JPS58214619A - Internal-combustion engine with supercharger - Google Patents

Abstract

PURPOSE:To prevent counter-flow of suction air into the suction path in such a manner that a suction block valve will close the suction path from the time when the supercharge path will start to open. CONSTITUTION:A suction block valve 7 is driven with reduced speed to half of the engine output to close a suction path 5 in the way of suction process. A supercharge suction path 18 will start to open from the time when the suction path 5 is closed by a suction block valve 7 to pressure supple the suction air from an exhaust turbo supercharger 13 into an operating chamber 4. A lead valve 21 may be replaced with the suction block valve 7.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a supercharged internal combustion engine equipped with a supercharger to increase the torque and output of the engine.

An object of the present invention is to provide a sufficient supercharging effect (increase in engine torque and output) even if the discharge flow rate of the supercharger is small.

The present invention will be explained below with reference to the drawings.

FIG. 1 shows an embodiment of a supercharged internal combustion engine according to the present invention, which is equipped with an exhaust turbo supercharger 13 driven by exhaust gas energy.

14 is a compressor wheel, 15 is a turbine wheel, 16 is an intake circulation valve that circulates compressed air from the discharge side to the intake side (this is provided if necessary), and 17 is an exhaust gas that prevents the boost pressure from becoming excessive. It is a bypass valve.

The intake air controlled by the supercharging throttle valve 11 mechanically interlocked with the throttle valve 10 of the gas generator 9 reaches the exhaust turbo supercharger 13 via the suction side supercharging intake passage 12, where it is compressed. Further, it passes through the discharge side supercharging intake passage 18 to the working chamber 4 (intake air
(a space where compression, combustion of fuel, expansion and exhaust of combustion gas are performed).

The intake cutoff valve 7 is driven at a speed of 1/2 of the rotation of the engine output shaft, and closes the intake passage 5 during the intake process (meaning the time during which intake air continues to flow into the working chamber 4). A closing portion 8 formed in the intake cutoff valve 7 closes the intake passage 5), and from around the time when the intake passage 5 is closed by the intake cutoff valve 7, the intake cutoff valve 7 closes the discharge side supercharging intake passage 18. begins to open (that is, another closing portion 20 formed in the intake cutoff valve 7 begins to open the discharge side supercharging intake passage 18), and the intake air pressure-fed by the exhaust turbo supercharger 13 is transferred to the working chamber 4. (The discharge side supercharging intake passage 18, the closing portion 20, etc. are shown with chain double-dashed lines because they are formed in front of the illustrated cross section).

That is, supercharging is performed by pressurizing the intake air from the exhaust turbo supercharger 13 into the working chamber 4 in addition to the intake air drawn into the working chamber 4 from the intake passage 5 up to the middle of the intake process. be.

(In order to make the drawing easier to understand, a cross section of the intake passage 5 near the intake shutoff valve 7 is shown in FIG. 2.) As a result, the discharge flow rate of the exhaust turbo supercharger 13 can be reduced, so that the turbine nozzle By reducing the cross-sectional area, it is possible to increase exhaust energy utilization and increase the engine's low-speed torque.

Further, since the discharge flow rate of the exhaust turbo supercharger 13 is small, it can be made smaller and lighter, and the responsiveness of the engine (rate of increase in torque with respect to time) can be improved.

Furthermore, when a pump (supercharger) driven by the engine output shaft is used as a supercharger, the discharge flow rate of this supercharger can be small, and as a result, a sufficient supercharging effect can be obtained. As a result, the turbocharger can be made smaller and lighter, and its drive horsepower loss can be reduced.

As described above, according to the present invention, a sufficient supercharging effect can be obtained even if the discharge flow rate of the supercharger is small. 6 is the connection part between the operating amount 4 and the intake passage 5, and 19 is the operating chamber. 4 and the discharge side supercharging intake passage 18, and the intake cutoff valve 7 is connected to the connection part 6.
, 19 is provided upstream.

In addition, the intake cutoff valve 7 closes the intake passage 5 during the period from the time when the discharge side supercharging intake passage 18 is opened until the time when the connection part 6 is closed by the side surface of the rotary piston 1, and the working chamber is closed. It is necessary to prevent backflow of intake air from 4.

Next, if the intake cutoff valve 7 closes the intake passage 5 during the intake stroke, and the supercharging throttle valve 11 is closed (fully opened) at least when the engine is under low load, the intake cutoff valve 7 closes the intake passage 5. After 7 closes the intake passage 5, no intake air is drawn into the working chamber 4, so the intake stroke is effectively short-term.If the same weight of intake air is to be drawn into the working chamber 4, the intake air must be throttled by the throttle valve 10. Good results can be obtained even if the degree of (This is desirable.)

That is, intake resistance loss can be significantly reduced.

Fig. 3 shows a PV diagram (pressure-volume diagram) of such an internal combustion engine.
It will be understood that when the engine is under load, the intake cutoff valve 7 closes the intake passage 5 at the VC point, thereby significantly reducing the intake resistance loss of the engine.

Point P0 indicates atmospheric pressure.

In Fig. 1, the intake passage 5 and the discharge side supercharging intake passage 18 are shown.
4 independently communicate with the working chamber 4, but FIG. 4 shows an embodiment in which they communicate with the working chamber 4 after merging with each other.

In FIG. 4, reference numeral 6 denotes a connecting portion between the working chamber 4 and the intake passage 5, and at the same time, a connecting portion between the working chamber 4 and the discharge side supercharging intake passage 18.

In the embodiment shown in FIG. 5, the intake cutoff valve 7 starts opening the discharge-side supercharging intake passage 18 in the middle of the intake process so as to add the intake air drawn into the working chamber 4 from the intake passage 5. The intake air supplied from the supercharger is pressurized into the working chamber 4 to perform supercharging.

In this case, near the time when the intake cutoff valve 7 starts to open the discharge side supercharging intake passage 18, the intake air filled in the working chamber 4 flows back into the intake passage 5, so that the intake air on the upstream side of the connection part 6 A reed 21 is provided at a predetermined position in the passage 5 to prevent this (this reed valve 21 is a backflow prevention device, and in the case of FIG. be). FIG. 6 shows the application of the present invention to a reciprocating piston type internal combustion engine, in which the connection part 25 (intake valve seat part) between the intake passage 5 and the working chamber 22 and the connection part 25 (intake valve seat part) between the discharge side supercharging intake passage 18 and the working chamber 22 are shown. An intake cutoff valve 7 provided upstream of the connecting portion 24 (intake valve seat) closes the intake passage 5 in the middle of the intake process, and closes the discharge side supercharging intake passage 18 from near this closing time. When the exhaust turbo supercharger 13 starts to open, the intake air fed under pressure from the exhaust turbo supercharger 13 is pressurized into the working chamber 22 to perform supercharging.

Furthermore, FIG. 7 shows an embodiment in which the intake passage 5 and the discharge side supercharging intake passage 18 are communicated with the working chamber 22 after merging with each other.

In FIG. 7, 26 is an intake valve, 27 is a pressure relief passage,
The intake cutoff valve 7 is opened for a certain period of time from immediately after the intake valve 26 closes until just before it starts to open again, and when the supercharging effect appears, the pressure between the intake cutoff valve 7 and the intake valve 26 is reduced to the intake passage. 5 (intake passage 5 on the upstream side of the intake cutoff valve 7
(to be formed as necessary).

Thereby, it is possible to prevent intake air from passing through when the intake valve 26 and the exhaust valve 23 overlap.

In this case, the intake cutoff valve 7 provided in the intake passage 5 is
By closing the intake passage 5 near the time when the discharge-side supercharging intake passage 18 starts to open, the backflow of intake air from the working chamber 22 is prevented, so it acts as a backflow prevention device. An example using a reed valve is shown in FIG.

That is, in FIG. 8, the intake passage 5 bypasses the intake cutoff valve 7 (passes above or below the intake cutoff valve 7) and communicates with the working chamber 22, as described above. A reed valve 28 is provided.

In the embodiment shown in FIG. 9, the intake passage 5 is branched into intake passages 5' and 5'' just before the intake cutoff valve 7, and the intake passage 5' is first separated by the intake cutoff valve 7 in the middle of the intake stroke (e.g. , the output shaft angle is 80° from the top dead center position), and then the intake passage 5'' is closed from near this closing point.
begins to open, and the intake passage 5 is further closed by the intake cutoff valve 7.
'' is closed in the middle of the intake process (for example, at a position 10 degrees before bottom dead center in terms of period output shaft angle), the discharge side supercharging intake passage 18 is opened near this closing time, and the m exhaust turbo supercharger 13 is pressurized into the working chamber 22 to perform supercharging.

In this case, when the engine is under low (medium) load, the discharge side supercharging intake passage 18 and the intake passage 5'' are each closed by a closing valve 2 as shown in the figure.
9 and 30, the intake resistance loss can be significantly reduced as explained in FIG. (At this time, it is preferable to open and close the closing valves 29 and 30 by mechanically interlocking them with the throttle valve of the carburetor.)

