JP3656060B2

JP3656060B2 - Siamese cylinder cooling system

Info

Publication number: JP3656060B2
Application number: JP2002142335A
Authority: JP
Inventors: 正寛明田; 一利岡本; 保一鎌田; 章早谷; 政次湯川; 理吉井; 和良森岡
Original assignee: Kubota Corp
Current assignee: Kubota Corp
Priority date: 1995-03-20
Filing date: 2002-05-17
Publication date: 2005-06-02
Anticipated expiration: 2015-12-26
Also published as: JP2003013798A

Description

【０００１】
【産業上の利用分野】
本発明は、多気筒エンジンのサイアミーズシリンダの冷却装置に関し、当該シリンダの連続肉壁部のヘッド寄り部を強力に冷却し、多気筒エンジンの相対的小型軽量化と出力アップを図る事ができるものを提供する。
【０００２】
【従来の技術】
近年、多気筒エンジンを小型・軽量化する必要からシリンダボアの間隔を狭くし、あるいは、排気量を多くしてエンジンの大出力化を図る必要からシリンダボアを大きくしてシリンダの連続肉壁部を可能な限り薄くしたサイアミーズシリンダが採用されるようになった。この種の従来技術としては、例えば、特公昭５６−４２７４４号公報に開示されたもの（以下、従来例１という）、あるいは、実開昭５９−６８１５５号公報に開示されたもの（以下、従来例２という）が知られている。
【０００３】
図６は従来例１を示し、図６（Ａ）はサイアミーズシリンダの要部の縦断面図、図６（Ｂ）は図６（Ａ）中のＢ−Ｂ線矢視横断平面図、図６（Ｃ）はサイアミーズシリンダの連続肉壁部のヘッド寄り部に鋳込まれる水路形成部材の斜視図である。この従来例１は、シリンダブロック１に複数のシリンダ３を前後に並設し、隣接するシリンダ３・３を連続肉壁部４で連続させてサイアミーズシリンダ２を構成し、このサイアミーズシリンダ２を囲むようにシリンダジャケット８を形成し、上記連続肉壁部４に水路形成部材１０を鋳込んである。この水路形成部材１０は、図６（Ａ）（Ｂ）（Ｃ）に示すように、その縦断側面視で縦長・偏平な冷却水路１５を備え、上記ヘッド寄り部４ａの左右両端部のシリンダジャケット８・８を当該冷却水路１５で連通するように構成されている。
【０００４】
図６（Ｂ）に示すように、上記シリンダジャケット８・８は、上記連続肉壁部４のヘッド寄り部４ａの左右両外側にせまっており、上記冷却水路１５の一側より流入した冷却水は、当該冷却水路１５を流通することにより、当該ヘッド寄り部４ａを冷却する。なお、シリンダヘッド（図示せず）を締結する左右一対のボルト６・６のボス部５・５は、当該シリンダジャケット８・８の外側に位置している。ここで、上記水路形成部材１０の左右両端部より突設した突出係止部１４ａ・１４ｂはシリンダジャケット中子の製作時に当該水路形成部材１０を中子に確実に固定するためのものである。
【０００５】
図７は従来例２を示し、図７（Ａ）はサイアミーズシリンダの要部の縦断面図、図７（Ｂ）は図７（Ａ）中のＢ−Ｂ線矢視横断平面図、図７（Ｃ）はサイアミーズシリンダの連続肉壁部４のヘッド寄り部４ａに鋳込まれる水路形成部材の斜視図である。この水路形成部材１０は、図７（Ａ）（Ｂ）（Ｃ）に示すように、連続肉壁部４の左右のシリンダジャケット８・８を連通する冷却水路１５と、この冷却水路１５の左右両端部に位置し、当該冷却水路１５と連通する左右一対のジャケット連通路１２・１２と、各ジャケット連通路１２・１２の下側に位置し、各シリンダジャケット８・８に向けて開口した左右一対の冷却水導入部１３・１３とを備えている。
【０００６】
上記冷却水導入部１３・１３より流入した冷却水は、上記冷却水路１５を流通するとともに、ジャケット連通路１２・１２を介して上記ヘッド寄り部４ａの上側に位置するヘッドジャケット（図示せず）に流出し、その間に連続肉壁部４のヘッド寄り部４ａを冷却する。なお、上記連続肉壁部４のヘッド寄り部４ａの左右に位置するシリンダヘッド締結用ボス部５・５は、従来例１と同様に当該シリンダジャケット８・８の外側に位置している。
【０００７】
【発明が解決しようとする課題】
従来例１は、冷却水路１５の左右両端部及び突出係止部１４ａ・１４ｂがシリンダジャケット８・８内に突出しているため、シリンダ外周面（３ａ）に沿って流れようとする冷却水の円滑な流通を阻害し、冷却水が冷却水路１５に流入するのを妨げている。このため、上記連続肉壁部４のヘッド寄り部４ａを強力に冷却できないという難点がある。しかも、水路形成部材１０の冷却水路１５が縦断側面視で縦長・偏平であることから、冷却水路１５の機械的強度が低く、シリンダボアの孔加工時の歪み耐久性が劣る。さらに、左右のシリンダヘッド締結用ボス部５・５が、シリンダジャケット８・８の外側に位置しているため、左右のヘッドボルト６・６の間隔が大きくなり、シリンダ３を周方向に沿って均一かつ強力に締結することができないという難点がある。
【０００８】
また、従来例２は、各ジャケット連通路１２を構成する筒体の下部を切り欠いて冷却水導入部１３を形成しているが、当該冷却水導入部１３の間口が小さいため、多量の冷却水を冷却水路１５に円滑に導入することができず、上記連続肉壁部４のヘッド寄り部４ａを強力に冷却できないという難点がある。しかも、従来例１と同様に冷却水路１５が縦長・偏平であることから、シリンダボアの孔加工時の歪み耐久性が劣る。さらに、左右のシリンダヘッド締結用ボス部５・５が、シリンダジャケット８・８の外側に位置しているため、左右のヘッドボルト６・６の間隔が大きくなり、シリンダ３を周方向に沿って均一かつ強力に締結することができないという難点がある。
【０００９】
