JPS635561B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention includes an intake passage that communicates with a combustion chamber and whose communication with the combustion chamber is interrupted by an intake valve, and
This invention relates to an improvement in an internal combustion engine including a bypass passage which bypasses a throttle valve provided in the intake passage and has one end opened upstream of the throttle valve of the intake passage and the other end opened near the intake valve. .

In general, this type of internal combustion engine is intended to improve fuel efficiency during light-load operation, and increases thermal efficiency by shortening combustion time by creating turbulence in the air-fuel mixture in the combustion chamber with intake air from the bypass passage. This is what we are trying to do. However, during light load operation, the amount of intake air from the bypass passage also decreases, so a sufficient improvement in fuel efficiency cannot necessarily be obtained.In addition, if the ratio of intake air from the bypass passage is increased in order to improve the fuel efficiency in this case, In a high load region, the proportion of intake air passing through the intake passage decreases, resulting in poor fuel atomization and vaporization, or an increase in intake air from the bypass passage causes dilution of the air-fuel mixture, resulting in lower output in this region. There is a problem that the value decreases.

The purpose of the present invention is to improve fuel efficiency in light load ranges with a relatively simple structure without reducing output in high load ranges, and furthermore, to improve fuel efficiency in light load areas such as motorcycles, which require high speed and high output. The aim is to improve the deterioration in fuel efficiency in the light load range, which tends to occur in internal combustion engines.

FIG. 1 shows a motorcycle engine that is an example of an internal combustion engine according to the present invention. The engine 10 is a fuel injection type multi-cylinder four-stroke engine, and the intake port 11 is airtightly connected to a connecting pipe 12 whose one end is airtightly connected to a surge tank 21. The inside of the pipe 12 forms an intake passage P ₁ that is opened and closed by an intake valve 13 of the engine 10 .
Further, a throttle valve 14 is disposed in the intake passage _P1 in the connecting pipe 12, and a throttle valve 14 is provided in the intake passage P1 in the connecting pipe 12.
is the intake passage _P1 on the downstream side of the throttle valve 14.
A fuel injection nozzle 31 facing toward the front is provided. This fuel injection nozzle 31 is connected to a fuel pump 33 connected to a fuel tank 32. On the other hand, the surge tank 21 is communicated with the atmosphere via an air flow meter 22 and an air cleaner 23. As a result, when the engine 10 is driven,
Air flows from the air cleaner 23 through the surge tank 21 to each intake passage _P1 , and then to the fuel injection nozzle 31.
The mixture is mixed with fuel that is intermittently injected into the intake passage _P1 , and flows into the combustion chamber R of the engine 10 as an air-fuel mixture. In addition, the reference numeral 34 in FIG. 1 is a fuel filter, and the reference numeral 35 is a fuel injection nozzle 31.
This figure shows a pressure regulator that controls the discharge pressure of fuel injected from the engine to a constant level.

Thus, in the engine 10, the second connecting pipe 15, whose one end is airtightly connected to the surge tank 21, is connected to a through hole that closes to the intake port 11 near the intake valve 13 via the flow rate control valve 40. 16, and the second connecting pipe 1
5. By the flow control valve 40 and the through hole 16,
A bypass passage _P2 is formed to bypass the throttle valve 14 provided in _the intake passage P1. As shown in FIGS. 2 to 4, the flow rate control valve 40 includes a valve housing 41 that is airtightly connected to the second connecting pipe 15 and the through hole 16, and a central large-diameter inner hole 41a of the valve housing 41. The coil spring 43 is constructed by a spool 42 interposed in the central large-diameter inner hole 41a and a coil spring 43 interposed in the central large-diameter inner hole 41a. The upstream end 42a of the spool 42 is formed into a large diameter portion that contacts the upstream stepped portion of the central large diameter inner hole 41a to open and close the upstream small diameter inner hole 41b. A wedge-shaped recess 42c is formed that gradually expands toward the downstream side toward the downstream end 42b. As shown in FIG. 2, this spool 42 is elastically urged upstream by a coil spring 43, and its upstream end 42a is connected to the large diameter inner hole 42.
In this state, the downstream end 42b slightly faces the downstream small diameter inner hole 41c of the valve housing 41. In addition, due to the drive of the engine 10, the intake passage near the intake valve 13
When an intake negative pressure is generated in _P1 , the spool 42 slides downstream within the downstream small-diameter inner hole 41c in response to the intake negative pressure, as shown in FIG. That is,
In the flow control valve 40, the wedge-shaped recess 4
2c and the downstream small-diameter inner hole 41c, the area of the valve port and the intake negative pressure have the relationship shown in FIG.

In the engine 10 configured in this way,
The air-fuel mixture flowing into the combustion chamber R of the engine 10 through the intake passage P ₁ is disturbed by the air flowing into the vicinity of the intake valve 13 in the intake passage P ₁ through the bypass passage P ₂ , making the air-fuel mixture more uniform. As the mixture is mixed, a swirl is generated within the combustion chamber R, and combustion of the air-fuel mixture within the combustion chamber R is promoted.

By the way, in the engine 10, since the flow control valve 40 having the characteristics shown in FIG. 5 is installed in the bypass passage _P2 , the flow rate from the bypass passage _P2 corresponding to the intake negative pressure A in the light load region is The inflow air amount characteristic B is as shown in FIG. That is, the inflow air amount characteristic B according to this method is different from the inflow air amount characteristic C from the bypass passage _P2 in the case of using a fixed throttle without intervening the flow rate control valve 40, in the front and rear regions of the intake stroke. A larger amount of inflow is obtained in the middle region, and the amount of inflow is reduced in the intermediate region, and the maximum amount of inflow can be obtained especially in the region at the rear of the intake stroke (crank angle Q ₁ to Q ₂ ). This is because, as shown in FIG. 5, the flow control valve 40 once increases its valve opening area as the intake negative pressure increases, and when the intake negative pressure is smaller than the maximum value of the intake negative pressure in the light load region. Its characteristics are determined so that the valve opening area reaches its maximum area, and as the intake negative pressure further increases, the valve opening area decreases significantly.On the other hand, the slope of increase/decrease in intake negative pressure is caused by intake inertia at the front of the intake stroke. This is because the region is larger than the region at the rear.
In this way, by interposing the flow rate control valve 40, it is possible to shift the timing at which the amount of inflowing air from the bypass passage _P2 increases to the rear region of the intake stroke, and the combustion occurs immediately before the end of the intake stroke. The swirl generated within chamber R can be increased to minimize swirl attenuation during the subsequent compression stroke. Therefore, in the engine 10, in the light load range, the swirl in the combustion chamber R is maintained without much attenuation until the ignition and combustion strokes, and fuel efficiency in the light load range is improved. Furthermore, in a region exceeding the light load region (low boost region), the intake negative pressure increases as a whole, so the valve opening area of the flow control valve 40 becomes large immediately after the intake valve opens and immediately before the intake valve closes. Only a very small area exists, and most of the intake air passes through the intake passage _P1 . Therefore, the fuel from the fuel injection nozzle 31 provided in the intake passage _P1 is sufficiently atomized and vaporized, so that no reduction in output occurs in this region.

Note that the above results are not limited to fuel injection type engines such as the engine 10, but also apply to the engine 10.
The present invention can also be obtained for a carburetor type engine which is equipped with a carburetor instead of the fuel injection nozzle 31, and the present invention can of course be applied to a carburetor type engine. In this case, since the flow rate control valve 40 is closed in an area exceeding the light load area, there is no dilution of the air-fuel mixture due to air flowing in from the bypass passage _P2 , and therefore the output due to dilution in such an area is reduced. No deterioration occurs. However, in a carburetor type engine, the intake amount Qb from the bypass passage P 2 is the total intake amount Qt from the intake passage P ₁ and the bypass passage P _{2 .}
If Qb/Qt is increased, the air/fuel in the intake passage _P1 becomes over-rich, and stable operation becomes difficult due to flow adhesion to the intake pipe wall, and as shown in Figures 7 and 8, Qb/Qt When the value approaches a predetermined value (approximately 0.6), the fuel efficiency deteriorates rapidly and the amount of HC in the exhaust gas increases rapidly, eventually leading to a misfire. On the other hand, in fuel injection type engines,
Since such a phenomenon rarely occurs, Qb/
Qt can be taken even larger. Therefore, when the present invention is applied to a fuel injection type engine like the engine in question, the ability to set Qb/Qt to a large value and the function of the flow rate control valve 40 are combined, and the ability to operate in a light load region is improved. This has the advantage of further improving fuel efficiency.

As is clear from the above description, the present invention includes an intake passage which communicates with the combustion chamber and whose communication with the combustion chamber is interrupted by an intake valve, and which bypasses a throttle valve provided in the intake passage and ends at one end. In an internal combustion engine, the bypass passage has a bypass passage that opens upstream from a throttle valve of the intake passage and whose other end opens near the intake valve. In response to the increase in intake negative pressure that occurs in The gist lies in an internal combustion engine characterized by having a flow control valve interposed therebetween having a valve opening area. Therefore, according to the present invention, in a light load region of an internal combustion engine, sufficient air can be provided just before the end of the intake stroke to uniformly mix the air-fuel mixture and create a swirl in the combustion chamber. It is possible to improve fuel atomization and vaporization in the light load range and above, or prevent dilution of the air-fuel mixture, thereby improving fuel efficiency in the light load range without causing a decrease in full-throttle output. .

[Brief explanation of the drawing]

FIG. 1 is a partial vertical cross-sectional view of a motorcycle engine showing an example of an internal combustion engine according to the present invention, FIG. 2 is a vertical cross-sectional view of a flow control valve, and FIG.
Figure 4 is a vertical cross-sectional view showing the operating state of the flow control valve, Figure 5 is a graph showing the characteristics of the flow control valve, and Figure 6 is the intake pipe internal pressure, crank angle, and inflow from the bypass passage. A graph showing the relationship between the amount of air, Figure 7 shows the total intake amount into the combustion chamber.
FIG. 8 is a graph showing the relationship between the intake amount Qb from the bypass passage and fuel efficiency with respect to Qt, and FIG. 8 is a graph showing the relationship between Qb/Qt and the HC amount. Explanation of symbols 10...engine, 13...intake valve, 14...throttle valve, 21...surge tank, 31...fuel injection nozzle, 40...flow control valve, 41...valve housing, 42...spool,
43...Coil spring, _P1 ...Intake passage, _P2 ...
bypass passage.

Claims (1)

[Claims] 1. An intake passage that communicates with the combustion chamber and is disconnected from the combustion chamber by an intake valve, and bypasses a throttle valve provided in the intake passage so that one end of the intake passage is located upstream of the throttle valve of the intake passage. In an internal combustion engine having a bypass passage which is open and whose other end opens near the intake valve, the bypass passage is temporarily closed in response to an increase in intake negative pressure generated in the intake passage near the intake valve. A flow control valve is installed in which the mouth area increases and reaches the maximum valve opening area, and then decreases significantly and reaches the maximum valve opening area at an intake negative pressure that is smaller than the maximum value of intake negative pressure in a light load region. An internal combustion engine characterized by: