JPH11280476A - Subchamber engine - Google Patents

Abstract

(57) [PROBLEMS] To provide an engine operation without changing a compression ratio by dividing a sub-chamber provided in a cylinder head into upper and lower sub-chambers partially connected by a movable partition plate. A sub-chamber engine capable of obtaining a fuel injection space according to a load is obtained. SOLUTION: A sub chamber 7 arranged in a cylinder head 3 is provided.
The upper and lower subchambers 15, 16 are separated by a partition plate 17.
It is divided into. The partition plate 17 is moved up and down by the actuator 30 according to the magnitude of the operation load of the engine, and changes the volume of the lower sub-chamber 16 into which the fuel is injected from the fuel injection nozzle 9. 2
0 and the communication hole 21 partially communicate the upper and lower subchambers 15 and 16, so that the compression ratio does not change. Upper subchamber 1
The pressure of 5 helps discharge gas in the lower sub-chamber 16 to the main chamber 11 through the communication hole 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sub-chamber engine in which a sub-chamber arranged in a cylinder head and a main chamber formed on a cylinder side are connected by a communication hole.

[0002]

2. Description of the Related Art Conventionally, as a combustion type sub-chamber type engine having a sub-chamber provided in a cylinder head, for example, a swirl chamber type or a pre-chamber type engine is known. The sub-chamber type diesel engine applied to the diesel engine is easier to control the equivalence ratio than the direct injection type diesel engine.
That is, it has a feature that generation of NOx can be suppressed.

In a swirl chamber type combustion chamber, a sub-chamber formed in a cylinder head is largely eccentric from the center axis of the cylinder to form a high-speed swirl in the sub-chamber, and fuel is sprayed onto the swirl so as to carry fuel spray. The air-fuel mixture is formed in the sub-chamber and is jetted obliquely from the communication hole as a jet while burning part of the air-fuel mixture, and is mixed with air existing in the main chamber and burned. In the sub-chamber engine, the air-fuel mixture injected into the main chamber needs to be mixed with the air in the main chamber while traversing almost the diameter of the cylinder. in which generation of the NO _X is reduced to the chamber combustion. In this sub-chamber engine, the intake air introduced from the main chamber into the sub-chamber is introduced through a communication hole formed tangentially to the sub-chamber, so that a strong swirl flow is formed in the sub-chamber. . The fuel injected into the sub-chamber is mixed and agitated by a strong swirl and a two-dimensional flow generated by the swirl flow.

[0004] In the pre-chamber type combustion chamber, the sub-chamber is arranged substantially at the center of the cylinder, and the shape of the sub-chamber is elongated vertically. This sub-chamber engine generates fuel-air mixture by injecting fuel into the sub-chamber, similar to the swirl chamber type described above, but does not form a swirl in the sub-chamber. The turbulence of air is formed in the sub-chamber by the air flow, and mixing is achieved. By arranging the sub-chamber almost in the center of the cylinder and by providing a plurality of communication holes radially around the main chamber to connect the sub-chamber and the cylinder side, the flame reach to the cylinder outer wall is shortened. Fuel efficiency can be improved.

Further, as a sub-chamber type engine, there is one disclosed, for example, in Japanese Patent Application Laid-Open No. 3-242420.
This sub-chamber type engine is constructed so that the volume of the sub-chamber can be changed, and the volume of the sub-chamber is reduced during partial load to burn in a fuel-rich state. Even if the air is introduced, combustion rich combustion is performed, NOx generation is suppressed, and good combustion is performed.

