JPS63162911A - Autodecompression device for engine - Google Patents
Autodecompression device for engineInfo
- Publication number
- JPS63162911A JPS63162911A JP31325886A JP31325886A JPS63162911A JP S63162911 A JPS63162911 A JP S63162911A JP 31325886 A JP31325886 A JP 31325886A JP 31325886 A JP31325886 A JP 31325886A JP S63162911 A JPS63162911 A JP S63162911A
- Authority
- JP
- Japan
- Prior art keywords
- cam
- camshaft
- decompression
- decompression cam
- engagement
- 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
Links
- 238000007906 compression Methods 0.000 claims abstract description 40
- 230000006835 compression Effects 0.000 claims abstract description 39
- 230000006837 decompression Effects 0.000 claims description 93
- 238000002485 combustion reaction Methods 0.000 abstract description 16
- 230000001105 regulatory effect Effects 0.000 description 2
- 230000007423 decrease Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
Abstract
Description
【発明の詳細な説明】 〔産業上の利用分野〕 本発明は、エンジンのデコンプ装置に関する。[Detailed description of the invention] [Industrial application field] The present invention relates to an engine decompression device.
このデコンプ装置は、エンジンの始動時において、通常
に設けられた弁開閉装置とは別の弁開閉装置により弁を
開いて燃焼室内の最初の圧縮行程の圧力を減圧し、２回
目の圧縮行程までにクランク軸を十分に回転させて回転
慣性力を増大させ、この力を利用してエンジンの始動性
を向上させるもので、例えば、特開昭５９−７４３１７
号公報に示されるような手動式のものや、特開昭６０−
４０７１５号公報に示されるように、ガバナを使用した
オートデコンプ装置がある。When the engine is started, this decompression device opens the valve using a valve opening/closing device that is separate from the normally installed valve opening/closing device to reduce the pressure in the first compression stroke in the combustion chamber, and continues until the second compression stroke. The crankshaft is sufficiently rotated to increase the rotational inertia force, and this force is used to improve the startability of the engine.
The manual type as shown in the publication, the JP-A-60-
As shown in Japanese Patent No. 40715, there is an auto decompression device using a governor.
しかし、前者の場合は手動式であるところからその操作
が煩わしく、また、後者の場合はその構造が複雑で部品
点数も多いので組付やメンテナンス等が面倒であった。However, in the former case, the operation is cumbersome because it is a manual type, and in the latter case, the structure is complex and the number of parts is large, making assembly and maintenance troublesome.
そこで本発明は、簡単な構造で部品点数も少なく、かつ
確実に自動的に弁を開き組付やメンテナンス等の容易な
オートデコンプ装置を提供することを目的としている。SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an auto-decompression device which has a simple structure, has a small number of parts, and which automatically opens a valve reliably and is easy to assemble and maintain.
上記目的達成のため本発明は、シリンダヘッドに設けた
吸・排気弁をカムシャフトにそれぞれ固設した動弁カム
にて作動させるエンジンにおいて、前記動弁カムに近接
して、カムシャフトの逆転時に一方向クラッチを介して
カムシャフトと一体に回転して前記吸・排気弁のいずれ
か一方を作動する逆転用デコンプカムを設け、該逆転用
デコンプカムと前記動弁カムとの間に、動弁カムのベー
ス円よりやや小径のベース円と、該ベース円の一側に設
けたウェイト部と、前記カムシャフトの径よりは大径の
内径とを有するデコンプ用カムをカムシャフトに遊嵌し
、該カムシャフトには、前記隣接する動弁カムの排気行
程部の位置に前記デコンプ用カムとの間に配設される係
合部材を嵌合する係合凹部を形成し、これと対向する圧
縮行程部の位置にデコンプ用カムに係合する係合突起を
設け、一方、前記デコンプ用カムの内径には、ウェイト
部内側に前記係合部材に係合する係合凹部を設け、これ
と対向する位置に前記カムシャフトに設けた係合突起に
係合する溝部を設け、該デコンプ用カムの係合凹部とカ
ムシャフトの係合凹部との間に係合部材を配設して、デ
コンプ用カムを前記隣接する動弁カムの排気行程部方向
と圧縮行程部方向には移動可能で、かつ、動弁カムと一
体回転可能に設け、カムシャフトとデコンプ用カムとの
間にデコンプ用カムを圧縮行程部方向と膨張行程部方向
の２方向に付勢する弾発部材を縮設し、前記デコンプ用
カムの溝部の吸入行程部側に前記カムシャフトの係合突
起に係合してデコンプ用カムのべ−ス円を動弁カムの圧
縮行程部のベース円より突出させて前記板・排気弁のい
ずれか一方を作動させる段部を溝部に連続して形成した
ことを特徴としている。To achieve the above object, the present invention provides an engine in which intake and exhaust valves provided in a cylinder head are operated by valve drive cams fixedly attached to a camshaft. A reversing decompression cam is provided which rotates together with the camshaft via a one-way clutch to operate one of the intake and exhaust valves, and a reversing decompression cam is provided between the reversing decompression cam and the valve cam. A decompression cam having a base circle having a slightly smaller diameter than the base circle, a weight portion provided on one side of the base circle, and an inner diameter larger than the diameter of the camshaft is loosely fitted onto the camshaft, and the cam An engagement recess into which an engagement member disposed between the decompression cam and the decompression cam is fitted is formed in the exhaust stroke part of the adjacent valve drive cam, and a compression stroke part facing the engagement recess is formed in the shaft. An engagement protrusion that engages with the decompression cam is provided at a position, and an engagement recess that engages with the engagement member is provided on the inside of the weight part on the inner diameter of the decompression cam, and an engagement recess that engages with the engagement member is provided at a position opposite to this. a groove that engages with an engagement protrusion provided on the camshaft; an engagement member is disposed between the engagement recess of the decompression cam and the engagement recess of the camshaft; The decompression cam is provided between the camshaft and the decompression cam so as to be movable in the exhaust stroke direction and the compression stroke direction of the adjacent valve train cam, and to be able to rotate integrally with the valve train cam. A resilient member is compressed and biased in two directions, ie, in the direction of the decompression cam and in the direction of the expansion stroke, and engages with the engagement protrusion of the camshaft on the suction stroke side of the groove of the decompression cam, thereby pushing the decompression cam toward the suction stroke. The present invention is characterized in that a stepped portion is formed continuously in the groove portion so that the base circle protrudes from the base circle of the compression stroke portion of the valve drive cam to operate either the plate or the exhaust valve.
