The present disclosure relates to a structure of a combustion chamber of an engine.
Conventionally, structures of a combustion chamber of an engine are known, in which the combustion chamber is formed between a cylinder head and a piston. For example, JP2020-007977A discloses this type of structure of a combustion chamber of an engine. An internal combustion engine disclosed in JP2020-007977A is provided with a cylinder block, a piston, and a cylinder head. A combustion chamber is defined by a cylinder bore surface of the cylinder block, a top surface of the piston, a combustion-chamber ceiling surface of the cylinder head, and bottom surfaces of intake and exhaust valves.
The internal combustion engine of JP2020-007977A is further provided with a fuel injection nozzle and ducts. The fuel injection nozzle has a tip-end part exposed to the combustion chamber. The tip-end part is formed with injection holes. Each duct is provided corresponding to the injection hole. Inside the duct, a flow-adjusting passage is formed. Fuel injected from the injection hole passes through the flow-adjusting passage, and then, is discharged into the combustion chamber.
In JP2020-007977A, the duct is provided so that, in the process where fuel spray of the injected fuel passes through the duct, premixing of the fuel spray and filled air can be facilitated while suppressing self-ignition, and thus, generation of smoke due to the self-ignition of over-concentrated fuel before homogenization can be reduced.
However, according to the configuration of JP2020-007977A, the fuel spray after passing through the respective injection nozzles may not have many chances to collide with each other, and thus, it is difficult that the entire fuel is efficiently mixed with the filled air.
One purpose of the present disclosure is to facilitate efficient mixing of the entire fuel with air inside the combustion chamber.
According to one aspect of the present disclosure, an engine is provided, which includes a combustion chamber defined by a cylinder head and a piston inside a cylinder of a cylinder block, a fuel injection nozzle provided to the cylinder head and formed in a tip-end part with a plurality of injection holes from which fuel is injected into the combustion chamber, the tip-end part being exposed to the combustion chamber, and a passage-forming member formed with a passage through which the fuel injected from the injection hole passes. The plurality of injection holes include a first injection hole and a second injection hole. The passage-forming member is disposed around the tip-end part of the fuel injection nozzle so as to cause a difference between a speed at which fuel injected from the first injection hole flows toward a circumferential part of the combustion chamber, and a speed at which fuel injected from the second injection hole flows toward the circumferential part of the combustion chamber.
According to this structure, the fuel injected from one of the first injection hole and the second injection hole priorly spreads inside the combustion chamber, and to this fuel spray, the fuel injected from the other of the first injection hole and the second injection hole collides. Accordingly, spatial turbulence of the fuel spray occurs inside the combustion chamber. As a result, the entire fuel is easily mixed with air inside the combustion chamber efficiently.
The passage formed in the passage-forming member may include a passage through which only the fuel injected from the first injection hole passes in a direction of the injection.
According to this structure, by the fuel flowing in the passage-forming member, compared to the structure without the passage-forming member, the fuel easily flows promptly. As a result, it becomes easier to set the difference between the speed at which the fuel injected from the first injection hole flows toward the circumferential part of the combustion chamber, and the speed at which the fuel injected from the second injection hole flows toward the circumferential part of the combustion chamber.
The passage of the passage-forming member may include an enlarged part gradually increasing in a cross-sectional area thereof from an upstream side to a downstream side of the passage.
According to this structure, while the fuel is acted upon by the Coanda effect to flow along the inner surface of the passage-forming member, since the cross-sectional area of the enlarged part gradually increases to the downstream side of the passage, the fuel easily flows toward the downstream end while spreading. Therefore, when the fuel is discharged from the passage-forming member, it becomes easier for the fuel to spread radially outward of the passage. As a result, mixing of the fuel with air inside the combustion chamber becomes easier.
The passage-forming member may be formed, in the passage, with a narrowed part on the upstream side of the enlarged part so as to gradually decrease in a cross-sectional area thereof and continue to an upstream end of the enlarged part.
