JPS6069235A - Diesel engine with supercharger - Google Patents

Abstract

PURPOSE:To lower the specific fuel consumption of an engine, by making the expansion ratio fairly great as compared with the compression ratio at the time when an intake valve is closed. CONSTITUTION:Providing that the minimum volume and the maximum volume of a work space are Vc, Vm, respectively, and the volume of the work space at the time point when an intake valve is closed is Vs, the compression ratio epsilon(=Vs/Vc) at the time when the intake valve is closed and the expansion ratio E(=Vm/Vc) is so selected to satisfy the following relationship, E/epsilon=1.35, In case that an engine is required to produce a high torque and a high output, drop of the engine torque and output due to the large value of E/epsilon is prevented by supplying high-pressure intake air from a supercharger 2. On the other hand, at the time of partial-load operation of the engine when supercharging for the engine is not required, return passages 11, 13 are opened by valves 12, 15 so as not to produce loss of work done by the supercharger 2 for compression the intake air.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a supercharged diesel engine that improves the fuel efficiency of the engine by significantly increasing the expansion ratio relative to the compression ratio when the intake valve is closed.

In general, increasing the compression ratio of a turbocharged diesel engine is an effective means of improving fuel efficiency, but adopting a compression ratio that is too high increases engine friction loss and actually reduces fuel efficiency. There is an upper limit to this problem, as the combustion pressure and heat load become excessive as the combustion pressure increases.

The present invention aims to improve the fuel efficiency of the engine by significantly increasing the expansion ratio compared to the compression ratio when the intake valve is closed (of course, a compression ratio as high as possible is adopted). explain.

In the present invention, the minimum volume of one operating space in the engine (referring to the space in which suction, compression, expansion, and exhaust are performed formed by the cylinder, cylinder head, and piston) is Vc, the maximum volume is Vm, and the intake valve is If the volume of the same operating space at the time of closing (when multiple intake valves are provided, the time when the one that closes latest is closed) is Vs, then the compression ratio ε when the intake valve is closed is ε=Vs/Vc , the expansion ratio E is defined as E=Vm/Vc.

FIG. 1 shows an embodiment of a supercharged diesel engine according to the present invention, which includes a supercharger 2 connected to an output shaft of an engine 1 via a chain belt or the like.

The vane 6 rotates together with the rotor 3 around a vane shaft 8 provided at the center of the rotor housing 4, and an extremely small gap is left between the tip surface of the vane 6 and the inner wall surface of the rotor housing 4. .

Supply air that flows from the suction side passage 9 into the working chamber 7 (referring to the space where the volume changes in the supercharger, and in the figure, the space formed by the rotor 3, rotor housing 4, side housing 5, and vane 6) is supplied to the engine 1 via a discharge side passage 10.

Then, when focusing on one working chamber 7, the same working chamber 7
The air supply is designed to uniformly flow into the working chamber 7 from the minimum volume state to the maximum volume state (the inflow of air supply is not interrupted on the way). The on-off valves 12 and 15 are mechanically linked to an accelerator pedal or a control rack (not shown) that controls the fuel injection amount, and are used in a partial load range where there is no need to supercharge the engine (especially when the engine is idling). In extremely low load ranges (including extremely low load areas), the return passages 11 and 13 (14) are opened by the on-off valves 12 and 15 to prevent the charge air compression work loss of the supercharger 2 from occurring.

When the return passages 11, 13 (14) are closed by the on-off valves 12, 15, the engine is supercharged.

In this case, the opening 1 of the return passage 13 opens into the working chamber 7.
3' are each formed to have a shape that is closed by the tip end surface of the vane 6, for example, by making its circumferential length less than or equal to the thickness of the tip end of the vane 6. Therefore, when each opening 13' is closed by the on-off valve 15, when the vane 6 passes through each opening 13',
Adjacent operating spaces with this vane 6 as a boundary do not communicate with each other, and supply air does not flow.

Now, the intake valve (not shown) is designed to close at a point θ after the bottom dead center of the piston at the engine output shaft angle during the intake process (if multiple intake valves are provided, the intake valve closes at the latest). ).

In this case, there is the following relationship between ε, E, and θ (where λ is the ratio of the quick contact rod length to the piston stroke,
Here, λ=2).

Generally, the expansion ratio E is 13 to 23, and θ is usually about 40° to 60°. Considering the ratio of E/ε to the compression ratio ε when the intake valve is closed, the value of E/ε is 1.09. ~1.23, but the present invention is characterized in that the value of E/ε is set to 1.35 or more.

