Ignition system
The ignition system with a dual sub-chamber configuration and controlled gas flow direction stabilizes ignition in gas engines using low flammability fuels, addressing combustion inefficiencies and promoting stable combustion.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2025-09-22
- Publication Date
- 2026-04-02
AI Technical Summary
The use of fuels with low flammability, such as ammonia, in gas engines can lead to insufficient combustion promotion in the combustion chamber, resulting in decreased combustion efficiency.
An ignition system with a first sub-chamber and a second sub-chamber, featuring specific communication holes and electrode configurations, stabilizes the ignition process by directing the air-fuel mixture flow unidirectionally through the electrode gap, promoting efficient combustion in the combustion chamber.
The ignition system enhances combustion stability and efficiency in the combustion chamber by stabilizing the ignition process, reducing misfires and fluctuations, and accelerating flame generation.
Smart Images
Figure JP2025033253_02042026_PF_FP_ABST
Abstract
Description
Ignition system
[0001] This disclosure relates to an ignition system. This application claims the benefit of priority based on Japanese Patent Application No. 2024-171106 filed on September 30, 2024, the content of which is incorporated herein by reference.
[0002] In a gas engine, a fuel having low flammability may be used. For example, as disclosed in Patent Document 1, a technology using ammonia having low flammability as a fuel has been proposed. By using ammonia as a fuel, carbon dioxide emissions can be suppressed.
[0003] Japanese Patent Application Laid-Open No. 2020-148198
[0004] When a fuel having low flammability is used, if the promotion of combustion in the combustion chamber is insufficient, there is a risk that the combustion efficiency will decrease. Therefore, it is desirable to promote combustion in the combustion chamber.
[0005] An object of this disclosure is to provide an ignition system capable of promoting combustion in a combustion chamber.
[0006] To solve the above problems, the ignition system of this disclosure includes a first sub-chamber communicating with a combustion chamber via at least one first communication hole, a first electrode, a second electrode having an insertion hole through which the first electrode is inserted, and an electrode gap formed between the first electrode and the second electrode. A second sub-chamber provided with an ignition device, a first space on the first sub-chamber side partitioned by the second electrode inside the second sub-chamber, a second space on the opposite side of the first sub-chamber, a through hole formed in the second electrode and communicating the first space and the second space, and a plurality of second communication holes communicating the first sub-chamber and the first space, wherein all the second communication holes face the inside of the first space without facing the through hole, or all the second communication holes face the second space through the through hole.
[0007] All the second communication holes face the inside of the first space without facing the through hole, the second sub-chamber is formed in a cylindrical shape, the plurality of second communication holes include a plurality of third communication holes provided at intervals in the circumferential direction of the second sub-chamber, and the plurality of third communication holes may face in a direction orthogonal to the central axis of the second sub-chamber.
[0008] The multiple second communication holes may include, in addition to the multiple third communication holes, a fourth communication hole that is arranged coaxially with the central axis of the second sub-chamber.
[0009] All second communication holes face the second space through through holes, the second sub-chamber is formed in a cylindrical shape, and the plurality of second communication holes include a plurality of fifth communication holes provided spaced apart from each other in the circumferential direction of the second sub-chamber, and the plurality of fifth communication holes may face in a direction eccentric with respect to the central axis of the second sub-chamber.
[0010] To solve the above problems, the ignition system of the present disclosure comprises: a first sub-chamber communicating with a combustion chamber through at least one first communication hole; a second sub-chamber provided with an ignition device including a first electrode, a second electrode having a through hole through which the first electrode is inserted, and an electrode gap formed between the first electrode and the second electrode; a first space on the side of the first sub-chamber partitioned by the second electrode, and a second space on the opposite side of the first sub-chamber; a through hole formed in the second electrode communicating the first space and the second space; and a plurality of second communication holes communicating the first sub-chamber and the first space, wherein gas flowing from the first sub-chamber into the first space through any of the second communication holes is sent into the first space without passing through the through hole, or gas flowing from the first sub-chamber into the first space through any of the second communication holes is sent into the second space through the through hole.
[0011] Any gas flowing from the first sub-chamber into the first space through any of the second communication holes is sent into the interior of the first space without passing through the through holes. The multiple second communication holes include a multiple third communication holes spaced apart from each other in the circumferential direction of the second sub-chamber, and the multiple third communication holes may face in a direction perpendicular to the central axis of the second sub-chamber.
[0012] The multiple second communication holes may include, in addition to the multiple third communication holes, a fourth communication hole that is arranged coaxially with the central axis of the second sub-chamber.
[0013] Gas flowing from the first sub-chamber into the first space through any of the second communication holes is also sent to the second space through the through holes, the second sub-chamber is formed in a cylindrical shape, and the plurality of second communication holes include a plurality of fifth communication holes provided spaced apart from each other in the circumferential direction of the second sub-chamber, and the plurality of fifth communication holes may face in a direction eccentric with respect to the central axis of the second sub-chamber.
[0014] According to this disclosure, combustion in the combustion chamber can be promoted.