このように構成することにより、エンジンの停止時にピ
ストンが圧縮行程で一旦止まった後、その圧縮圧力でピ
ストンが下降し、クランクシャフト及びカムシャフトを
逆転させて停止した場合には、一方向クラッチがカムシ
ャフトに係合して逆転用デコンプカムがカムシャフトと
一体に回転して弁を作動し、燃焼室内の圧縮圧力を減少
し、また、デコンプ用カムは、隣接する動弁カムの最初
の圧縮行程において、カムシャフトに設けた係合ビンに
係合してそのベース円を動弁カムの圧縮行程部のベース
円より突出させて弁を作動し、燃焼室内の圧縮圧力を減
少する。With this configuration, when the engine is stopped and the piston stops during the compression stroke, the piston moves down due to the compression pressure, and when the crankshaft and camshaft are reversed and stopped, the one-way clutch is activated. The reversing decompression cam engages with the camshaft and rotates together with the camshaft to operate the valve and reduce the compression pressure in the combustion chamber. In this case, the valve is engaged with an engagement pin provided on the camshaft to cause its base circle to protrude from the base circle of the compression stroke portion of the valve operating cam, thereby operating the valve and reducing the compression pressure in the combustion chamber.
以下、本発明の一実施例を図面に基づいて説明する。 Hereinafter, one embodiment of the present invention will be described based on the drawings.
エンジン１のシリンダブロック２内にはピストン３が往
復動可能に設けられ、シリンダブロック２の上部に固設
されたシリンダヘッド４との間に燃焼室５を形成してい
る。A piston 3 is provided in a cylinder block 2 of an engine 1 so as to be able to reciprocate, and forms a combustion chamber 5 between the piston 3 and a cylinder head 4 fixedly installed on the upper part of the cylinder block 2.
シリンダヘッド４の上部には、吸気弁（図示せず）を作
動するロッカアーム５と、排気弁（図示せず）を作動す
るロッカアーム６とがシャフト７に回動可能に支持され
ており、ロッカアーム５のスリッパ面５ａとロッカアー
ム６の第１スリツパ而６ａの下方には、カムシャフト８
がシリンダヘッド４に回転可能に支承され、一端に固設
したスプロケット９とクランクシャフトのスプロケット
（図示せず）との間に巻架されたカムチェーン１０によ
り、クランクシャフトの回転に同期して回転する。At the top of the cylinder head 4, a rocker arm 5 that operates an intake valve (not shown) and a rocker arm 6 that operates an exhaust valve (not shown) are rotatably supported by a shaft 7. A camshaft 8 is located below the slipper surface 5a of the rocker arm 6 and the first slipper 6a of the rocker arm 6.
is rotatably supported by the cylinder head 4, and rotates in synchronization with the rotation of the crankshaft by a cam chain 10 wound between a sprocket 9 fixed at one end and a sprocket of the crankshaft (not shown). do.
カムシャフト８には、ロッカアーム５のスリッパ面５ａ
下部に吸気用動弁カム１１が、ロッカアーム６の第１ス
リッパ面６ａ下部に排気用動弁カム１２がそれぞれ固設
されており、また、排気用動弁カム１２に隣接してロッ
カアーム６の第１スリッパ面６ａ下部にデコンプ用カム
１３が設けられ、さらに、ロッカアーム６の第１スリッ
パ面６ａに隣接して形成された第２スリッパ面６ｂの下
部には、デコンプ用カム１３に隣接して逆転用デコンプ
カム１４が設けられている。The camshaft 8 has a slipper surface 5a of the rocker arm 5.
An intake valve cam 11 is fixed to the lower part, and an exhaust valve cam 12 is fixed to the lower part of the first slipper surface 6a of the rocker arm 6. A decompression cam 13 is provided at the lower part of the first slipper surface 6a, and a reversing cam 13 is provided adjacent to the decompression cam 13 at the lower part of the second slipper surface 6b formed adjacent to the first slipper surface 6a of the rocker arm 6. A decompression cam 14 is provided.
デコンプ用カム１３は、排気用動弁カム１２のベース円
１２ａよりもやや小径のベース円１３ａと、このベース
円１３ａから一側に延出し、排気用動弁カム１２のカム
リフト１２ｂより小さな形状のウェイト部１３ｂとを有
し、その内径１３Ｃはカムシャフト８の径よりやや大径
に形成されて、カムシャフト８に遊嵌されている。The decompression cam 13 has a base circle 13a having a diameter slightly smaller than the base circle 12a of the exhaust valve train cam 12, and a base circle 13a extending to one side from the base circle 13a and having a shape smaller than the cam lift 12b of the exhaust valve train cam 12. The weight portion 13b has an inner diameter 13C slightly larger than the diameter of the camshaft 8, and is loosely fitted onto the camshaft 8.
上記デコンプ用カム１３を遊嵌するカムシャフト８には
、デコンプ用カム１３に隣接する前記排気用動弁カム１
２の排気行程部１２ｃとなるカムリフト１２ａの位置に
、デコンプ用カム１３との間に配設されるボール状係合
部材１５を嵌合する係合凹部１６が形成され、これと対
向する前記排気用動弁カム１２の圧縮行程部１２ｄとな
る位置に係合ビン１７が突設されている。The exhaust valve drive cam 1 adjacent to the decompression cam 13 is attached to the camshaft 8 into which the decompression cam 13 is loosely fitted.
An engagement recess 16 into which a ball-shaped engagement member 15 disposed between the cam lift 12a and the decompression cam 13 is fitted is formed at the position of the cam lift 12a, which becomes the exhaust stroke section 12c of the second exhaust stroke section 12c. An engagement pin 17 is provided in a protruding manner at a position of the compression stroke portion 12d of the valve operating cam 12.
一方、デコンプ用カム１３の内径１３Ｃのウェイト部１
３ｂ内側には、前記ボール状係合部材１５に係合する凹
部１８が設けられ、また、これに対向する位置の内径１
３ｃに前記カムシャフト８に突設された係合ビン１７に
係合する溝部１つが設けられており、該デコンプ用カム
１３の凹部１８とカムシャフト８の係合凹部１６との間
には、ボール状係合部材１５が配設されている。On the other hand, the weight portion 1 of the decompression cam 13 has an inner diameter of 13C.
A recess 18 that engages with the ball-shaped engaging member 15 is provided on the inside of 3b, and an inner diameter 1 at a position opposite thereto is provided.
3c is provided with one groove that engages with the engagement pin 17 protruding from the camshaft 8, and between the recess 18 of the decompression cam 13 and the engagement recess 16 of the camshaft 8, A ball-shaped engagement member 15 is provided.
これにより、デコンプ用カム１３は、ボール状係合部材
１５と係合ビン１７に係合し、ウェイト部１３ｂを排気
用動弁カム１２のカムリフト１２ｂと同位置にして、排
気用動弁カム１２の排気行程部１２ｃ方向と圧縮行程部
１２ｄ方向には移動可能で、かつ、排気用動弁カム１２
と一体回転可能にカムシャフト８に設けられる。As a result, the decompression cam 13 engages with the ball-shaped engagement member 15 and the engagement pin 17, and places the weight portion 13b in the same position as the cam lift 12b of the exhaust valve drive cam 12. The exhaust valve operating cam 12 is movable in the direction of the exhaust stroke section 12c and the direction of the compression stroke section 12d.
The camshaft 8 is provided so as to be rotatable integrally with the camshaft 8.
また、カムシャツ１−８とデコンプ用カム１３と、の間
には、デコンプ用カム１３を排気用動弁カム１２の圧縮
行程部１２ｄ方向と膨張行程部１２ｅ方向の２方向に付
勢するカムスプリング２ｏが縮設されている。このカム
スプリング２０の付勢力は、デコンプ用カム１３の停止
状態では、デコンプ用カム１３のベース円１３ａを排気
用動弁カム１２のベース円１２ａより突出させ、デコン
プ用カム１３が回転すると、デコンプ用カム１３のウェ
イト部１３ｂの遠心力によりデコンプ用カム１３が排気
用動弁カム１２のカムリフト１２ｂ方向に移動するのを
妨げない強さにセットされている。Further, between the cam shirt 1-8 and the decompression cam 13, a cam spring is provided that biases the decompression cam 13 in two directions, that is, in the direction of the compression stroke section 12d and in the direction of the expansion stroke section 12e of the exhaust valve operating cam 12. 2o has been reduced. The biasing force of the cam spring 20 causes the base circle 13a of the decompression cam 13 to protrude from the base circle 12a of the exhaust valve operating cam 12 when the decompression cam 13 is stopped, and when the decompression cam 13 rotates, the decompression The centrifugal force of the weight portion 13b of the decompression cam 13 is set to a strength that does not prevent the decompression cam 13 from moving in the direction of the cam lift 12b of the exhaust valve operating cam 12.
さらに、デコンプ用カム１３の溝部１９には、排気用動
弁カム１２の吸入行程部１２ｆ側に、前記カムシャフト
８の係合ビン１７に係合して、デコンプ用カム１３のベ
ース円１３ａを排気用動弁カム１２の圧縮行程部１２Ｃ
Ｉのベース円１２ａより突出させる段部２１が溝部１９
に連続して形成されている。Further, the groove portion 19 of the decompression cam 13 is engaged with the engagement pin 17 of the camshaft 8 on the suction stroke portion 12f side of the exhaust valve operating cam 12, and the base circle 13a of the decompression cam 13 is Compression stroke section 12C of exhaust valve cam 12
The step portion 21 that protrudes from the base circle 12a of I is the groove portion 19.
are formed continuously.
