグ冷却通路部（１４ａ）を含み、
前記連通孔（１１）は、前記プラグ冷却通路部（１４ａ）に連通し、
前記キャップ部材（２０）は、
前記プラグ冷却通路部（１４ａ）に突出する軸部（２２）を有し、
前記プラグ冷却通路部（１４ａ）は、前記取付孔（１２）の側の第一の内壁面（１ａ）と、反対側の第二の内壁面（１ｃ）とを有し、
前記軸部の側面（２４ａ）と、前記第一の内壁面（１ａ）との間に冷却水の絞り通路（１４ｂ）が形成される、
ことを特徴とするシリンダヘッドが提供される。 According to the present invention
Spark plug mounting holes (12) and
Cooling water passage (14) and
In the cylinder head (1) provided with
A communication hole (11) extending from the cooling water passage (14) to the surface of the cylinder head (1) and opening in the surface,
A cap member (20) that closes the communication hole (11) is provided.
The cooling water passage (14) includes a plug cooling passage portion (14a) passing around the mounting hole (12).
The communication hole (11) communicates with the plug cooling passage portion (14a), and the communication hole (11) communicates with the plug cooling passage portion (14a).
The cap member (20) is
It has a shaft portion (22) protruding from the plug cooling passage portion (14a), and has a shaft portion (22).
The plug cooling passage portion (14a) has a first inner wall surface (1a) on the side of the mounting hole (12) and a second inner wall surface (1c) on the opposite side.
A cooling water throttle passage (14b) is formed between the side surface (24a) of the shaft portion and the first inner wall surface (1a).
Cylinder heads are provided.

本発明によれば、砂型の断面積を大きくとることで砂型の強度を確保しつつ、点火プラグ周辺の流路断面積を小さくすることで冷却性能を向上することができる。 According to the present invention, it is possible to improve the cooling performance by reducing the cross-sectional area of the flow path around the spark plug while ensuring the strength of the sand mold by increasing the cross-sectional area of the sand mold.

本発明の一実施形態に係るシリンダヘッド。A cylinder head according to an embodiment of the present invention. 図１のシリンダヘッドの平面図。The plan view of the cylinder head of FIG. 図２のキャップ部材中心を通るＡ−Ａ線断面図。FIG. 2 is a cross-sectional view taken along the line AA passing through the center of the cap member of FIG. 冷却水通路等を示す図１のシリンダヘッドの透視図。A perspective view of the cylinder head of FIG. 1 showing a cooling water passage and the like. 図３の軸部を通り、シリンダ軸線に直交するＢ−Ｂ線断面図。BB line cross-sectional view which passes through the shaft portion of FIG. 3 and is orthogonal to the cylinder axis. 冷却水通路の概略図。Schematic diagram of the cooling water passage. 図３の部分拡大図。A partially enlarged view of FIG. （Ａ）〜（Ｃ）は連通孔の加工工程を示す断面図。(A) to (C) are cross-sectional views showing a processing process of a communication hole.

以下、添付図面を参照して実施形態を詳しく説明する。尚、以下の実施形態は特許請求の範囲に係る発明を限定するものではなく、また実施形態で説明されている特徴の組み合わせの全てが発明に必須のものとは限らない。実施形態で説明されている複数の特徴のうち二つ以上の特徴が任意に組み合わされてもよい。また、同一若しくは同様の構成には同一の参照番号を付し、重複した説明は省略する。 Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. It should be noted that the following embodiments do not limit the invention according to the claims, and not all combinations of features described in the embodiments are essential to the invention. Two or more of the plurality of features described in the embodiments may be arbitrarily combined. In addition, the same or similar configuration will be given the same reference number, and duplicated explanations will be omitted.

＜シリンダヘッドの概要＞
図１は本発明の一実施形態に係るシリンダヘッド１の外観図である。図２は点火プラグ１０１及びキャップ部材２０を取り付けたシリンダヘッド１の平面図（気筒軸方向に見た図）である。図３は図２のＡ−Ａ線断面図である。 <Overview of cylinder head>
FIG. 1 is an external view of a cylinder head 1 according to an embodiment of the present invention. FIG. 2 is a plan view (a view in the cylinder axial direction) of the cylinder head 1 to which the spark plug 101 and the cap member 20 are attached. FIG. 3 is a cross-sectional view taken along the line AA of FIG.

