hydrogen engine

Abstract

To provide a hydrogen engine which can restrain occurrence of backfire and can achieve high engine efficiency.SOLUTION: A hydrogen engine using fuel gas containing hydrogen includes: a cylinder; a piston which can move in the cylinder; a cylinder head which forms a combustion chamber between the piston and the cylinder head, and includes an intake port connected to the combustion chamber, and a fuel supply port connected to the combustion chamber; an intake valve for opening and closing the intake port; a fuel supply valve for opening and closing the fuel supply port; and a valve train which is provided commonly for the intake valve and the fuel supply valve so as to open and close the intake valve and the fuel supply valve in an interlocking manner. Valve opening timing of the fuel supply valve is retarded from valve opening timing of the intake valve.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to hydrogen engines. [Background technology]

[0002] Patent Document 1 discloses a hydrogen engine that uses hydrogen fuel. This hydrogen engine is provided with an injector for injecting hydrogen fuel into an intake port, and the intake air flowing through the intake port is mixed with the hydrogen fuel injected from the injector and supplied to the combustion chamber. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-118109 Summary of the Invention [Problem to be solved by the invention]

[0004] Because hydrogen has a wide flammable range and a fast burning speed, when hydrogen fuel is injected into the intake port as described in Patent Document 1, backfire, in which the flame travels back to the intake port, is likely to occur, posing a risk of damaging the intake path. One possible method for suppressing such backfire is to provide a fuel supply port separate from the intake port and supply fuel gas to the combustion chamber without going through the intake port. However, because there is a period when the intake valve and the exhaust valve are open overlap, some of the fuel gas supplied from the fuel supply port to the combustion chamber is discharged from the exhaust port without being burned, resulting in reduced engine efficiency.

[0005] In view of the above circumstances, at least one embodiment of the present disclosure has an object to provide a hydrogen engine that can suppress the occurrence of flashback and achieve high engine efficiency. [Means for solving the problem]

[0006] In order to achieve the above object, a hydrogen engine according to at least one embodiment of the present disclosure comprises: A hydrogen engine that uses a fuel gas containing hydrogen, A cylinder; a piston movable within the cylinder; a cylinder head that defines a combustion chamber between itself and the piston and includes an intake port connected to the combustion chamber and a fuel supply port connected to the combustion chamber; an intake valve for opening and closing the intake port; a fuel supply valve for opening and closing the fuel supply port; a valve mechanism that is provided in common to the intake valve and the fuel supply valve and that is configured to open and close the intake valve and the fuel supply valve in conjunction with each other; Equipped with The opening timing of the fuel supply valve is configured to be more retarded than the opening timing of the intake valve.

[0007] In order to achieve the above object, a hydrogen engine according to at least one embodiment of the present disclosure comprises: A hydrogen engine that uses a fuel gas containing hydrogen, A cylinder; a piston movable within the cylinder; a cylinder head that defines a combustion chamber between itself and the piston, the cylinder head including an intake port connected to the combustion chamber, a fuel supply port connected to the combustion chamber, and an exhaust port connected to the combustion chamber; an intake valve for opening and closing the intake port; a fuel supply valve for opening and closing the fuel supply port; a valve mechanism that is provided in common to the intake valve and the fuel supply valve and that is configured to open and close the intake valve and the fuel supply valve in conjunction with each other; a cover portion configured to cover at least a portion of an outlet portion of the fuel supply port on the exhaust port side during at least a portion of an opening period of the fuel supply valve; Equipped with.

[0008] In order to achieve the above object, a hydrogen engine according to at least one embodiment of the present disclosure comprises: A hydrogen engine that uses a fuel gas containing hydrogen, A cylinder; a piston movable within the cylinder; a cylinder head that defines a combustion chamber between itself and the piston, the cylinder head including an intake port connected to the combustion chamber, a fuel supply port connected to the combustion chamber, and an exhaust port connected to the combustion chamber; an intake valve for opening and closing the intake port; a fuel supply valve for opening and closing the fuel supply port; a valve mechanism that is provided in common to the intake valve and the fuel supply valve and that is configured to open and close the intake valve and the fuel supply valve in conjunction with each other; Equipped with The lower surface of the cylinder head is formed along a plane, When the fuel supply valve abuts against a valve seat surface provided in the fuel supply port, the lower surface of the fuel supply valve is located upstream of the flow of fuel gas in the axial direction of the fuel supply valve relative to the lower surface of the cylinder head. [Effects of the Invention]

[0009] According to at least one embodiment of the present disclosure, a hydrogen engine is provided that can suppress the occurrence of flashback and achieve high engine efficiency. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic cross-sectional view of a hydrogen engine 2 according to an embodiment. [Figure 2] 2 is a side view showing an example of a detailed configuration of a valve mechanism 18. FIG. [Figure 3] 3 is an enlarged view showing an example of the configuration of the other end 44b of the intake rocker arm 44 shown in FIGS. 1 and 2 in the vicinity thereof. FIG. [Figure 4] FIG. 2 is a diagram showing an example of changes in the effective opening area of ​​each of the intake valve 10, the exhaust valve 14, and the fuel supply valve 15 in one combustion cycle of the hydrogen engine 2. [Figure 5A] FIG. 3 is a diagram for explaining an example of a detailed configuration of the fuel supply valve 15 shown in FIGS. 1 and 2, and illustrates a state in which the valve body portion 36 of the fuel supply valve 15 abuts against the valve seat surface 54 of the fuel supply port 26, thereby closing the fuel supply port 26. [Figure 5B] FIG. 3 is a diagram for explaining an example of a detailed configuration of the fuel supply valve 15 shown in FIGS. 1 and 2, and illustrates a state in which the valve body portion 36 of the fuel supply valve 15 is separated from the valve seat surface 54 of the fuel supply port 26, and the fuel supply port 26 is open. [Figure 5C] 5A is a diagram for explaining an example of the detailed configuration of the fuel supply valve 15 shown in FIGS. 1 and 2, and illustrates a state in which the valve body portion 36 of the fuel supply valve 15 is separated from the valve seat surface 54 and the fuel supply port 26 is closed by the collar portion 50 of the fuel supply valve 15 (a state between the state shown in FIG. 5A and the state shown in FIG. 5B). [Figure 6] 3 is a diagram showing the relationship between the crank angle of the hydrogen engine 2 and the lift amount of each of the exhaust valve 14 and the fuel supply valve 15. FIG. [Figure 7A] FIG. 3 is a diagram for explaining an example of the detailed configuration of the cylinder head 8 shown in FIGS. 1 and 2, and illustrates a state in which the valve body portion 36 of the fuel supply valve 15 abuts against the valve seat surface 54 of the fuel supply port 26, thereby closing the fuel supply port 26. [Figure 7B] FIG. 3 is a diagram for explaining an example of the detailed configuration of the cylinder head 8 shown in FIGS. 1 and 2, and shows a state in which the valve body portion 36 of the fuel supply valve 15 is separated from the valve seat surface 54 of the fuel supply port 26, and the fuel supply port 26 is open. [Figure 7C] 7A and 7B are diagrams for explaining an example of the detailed configuration of the cylinder head 8 shown in FIGS. 1 and 2, and illustrate a state in which the valve body portion 36 of the fuel supply valve 15 is spaced apart from the valve seat surface 54 and is in contact with the inner circumferential surface of the valve seat member 56 (a state between the state shown in FIG. 7A and the state shown in FIG. 7B). [Figure 8A] FIG. 3 is a diagram for explaining an example of the detailed configuration of the cylinder head 8 shown in FIGS. 1 and 2, and illustrates a state in which the valve body portion 36 of the fuel supply valve 15 abuts against the valve seat surface 54 of the fuel supply port 26, thereby closing the fuel supply port 26. [Figure 8B] FIG. 3 is a diagram for explaining an example of the detailed configuration of the cylinder head 8 shown in FIGS. 1 and 2, and shows a state in which the valve body portion 36 of the fuel supply valve 15 is separated from the valve seat surface 54 of the fuel supply port 26, and the fuel supply port 26 is open. [Figure 8C] 8A is a diagram for explaining an example of the detailed configuration of the cylinder head 8 shown in FIGS. 1 and 2, and shows a state in which the valve body portion 36 of the fuel supply valve 15 is separated from the valve seat surface 54 of the fuel supply port 26 and the fuel supply port 26 is open (a state between the state shown in FIG. 8A and the state shown in FIG. 8B). [Figure 9A] FIG. 3 is a diagram for explaining an example of a detailed configuration of the fuel supply valve 15 shown in FIGS. 1 and 2, and illustrates a state in which the valve body portion 36 of the fuel supply valve 15 abuts against the valve seat surface 54 of the fuel supply port 26, thereby closing the fuel supply port 26. [Figure 9B] FIG. 3 is a diagram for explaining an example of a detailed configuration of the fuel supply valve 15 shown in FIGS. 1 and 2, and illustrates a state in which the valve body portion 36 of the fuel supply valve 15 is separated from the valve seat surface 54 of the fuel supply port 26, and the fuel supply port 26 is open. [Figure 9C] 9A is a diagram for explaining an example of the detailed configuration of the fuel supply valve 15 shown in FIGS. 1 and 2, and illustrates a state in which the valve body portion 36 of the fuel supply valve 15 is spaced from the valve seat surface 54 and at least a portion of the outlet portion 70 of the fuel supply port 26 on the exhaust port 24 side is covered by the collar portion 72 (cover portion) of the fuel supply valve 15 (a state between the state shown in FIG. 9A and the state shown in FIG. 9B). [Figure 10A] 10 is a diagram for explaining an example of an area where a collar portion 72 is provided. FIG. [Figure 10B] 10 is a diagram for explaining another example of the range in which the collar portion 72 is provided. FIG. [Figure 11] 1 and 2. FIG. 4 is a diagram illustrating yet another example of the detailed configuration of the cylinder head 8 shown in FIGS. [Figure 12A] 10 is a diagram for explaining an example of a range in which a protrusion 76 of a mask plate 74 is provided. FIG. [Figure 12B]10 is a diagram for explaining another example of the range in which the protrusions 76 of the mask plate 74 are provided. FIG. [Figure 13] 1 and 2. FIG. 4 is a diagram illustrating yet another example of the detailed configuration of the cylinder head 8 shown in FIGS. [Figure 14A] 10 is a diagram for explaining an example of a range in which a protrusion 77 of a valve seat member 56 is provided. FIG. [Figure 14B] 10 is a diagram for explaining another example of the range in which the protrusion 77 of the valve seat member 56 is provided. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, several embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the invention. For example, expressions expressing relative or absolute arrangement such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial" not only express such an arrangement exactly, but also express a state in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained. For example, expressions such as "identical," "equal," and "homogeneous" that indicate that something is in an equal state not only indicate a state of strict equality, but also indicate a state in which there is a tolerance or a difference to the extent that the same function is obtained. For example, expressions representing shapes such as a square shape or a cylindrical shape not only represent shapes such as a square shape or a cylindrical shape in the strict geometric sense, but also represent shapes including uneven portions, chamfered portions, etc., to the extent that the same effect can be obtained. On the other hand, the expressions "comprise," "include," "have," "includes," or "have" of one element are not exclusive expressions that exclude the presence of other elements.

