JPH1162564A - Internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve purification performance of exhaust gas and fuel consumption by introducing fresh air to an exhaust port only when the temperature of an internal combustion engine is lower than fixed temperature. SOLUTION: A negative pressure valve 27 and a reed valve 28 are arranged on the way of a fresh air tube 26 connecting between an exhaust port 9 and an intake manifold 20, the negative pressure valve 27 is connected to an intake port 8 through a communicating tube 30, and a three-way valve 31 is arranged on the way of the communicating tube 30. In the three-way valve 31, under the condition in which temperature of cooling water detected by a water temperature sensor 35 is lower than fixed temperature, namely, an engine is not warmed up, the opening 31c is opened by a solenoid 31b. When negative pressure in the intake port 8 is large, the valve element 27c of the negative pressure valve 27 is moved upward to open, when the pressure on the exhaust port 9 side is lower than the intake manifold 20 side, the reed valve 28 is opened, fresh air in the intake manifold 20 is introduced into the exhaust port 9 through the fresh air tube 26, and unburnt gas is burnt.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine for purifying and exhausting gas exhausted from an internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, in a general internal combustion engine, an air-fuel mixture is introduced into a combustion chamber of a cylinder from an intake manifold via an intake port, and the air-fuel mixture is burned. It discharges to the side.

At this time, in order to reduce pollution, a catalyst device provided in an exhaust muffler purifies and exhausts exhaust gas.

However, this catalyst device has a poor purifying function when the temperature is low. Therefore, fresh air is introduced to the exhaust port side to burn the exhausted unburned gas and to promote warm air of the catalyst device. What has been proposed.

[0005]

However, in such a conventional vehicle, a new port is always provided on the exhaust port side regardless of whether the internal combustion engine is warmed up or not. Since fresh air is introduced into the exhaust port even when the internal combustion engine is warmed up, when the stoichiometric air-fuel ratio is set, the amount of oxygen becomes excessive. In addition, the purification rate of nitrogen oxides (NOx) by the catalyst device is reduced. Also, in both the state where the internal combustion engine is warmed up and the state where the internal combustion engine is not warmed up, if the fuel is always set to be richer than the stoichiometric air-fuel ratio, the catalyst device is used as described above. Even if the purification rate of nitrogen oxides (NOx) does not decrease, there is a problem that fuel efficiency deteriorates.

Accordingly, an object of the present invention is to provide an internal combustion engine capable of improving the purifying performance of exhaust gas and improving fuel efficiency.

[0007]

In order to achieve the object, an invention according to claim 1 is directed to an internal combustion engine in which fresh air is introduced into an exhaust port only when the temperature of the internal combustion engine is lower than a predetermined temperature. It is characterized by having done.

According to a second aspect of the present invention, in addition to the first aspect, when the temperature of the internal combustion engine is lower than a predetermined temperature,
The blow-by gas in the oil pan is introduced to the intake side, and when the temperature of the internal combustion engine is higher than a predetermined temperature, the blow-by gas in the oil pan is introduced to the exhaust port.

[0009]

Embodiments of the present invention will be described below.

[First Embodiment of the Invention] FIGS. 1 and 2 show a first embodiment of the present invention.

First, the structure will be described. In the first embodiment, a two-cylinder 4 of a motorcycle as an "internal combustion engine" is used.
In the cycle engine, DOHC (Double Overhead Camsh
aft) mechanism.

That is, reference numeral 1 in FIG. 1 denotes a cylinder block. A cylinder head 2 is mounted on the upper side of the cylinder block 1, and an oil pan 3 is mounted on a lower side.

A cylinder chamber 4 is formed in the cylinder block 1, and a piston 5 is disposed in the cylinder chamber 4 so as to be vertically movable. This piston 5 is connected to a crankshaft 7 via a connecting rod 6.

An intake port 8 and an exhaust port 9 are formed in the cylinder head 2.
The opening facing the combustion chamber 10 is opened and closed by an intake valve 11 and an exhaust valve 12.