本実施形態のシリンダヘッド１は、水冷単気筒４サイクルエンジンを構成し、ＳＯＨＣ式の動弁機構が設けられるシリンダヘッドである。しかし、本発明は他気筒エンジンや他の形式の動弁機構を備えるシリンダヘッドにも適用可能である。 The cylinder head 1 of the present embodiment is a cylinder head that constitutes a water-cooled single-cylinder 4-cycle engine and is provided with a SOHC type valve operating mechanism. However, the present invention is also applicable to other cylinder engines and cylinder heads having other types of valve operating mechanisms.

シリンダヘッド１は、その下面に燃焼室２を備える。燃焼室２には吸気バルブ用のバルブシート３と、排気バルブ用のバルブシート４とがそれぞれ２つ形成されている。シリンダヘッド１には、また、吸気バルブのバルブステムが通過するガイド孔７と排気バルブのバルブステムが通過するガイド孔８とが２つ形成されている。シリンダヘッド１の一側部には、カムスプロケットが配置される空洞部５が形成されており、他側部には点火プラグ１０１が取り付けられる取付孔１２が形成されている。シリンダヘッド１の上部には、カムシャフトを支持する支持孔６や、吸気側、排気側の各ロッカシャフトを支持する支持孔９が形成されている。 The cylinder head 1 is provided with a combustion chamber 2 on the lower surface thereof. Two valve seats 3 for an intake valve and two valve seats 4 for an exhaust valve are formed in the combustion chamber 2. The cylinder head 1 is also formed with two guide holes 7 through which the valve stem of the intake valve passes and a guide hole 8 through which the valve stem of the exhaust valve passes. A cavity 5 on which a cam sprocket is arranged is formed on one side of the cylinder head 1, and a mounting hole 12 on which the spark plug 101 is mounted is formed on the other side. A support hole 6 for supporting the camshaft and a support hole 9 for supporting the intake side and exhaust side rocker shafts are formed in the upper part of the cylinder head 1.

シリンダヘッド１には、その表面に開口した連通孔１１が形成されている。連通孔１１はシリンダヘッド１の上面中央部に形成されており、シリンダヘッド１の平面視で、２つのガイド孔７と、２つのガイド孔８との間に位置している。連通孔１１はキャップ部材２０で閉塞される。 The cylinder head 1 is formed with a communication hole 11 opened on the surface thereof. The communication hole 11 is formed in the center of the upper surface of the cylinder head 1 and is located between the two guide holes 7 and the two guide holes 8 in the plan view of the cylinder head 1. The communication hole 11 is closed by the cap member 20.

＜冷却水通路の構造＞
図３〜図６を参照して、シリンダヘッド１の冷却水通路の構造について説明する。図４は冷却水通路１４、キャップ部材２０及び点火プラグ１０を太線で表示し、シリンダヘッド１の輪郭を細線で示した透過図である。図５は図３のＢ−Ｂ線断面図であり、破線矢印は冷却水の流れ方向を示している。図６は冷却水通路１４の概略図（平面視）である。 <Structure of cooling water passage>
The structure of the cooling water passage of the cylinder head 1 will be described with reference to FIGS. 3 to 6. FIG. 4 is a transmission diagram in which the cooling water passage 14, the cap member 20, and the spark plug 10 are indicated by thick lines, and the outline of the cylinder head 1 is indicated by thin lines. FIG. 5 is a cross-sectional view taken along the line BB of FIG. 3, and the broken line arrow indicates the flow direction of the cooling water. FIG. 6 is a schematic view (plan view) of the cooling water passage 14.

冷却水通路１４は、シリンダヘッド１の内部に形成されており、主に図６に示すように、シリンダブロック側から、排気バルブの側において冷却水が供給され、２方向に分岐した後、吸気バルブの側において合流して、取付部１３に取り付けられる配管部材から排出される。 The cooling water passage 14 is formed inside the cylinder head 1, and as shown mainly in FIG. 6, cooling water is supplied from the cylinder block side to the exhaust valve side, and after branching in two directions, intake water is taken. It merges on the valve side and is discharged from the piping member attached to the attachment portion 13.

冷却水通路１４は、点火プラグ１０の取付孔１２の周囲を通るプラグ冷却通路部１４ａを含む。プラグ冷却通路部１４ａを冷却水が流れることで、点火プラグ１０１に対する冷却性能を向上する。シリンダヘッド１の内部には、空洞部５の側から取付孔１２の側へ延びるリブ１ｂが形成されており、平面視でプラグ冷却通路部１４ａはリブ１ｂを囲むようにＵ字型に形成されている。リブ１ｂを形成してその周囲にプラグ冷却通路部１４ａを形成したことで、点火プラグ１０１の近傍を冷却水が流れ易くなり、点火プラグ１０１に対する冷却性能を向上できる。連通孔１１は、冷却水通路１４からシリンダヘッド１の表面に延び、該表面に開口した孔であり、特に、プラグ冷却通路部１４ａに連通している。 The cooling water passage 14 includes a plug cooling passage portion 14a that passes around the mounting hole 12 of the spark plug 10. Cooling water flows through the plug cooling passage portion 14a to improve the cooling performance of the spark plug 101. A rib 1b extending from the cavity 5 side to the mounting hole 12 side is formed inside the cylinder head 1, and the plug cooling passage portion 14a is formed in a U shape so as to surround the rib 1b in a plan view. ing. By forming the rib 1b and forming the plug cooling passage portion 14a around the rib 1b, the cooling water can easily flow in the vicinity of the spark plug 101, and the cooling performance for the spark plug 101 can be improved. The communication hole 11 is a hole that extends from the cooling water passage 14 to the surface of the cylinder head 1 and opens in the surface, and particularly communicates with the plug cooling passage portion 14a.

キャップ部材２０は、連通孔１１を閉塞して連通孔１１から冷却水が漏れることを防止するだけでなく、プラグ冷却通路部１４ａを部分的に塞いでその流路断面積を小さくする部材である。図３〜図６に加えて図７を参照する。図７は図３のキャップ部材２０の周辺の拡大図であるが、キャップ部材２０は断面図ではない。 The cap member 20 is a member that not only closes the communication hole 11 to prevent cooling water from leaking from the communication hole 11, but also partially closes the plug cooling passage portion 14a to reduce the cross-sectional area of the passage. .. See FIG. 7 in addition to FIGS. 3-6. FIG. 7 is an enlarged view of the periphery of the cap member 20 of FIG. 3, but the cap member 20 is not a cross-sectional view.

キャップ部材２０は、頭部２１と軸部２２とを有する。本実施形態の場合、頭部２１、軸部２２はいずれも断面円形の円柱体であるが、断面角形の角柱体等、他の断面形状を有する部材であってもよい。頭部２１には、六角レンチなどの工具を差し込んで、連通孔１１に対するキャプ部材２０の閉塞作業（取付作業）に有利な凹部２０ａが形成されている。 The cap member 20 has a head portion 21 and a shaft portion 22. In the case of the present embodiment, the head portion 21 and the shaft portion 22 are both cylindrical bodies having a circular cross section, but members having other cross-sectional shapes such as a prismatic body having a square cross section may be used. A recess 20a, which is advantageous for closing (attaching) the cap member 20 to the communication hole 11, is formed in the head 21 by inserting a tool such as a hexagon wrench.

本実施形態の連通孔１１はねじ孔である。キャップ部材２０の軸部２２は、頭部２１側のねじ部２３と、ねじ部２３から延びる通路形成部２４とを有する。キャップ部材２０は、ねじ部２３が連通孔１１と螺合することで連通孔１１に取り付けられ、頭部２１と、連通孔１１の周囲の座面１１ａとが密接することで、冷却水の漏出を防止する。頭部２１と座面１１ａとの間にはシール部材が介在してもよい。 The communication hole 11 of this embodiment is a screw hole. The shaft portion 22 of the cap member 20 has a screw portion 23 on the head 21 side and a passage forming portion 24 extending from the screw portion 23. The cap member 20 is attached to the communication hole 11 by screwing the screw portion 23 into the communication hole 11, and the head 21 and the seating surface 11a around the communication hole 11 come into close contact with each other to leak cooling water. To prevent. A sealing member may be interposed between the head 21 and the seat surface 11a.