[0012] (hydrogen engine) 1 is a schematic cross-sectional view of a hydrogen engine 2 according to one embodiment. The hydrogen engine 2 will be described below using a four-stroke engine that uses fuel gas containing hydrogen as an example. The hydrogen concentration of the fuel gas used by the hydrogen engine 2 may be, for example, 50% or more, 75% or more, or 99% or more.

[0013] As shown in FIG. 1, the hydrogen engine 2 includes a cylinder 4, a piston 6, a cylinder head 8, an intake valve 10, a valve spring 12, an exhaust valve 14, a fuel supply valve 15, a valve spring 16, and a valve mechanism 18.

[0014] The piston 6 is configured to be movable within the cylinder 4. The piston 6 reciprocates within the cylinder 4 so that the outer circumferential surface of the piston 6 slides against the inner circumferential surface of the cylinder 4, and a crankshaft (not shown) connected to the piston 6 rotates in conjunction with the reciprocating motion of the piston 6.

[0015] The cylinder head 8 forms a combustion chamber 20 between itself and the piston 6. The cylinder head 8 includes an intake port 22 connected to the combustion chamber 20, an exhaust port 24 connected to the combustion chamber 20, and a fuel supply port 26 connected to the combustion chamber 20. In the illustrated example, a lower surface 9 of the cylinder head 8 is formed along a plane perpendicular to the axial direction of the piston 6.

[0016] The intake valve 10 is configured to open and close the intake port 22. The intake valve 10 includes a valve stem 28, a valve element 30 provided at one end of the valve stem 28, and a force receiving portion 32 provided at the other end of the valve stem 28. In the illustrated example, the valve stem 28 extends vertically, the valve element 30 is provided at the lower end of the valve stem 28, and the force receiving portion 32 is provided at the upper end of the valve stem 28. In the illustrated example, the valve element 30 is formed in a truncated cone shape so that the outer diameter of the valve element 30 decreases toward the upstream side of the intake air flow, and an inclined surface of the truncated cone (an inclined surface inclined with respect to the axial direction of the intake valve 10) is arranged to be able to abut against the valve seat surface of the intake port 22 in the axial direction of the intake valve 10 (the axial direction of the valve stem 28). In the illustrated example, the force receiving portion 32 is formed in a plate shape along a plane perpendicular to the axial direction of the intake valve 10.

[0017] The valve spring 12 is sandwiched in a compressed state between the upper surface of the cylinder head 8 and the lower surface of the force receiving portion 32, and urges the force receiving portion 32 upward so as to urge the intake valve 10 in the closing direction.

[0018] The exhaust valve 14 is configured to be able to open and close the exhaust port 24. The exhaust valve 14 has a structure similar to that of the intake valve 10, and a valve spring (not shown) biases the exhaust valve 14 in a direction to close it.

[0019] The fuel supply valve 15 is configured to be able to open and close the fuel supply port 26. The fuel supply valve 15 includes a valve stem 34, a valve element portion 36 provided on one end of the valve stem 34, and a force receiving portion 38 provided on the other end of the valve stem 34. In the illustrated example, the valve stem 34 extends in the up-down direction, the valve element portion 36 is provided at the lower end of the valve stem 34, and the force receiving portion 38 is provided at the upper end of the valve stem 34. In the illustrated example, the valve element portion 36 is formed in a truncated cone shape so that the outer diameter of the valve element portion 36 decreases toward the upstream side of the fuel gas flow, and an inclined surface 53 of the truncated cone shape (an inclined surface inclined with respect to the axial direction of the fuel supply valve 15) is arranged to be able to abut against a valve seat surface 54 of the fuel supply port 26 in the axial direction of the fuel supply valve 15 (the axial direction of the valve stem 34). In the illustrated example, the force receiving portion 38 is formed in a plate shape along a plane perpendicular to the axial direction of the fuel supply valve 15.

[0020] The valve spring 16 is sandwiched in a compressed state between the upper surface of the cylinder head 8 and the lower surface of the force receiving portion 38, and urges the force receiving portion 38 upward so as to urge the fuel supply valve 15 in the closing direction.

[0021] The valve mechanism 18 is provided in common to the intake valve 10 and the fuel supply valve 15, and is configured to open and close the intake valve 10 and the fuel supply valve 15 in conjunction with each other. An example of the detailed configuration of the valve mechanism 18 will be described later.

[0022] In the hydrogen engine 2, fuel gas supplied from the fuel supply port 26 and air supplied from the intake port 22 are mixed in the combustion chamber 20 and ignited by an ignition device (not shown), resulting in combustion of the combustion gas. In the above configuration, the fuel supply port 26 is provided separately from the intake port 22, and fuel gas containing hydrogen is supplied from the fuel supply port 26 to the combustion chamber 20 without passing through the intake port 22. This makes it possible to suppress flashback, which is when a flame travels back to the intake port 22.

[0023] (Valve train) FIG. 2 is a side view showing an example of the detailed configuration of the valve mechanism 18. As shown in FIG. As shown in FIG. 2, the valve train 18 includes an intake camshaft 40, an intake cam 41, a push rod 42, an intake rocker arm 44, a rocker arm shaft 46, and a fuel supply valve arm 48.

[0024] The intake cam 41 is formed integrally with the intake camshaft 40. The intake camshaft 40 rotates together with the intake cam 41 in conjunction with the rotation of a crankshaft (not shown) of the hydrogen engine 2. The lower end of the push rod 42 abuts against the outer peripheral surface (cam surface) of the intake cam 41, and as the intake cam 41 rotates, the distance r between the push rod 42 and the rotation axis C1 of the intake cam 41 changes, causing the push rod 42 to reciprocate in the axial direction of the push rod 42.

[0025] The intake rocker arm 44 is supported by a rocker arm shaft 46 so as to be rotatable about the central axis C2 of the rocker arm shaft 46 (the rotation axis of the intake rocker arm 44). The underside of one end 44a of the intake rocker arm 44 abuts against the upper end of the push rod 42. As the push rod 42 reciprocates in the axial direction of the push rod 42 in response to the rotation of the intake cam 41, the upper end of the push rod 42 presses against the underside of one end 44a of the intake rocker arm 44, causing the intake rocker arm 44 to rotate (swing) about the rotation axis C2.

[0026] The underside of the other end 44b of the intake rocker arm 44 is capable of pressing against the intake valve 10 when the intake rocker arm 44 rotates. When the intake rocker arm 44 rotates, the underside of the other end 44b of the intake rocker arm 44 presses down on the intake valve 10 against the biasing force of the valve spring 12 (see FIG. 1), causing the intake valve 10 to move in the opening direction. Furthermore, when the intake rocker arm 44 rotates, the other end 44b of the intake rocker arm 44 is displaced in the direction of the biasing force of the valve spring 12, causing the intake valve 10 to move in the closing direction.

