JPS63239312A - Engine with supercharger - Google Patents

Abstract

PURPOSE:To keep ability of anti-knocking in a good contition and improve heat efficiency as well, by setting a geometrical compression ratio of an engine with a supercharger larger and also an intake valve closing timing to a specific angle more delayed than those of conventional ones. CONSTITUTION:The intake passage 7 of a multiple-cylinder engine is composed of an independent intake passage 8 connected to the intake port 3 of each cylinder 2, a surge tank 9 connected to the upstream of this passage 8 and a common-intake passage 10 connected to the upstream of the surge tank 9 and a mechanical supercharger 14 is provided in the common-intake passage 10. Each fuel injection valve 17 is provided in each independent intake passage 8 and a throttle control valve 18 is arranged on its upstream side. In this type of an engine, a geometrical compression ratio of the engine is set higher than 8.5 and also an intake-valve closing timing defined by the time when the intake valve 3 closes to the position where a quantity of valve lift is 1mm is set to the timing which is delayed by more than 50 degrees in a crank angle from a bottom dead point.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a supercharged engine having a high geometric compression ratio.

(Prior art) Various engines have been known in which intake air is supercharged by a supercharger in order to increase the intake air filling amount of the engine (see, for example, Japanese Utility Model Application Publication No. 171630/1983). Known examples include a turbo supercharger driven by exhaust gas and a mechanical supercharger driven by an engine output shaft.

By the way, in conventional supercharged engines, the geometric compression ratio of the engine was set to a relatively low value of 8.5 or less, as knocking is more likely to occur in the high supercharging region when the compression ratio is increased. However, lowering the compression ratio tends to reduce engine cycle efficiency. In addition, in a supercharged engine, it is necessary to ensure the reliability of the exhaust system by suppressing the excessive rise in exhaust temperature during high supercharging, and for this reason, conventionally the air-fuel ratio was made rich at high speeds and high loads. Although this was done to lower the exhaust temperature, this would result in more fuel being supplied than the amount required for output.

Due to these circumstances, the fuel efficiency of conventional supercharged engines has not been sufficiently improved, resulting in high fuel consumption, especially in high-speed, high-load ranges, and countermeasures have been required to address these issues.

(Object of the Invention) In view of the above circumstances, the present invention provides a supercharged engine that can improve thermal efficiency and significantly improve fuel efficiency.

(Structure of the Invention) The first invention is an engine equipped with a supercharger, in which the geometric compression ratio of the engine is set to a high compression ratio of 8.5 or more, and the intake valve has a valve lift of 1 lau*. The intake valve closing timing, which is defined as the time when the intake valve closes to the position , is set to a time delayed by 506 eQ or more in terms of crank angle from the bottom dead center.

In other words, in this invention, the geometric compression ratio is made larger than that of a conventional supercharged engine, while the intake valve closing timing is made later than that of a conventional supercharged engine. By increasing the expansion ratio while suppressing the effective compression ratio appropriately, it is possible to maintain good knock resistance, lower exhaust gas temperature, and increase thermal efficiency, making it possible to improve fuel efficiency.

Further, the second invention provides an engine equipped with a supercharger, in which the geometric compression ratio of the engine is set to a high compression ratio of 8.5 or more, and when defined as the point in time when the valve lift amount is 1 am. , the intake valve closing timing Y (degABDc) expressed in crank angle from bottom dead center and the opening overlap period X (degABDc) of the intake and exhaust valves expressed in crank angle
) are set to satisfy the relationship Y≧−1, 75X+10.

In other words, in this invention, while the above effect can be obtained by delaying the intake valve closing timing, the above-mentioned opening can also be achieved by increasing the valve opening overlap period of the intake and exhaust valves in the supercharging region where the supercharging pressure exceeds the exhaust pressure. The scavenging effect during the valve overlap period improves knock resistance and lowers the exhaust temperature, resulting in both the effect of delaying the intake valve closing timing and the effect of increasing the valve opening overlap amount. Focusing on the fact that the two can complement each other, the relationship between the two is set as described above, and this configuration also improves fuel efficiency.

