JP3629879B2 - Compression ignition internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a compression ignition internal combustion engine that compresses and ignites a premixed gas at high compression.
[0002]
[Prior art]
A premixed compression ignition gasoline engine, which is one of compression ignition type internal combustion engines, has attracted attention as a candidate for an engine that achieves high efficiency and cleanliness at the same time. In a premixed compression ignition gasoline engine, as in a conventional spark ignition gasoline engine, gasoline is injected into the intake port, a complete premixed gas is introduced into the cylinder, and compressed to a high compression ratio comparable to that of a diesel engine. Compression self-ignition is performed without using a stopper.
[0003]
According to the literature ("Automotive Technical Society Preprints 951 1995-5" by the Japan Society of Automotive Engineers), in premixed compression ignition gasoline engines, the premixed gas is stable in a predetermined range (for example, 34 to 44). It is said that compression ignition combustion can be obtained, and low fuel consumption comparable to that of a diesel engine and a low NOx level less than one tenth of that of a diesel engine can be achieved. Further, NOx generation in the cylinder is said to be able to significantly reduce the NOx concentration in the uniform air-fuel mixture than in the stratified intake.
[0004]
However, when the air-fuel ratio is leaner than the predetermined range, ignition failure is likely to occur, and knocking is likely to occur on the rich side, so that there is a problem that the stable combustion operating range is limited to a narrow range.
[0005]
The cause of the ignition failure on the lean side is that the auto-ignition temperature of gasoline is higher than that of light oil. Therefore, it was considered that the intake air temperature could be increased by intake air heating to increase the lean limit of the stable combustion region.However, although the increase of the lean limit was achieved, the rich limit of the stable combustion region moved to the lean side. Knocking easily occurs in the load range, and the stable combustion range has not been expanded. In addition, there is a problem that the output is reduced due to a decrease in volumetric efficiency due to intake air heating.
[0006]
Japanese Patent Application Laid-Open No. 7-332140 discloses a port injection valve for injecting fuel into an intake port and an in-cylinder injection valve for directly injecting fuel into the cylinder. The stable combustion area was expanded by injecting fuel in combination with direct injection.
[0007]
[Problems to be solved by the invention]
In the technique disclosed in the above publication, the operation timing of the in-cylinder injection valve is set to 8 to 30 degrees in the crank angle before compression top dead center (hereinafter, the crank angle is abbreviated as ° CA), and from the in-cylinder injection valve. The fuel injection amount Qd directly injected into the cylinder (hereinafter referred to as the in-cylinder injection amount) Qd is 15 to 25% of the total injection amount at full load. Here, the total injection amount Q is the sum of the fuel injection amount (hereinafter referred to as port injection amount) Qp injected from the port injection valve to the intake port and the in-cylinder injection amount Qd.
[0008]
By the way, the in-cylinder injection amount Qd, which is 15 to 25% of the total injection amount at the full load, corresponds to the injection amount at the no load of the engine, so the port injection amount Qp is small on the light load side, and most of the fuel is used. In-cylinder injection is performed from the in-cylinder injection valve, and as a result, actual combustion becomes similar to stratified combustion by direct injection in-cylinder, which is a major advantage of premixed compression ignition gasoline engines. That is, it becomes difficult to achieve a low NOx level (less than one tenth of a diesel engine).
[0009]
Further, in the technique disclosed in the above publication, the fuel port injection amount Qp at full load is as large as 75 to 85% of the total injection amount, so that knocking is likely to occur once self-ignition occurs.
[0010]
The present invention has been made in view of such problems of the prior art, and the problem to be solved by the present invention is to re-suction exhaust in a cylinder (so-called internal EGR) as the load decreases on the light load side. ) To increase the intake air heating so that ignition failure does not occur, thereby expanding the stable combustion region on the light load side.
[0011]
Another problem to be solved by the present invention is to reduce the amount of in-cylinder injected fuel on the high load side so that knocking does not occur, thereby expanding the stable combustion region on the high load side. .
[0012]
[Means for Solving the Problems]
The present invention employs the following means in order to solve the above problems.
(1) The present invention relates to a cylinder, a piston that reciprocates in the cylinder, a combustion chamber defined by the cylinder and the piston, and an intake valve that opens and closes an intake port for supplying intake air into the cylinder. An exhaust valve for opening and closing an exhaust port for exhausting the gas in the cylinder, and an opening / closing timing varying means for changing the opening / closing timing of only the intake valve or both of the intake valve and the exhaust valve among the intake valve and the exhaust valve And a cylinder injection valve that directly injects fuel into the combustion chamber, and injects fuel only from the port injection valve. The maximum injection amount that does not sometimes cause knocking is set as the reference injection amount, and the corresponding load amount is set as the reference load amount. In the load range below the reference load amount, the required injection amount The opening / closing timing variable means controls so that the entire amount of fuel is injected from the port injection valve during the intake stroke after the top dead center of the piston, and the valve opening polymerization period of the intake valve and the exhaust valve becomes longer as the load decreases. This is a compression ignition internal combustion engine.
[0013]
Since the amount of fuel injected from the port injection valve is equal to or less than the amount of fuel that causes knocking, knocking does not occur even if the port injection fuel self-ignites. The smaller the load is, the longer the opening polymerization period of the intake valve and the exhaust valve is. Therefore, the smaller the load is, the more re-intake of exhaust in the cylinder (so-called internal EGR) is, and the intake air is heated higher. Due to the gas temperature rise in the cylinder before the start of compression, the fuel is surely self-ignited even under a light load.
[0014]
Further, fuel injection from the port injection valve is executed after the top dead center of the piston, that is, it is executed after entering a substantial intake stroke, and the fuel injected into the port is injected into the internal EGR. The gas can be prevented from flowing back through the intake port, and the fuel is reliably sucked into the cylinder and mixed with fresh air to form a uniform premixed gas.
[0015]
The opening / closing timing varying means may vary the opening / closing timing of only the intake valve, or may vary the opening / closing timing of both the intake valve and the exhaust valve. It is sufficient if the valve opening polymerization period can be varied.
[0016]
(2) Further, the present invention opens and closes a cylinder, a piston that reciprocates in the cylinder, a combustion chamber defined by the cylinder and the piston, and an intake port for supplying intake air into the cylinder. An intake valve, an exhaust valve that opens and closes an exhaust port for exhausting gas in the cylinder, a port injection valve that injects fuel into the intake port, and an in-cylinder injection valve that directly injects fuel into the combustion chamber; In the compression ignition type internal combustion engine having the above, the maximum injection amount that does not cause knocking when fuel is injected only from the port injection valve is set as the reference injection amount, and the corresponding load amount is set as the reference load amount. In the load range exceeding the reference load amount, the fuel for the reference injection amount out of the required injection amount is injected from the port injection valve, and the reference injection amount out of the required injection amount is not. In the compression ignition type internal combustion engine, an additional amount of fuel is injected from the in-cylinder injection valve before the compression top dead center.
[0017]
Since the amount of fuel injected from the port injection valve is equal to or less than the amount of fuel that causes knocking, knocking does not occur even when the port injection fuel self-ignites. The in-cylinder injected fuel injected from the in-cylinder injection valve evaporates in the vicinity of the compression top dead center and mixes with the premixed gas while cooling the premixed gas including the port injected fuel to become a combustible air-fuel mixture. . In the fuel combustion process, the premixed gas including the port-injected fuel is first self-ignited, and the in-cylinder injected fuel is ignited by the combustion gas and diffusely burned. When the in-cylinder injected fuel undergoes diffusion combustion, the piston is descending, so the pressure rise in the cylinder is small, and isothermal combustion continues, so that knocking does not occur at this time.
[0018]
In the inventions of (1) and (2), a cavity may be provided at the top of the piston, and the inside of this cavity may be a combustion chamber, or a recess provided in the top of the cylinder head with the piston top being flat. Also good.
[0019]
In the inventions of (1) and (2), the fuel is not limited to gasoline, and it is possible to use a light fuel with a low cetane number to which an exhaust aftertreatment device can be easily applied.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a compression ignition type internal combustion engine according to the present invention will be described with reference to the drawings of FIGS.
