Internal combustion engine

Abstract

An intake valve of an internal combustion engine has a shaft portion and a petal portion. An upper surface of the petal portion includes a guide portion. The guide portion has a specific tangent line that intersects with one or more selected from a portion of a spark plug located inside a cylinder and a portion of an exhaust valve in a closed state, which are located inside the cylinder, when the intake valve is in a fully open state. An angle formed by a line segment that coincides with the tangent line of the guide portion and extends from a tangent point of the tangent line with respect to the guide portion to an intersection point of the tangent line with respect to a central axis of the petal portion, and a line segment that coincides with the central axis and extends from the intersection point toward an intake passage, on an imaginary cross section parallel to the central axis of the petal portion and passing through the guide portion, is a specific angle. A tangent line that makes the specific angle the smallest is the specific tangent line.

Description

Technical Field

[0001] This disclosure relates to internal combustion engines. Background Technology

[0002] The internal combustion engine described in Japanese Patent Application Publication No. 2021-95899 includes a cylinder, an intake passage, and a water injection valve. Combustion of the air-fuel mixture occurs in the cylinder. The intake passage is connected to the cylinder. The water injection valve is located within the intake passage. The water injection valve injects water towards the cylinder. Summary of the Invention

[0003] The problem that the invention aims to solve

[0004] The internal combustion engine described in the aforementioned announcement has an exhaust passage for discharging exhaust gases and includes an exhaust valve and a spark plug. The exhaust valve opens and closes at the end of the exhaust passage connected to the cylinder. The spark plug ignites the air-fuel mixture through a spark discharge.

[0005] In the internal combustion engine described in the aforementioned bulletin, water injected from the water injection valve does not easily adhere to the spark plugs and exhaust valves. Consequently, it is impossible to efficiently cool the spark plugs and exhaust valves.

[0006] Methods for solving problems

[0007] One aspect of this disclosure relates to an internal combustion engine comprising: a cylinder having an intake opening and an exhaust opening; a spark plug having a top end located within the cylinder; an intake passage connected to the intake opening of the cylinder; an exhaust passage connected to the exhaust opening of the cylinder; a water injection valve located within the intake passage and configured to inject water into the intake passage; an intake valve configured to selectively open and close the intake opening; and an exhaust valve configured to selectively open and close the exhaust opening. The intake valve has a rod-shaped shaft portion and an umbrella portion connected to the top end of the shaft portion and located within the cylinder. The outer surface of the umbrella portion has an upper surface facing the intake opening. The upper surface includes a curved guide portion. The guide portion has a specific tangent line that, when the intake valve is fully open, intersects at least one selected from the portion of the spark plug located within the cylinder and the portion of the exhaust valve located within the cylinder when the valve is closed. On an imaginary cross-section parallel to the central axis of the umbrella section and passing through the guide section, the angle formed by a line segment that coincides with the tangent to the guide section and extends from the point of tangency of the tangent relative to the guide section to the point of intersection of the tangent relative to the central axis, and a line segment that coincides with the central axis and extends from the intersection point toward the air intake passage, is a specific angle. The tangent that minimizes this specific angle is the specific tangent. Attached Figure Description

[0008] Figure 1 This is a schematic diagram of the internal combustion engine.

[0009] Figure 2 It is shown Figure 1 A partial sectional view of the cylinder and surrounding parts of an internal combustion engine.

[0010] Figure 3 It is Figure 2 Enlarged partial sectional view.

[0011] Figure 4 This is a partial sectional view showing the cylinder and surrounding parts of an internal combustion engine in a modified example. Detailed Implementation

[0012] Hereinafter, one embodiment of the internal combustion engine will be described with reference to the accompanying drawings.

[0013] <About Internal Combustion Engines>

[0014] like Figure 1 As shown, the internal combustion engine 10 has four cylinders 11 (only one is shown in the figure), an intake passage 12, and an exhaust passage 13.

[0015] Cylinder 11 is a space for combustion of the fuel-air mixture. Cylinder 11 is generally cylindrical. Cylinder 11 has four openings. When viewed along the axis of cylinder 11, the four openings are arranged in two rows and two columns. The four openings include two intake openings and two exhaust openings.

[0016] The intake passage 12 is the passage for air intake. The downstream portion of the intake passage 12 branches into eight passages. Two of the eight branch passages are connected to each cylinder 11. The two branch passages are connected to the two intake openings of each cylinder 11.

[0017] Exhaust passage 13 is the passage for exhaust flow. The upstream portion of exhaust passage 13 branches into 8 passages. Two of the 8 branched passages are connected to each cylinder 11. The two branched passages are connected to the two exhaust ports of each cylinder 11.

[0018] The internal combustion engine 10 has eight intake valves 14 and eight exhaust valves 15. Figure 1 The diagram shows two intake valves 14 and two exhaust valves 15 positioned relative to one cylinder 11.

[0019] The intake valve 14 is located at the connection between the intake passage 12 and the cylinder 11. The intake valve 14 can open and close the intake opening of the cylinder 11.

[0020] like Figure 2 and Figure 3As shown, the intake valve 14 has a shaft portion 21 and a canopy portion 22. The shaft portion 21 is rod-shaped. The canopy portion 22 is located at the top of the shaft portion 21 and is situated inside the cylinder 11. When viewed along the central axis C1 of the shaft portion 21, the canopy portion 22 is circular. The central axis of the canopy portion 22 coincides with the central axis C1 of the shaft portion 21. The specific shape of the canopy portion 22 will be described later.

[0021] Shaft 21 is connected to a valve mechanism (not shown). Power from the valve mechanism enables the intake valve 14 to move in the direction along the central axis C1 of shaft 21. According to this movement, the umbrella portion 22 of the intake valve 14 opens and closes the intake passage 12 within the cylinder 11.

[0022] The intake valve 14 can move between a closed position where the umbrella 22 is closest to the intake opening and a fully open position where the umbrella 22 is furthest from the intake opening. If the intake valve 14 moves to the closed position, the umbrella 22 closes the intake opening. The state in which the umbrella 22 closes the intake opening is called the closed state of the intake valve 14.

[0023] If the intake valve 14 is moved to the fully open position, the umbrella 22 will open the intake opening to its maximum extent. The state in which the umbrella 22 opens the intake opening to its maximum extent is called the fully open state of the intake valve 14.

[0024] The exhaust valve 15 is located at the connection between the exhaust passage 13 and the cylinder 11. The exhaust valve 15 can open and close the exhaust opening of the cylinder 11.

[0025] The exhaust valve 15 has a shaft portion 31 and a canopy portion 32. The shaft portion 31 is rod-shaped. The canopy portion 32 is located at the top of the shaft portion 31 and is situated inside the cylinder 11. When viewed from a direction along the central axis C2 of the shaft portion 31, the canopy portion 32 is circular.

[0026] The shaft 31 is connected to a valve mechanism (not shown). Power from the valve mechanism enables the exhaust valve 15 to move in the direction along the central axis C2 of the shaft 31. According to this movement, the umbrella portion 32 of the exhaust valve 15 opens and closes the exhaust passage 13 within the cylinder 11.

[0027] The exhaust valve 15 can move between the closed position of the umbrella 32 closest to the exhaust opening and the fully open position of the umbrella 32 furthest from the exhaust opening. If the exhaust valve 15 moves to the closed position, the umbrella 32 closes the exhaust opening. The state in which the umbrella 32 closes the exhaust opening is called the closed state of the exhaust valve 15.

[0028] If the exhaust valve 15 is moved to the fully open position, the umbrella part 32 will open the exhaust opening to its maximum extent. The state in which the umbrella part 32 opens the exhaust opening to its maximum extent is called the fully open state of the exhaust valve 15.

[0029] like Figure 1As shown, the internal combustion engine 10 has four spark plugs 16. Figure 1 The diagram shows a spark plug 16 positioned relative to one cylinder 11. Additionally, in... Figure 1 The diagram only shows a portion of the spark plug 16, including its tip. The spark plug 16 is located in the area surrounded by the four openings of the cylinder 11. Most of the spark plug 16 is embedded inside the internal combustion engine 10. The tip of the spark plug 16 is located inside the cylinder 11. The spark plug 16 ignites the air-fuel mixture within the cylinder 11.

[0030] like Figure 2 As shown, the internal combustion engine 10 has four water injection valves 17. Figure 2 The diagram shows a water injection valve 17 positioned relative to a cylinder 11. Additionally, in... Figure 2 In the diagram, water jet valve 17 is schematically shown near the downstream end of air intake passage 12. Water jet valve 17 is connected to a water tank (not shown). Water jet valve 17 receives water supply from the water tank.

[0031] Water injection valve 17 is located within intake passage 12. Water injection valve 17 injects water into intake passage 12. The water injected from each water injection valve 17 flows into the corresponding cylinder 11 along with the intake air. In addition, the water injected from each water injection valve 17 flows into two branch passages that are respectively connected to the two intake openings of the corresponding cylinder 11.