According to this structure, since the cross-sectional area of the passage through which the fuel passes is reduced at the narrowed part, turbulence occurs in the flow of the fuel as a result of the fuel passing through the narrowed part, thereby the fuel easily being split finely. As a result, the central part of the fuel is prevented from becoming high in its concentration, and the concentration of the fuel is homogenized, which enables uniform mixing.
The narrowed part may be positioned upstream of the midpoint in the passage.
According to this structure, a sufficient length of the enlarged part can be easily secured on the downstream of the narrowed part. Since the enlarged part has a sufficient length, the fuel is more easily affected by the Coanda effect and smoothly flows along the inner surface of the passage-forming member. Moreover, since the downstream end of the enlarged part sufficiently spreads radially outwardly, when the fuel is discharged from the enlarged part, it can sufficiently spread radially outward of the passage.
The enlarged part may be comprised of a first enlarged part gradually increasing in a cross-sectional area thereof toward the downstream side, and a second enlarged part provided downstream of the first enlarged part to continue from the first enlarged part, and of which a rate of increase in a cross-sectional area thereof toward the downstream side is higher than the first enlarged part.
According to this structure, when the fuel is discharged from the second enlarged part of the passage-forming member, it becomes easier for the fuel to spread radially outward of the passage. As a result, mixing of the fuel with air inside the combustion chamber becomes easier.
The first enlarged part and the second enlarged part may be smoothly connected to each other.
According to this structure, the fuel smoothly flows, by the Coanda effect, along the inner surface of the passage-forming member. As a result, the fuel is easily spread radially outward of the passage.
The cylinder head may be formed, in the combustion-chamber ceiling surface of the cylinder head, with a concave part configured to accommodate a part of the passage-forming member. The passage-forming member may be disposed at the concave part.
According to this structure, it becomes possible to bring a top dead center of the piston disposed in the cylinder block closer to the cylinder head, which can increase a compression ratio of the engine.
The structure of the combustion chamber may further include a first passage-forming part formed with a passage through which the fuel injected from the first injection hole passes, and a second passage-forming part formed with a passage through which the fuel injected from the second injection hole passes. At least one of a radius and a length may be different between the passage of the first passage-forming part and the passage of the second passage-forming part.
According to this structure, by suitably designing the radius or the length of the passages of the first passage-forming part and the second passage-forming part, the difference between the speed at which the fuel injected from the first injection hole flows toward the circumferential part of the combustion chamber, and the speed at which the fuel injected from the second injection hole flows toward the circumferential part of the combustion chamber, can freely be set. As a result, the entire fuel is easily mixed with air inside the combustion chamber efficiently.
The structure of the combustion chamber may further include a passage-forming unit in a circular ring shape and alternately having the first passage-forming part and the second passage-forming part in a circumferential direction.
According to this structure, the positioning between the injection holes of the fuel injection nozzle and the passage-forming member becomes easier.
The first passage-forming part and the second passage-forming part may be alternately disposed in a circumferential direction centering on a center axis of the fuel injection nozzle.
According to this, the difference between the speed at which the fuel injected from the first injection hole flows toward the circumferential part of the combustion chamber, and the speed at which the fuel injected from the second injection hole flows toward the circumferential part of the combustion chamber, can be set easily with the simple structure.
Hereinafter, embodiments to implement the present disclosure are described with reference to the accompanying drawings. Essentially, the following preferable description of the embodiments is merely illustration, and is not intended to limit the present disclosure, its application, or its use.