なお、軸部２２はその全体がねじ部であってもよい。しかし、軸部２２が通路の形成に特化した通路形成部２４を有することで、意図する通路構造を得られやすい。また、連通孔１１に対するキャップ部材３０の固定構造は、ねじ構造に限られず、圧入、接着等、他の固定構造であってもよい。 The shaft portion 22 may be a screw portion as a whole. However, since the shaft portion 22 has the passage forming portion 24 specialized for forming the passage, it is easy to obtain the intended passage structure. Further, the fixing structure of the cap member 30 to the communication hole 11 is not limited to the screw structure, and may be another fixing structure such as press fitting or adhesion.

軸部２２は取付孔１２の近傍に位置しており、通路形成部２４は、プラグ冷却通路部１４ａに突出するように進入している。通路形成部２４の存在によってプラグ冷却通路部１４ａの通路幅がＷ０からＷ１へ狭くなる。通路幅は、内壁面１ａと内壁面１ｃとの間の距離である。内壁面１ａは取付孔１２の側の面（取付孔１２を形成する壁部側面）であり、内壁面１ｂは反対側の面（リブ１ｂの側面１ｃ）である。通路形成部２４の側面（周面）のうち、内壁面１ａと対向する側面２３ａと内壁面１ａとの間に冷却水の絞り通路１４ｂが形成される。通路形成部２４が存在することで、プラグ冷却通路部１４ａは、通路形成部２４が無い場合に比べてその流路断面積が大幅に削減された絞り通路１４ｂとなる。これにより、絞り通路１４ｂは、冷却水の流速を速める絞り部として機能し、点火プラグ１０１に対する冷却性能を更に向上できる。 The shaft portion 22 is located in the vicinity of the mounting hole 12, and the passage forming portion 24 enters the plug cooling passage portion 14a so as to project from the plug cooling passage portion 14a. Due to the presence of the passage forming portion 24, the passage width of the plug cooling passage portion 14a is narrowed from W0 to W1. The passage width is the distance between the inner wall surface 1a and the inner wall surface 1c. The inner wall surface 1a is a surface on the side of the mounting hole 12 (the side surface of the wall portion forming the mounting hole 12), and the inner wall surface 1b is the surface on the opposite side (the side surface 1c of the rib 1b). Of the side surface (peripheral surface) of the passage forming portion 24, the cooling water drawing passage 14b is formed between the side surface 23a facing the inner wall surface 1a and the inner wall surface 1a. Due to the presence of the passage forming portion 24, the plug cooling passage portion 14a becomes a throttle passage 14b in which the cross-sectional area of the passage is significantly reduced as compared with the case where the passage forming portion 24 is not present. As a result, the throttle passage 14b functions as a throttle portion for accelerating the flow velocity of the cooling water, and the cooling performance for the spark plug 101 can be further improved.