[0021]
FIG. 1 is a sectional view of a compression ignition type 4-cycle gasoline engine as a compression ignition type internal combustion engine. The engine 1 includes a cylinder 4 including a cylinder block 2 and a cylinder head 3, and a piston 5 that can slide back and forth in the axial direction and cannot rotate in the circumferential direction. The piston 5 rotates a crankshaft (not shown) via a connecting rod (not shown).
[0022]
The cylinder head 3 is provided with an intake port 6 for supplying intake air into the cylinder 4 and an exhaust port 7 for exhausting gas in the cylinder 4. The intake port 6 is a so-called swirl port that can generate a swirl. Instead of using a swirl port, a swirl control valve may be provided to generate a swirl. The intake system is not equipped with a throttle valve, which is equipped with a spark ignition gasoline engine.
[0023]
The intake port 6 opens at the inner top surface of the cylinder head 3 to form an intake port, and this intake port is controlled to be opened and closed by an intake valve 8. The exhaust port 7 opens at the inner top surface of the cylinder head 3 to form an exhaust port, and this exhaust port is controlled to be opened and closed by an exhaust valve 9. These intake valve 8 and exhaust valve 9 are urged in a valve closing direction (a direction away from the piston 5) by a valve spring 10 installed between the cylinder head 3 and against the valve spring against the piston 5. The valve is opened by being moved in the approaching direction, and is opened and closed by a valve drive mechanism including a cam 11 and the like. In FIG. 1, the valve spring and the cam mechanism for the exhaust valve 9 are not shown.
[0024]
A cavity 13 is formed at the top of the piston 5, and this cavity 13 forms a combustion chamber 14 when the piston 5 is located at the top dead center. The cavity 13 is arranged eccentric from the center of the piston 5 so as not to interfere even if the intake valve 8 is opened when the piston 5 is located at the top dead center.
[0025]
Further, the cylinder head 3 has a port injection valve 15 for injecting fuel into the intake port 6 with the injection hole facing the intake port 6, and a combustion chamber 14 in the cylinder with the injection hole facing the combustion chamber 14. An in-cylinder injection valve 16 for directly injecting fuel is installed.
[0026]
Since the port injection valve 15 injects fuel into the low-pressure intake port 6, a low-pressure fuel injection valve can be used. For example, the injection valve may inject at a low pressure in the range of 0.15 to 1 MPa. On the other hand, since the in-cylinder injection valve 16 is for injecting fuel into the high-pressure fuel chamber 14 when the piston 5 is located near the top dead center, it is necessary to use a high-pressure fuel injection valve. If the compression ratio is 14 to 20, an injection valve that injects at a high pressure in the range of 10 to 30 MPa is employed.
[0027]
The fuel injection timing of the port injection valve 15 is set after the top dead center of the piston 5 in the intake stroke, and the fuel injection timing of the in-cylinder injection valve 16 is set before the compression top dead center of the piston 5. .
[0028]
Incidentally, the opening and closing timing of the intake valve 8 can be changed according to the operating conditions of the engine 1. Hereinafter, an example of the opening / closing timing varying means 12 for varying the opening / closing timing of the intake valve 8 will be described with reference to FIG.
[0029]
The cam 11 for driving the intake valve 8 is fixed to an intake camshaft 20 that is rotatably supported by the cylinder head 3. The intake camshaft 20 is linked via a timing belt 23 to a pulley 21 that is rotationally driven by a crankshaft (not shown). The pulley 21 and the intake camshaft 20 are coupled so as to rotate synchronously and are coupled so that the phases can be changed.
[0030]
More specifically, an end portion of the intake cam 20 is rotatably provided inside the pulley 21, and a cylindrical plunger 22 is disposed in the axial direction between the outer end portion of the intake cam 20 and the pulley 21. It is movably intervened.
[0031]
Each of the outer peripheral surface of the plunger 22 and the inner peripheral surface of the pulley 21 is formed with a helical spline 22a (the reference numerals for the helical spline of the pulley 21 are omitted) that can mesh with each other and slide relative to each other in the axial direction. ing. Due to the meshing of these helical splines, the rotational driving force of the pulley 21 is transmitted to the plunger 22.
