JP3133434B2 - engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine, and more particularly, to an engine which thoroughly purifies residual gas remaining in a combustion chamber.

[0002]

2. Description of the Related Art As means for increasing the thermal efficiency of an engine,
It is known to increase the compression ratio, but there is a problem that knocking is likely to occur when the compression ratio of the engine is increased.

In order to solve the problem of knocking, Japanese Patent Laid-Open No.
Japanese Patent Publication No. 119621 discloses that a so-called valve overlap period in which both an intake valve and an exhaust valve are opened is increased to scavenge residual gas remaining in a combustion chamber. That is, by scavenging the high-temperature residual gas, the in-cylinder temperature can be lowered, thereby suppressing the occurrence of knocking.

[0004]

However, scavenging by extending the valve overlap period is effective for an engine with a mechanical supercharger in which the intake pressure is larger than the exhaust pressure, but the exhaust pressure is more effective. It is powerless for a naturally aspirated engine or an engine with a turbocharger that has a larger intake pressure.

An object of the present invention is to provide an engine capable of performing scavenging regardless of the type of engine.

[0006]

According to the present invention, in order to achieve the above technical objects, the present invention is formed on an engine body,
It has a storage chamber that opens to the combustion chamber, and a storage chamber valve that opens and closes the opening of the storage chamber. The storage chamber valve is configured to be opened at the end of the exhaust stroke and closed in the compression stroke. .

[0007]

According to the above arrangement, high-pressure air is taken into the storage chamber during the compression stroke, and the high-pressure air stored in the storage chamber is discharged to the combustion chamber at the end of the exhaust stroke. In this exhaust stroke, the combustion chamber is in a high temperature state, so that the high-temperature air in the storage chamber is ejected into the combustion chamber while expanding, and the high-pressure residual gas is discharged by the high-pressure air into the exhaust port. Will be extruded. That is, scavenging is performed by high-pressure air in the storage chamber.

As prior arts which are structurally similar to the present invention, Japanese Patent Application Laid-Open Nos. 54-116512 and 54-9
There is an engine disclosed in, for example, Japanese Patent No. 80408. This engine includes a storage chamber that opens to the combustion chamber, and a storage chamber valve that opens and closes the opening of the storage chamber. This point is common to the present invention.

[0009] However, in this engine with a storage chamber, the storage chamber valve is opened in accordance with the closing timing of the intake valve, and the air in the storage chamber is used (using the pressure difference between the storage chamber and the combustion chamber). The present invention differs from the present invention in that a strong swirl is generated in the combustion chamber.

[0010]

Embodiments of the present invention will be described below with reference to the accompanying drawings. In FIG. 1, reference numeral 1 denotes an engine,
The engine 1 has a piston 3 inserted into a cylinder bore 2.
This defines a combustion chamber 4. The combustion chamber 4 is of a pentle-shaped type, and a spark plug 5 is disposed at the top thereof. An intake valve 6 is disposed at an intake port 6 which opens to the combustion chamber 4, and an exhaust port is provided. An exhaust valve 9 is provided at 8. A throttle valve 11 is disposed in an intake passage 10 connected to the intake port 6.
A fuel injection valve 12 is provided facing the port 6.

The engine 1 has a storage chamber 15. The storage chamber 15 has a storage chamber port 15a opened to the combustion chamber 4, and the storage chamber port 15a has a storage chamber valve 1 provided therein.
A storage chamber port 15a is opened and closed by the storage chamber valve 16.

FIG. 2 shows an example of the opening and closing timing of the storage chamber valve 16. In FIG. 2, a broken line indicates the valve timing of the exhaust valve 9. The chain line indicates the intake valve 7.
FIG. The solid line indicates the valve timing of the storage chamber valve 16.

As apparent from FIG. 2, the storage chamber valve 1
Reference numeral 6 indicates that the opening / closing operation is performed twice per cycle. That is, in the first opening / closing operation, the storage chamber valve 16 is opened before the intake valve 7 is opened, and the closing timing of the storage chamber valve 16 is after the intake valve 7 is opened.

In other words, the first opening / closing operation of the storage chamber valve 16 is opened at the end of the exhaust stroke and closed at the beginning of the intake stroke. On the other hand, in the second opening / closing operation of the storage chamber valve 16, the storage chamber valve 16 is opened in the latter half of the intake stroke (before the intake valve 7 is closed), and the storage chamber valve 16 is closed during the compression stroke. ing.
In the second opening / closing operation, the storage chamber valve 16 may be opened before the intake bottom dead center.

In the first opening / closing operation of the storage chamber valve 16, the reason why the storage chamber valve 16 is closed at the beginning of the intake stroke is that it is meaningless if the residual gas is driven into the intake port 6 side. The storage chamber valve 16 may be closed in accordance with the opening timing of the intake valve 7 as the closing timing of the storage chamber valve 16.

In the above configuration, part of the high-pressure air in the combustion chamber 4 is confined in the storage chamber 15 by the second opening / closing operation of the storage chamber valve 16 performed in the compression stroke from the latter half of the intake stroke. Then, it is cooled in the storage chamber 15.

The high-pressure air cooled in the storage chamber 15 is discharged to the combustion chamber 4 by the first opening / closing operation of the storage chamber valve 16. That is, the high-pressure air in the storage chamber 15 is ejected while expanding into the combustion chamber 4 in a high temperature state, and the residual gas in the combustion chamber 4 is pushed out to the exhaust port 8 (scavenging of the residual gas).

FIG. 3 shows a modification of the opening / closing operation of the storage chamber valve 16. As is clear from FIG. 3, the storage chamber valve 16 is opened at the end of the exhaust stroke and closed at the compression stroke as in FIG.
In this modification, the open state of the storage chamber valve 16 is maintained during that time. According to this modification, the open state of the storage chamber valve 16 is continued for a long time, and thus there is an advantage that a large lift amount can be easily set. Here, it has been described that if the intake valve 7 and the storage chamber valve 16 are simultaneously opened, the residual gas will be driven into the intake port 6 side. However, the opening timing of the storage chamber valve 16 is appropriately selected (set). Thus, it is possible to complete scavenging (pushing residual gas to the exhaust port 8) before the intake valve 7 opens.

As another modified example of the opening / closing operation of the storage chamber valve 16, although not shown, when the opening / closing operation of the storage chamber valve 16 is performed twice, a second opening / closing operation (take in of high-pressure air) is performed. May be performed during the compression stroke after the intake valve 7 is closed. That is, the second opening and closing operation of the storage chamber valve 16 may be performed during the compression stroke after the intake valve 7 is closed.

As the operation area of the storage chamber valve 16, the storage chamber valve 16 may be operated in a high load area, and the operation of the storage chamber valve 16 may be stopped (maintained in a closed state) in a light load area. According to this, it is possible to scavenge the residual gas using the storage chamber 15 in the high load region,
There is an advantage that knocking during high-load operation can be suppressed due to a decrease in the in-cylinder temperature due to the scavenging.

Therefore, in a naturally aspirated engine, a high compression ratio can be achieved. Further, in an engine with a turbocharger driven by exhaust energy, it is possible to increase the compression ratio and / or the supercharging pressure. In the case of an engine with a mechanical supercharger, the valve
There is an advantage that scavenging can be achieved without extending the wrap period.

On the other hand, in the light load region, since the storage chamber 15 is closed, during the compression stroke, the storage chamber valve 16 is closed.
There is an advantage that a compression loss due to opening and closing of the can be prevented. In other words, when the storage chamber valve 16 is opened and closed during the compression stroke, the compression stroke is performed under the volume of the combustion chamber 4 plus the volume of the storage chamber 15, so that a compression loss occurs.

