JP2013221496A

JP2013221496A - High-efficiency rotary piston engine

Info

Publication number: JP2013221496A
Application number: JP2012121330A
Authority: JP
Inventors: Shuichi Kitamura; 修一北村
Original assignee: Individual
Current assignee: Individual
Priority date: 2012-04-16
Filing date: 2012-04-16
Publication date: 2013-10-28

Abstract

PROBLEM TO BE SOLVED: To remarkably improve efficiency and to implement ultra-low NOx emission by enabling ultra-lean burn by inducing HCCI (Homogeneous Charge Compression Ignition) burn in a low load area of an engine.SOLUTION: An exhaust gas control valve 14 is provided in an exhaust gas re-suction path 13 which is opened on an inner circumferential surface of a rotor housing and further, an intake air control valve 8 is provided in an intake air passage 6. In a low load area of an engine, the exhaust gas control valve 14 is opened to introduce a quantity of exhaust gas into a working chamber 4 and the intake air control valve 8 is closed to increase an effective compression ratio, thereby inducing HCCI burn. HCCI burn and spark ignition burn may be switched in accordance with operational conditions such as a load and a revolution speed of the engine.

Description

本発明は多量の排ガスを再吸入して圧縮開始・圧縮端温度を上昇させ、以って予混合圧縮着火燃焼を引き起して熱効率を改善する高効率ロータリピストン機関に関するものである。The present invention relates to a high-efficiency rotary piston engine in which a large amount of exhaust gas is re-inhaled to increase the compression start / end temperature, thereby causing premixed compression ignition combustion to improve thermal efficiency.

一般にロータリピストン機関では作動室内に吸入した吸気（混合気）を圧縮して点火プラグにより着火させ、これを火炎伝播によって燃焼を完結する様にしており、出力は吸入吸気を吸気絞り弁により絞る事によって制御している。従って最初に燃焼した部分は後から燃焼した部分によって断熱圧縮されるから、燃焼温度が高くなり、多量のＮＯｘが発生すると共に冷却損失が増大する。かつ吸気絞りによってポンプ損失が増加し、熱効率が悪化する。しかも極低負域では残留ガスの影響を受けて燃焼が不安定で希薄燃焼が困難である（点火プラグによる火花着火燃焼が困難）。In general, in a rotary piston engine, intake air (air mixture) sucked into a working chamber is compressed and ignited by a spark plug, and combustion is completed by flame propagation. Is controlled by. Therefore, since the first combusted portion is adiabatically compressed by the later combusted portion, the combustion temperature increases, a large amount of NOx is generated, and the cooling loss increases. In addition, the pump loss increases due to the intake throttle, and the thermal efficiency deteriorates. Moreover, in the extremely low negative region, the combustion is unstable and the lean combustion is difficult due to the influence of the residual gas (spark ignition combustion by the spark plug is difficult).

本発明の目的は、多量の排ガスを再吸入する事によって圧縮開始及び圧縮端温度を高めて予混合圧縮着火燃焼（ＨＣＣＩ燃焼）を引き起し、これにより点火プラグでは燃焼させ得ない（超）希薄混合気を燃焼させる事にある。この希薄燃焼法は吸気を絞る必要がない低温の燃焼法であるから、ポンプ損失がなくなって冷却損失が減少する結果、大幅な高効率化を達成できるものである。更には火炎伝播によらない圧縮自着火による燃焼法であるから、ＮＯｘの発生が殆どない燃焼法である。以上の如く熱効率の大幅な向上及び超低ＮＯｘエミッションを目的とする。The object of the present invention is to re-inhale a large amount of exhaust gas to raise the compression start and compression end temperatures to cause premixed compression ignition combustion (HCCI combustion), and therefore cannot be burned by a spark plug (super) It is to burn a lean mixture. Since this lean combustion method is a low temperature combustion method that does not require the intake air to be throttled, the pump loss is eliminated and the cooling loss is reduced. As a result, a significant increase in efficiency can be achieved. Furthermore, since this is a combustion method by compression self-ignition that does not depend on flame propagation, it is a combustion method that hardly generates NOx. As described above, the present invention aims to greatly improve thermal efficiency and ultra-low NOx emission.

課題を解決する為の手段Means to solve the problem

本発明は上記課題を解決する為、ローターハウジング内周面に開口する排ガス再吸入路に排ガス制御弁を備え、作動室内に吸気を導入する吸気通路に吸気制御弁を備え、エンジンの低負荷域では排ガス制御弁を開いて多量の排ガスを作動室内に導入すると共に吸気制御弁を閉じて有効圧縮比を高め、以って予混合圧縮着火燃焼を引き起し、エンジンの負荷、回転速度などの運転条件によって予混合圧縮燃焼と火花点火燃焼とを切り換える事を実行する様にした。In order to solve the above problems, the present invention is provided with an exhaust gas control valve in an exhaust gas re-intake passage that opens to the inner peripheral surface of a rotor housing, an intake control valve in an intake passage for introducing intake air into a working chamber, and a low load region of an engine. Then, open the exhaust gas control valve to introduce a large amount of exhaust gas into the working chamber and close the intake control valve to increase the effective compression ratio, thereby causing premixed compression ignition combustion, such as engine load, rotation speed, etc. Switching between premixed compression combustion and spark ignition combustion is performed according to the operating conditions.