この段部２１は、係合ビン１７が係合した際に、排気用
動弁カム１２のベース円１２ａとロッカアーム６の第１
スリッパ面６８間に形成されているタペットギャップＬ
よりもデコンプ用カム１３のベース円１３ａが大きく突
出するように形成されている。This stepped portion 21 connects the base circle 12a of the exhaust valve operating cam 12 and the first portion of the rocker arm 6 when the engagement bin 17 is engaged.
Tappet gap L formed between slipper surfaces 68
The base circle 13a of the decompression cam 13 is formed to protrude more than the base circle 13a of the decompression cam 13.
このデコンプ用カム１３に隣接する逆転用デコンプカム
１４は、カムシャフト８に回動可能に軸支されており、
内周には、カムシャフト８の逆転時にカムシャフト８に
係合して該逆転用アコンブカム１４をカムシャフト８と
一体に回転さゼる一方向クラッチ２２を備え、外周には
、静止時にロッカアーム６の第２スリッパ面６ｂに当接
する低カム面１４ａと、この低カム面１４ａに連続して
ベース円より突出するカムリフト１４ｂと、ベース円よ
り突出するストッパ部１４ｃとを形成している。A reverse decompression cam 14 adjacent to the decompression cam 13 is rotatably supported by the camshaft 8.
A one-way clutch 22 is provided on the inner periphery, which engages the camshaft 8 when the camshaft 8 is reversed, and rotates the reversing acombination cam 14 integrally with the camshaft 8. A one-way clutch 22 is provided on the outer periphery, which engages the camshaft 8 when the camshaft 8 is reversed, and rotates the reversing cam 14 integrally with the camshaft 8. A low cam surface 14a that comes into contact with the second slipper surface 6b, a cam lift 14b that protrudes from the base circle continuously from the low cam surface 14a, and a stopper portion 14c that protrudes from the base circle are formed.
カムリフト１４ｂは、カムシャフト８の逆転時にロッカ
アーム６の第２スリッパ面６ｂを押し上げて排気弁を作
動し、ストッパ部１４ｃはカムシャフト８の正転時にシ
リンダヘッド４に設けたストッパ２３に当接して該逆転
用デコンプカム１４の回転を規制している。The cam lift 14b pushes up the second slipper surface 6b of the rocker arm 6 when the camshaft 8 rotates in the reverse direction to operate the exhaust valve, and the stopper part 14c comes into contact with a stopper 23 provided on the cylinder head 4 when the camshaft 8 rotates in the forward direction. The rotation of the reversing decompression cam 14 is regulated.
次にこのように構成されたデコンプ装置の作用について
説明する。Next, the operation of the decompression device configured as described above will be explained.
エンジン１の運転中は、カムシャフト８は第６図におい
て矢印へに示される時計方向に回転している。したがっ
て、一方向クラッチ２２は作動せず、逆転用デコンプカ
ム１４はストッパ部１４ｃをストッパ２３に当接して回
転を停止して、低カム面１４ａをロッカアーム６の第２
スリッパ面６ｂに当接させている。During operation of the engine 1, the camshaft 8 is rotating in the clockwise direction indicated by the arrow in FIG. Therefore, the one-way clutch 22 does not operate, and the reverse rotation decompression cam 14 stops rotating by bringing the stopper portion 14c into contact with the stopper 23, and the low cam surface 14a is moved to the second position of the rocker arm 6.
It is brought into contact with the slipper surface 6b.
エンジン１を停止させると、時には、ピストン３は燃焼
室５内の混合気の圧縮圧力の抵抗で止まり、その圧力で
僅かに戻された位置に停止する場合がある。When the engine 1 is stopped, the piston 3 sometimes stops due to the resistance of the compression pressure of the air-fuel mixture in the combustion chamber 5, and may stop at a position slightly returned by the pressure.
この場合には、第７図矢印Ｂで示されるように、カムシ
ャフト８は反時計方向に逆転するので、一方向クラッチ
２２が作動して逆転用デコンプカム１４がカムシャフト
８と一体に回転する。これにより、逆転用デコンプカム
１４のカムリフト１４ｂがロッカアーム６の第２スリツ
パ而６ｂを押し上げて燃焼室５内の圧縮圧力を減少する
。In this case, as shown by arrow B in FIG. 7, the camshaft 8 rotates counterclockwise, so the one-way clutch 22 is activated and the reverse rotation decompression cam 14 rotates together with the camshaft 8. As a result, the cam lift 14b of the reverse rotation decompression cam 14 pushes up the second slipper 6b of the rocker arm 6 to reduce the compression pressure in the combustion chamber 5.
この状態でエンジン１を始動させると、ピストン３は圧
縮行程に入った所で停止しているが、燃焼室５内の圧縮
圧力は上記デコンプ作用で減少しているため、始動時の
負荷が大幅に減少されて、始動を容易に行える。When the engine 1 is started in this state, the piston 3 stops at the point where it enters the compression stroke, but the compression pressure in the combustion chamber 5 decreases due to the decompression action described above, so the load at the time of starting is significant. is reduced to make starting easier.
エンジン１が始動すると、カムシャフト８は第６図の矢
印六方向に回転するので、一方向クラッチ２２の係合が
なくなり、逆転用デコンプカム１４はストッパ部１４ｃ
をストッパ２３に当接して回転が規制され、以後エンジ
ン１の運転中はこの位置にある。When the engine 1 starts, the camshaft 8 rotates in the six directions shown by the arrows in FIG.
The rotation is regulated by contacting the stopper 23, and remains in this position while the engine 1 is operating.
次に、デコンプ用カム１３の作用について説明する。Next, the function of the decompression cam 13 will be explained.
第２図は、エンジン１の停止時に排気用動弁カム１２が
膨張行程位置で回転を停止した状態を示すもので、デコ
ンプ用カム１３は、カムスプリンング２０の付勢力によ
り排気用動弁カム１２の圧縮行程部１２ｄ方向に移動し
、そのベース円１３ａを排気用動弁カム１２の圧縮行程
部１２ｄのベース円１２ａより突出しているが、ロッカ
アーム６の第１スリッパ面６ａの下部では、ベース円１
３ａを排気用動弁カム１２の膨張行程部１２ｅのベース
円１２ａよりも内側に位置させているので、排気用動弁
カム１２とロッカアーム６の第１スリッパ面６８間のタ
ペットギャップしは保持されている。FIG. 2 shows a state in which the exhaust valve drive cam 12 has stopped rotating at the expansion stroke position when the engine 1 is stopped. 12, and its base circle 13a protrudes from the base circle 12a of the compression stroke section 12d of the exhaust valve operating cam 12. However, at the lower part of the first slipper surface 6a of the rocker arm 6, the base 1 yen
3a is located inside the base circle 12a of the expansion stroke portion 12e of the exhaust valve cam 12, so that the tappet gap between the exhaust valve cam 12 and the first slipper surface 68 of the rocker arm 6 is maintained. ing.
この状態からエンジン１を始動させると、排気用動弁カ
ム１２及びデコンプ用カム１３は図において矢印六方向
に回転し、１回目の排気行程、吸入行程を経て、第３因
に示されるように排気用動弁カム１２の圧縮行程部１２
ｄの初めがロッカアーム６のＭ１スリッパ面６ａの下部
に回転してくると、デコンプ用カム１３のベース円１３
ａが排気用動弁カム１２のベース円１２ａより突出して
いるため、デコンプ用カム１３のベース円１３ａがロッ
カアーム６の第１スリッパ面６ａに当接し、ざらに回転
すると、デコンプ用カム１３はロッカアーム６に押され
、ボール状係合部材１５を支点として図において左方へ
移動し、デコンプ用カム１３の段部２１にカムシャフト
８の係合突起１７が係合する、。When the engine 1 is started from this state, the exhaust valve operating cam 12 and the decompression cam 13 rotate in the six directions of the arrows in the figure, and after passing through the first exhaust stroke and intake stroke, as shown in the third factor. Compression stroke section 12 of exhaust valve drive cam 12
When the beginning of d rotates to the lower part of the M1 slipper surface 6a of the rocker arm 6, the base circle 13 of the decompression cam 13
a protrudes from the base circle 12a of the exhaust valve drive cam 12, so when the base circle 13a of the decompression cam 13 comes into contact with the first slipper surface 6a of the rocker arm 6 and rotates roughly, the decompression cam 13 moves toward the rocker arm. 6 and moves to the left in the figure using the ball-shaped engagement member 15 as a fulcrum, and the engagement protrusion 17 of the camshaft 8 engages with the stepped portion 21 of the decompression cam 13.
そして、さらに回転して第４図に示されるように排気用
動弁カム１２の圧縮行程部１２ｄの途中がロッカアーム
６の第１スリッパ面６ａの下部にくると、デコンプ用カ
ム１３はカムシャフト８の係合突起１７との係合により
、そのベース円１３ａを排気用動弁カム１２の圧縮行程
部１２ｄのベース円１２ａより高さＨ分突出して保持さ
れる。Then, as it rotates further and as shown in FIG. By engaging with the engagement protrusion 17, the base circle 13a is held so as to protrude by a height H from the base circle 12a of the compression stroke portion 12d of the exhaust valve operating cam 12.
この高さＨはタペットギャップＬより高いので、デコン
プ用カム１３のベース円１３ａがロッカアーム６の第１
スリッパ面６ａを押し上げて排気弁を開き、燃焼室５内
の圧縮圧力を減圧する。Since this height H is higher than the tappet gap L, the base circle 13a of the decompression cam 13 is in the first position of the rocker arm 6.
The slipper surface 6a is pushed up to open the exhaust valve and the compression pressure in the combustion chamber 5 is reduced.
この状態からさらに回転すると、デコンプ用カム１３は
ロッカアーム６に押され、ボール状係合部材１５を支点
として、図において左方へ移動して、カムシャフト８の
係合突起１７との係合が解除される。When the decompression cam 13 is further rotated from this state, it is pushed by the rocker arm 6 and moves to the left in the figure using the ball-shaped engagement member 15 as a fulcrum, so that the decompression cam 13 is no longer engaged with the engagement protrusion 17 of the camshaft 8. It will be canceled.
そして、第２回目以降の回転が続くと、第５図に示され
るように、デコンプ用カム１３のウェイト部１３ｂに働
く遠心力がカムスプリング２０の付勢力に抗してデコン
プ用カム１３を排気用動弁カム１２の排気行程部１２ｃ
方向に移動させ、デコンプ用カム１３は排気用動弁カム
１２の外径よりも内側の位置に保持された状態で、排気
用動弁カム１２と一体に回転する。Then, as the second and subsequent rotations continue, as shown in FIG. Exhaust stroke section 12c of the valve drive cam 12
The decompression cam 13 rotates together with the exhaust valve cam 12 while being held at a position inside the outer diameter of the exhaust valve cam 12.