[0027] The fuel supply valve arm 48 is connected to the other end 44b of the intake rocker arm 44, and rotates around the rotation axis C2 together with the intake rocker arm 44. When the fuel supply valve arm 48 rotates around the rotation axis C2, the tip end 48a of the fuel supply valve arm 48 can press the fuel supply valve 15.

[0028] When the intake rocker arm 44 rotates, the tip 48a of the fuel supply valve arm 48 presses down on the fuel supply valve 15 against the biasing force of the valve spring 16 (see FIG. 1), thereby moving the fuel supply valve 15 in the opening direction. When the intake rocker arm 44 rotates, the tip 48a of the fuel supply valve arm 48 is displaced in the direction of the biasing force of the valve spring 16, thereby moving the fuel supply valve 15 in the closing direction.

[0029] (Fuel supply valve and its surrounding structure) Figure 3 is an enlarged view showing an example of the configuration of the vicinity of the other end 44b of the intake rocker arm 44 shown in Figures 1 and 2. Figure 4 is a view showing an example of changes in the effective opening area of ​​each of the intake valve 10, exhaust valve 14, and fuel supply valve 15 during one combustion cycle of the hydrogen engine 2.

[0030] 3, for example, if the distance between the fuel supply valve arm 48 and the fuel supply valve 15 is g1 and the distance between the intake rocker arm 44 and the intake valve 10 is g2, the maximum value g1max of the distance g1 in one combustion cycle of the hydrogen engine 2 may be larger than the maximum value g2max of the distance g2 in one combustion cycle of the hydrogen engine 2. For example, in the configuration shown in FIG. 2, when the distance r between the rotation center C1 of the intake cam 41 and the push rod 42 is minimum during one rotation of the intake cam 41, the distance g1 between the fuel supply valve arm 48 and the fuel supply valve 15 and the distance g2 between the intake rocker arm 44 and the intake valve 10 are maximum values ​​g1max and g2max, respectively (i.e., the intake valve 10 and the fuel supply valve 15 are each in a closed position), and this maximum value g1max is larger than the maximum value g2max.

[0031] As a result, as shown in Fig. 4, during the intake stroke of the hydrogen engine 2, the opening timing FO of the fuel supply valve 15 is retarded relative to the opening timing IO of the intake valve 10. In Fig. 4, the dashed-dotted line indicates the effective opening area of ​​the exhaust valve 14 (the throat area corresponding to the position of the exhaust valve 14 in the exhaust port 24), the solid line indicates the effective opening area of ​​the intake valve 10 (the throat area corresponding to the position of the intake valve 10 in the intake port 22), and the dashed line indicates the effective opening area of ​​the fuel supply valve 15 (the throat area corresponding to the position of the fuel supply valve 15 in the fuel supply port 26). In Fig. 4, EO indicates the opening timing of the exhaust valve 14, EC indicates the closing timing of the exhaust valve 14, FC indicates the closing timing of the fuel supply valve 15, and IC indicates the closing timing of the intake valve 10. In addition, in this specification, "valve opening timing" means the timing when the valve starts to open (the timing when the effective opening area starts to increase from 0), and "valve closing timing" means the timing when the valve closes (the timing when the effective opening area becomes 0).

[0032] In the configuration shown in FIG. 3, the distance g1 between the fuel supply valve arm 48 and the fuel supply valve 15 may be greater than 0 at the closing timing EC of the exhaust valve 14 during the exhaust stroke of the hydrogen engine 2 (see FIG. 4).

[0033] According to the hydrogen engine 2, a fuel supply port 26 is provided in addition to the intake port 22, and fuel gas containing hydrogen is supplied to the combustion chamber 20 from the fuel supply port 26 without passing through the intake port 22. This makes it possible to suppress the occurrence of flashback, where a flame travels back to the intake port 22.

[0034] Furthermore, by making the maximum value g1max of the distance g1 in one combustion cycle of the hydrogen engine 2 greater than the maximum value g2max of the distance g2 in that one combustion cycle of the hydrogen engine 2, the opening timing FO of the fuel supply valve 15 can be retarded relative to the opening timing IO of the intake valve 10. Therefore, even if there is a period in which the opening periods of the intake valve 10 and the exhaust valve 14 overlap (the period from the opening timing IO of the intake valve 10 to the closing timing EC of the exhaust valve 14 in FIG. 4), it is possible to prevent a portion of the fuel gas supplied from the fuel supply port 26 to the combustion chamber 20 from being discharged from the exhaust port 24 without being burned. This prevents a decrease in engine efficiency, thereby achieving a highly efficient hydrogen engine 2. Furthermore, by making the distance g1 between the fuel supply valve arm 48 and the fuel supply valve 15 at the closing timing EC of the exhaust valve 14 greater than zero, the opening timing FO of the fuel supply valve 15 can be retarded relative to the closing timing EC of the exhaust valve 14. Therefore, it is possible to effectively prevent a portion of the fuel gas supplied from the fuel supply port 26 to the combustion chamber 20 from being discharged from the exhaust port 24 without being burned.

[0035] 5A to 5C are diagrams illustrating an example of a detailed configuration of the fuel supply valve 15 shown in FIGS. 1 and 2. Fig. 5A shows a state in which the valve body 36 of the fuel supply valve 15 abuts against the valve seat surface 54 of the fuel supply port 26, thereby closing the fuel supply port 26. Fig. 5B shows a state in which the valve body 36 of the fuel supply valve 15 is separated from the valve seat surface 54 of the fuel supply port 26, thereby opening the fuel supply port 26. Fig. 5C shows a state in which the valve body 36 of the fuel supply valve 15 is separated from the valve seat surface 54, thereby closing the fuel supply port 26 by the collar portion 50 of the fuel supply valve 15 (a state between the state shown in Fig. 5A and the state shown in Fig. 5B).

[0036] 5A to 5C, the fuel supply valve 15 includes a collar portion 50 in addition to the valve stem 34, the valve body portion 36, and the force receiving portion 38. The cylinder head 8 also includes a cylinder head main body 52 and an annular valve seat member 56 that forms an annular valve seat surface 54 of the fuel supply port 26 and is configured as a separate body from the cylinder head main body 52.

[0037] In the illustrated example, the collar portion 50 is provided adjacent to the valve disc portion 36 on the valve stem 34 on the side of the valve disc portion 36 (at the upper end of the valve disc portion 36), and is formed in a disk or cylindrical shape. The outer diameter of the collar portion 50 is larger than the outer diameter of the valve stem 34 and substantially matches the flow path width of the fuel supply port 26, i.e., the inner diameter of the annular valve seat member 56. The outer diameter of the collar portion 50 is set to allow the outer surface of the collar portion 50 to slide on the flow path wall 75 of the fuel supply port 26 (the inner surface of the valve seat member 56 in the illustrated example). Furthermore, when the valve disc portion 36 abuts against the valve seat surface 54 of the fuel supply port 26 in the axial direction of the fuel supply valve 15 (see FIG. 5A ), the collar portion 50 is located upstream of the valve seat surface 54 in the axial direction of the fuel supply valve 15 in the flow of fuel gas.

[0038] Here, as shown in Fig. 5C, the height of the collar portion 50 in the axial direction of the fuel supply valve 15 is H1, and as shown in Fig. 6, the lift amount of the fuel supply valve 15 at the closing timing EC (see Fig. 4) of the exhaust valve 14 during the exhaust stroke of the hydrogen engine 2 is L. The collar portion 50 is configured to satisfy H1 > 0.7 × L. More preferably, the collar portion 50 is configured to satisfy H1 > L. In Fig. 6, the horizontal axis represents the crank angle of the hydrogen engine 2, and the vertical axis represents the lift amounts of the exhaust valve 14 and the fuel supply valve 15. The lift amount L shown in Fig. 6 represents the distance between the valve body portion 36 of the fuel supply valve 15 and the valve seat surface 54 at the closing timing EC (see Fig. 4) of the exhaust valve 14 during the exhaust stroke of the hydrogen engine 2.

[0039] With the configuration including the collar portion 50, as shown in FIG. 5C , even if the valve body portion 36 moves away from the valve seat surface 54, the fuel supply port 26 can be kept closed or the opening area of ​​the fuel supply port 26 can be kept small while the outer circumferential surface of the collar portion 50 abuts against the flow path wall 75 of the fuel supply port 26. This prevents fuel gas from being supplied to the combustion chamber 20 at the initial lift of the fuel supply valve 15. This allows the opening timing FO of the fuel supply valve 15 to be retarded relative to the opening timing IO of the intake valve 10. Therefore, even if there is a period in which the opening periods of the intake valve 10 and the exhaust valve 14 overlap (the period from the opening timing IO of the intake valve 10 to the closing timing EC of the exhaust valve 14 in FIG. 4 ), it is possible to prevent a portion of the fuel gas supplied from the fuel supply port 26 to the combustion chamber 20 from being discharged from the exhaust port 24 without being burned. This prevents a decrease in engine efficiency, thereby achieving a highly efficient hydrogen engine 2.