発明の効果Effect of the invention

本発明によればエンジンの低負荷域では排ガス再吸入路１３から高温の排ガスを多量に作動室内に導入しており、更に１５位の高圧縮比（図３では１３位であるが、従来よりは高圧縮比である）の効果と相まって圧縮端温度が非常に高くなり、容易にＨＣＣＩ燃焼を引き起す事ができる。このＨＣＣＩ燃焼は火炎伝播を伴わない低温の急速燃焼の一形態で、超希薄燃焼が可能であり、冷却損失やポンプ損失が少なく比熱比が大きい為、高効率運動が可能である。かつＮＯｘの発生を殆ど０に抑える事ができる特長を有する。更に本発明では排ガス制御弁１４又は吸気制御弁８の開度を調整する事により圧縮端温度を制御できるから、困難とされるＨＣＣＩ燃焼そのものを制御する事が可能となり、熱効率を更に高め、ＨＣＣＩ燃焼領域を拡大する事ができる。
中・高負荷域では火花点火燃焼に切り換えるが、この領域では圧縮比に対し膨張比の方が高いサイクルとなるから熱効率が大幅に向上する。According to the present invention, a large amount of high-temperature exhaust gas is introduced into the working chamber from the exhaust gas re-intake passage 13 in the low load region of the engine, and the 15th high compression ratio (13th in FIG. Is a high compression ratio), the compression end temperature becomes very high, and HCCI combustion can easily be caused. This HCCI combustion is a form of rapid low-temperature combustion that does not involve flame propagation. Ultra-lean combustion is possible, and since cooling loss and pump loss are small and the specific heat ratio is large, high-efficiency motion is possible. And it has the feature that generation of NOx can be suppressed to almost zero. Further, in the present invention, since the compression end temperature can be controlled by adjusting the opening degree of the exhaust gas control valve 14 or the intake control valve 8, it is possible to control the difficult HCCI combustion itself, further increasing the thermal efficiency, and the HCCI. The combustion area can be expanded.
Switching to spark ignition combustion in the middle and high load range, but in this range, the expansion ratio is higher than the compression ratio, so the thermal efficiency is greatly improved.

