JP2019049239A - In-cylinder pressure suppression device - Google Patents

In-cylinder pressure suppression device Download PDF

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JP2019049239A
JP2019049239A JP2017174478A JP2017174478A JP2019049239A JP 2019049239 A JP2019049239 A JP 2019049239A JP 2017174478 A JP2017174478 A JP 2017174478A JP 2017174478 A JP2017174478 A JP 2017174478A JP 2019049239 A JP2019049239 A JP 2019049239A
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cylinder
pressure
oil
valve
oil passage
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森 石井
Shin Ishii
森 石井
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Hino Motors Ltd
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Abstract

To provide an in-cylinder pressure suppression device capable of certainly suppressing the maximum cylinder internal pressure of an engine with only high load operation region without requiring a complicated variable valve mechanism.SOLUTION: An in-cylinder pressure suppression device comprises: a dedicated cam 7x assigned to each of cylinders 1 for a cam shaft 6 of the valve system and expanded; a master piston 12 operated by the dedicated cam 7x from the closing of an intake valve 4 in the corresponding cylinder 1 to the start of fuel injection in each of the dedicated cams 7x; a slave piston 14 connected to the master piston 12 via an oil passage 13 and opening the intake valve 4 of the cylinder 1 when an oil pressure is generated in the oil passage 13 by the operation of the master piston 12; hydraulic oil supply means (solenoid valve 16 and control valve 17) for switching holding and release of hydraulic pressure in each of the oil passages 13; and a control device 19 for holding the oil pressure of each oil passage 13 by hydraulic oil supply means when the engine is driven in the high load operation region.SELECTED DRAWING: Figure 1

Description

本発明は、筒内圧力抑制装置に関するものである。   The present invention relates to an in-cylinder pressure control device.

従来、エンジンの高圧縮比化を図ることで熱効率を上げて燃費を改善する手法が知られており、このような手法を用いて燃費を改善するにあたっては、高負荷運転領域での最大筒内圧力の増大に関する対策が必要不可欠であるが、高負荷運転領域での運転のためだけに従来より高い最大筒内圧力に耐え得るようエンジンを刷新したのでは、設備コストの大幅な高騰を招く結果となって燃費改善に向けた費用対効果が低くなってしまう。   Heretofore, there has been known a method for improving the fuel efficiency by increasing the thermal efficiency by aiming at a high compression ratio of the engine. In order to improve the fuel efficiency using such a method, the maximum in-cylinder in the high load operation region is known. It is essential to take measures against pressure increase, but if the engine has been upgraded to withstand the higher maximum in-cylinder pressure just for operation in the high load operating range, the equipment cost will increase dramatically. Cost-effectiveness for fuel efficiency improvement.

このため、既存のエンジン及び動弁系をそのまま利用して高負荷運転領域だけで最大筒内圧力を抑制することが可能な対策が求められており、燃料噴射のタイミングを遅角（リタード）する手法や、吸気弁の遅閉じにより吸入空気の一部を筒内から逃がす手法が既に提案されている（例えば下記の特許文献１等を参照）。   For this reason, there is a need for measures capable of suppressing the maximum in-cylinder pressure only in the high load operating region by using the existing engine and valve system as it is, and retarding the timing of fuel injection. A method or a method of releasing part of the intake air from the inside of the cylinder by the late closing of the intake valve has already been proposed (see, for example, Patent Document 1 described below).

特開２０１７−１３７８３０号公報JP, 2017-137830, A

しかしながら、燃料噴射のタイミングを遅角（リタード）する手法では、燃費を改善するために行った高圧縮比化により燃費の悪化を招いてしまうという本末転倒の問題を招きかねず、また、吸気弁の遅閉じにより吸入空気の一部を筒内から逃がす手法では、複雑な可変バルブ機構が必要となって設備コストの大幅な高騰を招いてしまう虞れがある。   However, the method of retarding the timing of fuel injection may lead to the problem of overturning the fuel efficiency due to the increase in compression ratio performed to improve the fuel efficiency, and also in the intake valve. In the method in which a part of the intake air is released from the inside of the cylinder by the late closing, a complicated variable valve mechanism may be required, which may cause a significant increase in the equipment cost.