通路形成部２４は、プラグ冷却通路部１４ａの底壁面１ｄまで延設されており、通路形成部２４と底壁面１ｄとの間に冷却水が逃げずに、絞り通路１４ｂを通り冷却水が多くなるように構成されている。通路形成部２４は底壁面１ｄに当接してもよいが、そうすると、頭部２１と、座面１１ａとが密接度合い確保の為に高精度な寸法管理が必要となり、コストアップに繋がる。このため、本実施形態では、通路形成部２４と底壁面１ｄとの間に微小隙間Ｇ１を形成している。微小隙間Ｇ１は、例えば、０．５ｍｍ〜２ｍｍの範囲内の隙間である。通路形成部２４の先端部２４ｃと、底壁面１ｄとは、互いに沿う形状を有している。これにより微小隙間Ｇ１を均一かつ小さくすることができる。先端部２４ｃは円錐形状を有しており、底壁面１ｄも円錐の凹部形状を有している。先端部２４ｃ、底壁面１ｄは平坦面であってもよい。 The passage forming portion 24 extends to the bottom wall surface 1d of the plug cooling passage portion 14a, and the cooling water does not escape between the passage forming portion 24 and the bottom wall surface 1d, and a large amount of cooling water passes through the throttle passage 14b. It is configured to be. The passage forming portion 24 may come into contact with the bottom wall surface 1d, but if this is done, highly accurate dimensional control is required to ensure the degree of close contact between the head 21 and the seat surface 11a, which leads to an increase in cost. Therefore, in the present embodiment, a minute gap G1 is formed between the passage forming portion 24 and the bottom wall surface 1d. The minute gap G1 is, for example, a gap in the range of 0.5 mm to 2 mm. The tip portion 24c of the passage forming portion 24 and the bottom wall surface 1d have a shape along each other. As a result, the minute gap G1 can be made uniform and small. The tip portion 24c has a conical shape, and the bottom wall surface 1d also has a conical concave shape. The tip portion 24c and the bottom wall surface 1d may be flat surfaces.

通路形成部２４の側面（周面）のうち、内壁面１ｃと対向する側面２３ｂと、内壁面１ｃとの間にも微小隙間Ｇ２を形成している。側面２３ｂと内壁面１ｃとは互いに当接してもよいが、そうするとキャップ部材２０を連通孔１１に装着する際、キャップ部材２０をプラグ冷却通路部１４ａに挿入しづらくなる場合がある。そこで本実施形態では、微小隙間Ｇ２を形成している。微小隙間Ｇ２は、例えば、０．５ｍｍ〜２ｍｍの範囲内の隙間である。側面２３ｂと内側面１ｃとは、互いに沿う形状を有しており、本実施形態の場合、円弧面である。これにより微小隙間Ｇ２を均一かつ小さくすることができる。 Of the side surfaces (peripheral surfaces) of the passage forming portion 24, a minute gap G2 is also formed between the side surface 23b facing the inner wall surface 1c and the inner wall surface 1c. The side surface 23b and the inner wall surface 1c may come into contact with each other, but if this is done, it may be difficult to insert the cap member 20 into the plug cooling passage portion 14a when the cap member 20 is attached to the communication hole 11. Therefore, in the present embodiment, a minute gap G2 is formed. The minute gap G2 is, for example, a gap in the range of 0.5 mm to 2 mm. The side surface 23b and the inner side surface 1c have shapes along each other, and in the case of the present embodiment, they are arcuate surfaces. As a result, the minute gap G2 can be made uniform and small.

＜連通孔の加工＞
連通孔１１の加工例について図８（Ａ）〜図８（Ｃ）を参照して説明する。図８（Ａ）〜図８（Ｃ）は連通孔１１の加工の各段階を示すその周辺の断面図であり、図３や図７と同じ切断面の断面図である。 <Processing of communication holes>
An example of processing the communication hole 11 will be described with reference to FIGS. 8 (A) to 8 (C). 8 (A) to 8 (C) are cross-sectional views of the periphery showing each stage of processing of the communication hole 11, and is a cross-sectional view of the same cut surface as in FIGS. 3 and 7.

図８（Ａ）は、シリンダヘッド１の鋳造後の段階を示している。連通孔１１は、中子砂型の砂抜き孔１１Ａを利用して形成される。図８（Ｂ）は砂抜き孔１１Ａを機械加工してキリ孔１１Ｂを形成した段階を示す。機械加工に用いるドリルにより、底壁面１ｄも形成する。機械加工により、内壁面１ｃと底壁面１ｄの精度を向上でき、図７に示したい隙間Ｇ１、Ｇ２をより狭くすることができる。図８（Ｃ）は、キリ孔１１Ｂにねじ切り加工を施し、ねじ部１１ｂを形成した段階を示す。これにより連通孔１１が形成される。 FIG. 8A shows the stage after casting the cylinder head 1. The communication hole 11 is formed by utilizing the core sand type sand removal hole 11A. FIG. 8B shows a stage in which the sand removal hole 11A is machined to form the drill hole 11B. The bottom wall surface 1d is also formed by the drill used for machining. By machining, the accuracy of the inner wall surface 1c and the bottom wall surface 1d can be improved, and the gaps G1 and G2 to be shown in FIG. 7 can be made narrower. FIG. 8C shows a stage in which the drilled hole 11B is threaded to form the threaded portion 11b. As a result, the communication hole 11 is formed.

