JPH0756209B2 - Multi-cylinder engine intake system - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake system for a multi-cylinder engine, and more particularly to an intake system for an engine configured to increase an intake charge amount by utilizing a resonance effect of an intake system.

(Prior Art) The engine is provided with a blow-by gas treatment device that causes the blow-by gas leaking from the combustion chamber to the crank chamber to burn again in the combustion chamber together with the air-fuel mixture. This device connects the crank chamber and the downstream side of the throttle valve in the intake passage to the PCV.
A blow-by gas recirculation passage communicating through a valve (blow-by gas flow rate adjusting valve) and a fresh air introduction passage communicating between the crank chamber and the upstream side of the throttle valve in the intake passage, and the throttle valve in the intake passage Due to the pressure difference between the upper side and the lower side, the air on the upstream side of the valve is introduced into the crank chamber through the fresh air introduction passage for scavenging, and the blow-by gas in the crank chamber is throttled through the blow-by gas recirculation passage. It sucks out to the downstream side of the valve. However, in an engine equipped with this device, the throttle valve is almost fully opened at the time of high load and above the valve in the intake passage,
When the pressure difference on the downstream side becomes smaller and the pressure in the crank chamber rises, blow-by gas in the crank chamber may flow backward through the fresh air introduction passage and flow into the intake valve upstream of the throttle valve. Further, such a reverse flow of blow-by gas is generated in the blow-by gas recirculation passage or when the engine or intake air is in an extremely low temperature state.
Freezing in the PCV valve also occurs when the smooth circulation of blow-by gas through the passage is hindered.

By the way, on the upstream side of the throttle valve in the intake passage, that is, in the vicinity of the opening of the fresh air introduction passage, an idle control passage for finely adjusting the intake flow rate at idling and an assist air for the fuel injection valve are provided. There may be provided an air outlet of a passage for guiding air to various engine control means such as an assist air supply passage for supplying air or an air introduction passage for guiding air to a negative pressure adjusting valve for controlling exhaust gas recirculation. However, in this case, if the blow-by gas flows backward through the fresh air introduction passage and flows into the intake passage as described above, the oil mist contained in the blow-by gas is supplied from the air outlet to the idle control passage and assist air supply. It will flow into the passage or the air introduction passage.
Therefore, the oil mist adheres to the inner wall of these passages or the engine control means such as the idle control valve, the fuel injection valve, or the negative pressure adjusting valve to which these passages are connected, which causes idle control, fuel injection or exhaust gas recirculation. This will reduce the control performance.

On the other hand, for example, Japanese Utility Model Laid-Open No. 59-148425 discloses a multi-cylinder engine configured to improve intake charging efficiency or engine output torque by utilizing the resonance effect of intake air. This type of engine effectively utilizes the resonance of intake air generated in the intake passage to obtain a pushing action of intake air into each cylinder, and a large positive pressure wave of intake air is generated in the intake passage due to the resonance phenomenon. However, as a reaction, a large negative pressure wave will also be generated. Therefore, when the fresh air introduction passage and the idle control passage are closely connected to the intake passage of this type of engine, the backflow of blow-by gas from the fresh air introduction passage becomes remarkable due to the large negative pressure wave. Therefore, a large amount of oil mist flows into the idle control passage and the like.

(Object of the Invention) An air intake device in a fresh air introduction passage communicating with a crankcase in an intake device of a multi-cylinder engine in which intake charging efficiency or output torque is improved by utilizing a resonance effect of intake air. By appropriately disposing the outlet and the air outlet in the idle control passage or the like on the upstream side of the throttle valve in the intake passage, blowby gas in the crank chamber is generated due to a large negative pressure in the intake passage due to the resonance effect. Even when the fresh air introduction passage is back-flowed, the oil mist in the gas is prevented from flowing into the passage for introducing air to the engine control means such as the idle control passage, and thus a good idle control device or the like is provided. The purpose is to ensure performance and durability.

(Structure of the Invention) An intake system for a multi-cylinder engine according to the present invention is characterized in that it has the following structure to achieve the above object.