Of course, scavenging using the storage chamber 15 may be performed in the high load area and the light load area. That is, the amount of the residual gas remaining in the combustion chamber 4 generally fluctuates greatly from cycle to cycle, but since the fluctuation of the amount of the residual gas can be suppressed by scavenging using the storage chamber 15, Combustion stability in the load region can be ensured. Therefore, in a so-called lean-burn engine that performs engine control under a lean air-fuel ratio, there is an advantage that the lean degree of the air-fuel ratio can be increased (the air-fuel ratio lean). Extension of the limit). Alternatively, there is an advantage that the idling operation can be stabilized.

FIGS. 4 to 6 show an example of the operation stop mechanism 19 of the storage chamber valve 16. FIG. The engine shown in FIG. 4 has two intake valves 7, 7 and two exhaust valves 9, 9 in one cylinder, and these intake valves 7 and exhaust valves 9 are individually controlled by camshafts 20, 21, respectively. The engine is a driven double overhead cam type engine (DOHC engine). That is, one camshaft 20 is used for an intake valve, and the other camshaft 21 is used for an exhaust valve.
It is linked to the engine output shaft and rotates in synchronization with the engine output shaft.

The cam 22 for the storage chamber valve 16 is disposed on the camshaft 20 for the intake valve, and between the storage chamber valve cam 22 and the storage chamber valve 16, the storage chamber valve 16 is provided. A first rocker 23 in contact with and a second rocker 24 in contact with the cam 22 are arranged side by side.
The first and second rockers 23 and 24 are swingable around a hollow shaft 25, and the second rocker 24 is a spring 26.
(See FIG. 5).

The first and second rockers 23 and 24 include:
As shown in FIG. 5 and FIG.
Hole 23a and the second hole 24a are formed respectively. A connecting pin 27 is slidably fitted in the first and second holes 23a and 24a. The connecting pin 27 is urged toward the second rocker 24 by a compression spring 28, and is connected to the pressure chamber 24b. When the hydraulic pressure is supplied, the connecting pin 27 enters the first rocker 23, and the first and second rockers 23 and 24 are integrated by the connecting pin 27 (see FIG. 6). It is opened and closed by the cam 22.

On the other hand, when the oil pressure in the pressure chamber 24b is drained, the connecting pin 27 is pushed back to the second rocker side 24 by the spring force of the compression spring 28 as shown in FIG. First and second rockers 23 and 2
4 is released, whereby the operation of the storage chamber valve 16 is stopped. The storage chamber valve 16 is spring-biased in the valve closing direction, as described later. Therefore, when the operation of the storage chamber valve 16 is stopped, the storage chamber valve 16 is maintained in the closed state. Further, the pressure chamber 2
Supply or release of the hydraulic pressure to 4b is performed using an oil passage 25a (see FIGS. 5 and 6) in the hollow shaft 25.

FIGS. 7 to 10 show specific examples of the storage chamber 15, FIGS. 7 and 8 show one example, and FIGS. 9 and 10 show other examples. Among the elements described in the drawings, the same elements as those described above are denoted by the same reference numerals, and the description thereof will be omitted.
Hereinafter, only the characteristic portions of each specific example will be described.

In FIGS. 7 and 8, reference numeral 30 denotes a cylinder head, in which the intake port 7 and the like are formed in the cylinder head 30 as is known. Further, in this specific example, the cylinder head 30 is used for a four-cylinder engine in which four valves are provided for each cylinder.
In contrast, an opening is provided in a region (end gas zone on the intake side) sandwiched between the two intake ports 6 and 6. The storage chamber port 15a extends along the intake port 6 and is opened on one side surface (the side surface on which the intake port 6 opens) of the cylinder head 30.

On the other hand, an intake manifold 31 (a member forming an independent intake passage communicating with the intake port 7 of each cylinder) connected to one side surface of the cylinder head 30 has a downstream end directed toward the cylinder head 30. A recess 15 is provided which opens when the intake manifold 31 is assembled to the cylinder head 30. The recess 15 forms the storage chamber 15.

According to the specific example, when the high-pressure air is stored in the storage chamber 15, the high-pressure air is cooled by air, and when the high-pressure air flows through the storage chamber port 15a, the cooling water passage 32 around the port 15a is closed. Water cooling is performed by the passing engine cooling water. Here, the storage chamber valve 16 is directly driven by the cam 22. Reference numeral 33 denotes a return spring.

In the case of a central ignition type engine in which the ignition plug 5 is arranged at the center of the combustion chamber 4, it is considered that the knocking occurs at the end gas zone on the intake side. Therefore, in this specific example, the storage chamber port 15a is opened in the end gas zone on the intake side.
Knock suppression accompanying scavenging can be made effective.

The cylinder head 30 shown in FIGS. 9 and 10 is for a three-valve DOHC type four-cylinder engine in which two intake valves 7, 7 and one exhaust valve 9 are arranged in each cylinder. For the two intake ports 6, 6, the storage chamber port 15a is opened on the upstream side in the flow direction of the swirl S generated in the combustion chamber 4, and the storage chamber port 15a is connected to the swirl S. It is oriented in the flow direction. Thereby, the outflow of the air in the storage chamber 15 by the swirl S is promoted, and it is possible to prevent the high-pressure air in the storage chamber 15 from directly flowing out to the exhaust port 8 without contributing to scavenging.

The ignition sequence of the engine 1 is shown in FIG.
, The order is No. 1 cylinder-No. 3 cylinder-No. 4 cylinder-No. 2 cylinder.

On the other hand, the storage chamber 15 is provided with a cylinder head 30.
Inside, two drill holes 4 extending in the longitudinal direction
0, 41, and the first drill hole 40 is No.
The common storage chamber 15 is used for one cylinder and No. 3 cylinder, and the second drill hole 41 is used as the common storage chamber 15 for No. 3 cylinder and No. 4 cylinder.

FIGS. 11 and 12 show another embodiment of the present invention. In the present embodiment, as shown in FIG. 11, an EGR passage 40 that recirculates a part of the exhaust gas to the intake system.
Is connected to a downstream portion of the intake passage 10, that is, in the vicinity of the intake port 6. The EGR control valve 4 is provided in the EGR passage 40.
The EGR control valve 41 has an actuator
An electromagnetic solenoid 42 is connected as a power supply.

In FIG. 11, reference numeral 45 denotes a control unit, and the control unit 45 is constituted by, for example, a microcomputer.
A ROM, a RAM and the like are provided. Signals from the sensors 50 to 52 are input to the control unit 45.

The sensor 50 detects the engine speed. The sensor 51 detects an engine load (opening of the throttle valve 11). The sensor 52 detects a crank angle.

The contents of the two controls performed by the control unit 45 will be described.
External EGR using 0 is performed in a light load region,
In the high load region, the EGR control valve 41 is closed and the external EGR is prohibited.

On the premise of the above, as shown in FIG. 12, the EGR control valve 41 is opened in the latter half of the intake stroke so that the EGR amount suitable for the engine operating state is returned to the intake system. ing.

Further, when acceleration is started before the EGR control valve 41 is opened in response to the detection of acceleration (abrupt opening operation of the throttle valve 11), the opening of the EGR control valve 41 is prohibited. On the other hand, when acceleration is started while the EGR control valve 41 is opened, the EGR
The control valve 41 is closed.

With the above configuration, first, it is possible to reduce the pumping loss by the external EGR using the EGR passage 40 in the light load operation state. Also in this light load operation region, scavenging is performed for each cycle using the storage chamber 15, so that a large change in internal EGR (residual gas) due to a change in intake negative pressure can be suppressed. Becomes Therefore, the operation state in the light load region can be stabilized by the EGR (control of the EGR gas amount) controlled by the EGR control valve 41.

Also, according to the start of acceleration, the EGR
Since the control valve 41 is closed, the difference between the actual ignition timing and the required ignition timing can be reduced. To explain this point in detail, first, in the light load steady operation state, the amount of burned gas flowing back to the intake system due to the intake negative pressure is large. On the other hand, in the full load steady operation state, the amount of burned gas flowing back into the intake system is small because the pipe pressure in the intake system is at atmospheric pressure. Therefore, at the time of light load operation, the residual gas in the combustion chamber 4 is quantitatively and proportionately large, while at the time of full load operation, the residual gas is quantitatively and proportionately small. The ignition timing is set based on the ratio of the residual gas in such a steady operation state.

However, when the acceleration is performed during the intake stroke, a large amount of fresh air is charged into the combustion chamber 4 together with the burned gas flowing back to the intake system. The residual gas ratio becomes different from the steady operation state, which causes a difference between the actual ignition timing and the required ignition timing.

Considering the above points, the residual gas amount is determined almost at the initial stage of the intake stroke. Therefore, scavenging is performed using high-pressure air in the storage chamber 15 in each cycle, and the EGR gas amount is controlled in the latter half of the intake stroke, so that steady operation or sudden acceleration can be achieved. It is possible to cope with it.

FIGS. 13 and 14 show another embodiment of the present invention. In this embodiment, a four-valve engine is provided with two intake ports 6 and two exhaust ports 8 for one cylinder, and one of the two intake ports 6 has a swivel port 6A. The other intake port 6B is a straight port.

The swirl port 6A and the straight port 6B are connected to independent independent intake passages 10A,
A shutter valve (S-valve) 43 is disposed in the independent intake passage 10B which is communicated with the inlet port 0B and communicated with the straight port 6B. The shutter valve 43 is opened and closed by an electromagnetic actuator 44. It has become.

The shutter valve 43 is controlled based on a control map shown in FIG. That is, the shutter valve 43 is opened on the high rotation side with the line L1 interposed therebetween, and intake is performed using the two intake ports 6A and 6B. On the other hand, on the low rotation side with the line L1 interposed therebetween, the shutter valve 43 is closed, and suction is performed using the swirl port 6A.

Assuming the above, the shutter valve 43
As shown in FIG. 14, the EGR passage 40 is closed in the low-speed low-load region II except for the idle region I, as shown in FIG.
Is performed using the EGR.

The timing of the external EGR will be described. The EGR control valve 41 is operated before the intake valve 7 is opened.
The opening and closing operation is performed. That is,
EGR gas is supplied to the lower end of the shutter valve 43 before the intake valve 7 is opened.

With the above structure, in the region II, before the intake valve 7 is opened, the intake passage 1 on the side of the straight port 6B is opened.
OB (downstream of the shutter valve 43) is filled with EGR gas, and the EGR gas increases the pressure in the pipe downstream of the shutter valve 43.

Therefore, with the opening operation of the intake valve 7,
First, the EGR gas is charged into the combustion chamber 4 from the straight port 6B, and then the fresh air is charged into the combustion chamber 4 from the swirl port 6A while generating swirl S.
As a result, in the combustion chamber 4, EGR gas is present in the lower layer, and fresh air is present in the upper layer. Can be improved.

In other words, while ensuring combustion stability, EG
In addition to being able to perform R, in addition to being able to further reduce the pumping loss by increasing the amount of EGR gas,
It is possible to improve or NO _x reduction in fuel consumption due to the expansion of the EGR region.

Although the embodiment of the present invention has been described above, the present invention may be applied to an engine with a turbocharger which uses supercharged exhaust energy. Further, the present invention may be applied to a supercharged engine including a mechanical supercharger mechanically driven by an engine output.

[0055]

As is apparent from the above description, according to the present invention, any of a naturally aspirated engine, an engine with a turbocharger, and a supercharged engine equipped with a mechanical supercharger can be used. Can be scavenged.

[Brief description of the drawings]

FIG. 1 is an explanatory view conceptually showing a mechanical configuration of the present invention.

FIG. 2 is a view showing an example of valve timing of a storage chamber valve according to the present invention.

FIG. 3 is a diagram showing another example of the valve timing of the storage chamber valve according to the present invention.

FIG. 4 is a plan view showing an operation stop mechanism of a storage chamber valve.

FIG. 5 is a cross-sectional view showing an operation stop state of the storage chamber valve.