尚、複雑な可変バルブ機構を用いることなく吸気弁の遅閉じを実現するために、該吸気弁を遅閉じさせるプロフィールを持つ吸気カムに変更することも考えられるが、このようにした場合、全運転領域で吸入空気の一部が筒内から逃げてしまう結果となり、燃費の改善効果を十分に得ることができなくなる。   In addition, in order to realize the late closing of the intake valve without using a complicated variable valve mechanism, it is conceivable to change to an intake cam having a profile for closing the intake valve, but in such a case, it is possible to As a result, part of the intake air escapes from the inside of the cylinder in the operating range, and it is not possible to obtain a sufficient improvement in fuel efficiency.

本発明は上述の実情に鑑みてなしたもので、複雑な可変バルブ機構を要することなく高負荷運転領域のみでエンジンの最大筒内圧力を確実に抑制し得る筒内圧力抑制装置を提供することを目的とする。   The present invention has been made in view of the above-described circumstances, and provides an in-cylinder pressure suppression device capable of reliably suppressing the maximum in-cylinder pressure of the engine only in the high load operation region without requiring a complicated variable valve mechanism. With the goal.

本発明は、動弁系のカムシャフトに対し各気筒毎に割り当てて増設された専用カムと、該専用カムの夫々が対応する気筒における吸気弁の閉から燃料噴射の開始までの間に前記専用カムにより作動するマスターピストンと、該マスターピストンに対し油通路を介して接続され且つ該油通路に前記マスターピストンの作動により油圧が発生した際に当該気筒の吸気弁を開作動するスレーブピストンと、前記油通路の夫々における油圧の保持・開放を切り替える作動油供給手段と、少なくとも高負荷運転領域でのエンジン駆動時に前記各油通路の油圧を前記作動油供給手段により保持せしめる制御装置とを備えたことを特徴とする筒内圧力抑制装置、に係るものである。   According to the present invention, the dedicated cam allocated to each cylinder for the camshaft of the valve system and the dedicated cam from the closing of the intake valve in the cylinder corresponding to each of the dedicated cams to the start of the fuel injection A master piston operated by a cam, and a slave piston connected to the master piston via an oil passage and opening the intake valve of the cylinder when an oil pressure is generated in the oil passage by the operation of the master piston; The hydraulic oil supply means for switching between holding and release of the hydraulic pressure in each of the oil passages, and a control device for holding the hydraulic pressure of each oil passage by the hydraulic oil supply means at least when the engine is operated in the high load operation region. The in-cylinder pressure suppression device is characterized in that

而して、最大筒内圧力に余裕のない高負荷運転領域でのエンジン駆動時に、制御装置により作動油供給手段を制御して各油通路の油圧を保持させておくと、各気筒で吸気弁の閉から燃料噴射の開始までの間に専用カムによりマスターピストンが作動されて油通路に油圧が発生し、スレーブピストンにより当該気筒の吸気弁が強制的に開作動されて吸入空気の一部が筒内から逃がされ、該吸入空気の量が減ることで最大筒内圧力が抑制されることになる。   Thus, when the engine is driven in the high load operating region where there is no margin for the maximum in-cylinder pressure, the hydraulic oil supply means is controlled by the control device to hold the oil pressure of each oil passage. Between the closing of the valve and the start of fuel injection, the master piston is operated by the dedicated cam and oil pressure is generated in the oil passage, and the intake valve of the cylinder is forcibly opened by the slave piston and a part of the intake air is The maximum in-cylinder pressure is suppressed by being released from the cylinder and the amount of the intake air being reduced.