連通孔１１が形成された段階で、プラグ冷却通路部１４ａの通路幅は、鋳造段階と概ね同じである（幅Ｗ０）。鋳造段階では、プラグ冷却通路部１４ａの幅が比較的広いため、中子の強度がプラグ冷却通路部１４ａで大きく低下することはない。そして、図８（Ｃ）の連通孔１１にキャップ部材２０を装着することで、図７に示す狭い絞り通路１４ｂを形成できる。図８（Ｂ）のうち、縦断面積Ｓ１及びＳ２が概ね、中子砂型の縦断面積に相当し、このうち、縦断面積Ｓ１がキャップ部材２０で塞がれ、縦断面積Ｓ２が絞り通路１４ｂとして残る。鋳造により最初から絞り通路１４ｂを形成するよりも砂型の製作が容易になる。つまり、砂型の断面積を大きくとることで砂型の強度を確保しつつ、点火プラグ１０１周辺の流路断面積を小さくすることで冷却性能を向上することができる。 At the stage where the communication hole 11 is formed, the passage width of the plug cooling passage portion 14a is substantially the same as that at the casting stage (width W0). At the casting stage, since the width of the plug cooling passage portion 14a is relatively wide, the strength of the core does not significantly decrease in the plug cooling passage portion 14a. Then, by mounting the cap member 20 in the communication hole 11 of FIG. 8C, the narrow throttle passage 14b shown in FIG. 7 can be formed. In FIG. 8B, the vertical cross-sectional areas S1 and S2 roughly correspond to the core sand type vertical cross-sectional areas, of which the vertical cross-sectional area S1 is closed by the cap member 20 and the vertical cross-sectional area S2 remains as the throttle passage 14b. .. It is easier to manufacture a sand mold than to form a drawing passage 14b from the beginning by casting. That is, the cooling performance can be improved by reducing the cross-sectional area of the flow path around the spark plug 101 while ensuring the strength of the sand mold by increasing the cross-sectional area of the sand mold.

＜実施形態のまとめ＞
上記実施形態は、以下のシリンダヘッドを少なくとも開示する。 <Summary of Embodiment>
The above embodiment discloses at least the following cylinder heads.

１．上記実施形態のシリンダヘッド(1)は、
点火プラグの取付孔（１２）と、
冷却水通路（１４）と、
を備えたシリンダヘッド（１）において、
前記冷却水通路（１４）から前記シリンダヘッド（１）の表面に延び、該表面に開口した連通孔（１１）と、
前記連通孔（１１）を閉塞するキャップ部材（２０）と、を備え、
前記冷却水通路（１４）は、前記取付孔（１２）の周囲を通るプラグ冷却通路部（１４ａ）を含み、
前記連通孔（１１）は、前記プラグ冷却通路部（１４ａ）に連通し、
前記キャップ部材（２０）は、
前記プラグ冷却通路部（１４ａ）に突出する軸部（２２）を有し、
前記プラグ冷却通路部（１４ａ）は、前記取付孔（１２）の側の第一の内壁面（１ａ）と、反対側の第二の内壁面（１ｃ）とを有し、
前記軸部の側面（２４ａ）と、前記第一の内壁面（１ａ）との間に冷却水の絞り通路（１４ｂ）が形成される。
この実施形態によれば、砂型の断面積を大きくとることで砂型の強度を確保しつつ、点火プラグ周辺の流路断面積を小さくすることで冷却性能を向上することができる。 1. 1. The cylinder head (1) of the above embodiment is
Spark plug mounting holes (12) and
Cooling water passage (14) and
In the cylinder head (1) provided with
A communication hole (11) extending from the cooling water passage (14) to the surface of the cylinder head (1) and opening in the surface,
A cap member (20) that closes the communication hole (11) is provided.
The cooling water passage (14) includes a plug cooling passage portion (14a) passing around the mounting hole (12).
The communication hole (11) communicates with the plug cooling passage portion (14a), and the communication hole (11) communicates with the plug cooling passage portion (14a).
The cap member (20) is
It has a shaft portion (22) protruding from the plug cooling passage portion (14a), and has a shaft portion (22).
The plug cooling passage portion (14a) has a first inner wall surface (1a) on the side of the mounting hole (12) and a second inner wall surface (1c) on the opposite side.
A cooling water throttle passage (14b) is formed between the side surface (24a) of the shaft portion and the first inner wall surface (1a).
According to this embodiment, the cooling performance can be improved by reducing the cross-sectional area of the flow path around the spark plug while ensuring the strength of the sand mold by increasing the cross-sectional area of the sand mold.