That is, if the value of E/ε is 1.35 or more, the expansion ratio E is 1.
In the range of 3 to 23, the above θ is 70° or more, and a considerable portion of the supply air once filled into the working space of the engine during the intake process flows back out of the working space of the engine (especially in the low speed range of the engine). , the torque of the engine is inevitably reduced significantly.

In the present invention, the value of E/ε is set to 1.35 or more, and when high torque and high output of the engine are required, high pressure air supply from the supercharger 2 (higher pressure air supply than before) is provided. Supply, E/
This prevents the engine's torque and output from decreasing due to the large value of ε.

That is, the on-off valves 12 and 15 are open at least in the extremely low load range, including when the engine is idling, and the air supplied from the supercharger 2 is supplied to the engine at atmospheric pressure (thereby, the supercharger There is no work loss in compression of the air supply in machine 2 (→Generally, in a turbocharged engine, the air supply is constantly pressurized above atmospheric pressure and supplied to the engine, so the fuel efficiency deteriorates considerably), this state When the accelerator pedal (not shown) is opened, the fuel injection amount increases and the engine output increases, and the on-off valves 12,1
5 is closed (fully closed), the engine is finally supercharged (the supply air pressure is higher than conventionally, that is, when the value of E/ε is smaller than 1.35). ), thus preventing an increase in the amount of fuel injection and a decrease in engine torque and output.

To give a preferred embodiment of the present invention, in a direct injection engine, for example, ε=13.5, E=20 (in this case, E/ε=1.
48 → Conventionally ε=13.5, E=16, E/ε=1.2
In an indirect injection (pre-chamber type) engine, for example, ε=16, E=24 (in this case, E/ε=1.5-→ conventionally, ε=17, E=21, E/ε = 1.23rd place).

Therefore, the expansion ratio E can be made extremely high while the compression ratio ε when the intake valve is closed is the same as the conventional one.

As described above, according to the present invention, the expansion ratio E can be made extremely high without excessively increasing the friction loss, combustion pressure, and thermal load of the engine (because ε is the same as before), and the idling state of the engine can be reduced. At least in the extremely low load range, including the supercharger, the charge air compression work loss of the supercharger is prevented from occurring (that is, the pressure on the discharge side of the supercharger is prevented from becoming positive pressure).
The fuel efficiency of the engine can be significantly improved.

The present invention enables E/ε without reducing engine torque/output.
The characteristic is that the value of E is set to 1.35 or more, but it is preferable to set the value of E/ε to 1.4 to 3.0 (E
It is undesirable to make the value of /ε too large because it increases the charge air compression work loss of the supercharger).

Generally, in a diesel engine with a supercharger, the compression ratio ε is slightly lowered when the intake valve is closed compared to a non-supercharged diesel engine in order to prevent an excessive increase in combustion pressure and thermal load.
On the other hand, it tends to deteriorate the combustion characteristics of the engine in a partial load range (particularly in an extremely low load range including idling).

Therefore, as shown in FIG. 2, it is desirable to use a throttle valve 16 to slightly throttle the supply air flowing through the suction side passage 9 at least in an extremely low load range, including when the engine is idling.

As a result, the pressure on the discharge side of the supercharger, that is, the pressure on the discharge side passage 10
The internal pressure becomes negative pressure, the amount of air charged into the working space of the engine (inside the cylinder) is restricted, the heat capacity in the working space of the engine is appropriately reduced, and the compression end temperature (engine temperature at the time of fuel injection) is reduced. (can be considered as the supply air temperature in the working space).

Therefore, the ignition delay period is shortened and the combustion pressure rises later, resulting in reduced combustion noise and complete combustion of the fuel, thus improving the combustion characteristics (generally used in diesel engines). In an engine, when the supply air is throttled, fuel consumption is supposed to worsen due to engine pump loss, but in reality, when the supply air is throttled, it has the effect of lowering the compression end pressure and reducing friction loss. There is almost no deterioration in fuel consumption).

In this case, since a strong negative pressure is generated on the discharge side (discharge side passage 10) of the supercharger, an exhaust gas introduction passage 17 having an appropriate flow rate control device 18 is formed as shown by the two-dot chain line. , the exhaust gas flowing in the exhaust passage 19 is transferred to the discharge side passage 1.
It is possible to introduce a large amount into 0.

