WO2024201934A1 - Internal combustion engine with auxiliary combustion chamber - Google Patents

Abstract

The present invention provides an internal combustion engine having an auxiliary combustion chamber 43 partitioned from a main combustion chamber 41 in a cylinder by a partition wall 42 provided to a cylinder head 34 and having communicating passages 44a, 44b provided in the partition wall 42 to connect the auxiliary combustion chamber 43 with the main combustion chamber 41, wherein the first communicating passage 44a is provided in a lateral surface of the partition wall 42 on an intake valve 32 side, and the partition wall 42 is formed such that the internal auxiliary combustion chamber 43 extends along an axis CL2 on which the side away from the piston is inclined toward the intake valve 32 side relative to an axis CL1 of the cylinder.

Description

Internal combustion engine with auxiliary combustion chamber

The present invention relates to an internal combustion engine having a secondary combustion chamber within a main combustion chamber.

Many internal combustion engines, such as gasoline engines used in automobiles, have an injector (fuel injection device) that injects fuel into the intake passage or combustion chamber, and a spark plug that is positioned facing the combustion chamber inside the cylinder.

Patent Document 1 discloses an internal combustion engine equipped with a secondary combustion chamber within a combustion chamber (main combustion chamber). In the internal combustion engine described in Patent Document 1, a mixture with a relatively high fuel concentration is supplied to the secondary combustion chamber, and the mixture in the secondary combustion chamber is ignited by an ignition plug, causing a flame to be injected (ejected) from the secondary combustion chamber into the main combustion chamber and burn the mixture in the main combustion chamber. This makes it possible to improve the ignition of the mixture in the main combustion chamber and increase the output of the internal combustion engine, or to reduce the fuel concentration in the main combustion chamber and improve fuel efficiency.

Furthermore, Patent Document 1 discloses an internal combustion engine that is provided with a plurality of nozzle holes for injecting flame from an auxiliary combustion chamber, and is configured so that the flame is injected radially toward the cylinder wall surface.
Moreover, Patent Document 2 discloses an internal combustion engine having a first chamber and a second chamber in a combustion chamber, and generating a tumble flow in the combustion chamber.

JP 2019-31961 A Japanese Patent Application Publication No. 5-44470

However, in an internal combustion engine with a structure in which flame is propagated from the auxiliary combustion chamber to the main combustion chamber as in Patent Document 1, and an internal combustion engine that generates a tumble flow in the combustion chamber (main combustion chamber) as in Patent Document 2, if there is a nozzle that sprays flame in the opposite direction to the direction of movement of the tumble flow, the spray of flame from that nozzle may be hindered, and the propagation of flame within the main combustion chamber may be partially suppressed.

The present invention has been made to solve these problems, and aims to provide an internal combustion engine with an auxiliary combustion chamber that promotes combustion in the main combustion chamber in an internal combustion engine that has an auxiliary combustion chamber and generates a tumble flow of intake air in the main combustion chamber.

In order to achieve the above object, the internal combustion engine with an auxiliary combustion chamber of the present invention comprises: a main combustion chamber formed in a cylinder by a cylinder head, a cylinder block, and a piston; an auxiliary combustion chamber partitioned from the main combustion chamber by a partition wall provided in the cylinder head; a fuel injection device that supplies fuel to the main combustion chamber and the auxiliary combustion chamber; an ignition plug that ignites fuel in the auxiliary combustion chamber; and an intake valve and an exhaust valve arranged on either side of the auxiliary combustion chamber in the cylinder head, the internal combustion engine with an auxiliary combustion chamber being provided with a communication passage in the partition wall that connects the auxiliary combustion chamber with the main combustion chamber, the communication passage having a first communication passage provided on a side of the partition wall facing the intake valve, and the auxiliary combustion chamber is formed so that the side opposite the piston with respect to the axis of the cylinder extends along an axis that is inclined toward the intake valve side.
As a result, by inclining the auxiliary combustion chamber toward the intake valve side, a swirling flow of the mixture containing the fuel flowing in from the communication passage is generated in the auxiliary combustion chamber, and the fuel concentration of the mixture on the intake valve side in the auxiliary combustion chamber can be increased. Therefore, the flame generated by ignition in the auxiliary combustion chamber can be strongly injected from the first communication passage to the intake side of the main combustion chamber against the tumble flow of the intake air in the main combustion chamber. This allows the flame to propagate to the part on the intake valve side where the flame has difficulty propagating due to the tumble flow in the main combustion chamber, and improves combustibility in the main combustion chamber.