[0040] Furthermore, as described above, by providing the fuel supply valve 15 with the collar portion 50 that satisfies H1>0.7L (more preferably by satisfying H1>L), the opening timing FO of the fuel supply valve 15 can be made more retarded than the closing timing EC of the exhaust valve 14, thereby effectively preventing a portion of the fuel gas supplied from the fuel supply port 26 to the combustion chamber 20 from being discharged from the exhaust port 24 without being burned.

[0041] 1 and 2. Fig. 7A shows a state in which the valve body 36 of the fuel supply valve 15 is in contact with the valve seat surface 54 of the fuel supply port 26, thereby closing the fuel supply port 26. Fig. 7B shows a state in which the valve body 36 of the fuel supply valve 15 is separated from the valve seat surface 54 of the fuel supply port 26, thereby opening the fuel supply port 26. Fig. 7C shows a state in which the valve body 36 of the fuel supply valve 15 is separated from the valve seat surface 54, thereby contacting the inner circumferential surface of the valve seat member 56 (a state between the state shown in Fig. 7A and the state shown in Fig. 7B).

[0042] 7A to 7C, the fuel supply port 26 includes a first flow path portion 60 provided along the axial direction of the fuel supply valve 15, a valve seat surface 54 provided downstream of the first flow path portion 60, and a second flow path portion 62 provided downstream of the valve seat surface 54 and having a flow path width W2 larger than the flow path width W1 of the first flow path portion 60. In the illustrated example, a step 65 is formed between an opening end 63 on the outlet side of the fuel supply port 26 and the valve seat surface 54.

[0043] The outer diameter D of the valve body 36 is approximately equal to the flow path width W2 of the second flow path portion 62, and a downstream edge 55 (maximum outer diameter portion) of the outer peripheral surface 53 (the inclined surface 53 described above) of the valve body 36 of the fuel supply valve 15 is configured to slide on a flow path wall 64 of the second flow path portion 62. The outer diameter D of the valve body 36 means the maximum value of the outer diameter of the valve body 36, and in the illustrated example, means the outer diameter of the valve body 36 at the lower end of the valve body 36.

[0044] 7C, the length of the second flow path section 62 in the axial direction of the fuel supply valve 15 (the height of the step 65) is H2, and as shown in Fig. 6, the lift amount of the fuel supply valve 15 at the closing timing EC of the exhaust valve 14 during the exhaust stroke of the hydrogen engine 2 is L. The second flow path section 62 is configured to satisfy H2>0.7L. More preferably, the second flow path section 62 is configured to satisfy H2>L.

[0045] 7A to 7C , a second flow path portion 62 having a flow path width W2 larger than the flow path width W1 of the first flow path portion 60 is provided downstream of the valve seat surface 54, and the outer peripheral surface 53 of the valve body 36 is configured to slide on a flow path wall 64 of the second flow path portion 62. Therefore, as shown in FIG. 7C , even if the valve body 36 moves away from the valve seat surface 54, the fuel supply port 26 can be kept closed or the opening area of ​​the fuel supply port 26 can be kept small while the outer peripheral surface 53 of the valve body 36 slides on the flow path wall 64 of the second flow path portion 62. This allows the opening timing FO of the fuel supply valve 15 to be retarded relative to the opening timing IO of the intake valve 10. Therefore, even if there is a period during which the opening periods of the intake valve 10 and the exhaust valve 14 overlap, it is possible to prevent a portion of the fuel gas supplied from the fuel supply port 26 to the combustion chamber 20 from being discharged from the exhaust port 24 without being burned. This makes it possible to suppress a decrease in engine efficiency and realize a highly efficient hydrogen engine 2.

[0046] Furthermore, as described above, by satisfying H2>0.7L (more preferably by satisfying H2>L), the opening timing FO of the fuel supply valve 15 can be retarded relative to the closing timing EC of the exhaust valve 14, thereby effectively preventing a portion of the fuel gas supplied from the fuel supply port 26 to the combustion chamber 20 from being discharged from the exhaust port 24 without being burned.

[0047] 8A to 8C are diagrams illustrating another example of the detailed configuration of the cylinder head 8 shown in FIGS. 1 and 2. FIG. 8A shows a state in which the valve body 36 of the fuel supply valve 15 abuts against the valve seat surface 54 of the fuel supply port 26, thereby closing the fuel supply port 26. FIG. 8B shows a state in which the valve body 36 of the fuel supply valve 15 is separated from the valve seat surface 54 of the fuel supply port 26, thereby opening the fuel supply port 26. FIG. 8C shows a state in which the valve body 36 of the fuel supply valve 15 is separated from the valve seat surface 54 of the fuel supply port 26, thereby opening the fuel supply port 26 (a state between the state shown in FIG. 8A and the state shown in FIG. 8B).

[0048] 8A to 8C, the fuel supply port 26 includes a first flow path portion 60 provided along the axial direction of the fuel supply valve 15, a valve seat surface 54 provided downstream of the first flow path portion 60, and a second flow path portion 62 provided downstream of the valve seat surface 54 and having a flow path width W2 (see FIG. 8A) larger than the flow path width W1 of the first flow path portion 60. In the illustrated example, a step 65 is formed between an outlet-side opening end 63 of the fuel supply port 26 and the valve seat surface 54. The flow path width W2 of the second flow path portion 62 is larger than the outer diameter D (see FIG. 8A) of the valve body portion 36. The outer diameter D of the valve body portion 36 refers to the maximum outer diameter of the valve body portion 36, and in the illustrated example, refers to the outer diameter of the valve body portion 36 at the lower end of the valve body portion 36.

[0049] Furthermore, as shown in FIG. 8A , when the fuel supply valve 15 is in contact with the valve seat surface 54 provided on the fuel supply port 26, the lower surface 66 of the fuel supply valve 15 is located upstream of the flow of fuel gas in the axial direction of the fuel supply valve 15, i.e., above the lower surface 9 of the cylinder head 8.

[0050] Furthermore, when the distance between the lower surface 66 of the fuel supply valve 15 and the lower surface 9 of the cylinder head 8 in the axial direction of the fuel supply valve 15 when the fuel supply valve 15 is in contact with the valve seat surface 54 provided on the fuel supply port 26 as shown in FIG. 8A is H3, and when the lift amount of the fuel supply valve 15 at the closing timing EC of the exhaust valve 14 during the exhaust stroke of the hydrogen engine 2 as shown in FIG. 6 is L, the second flow path section 62 is configured so that H3>L is satisfied.

[0051] 8A to 8C, even if the valve body portion 36 is separated from the valve seat surface 54, as shown in Fig. 8C, the fuel gas flows through the second flow path portion 62 before being supplied to the combustion chamber 20, thereby delaying the time it takes for the fuel gas to reach the position of the exhaust valve 14. Therefore, even if there is a period during which the opening period of the intake valve 10 and the opening period of the exhaust valve 14 overlap (the period from the opening timing IO of the intake valve 10 to the closing timing EC of the exhaust valve 14 in Fig. 4), it is possible to prevent a portion of the fuel gas supplied from the fuel supply port 26 to the combustion chamber 20 from being discharged from the exhaust port 24 without being burned. This prevents a decrease in engine efficiency, making it possible to achieve a highly efficient hydrogen engine 2.

[0052] Furthermore, by satisfying H3>L as described above, the opening timing FO of the fuel supply valve 15 can be retarded relative to the closing timing EC of the exhaust valve 14. This effectively prevents a portion of the fuel gas supplied from the fuel supply port 26 to the combustion chamber 20 from being discharged from the exhaust port 24 without being burned.

[0053] 9A to 9C are diagrams illustrating another example of the detailed configuration of the fuel supply valve 15 shown in Fig. 1 and Fig. 2. Fig. 9A shows a state in which the valve body 36 of the fuel supply valve 15 abuts against the valve seat surface 54 of the fuel supply port 26, thereby closing the fuel supply port 26. Fig. 9B shows a state in which the valve body 36 of the fuel supply valve 15 is separated from the valve seat surface 54 of the fuel supply port 26, thereby opening the fuel supply port 26. Fig. 9C shows a state in which the valve body 36 of the fuel supply valve 15 is separated from the valve seat surface 54, and at least a portion of the outlet portion 70 of the fuel supply port 26 on the exhaust port 24 side is covered by the collar portion 72 (cover portion) of the fuel supply valve 15 (a state between the state shown in Fig. 9A and the state shown in Fig. 9B).

[0054] 9A to 9C , the collar portion 72 is provided adjacent to the valve disc portion 36 on the valve stem 34 (at the upper end of the valve disc portion 36), has a fan shape when viewed in the axial direction of the fuel supply valve 15, and is provided to protrude from the valve stem 34 in the radial direction of the valve stem 34. The amount of protrusion of the collar portion 72 from the valve stem 34 in the radial direction of the valve stem 34 (the length of the chord of the fan shape) may be set to an amount of protrusion that allows the outer circumferential surface of the collar portion 72 to slide on the flow path wall of the fuel supply port 26 (the inner circumferential surface of the valve seat member 56). Furthermore, in a state in which the valve disc portion 36 abuts against the valve seat surface 54 of the fuel supply port 26 in the axial direction of the fuel supply valve 15 (see FIG. 9A ), the collar portion 72 is located upstream of the valve seat surface 54 in the flow of fuel gas in the axial direction of the fuel supply valve 15.

[0055] 9A to 9C, the collar portion 72 is configured to cover at least a portion of the outlet portion 70 of the fuel supply port 26 on the exhaust port 24 side during at least a portion of the opening period of the fuel supply valve 15. This prevents fuel gas from flowing from the fuel supply port 26 toward the exhaust port 24 during the initial lift operation of the fuel supply valve 15, thereby directing the fuel gas from the fuel supply port 26 toward the intake port 22. This prevents fuel gas from passing through from the fuel supply port 26 toward the exhaust port 24 during the opening period of the exhaust valve 14. Note that in a configuration including the collar portion 72, a rotation stopper may be provided to prevent the fuel supply valve 15 from rotating. The rotation stopper may be achieved, for example, by providing a notch in the valve stem 34 of the fuel supply valve 15 and providing an engaging portion in the cylinder head 8 that engages with the notch.

[0056] 10A, the collar portion 72 may be provided in a range S1 on the exhaust port 24 side in the circumferential direction around the axis C3 (the central axis of the valve stem 34) of the fuel supply valve 15. In the example shown in Fig. 10A, the side on which the two intake ports 22 are arranged with respect to a plane K including the axis C3 of the fuel supply valve 15 is defined as the intake port 22 side, and the side on which the two exhaust ports 24 are arranged is defined as the exhaust port 24 side.

[0057] 10B, the collar portion 72 may be provided in a range of 180° or more, including a range S1 on the exhaust port 24 side, in the circumferential direction around the axis C3 of the fuel supply valve 15. In the example shown in Fig. 10B, the collar portion 72 is provided in the circumferential direction around the axis of the fuel supply valve 15, across the range S1 on the exhaust port 24 side and a range S2 adjacent to the upstream side of the range S1 in the swirling direction of the swirling flow of intake air that has flowed from the intake port 22 into the combustion chamber 20.

[0058] More specifically, if the strength of the swirl flow S is a dimensionless number indicating how many times the swirling flow of intake air flowing from the intake port 22 into the combustion chamber 20 circulates around the combustion chamber 20 during one rotation of the hydrogen engine 2, the width of the crank angle corresponding to the period during which the opening period of the exhaust valve 14 and the opening period of the fuel supply valve 15 overlap during one combustion cycle of the hydrogen engine 2 (the width of the crank angle from the opening timing FO of the fuel supply valve 15 to the closing timing EC of the exhaust valve 14 in Figure 6) is an angle θ, the collar portion 72 may be configured in a range that includes, in the circumferential direction around the axis C3 of the fuel supply valve 15, a range S1 on the exhaust port 24 side and a range S2 at an angle θ from the upstream end of the range S1 in the rotational direction of the swirl flow to the upstream side in the rotational direction of the swirl flow. This makes it possible to effectively prevent fuel gas from passing through from the fuel supply port 26 to the exhaust port 24 while the exhaust valve 14 is open, taking into account the strength S of the swirling flow of the intake air that has flowed into the combustion chamber 20.

[0059] FIG. 11 is a diagram for explaining yet another example of the detailed configuration of the cylinder head 8 shown in FIGS. In the configuration shown in FIG. 11 , the cylinder head 8 includes a cylinder head main body 52, an annular valve seat member 56 that forms the valve seat surface 54 of the fuel supply port 26 and is configured as a separate body from the cylinder head main body 52, and a mask plate 74 that is positioned between the cylinder head main body 52 and the valve seat member 56 in the axial direction of the fuel supply valve 15.

[0060] The mask plate 74 is located upstream of the flow of fuel gas with respect to the valve seat member 56 in the axial direction of the fuel supply valve 15, and is sandwiched between the cylinder head main body 52 and the valve seat member 56. The mask plate 74 has a fan shape when viewed in the axial direction of the fuel supply valve 15, and includes a protrusion 76 (cover portion) that protrudes from a flow path wall 75 of the fuel supply port 26 toward the valve stem 34. The amount of protrusion of the mask plate 74 from the flow path wall 75 in the radial direction of the valve stem 34 (the length of the chord of the fan shape) may be set to a protrusion amount that allows the inner peripheral edge of the mask plate 74 to slide on the outer peripheral surface of the valve stem 34.

[0061] The protrusion 76 of the mask plate 74 is configured to cover at least a portion of the outlet portion 70 of the fuel supply port 26 on the exhaust port 24 side. This makes it difficult for fuel gas to flow from the fuel supply port 26 to the exhaust port 24 side, thereby preventing a portion of the fuel gas supplied from the fuel supply port 26 to the combustion chamber 20 from being discharged from the exhaust port 24 without being burned. Furthermore, compared to the configurations shown in FIGS. 9A to 9C , the weight of the fuel supply valve 15 is reduced, thereby improving the responsiveness of the fuel supply valve 15 and facilitating the manufacture and quality control of the fuel supply valve 15. Furthermore, because it is difficult for fuel gas to be supplied to the exhaust port 24 side regardless of the lift amount of the fuel supply valve 15, the fuel distribution in the cylinder 4 becomes such that the fuel concentration is high on the intake side and low on the exhaust side. As a result, the intake side burns before the exhaust side, which helps to suppress knocking (if the fuel concentration were uniform, the exhaust side, which has a higher temperature, would burn first, and the intake side would burn slowly, causing the end gas remaining on the low-temperature wall of the intake side to self-ignite, resulting in knocking).

[0062] In a configuration including the mask plate 74, as shown in Fig. 12A, for example, the protrusion 76 of the mask plate 74 may be provided in a range S1 on the exhaust port 24 side in the circumferential direction around the axis C of the fuel supply valve 15. In the example shown in Fig. 12A, the side on which the two intake ports 22 are arranged with respect to a plane K including the axis C of the fuel supply valve 15 is defined as the intake port 22 side, and the side on which the two exhaust ports 24 are arranged is defined as the exhaust port 24 side.

[0063] 12B , the protrusion 76 of the mask plate 74 may be provided in a range of 180° or more including a range S1 on the exhaust port 24 side in the circumferential direction around the axis of the fuel supply valve 15. In the example shown in FIG. 12B , the protrusion 76 of the mask plate 74 is provided in a range S1 on the exhaust port 24 side and a range S2 adjacent to the upstream side of the range S1 in the swirling direction of the swirling flow of the intake air that has flowed into the combustion chamber from the intake port in the circumferential direction around the axis of the fuel supply valve 15. More specifically, when the product of the strength S of the swirling flow and the angular width OL is defined as an angle θ, the protrusion 76 of the mask plate 74 may be configured in a range including the range S1 on the exhaust port 24 side and a range S2 at an angle θ from the upstream end of the range S1 in the rotational direction of the swirling flow to the upstream side in the rotational direction of the swirling flow in the circumferential direction around the axis C of the fuel supply valve 15. This makes it possible to effectively prevent fuel gas from passing through from the fuel supply port 26 to the exhaust port 24 while the exhaust valve is open, taking into consideration the strength S of the swirl flow of the intake air that has flowed into the combustion chamber 20.

[0064] FIG. 13 is a diagram for explaining yet another example of the detailed configuration of the cylinder head 8 shown in FIGS. 13 , the annular valve seat member 56 includes a protruding portion 77 (cover portion) that protrudes from a flow path wall 75 of the fuel supply port 26 toward the valve stem 34. The amount of protrusion of the valve seat member 56 from the flow path wall 75 in the radial direction of the valve stem 34 (the length of the chord of the sector shape) may be set to an amount of protrusion that allows the protruding portion 77 of the valve seat member 56 to slide on the outer circumferential surface of the valve stem 34.

[0065] The protrusion 77 of the valve seat member 56 is configured to cover at least a portion of the outlet portion 70 of the fuel supply port 26 on the exhaust port 24 side. This makes it difficult for fuel gas to flow from the fuel supply port 26 to the exhaust port 24 side, thereby preventing a portion of the fuel gas supplied from the fuel supply port 26 to the combustion chamber 20 from being discharged from the exhaust port 24 without being burned. Furthermore, compared to the configurations shown in FIGS. 9A to 9C , the weight of the fuel supply valve 15 is reduced, thereby improving the responsiveness of the fuel supply valve 15 and facilitating the manufacture and quality control of the fuel supply valve 15. Furthermore, because it is difficult for fuel gas to be supplied to the exhaust port 24 side regardless of the lift amount of the fuel supply valve 15, the fuel distribution in the cylinder 4 becomes such that the fuel concentration is high on the intake side and low on the exhaust side. As a result, the intake side burns before the exhaust side, which helps to suppress knocking (if the fuel concentration were uniform, the exhaust side, which has a higher temperature, would burn first, and the intake side would take longer to burn, causing the end gas remaining on the low-temperature wall of the intake side to self-ignite and result in knocking). Also, the number of parts can be reduced compared to the configuration shown in Figure 11.