This has the advantage of further increasing the compression end temperature (since the temperature of the exhaust gas is extremely high) and also reduces the amount of N in the exhaust gas.
Ox can be reduced.

Here, if the flow rate of the exhaust gas introduced into the discharge side passage 10 is gradually increased, the pressure inside the discharge side passage 10 will finally reach almost atmospheric pressure, but even if this is done, the compression end temperature can be maintained sufficiently. (This is not due to a decrease in the heat capacity in the working space of the engine, but rather
Limiting the amount of air supplied to the engine, that is, fresh air;
This is due to the introduction of exhaust gas).

It is preferable that the throttle valve 16 is mechanically linked to an accelerator pedal (not shown) or the like, and that the intake air is throttled by the throttle valve 16 at least in an extremely low load range, including when the engine is idling.

Next, FIG. 4 shows an embodiment in which the combustion characteristics in the partial load range of the engine (particularly in the extremely low load range including the idling state) are improved without throttling the air supply using the throttle valve 16.

That is, in FIG. 4, the suction side passage 9 is divided into a number of suction side passages 9' just before opening into the working chamber 7, and is provided with a control valve 21 for sequentially opening and closing these suction side passages 9'.

The openings 9'' of each suction side passage 9' opening into the working chamber 7 are each formed to have a shape that is closed by the tip end surface of the vane 6.

Therefore, focusing on one opening 9'', when the suction side passage 9' belonging to the opening 9'' is closed by the control valve 21, the vane 6 passes through the opening 9''. At this time, adjacent working chambers with the vane 6 as a boundary do not communicate with each other, and supply air does not pass through.

Now, considering a partial load range (particularly an extremely low load range) that includes the idling state of the engine, the control valve 21 completely closes each suction side passage 9' belonging to each opening 9'' as shown in the figure. (hereinafter referred to as the control valve 21 being fully closed), certain 1
Focusing on the two working chambers 7, the volume of the working chamber 7 is in the middle of the process from the minimum state to the maximum state (hereinafter, this point is referred to as V
By communicating the suction side passage 20 to the working chamber 7 up to point d), the supply air flows into the working chamber 7.

That is, up to the Vd point, the supply air is made to flow into the working chamber 7 so as to account for all of the supply air supplied to the engine.

After the supply air flowing into the working chamber 7 is cut off at the Vd point, the supply air in the working chamber 7 expands adiabatically (it is thought that the temperature of the supply air decreases). Therefore, it is desirable to preheat this amount using exhaust gas, cooling water, etc.)
When the pressure on the discharge side of the supercharger 2 becomes equal to the pressure (negative pressure) in the discharge side passage 10, the working chamber 7 is connected to the communication passage 2.
3, 24 to the discharge side of the supercharger 2 (discharge side passage 10)
Finally, the supply air in the working chamber 7 is discharged to the discharge side of the supercharger (in this case, each opening 9
Since each of the suction side passages 9' belonging to the
When passing through the vane 6, adjacent working chambers do not communicate with each other through the vane 6, and the supply air does not pass through, so the supply air in the working chamber 7 expands adiabatically. ).

In this way, the supply air (fresh air) that can be supplied to the engine is restricted (the density of fresh air is made lower than the atmospheric pressure).

FIG. 3 shows a PV diagram (pressure-volume diagram) of the working chamber 7 when the control valve 21 is fully closed and the communicating passages 23 and 24 are fully opened, and as is clear from the diagram. The supercharger 2 generates work, that is, power, corresponding to the shaded area, and transmits this to the engine (Po is the atmospheric pressure, Pi is the pressure on the discharge side of the supercharger 2 - (indicates negative pressure).

In this way, the supply air (fresh air) supplied to the engine is limited at least in the extremely low load range, including when the engine is idling, so the amount of supply air that is filled into the engine's working space is limited, and the engine is not operating properly. The internal heat capacity is moderately reduced.

Therefore, the compression end temperature is sufficiently increased and the ignition delay period is shortened, so that the increase in combustion pressure becomes gradual, combustion noise is reduced, complete combustion of the fuel becomes possible, and combustion characteristics are improved.

When the amount of fuel injection increases and a larger amount of air supply to the engine is required, the control valves 21 are sequentially opened, starting from a predetermined opening degree of the accelerator pedal (not shown).
The suction side passages 9' belonging to the respective openings 9'' may be sequentially opened by the control valve 21), thereby increasing the fuel injection amount and increasing the engine output.

