JPS602493B2 - Internal combustion engine intake system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an intake system for improving the combustion characteristics of an internal combustion engine.

As part of exhaust countermeasures for internal combustion engines, for example, N
Increasing the exhaust gas recirculation rate to reduce oxidation, or diluting the supplied air-fuel mixture to simultaneously reduce HC, CO, and NOx, will both worsen combustion and destabilize the engine.

In addition, combustion becomes unstable when the engine is under low load, especially when idling or when the engine is cold started, so it is necessary to enrich the air-fuel mixture, which makes it difficult to reduce HC and CO emissions. there were.

Therefore, unless the stabilization of combustion is promoted along with the improvement of exhaust gas countermeasures, it will be difficult to maintain engine performance, and there will naturally be a limit to this. In order to solve this problem, the present invention introduces a high-speed air flow or a mixed air flow into the cylinder through a valve guide and an intake boat in synchronization with the opening of the intake valve, in addition to the intake air, to separate fuel and air. It is an object of the present invention to provide an intake system for an internal combustion engine, which actively promotes uniform mixing of intake air and turbulence of intake air, improves combustion characteristics, and thereby makes it possible to pursue further exhaust emission measures without impairing engine stability. purpose.

The present invention will be described below with reference to some examples. In the embodiment shown in FIG. 1, 1 in the figure is a cylinder head;
2 is a cylinder block, 3 is an intake manifold, 4 is an intake valve, and 5 is an intake boat, which bypasses a throttle valve (not shown) and directs air from upstream to the valve guide 7.
A passage 6 leading to the air passes through the intake manifold 3 and the flesh of the cylinder head 1.

The valve guide 7 of the intake valve 4 has a port 8 that connects with the passage 6, and has a similar annular groove 9 on the sliding surface with the stem portion 4a. Pass through the lotus.
The stem portion 4a is provided with an annular cover 34 located near the tip of the valve guide 7, and this cover 34 allows fluid to pass through the annular groove 9 of the valve guide 7 when the nozzle portion 12 is connected to the intake valve 4. Try to make it squirt. Note that the nozzle part 12
The jet flow from between the intake valve 4 and the valve seat 13 enters the combustion chamber 1.
The direction of the nozzle part 12 is determined so that the water flows into the inside of the nozzle 4, which will be described in detail later. Further, in the figure, 15 is a piston, and 16 is a spark plug. It is constructed as described above, and its operation will be explained next.

A negative current is generated in the intake passage (intake boat 5) from the throttle valve (not shown) to the intake valve 4 depending on the engine load state.

This suction negative pressure is larger in the lower load range, so if the passage 6, which has one end communicating with the upstream side of the throttle valve, is opened to the intake boat 5 through the port 8 of the valve guide 7, the annular groove 9, and the nozzle part 12, When the load is low, air is injected as a high-speed jet from the nozzle part 12 together with the intake valve 4, generating severe turbulence in the intake boat 5 and further in the combustion chamber 14. This flow promotes gas flow within the combustion chamber 14, promotes uniform mixing of the mixed gas in the suction and compression strokes, and furthermore causes flame turbulence in the combustion stroke due to the continued gas flow due to inertia. Together, they significantly increase the combustion rate and improve combustion stability.

Particularly in this case, when the intake valve 4 is lifted upward and closed, the nozzle portion 12 is blocked via the cover 34, so fluid injection is stopped; however, when the intake valve 4 engages, the cover 34 is lowered and the nozzle portion 12 is opened, and injection begins vigorously from the nozzle portion 12 into the combustion chamber 14.

By injecting in synchronization with the opening and closing of the intake valve 4 in this way, more fluid is delivered to the combustion chamber 14 as a jet within a limited period of time.
This further strengthens the swirling movement of the intake air flow and reduces attenuation until the combustion stroke, further promoting combustion. In other words, ``Compared to continuous jets, synchronized and intermittent jets can concentrate the energy of the jets more effectively and increase the sustainability of the swirl, resulting in even more stable combustion. It is possible to realize improvements in exhaust gas countermeasures based on the reduction in fuel efficiency, improvement in fuel efficiency, and extension of the lean limit of the air-fuel mixture and the limit of exhaust gas recirculation.