In addition, since the definition of the opening/closing timing of intake valves and exhaust valves is generally not unified, in the configurations of each of the above inventions, taking into consideration the timing when effective intake and exhaust are performed, the rIa closing timing is determined at the point when the valve lift reaches 11ag. is defined. Hereinafter, when the term "intake valve closing timing" or "valve opening overlap l" is simply used in the specification, it means that it follows the above definition. Moreover, the geometric compression ratio refers to the ratio of the volume of the cylinder at the piston bottom dead center to the gap volume (volume at the top dead center).

(Embodiment) FIG. 1 shows a first embodiment of the present invention, and in this figure,
Reference numeral 1 denotes an engine, in which an intake port 3 and an exhaust boat 4 are opened in the combustion chamber of each cylinder 2, and each boat 3.4 has an intake valve that is opened and closed by a valve mechanism (not shown). 5 and an exhaust valve 6 are equipped.

An intake passage 7 is connected to the intake boat 3 of each cylinder 2. This intake passage 7 is connected to an independent intake passage 8 whose lower 8I end communicates with the intake port 3 of each cylinder 2, a surge tongue 9 connected to the upstream end of each independent intake passage 8, and the upstream side of this surge tank. The upstream end of the common intake passage 10 is connected to an air cleaner 11.

The common intake passage 10 is provided with an air flow meter 12 that detects the intake air amount, a throttle valve 13 that adjusts the intake air, and a supercharger 14 that supercharges the intake air. This supercharged I! In this embodiment, 114 is formed by a mechanical supercharger such as a Roots type supercharger driven by the engine, and is connected to an engine output shaft (not shown) via an electromagnetic latch or the like. Further, the areas immediately upstream and downstream of the supercharger 14 in the common intake passage 10 are communicated by a bypass intake passage 15, and a bypass valve 16 for opening and closing the bypass intake passage 15 is provided in the middle of the bypass intake passage 15. It is provided.

The above Taki I! ! Each of the independent intake passages 8 communicating with the intake port 3 of the l12 is provided with a fuel injection valve 17 for injecting and supplying fuel, and upstream of the fuel injection valve 17, a throttle control is provided to throttle and close the independent intake passage 8 by 1 flll. Valve 1
8 are arranged. Each throttle control valve 18 is connected to an actuator 19, and is opened and closed simultaneously by this actuator 19. A rotation speed sensor 21 detects the engine rotation speed, and a sensor 2 detects the throttle opening corresponding to the engine load.
The control unit 20 receiving the signal from the throttle control valve 2 outputs a control signal to the actuator 19 to control the opening/closing operation of the throttle control valve 18 according to the operating state as described later.

In such a supercharged engine, the geometric compression ratio of the engine is set to be 8.5 or higher, whereas a conventional supercharged engine (geometric compression ratio of about 7.5 to 8.5) The compression ratio is set higher than that of the

Furthermore, in the valve lift characteristics of the intake valve 5 and exhaust valve 6 as shown in FIG. 2, the 1111rf1 timing (
1,0 and 1. C) and the opening/closing timing of the exhaust valve 6 (E
, O and E, C) are set as follows. That is, as shown in Fig. 2, let X (deg) be the opening overlap period of the intake and exhaust valves expressed in crank angle, and let the intake valve closing timing expressed in crank angle from bottom dead center (BDC) be X (deg). If Y (degABDC), the valve lift fi
When the opening/closing time of the intake and exhaust valves is defined as the time when the distance reaches 1 m, the relationship between the two is set to be Y≧−1, 75X+10 . . .■. In addition, as will be described later, in order to have the effect of increasing adiabatic expansion rather than adiabatic compression by closing the intake valve 5 late, the exhaust valve opening timing Z (degBBDC> expressed by the crank angle to bottom dead center) and the intake valve closing timing described above The relationship with Y is set so that [Y>Z].