However, in the sub-chamber type engine having the structure disclosed in the above-mentioned publication, although the volume of the sub-chamber can be made variable, since the sub-chamber is constructed in a sealed state, the volume of the sub-chamber is reduced. The sliding part of the moving cylinder that slides inside the sub-chamber wall must be securely sealed to prevent air-fuel mixture leakage, and the structure of the sub-chamber exposed to high temperatures is complicated. Become. Furthermore, in the sub-chamber engine of this structure,
Changing the volume of the sub-chamber also changes the compression ratio in the sub-chamber. That is, since the sub-chamber is configured so that the periphery is hermetically sealed, if the volume of the sub-chamber is reduced when the operating load of the engine is a partial load (low load), the compression ratio in the sub-chamber at the compression top dead center is high. If the capacity of the sub-chamber is increased when the load is high, the compression ratio becomes low, and it becomes difficult to control the ratio between the compressed air and the fuel, that is, the equivalent ratio.

[0007]

Therefore, in the sub-chamber engine, when changing the volume of the sub-chamber, the fuel injection region and the region where fuel is not injected are communicated with the fuel injection region in the sub-chamber. In this way, the volume of the fuel injection area in the sub-chamber can be changed according to the operating load of the engine without changing the compression ratio in the sub-chamber, and the formation and combustion of the rich mixture in the fuel injection area The problem to be solved is to maximize the function of the sub-chamber by pushing out the rich mixture that started combustion using the pressure in the area where fuel is not injected into the main chamber on the cylinder side. is there.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and to make it possible to change the volume in a fuel injection region in which the formation and combustion of the rich mixture are performed together with the operating load of the engine. At the same time, the control of the equivalence ratio over the entire engine operating load range is facilitated, the low NOx combustion is performed in the rich mixture state in the fuel injection region, and the main combustion chamber is designed to prevent unburned gas and fuel from remaining in the sub-chamber. It is an object of the present invention to provide a sub-chamber engine in which the fuel is sent into a room, agitated well with air, and the injected fuel is efficiently consumed.

The present invention is configured as follows to achieve the above object. That is, the present invention provides a sub-chamber disposed in a cylinder head, a communication hole formed in the sub-chamber and communicating the sub-chamber with a main chamber on the cylinder side, and connecting the sub-chamber to an upper sub-chamber and the upper sub-chamber. A partition plate that partially communicates with a lower sub-chamber provided with the communication hole, a fuel injection nozzle that injects fuel into the lower sub-chamber, and the partition plate that is moved in accordance with an operating load of an engine, An actuator for changing the volume ratio between the upper sub-chamber and the lower sub-chamber,
And a sub-chamber engine comprising:

In the sub-chamber structure of the sub-chamber engine, the actuator increases the volume of the lower sub-chamber when the operating load of the engine is high, and when the operating load of the engine is low, The partition plate is moved so as to reduce the volume of the lower sub-chamber.

Further, the sub-chamber structure of the sub-chamber engine further includes a detecting means for detecting an operation load of the engine, and a controller for outputting a control signal for operating the actuator. The control signal is output based on the operating load of the engine detected by the means.

In the sub-chamber structure of the sub-chamber engine, the upper sub-chamber and the lower sub-chamber may be provided with a communication hole formed in the partition plate or between the partition plate and a peripheral wall of the sub-chamber. Are partially communicated with each other through a gap formed at the bottom.

The sub-chamber structure of the sub-chamber engine according to the present invention is constructed as described above, and operates as follows. That is, in this sub-chamber type engine, the sub-chamber arranged in the cylinder head is connected to the upper sub-chamber and the upper sub-chamber by the partition plate so that the sub-chamber is partially communicated with the upper sub-chamber and can communicate with the main chamber on the cylinder side. It is partitioned into a lower sub-chamber with holes. Since the fuel injection nozzle injects fuel into the lower sub-chamber, the fuel is only slightly dispersed in the upper sub-chamber separated by the partition plate. The actuator moves the partition plate according to the operating load of the engine to change the ratio of the volumes of the upper sub chamber and the lower sub chamber. Therefore, the volume of the lower sub-chamber where the fuel is injected by the fuel injection nozzle to form the rich mixture can be changed according to the operating load of the engine because the actuator moves the partition plate. Moreover, since the partition plate partitions the upper sub-chamber and the lower sub-chamber so as to partially communicate with each other, the volume of the entire sub-chamber does not change. Therefore, the compression ratio of the lower sub-chamber into which fuel is injected does not change according to the magnitude of the operating load of the engine. Further, in the expansion stroke, the fuel-rich mixture formed in the lower sub-chamber is smoothly moved toward the main chamber by the air pressure in the upper sub-chamber.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a sub-chamber engine according to the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing an embodiment of a sub-chamber engine according to the present invention when the engine is in an operation state corresponding to a low-load operation state of the engine. FIG. FIG. 3 is a cross-sectional view showing an operation state in the state, and FIG. 3 is a cross-sectional view taken along the line AA in FIG.