他方、最大筒内圧力に余裕のある低負荷運転領域や中負荷運転領域でのエンジン駆動時に、制御装置により作動油供給手段を制御して各油通路の油圧を解放しておくと、専用カムによりマスターピストンが作動されても油通路に油圧が発生しなくなってスレーブピストンが従動しなくなり、吸気弁は通常のバルブ操作により吸気行程でのみ開作動され、これ以外のタイミングで開作動されることはなくなるので、エンジンを高圧縮比化して熱効率を上げることによる燃費の改善効果が十分に得られる。   On the other hand, when the engine is driven in the low load operation area or the medium load operation area where the maximum in-cylinder pressure is sufficient, the control device controls the hydraulic oil supply means to release the oil pressure of each oil passage. Therefore, even if the master piston is actuated, the hydraulic pressure is not generated in the oil passage and the slave piston does not follow, and the intake valve is opened only in the intake stroke by normal valve operation and opened at other timings. As a result, the fuel efficiency can be sufficiently improved by increasing the engine compression ratio to increase the thermal efficiency.

また、本発明においては、燃料噴射が実施されない制動時にも油通路の油圧を作動油供給手段により保持せしめ得るように制御装置を構成することも可能であり、燃料噴射が実施されない制動時に制御装置により作動油供給手段を制御して油通路の油圧を保持させておくと、専用カムによりマスターピストンが作動されて油通路に油圧が発生し、スレーブピストンにより当該気筒の吸気弁が強制的に開作動されて圧縮圧力が開放され、次の膨張行程におけるピストンを押し下げる力が喪失して圧縮行程で得た制動力が有効に作用すると共に、膨張行程にあっても抵抗がかかるようになってエンジンブレーキが増強されることになり、本発明の筒内圧力抑制装置を圧縮圧開放型エンジンブレーキとして活用することが可能となる。   Further, in the present invention, it is also possible to configure the control device so that the hydraulic pressure of the oil passage can be held by the hydraulic fluid supply means even when the fuel injection is not performed. When the hydraulic pressure in the oil passage is maintained by controlling the hydraulic oil supply means, the master piston is operated by the dedicated cam and the hydraulic pressure is generated in the oil passage, and the intake valve of the relevant cylinder is forcibly opened by the slave piston. It is operated to release the compression pressure, the force to depress the piston in the next expansion stroke is lost, and the braking force obtained in the compression stroke works effectively, and the engine also becomes resistant even in the expansion stroke. The brake is enhanced, and the in-cylinder pressure suppression device of the present invention can be utilized as a compression pressure release engine brake.

更に、このように本発明を圧縮圧開放型エンジンブレーキとしても活用する場合には、専用カムによりマスターピストンを作動させるタイミングを圧縮上死点に近づくよう燃料噴射の開始直前に設定しておくことが好ましく、このようにすれば、エンジンブレーキを増強する効果を最大限に得ることが可能となる。   Furthermore, when the present invention is also utilized as a compression pressure release engine brake as described above, the timing for operating the master piston by the dedicated cam is set immediately before the start of fuel injection so as to approach compression top dead center. In this way, it is possible to obtain the maximum effect of enhancing the engine brake.

上記した本発明の筒内圧力抑制装置によれば、下記の如き種々の優れた効果を奏し得る。   According to the in-cylinder pressure suppression device of the present invention described above, the following various excellent effects can be obtained.

（Ｉ）本発明の請求項１に記載の発明によれば、複雑な可変バルブ機構を要することなく既存のエンジン及び動弁系をそのまま利用して高負荷運転領域のみでエンジンの最大筒内圧力を確実に抑制することができるので、エンジンを高圧縮比化して熱効率を上げることによる燃費の改善を設備コストの大幅な高騰を回避しつつ実現することができる。   (I) According to the first aspect of the present invention, the maximum in-cylinder pressure of the engine can be obtained only in the high load operating region by using the existing engine and valve system as it is without requiring a complicated variable valve mechanism. As a result, the fuel efficiency can be improved by increasing the engine compression ratio to increase the thermal efficiency while avoiding a significant increase in the facility cost.