The intake cutoff valve 7 functions as a backflow prevention device in the intake passage 5'5'' as described above when the supercharging effect appears, but in particular, the reed valve acts as a backflow prevention device in the intake passage 5''. An example using this is shown in FIG.

That is, in FIG. 10, the intake passage 5'' bypasses the intake cutoff valve 7 and communicates with the working chamber 22.
is a reed valve that prevents intake air from flowing back into the intake passage 5'' when the supercharging effect appears.

Next, the present invention is similarly applicable to diesel engines.

Consider replacing the spark plug with a fuel injection valve and removing the carburetor, and in this case, when the engine is under low (medium) load, the discharge side (
(or suction side) It is desirable to close the supercharging intake passage, and this will be explained in FIG.

That is, in FIG. 6 (considering a direct injection diesel engine), the discharge side supercharging intake passage 18 is closed by the closing valve (see FIG. 9) when the engine is under low (medium) load.

As a result, when the engine is under low (medium) load, after the intake cutoff valve 7 closes the intake passage 5 in the middle of the intake stroke, no intake air is drawn into the working chamber 22, so the compression ratio is effectively reduced to a low compression ratio. (For example, about 14).

However, when the closing valve is fully opened (discharge side supercharging intake passage 1
8), the working chamber 22 is fully filled with intake air throughout the entire intake process, so the compression ratio remains high (for example, about 17) as before.

In this way, by opening and closing the discharge-side supercharging intake passage 18 using the closing valve, the compression ratio becomes virtually variable, resulting in the following advantages.

(1) When the closing valve is closed, the compression ratio is effectively a low compression ratio (for example, 14), so the friction loss of the engine is reduced and NOx in the exhaust gas is also reduced.

However, since the expansion ratio is the same as the compression ratio when the closing valve is fully open, the fuel efficiency of the engine is greatly improved.

(2) If the closing valve is opened when the engine is started and warmed up, the compression ratio will effectively become a high compression ratio, improving the engine startability and warm-up characteristics (in this case, the engine It is best to gradually close the shutoff valve as the engine warms up.)

Since the present invention is configured as described above, a sufficient supercharging effect can be obtained even if the discharge flow rate of the supercharger is small.

[Brief explanation of the drawing]

Figures 1, 4, and 5 are cross-sectional views of a supercharged internal combustion engine according to the present invention, Figure 2 is a cross-sectional view of the intake passage near the intake shutoff valve, Figure 3 is a PV diagram, and Figures 6 and 5 are cross-sectional views of the intake passage near the intake shutoff valve. Figures 7, 8, 9, and 10 are diagrams (schematically drawn plan views) of an internal combustion engine with a supercharger according to the present invention.
It is. 1 is rotary piston, 2 is rotor housing, 3 is side housing, 4.22 is working chamber, 5.5'.5''
is an intake passage, 6, 19, 24, and 25 are connection parts, 7 is an intake cutoff valve, 8 and 20 are closing parts, 9 is a carburetor, 10 is a throttle valve,
11 is a supercharging throttle valve, 12 is a suction side supercharging intake passage, 13 is an exhaust turbo supercharger, 14 is a compressor wheel, 15
is a turbine wheel, 16 is an intake circulation valve, 17 is an exhaust bypass valve, 18 is a discharge side supercharging intake passage, 21 and 28 are reed valves, 23 is an exhaust valve, 26 is an intake valve, 27 is a pressure relief passage, 29. 36 is a closing valve. Patent applicant Osamu Kitamura■

Claims (4)

[Claims] (1) In an internal combustion engine having an intake passage and a discharge side supercharged intake passage connected to a supercharger, the discharge side supercharged intake passage is opened from the middle of the intake process by an intake cutoff valve, and the intake cutoff valve is provided at a predetermined position in the discharge-side supercharging intake passage upstream of the contact part with the working chamber of the engine, and is added to the intake air sucked into the working chamber of the engine from the intake passage by the supercharger. Pressure-fed intake air is pressurized into the working chamber of the engine to perform supercharging, and the intake passage is further closed by a backflow prevention device from around the time when the intake cutoff valve begins to open the discharge side supercharging intake passage, An internal combustion engine with a supercharger, characterized in that the backflow prevention device is provided at a predetermined position in the intake passage upstream of the connection part with the working chamber of the engine. (2) The supercharged internal combustion engine according to claim 1, wherein the backflow prevention device is an intake cutoff valve. (3) The supercharged internal combustion engine according to claim 1, wherein the backflow prevention device is a reed valve. (4) The intake passage is closed from the middle of the intake stroke by the intake cutoff valve, and the discharge side supercharging intake passage is closed at least during low load after the end of the warm-up period. Internal combustion engine with a supercharger as described in .