(In this case, the control valve 12 may be linked to a control rack, control sleeve, etc. that controls the fuel injection amount.) Then, when the control valve 21 is further opened, the communication passage 23 is sequentially closed. Eventually, the engine will be supercharged (if the openings 23' are also formed to have a shape that has the moment when they are closed by the tip surfaces of the vanes 6, the vanes 6 will pass through each opening 23'). At this time, adjacent working chambers with the vane 6 as a boundary do not communicate with each other, and supply air does not pass through at all.

A PV diagram of the working chamber 7 when each communication passage 23 is closed by T degree by the control valve 21 is shown by a two-dot chain line in FIG.

Note that it is desirable to make the gap between each suction side passage 9' and the control valve 21 as small as possible to improve airtightness.
If necessary, this gap may be left slightly.

In this way, considering the extremely low load range including the idling state of the engine, even after the inflow of the supply air flowing into the working chamber 7 at the Vd point is cut off, the supply air flows into the working chamber 7 (from the gap). A small amount of supply air will flow in, but in other words, the supply air will flow into the working chamber 7 so as to account for most of the supply air supplied to the engine up to the Vd point. Even in this manner, the supercharger 2 can generate power.

Now, as mentioned above, when the control valve 21 is fully closed, a strong negative pressure is generated on the discharge side of the supercharger 2, so a large amount of exhaust gas flows into the discharge side passage 10 as described in FIG. If the exhaust gas is introduced into the exhaust gas, it is possible to further increase the compression end temperature, improve the combustion characteristics, and reduce NOx in the exhaust gas. The communication passage 23 is newly installed on the delay side to make the angle φ small, so that the timing at which the working chamber 7 from the Vd point communicates with the discharge side passage 10 via the communication passages 23 and 24 is brought forward).

Then, as the flow rate of exhaust gas introduced into the discharge side passage 10 is gradually increased, the pressure inside the discharge side passage 10 finally becomes almost atmospheric pressure, and the supercharger 2 no longer generates power. However, since no pump loss occurs in the engine at the same time, there is no adverse effect on fuel efficiency at all (in this case, the communication passage 23 is placed near the leading end 22 of the control valve 21 so that the angle ).

Also in FIG. 4, the value of E/ε is set to 1.35 or more, and the expansion ratio E is made extremely high without excessively increasing the friction loss, combustion pressure, and heat load of the engine.

In addition, at least in the extremely low load range including the idling state of the engine, the charge air compression work loss of the supercharger 2 is prevented from occurring (the pressure in the discharge side passage 10 is prevented from becoming positive pressure).

Therefore, the fuel efficiency of the engine can be significantly improved.

Furthermore, when the supply air (fresh air) supplied to the engine is restricted and the pressure in the discharge side passage 10 becomes negative pressure, power is generated in the supercharger 2, so the engine (In general, in a diesel engine, if the supply air to the engine is restricted, the fuel efficiency should worsen due to the engine pump loss, but in reality, the fuel consumption is reduced due to the reduction in compression end pressure.) This has the effect of reducing fuel consumption and improving combustion characteristics, and there is almost no deterioration in fuel efficiency.Therefore, fuel efficiency is improved by an amount equivalent to the power generated by the supercharger 2).

FIG. 5 shows an embodiment in which the leading end 22 of the control valve 21 in FIG. 4 is extended to the communication path 23 located on the most delayed side.

In the figure, the P-V diagram of the working chamber 7 when the control valve 21 is fully closed (at least in the extremely low load range including the idling state of the engine) is the same as that in Figure 3 (the solid line part), and the control valve 21 is 21 (even if the suction side passage 9' is opened by the control valve 21)
Until all the communication passages 23 are closed by the control valve 21, the supply air flowing into the working chamber 7 expands until the pressure in the discharge side passage 10 is almost equal to the pressure in the discharge side passage 10, and then the working chamber 7 closes in the communication passage. 23 and 24 to the discharge side passage 10 (of course, almost the same effect can be obtained even if the leading end 22 of the control valve 21 is reduced to about the middle of the angle φ). ).

Further, FIG. 6 shows an embodiment in which a communicating path 23 is formed in the section of angle φ in FIG. 1.

That is, in FIG. 6, when considering at least an extremely low load range including the idling state of the engine in which the control valve 21 is fully closed, the Vd
In the vicinity of the point, the working chamber 7 communicates directly with the discharge side road 10 via communication passages 23 and 24.