つまり、従来例１及び従来例２は、いずれも燃焼室に近いヘッド寄り部４ａを強力に冷却できず放熱能力が低いため、空気利用率の向上を図ることができず、ひいてはエンジンの出力アップを図ることができない。即ち、ピストンリングはシリンダ壁を介して冷却されるが、上記ヘッド寄り部４ａの放熱能力が低いと、ピストンリングの焼き付き等を防止する観点より、特にトップリングをピストン頂面から一定距離だけ離間して装着せざるを得ない。このことはピストン頂部の外周に燃焼に寄与しないリング状のデッドスペースが生じることを意味する。このため空気利用率の向上を図ることができず、ひいてはエンジンの出力アップを図ることができないことになる。しかも、シリンダボアの孔加工時やエンジン運転時の歪み耐久性が劣る。
【００１０】
また、ディーゼルエンジンでは、圧縮比が高く、略９００Ｋｇ／ｃｍ²以上のガスシール圧を必要とするが、上記従来例１及び従来例２は、いずれもシリンダヘッド締結用ボス部５・５の間隔が大きく、シリンダ３を周方向に沿って均一かつ強力に締結することができないため、ディーゼルエンジンに適用した場合には、ガスシール圧を十分に高めることができない。特に近年では、さらに小型軽量化を促進し、エンジンの大出力化を図ることが要請されているが、従来例１及び従来例２は上記難点を有するため、これらの要請に十分に応えることができない。
【００１１】
本発明はこのような事情に鑑みてなされたもので、上記連続肉壁部のヘッド寄り部をさらに強力に冷却してトップリングをより上方に位置させることにより空気利用率の向上を図り、多気筒エンジンの一層の小型軽量化とエンジンの出力向上を図るとともに、シリンダボアの孔加工時やエンジン運転時の歪み耐久性を高めることを技術的課題とする。
【００１２】
【課題を解決するための手段】
本発明の基本構成は、以下のように構成される。サイアミーズシリンダ２を囲むようにシリンダジャケット８を形成し、上記サイアミーズシリンダ２の連続肉壁部４に水路を形成する。上記水路は、上記連続肉壁部４の左右両側に位置するシリンダジャケット８・８とヘッドジャケット２２とを連通するように縦向きに形成された左右のジャケット連通路１２・１２と、上記左右のジャケット連通路１２・１２の下部に設けられ、上記シリンダジャケット８・８に向けて開口する冷却水導入部１３・１３と、上記左右のジャケット連通路１２・１２を連通する横向きの冷却水路１５とを備える。
【００１３】
請求項１に記載の発明は、上記基本構成を有するサイアミーズシリンダの冷却装置において、以下の特徴構成を備える。上記連続肉壁部４の左右両側で、シリンダ３・３にシリンダヘッド締結用ボス部５・５を連続させて形成するとともに、上記各ジャケット連通路１２・１２を上記各シリンダヘッド締結用ボス部５・５の内側に位置させ、上記左右のシリンダヘッド締結用ボス部５・５間のヘッド寄り部４ａと、このヘッド寄り部４ａよりも下方の部分とにわたり上記冷却水路１５を設け、この冷却水路１５を上下に区画分離し、シリンダヘッド締結用ボス部５・５の下縁から冷却水路１５の最下縁までの冷却水路下半部の上下方向全域にわたり、縦向き一連に上記冷却水導入部１３・１３を形成し、この冷却水導入部１３・１３をその上下方向全域にわたりシリンダジャケット８・８に向けて前後に拡開させ、この冷却水導入部１３・１３の拡開先の入口前後縁を相互に対向するシリンダ外周面３ａ・３ａで形成した、ことを特徴とする。
【００１４】
請求項２に記載の発明は、請求項１に記載したサイアミーズシリンダの冷却装置において、上記冷却水路１５の上縁を左右方向両外側へ上り勾配に形成した、ことを特徴とする。
【００１５】
【発明の作用・効果】
▲１▼ 請求項１に記載の発明では、前記基本構成を備えるサイアミーズシリンダの冷却装置において、連続肉壁部４の左右両側で、シリンダ３・３にシリンダヘッド締結用ボス部５・５を連続させて形成するとともに、上記各ジャケット連通路１２・１２を上記各シリンダヘッド締結用ボス部５・５の内側に位置させ、上記左右のシリンダヘッド締結ボス部５・５間のヘッド寄り部４ａと、このヘッド寄り部（４ａ）よりも下方の部分とにわたり上記冷却水路１５を設け、この冷却水路１５を上下に区画分離したことから、連続肉壁部４の左右両側の厚肉部をくりぬいて、当該ジャケット連通路１２・１２の孔径を大きくできる。これにより、多量の冷却水を流通させて冷却性能を高めることができる。即ち、シリンダジャケット８・８内の冷却水は、上記水路を通ってヘッドジャケット２２へ抜ける。その間に冷却水の多くは冷却水路１５を流通して上記ヘッド寄り部４ａを強力に冷却する。そしてピストンリングはシリンダ壁を介してピストンを強力に冷却できるので、トップリングをピストン頂面に可及的に近づけ、ピストン頂部外周の燃焼に寄与しないリング状のデッドスペースを極力小さくして空気利用率の向上を図ることができる。また、これに伴って燃料の未燃部分及び潤滑油の炭化によるトップリングの膠着を解消することができる。
【００１６】
▲２▼ トップリングをピストン頂面に可及的に近づけることに伴って、ピストンピンの位置をピストン頂面に可及的に近づけ、その分だけクランク軸の振り回しの寸法を長くすることができ、コンロッドやエンジンの体格（高さ）を変えないで、ピストンストローク、ひいては排気量アップを図ることができる。つまり、多気筒エンジンの相対的小型化とエンジンの大出力化を図ることができる。
【００１７】
▲３▼ 逆にピストンストロークを変えない場合には、ピストンピンの位置をピストン頂面に近づけた分だけコンロッドを長く設定できるので、ピストン側圧力を低減でき、結果として摩擦損失の低減が図れる。
▲４▼ また、当該ヘッド寄り部を強力に冷却できるので、シリンダボアの直径を大きくすることにより排気量アップ、ひいては出力アップを図ることができる。
【００１８】
▲５▼ 請求項１に記載の発明では、冷却水路１５を上下に区画分離したことから、縦長で偏平な冷却水路を備える従来例と比較して、冷却水路１５の機械的強度が増大し、シリンダボアの孔加工時やエンジン運転時の歪み耐久性が高まる。