[0015] Figure 1 is a diagram showing a schematic configuration of a gas engine according to an embodiment of the present disclosure. Figure 2 is a diagram showing a schematic configuration of an ignition system according to an embodiment of the present disclosure. Figure 3 is a diagram showing a schematic configuration of a second sub-chamber and ignition device in an ignition system according to an embodiment of the present disclosure. Figure 4 is a view of the second sub-chamber housing in an ignition system according to an embodiment of the present disclosure, viewed from below. Figure 5 is a cross-sectional view of the second sub-chamber housing in an ignition system according to an embodiment of the present disclosure, viewed in the direction of the central axis of the second sub-chamber. Figure 6 is a diagram showing a schematic configuration of the second sub-chamber and ignition device in an ignition system according to a first modification of the present disclosure. Figure 7 is a diagram showing a schematic configuration of the second sub-chamber and ignition device in an ignition system according to a second modification of the present disclosure. Figure 8 is a diagram showing a schematic configuration of the second sub-chamber and ignition device in an ignition system according to a third modification of the present disclosure. Figure 9 is a cross-sectional view of the second sub-chamber housing in an ignition system according to a third modification of the present disclosure, viewed in the direction of the central axis of the second sub-chamber.
[0016] Embodiments of this disclosure will be described below with reference to the attached drawings. The dimensions, materials, and other specific numerical values shown in the embodiments are merely examples for the purpose of facilitating understanding and do not limit this disclosure unless otherwise specified. In this specification and drawings, elements having substantially the same function or configuration are denoted by the same reference numerals to avoid redundant explanations, and elements not directly related to this disclosure are omitted from the illustrations.
[0017] Figure 1 shows a schematic configuration of the gas engine 100 according to this embodiment. As shown in Figure 1, the gas engine 100 comprises a cylinder block 102, a cylinder head 104, and a piston 106.
[0018] A cylinder 102a is formed in the cylinder block 102. The inner circumferential surface of the cylinder 102a may be formed by a cylinder liner that is press-fitted or cast into the interior of the cylinder block 102. A piston 106 is housed in the cylinder 102a. A combustion chamber 108 is formed inside the cylinder 102a. The combustion chamber 108 is partitioned by the cylinder 102a of the cylinder block 102, the cylinder head 104, and the crown surface 106a of the piston 106.
[0019] An intake port 104a and an exhaust port 104b are formed in the cylinder head 104. The intake port 104a and the exhaust port 104b open into the combustion chamber 108. The opening of the intake port 104a on the combustion chamber 108 side is opened and closed by an intake valve 110a. The opening of the exhaust port 104b on the combustion chamber 108 side is opened and closed by an exhaust valve 110b.
[0020] An ignition system 200 is provided in the cylinder head 104. The ignition system 200 is positioned, for example, on the central axis of the piston 106. The ignition system 200 comprises a first sub-chamber 202, a second sub-chamber 204, and an ignition device 206. Details of the ignition system 200 will be described later with reference to Figure 2, etc.
[0021] The gas engine 100 is, for example, a four-stroke engine. During the intake stroke, the intake valve 110a opens and the exhaust valve 110b closes, and the piston 106 moves toward bottom dead center. A mixture of fuel gas and air flows into the combustion chamber 108 from the intake port 104a. During the compression stroke, the intake valve 110a and the exhaust valve 110b close, and the piston 106 moves toward top dead center. The mixture compressed by the piston 106 is guided from the combustion chamber 108 through the first sub-chamber 202 to the second sub-chamber 204. The combustion gas produced by the ignition device 206 igniting the mixture is ejected into the combustion chamber 108 through the second sub-chamber 204 and the first sub-chamber 202. The mixture burns in the combustion chamber 108 due to the combustion gas. During the expansion stroke, the piston 106 is pushed toward bottom dead center. During the exhaust stroke, the intake valve 110a closes and the exhaust valve 110b opens, causing the piston 106 to move towards top dead center. The exhaust gas after combustion is discharged from the combustion chamber 108 through the exhaust port 104b.
[0022] The fuel gas used in the gas engine 100 is not particularly limited. However, in some cases, a flame-retardant fuel may be used in the gas engine 100. Examples of flame-retardant fuels include ammonia or dilute natural gas. When a flame-retardant fuel is used, if the combustion in the combustion chamber 108 is not sufficiently promoted, the combustion efficiency may decrease. In this embodiment, combustion in the combustion chamber 108 is promoted by modifying the ignition system 200. The details of the ignition system 200 will be described below.
[0023] Hereafter, the axial, circumferential, and radial directions of the piston 106 will also be referred to simply as the axial, circumferential, and radial directions, respectively. Hereafter, the top dead center side of the piston 106 will also be referred to as the upper side, and the bottom dead center side of the piston 106 will also be referred to as the lower side.
[0024] Figure 2 shows a schematic configuration of the ignition system 200 according to this embodiment. However, the example in Figure 2 is merely one example of the ignition system 200. As will be described later, the shape and arrangement of each component of the ignition system 200 are not limited to the example in Figure 2.
[0025] As shown in Figure 2, the ignition system 200 comprises a first sub-chamber 202, a second sub-chamber 204, and an ignition device 206.
[0026] The first sub-chamber 202 is a space that communicates with the combustion chamber 108. The first sub-chamber 202 is partitioned by the first sub-chamber housing 202a. The first sub-chamber housing 202a includes an upper housing 202a1 and a lower housing 202a2.
[0027] The upper housing 202a1 has a cylindrical shape. The upper housing 202a1 is positioned coaxially with the central axis of the piston 106. The lower part of the upper housing 202a1 is connected to the upper part of the lower housing 202a2. The upper housing 202a1 is in communication with the lower housing 202a2.