（ＩＩ）本発明の請求項２に記載の発明によれば、本発明の筒内圧力抑制装置を制動時に圧縮圧開放型エンジンブレーキとしても活用することができ、制動時におけるエンジンブレーキの増強効果を得ることができる。   (II) According to the invention described in claim 2 of the present invention, the in-cylinder pressure suppression device of the present invention can be utilized also as a compression pressure release type engine brake at the time of braking, and the enhancing effect of the engine brake at the time of braking You can get

（ＩＩＩ）本発明の請求項３に記載の発明によれば、本発明の筒内圧力抑制装置を制動時に圧縮圧開放型エンジンブレーキとして活用するにあたり、エンジンブレーキを増強する効果を最大限に得ることができる。   (III) According to the third aspect of the present invention, in utilizing the in-cylinder pressure suppression device of the present invention as a compression pressure release engine brake at the time of braking, the effect of enhancing the engine brake can be maximized. be able to.

本発明を実施する形態の一例を示す概略図である。It is the schematic which shows an example of the form which implements this invention. 図１の専用カムを周辺構造と共に示した平面図である。It is the top view which showed the exclusive cam of FIG. 1 with peripheral structure. 本形態例の作動タイミングについて説明するグラフである。It is a graph explaining the operation timing of this example of a form. 本形態例の作動タイミングについて説明するＰＶ線図である。It is a PV diagram explaining the operation timing of the present embodiment. 本形態例の制動力小の作動タイミングについて説明するＰＶ線図である。It is a PV diagram for explaining the operation timing of the small braking force in the present embodiment. 本形態例の制動力大の作動タイミングについて説明するＰＶ線図である。It is a PV diagram for explaining the operation timing of the large braking force of this embodiment.

以下、本発明の実施の形態を図面を参照しつつ説明する。   Hereinafter, embodiments of the present invention will be described with reference to the drawings.

図１〜図６は本発明の筒内圧力抑制装置を実施する形態の一例を示すもので、本形態例においては、トラックやバス等の大型車両に採用されている既存の圧縮圧開放型エンジンブレーキの基本構造を利用しており、図１及び図２中における符号の１は気筒、２は燃焼室、３はピストン、４は吸気弁、５は吸気流路を夫々示しており、吸気行程でカムシャフト６に装備した吸気カム７により一端を押し上げられて傾動するロッカーアーム８の他端によりバルブブリッジ９を介し両方の吸気弁４が押し下げられて開作動され、吸気流路５から気筒１内に吸入空気１０が取り込まれるようになっている。   1 to 6 show an example of an embodiment for implementing the in-cylinder pressure suppression device of the present invention, and in the present embodiment, an existing compression pressure release engine employed in a large vehicle such as a truck or a bus 1 and 2 indicate cylinders, 2 indicates a combustion chamber, 3 indicates a piston, 4 indicates an intake valve, and 5 indicates an intake flow passage. At the other end of the rocker arm 8 whose one end is pushed up and tilted by the intake cam 7 mounted on the camshaft 6, both intake valves 4 are pushed down and opened through the valve bridge 9 and the intake passage 5 to the cylinder 1 The intake air 10 is taken inside.

ここで、前記カムシャフト６に、各気筒１毎に割り当てられた専用カム７ｘが前記吸気カム７に隣接して増設されていると共に、前記吸気弁４の開作動を担うロッカーアーム８が軸支されているロッカーシャフト１５には、当該気筒１の吸気行程で開いた吸気弁４が閉となってから燃料噴射が開始されるまでの間における適宜なタイミングで前記専用カム７ｘにより一端を押し上げられて傾動するロッカーアーム８ｘが前記ロッカーアーム８に隣接して増設されている。   Here, a dedicated cam 7x assigned to each cylinder 1 is added to the camshaft 6 adjacent to the intake cam 7, and a rocker arm 8 responsible for opening the intake valve 4 is axially supported. One end of the rocker shaft 15 is pushed up by the dedicated cam 7x at an appropriate timing from when the intake valve 4 opened in the intake stroke of the cylinder 1 is closed to when fuel injection is started. A rocker arm 8x that tilts in an inclined manner is extended adjacent to the rocker arm 8.

