JP2007146704A - Indirect injection engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an indirect injection engine with improved thermal efficiency in a wide operating range. <P>SOLUTION: The indirect injection engine comprises: a main combustion chamber 30 formed in a cylinder in which a piston 32 is reciprocated; an auxiliary combustion chamber 40 adjacent to the main combustion chamber 30; a blowout port 43 connecting between the main combustion chamber 30 and the auxiliary combustion chamber 40; an auxiliary combustion chamber ignition means 42 igniting air-fuel mixture supplied in the auxiliary combustion chamber; a squish current generation means 35 generating squish current in the main combustion chamber 30; a squish flow adjustment means adjusting the strength of the squish current depending on operational statuses; an operational status detection means detecting the operational status; and a combustion control means controlling the ignition timing of the auxiliary combustion chamber ignition means 42 depending on operational statuses so as to control the timing of the blowout of the torch flame from the blowout port 43 into the main combustion chamber 30, and controlling the strength of the squish current so as to control the torch flame travel. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a sub-chamber engine.

  In order to improve the fuel efficiency, it is effective to make the air-fuel ratio of the air-fuel mixture lean and perform lean combustion. However, if the air-fuel ratio of the air-fuel mixture is lean and burned, the combustibility may become unstable. Therefore, it is necessary to assist combustion by generating a gas flow in the combustion chamber to improve the combustion speed. In view of this, a sub-chamber engine has been proposed in which a sub-chamber adjacent to the main combustion chamber is provided, and an air-fuel mixture is ignited inside the combustion chamber and a combustion flame is ejected from a nozzle hole communicating between the main combustion chamber and the sub-chamber. Yes. The combustion flame generated at this time is ejected into the main combustion chamber in a torch shape while generating severe turbulence, and the combustion of the air-fuel mixture in the main combustion chamber can be completed rapidly.

However, in the sub-chamber engine as described above, the torch flame has a very high ejection speed, so the combustion flame quickly reaches the wall of the main combustion chamber or the crown of the piston, which increases the cooling loss. On the contrary, there is a possibility that the fuel consumption may be deteriorated. In view of this, a sub-chamber engine has been proposed in which an air-fuel mixture is burned near the center of the combustion chamber by generating a squish flow toward the center in the main combustion chamber (see Patent Document 1).
JP-A-56-115815

  However, in the above-described conventional sub-chamber engine, it is impossible to control the strength of the squish flow and the ejection timing of the torch flame according to the operating state. Therefore, even if the operation state is low load, the diffusion of the torch flame is suppressed by the squish flow toward the center of the main combustion chamber, and the combustibility when the load is low is deteriorated.

  The present invention has been made paying attention to such conventional problems, and by controlling the direction and intensity of the squish flow according to the operating state, and further, the ejection timing of the torch flame, the cooling loss can be reduced. Another object of the present invention is to provide a sub-chamber engine that realizes expansion of a lean combustion region and improves the thermal efficiency of the engine in a wide operation region.

  The present invention solves the above problems by the following means. In addition, in order to make an understanding easy, although the code | symbol corresponding to embodiment of this invention is attached | subjected, it is not limited to this.

  The present invention includes a main combustion chamber (30) formed in a cylinder in which a piston (32) reciprocates, a sub chamber (40) provided adjacent to the main combustion chamber (30), and the main combustion chamber. (30) and a sub-chamber (40) communicating with a nozzle hole (43), a sub-chamber ignition means (42) for igniting an air-fuel mixture supplied into the sub-chamber, and the main combustion chamber (30 ) A squish flow generating means (35) for generating a squish flow, a squish flow adjusting means (step S20) for adjusting the strength of the squish flow according to the operating condition, and an operating condition detecting means for detecting the operating condition. (Step S10) and a torch-like flame is ejected from the nozzle hole (43) to the main combustion chamber (30) by controlling the ignition timing by the sub chamber ignition means (42) according to the operating state. Control the timing Together, combustion control means for controlling the reach of the torch flame by controlling the strength of the squish flow; characterized by comprising a (70 step S50).

