JPS6124526B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel-injected active thermal atmosphere combustion internal combustion engine.

As a two-stroke internal combustion engine with a carburetor that can significantly reduce fuel consumption and harmful components in exhaust gas and provide quiet operation, the cross-sectional area of the scavenging passage that connects the engine crank chamber and combustion chamber has been reduced to the crank chamber. By squeezing on the near side, fresh air flows into the combustion chamber at a low speed, creating an active heat atmosphere within the combustion chamber, and then maintaining this atmosphere continuously during the compression stroke to ignite the fresh air at the end of the compression stroke. The present inventor has already proposed a two-stroke engine in which ignition and combustion occur without using a plug.

The present invention performs active thermal atmosphere combustion as described above in a fuel-injected internal combustion engine, thereby greatly reducing fuel consumption and harmful components in exhaust gas. It is an object of the present invention to provide a fuel injection type internal combustion engine that provides smooth operation.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 and FIG. 2 show a case where the present invention is applied to a loop scavenging type two-stroke internal combustion engine. It goes without saying that the present invention can also be applied to other types of internal combustion engines, such as a uniflow two-stroke internal combustion engine equipped with an exhaust valve. 1 and 2, 1 is a crank case, 2 is a cylinder block fixed on the crank case 1, 3 is a cylinder head fixed on the cylinder block 2,
A piston 4 has a substantially flat top surface and can reciprocate within a cylinder liner 5 fitted into the cylinder block 2, a combustion chamber 6 formed between the cylinder head 3 and the piston 4, and a combustion chamber 7. A fuel injection valve is arranged at the top of the chamber 6, 8 is a crank chamber formed in the crank case 1, 9 is a balance weight,
10 is a connecting rod, 11 is a plurality of scavenging holes formed in the cylinder liner 5, 12 is a plurality of exhaust holes formed in the cylinder liner 5, 13 is an exhaust passage, 1
Reference numeral 4 indicates an intake passage for introducing air into the crank chamber 8, 15 indicates a reed valve that allows flow only from the intake passage 14 into the crank chamber 8, and 16 indicates an engine-driven fuel injection pump. The injection pump 16 is connected to the fuel injection valve 7 via a fuel line 17 . A scavenging passage 19 opening into the crank chamber at an opening 18 is formed in the lower end of the cylinder block 2, and this scavenging passage 19 is connected to the scavenging hole 11 via a branched scavenging passage branch 20. A scavenging control valve 21 is arranged in the scavenging passage 19 near the opening 18, and the valve shaft 2 of this scavenging control valve 21
The tip of an arm 23 fixed to the vehicle 2 is connected to an accelerator pedal 25 via a wire 24. The relationship between the opening amount of the scavenging control valve 21 and the depression amount of the accelerator pedal 25 will be described later. The effective compression ratio of the two-stroke internal combustion engine shown in Figure 1 is from 14 to
It is set between 16.

FIG. 3 is a diagram showing the opening period of the scavenging hole 11 and the exhaust hole 12. In Figure 3, EC is exhaust hole 1
SO indicates the opening timing of the scavenging hole 11, SC indicates the closing timing of the scavenging hole 11, and EC indicates the closing timing of the exhaust hole 12. The opening and closing timings of the scavenging and exhaust holes are the same as in conventional two-stroke engines.

FIG. 4 shows a side sectional view of the fuel injection pump 16 of FIG. Referring to FIG. 4, 30 is a housing, 31 is a cylinder liner, 32 is a fuel reservoir,
33 is a controller sleeve that is rotatable within the housing 30; 34 is a plunger that is slidably inserted into the cylinder liner 31 and extends through the controller sleeve 33; and 35 is a plunger that is driven by the engine and is connected to the engine's crankshaft. 36 is a plunger seat, and 37 is a retainer that presses the enlarged lower end of the plunger 34 onto the plunger seat 36 by the spring force of a compression spring 38. The opposing peripheral wall of the lower half of the plunger 34 is a flat surface 39
On the other hand, the inner peripheral surface of the controller sleeve 33 facing this flat surface 39 is also formed from a flat surface 40 . Therefore, the controller sleeve 33
When the plunger 34 rotates, the plunger 34 simultaneously rotates about its axis. A thread 41 is threaded onto the upper outer circumferential wall surface of the controller sleeve 33, and a rack 42 that is threadedly engaged with the thread 41 is attached to the housing 30.
is slidably disposed within. The end of this rack 42 is connected to the accelerator pedal 25 as shown in FIG.
Therefore, when the accelerator pedal 25 is depressed, the controller sleeve 33 rotates. The cylinder liner 31 has a cylinder chamber 4
A combustion supply port 44 is formed that opens into 3;
On the other hand, the cylinder chamber 43 is connected to the fuel injection valve 7 via a fuel discharge port 46, a pressure regulating valve (not shown), and a fuel conduit 17.

FIG. 5 shows a perspective view of the head of the plunger 34 shown in FIG. 4. Referring to FIGS. 4 and 5, a pair of grooves 47, 48 are formed, and these grooves 47,
A plunger working peripheral surface 49 is formed between 48 and shown by hatching. Further, a groove 50 extending in the longitudinal direction is formed on the peripheral wall surface of the plunger 34,
Through this groove 50, the groove 48 is always connected to the cylinder chamber 43.
connected within. When the cam 35 rotates and the plunger 34 is pushed up, and the plunger working peripheral surface 49 closes the combustion supply port 44, the fuel in the cylinder chamber 43 is compressed and fuel is injected from the fuel injection valve 7. Then, when the plunger 34 further rises and the combustion supply port 44 opens into the groove 48, the pressurized fuel in the cylinder chamber 43 is returned to the fuel reservoir 32 via the grooves 50, 48 and the combustion supply port 44, so that the fuel injection stops. In this way, fuel injection is performed while the plunger working peripheral surface 49 closes the combustion supply port 44.

FIG. 6 shows a developed view of the plunger working peripheral surface 49 of FIG. In FIG. 6, the vertical axis H indicates the height direction of the plunger 34, and the horizontal axis C indicates the height direction of the plunger 34.
Indicates the circumferential direction. The plunger 34 is moved to the fifth position by the rack 42 when the accelerator pedal 25 is stepped on.
In the figure, it is rotated in the direction of arrow M. That is, in FIG. 6, the portion of the plunger working peripheral surface 49 facing the combustion supply port 44 changes from X--X to Y--Y as the engine load increases.
As mentioned above, the upper edge 5 of the plunger working peripheral surface 49
1 passes through the combustion supply port 44, fuel injection starts, and immediately after the lower edge 52 of the plunger working peripheral surface 49 reaches the combustion supply port 44, fuel injection stops. Therefore, it can be seen that the vertical length of the upper edge 51 and the lower edge 52 indicates the fuel injection amount. Thus, it can be seen from FIG. 6 that as the load becomes higher, the fuel injection amount gradually increases. On the other hand, the height H of the upper edge 51 of the plunger working peripheral surface 49 indicates the injection start time, and the higher the height of the upper edge 51, the earlier the fuel injection start time. Therefore, from FIG. 6, it can be seen that the injection start timing is earliest during low load operation, then gradually becomes later as the load increases, and then becomes gradually earlier again.

FIG. 7 shows the start timing of fuel injection from the fuel injection valve 7 and the opening degree of the scavenging control valve 21. In FIG. 7, the vertical axis shows the engine load L, and the horizontal axis shows the crank angle θ at which fuel injection is started and the opening ratio R of the scavenging control valve. In FIG. 7, the solid line D shows the fuel injection start timing of the internal combustion engine according to the present invention, the broken line E shows the opening ratio R of the scavenging control valve 21, and the chain line F shows the fuel injection start timing of the conventional diesel engine. . As shown by curve D in Fig. 7, the fuel injection start timing is around 120 degrees before top dead center during low load operation, and then gradually becomes later as the load increases, and the fuel injection start timing is approximately 120 degrees before top dead _center during low load operation. will be around 10 degrees before top dead center. Next, when the load becomes higher than _Lp , the injection start timing gradually advances as in a conventional diesel engine. Therefore, the shape of the plunger working peripheral surface 49 in FIG. 6 is determined according to the curve D shown in FIG. 7th
There are various other methods for setting the fuel injection start timing according to the curve D in the figure, and therefore, determining the injection start timing based on the shape of the plunger working peripheral surface 49 is only one example. Further, as shown by the broken line E in FIG. 7, the scavenging control valve 21 is only slightly opened during low load operation. Next, when the accelerator pedal 25 is depressed, the scavenging control valve 21 gradually opens until the load reaches the full load of 40°C.
It opens fully when the load reaches a certain percentage, and remains fully open when the load is higher than that.

First of all, if we consider during partial load operation when the scavenging control valve 21 is somewhat open, then the intake passage 14 is connected to the crank chamber 8 through the reed valve 15 during engine operation.
The air introduced into the interior is compressed as the piston 4 descends, and then passes through the opening 18 to the scavenging passage 1.
Pushed into 9. At this time, since the scavenging control valve 21 is provided, the air flowing in the scavenging passage 19 is decelerated, and then the air flows through the scavenging passage branch 20.
The air flows into the combustion chamber 6 through the scavenging hole 11 at a low speed. Next, these will be explained with reference to FIG. In the graph shown in Figure 3, the vertical axis is the combustion chamber 6
The inflow velocity V of the air flowing into the cylinder is shown, while the horizontal axis shows the crank angle θ. If the scavenging control valve 21 is not provided, most of the air will be sent from the crank chamber 8 into the combustion chamber 6 immediately after the piston 4 opens the scavenging hole 11, so the air inflow speed will be as shown by the curve in FIG. Scavenging port 1 as shown in A
Immediately after opening No. 1, there is a period when the speed becomes extremely fast.
On the other hand, by providing the scavenging control valve 21, the timing of air inflow is slightly delayed as shown by curve B, and the air flows into the combustion chamber 6 at a low speed. Further, when the air passes through the scavenging control valve 21, turbulence occurs in the air, but as shown in FIG. Therefore, the turbulence of the air flow is attenuated in the scavenging passage 19 before reaching the scavenging hole 11. As mentioned above, the air flow flowing into the combustion chamber 6 has a low velocity and the turbulence is attenuated, so when the air flows into the combustion chamber 6, almost no residual gas flow occurs within the combustion chamber 6. The heat dissipation of the residual burnt gas is thus prevented, thereby maintaining the residual burnt gas at a high temperature. Moreover, the air that has flowed into the combustion chamber 6 is surrounded by residual burnt gas. Especially at the beginning of compression during partial load operation, the combustion chamber 6
There is a large amount of residual burnt gas within the air, and the air is therefore surrounded by a large amount and high temperature of the remaining burnt gas. Then, during low load operation, the scavenging hole 11
Fuel is injected from the fuel injection valve 7 toward the supply air near the crank angle at which the piston 4 closes the fuel injection valve 7 . The injected fuel is heated by the high temperature residual burnt gas to promote vaporization, a portion of which is dispersed in the residual burnt gas, and the remainder mixed with the supply air to form a fuel-air mixture. As mentioned above, the temperature of the residual burnt gas is high, and the fuel vapor and fuel air mixture dispersed in the residual burnt gas are heated to form a mixture inside the residual burnt gas, the fuel air mixture and the residual burnt gas. Radicals are generated in the gas phase at the contact interface with the combustion chamber 6, and as a result, an active heat atmosphere is formed in the combustion chamber 6 (the atmosphere in which radicals are generated is referred to as an active heat atmosphere). During the compression stroke, the gas flow in the combustion chamber 6 is very small, so there is little turbulence and thermal energy loss to the combustion chamber wall, so the gas in the combustion chamber 6 becomes increasingly hot as compression progresses, and as a result, more radicals are generated. Occur. When radicals are being generated in this way, combustion called a pre-flame reaction has already started, and when the gas temperature in the combustion chamber 6 increases at the end of the compression stroke, a hot flame is generated and self-ignition occurs. Note that in the internal combustion engine shown in FIG. 1, there is an excess of air, and a large amount of oxygen is present in the residual burnt gas, so hot flames are also generated from the residual burnt gas. Then, a gentle combustion controlled by the residual burnt gas takes place, and the piston 4
When the combustion chamber 6 descends and opens the exhaust hole 12, the burnt gas in the combustion chamber 6 is discharged into the exhaust passage 13.

As shown in Figure 7, as the engine load increases, the start of fuel injection gradually becomes slower, but this is because as the engine load increases, the amount of injected fuel increases, and as a result, the amount of radicals generated also increases. This is because even if the injection start timing is delayed, sufficient radicals are generated to cause self-ignition at the end of the compression stroke.
Also, as shown in Fig. 7, the engine load is load L _p
If it exceeds , it becomes similar to a conventional diesel engine,
Therefore, as in the past, the fuel injection start timing is advanced as the engine load increases.
In this way, the timing to start fuel injection at full load is before top dead center.
It will be around 30 degrees. As mentioned above, the effective compression ratio of the internal combustion engine according to the present invention is preferably in the range of 14 to 16, which is much lower than that of a diesel engine, and therefore, like a conventional diesel engine, ignition combustion is performed by the heat of compression of air. Unlike the conventional combustion engine, this system makes the most effective use of exhaust gas heat to promote the generation of radicals, resulting in self-ignition.

As mentioned above, in order to maintain the active thermal atmosphere state until the end of the compression stroke, it is necessary to minimize the turbulence and flow of the residual burnt gas in the combustion chamber 6. Further causes of such turbulence and flow include rapid ejection of exhaust gas from the exhaust hole 12 and exhaust pulsation interference. In order to prevent these sudden jets of exhaust gas and exhaust pulsation interference, the first
It is preferable to dispose an exhaust control valve 55 in the exhaust passage 13 as shown by a broken line in the figure.This exhaust control valve 55 is connected to the accelerator pedal 25 via a link mechanism (not shown), and is As shown in FIG. 2, the valve gradually opens as the load increases from low-load operation, and the exhaust control valve 55 becomes fully open before the scavenging control valve 21 fully opens.

FIG. 8 shows another embodiment of FIG. In this embodiment as well, the start timing of fuel injection from the fuel injection valve 7 is set in the same manner as in FIG. Referring to FIG. 8, the internal combustion engine includes an exhaust turbo supercharger 60 having a radial turbine T and a centrifugal blower B.
The exhaust passage 13 is connected to the exhaust intake port 61 of the turbine T, and the scavenging passage 19 is connected to the intake discharge side 6 of the blower B.
Connected to 2. A scavenging control valve 63 connected to the accelerator pedal 25 is provided in the scavenging passage 19 as in FIG. 1, and as the load increases, the scavenging control valve 63 opens as shown by curve E in FIG. speak. On the other hand, as shown in FIG. 8, in this embodiment, the scavenging hole 11 opens into the combustion chamber 6 above the exhaust hole 12. That is, referring to FIG. 9, which is indicated using the same reference numerals as in FIG. I know it will be closed. Although not shown in the figure, the scavenging hole 11 and the exhaust hole 12 may be arranged to open and close at the same time.

In the crank compression two-stroke engine shown in FIG. 1, the pressure in the crank chamber 8 reaches its maximum immediately after the scavenging hole 11 opens. As shown by A, the flow velocity of the air flowing into the combustion chamber 6 becomes extremely high immediately after the scavenging hole 11 is opened, and it is therefore difficult to carry out active thermal atmosphere combustion during high-load operation. However, when the scavenging passage 19 is connected to the intake/discharge side 62 of the blower B as shown in FIG. 8, the pressure on the intake/discharge side 62 does not fluctuate as much as in the crank chamber, so even if the scavenging control valve 63 is fully open, the air is not scavenged. The gas flows into the combustion chamber 6 at a uniform and relatively low speed while the pores 11 are open. That is, even if the air flows in at such a low speed, the air continues to flow throughout the opening period of the scavenging holes 11, so that the amount of air necessary for high-load operation can be supplied into the combustion chamber 6. In other words, even during high-load operation, air is pumped into the combustion chamber 6 at a relatively low velocity.
Since the fuel can be supplied into the atmosphere, active thermal atmosphere combustion can be carried out. Note that during partial load operation, the air flow is throttled by the throttling action of the scavenging control valve 63 and flows into the combustion chamber 6 at a uniform speed, so the flow velocity of the air flowing into the combustion chamber 6 is equal to curve B in FIG. The flow rate becomes slower than the maximum flow velocity shown in , and active thermal atmosphere combustion becomes more likely to occur.

Further, as described above, when the piston 4 descends, the scavenging hole 11 opens and then the exhaust hole 12 opens, or the scavenging hole 11 and the exhaust hole 12 open simultaneously. Therefore, when the scavenging hole 11 opens, the pressure of the burned gas in the combustion chamber 6 is high, and a part of the burned gas in the combustion chamber 6 flows into the scavenging passage 19 through the scavenging hole 11. Inflow. Therefore, air and burnt gas are mixed in the scavenging passage 19 and then supplied into the combustion chamber 6 at a low speed. The air thus supplied into the combustion chamber 6 is mixed with the burnt gas, and therefore the NOx reduction effect of the burnt gas can be ensured. Note that if such a NOx reduction effect is not required, it may be placed below the scavenging hole 11 or the exhaust hole 12. Further, in the embodiment shown in FIG. 8, the turbine T performs the same function as the throttling action of the exhaust control valve 55 shown in FIG. Rapid ejection and exhaust pulse interference can be prevented.