即ち、デコンプ用カム１３は、エンジン１を始動する際
の１回目の圧縮行程においてのみ、そのベース円１３ａ
を排気用動弁カム１２の圧縮行程部１２Ｃのベース円１
２ａより高い位置に保持し、これにより、排気弁を作動
して燃焼室５内の圧縮圧力を減圧してクランクシャツｔ
・の回転慣性力を増大し、エンジン１の始動性を向上さ
せ、その後のカムシャフト８の回転中は、ウェイト部１
３ｂに働く遠心力により、排気用動弁カム１２の外径よ
りも内側に保持されるので、排気用動弁カム１２の正常
な作動を妨げることがない。That is, the decompression cam 13 changes its base circle 13a only in the first compression stroke when starting the engine 1.
The base circle 1 of the compression stroke part 12C of the exhaust valve cam 12
2a, thereby operating the exhaust valve to reduce the compression pressure in the combustion chamber 5 and release the crank shirt t.
・Increases the rotational inertia of the engine 1, improves the startability of the engine 1, and during the subsequent rotation of the camshaft 8, the weight part 1
Since the centrifugal force acting on the exhaust valve cam 12 is held inside the outer diameter of the exhaust valve cam 12, normal operation of the exhaust valve cam 12 is not hindered.
本発明に係るデコンプ装置は以上のように構成されてい
るので、エンジン１を停止してカムシャフト８が逆転し
た際に、ピストン３が圧縮工程に入った所で停止した場
合には、逆転用デコンプカム１４が作動して燃焼室５内
の圧縮圧力を減少し、カムシャフトが逆転せずに停止し
た場合には、デコンプカム１３が作動して燃焼室５内の
圧縮圧力を減少してエンジン１の始動を容易にする。Since the decompression device according to the present invention is configured as described above, when the engine 1 is stopped and the camshaft 8 is reversed, if the piston 3 stops at the point where it enters the compression process, the decompression device If the decompression cam 14 operates to reduce the compression pressure in the combustion chamber 5 and the camshaft stops without rotating in reverse, the decompression cam 13 operates to reduce the compression pressure in the combustion chamber 5 and reduce the compression pressure in the combustion chamber 5. Makes starting easier.
このため、始動時の負荷が大幅に減少され、始動装置を
小型化することでき、また、キックによる始動やクラン
キングによる始動も容易に行える。Therefore, the load during starting is significantly reduced, the starting device can be downsized, and starting by kicking or cranking can be easily performed.
さらに、デコンプ用カム１３を動弁カム１２と逆転用デ
コンプカム１４の間に配置したので、デコンプ用カム１
３の幅を薄く軽量化しても確実に作動する。Furthermore, since the decompression cam 13 is disposed between the valve train cam 12 and the reverse rotation decompression cam 14, the decompression cam 13
Even if the width of 3 is made thinner and lighter, it still operates reliably.
尚、上記実施例ではデコンプ用カム及び逆転用デコンプ
カムを排気用動弁カムに隣接して設けたもので説明した
が、吸気用動弁カムに隣接して設けたものでも同様に作
動する。また、デコンプ用カムに設けられるウェイト部
の形状も上記実施例の形状に限定されず、隣接する動弁
カムの外径内に収まる形状であればよく、逆転用デコン
プカムに用いられる一方向クラッチも図示のクラッチに
限定されない。さらに、上記実施例では５ＯＨＣエンジ
ンで説明したが、ＤＯＨＣエンジンやクランクシャフト
近傍にカムシャフトを備えたＯＨＶまたはサイドバルブ
方式のエンジン等にも本発明を適用できることは勿論で
ある。In the above embodiment, the decompression cam and the reversal decompression cam are provided adjacent to the exhaust valve operating cam, but they operate similarly even if they are provided adjacent to the intake valve operating cam. Further, the shape of the weight portion provided on the decompression cam is not limited to the shape of the above embodiment, and may be any shape that fits within the outer diameter of the adjacent valve train cam. It is not limited to the illustrated clutch. Furthermore, although the above embodiment has been explained using a 5OHC engine, it goes without saying that the present invention can also be applied to a DOHC engine, an OHV engine having a camshaft near the crankshaft, or a side valve type engine.
本発明は以上のように構成したから、エンジンの停止時
にピストンが圧縮行程に入った所で停止してカムシャフ
トが逆転した場合には、逆転用デコンプカムが作動して
燃ｖｌ室内の圧縮圧力を減少し、また、デコンプ用カム
は隣接する動弁カムの最初の圧縮行程において作動して
燃焼室内の圧縮圧力を減少してエンジンの始動を容易に
するので、いかなる状態でも確実に自動的に作動するオ
ートデコンプ装置とすることができる。Since the present invention is constructed as described above, when the engine is stopped and the piston stops at the point where it enters the compression stroke and the camshaft reverses, the reverse decompression cam operates to reduce the compression pressure in the combustion chamber. In addition, the decompression cam operates during the first compression stroke of the adjacent valve train cam to reduce the compression pressure in the combustion chamber and facilitate engine starting, ensuring automatic operation under any conditions. It can be an auto decompression device.