２．上記実施形態では、
前記軸部(22)は、前記連通孔から前記プラグ冷却通路部の底壁面(1d)まで延設されている。
この実施形態によれば、前記軸部と前記底壁面との隙間を小さくして、流路断面積をより小さくすることができる。 2. In the above embodiment
The shaft portion (22) extends from the communication hole to the bottom wall surface (1d) of the plug cooling passage portion.
According to this embodiment, the gap between the shaft portion and the bottom wall surface can be reduced to make the flow path cross-sectional area smaller.

３．上記実施形態では、
前記底壁面（１ｄ）は、前記軸部（２２）の先端（２４ｃ）に沿う形状の部分を有している。
この実施形態によれば、前記軸部と前記底壁面との隙間がより小さくなり、流路断面積をより小さくすることができる。 3. 3. In the above embodiment
The bottom wall surface (1d) has a portion having a shape along the tip end (24c) of the shaft portion (22).
According to this embodiment, the gap between the shaft portion and the bottom wall surface becomes smaller, and the cross-sectional area of the flow path can be made smaller.

４．上記実施形態では、
前記底壁面（１ｄ）の前記部分は、機械加工により形成された面である。
この実施形態によれば、前記底壁面の前記部分の形状精度を向上し、前記底壁面と前記軸部の先端との隙間を最小限に抑えることができる。この結果、流路断面積をより小さくすることができる。 4. In the above embodiment
The portion of the bottom wall surface (1d) is a surface formed by machining.
According to this embodiment, the shape accuracy of the portion of the bottom wall surface can be improved, and the gap between the bottom wall surface and the tip of the shaft portion can be minimized. As a result, the cross-sectional area of the flow path can be made smaller.

５．上記実施形態では、
前記第二の内壁面（１ｃ）は、前記軸部（２２）の側面（２４ｂ）に沿う形状の部分を有している。
この実施形態によれば、前記軸部と前記第二の内壁面との隙間がより小さくなり、流路断面積をより小さくすることができる。 5. In the above embodiment
The second inner wall surface (1c) has a portion having a shape along the side surface (24b) of the shaft portion (22).
According to this embodiment, the gap between the shaft portion and the second inner wall surface becomes smaller, and the cross-sectional area of the flow path can be made smaller.

６．上記実施形態では、
前記第二の内壁面（１ｃ）の前記部分は、機械加工により形成された面である。
この実施形態によれば、前記第二の内壁面の前記部分の形状精度を向上し、前記第二の壁面と前記軸部の側面との隙間を最小限に抑えることができる。 6. In the above embodiment
The portion of the second inner wall surface (1c) is a surface formed by machining.
According to this embodiment, the shape accuracy of the portion of the second inner wall surface can be improved, and the gap between the second wall surface and the side surface of the shaft portion can be minimized.