The sub-chamber type engine 1 is disposed in a cavity 5 formed in a cylinder head 3 and a cylinder head 3 which are fixed to a cylinder block 2 with a gasket 4 interposed therebetween and forms a sub-chamber 7 therein. Member 6, sub chamber member 6
An injector is provided in the cylinder head 3 and penetrates through the through hole 8 formed in the upper part of the cylinder to inject fuel into the sub-chamber 7, that is, formed in the fuel injection nozzle 9 and the sub-chamber member 6. It has a communication hole 10 that is located on the side 12 and communicates with the main chamber 11 formed above the piston 13.

The sub-chamber 7 is divided into an upper sub-chamber 15 and a lower sub-chamber 16 by a partition plate 17 provided in the sub-chamber member 6. FIG. 3 is a sectional view of the partition plate 17. The partition plate 17 is a substantially circular plate having a circular outer peripheral end 19 along the inner peripheral wall 14 of the sub-chamber member 6 as a whole, and has a size in the center where the tip of the fuel injection nozzle 9 can penetrate. A through hole 18 is formed. An injection hole 9a formed at the tip of the fuel injection nozzle 9 penetrates the through hole 18 of the partition plate 17 and opens in the lower sub-chamber 16, and the fuel injected from the injection hole 9a passes through the sub-chamber. The fuel is injected toward the inner peripheral wall 14 of the member 6. Upper subchamber 15
The lower sub-chamber 16 is separated from the lower sub-chamber 16 by a partition plate 17. A gap 20 formed between the inner peripheral wall 14 of the sub-chamber member 6 and the outer peripheral end 19 of the partition plate 17, and the partition plate 17.
Are communicated through a plurality of communication holes 21 (only some of which are denoted by reference numerals) formed at intervals around the through hole 18.

The axes of the sub-chamber member 6 and the fuel injection nozzle 9 are arranged centrally so as to coincide with the central axis of the cylinder 12. Further, a communication hole 10 that connects the lower sub-chamber 16 and the main chamber 11 is also arranged radially around the central axis of the cylinder 12. Therefore, when the air above the piston 13 enters the lower sub-chamber 16, the lower sub-chamber 16
It is not specifically intended that swirl occur in the air. The number and arrangement of the communication holes 21 of the partition plate 17 may be formed according to the number and arrangement of the communication holes 10, but are not necessarily limited thereto. Although not shown, an intake / exhaust port is formed in the cylinder head 3, and an intake / exhaust valve is disposed in the intake / exhaust port. The main chamber 11 includes, for example, a space formed by the cylinder 12 formed by the cylinder liner 23 fitted in the hole 22 of the cylinder block 2 and the lower surface 24 of the cylinder head, or a recess 25 formed by the piston 13. Is what is done.

Although not shown, the sub-chamber member 6 is fixed to the cylinder head 3 by a fixing fitting, shrink fitting, press fitting, or the like. A heat insulating air layer is formed between the outer surface of the sub-chamber member 6 and the inner surface of the cavity 5 of the cylinder head 3 to improve the degree of heat insulation of the sub-chamber 7 including the upper sub-chamber 15 and the lower sub-chamber 16. be able to. The lower surface of the sub-chamber member 6 constitutes a part of the cylinder head lower surface 24, and the lower surface of the sub-chamber member 6 has a plurality of communication holes communicating the lower sub-chamber 16 with the main chamber 11 formed on the cylinder 12 side. 10 is formed to be inclined from the lower sub-chamber 16 toward the cylinder periphery. Moreover, the communication holes 10 are mutually inclined in the direction of diffusion from the lower sub-chamber 16 to the main chamber 11, and are formed so as to be spaced from each other in the direction around the sub-chamber central axis CC.