[0032]
Further, helical splines 20a (the reference numerals for the helical splines of the plunger 22 are omitted) that engage with each other and slide relative to each other in the axial direction also on the outer peripheral surface of the intake camshaft 20 and the inner peripheral surface of the plunger 22. Is formed. The rotational driving force of the plunger 22 is transmitted to the intake camshaft 20 by the meshing of these helical splines.
[0033]
That is, the rotational driving force of the pulley 21 is transmitted to the intake camshaft 20 via the plunger 22 by the engagement of the helical spline of the pulley 21 and the plunger 22 and the engagement of the helical spline of the plunger 22 and the intake camshaft 20.
[0034]
Further, pressure chambers (not shown) are provided on both sides in the axial direction across the plunger 22, and hydraulic circuits (not shown) for supplying and shutting off the hydraulic pressure to each pressure chamber are provided. Yes.
[0035]
Then, by controlling the oil pressure applied to each pressure chamber, the plunger 22 can be moved in the axial direction within a predetermined range. When the plunger 22 moves in the axial direction, the plunger 22 moves while rotating along a helical spline that meshes with the pulley 21 and moves while rotating along a helical spline that meshes with the intake camshaft 20.
[0036]
Therefore, by moving the plunger 22 in the axial direction with respect to the pulley 21, the phase of the pulley 21 and the intake camshaft 20 can be continuously changed in a stepless manner within a predetermined range. Further, after moving the plunger 22 to a predetermined position, the hydraulic circuit is shut off to maintain the oil pressure in both the pressure chambers, making the plunger 22 immovable, and the phase between the pulley 21 and the intake camshaft 20 is changed. It can be held in a predetermined manner.
[0037]
That is, the opening / closing timing of the intake valve 8 can be changed as desired by the opening / closing timing control means 12. Note that the opening / closing timing of the exhaust valve 9 can be changed as desired by the same opening / closing timing control means as the opening / closing timing control means 12 of the intake valve 8.
[0038]
Next, the operation of the engine 1 will be described.
First, the engine 1 is actually operated in advance, and a maximum fuel injection amount that does not cause knocking when fuel is injected only from the port injection valve 15 is obtained, and this injection amount is set as a reference injection amount Qb, corresponding to this. The load amount to be set is set as the reference load amount Hb.
[0039]
In the following description, as shown in FIG. 3, a load region that is equal to or less than the reference load amount Hb is defined as a light load region, and a load region that exceeds the reference load amount Hb is defined as a high load region.
In this engine 1, the fuel of the injection quantity Qq required in accordance with the load is injected from the port injection valve 15 in the light load area, and the injection quantity Qq required in accordance with the load in the high load area. Fuel injection control is performed so that the fuel for the reference injection amount Qb is injected from the port injection valve 15 and the remaining amount Qd (Qd = Qq−Qb) is injected from the in-cylinder injection valve 16. Is called. The load amount (load magnitude) is obtained from the accelerator opening and the engine speed.
[0040]
Further, in this engine 1, the opening / closing timing control means 12 always sets the opening timing of the intake valve 8 to the most retarded angle (indicated by a solid line in FIG. 4) in the reference load amount Hb and the high load range, and the low load range. Then, the valve opening timing of the intake valve is controlled so as to gradually shift steplessly toward the advance side as the load decreases. That is, in the light load range, as shown in FIG. 5, as the load decreases, the valve opening polymerization period of the intake valve 8 and the exhaust valve 9 is controlled to be longer. The compression ratio also increases.
[0041]
Hereinafter, the combustion process in the engine 1 will be described separately for a light load region and a high load region.
(1) Light load range
In the intake stroke, there is a valve opening polymerization period before and after the top dead center of the piston 5, and the high temperature remaining in the cylinder 4 during the valve opening polymerization period before the piston 5 reaches the top dead center. When the exhaust gas flows back into the intake port 6 and substantial intake into the cylinder 4 starts after the top dead center of the piston 5, the exhaust gas flowing back into the intake port 6 again becomes the cylinder 4. (Hereinafter, this re-inhalation of the exhaust gas into the cylinder 4 is referred to as internal EGR). As a matter of course, the internal EGR is sucked into the cylinder 4 before fresh air is sucked.