Preferably, the fuel injection device is disposed facing the intake valve side of the main combustion chamber and injects fuel toward the auxiliary combustion chamber.
As a result, the penetration force of the fuel injected from the fuel injection device makes it easier for the fuel to flow into the first communication passage, which allows a rich mixture to be supplied to the auxiliary combustion chamber and strengthens the swirling flow within the auxiliary combustion chamber, thereby increasing the momentum of the flame generated in the auxiliary combustion chamber and enabling a strong flame to be injected into the main combustion chamber, particularly toward the intake valve.

Preferably, a plurality of the communication passages are provided including the first communication passage, and the first communication passage is formed to have a larger passage diameter than the other communication passages.
This allows the fuel injected from the fuel injection device to easily flow into the first communication passage, strengthening the swirling flow in the auxiliary combustion chamber. Also, the flame generated in the auxiliary combustion chamber is injected from each communication passage into the main combustion chamber, and the amount of flame injected from the first communication passage toward the intake valve can be increased. This makes it easier for the flame to propagate to the intake valve side of the main combustion chamber against the tumble flow.

Preferably, a plurality of the communication passages are arranged in the partition wall and aligned in the circumferential direction.
This allows multiple flames to be injected from the auxiliary combustion chamber into the main combustion chamber so as to spread, and the flames can be propagated widely within the main combustion chamber, thereby further improving combustibility in the main combustion chamber.

Preferably, the communication passages are arranged at equal intervals.
This allows multiple flames to be injected from the auxiliary combustion chamber into the main combustion chamber so that they spread evenly radially, allowing the flames to propagate more evenly within the main combustion chamber, further improving combustibility in the main combustion chamber.

　According to the internal combustion engine with auxiliary combustion chamber of the present invention, a swirling flow can be generated in the auxiliary combustion chamber, which increases the fuel concentration especially on the intake valve side and ignites it, and a strong flame can be injected from the first communication passage to the intake valve side of the main combustion chamber. This allows the flame to be supplied against the tumble flow in the main combustion chamber and propagates evenly within the main combustion chamber, improving combustibility in the main combustion chamber and improving power and fuel efficiency.

1 is a configuration diagram of an intake and exhaust system of an internal combustion engine according to an embodiment of the present invention; FIG. 2 is a top view of a cylinder in the internal combustion engine of the present embodiment. FIG. 4 is a vertical cross-sectional view of the inside of a cylinder showing a fuel injection state. FIG. 4 is a vertical cross-sectional view showing a detailed structure of an upper part of the cylinder. FIG. 4 is a vertical cross-sectional view of an upper part of a cylinder, showing a state of fuel movement within an auxiliary combustion chamber. FIG. 4 is a vertical cross-sectional view of the upper part of the cylinder, showing the fuel concentration in the auxiliary combustion chamber and the flame injection state into the main combustion chamber.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a configuration diagram of an intake and exhaust system of an internal combustion engine 1 (an internal combustion engine with an auxiliary combustion chamber) according to one embodiment of the present invention.

As shown in FIG. 1, the internal combustion engine 1 of this embodiment is a direct injection type gasoline engine having an injector 3 (fuel injection device) that injects gasoline, which is a fuel, into a combustion chamber.
In the intake passage 5 of the internal combustion engine 1 of this embodiment, an air cleaner 6, an intercooler 7, and a throttle valve 8 are provided upstream of the intake port 2 along the flow of intake air. In the exhaust passage 11 of the internal combustion engine 1, an upstream side exhaust purification catalyst 12 and a downstream side exhaust purification catalyst 13 are provided along the flow of exhaust gas from the exhaust port 31.

The internal combustion engine 1 is also equipped with a turbocharger 15 and an EGR system 16 .
The EGR system 16 includes an EGR passage 20 that connects the exhaust passage 11 and the intake passage 5 of the internal combustion engine 1, an EGR valve 21 that changes the flow area of the EGR passage 20, and an EGR cooler 22 that cools the exhaust passing through the EGR passage 20. The EGR passage 20 connects the exhaust passage 11 between the upstream side exhaust purification catalyst 12 and the downstream side exhaust purification catalyst 13, and the intake passage 5 between the air cleaner 6 and the compressor of the turbocharger 15.

Fig. 2 is a top view of the inside of a cylinder 30 in the internal combustion engine 1 of this embodiment. Fig. 3 is a vertical cross-sectional view of the inside of the cylinder showing a fuel injection state.
2, the internal combustion engine 1 is provided with two intake ports 2 and two exhaust ports 31 for each cylinder 30. Furthermore, each of the two intake ports 2 is provided with an intake valve 32, and each of the two exhaust ports 31 is provided with an exhaust valve 33.

In the upper portion (cylinder head 34) of a cylinder 30 of the internal combustion engine 1, two intake ports 2 are arranged side by side on one side with the center portion in between, and two exhaust ports 31 are arranged side by side on the other side.
The injector 3 is provided in the cylinder head 34, one for each cylinder, and is disposed at a circumferential position between the two intake ports 2. The injector 3 is disposed so as to inject fuel toward the upper center of the combustion chamber.

An ignition plug 35 (ignition device) is provided in the center of the cylinder head 34.
In the cylinder 30, a main combustion chamber 41 is provided, which is a substantially cylindrical space surrounded by a cylinder block 36, a cylinder head 34, and a piston 37, and a sub-combustion chamber 43 is provided in the upper center of the main combustion chamber 41. Specifically, a partition wall 42 is provided in the cylinder head 34 so as to surround the center electrode of the ignition plug 35, and the portion surrounded by the partition wall 42 in the main combustion chamber 41 becomes the sub-combustion chamber 43. The main combustion chamber 41 has a substantially cylindrical cross section taken along a plane perpendicular to the moving direction of the piston 37. The partition wall 42 is formed in a cylindrical shape that protrudes downward (toward the piston 37) from the ignition plug 35, has a substantially hemispherical lower part, and is disposed so as to cover the center electrode 35a and the ground electrode 35b of the ignition plug 35. The center electrode 35a of the ignition plug 35 is located in the upper center of the sub-combustion chamber 43, i.e., at the upper part within the partition wall 42 and on the central axis.

The partition wall 42 is provided with a plurality of communication passages 44 a , 44 b , 44 c that connect the main combustion chamber 41 and the auxiliary combustion chamber 43 .
The operation of the internal combustion engine 1 is controlled by a control unit 50 (control section).

The unit 50 is composed of an output device, a storage device (ROM, RAM, non-volatile RAM, etc.), a central processing unit (CPU), etc. The control unit 50 acquires the crank angle, intake volume, exhaust temperature, EGR gas volume, etc., and controls the operation of the injector 3, the spark plug 35, the throttle valve 8, the EGR valve 21, etc.

As shown in Figures 2 to 4, the partition wall 42 and spark plug 35 of this embodiment are positioned near the central axis of the cylinder 30, with their upper portions inclined toward the intake side (intake valve 32 side) with respect to the axis CL1 of the cylinder 30 (the central axis of the main combustion chamber 41). In other words, the central axis CL2 of the partition wall 42 and the auxiliary combustion chamber 43 therein are inclined toward the intake side with respect to the axis CL1 of the cylinder 30.

A plurality of (for example, eight) communication passages 44a (first communication passages) and communication passages 44b are arranged at substantially equal intervals in the circumferential direction of the partition wall 42.
The communication passages 44 a and 44 b are provided at a position slightly below the upper end of the hemispherical portion of the lower part of the partition wall 42 .

Of the multiple communication passages 44a, 44b arranged in the circumferential direction, one communication passage 44a (first communication passage) is provided in a position directly facing the injector 3. The fuel injected from the injector 3 is mainly injected toward the communication passage 44a.

The communication passages 44a, 44b are arranged on the same plane perpendicular to the axis CL1 of the cylinder 30. The communication passages 44a, 44b extend at an angle to the plane perpendicular to the axis CL1 of the cylinder 30, and are inclined upward (toward the spark plug 35) from the main combustion chamber 41 toward the auxiliary combustion chamber 43. The axes of the communication passages 44a, 44b are set to intersect at the same intersection CP1 on the central axis CL2 of the partition wall 42. In this embodiment, the partition wall 42 is located near the central axis of the cylinder 30, and the intersection CP1 of the axes of the communication passages 44a and 44b is located on the central axis CL1 of the cylinder 30.

Furthermore, a communication passage 44c is provided at the lower end of the partition wall 42. More specifically, the communication passage 44c is provided at a position of the partition wall 42 closest to the piston 37, and extends along the axis CL1 of the cylinder 30.

As described above, the internal combustion engine 1 of this embodiment is provided with an auxiliary combustion chamber 43 partitioned by a partition wall 42 in the upper center of the main combustion chamber 41. The partition wall 42 is provided with communication passages 44a, 44b, and 44c that connect the main combustion chamber 41 and the auxiliary combustion chamber 43.

As shown in FIG. 3, this embodiment uses a direct-injection type injector 3, which injects fuel directly into the main combustion chamber 41. The injector 3 is positioned to inject fuel toward the auxiliary combustion chamber 43, and as the piston 37 moves in the compression direction while injecting fuel, some of the fuel that has reached the vicinity of the auxiliary combustion chamber 43 flows into the auxiliary combustion chamber 43 from the communication passages 44a, 44b, and 44c. The remaining fuel that does not flow into the auxiliary combustion chamber 43 is mixed with the intake air in the main combustion chamber 41. Note that the fuel may be injected twice, once into the main combustion chamber 41 and once into the auxiliary combustion chamber 43.

When the mixture in the auxiliary combustion chamber 43 is ignited by the spark plug 35, the flame generated by ignition in the auxiliary combustion chamber 43 passes through the connecting passages 44a, 44b, and 44c and is injected into the main combustion chamber 41, combusting the mixture in the main combustion chamber 41.

The lower end of the partition wall 42 is provided with a communication passage 44c, which extends parallel to the axis CL1 of the cylinder 30. During the compression stroke when the piston moves upward, fuel flows from the communication passage 44c toward the upper part of the auxiliary combustion chamber 43.

In this embodiment, the central axis CL2 of the auxiliary combustion chamber 43 is inclined toward the intake side with respect to the axis CL1 of the cylinder 30, so that the fuel that flows into the auxiliary combustion chamber 43 from the communication passage 44c moves from the center of the auxiliary combustion chamber 43 toward a position biased toward the exhaust side. Then, when it collides with the ignition plug 35 and turns around, a swirling flow is generated in the auxiliary combustion chamber 43 as shown by the arrow in Figure 5.

The partition wall 42 is also provided with multiple communication passages 44a, 44b arranged in the circumferential direction, so that fuel also flows into the auxiliary combustion chamber 43 through the communication passages 44a, 44b during the compression stroke.

The extension lines of the communicating passages 44a, 44b are inclined upwardly on the opposite side to the communicating passage 44c with respect to a direction perpendicular to the extension line of the communicating passage 44c (i.e., the axis CL1 of the cylinder 30) and are arranged so as to intersect on the extension line (CL1) of the communicating passage 44c. Therefore, the fuel flowing in from the communicating passages 44a, 44b collides on the extension line (CL1) of the communicating passage 44c, generating a flow that moves toward the upper part of the auxiliary combustion chamber 43 along the extension line of the communicating passage 44c.
As a result, a strong swirling flow of the air-fuel mixture can be generated within the auxiliary combustion chamber 43 by the fuel that has passed through the communication passages 44 a , 44 b , and 44 c and flowed into the auxiliary combustion chamber 43 .

As shown in FIG. 6, the fuel (rich mixture) that collides with the spark plug 35 in the auxiliary combustion chamber 43 and reverses direction stays on the intake side of the auxiliary combustion chamber 43, where the fuel concentration increases. Then, when ignited by the spark plug 35, it burns strongly on the intake side of the auxiliary combustion chamber 43. Therefore, the momentum of the flame that is injected from the auxiliary combustion chamber 43 through the communication passage 44a is stronger than the momentum of the flame that is injected from the other communication passage 44b.

In addition, in the main combustion chamber 41, a tumble flow (for example, Tc in FIG. 6) is generated by the intake air that flows in when the intake valve 32 is open. The tumble flow of the intake air flows from the intake side to the exhaust side at the top of the main combustion chamber 41. The flame is injected radially from the auxiliary combustion chamber 43 through the connecting passages 44a and 44b, but the flame injected from the connecting passage 44a to the intake side may be obstructed by the tumble flow, making it difficult for the flame to propagate near the wall surface of the cylinder block 36 on the intake side. However, in this embodiment, as described above, the flame is injected from the connecting passage 44a more strongly than the other connecting passages 44b, so that the flame is more likely to reach the wall surface of the cylinder block 36 on the intake side. This allows the flame to propagate evenly in the main combustion chamber 41, improving the combustibility in the main combustion chamber 41, improving the output of the internal combustion engine 1, or reducing the fuel concentration in the main combustion chamber 41 to improve fuel efficiency. It also prevents unburned gas from leaking out of the main combustion chamber 41.

In addition, since the injector 3 is positioned facing the intake valve 32 side of the main combustion chamber 41 and injects fuel toward the auxiliary combustion chamber 43, the penetrating force of the fuel injected from the injector 3 makes it easier for the fuel to flow into the communication passage 44a that opens to the intake side of the partition wall 42. This makes it possible to supply a rich mixture to the auxiliary combustion chamber 43 and to strengthen the swirling flow within the auxiliary combustion chamber 43. This makes it possible to increase the momentum of the flame generated in the auxiliary combustion chamber 43 and to inject a strong flame, particularly toward the intake side of the main combustion chamber 41.

In addition, since the communication passage 44a on the intake side faces the fuel injection port 3a of the injector 3, fuel flows directly into the communication passage 44a when injected from the injector 3. This allows fuel to flow efficiently from the communication passage 44a into the auxiliary combustion chamber 43, and also causes the fuel to flow strongly toward the exhaust side of the auxiliary combustion chamber 43. As a result, when the fuel flows upward in the auxiliary combustion chamber 43, it flows even more biased toward the exhaust side, which generates a strong swirling flow of the mixture in the auxiliary combustion chamber 43 and improves combustibility in the auxiliary combustion chamber 43.

Furthermore, among the multiple communication passages 44a, 44b arranged in the circumferential direction of the partition wall 42, the communication passage 44a on the intake side has a larger path cross-sectional area (passage diameter) than the other communication passages 44b, i.e., the opening area on the main combustion chamber 41 side is formed to be larger.

This allows the fuel injected from the injector 3 to flow more easily into the connecting passage 44a, strengthening the swirling flow in the auxiliary combustion chamber 43. Also, the flame generated in the auxiliary combustion chamber 43 can be ejected more from the connecting passage 44a on the intake side than from the other connecting passage 44b. Therefore, the flame can be propagated further to the intake side of the main combustion chamber 41 against the tumble flow, and the flame can be propagated evenly within the main combustion chamber 41, particularly in high-speed rotation conditions where the intake volume is large, to further improve combustibility in the main combustion chamber 41.

In addition, since multiple communication passages 44a, 44b are arranged in a circumferential line on the partition wall 42, multiple flames are injected from the auxiliary combustion chamber 43 so as to spread radially outwardly into the main combustion chamber 41. This allows the flames to propagate widely within the main combustion chamber 41, further improving the combustibility in the main combustion chamber 41.

In particular, since multiple communication passages 44a, 44b are arranged at equal intervals in the circumferential direction on the partition wall 42, multiple flames can be supplied from the auxiliary combustion chamber 43 to the main combustion chamber 41 so that they spread evenly radially, and the flames can be propagated more evenly within the main combustion chamber 41, further improving the combustibility in the main combustion chamber 41.

The present invention is not limited to the above-described embodiments.
For example, in the above embodiment, the partition wall 42 has a total of eight communication passages 44a and 44b arranged in the circumferential direction, but the number may be more than eight or may be any other number.

In addition, the shapes of the main combustion chamber 41, the auxiliary combustion chamber 43, etc., and the positions and detailed shapes of the communication passages 44a, 44b, 44c may be appropriately changed.
In this embodiment, one cylinder is provided with two intake valves 32 and two exhaust valves 33, but the present invention can also be applied to an internal combustion engine with, for example, one intake valve 32 and one exhaust valve 33.

Further, although the internal combustion engine 1 of the present embodiment is a direct injection type internal combustion engine, the present invention is also applicable to a port injection type internal combustion engine or an internal combustion engine configured to inject fuel directly into a pre-combustion chamber.
The internal combustion engine of the present invention can be applied to various internal combustion engines such as those used to drive automobiles.

1. Internal combustion engine (internal combustion engine with auxiliary combustion chamber)
32 Intake valve 33 Exhaust valve 34 Cylinder head 36 Cylinder block 37 Piston 41 Main combustion chamber 43 Auxiliary combustion chamber 42 Partition wall 44a Communication passage (first communication passage)
44b Communication passage

Claims (5)

An internal combustion engine with a secondary combustion chamber, comprising: a main combustion chamber formed in a cylinder by a cylinder head, a cylinder block, and a piston; a secondary combustion chamber separated from the main combustion chamber by a partition wall provided in the cylinder head; a fuel injection device that supplies fuel to the main combustion chamber and the secondary combustion chamber; an ignition plug that ignites in the secondary combustion chamber; and an intake valve and an exhaust valve that are disposed on either side of the secondary combustion chamber in the cylinder head, wherein a communication passage is provided in the partition wall that communicates between the secondary combustion chamber and the main combustion chamber,
the communication passage includes a first communication passage provided on at least a side surface of the partition wall on the intake valve side,
2. An internal combustion engine with a pre-combustion chamber, wherein the pre-combustion chamber is formed so that the side opposite the piston with respect to the axis of the cylinder extends along an axis that is inclined toward the intake valve. 2. The internal combustion engine with an auxiliary combustion chamber according to claim 1, wherein the fuel injection device is disposed facing the intake valve side of the main combustion chamber and injects fuel toward the auxiliary combustion chamber. The communication passage includes a plurality of communication passages including the first communication passage,
3. The internal combustion engine with a pre-combustion chamber according to claim 2, wherein the first communication passage has a larger passage diameter than the other communication passages. 4. The internal combustion engine with an auxiliary combustion chamber according to claim 1, wherein a plurality of the communication passages are arranged side by side in a circumferential direction of the partition wall. 5. The internal combustion engine with a pre-combustion chamber according to claim 4, wherein the communication passages are arranged at equal intervals.

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