This sub-chamber engine is characterized by the relationship between the structure of the sub-chamber 7 and the partition plate 17. In this sub-chamber type engine, in particular, a partition plate 17 for partitioning the upper sub-chamber 15 and the lower sub-chamber 16 can be moved so that the ratio of the volume of the upper sub-chamber 15 to the volume of the lower sub-chamber 16 is variable. And the partition plate 17 comprises an upper sub-chamber 15 and a lower sub-chamber 16.
Are partially communicated with each other. Since the communication hole 10 of the sub-chamber member 6 is provided in the radial direction and the communication hole 21 of the partition plate 17 is also provided in parallel with the center axis C-C, the air from the main chamber 11 is compressed during the compression stroke. The lower sub-chamber 16 and the upper sub-chamber 15 are formed without forming a swirl.
And invade into.

The combustion in the sub-chamber 7 is performed in the lower sub-chamber 16. The fuel injected into the lower sub-chamber 16 is
The air mixes with the air inside, and forms an over-enriched air-fuel mixture, which gathers in the lower sub-chamber 16, especially near the outlet of the communication hole 10, and hardly disperses to the upper sub-chamber 15. Even after ignition, the fuel burns in a relatively low-temperature rich mixture state rather than in a high-temperature lean burn, so that the amount of generated NOx is small. On the other hand, the upper sub-chamber 15 has an air layer or a lean mixture in which fuel is slightly mixed. In this case, stratified combustion is performed.

Next, when the combustion cycle of the engine shifts to the expansion stroke simultaneously with the start of combustion in the sub-chamber 7, the fuel and unburned gas present in the lower sub-chamber 16 are subjected to the pressure and pressure generated as a result of their own combustion. Due to the pressure of the air layer in the upper sub chamber 15 or the air-fuel mixture in stratified combustion, the air is quickly and quickly pushed out to the main chamber 11 having a large amount of air through the communication hole 10. Lower subchamber 16 of subchamber 7
The unburned air-fuel mixture remaining inside hardly disappears, and the combustion period in the main chamber 11 is shortened to complete the combustion. As a result, N
O _X, and reduce the occurrence of smoke or the like, is up the thermal efficiency, it is possible to improve the fuel consumption.

The actuator 30 for moving the partition plate 17 utilizes an electromagnetic solenoid. A lifting rod 31 is connected to the partition plate 17 at a position offset from the center, and the lifting rod 31 is guided by a guide 32 mounted in a mounting hole 33 of the cylinder head 3 and can be raised and lowered. An armature 34 is fixed to the uppermost part of the lifting rod 31, and the top surface 2 of the cylinder head 3 is fixed.
Solenoid 3 of actuator 30 attached to 6
5 sucks the armature 34. A spring 36 is interposed between the armature 34 and the fixed frame 37 of the actuator 30. The controller 40 outputs a control signal to the actuator 30 based on the detection output of the sensor 38 for detecting the accelerator opening and the sensor 39 for detecting the engine speed.

The controller 40 controls each of the sensors 38,
When the controller 40 determines that the operating load of the engine is low based on the signal from the controller 39, the controller 40 stops supplying power to the solenoid 35 of the actuator 30.
At this time, the spring 36 pushes down the armature 34, and the partition plate 17 descends via the lifting rod 31, and
The volume of the lower sub-chamber 16 is reduced, and the volume of the upper sub-chamber 15 is increased. Since the compression ratio in the sub-chamber 7 is constant irrespective of the position of the partition plate 17, the compression ratio does not become too high when the volume of the lower sub-chamber 16 is reduced, and the low load operation state is maintained. However, a rich air-fuel mixture can be obtained in the lower sub-chamber 16 with the fuel injection amount suppressed.
When the controller 40 determines that the operating load of the engine is high based on the signals from the sensors 38 and 39, the controller 40 supplies power to the solenoid 35 of the actuator 30 and opposes the spring 36. The armature 34 is raised, and the partition plate 17 is raised via the lifting rod 31. As a result, the volume of the lower sub-chamber 16 of the sub-chamber 7 increases, and the volume of the upper sub-chamber 15 decreases.
The state of the engine at this time is shown in FIG.