[0042]
In the light load region, the smaller the load is, the longer the valve opening polymerization period is. Therefore, the smaller the load is, the larger the amount of internal EGR is. Since the amount of heat in the internal EGR is used for intake air heating, the smaller the load, the higher the intake air temperature, and the higher the gas temperature in the combustion chamber 14 before starting compression. Furthermore, since the compression ratio substantially increases due to the early closing of the intake valve 8, the gas temperature in the cylinder 4 at the compression end point becomes higher.
[0043]
Further, in the light load region, the entire injection amount Qb required according to the load at that time is injected from the port injection valve 15, and fuel is not injected from the in-cylinder injection valve 9.
The fuel injection timing of the port injection valve 15 is set after the top dead center of the piston 5 in the intake stroke, and this is nothing but after the substantial intake into the cylinder 4 is performed. The fuel injected from the valve 15 is reliably sucked into the cylinder 4 without flowing back through the intake port 8.
[0044]
In addition, the internal EGR is first sucked into the cylinder 4 and then fresh air is sucked. At that time, since the intake port 6 is constituted by a swirl port, both the internal EGR and the fresh air are swirled. Thus, the air is sucked in a stratified state, and the internal EGR and the fresh air are not completely mixed in the cylinder 4.
[0045]
Then, by adjusting the fuel injection timing of the port injection valve 15 at the time of fresh air intake after the internal EGR is sucked into the cylinder 4, the fuel injected from the port injection valve 15 is uniformly premixed with the fresh air. In the cylinder 4, it exists in a layered state as a uniform premixed gas at the upper part of the internal EGR.
[0046]
That is, even after the fuel sucked together with fresh air is sucked into the cylinder 4, a large amount of oxygen is still present around the fuel. Then, coupled with the fact that fresh air is heated by the internal EGR, the inside of the cylinder 4 becomes an atmosphere that is extremely easy to self-ignite.
[0047]
Therefore, if the combustion chamber 14 is compressed to a predetermined level after moving to the compression stroke, the fuel is surely self-ignited. Thereby, in this engine 1, the stable combustion area by the side of a light load is expanded rather than the conventional compression ignition gasoline engine.
[0048]
In the above description, it is assumed that most of the fuel is premixed with fresh air and the surroundings of the fuel are in an atmosphere with sufficient oxygen. Focusing on the improvement in ignitability by sufficient oxygen, the internal EGR and fresh air are stratified. Is realized by swirl.
[0049]
However, when paying attention to the improvement in ignitability due to the rise in intake air temperature, it is better to completely mix the internal EGR and fresh air in the cylinder 4 than to stratify the internal EGR and fresh air by swirl. There is also a way of thinking. Therefore, it is also possible to heat the fresh air by generating a tumble in the intake air to completely mix the internal EGR, fresh air and fuel. When the tumble is generated in this way, the oxygen concentration around the fuel is lower than that when the swirl is generated, but the intake air temperature around the fuel rises. This is an improvement over conventional compression ignition gasoline engines.
[0050]
In the light load range, as the load increases, the internal EGR decreases and the degree of heating with respect to the intake air also decreases, so that knocking does not occur even when approaching the reference load amount Hb.
[0051]
(2) High load range
In the high load range, the intake valve 8 and the exhaust valve 9 have a valve opening polymerization period in the intake stroke, but the valve opening timing of the intake valve 8 is set to the most retarded angle and the valve opening polymerization period is extremely small. There is almost no EGR, so there is little intake air heating.
[0052]
In the high load range, the fuel for the reference injection amount Qb out of the injection amount Qq required according to the load is injected from the port injection valve 15, and the remaining amount Qd (Qd = Qq-Qb) of fuel is injected into the cylinder. It is injected from the inner injection valve 16. As described above, the fuel injection timing is set after the top dead center of the piston 5 in the intake stroke from the port injection valve 15 and before the compression top dead center from the in-cylinder injection valve 16.
[0053]
Therefore, first, fuel is injected from the port injection valve 15 after the top dead center of the piston 5 in the intake stroke, and becomes fresh air and uniform premixed gas in the cylinder 4.
On the other hand, fuel is injected from the in-cylinder injection valve 16 toward the cavity 13 of the piston 15 before the compression top dead center. This fuel injection timing is before the fuel injected from the port injection valve 15 self-ignites. Therefore, the fuel injected from the in-cylinder injection valve 16 evaporates near the compression top dead center, and the premixed gas already sucked into the cylinder 4 is cooled by the latent heat of vaporization. At the same time, the fuel injected in the cylinder is mixed with the pre-mixed gas to become a combustible air-fuel ratio.
[0054]
In the compression stroke, when the inside of the combustion chamber 14 is compressed in the vicinity of the compression top dead center, the premixed gas is self-ignited in the combustion chamber 14, and the fuel injected into the cylinder by the combustion gas is the top dead center. After that, it ignites and diffuses and burns. Since the injection amount from the port injection valve 15 is the reference injection amount Qb, knocking does not occur when the fuel injected by the port self-ignites. Further, when the fuel injected into the cylinder diffuses and burns, since the piston 5 is already descending, the pressure rise in the cylinder 4 is small and the isothermal combustion is continued, so that knocking is avoided.
[0055]
Therefore, in the engine 1, knocking can be avoided even in a high load region, and the stable combustion region on the high load side can be expanded as compared with the conventional compression ignition gasoline engine.
[0056]
As described above, in the compression ignition type gasoline engine 1, the stable combustion region on the low load side is expanded, and the uniform premixed combustion is performed in the low load region, thereby realizing low NOx of the exhaust. . Therefore, a catalytic converter having a low NOx purification rate can be used in the exhaust purification system, and this is particularly effective when the present invention is applied to a large displacement engine having a light load to a medium load in a practical load range. .
[0057]
Moreover, the light load range, which is the majority of the practical use range of the engine, is covered by port injection, the amount of in-cylinder injected fuel is small even in the entire engine use range, and the injection timing is compression top dead center Due to the proximity, the engine oil is hardly diluted with fuel.
[0058]
In carrying out the present invention, the compression ratio, the fuel injection timing of the port injection valve 15, the fuel injection timing of the in-cylinder injection valve 16, and the opening / closing timings of the intake valve 8 and the exhaust valve 9 are experimentally examined. Find the optimal value and apply it.
[0059]
<Other embodiments>
In the above embodiment, the opening / closing polymerization period of the intake valve 8 and the exhaust valve 9 is changed by changing the opening / closing timing of only the intake valve 8, but the intake valve 8 and the exhaust valve 9 are changed as shown in FIG. The valve opening polymerization period may be changed by changing both the opening and closing timings. The means for changing the opening / closing timing of the exhaust valve 9 can be configured in the same manner as the opening / closing timing varying means for the intake valve 8 described above.
[0060]
Further, when the opening / closing timing varying means for the exhaust valve 9 is provided, the opening timing of the exhaust valve is gradually advanced as the engine water temperature becomes lower as shown in FIG. Thus, the lower the engine water temperature, the higher the intake air heating effect, and the self-ignitability of the port-injected fuel can be improved. This is because if the opening timing of the exhaust valve 9 is advanced, the combustion gas in the cylinder 4 is exhausted before sufficiently expanding, and the expansion ratio becomes smaller. Depending on what you can get.
[0061]
【The invention's effect】
As described above, according to the present invention, the maximum injection amount that does not cause knocking when fuel is injected only from the port injection valve is set as the reference injection amount, and the corresponding load amount is set as the reference load amount. In the load range below the reference load amount, the entire required fuel injection amount is injected from the port injection valve during the intake stroke after the top dead center of the piston, and the intake valve and the exhaust gas are exhausted as the load decreases. By controlling the opening / closing timing variable means so that the valve opening polymerization period of the valve becomes longer, the smaller the load, the greater the amount of internal EGR, the greater the intake heating effect, and the self-ignitability in the light load region improves. The stable combustion area on the light load side can be expanded as compared with the conventional case.