発明を実施する為の形態BEST MODE FOR CARRYING OUT THE INVENTION

図１は本発明による高効率ロータリピストン機関で、ローター１はローターハウジング２とサイドハウジング３により囲まれた空間内に収められ、偏心軸（レシプロ機関のクランク軸に相当）及び位相歯車により公転・自転し、吸気・圧縮・膨張・排気の各行程を行なう。ロータリピストン機関としては唯一実用化されたバンケル機関を示すものである。
７は吸入吸気を絞って出力を制御する吸気絞り弁、１２は触媒コンバーター、９は吸気制御弁８を駆動するアクチュエーター、１５は排ガス制御弁１４を駆動するアクチュエーターである（吸気絞り弁７もアクチュエーターにより駆動する事が望ましい）。電子制御ユニット１７（以下ＥＣＵ）はＲＯＭ、ＲＡＭ、ＣＰＵ、入・出力ポート等から成るマイクロコンピューターを中心として構成され、これらは、双方向性バスによって相互に接続をされている。ＥＣＵ１７にはエンジンの運転状態の把握に必要なパラメーター用の各種センサー（例えばローター１を支持する偏心軸の回転角を検出する回転角センサー、エンジン回転速度センサー、アクセル開度を検出するアクセルセンサー、エンジン吸入吸気流量センサー、エンジン冷却水温を検出する水温センサー、大気圧センサー、Ｏ_２センサー、ノックセンサー等）からの各信号が対応するＡ／Ｄコンバーターを介して入力ポートに送信される。又、出力ポートは燃料噴射弁１０、点火プラグ１６、アクチュエーター９、１５等と各々対応する駆動回路を介して接続され、各々の制御信号を送信する。ＲＯＭには燃料噴射弁１０の噴射量や噴射時期を決定する為の制御ルーチン、点火プラグ１６への通電を制御する為の制御ルーチン等のエンジンを制御する為の制御ルーチンやそれらに用いられる制御値を含むマップが記憶されている。ＣＰＵはＲＯＭに記憶されているアプリケーションプログラムに従って動作し、燃料の噴射制御、点火時期制御等を実行する。
作動室４内に吸気通路５、６から吸入された吸気（混合気）は圧縮された後には自着火又は点火プラグ１６により点火されて燃焼し、膨張して仕事を為した上で排気通路１１から排出される。ローターハウジング２の内周面（ローター１のアペックスシールの摺動面）に開口する排ガス再吸入路１３には排ガス制御弁１４が備えられ、吸入行程中の作動室４内に導入される排ガス再吸入量を調整する。エンジンの始動時は排ガス制御弁１４は閉じており、点火プラグ１６によりエンジン始動が為される。
エンジン暖機後の低負荷域では排ガス制御弁１４は開、吸気通路６に備えられた吸気制御弁８は全閉となっており、従って吸気行程中にある作動室４内には多量の排ガス（既燃ガス）が導入され（排ガス再吸入路１３のローターハウジング内周面への開口部がローターの回転方向に進んだ位置にあるほど、より多量の排ガスが導入される）、圧縮始めの作動室内ガス温度は高くなる。かつ吸気制御弁８は閉じているから圧縮はローター１により吸気通路５の開口部が閉鎖された時点から始まり、吸気通路６から吸入側へ押し戻されない為、圧縮比は例えば１５位と高圧縮比となる（吸気制御弁８を開くと作動室４内の吸気は吸入側へ一定量押し戻されて圧縮比は低下し、例えば１２位となる）。
この時、圧縮比が１５の時は膨張比も同じく１５となる。以上の如く多量の排ガス再吸入量と１５位の高圧縮比の効果と相まって圧縮端温度は非常に高くなり（１０００Ｋ以上）、容易に予混合圧縮着火燃焼を引き起す事ができる（予混合圧縮着火燃焼法でも均質な混合気を用いるＨＣＣＩ燃焼法がより低ＮＯｘなので好ましく、以下ＨＣＣＩ燃焼法を採用するものとする）。ＨＣＣＩ燃焼法では燃焼の制御が重要であり、燃焼発生が圧縮上死点から大きく外れるとノッキングや失火の原因となる。従って燃料噴射量が増して燃焼圧力上昇率が高くなってノッキングに近い状態になると、ノックセンサーがこれを検出して（他に点火プラグ周辺のイオン電流を測定し、電流値の上昇により判断するセンサーもあり）ＥＣＵ１７は排ガス制御弁１４の開度が小さくなる様に指令して排ガス再吸入量を減少させ、圧縮始め及び圧縮端温度を低下させてノッキングを防止する様に制御するのである。又は、ＥＣＵ１７は吸気制御弁８の開度を増す様に指令して圧縮始め初期の作動室内ガスを吸気通路６から所定量吸入側へ押し戻し、圧縮比（有効圧縮比）を近似的に下げてノッキングを防止する様に制御する（有効圧縮比は１２までは下げられる）。
ＨＣＣＩ燃焼領域では吸気絞り弁７は原則として全開とするが、その開度を調整して吸気吸入を制御（これにより排ガス再吸入量が調整される）する様にしても良い。以上の如く吸気制御弁８、排ガス制御弁１４の開度を調整する事によりＨＣＣＩ燃焼領域における燃焼を制御する事ができ、熱効率を向上させ、ＨＣＣＩ燃焼領域を拡大する事ができる。
ＨＣＣＩ燃焼法は低温の希薄燃焼であるから、冷却損失やポンプ損失が少なく高効率運転が可能である。エンジンの中・高負荷域ではＨＣＣＩ燃焼法では燃焼圧力上昇率が過大となるので、点火プラグによる火花点火燃焼に切り換えるが、これはエンジンの負荷、回転速度などの運転条件によってＥＣＵ１７が実行する。この領域では吸気制御弁８は全開となり、従って圧縮行程の初期には吸気通路６を介して作動室４内のガスが一定量吸入側へ押し戻され、圧縮比は例えば１２と低圧縮比になり（但し、膨張比は１５位と高い）、ノッキングの発生は抑えられる。
又、この火花点火燃焼領域では排ガス制御弁１４は全閉となり、原則として排ガスの再循環は行なわれない（ＮＯｘ低減の為に若干開いても良い）。圧縮比に対し膨張比の方が高い領域であるから、熱効率の大幅な改善が可能である。ＨＣＣＩ燃焼領域ではＮＯｘの発生は殆どないが、火花点火燃焼領域では多量に発生し、これは理論混合比として三元触媒により浄化する。尚、吸気制御弁８の開度を調整する事により有効圧縮比を近似的に可変化できるから（１２〜１５）、エンジン暖機中はこれを例えば１４として燃焼の安定化を図っても良い。FIG. 1 shows a high-efficiency rotary piston engine according to the present invention, in which a rotor 1 is housed in a space surrounded by a rotor housing 2 and a side housing 3 and revolved by an eccentric shaft (corresponding to a crankshaft of a reciprocating engine) and a phase gear. Rotates and performs intake, compression, expansion, and exhaust strokes. This is the only practical Wankel engine as a rotary piston engine.
7 is an intake throttle valve that throttles intake air and controls the output, 12 is a catalytic converter, 9 is an actuator that drives the intake control valve 8, and 15 is an actuator that drives the exhaust gas control valve 14 (the intake throttle valve 7 is also an actuator). It is desirable to drive by). The electronic control unit 17 (hereinafter referred to as ECU) is mainly composed of a microcomputer comprising a ROM, a RAM, a CPU, an input / output port, etc., which are connected to each other by a bidirectional bus. The ECU 17 includes various sensors for parameters necessary for grasping the operating state of the engine (for example, a rotation angle sensor that detects the rotation angle of the eccentric shaft that supports the rotor 1, an engine rotation speed sensor, an accelerator sensor that detects the accelerator opening degree, Each signal from an engine intake / intake flow rate sensor, a water temperature sensor for detecting engine cooling water temperature, an atmospheric pressure sensor, an O ₂ sensor, a knock sensor, etc.) is transmitted to the input port via the corresponding A / D converter. Further, the output port is connected to the fuel injection valve 10, the spark plug 16, the actuators 9, 15 and the like via corresponding drive circuits, and transmits respective control signals. The ROM has a control routine for controlling the engine, such as a control routine for determining the injection amount and injection timing of the fuel injection valve 10, a control routine for controlling the energization of the spark plug 16, and controls used for them. A map containing the values is stored. The CPU operates in accordance with an application program stored in the ROM, and executes fuel injection control, ignition timing control, and the like.
The intake air (air mixture) sucked into the working chamber 4 from the intake passages 5 and 6 is compressed and then ignited or burned by self-ignition or a spark plug 16, expands and performs work, and then the exhaust passage 11. Discharged from. The exhaust gas re-intake passage 13 opened on the inner peripheral surface of the rotor housing 2 (sliding surface of the apex seal of the rotor 1) is provided with an exhaust gas control valve 14, and the exhaust gas re-introduction passage introduced into the working chamber 4 during the intake stroke. Adjust the amount of inhalation. The exhaust gas control valve 14 is closed when the engine is started, and the engine is started by the spark plug 16.
In the low load range after the engine warms up, the exhaust gas control valve 14 is open and the intake control valve 8 provided in the intake passage 6 is fully closed, so that a large amount of exhaust gas is placed in the working chamber 4 during the intake stroke. (Burned gas) is introduced (a larger amount of exhaust gas is introduced as the opening of the exhaust gas re-intake passage 13 to the inner peripheral surface of the rotor housing advances in the rotational direction of the rotor). The operating room gas temperature increases. And since the intake control valve 8 is closed, compression starts when the opening of the intake passage 5 is closed by the rotor 1 and is not pushed back from the intake passage 6 to the intake side, so the compression ratio is as high as 15th, for example. (When the intake control valve 8 is opened, the intake air in the working chamber 4 is pushed back to the intake side by a certain amount, and the compression ratio decreases, for example, becomes 12th).
At this time, when the compression ratio is 15, the expansion ratio is also 15. As described above, combined with the effect of a large amount of exhaust gas re-inhalation and the 15th high compression ratio, the compression end temperature becomes very high (1000 K or more), and premixed compression ignition combustion can be easily caused (premixed compression). The HCCI combustion method using a homogeneous air-fuel mixture is also preferable in the ignition combustion method because it has lower NOx, and hereinafter, the HCCI combustion method is adopted). Combustion control is important in the HCCI combustion method, and if the occurrence of combustion deviates significantly from the compression top dead center, it may cause knocking or misfire. Therefore, when the fuel injection amount increases and the combustion pressure increase rate becomes high and it becomes close to knocking, the knock sensor detects this (in addition, the ion current around the spark plug is measured and judged by the increase in current value). The ECU 17 controls the exhaust gas control valve 14 so as to prevent the knocking by decreasing the exhaust gas re-intake amount and decreasing the compression start temperature and the compression end temperature. Alternatively, the ECU 17 commands the opening degree of the intake control valve 8 to increase and pushes the initial working chamber gas from the intake passage 6 back to the predetermined amount suction side by starting compression, and approximately lowers the compression ratio (effective compression ratio). Control is performed to prevent knocking (the effective compression ratio is reduced to 12).
In principle, the intake throttle valve 7 is fully opened in the HCCI combustion region. However, it is also possible to control the intake air intake by adjusting its opening (this adjusts the exhaust gas re-intake amount). As described above, by adjusting the opening degree of the intake control valve 8 and the exhaust gas control valve 14, combustion in the HCCI combustion region can be controlled, thermal efficiency can be improved, and the HCCI combustion region can be expanded.
Since the HCCI combustion method is a low temperature lean combustion, it is possible to operate with high efficiency with little cooling loss and pump loss. In the middle / high load range of the engine, the combustion pressure increase rate becomes excessive in the HCCI combustion method, and therefore, switching to spark ignition combustion using a spark plug is performed by the ECU 17 depending on operating conditions such as engine load and rotation speed. In this region, the intake control valve 8 is fully opened. Therefore, in the initial stage of the compression stroke, the gas in the working chamber 4 is pushed back to the intake side through the intake passage 6 and the compression ratio becomes a low compression ratio of 12, for example. (However, the expansion ratio is as high as 15th place), the occurrence of knocking is suppressed.
Further, in this spark ignition combustion region, the exhaust gas control valve 14 is fully closed, and in principle, the exhaust gas is not recirculated (may be slightly opened to reduce NOx). Since the expansion ratio is higher than the compression ratio, the thermal efficiency can be greatly improved. Although almost no NOx is generated in the HCCI combustion region, a large amount is generated in the spark ignition combustion region, and this is purified by a three-way catalyst as a theoretical mixing ratio. Since the effective compression ratio can be approximately varied by adjusting the opening degree of the intake control valve 8 (12 to 15), this may be set to 14, for example, to stabilize combustion during engine warm-up. .

図１では吸気通路を二分割して吸気通路６に吸気制御弁８を備えていたが、図２（イ）の如く一本化した吸気通路１８とし、この吸気通路１８に吸気制御弁１９を備えても良い。吸気制御弁１９はＡ方向から見た断面を示す図２（ロ）の如くその先端部はサイドハウジング３の内壁面から微小ギャップ（０．１ｍｍ位）だけ引っ込んだ位置にあってこれが全閉状態であり、この領域（ＨＣＣＩ燃焼領域）では圧縮比は１５位となり、吸気制御弁１９が全開してサイドハウジング内壁面から離れて外側へ引っ込むと（火花点火燃焼領域）、作動室内のガスは圧縮行程において一定量吸気通路１８内へ（吸入側へ）押し戻されるから、圧縮比は１２位と低圧縮比となる。吸気制御弁１９の中間開度では圧縮比は１２から１５まで近似的に可変圧縮比となる。図２（ハ）は、図１において吸気通路６をローターハウジングに形成したものに相当する実施例である。図は吸気制御弁２１が全閉の状態であるが、全閉の状態では吸気制御弁２１の先端部はローターハウジング２の内周面から微小ギャップ（０．１ｍｍ位）引っ込んだ位置にあり、これによりローター１のアペックスシールが通過してもその前後が連通状態となる事はない。図２（ニ）は図１において排気通路１１と排ガス再吸入路１３とを一体とした構造に相当する実施例で、排ガス制御弁２２はこれに適合した構造を有するものである。即ち、図は排ガス制御弁２２を全開とした状態であるが、排ガスは排ガス制御弁２２の下流部に形成される排ガス再吸入路２３を経て吸入行程にある作動室４内へ再吸入される。排ガス制御弁２２を全閉とすれば、ローターハウジング２の内周面から０．１ｍｍ位微小ギャップだけ引っ込んだ位置にあり、これによりローター１のアペックスシールが通過してもその前後が連通状態になる事はない。排ガス制御弁２２が中間開度にある時は排ガス再吸入量もそれに応じて制御される。図１では点火プラグ１６は２個備えているが、図２（ホ）に示す実施例は一方のサイドハウジングに２個備えて合計４個としたもので、その分必要とされる火炎伝播距離が短かくて済み、燃焼期間の短縮化により急速燃焼が可能であり、熱効率が向上する効果がある。更にもう一方のサイドハウジングにも点火プラグを２個備えて合計６個とすると、より一層燃焼期間が短縮され、熱効率が向上する。又、これにより点火時期を遅角化することも可能となり、ＮＯｘの発生を抑え込む事ができる（上死点又はそれ以降の点火時期としてＮＯｘを完全に０とする事もできる）。In FIG. 1, the intake passage is divided into two and the intake passage 6 is provided with the intake control valve 8. However, the intake passage 18 is unified as shown in FIG. You may prepare. As shown in FIG. 2 (b), which shows a cross section viewed from the direction A, the intake control valve 19 has its tip end retracted from the inner wall surface of the side housing 3 by a minute gap (about 0.1 mm), which is in a fully closed state. In this region (HCCI combustion region), the compression ratio is 15th, and when the intake control valve 19 is fully opened and retracted away from the inner wall surface of the side housing (spark ignition combustion region), the gas in the working chamber is compressed. In the stroke, it is pushed back into the intake passage 18 by a certain amount (to the suction side), so the compression ratio becomes the 12th place and the low compression ratio. At an intermediate opening of the intake control valve 19, the compression ratio is approximately a variable compression ratio from 12 to 15. FIG. 2 (c) shows an embodiment corresponding to the intake passage 6 formed in the rotor housing in FIG. In the figure, the intake control valve 21 is in a fully closed state. In the fully closed state, the tip of the intake control valve 21 is in a position where a minute gap (about 0.1 mm) is retracted from the inner peripheral surface of the rotor housing 2. Thereby, even if the apex seal of the rotor 1 passes, the front and back of the apex seal will not be in communication. FIG. 2 (d) is an embodiment corresponding to the structure in which the exhaust passage 11 and the exhaust gas re-intake passage 13 are integrated in FIG. 1, and the exhaust gas control valve 22 has a structure adapted to this. That is, the figure shows a state in which the exhaust gas control valve 22 is fully opened, but the exhaust gas is re-inhaled into the working chamber 4 in the intake stroke through the exhaust gas re-intake passage 23 formed in the downstream portion of the exhaust gas control valve 22. . If the exhaust gas control valve 22 is fully closed, it is in a position retracted by a minute gap of about 0.1 mm from the inner peripheral surface of the rotor housing 2, so that the front and back of the rotor 1 are in communication with each other even if the apex seal of the rotor 1 passes. There will never be. When the exhaust gas control valve 22 is at the intermediate opening, the exhaust gas re-intake amount is also controlled accordingly. Although two spark plugs 16 are provided in FIG. 1, the embodiment shown in FIG. 2 (e) is provided with two on one side housing, for a total of four, and the required flame propagation distance. Is short, and rapid combustion is possible by shortening the combustion period, which has the effect of improving thermal efficiency. Furthermore, if the other side housing is also provided with two spark plugs for a total of six, the combustion period is further shortened and the thermal efficiency is improved. In addition, this makes it possible to retard the ignition timing and suppress the generation of NOx (NOx can be completely zero as the top dead center or the ignition timing thereafter).

図１、２では吸気制御弁８（１９）の開度を制御して（有効）圧縮比を可変化していたが、圧縮比を可変化せず常に一定としてＨＣＣＩ燃焼を引き起し、エンジンの負荷、回転速度などの運転条件により火花点火燃焼に切り換える様にする事もできる。即ち、図３においてローター１により吸気通路２４が閉鎖された時点から圧縮が始まり、この時の圧縮比は常時一定である（例えば１３と一定、膨張比も１３と一定）。エンジンの低負荷域では排ガス制御弁１４は開いており、従って図１で説明した通り排ガス再吸入路１３から多重の排ガスが作動室４内に再吸入され、圧縮始め及び圧縮端温度を大幅に上昇させ、ＨＣＣＩ燃焼を引き起し易くする（圧縮１３は従来に対しては十分に高圧縮比である）。中・高負荷域では排ガス制御弁１４は全閉とし（ＮＯｘ低減の為、若干開いてたＧＲを行なっても良い）、点火プラグによる火花点火燃焼に切り換える。
この領域ではノッキングを防ぐ事が重要であり、圧縮１３は少し高いので、ノッキングを防ぐ為に点火時期を遅角化するが、それによる熱効率の低下を回避する為に図示の如く点火プラグ１６を４〜６個と、４個以上備えて急速燃焼を達成する様にする（これは既に図２（ホ）で述べた）。
火花点火燃焼領域で発生するＮＯｘは理論混合比を用いて三元触媒で浄化する事ができる。In FIGS. 1 and 2, the opening of the intake control valve 8 (19) is controlled (effectively) to vary the compression ratio. It is also possible to switch to spark ignition combustion depending on the operating conditions such as the load and rotation speed. That is, in FIG. 3, compression starts when the intake passage 24 is closed by the rotor 1, and the compression ratio at this time is always constant (for example, constant at 13 and the expansion ratio is also constant at 13). In the low load region of the engine, the exhaust gas control valve 14 is open, so that multiple exhaust gases are re-inhaled from the exhaust gas re-intake passage 13 into the working chamber 4 as described with reference to FIG. To increase HCCI combustion (compression 13 has a sufficiently high compression ratio compared to the prior art). In the middle / high load range, the exhaust gas control valve 14 is fully closed (slightly opened GR may be performed to reduce NOx) and switched to spark ignition combustion with a spark plug.
In this region, it is important to prevent knocking. Since the compression 13 is slightly high, the ignition timing is retarded to prevent knocking. However, in order to avoid a decrease in thermal efficiency, the spark plug 16 is Four to six and four or more are provided to achieve rapid combustion (this has already been described with reference to FIG. 2 (e)).
NOx generated in the spark ignition combustion region can be purified by a three-way catalyst using a theoretical mixing ratio.

一般にロータリピストン機関では吸入吸気はローターハウジング２の短軸方向から流れて来て作動室４内に流入するので、スワールが形成されず良好な燃焼が得られない。この欠点を解消するには、図４（イ）の如く吸入吸気がローターハウジング２の長軸方向（Ｙ方向、短軸方向はＸ方向）から流れて来て作動室４内に流入する様に吸気通路２５を形成すれば良い。こうするとＢ方向から見た断面を示す図４（ロ）の如く、吸入吸気は作動室４内に流入すると、ローターハウジング２の内周面に衝突して向きを斜めにサイドハウジング３の方向に変えるから、図示の如くスワールが形成され、良好な燃焼が得られる。この場合、吸気通路２５を図４（ハ）の如く二分割して、吸気通路２５ｂをエンジン低速域では閉鎖弁２６により閉鎖しておくと、より強いスワールを形成する事ができる。又、一般にロータリピストン機関ではサイドハウジングに吸気通路を備えているが、これは高速域では吸気効率が低下する。これを解決するには図４（ニ）の如くローターハウジング内周面に開口する吸気通路３０を更に備え、エンジンの高速域ではアクチュエーターにより高速制御弁３１を開く様にすれば良い。エンジンの低速域では図示の状態から高速制御弁３１を閉じると、ローターハウジング内周面に近接する近接面３２（０．１ｍｍ位の微小ギャップを以って近接する）を有する構造によりローターのアペックスシールが通過してもその前後が連通状態とならないから、過大なオーバーラップは防がれ、燃焼が安定化する。以上は本発明のみならず、従来のロータリピストン機関にも実施できるものである。
尚、高速制御弁３１はスイング式であるが、図２（ハ）の如くスライド式でも良い。In general, in a rotary piston engine, intake and intake air flows from the minor axis direction of the rotor housing 2 and flows into the working chamber 4, so that no swirl is formed and good combustion cannot be obtained. In order to eliminate this drawback, as shown in FIG. 4 (a), the intake and intake air flows from the major axis direction of the rotor housing 2 (the Y direction and the minor axis direction is the X direction) and flows into the working chamber 4. The intake passage 25 may be formed. In this way, as shown in FIG. 4B showing a cross section viewed from the direction B, when the intake air flows into the working chamber 4, it collides with the inner peripheral surface of the rotor housing 2, and the direction is inclined in the direction of the side housing 3. As a result, swirls are formed as shown, and good combustion is obtained. In this case, if the intake passage 25 is divided into two as shown in FIG. 4C and the intake passage 25b is closed by the closing valve 26 in the engine low speed region, a stronger swirl can be formed. In general, a rotary piston engine is provided with an intake passage in a side housing, but this reduces the intake efficiency in a high speed range. In order to solve this, as shown in FIG. 4 (d), an intake passage 30 that opens to the inner peripheral surface of the rotor housing may be further provided, and the high speed control valve 31 may be opened by an actuator in the high speed region of the engine. When the high speed control valve 31 is closed from the illustrated state in the low speed region of the engine, the rotor apex has a structure having a proximity surface 32 (adjacent with a minute gap of about 0.1 mm) close to the inner peripheral surface of the rotor housing. Even if the seal passes, the front and back of the seal are not in communication, so excessive overlap is prevented and combustion is stabilized. The above is applicable not only to the present invention but also to a conventional rotary piston engine.
The high speed control valve 31 is a swing type, but may be a slide type as shown in FIG.

図３においてはノッキングを回避する為、冷却した排ガスを導入する事もできる。
即ち図５において、排ガス冷却器２８（例えば多管型水冷式）によって十分に冷却した排ガスをエンジンの高負荷域では導入弁２９を開いて吸気通路２４内へ導入し、作動室４内へ吸入させるのであり、これにより高圧縮比でもノッキングを防ぐ事ができる（中負荷域でも導入弁２９を開いてＮＯｘ低減を図っても良い）。この場合、吸気絞り弁２７の開度を調整する事により吸気通路２４内へ導入する排ガス量を制御する事ができる。尚、点火プラグ１６は４個以上とする事が望ましい。In FIG. 3, in order to avoid knocking, it is possible to introduce cooled exhaust gas.
That is, in FIG. 5, the exhaust gas sufficiently cooled by the exhaust gas cooler 28 (for example, a multi-tube type water cooling type) is introduced into the intake passage 24 by opening the introduction valve 29 in the high load region of the engine and sucked into the working chamber 4. Thus, knocking can be prevented even at a high compression ratio (NOx reduction can be achieved by opening the introduction valve 29 even in the middle load range). In this case, the amount of exhaust gas introduced into the intake passage 24 can be controlled by adjusting the opening of the intake throttle valve 27. It should be noted that the number of spark plugs 16 is preferably four or more.