Comparing this setting with a conventional supercharged engine,
In a conventional general supercharged engine, the intake valve close timing is 2.
0 to 40 deQABDC, and the valve opening overlap period is approximately -30 to -20 del:l, which does not satisfy the above equation 0. However, in the present invention, the intake valve closing timing Y and the valve opening overlap period are approximately -30 to -20 del:l. By making both of the periods X larger than before, or by making at least one of them larger than before, the condition of the above equation 0 is set so as to be satisfied.

In addition, when attempting to improve fuel efficiency solely through the effect of late closing of the intake valve, which will be described later, without making the valve opening overlap period particularly large, the intake valve closing timing may be set to approximately 50 deaA.
Set it to BDC or higher.

According to the above-mentioned supercharged engine, the cycle efficiency is improved by increasing the geometric compression ratio, while the effect of preventing knocking and lowering the exhaust temperature even in the high supercharging range is achieved. can get.

In other words, if the closing time W4Y of the intake valve 5 is delayed, the expansion stroke becomes larger than the compression stroke between the time when the intake valve 5 is closed and the time when the exhaust valve 6 is opened, and the effective compression ratio is lowered. The expansion ratio will be increased. Therefore, the cycle efficiency is increased by the work done in the expansion stroke corresponding to the geometric compression ratio, and by lowering the effective compression ratio, the knock resistance is improved in the high-load, high-speed range where supercharging is common. In addition, the temperature drop due to adiabatic expansion is smaller than the temperature increase due to adiabatic compression, thereby lowering the exhaust temperature.

Furthermore, when the valve opening overlap period Since the temperature inside the combustion chamber is lowered, the knock resistance is improved and the exhaust temperature is lowered.

In addition, by increasing the knock resistance, it becomes possible to increase the compression ratio of the engine, thereby increasing cycle efficiency.

In this way, delaying the intake valve closing timing and increasing the valve opening overlap period both have the effect of increasing knock resistance and lowering the exhaust temperature under high compression ratios, and both have the effect of reducing the exhaust temperature. They have a relationship that complements each other.

When this relationship is examined in terms of knock resistance, it is shown in Figure 3. In other words, Figure 3 shows the average effective pressure at the knock limit at an engine speed of 150 rpm when the geometric compression ratio is 9.4 and the intake valve m timing Y and valve opening overlap period X are varied. Pe (39/CI), and lines P1 to P4 in the figure are lines where the average effective pressure is equal pressure.In addition, in this data, the engine speed is set to isoorpm because the frequency of use is This is because it is high and suitable as a representative example.Furthermore, even if the geometric compression ratio is set to a high compression ratio other than 9.4, the tendency is the same as that shown in FIG.

As shown in this figure, when the intake valve m timing Y is fixed to a constant value and the valve opening overlap period 1Ilx is varied, when the valve opening overlap period X becomes smaller to the left of line A in the figure, the knock limit is reached. There is a tendency for the average effective pressure at the time to drop to an extremely low level, which means that knocking is more likely to occur in such a region. Therefore, it is desirable for the knock resistance that the valve opening overlap period X with respect to the intake valve closing timing Y be within the shaded area on the right side of line A. Also,
In the region to the right of JIB in the figure, the average effective pressure decreases due to intake air blow-through, so the region between IiA and 18 is desirable.

From this figure, if the above line A is determined by the relational expression between the intake valve closing WAY and the valve opening overlap period X, then Y--1,75X
+100 (X, Y defined by valve lift amount OIm) or Y--1,75X+10 (X, Y defined by valve lift!!11a*).

Therefore, if the intake valve closing timing Y and valve opening overlap period Become.

In the present invention, the valve opening overlap period IIX is set to about -2
3'? jea, the desired range of the geometric compression ratio and intake valve closing timing Y is shown in FIGS. 4 and 5.

That is, FIG. 4 shows the relationship between the geometric compression ratio on the horizontal axis, the effective compression ratio on the vertical axis, and the intake boat closing timing as a parameter. In this figure, the dashed diagonal range indicates the setting range for a conventional supercharged engine. 5. The intake boat closing timing is set to about 20 to 40 dea ABDC, and within this range an appropriate effective compression ratio can be obtained to prevent knocking and ensure combustion stability during high supercharging. On the other hand, in the present invention, when the valve opening overlap period is set as above, the desirable range of the geometric compression ratio and the intake valve closing timing Y and the corresponding range of the effective compression ratio are indicated by solid diagonal lines. It becomes an area. That is, by setting the geometric compression ratio to a high compression ratio higher than 8.5 and setting the intake valve m timing to 50 deg ABDC or more, the effective compression ratio can be made comparable to the conventional one.

Alternatively, since increasing the geometric compression ratio reduces the gap volume and improves combustion stability by reducing residual gas, the effective compression ratio can also be set lower than before.

In order to keep the effective compression ratio within the predetermined range as mentioned above, the geometric compression ratio must be adjusted so that the relationship between the geometric compression ratio and the intake valve closing timing Y falls within the shaded range in FIG. The higher the target compression ratio, the greater the delay in the intake valve closing timing.

Experimental data confirming the effects of such settings are shown in FIGS. 6(a) to 6(C).

Figures 6(a) to (C) show the fuel efficiency, intake negative pressure, and exhaust temperature under various average effective pressures for the present invention, a conventional supercharged engine, and a non-supercharged engine. This shows the data investigated in this case. In each of these figures, the solid line indicates the engine of the present invention with a geometric compression ratio of 9.4 and an intake valve closing timing of approximately 60 deA.
B.D.C.

This is when the valve opening overlap period is set to -23 dea, and the broken line is a conventional supercharged engine with a geometric compression ratio of 7.9 and an intake valve closing timing of approximately 306 eQA.
In the case of BDC, the two-dot chain line indicates a non-supercharged engine with a geometric compression ratio of 9.4 and an intake valve closing timing of approximately 30degABD.
C. Engine speed is 1500rpm
, the air-fuel ratio is set to λ-1.

As is clear from these experimental data, the supercharged engine configured as described above in the present invention has a lower fuel efficiency than both conventional supercharged engines and non-supercharged high compression ratio engines. becomes lower. Furthermore, since the intake negative pressure is reduced, it is also possible to reduce the pumping loss in the low to medium load range. This trend is also seen in other engine speed ranges. Also, exhaust 2! ! Therefore, in order to suppress the excessive rise in exhaust temperature at high speeds and high loads, it is necessary to enrich the air-fuel ratio in conventional supercharged engines. It turns out that it is not.

Note that the above data is based on the case where the intake valve closing timing is delayed, but as mentioned above, the effect of improving fuel efficiency and lowering the exhaust temperature by achieving a high compression ratio while suppressing knocking is due to the valve opening overlap. This is also possible by increasing the period X.

Furthermore, when the intake valve closing timing and valve opening overlap period are increased in this way, combustion stability tends to deteriorate somewhat in the light load and low speed range such as idling due to backflow of exhaust gas, but as shown in Figure 1. In the embodiment shown in FIG. 1, a throttle control valve 18 is provided in the independent intake passage 8 in order to correct this tendency. As shown in FIG. 7, in the light load and low rotation range, the throttle valve 18 is opened to a small degree.

As a result, when the valve opening overlap period X is set to be large, for example, an effect of suppressing the backflow of exhaust gas during the valve opening overlap period can be obtained, as shown in FIG.

That is, FIG. 8 shows the average exhaust pressure Pe, average intake pressure pb, and intake pressure Pb1 in the independent intake passage 8 when the throttle IIJtllllmU is set in the light load and low rotation range, corresponding to the valve lift characteristics of the intake and exhaust valves. Cylinder pressure Pc, throttle control valve 1
8 is not provided. In this way, in the light load and low speed range, the average intake pressure pb becomes lower than the average exhaust pressure Pe, causing exhaust gas to flow back into each independent intake passage 8, but when the throttle control valve 18 is closed,
Since the backflow of exhaust gas is stopped here, the pressure in the independent intake passage 18 and the cylinder 2 on the downstream side increases, and this pressure increase reduces the pressure difference with the exhaust pressure, so the exhaust gas is transferred from the exhaust system to the cylinder. Also, backflow of exhaust gas to the independent intake passage 8 is suppressed.

In this way, combustion stability is improved.

FIG. 9 shows a second embodiment of the invention, in which:
The intake valve closing timing Y and the valve opening overlap period The exhaust boat 33 is opened, and these boats are opened and closed by the main intake valve 34, the sub-intake valve 35, and the exhaust valve 36, respectively. As will be described later, the opening periods of the main intake valve 34 and the sub-intake valve 35 are different.

A main intake passage 38 communicating with the main intake boat 31 and a n
A sub-intake passage 39 communicating with the first intake boat 32 is formed independently from each other, and the sub-intake passage 39 is provided with a shutter valve 40 for opening and closing this passage. 41 are configured. The shutter valve 40 has a control unit 42
a rotation speed sensor 44 that detects the engine rotation speed via the actuator 43; a pressure sensor 45 that detects the pressure in the intake passage downstream of the throttle valve 47; and a throttle opening sensor 46 that detects the opening of the throttle valve 47. Detection signals from each are input.

Further, the supercharger 50 is a turbo supercharger in this embodiment, and includes a turbine 51 provided in an exhaust passage 53 and a compressor 52 provided in an intake passage 54, and is driven by exhaust gas. It is designed to supercharge the intake air. 55 is a fuel injection valve that injects fuel into the main and auxiliary intake passages 38 and 39; 56 is an intercooler that cools the supercharged air;
57 is a waste gate passage that bypasses the turbine 51 of the supercharger 50, and 58 is a waste gate pulp provided in the waste gate passage 57.

The geometric compression ratio of this engine 1 is also preset to a high compression ratio of 8.5 or more.

In addition, the main intake valve 34, the sub-intake valve 35 and the exhaust valve 3
The valve lift characteristics of No. 6 are set as shown in FIG. 10, and the auxiliary intake valve 35 has a longer open period than the main intake valve 34. When the shutter valve 40 is opened, the opening IIrfa of the ra1 intake valve 35 becomes the actual intake valve opening period of each cylinder, and the intake valve closing timing Y at this time
SJ5 and the valve opening overlap period XS are set large so as to satisfy the above-mentioned formula 0. On the other hand, when the shutter valve 40 is closed, the opening period of the main intake valve 34 becomes the actual intake valve opening period of each cylinder, and the intake valve closing timing Yp and the valve opening overlap period xp at this time
is relatively small and is set to be on the same level as before.

The shutter valve 40 is controlled by the control unit 42 so that it is opened at least in a high-speed, high-load range, and closed at a predetermined high-load time when the engine speed is low and the amount of supercharging is small. For example, as shown in FIG. 11, the shutter valve 40 is controlled to be fully open at high rotations above a predetermined rotation speed Ns (approximately 1700 rpm), and closed at the beginning of acceleration in a low rotation range below the predetermined rotation speed NS.

This control will be explained using the flowchart in FIG. 12. In this flowchart, the engine rotational speed E is read in step S1, and then, based on the determination in step S2, the engine rotational speed E is determined to be equal to or higher than the predetermined rotational speed NS. If so, open the shutter valve 40 (step 84).
. In addition, when the rotation speed is less than the predetermined rotation speed NS, based on the determination in step S3, at a predetermined time @ (for example, 2 seconds) after the start of acceleration.
The shutter valve 40 is closed when it is determined that the acceleration is at the beginning of the acceleration within the range of 1 to 2 (step S5), and the shutter valve 40 is opened otherwise.

The 131st detailed explanation of the above controls! To explain this in detail using the time chart 1, the shutter valve 40 is closed during low load when the throttle bottom opening is small even in the low rotation range, but the shutter valve 40 is closed at the beginning of acceleration when the throttle opening is large, and after that, the intake air is closed. The shutter valve 40 is gradually closed as the pressure inside the passage increases (see Actual a in FIG. 13). In this case, if the engine speed reaches the predetermined speed NS before the supercharging pressure increases sufficiently due to acceleration in the low gear, the shutter valve 40 is fully opened at that point (see the broken line in Fig. 13). .

According to the structure of this embodiment, when the shutter valve 40 is opened, intake air is supplied from both intake boats 31 and 32 to the combustion chamber, and the opening/closing timing of the -1 intake valve 35 is adjusted for each cylinder. This is the actual intake valve opening/closing timing. This results in
Although the geometric compression ratio is set higher than that of conventional engines with superchargers, the intake valve w1 timing YS, fff
By increasing the l-valve overlap artsXS, it is possible to suppress knocking and lower the exhaust temperature even in the high-load, high-speed range, as in the first embodiment. Furthermore, in medium and low load ranges, the closing timing of the intake valve is delayed, thereby reducing pumping loss.

On the other hand, at the beginning of acceleration in the low rotation range, the shutter valve 40 of the variable intake valve opening/closing timing device 41 is closed, the intake air supply from the first intake boat 32 is stopped, and the opening/closing timing of the main intake valve 34 is changed. This becomes the actual intake valve r11 timing, which effectively increases the engine output and prevents deterioration in acceleration performance. In other words, even if the load is high, if the engine speed is low, the amount of supercharging is relatively small.Especially, with the turbocharger 1150, the amount of supercharging at the beginning of acceleration is small due to a delay in response to changes in engine load (so-called turbo lag). If the intake valve closing timing and the valve opening overlap period are increased, the output may decrease due to intake air blowback, exhaust gas backflow, and the like. Therefore, when there is a low supercharging state at the beginning of acceleration, the intake valve closing timing is advanced and the valve opening overlap period is increased, which prevents intake air blowback and exhaust gas backflow and reduces effective compression. Since the ratio is increased, acceleration performance is improved.

In this embodiment as well, a mechanical supercharger driven by the engine may be used as the supercharger 50 instead of the turbocharger described above. In addition, in the structure of this embodiment, when the closing timing YS of the auxiliary intake valve 35 is set to 50 deQABDC or more, the actual intake valve closing timing is set to the closing timing YS of the auxiliary intake valve 35 (the shutter valve 40 is opened). The area and the area where the main intake valve 34 is opened (Yl) (shutter valve 40 is closed) may be set as shown in FIG. 14, especially when the above-mentioned mechanical supercharger is used. Based on such area settings, it is sufficient to set the distance to 111 m.

That is, even when the above mechanical supercharger is used, the first
In the high speed, high load range, medium and low load range (excluding idle range) shown with diagonal lines in Figure 4, the shutter valve 40 is opened to change the actual intake valve closing timing to the closing time of the sub-intake valve 35 J11.
By setting it to 1Ys, it is possible to obtain functions such as preventing knocking and lowering exhaust temperature in the high rotation and high load range, and reducing pumping loss in the medium and low load ranges. On the other hand, in a region where the engine speed is low even under load and the amount of supercharging is small, the effective compression ratio can be increased by closing the shutter valve 40 and setting the actual intake valve closing timing to the opening timing Yp of the main intake valve 34. This is advantageous for improving engine output.

Furthermore, in order to improve combustibility even in the idle region, it is desirable to set the actual intake valve closing timing to the closing timing Yp of one intake valve 34.

In addition to the intake port closing timing variable device shown in the above embodiments, for example, a valve stop mechanism that can stop the operation of the auxiliary intake valve 35 may be provided, or the intake valve drive timing may be A variable timing mechanism may be provided to vary the timing.

(Effects of the Invention) As described above, according to the present invention, it is possible to increase the geometric compression ratio of the engine to a high compression ratio while preventing knocking, thereby increasing the cycle efficiency, and without relying on enriching the air-fuel ratio. Excessive rise in exhaust gas temperature can be prevented, and these effects can improve fuel efficiency.

That is, according to the first invention, the effective compression ratio is 50 dea.
Since it is delayed by more than ABDC, the effective compression ratio is moderately lowered while increasing the geometric compression ratio, thereby preventing knocking and lowering the exhaust temperature.
Furthermore, it also has the effect of reducing pumping loss in the low and medium load range, resulting in improved fuel efficiency.

Further, according to the second invention, the intake valve closing timing Y (degΔ
TDC) and intake/exhaust valve opening overlap period X(dea
) is set to satisfy the relationship Y≧-1,75 This makes it possible to improve fuel efficiency through the interaction of increasing the valve opening overlap period and delaying the intake valve closing timing.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of the entire supercharged engine showing the first embodiment of the present invention, Fig. 2 is a diagram showing the valve lift characteristics of the intake valve and exhaust valve in this embodiment, and Fig. 3 is a diagram showing the valve lift characteristics of the intake valve and exhaust valve in this embodiment. Figure 4 shows the relationship between the intake valve closing timing and valve opening overlap period and the average material effective pressure at the knocking limit in an example. A diagram showing the relationship between compression ratio, intake valve closing timing, and effective compression ratio; FIG. 5 is a diagram showing the preferable range of the geometric compression ratio and intake valve closing timing based on the relationship shown in FIG. 4;
Figures 6(a) to (C) show experimental data comparing fuel efficiency, intake pressure, and exhaust temperature between an embodiment of the present invention and a conventional engine. Figure 8 is a diagram showing the area setting of opening/closing control, Figure 8 is a characteristic diagram showing the relationship between intake pressure and exhaust pressure in the light load range of the engine, Figure 9 is a characteristic diagram showing the relationship between intake pressure and exhaust pressure in the light load range of the engine.
The figure is a schematic diagram of the entire supercharged engine showing the second embodiment,
FIG. 10 is a diagram showing the valve lift characteristics of the intake valve and exhaust valve in the case of the second embodiment, FIG. 11 is a diagram showing the control area setting of the shutter valve in the second embodiment, and FIG.
The figure is a flowchart of the control of the shutter valve, No. 13.
The figure is a time chart of the same control, and FIG. 14 is a diagram showing another example of the area setting of the control in the second embodiment. 1...Engine, 2...Ki 113.3.34.35
-...Intake valve, 6.36...Exhaust valve, 14.50...
・Turbocharger patent applicant Mazda Co., Ltd. agent Patent attorney Etsushi Kotani
Patent Attorney Chief 1) 1 Patent Attorney Board Writer Yasuo No. 4 Figure BDC 1 Moxibustion Bow 1? On the IE circuit. Figure 5 Attack and scientific pressure ratio Figure 7 Figure 8 Crank angle 0 Senbo Kosara. Q Fig. 9 Fig. 10 Fig. 11 Engine 1tL (rP'> Fig. 12

Claims (1)

[Claims] 1. In an engine equipped with a supercharger, the geometric compression ratio of the engine is set to a high compression ratio of 8.5 or more, and the point in time when the intake valve closes to a position with a valve lift of 1 mm. A supercharged engine characterized in that the intake valve closing timing defined by the above is set to a time delayed by 50 degrees or more in terms of crank angle from bottom dead center. 2. For engines equipped with a supercharger, set the geometric compression ratio of the engine to a high compression ratio of 8.5 or higher, and define the opening/closing point of the intake and exhaust valves as the point in time when the valve lift amount is 1 mm. In this case, the intake valve closing timing Y (degABDC) expressed in crank angle from bottom dead center and the opening overlap period
g) is set to satisfy the relationship Y≧−1.75X+10.