[0062]
Further, since uniform premixed combustion by port injection is performed in the low load region, it is possible to achieve low NOx emission, and therefore, a catalytic converter having a low NOx purification rate can be used in the exhaust purification system.
[0063]
In addition, the maximum injection amount that does not cause knocking when fuel is injected only from the port injection valve is set as the reference injection amount, and the corresponding load amount is set as the reference load amount. The fuel for the reference injection amount out of the required injection amount is injected from the port injection valve, and the fuel that is insufficient for the reference injection amount out of the required injection amount is compression dead from the cylinder injection valve By injecting before the point, occurrence of knocking in the high load region can be avoided, and the stable combustion region on the high load side can be expanded as compared with the conventional case. Further, since the amount of in-cylinder injected fuel can be reduced, the dilution of the lubricating oil with the fuel can be reduced.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an embodiment of a compression ignition type internal combustion engine of the present invention.
FIG. 2 is a perspective view showing an example of an opening / closing timing varying means used in the compression ignition type internal combustion engine of the present invention.
FIG. 3 is an example of a fuel injection map in the compression ignition internal combustion engine of the present invention.
FIG. 4 is a diagram showing an example of opening and closing timings of intake and exhaust valves in a compression ignition type internal combustion engine of the present invention.
FIG. 5 is a diagram showing an example of a change in the valve opening polymerization period of the intake and exhaust valves in the compression ignition type internal combustion engine of the present invention.
FIG. 6 is a view showing another example of the opening / closing timing of the intake and exhaust valves in the compression ignition type internal combustion engine of the present invention.
FIG. 7 is a valve opening timing change diagram in the case of changing the valve opening timing of the exhaust valve according to the engine water temperature in the compression ignition type internal combustion engine of the present invention.
[Explanation of symbols]
1 Compression ignition gasoline engine (compression ignition internal combustion engine)
4 cylinders
5 piston
6 Intake port
7 Exhaust port
8 Intake valve
9 Exhaust valve
12 Opening / closing timing variable means
14 Combustion chamber
15 port injection valve
16 In-cylinder injection valve

Claims (2)

A cylinder, a piston that reciprocates in the cylinder, a combustion chamber defined by the cylinder and the piston, an intake valve that opens and closes an intake port for supplying intake air into the cylinder, and a gas in the cylinder An exhaust valve for opening and closing an exhaust port for exhausting air, an opening / closing timing varying means for changing an opening / closing timing of only the intake valve or both of the intake valve and the exhaust valve, and fuel in the intake port In a compression ignition internal combustion engine comprising a port injection valve for injecting fuel and an in-cylinder injection valve for directly injecting fuel into the combustion chamber,
The maximum injection amount that does not cause knocking when fuel is injected only from the port injection valve is set as the reference injection amount, and the load amount corresponding to this is set as the reference load amount. The required fuel injection amount is injected from the port injection valve during the intake stroke after the top dead center of the piston, and the opening polymerization period of the intake valve and the exhaust valve increases as the load decreases. The compression ignition internal combustion engine, wherein the opening / closing timing varying means is controlled. A cylinder, a piston that reciprocates in the cylinder, a combustion chamber defined by the cylinder and the piston, an intake valve that opens and closes an intake port for supplying intake air into the cylinder, and a gas in the cylinder A compression ignition internal combustion engine comprising: an exhaust valve that opens and closes an exhaust port for exhausting air; a port injection valve that injects fuel into the intake port; and an in-cylinder injection valve that directly injects fuel into the combustion chamber In
When the fuel is injected only from the port injection valve, the maximum injection amount that does not cause knocking is set as the reference injection amount, the load amount corresponding to this is set as the reference load amount, and in the load range exceeding the reference load amount, Of the required injection amount, the fuel corresponding to the reference injection amount is injected from the port injection valve. Of the required injection amount, the fuel that is insufficient for the reference injection amount is compressed from the in-cylinder injection valve to the compression top dead center. A compression ignition type internal combustion engine which is injected before.

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