そして、前記ロッカーアーム８ｘの一端が上方の油圧ユニット１１に備えられたマスターピストン１２を押し上げ、前記油圧ユニット１１内に穿設された油通路１３に圧力を発生させて当該気筒１の上方にあるスレーブピストン１４を従動させ、該スレーブピストン１４により当該気筒１のロッカーアーム８の他端側上部を押し下げてバルブブリッジ９を介し両方の吸気弁４を開作動させるようにしてある。   Then, one end of the rocker arm 8x pushes up the master piston 12 provided in the upper hydraulic unit 11, generates pressure in the oil passage 13 bored in the hydraulic unit 11, and is above the cylinder 1 The slave piston 14 is driven, and the upper end of the other side of the rocker arm 8 of the cylinder 1 is pushed down by the slave piston 14 to open both intake valves 4 through the valve bridge 9.

また、前記油通路１３には、油圧の保持・開放を切り替える為の作動油供給手段であるソレノイドバルブ１６及びコントロールバルブ１７を介し作動油１８（エンジンオイル）が供給されるようになっており、前記ソレノイドバルブ１６は、エンジン制御コンピュータ（ＥＣＵ：Electronic Control Unit）を成す制御装置１９からの制御信号１６ａにより作動油１８の供給・遮断を行い、前記コントロールバルブ１７は、ソレノイドバルブ１６が開いた状態で前記油通路１３の油圧が保持されるよう逆止弁として機能し且つソレノイドバルブ１６が閉じた状態では前記油通路１３の油圧をリリーフ口２０へと開放するよう機能するようになっている。   Further, hydraulic oil 18 (engine oil) is supplied to the oil passage 13 via a solenoid valve 16 and a control valve 17 which are hydraulic oil supply means for switching between holding and release of hydraulic pressure. The solenoid valve 16 supplies and shuts off the hydraulic oil 18 by a control signal 16a from a control device 19 forming an engine control computer (ECU: Electronic Control Unit), and the control valve 17 is in a state where the solenoid valve 16 is opened. It functions as a check valve so that the oil pressure of the oil passage 13 is maintained, and functions to open the oil pressure of the oil passage 13 to the relief port 20 when the solenoid valve 16 is closed.

ここで、前記制御装置１９においては、少なくとも高負荷運転領域でのエンジン駆動時に前記ソレノイドバルブ１６を開けて前記各油通路１３の油圧を保持せしめるようにしているが、本形態例にあっては、制動時における圧縮圧開放型エンジンブレーキとしての活用も想定しており、燃料噴射が実施されない制動時にも前記各油通路１３の油圧を保持せしめ得るようにしてある。   Here, in the control device 19, the solenoid valve 16 is opened at least when the engine is driven in the high load operation region to hold the oil pressure of each of the oil passages 13. However, in the present embodiment, The use as a compression pressure release type engine brake at the time of braking is also assumed, so that the oil pressure of each oil passage 13 can be held even at the time of braking where fuel injection is not performed.

尚、図２に示されている通り、前記吸気カム７が装備されているカムシャフト６には、排気カム７’（図１では位相違いにより図示無し）も装備されており、該排気カム７’により一端を押し上げられて傾動するロッカーアーム８’の他端によりバルブブリッジ９’を介し両方の排気弁４’が押し下げられて開作動され、これにより燃焼室２から排気流路２１（図１参照）へと排気ガス２２（図１参照）が送出されるようになっている。   Incidentally, as shown in FIG. 2, an exhaust cam 7 ′ (not shown due to a phase difference in FIG. 1) is also equipped on the camshaft 6 on which the intake cam 7 is equipped. The other exhaust valve 4 'is pushed down and opened by the other end of the rocker arm 8' whose one end is pushed up and tilted by the valve bridge 9 ', whereby the exhaust flow path 21 from the combustion chamber 2 (FIG. Exhaust gas 22 (see FIG. 1) is delivered to the reference).