Since the sub-chamber engine 1 is configured as described above, it operates as follows. That is, in the sub-chamber engine 1, in the compression stroke in which the piston 13 rises, the intake air is compressed and
The swirl in the lower sub-chamber 16 hardly occurs because the communication hole 10 is set in the radial direction. Next, the air flowing into the lower sub-chamber 16 is separated from the lower sub-chamber 16 by a gap 2 around the partition plate 17.
0 and into the upper sub chamber 15 through the communication hole 21.
Also in this case, no swirl is formed in the upper sub chamber 15.

Next, near the end of the compression stroke, fuel is injected from the multiple injection holes 9a of the fuel injection nozzle 9. The fuel spray injected from the fuel injection nozzle 9 is set to be directly injected toward the inner peripheral wall 14 of the sub chamber 7. Then, the fuel spray mixes with the air introduced into the lower sub-chamber 16 through the communication hole 10 and ignites and burns. Even if the partition plate 17 partially communicates with the upper sub-chamber 15 through the gap 20 and the communication hole 21, strong combustion does not occur in the upper sub-chamber 15 because the amount of fuel in the upper sub-chamber 15 is small. The gas pressure in the upper sub-chamber 15 rises rapidly with the combustion of the lower sub-chamber 16. On the other hand, the combustion gas and the unburned fuel spray in the lower sub-chamber 16 are mixed with air to form a mixture, and the mixture is pushed out by the gas whose pressure has increased in the upper sub-chamber 15 and the communication hole 10 is pushed out. Through the main chamber 11.

Next, the gas such as the flame and the unburned mixture injected into the main chamber 11 extends the penetration in the main chamber 11 having a large air mass to achieve mixing with the fresh air, thereby completing the combustion. Therefore, in the pre-combustion chamber engine, the combustion state of the rich air-fuel mixture in the lower sub-chamber 16 of the auxiliary chamber 7 is started, the less amount of generation of NO _X, suppressing the occurrence of such Sumuku engine Output can be increased to improve thermal efficiency and improve fuel efficiency.

In the embodiment shown in FIG. 1, the auxiliary chamber 7, the combustion injection nozzle 9 and the communication hole 10 are connected to the central axis C-
It is arranged evenly or symmetrically on C or around the central axis CC, but is not limited to this, and the sub chamber 7 and the fuel injection nozzle 9 are arranged at a position eccentric from the center line of the cylinder 12. Similarly, the partition plate is moved according to the operating load of the engine to change the volume of the lower sub-chamber, control the equivalent ratio in the lower sub-chamber, and use the gas pressure of the upper sub-chamber. Thus, the air-fuel mixture can be discharged from the lower sub chamber to the main chamber on the cylinder side. Further, the operating load of the engine is detected based on the operating state of the engine, but a target fuel injection amount provided based on the accelerator opening and the engine speed can be detected as the engine load. In addition, other parameters (for example, intake pressure) can be used as needed. Further, the actuator of the partition plate is constituted by an electromagnetic solenoid, but other driving means can be adopted. For example, a cam spring may be used for pushing down the partition plate and using a force of a cam to push up and return with a spring. Furthermore, in the above embodiment, even if the partition plate 17 occupies the lowest position,
The fuel injection nozzle 9 has an injection hole 9a opened in the lower sub-chamber 16 and directly injects fuel toward the peripheral wall of the lower sub-chamber 16, but the partition plate 17 is lowered most and the lower sub-chamber 16 1
In a state where the volume of the nozzle 6 is the smallest, the injection hole 9a occupies the position facing the through hole 18 and the height from which the fuel from the injection hole 9a can be injected into the lower sub-chamber 16 through the through hole 18. It is clear that the fuel injection nozzle 9 may be arranged such that