Below, an outline structure of a combustion chamber of a diesel engine in a direct-injection type according to this embodiment is described with reference to
Each piston 1 is formed with a cavity 9 in a top surface of the piston 1. The cylinder block 2 is provided with cylinders. The cylinder block 2 is formed, in its upper-end surface, with a mating surface 2a to be connected to the cylinder head 3. Although not illustrated, the cylinder head 3 is formed with the intake ports and the exhaust ports, and the intake valves and the exhaust valves are provided to the intake ports and the exhaust ports, respectively, so as to be openable and closeable. Moreover, the fuel injection nozzles 8 are attached to the cylinder head 3. The cylinder head 3 is formed, in its lower-end surface, with a mating surface 3a to be connected to the cylinder block 2. The cylinder head 3 and the cylinder block 2 are mated with each other by the mating surfaces 3a and 2a, and the piston 1 is accommodated inside the cylinder, so that the combustion chamber 10 is defined between the cylinder head 3 and the piston 1.
In detail, the combustion chamber 10 of the diesel engine is mainly defined by the top surface (the cavity 9) of the piston 1, an inner-wall surface of the cylinder block 2, a combustion-chamber ceiling surface 3b surrounded by the mating surface 3a of the cylinder head 3, and umbrella parts of the intake valve and the exhaust valve.
In the diesel engine described above, propulsive force is obtained from an explosion caused in the combustion chamber 10 by fuel being injected from the fuel injection nozzle 8 into the combustion chamber 10 during a compression stroke (e.g., in a latter half of the compression stroke) and spontaneously ignited. Then, the piston 1 reciprocates inside the cylinder by the propulsive force so that the reciprocating motion of the piston 1 is converted into a rotating motion of a crank shaft (not illustrated) via a rod (not illustrated) to obtain a motive force.
Each fuel injection nozzle 8 is attached to the cylinder head 3 so that a tip-end part of the fuel injection nozzle 8 is exposed to the combustion chamber 10. A plurality of injection holes are arranged at the tip-end part of the fuel injection nozzle 8 at even intervals in the circumferential direction centering on an axis of the fuel injection nozzle 8. In this embodiment, eight injection holes are provided to the tip-end part of the fuel injection nozzle 8. The eight injection holes include four first injection holes 8a and four second injection holes 8b (both will be described later). However, the number of injection holes 8a and 8b is not limited to this, but may be seven or less, or nine or more as a total. The center axis of each of the injection holes 8a and 8b extends radially outwardly and obliquely downwardly with respect to the center axis of the cylinder. When seen as a whole, the eight injection holes 8a and 8b are provided so that fuel is injected radially outwardly with respect to the center axis of the combustion chamber 10.
In the diesel engine of this embodiment, four passage-forming members 20 are provided corresponding to the first injection holes 8a (the half of the eight injection holes 8a and 8b provided to the fuel injection nozzle 8). As illustrated in
As illustrated in
As illustrated in
As illustrated in
In the structure of the combustion chamber of the diesel engine according to this embodiment, fuel injected from the first injection hole 8a of the fuel injection nozzle 8 passes through the passage-forming member 20 so as to flow toward a circumferential part of the combustion chamber 10 at a first speed. On the other hand, fuel injected from the second injection hole 8b of the fuel injection nozzle 8 is not allowed to pass through the passage-forming member 20 so as to flow toward the circumferential part of the combustion chamber 10 at a second speed lower than the first speed. In other words, the structure of the combustion chamber of the diesel engine according to this embodiment is provided with the passage-forming member 20 (see
In the structure of the combustion chamber of the diesel engine configured as described above, when fuel is injected from the injection holes 8a and 8b of the fuel injection nozzle 8 during the compression stroke (e.g., in a latter half of the compression stroke), part of the fuel enters the passage of the passage-forming member 20 disposed coaxially with the first injection hole 8a. The fuel which entered into the passage from the upstream end of the passage-forming member 20 is acted upon by the Coanda effect to flow along the inner surface of the passage-forming member 20, and thus, the Coanda effect causes the flow of the fuel toward the downstream end of the passage-forming member 20 along the substantially cone-shaped inner surface of the enlarged part 22. That is, the fuel passing through the passage of the passage-forming member 20 is caused to flow from the upstream end to the downstream end along the inner surface of the enlarged part 22 by the Coanda effect, while spreading radially outwardly with respect to the center axis of the passage. By the fuel passing through the passage-forming member 20, it flows faster than the case of not passing through the passage-forming member 20. This is because, inside the passage of the passage-forming member 20, air (which becomes resistance) is difficult to be caught in the fuel spray. Moreover, when the fuel is discharged from the passage-forming member 20, it becomes easier for the fuel to spread radially outward of the passage from the downstream end of the enlarged part 22. As a result, the fuel after passing through the passage-forming member 20 flows toward the circumferential part of the combustion chamber 10 at the higher speed, and is mixed with air inside the combustion chamber 10. The fuel injected from the second injection hole 8b of the fuel injection nozzle 8 flows toward the circumferential part of the combustion chamber 10 at the lower speed than the fuel which is injected from the first injection hole 8a and passed through the passage-forming member 20, and collides with the fuel priorly mixed with air. Accordingly, spatial turbulence of the fuel spray occurs inside the combustion chamber 10. As a result, the entire fuel is efficiently mixed with air inside the combustion chamber 10.