▲６▼ 請求項１に記載の発明では、シリンダヘッド締結用ボス部５・５の下縁から冷却水路１５の最下縁までの冷却水路下半部の上下方向全域にわたり、縦向き一連に上記冷却水導入部１３・１３を形成し、この冷却水導入部１３・１３をシリンダジャケット８・８に向けて前後に拡開させ、この冷却水導入部１３・１３の拡開先の入口前後縁を相互に対向するシリンダ外周面３ａ・３ａで形成した、ことから、シリンダジャケット８・８内の冷却水はシリンダ外周面３ａに沿って円滑に流れ、シリンダジャケット８・８に向けて大きく拡開された冷却水導入部１３・１３より流入し、上記ジャケット連通路１２・１２及び冷却水路１５を通ってヘッドジャケット２２へ抜ける。これにより、上記ヘッド寄り部４ａを一層強力に冷却するとともに、ヘッド寄り部４ａよりも下方の冷却通路下半部も強力に冷却する。
【００１９】
▲７▼ 請求項２に記載の発明では、請求項１に記載した発明の効果▲１▼〜▲６▼に加え、上記冷却水路１５の上縁を左右方向両外側へ上り勾配に形成したことから、冷却水路１５内で冷却水が沸騰して水蒸気が発生した場合でも、水蒸気は左右方向両外側へ上り勾配に形成した冷却水路１５の上縁に沿って上方へ移動し、ジャケット連通路１２・１２を通ってヘッドジャケット２２に逃げるので、冷却性能は高く維持される。
【００２０】
【発明の実施の形態】
以下、本発明の実施形態を図面に基づいて説明する。図１は本発明に係るサイアミーズシリンダの冷却装置を具備する縦型多気筒エンジンの要部を示し、同図（Ａ）は部分縦断面図、同図（Ｂ）はそのシリンダブロックの部分平面図である。また、図２は本発明の実施形態に係る水路形成部材を示し、同図（Ａ）は当該水路形成部材の斜視図、同図（Ｂ）は図２（Ａ）中のＢ−Ｂ線矢視縦断面図、同図（Ｃ）は図２（Ａ）中のＣ−Ｃ線矢視横断平面図である。さらに、図３は本発明に係るサイアミーズシリンダの冷却装置を具備する縦型多気筒エンジンの要部の縦断面図である。
【００２１】
この縦型多気筒エンジンＥは、図３に示すように、クランクケースを一体に形成したシリンダブロック１の上にシリンダヘッド２０をヘッドボルト６で固定し、シリンダブロック１に形成したシリンダジャケット８とシリンダヘッド２０に形成したヘッドジャケット２２とを、連続肉壁部４以外の部分に形成した多数のジャケット連通孔２４で連通し、シリンダブロック１を冷却した冷却水でシリンダヘッド２０を冷却するように構成されている。
【００２２】
本発明に係るサイアミーズシリンダの冷却装置は、従来例１及び従来例２と同様の基本構成を備えている。即ち、図１及び図３に示すように、シリンダブロック１に複数のシリンダ３を前後に並設し、隣接するシリンダ３・３を連続肉壁部４で連続させてサイアミーズシリンダ２を構成するとともに、上記サイアミーズシリンダ２を囲むようにシリンダジャケット８が形成されている。上記連続肉壁部４には、後述する水路形成部材１０が鋳込まれている。
【００２３】
以下、本発明の実施形態の特徴構成について説明する。上記水路形成部材１０は、図２に示すように、プレス成型した２枚の板金を相互に対向して重ね合わせ、接当部をシーム溶接して一体に構成されている。
即ち、この水路形成部材１０は、左右一対のジャケット連通路１２・１２と、上記ジャケット連通路１２・１２の下側に位置し、各シリンダジャケット８・８に向けて開口する左右一対の冷却水導入部１３・１３と、左右のジャケット連通路１２・１２及び左右の冷却水導入部１３・１３と連通する冷却水路１５とを備え、上記冷却水導入部１３・１３は、左右に突設した前後一対の冷却水案内板１４・１４を、それぞれシリンダ外周面３ａに沿って前後に拡開させて成り、上記冷却水導入部１３・１３より導入した多量の冷却水を、上記冷却水路１５に流通させるとともに、上記ジャケット連通路１２・１２を介して上記ヘッド寄り部４ａの上側に位置するヘッドジャケット２２に流出させるように構成されている。
【００２４】
上記のように水路形成部材１０は、上下多段で交互に形成した非空洞部１１と冷却水路１５とを備えることから、冷却水路１５の機械的強度が増大するので、従来例のように冷却水路１５を縦断側面視で縦長・偏平に形成した場合と比較して、シリンダボアの加工時やエンジン運転時に連続肉壁部４に作用する加圧力に対して強力に対抗でき、歪み耐久性が高まるという利点がある。
【００２５】
左右一対のシリンダヘッド締結用ボス部５・５は、上記ヘッド寄り部４ａの左右両側部と連続して形成され、ヘッドボルト６・６の配置間隔を狭めて当該狭められた分だけシリンダ３を周方向に沿って均一かつ強力に締結するように構成されている。なお、本発明はこれに限らないが、左右一対のシリンダヘッド締結用ボス部５・５をヘッド寄り部４ａの左右両側部及びシリンダ３・３と連続して形成することにより、シリンダブロック１の上端壁にあけたジャケット連通孔２３と一対のジャケット連通路１２・１２の孔径を大きくして多量の冷却水を流通させることができるという利点がある。
【００２６】
上記一対のジャケット連通路１２・１２は当該ボス部５・５の内側に位置し、シリンダブロック１の上端壁及びシリンダヘッド２０の下端壁とにあけたジャケット連通孔２３と連通している。また、冷却水路１５の左右の寸法ｄは、図１（Ａ）（Ｂ）に示すように、上記連続肉壁部４の左右の寸法Ｄよりも小さく設定されている。これにより、上記一対のジャケット連通路１２・１２の開口内側間隔ｄが上記連続肉壁部４の左右の寸法Ｄよりも小さく設定される。従って、ジャケット連通路１２・１２の開口内側間隔ｄを狭めた分だけ、左右のヘッドボルト６・６の配置間隔を狭めることができ、シリンダ３の周囲のヘッドボルト６の個数を多くすることができるので、シリンダ３を周方向に沿って一層均一かつ強力に締結することができる。これにより、ガスシール圧を高めることができる。
【００２７】
上記冷却水導入部１３・１３は、図１（Ａ）（Ｂ）に示すように、上記各ジャケット連通路１２・１２の下部で、上記左右のシリンダヘッド締結ボス部５・５の下側に近接配置され、前後一対の冷却水案内板１４・１４を左右に突設し、これらの冷却水案内板１４・１４をそれぞれシリンダ外周面３ａに添わせ、前後に拡開させて構成されている。すなわち、図１（Ａ）（Ｂ）に示すように、シリンダヘッド締結用ボス部５・５の下縁から冷却水路１５の最下縁までの冷却水路下半部の上下方向全域にわたり、縦向き一連に上記冷却水導入部１３・１３を形成し、この冷却水導入部１３・１３をその上下方向全域にわたりシリンダジャケット８・８に向けて前後に拡開させ、図２（Ｃ）に示すように、この冷却水導入部１３・１３の拡開先の入口前後縁を相互に対向するシリンダ外周面３ａ・３ａで形成した。上記構成により、冷却水導入部１３・１３の上下及び前後の間口が大きく形成され、冷却水の多くはシリンダジャケット８・８に向けて拡開された冷却水導入部１３・１３より下側冷却水路１５ｂ及びジャケット連通路１２に多量に流入し、上記ジャケット連通路１２・１２を通って連続肉壁部４の上側に位置するヘッドジャケット２２へ抜ける。その間に多量の冷却水が冷却水路１５及びジャケット連通路１２・１２を流通し、上記ボス部５・５の間のヘッド寄り部４ａを強力に冷却されるとともに、ヘッド寄り部４ａよりも下方の冷却通路下半部も強力に冷却される。これによりエンジンの排気量アップ、ひいては出力アップを図ることができる。
【００２８】
即ち、ヘッド寄り部４ａを強力に冷却することで、シリンダ壁を介してピストンリングを強力に冷却できるので、トップリングをピストン頂面に可及的に近づけ、ピストン頂部外周の燃焼に寄与しないリング状のデッドスペースを極力小さくして空気利用率の向上を図ることができる。また、これに伴って燃料の未燃部分の炭化によるトップリングの膠着を解消することができる。
【００２９】
しかも、トップリングをピストン頂面に可及的に近づけることに伴って、ピストンピンの位置をピストン頂面に可及的に近づけ、その分だけクランク軸の振り回しの寸法を長くすることができ、コンロッドエンジンの体格を変えないで相対的小型化を図り、ピストンストロークを大きくして、排気量アップを図ることができる。また、当該ヘッド寄り部４ａを強力に冷却できるので、シリンダボアの直径を大きくすることにより排気量アップを図ることもできる。さらに、ターボチャージャを搭載した多気筒エンジン等においても本発明を適用することにより、相対的小型化とエンジンの大出力化を図ることができる。
【００３０】
図４は２枚の板金を重ね合わせて構成した水路形成部材１０の冷却水路１５の断面形状を例示する概要図で、それぞれ（Ａ）は矩形、（Ｂ）は５角形、（Ｃ）は６角形、（Ｄ）は半円形、（Ｅ）は半矩形を示し、連続肉壁部４の形状等を考慮して適宜形状が選定される。
【００３１】
図５は水路形成部材１０の冷却水路１５の他の配列を例示する概要図である。図５（Ａ）は非空洞部１１と冷却水路１５とを上下多段で交互に配列したものであるが、連続肉壁部４のヘッド寄り部４ａを強力に冷却するために、上方の冷却水路１５ａの路幅を下方の冷却水路１５ｂの路幅よりも大きくしてある。図５（Ｂ）は、上下多段で交互に配列した非空洞部１１と冷却水路１５とが、共に下向きに円弧状に形成してある。図５（Ｃ）は冷却水路１５を略Ｖ字状とし、かつ、図５（Ａ）と同様に上方の冷却水路１５ａの路幅を下方の冷却水路１５ｂの路幅よりも大きくしてある。図５（Ｄ）は上下多段に配列した冷却水路１５の中央部を縦向きの冷却水路１５ｃで連通してある。図５（Ｅ）は図５（Ｃ）と同様の冷却水路１５の中央部を縦向きの冷却水路１５ｃで連通してある。図５（Ｆ）は非空洞部１１と冷却水路１５とを上下多段に傾斜させてある。そして図５（Ｇ）は略Ｘ字状に交差させた冷却水路１５を上下二段に配列させてある。
【００３２】
図５（Ｂ）〜図５（Ｇ）の配列によれば、万一、冷却水路１５内で冷却水が沸騰して水蒸気が発生した場合でも、水蒸気は傾斜した各冷却水路１５の上縁に沿って上方へ移動し、ジャケット連通路１２・１２を通ってヘッドジャケット２２に逃げるので、冷却性能は高く維持される。
【図面の簡単な説明】
【図１】本発明に係るサイアミーズシリンダの冷却装置を具備する縦型多気筒エンジンの要部を示し、同図（Ａ）は部分縦断面図、同図（Ｂ）はそのシリンダブロックの部分平面図である。
【図２】本発明の実施形態に係る水路形成部材を示し、同図（Ａ）は当該水路形成部材の斜視図、同図（Ｂ）は図２（Ａ）中のＢ−Ｂ線矢視縦断面図、同図（Ｃ）は図２（Ａ）中のＣ−Ｃ線矢視横断平面図である。
【図３】本発明に係るサイアミーズシリンダの冷却装置を具備する縦型多気筒エンジンの要部の縦断面図である。
【図４】本発明の水路形成部材の冷却水路の断面形状を例示する概要図である。
【図５】本発明の水路形成部材の冷却水路の配列を例示する概要図である。
【図６】従来例１を示し、同図（Ａ）は縦型エンジンのサイアミーズシリンダの要部の縦断面図、同図（Ｂ）は図６（Ａ）中のＢ−Ｂ線矢視横断平面図、同図（Ｃ）は水路形成部材の斜視図である。
【図７】従来例２を示す図６相当図である。
【符号の説明】
２…サイアミーズシリンダ、３…シリンダ、３ａ…シリンダ外周面、４…連続肉壁部、４ａ…連続肉壁部のヘッド寄り部、５…シリンダヘッド締結用ボス部、８…シリンダジャケット、１２…ジャケット連通路、１３…冷却水導入部、１５…冷却水路、１５ｂ…冷却水路の上縁、２２…ヘッドジャケット。[0001]
[Industrial application fields]
The present invention relates to a cooling device for a siamese cylinder of a multi-cylinder engine, which strongly cools the head side portion of the continuous wall portion of the cylinder and can reduce the relative size and weight of the multi-cylinder engine and increase the output. I will provide a.
[0002]
[Prior art]
In recent years, it has become necessary to reduce the size and weight of multi-cylinder engines, so that the distance between cylinder bores has been narrowed, or because it is necessary to increase engine output by increasing the amount of displacement, the cylinder bore can be enlarged to allow continuous cylinder wall sections. The thinnest Siamese cylinder has been adopted. Examples of this type of prior art include those disclosed in Japanese Patent Publication No. 56-42744 (hereinafter referred to as Conventional Example 1) or those disclosed in Japanese Utility Model Publication No. 59-68155 (hereinafter referred to as conventional). Example 2) is known.
[0003]
6 shows Conventional Example 1, FIG. 6 (A) is a longitudinal sectional view of the main part of the Siamese cylinder, FIG. 6 (B) is a cross-sectional plan view taken along the line BB in FIG. 6 (A), FIG. (C) is a perspective view of a water channel forming member cast into the head portion of the continuous wall portion of the Siamese cylinder. In this conventional example 1, a plurality of cylinders 3 are arranged in front and rear in a cylinder block 1 and adjacent cylinders 3 and 3 are connected by a continuous wall portion 4 to form a siamese cylinder 2, which surrounds the siamese cylinder 2. A cylinder jacket 8 is formed as described above, and a water channel forming member 10 is cast into the continuous wall portion 4. As shown in FIGS. 6A, 6B, and 6C, the water channel forming member 10 includes a cooling water channel 15 that is vertically long and flat when viewed from the vertical side, and cylinder jackets at both the left and right ends of the head-proximal portion 4a. 8.8 is configured to communicate with the cooling water passage 15.
[0004]
As shown in FIG. 6 (B), the cylinder jackets 8 and 8 are set on the left and right outer sides of the head side portion 4a of the continuous wall portion 4, and the cooling water flowing in from one side of the cooling water channel 15 is provided. Circulates through the cooling water channel 15 to cool the head offset portion 4a. The bosses 5 and 5 of the pair of left and right bolts 6 and 6 that fasten the cylinder head (not shown) are located outside the cylinder jackets 8 and 8. Here, the protruding locking portions 14a and 14b projecting from the left and right end portions of the water channel forming member 10 are for securely fixing the water channel forming member 10 to the core when the cylinder jacket core is manufactured.
[0005]
7 shows a second conventional example, FIG. 7A is a longitudinal sectional view of the main part of the Siamese cylinder, FIG. 7B is a cross-sectional plan view taken along the line B-B in FIG. (C) is a perspective view of a water channel forming member cast into the head side portion 4a of the continuous wall portion 4 of the Siamese cylinder. 7A, 7B, and 7C, the water channel forming member 10 includes a cooling water channel 15 that communicates the left and right cylinder jackets 8 and 8 of the continuous wall 4 and the left and right sides of the cooling water channel 15. A pair of left and right jacket communication passages 12, 12 that are located at both ends and communicate with the cooling water passage 15, and left and right openings that are located under the jacket communication passages 12, 12 and open toward the cylinder jackets 8, 8. A pair of cooling water introduction parts 13 and 13 is provided.
[0006]
The cooling water that has flowed in from the cooling water introducing portions 13 and 13 flows through the cooling water passage 15 and is located above the head side portion 4a via the jacket communication passages 12 and 12 (not shown). In the meantime, the head side portion 4a of the continuous wall portion 4 is cooled. The cylinder head fastening bosses 5 and 5 located on the left and right sides of the head side portion 4a of the continuous wall 4 are located outside the cylinder jackets 8 and 8 in the same manner as in the first conventional example.
[0007]
[Problems to be solved by the invention]
In the first conventional example, the left and right ends of the cooling water channel 15 and the protruding locking portions 14a and 14b protrude into the cylinder jackets 8 and 8, so that the cooling water flowing smoothly along the cylinder outer peripheral surface (3a) is smooth. The flow of the water is hindered and the cooling water is prevented from flowing into the cooling water channel 15. For this reason, there is a drawback that the head side portion 4a of the continuous wall portion 4 cannot be cooled strongly. In addition, since the cooling water channel 15 of the water channel forming member 10 is vertically long and flat when viewed from the longitudinal section, the mechanical strength of the cooling water channel 15 is low, and the strain durability during drilling of the cylinder bore is inferior. Further, since the left and right cylinder head fastening bosses 5 and 5 are located outside the cylinder jackets 8 and 8, the distance between the left and right head bolts 6 and 6 is increased, and the cylinder 3 is moved along the circumferential direction. There is a drawback that it cannot be uniformly and strongly fastened.
[0008]
Moreover, although the prior art example 2 cuts out the lower part of the cylinder which comprises each jacket communication path 12, and forms the cooling water introduction part 13, since the frontage of the said cooling water introduction part 13 is small, a lot of cooling There is a problem in that water cannot be smoothly introduced into the cooling water channel 15 and the head side portion 4a of the continuous wall portion 4 cannot be cooled strongly. Moreover, since the cooling water passage 15 is vertically long and flat like the conventional example 1, the strain durability during drilling of the cylinder bore is inferior. Further, since the left and right cylinder head fastening bosses 5 and 5 are located outside the cylinder jackets 8 and 8, the distance between the left and right head bolts 6 and 6 is increased, and the cylinder 3 is moved along the circumferential direction. There is a drawback that it cannot be uniformly and strongly fastened.
[0009]
That is, in both of the conventional example 1 and the conventional example 2, the head side portion 4a close to the combustion chamber cannot be cooled strongly and the heat dissipating capacity is low, so the air utilization rate cannot be improved, and the engine output is increased. I can't plan. In other words, the piston ring is cooled through the cylinder wall. However, if the heat dissipation capability of the head side portion 4a is low, the top ring is separated from the piston top surface by a certain distance from the viewpoint of preventing seizure of the piston ring. I have to wear it. This means that a ring-shaped dead space that does not contribute to combustion occurs on the outer periphery of the piston top. For this reason, an improvement in the air utilization rate cannot be achieved, and as a result, the engine output cannot be increased. Moreover, the strain durability during drilling of the cylinder bore and engine operation is inferior.
[0010]
The diesel engine has a high compression ratio and requires a gas seal pressure of approximately 900 Kg / cm ² or more. Both the conventional example 1 and the conventional example 2 have a gap between the cylinder head fastening bosses 5 and 5. Since the cylinder 3 cannot be fastened uniformly and strongly along the circumferential direction, the gas seal pressure cannot be sufficiently increased when applied to a diesel engine. In particular, in recent years, it has been demanded to further reduce the size and weight and increase the output of the engine. However, the conventional example 1 and the conventional example 2 have the above-described drawbacks, and thus can sufficiently satisfy these requests. Can not.
[0011]
The present invention has been made in view of such circumstances, and by improving the air utilization rate by cooling the head portion of the continuous wall portion more strongly and positioning the top ring more upward, It is a technical problem to further reduce the size and weight of the cylinder engine and improve the engine output, and to improve the durability of distortion during drilling of the cylinder bore and during engine operation.
[0012]
[Means for Solving the Problems]
The basic configuration of the present invention is configured as follows. A cylinder jacket 8 is formed so as to surround the siamese cylinder 2, and a water channel is formed in the continuous wall portion 4 of the siamese cylinder 2. The water channel includes left and right jacket communication passages 12 and 12 formed in a vertical direction so as to communicate the cylinder jackets 8 and 8 and the head jacket 22 positioned on the left and right sides of the continuous meat wall portion 4, and the left and right Cooling water introducing portions 13 and 13 that are provided in the lower part of the jacket communication passages 12 and 12 and open toward the cylinder jackets 8 and 8, and a lateral cooling water passage 15 that communicates with the left and right jacket communication passages 12 and 12. Is provided.
[0013]
The invention described in claim 1 is a siamese cylinder cooling device having the above basic configuration, and includes the following characteristic configuration. The cylinder head fastening bosses 5 and 5 are formed continuously on the cylinders 3 and 3 on both the left and right sides of the continuous wall 4 and the jacket communication passages 12 and 12 are formed on the cylinder head fastening bosses. The cooling water passage 15 is provided between the left and right cylinder head fastening bosses 5 and 5 and the portion closer to the lower side than the head displacement portion 4a. The water channel 15 is divided into upper and lower parts, and the cooling water is introduced in a series of vertical directions over the entire upper and lower direction of the lower half of the cooling water channel from the lower edge of the cylinder head fastening bosses 5 and 5 to the lowermost edge of the cooling water channel 15. Part 13 and 13 is formed, and this cooling water introduction part 13 and 13 is expanded back and forth toward the cylinder jacket 8 and 8 over the entire vertical direction , and the inlet of the expansion destination of this cooling water introduction part 13 and 13 is formed. Previous Formed in the cylinder outer peripheral surface 3a · 3a facing the edges to each other, characterized in that.
[0014]
According to a second aspect of the present invention, in the cooling device for the Siamese cylinder according to the first aspect, the upper edge of the cooling water passage 15 is formed in an upward slope toward both outer sides in the left-right direction.
[0015]
[Operation and effect of the invention]
(1) In the invention according to claim 1, in the cooling device for the Siamese cylinder having the above basic structure, the cylinder head fastening bosses 5 and 5 are continuously connected to the cylinders 3 and 3 on both the left and right sides of the continuous wall portion 4. And the jacket communication passages 12 and 12 are positioned inside the cylinder head fastening boss portions 5 and 5, and the head side portions 4 a between the left and right cylinder head fastening boss portions 5 and 5, Since the cooling water channel 15 is provided over the lower part of the head side portion (4a) and the cooling water channel 15 is divided into upper and lower parts, the thick wall portions on the left and right sides of the continuous wall portion 4 are hollowed out. The hole diameter of the jacket communication passages 12 and 12 can be increased. Thereby, a lot of cooling water can be circulated and cooling performance can be improved. That is, the cooling water in the cylinder jackets 8 and 8 passes through the water channel to the head jacket 22. In the meantime, most of the cooling water flows through the cooling water passage 15 and cools the head portion 4a. And since the piston ring can cool the piston strongly through the cylinder wall, the top ring is brought as close as possible to the piston top surface, and the ring-shaped dead space that does not contribute to combustion on the outer periphery of the piston top is made as small as possible to use air The rate can be improved. Accordingly, it is possible to eliminate the sticking of the top ring due to the unburned portion of the fuel and the carbonization of the lubricating oil.
[0016]
(2) As the top ring is moved as close as possible to the piston top surface, the piston pin position is moved as close as possible to the piston top surface, and the crankshaft swinging dimension can be increased accordingly. The piston stroke and thus the displacement can be increased without changing the physique (height) of the connecting rod or the engine. That is, it is possible to reduce the relative size of the multi-cylinder engine and increase the engine output.
[0017]
(3) Conversely, when the piston stroke is not changed, the connecting rod can be set longer as much as the position of the piston pin is brought closer to the top surface of the piston, so that the piston side pressure can be reduced, and as a result, friction loss can be reduced.
{Circle around (4)} Since the head side portion can be strongly cooled, the displacement can be increased and the output can be increased by increasing the diameter of the cylinder bore.
[0018]
(5) In the invention according to claim 1, since the cooling water channel 15 is divided into upper and lower parts, the mechanical strength of the cooling water channel 15 is increased as compared with the conventional example including a vertically long and flat cooling water channel, Strain durability during drilling of cylinder bores and engine operation is increased.
(6) In the first aspect of the present invention, the above-mentioned series in the vertical direction over the entire upper and lower direction of the lower half of the cooling water channel from the lower edge of the cylinder head fastening bosses 5 and 5 to the lowermost edge of the cooling water channel 15. The cooling water introduction portions 13 and 13 are formed, and the cooling water introduction portions 13 and 13 are expanded forward and backward toward the cylinder jackets 8 and 8, and the front and rear edges of the inlet of the expansion destination of the cooling water introduction portions 13 and 13 are formed. Is formed by the cylinder outer peripheral surfaces 3a and 3a facing each other, the cooling water in the cylinder jackets 8 and 8 smoothly flows along the cylinder outer peripheral surface 3a and greatly expands toward the cylinder jackets 8 and 8. The cooling water is introduced from the cooling water introducing portions 13 and 13 and passes through the jacket communication passages 12 and 12 and the cooling water passage 15 to the head jacket 22. As a result, the head closer portion 4a is cooled more strongly, and the lower half of the cooling passage below the head closer portion 4a is also cooled more powerfully.
[0019]
(7) In the invention described in claim 2, in addition to the effects (1) to (6) of the invention described in claim 1, the upper edge of the cooling water channel 15 is formed in an upward slope to both sides in the left-right direction. Thus, even when the cooling water boils in the cooling water channel 15 and steam is generated, the water vapor moves upward along the upper edge of the cooling water channel 15 formed in an upward gradient to both outer sides in the left-right direction, and the jacket communication channel 12 -Since it escapes to the head jacket 22 through 12, the cooling performance is maintained high.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a main part of a vertical multi-cylinder engine provided with a cooling device for a siamese cylinder according to the present invention. FIG. 1 (A) is a partial longitudinal sectional view, and FIG. 1 (B) is a partial plan view of the cylinder block. It is. 2 shows a water channel forming member according to an embodiment of the present invention, FIG. 2 (A) is a perspective view of the water channel forming member, and FIG. 2 (B) is a BB line arrow in FIG. 2 (A). FIG. 2C is a longitudinal sectional view taken along line CC in FIG. 2A. FIG. 3 is a longitudinal sectional view of an essential part of a vertical multi-cylinder engine equipped with a siamese cylinder cooling device according to the present invention.
