JPS6123813A - Suction and exhaust valve lift control device for internal-combustion engine - Google Patents
Suction and exhaust valve lift control device for internal-combustion engineInfo
- Publication number
- JPS6123813A JPS6123813A JP14218084A JP14218084A JPS6123813A JP S6123813 A JPS6123813 A JP S6123813A JP 14218084 A JP14218084 A JP 14218084A JP 14218084 A JP14218084 A JP 14218084A JP S6123813 A JPS6123813 A JP S6123813A
- Authority
- JP
- Japan
- Prior art keywords
- cam
- lift
- intake
- control
- lever
- 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
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
- F01L13/00—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations
- F01L13/0015—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations for optimising engine performances by modifying valve lift according to various working parameters, e.g. rotational speed, load, torque
- F01L13/0021—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations for optimising engine performances by modifying valve lift according to various working parameters, e.g. rotational speed, load, torque by modification of rocker arm ratio
- F01L13/0026—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations for optimising engine performances by modifying valve lift according to various working parameters, e.g. rotational speed, load, torque by modification of rocker arm ratio by means of an eccentric
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
- F01L13/00—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Valve-Gear Or Valve Arrangements (AREA)
- Valve Device For Special Equipments (AREA)
Abstract
Description
【発明の詳細な説明】
〈産業上の利用分野〉
本発明は、吸・排気弁のリフト特性を機関運転条件に応
じて可変制御する内燃機関の吸・排気弁リフト制御装置
に関する。DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an intake/exhaust valve lift control device for an internal combustion engine that variably controls the lift characteristics of intake/exhaust valves according to engine operating conditions.
(従来の技術)
バルブオーバランプや新気充填効率等が常に最適に設定
されるように吸・排気弁のリフト特性(開閉時期及びリ
フト量)を可変制御する装置として、例えば第9図に示
すものがある(参考文献:米国特許第3413965号
)。(Prior art) As an example of a device that variably controls the lift characteristics (opening/closing timing and lift amount) of intake and exhaust valves so that valve overramp, fresh air filling efficiency, etc. are always optimally set, as shown in Fig. 9, for example. (Reference: US Pat. No. 3,413,965).
このものの概要を図に基づいて説明すると、吸・排気弁
駆動カム1に一端が当接し、吸・排気弁2のステムエン
ドに嵌合して揺動自由に指示されたロッカアーム3の背
面3aを湾曲形成し、この背面3aがレバー4に支点接
触しながらロッカアーム3の両端が揺動することによっ
て吸・排気弁駆動カム1のリフトを吸・排気弁2に伝達
するようになっている。特に前記レバー4は一端が機関
本体に揺動自由に軸支されており、該レバー4の揺動位
置(傾斜)を他端部に当接するリフト制御カム5を油圧
アクチュエータ等により機関運転条件に応じて適切な位
相に回転駆動することによって制御し、もってロッカア
ーム3の背面3aとレバー4との接触する支点位置を変
化させて吸・排気弁2のリフト特性を可変制御するよう
にしている。To explain the outline of this device based on a diagram, the back surface 3a of the rocker arm 3 whose one end is in contact with the intake/exhaust valve drive cam 1 and which is fitted to the stem end of the intake/exhaust valve 2 and is instructed to swing freely. The rear surface 3a is in fulcrum contact with the lever 4 while both ends of the rocker arm 3 swing, thereby transmitting the lift of the intake/exhaust valve drive cam 1 to the intake/exhaust valves 2. In particular, one end of the lever 4 is rotatably supported by the engine body, and the swing position (inclination) of the lever 4 is controlled by a hydraulic actuator or the like to adjust the lift control cam 5 that abuts the other end to the engine operating conditions. The lift characteristic of the intake/exhaust valve 2 is variably controlled by controlling the rotary drive in an appropriate phase accordingly, thereby changing the fulcrum position where the back surface 3a of the rocker arm 3 and the lever 4 contact.
例えば、リフト制御カム5によるレバー4の押し下げ量
が大であれば、吸・排気弁駆動カム1のベースサークル
状態においてレバー4の自由端部と口・7カアーム3と
が近接しており、従って、吸・排気弁2の開弁時期が早
まると共にリフト量が大となる。逆に、リフト制御カム
5による押し下げ量が小であれば、吸・排気弁駆動カム
1のペースサークル状態でレバー4の自由端部とロッカ
アーム3とが離間しており、従って、吸・排気弁2の開
弁時期が遅れると共にリフトitが小となるのである。For example, if the lever 4 is pushed down by a large amount by the lift control cam 5, the free end of the lever 4 and the opening/socket arm 3 are close to each other in the base circle state of the intake/exhaust valve drive cam 1, and therefore, , the opening timing of the intake/exhaust valves 2 is advanced and the lift amount becomes large. Conversely, if the amount of depression by the lift control cam 5 is small, the free end of the lever 4 and the rocker arm 3 are separated from each other in the pace circle state of the intake/exhaust valve drive cam 1, and therefore the intake/exhaust valve As the opening timing of the second valve is delayed, the lift it becomes smaller.
〈発明が解決しようとする問題点〉
しかしながら、このような従来の吸・排気弁リフト制御
装置にあっては、リフト制御カム5と一体の支軸5aを
油圧アクチュエータ等によりリフト特性を可変制御する
構成となっているため、次のような問題を生じていた。<Problems to be Solved by the Invention> However, in such a conventional intake/exhaust valve lift control device, the lift characteristics of the support shaft 5a integrated with the lift control cam 5 are variably controlled by a hydraulic actuator or the like. Due to this configuration, the following problems occurred.