  According to the present invention, it is possible to adjust the reach distance of the torch flame by controlling the ignition timing according to the operating state and adjusting the direction and intensity of the squish flow. With this control, for example, when the operating state is a high load, flame growth is suppressed by blowing out a torch flame while a squish flow toward the center of the combustion chamber (positive squish) is generated. Cooling loss can be reduced. On the contrary, in the case of a low load, the combustion speed can be improved by jetting the torch flame while the squish flow (reverse squish) toward the outer periphery is generated, and the combustion of the lean air-fuel mixture can be stabilized. Therefore, the thermal efficiency of the engine can be improved in a wide operation region.

Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings.
(First embodiment)
FIG. 1 is a diagram showing a first embodiment of a sub-chamber engine according to the present invention.

  The engine 10 includes an intake port 56 that introduces outside air, a main combustion chamber 30 that combusts the air-fuel mixture therein and transmits the combustion pressure to the piston 32 that slides in the cylinder 31a, and an exhaust port 62 that discharges combustion exhaust. With.

  The intake port 56 includes a fuel injection valve 41. The fuel injection valve 41 is connected to a fuel injection pump (not shown). The fuel injection valve 41 injects fuel in the form of a mist and mixes it with outside air to generate an air-fuel mixture, which is supplied to the main combustion chamber 30.

  An intake valve 55 is provided between the main combustion chamber 30 and the intake port 56. The intake valve 55 adjusts the intake air amount by opening and closing between the intake port 56 and the main combustion chamber 30. The intake valve 55 is applied with a variable valve timing control mechanism capable of controlling the opening / closing timing.

  The main combustion chamber 30 is formed by being divided into a cylinder head 50, a cylinder 31a, and a piston 32. In addition, the engine 10 is provided with a sub chamber 40 adjacent to the main combustion chamber 30 in the cylinder head 50. The sub chamber 40 has a substantially cylindrical shape smaller than the main combustion chamber 30. A nozzle hole 43 communicating with the main combustion chamber 30 is formed in the sub chamber 40. The sub chamber 40 exchanges gas with the air-fuel mixture supplied to the main combustion chamber 30 through the nozzle holes 43 and takes in the air-fuel mixture. The sub chamber 40 is provided with a spark plug 42 that ignites the taken air-fuel mixture. When the combustion pressure in the auxiliary chamber becomes higher than that of the main combustion chamber 30 due to the combustion flame generated by igniting the air-fuel mixture, the combustion flame is ejected from the nozzle hole 43 in a torch shape. This torch flame ignites the air-fuel mixture in the main combustion chamber.

  An exhaust valve 61 is provided between the main combustion chamber 30 and the exhaust port 62. The exhaust valve 61 opens and closes between the exhaust port 62 and the main combustion chamber 30 to discharge exhaust gas.

  The engine 10 is a multi-link variable compression ratio engine. The engine 10 connects the piston 32 and the crankshaft 33 by two links (upper link 11 and lower link 12), and controls the posture of the lower link 12 by the control link 13 to control the top dead center (TDC) of the piston 32. ) Position can be changed, and the engine compression ratio can be changed.

  The upper link 11 has an upper end connected to the piston 32 via the piston pin 21 and a lower end connected to one end of the lower link 12 via the connection pin 22. The piston 32 receives the combustion pressure and reciprocates in the cylinder 31 a of the cylinder block 31.

  One end of the lower link 12 is connected to the upper link 11 via a connecting pin 22, and the other end is connected to the control link 13 via a connecting pin 23. Further, the lower link 12 is inserted into the substantially central connecting hole with the crankpin 33b of the crankshaft 33, and rotates around the crankpin 33b. The lower link 12 is configured to be split into two left and right members. The crankshaft 33 includes a plurality of journals 33a and a crankpin 33b. The journal 33 a is rotatably supported by the cylinder block 31 and the ladder frame 34. The crank pin 33b is eccentric by a predetermined amount from the journal 33a, and the lower link 12 is rotatably connected thereto.

