JPS6393876A - Cylinder head for internal-combustion engine made of cast iron - Google Patents
Cylinder head for internal-combustion engine made of cast ironInfo
- Publication number
- JPS6393876A JPS6393876A JP23876186A JP23876186A JPS6393876A JP S6393876 A JPS6393876 A JP S6393876A JP 23876186 A JP23876186 A JP 23876186A JP 23876186 A JP23876186 A JP 23876186A JP S6393876 A JPS6393876 A JP S6393876A
- Authority
- JP
- Japan
- Prior art keywords
- cast iron
- cylinder head
- surface layer
- graphite cast
- graphite
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 229910001018 Cast iron Inorganic materials 0.000 title claims abstract description 41
- 238000002485 combustion reaction Methods 0.000 title claims abstract description 10
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 45
- 229910002804 graphite Inorganic materials 0.000 claims abstract description 44
- 239000010439 graphite Substances 0.000 claims abstract description 44
- 239000002344 surface layer Substances 0.000 claims abstract description 18
- 239000000463 material Substances 0.000 claims abstract description 14
- 229910000859 α-Fe Inorganic materials 0.000 claims abstract description 8
- 229910001562 pearlite Inorganic materials 0.000 claims description 5
- 229910001141 Ductile iron Chemical group 0.000 abstract description 19
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical group [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 abstract description 10
- 230000009466 transformation Effects 0.000 abstract description 7
- 229910045601 alloy Inorganic materials 0.000 abstract description 6
- 239000000956 alloy Substances 0.000 abstract description 6
- 239000000843 powder Substances 0.000 abstract description 6
- 239000011159 matrix material Substances 0.000 abstract description 5
- 238000000137 annealing Methods 0.000 abstract description 4
- 229910001567 cementite Inorganic materials 0.000 abstract description 3
- KSOKAHYVTMZFBJ-UHFFFAOYSA-N iron;methane Chemical group C.[Fe].[Fe].[Fe] KSOKAHYVTMZFBJ-UHFFFAOYSA-N 0.000 abstract description 3
- 239000010410 layer Substances 0.000 description 16
- 230000008646 thermal stress Effects 0.000 description 5
- 238000000034 method Methods 0.000 description 4
- 238000002844 melting Methods 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- 238000005275 alloying Methods 0.000 description 2
- 239000010953 base metal Substances 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 239000000446 fuel Substances 0.000 description 2
- 239000003779 heat-resistant material Substances 0.000 description 2
- 238000002347 injection Methods 0.000 description 2
- 239000007924 injection Substances 0.000 description 2
- 230000001678 irradiating effect Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 230000035882 stress Effects 0.000 description 2
- 101000616862 Dendroaspis angusticeps Mambaquaretin-1 Proteins 0.000 description 1
- 240000005979 Hordeum vulgare Species 0.000 description 1
- 235000007340 Hordeum vulgare Nutrition 0.000 description 1
- 206010040844 Skin exfoliation Diseases 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000010894 electron beam technology Methods 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000003303 reheating Methods 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 238000007751 thermal spraying Methods 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
Landscapes
- Cylinder Crankcases Of Internal Combustion Engines (AREA)
- Other Surface Treatments For Metallic Materials (AREA)
Abstract
Description
【発明の詳細な説明】
産業上の利用分野
この発明は自動車用ディーゼルエンジンなどの内燃機関
に使用される鋳鉄製のシリンダに関し、特にインテーク
バルブシートとエキゾーストバルブシートとの間の部分
く弁間部）を強化した鋳鉄製内燃機関用シリンダヘッド
に関するものである。DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a cast iron cylinder used in an internal combustion engine such as an automobile diesel engine, and in particular to a valve gap between an intake valve seat and an exhaust valve seat. ) This relates to a cast iron cylinder head for internal combustion engines with reinforced steel.