即ち、ロッカアーム3.レバー4を介してバルブスプリ
ング6の反力がリフト制御カム5あるいはその支軸5a
の支持部材(図示せず)に加わるため、レバー4とリフ
ト制御カム5との接触面あるいは、支軸5aと支軸部材
との摺動面に摩擦力を生じ、アクチュエータがこれら摩
擦力に打ち勝ってリフト制御カム5を回転させる必要が
あるため、大きな力を必要とされ、アクチュエータの大
型化、制御のためのエネルギ損失増大を招く。That is, rocker arm 3. The reaction force of the valve spring 6 is applied via the lever 4 to the lift control cam 5 or its support shaft 5a.
(not shown), a frictional force is generated on the contact surface between the lever 4 and the lift control cam 5 or on the sliding surface between the support shaft 5a and the support shaft member, and the actuator overcomes these frictional forces. Since it is necessary to rotate the lift control cam 5 using the actuator, a large force is required, resulting in an increase in the size of the actuator and an increase in energy loss for control.
特に、いずれかの気筒で常にバルブスプリングの反力が
リフト制御カム5に作用する4気筒以上の機関では上記
問題は極めて大きなものとなる。In particular, the above problem becomes extremely serious in engines with four or more cylinders in which the reaction force of the valve spring always acts on the lift control cam 5 in any one of the cylinders.
また、リフト制御カム5のカム面が長円形状(又は偏心
円形状)となっているため、レバー4からの反力の方向
とリフト制御カム5の回転軸中心とのずれによってリフ
ト制御カム5に回転方向のモーメントが作用し、カム面
とレバー4との係合面が移動し易く、信頬性が悪い上に
、前記モーメントに対向する力を常に加えておく必要が
あるため、この面からもエネルギ損失を招くという問題
があった。In addition, since the cam surface of the lift control cam 5 has an elliptical shape (or an eccentric circular shape), the lift control cam 5 may be A moment in the rotational direction acts on the cam surface, and the engagement surface between the cam surface and the lever 4 is likely to move, resulting in poor reliability. Moreover, it is necessary to constantly apply a force that opposes the moment. There was also the problem of energy loss.
本発明はこのような従来の問題点に鑑みなされたもので
、吸・排気弁のリフト時にはリフト制御カムの回転駆動
力を弾性力によって必要最小限蓄え、非リフト時にリフ
ト制御カムが回転するようにしてその駆動力を必要最小
限に軽減でき、もって駆動手段の小型化、制御エネルギ
の損失の低減を図れると共に、リフト制御カムとレバー
とが安定した保合状態に保持されて制御の信顛性を向上
した制御性能を維持できるようにした内燃機関の吸・排
気弁リフト制御装置を提供することを目的とする。The present invention has been developed in view of these conventional problems, and uses elastic force to store the necessary minimum rotational driving force of the lift control cam when the intake/exhaust valves are lifted, and allows the lift control cam to rotate when the intake/exhaust valves are not lifted. The driving force can be reduced to the necessary minimum, thereby reducing the size of the driving means and reducing the loss of control energy.In addition, the lift control cam and lever are held in a stable state of engagement, which improves control reliability. An object of the present invention is to provide an intake/exhaust valve lift control device for an internal combustion engine that can maintain improved control performance.
(間B点を解決するための手段)
このため本発明は、前記の如くリフト制御カムを回転さ
せてレバーとロッカアーム背面との接触する支点位置を
変えることにより吸・排気弁のりラド特性を可変制御す
る装置において、前記リフト制御カムに同一回転方向に
対して吸・排気弁リフト量を段階的に変化させる略平ら
な複数のカム面を形成すると共に、リフト制御カムと該
リフト制御カムを回転させるカム制御軸とを回転軸回り
に弾性を有した弾性部材を介して連結し、かつ、前記カ
ム制御軸を機関運転条件に応じて所定量回転駆動させる
駆動手段を設け、該駆動手段によって駆動されるカム制
御軸の回転速度をリフト制御カムの隣接するカム面相互
の回転角分回転するのに要する時間が吸・排気弁のリフ
ト期間の約2倍以上となるように設定した構成とする。(Means for solving the problem of point B) Therefore, the present invention changes the intake/exhaust valve slope characteristics by rotating the lift control cam as described above and changing the fulcrum position where the lever and the back surface of the rocker arm come into contact. In the control device, the lift control cam is formed with a plurality of substantially flat cam surfaces that change the lift amount of the intake and exhaust valves stepwise in the same rotational direction, and the lift control cam and the lift control cam are rotated. A cam control shaft is connected to the cam control shaft through an elastic member having elasticity around the rotating shaft, and a drive means is provided for driving the cam control shaft by a predetermined amount of rotation according to engine operating conditions, and the drive means is driven by the drive means. The rotation speed of the cam control shaft is set so that the time required for the lift control cam to rotate by the rotation angle of the adjacent cam surfaces is approximately twice or more than the lift period of the intake and exhaust valves. .
く作用〉
かかる構成により、吸・排気弁のリフト時に固定される
リフト制御カムと、回転するカム制御軸との相対回転に
よって弾性部材が最大限捩じれた場合でもこの捩じれ角
はリフト制御カムの隣接するカム面相互の回転角を上回
らないため、弾性部材の捩じれ過ぎを防止できると共に
、カム面切換時、リフト制御カムの回り過ぎを防止でき
、もってカム面への切換係合が1つずつ安定かつ確実に
行われる。With this configuration, even if the elastic member is twisted to the maximum due to the relative rotation between the fixed lift control cam and the rotating cam control shaft when the intake/exhaust valves are lifted, this torsion angle will be smaller than that of the lift control cam adjacent to the lift control cam. Since the rotation angle of the cam surfaces does not exceed the mutual rotation angle between the cam surfaces, it is possible to prevent the elastic member from twisting too much, and when switching the cam surfaces, it is also possible to prevent the lift control cam from rotating too much, thereby stabilizing the switching engagement with the cam surfaces one by one. and be carried out reliably.
(実施例〉 以下、本発明の実施例を図面に基づいて説明する。(Example> Embodiments of the present invention will be described below based on the drawings.
一実施例を示す第1図〜第3図において、m関回転に同
期して回転する吸・排気弁駆動カム11と吸・排気弁1
2のステムエンドとに両端を当接させてロッカアーム1
3が設けられ、該ロッカアーム13の湾曲形成された背
面13aを支点接触させると共に、ロッカアーム13の
両側壁から突出するシャフト13bを保持部材14を介
して凹溝15a内に保持するレバー15が設けられる。In FIGS. 1 to 3 showing one embodiment, an intake/exhaust valve drive cam 11 and an intake/exhaust valve 1 rotating in synchronization with the m rotation are shown.
Rocker arm 1 with both ends in contact with the stem end of 2.
3 is provided, and a lever 15 is provided that brings the curved back surface 13a of the rocker arm 13 into fulcrum contact and holds the shaft 13b protruding from both side walls of the rocker arm 13 in the groove 15a via the holding member 14. .
レバー15に形成されたスプリングシート15bと保持
部材14との間には、ロッカアーム13を下方向に付勢
するバネ定数小のスプリング16が介装される。A spring 16 with a small spring constant is interposed between the spring seat 15b formed on the lever 15 and the holding member 14 to bias the rocker arm 13 downward.
又、シリンダヘッド17に固定されたブラケット18に
嵌挿保持された油圧ピボットI9の球状の下端面がレバ
ー15の吸・排気弁12ステムエンド側の他端部頂壁に
形成された凹陥部15cに嵌合して、該嵌合部を中心と
してレバー15を揺動自由に支持すると共に、ブラケッ
ト18に対して後述する如く回転自由に取り付けられた
リフト制御カム20がレバー15の吸・排気弁駆動カム
11側の端部頂壁に当接してレバー15の揺動位置を規
制している。Further, the spherical lower end surface of the hydraulic pivot I9, which is fitted and held by a bracket 18 fixed to the cylinder head 17, is in a concave portion 15c formed on the top wall of the other end of the lever 15 on the stem end side of the intake/exhaust valve 12. The lift control cam 20 is fitted into the bracket 18 to support the lever 15 in a freely swinging manner about the fitting part, and the lift control cam 20 is rotatably attached to the bracket 18 as will be described later. The swinging position of the lever 15 is regulated by coming into contact with the top wall of the end portion on the drive cam 11 side.
前記油圧ピボフト19は下端面が前記レバー15の凹陥
部15Cに嵌合すると共に、周面がブラケット18に形
成した取付孔18a内に摺動自由に嵌挿された外筒19
aと、該外筒19a内に嵌挿される内筒19bとを備え
、かつ、両者の間に形成された油圧室19Cにチェック
バルブ19dを備えて形成される。そして、ブラケット
18内部に形成された油圧供給通路18bから内筒19
b内部及びチェックバルブ19dを介して油圧を油圧室
19cに供給してパルプクリアランスを一定に保つよう
になっている。 N前記リフ
ト制御カム20は外周面に、吸・排気弁12のリフト量
を同一回転方向に対して段階的に増大させるように略平
らな4つのカム面01〜Cイを有すると共に、リフト量
を減少させる回転方向に対してリフト量を最小とするカ
ム面C1がレバー15と係合する位置でブラケット18
の一部に形成した突起18Cに係止するストッパ20a
を有し、かつ、中心部に後述するカム制御軸23を挿通
する孔20bを有する。また、リフト制御カム20の両
側から突出して形成された円筒部20cの外周面は、第
3図に示すようにブラケット18に形成された下部円弧
溝18dと、ブラケット18上にポルト21で締結され
た一対のキャップ22に形成された上部円弧溝22aと
の間に回転自由に保持される。The hydraulic pivot 19 has an outer cylinder 19 whose lower end surface fits into the concave portion 15C of the lever 15, and whose peripheral surface is slidably inserted into the mounting hole 18a formed in the bracket 18.
a, an inner cylinder 19b that is fitted into the outer cylinder 19a, and a check valve 19d in a hydraulic chamber 19C formed between the two. The inner cylinder 19 is connected from the hydraulic pressure supply passage 18b formed inside the bracket 18.
The pulp clearance is kept constant by supplying hydraulic pressure to the hydraulic chamber 19c through the inside b and the check valve 19d. N The lift control cam 20 has four substantially flat cam surfaces 01 to C on its outer peripheral surface so as to increase the lift amount of the intake/exhaust valves 12 stepwise in the same rotational direction, and The bracket 18 is positioned at a position where the cam surface C1 that minimizes the lift amount with respect to the direction of rotation that reduces the lever 15 engages with the lever 15.
A stopper 20a that engages with a protrusion 18C formed on a part of the
, and has a hole 20b in the center thereof through which a cam control shaft 23 (described later) is inserted. Further, the outer circumferential surface of the cylindrical portion 20c formed to protrude from both sides of the lift control cam 20 is fastened to a lower circular groove 18d formed in the bracket 18 with a port 21 on the bracket 18, as shown in FIG. It is rotatably held between the upper arcuate grooves 22a formed in the pair of caps 22.
そして、気筒数個設けたリフト制御カム20の中心部を
貫通して形成された孔20bに一部のカム制御軸23を
通し、該カム制御軸23の各リフト制御カム20両側部
分に夫々嵌挿したコイルスプリング24の一端をカム制
御軸23外壁にねじ込んだ止め螺子23aに係止すると
共に、該コイルスプリング24の他端をリフト制御カム
20の円筒部20c側壁に形成した孔に嵌挿して係止す
る。Then, some of the cam control shafts 23 are passed through holes 20b formed by penetrating the center of the lift control cams 20 provided in several cylinders, and the cam control shafts 23 are fitted into both sides of each lift control cam 20, respectively. One end of the inserted coil spring 24 is locked to a set screw 23a screwed into the outer wall of the cam control shaft 23, and the other end of the coil spring 24 is inserted into a hole formed in the side wall of the cylindrical portion 20c of the lift control cam 20. to lock.
前記カム制御軸23の一端は、継手25を介して駆動手
段としてのステッピングモータ26の駆動軸26aに連
結されている。ステッピングモータ26はM?[1回路
27によりカム制御軸23を回転させるようになってい
る。One end of the cam control shaft 23 is connected via a joint 25 to a drive shaft 26a of a stepping motor 26 serving as a drive means. Is the stepping motor 26 M? [1 circuit 27 rotates the cam control shaft 23.
制御回路27はマイコン等で構成され、機関回転数、絞
り弁開度、冷却水温度、吸入空気流量、吸入負圧等の機
関運転条件に応じてカム面01〜C4の中からレバー1
5と係合するカム面を選択し、係合状態にあるカム面か
ら選択されたカム面への切換時、該選択されたカム面へ
の切換移動に相当する回転角分だけステッピングモータ
2Gに駆動パルスを出力してカム制御軸23を回転させ
るように、ステッピングモータ26を制御するようにな
っている。ここで、ステッピングモータ26の駆動速度
、即ち、カム制御軸23の回転速度は次のように設定さ
れている。The control circuit 27 is composed of a microcomputer, etc., and selects lever 1 from among cam surfaces 01 to C4 according to engine operating conditions such as engine speed, throttle valve opening, cooling water temperature, intake air flow rate, and intake negative pressure.
5, and when switching from the engaged cam surface to the selected cam surface, the stepping motor 2G is rotated by the rotation angle corresponding to the switching movement to the selected cam surface. The stepping motor 26 is controlled to rotate the cam control shaft 23 by outputting a drive pulse. Here, the driving speed of the stepping motor 26, ie, the rotational speed of the cam control shaft 23, is set as follows.
即ち、隣接するカム面相互の回転角分回転するのに要す
る時間をTとしたとき、次式が成り立つように設定され
る。That is, when the time required for adjacent cam surfaces to rotate by the rotation angle relative to each other is T, the following equation is set so as to hold true.
ここで、上式の右辺は、4サイクル機関のアイドル時に
おける吸・排気弁のリフト期間の2倍に相当する。Here, the right side of the above equation corresponds to twice the lift period of the intake and exhaust valves when the four-stroke engine is idling.
次に、本実施例の作用を説明する。Next, the operation of this embodiment will be explained.
例えば第1図に示すように、リフト制御カム20が最も
リフト量の大きいカム面C1でレバー15に当接し7て
いる状態では、レバー15が吸・排気弁駆動カム11側
に最も押し下げられた状態となる。このため、ロッカア
ーム13の背面13aに支点接触されるレバー15の下
面も下がり、支点接触点Aが吸・排気弁駆動カム11側
に移動しつつ吸・排気弁12に伝達され、第4図の曲線
Xに示すようにリフト量が大きく、かつ、開弁時期が早
く閉弁時期が遅い特性となる。For example, as shown in FIG. 1, when the lift control cam 20 is in contact with the lever 15 at the cam surface C1 with the largest lift amount, the lever 15 is pushed down the most toward the intake/exhaust valve drive cam 11. state. For this reason, the lower surface of the lever 15, which is in fulcrum contact with the back surface 13a of the rocker arm 13, also lowers, and the fulcrum contact point A moves toward the intake/exhaust valve drive cam 11 side and is transmitted to the intake/exhaust valves 12, as shown in FIG. As shown by curve X, the lift amount is large, and the valve opening timing is early and the valve closing timing is late.
一方、リフト制御カム20が回転し、例えば、リフト量
が小さいカム面C2でレバー15に当接するようにする
と、レバー15の吸・排気弁駆動カム11側の端部は凹
陥部15Cを支点とした揺動によって上昇し、レバー1
5の下面15dも上方に後退する。On the other hand, when the lift control cam 20 rotates and, for example, contacts the lever 15 with the cam surface C2 having a small lift amount, the end of the lever 15 on the intake/exhaust valve drive cam 11 side uses the concave portion 15C as a fulcrum. It rises due to the oscillation, and lever 1
The lower surface 15d of 5 also retreats upward.
レバー15の下面15dはロッカアーム13が吸・排気
弁駆動カム11のリフトを吸・排気弁12に伝えるため
の支点となるが、吸・排気弁駆動カム11がベースサー
クルでロッカアーム13に当接している状態の支点の初
期位置が、前記リフトff量大のカム面C4でレバー1
5が当接している時に比べて第1図で右側、即ち、リフ
ト後に支点が移動する方向から遠ざかる側に移動する。The lower surface 15d of the lever 15 serves as a fulcrum for the rocker arm 13 to transmit the lift of the intake/exhaust valve drive cam 11 to the intake/exhaust valves 12. The initial position of the fulcrum in the state where lever 1
5 moves to the right in FIG. 1 compared to when they are in contact, that is, to the side away from the direction in which the fulcrum moves after the lift.
この結果、第4図の曲線Yに示すように、リフト量が小
さく、かつ、開弁時期が遅れ、閉弁時期が早まる特性と
なる。As a result, as shown by curve Y in FIG. 4, the lift amount is small, the valve opening timing is delayed, and the valve closing timing is advanced.
このようにして、リフト制御カム20を回転してカム面
01〜C4のいずれかをレバー15に当接させることに
より、吸・排気弁12のリフト特性を段階的に変化させ
ることができる。In this way, by rotating the lift control cam 20 and bringing any of the cam surfaces 01 to C4 into contact with the lever 15, the lift characteristics of the intake/exhaust valves 12 can be changed in stages.
ここで、前記リフト制御カム20の回転は、機関運転条
件の変化を検出して作動する制御回路27がらの切換信
号に応じてステッピングモータ26の駆動によりカム制
御軸23及びコイルスプリング24を介して行われる。Here, the rotation of the lift control cam 20 is controlled via a cam control shaft 23 and a coil spring 24 by driving a stepping motor 26 in response to a switching signal from a control circuit 27 that detects changes in engine operating conditions and operates. It will be done.
次に、カム面の切換制御動作を第5図に示したフローチ
ャートを参照しつつ説明する。Next, the cam surface switching control operation will be explained with reference to the flowchart shown in FIG.
Slでは、機関回転数、絞り弁開度、冷却水温度、吸入
空気流量、吸入負圧等の信号に基づいて検出される機関
運転条件に最適の吸・排気弁の開閉特性が得られるよう
にカム面Cl−04の中から所定のカム面Cxを選択す
る。SL is designed to provide intake/exhaust valve opening/closing characteristics that are optimal for the engine operating conditions detected based on signals such as engine speed, throttle valve opening, cooling water temperature, intake air flow rate, and intake negative pressure. A predetermined cam surface Cx is selected from among the cam surfaces Cl-04.
S2では、前記選択されたカム面Cxが現在係合状態に
あるカム面Ciと一致しているか否かを判定し、この判
定がYESの場合は現状に維持し、Noであると判定さ
れた場合、即ち、係合カム面を切り換えるべきであると
判定された場合はS3へ進む。In S2, it is determined whether the selected cam surface Cx matches the cam surface Ci currently in the engaged state, and if this determination is YES, the current state is maintained, and it is determined that it is NO. In other words, if it is determined that the engaging cam surface should be switched, the process advances to S3.
S3では、現在係合状態にあるカム面Ciから81で選
択されたカム面Cxへの切換移動に要するリフト制御カ
ム20の回転角からステッピングモータ26へ与えられ
る駆動パルス数n iを設定する。In S3, the number n i of drive pulses given to the stepping motor 26 is set based on the rotation angle of the lift control cam 20 required for switching movement from the cam surface Ci currently in the engaged state to the cam surface Cx selected in 81.
S4では、S2で設定された数niの駆動パルスがステ
ッピングモータ26に出力される。これにより該モータ
26の駆動軸26a、継手25を介してカム制御軸23
が駆動パルスniに応じた所定角度回転する。In S4, the number ni drive pulses set in S2 are output to the stepping motor 26. As a result, the drive shaft 26a of the motor 26 is connected to the cam control shaft 23 via the joint 25.
is rotated by a predetermined angle according to the drive pulse ni.
S5で駆動パルス出力後設定時間後にステッピングモー
タ26への通電を短時間OFFとした上で、S6でステ
ッピングモータ26に弱い保持電流を通電し、S7で切
換保合後のカム面CxをC4にセットする。In S5, the power to the stepping motor 26 is turned off for a short time after a set time has elapsed after the drive pulse is output, and in S6, a weak holding current is applied to the stepping motor 26, and in S7, the cam surface Cx after switching and maintenance is changed to C4. set.
今、リフト量最小のカム面C1からリフト量大のカム面
C3への切換制御時について各気筒の切換動作を第6図
のタイムチャートを参照しつつ説明する。Now, the switching operation of each cylinder will be described with reference to the time chart of FIG. 6 when controlling the switching from the cam surface C1 with the minimum lift amount to the cam surface C3 with the large lift amount.
カム制御軸23が回動するタイミングで吸・排気弁12
がリフトしていないとき、ロッカアーム13とレバー1
5との接触支点は、略吸・排気弁12の上方近くに位置
するため、バルブスプリング28の反力は、リフト制御
カム20には作用せず、リフト制御カム20に作用する
力は、ロッカアーム13とレバー15との間に取り付け
られたスプリング16の弱い力のみとなる。したがって
、カム制御軸23の同転に、コイルスプリング24を介
してリフト制御カム20が追従して回転する。The intake/exhaust valve 12 is activated at the timing when the cam control shaft 23 rotates.
is not lifted, rocker arm 13 and lever 1
Since the contact fulcrum with 5 is located near the upper part of the intake/exhaust valve 12, the reaction force of the valve spring 28 does not act on the lift control cam 20, and the force acting on the lift control cam 20 is transferred to the rocker arm. Only a weak force is exerted by the spring 16 attached between the lever 13 and the lever 15. Therefore, the lift control cam 20 rotates following the same rotation of the cam control shaft 23 via the coil spring 24.
一方、カム制御軸23が回転するタイミングで、吸・排
気弁12がリフト中にあるときは、ロッカアーム13と
レバー15との接触支点が吸・排気弁駆動カム11側に
移動しているため、バルブスプリング2日の大きな反力
がロッカアーム13.レバー15を介してリフト制御カ
ム20に作用する。このため、リフト制御カム20は固
定されたままその両側のコイルスプリング24を捩じり
つつ、カム制御軸23のみが回転する。On the other hand, when the intake/exhaust valves 12 are in lift at the timing when the cam control shaft 23 rotates, the contact fulcrum between the rocker arm 13 and the lever 15 moves toward the intake/exhaust valve drive cam 11. A large reaction force on valve spring 2 causes rocker arm 13. It acts on the lift control cam 20 via the lever 15. Therefore, only the cam control shaft 23 rotates while the lift control cam 20 remains fixed while twisting the coil springs 24 on both sides thereof.
したがって、まず隣接するカム面01〜力ム面C2への
切換に際して、カム面C1,C2相互の境界部分がレバ
ー15と線接触係合状態にあって、かつ、レバー15か
らの反力によってリフト制御カム20に生じる回転モー
メントがカム面の切換方向とは逆向きに作用しているう
ちに吸・排気弁12のリフトが開始された場合は、バル
ブスプリング28の反力により、一旦切換前のカム面C
3がレバー15と面接触係合する位置まで戻され、その
分コイルスプリング24に捩じりトルクが蓄えられる(
第6図のa部分)。次に吸・排気弁のリフトが終了する
と、前記コイルスプリング24に蓄えられた捩じりトル
クによりリフト制御カム20がカム制御軸23に追従す
る位置まで回転する(第6図のb部分)。Therefore, when switching from the adjacent cam surface 01 to the force surface C2, the boundary between the cam surfaces C1 and C2 is in line contact engagement with the lever 15, and the reaction force from the lever 15 lifts the surface. If the lift of the intake/exhaust valves 12 is started while the rotational moment generated on the control cam 20 is acting in the opposite direction to the switching direction of the cam surface, the reaction force of the valve spring 28 will cause Cam surface C
3 is returned to the position where it engages in surface contact with the lever 15, and torsional torque is stored in the coil spring 24 accordingly (
part a of Figure 6). Next, when the lift of the intake and exhaust valves is completed, the torsional torque stored in the coil spring 24 causes the lift control cam 20 to rotate to a position where it follows the cam control shaft 23 (section b in FIG. 6).
このように回転が進行してレバー15からの反力により
リフト制御カム20に生じる回転モーメントがカム面C
2への切換方向と同一となった段階で吸・排気弁12の
リフトが開始されると、バルブスプリング28の反力に
より今度はカム面C2がレバー15と面接触係合する位
置まで瞬時に回転する(第6図のC部分)。この結果、
カム面C2への切換係合により吸・排気弁12のリフト
が増大する。以下、同様にしてカム面C2からカム面C
3への切換が行われる。尚、駆動パルス出力完了後、最
後の気筒の力り4面切換が確実に完了するまでの間、コ
イルスプリング24の捩りトルクを支持するためステッ
ピングモータ26への通電を継続し、その後一旦OFF
として支持トルクを解除してから、カム面C3をスプリ
ング16の反力と平らなカム面とによる自己修正作用で
レバー15と安定位置に係合させた後、この状態を維持
する保持トルクを発生ずるように小電流を通電する。As the rotation progresses in this way, the rotational moment generated in the lift control cam 20 due to the reaction force from the lever 15 is applied to the cam surface C.
When the lift of the intake/exhaust valve 12 is started at the same stage as the switching direction to 2, the reaction force of the valve spring 28 instantly moves the cam surface C2 to a position where it engages in surface contact with the lever 15. Rotate (section C in Figure 6). As a result,
The lift of the intake/exhaust valve 12 increases due to the switching engagement with the cam surface C2. From cam surface C2 to cam surface C in the same manner.
3 is performed. After the drive pulse output is completed, the stepping motor 26 is continuously energized to support the torsional torque of the coil spring 24 until the last cylinder's four-plane force switching is reliably completed, and then the stepping motor 26 is turned off once.
After releasing the supporting torque as shown in FIG. A small current is applied so that the
かかる切換制御において、カム制御軸23の回転速度を
、前記したように隣接するカム面相互の回転角分回転さ
せるのに要する時間が吸・排気弁のリフト期間の2倍以
上(第6図に示す実施例ではこれより十分大きい)とな
るように設定しであるため、以下に述べるように、滑ら
かでかつ安定した切換制御が行える。In such switching control, the time required to rotate the rotation speed of the cam control shaft 23 by the rotation angle of the adjacent cam surfaces as described above is more than twice the lift period of the intake and exhaust valves (as shown in FIG. 6). In the embodiment shown, the value is set to be sufficiently larger than this value, so that smooth and stable switching control can be performed as described below.
例えば、前記とは異なり第7図に示すように、カム制御
軸の回転速度を吸・排気弁のリフト期間が2つ離れたカ
ム面相互の回転角弁回転する大きさとなるように設定し
た場合、カム制御軸23の回転と共に吸・排気弁12の
リフトが開始されると、吸・排気弁12のリフト期間中
に、コイルスプリング24に前記2つのカム面相互の回
転角分に相当する大きな捩じりトルクが蓄えられる。そ
してリフト終了時には、この大きな捩りトルクによって
一気に2つ先のカム面へ切換えられるが、加速が大きい
ためリフト制御カム20は慣性による勢いでさらに先の
カム面切換方向まで回転し、不安定な位置に係合してし
まうおそれがある。For example, as opposed to the above case, as shown in Figure 7, if the rotational speed of the cam control shaft is set so that the lift period of the intake and exhaust valves is such that the rotation angle of the cam surfaces that are two intervals apart is such that the valves rotate. When the lift of the intake/exhaust valves 12 is started with the rotation of the cam control shaft 23, during the lifting period of the intake/exhaust valves 12, a large force is applied to the coil spring 24 corresponding to the rotation angle between the two cam surfaces. Torsional torque is stored. At the end of the lift, this large torsional torque causes the switch to the next cam surface at once, but due to the large acceleration, the lift control cam 20 rotates to the next cam surface due to momentum due to inertia, resulting in an unstable position. There is a risk that it may become engaged.
また、コイルスプリング24も大きな捩じりトルクが作
用するため、耐久性が低下する。Further, since a large torsional torque acts on the coil spring 24, its durability is reduced.
さらに、カム制御軸23の駆動手段として出力トルクの
大きなものが必要となり、特にステッピングモータ26
を使用する場合、トルクの増大によって脱調を生じ易く
なり、信顛性を低下させることとなる。Furthermore, as a drive means for the cam control shaft 23, a device with a large output torque is required, especially the stepping motor 26.
When using this, the increase in torque tends to cause step-out, which reduces reliability.
一方、カム制御軸23の回転速度を吸・排気弁のリフト
期間の約2倍の時間で隣接するカム面相互の回転角分回
転する大きさに設定した場合、コイルスプリング24の
捩りトルクが吸・排気弁のリフト期間中最大となるのは
第8図に示すような状態のときである。On the other hand, when the rotational speed of the cam control shaft 23 is set to such a value that the adjacent cam surfaces rotate by the mutual rotation angle in a time approximately twice the lift period of the intake/exhaust valves, the torsional torque of the coil spring 24 is・During the lift period of the exhaust valve, the maximum value is reached in the state shown in FIG.
即ち、カム制御軸23が回転し始めてから、隣接するカ
ム面相互間の回転角の約2の角度回転してカム面相互の
境界点がレバーに係合している時に吸・排気弁のリフト
が開始され、バルブスプリング28からの反力により切
換方向と逆向きに回転して切換前のカム面とレバーメが
係合する位置まで戻された後に、さらにカム制御軸23
の回転によりコイルスプリング24に捩じりトルクが蓄
えられる場合である。この場合、吸・排気弁12のリフ
トが完了するまでに略隣接するカム面相互の回転角分に
相当する捩じりトルクが蓄えられることになり、リフト
終了後、前記捩じりトルクにより適切な速度でカム制御
軸23が回転し、隣接するカム面への切換が行われる。That is, after the cam control shaft 23 starts rotating, the intake/exhaust valves are lifted when the cam control shaft 23 has rotated by an angle of about 2 times the rotation angle between the adjacent cam surfaces and the boundary point between the cam surfaces is engaged with the lever. The cam control shaft 23 is rotated in the opposite direction to the switching direction by the reaction force from the valve spring 28 and returned to the position where the cam surface and the lever engage before switching.
This is a case where torsional torque is stored in the coil spring 24 due to the rotation of the coil spring 24. In this case, until the lift of the intake/exhaust valve 12 is completed, torsional torque approximately equivalent to the mutual rotation angle of the adjacent cam surfaces is accumulated, and after the lift is completed, the torsional torque is appropriately applied. The cam control shaft 23 rotates at a certain speed, and switching to the adjacent cam surface is performed.
吸・排気弁12のリフトの開始が第8図に示す状態より
相対的に早められると、リフト開始時のリフト制御カム
20の戻り回転量が小さいため、リフト期間中に蓄えら
れるコイルスプリング24の捩じりトルク量は減少する
。If the start of the lift of the intake/exhaust valve 12 is relatively earlier than in the state shown in FIG. The amount of torsional torque decreases.
逆に、カム制御軸23の回転が第8図に示す状態より相
対的に早められると、吸・排気弁12のリフト開始まで
にリフト制御カム20が切換後のカム面に近い側まで回
転しているため、リフト開始時にバルブスプリング28
の反力を受けると、その時点でカム面が切り換えられる
。On the other hand, if the rotation of the cam control shaft 23 is relatively accelerated from the state shown in FIG. valve spring 28 at the start of the lift.
When the reaction force is received, the cam surface is switched at that point.
したがって、第8図に示すような状態のときがコイルス
プリング24に蓄えられる捩じりトルクは最大となり、
該最大の捩じりトルクは隣接するカム面相互の回転角分
に略相当する大きさであるから、切換時にリフト制御カ
ムが回転し過ぎることはなく、駆動パルスを連続して出
力し続けてもカム面への切換が1つずつ安定かつ確実に
行われる。Therefore, in the state shown in FIG. 8, the torsional torque stored in the coil spring 24 is maximum.
Since the maximum torsional torque is approximately equivalent to the rotation angle between the adjacent cam surfaces, the lift control cam does not rotate too much during switching and continues to output drive pulses. Also, switching to the cam surface is performed stably and reliably one by one.
また、コイルスプリング24に蓄えられる最大捩じりト
ルクを小さくできるため、耐久性が向上し、リフト制御
カム20とレバー15との係合面の摩耗を抑制できる。Furthermore, since the maximum torsional torque stored in the coil spring 24 can be reduced, durability is improved and wear of the engagement surface between the lift control cam 20 and the lever 15 can be suppressed.
さらに、駆動手段の出力トルクを軽減できるので、小型
化を図れ、特に構造が簡易で使用に供し易いステッピン
グモータ26を使用する場合、脱調の発生も抑制でき、
信軌性が向上する。Furthermore, since the output torque of the driving means can be reduced, the size can be reduced, and the occurrence of step-out can also be suppressed, especially when using the stepping motor 26, which has a simple structure and is easy to use.
Improves reliability.
尚、本実施例ではカム制御軸23の回転速度をアイドル
時の吸・排気弁のリフト期間を基準として設定したため
、アイドル以外の通常回転領域では、コイルスプリング
24に蓄えられる最大捩りトルクはさらに減少し、全回
転域に亘って安定した切換制御が行われるが、機関回転
数を検出し、カム面切換時の吸・排気弁のリフト期間を
基準としてカム制御軸23の回転速度を設定することに
より機関回転数に応じて制御速度を早めるようにしても
よい。In this embodiment, the rotational speed of the cam control shaft 23 is set based on the lift period of the intake and exhaust valves at idle, so in the normal rotation range other than idle, the maximum torsional torque stored in the coil spring 24 is further reduced. However, stable switching control is performed over the entire rotation range, but it is necessary to detect the engine rotation speed and set the rotation speed of the cam control shaft 23 based on the lift period of the intake and exhaust valves when switching the cam surface. The control speed may be increased according to the engine speed.
〈発明の効果〉
以上説明したように、本発明によれば、リフト制御カム
のカム面を陽子らな複数のカム面を備えた形状とし、リ
フト制御カムとカム制御軸とを回転軸回りに弾性を有し
た弾性部材を介して連結すると共に、カム制御軸の回転
速度を吸・排気弁のリフト期間を基準として設定するこ
とにより、カム面の切換制御時、吸・排気弁リフト中に
前記弾性部材に蓄えられる捩りトルクを最小限に抑える
ことができ、もって、カム面を1つずつ安定かつ確実に
切換係合させることができる。<Effects of the Invention> As explained above, according to the present invention, the cam surface of the lift control cam is shaped to include a plurality of protonated cam surfaces, and the lift control cam and the cam control shaft are arranged around the rotation axis. By connecting via an elastic member having elasticity and setting the rotational speed of the cam control shaft based on the lift period of the intake/exhaust valves, the above-mentioned rotational speed during the intake/exhaust valve lifts is achieved when controlling the switching of the cam surface. The torsional torque stored in the elastic member can be minimized, and the cam surfaces can be switched and engaged one by one stably and reliably.
また、弾性部材の捩じれ過ぎ防止により耐久性も向上で
き、さらにカム制御軸駆動手段の出力トルクを小さくし
て小型化を図ることもできる等種々の特長を備える。Further, durability can be improved by preventing excessive twisting of the elastic member, and furthermore, the output torque of the cam control shaft driving means can be reduced to achieve miniaturization, and other various features are provided.
第1図は本発明の第1の実施例を示す要部縦断面図、第
2図は同上実施例の要部平面図、第3図は同上実施例の
リフト制御カムのカム取付は方法を示す分解斜視図、第
4図は同上実施例の弁リフト特性を示すグラフ、第5図
は同上実施例のカム面切換制御ルーチンを示すフローチ
ャート、第6図は同上実施例のカム面切換時のタイムチ
ャート、第7図はカム制御軸の回転速度を大きく設定し
た場合の弁リフトとコイルスプリングに蓄えられる捩じ
りトルクの状態を示すタイムチャート、第8図はカム制
御軸の回転速度を小さくした場合の吸・排気弁の弁リフ
トとコイルスプリングの捩りトルクの状態を示すタイム
チャー1・、第9図は従来の内燃機関の吸・排気弁リフ
ト制御装置の一例を示す縦断面図である。
11・・・吸・排気弁駆動カム 12・・・吸・排気
弁13・・・ロッカアーム 15・・ルバー 20
・・・リフト制御カム 23川カム制御軸 24・
・・コイルスプリング 26・・・ステンピングモー
タ 27・・・制御回路 C6〜c4・・・カム
面
特許出願人 日産自動車株式会社
代理人 弁理士 笹 島 冨二雄
第3図
第40
2ランフII4
第5図Fig. 1 is a vertical cross-sectional view of the main parts of the first embodiment of the present invention, Fig. 2 is a plan view of the main parts of the same embodiment, and Fig. 3 shows how to install the lift control cam of the above embodiment. FIG. 4 is a graph showing the valve lift characteristics of the above embodiment, FIG. 5 is a flowchart showing the cam surface switching control routine of the above embodiment, and FIG. 6 is a flow chart showing the cam surface switching control routine of the above embodiment. Time chart, Figure 7 is a time chart showing the state of the valve lift and torsional torque stored in the coil spring when the rotation speed of the cam control shaft is set high, and Figure 8 is a time chart showing the state of the torsional torque stored in the coil spring when the rotation speed of the cam control shaft is set low. Time chart 1 showing the state of the valve lift of the intake/exhaust valve and the torsional torque of the coil spring when . 11... Intake/exhaust valve drive cam 12... Intake/exhaust valve 13... Rocker arm 15... Louver 20
...Lift control cam 23 River cam control axis 24.
... Coil spring 26 ... Stamping motor 27 ... Control circuit C6 - c4 ... Cam surface patent applicant Nissan Motor Co., Ltd. agent Patent attorney Fujio Sasashima Figure 3 Figure 40 2 Lumph II 4 Figure 5
Claims (1)
が係合するロッカアームの湾曲形成された背面を、該背
面に沿って機関本体に揺動自由に取付けられたレバーに
支点接触させ、該レバーの一端部に係合させたリフト制
御カムの回転量を制御してレバーの揺動位置を変化させ
ることにより、レバーとロッカアームとの接触する支点
位置を変化させて吸・排気弁のリフト特性を可変制御す
るようにした内燃機関の吸・排気弁リフト制御装置にお
いて、前記リフト制御カムに吸・排気弁リフト量を段階
的に変化させる略平らな複数のカム面を形成すると共に
、リフト制御カムと該リフト制御カムを回転させるカム
制御軸とを回転軸回りに弾性を有した弾性部材を介して
連結し、かつ、前記カム制御軸を機関運転条件に応じて
所定量回転駆動させる駆動手段を設け、該駆動手段によ
って駆動されるカム制御軸の回転速度をリフト制御カム
の隣接するカム面相互の回転角分回転するのに要する時
間が吸・排気弁のリフト期間の約2倍以上となるように
設定したことを特徴とする内燃機関の吸・排気弁リフト
制御装置。The curved back surface of the rocker arm, whose ends engage the intake/exhaust valve drive cam and the stem ends of the intake/exhaust valves, is brought into fulcrum contact with a lever that is swingably attached to the engine body along the back surface; By controlling the amount of rotation of a lift control cam engaged with one end of the lever and changing the rocking position of the lever, the fulcrum position where the lever and rocker arm come into contact is changed and the intake/exhaust valves are lifted. In an internal combustion engine intake/exhaust valve lift control device that variably controls characteristics, the lift control cam is formed with a plurality of substantially flat cam surfaces that change the amount of lift of the intake/exhaust valves in stages; A drive in which a control cam and a cam control shaft that rotates the lift control cam are connected via an elastic member having elasticity around the rotation axis, and the cam control shaft is rotated by a predetermined amount depending on engine operating conditions. means is provided, and the time required to rotate the rotation speed of the cam control shaft driven by the drive means by the mutual rotation angle of adjacent cam surfaces of the lift control cams is approximately twice or more than the lift period of the intake/exhaust valves. An intake/exhaust valve lift control device for an internal combustion engine, characterized in that it is set so that:
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP14218084A JPS6123813A (en) | 1984-07-11 | 1984-07-11 | Suction and exhaust valve lift control device for internal-combustion engine |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP14218084A JPS6123813A (en) | 1984-07-11 | 1984-07-11 | Suction and exhaust valve lift control device for internal-combustion engine |
Publications (1)
Publication Number | Publication Date |
---|---|
JPS6123813A true JPS6123813A (en) | 1986-02-01 |
Family
ID=15309229
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP14218084A Pending JPS6123813A (en) | 1984-07-11 | 1984-07-11 | Suction and exhaust valve lift control device for internal-combustion engine |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS6123813A (en) |
-
1984
- 1984-07-11 JP JP14218084A patent/JPS6123813A/en active Pending
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