[0021]
As shown in FIG. 3, the vertical multi-cylinder engine E has a cylinder head 20 fixed with a head bolt 6 on a cylinder block 1 integrally formed with a crankcase, and a cylinder jacket 8 formed on the cylinder block 1. The head jacket 22 formed on the cylinder head 20 is communicated with a large number of jacket communication holes 24 formed on portions other than the continuous wall portion 4, and the cylinder head 20 is cooled with cooling water that has cooled the cylinder block 1. It is configured.
[0022]
The siamese cylinder cooling device according to the present invention has the same basic configuration as that of Conventional Examples 1 and 2. That is, as shown in FIGS. 1 and 3, the cylinder block 1 includes a plurality of cylinders 3 arranged in front and rear, and the adjacent cylinders 3 and 3 are connected by the continuous wall portion 4 to form the siamese cylinder 2. A cylinder jacket 8 is formed so as to surround the siamese cylinder 2. A water channel forming member 10 to be described later is cast into the continuous wall portion 4.
[0023]
The characteristic configuration of the embodiment of the present invention will be described below. As shown in FIG. 2, the water channel forming member 10 is integrally formed by stacking two press-molded sheet metals so as to face each other and seam welding the contact portions.
That is, the water channel forming member 10 is located on the lower side of the pair of left and right jacket communication passages 12 and 12 and on the lower side of the jacket communication passages 12 and 12 and opens toward the cylinder jackets 8 and 8. Introducing portions 13 and 13, left and right jacket communication passages 12 and 12, and cooling water passages 15 communicating with the left and right cooling water introducing portions 13 and 13, the cooling water introducing portions 13 and 13 projecting left and right. A pair of front and rear cooling water guide plates 14 and 14 are respectively expanded front and rear along the cylinder outer peripheral surface 3a, and a large amount of cooling water introduced from the cooling water introduction portions 13 and 13 is supplied to the cooling water passage 15. In addition to being circulated, it is configured to flow out to the head jacket 22 located above the head side portion 4a through the jacket communication passages 12 and 12.
[0024]
As described above, the water channel forming member 10 includes the non-cavity portions 11 and the cooling water channels 15 that are alternately formed in upper and lower stages, so that the mechanical strength of the cooling water channel 15 is increased. Compared with the case where 15 is formed vertically long and flat in a side view in the longitudinal direction, it can strongly counter the pressure applied to the continuous wall portion 4 when the cylinder bore is processed or the engine is operated, and the strain durability is increased. There are advantages.
[0025]
The pair of left and right cylinder head fastening bosses 5 and 5 are formed continuously with the left and right side portions of the head side portion 4a, and the arrangement distance of the head bolts 6 and 6 is narrowed to reduce the cylinder 3 by the narrowed amount. It is configured to be fastened uniformly and strongly along the circumferential direction. Although the present invention is not limited to this, by forming the pair of left and right cylinder head fastening bosses 5, 5 continuously with the left and right side portions of the head offset portion 4 a and the cylinders 3, 3, There is an advantage that a large amount of cooling water can be circulated by enlarging the hole diameter of the jacket communication hole 23 and the pair of jacket communication passages 12 and 12 formed in the upper end wall.
[0026]
The pair of jacket communication passages 12 and 12 are located inside the boss portions 5 and 5 and communicate with a jacket communication hole 23 formed in the upper end wall of the cylinder block 1 and the lower end wall of the cylinder head 20. Moreover, the left-right dimension d of the cooling water channel 15 is set smaller than the left-right dimension D of the said continuous wall part 4, as shown to FIG. 1 (A) (B). Thereby, the opening inner space | interval d of a pair of said jacket communication path 12 * 12 is set smaller than the dimension D of the left and right of the said continuous wall part 4. FIG. Therefore, the arrangement interval of the left and right head bolts 6 and 6 can be narrowed by the amount of narrowing of the opening inner space d of the jacket communication passages 12 and 12, and the number of head bolts 6 around the cylinder 3 can be increased. Therefore, the cylinder 3 can be fastened more uniformly and strongly along the circumferential direction. Thereby, a gas seal pressure can be raised.
[0027]
As shown in FIGS. 1A and 1B, the cooling water introduction portions 13 and 13 are provided below the left and right cylinder head fastening boss portions 5 and 5 below the jacket communication passages 12 and 12, respectively. A pair of front and rear cooling water guide plates 14 and 14 are provided in the vicinity of each other so as to protrude left and right. These cooling water guide plates 14 and 14 are respectively attached to the outer peripheral surface 3a of the cylinder and are expanded forward and backward. . That is, as shown in FIGS. 1 (A) and 1 (B), the vertical direction extends over the entire vertical direction of the lower half of the cooling water channel from the lower edge of the cylinder head fastening bosses 5 and 5 to the lowermost edge of the cooling water channel 15. The cooling water introduction portions 13 and 13 are formed in series, and the cooling water introduction portions 13 and 13 are spread back and forth toward the cylinder jackets 8 and 8 over the entire vertical direction , as shown in FIG. In addition, the front and rear edges of the inlet of the expansion destination of the cooling water introduction portions 13 and 13 are formed by cylinder outer peripheral surfaces 3a and 3a facing each other. With the above configuration, the upper and lower and front and rear openings of the cooling water introduction portions 13 and 13 are formed large, and most of the cooling water is cooled below the cooling water introduction portions 13 and 13 that are expanded toward the cylinder jackets 8 and 8. A large amount flows into the water passage 15 b and the jacket communication passage 12, and passes through the jacket communication passages 12 and 12 to the head jacket 22 positioned on the upper side of the continuous wall portion 4. In the meantime, a large amount of cooling water flows through the cooling water passage 15 and the jacket communication passages 12 and 12, and the head side portion 4a between the boss portions 5 and 5 is strongly cooled, and the head side portion 4a is lower than the head side portion 4a. The lower half of the cooling passage is also cooled strongly. As a result, the engine displacement can be increased, and thus the output can be increased.