従来の技術
近年、自動車のエンジンに対する要求性能はますます高
度なものとなっており、そのためエンジンの運転条件は
材料にとって著しく苛酷なものとなっている。特にディ
ーゼルエンジンにおいては作動時の燃焼温度が高く、そ
のシリンダヘッドは著しい高温に曝されるようになって
いる。BACKGROUND OF THE INVENTION In recent years, the performance requirements for automobile engines have become increasingly high, and as a result, engine operating conditions have become extremely harsh on materials. In particular, diesel engines have high combustion temperatures during operation, and their cylinder heads are exposed to extremely high temperatures.
従来のディーゼルエンジン用シリンダヘッドとしては鋳
鉄製のものが一般的であり、またその場合の鋳鉄として
は、鋳造性やコスト等の点から片状黒ｔｋｉ鋳鉄を用い
るのが通常である。片状黒鉛鋳鉄は、周知のように片状
の細長い形状の黒鉛が晶出したものであって、基地組織
は一般にバーライ１〜とされている。このような片状黒
鉛鋳鉄を用いた従来のシリンダヘッド、特にディーゼル
エンジン用のシリダヘッドにおいては、インテークバル
ブ（吸気弁）のバルブシートとエキゾーストバルブ（排
気弁）のバルブシートとの間の部分（弁間部）において
亀裂が発生し易く、そのためシリンダヘッドの信頼性、
耐久性が低いという問題があった。Conventional cylinder heads for diesel engines are generally made of cast iron, and from the viewpoint of castability, cost, etc., flaky black TKI cast iron is usually used as the cast iron. As is well known, flake graphite cast iron is obtained by crystallizing graphite in the form of flakes and elongated shapes, and the matrix structure is generally barley 1. In conventional cylinder heads using such flake graphite cast iron, especially cylinder heads for diesel engines, the part between the valve seat of the intake valve (intake valve) and the valve seat of the exhaust valve (exhaust valve) cracks are likely to occur in the cylinder head), which reduces the reliability of the cylinder head.
There was a problem of low durability.
すなわちシリンダヘッドの弁間部は、シリンダヘッドの
各部のうちでも燃焼時に特に＠激に高温に曝される部分
であり、エンジンの作動および作動停止に伴なう温度の
上昇、下降による熱膨張・収縮による熱応力は著しく高
い。しかもシリンダヘッドの弁間部は、シリンダヘッド
の構造上、他の部分と比較して格段に薄肉に作られてお
り、そのため上述のような熱応力により弁間部の片状黒
鉛の部分に応力集中が生じてその片状黒鉛の部分からク
ラックが発生し易く、また発生したクラックが細長い片
状黒鉛に沿って成長し易く、そのため弁間部で割れが発
生することが多かったのである。In other words, the part between the valves of the cylinder head is a part of the cylinder head that is particularly exposed to extremely high temperatures during combustion, and is subject to thermal expansion and drop due to temperature rises and falls as the engine starts and stops. Thermal stress due to shrinkage is significantly high. Moreover, due to the structure of the cylinder head, the valve gap of the cylinder head is made to be much thinner than other parts, so the thermal stress mentioned above causes stress to the flaky graphite part of the valve gap. When concentration occurs, cracks tend to occur from the flaky graphite portions, and cracks that occur tend to grow along the elongated flaky graphite, which often causes cracks to occur in the intervalve areas.
鋳鉄製シリンダヘットの弁間部を強化する方法としては
、例えば特開昭５８−６２３４４号公報に記載されてい
るように肉盛によりＮ：合金等の耐熱性金属層を弁間部
に形成する方法など、弁間部にシリンダヘッドの本体部
分を構成している鋳鉄とは別の耐熱性材料からなる層を
設ける方法が知られている。As a method of strengthening the valve gap of a cast iron cylinder head, for example, as described in JP-A-58-62344, a heat-resistant metal layer such as N:alloy is formed in the valve gap by overlaying. There is a known method in which a layer made of a heat-resistant material different from the cast iron that constitutes the main body of the cylinder head is provided between the valves.
発明が解決すべき問題点
前記提案のように肉盛などによって鋳鉄製シリンダヘッ
ドの弁間部に、母材鋳鉄とは別異の耐熱性材料からなる
層を形成する方法では、その層と母材である鋳鉄製本体
部分との境界部に、熱膨張率の相異によって亀裂が発生
する問題がある。Problems to be Solved by the Invention In the above-mentioned method of forming a layer made of a heat-resistant material different from the base material cast iron in the valve space of a cast iron cylinder head by overlaying, etc., the layer and the base material are There is a problem in that cracks occur at the boundary with the main body made of cast iron due to the difference in coefficient of thermal expansion.
この発明は以上の事情を背景としてなされたもので、上
述のような問題を招くことなく、片状黒鉛鋳鉄からなる
シリンダヘッドの弁間部を強化してその弁間部の亀裂発
生を防止したシリンダヘッドを提供することを目的とす
るものである。This invention was made against the background of the above-mentioned circumstances, and it is possible to strengthen the valve gap of a cylinder head made of flaky graphite cast iron and prevent the occurrence of cracks in the valve gap, without causing the above-mentioned problems. The purpose is to provide a cylinder head.
問題点を解決するための手段
この発明の鋳鉄製シリンダヘッドは、シリンダヘッドの
母材が片状黒鉛鋳鉄からなり、かつ少なくとも弁間部の
表面層の組織中における黒鉛が局部的に球状化されてい
ることを特徴とするものである。Means for Solving the Problems In the cast iron cylinder head of the present invention, the base material of the cylinder head is made of flaky graphite cast iron, and the graphite in the structure of the surface layer at least in the intervalve region is locally spheroidized. It is characterized by the fact that
ここで、弁間部を構成する片状黒鉛鋳鉄組織の基地組織
は、パーライトとしても良いが、フェライトとすること
が好ましい。Here, the matrix structure of the flake graphite cast iron structure constituting the intervalve region may be pearlite, but is preferably ferrite.
作 用
球状黒鉛鋳鉄は、その黒鉛が球状であるため、片状黒鉛
鋳鉄のような応力集中が生じにくく、また黒鉛に沿って
のクラックの成長も生じにくく、そのため大きな熱応力
、繰返し熱応力に対しても割れが発生しにくい。この発
明のシリンダヘッドにおいても、母材は片状黒鉛鋳鉄で
作られているが、少なくとも弁間部の表面層の組織中の
黒鉛は球状化されて、その部分が球状黒鉛鋳鉄となって
いるから、エンジンの作動・停止による熱応力によって
弁間部に亀裂が発生することが有効に防止される。また
この弁間部の球状黒鉛鋳鉄部分は、母材の片状黒鉛鋳鉄
部分と一体化しており、また球状黒鉛鋳鉄と片状黒鉛鋳
鉄の熱膨張率はほとんど同じであるから、弁間部に形成
した球状黒鉛鋳鉄層と母材との境界で亀裂が発生するお
それもない。Function: Because the graphite in spheroidal graphite cast iron is spherical, stress concentration is less likely to occur as in flaky graphite cast iron, and cracks are less likely to grow along the graphite, so it is resistant to large thermal stress and repeated thermal stress. Cracking is also less likely to occur. In the cylinder head of this invention, the base material is also made of flaky graphite cast iron, but the graphite in the structure of the surface layer at least in the valve gap is spheroidized, and that part is made of spheroidal graphite cast iron. This effectively prevents cracks from forming in the valve gap due to thermal stress caused by engine operation and shutdown. In addition, the spheroidal graphite cast iron part of the valve space is integrated with the flaky graphite cast iron part of the base material, and since the thermal expansion coefficients of spheroidal graphite cast iron and flaky graphite cast iron are almost the same, the spheroidal graphite cast iron part of the valve space is There is no fear that cracks will occur at the boundary between the formed spheroidal graphite cast iron layer and the base material.
また特に弁間部の球状黒鉛鋳鉄層の基地組織をフェライ
トとしておけば、基地組織がパーライトの場合よりも靭
性が向上し、そのため弁間部の割れ発生をより一層確実
に防止することができる。Furthermore, if the base structure of the spheroidal graphite cast iron layer in the intervalve region is made of ferrite, the toughness will be improved compared to when the base structure is pearlite, and therefore the occurrence of cracks in the intervalve region can be more reliably prevented.