７．上記実施形態では、
前記キャップ部材は、前記シリンダヘッドの外部に露出した頭部（２１）を有し、前記軸部は前記頭部から延設されており、
前記連通孔（１１）は、ねじ孔であり、
前記軸部は、
前記ねじ孔（１１）と螺合する前記頭部側のねじ部（２３）と、
前記ねじ部（２３）から延び、前記プラグ冷却通路部に突出する通路形成部（２４）と、を有する。
この実施形態によれば、ねじ構造によって前記キャップ部材を比較的簡易に前記連通孔に固定することができる。 7. In the above embodiment
The cap member has a head portion (21) exposed to the outside of the cylinder head, and the shaft portion extends from the head portion.
The communication hole (11) is a screw hole.
The shaft portion
The screw portion (23) on the head side to be screwed into the screw hole (11),
It has a passage forming portion (24) extending from the threaded portion (23) and projecting into the plug cooling passage portion.
According to this embodiment, the cap member can be relatively easily fixed to the communication hole by the screw structure.

以上、発明の実施形態について説明したが、発明は上記の実施形態に制限されるものではなく、発明の要旨の範囲内で、種々の変形・変更が可能である。 Although the embodiments of the invention have been described above, the invention is not limited to the above-described embodiments, and various modifications and changes can be made within the scope of the gist of the invention.

例えば、上記の実施形態では図３に示す断面図において、点火プラグ１０１の軸心と、キャップ部材２０の軸心が同一平面に存在するが、両者の配置はこれに限られない。例えば、点火プラグ１０１側からの側面視において、点火プラグ１０１とキャップ部材２０とが部分的に重なっている構成であってもよい。 For example, in the above embodiment, in the cross-sectional view shown in FIG. 3, the axis of the spark plug 101 and the axis of the cap member 20 are present on the same plane, but the arrangement of both is not limited to this. For example, the spark plug 101 and the cap member 20 may be partially overlapped when viewed from the side of the spark plug 101.

１シリンダヘッド、１１連通孔、１２取付孔、１４ａプラグ冷却通路部、１４ｂ絞り通路、２０キャップ部材、１０１点火プラグ 1 Cylinder head, 11 communication holes, 12 mounting holes, 14a plug cooling passage, 14b throttle passage, 20 cap members, 101 spark plugs

Claims

Spark plug mounting holes (12) and
Cooling water passage (14) and
In the cylinder head (1) provided with
A communication hole (11) extending from the cooling water passage (14) to the surface of the cylinder head (1) and opening in the surface,
A cap member (20) that closes the communication hole (11) is provided.
The cooling water passage (14) includes a plug cooling passage portion (14a) passing around the mounting hole (12).
The communication hole (11) communicates with the plug cooling passage portion (14a), and the communication hole (11) communicates with the plug cooling passage portion (14a).
The cap member (20) is
It has a shaft portion (22) protruding from the plug cooling passage portion (14a), and has a shaft portion (22).
The plug cooling passage portion (14a) has a first inner wall surface (1a) on the side of the mounting hole (12) and a second inner wall surface (1c) on the opposite side.
A cooling water throttle passage (14b) is formed between the side surface (24a) of the shaft portion and the first inner wall surface (1a).
Cylinder head characterized by that.

The cylinder head (1) according to claim 1.
The shaft portion (22) extends from the communication hole (11) to the bottom wall surface (1d) of the plug cooling passage portion (14a).
Cylinder head characterized by that.

The cylinder head (1) according to claim 2.
The bottom wall surface (1d) has a portion having a shape along the tip end (24c) of the shaft portion (22).
Cylinder head characterized by that.

The cylinder head (1) according to claim 3.
The portion of the bottom wall surface (1d) is a surface formed by machining.
Cylinder head characterized by that.

The cylinder head (1) according to any one of claims 1 to 4.
The second inner wall surface (1c) has a portion having a shape along the side surface (24b) of the shaft portion (22).
Cylinder head characterized by that.

The cylinder head according to claim 5.
The portion of the second inner wall surface (1c) is a surface formed by machining.
Cylinder head characterized by that.

The cylinder head according to claim 1.
The cap member has a head portion (21) exposed to the outside of the cylinder head, and the shaft portion extends from the head portion.
The communication hole (11) is a screw hole.
The shaft portion
The screw portion (23) on the head side to be screwed into the screw hole (11),
It has a passage forming portion (24) extending from the threaded portion (23) and projecting into the plug cooling passage portion.
Cylinder head characterized by that.