一般に２サイクル機関では低負荷域においては多量の残留ガスにより不整燃焼が発生し、熱効率が大幅に悪化する。これを解決するには予混合圧縮着火燃焼を採用する事が最善である。即ち、図６（イ）において、この２サイクル機関ではピストンなどの潤滑を４サイクル機関と同様とする為に、排気弁３４，掃気弁３９，掃気ポンプ４０（例えばルーツブロワ）を備えており、ピストン下死点前の所定のクランク角度で先ず排気弁３４が開き、若干遅れて掃気弁３９が開いて掃気ポンプ４０からの掃気（空気）によりシリンダー内が掃気され、ピストン上昇行程においては先ず排気弁３４が閉じ、若干遅れて掃気弁３９が閉じる様になっている（各弁は図示しないカムによって、駆動される）。図６（ロ）は図６（イ）を上方から見た図であるが。燃焼室３５の周囲はスキッシュ部Ｓとなっており、燃焼室３５には掃気弁３９が備えられ、３点以上の火花ギャップ（３個以上の点火プラグ３６）が臨んでいる（掃気弁３９と排気弁３４とを入れ替えて排気弁３４を燃焼室３５に備えても良い）。
点火プラグ３６は３点以上の多点着火方式となるから、燃焼期間が飛躍的に短縮化され、着火時期を大幅に遅らせて（上死点又はそれ以降とする事も可能）ＮＯｘを低減させ、ノッキングの心配がないから１２〜１４位の高圧縮比を採用する事ができる。エンジンの低負荷域では吸気絞り弁４１により吸入吸気を制限して（又は、可変速手段により掃気ポンプ４０の回転を下げて）多量の既燃ガスをシリンダー内に留まる様にする事ができるから、１２〜１４位の高圧縮比の効果と相まって圧縮端温度が非常に高くなり、容易に予混合圧縮着火燃焼（均質な混合気を用いるＨＣＣＩ燃焼が望ましい）を引き起す事ができる。これは超希薄燃焼であるから（点火プラグでは着火燃焼不可）、不整燃焼は解消され、ＮＯｘの発生も殆どない。エンジンの中・高負荷域では図１と同様に図示しないＥＣＵの指令により火花点火燃焼に切り換えられる。この領域ではシリンダー内残留ガスが減少しており、点火プラグによる良好な燃焼が得られ、着火時期が大幅に遅角化されているから、２サイクル機関特有の内部ＥＧＲの効果と相まってＮＯｘ発生は低く抑えられる。
図６（ハ）は掃気弁３９ａ、３９ｂの閉時期に差を設けたもので、例えば掃気弁３９ａは下死点後７０℃Ａで閉、掃気弁３９ｂは下死点後３０℃Ａで閉とし、従ってエンジンの低負荷域では閉鎖弁４２を全閉とすると掃気弁３９ａ、３９ｂは全体として見れば下死点後３０℃Ａで閉としたものに等しくなるから、高圧縮比（例えば１８）となり、ＨＣＣＩ燃焼をより容易に引き起す事ができる。閉鎖弁４２を全開とすれば掃気弁３９ａ、３９ｂは全体として見れば下死点後７０℃Ａで閉としたものに等しく、従って圧縮比は低下し（例えば１３）、ノッキングは起らない。図６（ニ）は掃気弁３９の上流側にリード弁４７を有するバイパス路４６を備えたもので、エンジンの低負荷域では閉鎖弁４４をアクチュエター４５により閉じておくとリード弁４７により逆流が防がれ（掃気弁３９を下死点で閉じたのと同等）、高圧縮比となるからＨＣＣＩ燃焼をより容易に引き起す事ができる。閉鎖弁４４を開くと逆流が可能となるので、圧縮始めは掃気弁３９が閉じた時点となり、低圧縮比となってメッキングを防ぐ。尚、図６（イ）では排気弁３４、掃気弁３９をロッカーアームを用いるなどして同一のカム軸で駆動する様にし、掃気弁３４の開時期及び掃気弁３９の閉時期を適切に選んで例えば有効膨張比を１８、有効圧縮比を１３としておけば、エンジンの低負荷域でカム軸の位相を移動させる事により（開閉時期を早める）有効圧縮比を１５位まで高圧縮比化できるので、ＨＣＣＩ燃焼をより容易に引き起す事ができる。In general, in a two-cycle engine, irregular combustion occurs due to a large amount of residual gas in a low load region, and thermal efficiency is greatly deteriorated. To solve this, it is best to adopt premixed compression ignition combustion. That is, in FIG. 6 (a), this two-cycle engine is provided with an exhaust valve 34, a scavenging valve 39, and a scavenging pump 40 (for example, a roots blower) in order to make lubrication of the piston and the like the same as in a four-cycle engine. First, the exhaust valve 34 opens at a predetermined crank angle before the bottom dead center, the scavenging valve 39 opens slightly later, and the inside of the cylinder is scavenged by scavenging (air) from the scavenging pump 40. 34 is closed and the scavenging valve 39 is closed a little later (each valve is driven by a cam (not shown)). FIG. 6B is a view of FIG. 6A as viewed from above. The combustion chamber 35 is surrounded by a squish portion S. The combustion chamber 35 is provided with a scavenging valve 39, and three or more spark gaps (three or more spark plugs 36) are faced (with the scavenging valve 39 and the scavenging valve 39). The exhaust valve 34 may be replaced with the exhaust valve 34 in the combustion chamber 35).
Since the spark plug 36 is a multi-point ignition system with 3 or more points, the combustion period is dramatically shortened, and the ignition timing is greatly delayed (it is possible to set the top dead center or later) to reduce NOx. Since there is no worry of knocking, a high compression ratio of 12-14 can be adopted. In the low load region of the engine, intake intake air can be restricted by the intake throttle valve 41 (or the rotation of the scavenging pump 40 can be lowered by the variable speed means) so that a large amount of burned gas can remain in the cylinder. The compression end temperature becomes very high in combination with the effect of a high compression ratio of about 12 to 14, and premixed compression ignition combustion (HCCI combustion using a homogeneous mixture is desirable) can be easily caused. Since this is ultra lean combustion (ignition combustion is not possible with a spark plug), irregular combustion is eliminated and NOx is hardly generated. In the middle / high load range of the engine, switching to spark ignition combustion is performed in accordance with a command from an ECU (not shown) as in FIG. In this region, the residual gas in the cylinder is reduced, good combustion by the spark plug is obtained, and the ignition timing is greatly retarded, so the generation of NOx coupled with the effect of internal EGR unique to the two-cycle engine It can be kept low.
FIG. 6 (c) shows a difference in the closing timing of the scavenging valves 39a and 39b. For example, the scavenging valve 39a is closed at 70 ° C. after bottom dead center, and the scavenging valve 39b is closed at 30 ° C. after bottom dead center. Therefore, when the closing valve 42 is fully closed in the low load region of the engine, the scavenging valves 39a and 39b are equal to those closed at 30 ° C. after bottom dead center as a whole. HCCI combustion can be caused more easily. When the shut-off valve 42 is fully opened, the scavenging valves 39a and 39b are generally equivalent to those closed at 70 ° C. after bottom dead center, and therefore the compression ratio is reduced (for example, 13) and knocking does not occur. FIG. 6 (d) is provided with a bypass passage 46 having a reed valve 47 on the upstream side of the scavenging valve 39. When the closing valve 44 is closed by the actuator 45 in the low load region of the engine, the reed valve 47 causes a reverse flow. Is prevented (equivalent to closing the scavenging valve 39 at the bottom dead center) and the compression ratio becomes high, so that HCCI combustion can be caused more easily. When the closing valve 44 is opened, a reverse flow is possible. Therefore, the scavenging valve 39 is closed when the scavenging valve 39 is closed, and the compression ratio is lowered to prevent mech. In FIG. 6A, the exhaust valve 34 and the scavenging valve 39 are driven by the same camshaft by using a rocker arm or the like, and the opening timing of the scavenging valve 34 and the closing timing of the scavenging valve 39 are appropriately selected. For example, if the effective expansion ratio is 18 and the effective compression ratio is 13, the effective compression ratio can be increased to 15th by moving the phase of the camshaft in the low load region of the engine (fastening the opening / closing timing). Therefore, HCCI combustion can be caused more easily.

本発明による高効率ロータリピストン機関の図。1 is a diagram of a high efficiency rotary piston engine according to the present invention. 本発明の各種実施例を示す図。The figure which shows the various Example of this invention. 本発明による高効率ロータリピストン機関の図。1 is a diagram of a high efficiency rotary piston engine according to the present invention. 作動室内にスワールを形成させる吸気通路を有するロータリ機関の図。The figure of the rotary engine which has an intake passage which forms a swirl in a working chamber. 冷却した排ガスを再吸入させるロータリピストン機関の図。The figure of the rotary piston engine which re-inhales the cooled exhaust gas. 排気弁、掃気弁を有する２サイクル機関を示す図。The figure which shows the 2-cycle engine which has an exhaust valve and a scavenging valve.

１はローター、２はローターハウジング、３はサイドハウジング、４は作動室、５・６・１８・２０・２４・２５・２５ａ・２５ｂ・３０・３３は吸気通路、７・２７は吸気絞り弁、８・２１は吸気制御弁、９・１５・４３・４５はアクチュエーター、１０は燃料噴射弁、１１は排気通路、１２は触媒コンバーター、１３・２３は排ガス再吸入路、１４・２２は排ガス制御弁、１６は点火プラグ、１７はＥＣＵ、１９は吸気制御弁、２６は閉鎖弁、２８は排ガス冷却器、２９は導入弁、３２は高速制御弁、３４は排気弁、３５は燃焼室、３６は点火プラグ、３７は燃料噴射弁、３８は掃気通路、３９・３９ａ・３９ｂは掃気弁、４０は掃気ポンプ、４１は吸気絞り弁、４２は閉鎖弁、４４は閉鎖弁、４６はバイパス路、４７はリード弁、Ｓはスキッシュ部である。1 is a rotor, 2 is a rotor housing, 3 is a side housing, 4 is a working chamber, 5 · 6 · 18 · 20 · 24 · 25 · 25a · 25b · 30 · 33 are intake passages, 7 and 27 are intake throttle valves, 8 and 21 are intake control valves, 9, 15, 43 and 45 are actuators, 10 is a fuel injection valve, 11 is an exhaust passage, 12 is a catalytic converter, 13 and 23 are exhaust gas re-intake passages, and 14 and 22 are exhaust gas control valves. , 16 is an ignition plug, 17 is an ECU, 19 is an intake control valve, 26 is a closing valve, 28 is an exhaust gas cooler, 29 is an introduction valve, 32 is a high speed control valve, 34 is an exhaust valve, 35 is a combustion chamber, 36 is Spark plug, 37 is a fuel injection valve, 38 is a scavenging passage, 39, 39a and 39b are scavenging valves, 40 is a scavenging pump, 41 is an intake throttle valve, 42 is a closing valve, 44 is a closing valve, 46 is a bypass passage, 47 Is reed valve, S is A quiche part.

Claims

ローターハウジング及びサイドハウジングにより囲まれた空間内にローターを収納して吸気・圧縮・膨張・排気の各行程を行なうロータリピストン機関において、前記ローターハウジング内周面に開口する排ガス再吸入路に排ガス制御弁を備え、更に作動室内に吸気を導入する吸気通路に吸気制御弁を備え、エンジンの低負荷域では前記排ガス制御弁を開いて多量の排ガスを作動室内に導入すると共に、前記吸気制御弁を閉じて有効圧縮比を高め、以って予混合圧縮着火燃焼を引き起し、エンジンの負荷、回転速度などの運転条件によって予混合圧縮着火燃焼と火花点火燃焼とを切り換える事を特徴とする高効率ロータリピストン機関。In a rotary piston engine that houses the rotor in a space surrounded by the rotor housing and the side housing and performs intake, compression, expansion, and exhaust strokes, exhaust gas control is performed on the exhaust gas re-intake passage that opens on the inner peripheral surface of the rotor housing And an intake control valve in an intake passage for introducing intake air into the working chamber. In the low load region of the engine, the exhaust gas control valve is opened to introduce a large amount of exhaust gas into the working chamber. Closed to increase the effective compression ratio, thereby causing premixed compression ignition combustion and switching between premixed compression ignition combustion and spark ignition combustion depending on the operating conditions such as engine load and rotation speed Efficiency rotary piston engine.

点火プラグを４個以上備えた請求項１記載の高効率ロータリピストン機関。The high-efficiency rotary piston engine according to claim 1, comprising four or more spark plugs.

ローターハウジング及びサイドハウジングにより囲まれた空間内にローターを収納して吸気・圧縮・膨張・排気の各行程を行なうロータリピストン機関において、前記ローターハウジング内周面に開口する排ガス再吸入路に排ガス制御弁を備え、エンジンの低負荷域では前記排ガス制御弁を開いて多量の排ガスを作動室内に導入し、以って予混合圧縮着火燃焼を引き起し、かつ点火プラグを４個以上備え、エンジンの負荷、回転速度などの運転条件によって予混合圧縮着火燃焼と火花点火燃焼とを切り換える事を特徴とする高効率ロータリピストン機関。In a rotary piston engine that houses the rotor in a space surrounded by the rotor housing and the side housing and performs intake, compression, expansion, and exhaust strokes, exhaust gas control is performed on the exhaust gas re-intake passage that opens on the inner peripheral surface of the rotor housing Provided with a valve, and in the low load range of the engine, the exhaust gas control valve is opened to introduce a large amount of exhaust gas into the working chamber, thereby causing premixed compression ignition combustion and four or more spark plugs. A high-efficiency rotary piston engine characterized by switching between premixed compression ignition combustion and spark ignition combustion depending on the operating conditions such as the load and rotation speed of the engine.