That is, two intake manifolds are provided corresponding to two cylinder groups whose intake orders are not adjacent to each other, and two divided passages each having a throttle valve are connected upstream of these intake manifolds. In the intake system of a cylinder engine,
A blow-by gas recirculation passage for recirculating blow-by gas is provided in the intake collecting portion, and a fresh air introduction passage for introducing fresh air into the crank chamber is provided upstream of the throttle valve in one of the two divided passages. Let it open,
And on the upstream side of the throttle valve in the other passage,
Various air extraction passages for extracting air from the passage and leading to the engine control means are opened.

By the way, various air extraction passages for introducing air to the engine control means include, for example, an idle control passage bypassing a throttle valve, an assist air supply passage for supplying assist air to a fuel injection valve, or a negative pressure adjusting valve for exhaust gas recirculation control. According to the above configuration, the air introduction passage for guiding air to the intake passage and the openings of the various air extraction passages to the intake passage and the opening of the fresh air introduction passage form the two divided passages. It will be surely shut off by the partition wall.

(Effects of the Invention) As described above, according to the present invention, two intake collecting portions corresponding to two cylinder groups whose intake orders are not adjacent to each other, and two divided passages respectively connected to these intake collecting portions. In an intake system for a multi-cylinder engine in which a resonance effect of intake air is provided, an opening of a fresh air introduction passage communicating with a crank chamber and an idle control passage, an assist air supply passage, or an exhaust gas recirculation control negative The openings of various air extraction passages such as an air introduction passage that guides air to the pressure regulating valve are reliably blocked by the partition wall between the two divided passages. Even if blow-by gas flows into one of the divided passages from the fresh air introduction passage when resonance occurs in the divided passage of the book, the air extraction passage connected to the other divided passage does not The blowby ga The oil mist in the gas stops flowing. This allows
It is possible to prevent the oil mist from adhering to the inner wall of the air extraction passage, the engine control means such as the idle control valve, the fuel injection valve, the negative pressure adjusting valve for exhaust gas recirculation control, etc. provided in the passage, and the idle control device and the fuel injection The performance and durability of the device or the exhaust gas recirculation device will be secured.

(Example) Hereinafter, the Example of this invention is described.

First and second figure shows a first embodiment of the present invention, the engine 1 has six cylinders 2 ₁ to 2 _6, what these cylinders 2 ₁ to 2 ₆ can not adjacent the intake order comrades 2 as the same group
One cylinder group 3 _1, 3 ₂ are grouped into. That is, the intake sequence is, for example, the first cylinder 2 ₁ → the fourth cylinder 2 ₄ → the second cylinder 2 ₂ →
The order of the fifth cylinder 2 ₅ → the third cylinder 2 ₃ → the sixth cylinder 2 ₆ is, in other words, the intake strokes are alternately performed without the cylinders of the _two cylinder groups 3 ₁ and 3 ₂ overlapping. It has become.

On the other hand, an intake device for supplying intake air to the respective cylinders 2 ₁ to 2 ₆ 4
The intake passage 5 ₁ to 5 ₆ independent of each communicating with respective cylinders 2 ₁ to 2 ₆
And the intake air corresponding to the first surge tank 6 ₁ and the second cylinder group 3 ₂ to which the upstream ends of the intake passages 5 _{1 to} 5 ₃ corresponding to the first cylinder group 3 ₁ of these independent intake passages are connected. A second surge tank 62 to which the upstream ends of the passages 5 _{4 to} 5 ₆ are connected, and a second surge tank 6 ₂ provided on the upstream side of both surge tanks 6 ₁ and 6 ₂ and having their upstream ends joined.
1, a second resonance path 7 _1, 7 _2, an air cleaner first, second resonance path 7 _1, 7 ₂ of the merging section is guided from the (not shown) (bifurcation)
Consists of connected with merge path 8, the first, first, second throttle valve 9 _1, 9 ₂ which opens and closes in conjunction with each other in the second resonance path 7 _1, 7 ₂ are provided . Where the first
The surge tank 6 ₁ and the first resonance passage 7 ₁ and the second surge tank 6 ₂ and the second resonance passage 7 ₂ constitute first and second resonance spaces which are independent of each other. It has a constant natural frequency determined by the volume of the surge tank and the length of the resonance passage.