FIG. 6 is a sectional view showing a state in which the operation of the storage chamber valve is permitted.

FIG. 7 is a diagram showing a specific example of a storage chamber and a storage chamber port formed in a cylinder head.

FIG. 8 is a sectional view taken along the line VIII-VIII shown in FIG. 7;

FIG. 9 is a view showing another specific example of a storage chamber and a storage chamber port formed in a cylinder head.

FIG. 10 is a sectional view taken along the line X10-X10 shown in FIG. 9;

FIG. 11 is a sectional view showing another embodiment of the present invention.

FIG. 12 shows valve timing and external E of a storage chamber valve.
The figure which shows the timing of EGR using a GR passage.

FIG. 13 is an overall configuration diagram of an engine showing a modified example related to external EGR.

FIG. 14 shows a shutter valve and an external EG disposed in an intake system.
4 is a control map used for controlling an EGR control valve interposed in the R passage.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine 3 Piston 4 Combustion chamber 6 Intake port 7 Intake valve 8 Exhaust port 9 Exhaust valve 10 Intake passage 15 Storage chamber 15a Storage chamber port 16 Storage chamber valve 40 EGR passage 41 EGR control valve 43 Shutter valve 45 Control unit

Continued on the front page (51) Int.Cl. ⁷ Identification code FI F02M 25/07 570 F02M 25/07 570Z (72) Inventor Toshihiko Hattori 3-1, Fuchu-cho, Shinchu, Aki-gun, Hiroshima Prefecture Mazda Motor Corporation (56 References JP-A-55-131521 (JP, A) JP-A-54-77811 (JP, A) JP-A-62-191615 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB Name) F02B 21/00-23/10

Claims (12)

(57) [Claims] 1. A storage chamber formed in an engine main body and opening to a combustion chamber, and a storage chamber valve for opening and closing an opening of the storage chamber, wherein the storage chamber valve is opened at the end of an exhaust stroke. An engine that is closed in a compression stroke. 2. The engine according to claim 1, wherein the storage chamber valve is opened before an intake valve is opened. 3. The storage chamber valve according to claim 1, wherein the storage chamber valve is opened during a valve overlap period in which both an exhaust valve and an intake valve are opened. The engine is set when the valve lift is greater than the intake valve lift. 4. The storage chamber valve according to claim 1, wherein the storage chamber valve is opened at the end of an exhaust stroke, and then the valve is kept open and closed during a compression stroke. engine. 5. The first storage valve according to claim 1, wherein the storage chamber valve is opened and closed at the end of an exhaust stroke.
And a second opening and closing operation in which the valve is opened during the latter half of the intake stroke and then closed during the compression stroke. 6. The storage chamber valve according to claim 1, wherein the storage chamber valve is opened and closed at the end of an exhaust stroke.
An opening / closing operation of the engine and a second opening / closing operation of opening and closing during a compression stroke after the intake valve is closed. 7. The storage chamber valve according to claim 1, wherein the storage chamber valve is opened at the end of an exhaust stroke and closed at an early stage of an intake stroke, and opened at a latter half of the intake stroke. An engine that performs a second opening / closing operation that is closed during a post-compression stroke. 8. The first opening / closing operation according to claim 1, wherein the storage chamber valve is opened at the end of an exhaust stroke and closed at an early stage of an intake stroke, and a compression stroke after the intake valve is closed. And a second opening / closing operation that is opened / closed inside. 9. An EGR passage for recirculating a part of the exhaust gas of an engine to an intake system, an EGR control valve interposed in the EGR passage, and An EG that opens the EGR control valve in the latter half of the intake stroke
R timing control means. 10. The engine according to claim 1, wherein the engine is a naturally-aspirated engine. 11. The supercharged engine according to any one of claims 1 to 9, wherein the engine is a supercharged engine including a turbocharger driven by exhaust gas energy.
An engine characterized by that. 12. The supercharged engine according to claim 1, wherein the engine is a supercharged engine provided with a mechanical supercharger driven by an engine output. And engine.