図は本発明の一実施例を示すもので、第１図はエンジン
の上半分の縦断正面図、第２図乃至第５図は排気用動弁
カムとデコンプ用カムの作動状態を示すもので、第２図
は排気用動弁カムの膨張行程時の側面図、第３図は圧縮
行程の初期の側面図、第４図は圧縮行程の途中の側面図
、第５図は通常の回転時の側面図、第６図は逆転用デン
コンプカムの側面図、第７図は逆転用デコンプカムの作
動状態を示す側面図である。
１・・・エンジン ２・・・シリンダ ３・・・ピ
ストン ４・・・シリンダヘッド ５・・・燃焼
室５．６・・・ロッカアーム ８・・・カムシャフト
１１・・・吸気用動弁カム １２・・・排気用動弁カ
ム１２ａ・・・ベース円 １２ｂ・・・カムリフト
１２Ｃ・・・排気行程部 １２ｄ・・・圧縮行程部
１２ｅ・・・膨張行程部 １２ｆ・・・吸入行程部１
３・・・デコンプ用カム １３ａ・・・ベース円１３
ｂ・・・ウェイトｆｌＪ １３ Ｇ・・・内径
１４・・・逆転用デコンプカム １４ａ・・・低カ
ム面１４ｂ・・・カムリフト １４ｃ・・・ストッ
パ部１５・・・ボール状係合部材 １６・・・カムシ
ャフトの係合凹部 １７・・・係合ビン １８・・
・デコンプ用カムの凹部 １９・・・溝部 ２０・
・・カムスプリング ２１・・・段部 ２２・・
・一方向クラッチThe figures show one embodiment of the present invention, and Fig. 1 is a longitudinal sectional front view of the upper half of the engine, and Figs. 2 to 5 show the operating states of the exhaust valve train cam and the decompression cam. , Figure 2 is a side view of the exhaust valve cam during the expansion stroke, Figure 3 is a side view at the beginning of the compression stroke, Figure 4 is a side view during the compression stroke, and Figure 5 is during normal rotation. FIG. 6 is a side view of the reversing decompression cam, and FIG. 7 is a side view showing the operating state of the reversing decompression cam. 1... Engine 2... Cylinder 3... Piston 4... Cylinder head 5... Combustion chamber 5.6... Rocker arm 8... Camshaft 11... Intake valve operating cam 12 ...Exhaust valve train cam 12a...Base circle 12b...Cam lift 12C...Exhaust stroke section 12d...Compression stroke section 12e...Expansion stroke section 12f...Suction stroke section 1
3... Decompression cam 13a... Base circle 13
b...Weight flJ 13 G...Inner diameter
14... Decompression cam for reverse rotation 14a... Low cam surface 14b... Cam lift 14c... Stopper portion 15... Ball-shaped engagement member 16... Engagement recess of camshaft 17... Engagement Bin 18...
・Decompression cam recess 19...Groove 20・
...Cam spring 21...Step part 22...
・One-way clutch
Claims (1)
にそれぞれ固設した動弁カムにて作動させるエンジンに
おいて、前記動弁カムに近接して、カムシャフトの逆転
時に一方向クラッチを介してカムシャフトと一体に回転
して前記吸・排気弁のいずれか一方を作動する逆転用デ
コンプカムを設け、該逆転用デコンプカムと前記動弁カ
ムとの間に、動弁カムのベース円よりやや小径のベース
円と、該ベース円の一側に設けたウェイト部と、前記カ
ムシャフトの径よりは大径の内径とを有するデコンプ用
カムをカムシャフトに遊嵌し、該カムシャフトには、前
記隣接する動弁カムの排気行程部の位置に前記デコンプ
用カムとの間に配設される係合部材を嵌合する係合凹部
を形成し、これと対向する圧縮行程部の位置にデコンプ
用カムに係合する係合突起を設け、一方、前記デコンプ
用カムの内径には、ウェイト部内側に前記係合部材に係
合する係合凹部を設け、これと対向する位置に前記カム
シャフトに設けた係合突起に係合する溝部を設け、該デ
コンプ用カムの係合凹部とカムシャフトの係合凹部との
間に係合部材を配設して、デコンプ用カムを前記隣接す
る動弁カムの排気行程部方向と圧縮行程部方向には移動
可能で、かつ、動弁カムと一体回転可能に設け、カムシ
ャフトとデコンプ用カムとの間にデコンプ用カムを圧縮
行程部方向と膨張行程部方向の２方向に付勢する弾発部
材を縮設し、前記デコンプ用カムの溝部の吸入行程部側
に前記カムシャフトの係合突起に係合してデコンプ用カ
ムのベース円を動弁カムの圧縮行程部のベース円より突
出させて前記吸・排気弁のいずれか一方を作動させる段
部を溝部に連続して形成したことを特徴とするエンジン
のオートデコンプ装置。1. In an engine in which the intake and exhaust valves provided in the cylinder head are operated by valve drive cams fixed to the camshaft, the cams are operated close to the valve drive cams via a one-way clutch when the camshaft reverses. A reversing decompression cam that rotates together with the shaft to operate one of the intake and exhaust valves is provided, and a base having a diameter slightly smaller than the base circle of the valve driving cam is provided between the reversing decompression cam and the valve driving cam. A decompression cam having a circle, a weight part provided on one side of the base circle, and an inner diameter larger than the diameter of the camshaft is loosely fitted onto the camshaft, An engagement recess into which an engagement member disposed between the decompression cam and the decompression cam is fitted is formed at the exhaust stroke portion of the valve train cam, and an engagement recess into which the engagement member disposed between the decompression cam and the decompression cam is fitted is formed at the compression stroke portion opposite to the engagement recess. An engagement protrusion that engages is provided, and an engagement recess that engages with the engagement member is provided on the inside of the weight portion on the inner diameter of the decompression cam, and an engagement recess that engages with the engagement member is provided on the camshaft at a position opposite to this. A groove that engages with the engagement protrusion is provided, an engagement member is provided between the engagement recess of the decompression cam and the engagement recess of the camshaft, and the decompression cam is connected to the adjacent valve drive cam. The decompression cam is installed between the camshaft and the decompression cam so that it can move in the exhaust stroke direction and the compression stroke direction, and can rotate integrally with the valve train cam. A resilient member is compressed and biased in two directions, and is engaged with the engagement protrusion of the camshaft on the suction stroke side of the groove of the decompression cam, thereby causing the base circle of the decompression cam to move in the direction of the valve operating cam. An automatic decompression device for an engine, characterized in that a stepped portion is formed continuously in a groove portion to protrude from a base circle of a compression stroke portion and actuate either one of the intake and exhaust valves.