By the way, as shown in FIGS. ₁ and ₂ , blow-by gas is supplied to the engine 1 from the internal space of the head cover 11 communicating with the crank chamber 10 of the engine 1 to the first and second surge tanks 6 ₁ and 6 ₂ , respectively. Two blow-by gas recirculation passages to guide 1
2 ₁ and 12 ₂ are provided, and both surge tanks are provided by PCV valves 13 ₁ and 13 ₂ provided in these passages 12 ₁ and 12 ₂ , respectively.
The flow-back amount of blow-by gas into 6 ₁ , 6 ₂ is adjusted.

A fresh air introduction passage 14 is provided between the intake device 4 and the crank chamber 10 for introducing fresh air into the crank chamber 10 to positively recirculate the blow-by gas. Further, the intake device 4 includes an idle control passage for bypassing the throttle valve and adjusting the intake flow rate during idling.
15 are provided.

However, in this engine 1, the fresh air introduction passage
Air outlet 14a of 14 with is provided upstream portion X of the throttle valve 9 ₁ in _one said first resonance passage 7, a throttle air outlet 15a of the idle control passage 15 is in the second resonance path 7 ₂ It is provided in the upstream portion Y of the valve 9 _2. The flow rate of the air passing through the idle control passage 15, that is, the flow rate of the air bypassing the _first and second throttle valves 9 ₁ and 9 ₂ is adjusted by the control valve provided in the passage 15.
It is supposed to be done by 16.

According to the above configuration, each cylinder is operated when the engine 1 is operating.
Blow-by gas that leaks into the crank chamber 10 from the combustion chamber of 2 ₁ to 2 _6, first through the blow-by gas recirculation passage 12 _1, 12 ₂ from the inner space of the head cover 11, the second surge tank ₆₁ and 62 in ₂ They are respectively returned. At this time, from the upstream portion X of the throttle valve 9 ₁ of the first resonance path 7 _1, fresh air into the crank chamber 10 through the fresh air introduction passage 14 is supplied, scavenging line in this manner the crank chamber 10 Be seen.

By the way, when the engine 1 is under a heavy load, the throttle valves 9 ₁ , 9 ₂ are substantially fully opened, and the first and second resonance passages 7 ₁ ,
7 both valves 9 ₁ in _2, 9 ₂ in the upstream portion X, together with Y is negative pressure state, increased pressure in the crank chamber 10, as a result,
The well fresh air inflow from the upstream portion X of the throttle valve 9 ₁ fresh air introduction passage 14 to the crank chamber 10 is blocked at the first resonance path 7 _1, the blow-by gas in the crank chamber 10 in the opposite A problem such that the passage 14 recirculates and flows into the upstream portion X easily occurs. In addition, such a problem is caused by the blow-by gas recirculation passages 12 ₁ and 12 ₂ or the PCV valves 13 ₁ and 13 ₂ being frozen when the passage 1
The same occurs when the smooth flow of blow-by gas in 2 ₁ , 12 ₂ is obstructed.