  The control link 13 has a connecting pin 23 inserted at the tip thereof and is connected to the lower link 12 so as to be rotatable. The other end of the control link 13 is connected to the control shaft 25 via an eccentric connecting pin 24. The control link 13 swings about the eccentric connecting pin 24. Further, a gear is formed on the control shaft 25, and the gear meshes with a pinion 53 provided on the rotating shaft 52 of the actuator 51. The control shaft 25 is rotated by the actuator 51, and the eccentric connecting pin 24 moves.

  Control of these mechanisms is performed by the controller 70 in accordance with the operating state. The controller 70 includes a microcomputer having a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), and an input / output interface (I / O interface).

  The controller 70 controls the actuator 51 to rotate the control shaft 25 to change the top dead center position of the piston 32. The controller 70 controls the fuel injection amount and injection timing of the fuel injection valve 41 provided in the intake port 56. Further, the controller 70 controls the ignition timing of the ignition plug 42 provided in the sub chamber 40. Further, the controller 70 adjusts the intake air amount by controlling the opening / closing timing of the intake valve 55 by the variable valve timing control mechanism. The controller 70 controls the reach distance of the torch flame ejected from the sub chamber 40 by performing these controls.

  FIG. 2 is a diagram illustrating a mechanism for generating a squish flow. 2A shows a compression stroke, and FIG. 2B shows an expansion stroke.

  The roof surface 30a of the main combustion chamber 30 is formed such that the gap with the piston crown surface 32a is narrowed at the outer peripheral portion (region R) when the piston 32 approaches top dead center. The squish flow is generated by utilizing the relative movement between the cylinder head 50 and the piston 32 due to the reciprocating motion of the piston 32. When the piston 32 rises, in the region R, the gap between the piston crown surface 32a and the cylinder head 50 is narrowed, and the air-fuel mixture is pushed out therefrom to generate a gas flow (FIG. 2 (A)). The gas flow generated at this time flows from the outer peripheral portion of the main combustion chamber 30 toward the central portion, which is called a normal squish. On the other hand, when the piston 32 descends, the air-fuel mixture is sucked toward the region R (FIG. 2B). The gas flow generated at this time flows from the center of the main combustion chamber 30 toward the outer periphery, which is called reverse squish.

  FIG. 3 is a view for explaining a mechanism for changing the top dead center position of the piston 32 of the sub-chamber engine 10 in the present embodiment.

  By rotating the control shaft 25 and changing the position of the eccentric connecting pin 24, the top dead center position of the piston 32 is changed. For example, as shown in FIGS. 3A and 3C, when the eccentric connecting pin 24 is set to the position A, the top dead center position of the piston 32 rises, and the roof surface 30a of the main combustion chamber 30 and the piston crown surface The distance from 32a (region R in FIG. 2; clearance) becomes small.

  On the other hand, as shown in FIGS. 3B and 3C, when the eccentric connecting pin 24 is set to the position B, the control link 13 is pushed upward, and the position of the connecting pin 23 is raised. As a result, the lower link 12 rotates counterclockwise about the crank pin 33b, the connecting pin 22 is lowered, and the position of the piston 32 at the piston top dead center is lowered. Accordingly, the gap between the roof surface 30a of the main combustion chamber 30 and the piston crown surface 32a is increased.

  In generating the squish flow, the smaller the clearance, the greater the force that pushes and pulls air back. Therefore, the strength of the squish flow can be controlled by changing the top dead center position of the piston 32 and adjusting the clearance.

  FIG. 4 is a flowchart of the control logic executed by the controller 70 according to the present invention.

  In step S10, an operating state is acquired based on information detected by various sensors. Specifically, the current operating state is determined based on the accelerator opening, the engine speed, and the like.

  In step S20, the top dead center position of the piston 32 is set according to the operating state acquired in step S10. By setting the top dead center position of the piston 32 as described above, the strength of the squish flow can be adjusted. Further, the compression ratio in the main combustion chamber can be controlled.

  In step S30, the opening / closing timing of the intake valve 55 is set. Specifically, the timing at which the intake valve 55 is closed when the operating state is high load and high rotation is retarded. By doing so, the amount of air taken into the combustion chamber can be increased, and the effective compression ratio in the combustion chamber can be reduced. When the combustion chamber is made to have a high compression ratio in a high-load and high-speed operation state, knocking is likely to be induced, but the occurrence of knocking can be suppressed by such control.

  In step S40, a fuel injection amount is set. In an operation state with a relatively low load, the ratio of the fuel contained in the air-fuel mixture is kept low to realize lean combustion, thereby improving fuel efficiency and reducing harmful substances contained in the exhaust gas.

  In step S50, the ignition timing of the air-fuel mixture is set. By controlling the ignition timing of the mixture, the ejection timing of the torch flame is controlled. The ejection timing of the torch flame is also affected by the equivalence ratio of the air-fuel mixture (ratio of the stoichiometric air-fuel ratio to the actual air-fuel ratio) and the compression ratio of the main combustion chamber 30. Therefore, the controller 70 sets the ignition timing in consideration of these pieces of information.

  FIG. 5 is a diagram for explaining control of the squish flow in the relationship between the engine load and the rotational speed. The strength of the squish flow is controlled by adjusting the top dead center position of the piston 32 as described above. In this embodiment, the top dead center position of the piston 32 is set in step S20, and the strength of the squish flow is controlled.

  The squish flow is a gas flow generated in the combustion chamber by the relative movement of the piston 32 and the cylinder head as described above. The squish flow is strengthened as the piston 32 moves at high speed. Further, when the top dead center position of the piston 32 is raised, the distance between the roof surface 30a of the main combustion chamber 30 and the piston crown surface 32a is reduced, so that the amount of air pushed out by the movement of the piston 32 increases and the squish flow is increased. Will be strengthened.

  In this embodiment, the squish flow is strengthened as the load decreases. When the operation state is a low load, the fuel injection amount is reduced and lean combustion is performed. Therefore, it is necessary to enhance gas flow in order to ensure stable combustibility. Therefore, when the operating state is a low load, control is performed such that the top dead center position of the piston 32 is raised to reduce the clearance.

  On the other hand, when the operating state is a high load, the combustion chamber is at a high temperature and the compression ratio is increased, so that knocking is likely to occur. Therefore, by retarding the timing at which the intake valve 55 closes from the bottom dead center, the intake air amount is reduced and the substantial compression ratio is lowered (step S30). When the operating state is a high load and the rotation speed is relatively low, the top dead center position of the piston 32 is set low to suppress the squish flow.

  FIG. 6 is a diagram illustrating the relationship between the engine load and the equivalence ratio of the air-fuel mixture. The controller 70 controls the fuel injection amount using this relationship (step S40). The horizontal axis indicates the engine load, and the vertical axis indicates the equivalence ratio φ. As described above, the equivalent ratio φ represents the ratio between the theoretical air-fuel ratio and the actual air-fuel ratio. Accordingly, the air-fuel mixture becomes the stoichiometric air-fuel ratio when the equivalence ratio φ = 1.

  As shown in FIG. 6, the equivalence ratio φ is set to 1 in the high load region. This is because in a high-load and high-rotation region, sufficient engine output cannot be ensured by lean combustion. While the equivalence ratio φ is set to 1 or less, supercharging may be performed to compensate for the shortage of engine output.