The valves 11 and 12 are urged by coil springs 13 and 14 in a direction to close the intake port 8 and the exhaust port 9, and are driven to open and close by an intake camshaft 15 and an exhaust camshaft 16. It has become.

As shown in FIG. 1, the intake camshaft 15 and the exhaust camshaft 16 have an intake valve 1
1 and cam portions 15a, 16a pressing exhaust valve 12
A cylinder head cover 17 is provided above the intake camshaft 15 and the exhaust camshaft 16.
Is attached.

A carburetor 18 is provided at the intake port 8.
The intake manifold 20 is connected to the intake manifold 20 via an air cleaner 21.

On the other hand, an exhaust pipe 23 is connected to the exhaust port 9.
Is provided with a catalyst device 24 for purifying exhaust gas.

The exhaust port 9 and the intake manifold 20 are connected via a fresh air pipe 26, and fresh air from the intake manifold 20 is introduced into the exhaust port 9 via the fresh air pipe 26. It has become so. A vacuum valve 27 and a reed valve 28 are provided in the middle of the fresh air pipe 26.

The negative pressure valve 27 is connected to the intake port 8 via a communication pipe 30. The negative pressure in the intake port 8 is
When it becomes larger than the inside of the intake manifold 20, the diaphragm 27a is displaced upward from the state shown in FIG. 1 against the urging force of the spring 27b.
It is opened when c moves upward.

A three-way valve 31 is provided in the communication pipe 30. This three-way valve 3
1 is such that the valve 31b is moved up and down by the solenoid 31a to open and close the opening 31c, and the communication state of the communication pipe 30 is shut off in the closed state. Then, the solenoid 31a is connected to the control unit 34, and the control unit 34
The cooling water temperature is higher than a certain temperature, that is, when the engine is in a warm-up operation state, the opening 31c is closed by the valve element 31b. Note that, instead of the water temperature sensor 35, the warm-up operation state can be detected based on the elapsed time from the start of operation of the internal combustion engine.

Further, a pair of the reed valves 28 are provided so as to open and close a flow port 29.
When the pressure is smaller on the exhaust port 9 side than on the intake manifold 20 side in a state where the valve 7 is open, as shown in FIG. 1, the reed valve 28 is opened and the communication port 29 is opened. I have.

On the other hand, a blow-by gas pipe 37 is connected between the cylinder block 1 and the intake manifold 20, so that blow-by gas in the cylinder block 1 is introduced into the intake manifold 20 side.

Next, the operation will be described.

Fresh air is introduced into the intake manifold 20 from the air cleaner 21, mixed with fuel in the carburetor 18, and the air-fuel mixture passes through the intake port 8, and the intake valve 11 is opened to open the combustion chamber 10. An air-fuel mixture is introduced therein. Then, the fuel is burned in the combustion chamber 10 and the exhaust valve 12 is opened, so that the exhaust gas is exhausted from the combustion chamber 10 and the catalyst device 2
Purified at 4 and discharged.

At this time, the temperature of the cooling water is
5 and this signal is sent to the control unit 3
4 and the water temperature is lower than a certain temperature, that is, in a state where the warm-up operation is not performed, the solenoid 31a
As a result, the valve body 31b is maintained at the position shown in FIG.
c has been opened.

When the negative pressure in the intake port 8 is large (in the case of low-speed operation), the valve body 27c of the negative pressure valve 27 moves upward and is opened, so that the negative pressure valve 27 is closer to the exhaust port 9 side than the intake manifold 20 side. When pressure is small, reed valve 2
8 is opened, and fresh air in the intake manifold 20 is introduced into the exhaust port 9 via the fresh air pipe 26.

In this case, since the air-fuel ratio of the air-fuel mixture is set to be small, unburned gas is exhausted to the exhaust port 9 side. The combustion gas can be burned. By burning in this manner, exhaust of unburned gas is suppressed, and warming up of the catalyst device 24 is promoted, so that the purification function is improved.

At the time of low-speed rotation, both valves 11 and 11 are operated during the intake stroke by a variable valve timing mechanism (not shown).
Since there is a point in time when 12 is simultaneously open, fresh air introduced into the exhaust port 9 is introduced into the combustion chamber 10 via the exhaust valve 12. Therefore, since the combustion in the combustion chamber 10 is promoted, the emission of unburned gas can be further suppressed. Thus, burning in the combustion chamber 10 burns better.

When the warm-up operation is started, a signal from the water temperature sensor 35 is input to the control unit 34, and the signal from the control unit 34
When the solenoid 31a of the three-way valve 31 is driven,
The valve element 31b is lowered from the position shown in the figure, the opening 31c is closed, and the upper side of the diaphragm 27a is opened to the atmosphere. Thus, the valve body 27c of the negative pressure valve 27 is closed, and the introduction of fresh air into the exhaust port 9 by the fresh air pipe 26 is shut off.

In the case of the warm-up operation state,
If the introduction of fresh air into the exhaust port 9 is blocked,
Even in the case of the stoichiometric air-fuel ratio, since the excess oxygen is not supplied to the catalyst device 24, the NOx purification rate is improved as compared with the conventional case. Further, in the warm-up operation state, the NOx purification rate does not deteriorate, so that the stoichiometric air-fuel ratio can be obtained as described above, and it is not necessary to always reduce the air-fuel ratio as in the related art. , Fuel efficiency can be improved.

Further, since the blow-by gas is introduced into the intake manifold 20 via the blow-by gas pipe 37, a rise in the pressure in the oil pan 3 is suppressed, so that the output of the internal combustion engine is improved and Since the blow-by gas is burned again, the exhaust gas is further purified.

[Second Embodiment of the Invention] FIGS. 3 and 4 show a second embodiment of the present invention.

The second embodiment differs from the first embodiment in that a three-way valve 31 is not provided in the communication pipe 30 and a control valve 40 is newly provided in the fresh air pipe 26. Further, the middle of the blow-by gas pipe 37 is connected via a three-way valve 41 between the control valve 40 and the negative pressure valve 27 of the fresh air pipe 26.

The control valve 40 has a valve body 40b that is opened and closed by a solenoid 40a.
It is connected to the. When the temperature of the cooling water is lower than a certain temperature, the valve body 40b is moved upward from the state shown in the figure by the control unit 34 and is opened, and when it is high, it is closed. When the vehicle travels at a low speed with a large negative pressure in the intake port 8, fresh air is introduced into the exhaust port 9 by opening the valve body 27 c of the negative pressure valve 27.

In this state, the three-way valve 41
The valve body 41a is set at the position shown in FIG. 3 by the solenoid 41b, and the blow-by gas is introduced into the intake manifold 20 side. The operation in this case is similar to that of the first embodiment.

On the other hand, when the cooling water temperature rises above a certain value and the engine is brought into a warm-up operation state, the valve 40b is closed by the solenoid 40a of the control valve 40 as shown in FIG. 3 is moved rightward in FIG. 3 by the solenoid 41b, the opening 41c is closed, and the blow-by gas intake manifold 2 is closed.
The flow to the zero side is cut off, and blow-by gas is introduced into the exhaust port 9 via the negative pressure valve 27 and the like.

As described above, when the blow-by gas is introduced into the exhaust port 9 when the internal combustion engine is not warmed up, the catalyst device 24 is not warmed up and has a poor purification function. Because it may be exhausted as it is,
In such a case, the exhaust gas is introduced into the intake manifold 20 to re-combust it. Also, when the internal combustion engine is warmed up, the catalyst device 24 is also warmed up and the purification function is improved. By introducing a blow-by gas into the catalyst device 24, the gas is purified and exhausted by the catalyst device 24. Therefore, as described above, it is not necessary to introduce the blow-by gas into the intake manifold 20, so that contamination of the vaporizer 18 and the like due to hydrocarbon, oil, moisture, and the like contained in the blow-by gas can be prevented. Since the blow-by gas has a small amount of oxygen, even if the blow-by gas is introduced into the exhaust port 9 during the warm-up operation, the NOx purification rate does not deteriorate.

Further, at the time of high-speed operation, the negative pressure in the intake port 8 becomes small, the valve body 27 of the negative pressure valve 27 is closed as shown in the figure, and the signal from the throttle position sensor 43 is transmitted to the control unit 34. , And the valve 40b of the control valve 40 is closed and the valve 41a of the three-way valve 41 is brought to the position shown in the drawing, and the blow-by gas is introduced into the intake manifold 20. By closing the valve element 40b of the control valve 40 and the valve element 41a of the three-way valve 41 in this manner, even if the pressure on the exhaust port 9 side increases due to high-speed operation, the exhaust gas is discharged to the negative pressure valve 27 side Without flowing back to
Damage and contamination of the reed valve 28 and the negative pressure valve 27 can be prevented.

Further, in the second embodiment, the middle of the blow-by gas pipe 37 is connected to the fresh air pipe 26, but it may be connected directly to the exhaust port 9.

Other configurations and operations are the same as those of the first embodiment, and therefore, description thereof is omitted.

In each of the first and second embodiments, the DOHC (Doubl) is a four-cylinder four-cycle engine of a motorcycle.
Although the present invention is applied to a device having an e-overhead camshaft (mechanism), the present invention is not limited to this, and it goes without saying that other internal combustion engines may be used.

[0043]

As described above, according to the present invention, fresh air is introduced into the exhaust port only when the internal combustion engine temperature is lower than a predetermined temperature. Since the exhaust gas is not warm, the purification function is not good. Thus, by introducing fresh air to the exhaust port side and burning it, the purification device can be improved by warming the catalyst device. .

Further, when the temperature of the internal combustion engine is higher than a predetermined temperature,
If the introduction of fresh air into the exhaust port is cut off when the engine is in the warm-up operation state, even if the stoichiometric air-fuel ratio is used, excessive oxygen is not supplied to the catalyst device.
The purification rate of x can be improved more than before. Furthermore, in the warm-up operation state, the NOx purification rate does not deteriorate, so that the stoichiometric air-fuel ratio can be obtained as described above, and it is not necessary to always reduce the air-fuel ratio as in the related art. , Fuel efficiency can be improved.

According to the second aspect of the present invention, in addition to the above-described effects, when the internal combustion engine temperature is lower than the predetermined temperature, the catalyst device is not warmed up, and the purification function is not good. By introducing the blow-by gas and burning it again, the purified exhaust gas can be discharged. In addition, when the internal combustion engine is warmed up, the catalyst device is also warmed up. Therefore, by introducing blow-by gas into the exhaust port, the catalyst device purifies and exhausts the exhaust gas. Therefore, as described above, since it is not necessary to introduce blow-by gas into the intake side, there is a practically useful effect that contamination of a vaporizer or the like by hydrocarbon, oil, moisture, or the like contained in the blow-by gas can be prevented. Demonstrate.

[Brief description of the drawings]

FIG. 1 is a sectional view of an internal combustion engine according to Embodiment 1 of the present invention.

FIG. 2 is a plan view of the internal combustion engine according to the first embodiment.

FIG. 3 is a sectional view of an internal combustion engine according to Embodiment 2 of the present invention.

FIG. 4 is a plan view of the internal combustion engine according to the second embodiment.

[Explanation of symbols]

 8 Intake port 9 Exhaust port 10 Combustion chamber 20 Intake manifold 24 Catalyst device 26 Fresh air pipe 27 Negative pressure valve 30 Communication pipe 34 Control unit 35 Water temperature sensor 37 Blow-by gas pipe

Claims (2)

[Claims] 1. An internal combustion engine wherein fresh air is introduced into an exhaust port only when the temperature of the internal combustion engine is lower than a predetermined temperature. 2. When the internal combustion engine temperature is lower than a predetermined temperature,
2. The internal combustion engine according to claim 1, wherein blow-by gas in the oil pan is introduced to the intake side, and when the temperature of the internal combustion engine is higher than a predetermined temperature, blow-by gas in the oil pan is introduced to the exhaust port.