[0028]
In other words, the piston ring can be strongly cooled via the cylinder wall by strongly cooling the head side portion 4a, so that the top ring is brought as close as possible to the piston top surface and does not contribute to the combustion on the outer periphery of the piston top portion. The air dead rate can be improved by making the dead space as small as possible. Accordingly, the sticking of the top ring due to carbonization of the unburned portion of the fuel can be eliminated.
[0029]
Moreover, as the top ring is brought as close as possible to the piston top surface, the piston pin position is brought as close as possible to the piston top surface, and the crankshaft swinging dimension can be increased accordingly. Relative downsizing can be achieved without changing the size of the connecting rod engine, and the piston stroke can be increased to increase the displacement. In addition, since the head offset portion 4a can be strongly cooled, the displacement can be increased by increasing the diameter of the cylinder bore. Further, by applying the present invention to a multi-cylinder engine equipped with a turbocharger, it is possible to achieve a relatively small size and a high engine output.
[0030]
FIG. 4 is a schematic diagram illustrating the cross-sectional shape of the cooling water channel 15 of the water channel forming member 10 configured by superposing two sheet metals, where (A) is a rectangle, (B) is a pentagon, and (C) is 6 A square shape, (D) indicates a semicircular shape, (E) indicates a semirectangular shape, and the shape is appropriately selected in consideration of the shape of the continuous wall portion 4 and the like.
[0031]
FIG. 5 is a schematic view illustrating another arrangement of the cooling water channels 15 of the water channel forming member 10. FIG. 5 (A) shows the non-hollow portions 11 and the cooling water channels 15 alternately arranged in upper and lower stages, and in order to cool the head side portion 4a of the continuous wall portion 4 strongly, The road width of 15a is made larger than the width of the cooling water passage 15b below. In FIG. 5B, the non-hollow portions 11 and the cooling water channels 15 alternately arranged in upper and lower stages are both formed in an arc shape downward. 5C, the cooling water passage 15 is substantially V-shaped, and the width of the upper cooling water passage 15a is larger than the width of the lower cooling water passage 15b as in FIG. 5A. In FIG. 5 (D), the central part of the cooling water passages 15 arranged in multiple upper and lower stages is communicated with a vertical cooling water passage 15c. In FIG. 5E, the central portion of the cooling water passage 15 similar to that in FIG. 5C is communicated with a vertical cooling water passage 15c. In FIG. 5 (F), the non-hollow part 11 and the cooling water channel 15 are inclined in multiple stages. In FIG. 5G, cooling water passages 15 intersecting in a substantially X shape are arranged in two upper and lower stages.
[0032]
According to the arrangement of FIGS. 5 (B) to 5 (G), even if the cooling water boils in the cooling water channel 15 and water vapor is generated, the water vapor is at the upper edge of each inclined cooling water channel 15. Accordingly, the cooling performance is maintained high.
[Brief description of the drawings]
FIG. 1 shows a main part of a vertical multi-cylinder engine equipped with a cooling device for a siamese cylinder according to the present invention, where FIG. 1 (A) is a partial longitudinal sectional view, and FIG. 1 (B) is a partial plane of the cylinder block. FIG.
2A and 2B show a water channel forming member according to an embodiment of the present invention, in which FIG. 2A is a perspective view of the water channel forming member, and FIG. 2B is a view taken along line BB in FIG. A longitudinal sectional view, (C) of FIG. 2 is a cross-sectional plan view taken along the line CC in FIG. 2 (A).
FIG. 3 is a longitudinal sectional view of an essential part of a vertical multi-cylinder engine equipped with a siamese cylinder cooling device according to the present invention.
FIG. 4 is a schematic view illustrating the cross-sectional shape of a cooling water channel of the water channel forming member of the present invention.
FIG. 5 is a schematic view illustrating the arrangement of cooling water channels of the water channel forming member of the present invention.
6A and FIG. 6B show a conventional example 1, in which FIG. 6A is a longitudinal sectional view of a main part of a siamese cylinder of a vertical engine, and FIG. 6B is a cross-sectional view taken along line BB in FIG. The top view and the same figure (C) are perspective views of a water channel formation member.
FIG. 7 is a view corresponding to FIG.
[Explanation of symbols]
2 ... Siamese cylinder, 3 ... Cylinder, 3a ... Cylinder outer peripheral surface, 4 ... Continuous wall portion, 4a ... Head close portion of continuous wall portion, 5 ... Cylinder head fastening boss portion, 8 ... Cylinder jacket, 12 ... Jacket A communication path, 13 ... cooling water introduction part, 15 ... cooling water channel, 15b ... upper edge of cooling water channel, 22 ... head jacket.

Claims

A cylinder jacket (8) is formed so as to surround the siamese cylinder (2), a water channel is formed in the continuous wall (4) of the siamese cylinder (2),
The water channel has a left and right jacket communication passage (12) formed vertically to communicate the cylinder jacket (8, 8) and the head jacket (22) located on the left and right sides of the continuous wall portion (4). 12), cooling water introducing portions (13, 13) provided at the lower part of the left and right jacket communication passages (12, 12) and opening toward the cylinder jacket (8, 8), and the left and right jackets In the cooling device for the Siamese cylinder, comprising a lateral cooling water passage (15) communicating with the communication passages (12, 12).
Cylinder head fastening bosses (5, 5) are continuously formed on the cylinders (3, 3) on both the left and right sides of the continuous wall portion (4), and the jacket communication passages (12, 12) are formed. Located inside the cylinder head fastening bosses (5, 5),
The cooling water channel (15) is provided across the head side portion (4a) between the left and right cylinder head fastening boss portions (5, 5) and a portion below the head side portion (4a). (15) is divided into upper and lower sections,
The cooling water introduction portions (13, 13) are arranged in series in the vertical direction over the entire upper and lower direction of the lower half of the cooling water channel from the lower edge of the cylinder head fastening boss (5, 5) to the lowermost edge of the cooling water channel (15). ), And the cooling water introduction part (13, 13) is widened back and forth toward the cylinder jacket (8, 8) over the entire vertical direction , and the cooling water introduction part (13, 13) is expanded. A cooling device for a siamese cylinder, wherein the front and rear edges of the inlet are formed by cylinder outer peripheral surfaces (3a, 3a) facing each other.

In the cooling device of the Siamese cylinder according to claim 1,
A cooling device for a siamese cylinder, wherein the upper edge of the cooling water channel (15) is formed to rise outward in the left-right direction.