On the other hand, the intake air sucked from an air cleaner (not shown) flows from the merging passage 8 on the upstream side of the intake device 4 to the first and second resonance passages.
While being distributed and introduced to 7 ₁ and 7 ₂ , they flow into the _1st and 2nd surge tanks 6 ₁ and 6 ₂ via the _1st and 2nd throttle valves 9 ₁ and 9 ₂ , respectively. Then, the intake air, first to third in the cylinder 2 ₁ to 2 _3, and the second surge constitutes an independent intake passage 5 ₁ to 5 ₃ via the first cylinder group 3 ₁ from the first surge tank 6 ₁ 4 constituting the second cylinder group 3 ₂ through the independent intake passage 5 _{4-5 6} from tank 7 ₂
~ Is distributed and supplied to the sixth cylinder 2 _{4-2 6.} In that case, the first
The three cylinders 2 ₁ to 2 ₃ forming the cylinder group 3 ₁ do not have intake orders adjacent to each other, and the three cylinders 2 ₄ to 2 ₆ forming the second cylinder group 3 ₂
However, since the intake order is not adjacent to each other, in each of the cylinder groups 3 ₁ and 3 ₂ , the pressure wave generated due to the opening and closing of the intake port (not shown) causes the independent intake passages 5 _{1 to} 5 ₃ or 5 ₄ 5 ₆ without cancel each other when they are propagated to the surge tank ₆₁ or 6 ₂ through the number of vibrations corresponding to the engine speed to the first, second surge tank ₆₁ and 62 in ₂ Intake vibration occurs. Then, both surge tanks 6 ₁ and 6 ₂ and the first and _second surge tanks
By the resonance passage 7 _1, 7 ₂ and the natural frequency of the two resonance spaces independent of each other by is formed, the co-sounding space and the said intake vibration resonates at a predetermined rotational range of the engine 1,
The large positive pressure wave generated by this resonance enhances the intake charging efficiency. However, when the resonance phenomenon occurs in the resonance space as described above, the pressure of the intake air in the _first and second resonance passages 7 ₁ and 7 ₂ fluctuates remarkably, and a large negative pressure is periodically generated due to this pressure fluctuation. Will occur. Therefore, the reverse flow of blow-by gas from the crank chamber 10 to the upstream portion X of the throttle valve 9 ₁ in the first resonance passage 7 ₁ via the fresh air introduction passage 14 becomes remarkable. The upstream portion Y oil mist of the throttle valve 9 ₂ in the second resonance path 7 ₂ of the blow-by gas flowing back this way in the first resonance path 7 ₁
If it flows into the idle control passage 15 from the above and adheres to the inner wall of the passage 15 or the control valve 16, it becomes difficult to accurately adjust the flow rate of the air passing through the passage 15, and the idle control performance is impaired. It will be.

However, in this intake device 4, a partition wall 17 that partitions the _first and second resonance passages 7 ₁ and 7 ₂ between the upstream and downstream portions X and Y of the first and second throttle valves 9 ₁ and 9 ₂ is provided. As described above, the air is cut off from the fresh air introduction passage 14 to the first resonance passage as described above.
7 even if a large amount of blow-by gas to ₁ flows, oil mist idle control passage of the blow-by gas and the gas
It will be prevented from flowing into 15. As a result, it is possible to prevent the performance of idle control from being deteriorated and the durability of the control valve 16 from being deteriorated.

Next, a second embodiment shown in FIG. 3 will be described.

In this embodiment, in order to promote atomization of fuel injected from the fuel injection valve 40 provided at the downstream end of each independent intake passage 25 ... 25, assist air is provided around the tip of the valve 40. The present invention relates to an engine 21 configured to supply the air, and an intake device 24 of the engine 21 includes a first resonance passage 27 ₁ connected to a first surge tank 26 ₁ as in the first embodiment,
A first resonance passage 27 ₂ connected to the second surge tank 26 ₂ , and the throttle valve 2 in the first resonance passage 27 ₁
Fresh air introduction passage 34 communicating with the crankcase is opened in the 9 ₁ of the upstream portion X '. Then, the second resonance passage 27 ₂
Throttle valve 29 ₂ of the upstream portion Y ', an air outlet of the assist air supply passage 41 for supplying assist air to the peripheral tip of the fuel injection valve 40 is opened in.

Therefore, also in this embodiment, since the partition wall 37 surely blocks the upstream portions X ', Y'of both throttle valves 29 ₁ , 29 ₂ from each other, when the engine 21 is under high load or cold, Furthermore, when a large negative pressure is generated in the first and second resonance passages 27 ₁ and 27 ₂ due to the resonance phenomenon, blow-by gas and oil mist flow from the fresh air introduction passage 34 into the upstream portion X ′. However, these do not flow into the assist air supply passage 42 from the upstream portion Y ′, so that good fuel injection performance of the fuel injection valve 40 is ensured.