Moreover, as illustrated in
Below, an outline structure of the combustion chamber 10 of the diesel engine according to Embodiment 2 is described with reference to
The passage-forming members 30 are provided in the same number as the injection holes 8a so as to correspond to each other. Each passage-forming member 30 has a substantially cylindrical external shape. In detail, the external shape of the passage-forming member 30 is such that a part of a cylindrical outer circumferential surface is scraped off to form a flat part 31. The flat part 31 constitutes a plane surface parallel to the center axis of a passage in the passage-forming member 30.
As illustrated in
In the structure of the combustion chamber of the diesel engine configured as described above, when fuel is injected during the compression stroke from the injection holes 8a and 8b of the fuel injection nozzle 8, part of the fuel enters into the passage of the passage-forming member 30 disposed coaxially with the first injection hole 8a. The fuel that has entered the passage from the upstream end of the passage-forming member 30, flows toward the narrowest part 33 while accelerating along the inner surface of the narrowed part 34. The cross-sectional area of the passage in the passage-forming member 30 through which the fuel passes, is reduced at the narrowed part 34 and the narrowest part 33. Accordingly, turbulence occurs to the flow of the fuel as a result of the fuel passing through the narrowed part 34, thereby the fuel easily being split finely. In detail, by the fuel passing through the narrow passage of the narrowed part 34 and the narrowest part 33, the entire flow of the fuel including the central part (core part) is disturbed (i.e., turbulence is generated). Therefore, the fuel including the center part of the fuel which is conventionally difficult to be split, is easily homogenized in its concentration. The fuel after passing through the narrowest part 33 is acted upon by the Coanda effect to flow along the inner surface of the passage-forming member 30 so that the fuel flows toward the downstream along the inner surface of the enlarged part 22. By the fuel passing through the enlarged part 22, it flows faster than the case of not passing thorough the passage-forming member 30. Moreover, since the cross-sectional area of the enlarged part 22 gradually increases toward the downstream end of the passage, the fuel easily flows toward the downstream end while spreading by the Coanda effect. As a result, the fuel is homogenized in its concentration, and mixing of the fuel with air inside the combustion chamber 10 is facilitated. The fuel injected from the second injection hole 8b of the fuel injection nozzle 8 flows toward the circumferential part of the combustion chamber 10 at the lower speed than the fuel which is injected from the first injection hole 8a and passed through the passage-forming member 30, and collides with the fuel priorly mixed with air. Accordingly, spatial turbulence of the fuel spray occurs inside the combustion chamber 10. As a result, the entire fuel is efficiently mixed with air inside the combustion chamber 10. Thus, unburnt fuel is unlikely to be generated, which improves emissions.
Particularly, in the passage-forming member 30 of this embodiment, as illustrated in
Below, an outline structure of the combustion chamber 10 of the diesel engine according to Embodiment 3 is described with reference to
As illustrated in
The first enlarged part 45 is disposed downstream of the narrowed part 34 in the passage of the passage-forming member 40, to be continued from the narrowed part 34. In other words, the first enlarged part 45 is provided immediately downstream of the narrowed part 34. A cross-sectional area of the first enlarged part 45 gradually increases as separating from the narrowed part 34.
The second enlarged part 41 is disposed downstream of the first enlarged part 45 in the passage of the passage-forming member 40, to be continued from the first enlarged part 45. In other words, the second enlarged part 41 is provided immediately downstream of the first enlarged part 45. A cross-sectional area of the second enlarged part 41 gradually increases as separating from the first enlarged part 45. In detail, in the second enlarged part 41, a rate of increase in the cross-sectional area to the downstream side of the passage is higher than that of the first enlarged part 45. Note that as illustrated in
In the structure of the combustion chamber of the diesel engine configured as described above, when fuel is injected during a compression stroke from the injection holes 8a and 8b of the fuel injection nozzle 8, part of the fuel enters into the passage of the passage-forming member 40 disposed coaxially with the first injection hole 8a. The fuel that has entered the passage from the upstream end of the passage-forming member 40, passes through the narrowed part 34 and the narrowest part 33 to be homogenized in its concentration. The fuel after passing through the narrowed part 34 and the narrowest part 33 is acted upon by the Coanda effect to flow along the inner surface of the passage-forming member 40. Therefore, the fuel flows toward the second enlarged part 41 on the downstream side along the inner surface of the first enlarged part 45. Furthermore, the fuel flows toward the downstream along the inner surface of the second enlarged part 41 while spreading radially outwardly with respect to the center axis of passage, and when the fuel is discharged from the downstream end of the passage of the second enlarged part 41, it further spreads radially outward of the passage of the passage-forming member 40 by the Coanda effect. Preferably, the inner surface of the second enlarged part 41 inclines nearly perpendicularly to the center axis of the passage in the passage-forming member 40 such that the fuel is discharged nearly perpendicularly with respect to the center axis of the passage-forming member 40. As a result, the mixing of fuel with air inside the combustion chamber 10 is facilitated more. The fuel injected from the second injection hole 8b of the fuel injection nozzle 8 flows toward the circumferential part of the combustion chamber 10 at the speed lower than the speed at which the fuel injected from the first injection hole 8a passes through the passage-forming member 40 and flows toward the circumferential part of the combustion chamber 10, and collides with the fuel priorly mixed with air. Accordingly, spatial turbulence of the fuel spray occurs inside the combustion chamber 10. As a result, the entire fuel is efficiently mixed with air inside the combustion chamber 10. Thus, unburnt fuel is unlikely to be generated, which improves emissions.
Below, an outline structure of the combustion chamber 10 of the diesel engine according to Embodiment 4 is described with reference to
The passage-forming member 50 is provided with a first enlarged part 51, a narrowed part 52, a narrowest part 53, and a second enlarged part 54, instead of the first enlarged part 45, the narrowed part 34, the narrowest part 33, and the second enlarged part 41, respectively.
As illustrated in
As illustrated in
According to the passage-forming member 50 configured as described above, fuel more easily flows along the inner surface of the passage-forming member 50. Therefore, the fuel easily and more promptly flows by the Coanda effect inside the passage-forming member 50 without stagnation. Moreover, when the fuel is discharged from the second enlarged part 54 of the passage-forming member 50, the fuel more easily spreads radially outward of the passage of the passage-forming member 50. The fuel injected from the second injection hole 8b of the fuel injection nozzle 8 flows toward the circumferential part of the combustion chamber 10 at the lower speed than the speed at which the fuel injected from the first injection hole 8a passes through the passage-forming member 50 and flows toward the circumferential part of the combustion chamber 10, and collides with the fuel priorly mixed with air. Accordingly, spatial turbulence of the fuel spray occurs inside the combustion chamber 10. As a result, the entire fuel is efficiently mixed with air inside the combustion chamber 10. Thus, unburnt fuel is unlikely to be generated, which improves emissions.
Although the embodiments of the present disclosure are described above as examples, the present disclosure is not limited to the above embodiments.
Although in the embodiments described above each passage-forming member is independently fixed to the concave part 3c formed in the combustion-chamber ceiling surface 3b of the cylinder head 3, it is not limited to this. Moreover, although in the above embodiments a passage-forming member is not provided corresponding to the second injection hole 8b, it is not limited to this. For example, a first passage-forming part (first passage-forming member) which is provided corresponding to the first injection hole 8a, and a second passage-forming part (second passage-forming member) which is provided corresponding to the second injection hole 8b, may be integrally formed in a common passage-forming unit. A reference character 60 in
The passage-forming unit 60 has a circular ring shape with a given thickness. The passage-forming unit 60 is formed with four first passages 61 positioned at every 90 degrees so as to radially penetrate an inner circumferential surface and an outer circumferential surface of the passage-forming unit 60. The first passage 61 is an example of the passage of the first passage-forming member. A cross section of each first passage 61 is circular. Moreover, the passage-forming unit 60 is formed with four second passages 62 positioned at every 90 degrees so as to radially penetrate the inner circumferential surface and the outer circumferential surface of the passage-forming unit 60. The second passage 62 is an example of the passage of the second passage-forming member. Each second passage 62 is disposed at an angular position middle between the adjacent first passages 61 in a circumferential direction. A cross section of each second passage 62 is circular which is larger than that of the first passage 61. The passage-forming unit 60 is attached so that the first passage 61 is opposed to the first injection hole 8a, the second passage 62 is opposed the second injection hole 8b, and the entire circumference of the fuel injection nozzle 8 is surrounded by the passage-forming unit 60. In detail, an end surface of the passage-forming unit 60 on one side in its the axial direction, is attached to the concave part 3c in the combustion-chamber ceiling surface 3b of the cylinder head 3 in a substantially surface-contacting state or a line-contacting state, by known methods (e.g., welding or screwing).
Also in this manner, fuel which passed through the first passage 61 (first passage-forming part) and fuel which passed through the second passage 62 (second passage-forming part) flow with a time difference, and collide with each other, and thus, the entire fuel is mixed easily. Note that fuel flows faster in the first passage 61 with the smaller cross section, compared to in the second passage 62. This is because an amount of air which flows into the passage increases as the cross section of the passage (hole diameter) increases, and air resistance to the fuel increases accordingly.
Moreover, since the four first passages 61 and the four second passages 62 are held by the common passage-forming unit 60, a positional relationship between the injection holes 8a and 8b, and the passages 61 and 62, respectively, can be easily and simultaneously determined.
A reference character 70 of
Schematically, the passage-forming unit 70 is a substantially octagon shape alternately having short sides 73 and long sides 74. The passage-forming unit 70 has a given thickness, and its axial part is a cylindrical hollow part 69. The passage-forming unit 70 is formed with four first passages 71 positioned at every 90 degrees so as to radially communicate the short side 73 and the hollow part 69. The first passage 71 is an example of the passage of the first passage-forming member. Moreover, the passage-forming unit 70 is formed with four second passages 72 positioned at every 90 degrees so as to radially communicate the center part of the long side 74 and the hollow part 69. The second passage 72 is an example of the passage of the second passage-forming member. Cross sections of the first passage 71 and the second passage 72 are substantially the same. The length of the first passage 71 (L1) is longer than the length of the second passage (L2) (L1>L2). The passage-forming unit 70 is attached so that the first passage 71 is opposed to the first injection hole 8a and the second passage 72 is opposed to the second injection hole 8b, and the entire circumference of the fuel injection nozzle 8 is surrounded by the passage-forming unit 70. In detail, an end surface of the passage-forming unit 70 on one side in its axial direction, is attached to the concave part 3c in the combustion-chamber ceiling surface 3b of the cylinder head 3 in a substantially surface-contacting state or a line-contacting state, by known methods (e.g., welding or screwing).
Also in this manner, fuel which passed through the first passage 71 (first passage-forming part) and fuel which passed through the second passage 72 (second passage-forming part) flow with a time difference, and collide with each other, and thus, the entire fuel is mixed easily. Note that fuel flows faster in the first passage 71 with the longer length L1 compared to in the second passage 72 with the shorter length L2, due to a difference in air resistance caused by a difference in a period of time during which air and fuel are in contact with each other. Moreover, since the four first passages 71 and the four second passages 72 are held by the common passage-forming unit 70, a positional relationship between the injection holes 8a and 8b, and the passages 71 and 72, respectively, can be easily and simultaneously determined.
In the embodiments described above, the passage-forming member is disposed at the concave part 3c formed in the combustion-chamber ceiling surface 3b of the cylinder head 3. However, instead of this, the passage-forming member may be disposed at a position other than the concave part 3c in the combustion-chamber ceiling surface 3b. Such an example is illustrated in
Alternatively, the passage-forming member may be disposed on a combustion-chamber ceiling surface of a pent-roof type, of the cylinder head 3. Such an example is illustrated in
As illustrated in
A glowplug attachment hole may be provided to the cylinder head 3 so that a glowplug is attached to the glowplug attachment hole. Such an example is illustrated in
In the embodiments described above, the flat part 21 is formed in the outer circumferential part of the passage-forming member 20, and the flat part 21 contacts the concave part 3c in the combustion-chamber ceiling surface 3b of the cylinder head 3 so as to be attached to the concave part 3c in the substantially surface-contacting state. However, it is not limited to this. The flat part may not be formed in the passage-forming member, and an outer circumferential surface of the passage-forming member may be line-contacted with the concave part 3c so that the passage-forming member is attached to the concave part 3c in this state.
Although in the embodiments described above the passage-forming member is directly attached to the concave part 3c in the combustion-chamber ceiling surface 3b of the cylinder head 3, it is not limited to this. Instead of this, the passage-forming member may be accommodated in a cylindrical holder, and the holder may be fixed to the concave part 3c in the combustion-chamber ceiling surface 3b of the cylinder head 3 by a fastening member (e.g., a screw or a bolt).
A plurality of (e.g., two) types of passage-forming members (passage-forming parts) may be disposed alternately in the circumferential direction around the fuel injection nozzle 8. Accordingly, the difference between the speed at which the fuel injected from the first injection hole 8a flows toward the circumferential part of the combustion chamber 10, and the speed at which the fuel injected from the second injection hole 8b flows toward the circumferential part of the combustion chamber 10 can be set freely. However, the passage-forming members of a common (single) type may be disposed corresponding to all of the injection holes 8a and 8b of the fuel injection nozzle 8. Also in this manner, the effect of facilitating the mixing of fuel with air inside the combustion chamber 10 can be achieved.
The engine is not necessarily limited to the diesel engine, but the present disclosure is also applicable to gasoline engines. For example, in the example of
Moreover, the elements described in the above embodiments and modifications may suitably be combined so long as a contradiction does not arise. For example, in the passage-forming unit 60, two types of passage-forming members 40 with different passage cross-sectional areas may be provided as the first passage-forming part and the second passage-forming part, at positions corresponding to the first passage 61 and the second passage 62, respectively.
The present disclosure is applicable to a structure of a combustion chamber of an engine.
It should be understood that the embodiments herein are illustrative and not restrictive, since the scope of the invention is defined by the appended claims rather than by the description preceding them, and all changes that fall within metes and bounds of the claims, or equivalence of such metes and bounds thereof, are therefore intended to be embraced by the claims.
Number | Date | Country | Kind |
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2020-146859 | Sep 2020 | JP | national |