JPS58152123A - Suction valve for internal-combustion engine - Google Patents

Abstract

PURPOSE:To enable reducing of residual gas carried in at a suction stroke, by a method wherein, at a low-load range of an engine, suction air is caused to flow in even after a suction valve is closed, and a pressure of a suction path attains an atmospheric pressure through prevention of reverse flow by means of a lead valve on an auxiliary suction path. CONSTITUTION:At a low-load operating time of an engine, a closing valve 8 is closed, and when, with a suction valve 4 opened, a suction stroke starts, suction air is sucked in a working chamber 3 through a suction air introducing path 12 and an auxiliary suction path 17. Then, after the suction valve is closed, suction air continues to flow in through the suction air introducing path 12, reverse flow of suction air to an upstream side is prevented by a lead valve device 18, whereby a pressure of a suction path 7 at the downstream side of the closing valve 8 restores to an atmospheric pressure. Thus, even if the suction valve 4 is opened, the pressure of the suction path 7 at the downstream side of the closing valve 8 is brought to an atmospheric pressure, and thereby a reverse flow of residual gas from the working chamber 3 hardly occurs. Simultaneously, a reverse flow of exhaust gas to the working chamber 3 from an exhaust path 6 also hardly occurs.

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

For this reason, the fuel efficiency of 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 an intake passage 7 leads to a working chamber 3 of the engine (a space where intake air is sucked, compressed, combusted, and expanded, and combustion gas is discharged). A closing valve 8 is provided at a predetermined position.

The auxiliary intake passage 17 that branches from the intake passage 7 at the branch portion 16 bypasses the closing valve 8 and communicates with the intake passage 7 downstream of the closing valve 8. A reed valve device 18 having a reed valve 19 is provided at a predetermined position.

Further, an intake air introduction passage 12 communicating with the intake passage 7 on the downstream side of the closing valve 8 is formed.

Considering the low load range of the engine, stop valve 8 is closed (fully closed).
When the intake valve 4 opens and the intake stroke begins, intake air is drawn into the working chamber 3 from the intake introduction passage 12 and the auxiliary intake passage 17.

The intake air drawn into this working chamber 3 is further compressed and ignited,
It burns and generates power in the engine.

Considering the engine after the intake valve 4 has been closed (the communication between the intake passage 7 and the working chamber 3 has been cut off), intake air is still (continuously) flowing in from the intake introduction passage 12. As a result, the pressure in the intake passage 7 on the downstream side of the closing valve 8 is finally restored to atmospheric pressure.

(At this time, the reed valve device 18 prevents the intake air from flowing back to the upstream side.) Therefore, even if communication between the intake passage 7 and the working chamber 3 starts (even if the intake valve 4 opens), the intake air is closed. Since the pressure in the intake passage 7 on the downstream side of the valve 8 (pressure on the upstream side of the intake valve 4) is atmospheric pressure, backflow of residual gas from the working chamber 3 hardly occurs (usually Since the pressure upstream of 4 is extremely low, 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 the intake valve and the exhaust valve are open). 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 stable (combustion is stable even with a lean mixture), and the fuel efficiency of the engine is improved. will be 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 atmospheric pressure when the intake valve 4 opens, but it is effective even if the pressure has not completely recovered to atmospheric pressure.) (This is clear) If the direction of the auxiliary intake passage 17 is set eccentrically with respect to the central axis of the cylinder 2, the working chamber 3 will be displaced during the intake stroke.
Since it is possible to form a strong vortex of intake air, the combustion condition is improved and the fuel efficiency of the engine is further improved.

Next, when the throttle valve 11 of the vaporized wood is further opened and the load on the engine is increased, the stop valve 8 mechanically interlocked with the throttle valve 11 begins to open, and the intake air passes around the stop valve 8 and is also drawn from the intake passage 7. becomes 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 load on the downstream side of the throttle valve 11. Please keep it closed.

Next, if it is necessary to control the flow rate of the intake air flowing through the intake air introduction passage 12, a small throttle valve 13 mechanically interlocked with the throttle valve 11 may be installed here (it is also possible to simply install an orifice). ), or connect the intake air introduction passage 12 to the first intake term 4 and the second intake term 15 as shown by the two-dot chain line, and gradually increase the intake cross-sectional area of the second intake term 5 as the throttle valve 11 opens. It is better to do it like this.

Normally, the flow rate of fuel ejected from the vaporizing skin is supplied taking into account the air flowing through the intake introduction passage 12, but fuel from a float chamber (not shown) is ejected into the intake introduction passage 12. This is not necessary if you do so.

Note that even if the opening 12' of the intake air introduction passage 12 is opened to the auxiliary intake passage 17 on the downstream side of the reed valve device 18 as shown by the two-dot chain line (the intake air introduction passage 12 is opened to the auxiliary intake passage 17 on the downstream side of the reed valve device 18), as shown by the two-dot chain line, (There is no change in the fact that it communicates with the intake passage 7 on the downstream side.) In addition, the auxiliary intake passage 17 may be connected to a dedicated carburetor.

FIG. 2 shows an embodiment in which a rotary valve device is used instead of a reed valve device as a backflow prevention device.

That is, in FIG. 2, reference numeral 20 denotes a rotary valve device, which is driven by decelerating the rotation to, for example, 1/4 of the rotation of the engine output shaft, and reaches near the time when communication between the intake passage 7 and the working chamber 3 is started. During a certain period of time (for example, the period from when the intake valve 4 closes to when it opens), the auxiliary intake passage 17 is closed (that is, the auxiliary intake passage 17 is closed by the closing part 21 of the rotary valve device 20). ), this prevents the intake air in the intake passage 7 downstream of the closing valve 8 (approximately atmospheric pressure) from flowing back into the auxiliary intake passage 17 upstream of the rotary valve device 20.

In this case, if the rotary valve device 20 opens the auxiliary intake passage 17 before the intake valve 4 opens, the intake air in the intake passage 7 downstream of the closing valve 8 may cause backflow; is acceptable.

Although it is desirable that the rotary valve device 20 also opens the auxiliary intake valve 17 while the intake valve 4 is open, it is not necessary to completely match the opening and closing timings of both.

FIG. 3 shows an application of the present invention to a rotary piston engine.

7 is an intake passage leading to the working chamber 25; 12 is an intake introduction passage leading to the intake passage 7 downstream of the closing valve 8; and 17 is an intake passage 7 which bypasses the closing valve 8 and is connected to the intake passage 7 downstream of the closing valve 8. 18 is a reed valve device, 23 is a rotor housing, and 24 is a side housing.

During the period from the time when the communication between the intake passage 7 and the working chamber 25 is cut off (by the side surface of the rotary piston 22) to the time when communication is started, intake air entering from the intake introduction passage 12 causes damage to the air on the downstream side of the closing valve 8. Since the pressure in the intake passage 7 is (almost) atmospheric pressure, the intake passage 7 and the working chamber 25
Even if communication with the rotary piston 22 is initiated (by the side surface of the rotary piston 22), backflow of residual gas (combustion gas) is prevented;
The difference between residual gas brought into the intake stroke and fresh air is significantly reduced.

In the present invention shown in FIGS. 4 and 5, the auxiliary intake passage directly communicates with the working chamber.

In FIG. 4, 8 is a closing valve that closes (fully closes) the intake passage 7 in the low load range of the engine. , bypassing the closing valve 8 and leading directly to the working chamber 8 of the engine (that is, the auxiliary intake passage 17 is connected to the auxiliary intake valve 26).

The sub-intake valve 26 is driven by a cam (not shown), and the closing valve 8
In a low load range of the engine when the engine is closed, intake air is drawn into the working chamber 8 through the auxiliary intake passage 17, the auxiliary intake valve 26, and further from the intake introduction passage 12.