  FIG. 7 shows a period from when the sub-chamber is ignited for each operation state to when the torch flame is ejected into the main combustion chamber 30. FIG. 7A shows a case where the driving state is low load high rotation, FIG. 7B shows low load low rotation, FIG. 7C shows high load high rotation, and FIG. 7D shows high load low rotation. . The horizontal axis indicates the crank angle, and the left side of the top dead center (TDC) is the compression stroke, and the right side is the expansion stroke.

  In the present embodiment, the timing for ejecting the torch flame is controlled by controlling the timing for igniting the air-fuel mixture according to the operating state (step S50). The torch flame is ejected from the nozzle hole 43 when the combustion flame ignited in the sub chamber propagates through the sub chamber 40 and the pressure in the sub chamber exceeds the pressure in the main combustion chamber. Therefore, under the influence of the air-fuel ratio and the pressure in the combustion chamber, the time from when the sub chamber 40 ignites until the torch flame is ejected into the main combustion chamber 30 changes.

  Specifically, when the operating state is a low load, since the air-fuel mixture is lean, the combustion pressure in the sub chamber decreases. For this reason, in the compression stroke, the torch flame is not ejected and is ejected after the expansion stroke in which the pressure in the main combustion chamber is reduced (FIG. 7B). Furthermore, when the load is low and the rotation speed is high, the pressure in the main combustion chamber increases, and the pressure difference from the sub chamber increases. Therefore, more time is required from the ignition of the air-fuel mixture to the ejection of the torch flame. Therefore, in order to advance the ejection timing of the torch flame, the ignition timing is advanced to adjust the ejection timing of the torch flame (FIG. 7A).

  On the other hand, in the case of high load and high rotation, a high engine output is required, so the ignition timing is advanced so that the injection timing of the torch flame reaches the end of the compression stroke (FIG. 7C). By doing so, the combustion pressure can be transmitted to the piston 32 to the maximum extent. On the other hand, control is performed so that the ignition timing is retarded and the torch flame is ejected in the expansion stroke in the case of low rotation even at high load (FIG. 7D).

  FIG. 8 is a table summarizing the combustion control in this embodiment.

  In the present embodiment, when the operation state is low load or low rotation, the reverse squish that is the gas flow toward the outer peripheral side of the main combustion chamber 30 is generated by ejecting the torch flame in the expansion stroke. Burn. Further, when the operating state is a low load, since the air-fuel mixture is lean as described above, the ejection speed of the torch flame decreases. Therefore, when the operating state is a low load, the squish flow generated to supplement the combustion speed is strengthened. As described above, the strength of the squish flow can be adjusted by controlling the top dead center position of the piston 32. By doing so, the combustion flame can be rapidly grown and the combustibility can be improved.

  On the other hand, when the operating state is high load and high rotation, the maximum combustion pressure is transmitted to the piston 32, so that the torch flame is ejected immediately before the piston 32 reaches top dead center in the compression stroke. . At this time, in the main combustion chamber 30, a positive squish that is a gas flow flowing in the central direction is generated. In the normal squish, the gas flow is generated in a direction that hinders the growth of the combustion flame. Therefore, the torch flame can be prevented from reaching the piston crown surface 32a and the side surface of the main combustion chamber 30, and the cooling loss can be reduced.

  As described above, the top dead center position of the piston 32 is adjusted according to the required load and the rotational speed of the engine 10. In this embodiment, as shown in FIG. 8, the squish flow is strengthened as the load is lower or the rotational speed is higher. In addition, when the operating state is a low load, the fuel injection amount is reduced and combustion is performed in a lean air-fuel mixture state, so the combustion speed is more likely to decrease. Therefore, in this embodiment, the adjustment amount of the top dead center position of the piston 32 is controlled so that the influence of the required load becomes larger than the rotational speed of the engine. Therefore, the squish flow is enhanced in the case of low load and low rotation than in the case of high load and high rotation.

  According to this embodiment, when the required load of the engine is low, the squish flow can be strengthened by raising the top dead center position of the piston and the combustibility can be stabilized. At this time, since the compression ratio in the combustion chamber is also increased at the same time, the lean mixture limit is improved, and the mixture can be diluted while stabilizing the combustibility. On the other hand, when the required load is high, by suppressing the growth of the torch flame, it is possible to reduce the cooling loss and improve the fuel consumption.

  Further, the ejection speed of the torch flame is proportional to the amount of fuel supplied and does not depend on the rotational speed of the engine. However, since the squish flow is strengthened according to the rotational speed of the engine, the combustion speed increases accordingly. Therefore, when the operating state is high load and high rotation, the torch flame may reach the piston crown surface 32a or the side surface of the main combustion chamber 30 to cause a cooling loss. Therefore, by controlling the torch flame to be ejected in the compression stroke immediately before reaching the top dead center, the combustion flame grows while the normal squish is generated in the main combustion chamber, and the reach distance of the torch flame And cooling loss can be reduced.

  Furthermore, by retarding the timing of closing the intake valve and increasing the intake air amount, the compression ratio in the main combustion chamber can be lowered and the occurrence of knocking can be suppressed.

(Second Embodiment)
FIG. 9 is a view showing a second embodiment of the present invention, and shows the shape of the squish generating part formed on the piston crown surface 32a. 9A is a cross-sectional view, and FIG. 9B is a cross-sectional view taken along line BB in FIG. 9A.

  In the following embodiments, the same reference numerals are given to the portions that perform the same functions as those of the above-described embodiments, and overlapping descriptions are omitted as appropriate.

  In the present embodiment, the squish generator 35 is formed on the piston crown surface 32a to assist the generation of the squish flow. To do. Other configurations, control of the fuel injection amount, and the ignition timing of the air-fuel mixture are the same as in the first embodiment.

  As shown in FIG. 9A, the squish generating portion 35 raises the outer peripheral portion of the piston crown surface 32a, and the gap between the main combustion chamber 30 and the roof surface 30a is small when the piston 32 approaches top dead center. It forms so that it may become. By doing so, a squish flow can be generated in the combustion chamber as in the first embodiment. In addition, since the squish generating part 35 forms a surface facing the roof surface 30a of the main combustion chamber 30 in parallel with the roof surface 30a, the gap can be further reduced, so that the squish flow can be generated more efficiently. . This gap is called a squish area.

  In the present embodiment, six injection holes 43 are formed at equal intervals on the side wall surface of the sub chamber 40. Furthermore, the squish generating part 35 is formed so that the inside becomes a substantially regular hexagon. At this time, as shown in FIG. 9B, the distance from the nozzle hole 43 through which the torch flame is ejected to the squish generator 35 is formed to be the shortest. Therefore, the torch flame injected from the injection hole 43 is injected toward the midpoint of each side of the hexagon formed on the inner peripheral side of the squish generator 35.

  According to this embodiment, the squish area in the growth direction of the torch flame is expanded. Therefore, the squish flow is locally strengthened in a direction that inhibits the growth of the torch flame. Therefore, it is possible to prevent the jetted torch flame from reaching the piston crown surface 32a or the side surface of the main combustion chamber 30 and reduce the cooling loss.

(Third embodiment)
FIG. 10 is a view showing a second embodiment of the present invention, and shows the shape of the squish area formed on the piston crown surface 32a. 10A is a cross-sectional view, and FIG. 10B is a cross-sectional view taken along line BB in FIG. 10A.

  As shown in FIG. 10A, in this embodiment as well, the squish generating portion 35 is formed by raising the outer peripheral portion of the piston crown surface 32a as in the second embodiment. In the present embodiment, as shown in FIG. 10B, the distance from the nozzle hole 43 in the ejection direction of the torch flame to the squish area is the shortest. Also in this embodiment, six nozzle holes 43 are formed at equal intervals on the side wall surface of the sub chamber 40 as in the second embodiment. Correspondingly, the inner peripheral surface of the squish generator 35 is substantially a regular hexagon. Formed to be. In the present embodiment, the hexagonal apex is formed so as to be positioned in the direction in which the torch flame is ejected, so that the squish generating portion 35 is rotated by 30 ° compared to the second embodiment.

  According to the present embodiment, the distance from the nozzle hole 43 to the squish generator 35 is the longest. Therefore, not only the suppression of the growth of the torch flame by the squish flow, but also the cooling loss can be reduced by ensuring a long distance to the side surface of the main combustion chamber 30 physically.

(Fourth embodiment)
FIG. 11 is a view showing a fourth embodiment of the present invention and showing the shape of the squish area formed on the piston crown surface 32a. 11A is a cross-sectional view, and FIG. 11B is a cross-sectional view taken along line BB in FIG. 11A.

  As shown in FIG. 11A, in the present embodiment, the piston crown surface 32a inside the squish generating portion 35 is formed so that the depth becomes deeper toward the outer periphery. At this time, the inclination angle from the center of the piston crown surface 32a toward the outer periphery is made substantially equal to the ejection angle of the torch flame, that is, the angle at which the injection hole 43 is formed.

  According to the present embodiment, the piston crown surface 32a is formed in the inner peripheral portion of the squish generating portion 35 in parallel with the ejection direction of the torch flame, so that it becomes difficult to contact and the cooling loss can be reduced.

  The present invention is not limited to the embodiment described above, and various modifications and changes can be made within the scope of the technical idea, and it is obvious that these are equivalent to the present invention.

  For example, in addition to adopting the multi-link variable compression ratio engine as in this embodiment as means for changing the top dead center position of the piston, a hydraulic device is incorporated in the piston itself to adjust the height of the piston crown surface. The same effect can be obtained by using a mechanism or a mechanism for adjusting the distance between the cylinder head and the cylinder block.

  In addition, it is equipped with a sensor that measures the temperature of the cooling water for the engine, and when the temperature of the cooling water is low, such as at the time of start-up, the gas flow is strengthened regardless of the operating state, thereby improving the combustibility and the main combustion. The wall temperature of the room can be raised.

  Furthermore, this embodiment is a single mixture type in which a mixture of the same air-fuel ratio is supplied to the main combustion chamber and the sub chamber, but a double mixture type that supplies a relatively rich mixture in the sub chamber is adopted. May be.

1 is a diagram showing a first embodiment of a sub-chamber engine according to the present invention. It is a figure explaining the process in which a torch flame spouts from the production | generation of a squish flow, and a sub chamber. It is a figure explaining the mechanism which changes the position of the top dead center of a piston. 3 is a flowchart of control logic according to the present invention. It is a figure which shows the area | region which performs increase and reduction of a squish flow in the relationship between an engine load and an engine speed. It is a figure which shows the relationship between an engine load and the equivalence ratio of air-fuel | gaseous mixture. It is a figure which shows the relationship between the ignition timing to the air-fuel | gaseous mixture in a subchamber, and the ejection timing of the torch flame to a main combustion chamber. It is a list of control by the operating state in the present invention. It is a figure explaining the shape of the squish production | generation part of 2nd Embodiment of this invention. It is a figure explaining the shape of the squish production | generation part of 3rd Embodiment of this invention. It is a figure explaining the shape of the squish production | generation part of 4th Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Engine 30 Main combustion chamber 30a Roof surface 31 Cylinder block 31a Cylinder 32 Piston 32a Piston crown surface 35 Squish production | generation part (squish flow production | generation means)
40 Sub chamber 41 Fuel injection valve 42 Spark plug 43 Injection hole 50 Cylinder head 55 Intake valve 56 Intake port 70 Controller (combustion control means)
Step S10 Operating state detection means Step S20 Squish flow adjustment means Step S30 Compression ratio reduction means Step S50 Combustion control means

Claims (14)

A main combustion chamber formed in a cylinder in which a piston reciprocates;
A sub chamber provided adjacent to the main combustion chamber;
A nozzle hole communicating between the main combustion chamber and the sub chamber;
Sub chamber ignition means for igniting the air-fuel mixture supplied into the sub chamber;
Squish flow generating means for generating a squish flow in the main combustion chamber;
Squish flow adjusting means for adjusting the strength of the squish flow;
Driving state detecting means for detecting the driving state;
In accordance with the operation state, the timing of the torch-like flame is ejected from the nozzle hole to the main combustion chamber by controlling the ignition timing by the sub chamber ignition means, and the strength of the squish flow is controlled. Combustion control means for controlling the reach of the torch flame by
A sub-chamber engine characterized by comprising: The combustion control means ignites the piston so that the torch flame is ejected after the piston passes through the top dead center when the operation state is a low load, and further, the squish is greater than when the operation state is a high load. Increasing the reach of the torch flame by strengthening the flow,
The sub-chamber engine according to claim 1. The combustion control means ignites the piston so that the torch flame is ejected after the piston passes through the top dead center when the operation state is low rotation, and further, the squish is more effective than when the operation state is high rotation. Shortening the reach of the torch flame by weakening the flow,
The sub-chamber engine according to claim 1 or 2, wherein the sub-chamber engine is provided. The combustion control means causes the torch flame to be ejected before the piston passes through the top dead center when the operation state is high load and high rotation, and further than when the operation state is high load and low rotation. To shorten the reach of the torch flame by strengthening the squish flow,
The sub-chamber engine according to any one of claims 1 to 3, wherein the sub-chamber engine is provided. The squish flow adjusting means is a clearance adjusting means for adjusting a clearance between a roof surface of the main combustion chamber and a piston crown surface,
The clearance adjusting means weakens the squish flow by increasing the clearance, and strengthens the squish flow by reducing the clearance.
The sub-chamber engine according to any one of claims 1 to 4, wherein the engine is a sub-chamber engine. The clearance adjusting means is a variable compression ratio mechanism that changes a piston top dead center position.
The sub-chamber engine according to claim 5. The squish flow generating means is a squish area composed of a squish generating portion formed on the roof surface of the main combustion chamber and the outer periphery of the piston crown surface.
The sub-chamber engine according to any one of claims 1 to 6, wherein the engine is a sub-chamber engine. The squish generator is formed to have a maximum width in the growth direction of the torch flame.
The sub-chamber engine according to claim 7. The squish generating part is formed to have a minimum width in the growth direction of the torch flame.
The sub-chamber engine according to claim 7. The piston crown surface is formed in a conical shape in which the inside of the squish generating portion protrudes toward the roof surface of the main combustion chamber.
The sub-chamber engine according to any one of claims 7 to 9, wherein the sub-chamber engine is provided. The combustion control means further includes an effective compression ratio reducing means for reducing an effective compression ratio inside the main combustion chamber,
The effective compression ratio lowering means lowers the effective compression ratio in the main combustion chamber when the operating state is high load and high rotation.
The sub-chamber engine according to any one of claims 1 to 10, wherein the engine is a sub-chamber engine. The compression ratio lowering means is a valve timing adjusting means.
The sub-chamber engine according to claim 11. The compression ratio lowering means lowers the effective compression ratio by adjusting the closing timing of the intake valve to the retard side.
The sub-chamber engine according to claim 12, wherein The operating state detection means further comprises cooling water temperature detection means,
The combustion control means strengthens the squish flow regardless of the engine load and rotation speed when the temperature of the cooling water detected by the cooling water temperature detection means is lower than a predetermined temperature.
The sub-chamber engine according to any one of claims 1 to 13, wherein the engine is a sub-chamber engine.