なおシリンダヘッド全体を球状黒鉛鋳鉄で作れば、この
発明のように特に弁間部の黒鉛を球状化する必要がなく
なるとも考えられるが、実際にはシリンダヘッド全体を
球状黒鉛で作ることは困難である。すなわち球状黒鉛鋳
鉄は鋳造性が片状黒鉛鋳鉄より格段に劣っており、特に
シリンダヘッドは肉厚の極端に厚い部分や極端に薄い部
分が存在しているから、このような肉厚の変化する鋳物
を球状黒鉛鋳鉄で鋳造しようとすれば、引は巣等の欠陥
の発生が著しくなって実用には耐えない。It is thought that if the entire cylinder head is made of spheroidal graphite cast iron, there will be no need to spheroidize the graphite between the valves as in this invention, but in reality it is difficult to make the entire cylinder head from spheroidal graphite. be. In other words, the castability of spheroidal graphite cast iron is significantly inferior to that of flake graphite cast iron, and the cylinder head in particular has extremely thick and extremely thin parts, so there is no change in wall thickness. If a casting is attempted to be made of spheroidal graphite cast iron, the occurrence of defects such as cavities will become significant, making it impractical for practical use.
そこでこの発明では、母材部分は従来と同様に片状黒鉛
鋳鉄で作成して欠陥の発生を防止し、弁間部のような特
に必要な部位のみを球状黒鉛鋳鉄としているのでおる。Therefore, in this invention, the base material is made of flake graphite cast iron as in the past to prevent the occurrence of defects, and only particularly necessary parts such as the valve gap are made of spheroidal graphite cast iron.
発明の実施のための具体的説明
第１図および第２図にこの発明のシリンダヘッドの一例
を示す。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 and FIG. 2 show an example of the cylinder head of the present invention.
第１図、第２図において、１は片状黒鉛鋳鉄で形成され
たシリンダヘッド本体であり、そのシリンダヘッド本体
１のインテークバルブシート２とエキゾーストバルブシ
ート３との間の弁間部４（第１図において交叉斜線を施
した部分）は、表面層が球状黒鉛鋳鉄層５とされている
。In FIGS. 1 and 2, reference numeral 1 denotes a cylinder head body made of flake graphite cast iron. The surface layer of the cross-hatched area (in FIG. 1) is a spheroidal graphite cast iron layer 5.
このようなシリンダヘッドは、次のようにして製造する
ことができる。Such a cylinder head can be manufactured as follows.
すなわち、常法にしたがって片状黒鉛鋳鉄からなるシリ
ンダヘッド粗形材を鋳造し、必要に応じて機械加工を施
してから、レーザ、ＴＩＧアーク、プラズマアーク、電
子ビームなどの高密度エネルギを用いて弁間部の表面層
を溶融させると同時に、ＭＱＳＣｅ等の黒鉛球状化元素
を合金化し、その合金化層の凝固後に、Ａ１変態点以上
の温度に再加熱してセメンタイトを分解し、続いてＡ１
変態点以下の温度で焼なましを施す。このようにすれば
、弁間部の表面層がフェライトを基地とする球状黒鉛鋳
鉄組織となっておりしかもその他の母材部分が片状黒鉛
鋳鉄で作られたシリンダヘッドが得られる。また上述の
プロセスにおいて、最後のＡ１変態点以下の温度での焼
なましを省略すれば、弁間部の表面層は基地組織がパー
ライトの球状黒鉛鋳鉄組織となる。That is, a cylinder head rough shape made of flake graphite cast iron is cast according to a conventional method, machined as necessary, and then machined using high-density energy such as a laser, TIG arc, plasma arc, or electron beam. At the same time as melting the surface layer of the intervalve part, a graphite spheroidizing element such as MQSCe is alloyed, and after the alloyed layer is solidified, it is reheated to a temperature higher than the A1 transformation point to decompose the cementite, and then the A1
Annealing is performed at a temperature below the transformation point. In this way, a cylinder head can be obtained in which the surface layer of the valve gap has a ferrite-based spheroidal graphite cast iron structure, and the other base material portions are made of flaky graphite cast iron. Furthermore, in the above process, if the final annealing at a temperature below the A1 transformation point is omitted, the surface layer of the intervalve region will have a spheroidal graphite cast iron structure with pearlite as the matrix structure.
以上のような製造方法において、弁間部を高密度エネル
ギにより溶融しつつＭｑＳＣｅ等の黒鉛球状化元素を合
金化する工程は、例えばＭｇヤＱｅあるいはそれらを含
む合金（Ｆｅとの母合金、必るいはＦｅおよび３ｉとの
合金など）の粉末を弁間部表面に供給しつつレーザやＴ
ＩＧアーク等の高密度エネルギを照射して、その粉末と
弁間部表面層とを溶融させ、その粉末と弁間部表面層と
を溶融・一体化させれば良い。あるいはまたＭｇ、Ｃｅ
もしくはそれらの合金の層を予め弁間部表面に溶射によ
り形成しておいたり、また五線物として弁間部表面に塗
布しておいたりし、それらの上からレーザやＴＩＧアー
クを照射しても良い。In the above manufacturing method, the step of alloying a graphite spheroidizing element such as MqSCe while melting the valve gap with high-density energy is performed using, for example, Mg, Qe, or an alloy containing them (a master alloy with Fe, a master alloy with Fe, etc.). A laser beam or T
The powder and the surface layer of the valve gap may be melted by irradiating high-density energy such as IG arc, and the powder and the surface layer of the valve gap may be melted and integrated. Or Mg, Ce
Alternatively, a layer of these alloys may be formed in advance on the surface of the valve gap by thermal spraying, or it may be coated as a five-line material on the surface of the valve gap, and a laser or TIG arc may be irradiated onto the layer. Also good.
上）ホのように高密度エネルギの照射により溶融・合金
化させた後、高密度エネルギの照射を停止させるかまた
は照射位置を相対移動させれば、母材側への熱移動によ
って溶融層は急速に冷却・凝固する。この冷却・凝固は
通常は急速に行なわれるから、その凝固層はチル化され
た状態となり、黒鉛は析出しておらず、また硬くて脆い
組織となっている。そこでこの後にＡ１変態点以上の温
度で再ｈＯ熱することによって、チル組織のせメンタイ
：・を分解させ、かつ黒鉛を析出させる。この黒鉛析出
時には、予め合金化しておいたＭ（Ｊ、Ｃｅ等の黒鉛球
状化元素の作用によって黒鉛が球状に析出する。またこ
のようなＡ１変態点以上の温度での再加熱後の基地組織
はパーライトとなっているが、この後さらにＡ１変態点
以下で焼なましを施すことによって基地組織をフェライ
トとすることができる。Above) After melting and alloying by high-density energy irradiation as shown in E, if the high-density energy irradiation is stopped or the irradiation position is moved relatively, the molten layer will be formed by heat transfer to the base metal side. Cools and solidifies rapidly. Since this cooling and solidification usually occurs rapidly, the solidified layer is in a chilled state, with no graphite precipitated and a hard and brittle structure. Thereafter, by reheating with HO at a temperature higher than the A1 transformation point, the chilled structure is decomposed and graphite is precipitated. During this graphite precipitation, graphite is precipitated in a spherical shape due to the action of graphite spheroidizing elements such as M (J, Ce, etc.) that have been alloyed in advance. is pearlite, but the base structure can be changed to ferrite by further annealing below the A1 transformation point.
なお以上の説明では第１図、第２図におけるインテーク
バルブシート２とエキゾーストバルブシート３との間の
弁間部４の表面層のみを球状黒鉛鋳鉄層５とするものと
したが、このほかインテークバルブシー１〜２と燃料噴
射孔６との間の部分７やエキゾーストバルブシート３と
燃料噴射孔６との間の部分８、さらには４弁以上の多弁
シリンダヘッドにおけるエキゾーストバルブシート３の
相互間の部分９ヤインテークバルブシート２の相互間の
部分１０においても、表面層の鋳鉄中の黒鉛を球状化し
て、それらの部分を球状黒鉛鋳鉄としＣも良い。In the above explanation, only the surface layer of the valve space 4 between the intake valve seat 2 and the exhaust valve seat 3 in FIGS. 1 and 2 is made of the spheroidal graphite cast iron layer 5, but in addition A portion 7 between the valve seats 1 to 2 and the fuel injection hole 6, a portion 8 between the exhaust valve seat 3 and the fuel injection hole 6, and further between the exhaust valve seats 3 in a multi-valve cylinder head with four or more valves. Also in the part 9 and the part 10 between the intake valve seats 2, graphite in the cast iron of the surface layer is spheroidized, and those parts are made of spheroidal graphite cast iron.
実施例
第１図および第２図に示すようなシリンダヘッドを製造
するにあたり、ＦＣＡｌｌの片状黒鉛鋳鉄からなるシリ
ンダヘッド粗形材を常法に従って鋳造して機械加工した
後、インテークバルブシート２とエキシース１〜バルブ
シート３との間の弁間部４の表面に、ＭＱ−１”ｅ−３
ｉ粉末を供給しながらぞの弁間部４にレーザ光を照射し
てＭＱ−Ｆｅ−３ｉ粉末および弁間部４の表面層を溶融
させ、合金化させた。その合金化層が凝固した後、９０
０″Ｃに再加熱して５時間保持してセメンタイトの分解
および黒鉛の析出を行ない、引続いて７００℃に５時間
保持して基地組織のフェライト化を行なった。EXAMPLE In manufacturing a cylinder head as shown in FIGS. 1 and 2, a cylinder head rough shape made of flake graphite cast iron of FCAll was cast and machined according to a conventional method, and then the intake valve seat 2 and MQ-1"e-3
The MQ-Fe-3i powder and the surface layer of the intervalve part 4 were melted and alloyed by irradiating laser light onto the intervalve part 4 while supplying the i powder. After the alloyed layer solidifies, 90
It was reheated to 0''C and held for 5 hours to decompose cementite and precipitate graphite, and then held at 700C for 5 hours to convert the base structure into ferrite.
その後放冷して仕上げ加工を施した。After that, it was left to cool and was subjected to finishing processing.
このようにして得られたシリンダシートは、弁間部４の
表面層の黒鉛が球状化しており、またその部分の基地組
織はフェライトとなっていることが確認された。In the cylinder sheet thus obtained, it was confirmed that the graphite in the surface layer of the intervalve portion 4 was spheroidized, and that the matrix structure in that portion was ferrite.
以上のようなシリンダヘッドを２５００ＣＣデイーゼル
エンジンに組込み、４４００ ｒｐｆｆｌ、全負荷３０
０［１ｉ間の台上耐久試験を行ない、シリンダヘッドの
弁間部の割れ発生状況を調べた。また比較のためＦＣＡ
ｌｌの片状黒鉛鋳鉄からなる無処理のシリンダヘッド（
弁間部の黒鉛を球状化していないもの）についても同様
な台上耐久試験を行なった。その結果を第３図に示す。The above cylinder head was installed in a 2500CC diesel engine, 4400 rpffl, full load 30
A bench durability test was conducted for 0[1i] to investigate the occurrence of cracks in the valve gap of the cylinder head. Also, for comparison, FCA
Untreated cylinder head made of flake graphite cast iron (
A similar bench durability test was also carried out for the case in which the graphite in the intervalve area was not spheroidized. The results are shown in FIG.
第３図から明らかなように、弁間部の黒鉛を球状化しな
かった比較例のシリンダヘッドと比較し、この発明の実
施例によるシリンダヘッドは、弁間部の割れの発生が約
１７５に減少し、耐久性、信頼性が大幅に向上している
ことが判明した。As is clear from FIG. 3, compared to the cylinder head of the comparative example in which the graphite in the valve gap was not spheroidized, the occurrence of cracks in the valve gap was reduced to about 175 in the cylinder head according to the embodiment of the present invention. It was found that durability and reliability were significantly improved.