[0032] <Regarding the shape of the intake valve umbrella>

[0033] The following explanation concerns the intake valve 14. It should be noted that the following explanation uses one cylinder 11 as an example. Furthermore, the explanation will use one of the two intake valves 14 corresponding to one cylinder 11 as an example.

[0034] like Figure 2 As shown, the outer surface of the umbrella portion 22 of the intake valve 14 has an upper surface 22A facing the intake opening. The upper surface 22A includes a guide portion (guide surface) 23.

[0035] Figure 2 A cross-section of the internal combustion engine 10 is shown along the plane including the central axis C1 of the shaft portion 21 of the intake valve 14 and the central axis C2 of the shaft portion 31 of the exhaust valve 15. This cross-section is referred to as a hypothetical cross-section. In this hypothetical cross-section, the guide portion 23 is a portion whose upper surface 22A is concave and curved. In addition, in the hypothetical cross-section, the guide portion 23 is a concave arc shape.

[0036] like Figure 1 As shown, the guide portion 23 is arranged in a circular shape around the central axis C1 when viewed from the direction along the central axis C1 of the shaft portion 21. Figure 2As shown, the width of the guide portion 23 in the radial direction orthogonal to the central axis C1, i.e., the umbrella portion 22, is L2. The width L2 of the guide portion 23 is constant throughout the entire 360 ​​degrees around the central axis C1. Therefore, the maximum width of the guide portion 23 in the direction orthogonal to the central axis C1 is the same as the width L2.

[0037] like Figure 3 As shown, the outer surface of the guide portion 23 is continuous with that of the shaft portion 21. In this embodiment, the outer surface of the shaft portion 21 is a straight line in an imaginary cross-section. In the imaginary cross-section, the intersection of the straight line defining the outer surface of the shaft portion 21 and the arc defining the guide portion 23 is the boundary between the shaft portion 21 and the guide portion 23. Furthermore, as described above, the guide portion 23 is annular. Therefore, in the imaginary cross-section, in a direction orthogonal to the central axis C1, the guide portion 23 is located on both sides of the shaft portion 21.

[0038] like Figure 2 As shown, the outer diameter of the umbrella portion 22 in the direction orthogonal to the central axis C1 is L1. The width L2 of the guide portion 23 is, for example, more than 1 / 4 of the outer diameter L1 of the umbrella portion 22. In this embodiment, the width L2 of the guide portion 23 is approximately 1 / 4 of the outer diameter L1 of the umbrella portion 22. As described above, in the imaginary cross-section, the guide portions 23 are located on both sides of the shaft portion 21 in the direction orthogonal to the central axis C1. Therefore, in the imaginary cross-section, the total width of the guide portions 23 located on both sides of the shaft portion 21 occupies approximately 1 / 2 of the outer diameter L1 of the umbrella portion 22.

[0039] like Figure 3 As shown, the guide section 23 has a specific tangent ST. The specific tangent ST will be explained below. In an imaginary cross-section, the angle formed by the tangent tangent to the guide section 23 and the central axis C1 is called the specific angle SA. Specifically, the specific angle SA is the angle formed by a line segment in the imaginary cross-section that coincides with the tangent tangent to the guide section 23 and extends from the point of tangency P1 of the tangent relative to the guide section 23 to the point of intersection P2 of the tangent relative to the central axis C1, and a line segment that coincides with the central axis C1 and extends from the intersection P2 toward the intake passage 12. The specific tangent ST is the tangent tangent to the guide section 23 and is the tangent that minimizes the specific angle SA. The specific angle SA defined by the specific tangent ST is, for example, smaller than 90 degrees.

[0040] In this embodiment, the tangent point P1 of the specific tangent line ST relative to the guide portion 23 is located at the radially outer end of the guide portion 23 in an imaginary cross-section. When the intake valve 14 is fully open, the specific tangent line ST intersects the portion of the exhaust valve 15 located inside the cylinder 11 in the closed state. Specifically, the specific tangent line ST intersects the umbrella portion 32 of the closed exhaust valve 15 (more specifically, the surface of the umbrella portion 32 facing into the cylinder 11). The specific tangent line ST intersects the umbrella portion 32 of the exhaust valve 15 on the side where the intake valve 14 is located relative to the shaft portion 31 of the exhaust valve 15.

[0041] Furthermore, not only when the intake valve 14 is fully open, but also when the intake valve 14 is in a specific opening range including the fully open state, the specific tangent ST intersects with the portion of the exhaust valve 15 in the closed state located within the cylinder 11. Specifically, when the closed state is set to 0% opening and the fully open state is set to 100% opening, the specific tangent ST intersects with the portion of the exhaust valve 15 in the closed state located within the cylinder 11 when the intake valve 14 is in an opening range of approximately 75% to 100%.

[0042] As described above, the shape of the guide portion 23 is defined such that a specific tangent ST when the intake valve 14 is in a specific opening range including the fully open state intersects with the portion of the exhaust valve 15 in the umbrella portion 32 located inside the cylinder 11 in the closed state.

[0043] <Regarding the function of this implementation method>

[0044] Depending on the operating state of the internal combustion engine 10, the water injection valve 17 injects water into the intake passage 12. The injected water flows into the cylinder 11 through the space surrounding the intake valve 14. The water flowing into the cylinder 11 reaches the upper surface 22A of the umbrella portion 22 of the intake valve 14. The water that reaches the upper surface 22A of the umbrella portion 22 flows along the upper surface 22A. That is, the water that reaches the upper surface 22A of the umbrella portion 22 of the intake valve 14 flows along the guide portion 23. The water is dispersed from the guide portion 23 at the tangent point P1 of a specific tangent line ST relative to the guide portion 23. The dispersed water moves along the specific tangent line ST. That is, the guide portion 23 acts like a jump platform for the water moving along the upper surface 22A.

[0045] <Regarding the effects of this implementation method>

[0046] (1) In the above embodiment, as described above, the water sprayed from the water jet valve 17 flows along the guide portion 23. The water disperses along a specific tangent ST, and as a result, is guided toward the exhaust valve 15. Therefore, the sprayed water easily collides with the exhaust valve 15. By guiding the water toward the exhaust valve 15, the exhaust valve 15 can be cooled efficiently.

[0047] (2) Assuming the curvature of the guide portion 23 is large, the momentum of water flowing along the upper surface 22A is easily attenuated at the guide portion 23. The larger the area of ​​the guide portion 23 relative to the umbrella portion 22, the smaller the curvature of the bend can be, and therefore the less likely the momentum of water flowing along the upper surface 22A is attenuated at the guide portion 23. In the above embodiment, the width dimension L2 of the guide portion 23 in the direction orthogonal to the central axis C1 is more than 1 / 4 of the outer diameter L1 of the umbrella portion 22. Therefore, according to the above embodiment, the guide portion 23 is provided in a considerable area of ​​the upper surface 22A of the umbrella portion 22. As a result, the momentum of water is not easily attenuated, and water sprayed from the umbrella portion 22 easily reaches the exhaust valve 15.

[0048] (3) In the above embodiment, in the imaginary cross-section, the guide portion 23 is continuous with the outer surface of the shaft portion 21. In other words, there are no steps or the like at the junction of the outer surface of the shaft portion 21 and the upper surface 22A of the umbrella portion 22. According to this structure, problems such as the flow of water being obstructed by the junction of the outer surface of the shaft portion 21 and the upper surface 22A of the umbrella portion 22 will not occur.

[0049] (4) Assumption: The guide portion 23 is not annular, but only provided within a certain angular range around the central axis C1. In this case, when assembling the intake valve 14, it is necessary to adjust the position of the guide portion 23 relative to the exhaust valve 15 to make it a suitable position. In addition, it is necessary to prevent the assembled intake valve 14 from rotating around the central axis C1. On the other hand, in the above embodiment, when viewed from the direction along the central axis C1, the guide portion 23 is provided in an annular shape around the central axis C1. Therefore, when assembling the intake valve 14, it is not necessary to adjust the position of the guide portion 23 as described above. As a result, the assembly of the intake valve 14 becomes simple.

[0050] (5) In the above embodiment, not only when the intake valve 14 is fully open, but also when the intake valve 14 is in a specific opening range including the fully open state, the specific tangent ST intersects with the portion of the exhaust valve 15 located in the cylinder 11. Therefore, during the process of the intake valve 14 moving from the closed state to the fully open state, water is also appropriately guided by the guide portion 23 toward the exhaust valve 15.

[0051] <Example of Change>

[0052] This embodiment can be modified as follows. This embodiment and the following modifications can be combined with each other within the scope of technical inconsistency.

[0053] • In the above embodiments, the shape of the guide portion 23 may also be specified in such a way that a specific tangent ST intersects with the spark plug 16.

