JPH01301910A - Valve system for four-cycle engine - Google Patents

Valve system for four-cycle engine

Info

Publication number
JPH01301910A
JPH01301910A JP13405788A JP13405788A JPH01301910A JP H01301910 A JPH01301910 A JP H01301910A JP 13405788 A JP13405788 A JP 13405788A JP 13405788 A JP13405788 A JP 13405788A JP H01301910 A JPH01301910 A JP H01301910A
Authority
JP
Japan
Prior art keywords
intake
valve
cam
exhaust
camshaft
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.)
Granted
Application number
JP13405788A
Other languages
Japanese (ja)
Other versions
JP2596972B2 (en
Inventor
Isao Morishita
森下 勲
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Yamaha Motor Co Ltd
Original Assignee
Yamaha Motor Co Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Yamaha Motor Co Ltd filed Critical Yamaha Motor Co Ltd
Priority to JP13405788A priority Critical patent/JP2596972B2/en
Priority to US07/357,474 priority patent/US5070824A/en
Publication of JPH01301910A publication Critical patent/JPH01301910A/en
Priority to US07/735,350 priority patent/US5127380A/en
Application granted granted Critical
Publication of JP2596972B2 publication Critical patent/JP2596972B2/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Abstract

PURPOSE:To make a cylinder head circumference smaller by supporting the nearly central part of a cam shaft by a central bearing, and mounting two suction valves and one exhaust valve on one side of the central bearing, further, mounting one piece each of suction valve and exhaust valve on the other side. CONSTITUTION:The nearly central part of a cam shaft 36 is supported by a central bearing 39. A cam 36b for two suction valves 24, 25, and a cam 36a for one exhaust valve 26, are mounted on the one side of the central bearing 39, further, one cam 36c for a suction valve 23, and one cam 36d for a exhaust valve 27, are mounted on the other side. Thereby, the central bearing is mounted eccentrically in the cam shaft direction so as to make a cylinder head circumference smaller.

Description

【発明の詳細な説明】 〔産業上の利用分野〕 本発明は、例えば自動二輪車用4サイクル単気筒エンジ
ンに採用される動弁装置に関し、特に1本のカム軸で3
本の吸気弁及び2本の排気弁を開閉駆動するようにした
OHCエンジンにおいて、カム軸の中央部も軸支するよ
うにした場合の、シリンダヘッド廻りのコンパクト化に
関する。
DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a valve train employed in, for example, a four-stroke single-cylinder engine for motorcycles, and in particular, the present invention relates to a valve train that is used in a four-stroke single-cylinder engine for motorcycles, and in particular,
This invention relates to making the cylinder head more compact in an OHC engine in which two intake valves and two exhaust valves are driven to open and close, in which the central portion of the camshaft is also pivotally supported.

〔従来の技術〕[Conventional technology]

−mにOHCエンジンの動弁装置は、1本のカム軸を燃
焼室の中央上方を横切るように配置し、該カム軸によっ
てロッカーアームを介して吸気弁と排気弁の両方を開閉
駆動するように構成されている。この場合、排気量が増
加して燃焼室径が大きくなると、吸気弁3本、排気弁2
本というように弁数を増加させる場合がある。このよう
にした場合はカム軸が長くなり、その結果、必要な剛性
を確保するためカム軸径が増大し、重量増加の問題が生
じ易い、そのため、従来、上記カム軸の左。
-The valve train of an OHC engine has a single camshaft placed across the upper center of the combustion chamber, and the camshaft opens and closes both the intake valve and the exhaust valve via a rocker arm. It is composed of In this case, if the displacement increases and the combustion chamber diameter increases, there will be three intake valves and two exhaust valves.
There are cases where the number of words is increased, such as in books. In this case, the camshaft becomes longer, and as a result, the camshaft diameter increases to ensure the necessary rigidity, which tends to cause the problem of increased weight.

右端部だけでなくその中央部も軸支することにより、カ
ム軸の小径化を図った例がある(例えば特開昭57−1
02506号公報参照)。
There are examples of reducing the diameter of the camshaft by supporting not only the right end but also the center (for example, Japanese Patent Laid-Open No. 57-1
(See Publication No. 02506).

〔発明が解決しようとする間理点〕[The problem that the invention attempts to solve]

ところで上記カム軸の中央部も軸支する場合は、中央軸
受の左、右外側に吸気弁、排気弁駆動用カムを形成する
こととなるが、このカムが中央軸受の幅分だけ外側に押
しやられ、それだけシリンダヘッド廻りが大型化してし
まう懸念がある。特に、吸気弁3本、排気弁2本の5バ
ルブエンジンのように弁数が多い場合は、この問題が顕
著となり、従って各弁駆動用カム、中央軸受等の配置設
計が □重要となる。
By the way, if the center part of the camshaft is also supported, intake valve and exhaust valve driving cams will be formed on the left and right sides of the center bearing, but this cam will push outward by the width of the center bearing. There is a concern that the size of the cylinder head will increase accordingly. This problem becomes particularly noticeable when the number of valves is large, such as in a five-valve engine with three intake valves and two exhaust valves, and therefore the layout design of each valve drive cam, central bearing, etc. becomes important.

そこで本発明は、このような5バルブエンジンにおける
実情に鑑み、中央軸受、及び各弁駆動用カムの配置を最
適化することにより、シリンダヘッド廻りをコンパクト
化できる4サイクルエンジンの動弁装置を提供すること
を目的としている。
Therefore, in view of the actual situation in 5-valve engines, the present invention provides a valve train for a 4-stroke engine that can make the cylinder head area more compact by optimizing the arrangement of the central bearing and the cams for driving each valve. It is intended to.

〔問題点を解決するための手段〕[Means for solving problems]

本発明は、3本の吸気弁と2本の排気弁を1本のカム軸
でロッカーアームアームを介して開閉駆動するようにし
た4サイクルエンジンの動弁装置において、上記カム軸
を燃焼室の略中央上方を横切るように配置するとともに
、該カム軸の略中央部を中央軸受で軸支し、該中央軸受
の一側に2本の吸気弁用第1吸気カムと1本の排気弁用
第1排気カムを形成し、他側に1本の吸気弁用第2吸気
カムと1本の排気弁用第2排気カムを形成するとともに
、上記中央軸受を燃焼室中心に対して上記第2吸気、排
気カム側に偏位させたことを特徴としている。
The present invention provides a valve operating system for a four-cycle engine in which three intake valves and two exhaust valves are driven to open and close by one camshaft via a rocker arm arm, in which the camshaft is connected to a combustion chamber. The camshaft is arranged so as to cross substantially above the center, and the substantially center portion of the camshaft is supported by a central bearing, and two first intake cams for intake valves and one first intake cam for exhaust valves are provided on one side of the central bearing. A first exhaust cam is formed, and one second intake cam for an intake valve and one second exhaust cam for an exhaust valve are formed on the other side, and the central bearing is aligned with the second exhaust cam with respect to the center of the combustion chamber. It is characterized by being deviated towards the intake and exhaust cam sides.

〔作用〕[Effect]

本発明に係る動弁装置によれば、カム軸の中央部を中央
軸受で軸支したので、カム軸を大径にする必要はなく、
カム軸を軽量化できる。そしてこの中央軸受の一側に、
吸気弁2本用第1吸気カム及び排気弁1本用第1排気カ
ムを、他側に吸気弁1本用第2吸気カム及び排気弁1本
用第2排気カムを形成したので、5本の弁に対して4つ
のカムで済み、それだけカム軸が短縮され、さらに吸気
弁、排気弁とも1本だけ配置されていることから比較的
スペースに余裕のある第2吸気、排気カム側に中央軸受
を偏位させたので、空きスペースを有効利用でき、これ
らの結果シリンダヘッド廻りをコンパクト化できる。
According to the valve train according to the present invention, since the central portion of the camshaft is supported by the central bearing, there is no need to increase the diameter of the camshaft.
The weight of the camshaft can be reduced. And on one side of this central bearing,
A first intake cam for two intake valves and a first exhaust cam for one exhaust valve were formed on the other side, and a second intake cam for one intake valve and a second exhaust cam for one exhaust valve were formed on the other side, so five cams were formed. Only four cams are required for the valve, and the camshaft is shortened accordingly.Furthermore, since there is only one intake valve and one exhaust valve, the second intake and exhaust cams have comparatively more space, so the camshaft is shortened accordingly. Since the bearing is offset, empty space can be used effectively, and as a result, the area around the cylinder head can be made more compact.

また、本発明では中央軸受部が多弁で囲まれた中央部に
位置し、これらの弁と干渉することがないので、該カム
軸の高さ位置を低くでき、この点からもシリンダヘッド
廻りをコンパクト化できる。
In addition, in the present invention, the central bearing portion is located in the center surrounded by multiple valves and does not interfere with these valves, so the height of the camshaft can be lowered, and from this point of view as well, the cylinder head area can be improved. Can be made compact.