FIG. 10 shows a case where the present invention is applied to a four-stroke internal combustion engine. In this embodiment as well, the timing of fuel injection from the fuel injection valve 7 is set as shown in FIG. However, in this case, fuel injection is performed once during two reciprocations of the piston 4. Further, in FIG. 10, the same components as in FIG. 1 are indicated by the same reference numerals. In FIG. 10, 70 is an intake valve;
71 is an intake passage, 72 is an exhaust valve, 73 is an exhaust passage, 74 is an intake control valve, and 75 is an exhaust control valve. Note that as the engine load increases, the intake control valve 74 opens as shown by curve E in FIG. 7, and the exhaust control valve 75 opens as shown by curve G in FIG. . In this embodiment, it is preferable that the valve overlapping period during which both the intake valve 70 and the exhaust valve 72 are open is longer. Considering a partial load operation in which the intake control valve 74 and the exhaust control valve 75 are not fully opened, the throttle action of the exhaust control valve 75 during the exhaust stroke prevents a sudden ejection of exhaust gas and interference with exhaust pulsation. , thereby preventing the residual burnt gas in the combustion chamber 6 from dissipating heat, and thus keeping the residual burnt gas at a high temperature. Also, the exhaust control valve 7
5, the burnt gas pressure in the combustion chamber 6 and the exhaust passage 73 upstream of the exhaust control valve 75 at the end of the exhaust stroke is relatively high.
When the valve is opened, a part of the burnt gas in the combustion chamber 6 is blown back into the intake passage 71 and mixed with air, and a part of the burnt gas in the exhaust passage 73 returns to the combustion chamber 6. Next, during the intake stroke, air flows into the combustion chamber 6 at a low speed due to the throttle action of the intake control valve 74. Next, during the compression stroke, when fuel is injected from the fuel injection valve 7, the residual burnt gas is maintained at a high temperature, so radicals are generated, and active thermal atmosphere combustion is thus performed. Although not shown in the drawings, in the embodiment shown in FIG. 10, a supercharger 60 similar to that shown in FIG. It can also be connected to the exhaust intake port 61 of the. However, in this case, there is no need to install the exhaust control valve 75.

As described above, according to the present invention, active thermal atmosphere combustion can be performed in a fuel-injected internal combustion engine, so fuel consumption and harmful components in exhaust gas can be significantly reduced, and moreover, no idle knock occurs. This allows for quiet operation.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of an internal combustion engine according to the present invention;
Figure 2 is a sectional view taken along the - line in Figure 1.
Fig. 3 is a diagram showing the opening period of the scavenging and exhaust holes in Fig. 1 and the change in the flow velocity of air flowing into the combustion chamber, Fig. 4 is a side sectional view of the combustion injection pump shown in Fig. Figure 6 is an enlarged perspective view of the plunger head in Figure 5, Figure 6 is a developed view of the operating peripheral surface of the plunger in Figure 5, Figure 7 is a graph showing the opening ratio of the scavenging/exhaust control valve and fuel injection start timing, Figure 8 9 is a side sectional view of another embodiment shown in FIG. 1, FIG. 9 is a diagram showing the opening period of the scavenging and exhaust holes of FIG. 8, and FIG. 10 is a side sectional view of still another embodiment. 6...Combustion chamber, 7...Fuel injection valve, 11...Scavenging hole, 12...Exhaust hole, 16...Fuel injection pump, 19...Scavenging passage, 21...Scavenging control valve, 5
5...Exhaust control valve.

Claims (1)

[Claims] 1. An internal combustion engine equipped with a fuel injection valve for injecting fuel into the combustion chamber of the engine, in which a throttle is provided in the air supply path to throttle the air supply path during partial load operation in order to supply air into the combustion chamber. A device is installed to allow air to flow into the combustion chamber at low speed during partial load operation, and to inject fuel only once from the combustion injector in each cycle, and to adjust the timing of fuel injection when the engine load is low to the timing when the engine load is high. A fuel-injected activated thermal atmosphere combustion internal combustion engine that is set to advance the fuel injection timing.