[0028]

The sub-chamber engine according to the present invention is configured as described above and has the following effects. That is, in this sub-chamber type engine, the sub-chamber arranged in the cylinder head is divided into an upper sub-chamber and a lower sub-chamber by a partition plate, and the lower sub-chamber and the main chamber are communicated by a communication hole. The sub-chamber and the lower sub-chamber are partially connected to each other through the communication hole or the surrounding gap, and the fuel is injected from the injection hole of the fuel injection nozzle to the lower sub-chamber. The ratio of the volume to the chamber can be changed according to the operating load of the engine, and the compression ratio in the lower sub-chamber can be changed by the movement of the partition plate by the partial communication between the upper sub-chamber and the lower sub-chamber. Since it does not change, it is easy to control the equivalence ratio between fuel and air, and the upper sub-chamber can be formed into a lean mixture state and the lower sub-chamber can be formed into a rich mixture state. The fuel in the sub chamber ignites and the engine After the burn cycle is shifted to the expansion stroke, the lower sub-chamber of the combustion gas, a gas containing unburned gas and fuel and air by the gas pressure in the upper sub-chamber and rapidly discharged into the main chamber through the communication hole. Therefore, the rich mixture formation region in the sub-chamber is appropriately controlled in accordance with the operation load of the engine, and the NOx reduction in the entire operation region is achieved. Also, since fuel is ignited in the rich mixture atmosphere in the upper sub-chamber, the amount of NOx generated is reduced, and the amount of combustion gas, unburned gas and fuel remaining in the lower sub-chamber is reduced, and fuel is efficiently consumed. Consumed.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a sub-chamber engine according to the present invention.

FIG. 2 is a sectional view showing an operation state when the sub-chamber engine shown in FIG. 1 is in a high-load operation state.

FIG. 3 is a sectional view taken along the line AA in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sub chamber type engine 2 Cylinder block 3 Cylinder head 5 Cavity 6 Sub chamber member 7 Sub chamber 9 Fuel injection nozzle 9a Injection hole 10 Communication hole 11 Main chamber 12 Cylinder 13 Piston 14 Inner peripheral wall 15 Upper sub chamber 16 Lower sub chamber 17 Partition Plate 20 Clearance 21 Communication hole 24 Lower surface of cylinder head 25 Depression 30 Actuator 40 Controller

Claims (4)

[Claims] 1. A sub-chamber disposed in a cylinder head, a communication hole formed in the sub-chamber and communicating the sub-chamber with a main chamber on the cylinder side, and the sub-chamber being partially connected to an upper sub-chamber and the upper sub-chamber. A partition plate which is in communication with the lower sub-chamber provided with the communication hole, a fuel injection nozzle for injecting fuel into the lower sub-chamber,
And an actuator for moving the partition plate according to the operating load of the engine to change the volume ratio between the upper sub-chamber and the lower sub-chamber. 2. The actuator according to claim 1, wherein the actuator increases the volume of the lower sub-chamber when the operating load of the engine is high, and decreases the volume of the lower sub-chamber when the operating load of the engine is low. 2. The sub-chamber engine according to claim 1, comprising moving the partition plate. A detecting means for detecting an operating load of the engine; and a controller for outputting a control signal for operating the actuator, wherein the controller is configured to detect the operating load of the engine based on the operating load detected by the detecting means. Outputting the control signal in response to the control signal.
Or the sub-chamber engine according to 2. 4. The partial communication between the upper sub-chamber and the lower sub-chamber through a communication hole formed in the partition plate or a gap formed between the partition plate and a peripheral wall of the sub-chamber. The sub-chamber engine according to claim 1, wherein: