JP2013194730A - Super-high efficiency four-cycle internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remarkably enhance efficiency by adopting a concentrated combustion chamber, multi-point ignition, a high compression ratio, a high expansion ratio, and an HCCI combusting system, and to reduce NOemission by adopting an ignition time of a top dead center or a subsequent point owing to rapid combustion by the multi-point ignition.SOLUTION: A concentrated combustion chamber is constituted by arranging a combustion chamber 1 with an intake valve 8 and an exhaust valve 2 and forming a squish part S with a minute gap between a top face of a piston and a wall surface of a cylinder head at a top dead center around the combustion chamber. Two or more spark gaps (ignition plug 21) are arranged in the combustion chamber and an ignition time of each spark gap is set to the top dead center or the subsequent point. Furthermore, in a premixed compression ignition combustion range, a closing time of an exhaust valve is set later than the top dead center to reabsorb an exhaust gas into a cylinder by a valve timing control device 15 of the exhaust valve, and in the premixed compression ignition combustion range, a closing time of an intake valve is advanced to increase an effective compression ratio by a valve timing control device 16 of the intake valve. Premixed compression ignition combustion and spark ignition combustion are switched depending on an operating condition of an engine.

Description

The present invention adopts a centralized combustion chamber, multi-point ignition system, high compression ratio, high expansion ratio, HCCI combustion system, etc. to achieve super-efficient thermal efficiency and high efficiency 4 cycles to minimize NOx generation The present invention relates to an internal combustion engine.

In general, in a four-cycle internal combustion engine, the thermal efficiency remains at a low value of 10 to 20% in a low load region and 30 to 35% in a medium / high load region. This is because the compression ratio is 12 or less to avoid knocking, there is a pump loss due to the intake throttle, the lean combustion is difficult, and the friction loss / cooling loss due to the adoption of multiple cylinders of 3 to 8 cylinders is large. Responsible. In particular, in recent years, the HCCI combustion method (premixed compression ignition combustion), in which ultra lean combustion is possible and pump loss and cooling loss are greatly reduced, is said to require a compression end temperature of 1000K. It is difficult to achieve with a 4-cycle engine.

The object of the present invention is first to achieve ultra-high efficiency of thermal efficiency. For this reason, a concentrated combustion chamber, a multipoint ignition system, a high compression ratio of 14 to 15th, an expansion ratio of 18th, an HCCI combustion system, and a conventional 2 to 4 cylinder engine that was a 3 to 8 cylinder engine A means to reduce friction loss and cooling loss by adopting a small number of cylinders is adopted. Secondly, it aims at realizing ultra-low NOx emission by adopting top dead center or subsequent ignition timing by a rapid combustion method by multi-point ignition. To achieve ultra-low NOx emission by the HCCI combustion method that does not rely on the spark ignition method in the low-load region, and thus achieve ultra-low NOx emission in the entire load region.

Means to solve the problem

In order to solve the above problems, the present invention provides a four-cycle internal combustion engine having an intake valve driven by a cam provided on an intake cam shaft and an exhaust valve driven by a cam provided on an exhaust cam shaft. In the combustion chamber, and a squish portion having a minute gap is formed between the top surface of the piston and the cylinder head wall surface at the top dead center position around the combustion chamber so that the combustion chamber is a concentrated combustion chamber. A valve opening / closing timing control device that allows two or more spark gaps to face and controls the ignition timing of the spark gap to be at or above the compression top dead center and further varies the opening / closing timing of the exhaust valve. In the premixed compression ignition combustion region, the exhaust valve closing timing is delayed from the top dead center, the exhaust gas is re-inhaled into the cylinder, and the exhaust valve opening timing is controlled according to the engine load. To control the expansion ratio as greater than the effective compression ratio. In the first aspect of the invention, the intake valve is provided in the combustion chamber, and the valve opening / closing timing control device that varies the opening / closing timing of the intake valve increases the effective compression ratio by increasing the closing timing of the intake valve in the premixed compression ignition combustion region. The premixed compression ignition combustion and the spark ignition combustion are switched according to the operating conditions such as engine load and rotation speed. In the second aspect of the invention, the intake valve is provided in the combustion chamber and the opening / closing timing thereof is fixed, so that the premixed compression ignition combustion and the spark ignition combustion are switched according to the operating condition of the engine. In the third aspect of the invention, the intake valve is provided so as to face the squish portion, and the premixed compression ignition combustion and the spark ignition combustion are switched depending on the operating condition of the engine.