Further, in the third embodiment shown in FIG. 4, the exhaust gas from the exhaust system is passed through the exhaust gas recirculation passage 70 to the first and second surge tanks 5.
6 _1, 56 ₂ relates intake system 54 of the constructed engine 51 to respective reflux, this engine 51, the negative圧応Doshiki actuating the flow regulating valve 71 provided in the exhaust gas recirculation passage 70 An actuator 72 and a negative pressure adjusting valve 74 for adjusting the negative pressure in the negative pressure chamber 72a of the actuator 72 via a negative pressure adjusting passage 73 are provided. Then, the negative pressure adjusting valve 74
A negative pressure introducing passage 75 for guiding a negative pressure from the second surge tank 56 ₂ and a throttle valve 59 ₂ in the second resonance passage 57 ₂ .
Is connected to an air introduction passage 76 for guiding air from the upstream portion Y ″ of the above, and the negative pressure supplied to the actuator 72 is controlled by adjusting the negative pressure and the air introduced from these passages 75, 76. It is like this.

However, also in this embodiment, the throttle valve 59 ₁ in the first resonance passage 57 ₁ in which the fresh air introduction passage 64 is open.
Of the upstream portion X ″ of the above and the air introduction passage 76 are open
Upstream portion Y of the throttle valve 59 ₂ in the resonance passage 57 ₂ "
That is, since the partition wall 67 is surely shut off, the blow-by gas and the oil mist that flow back into the fresh air introduction passage 64 and flow into the upstream portion X ″ are prevented from flowing into the air introduction passage 76. Therefore, good performance of the negative pressure adjusting valve 74 is ensured, and a problem that the flow rate of exhaust gas passing through the exhaust gas recirculation passage 70 is hindered is prevented.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention, and FIG. 1 is a fragmentary plan view showing an engine intake device in the first embodiment.
Fig. 2 is a front view of the engine, and Figs. 3 and 4 are second and third views, respectively.
1 is a schematic view of a main part of an intake device for an engine showing an embodiment. 1,21,51 …… Engine, 3 ₁ , 3 ₂ …… Cylinder group, 4,24,54 ……
Intake device, 5 _{1 to} 5 ₆ , 25 ... Independent intake device, 6 ₁ , 6 ₂ , 26 ₁ ,
26 ₂ , 56 ₁ , 56 ₂ …… Intake air collection part (first and second surge tanks), 7 ₁ , 7 ₂ , 27 ₁ , 27 ₂ , 57 ₁ , 57 ₂ …… Split passages (first, second
Second resonance passage), 9 ₁ , 9 ₂ , 29 ₁ , 29 ₂ , 59 ₁ , 59 ₂ ...... Throttle valve, 10 ...... Crank chamber, 12 ₁ , 12 ₂ ...... Blow-by gas recirculation passage, 14, 34, 64 …… New air introduction passage, 15,41,
76 ... Air extraction passage, 16,40,74 ... Engine control means (control valve, fuel injection valve, negative pressure adjustment valve), X, X ', X "...
Upstream side of one throttle valve, Y, Y ′, Y ″ …… Upstream side of the other throttle valve.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location F02M 69/00 310 A 69/32

Claims (1)

[Claims] 1. A pair of intake manifolds, which are connected to two cylinder groups whose intake orders are not adjacent to each other through independent intake passages,
An intake system for a multi-cylinder engine, which is connected to each of these intake manifolds, merges into one on the upstream side, and has two divided passages each provided with a throttle valve. A blow-by gas recirculation passage for recirculating the blow-by gas is provided, and a fresh air introduction passage for introducing fresh air into the crank chamber is opened on the upstream side of the throttle valve in one of the two divided passages, and the other one. An intake device for a multi-cylinder engine, characterized in that an air extraction passage for extracting air from the passage and leading to the engine control means is opened upstream of the throttle valve in the passage.