At this time, the opening/closing timing of the auxiliary intake valve 26 does not particularly need to match that of the intake valve 4 (for example, the auxiliary intake valve 26 may open later than the intake valve 4 and close in the middle of the intake stroke). It is a good thing).

During a certain period (period from when the intake valve 4 closes until it opens) when the intake passage 7 and the working chamber 3 start communicating with each other, intake air that enters from the intake introduction passage 12 causes the air flow to the downstream side of the closing valve 8. Since the pressure in the intake passage 7 is (almost) atmospheric pressure, even if the intake valve 4 is opened, residual gas will not be absorbed into the intake passage 7.
Almost no backflow occurs (of course, backflow of exhaust gas from the exhaust passage 6 to the working chamber 3 almost never occurs).

Therefore, the ratio of residual gas brought into the intake stroke to fresh air becomes small, and the fuel efficiency of the engine is significantly improved.

In this case, since the auxiliary intake passage 17 does not communicate with the intake passage 7 downstream of the closing valve 8, there is no need for a backflow prevention device such as a reed valve device (the same applies to the case in Fig. 5). .

Note that it is preferable that the auxiliary intake valve 26 is opened later than the intake valve 4.

Next, in FIG. 5, reference numeral 17 indicates an auxiliary intake passage which bypasses the closing valve 8 and directly communicates with the working chamber 25 (that is, opens to a predetermined position on the inner wall of the side housing 24). The intake air that has entered through the intake air introduction passage 12 during the period from the time when communication with the chamber 25 is cut off to the time when communication with the chamber 25 is started causes the air intake valve 7 on the downstream side of the closing valve 8 to
The pressure is increased (almost to atmospheric pressure) to reduce the ratio of residual gas brought into the intake stroke to fresh air.

This significantly improves the fuel efficiency of the engine.

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

[Brief explanation of drawings]

Figures 1 and 3 are cross-sectional views of the intake system for an internal combustion engine according to the present invention, and Figures 2, 4, and 5 are cross-sectional views of the intake system for an internal combustion engine according to the present invention.
A partial cross-sectional view of. 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 venturi part, 11 is a throttle valve, 12 is an intake introduction passage, 12' is an opening, 13 is a small throttle valve, 14 is a first intake hole, 15 is a second intake 16 is a branch part, 17 is a sub-intake passage, 18 is a reed valve device, 19 is a reed valve, 20 is a rotary valve device, 21 is a closing part, 22
is a rotary piston, 23 is a rotor housing, 24
2 is a side housing, and 26 is an auxiliary intake valve. 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 the intake passage downstream of the closing valve is further provided with a closing valve. The air intake passage forms an intake air introduction passageway through which the intake air can flow continuously, and an auxiliary intake air passage which bypasses the closing valve and leads to the intake passage downstream of the closing valve. The auxiliary intake passage is closed by a backflow prevention device for a certain period of time up to the time when a passage is formed and communication between the intake passage and the working chamber of the engine is started. An intake system for an internal combustion engine characterized by: (2) An intake system for an internal combustion engine according to claim 1, wherein the backflow prevention device is a reed valve device. (3) An intake system for an internal combustion engine according to claim 1, wherein the backflow prevention device is a rotary valve device. (4) The intake system for an internal combustion engine according to any one of claims 1 to 3, wherein a vortex is formed in the working chamber of the engine by the airflow of intake air from the auxiliary intake passage. (5) 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 load region of the engine, and the intake passage downstream of the closing valve is further provided with a closing valve. The intake air intake passage is configured to form an intake air introduction passageway through which the intake air can flow continuously, and to form an auxiliary intake passageway that bypasses the closing valve and directly communicates with the working chamber of the engine. An intake system for an internal combustion engine characterized by: (6) An intake system for an internal combustion engine according to claim 5, wherein a vortex is formed in the working chamber of the engine by the airflow of intake air from the auxiliary intake passage.