Effect of the invention

According to the present invention, a multi-point ignition system is achieved by facing two or more spark gaps in a compact concentrated combustion chamber to achieve ultra-rapid combustion (the combustion period is 1/3 of the conventional crank angle). The ignition timing at or above the top dead center can be adopted. Accordingly, not only the maximum combustion temperature and pressure are low, but also cooling loss and friction loss are small, and combustion before top dead center does not occur. Therefore, there is a feature that cooling loss and friction loss corresponding to this period are small. It is particularly reaches the flame as shown in FIG. 4 with respect to the cooling loss (b) until the squish portion S _1, because squish portion S ₂ is a good heat insulating layer of air only, cooling loss is very small. Since the ignition timing is at or above the top dead center, there is no worry of knocking and a high compression ratio (14th) can be adopted, and since the expansion ratio is higher than the compression ratio (18th), the thermal efficiency is very high. Moreover, since the HCCI combustion with high thermal efficiency can be performed in the low load region, the improvement range of the thermal efficiency is large. From the above, a dramatic improvement in thermal efficiency can be expected.
In the HCCI combustion region, exhaust gas is re-inhaled at an exhaust valve closing timing of, for example, 70 ° after top dead center. Therefore, the compression end temperature rises in combination with the effect of the 18th high compression ratio, and the HCCI combustion region. Can be expanded.
For this reason, the pump loss is greatly reduced. Further, since the fuel is injected into the combustion chamber so as to remain only in the combustion chamber (injection after the intake valve is closed), the squish portion S is only air, and unburned HC and CO are not discharged. In addition, since the ignition timing at or above the top dead center is adopted, NOx generation is almost zero, and therefore an expensive lean NOx purification catalyst is not required (only an inexpensive oxidation catalyst). Moreover, the ignition timing is at the top dead center or later, and a high expansion ratio of 18th is adopted, so the exhaust gas temperature is low, and it is not necessary to supply a rich mixture to protect the catalyst (high load range) .

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 shows an ultra-high efficiency four-cycle internal combustion engine according to the present invention. An intake valve 8 driven by a cam provided on an intake cam shaft (not shown) and an exhaust valve driven by a cam 5 provided on the exhaust cam shaft 4. 2 is provided. The exhaust valve 2 is driven by the cam 5 through the rocker arm 3, and the intake valve 8 is also driven in the same manner, although not shown. In this four-cycle internal combustion engine, each stroke of intake, compression, expansion, and exhaust is performed by two rotations of the crankshaft. In the present invention, the conventional three to eight cylinders are reduced to a small number of two to four cylinders. In FIG. 1 (a), the ignition plug 21, the fuel injection valve 12 and the like as viewed from above the combustion chamber 1 as a two-cylinder engine. The layout is shown in FIG.
7 is a catalyst for purifying exhaust gas, 10 is an intake throttle valve driven by an actuator (electric motor) 11, 22 is an electronic control unit, and 24 is a hydraulic control valve. The exhaust camshaft 4 is provided with a valve opening / closing timing control device 15 integrally with a sprocket (or pulley) 13, and the intake camshaft (not shown) is similarly provided with a valve opening / closing timing control device 16 (valve opening / closing timing). Since the timing control device 15 has the same structure as the valve opening / closing timing control device 16, the internal structure is omitted), and the sprockets 13 and 14 are driven by being decelerated to 1/2 through a crankshaft and a chain (or a toothed belt). Is done. A known valve timing control device 16 includes a housing 17 and a rotor 18. The housing 17 is coupled and integrated with a sprocket 14 and a bolt, and the rotor 18 is coupled and integrated with an intake camshaft and a bolt (not shown). . The advance chamber 19 and the retard chamber 20 are formed by the housing 17 and the rotor 18, and hydraulic oil is supplied from the hydraulic control valve 23. The hydraulic control valve 23 is supplied with hydraulic pressure from a hydraulic pump (not shown), and a plunger 24 and a spool whose axial movement is controlled by an electromagnetic solenoid according to an output signal from an electronic control unit (hereinafter referred to as ECU) 22, which will be described later. A valve 26 and a spring 27 are provided, and the spool valve 26 is positioned at a position where the repulsive force of the spring 27 and the pressing force of the plunger 24 are balanced. The ECU 22 receives a signal from a crank angle sensor that outputs a crank angle signal for each predetermined crank angle, and a signal from a cam angle sensor that outputs a cam angle signal for each predetermined cam angle. The ECU 22 receives signals from the cam angle sensor. The cam phase angle can be detected based on the output phase difference between the output rotation angle pulse and the rotation angle pulse output from the crank angle sensor. The ECU 22 outputs a control signal to the hydraulic control valve 23 so that the phase difference of the rotor 18, that is, the intake camshaft with respect to the crankshaft becomes a target value. The ECU captures the detected cam phase angle as a feedback signal, and feedback-controls the drive duty ratio of the hydraulic control valve 23 according to a deviation value from the target phase angle in the control.
The hydraulic control valve 23 drives an electromagnetic solenoid according to the duty ratio instructed from the ECU 22, adjusts the supply / discharge of hydraulic pressure to the advance chamber 19 and the retard chamber 20, and advances the intake camshaft to the target phase angle. Alternatively, the angle is retarded or neutral (fixed to an arbitrary cam phase angle). The ECU 22 is mainly composed of a microcomputer including a ROM, a RAM, a CPU, an input port, an output port, and the like, and these are mutually connected by a bidirectional bus. The ECU 22 includes various sensors for parameters necessary for grasping the motion state of the engine, such as a crank angle sensor, a cam angle sensor, an accelerator sensor for detecting an accelerator opening degree, an air flow rate sensor for air sucked into the engine, and an engine cooling water temperature. Each signal from a water temperature sensor, an atmospheric pressure sensor, an O ₂ sensor, a knock sensor, or the like for detecting the signal is transmitted to the input port via the corresponding A / D converter. The engine speed can be known from the output signal from the crank angle sensor. The output port is connected to the fuel injection valve 12, the spark plug 21, the actuator 11, the hydraulic control valve 23, and the like via corresponding drive circuits, and transmits respective control signals. The ROM has a control routine for controlling the engine, such as a control routine for determining the injection amount and injection timing of the fuel injection valve 12, a control routine for controlling the energization of the spark plug 21, and controls used for them. A map containing the values is stored. Various data stored in the RAM are rewritten to the latest data every time the engine speed sensor outputs a signal. The CPU operates in accordance with an application program stored in the ROM, and executes fuel injection control, ignition timing control, and the like.

In the present invention, fuel is injected by the fuel injection valve 12 so as to remain only in the combustion chamber 1 (injected obliquely upward as shown in FIG. 1 (C)), and is applied to the cylinder inner wall, piston top surface, and squish portion S. Does not adhere. The fuel is injected during the compression stroke after the intake valve is closed. Therefore, in the compression stroke, air in the cylinder may flow into the combustion chamber 1 vigorously, so that the air-fuel mixture exists only in the combustion chamber 1 and the combustion in the combustion chamber 1 is completed to complete the combustion. (There is no combustion of the squish portion S). The combustion chamber 1 is provided with an exhaust valve 2 and an intake valve 8, and a squish portion having a minute gap (about 0.7 mm) between the piston top surface and the cylinder head wall surface at the top dead center position around the combustion chamber 1. S is formed as a concentrated combustion chamber.
Combustion chamber 1 is exposed to two or more spark gaps (here, four spark gaps consisting of four spark plugs 21 as shown in FIG. 1 (b)), and the ignition timing of this spark gap is determined. It is controlled to be at the top dead center or later.
FIG. 1 (b) is a view of the combustion chamber 1 of FIG. 1 (b) as viewed from above, and this is shown in a simplified manner in FIG. 2 (b). The combustion chamber 1 has four spark gaps G ₁ , G ₂ , G ₃ , and G ₄ , and the flame propagation distance in the longitudinal direction of the combustion chamber is a / 2, where a≈0.8r Therefore, after all, 0.8r / 2 = 0.4r. On the other hand, since the flame propagation distance in the case of the center 1 ignition flower gap in FIG. 2 (a) is r, in the present invention, compared with FIG. 2 (a), the flame propagation distance is 0.4 · r / r = 1 / Although it is greatly shortened to 2.5, the spark gap G ₁ (G ₃ ) is in a position protruding about 5 mm from the wall surface of the combustion chamber, so that the flame propagation distance is shortened to 1 / 2.8. The flame propagation distance in the short axis direction of the combustion chamber is b, and since this is short, the combustion is quick, so that the flame spread from the spark gaps G ₂ and G ₄ collides in the center and the flame surface is moved in the long axis direction. Since it spreads in an elliptical shape, the flame propagation speed in the long axis direction is increased, and the flame propagation distance is considered to be substantially 1/3 of 1 / 2.8 or less (there is also a strong squish effect). Compared to the case of the center 1 spark gap in FIG. 2 (a), the conventional combustion period of 40 to 50 degrees in crank angle can be greatly shortened to about 1/3 of 15 degrees. . As a result, even if the ignition timing is set to top dead center or later, ultra-rapid combustion is possible, so there is no deterioration in thermal efficiency. Rather, cooling loss and friction loss are greatly reduced by lowering the maximum combustion temperature and pressure. Heat efficiency. In the case of a large displacement engine, this can be achieved by making the combustion chamber 1 have six spark gaps as shown in FIG.
In the case of an engine with a very small displacement, since the absolute value of the flame propagation distance is small, a spark gap of 3 points (or 2 points) as shown in FIG. The present invention is characterized by having two or more spark gaps facing the combustion chamber. In the present invention, a spark plug is used as the spark gap. However, as shown in FIG. 2 (f), an electrically non-conductive plate 28 such as ceramic having a spark gap 29 (4 to 6 points) is used as shown in FIG. As such, it may be provided in the combustion chamber.

Next, each operation state of the four-cycle internal combustion engine according to the present invention will be described.
In the present invention, since the valve opening / closing timing control devices 15 and 16 are provided, the opening / closing timing of the exhaust valve 2 and the intake valve 8 can be freely controlled (however, the valve opening / closing timing control device 15 employed in FIG. 16 is for changing only the opening / closing timing while the opening / closing period is constant). For example, HCCI combustion is performed in a low load range. At this time, the valve opening / closing timing is 30 ° after bottom dead center with the crank angle as shown in FIG. 3 (a) (the compression ratio at this time is approximately 18). The exhaust valve opening timing is controlled so that the crank angle is 10 ° after the bottom dead center (the expansion ratio at this time is 18). Switch to spark ignition combustion in the middle / high load range, as shown in Fig. 3 (b), the intake valve closing timing is 70 ° after bottom dead center (compression ratio is 14), and the exhaust valve opening timing is crank angle. It is controlled so as to be 40 ° before the bottom dead center (the expansion ratio at this time is approximately 18). The engine is started by spark ignition combustion by the spark plug 21. At the time of starting and warming up (in the cold state), the intake valve closing timing is 30 ° after bottom dead center and the exhaust valve opening timing is as shown in FIG. Is 40 ° before bottom dead center, the compression ratio is approximately 18, and the expansion ratio is approximately 18. Accordingly, since the compression ratio becomes high, the compression end temperature rises and good combustion is obtained (because the engine is cold, self-ignition does not occur). In addition, since the present invention employs a multi-point ignition system, ultra-rapid combustion is possible (as described above, the combustion period is shortened to about 15 ° of 1/3 of the conventional crank angle). Inside, the ignition timing can be greatly delayed to raise the exhaust temperature and promote early activation of the catalyst. In the present invention, the ignition timing of the spark plug 21 is basically at or above the top dead center. However, it is preferable to set the ignition plug 21 before the top dead center in order to improve startability. In the low load range after completion of engine warm-up, the PCCI combustion method, that is, the premixed compression ignition combustion (among others, the HCCI combustion method using a homogeneous air-fuel mixture can suppress NOx generation to almost zero. 3), the intake valve closing timing is 30 ° after bottom dead center (the opening timing is naturally 40 ° before top dead center), and the exhaust valve closing timing is 70 after top dead center as shown in FIG. (The opening time is naturally 10 ° after bottom dead center). At this time, the compression ratio is approximately 18, and the expansion ratio is approximately 18. Therefore, the valve overlap period is 110 °, and high temperature and large amount of exhaust gas is re-inhaled into the cylinder from the exhaust passage 6 to increase the compression end temperature, and the compression end temperature is greatly increased in combination with the effect of the 18th high compression ratio. Can be raised and thus can easily cause HCCI combustion. To further increase the temperature at the start of compression and the compression end temperature, when exhaust gas is re-inhaled from the exhaust passage 6, it is preferable to re-inhale the exhaust gas whose temperature has risen in the catalyst 7 and further downstream thereof (exhaust passage 6). If it has a heat insulating structure such as a port liner, it is more effective). Therefore, it is better that the distance between the exhaust valve 2 and the catalyst 7 is short, and this point is advantageous in the two-cylinder engine. In the present invention, since the exhaust gas temperature is low even in a high load region, thermal stress is not applied to the catalyst even if the exhaust passage 6 has a heat insulating structure. Further, when the piston top surface has a heat insulating structure, the air-fuel mixture in the combustion chamber 1 is subjected to a heating action, so that it becomes easier to cause HCCI combustion and there is a concern about a decrease in charging efficiency in a high load region. In this case, as shown in FIG. 4 (a), the piston top surface portion 30 corresponding to the portion immediately below the combustion chamber may have a heat insulating structure. For example, there are methods such as coating the heat insulating portion 30 with a heat insulating agent, and bonding the heat insulating material with bolts across an air layer. The HCCI combustion method is a low-temperature combustion as a combustion, and is also a lean combustion, so that a highly efficient operation is possible with little cooling loss, and the generation of NOx can be suppressed to almost zero. Moreover, since the compression ratio and the expansion ratio are as high as 18th, the thermal efficiency is further increased. In addition, since there is no air-fuel mixture in the squish portion S and only air, unburned HC and CO are not discharged (this is the same in the spark ignition combustion region). In HCCI combustion, when the engine load increases, the rate of increase in combustion pressure becomes higher and it becomes a state close to knocking. In the present invention, such a state is detected by a knock sensor, the intake valve closing timing is delayed, and the compression ratio is increased from 18. It can be reduced within the range up to 14, and knocking can be prevented in advance. That is, the timing at which HCCI combustion occurs can be controlled. Since this engine is a four-cycle engine, when HCCI combustion in an extremely low negative region such as an idle state is difficult, the engine can be switched to spark ignition combustion.
In the middle / high load range of the engine, the rate of increase in combustion pressure is excessive in the HCCI combustion method, and this is avoided, and the ECU 22 switches to spark ignition combustion depending on the operating conditions such as engine load and rotation speed. In this operating range, as shown in FIG. 3B, the intake valve closing timing is 70 ° after bottom dead center (the opening timing is naturally top dead center), and the exhaust valve opening timing is 40 ° before bottom dead center (the closing timing is Naturally, it becomes 20 ° after top dead center). At this time, the compression ratio is 14 and the expansion ratio is approximately 18. The expansion ratio is larger, and exhaust loss is reduced to greatly increase the thermal efficiency. In this region, the conventional combustion period of 40 ° to 50 ° in crank angle can be shortened to about 1/3 of 15 ° by the multi-point ignition method (by ultra-rapid combustion). (There is no worry of knocking despite the high compression ratio of 14th place). Therefore, the maximum combustion temperature and pressure are low, resulting in reduced cooling loss and friction loss, and no combustion before top dead center. The width is large. Now add a word especially for the cooling loss, although flame at the expansion stroke enters becomes reverse squish to squish portion S ₁ as shown in FIG. 4 (b), squish portion S ₂ is only air (flame present Not), therefore there is a good thermal insulation layer with air and the cooling loss is greatly reduced. Furthermore, since combustion is performed in the expansion stroke after top dead center, the generation of NOx can be suppressed to almost zero. Further, in the present invention, since the conventional number of 3 to 8 cylinders is changed to a small number of 2 to 4 cylinders, the cooling loss and the friction loss are naturally small, and the above combined increases the thermal efficiency.
In addition, in the present invention, since the expansion ratio is 18 with respect to the compression ratio 14, there is a margin in the heat efficiency. Therefore, if the ignition timing is slightly delayed, the generation of NOx can be completely suppressed to zero. After all, since the HCCI combustion method can also suppress the generation of NOx to almost zero, an expensive lean NOx purification catalyst can be made unnecessary (only an oxidation catalyst is sufficient). The combustion chamber 1 can also be formed on the top surface of the piston as shown in FIG.

By the way, in FIG. 1 (b), the combustion chamber 1 is provided with an intake valve 8, which has a large diameter (larger diameter than the exhaust valve 2), so that the width of the combustion chamber increases and the height decreases and becomes flat. It lacks compactness and is disadvantageous for fire propagation. As a solution to this, it is conceivable to provide the second intake valve 31 so as to face the squish portion S as shown in FIG. Accordingly, since the intake valve 8 can be the same as or smaller in diameter than the exhaust valve 2, the width of the combustion chamber 1 is reduced (and the length is reduced), and the height is increased, resulting in a compact size. In this case, the opening and closing timing of the second intake valve 31 is fixed (for example, it opens at the top dead center and closes at 30 ° after the bottom dead center), and it is desirable to drive the intake valve 8 by an independent cam. It is also possible to drive by installing a new cam on the intake camshaft to be driven. However, since the intake camshaft includes the valve opening / closing timing control device 16, it is necessary to determine the opening / closing timing of the second intake valve 31 so as not to collide with the piston. An example is shown in FIG. That is, in the HCCI combustion region, the valve is opened at the top dead center, the valve is closed at 30 ° after the bottom dead center, and in the spark ignition combustion region, the valve is opened at 40 ° after the top dead center, and the valve is closed at 70 ° after the bottom dead center ( The second intake valve 31 is closed until 40 ° after the top dead center, but the intake valve 8 is open, so that suction is performed.
Alternatively, the opening / closing timing of the second intake valve 31 is opened at the top dead center in the spark ignition combustion region and closed at 70 ° after the bottom dead center as shown in FIG. 4 (f), and a known mechanism for the rocker arm in the HCCI combustion region. The operation of the second intake valve 31 may be stopped.
For the same reason as the second intake valve 31, a second exhaust valve 2 ′ may be provided as shown in FIG. 4 (h), which is a method of driving by an independent cam, the exhaust camshaft 4. In addition, there is a method of driving by installing a new cam. In the latter case, the second exhaust valve 2 'is closed at the top dead center in the spark ignition combustion region, opened at 40 ° before the bottom dead center, and opened at 10 ° after the bottom dead center in the HCCI combustion region. The valve is closed at 50 ° after the point. In the present invention, the compression ratio (effective compression ratio) and the expansion ratio (effective expansion ratio) are made variable by changing the opening and closing timing of the intake valve 8 and the exhaust valve 2, but many other than those shown in FIG. The valve opening / closing timing control device can be used. For example, the valve opening / closing timing is changed by moving the helical spline in the axial direction, the valve opening / closing timing is changed electromagnetically or electrically, and the valve opening / closing timing is changed by sliding the solid cam in the axial direction. .
FIG. 4 (G) shows an electromagnetic valve opening / closing timing control device. In the housing 32, ring-shaped electromagnets 34 and 35 are opposed to each other with a plunger 33 integrated with a valve shaft interposed therebetween. Has been placed. The springs 37 and 36 are attached to the hollow portions of the electromagnets 34 and 35 so as to sandwich the plunger 33, so that the exhaust valve 2 (intake valve 8) is located at the intermediate position of the valve lift by the balance of the forces of the springs 37 and 36. At rest. When the electromagnet 34 is magnetized, the plunger 33 is attracted upward and the exhaust valve 2 (intake valve 8) is closed. When the electromagnet 35 is magnetized, the plunger 33 is attracted downward and opens. . The driver 38 alternately supplies an excitation current to the electromagnets 34 and 35 in accordance with a control signal from the ECU 22 that designates the opening / closing timing (including valve lift information) of the exhaust valve 2 (intake valve 8). According to this, the valve opening timing and valve closing timing of the exhaust valve 2 (intake valve 8) can be arbitrarily set, and the degree of freedom increases.

In FIG. 1, the opening / closing timing of the intake valve 8 is variable, but the valve opening / closing timing control device 16 may be removed and fixed timing (for example, 20 ° opened before top dead center and 70 ° closed after bottom dead center). This is shown in FIG. In this case, the second intake valve 39 may be provided so as to face the squish portion S for the same reason as in FIG. 4 (d) (the valve opening / closing timing is opened at the top dead center and closed at 70 ° after the bottom dead center). . If this is done, the compression ratio cannot be increased to 18 in the HCCI combustion region as shown in FIG. 1 (fixed at 14). As a result, the HCCI combustion region is narrowed, but there is no problem if this engine is used for a hybrid vehicle. That is, in an area where HCCI combustion does not occur, electric power generated in an area where engine efficiency is high and electric power stored in the battery may be supplied to the motor and run by this motor.
This is the same in FIG. 1, and even if HCCI combustion is caused in an extremely low load region close to idling, the thermal efficiency is low, so this region should not be used.

FIG. 6 (a) shows a four-cycle internal combustion engine of the present invention corresponding to the exhaust valve 2 provided in the combustion chamber 1 and the intake valve 8 provided to face the squish portion S in FIG. That is, in FIG. 6A, the exhaust valve 40 is provided in the combustion chamber 41, the intake valve 42 is provided so as to face the squish portion S, 21 is a spark plug, and 12 is a fuel injection valve (from the direction A). The cross section seen is shown in FIG. The exhaust valve 40 is the same as the valve opening / closing timing control device 15 of FIG. 1, and the valve opening / closing timing is varied. However, the exhaust valve 42 is provided so as to face the squish portion S, and in order to avoid collision with the piston, The opening and closing time is fixed. That is, in the HCCI combustion region, as shown in FIG. 6C, the intake valve 42 opens at the top dead center, closes at 70 ° after the bottom dead center, the exhaust valve 40 opens at 10 ° after the bottom dead center, and 70 after the bottom dead center. In the spark ignition combustion region, as shown in FIG. 6 (d), only the exhaust valve 40 is varied and controlled to open at 40 ° before bottom dead center and to close at 20 ° after top dead center. The Therefore, in the HCCI combustion region, the compression end temperature becomes high due to a large amount of exhaust gas re-intake, and HCCI combustion is likely to occur. The compression ratio at this time is 14. Further, since the compression ratio is 14 and the expansion ratio is as high as 18, the thermal efficiency can be greatly improved. Since only the exhaust valve 40 needs to be considered in the combustion chamber 41, the combustion chamber 41 is compact and advantageous in terms of flame propagation. If the opening / closing timing of the intake valve 42 is slightly varied by the valve opening / closing timing control device, the compression ratio is set such that the closing timing of the intake valve 42 is closed, for example, 50 ° after bottom dead center as shown in FIG. (16th place).
However, in order to avoid collision with the piston, it is necessary to make a slight relief (valve recess). The exhaust temperature is low for reasons such as ignition at or above the top dead center and high expansion ratio, and there is no concern about pre-ignition.

Next, one of the features of the present invention is that the ignition timing is at or above the top dead center. Consider the case where the ignition timing is before the top dead center as in the prior art (the number of spark plugs is not limited). Absent). That is, if the pre-top dead center ignition method is employed, the maximum combustion pressure / temperature rises, so that cooling loss and friction loss increase and thermal efficiency decreases, and NOx is generated in the spark ignition combustion region.
However, this is the shortcoming, enabling the HCCI combustion method with high thermal efficiency in the low load range, the expansion ratio being higher than the compression ratio, and the extremely low cooling loss as described in FIG. For this reason, it has much higher thermal efficiency than before. NOx generated in the spark ignition combustion region can be suppressed to 0 by the three-way catalyst using the theoretical mixing ratio. As described above, although it is slightly backward than the present invention, it has a much higher thermal efficiency than the prior art.

The figure which shows the super high efficiency 4 cycle internal combustion engine by this invention. The figure which shows layouts, such as a spark plug and a fuel injection valve, in a combustion chamber. The figure which shows the opening / closing timing of an intake valve and an exhaust valve. The figure which shows the various Example of this invention. The figure which shows the super high efficiency 4 cycle internal combustion engine by this invention. The figure which shows the super high efficiency 4 cycle internal combustion engine by this invention.

1 is a combustion chamber, 2 is an exhaust valve, 4 is an exhaust camshaft, 5 is a cam, 3 is a rocker arm, 6 is an exhaust passage, 7 is a catalyst, 8 is an intake valve, 9 is an intake passage, 10 is an intake throttle valve, 11 is an actuator, 12 is a fuel injection valve, 13 and 14 are sprockets, 15, 16 and 32 are valve opening / closing timing control devices, 17 is a housing, 18 is a rotor, 19 is an advance chamber, 20 is a retard chamber, and 21 is spark plugs, 22 ECU, 23 is the hydraulic control valve, 24 is a plunger, 25 is an electromagnet, 26 spool valve, 27 a spring, 28 is electrically nonconductive plate, the spark gap _{29, G 1 · G 2 ·} G _{3-G 4} is the spark gap, 30 is a heat insulating portion, the second intake valve 31, 32 is a valve timing control apparatus, 33 a plunger, 34, 35 is an electromagnet, 36-37 spring, 38 the driver, 39 is the second intake valve, 40 is the exhaust A valve, 41 is a combustion chamber, 42 is an intake valve, and S is a squish section. Reference numeral 2 'denotes a second exhaust valve.

Claims (5)

In a 4-cycle internal combustion engine having an intake valve driven by a cam provided on an intake cam shaft and an exhaust valve driven by a cam provided on an exhaust cam shaft, the exhaust valve is provided in a combustion chamber, A squish part having a minute gap is formed between the piston top surface and the cylinder head wall surface at the top dead center position in the periphery to make the combustion chamber a concentrated combustion chamber, and two or more spark gaps are made to face this combustion chamber. In addition, the exhaust valve is controlled in the premixed compression ignition combustion region by a valve opening / closing timing control device that controls the ignition timing of the spark gap to be at or above the compression top dead center and further varies the opening / closing timing of the exhaust valve. The closing timing of the engine is delayed from the top dead center, the exhaust gas is re-inhaled into the cylinder, and the opening timing of the exhaust valve is controlled in accordance with the engine load to make the effective expansion ratio larger than the effective compression ratio. The intake valve is provided in the combustion chamber, and the valve opening / closing timing control device that varies the opening / closing timing of the intake valve is effective by accelerating the closing timing of the intake valve in the premixed compression ignition combustion region. A four-cycle internal combustion engine which is controlled to increase the compression ratio and thus switches between premixed compression ignition combustion and spark ignition combustion according to operating conditions such as engine load and rotation speed. The four-stroke internal combustion engine according to claim 1, further comprising a second intake valve facing the squish portion. The 4-cycle internal combustion engine according to claim 1 or 2, further comprising a second exhaust valve facing the squish portion. In a 4-cycle internal combustion engine having an intake valve driven by a cam provided on an intake cam shaft and an exhaust valve driven by a cam provided on an exhaust cam shaft, the exhaust valve is provided in a combustion chamber, A squish part having a minute gap is formed between the piston top surface and the cylinder head wall surface at the top dead center position in the periphery to make the combustion chamber a concentrated combustion chamber, and two or more spark gaps are made to face this combustion chamber. In addition, the ignition timing of the spark gap is controlled to be at or above the compression top dead center, and further, the valve opening / closing timing control device that varies the opening / closing timing of the exhaust valve, The valve closing timing is delayed from the top dead center, the exhaust gas is re-inhaled into the cylinder, the opening timing of the exhaust valve is controlled according to the engine load, and the effective expansion ratio is larger than the effective compression ratio. The intake valve is provided in the combustion chamber and the opening and closing timing of the intake valve is fixed to obtain a fixed timing. Thus, premixed compression ignition combustion and spark ignition are performed according to operating conditions such as engine load and rotation speed. A four-cycle internal combustion engine characterized by switching between combustion. In a 4-cycle internal combustion engine having an intake valve driven by a cam provided on an intake cam shaft and an exhaust valve driven by a cam provided on an exhaust cam shaft, the exhaust valve is provided in a combustion chamber, A squish part having a minute gap is formed between the piston top surface and the cylinder head wall surface at the top dead center position in the periphery to make the combustion chamber a concentrated combustion chamber, and two or more spark gaps are made to face this combustion chamber. In addition, the exhaust valve is controlled in the premixed compression ignition combustion region by a valve opening / closing timing control device that controls the ignition timing of the spark gap to be at or above the compression top dead center and further varies the opening / closing timing of the exhaust valve. The closing timing of the engine is delayed from the top dead center, the exhaust gas is re-inhaled into the cylinder, and the opening timing of the exhaust valve is controlled in accordance with the engine load to make the effective expansion ratio larger than the effective compression ratio. And the intake valve faces the squish section, thus switching between premixed compression ignition combustion and spark ignition combustion according to operating conditions such as engine load and rotational speed. Cycle internal combustion engine.

Images