Note that it is also possible to provide the intake valve 4 with a passage for introducing auxiliary air as described above, the nozzle portion 12, etc., but in that case, the intake valve 4 may be provided in order to fix the orientation of the nozzle portion 12 in a desired direction. In addition to complicating the processing and structure, such as requiring a rotation stopper, there is also a risk that the strength and durability of the intake valve 4 may be impaired. In this respect, according to the above configuration, since the valve guide 7 is fixed, no change in the nozzle position that would strengthen the intake swirl flow occurs, and machining is easy, and it is advantageous in terms of strength and durability. . Next, other embodiments of the present invention will be described.

In Fig. 2, instead of integrally molding the cover 34 with the stem part 4a, an annular groove 35 is provided in the stem part 4a, and a cover 34' having vertically divided grooves is made, and this is attached to the upper end of the stem part 4a. insert the spring 37 into the annular groove 35.
It is tightened so that it is joined to the Since the cover 34' is of a separate type, productivity is improved compared to integral molding. In addition, in the example shown in FIG. 3, a lotus-through recess 38 is formed in the stem portion 4a without directly opening and closing the nozzle portion 12, and the recess 38 is formed in the stem portion 4a.
is constantly conveyed to the passage 6 via the passage 39 of the valve guide 7, while the concave portion 38 is intermittently passed through the annular groove 9 as the intake valve 4 is opened and closed.
The fluid is ejected from the intake valve 4 in synchronization with the intake valve 4. In addition, FIG. 4 shows an example in which the upstream entrance end of the air guiding passage 6 is passed through the clean side of the upstream air cleaner 23 by bypassing the throttle valves 22a and 22b of the carburetor 21. A throttle valve 24 may be provided in the passage 6a in the portion , either in conjunction with the throttle valves 22a and 22b or in a separate system, so that the amount of air jetted into the intake boat 5 is made proportional to the amount of intake air. good.

By controlling this injection air, it is possible to prevent fluctuations in the actual air-fuel ratio of the air-fuel mixture. In addition, in FIG. 5, instead of simply injecting air as shown in FIG. and nozzle part 1
The air-fuel mixture is ejected from 2.

The combustion conditions are further improved compared to the case where air is blown out, and if control is performed so that the main throttle valves 22a and 22b are fully closed during partial loads where particularly strong suction negative pressure is generated, the jet from the nozzle part 12 can be The air-fuel mixture blows out in a jet stream, making the mixture even leaner or improving low-temperature starting performance.
Improvements in fuel efficiency can be expected. In this case, the throttle valve 24 can be removed if the inner diameter of the nozzle portion 12 is determined so that the required amount of air-fuel mixture is obtained mainly during idling. The example shown in FIG. 6 shows a case where the intake system is equipped with an electronically controlled fuel injection device as a fuel V supply device instead of the carburetor 21. In this case as well, there is basically no difference from each of the above embodiments. Instead, the intake boat 5 is provided with a main fuel injection valve 28 that injects fuel proportional to the amount of intake air based on a signal from a control circuit (not shown); When it is desired to inject fuel, an auxiliary fuel injection valve 29 which is controlled in the same manner is provided.
Of course, when injecting only air, the auxiliary fuel injection valve 29 may be removed.

In the case of this electronically controlled fuel injection device, since the metering accuracy for the air in the main intake and auxiliary intake systems can be improved, the actual air-fuel control accuracy of the air-fuel mixture taken into the combustion chamber 14 is extremely high. In addition, since the fuel is atomized based on fuel mist, it is possible to supply an overall homogeneous air-fuel mixture.
Stable combustion characteristics can be obtained over a wide operating range.

Furthermore, in the example shown in FIG. 7, recirculated exhaust gas is used as the jet fluid to the intake boat 5, and for the purpose of reducing N A portion of the exhaust air is conducted into the passage 6 via 32.

If the amount of recirculated exhaust gas is increased to reduce N○×, combustion becomes significantly unstable, but this can be improved by homogenizing the mixing state of the intake air-fuel mixture and recirculated exhaust gas, which also has the effect of promoting swirl. This increases the stability of combustion. In addition, since the exhaust gas recirculation amount is reduced or made zero by the control valve 32 in a low load range such as during idling, one more nozzle part 12 is installed so that the air-fuel mixture is injected instead of the recirculated exhaust gas only at such times. It may be provided.

Therefore, reduction of N○× can be achieved without impairing engine operating performance.

However, regarding exhaust recirculation, it is the same as a normal engine,
Of course, air or air-fuel mixture may be ejected from the nozzle portion 12. By the way, in order to further promote the swirl of the air-fuel mixture in the combustion chamber 14, the direction on the plane of the fluid ejected from the nozzle part 12 is changed based on the relationship with the intake boat 5, for example, in the eighth direction. Configure as shown.

In this case, the intake valve 4 and the exhaust valve 17 are of a type that are not offset from the cylinder center, but since the intake boat 5 is curved in plan view, the intake air flow is not offset from the combustion chamber.
Turn counterclockwise within 4.

Therefore, in order to further promote this swirling flow S, the planar ejection direction of the nozzle portion 12 formed in the valve guide 7 should be
It is preferable to set the angle Q between the line connecting the stem center A and the Schilling center C and the tangent to the swirling flow S at the stem center point A. In this case, the jetting direction in the vertical section is preferably directed toward the circumference of the intake valve 4, but the closer this inflow angle is to the horizontal, the greater the effect of promoting swirling flow. In addition, as shown in FIG. 9, when the intake valve 4 is offset from the cylinder center C and the intake boat 5 forms a so-called swirl port, the jet The ejection direction N on the plane of the nozzle portion 12 is basically the same as in FIG.
The angle Q between the intake boat 5 and a line substantially perpendicular to the axis of the intake boat 5
It is preferable to set it in the range of 2.

In this way, the suction negative pressure generated in the intake boat 5 is used to inject air and mixture to improve the properties of the intake mixture.
It improves combustion characteristics, but the intake manifold 3
The effect of most efficiently disturbing the air-fuel mixture flowing into the intake boat 5 from the intake boat 5 and further promoting the swirling action is to
It depends on the negative pressure and the opening area of the nozzle part 12.

Specifically, it is most effective to control the flow rate Qn ejected from the nozzle portion 12 to a range of 10 to 50% of the theoretical suction mixture amount Q ratio determined based on the cylinder volume.

In other words, since the negative pressure in the intake boat 5 becomes particularly large during partial load, the fluid flowing in from the nozzle section 12 opening into the intake boat 5 becomes a violent jet, but if the cross-sectional area of this nozzle is too small, the flow rate is already low in the region. Since it reaches the speed of sound and becomes saturated, it is no longer possible to obtain a strong jet.

Therefore, a sufficient jet effect can be obtained by jetting more than 50% of the actual intake amount (therefore, 10% of the theoretical intake air mixture amount) from the nozzle part 12, especially during idling when the filling rate generally decreases to 20%. Contributes to improving engine stability during idling. On the other hand, if the nozzle cross-sectional area is too large, it will affect the negative pressure in the intake boat 5 and reduce the negative pressure, which will weaken the strength of the jet flow. desirable.

Looking at this in terms of the nozzle cross-sectional area, it depends on the shape of the intake boat, but when we tested it on a 4-cycle spark ignition reciprocating engine, for example, we found that it was quite effective in the range of 16mm (Sp/Sn) ≦1600. .

However, Sp is the total cross-sectional area of the intake boat at the nozzle entrance, and Sn is the total cross-sectional area of the nozzle.

In order to increase the nozzle injection speed as much as possible within the above area range, it is preferable to make the cross section of the passage leading to the nozzle portion 12 relatively larger than the cross section of the nozzle portion 12.

As described above, according to the present invention, the engine intake air-fuel mixture is mixed with a high-speed jet mainly during operation in the idling, partial load, and medium load ranges, and the mixed state of fuel, air, and even recirculated exhaust gas is homogenized. In addition to creating a swirling motion of the air-fuel mixture within the combustion chamber, the flame propagation is further disturbed, and these combinations can significantly improve the combustion conditions.

In particular, since the /zuru is located close to the combustion chamber, the mixing and vortex effects caused by the jet flow are extremely strong and the effects last until compression top dead center. Therefore, increasing the exhaust gas recirculation rate to reduce N○k, diluting the air-fuel mixture to reduce HC and CO, etc. can be carried out sufficiently without deteriorating engine operating performance, or Fuel efficiency and low-temperature startability are improved based on improved engine stability. In addition, a synergistic effect with lean mixture operation or high EGR operation can be achieved by combining with a multi-point ignition engine that installs a plurality of spark plugs for each cylinder to shorten combustion time. It goes without saying that the effect can be obtained not only in spark ignition but also in compression ignition internal combustion engines. Furthermore, according to the present invention, since the nozzle part and a part of the passage leading to the nozzle part are provided in the valve guide, the direction and positioning of the nozzle part are reliable, the structure and processing are relatively simple, and the intake air This has the advantage that there is no risk of impairing the durability of the valve.

[Brief explanation of the drawing]

Figure 1 is a sectional view showing one embodiment of the present invention, Figures 2 and 3 are
The figures are sectional views of other embodiments regarding intermittent injection. Similarly, FIG. 4 is a cross-sectional view of an embodiment that injects air, FIG. 5 is a cross-sectional view of an embodiment that injects air-fuel mixture, and FIG. 6 is a cross-sectional view of an embodiment for an engine equipped with a fuel injection device. FIG. 7 is a cross-sectional view of an embodiment in which the reflux member E blows out air. Figure 8,
FIG. 9 is an explanatory diagram showing the flow of the air-fuel mixture. 3
...Intake manifold, 4...Intake valve, 4a...
Stem portion, 5...Intake boat, 6...Introduction passage, 7
... Valve guide, 9 ... Annular groove, 12 ... Nozzle part, 14 ... Combustion chamber, 34 ... Cap-shaped cover, 3
8... Concavity. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9

Claims (1)

[Scope of Claims] 1. A nozzle portion of a passage bypassing an intake throttle valve is opened in an intake valve valve guide of an internal combustion engine, and communication of the passage is opened and closed in synchronization with the opening/closing operation of the intake valve. An intake system for an internal combustion engine configured to jet fluid at high speed from between an intake valve and a valve seat in a direction that generates mixing and vortex flow of intake air in a combustion chamber in response to negative intake pressure when a valve is opened. 2. The fluid passage formed in the cylinder head is constantly communicated with an annular groove formed in the sliding contact surface with the stem part of the valve guide, and the nozzle part provided in the valve guide connected to this annular groove is provided in the stem part. An intake system for an internal combustion engine according to claim 1, which opens only when an intake valve is opened through a cover provided with the intake valve. 3. The fluid passage formed in the cylinder head is communicated with the communication recess formed on the outer periphery of the valve stem part, while the annular groove formed in the sliding surface of the valve guide with the stem part and constantly communicating with the nozzle part. An intake system for an internal combustion engine according to claim 1, wherein the intake valve communicates with the intake valve through the communication recess when the intake valve is opened. 4. An intake device for an internal combustion engine according to any one of claims 1 to 3, wherein the fluid ejected from the nozzle portion is air. 5. The intake device for an internal combustion engine according to any one of claims 1 to 3, wherein the fluid ejected from the nozzle portion is a mixture. 6. The intake device for an internal combustion engine according to any one of claims 1 to 3, wherein the fluid ejected from the nozzle portion is recirculated exhaust gas. 7. The intake system for an internal combustion engine according to claim 5, which supplies only the air-fuel mixture from the nozzle portion to the engine during idling. 8. The intake system for an internal combustion engine according to claim 6, wherein the exhaust gas is stopped from being ejected from the nozzle during idling. 9 The relationship between the engine's theoretical suction mixture Qth and the flow rate Qn sucked from the nozzle is 0.1≦(Qn/Qth)
An intake system for an internal combustion engine according to any one of claims 1 to 3, wherein the cross-sectional areas of the intake port and the nozzle portion are set so that ≦0.5.