而して、最大筒内圧力に余裕のない高負荷運転領域でのエンジン駆動時に、制御装置１９からの制御信号１６ａによりソレノイドバルブ１６を開けて各油通路１３の油圧を保持させておくと、図３のグラフ及び図４のＰＶ線図に示すように、吸気弁４の閉（図３及び図４中にIVC：Intake valve closeで示す）から燃料噴射の開始（図３及び図４中にSOI：Start of injectionで示す）までの間（図３及び図４中にＡで示す）に専用カム７ｘによりマスターピストン１２が作動されて油通路１３に油圧が発生し、スレーブピストン１４により当該気筒１の吸気弁４が強制的に開作動されて吸入空気１０の一部が筒内から逃がされ、該吸入空気１０の量が減ることで最大筒内圧力が抑制されることになる。   Thus, when the engine is driven in a high load operation region where there is no margin for the maximum in-cylinder pressure, if the solenoid valve 16 is opened by the control signal 16a from the control device 19 to hold the oil pressure of each oil passage 13; As shown in the graph of FIG. 3 and the PV diagram of FIG. 4, the start of fuel injection from the closing of the intake valve 4 (indicated by IVC: Intake valve close in FIGS. 3 and 4) (in FIGS. 3 and 4) The master piston 12 is actuated by the dedicated cam 7x until the SOI (shown by A in FIG. 3 and FIG. 4) until the start of injection is generated, and the hydraulic pressure is generated in the oil passage 13. The first intake valve 4 is forcibly opened and a part of the intake air 10 is released from the cylinder, and the amount of the intake air 10 is reduced, whereby the maximum in-cylinder pressure is suppressed.

他方、最大筒内圧力に余裕のある低負荷運転領域や中負荷運転領域でのエンジン駆動時に、制御装置１９からの制御信号１６ａによりソレノイドバルブ１６を開けて各油通路１３の油圧を解放しておくと、専用カム７ｘによりマスターピストン１２が作動されても油通路１３に油圧が発生しなくなってスレーブピストン１４が従動しなくなり、吸気弁４は通常のバルブ操作により吸気行程でのみ開作動され、これ以外のタイミングで開作動されることはなくなるので、エンジンを高圧縮比化して熱効率を上げることによる燃費の改善効果が十分に得られる。   On the other hand, when the engine is driven in the low load operating range or the medium load operating range where the maximum in-cylinder pressure is sufficient, the solenoid valve 16 is opened by the control signal 16a from the control device 19 to release the oil pressure of each oil passage 13 Then, even if the master piston 12 is actuated by the dedicated cam 7x, no hydraulic pressure is generated in the oil passage 13 and the slave piston 14 does not follow, and the intake valve 4 is opened only in the intake stroke by normal valve operation. Since the valve is not opened at any other timing, the fuel efficiency can be sufficiently improved by increasing the compression ratio of the engine to increase the thermal efficiency.