〔実施例〕〔Example〕

以下、本発明の実施例を図について説明する。 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

第1図ないし第4図は本発明の一実施例による4サイク
ルエンジンの動弁装置を説明するための図である。
1 to 4 are diagrams for explaining a valve train for a four-stroke engine according to an embodiment of the present invention.

図において、1は本実施例装置が適用された4サイクル
エンジンを搭載した自動二輪車であり、これの車体フレ
ーム2の前端には、下端で前輪3を軸支する前フオーク
4が軸支され、中央下端には、後端で後輪5を軸支する
後アーム6が上下に揺動自在に枢支されており、さらに
後部には大型の燃料タンク7が、その上側にはシート8
がそれぞれ搭載されている。なお、62〜64.58は
それぞれオイルタンク、ラジェータ、エアクリーナ、気
化器である。
In the figure, reference numeral 1 denotes a motorcycle equipped with a four-stroke engine to which the device of this embodiment is applied, and a front fork 4 that pivotally supports a front wheel 3 at its lower end is supported at the front end of a body frame 2 of this vehicle. At the lower center end, a rear arm 6 that pivotally supports the rear wheel 5 at the rear end is pivoted so as to be able to swing up and down.Furthermore, at the rear is a large fuel tank 7, and above it is a seat 8.
are installed in each. Note that 62 to 64.58 are an oil tank, a radiator, an air cleaner, and a carburetor, respectively.

そして上記車体フレーム2の前部には水冷式4サイクル
単気筒のエンジンユニット9が搭載されている。このエ
ンジンユニット9は、シリンダIO,シリンダへラド1
1.及びヘンドカバー12をクランクケース14上に積
層して構成されている。
A water-cooled four-stroke single-cylinder engine unit 9 is mounted on the front portion of the vehicle body frame 2. This engine unit 9 has a cylinder IO, a cylinder rad 1
1. and a hend cover 12 are stacked on a crankcase 14.

上記シリンダ10は水冷ジャケット10aを有するシリ
ンダ本体10b内に円筒状のシリンダライナ10cを圧
入してなり、該シリンダライナ1oC内にはピストン1
4が摺動自在に挿入されている。
The cylinder 10 is formed by press-fitting a cylindrical cylinder liner 10c into a cylinder body 10b having a water-cooled jacket 10a, and a piston 1 is fitted into the cylinder liner 1oC.
4 is slidably inserted.

また、上記シリンダヘッド11の下面の略中夫には上記
ピストン14の上面とで燃焼室15を形成する燃焼室凹
部16が凹設されている。この燃焼室凹部16の周縁に
沿う略円周上に、3つの吸気弁開口17〜19及び2つ
の排気弁開口20゜21が形成されている。また、この
燃焼室凹部16の中央にはプラグ孔22が形成されてお
り、このプラグ孔22は、点火プラグを外方から装着す
るためのプラグ挿入孔29によって外方に導出されてい
る。このプラグ挿入孔29は周壁で囲まれた筒状をなし
ており、シリンダヘッド11.ヘッドカバー12に直線
状に形成されたヘッド側挿入孔29a、カバー側挿入孔
29bで構成されている。また上記プラグ孔22には点
火プラグ30が装着されている。
Further, a combustion chamber recess 16 that forms a combustion chamber 15 with the upper surface of the piston 14 is provided substantially in the center of the lower surface of the cylinder head 11 . Three intake valve openings 17 to 19 and two exhaust valve openings 20.degree. 21 are formed approximately on the circumference along the periphery of the combustion chamber recess 16. Further, a plug hole 22 is formed in the center of this combustion chamber recess 16, and this plug hole 22 is led out to the outside by a plug insertion hole 29 for installing a spark plug from the outside. This plug insertion hole 29 has a cylindrical shape surrounded by a peripheral wall, and has a cylindrical shape surrounded by a peripheral wall. The head cover 12 includes a head-side insertion hole 29a and a cover-side insertion hole 29b formed in a straight line. Further, a spark plug 30 is installed in the plug hole 22.

上記3つの吸気弁開口17〜19はこのシリンダヘッド
11に形成された1つの共用吸気通路31に合流した後
、車両前後方向後側に導出されており、また、2つの排
気弁開口20.21はそれぞれ別個の排気通路32.3
3によって前側に導出されている。そしてこの各排気通
路32,33゜吸気通路31.及び上記燃焼室凹部16
の周囲にはヘッド側水冷ジャケット19が形成されてお
り、該ジャケット19は上記シリンダ側水冷ジャケッ)
10aと連通している。
The three intake valve openings 17 to 19 merge into one common intake passage 31 formed in the cylinder head 11, and then lead out to the rear side in the longitudinal direction of the vehicle, and the two exhaust valve openings 20.21 are each separate exhaust passage 32.3
3 leads to the front side. Each exhaust passage 32, 33° intake passage 31. and the combustion chamber recess 16
A head side water cooling jacket 19 is formed around the cylinder side water cooling jacket 19.
It communicates with 10a.

上記吸気弁開口17〜19及び排気弁開口20゜21に
は、これを開閉する吸気弁23〜25及び排気弁26.
27の弁板が配置されている。この各喚、排気弁23〜
27の弁ステム23a〜27aは吸気、排気通路31〜
33の天井壁部を貫通してこのシリンダヘッド11の上
側に突出している。この場合に弁ステム24aは23a
、25aに比べてより起立しており、上記プラグ挿入孔
29は排気弁26.27の間に位置し、かつ該両排気弁
26.27と平行になっている。また吸気弁ステム2.
3a〜25aの突出端及び排気弁ステム25a、27a
の突出端はそれぞれ第1図に示すように、平行な直線A
、 B上に位置している。また各弁ステム23a〜27
aの上端に取り付けられたバネストッパ34とシリンダ
ヘッド11に装着されたばね座11aとの間には付勢ば
ね35が配設されており、これにより答弁23〜27は
各弁開口17〜21を閉じるように付勢されている。
The intake valve openings 17 to 19 and the exhaust valve openings 20 and 21 have intake valves 23 to 25 and an exhaust valve 26 that open and close them.
27 valve plates are arranged. Each of these exhaust valves 23~
27 valve stems 23a to 27a are the intake and exhaust passages 31 to 27.
It penetrates the ceiling wall portion of 33 and projects above this cylinder head 11. In this case, the valve stem 24a is 23a
, 25a, and the plug insertion hole 29 is located between the exhaust valves 26.27 and parallel to both exhaust valves 26.27. Also, the intake valve stem 2.
Projecting ends of 3a to 25a and exhaust valve stems 25a, 27a
As shown in Figure 1, each of the projecting ends of
, is located on B. In addition, each valve stem 23a to 27
A biasing spring 35 is disposed between a spring stopper 34 attached to the upper end of a and a spring seat 11a attached to the cylinder head 11, so that the valves 23 to 27 close the respective valve openings 17 to 21. It is energized as follows.

そして上記直線A、B関には、1本のカム軸36がこれ
らと平行に、かつ上記燃焼室15の平面視中心Cより[
12だけ後側にずれた位置を横切るように配設されてい
る。このカム軸36の、車両前方(第1図右方)に見て
左、右両端及び中央はそれぞれ左、右軸受部37.38
、及び中央軸受部39で支持されており、該中央軸受部
39は上記中心Cから右方にDlだけ偏位している。そ
してこの中央軸受39は上記中央の吸気弁24.プラグ
挿入孔29間に位置し、かつ両者と対向している。
A camshaft 36 is parallel to the straight lines A and B, and is located from the center C of the combustion chamber 15 in plan view.
It is arranged so as to cross a position shifted by 12 points to the rear side. The left and right ends and center of this camshaft 36 when viewed from the front of the vehicle (right side in Figure 1) are left and right bearing portions 37 and 38, respectively.
, and a central bearing portion 39, which is offset from the center C to the right by Dl. This central bearing 39 is connected to the central intake valve 24. It is located between the plug insertion holes 29 and faces both of them.

またこのカム軸36の左軸受部37からの突出部には駆
動スプロケット40が取り付けられており、これはカム
チェン41でクランク軸と連結されている。
Further, a driving sprocket 40 is attached to a protruding portion of the camshaft 36 from the left bearing portion 37, and this is connected to the crankshaft by a cam chain 41.

また、上記カム軸36の、軸受部37.39間には第1
排気、吸気カム36a、36bが、軸受部39.38間
には第2吸気、排気カム36C936dが一体形成され
ており、この第1吸気カム36bは、吸気弁24.25
の両方を駆動するためのものであり、該両弁24,25
の略中間に位置している。そしてこの各カム36a〜3
6dにはそれぞれ第1排気、吸気ロッカーアーム42゜
43、第2吸気、排気ロッカー了−ム44.45の摺動
部428〜45aが摺接している。この両吸気ロッカー
アーム43,44.及び両排気ロッカーアーム42.4
5はそれぞれカム軸36と平行に配置された吸気、排気
ロッカーアーム軸46゜47によって揺動自在に支持さ
れている。
Further, a first
A second intake and exhaust cam 36C936d is integrally formed between the exhaust and intake cams 36a and 36b, and the bearing portion 39.38, and this first intake cam 36b is connected to the intake valve 24.25.
Both valves 24, 25
It is located approximately in the middle. And each of these cams 36a to 3
Sliding portions 428 to 45a of first exhaust and intake rocker arms 42 and 43, and second intake and exhaust rocker arms 44 and 45 are in sliding contact with 6d, respectively. Both intake rocker arms 43, 44. and both exhaust rocker arms 42.4
5 are swingably supported by intake and exhaust rocker arm shafts 46 and 47, respectively, which are arranged parallel to the camshaft 36.

上記第1吸気ロツカーアーム43は2本の吸気弁24.
25を駆動するためのものであり、他のロッカーアーム
はそれぞれ1本の弁用である。そのため上記第1吸気ロ
ツカーアーム43の他端側には2つの作動部43b、4
3cが分岐形成されており、このロッカーアーム43は
、該前作動部43b、43cを結ぶ線を底辺とし、摺動
部43aを頂点とする概略二等辺三角形になっている。
The first intake rocker arm 43 has two intake valves 24.
25, and the other rocker arms are for one valve each. Therefore, on the other end side of the first intake rocker arm 43, there are two actuating parts 43b, 4.
3c is branched, and the rocker arm 43 has a substantially isosceles triangular shape with the line connecting the front actuating parts 43b and 43c as the base and the sliding part 43a as the apex.

また他のロッカーアームの他端側にはそれぞれ1つの作
動部が形成されている。これらの作動部42b〜45b
及び42cには調整ボルト48が螺装されており、この
各調整ボルト48は上記各弁ステム23a〜27aの上
端に当接している。
Further, one operating portion is formed at the other end of each of the other rocker arms. These operating parts 42b to 45b
and 42c are threaded with adjustment bolts 48, each of which is in contact with the upper end of each of the valve stems 23a to 27a.

上記左、右軸受部37.38及び中央軸受部39は、シ
リンダヘッド11側に形成された下半部とベンドカバー
12側に形成された上半部とからなる2分割構造になっ
ている。そして、中央軸受部39の下半部39aの前、
後部分は、それぞれ上記ヘッド側挿入孔29aの周壁、
上記共用吸気通路31の天井壁31aと一体に連結され
ている。
The left and right bearing portions 37, 38 and the center bearing portion 39 have a two-part structure consisting of a lower half formed on the cylinder head 11 side and an upper half formed on the bend cover 12 side. In front of the lower half 39a of the central bearing part 39,
The rear portion includes a peripheral wall of the head side insertion hole 29a, and
It is integrally connected to the ceiling wall 31a of the shared intake passage 31.

また、この連結部にはシリンダヘッド11#ヘツドカバ
ー12とを締め付は固定する締結ボルト12bが挿着さ
れている。このボルト12bは該ヘッドカバー12に一
体形成された懸架用フランして車体フレーム2のテンシ
ョンバイブ2aに懸架されている。
Further, a fastening bolt 12b for tightening and fixing the cylinder head 11# and the head cover 12 is inserted into this connecting portion. This bolt 12b serves as a suspension flange integrally formed with the head cover 12 and is suspended from a tension vibe 2a of the vehicle body frame 2.

次に本実施例の作用効果について説明する。Next, the effects of this embodiment will be explained.

本実施例の動弁装置では、クランク軸によりカムチェン
41を介してカム軸36が回転駆動されると、各カム3
6a〜36dによって各ロッカーアーム42〜45が揺
動し、各吸気、排気弁23〜27が開閉駆動されること
となる。
In the valve train of this embodiment, when the camshaft 36 is rotationally driven by the crankshaft via the cam chain 41, each cam 3
6a to 36d, each rocker arm 42 to 45 swings, and each intake and exhaust valve 23 to 27 is driven to open and close.

このような動作を行う動弁装置では、1気筒当たりの弁
数が例えば5本というように多い場合はカム軸の全長が
長くなり、カム軸の剛性を確保するためカム軸径が大き
くなって重量増加の問題が生じ易い、これに対して本実
施例では、カム軸36を左、右軸受部37.38だけで
なく、中央軸受部39でも支持するようにしたので、カ
ム軸径を細くでき、重量増加を防止できる。
In a valve train that performs this type of operation, when the number of valves per cylinder is large, such as five, the overall length of the camshaft becomes longer, and the camshaft diameter becomes larger to ensure the rigidity of the camshaft. In this embodiment, the camshaft 36 is supported not only by the left and right bearing parts 37 and 38 but also by the center bearing part 39, which tends to cause the problem of increased weight, so that the camshaft diameter can be reduced. It is possible to prevent weight increase.

また、本実施例のように、中央軸受部を設け、しかも弁
数が5本と多くなると、カム位置、中央軸受位置等の設
計の如何によっては、カム軸が長くなり、シリンダヘッ
ド廻りが大型化する恐れがある。これに対して本実施例
では、2本の吸気弁24.25を1つのカム36bで駆
動するようにしたので、5本の弁23〜27に対して4
つのカム36a〜3dで済み、それだけカム軸36の軸
長を短縮でき、動弁装置、ひいてはシリンダヘッド11
をコンパクト化できる。しかもこの場合、中央軸受部3
9を、燃焼室中心Cから、弁数が2本と少なく、スペー
スに比較的余裕のある右側にDlだけ偏心させたので、
余裕スペースを有効利用でき、この点からもシリンダヘ
ッド11廻りを、コンパクト化できる。また、上述のよ
うに2本の吸気弁を1つのカムで駆動するようにしたの
で、ロッカーアーム数も少なくて浅み、さらにこのロン
カーアーム43は、上記カム36bが両弁24゜25の
略中間に位置しているので、二等辺三角形となって、応
力バランスがよいとともに、軽量化できる。
In addition, if a central bearing is provided and the number of valves is increased to five, as in this example, the camshaft will become longer and the cylinder head will become larger depending on the design of the cam position, central bearing position, etc. There is a risk of becoming On the other hand, in this embodiment, the two intake valves 24 and 25 are driven by one cam 36b, so there are four intake valves for the five valves 23 to 27.
Only one cam 36a to 3d is required, and the axial length of the camshaft 36 can be shortened accordingly.
can be made compact. Moreover, in this case, the central bearing part 3
9 was offset by Dl from the center C of the combustion chamber to the right side, where the number of valves is small at 2 and there is relatively more space.
The extra space can be used effectively, and from this point of view as well, the area around the cylinder head 11 can be made more compact. Furthermore, since the two intake valves are driven by one cam as described above, the number of rocker arms is small and shallow. Since it is located approximately in the middle, it forms an isosceles triangle, resulting in good stress balance and weight reduction.

そして上記中央軸受部39を中央の吸気弁24とプラグ
挿入孔29との間に配置するとともに、該中央軸受部3
9の下半部39aの前、後部をそれぞれヘッド側挿入孔
29aの周壁、共用吸気通路31の天井壁31aに連結
したので、該中央軸受部39の剛性を、例えば該下半部
をオーバーハング状に形成した場合に比べて大幅に向上
できる。
The central bearing portion 39 is disposed between the central intake valve 24 and the plug insertion hole 29, and the central bearing portion 39 is disposed between the central intake valve 24 and the plug insertion hole 29.
Since the front and rear portions of the lower half portion 39a of the central bearing portion 39 are connected to the peripheral wall of the head side insertion hole 29a and the ceiling wall 31a of the shared intake passage 31, respectively, the rigidity of the central bearing portion 39 can be increased by, for example, overhanging the lower half portion. This can be significantly improved compared to the case where it is formed in a shape.

しかもこの剛性向上に際し、下半部39aの前。Moreover, when improving this rigidity, the front of the lower half portion 39a.

後部を近接するヘッド側挿入孔29aの周壁、吸気通路
31の天井壁31Mに接続するだけであるから、シリン
ダヘッド11に余分の軸受用壁部を形成する必要はなく
、該シリンダヘッド11の重量増加の問題が生じること
もない。
Since the rear portion is simply connected to the peripheral wall of the adjacent head-side insertion hole 29a and the ceiling wall 31M of the intake passage 31, there is no need to form an extra bearing wall on the cylinder head 11, and the weight of the cylinder head 11 is reduced. There is no problem of increase.

また、本実施例ではカム軸36が5本の弁の間を遺り、
中央軸受39がこれらと干渉することはないから、カム
軸36を低く配置でき、この点がらもシリンダヘッド1
1廻りをコンパクト化できる。
In addition, in this embodiment, the camshaft 36 remains between the five valves,
Since the central bearing 39 does not interfere with these, the camshaft 36 can be placed low, and in this respect, the cylinder head 1
One rotation can be made more compact.

また、本実施例では、カム軸36を燃焼室中心Cに対し
て後側にD2だけ偏心させるととともに、この偏心によ
ってスペース的に有利となった前側にプラグ挿入孔29
を燃焼室中心Cに向けて形成し、さらに排気ロッカーア
ーム軸47に点火プラグ挿入時の干渉を防止する切欠部
47aを形成したので、構造を複雑化させることなく点
火プラグ30をより垂直に配置できる。ちなみに、従来
はこの垂直性を向上させるために、ロッカーアーム軸を
2分割したり、該軸に貫通孔を形成したりしており、部
品点数の増加、構造の複雑化等の問題が生じていた。
In addition, in this embodiment, the camshaft 36 is eccentric to the rear side by D2 with respect to the center C of the combustion chamber, and the plug insertion hole 29 is located at the front side, which is advantageous in terms of space due to this eccentricity.
is formed toward the center C of the combustion chamber, and a notch 47a is formed in the exhaust rocker arm shaft 47 to prevent interference when the spark plug is inserted, so the spark plug 30 can be arranged more vertically without complicating the structure. can. By the way, in the past, in order to improve this verticality, the rocker arm shaft was divided into two parts or a through hole was formed in the shaft, which resulted in problems such as an increase in the number of parts and a complicated structure. Ta.

また、本実施例では、ロッカーアーム軸47の切欠部4
7a面がカバー側挿入孔29bの内周壁の一部を構成し
ており、スペースの有効利用が図れ、かつ軽量化が図れ
る。
In addition, in this embodiment, the notch 4 of the rocker arm shaft 47
The surface 7a constitutes a part of the inner circumferential wall of the cover-side insertion hole 29b, allowing for effective use of space and weight reduction.

さらにまた、本実施例では、シリンダヘッド11とヘッ
ドカバー12との締結ボルト12bの挿着部付近を車体
フレーム2に懸架するようにしたので、それだけ強度を
向上できる。
Furthermore, in this embodiment, since the vicinity of the insertion portion of the fastening bolt 12b between the cylinder head 11 and the head cover 12 is suspended on the vehicle body frame 2, the strength can be improved accordingly.

なお、上記実施例では自動二輪車用エンジンについて説
明したが、本発明はこれ以外のエンジンにも勿論適用で
きる。
In addition, although the above-mentioned embodiment explained an engine for a two-wheeled motor vehicle, the present invention can of course be applied to engines other than this.

〔発明の効果〕〔Effect of the invention〕

以上のように本発明に係る4サイクルエンジンの動弁装
置によれば、カム軸を燃焼室中央を横切るように配置し
てその中央部を中央軸受で軸支し、該中央軸受の一側に
2本の吸気弁用カム、1本の排気弁用カムをそれぞれ形
成し、他側に吸気弁1本、排気弁1本用カムを形成しす
るとともに、中央軸受を上記他側方向に偏位させたので
、弁数が2本と少なく、スペース的に比較的余裕のある
部分を利用して中央軸受を配置でき、シリンダヘッド廻
りをコンパクト化できる効果がある。
As described above, according to the valve train for a four-stroke engine according to the present invention, the camshaft is arranged to cross the center of the combustion chamber, the center part of the camshaft is supported by the center bearing, and the camshaft is supported on one side of the center bearing. Two cams for intake valves and one cam for exhaust valves are formed on the other side, and cams for one intake valve and one exhaust valve are formed on the other side, and the central bearing is offset in the direction of the other side. As a result, the number of valves is as small as two, and the central bearing can be placed using a relatively free space, which has the effect of making the cylinder head more compact.

【図面の簡単な説明】[Brief explanation of the drawing]

第1図ないし第4図は本発明の一実施例による動弁装置
を説明するための図であり、第1図はそのヘッドカバー
を外した状態の平面図、第2図181は第1図のm、−
n、線断面側面図、第2図山)は懸架状態を示す断面図
、第3図はシリンダヘッドの底面図、第4図は本実施例
装置が適用された自動二輪車の左側面図である。 図において、9は4サイクルエンジン、15は燃焼室、
23〜25は3本の吸気弁、26.27は2本の排気弁
、36はカム軸、36a、36dは1本の排気弁用筆1
.第2排気カム、36bは2本の吸気弁用第1吸気カム
、36cは1本の吸気弁用第2吸気カム、39は中央軸
受、42〜45はロッカーアーム、Cは燃焼室中心、D
lは中央軸受の偏位置である。 特許出願人  ヤマハ発動機株式会社 代理人    弁理士 下 市  努 第1図 14 10c 第 2  し4 (¥02) (b) 第3図
1 to 4 are diagrams for explaining a valve train according to an embodiment of the present invention. FIG. 1 is a plan view of the valve train with the head cover removed, and FIG. m, -
Figure 2 is a cross-sectional view showing a suspended state, Figure 3 is a bottom view of the cylinder head, and Figure 4 is a left side view of a motorcycle to which the device of this embodiment is applied. . In the figure, 9 is a 4-stroke engine, 15 is a combustion chamber,
23 to 25 are three intake valves, 26.27 are two exhaust valves, 36 is a camshaft, and 36a and 36d are one exhaust valve brush 1.
.. 2nd exhaust cam, 36b is the first intake cam for two intake valves, 36c is the second intake cam for one intake valve, 39 is the center bearing, 42 to 45 are rocker arms, C is the center of the combustion chamber, D
l is the eccentric position of the central bearing. Patent Applicant Yamaha Motor Co., Ltd. Agent Patent Attorney Tsutomu Shimoichi Figure 1 14 10c 2 4 (¥02) (b) Figure 3

Claims (1)

【特許請求の範囲】[Claims] (1)3本の吸気弁と2本の排気弁を1本のカム軸でロ
ッカーアームアームを介して開閉駆動するようにした4
サイクルエンジンの動弁装置において、上記カム軸を燃
焼室の略中央上方を横切るように配置し、該カム軸の略
中央部を中央軸受で軸支するとともに、該中央軸受の一
側に2本の吸気弁用第1吸気カムと1本の排気弁用第1
排気カムを形成し、他側に1本の吸気弁用第2吸気カム
と1本の排気弁用第2排気カムを形成し、さらに上記中
央軸受を燃焼室中心に対して上記第2吸気、排気カム側
に偏位させたことを特徴とする4サイクルエンジンの動
弁装置。
(1) Three intake valves and two exhaust valves are driven to open and close by one camshaft via a rocker arm 4
In a valve train for a cycle engine, the camshaft is arranged so as to cross above the substantially center of the combustion chamber, the substantially center portion of the camshaft is supported by a central bearing, and two camshafts are provided on one side of the central bearing. The first intake cam for one intake valve and the first intake cam for one exhaust valve.
an exhaust cam is formed, one second intake cam for an intake valve and one second exhaust cam for an exhaust valve are formed on the other side, and the central bearing is arranged with respect to the center of the combustion chamber, and the second intake cam is formed on the other side. A valve train for a four-stroke engine, characterized by being biased toward the exhaust cam side.
JP13405788A 1988-05-30 1988-05-30 Valve system for 4-cycle engine Expired - Lifetime JP2596972B2 (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
JP13405788A JP2596972B2 (en) 1988-05-30 1988-05-30 Valve system for 4-cycle engine
US07/357,474 US5070824A (en) 1988-05-30 1989-05-26 Combustion chamber and valve operating mechanism for multi-valve engine
US07/735,350 US5127380A (en) 1988-05-30 1991-07-24 Combustion chamber and valve operating mechanism for multi-valve engine

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP13405788A JP2596972B2 (en) 1988-05-30 1988-05-30 Valve system for 4-cycle engine

Publications (2)

Publication Number Publication Date
JPH01301910A true JPH01301910A (en) 1989-12-06
JP2596972B2 JP2596972B2 (en) 1997-04-02

Family

ID=15119358

Family Applications (1)

Application Number Title Priority Date Filing Date
JP13405788A Expired - Lifetime JP2596972B2 (en) 1988-05-30 1988-05-30 Valve system for 4-cycle engine

Country Status (1)

Country Link
JP (1) JP2596972B2 (en)

Also Published As

Publication number Publication date
JP2596972B2 (en) 1997-04-02

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