発明の効果
以上の説明で明らかなようにこの発明の鋳鉄製シリンダ
ヘッドは、弁間部の鋳鉄組織中の黒鉛が球状化されてお
り、そのため弁間部に亀裂が生じにくく、従来の鋳鉄製
シリンダヘッドと比較して格段に耐久性、信頼性が増し
ている。なお弁間部の球状黒鉛鋳鉄層は片状黒鉛鋳鉄か
らなる母材と一体化していてしかも母材との熱膨張率の
差はほとんどないため、弁間部の球状黒鉛鋳鉄層が母材
から剥離するおそれもない。Effects of the Invention As is clear from the above explanation, the cast iron cylinder head of the present invention has spheroidized graphite in the cast iron structure in the valve gap area, which makes it difficult for cracks to occur in the valve gap area, compared to conventional cast iron cylinder heads. Compared to cylinder heads, it is much more durable and reliable. Note that the spheroidal graphite cast iron layer in the valve gap area is integrated with the base material made of flaky graphite cast iron, and there is almost no difference in thermal expansion coefficient between the valve gap area and the base metal. There is no risk of peeling.
第１図はこの発明のシリンダヘッドの要部を示す略解的
な底面図、第２図は第１図のｎ−Ｉ線における縦断面図
、第３図は実施例における耐久試験結果を示すグラフで
ある。
１・・・シリンダヘッド本体、 ４・・・弁間部、 ５
・・・球状黒鉛鋳鉄層。FIG. 1 is a schematic bottom view showing the main parts of the cylinder head of the present invention, FIG. 2 is a vertical cross-sectional view taken along the line n-I in FIG. 1, and FIG. 3 is a graph showing the durability test results in Examples. It is. 1... Cylinder head body, 4... Valve space, 5
...Spheroidal graphite cast iron layer.
Claims (3)
かつ少なくとも弁間部の表面層の組織中における黒鉛が
局部的に球状化されていることを特徴とする鋳鉄製内燃
機関用シリンダヘッド。(1) The base material of the cylinder head is made of flake graphite cast iron,
A cast iron cylinder head for an internal combustion engine, characterized in that graphite in the structure of the surface layer at least in the valve gap is locally spheroidized.
ライトとされている特許請求の範囲第１項記載の鋳鉄製
内燃機関用シリンダヘッド。(2) The cast iron cylinder head for an internal combustion engine according to claim 1, wherein the base structure in the structure of the surface layer of the valve gap is ferrite.
ライトとされている特許請求の範囲第１項記載の鋳鉄製
内燃機関用シリンダヘッド。(3) The cast iron cylinder head for an internal combustion engine according to claim 1, wherein the base structure in the structure of the surface layer of the intervalve portion is pearlite.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23876186A JPS6393876A (en) | 1986-10-07 | 1986-10-07 | Cylinder head for internal-combustion engine made of cast iron |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23876186A JPS6393876A (en) | 1986-10-07 | 1986-10-07 | Cylinder head for internal-combustion engine made of cast iron |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS6393876A true JPS6393876A (en) | 1988-04-25 |
Family
ID=17034871
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP23876186A Pending JPS6393876A (en) | 1986-10-07 | 1986-10-07 | Cylinder head for internal-combustion engine made of cast iron |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6393876A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH04228253A (en) * | 1990-12-27 | 1992-08-18 | Nissan Motor Co Ltd | Method for reinforce-treating interval between valves in cylinder head |
| JP2012110920A (en) * | 2010-11-24 | 2012-06-14 | Press Kogyo Co Ltd | Method of manufacturing axle case |
-
1986
- 1986-10-07 JP JP23876186A patent/JPS6393876A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH04228253A (en) * | 1990-12-27 | 1992-08-18 | Nissan Motor Co Ltd | Method for reinforce-treating interval between valves in cylinder head |
| JP2012110920A (en) * | 2010-11-24 | 2012-06-14 | Press Kogyo Co Ltd | Method of manufacturing axle case |
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