また、本形態例においては、制動時における圧縮圧開放型エンジンブレーキとしての活用も想定しているが、燃料噴射が実施されない制動時に制御装置１９からの制御信号１６ａによりソレノイドバルブ１６を開けて各油通路１３の油圧を保持させておくと、専用カム７ｘによりマスターピストン１２が作動されて油通路１３に油圧が発生し、スレーブピストン１４により当該気筒１の吸気弁４が強制的に開作動されて圧縮圧力が開放され、次の膨張行程におけるピストン３を押し下げる力が喪失して圧縮行程で得た制動力が有効に作用すると共に、膨張行程にあっても抵抗がかかるようになってエンジンブレーキが増強されることになり、本発明の筒内圧力抑制装置を圧縮圧開放型エンジンブレーキとして活用することが可能となる。   Moreover, in this embodiment, utilization as a compression pressure release type engine brake at the time of braking is also assumed, but at the time of braking where fuel injection is not performed, the solenoid valve 16 is opened by the control signal 16a from the control device 19 When the oil pressure in the oil passage 13 is held, the master piston 12 is operated by the dedicated cam 7x to generate the oil pressure in the oil passage 13, and the intake valve 4 of the cylinder 1 is forcibly opened by the slave piston 14 The compression pressure is released, the force to depress the piston 3 in the next expansion stroke is lost, and the braking force obtained in the compression stroke is effectively applied, and resistance is applied even in the expansion stroke, thus the engine brake As a result, the in-cylinder pressure suppression device of the present invention can be utilized as a compression release type engine brake.

また、このように本発明の筒内圧力抑制装置を圧縮圧開放型エンジンブレーキとして活用する場合には、専用カム７ｘによりマスターピストン１２を作動させるタイミングを圧縮上死点に近づくよう燃料噴射の開始直前に設定しておくことが好ましく、このようにすれば、エンジンブレーキを増強する効果を最大限に得ることが可能となる。   Further, when the in-cylinder pressure suppression device of the present invention is utilized as a compression pressure release type engine brake as described above, the fuel injection is started so that the timing for operating the master piston 12 by the dedicated cam 7x approaches compression top dead center. It is preferable to set immediately before, which makes it possible to maximize the effect of enhancing the engine brake.

即ち、吸気弁４の閉（図３及び図４中にIVC：Intake valve closeで示す）から燃料噴射の開始（図３及び図４中にSOI：Start of injectionで示す）までの間（図３及び図４中にＡで示す）で吸気弁４を強制的に開作動するといっても、図５のＰＶ線図にＰ1で示すように、吸気弁４の閉（IVC）に近いところで吸気弁４を直ぐに開けた場合には、図５中にＢ（EVO:Exhaust valve openは排気弁４’の開を示す）で示す範囲の小さな制動力しか得られないのに対し、図６のＰＶ線図にＰ2で示すように、燃料噴射の開始（SOI）直前に吸気弁４を開けた場合は、該吸気弁４を開けるタイミングが圧縮上死点に近づき、図６中にＣで示す範囲の大きな制動力が得られることになる。 That is, from the closing of the intake valve 4 (indicated by IVC: Intake valve close in FIGS. 3 and 4) to the start of fuel injection (indicated by SOI: Start of injection in FIGS. 3 and 4) (FIG. 3) and even if the forcibly opening operation of the intake valve 4 in indicated by a) in FIG. 4, as indicated by P 1 in the PV diagram of FIG. 5, an intake as close to the closed (IVC) of the intake valve 4 When the valve 4 is opened immediately, only a small braking force in the range indicated by B (EVO: Exhaust valve open indicates the opening of the exhaust valve 4) in FIG. 5 can be obtained, while the PV of FIG. as indicated by P 2 in the diagram, if you open the start (SOI) intake valve 4 immediately before the fuel injection, the timing of opening the intake valve 4 comes close to the compression top dead center, indicated by C in FIG. 6 A large range of braking force will be obtained.