[0066] 14A, the protrusion 77 of the valve seat member 56 may be provided in a range S1 on the exhaust port 24 side in the circumferential direction around the axis C of the fuel supply valve 15. In the example shown in Fig. 14A, the side on which the two intake ports 22 are arranged with respect to a plane K including the axis C of the fuel supply valve 15 is defined as the intake port 22 side, and the side on which the two exhaust ports 24 are arranged is defined as the exhaust port 24 side.

[0067] 14B , for example, the protrusion 77 of the valve seat member 56 may be provided in a range of 180° or more, including a range S1 on the exhaust port 24 side, in the circumferential direction about the axis of the fuel supply valve 15. In the example shown in FIG. 14B , the protrusion 77 of the valve seat member 56 is provided in a range S1 on the exhaust port 24 side and a range S2 adjacent to the upstream side of the range S1 in the swirling direction of the swirling flow of the intake air that has flowed into the combustion chamber from the intake port, in the circumferential direction about the axis of the fuel supply valve 15. More specifically, when the product of the strength S of the swirling flow and the angular width OL is defined as an angle θ, the protrusion 77 of the valve seat member 56 may be configured in a range that includes the range S1 on the exhaust port 24 side and a range S2 that is an angle θ from the upstream end of the range S1 in the rotational direction of the swirling flow to the upstream side in the rotational direction of the swirling flow. This makes it possible to effectively prevent fuel gas from passing through from the fuel supply port 26 to the exhaust port 24 while the exhaust valve is open, taking into consideration the strength S of the swirl flow of the intake air that has flowed into the combustion chamber 20.

[0068] The present disclosure is not limited to the above-described embodiments, but also includes modifications to the above-described embodiments and appropriate combinations of these modifications.

[0069] The contents described in each of the above embodiments can be understood, for example, as follows.

[0070] (1) A hydrogen engine according to at least one embodiment of the present disclosure includes: A hydrogen engine (such as the hydrogen engine 2 described above) that uses a fuel gas containing hydrogen, a cylinder (e.g., cylinder 4 above); a piston (for example, the above-mentioned piston 6) movable within the cylinder; a cylinder head (e.g., the cylinder head 8 described above) that forms a combustion chamber (e.g., the combustion chamber 20 described above) between the piston and the cylinder head, and that includes an intake port (e.g., the intake port 22 described above) connected to the combustion chamber and a fuel supply port (e.g., the fuel supply port 26 described above) connected to the combustion chamber; an intake valve (e.g., the intake valve 10 described above) for opening and closing the intake port; a fuel supply valve (for example, the above-mentioned fuel supply valve 15) for opening and closing the fuel supply port; a valve mechanism (for example, the above-described valve mechanism 18) that is provided in common with the intake valve and the fuel supply valve and that is configured to open and close the intake valve and the fuel supply valve in conjunction with each other; Equipped with The valve opening timing of the fuel supply valve (for example, the above-mentioned valve opening timing FO) is configured to be more retarded than the valve opening timing of the intake valve (for example, the above-mentioned valve opening timing IO).

[0071] According to the hydrogen engine described in (1) above, a fuel supply port is provided separately from the intake port, and fuel gas is supplied to the combustion chamber from the fuel supply port without passing through the intake port. This makes it possible to suppress backfire, in which a flame travels back to the intake port. Furthermore, because the opening timing of the fuel supply valve is retarded relative to the opening timing of the intake valve, even if there is a period when the opening periods of the intake valve and the exhaust valve overlap, it is possible to suppress the occurrence of a portion of the fuel gas supplied from the fuel supply port to the combustion chamber being discharged from the exhaust port without being burned. This suppresses a decrease in engine efficiency and realizes a highly efficient hydrogen engine. Therefore, it is possible to suppress the occurrence of backfire and achieve high engine efficiency.

[0072] (2) In some embodiments, in the hydrogen engine described in (1) above, The valve mechanism includes: an intake rocker arm (for example, the intake rocker arm 44) configured to rotate around a predetermined rotation axis (for example, the above-mentioned rotation axis C2) and to be able to press the intake valve; a fuel supply valve arm (for example, the above-described fuel supply valve arm 48) configured to rotate about the rotation axis together with the intake rocker arm and to be able to press the fuel supply valve; Equipped with The maximum value of the distance between the fuel supply valve arm and the fuel supply valve in one combustion cycle of the engine (for example, the above-mentioned maximum value g1max) is greater than the maximum value of the distance between the intake rocker arm and the intake valve in one combustion cycle of the engine (for example, the above-mentioned maximum value g2max).

[0073] According to the hydrogen engine described in (2) above, by making the maximum distance between the fuel supply valve arm and the fuel supply valve in one combustion cycle of the engine greater than the maximum distance between the intake rocker arm and the intake valve in one combustion cycle of the engine, the opening timing of the fuel supply valve can be retarded relative to the opening timing of the intake valve, thereby achieving the effect described in (1) above with a simple configuration.

[0074] (3) In some embodiments, in the hydrogen engine described in (2) above, The distance (for example, the above-mentioned distance g1) between the fuel supply valve arm and the fuel supply valve at the exhaust valve closing timing (for example, the above-mentioned valve closing timing EC) of the engine is greater than zero.

[0075] According to the hydrogen engine described in (3) above, by making the distance between the fuel supply valve arm and the fuel supply valve greater than 0 when the exhaust valve of the engine is closed, the opening timing of the fuel supply valve can be retarded relative to the closing timing of the exhaust valve. This effectively prevents a portion of the fuel gas supplied from the fuel supply port to the combustion chamber from being discharged from the exhaust port without being burned.

[0076] (4) In some embodiments, in the hydrogen engine described in any one of (1) to (3) above, The fuel supply valve is a valve stem (e.g., valve stem 34 described above); a valve body portion (for example, the above-described valve body portion 36) provided on one end side of the valve stem and capable of abutting against a valve seat surface of the fuel supply port in the axial direction of the valve stem; a collar portion (for example, the above-described collar portion 50) that is provided on the valve stem on the valve body portion side and that is located upstream of the valve seat surface in the flow of the fuel gas in the axial direction of the fuel supply valve when the valve body portion is in contact with the valve seat surface of the fuel supply port; Equipped with.

[0077] According to the hydrogen engine described in (4) above, by providing the collar portion on the fuel supply valve, the opening timing of the fuel supply valve can be retarded relative to the opening timing of the intake valve, thereby achieving the effect described in (1) above with a simple configuration.

[0078] (5) In some embodiments, in the hydrogen engine described in (4) above, When the lift amount of the fuel supply valve at the timing of closing the exhaust valve of the engine is L and the height of the collar portion is H1, the relationship H1>0.7L is satisfied.

[0079] According to the hydrogen engine described in (5) above, by providing the fuel supply valve with a collar that satisfies H1 > 0.7 L, the opening timing of the fuel supply valve can be retarded relative to the closing timing of the exhaust valve, which effectively prevents a portion of the fuel gas supplied from the fuel supply port to the combustion chamber from being discharged from the exhaust port without being burned.

[0080] (6) In some embodiments, in the hydrogen engine described in any one of (1) to (5) above, The fuel supply port is a first flow path portion (for example, the above-mentioned first flow path portion 60) provided along the axial direction of the fuel supply valve; a valve seat surface (for example, the above-mentioned valve seat surface 54) provided downstream of the first flow path portion; a second flow path portion (for example, the above-described second flow path portion 62) provided downstream of the valve seat surface and having a flow path width larger than the flow path width of the first flow path portion; Including, The outer peripheral surface of the valve body of the fuel supply valve is configured to slide on the flow path wall of the second flow path portion (for example, the above-mentioned flow path wall 64).

[0081] According to the hydrogen engine described in (6) above, even if the valve body of the fuel supply valve separates from the valve seat surface, the fuel supply port can be kept closed while the outer circumferential surface of the valve body slides on the flow path wall of the second flow path portion. This allows the opening timing of the fuel supply valve to be retarded relative to the opening timing of the intake valve. Therefore, the effect described in (1) can be achieved with a simple configuration. Furthermore, the fuel supply valve can be made lighter than the configuration described in (4), thereby improving the responsiveness of the fuel supply valve.

[0082] (7) In some embodiments, in the hydrogen engine described in (6) above, When the lift amount of the fuel supply valve at the closing timing of the exhaust valve of the engine is L and the length of the second flow path portion in the axial direction of the fuel supply valve is H2, the relationship H2>0.7L is satisfied.

[0083] In the hydrogen engine described in (7) above, by satisfying the condition H2 > 0.7 L, the opening timing of the fuel supply valve can be retarded relative to the closing timing of the exhaust valve, which effectively prevents a portion of the fuel gas supplied from the fuel supply port to the combustion chamber from being discharged from the exhaust port without being burned.

[0084] (8) A hydrogen engine according to at least one embodiment of the present disclosure includes: A hydrogen engine (such as the hydrogen engine 2 described above) that uses a fuel gas containing hydrogen, a cylinder (e.g., cylinder 4 above); a piston (for example, the above-mentioned piston 6) movable within the cylinder; a cylinder head that forms a combustion chamber (e.g., the above-mentioned combustion chamber 20) between itself and the piston, and that includes an intake port (e.g., the above-mentioned intake port 22) connected to the combustion chamber, a fuel supply port (e.g., the above-mentioned fuel supply port 26) connected to the combustion chamber, and an exhaust port (e.g., the above-mentioned exhaust port 24) connected to the combustion chamber; an intake valve (e.g., the intake valve 10 described above) for opening and closing the intake port; a fuel supply valve (for example, the above-mentioned fuel supply valve 15) for opening and closing the fuel supply port; a valve mechanism (for example, the above-described valve mechanism 18) that is provided in common with the intake valve and the fuel supply valve and that is configured to open and close the intake valve and the fuel supply valve in conjunction with each other; a cover portion (for example, the above-described collar portion 72, protrusion 76, or protrusion 77) configured to cover at least a portion of the outlet portion of the fuel supply port on the exhaust port side during at least a portion of an opening period of the fuel supply valve; Equipped with.

[0085] According to the hydrogen engine described in (8) above, since at least a portion of the outlet of the fuel supply port on the exhaust port side is covered by the cover during at least a portion of the period when the fuel supply valve is open, fuel gas is less likely to flow from the fuel supply valve to the exhaust port side, which makes it possible to prevent a portion of the fuel gas supplied from the fuel supply port to the combustion chamber from being discharged from the exhaust port without being burned.

[0086] (9) In some embodiments, in the hydrogen engine described in (8), the cover portion is a collar portion (for example, the above-described collar portion 72) provided on the valve body portion side of the valve stem of the fuel supply valve, The collar portion is formed in a circular or cylindrical shape, and when the valve body portion of the fuel supply valve abuts against the valve seat surface of the fuel supply port, the collar portion is located upstream of the valve seat surface in the axial direction of the fuel supply valve in the flow of the fuel gas, and has an outer diameter larger than the outer diameter of the valve rod.

[0087] According to the hydrogen engine described in (9) above, the flow of fuel gas from the fuel supply port to the exhaust port can be restricted by the collar, so that the effect described in (8) above can be obtained with a simple configuration.

[0088] (10) In some embodiments, in the hydrogen engine described in (8) above, The cylinder head a cylinder head body (e.g., the cylinder head body 52 described above); a valve seat member (for example, the above-mentioned valve seat member 56) that forms a valve seat surface of the fuel supply port and is configured as a separate body from the cylinder head body; a mask plate (for example, the above-mentioned mask plate 74) sandwiched between the cylinder head body and the valve seat member; Including, the mask plate includes a protrusion (e.g., the protrusion 76 described above) that protrudes from a flow path wall of the fuel supply port toward the valve stem of the fuel supply valve, The cover portion is the protrusion portion.

[0089] According to the hydrogen engine described in (10) above, the flow of fuel gas from the fuel supply port to the exhaust port can be suppressed by the protrusion of the mask plate. This allows the effect described in (8) above to be achieved with a simple configuration. Furthermore, compared to the configuration described in (9) above, the weight of the fuel supply valve is reduced, improving the responsiveness of the fuel supply valve and facilitating manufacturing and quality control of the fuel supply valve. Furthermore, because fuel gas is less likely to be supplied to the exhaust port regardless of the lift amount of the fuel supply valve, the fuel distribution in the cylinder becomes such that the fuel concentration is high on the intake side and low on the exhaust side. Therefore, the intake side burns before the exhaust side, thereby suppressing knocking. (If the fuel concentration were uniform, the high-temperature exhaust side would burn first, while the intake side would burn slowly, resulting in the end gas remaining on the low-temperature wall of the intake side eventually self-igniting, causing knocking.)

[0090] (11) In some embodiments, in the hydrogen engine described in (8), The cylinder head a cylinder head body (e.g., the cylinder head body 52 described above); a valve seat member (for example, the above-mentioned valve seat member 56) that forms a valve seat surface of the fuel supply port and is configured as a separate body from the cylinder head body; Including, the valve seat member includes a protrusion (for example, the protrusion 77 described above) that protrudes from a flow path wall of the fuel supply port toward the valve stem of the fuel supply valve, The cover portion is the protrusion portion.

[0091] According to the hydrogen engine described in (11) above, the flow of fuel gas from the fuel supply port to the exhaust port can be suppressed by the protruding portion of the valve seat member. Therefore, the effect described in (8) above can be achieved with a simple configuration. Furthermore, compared to the configuration described in (9) above, the weight of the fuel supply valve can be reduced, improving the responsiveness of the fuel supply valve and facilitating manufacturing and quality control of the fuel supply valve. Furthermore, because fuel gas is less likely to be supplied to the exhaust port regardless of the lift amount of the fuel supply valve, the fuel distribution in the cylinder becomes such that the fuel concentration is high on the intake side and low on the exhaust side. Therefore, the intake side burns before the exhaust side, thereby suppressing knocking. (If the fuel concentration were uniform, the high-temperature exhaust side would burn first, while the intake side would burn slowly, resulting in the end gas remaining on the low-temperature wall of the intake side eventually autoigniting, causing knocking.) Furthermore, compared to the configuration described in (10) above, the number of parts can be reduced.

[0092] (12) In some embodiments, in the hydrogen engine described in any one of (8) to (11), a strength S of the swirl flow is a dimensionless number indicating how many times the swirl flow of the intake air that has flowed into the combustion chamber from the intake port circulates around the combustion chamber during one rotation of the engine; an angle width OL is a width of the crank angle corresponding to a period during which an opening period of the exhaust valve of the engine and an opening period of the fuel supply valve overlap during one combustion cycle of the engine; and an angle θ is a product of the strength S of the swirl flow and the angle width OL. In the circumferential direction around the axis of the fuel supply valve, if a range on the exhaust port side is defined as S1, and a range of the angle θ from the upstream end of the range S1 in the rotation direction of the swirling flow to the upstream side in the rotation direction of the swirling flow is defined as S2, then: The cover portion is provided in a range including the range S1 and the range S2 in the circumferential direction.

[0093] According to the hydrogen engine described in (12) above, by taking into consideration the strength S of the swirl flow of the intake air flowing into the combustion chamber, it is possible to effectively prevent fuel gas from passing through from the fuel supply port to the exhaust port while the exhaust valve is open.

[0094] (13) A hydrogen engine according to at least one embodiment of the present disclosure includes: A hydrogen engine (such as the hydrogen engine 2 described above) that uses a fuel gas containing hydrogen, a cylinder (e.g., cylinder 4 above); a piston (for example, the above-mentioned piston 6) movable within the cylinder; a cylinder head (e.g., the above-mentioned cylinder head 8) that forms a combustion chamber (e.g., the above-mentioned combustion chamber 20) between itself and the piston, and that includes an intake port (e.g., the above-mentioned intake port 22) that connects to the combustion chamber, a fuel supply port (e.g., the above-mentioned fuel supply port 26) that connects to the combustion chamber, and an exhaust port (e.g., the above-mentioned exhaust port 24) that connects to the combustion chamber; an intake valve (e.g., the intake valve 10 described above) for opening and closing the intake port; a fuel supply valve (for example, the above-mentioned fuel supply valve 15) for opening and closing the fuel supply port; a valve mechanism (for example, the above-described valve mechanism 18) that is provided in common with the intake valve and the fuel supply valve and that is configured to open and close the intake valve and the fuel supply valve in conjunction with each other; Equipped with The lower surface of the cylinder head is formed along a plane, When the fuel supply valve is in contact with a valve seat surface provided in the fuel supply port, the lower surface of the fuel supply valve (e.g., the above-mentioned lower surface 66) is located upstream of the flow of the fuel gas in the axial direction of the fuel supply valve relative to the lower surface of the cylinder head (e.g., the above-mentioned lower surface 9).

[0095] According to the hydrogen engine described in (13) above, when the fuel supply valve is in contact with the valve seat provided in the fuel supply port, the lower surface of the fuel supply valve is located upstream of the lower surface of the cylinder head in the fuel gas flow direction. This allows for a longer time from when the fuel supply valve opens until the fuel gas reaches the exhaust valve, compared to when the lower surface of the fuel supply valve is located downstream of the lower surface of the cylinder head in the fuel gas flow direction. Therefore, even if there is a period when the intake valve and the exhaust valve are open overlap, it is possible to prevent a portion of the fuel gas supplied from the fuel supply port to the combustion chamber from being discharged from the exhaust port without being burned. This prevents a decrease in engine efficiency, resulting in a highly efficient hydrogen engine.

