JPS58152122A - Suction device for internal-combustion engine - Google Patents

Abstract

PURPOSE:To reduce carrying-in of residual gas at a suction stroke, by a method wherein, at a low-load operating time, with a main and an auxiliary suction valves opened, a suction closing valve and a suction shut-off valve are closed, air is sucked only through an auxiliary suction path, the shut-off valve is opened during closing of a suction valve, and suction air is sucked through a suction path. CONSTITUTION:In a low-load zone of an engine, a closing valve 8 is closed, and if, with a suction valve 4 and an auxiliary suction valve 17 opened, a suction stroke starts, suction air is sucked in a working chamber 3 only through an auxiliary suction path 14. For a specified duration of a period for which connection between a suction path 7 and the working chamber 3 is disconnected, a suction air introducing path 19 is opened by at least a suction air shut-off valve 15, and thereby suction air enters the path 7 at a downstream side of the closing valve 8 through the path 19 at a high speed, which results in bringing a pressure in a space to rise to an atmospheric pressure. When considering a condition right before the path 7 and the working chamber 3 start to be connected with each other, the pressure of the path 7 is brought to an atmospheric pressure, and this nearly prevents the occurrence of a reverse flow of residual gas from the working chamber 3 even if the suction valve 4 is opened.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an intake system for an internal combustion engine that makes it possible to reduce residual gas (combustion gas) carried into the intake stroke.

Generally, when the intake valve, etc. is opened in the low engine load range, the pressure in the intake passage upstream of the intake valve, etc. is extremely low, so residual gas (combustion gas) causes a backflow and is carried into the intake stroke. The ratio of residual gas to fresh air becomes significantly large, worsening combustion.

As a result, combustion in the engine deteriorates.

The present invention aims to solve these drawbacks and improve the fuel efficiency of the engine, and will be described below with reference to the drawings.

FIG. 1 shows an embodiment of an intake system for an internal combustion engine according to the present invention, in which a working chamber 3 of the engine (a space where intake air is sucked, compressed, combusted, and expanded, and combustion gas is discharged) is connected to an intake passage 7. A closing valve 8 is provided at a predetermined position.

The auxiliary intake passage 14 that branches from the intake passage 7 so as to bypass the closing valve 8 at the branch part 13 communicates with the working chamber 3 of the engine (without merging into the auxiliary intake passage 7 driven by a cam). An intake cutoff valve 15 is provided at a predetermined position in the auxiliary intake passage 14. The intake cutoff valve 15 is driven at a speed reduced to, for example, 1/2 of the rotation of the output shaft of the engine.

Furthermore, an intake air introduction passage 19 communicating with the intake passage 7 on the downstream side of the closing valve 8 is formed.

The opening/closing timing of the auxiliary intake valve 17 is almost the same as that of the intake valve 4, and it is preferable that the opening timing of the auxiliary intake valve 17 is made later.On the other hand, the intake cutoff valve 15 has the auxiliary intake valve 17 open. During this period, when the sub-intake valve 17 is opened for a certain period of time and the intake stroke begins, the intake air flows only from the sub-intake passage 14 into the working chamber 3 of the engine.
is inhaled.

(As described below, the intake air introduction passage 19 is connected to the intake air cutoff valve 15.
(Depending on the opening/closing timing, intake air may also be drawn into the working chamber 3 of the engine from here.) At this time, as shown in the figure, the intake air introduction passage 19 is opened and closed by the intake cutoff valve 15.
(In other words, communication between the communication passage 20 formed in the intake cutoff valve 15 and the intake air introduction passage 19 is interrupted.) To make this easier to understand, the intake cutoff valve 1
A cross-section of the intake air introduction passage 19 near point 5 is shown in FIG.

Also, for a certain period of time during which communication between the intake passage 7 and the working chamber 3 of the engine is cut off (intake valve 4 is closed)
The intake air introduction passage 19 is opened by the intake air cutoff valve 15 at least during the period (up to 10°).

As a result, the intake air enters the intake passage 7 on the downstream side of the closing valve 8 through the intake introduction passage 19 at a high speed, and the pressure in this space increases to atmospheric pressure (the intake cutoff valve 15 If the timing and period of opening and closing of the intake air introduction passage 19 are appropriately selected, it is possible that the air will enter at a high speed.) At this point, communication between the intake passage 7 and the working chamber 8 of the engine is started (the intake valve 4 Considering the situation just before the valve opens), as mentioned above, the pressure in the intake passage 7 on the downstream side of the closing valve 8 is atmospheric pressure, so even if the intake valve 4 opens, the residual gas from the working chamber 3 will not flow back. This hardly occurs (normally, the pressure on the upstream side of the intake valve 4 is extremely low, so a backflow of residual gas occurs).

At the same time, backflow of exhaust gas (combustion gas) from the exhaust passage 6 to the working chamber 3 hardly occurs (normally backflow of exhaust gas occurs during the overlap period when both intake and exhaust valves are open).

As described above, according to the present invention, the ratio of residual gas (in short, combustion gas) brought into the intake stroke to fresh air is small, so combustion is good (combustion is stable even with a lean mixture), and Engine combustion is significantly improved.

(In this case, it is desirable that the pressure in the intake passage 7 on the downstream side of the closing valve 8 be increased to atmospheric pressure when the intake valve 4 opens, but it is effective even if the pressure is completely restored to atmospheric pressure.) It is clear that if the direction of the auxiliary intake passage 14 is set eccentrically with respect to the central axis of the cylinder 2, the flow of intake air (vortex, turbulence, etc.) formed in the working chamber 3 during the intake stroke will be strengthened. As a result, combustion becomes better and the fuel efficiency of the engine is further improved.

Next, when the vaporization throttle valve 10 is further opened to increase the load on the engine, the stop valve 8 that is mechanically interlocked with the throttle valve 10 begins to open, passing around the stop valve 8 and also from the intake passage 7. The air will be inhaled.

In other words, it remains the same as before.

In this case, it is possible to open and close the closing valve 8 using a diaphragm device (not shown) that operates by sensing the negative pressure downstream of the throttle valve 10. It should be kept closed during the day.

Reference numeral 18 denotes a nozzle through which combustion is ejected from the carburetor float chamber (not shown). If this nozzle 18 is not provided, an orifice (not shown) is installed in the intake air introduction passage 19 or a throttle valve 10 is installed. A small throttle valve (not shown) mechanically interlocked with
It is preferable to install the intake air flow rate through the intake air introduction passage 19 to control the intake air flow rate.

Furthermore, it is also conceivable to configure the intake air introduction passage 19 so that the intake cross-sectional area of the first intake term 1 and the second intake term 12 increases sequentially as shown by the two-dot chain line.

Further, the closing valve 8 may be a plate-shaped or cylindrical valve that moves up and down, and the auxiliary intake passage 14 may be connected to a dedicated carburetor.

It is clear from the figure that during two rotations of the engine output shaft (crankshaft), the intake cutoff valve 15 opens the auxiliary intake passage 14 twice and the intake introduction passage 19 once.

Next, the preferred embodiment of the present invention is the intake cutoff valve 15.
is in the middle of the intake stroke (for example, when the crankshaft angle is 80° from the top dead center position of the piston 1), the auxiliary intake passage 14
The goal is to close the .

In this way, in the low load range of the engine when the shutoff valve 8 is closed, the intake stroke becomes virtually short (the working chamber 3
(Because the intake of air to the engine is interrupted midway), when the same weight of intake air is drawn into the working chamber 8, the degree of throttling of the intake air by the throttle valve 10 can be reduced.

FIG. 3 shows a PV diagram (pressure-volume diagram) of the engine in such an embodiment, and as is clear from the diagram, the intake cutoff valve 15 closes the auxiliary intake passage 14 at the Vc point. It will be understood that this reduces the degree of intake throttling by the throttle valve and significantly reduces the engine's intake resistance loss (pumping loss).

This further improves the fuel efficiency of the engine.

Of course, in this case, after the intake cutoff valve 15 closes the auxiliary intake passage 14, the intake air flows from the intake introduction passage 19 etc. to the working chamber 3.
It goes without saying that you must prevent them from entering. P. The dots indicate atmospheric pressure.

In order to prevent the intake cutoff valve 15 from becoming an intake resistance in the intake passage 7, the intake cutoff valve 15 has a narrow diameter portion 21 as shown in FIG. (It is devised so that it crosses aisle 7).

FIG. 4 shows an application of the present invention to a rotary piston engine.

8 is a closing valve that closes the intake passage 7 in the low (medium) load range of the engine; 14 is a sub-intake passage that opens at a predetermined position of the side housing 24 and communicates with the working chamber 25 so as to bypass the closing valve 8; Reference numeral 15 denotes an intake cutoff valve that opens the auxiliary intake passage 14 during a certain period from the time when communication between the intake passage 7 and the working chamber 25 is started (by the side surface of the rotary piston 22) until the time when communication is interrupted. Shutoff valve 1
Reference numeral 5 designates an intake passage 19 that communicates with the intake passage 7 on the downstream side of the closing valve 8 for a certain period of time during which communication between the intake passage 7 and the working chamber 25 is cut off (for example, between the intake passage 7 and the working chamber 25). At least during the period from the time when communication with 25 is cut off until the time when communication with 25 is restarted, the communication is open.

In the figure, this intake cutoff valve 15 is
Since the cross-sectional area is smaller than that of the intake passage 7, the flow of intake air formed in the working chamber 25 is strengthened by the fast air flow of intake air entering from the auxiliary intake passage 14, and the combustion characteristics are improved. .

If it is closed and the intake air is prevented from entering the working chamber 25 from the intake introduction passage 19 etc., the degree of throttling of the intake air by the throttle valve will be reduced as described above, and the intake resistance loss of the engine will be significantly reduced. (This also applies to Figures 5 and 6, which will be described below).

In the present invention shown in FIGS. 5 and 6, the sub-intake passage is arranged to communicate with the intake passage downstream of the closing valve.

First, in FIG. 5 (showing an embodiment of the present invention in a rotary piston engine), 8 is a closing valve that closes the intake passage 7 in the low (medium) load range of the engine, and 14 is a closing valve 8.
The auxiliary intake passage bypasses the closing valve 8 and communicates with the intake passage 7 on the downstream side of the closing valve 8. Reference numeral 19 indicates an intake introduction passage.

The intake cutoff valve 15 operates for a certain period of time during the period when the communication between the intake passage 7 and the working chamber 25 is cut off (for example, when the communication between the intake passage 7 and the working chamber 25 starts again from the time when the communication is cut off). During this period), at least the intake air introduction passage 19 is opened (the communication passage 20 is in communication).

Further, the intake cutoff valve 15 opens the auxiliary intake passage 14 for a certain period of the intake stroke, and also opens the sub-intake passage 14 for a certain period of time (e.g., close to the time when communication between the intake passage 7 and the working chamber 25 starts) The period from the time when communication between the passage 7 and the working chamber 25 is cut off until the time when communication is restarted is the sub-intake passage 1.
4 is kept closed.

This prevents intake air that has entered the intake passage 7 downstream of the shutoff valve 8 from the intake introduction passage 19 from flowing back into the auxiliary intake passage 14 upstream of the cutoff valve 15.

Even if communication between the intake passage 7 and the working chamber 25 is started in this way, the pressure in the intake passage 7 on the downstream side of the closing valve 8 has been increased to atmospheric pressure, so that residual gas does not flow back into the intake passage 7. This reduces the ratio of residual gas (combusted gas) to fresh air brought into the intake stroke, resulting in better combustion characteristics and greatly improved engine fuel efficiency.

Note that if the intake cutoff valve 15 opens the auxiliary intake passage 14 slightly before the time when communication between the intake passage 7 and the working chamber 25 starts, the intake air in the intake passage 7 on the downstream side of the closing valve 8 will be removed. may cause momentary reflux, but some reflux is tolerable.

Next, in FIG. 6, reference numeral 14 denotes an auxiliary intake passage that bypasses the closing valve 8 and communicates with the intake passage 7 downstream of the closing valve 8;
Reference numeral 15 indicates an intake cutoff valve that is driven at a speed of 1/2 of the rotation of the engine output shaft.

This intake cutoff valve 15 is used for a certain period of time (for example, until the intake valve 4 opens due to the crankshaft angle) during a period when the communication between the intake passage 7 and the working chamber 3 is cut off (the intake valve 4 is closed). 100° period) is at least a predetermined period (for example,
The auxiliary intake passage 14 is closed during a period of 100° until the intake valve 4 opens due to the crankshaft angle.

As a result, even if the intake valve 4 opens, the pressure in the intake passage 7 on the downstream side of the closing valve 8 is increased (to atmospheric pressure), so the ratio of residual gas brought into the intake stroke to fresh air is significantly increased. Decrease.

In this case, the intake cutoff valve 15
The sub intake passage 14 is opened twice, but the intake introduction passage 19 is opened twice.
It is preferable to open it only once.

Note that it is clear that the ninth position introduction passage 19 may be opened to the auxiliary intake passage 14 downstream of the intake cutoff valve 15 (as before, the ninth position introduction passage 19 may be opened to the intake passage 7 downstream of the closing valve 8). There is no change in the fact that it is open).

Since the present invention is configured as described above, the ratio of residual gas brought into the intake stroke to fresh air can be significantly improved.

[Brief explanation of drawings]

Figures 1, 4, 5, and 6 are cross-sectional views of an intake system for an internal combustion engine according to the present invention, Figure 2 is a cross-sectional view of an intake air introduction passage in the vicinity of an intake cutoff valve, and Figure 3 is a PV diagram. 1 is the piston, 2 is the cylinder, 3.25 is the working chamber, 4
is an intake valve, 5 is an exhaust valve, 6 is an exhaust passage, 7 is an intake passage,
8 is a closing valve, 9 is a carburetor, 10 is a throttle valve, 11 is a first intake hole, 12 is a second intake hole, 13 is a branch part, 14 is a sub intake passage, 15 is an intake cutoff valve, 16 is a closing part , 17 is a sub-intake valve, 18 is a nozzle, 19 is an intake introduction passage, 20 is a communication passage,
21 is a narrow diameter portion, 22 is a rotary piston, 23 is a rotor housing, and 24 is a side housing. Patent applicant Osamu Kitamura■

Claims (6)

[Claims] (1) A closing valve is provided at a predetermined position in the intake passage leading to the working chamber of the engine, and this closing valve is kept closed during the low engine load range, and a sub-intake passage that bypasses the closing valve is provided. An intake shutoff valve is provided, and an intake introduction passage communicating with the intake passage downstream of the shutoff valve is formed, and at least for a certain period during which communication between the intake passage and the working chamber of the engine is cut off, The intake intake passage is opened by an intake cutoff valve, thereby increasing the pressure in the intake passage downstream of the closing valve, and causing the sub-intake passage to join the intake passage downstream of the closing valve. An intake system for an internal combustion engine, characterized in that the air intake system is arranged so that it can be smoothly communicated with the working chamber of the engine. (2) The auxiliary intake passage is closed in the middle of the intake stroke by an intake shutoff valve, and when the shutoff valve is closed, intake air is prevented from entering the working chamber of the engine from then on. intake system for internal combustion engines. (3) An intake system for an internal combustion engine according to claim 1 or 2, wherein the flow of intake air in the working chamber of the engine is strengthened by the fast airflow of intake air from the auxiliary intake passage. (4) A closing valve is provided at a predetermined position in the intake passage leading to the working chamber of the engine, and this closing valve is kept closed during the low engine load range, and furthermore, the intake passage is provided in a sub-intake passage that bypasses the closing valve. A shutoff valve is provided, and an intake air introduction passage is formed that communicates with the intake passage downstream of the shutoff valve, and at least for a certain period of time during which communication between the intake passage and the working chamber of the engine is cut off, the intake air is The intake air introduction passage is opened by a shutoff valve, thereby increasing the pressure in the intake passage downstream of the closing valve, and the auxiliary intake passage starts communicating with the intake passage downstream of the closing valve. An intake system for an internal combustion engine, wherein the auxiliary intake passage is closed by the intake cutoff valve for a predetermined period up to the vicinity of the timing of the intake. (5) The auxiliary intake passage is closed in the middle of the intake stroke by an intake shutoff valve, and when the shutoff valve is closed, intake air is prevented from entering the working chamber of the engine thereafter. intake system for internal combustion engines. (6) An intake system for an internal combustion engine according to claim 4 or 5, wherein the flow of intake air in the working chamber of the engine is strengthened by a fast airflow of intake air from the auxiliary intake passage.