As is clear from Figure 7, which shows the P-V diagram of the working chamber 7, the turbocharger generates work corresponding to the shaded area, that is, power (for reference, the control A PV diagram of the working chamber 7 when the valve 21 is slightly opened is shown by a two-dot chain line).

In this case, the leading end 22 of the control valve 21 may be slightly extended toward the communication passage 23, so that the air supplied from the Vd point in the working chamber expands slightly and then enters the communication passages 23, 23.
It comes to be discharged into the discharge side passage 10 through.

Figure 8 shows a diesel engine with a supercharger according to the present invention, which uses a pump called a Repshield pump as a supercharger.
(engine not shown), the engine is operated in a partial load range (especially in an extremely low load range including idling) without throttling the supply air with a throttle valve.
The combustion characteristics of the fuel are improved.

The rotors 25 are meshed with each other without contact by synchronous gears (not shown), and the supply air flowing through the suction side passage 30 is connected to the connection part 3 between the suction side passage 30 and the rotor 25.
1 (located on the inner wall surface of the side housing 27 on the opposite side), through the communication hole 32 formed in the rotor 25, and further into the working chamber 28 via the suction side passage 33 (formed on the side housing on the front side). It seems that there is an influx into the country.

Considering at least the extremely low load range including the idling state of the engine, the closing valve 36 is fully closed or almost fully closed (usually fully closed), and when focusing on one working chamber 28, the same working chamber 28
By the point Vd in the middle of the journey from the minimum volume state to the maximum volume state (the communication hole 32 formed in the rotor 25
(by communicating with the connection part 31 up to point d), it accounts for all (when the closing valve 36 is fully closed) or most (when the closing valve 36 is slightly open) of the supply air supplied to the engine. Thus, the supply air is allowed to flow into the working chamber 28, thereby restricting the supply air (fresh air) supplied to the engine, sufficiently raising the compression end temperature, and improving the combustion characteristics.

FIG. 9 shows a P-V diagram of the working chamber 28 when the closing valve 36 is fully closed. As is clear from the figure, the supercharger 2' performs the work corresponding to the shaded area, that is, the power. This generates energy and transmits it to the engine, further improving fuel efficiency.

When the amount of fuel injection increases and a larger amount of air is required to be supplied to the engine, the closing valve 36 that is linked to the accelerator pedal etc. is opened continuously or suddenly, and a large amount of air is also removed from the suction side passage 29. The supply air may be allowed to flow into the working chamber 28.

34 indicates a reed valve.

Note that when the closing valve 36 is fully closed or slightly opened, a strong negative pressure is generated in the discharge side passage 35, so that a large amount of exhaust gas can be introduced as described above.

FIG. 10 shows a partial load range of the engine (the engine is not throttled) in a turbocharged diesel engine (engine not shown) according to the present invention using a screw pump as a supercharger, without throttling the supply air with a throttle valve.
It is designed to improve combustion characteristics, especially in extremely low load ranges (including idling).

That is, in FIG. 10, the slide valve 43 is configured to open (slide from the front side to the opposite side) from a predetermined opening degree of the accelerator pedal, and opens to the working chamber 41 of the suction side passage 42 by opening and closing the slide valve 43. The effective cross-sectional area of the opening (located on the inner wall surface of the rotor housing 39) changes, and the timing at which communication between the opening and the working chamber 41 is cut off changes.

At least in the extremely low load range, including when the engine is idling, the opening of the suction side passage 42 that opens into the working chamber 41 already has a certain effective cross-sectional area, and therefore only one working chamber 41
Paying attention to , the supply air flows into the working chamber 41 from the suction side passage 42 and its opening until the communication between the working chamber 41 and the opening is cut off (corresponding to the Vd); From the point Vd, the supply air in the working chamber 41 expands adiabatically, and when the pressure becomes almost equal to the pressure in the discharge side passage 44, the working chamber 41 flows through the communication passage 45 into the discharge side passage 44. It seems to be connected to.

In this way, the supply air (fresh air) supplied to the engine is restricted to sufficiently raise the compression end temperature and improve combustion characteristics.

In this case, the PV diagram of the working chamber 41 is similar to that in FIG. 3 (solid line portion), and the power generated in the supercharger is transmitted to the engine, further improving fuel efficiency.

If a larger amount of supply air is required to be supplied to the engine, the slide valve 43 is opened continuously or suddenly, and when the pressure in the discharge side passage 44 reaches almost atmospheric pressure, the rotary valve 46 is opened. This closes the passage 45.

It goes without saying that the value of E/ε is set to 1.35 or more to significantly improve the fuel efficiency of the engine.

As described above, the present invention increases the expansion ratio without excessively increasing the engine's friction loss, combustion pressure, and heat load, and at least in the extremely low load range including the idling state of the engine, the charge air compression work of the supercharger is achieved. Since loss is prevented from occurring (pressure on the discharge side of the supercharger does not become positive pressure), the fuel efficiency of the engine can be significantly improved.

[Brief explanation of drawings]

Figures 1 and 4 are sectional views of a diesel engine with a supercharger according to the present invention, Figures 2, 5, and 6 are views of a diesel engine with a turbocharger according to the present invention (the engine is omitted), and Figures 3, 7, and 9. The figure is a PV diagram, and Figures 8 and 10 are sectional views (the engine is omitted) of a supercharged diesel engine according to the present invention. 1 is the engine, 2.2' is the supercharger, 3.25.37.38 is the rotor, 4.26.39 is the rotor housing, 5.
27.40 is the side housing, 6 is the vane, 7.28
・41 is the working chamber, 8 is the vane shaft, 9, 9', 20, 29
・30, 33, 42 are suction side passages, 10, 35, 44 are discharge side passages, 11, 13, 14 are return passages, 12, 15
1 is an on-off valve, 16 is a throttle valve, 17 is an exhaust gas introduction passage, 18 is a flow rate control device, 19 is an exhaust passage, 21 is a control valve, 22 is a leading end, 23, 24, and 45 are communication passages, 31 is a connection part, 3
2 is a communication hole, 34 is a reed valve, 36 is a closing valve, 43 is a slide valve, 46 is a rotary valve, and 9'', 13', and 23' are openings. Patent applicant Shuichi Kitamura

Claims (9)

[Claims] (1) In a diesel engine equipped with a supercharger connected to the output shaft of the engine, the intake air from the time when the latest intake valve of at least one intake valve is closed after the bottom dead center of the piston. If the compression ratio when the valve is closed is ε, and the expansion ratio is E relative to this ε, then the configuration is such that the value of E/ε is 1.35 or more, and at least in the extremely low load range including the idling state of the engine. A diesel engine with a supercharger, characterized in that the pressure on the discharge side of the supercharger does not become positive pressure. (2) The supercharged diesel engine according to claim 1, wherein the value of E/ε is 1.4 to 3.0. (3) Focusing on one working chamber in which the supercharger is located, supply air is uniformly flowed into the working chamber from the minimum volume state to the maximum volume state, and the configuration is as described above. A supercharged diesel engine according to claim 1 or 2, comprising a supercharger. (4) The supercharged diesel engine according to claim 3, wherein the air supply flowing into the working chamber is throttled by a throttle valve at least in an extremely low load range including when the engine is idling. (5) A diesel engine with a supercharger according to claim 4, wherein exhaust gas is introduced into the discharge side of the supercharger at least in an extremely low load range including when the engine is idling. (6) Focusing on one working chamber in which the supercharger is located, all or most of the air supplied to the engine is supplied to the engine up to point Vd in the middle of the process from the minimum volume state to the maximum volume state of the working chamber. The supply air is allowed to flow into the same working chamber until the Vd point is reached, thereby restricting the fresh air supplied to the engine and reducing the amount of air on the discharge side of the supercharger. The pressure of the engine is prevented from becoming positive pressure, and when more air supply to the engine is required, the air supply is further supplied to the engine through the same working chamber. A supercharged diesel engine according to claim 1 or 2, comprising a feeder. (7) Make sure that the pressure in the working chamber just before point Va is sufficiently higher than the pressure on the discharge side of the supercharger, thereby restricting the fresh air supplied to the engine and 7. A diesel engine with a supercharger according to claim 6, wherein the pressure of the supercharger becomes negative pressure, thereby causing the supercharger to generate power. (8) A diesel engine with a supercharger according to claim 7, wherein exhaust gas is introduced into the discharge side of the supercharger. (9) Exhaust gas is introduced to the discharge side of the supercharger so that the pressure in the working chamber just before the Vd point is almost equal to the pressure on the discharge side of the supercharger, and thereby fresh air is supplied to the engine. 7. A diesel engine with a supercharger according to claim 6, wherein the pressure on the discharge side of the supercharger is prevented from becoming positive pressure by limiting the pressure on the discharge side of the supercharger.