[0096] (14) In some embodiments, in the hydrogen engine described in (13) above, When the lift amount of the fuel supply valve at the closing timing of the exhaust valve of the engine is L, and the distance between the lower surface of the fuel supply valve and the lower surface of the cylinder head in the axial direction of the fuel supply valve when the fuel supply valve is in contact with a valve seat surface provided in the fuel supply port is H3, H3>L is satisfied.

[0097] In the hydrogen engine described in (14) above, by satisfying H3>L, the opening timing of the fuel supply valve can be retarded relative to the closing timing of the exhaust valve, which effectively prevents a portion of the fuel gas supplied from the fuel supply port to the combustion chamber from being discharged from the exhaust port without being burned. [Explanation of symbols]

[0098] 2 Hydrogen engine 4 cylinders 6 pistons 8. Cylinder head 9 Bottom side 10 Intake valve 12,16 Valve springs 14 Exhaust valve 15 Fuel supply valve 18 Valve train 20 Combustion chamber 22 Intake port 24 exhaust port 26 Fuel supply port 28,34 Valve stem 30,36 Valve body 32,38 Force receiving part 40 Intake camshaft 41 Intake cam 42 Push rod 44 Intake rocker arm 44a One end 44b Other end 46 Rocker arm shaft 48 Fuel supply valve arm 48a Tip 50,72 Color section 52 Cylinder head body 53 Inclined surface (outer surface) 54 Valve seat surface 56 Valve seat member 60 First flow path section 62 Second flow path section 63 Open End 64,75 Channel wall 65 steps 66 Bottom side 70 Exit section 74 Mask Plate 76,77 Protrusion

Claims

1. A hydrogen engine that uses a fuel gas containing hydrogen, A cylinder; a piston movable within the cylinder; a cylinder head that defines a combustion chamber between itself and the piston, the cylinder head including an intake port connected to the combustion chamber and a fuel supply port connected to the combustion chamber; an intake valve for opening and closing the intake port; a fuel supply valve for opening and closing the fuel supply port; a valve mechanism that is provided in common to the intake valve and the fuel supply valve and that is configured to open and close the intake valve and the fuel supply valve in conjunction with each other; Equipped with The opening timing of the fuel supply valve is configured to be retarded relative to the opening timing of the intake valve, The valve mechanism includes: an intake rocker arm configured to rotate about a predetermined rotation axis and to be able to press the intake valve; a fuel supply valve arm configured to rotate about the rotation axis together with the intake rocker arm and to be able to press the fuel supply valve; Equipped with a maximum value of the distance between the fuel supply valve arm and the fuel supply valve in one combustion cycle of the hydrogen engine is greater than a maximum value of the distance between the intake rocker arm and the intake valve in one combustion cycle of the hydrogen engine; Hydrogen engine.

2. 2. The hydrogen engine according to claim 1, wherein a distance between the fuel supply valve arm and the fuel supply valve at a timing when an exhaust valve of the hydrogen engine is closed is greater than zero.

3. A hydrogen engine that uses a fuel gas containing hydrogen, A cylinder; a piston movable within the cylinder; a cylinder head that defines a combustion chamber between itself and the piston, the cylinder head including an intake port connected to the combustion chamber and a fuel supply port connected to the combustion chamber; an intake valve for opening and closing the intake port; a fuel supply valve for opening and closing the fuel supply port; a valve mechanism that is provided in common to the intake valve and the fuel supply valve and that is configured to open and close the intake valve and the fuel supply valve in conjunction with each other; Equipped with The opening timing of the fuel supply valve is configured to be retarded relative to the opening timing of the intake valve, The fuel supply valve is A valve stem; a valve body portion provided on one end side of the valve stem and capable of abutting against a valve seat surface of the fuel supply port in the axial direction of the valve stem; a collar portion provided on the valve stem on the valve body portion side, the collar portion being located upstream of the valve seat surface in the axial direction of the fuel supply valve in a state in which the valve body portion abuts against a valve seat surface of the fuel supply port; Equipped with a hydrogen engine.

4. 4. The hydrogen engine according to claim 3, wherein, when the lift amount of the fuel supply valve at the closing timing of the exhaust valve of the hydrogen engine is L and the height of the collar portion is H1, H1 > 0.7L is satisfied.

5. A hydrogen engine that uses a fuel gas containing hydrogen, A cylinder; a piston movable within the cylinder; a cylinder head that defines a combustion chamber between itself and the piston, the cylinder head including an intake port connected to the combustion chamber and a fuel supply port connected to the combustion chamber; an intake valve for opening and closing the intake port; a fuel supply valve for opening and closing the fuel supply port; a valve mechanism that is provided in common to the intake valve and the fuel supply valve and that is configured to open and close the intake valve and the fuel supply valve in conjunction with each other; Equipped with The opening timing of the fuel supply valve is configured to be retarded relative to the opening timing of the intake valve, The fuel supply port is a first flow path portion provided along the axial direction of the fuel supply valve; a valve seat surface provided downstream of the first flow path portion; a second flow path portion provided downstream of the valve seat surface and having a flow path width greater than a flow path width of the first flow path portion; Including, a valve body portion of the fuel supply valve configured so that an outer peripheral surface thereof slides on a flow path wall of the second flow path portion;

6. 6. The hydrogen engine according to claim 5, wherein H2>0.7L is satisfied, where L is a lift amount of the fuel supply valve at a closing timing of an exhaust valve of the hydrogen engine, and H2 is a length of the second flow path portion in the axial direction of the fuel supply valve.

7. When the side on which the intake port is arranged is defined as the intake port side and the side on which the exhaust port of the cylinder head is arranged is defined as the exhaust port side with respect to a plane including the axis of the fuel supply valve, a cover portion configured to cover at least a portion of an outlet portion of the fuel supply port on the exhaust port side during at least a portion of an opening period of the fuel supply valve; 6. A hydrogen engine according to claim 1, 3 or 5, comprising:

8. the cover portion is a collar portion provided on a valve body portion side of a valve stem of the fuel supply valve, 8. The hydrogen engine according to claim 7, wherein the collar portion is formed in a disk or a columnar shape, and is located upstream of the valve seat surface in the axial direction of the fuel supply valve in a state where the valve body portion of the fuel supply valve abuts against the valve seat surface of the fuel supply port, and has an outer diameter larger than an outer diameter of the valve stem.

9. The cylinder head A cylinder head body, a valve seat member that forms a valve seat surface of the fuel supply port and is configured separately from the cylinder head body; a mask plate sandwiched between the cylinder head body and the valve seat member; Including, the mask plate includes a protrusion that protrudes from a flow path wall of the fuel supply port toward a valve stem of the fuel supply valve, 8. The hydrogen engine according to claim 7, wherein the cover portion is the protrusion.

10. The cylinder head A cylinder head body, a valve seat member that forms a valve seat surface of the fuel supply port and is configured separately from the cylinder head body; Including, the valve seat member includes a protrusion that protrudes from a flow path wall of the fuel supply port toward a valve stem of the fuel supply valve, 8. The hydrogen engine according to claim 7, wherein the cover portion is the protrusion.

11. a strength S of the swirl flow is a dimensionless number indicating how many times the swirl flow of intake air flowing from the intake port into the combustion chamber circulates around the combustion chamber during one rotation of the hydrogen engine; an angular width OL is a width of the crank angle corresponding to a period during which an opening period of the exhaust valve of the hydrogen engine and an opening period of the fuel supply valve overlap within one combustion cycle of the hydrogen engine; and an angle θ is a product of the strength S of the swirl flow and the angular width OL. In the circumferential direction around the axis of the fuel supply valve, if a range on the exhaust port side is defined as S1, and a range of the angle θ from an upstream end of the range S1 in the rotation direction of the swirling flow to the upstream side in the rotation direction of the swirling flow is defined as S2, then:

8. The hydrogen engine according to claim 7, wherein the cover portion is provided in a range including the range S1 and the range S2 in the circumferential direction.

12. The lower surface of the cylinder head is formed along a plane, 6. A hydrogen engine according to claim 1, wherein a lower surface of the fuel supply valve is located upstream of a lower surface of the cylinder head in an axial direction of the fuel supply valve in a state where the fuel supply valve is in contact with a valve seat surface provided in the fuel supply port.

13. 13. The hydrogen engine according to claim 12, wherein H3>L is satisfied, where L is a lift amount of the fuel supply valve at a closing timing of an exhaust valve of the hydrogen engine, and H3 is a distance in the axial direction of the fuel supply valve between a bottom surface of the fuel supply valve and a bottom surface of the cylinder head when the fuel supply valve is in contact with a valve seat surface provided in the fuel supply port.

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