[0028] The lower housing 202a2 has a cylindrical shape. The diameter of the lower housing 202a2 is smaller than the diameter of the upper housing 202a1. The lower housing 202a2 is positioned coaxially with the central axis of the piston 106. In other words, the lower housing 202a2 is positioned coaxially with the upper housing 202a1. The lower part of the lower housing 202a2 protrudes into the combustion chamber 108. The portion of the lower housing 202a2 that protrudes into the combustion chamber 108 separates the combustion chamber 108 from the first sub-chamber 202.
[0029] The first sub-chamber 202 communicates with the combustion chamber 108 via the first communication holes 202b. For example, multiple first communication holes 202b are provided in the first sub-chamber housing 202a. Multiple first communication holes 202b are provided in the lower part of the first sub-chamber housing 202a. Multiple first communication holes 202b are provided in the portion of the first sub-chamber housing 202a facing the combustion chamber 108.
[0030] Multiple first communication holes 202b are provided at intervals from each other in the circumferential direction. For example, multiple first communication holes 202b are provided at equal intervals in the circumferential direction. However, the number and arrangement of the first communication holes 202b are not limited. For example, the number of first communication holes 202b may be one. For example, multiple first communication holes 202b may be provided at unequal intervals in the circumferential direction. The cross-sectional shape of the first communication hole 202b, which is perpendicular to the direction of extension, is, for example, circular. However, the cross-sectional shape of the first communication hole 202b is not limited. For example, the cross-sectional shape of the first communication hole 202b may be elliptical or polygonal.
[0031] The second sub-room 204 is a space that communicates with the first sub-room 202. For example, the volume of the second sub-room 204 is smaller than the volume of the first sub-room 202. The second sub-room 204 is partitioned by the second sub-room housing 204a.
[0032] The second sub-chamber housing 204a has a cylindrical shape. The second sub-chamber housing 204a is positioned coaxially with the central axis of the piston 106. In other words, the second sub-chamber housing 204a is positioned coaxially with the first sub-chamber housing 202a. The lower part of the second sub-chamber housing 204a protrudes into the first sub-chamber 202. The portion of the second sub-chamber housing 204a that protrudes into the first sub-chamber 202 separates the first sub-chamber 202 from the second sub-chamber 204.
[0033] The second sub-chamber 204 communicates with the first sub-chamber 202 via a second communication hole 204b. For example, multiple second communication holes 204b are provided in the second sub-chamber housing 204a. Multiple second communication holes 204b are provided in the lower part of the second sub-chamber housing 204a. Multiple second communication holes 204b are provided in the portion of the second sub-chamber housing 204a facing the first sub-chamber 202.
[0034] Multiple second communication holes 204b are provided at intervals from each other in the circumferential direction. For example, multiple second communication holes 204b are provided at equal intervals in the circumferential direction. However, the number and arrangement of the second communication holes 204b are not limited. For example, multiple second communication holes 204b may be provided at unequal intervals in the circumferential direction. The cross-sectional shape of the second communication hole 204b, which is perpendicular to the direction of extension, is, for example, circular. However, the cross-sectional shape of the second communication hole 204b is not limited. For example, the cross-sectional shape of the second communication hole 204b may be elliptical or polygonal.
[0035] The ignition device 206 is provided to ignite the mixture of fuel gas and air. The ignition device 206 is located in the second sub-chamber 204. Details of the configuration of the ignition device 206 will be described later.
[0036] As shown by the dashed arrow in Figure 2, during the compression stroke, a mixture of fuel gas and air is guided from the combustion chamber 108 through the first communication hole 202b to the first sub-chamber 202. As shown by the dashed arrow in Figure 2, the mixture guided to the first sub-chamber 202 is then guided from the first sub-chamber 202 through the second communication hole 204b to the second sub-chamber 204. The mixture in the second sub-chamber 204 is then ignited by the ignition device 206, producing burnt gas.
[0037] Subsequently, as shown by the solid arrows in Figure 2, the burnt gas is ejected from the second sub-chamber 204 through the second communication hole 204b into the first sub-chamber 202. The burnt gas ejected into the first sub-chamber 202 ignites the fuel-air mixture inside the first sub-chamber 202. Then, as shown by the solid arrows in Figure 2, the burnt gas is ejected from the first sub-chamber 202 through the first communication hole 202b into the combustion chamber 108. The burnt gas ejected into the combustion chamber 108 ignites the fuel-air mixture inside the combustion chamber 108.
[0038] As described above, the ignition system 200 includes a second sub-chamber 204 having a smaller volume than the first sub-chamber 202, in addition to the first sub-chamber 202. The fuel-air mixture in the second sub-chamber 204 is then ignited by the ignition device 206. Therefore, compared to directly igniting the fuel-air mixture in the first sub-chamber 202, the combustion of the fuel-air mixture in the second sub-chamber 204 can be completed earlier, accelerating the timing of flame generation. Thus, the combustion in the first sub-chamber 202 can be accelerated, and consequently, the combustion in the combustion chamber 108 can be promoted.
[0039] As described above, in the ignition system 200, combustion in the combustion chamber 108 is promoted when the air-fuel mixture in the second sub-chamber 204 is ignited by the ignition device 206. Therefore, if the ignition of the air-fuel mixture by the ignition device 206 in the second sub-chamber 204 is unstable, the promotion of combustion in the combustion chamber 108 may be hindered. In this embodiment, as will be described later, by making improvements to the orientation of the second communication hole 204b and, consequently, the flow direction of the air-fuel mixture flowing from the second communication hole 204b into the second sub-chamber 204, it is possible to stabilize the ignition of the air-fuel mixture by the ignition device 206 in the second sub-chamber 204, and consequently, to further promote combustion in the combustion chamber 108.
[0040] Figure 3 shows a schematic configuration of the second sub-chamber 204 and the ignition device 206 in the ignition system 200 according to this embodiment. In Figure 3, the second sub-chamber 204 and the ignition device 206 of the ignition system 200 are shown as an excerpt.
[0041] The ignition device 206 includes a first electrode 206a, a second electrode 206b, and an electrode gap 206c. The ignition method using the ignition device 206 is a spark-based method.
[0042] The first electrode 206a has, for example, a rod shape. The first electrode 206a extends linearly downward from the upper part of the second sub-chamber 204. The first electrode 206a is positioned coaxially with the central axis A0 of the second sub-chamber 204.
[0043] The second electrode 206b, for example, has a substantially disk shape and is arranged coaxially with the central axis A0 of the second sub-chamber 204. An insertion hole 206b1 is formed at the center of the second electrode 206b. The insertion hole 206b1 penetrates the center of the second electrode 206b. In the example of FIG. 3, the second electrode 206b has a frustum shape that slopes upward as it progresses radially outward. However, the second electrode 206b does not have to slope as it progresses radially outward, and it may slope downward as it progresses radially outward.
[0044] The outer peripheral surface of the second electrode 206b is fitted to the inner peripheral surface of the second sub-chamber housing 204a. Thereby, the internal space of the second sub-chamber 204 is partitioned by the second electrode 206b into a first space 204c on the side of the first sub-chamber 202 and a second space 204d on the side opposite to the first sub-chamber 202.
[0045] A through hole 206b2 that communicates the first space 204c and the second space 204d is formed in the second electrode 206b. The through hole 206b2 penetrates the second electrode 206b in the central axis direction of the second sub-chamber 204 (that is, the direction along the central axis A0 of the second sub-chamber 204). For example, a plurality of through holes 206b2 are provided at intervals in the circumferential direction of the second sub-chamber 204. For example, the plurality of through holes 206b2 are provided at equal intervals in the circumferential direction of the second sub-chamber 204. However, the number and arrangement of the through holes 206b2 are not limited. For example, the number of the through holes 206b2 may be singular. For example, the plurality of through holes 206b2 may be provided at unequal intervals in the circumferential direction. The shape of the through hole 206b2 is, for example, circular. However, the shape of the through hole 206b2 is not limited. For example, the shape of the through hole 206b2 may be elliptical or polygonal.
[0046] The first electrode 206a is inserted into the insertion hole 206b1 of the second electrode 206b. The outer peripheral surface of the tip portion (that is, the lower end portion) of the first electrode 206a faces the inner peripheral surface of the insertion hole 206b1 of the second electrode 206b. The electrode gap 206c is an annular space formed between the tip portion of the first electrode 206a and the inner peripheral surface of the insertion hole 206b1 of the second electrode 206b. The electrode gap 206c is also called a spark gap. The potential of the second electrode 206b is maintained at, for example, the ground potential. The ignition device 206 can generate a spark discharge in the electrode gap 206c due to the potential difference between the first electrode 206a and the second electrode 206b by applying a voltage to the first electrode 206a.
[0047] The second communication hole 204b is disposed in a portion of the second sub-chamber housing 204a below the second electrode 206b. Therefore, the second communication hole 204b connects the first sub-chamber 202 and the first space 204c of the second sub-chamber 204. In the ignition system 200, a plurality of communication holes 204b1 are provided as the plurality of second communication holes 204b, which are spaced apart from each other in the circumferential direction of the second sub-chamber 204.
[0048] FIG. 4 is a view of the second sub-chamber housing 204a in the ignition system 200 according to the present embodiment as viewed from below. As shown in FIG. 4, for example, four communication holes 204b1 are provided in the second sub-chamber housing 204a at equal intervals in the circumferential direction. However, the number and arrangement of the communication holes 204b1 are not limited to the example of FIG. 4.
[0049] Figure 5 is a cross-sectional view of the second sub-chamber housing 204a in the ignition system 200 according to this embodiment, viewed in the direction of the central axis of the second sub-chamber 204. In Figures 3 and 5, the flow of the air-fuel mixture from the first sub-chamber 202 to the second sub-chamber 204 through the communication holes 204b1 during the compression stroke is indicated by dashed arrows. As shown in Figure 5, when viewed in the direction of the central axis of the second sub-chamber 204, the air-fuel mixture flowing into the second sub-chamber 204 from each communication hole 204b1 flows toward the central axis A0 of the second sub-chamber 204. As shown in Figure 3, on a plane including the central axis A0 of the second sub-chamber 204, the air-fuel mixture flowing into the second sub-chamber 204 from each communication hole 204b1 flows in a direction perpendicular to the central axis A0 of the second sub-chamber 204. Thus, each communication hole 204b1 faces in a direction perpendicular to the central axis A0 of the second sub-chamber 204.
[0050] In this disclosure, the direction facing the hole may mean, for example, the direction along the central axis of the cylindrical portion forming the opening of the hole, or the direction of gas flow out of the hole. For example, gas flowing out of a hole flows in the direction facing the hole.
[0051] During the compression stroke, the air-fuel mixture flows from the first sub-chamber 202 to the second sub-chamber 204 through each communication hole 204b1. As described above, all communication holes 204b1 face in a direction perpendicular to the central axis A0 of the second sub-chamber 204. In other words, as shown in Figure 3, all communication holes 204b1 face the interior of the first space 204c without facing the through hole 206b2. Therefore, as indicated by the dashed arrows in Figure 3, the air-fuel mixture flowing from the first sub-chamber 202 to the first space 204c through any of the communication holes 204b1 is sent into the interior of the first space 204c without passing through the through hole 206b2. As a result, the pressure inside the first space 204c is increased.
[0052] Subsequently, as shown by the dashed arrow in Figure 3, the mixture is sent from the first space 204c to the second space 204d through the electrode gap 206c. In other words, the mixture passes upward through the electrode gap 206c. By making the flow of the mixture through the electrode gap 206c unidirectional in this way, turbulence in the gas flow within the electrode gap 206c can be suppressed. Therefore, the growth of the flame kernel in the electrode gap 206c can be promoted without being hindered. Thus, ignition of the mixture by the ignition device 206 in the second sub-chamber 204 is performed stably. After that, the burned gas is sent from the second space 204d through the through hole 206b2 to the first space 204c, and then flows out into the first sub-chamber 202 through the communication hole 204b1.
[0053] As described above, the ignition system 200 according to this embodiment includes a first sub-chamber 202 communicating with the combustion chamber 108 through at least one first communication hole 202b, a second sub-chamber 204 in which an ignition device 206 is provided, which includes a first electrode 206a, a second electrode 206b having an insertion hole 206b1 through which the first electrode 206a is inserted, and an electrode gap 206c formed between the first electrode 206a and the second electrode 206b, and inside the second sub-chamber 204, the second electrode 206b The combustion chamber 108 comprises a first space 204c on the side of the first sub-chamber 202, a second space 204d on the opposite side of the first sub-chamber 202, a through hole 206b2 formed in the second electrode 206b that connects the first space 204c and the second space 204d, and a plurality of second communication holes 204b that connect the first sub-chamber 202 and the first space 204c of the second sub-chamber 204, wherein all of the second communication holes 204b do not face the through hole 206b2 but face the interior of the first space 204c. This makes it possible to make the flow of the air-fuel mixture through the electrode gap 206c unidirectional, thereby stabilizing the ignition of the air-fuel mixture by the ignition device 206 in the second sub-chamber 204. Therefore, for example, misfires and combustion fluctuations from cycle to cycle can be suppressed. Thus, it becomes possible to further promote combustion in the combustion chamber 108.
[0054] From another perspective, as described above, the ignition system 200 according to this embodiment includes a first sub-chamber 202 communicating with the combustion chamber 108 through at least one first communication hole 202b, a second sub-chamber 204 in which an ignition device 206 is provided, which includes a first electrode 206a, a second electrode 206b having an insertion hole 206b1 through which the first electrode 206a is inserted, and an electrode gap 206c formed between the first electrode 206a and the second electrode 206b, and a first cavity on the first sub-chamber 202 side partitioned by the second electrode 206b inside the second sub-chamber 204 The device comprises a gap 204c, a second space 204d on the opposite side of the first sub-chamber 202, a through-hole 206b2 formed in the second electrode 206b that connects the first space 204c and the second space 204d, and a plurality of second communication holes 204b that connect the first sub-chamber 202 and the first space 204c of the second sub-chamber 204, wherein gas (specifically, the air-fuel mixture) flowing from the first sub-chamber 202 into the first space 204c through any of the second communication holes 204b is sent into the interior of the first space 204c without passing through the through-hole 206b2. This makes it possible to make the flow of the air-fuel mixture passing through the electrode gap 206c unidirectional, thereby stabilizing the ignition of the air-fuel mixture by the ignition device 206 in the second sub-chamber 204. Therefore, for example, misfires and combustion fluctuations from cycle to cycle can be suppressed. Therefore, combustion in the combustion chamber 108 can be further promoted.
[0055] Furthermore, in the ignition system 200 described above, the second sub-chamber 204 is formed in a cylindrical shape, and the plurality of second communication holes 204b include a plurality of third communication holes (in the above example, a plurality of communication holes 204b1) provided at intervals from each other in the circumferential direction of the second sub-chamber 204, and the plurality of third communication holes face in a direction perpendicular to the central axis A0 of the second sub-chamber 204. As a result, the pressure inside the first space 204c can be effectively increased by causing the air-fuel mixture flowing into the first space 204c from each third communication hole to collide with each other. Thus, the flow of the air-fuel mixture passing through the electrode gap 206c is appropriately made unidirectional.
[0056] In the above example, the second sub-chamber 204 is cylindrical, but the second sub-chamber 204 may be a cylindrical shape other than a cylindrical shape (for example, a rectangular cylinder). Also, the third communication hole (communication hole 204b1 in the above example) may face in a direction inclined with respect to the central axis A0 of the second sub-chamber 204.
[0057] In the above, an example of the second communication hole 204b was described with reference to the ignition system 200. However, the configuration of the second communication hole 204b is not limited to the above example. Various modifications of the ignition system 200 described above will be explained below.
[0058] Figure 6 shows a schematic configuration of the second sub-chamber 204 and ignition device 206 in the ignition system 200A according to the first modification of the present disclosure. The ignition system 200A according to the first modification differs from the ignition system 200 described above in that the second communication hole 204b includes a communication hole 204b2 in addition to the communication hole 204b1.
[0059] In the ignition system 200A, similar to the ignition system 200 described above, the multiple communication holes 204b1 are provided spaced apart from each other in the circumferential direction of the second sub-chamber 204. In the ignition system 200A, each communication hole 204b1 faces in a direction perpendicular to the central axis A0 of the second sub-chamber 204, similar to the ignition system 200 described above.
[0060] The communication hole 204b2 is positioned coaxially with the central axis A0 of the second sub-chamber 204. In other words, the communication hole 204b2 is positioned directly below the tip (i.e., lower end) of the first electrode 206a in the second sub-chamber housing 204a. The communication hole 204b2 faces the center of the electrode gap 206c in the direction of the central axis of the second sub-chamber 204. Therefore, in the ignition system 200A, during the compression stroke, as shown by the dashed arrows in Figure 6, in addition to the flow of the air-fuel mixture flowing from each communication hole 204b1 into the first space 204c, a flow of air-fuel mixture flowing from the communication hole 204b2 into the first space 204c also occurs. The air-fuel mixture flowing from the communication hole 204b2 into the first space 204c flows upward.
[0061] In the ignition system 200A, each communication hole 204b1 and communication hole 204b2 faces the interior of the first space 204c without facing the through hole 206b2. Therefore, as shown by the dashed arrows in Figure 6, the air-fuel mixture flowing from the first sub-chamber 202 into the first space 204c through either of the second communication holes 204b (i.e., each communication hole 204b1 and communication hole 204b2) is also sent into the interior of the first space 204c without passing through the through hole 206b2. This increases the pressure inside the first space 204c. Subsequently, as shown by the dashed arrows in Figure 6, the air-fuel mixture is sent from the first space 204c to the second space 204d through the electrode gap 206c.
[0062] As explained above, in the ignition system 200A, the multiple second communication holes 204b include, in addition to the multiple third communication holes (multiple communication holes 204b1 in the above example), a fourth communication hole (communication hole 204b2 in the above example) which is arranged coaxially with the central axis A0 of the second sub-chamber 204. As a result, the flow of the air-fuel mixture flowing into the first space 204c from the fourth communication hole makes it easier for the air-fuel mixture sent into the first space 204c to flow upward. Therefore, it may be possible to promote the flow of the air-fuel mixture passing upward through the electrode gap 206c. Therefore, it may be possible to make the flow of the air-fuel mixture passing through the electrode gap 206c unidirectional.
[0063] Figure 7 shows a schematic configuration of the second sub-chamber 204 and ignition device 206 in the ignition system 200B according to a second modification of the present disclosure. In the ignition system 200B according to the second modification, the direction in which the communication hole 204b1, which serves as the second communication hole 204b, faces is different compared to the ignition system 200 described above.
[0064] In the ignition system 200B, similar to the ignition system 200 described above, the multiple communication holes 204b1 are spaced apart from each other in the circumferential direction of the second sub-chamber 204. On the other hand, unlike the ignition system 200 described above, each communication hole 204b1 faces in a direction inclined with respect to the central axis A0 of the second sub-chamber 204. Specifically, when viewed in a direction perpendicular to the central axis A0 of the second sub-chamber 204, each communication hole 204b1 faces in a direction inclined upward with respect to the direction perpendicular to the central axis A0. Each communication hole 204b1 faces the through hole 206b2. Specifically, the central axis of each communication hole 204b1 faces the through hole 206b2. In other words, the straight line extending along the central axis of each communication hole 204b1 passes through the through hole 206b2. Furthermore, each communication hole 204b1 is located on the same plane as the central axis A0 of the second sub-chamber 204, similar to the ignition system 200 described above.
[0065] As shown in Figure 7, each communication hole 204b1 faces the second space 204d through the through hole 206b2. Therefore, as indicated by the dashed arrows in Figure 7, the mixture flowing from the first sub-chamber 202 into the first space 204c through any of the communication holes 204b1 is also sent to the second space 204d through the through hole 206b2. This increases the pressure inside the second space 204d.
[0066] Subsequently, as shown by the dashed arrow in Figure 7, the mixture is sent from the second space 204d to the first space 204c through the electrode gap 206c. In other words, the mixture passes downward through the electrode gap 206c. By making the flow of the mixture through the electrode gap 206c unidirectional in this way, turbulence in the gas flow within the electrode gap 206c can be suppressed. Therefore, the growth of the flame kernel in the electrode gap 206c can be promoted without being inhibited. Thus, ignition of the mixture by the ignition device 206 in the second sub-chamber 204 is performed stably. After that, the burnt gas flows out from the communication hole 204b1 into the first sub-chamber 202.
[0067] As explained above, in the ignition system 200B, unlike the ignition system 200 described above, all second communication holes 204b face the second space 204d through the through holes 206b2. In this case as well, similar to the ignition system 200 described above, the flow of the air-fuel mixture passing through the electrode gap 206c can be made unidirectional, so that the ignition of the air-fuel mixture by the ignition device 206 in the second sub-chamber 204 can be stabilized. Therefore, it becomes possible to further promote combustion in the combustion chamber 108.
[0068] From another perspective, as explained above, in the ignition system 200B, unlike the ignition system 200 described above, the gas (specifically, the fuel-air mixture) flowing from the first sub-chamber 202 into the first space 204c through either of the second communication holes 204b is also sent to the second space 204d through the through-hole 206b2. In this case as well, similar to the ignition system 200 described above, the flow of the fuel-air mixture passing through the electrode gap 206c can be made unidirectional, thereby stabilizing the ignition of the fuel-air mixture by the ignition device 206 in the second sub-chamber 204. Therefore, it becomes possible to further promote combustion in the combustion chamber 108.
[0069] Figure 8 shows a schematic configuration of the second sub-chamber 204 and ignition device 206 in the ignition system 200C according to a third modification of the present disclosure. In the ignition system 200C according to the third modification, the direction in which the communication hole 204b1, which serves as the second communication hole 204b, faces is different compared to the ignition system 200 described above.
[0070] In the ignition system 200C, similar to the ignition system 200 described above, the multiple communication holes 204b1 are spaced apart from each other in the circumferential direction of the second sub-chamber 204. Figure 9 is a cross-sectional view of the second sub-chamber housing 204a in the ignition system 200C according to a third modification of the present disclosure, viewed in the direction of the central axis of the second sub-chamber 204. As indicated by the dashed arrows in Figure 9, when viewed in the direction of the central axis of the second sub-chamber 204, the air-fuel mixture flowing into the second sub-chamber 204 from each communication hole 204b1 does not flow toward the central axis A0 of the second sub-chamber 204, but flows along a straight line that does not pass through the central axis A0. Therefore, when viewed in the direction of the central axis of the second sub-chamber 204, unlike the ignition system 200 described above, each communication hole 204b1 faces in a direction eccentric with respect to the central axis A0 of the second sub-chamber 204.
[0071] As described above, in the ignition system 200C, each communication hole 204b1 faces in a direction eccentric with respect to the central axis A0 of the second sub-chamber 204. As shown in Figure 8, when viewed in a direction perpendicular to the central axis A0 of the second sub-chamber 204, each communication hole 204b1 faces in a direction inclined upward with respect to the direction perpendicular to the central axis A0. Therefore, as indicated by the dashed arrows in Figure 8, the air-fuel mixture flowing into the first space 204c from each communication hole 204b1 is sent upward while swirling. Here, the air-fuel mixture flowing from the first sub-chamber 202 into the first space 204c through any of the communication holes 204b1 is sent to the second space 204d through the through hole 206b2. In other words, each communication hole 204b1 faces the second space 204d through the through hole 206b2. Then, by sending the mixed gas from each communication hole 204b1 to the second space 204d, the pressure inside the second space 204d is increased.
[0072] Subsequently, as shown by the dashed arrow in Figure 8, the mixture is sent from the second space 204d to the first space 204c through the electrode gap 206c. In other words, the mixture passes downward through the electrode gap 206c. By making the flow of the mixture through the electrode gap 206c unidirectional in this way, turbulence in the gas flow within the electrode gap 206c can be suppressed. Therefore, the growth of the flame kernel in the electrode gap 206c can be promoted without being hindered. Thus, ignition of the mixture by the ignition device 206 in the second sub-chamber 204 is performed stably. After that, the burnt gas flows out from the communication hole 204b1 into the first sub-chamber 202.
[0073] As explained above, in the ignition system 200C, similar to the ignition system 200B described above, all second communication holes 204b face the second space 204d through the through holes 206b2. In this case as well, similar to the ignition system 200 described above, the flow of the air-fuel mixture passing through the electrode gap 206c can be made unidirectional, so that the ignition of the air-fuel mixture by the ignition device 206 in the second sub-chamber 204 can be stabilized. Therefore, it becomes possible to further promote combustion in the combustion chamber 108.
[0074] From another perspective, as explained above, in the ignition system 200C, similar to the ignition system 200B described above, the gas (specifically, the air-fuel mixture) flowing from the first sub-chamber 202 into the first space 204c through either of the second communication holes 204b is also sent to the second space 204d through the through-hole 206b2. In this case as well, similar to the ignition system 200 described above, the flow of the air-fuel mixture through the electrode gap 206c can be made unidirectional, thereby stabilizing the ignition of the air-fuel mixture by the ignition device 206 in the second sub-chamber 204. Therefore, combustion in the combustion chamber 108 can be further promoted.
[0075] Furthermore, in the ignition system 200C described above, the second sub-chamber 204 is formed in a cylindrical shape, and the plurality of second communication holes 204b include a plurality of fifth communication holes (in the above example, a plurality of communication holes 204b1) provided at intervals from each other in the circumferential direction of the second sub-chamber 204, and the plurality of fifth communication holes face in a direction eccentric with respect to the central axis A0 of the second sub-chamber 204. As a result, the air-fuel mixture flowing into the second sub-chamber 204 from the fifth communication holes flows within the second sub-chamber 204 while swirling in the circumferential direction of the second sub-chamber 204. Here, depending on the specifications of the second sub-chamber 204 or the ignition device 206, etc. (for example, shape or dimensions, etc.), it may be possible to stabilize the ignition of the air-fuel mixture by the ignition device 206 within the second sub-chamber 204 by swirling the air-fuel mixture within the second sub-chamber 204, and furthermore, by adjusting the degree of swirling of the air-fuel mixture. In such cases, by orienting the fifth communication hole to face an eccentric direction with respect to the central axis A0 of the second sub-chamber 204, the ignition of the fuel-air mixture by the ignition device 206 within the second sub-chamber 204 can be further stabilized.
[0076] While embodiments of this disclosure have been described above with reference to the attached drawings, it goes without saying that this disclosure is not limited to such embodiments. It will be obvious to those skilled in the art that various modifications or alterations can be conceived within the scope of the claims, and these will naturally also fall within the technical scope of this disclosure.
[0077] The shapes of the first sub-chamber housing 202a and the second sub-chamber housing 204a are not limited to the example in Figure 2. For example, the upper housing 202a1 may be omitted from the example in Figure 2, and the first sub-chamber housing 202a may have a cylindrical shape as a whole.
[0078] The positional relationships of each component are not limited to the example in Figure 2. For example, the first sub-chamber housing 202a, the second sub-chamber housing 204a, and the ignition device 206 do not have to be arranged coaxially with the central axis of the piston 106. For example, the first sub-chamber housing 202a and the second sub-chamber housing 204a do not have to be arranged coaxially with each other.
[0079] In addition, in each of the above examples, a communication hole may be added that connects the first sub-chamber 202 and the second space 204d of the second sub-chamber 204.
[0080] This disclosure contributes to promoting combustion in the combustion chamber and can therefore contribute, for example, to Sustainable Development Goal (SDG) 7, "Ensure access to affordable, reliable, sustainable and modern energy," and Goal 13, "Take urgent action to combat climate change and its impacts."
[0081] 108: Combustion chamber 200: Ignition system 200A: Ignition system 200B: Ignition system 200C: Ignition system 202: First sub-chamber 202b: First connecting hole 204: Second sub-chamber 204b: Second connecting hole 204b1: Connecting hole (Third connecting hole, Fifth connecting hole) 204b2: Connecting hole (Fourth connecting hole) 204c: First space 204d: Second space 206: Ignition device 206a: First electrode 206b: Second electrode 206b1: Through hole 206b2: Through hole 206c: Electrode gap A0: Central axis
Claims
1. An ignition system comprising: a first sub-chamber communicating with a combustion chamber through at least one first communication hole; a second sub-chamber provided with an ignition device including a first electrode, a second electrode having a through hole through which the first electrode is inserted, and an electrode gap formed between the first electrode and the second electrode; a first space on the side of the first sub-chamber and a second space on the opposite side of the first sub-chamber, partitioned by the second electrode; a through hole formed in the second electrode that connects the first space and the second space; and a plurality of second communication holes connecting the first sub-chamber and the first space, wherein all of the second communication holes face the interior of the first space without facing the through hole, or all of the second communication holes face the second space through the through hole.
2. The ignition system according to claim 1, wherein all of the second communication holes face into the interior of the first space rather than facing the through holes, the second sub-chamber is formed in a cylindrical shape, the plurality of second communication holes include a plurality of third communication holes spaced apart from each other in the circumferential direction of the second sub-chamber, and the plurality of third communication holes face in a direction perpendicular to the central axis of the second sub-chamber.
3. The ignition system according to claim 2, wherein the plurality of second communication holes include, in addition to the plurality of third communication holes, a fourth communication hole arranged coaxially with the central axis of the second sub-chamber.
4. The ignition system according to claim 1, wherein all of the second communication holes face the second space through the through holes, the second sub-chamber is formed in a cylindrical shape, the plurality of second communication holes include a plurality of fifth communication holes spaced apart from each other in the circumferential direction of the second sub-chamber, and the plurality of fifth communication holes face in a direction eccentric with respect to the central axis of the second sub-chamber.
5. An ignition system comprising: a first sub-chamber communicating with a combustion chamber via at least one first communication hole; a second sub-chamber provided with an ignition device including a first electrode, a second electrode having a through hole through which the first electrode is inserted, and an electrode gap formed between the first electrode and the second electrode; a first space on the side of the first sub-chamber and a second space on the opposite side of the first sub-chamber, partitioned by the second electrode; a through hole formed in the second electrode that connects the first space and the second space; and a plurality of second communication holes connecting the first sub-chamber and the first space, wherein gas flowing from the first sub-chamber into the first space through any of the second communication holes is sent into the first space without passing through the through hole, or gas flowing from the first sub-chamber into the first space through any of the second communication holes is sent into the second space through the through hole.
6. The ignition system according to claim 5, wherein any gas flowing from the first sub-chamber into the first space through any of the second communication holes is sent into the first space without passing through the through holes, the second sub-chamber is formed in a cylindrical shape, the plurality of second communication holes include a plurality of third communication holes provided spaced apart from each other in the circumferential direction of the second sub-chamber, and the plurality of third communication holes face in a direction perpendicular to the central axis of the second sub-chamber.
7. The ignition system according to claim 6, wherein the plurality of second communication holes include, in addition to the plurality of third communication holes, a fourth communication hole arranged coaxially with the central axis of the second sub-chamber.
8. The ignition system according to claim 5, wherein any gas flowing from the first sub-chamber into the first space through any of the second communication holes is also sent to the second space through the through holes, the second sub-chamber is formed in a cylindrical shape, the plurality of second communication holes include a plurality of fifth communication holes spaced apart from each other in the circumferential direction of the second sub-chamber, and the plurality of fifth communication holes face in a direction eccentric with respect to the central axis of the second sub-chamber.
Citation Information
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