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP31325886A JPH0670366B2 (en) | 1986-12-25 | 1986-12-25 | Engine auto decompression device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP31325886A JPH0670366B2 (en) | 1986-12-25 | 1986-12-25 | Engine auto decompression device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS63162911A true JPS63162911A (en) | 1988-07-06 |
| JPH0670366B2 JPH0670366B2 (en) | 1994-09-07 |
Family
ID=18039036
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP31325886A Expired - Fee Related JPH0670366B2 (en) | 1986-12-25 | 1986-12-25 | Engine auto decompression device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0670366B2 (en) |
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH06146938A (en) * | 1992-11-06 | 1994-05-27 | Mitsubishi Motors Corp | Reverse rotation preventing device for diesel engine |
| WO2002081877A1 (en) * | 2001-03-30 | 2002-10-17 | Honda Giken Kogyo Kabushiki Kaisha | Decompressor for 4-stroke cycle internal combustion engine |
| EP1447530A1 (en) * | 2001-03-26 | 2004-08-18 | Honda Giken Kogyo Kabushiki Kaisha | Decompressor for 4-stroke cycle internal combustion engines |
| WO2007083386A1 (en) * | 2006-01-20 | 2007-07-26 | Honda Motor Co., Ltd. | Decompression device for internal combustion engine |
| JP2008274855A (en) * | 2007-04-27 | 2008-11-13 | Honda Motor Co Ltd | Internal combustion engine provided with decompression device and motorcycle equipped with the internal combustion engine |
| JP2009091901A (en) * | 2007-10-03 | 2009-04-30 | Honda Motor Co Ltd | Engine decompression apparatus |
| CN101994595A (en) * | 2009-08-24 | 2011-03-30 | 本田技研工业株式会社 | A steam cylinder head structure of an internal combustion engine in a vehicle |
| TWI451031B (en) * | 2010-05-12 | 2014-09-01 | Sanyang Industry Co Ltd | Engine decompression mechanism |
| CN110500157A (en) * | 2019-09-12 | 2019-11-26 | 江门市大长江集团有限公司 | Position limiting structure and engine cylinder head decompressor |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4346262B2 (en) | 2001-07-25 | 2009-10-21 | 本田技研工業株式会社 | Method and apparatus for starting internal combustion engine |
-
1986
- 1986-12-25 JP JP31325886A patent/JPH0670366B2/en not_active Expired - Fee Related
Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH06146938A (en) * | 1992-11-06 | 1994-05-27 | Mitsubishi Motors Corp | Reverse rotation preventing device for diesel engine |
| EP1447530A1 (en) * | 2001-03-26 | 2004-08-18 | Honda Giken Kogyo Kabushiki Kaisha | Decompressor for 4-stroke cycle internal combustion engines |
| EP1447530A4 (en) * | 2001-03-26 | 2008-04-09 | Honda Motor Co Ltd | Decompressor for 4-stroke cycle internal combustion engines |
| WO2002081877A1 (en) * | 2001-03-30 | 2002-10-17 | Honda Giken Kogyo Kabushiki Kaisha | Decompressor for 4-stroke cycle internal combustion engine |
| WO2007083386A1 (en) * | 2006-01-20 | 2007-07-26 | Honda Motor Co., Ltd. | Decompression device for internal combustion engine |
| JP2008274855A (en) * | 2007-04-27 | 2008-11-13 | Honda Motor Co Ltd | Internal combustion engine provided with decompression device and motorcycle equipped with the internal combustion engine |
| JP4759534B2 (en) * | 2007-04-27 | 2011-08-31 | 本田技研工業株式会社 | INTERNAL COMBUSTION ENGINE WITH DECOMP DEVICE AND MOTORCYCLE MOUNTED WITH THE INTERNAL COMBUSTION ENGINE |
| JP2009091901A (en) * | 2007-10-03 | 2009-04-30 | Honda Motor Co Ltd | Engine decompression apparatus |
| CN101994595A (en) * | 2009-08-24 | 2011-03-30 | 本田技研工业株式会社 | A steam cylinder head structure of an internal combustion engine in a vehicle |
| TWI451031B (en) * | 2010-05-12 | 2014-09-01 | Sanyang Industry Co Ltd | Engine decompression mechanism |
| CN110500157A (en) * | 2019-09-12 | 2019-11-26 | 江门市大长江集团有限公司 | Position limiting structure and engine cylinder head decompressor |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0670366B2 (en) | 1994-09-07 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| LAPS | Cancellation because of no payment of annual fees |