[0054] Specifically, for example, such as Figure 4 As shown, a tangent line tangent to the guide portion 23 is drawn on an imaginary cross-section including the central axis C1 of the intake valve 14 and the central axis of the spark plug 16. On this imaginary cross-section, a tangent line tangent to the guide portion 23 is drawn. Figure 3 Similarly, the tangent line that is tangent to the guide portion 23 and minimizes the specific angle SA is the specific tangent line ST. When the intake valve 14 is fully open, the specific tangent line ST intersects the portion of the spark plug 16 located inside the cylinder 11. According to this modified example, as explained in the effect of (1) above, water can be directed toward the spark plug 16. Therefore, the spark plug 16 can be cooled efficiently. In this modified example, the specific tangent line ST may also intersect the portion of the spark plug 16 located inside the cylinder 11 when the intake valve 14 is in a certain opening range including the fully open state.

[0055] • In the above embodiments, the structure of the internal combustion engine 10 is not limited to the examples of the above embodiments. For example, the number of cylinders 11 may also differ from the examples of the above embodiments. In addition, the number of water injection valves 17 is not limited to the examples described above.

[0056] In the above embodiment, a specific tangent ST in an imaginary cross-section of the central axis C1 of the shaft portion 21 of the intake valve 14 and the central axis C2 of the shaft portion 31 of the exhaust valve 15 has been described, but the imaginary cross-section is not limited to such a cross-section. The specific tangent ST can be drawn in an imaginary cross-section parallel to the central axis C1 of the shaft portion 21 and passing through the guide portion 23. At least one imaginary cross-section is required where the specific tangent ST intersects with the portion of the exhaust valve 15 located within the cylinder 11.

[0057] In the above embodiment, the width L2 of the guide portion 23 may also be less than 1 / 4 of the outer diameter L1 of the umbrella portion 22. The width L2 can be appropriately changed according to the outer diameter L1 of the umbrella portion 22, the curvature of the arc of the guide portion 23, the flow rate of the water sprayed from the water jet valve 17, etc.

[0058] In the above embodiment, the guide portion 23 may not be smoothly continuous with the outer surface of the shaft portion 21. That is, there may be a slope or step between the shaft portion 21 and the guide portion 23.

[0059] In the above embodiment, the guide portion 23 may not be arranged in a circular shape around the central axis C1. The guide portion 23 may be located on the side of the umbrella portion 22 that is closer to the exhaust valve 15 relative to the central axis C1.

[0060] • In the imaginary cross-section, the guide portion 23 may not be arc-shaped. The guide portion 23 may also have a straight section in the imaginary cross-section.

[0061] • In the above embodiments, it is also possible that a specific tangent ST intersects only when the intake valve 14 is fully open and the portion of the exhaust valve 15 located inside the cylinder 11 in the closed state.

Claims

1. An internal combustion engine, comprising: A cylinder has an intake port and an exhaust port; Spark plug, having a top located inside the cylinder; An intake passage is connected to the intake opening of the cylinder; An exhaust passage is connected to the exhaust opening of the cylinder; A water jet valve is located within the air intake passage and is configured to jet water into the air intake passage. The intake valve is configured to selectively open and close the intake opening; and The exhaust valve is configured to selectively open and close the exhaust opening. The intake valve has a rod-shaped shaft and an umbrella-shaped portion connected to the top of the shaft and located inside the cylinder. The outer surface of the umbrella section has an upper surface facing the air inlet. The upper surface includes a curved guide portion. The guide portion has a specific tangent line that intersects with one or more of the following when the intake valve is fully open: the portion of the spark plug located in the cylinder and the portion of the exhaust valve located in the cylinder when the exhaust valve is closed. On an imaginary cross-section parallel to the central axis of the umbrella section and passing through the guide section, the angle formed by a line segment that coincides with the tangent to the guide section and extends from the point of tangency of the tangent relative to the guide section to the point of intersection of the tangent relative to the central axis, and a line segment that coincides with the central axis and extends from the intersection point toward the air intake passage, is a specific angle. The tangent that minimizes the specific angle is the specific tangent.

2. The internal combustion engine according to claim 1, In a direction orthogonal to the central axis, the maximum width of the guide portion is more than 1 / 4 of the outer diameter of the umbrella portion.

3. The internal combustion engine according to claim 1, On the hypothetical cross section, The outer surface of the shaft is a straight line. The guide portion is concave and arc-shaped, and is continuous with the outer surface of the shaft portion.

4. The internal combustion engine according to claim 1, When viewed from a direction along the central axis, the guide portion is arranged in a circular shape around the central axis.

5. The internal combustion engine according to any one of claims 1 to 4, When the intake valve is in a specific opening range including the fully open state, the specific tangent intersects with one or more selected from the portion of the spark plug located in the cylinder and the portion of the exhaust valve located in the cylinder when it is closed.

Images