従って、上記形態例によれば、複雑な可変バルブ機構を要することなく既存のエンジン及び動弁系をそのまま利用して高負荷運転領域のみでエンジンの最大筒内圧力を確実に抑制することができるので、エンジンを高圧縮比化して熱効率を上げることによる燃費の改善を設備コストの大幅な高騰を回避しつつ実現することができ、また、制動時に圧縮圧開放型エンジンブレーキとしても活用することができて、制動時におけるエンジンブレーキの増強効果を得ることができ、しかも、そのエンジンブレーキを増強する効果を最大限に得ることができる。   Therefore, according to the above embodiment, it is possible to reliably suppress the maximum in-cylinder pressure of the engine only in the high load operation region by using the existing engine and valve system as it is without requiring a complicated variable valve mechanism. Therefore, the fuel efficiency can be improved by increasing the compression ratio of the engine to increase the thermal efficiency while avoiding a sharp rise in the facility cost, and also it can be used as a compression pressure release engine brake at the time of braking. Thus, it is possible to obtain the enhancement effect of the engine brake at the time of braking, and also obtain the maximum effect of enhancing the engine brake.

尚、本発明の筒内圧力抑制装置は、上述の形態例にのみ限定されるものではなく、必ずしも制動時に圧縮圧開放型エンジンブレーキとしても活用できるようにしなくても良いこと、その他、本発明の要旨を逸脱しない範囲内において種々変更を加え得ることは勿論である。   The in-cylinder pressure suppression device of the present invention is not limited to the above-described embodiment, and may not necessarily be utilized as a compression pressure release engine brake at the time of braking. It goes without saying that various modifications can be made without departing from the scope of the invention.

１ 気筒
４ 吸気弁
６ カムシャフト
７ｘ 専用カム
１２ マスターピストン
１３ 油通路
１４ スレーブピストン
１６ ソレノイドバルブ（作動油供給手段）
１７ コントロールバルブ（作動油供給手段）
１９ 制御装置 1 cylinder 4 intake valve 6 camshaft 7x dedicated cam 12 master piston 13 oil passage 14 slave piston 16 solenoid valve (hydraulic oil supply means)
17 Control valve (hydraulic oil supply means)
19 Controller

Claims (3)

動弁系のカムシャフトに対し各気筒毎に割り当てて増設された専用カムと、該専用カムの夫々が対応する気筒における吸気弁の閉から燃料噴射の開始までの間に前記専用カムにより作動するマスターピストンと、該マスターピストンに対し油通路を介して接続され且つ該油通路に前記マスターピストンの作動により油圧が発生した際に当該気筒の吸気弁を開作動するスレーブピストンと、前記油通路の夫々における油圧の保持・開放を切り替える作動油供給手段と、少なくとも高負荷運転領域でのエンジン駆動時に前記各油通路の油圧を前記作動油供給手段により保持せしめる制御装置とを備えたことを特徴とする筒内圧力抑制装置。   A dedicated cam assigned to each cylinder for the camshaft of the valve system and the dedicated cam operate by the dedicated cam from the closing of the intake valve in the corresponding cylinder to the start of the fuel injection A master piston, a slave piston connected to the master piston via an oil passage, which opens the intake valve of the cylinder when an oil pressure is generated in the oil passage by the operation of the master piston; A hydraulic oil supply means for switching between holding and releasing of the hydraulic pressure in each case, and a control device for holding the hydraulic pressure of each oil passage by the hydraulic oil supply means at least when the engine is operated in the high load operation region. In-cylinder pressure control device. 燃料噴射が実施されない制動時にも油通路の油圧を作動油供給手段により保持せしめ得るように制御装置を構成したことを特徴とする請求項１に記載の筒内圧力抑制装置。   2. The in-cylinder pressure suppression device according to claim 1, wherein the control device is configured such that the hydraulic pressure of the oil passage can be held by the hydraulic fluid supply means even during braking when fuel injection is not performed. 専用カムによりマスターピストンを作動させるタイミングを圧縮上死点に近づくよう燃料噴射の開始直前に設定したことを特徴とする請求項２に記載の筒内圧力抑制装置。   3. The in-cylinder pressure suppression device according to claim 2, wherein the timing to operate the master piston by the dedicated cam is set immediately before the start of the fuel injection so as to approach the compression top dead center.
JP2017174478A 2017-09-12 2017-09-12 In-cylinder pressure suppression device Withdrawn JP2019049239A (en)

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