Internal combustion engine
The use of a porous valve guide with a flow passage addresses oil shortage issues by ensuring consistent lubrication between the valve guide and shaft, enhancing engine performance.
Patent Information
- Application Number
- JP2024116914
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-07-22
- Publication Date
- 2026-02-03
AI Technical Summary
In internal combustion engines, there is a risk of oil shortage between the inner and outer surfaces of the valve guide and shaft due to oil adherence, which can lead to lubrication issues.
The valve guide is made of a porous material with an opening on its outer peripheral surface and a flow passage leading from the exposed portion to the inserted portion, allowing oil to penetrate and distribute evenly.
This configuration prevents oil shortage and ensures consistent lubrication between the valve guide and shaft, maintaining engine performance.
Smart Images
Figure 2026015969000001_ABST
Abstract
Description
[Technical Field]
[0001] The present invention relates to an internal combustion engine. [Background technology]
[0002] The internal combustion engine of Patent Document 1 includes a head cover, a cylinder head, a valve guide, a valve, and a valve mechanism. The head cover and the cylinder head define an accommodation space that accommodates the valve mechanism. The cylinder head includes an exhaust port through which exhaust gas flows. The cylinder head includes a fixing hole. The fixing hole leads from the accommodation space to the exhaust port. The valve guide is cylindrical in shape. The valve guide is inserted into the fixing hole. A portion of the valve guide protrudes from the fixing hole into the accommodation space. The valve includes a shaft and a valve element. The shaft is inserted inside the valve guide. The valve element extends from the shaft. The valve element opens and closes the exhaust port. [Prior art documents] [Patent documents]
[0003] [Patent Document 1] Japanese Patent Publication No. 2023-082746 Summary of the Invention [Problem to be solved by the invention]
[0004] In an internal combustion engine such as that described in Patent Document 1, the components located in the accommodation space are generally lubricated by the oil in the accommodation space. Therefore, in the internal combustion engine of Patent Document 1, for example, if oil from the accommodation space adheres to the tip of the portion of the valve guide located in the accommodation space, the oil can be introduced into the gap between the inner circumferential surface of the valve guide and the outer circumferential surface of the valve shaft. However, in the internal combustion engine of Patent Document 1, there is a risk of a shortage of oil between the inner circumferential surface of the valve guide and the outer circumferential surface of the valve shaft. [Means for solving the problem]
[0005] An internal combustion engine for solving the above problem comprises a head cover, a cylinder head connected to the head cover, a cylindrical valve guide fixed to the cylinder head, a valve inserted into the valve guide, and a valve mechanism that operates the valve, wherein the head cover and the cylinder head define an accommodation space that accommodates the valve mechanism, the cylinder head comprises a gas passage through which gas flows and a fixed hole that leads from the accommodation space to the gas passage, the valve comprises a shaft inserted into the valve guide and a valve element extending from the shaft to open and close the gas passage, the valve guide is made of a porous material, the valve guide is inserted into the fixed hole and a portion of the valve guide protrudes from the fixed hole into the accommodation space, and when the portion of the valve guide that is exposed to the accommodation space is defined as the exposed portion and the portion of the valve guide that is inserted into the fixed hole is defined as the inserted portion, the valve guide has an opening at the outer peripheral surface of the exposed portion and a flow passage that leads from the exposed portion to the inserted portion. [Effects of the Invention]
[0006] According to the above configuration, it is possible to prevent a shortage of oil between the inner peripheral surface of the valve guide and the outer peripheral surface of the valve shaft. [Brief explanation of the drawings]
[0007] [Figure 1] FIG. 1 is a cross-sectional view showing a schematic configuration of an internal combustion engine. [Figure 2] FIG. 2 is a cross-sectional view showing the peripheral configuration of the combustion chamber. [Figure 3] FIG. 3 is a cross-sectional view showing the peripheral configuration of the exhaust valve guide. [Figure 4] FIG. 4 is a cross-sectional view showing the configuration of the exhaust side valve guide. [Figure 5] FIG. 5 is a cross-sectional view showing the configuration of an exhaust-side valve guide according to a modified example. DETAILED DESCRIPTION OF THE INVENTION
[0008] <General configuration of an internal combustion engine> An embodiment of the present invention will be described below with reference to Figures 1 to 4. First, a general configuration of an internal combustion engine 100 will be described. In the following description, the front-rear, left-right, and up-down directions refer to directions as seen from a driver seated in the driver's seat of a vehicle in which the internal combustion engine 100 is mounted.
[0009] 1, the internal combustion engine 100 includes a head cover 20, a cylinder head 30, a cylinder block 40, a crankcase 50, and an oil pan 60. The internal combustion engine 100 also includes an intake pipe 71, an exhaust pipe 72, a plurality of pistons 76, a plurality of connecting rods 77, a crankshaft 78, a plurality of fuel injection valves 81, and a plurality of ignition devices 82.
[0010] The cylinder block 40 has an overall rectangular prism shape. The cylinder block 40 has four cylinders 41 as an internal space. The cylinders 41 are approximately cylindrical in shape. The cylinders 41 extend from the upper end of the cylinder block 40 to near the center of the cylinder block 40 from top to bottom. The cylinders 41 are spaces for burning a mixture of fuel and intake air. In this embodiment, an example of fuel for the internal combustion engine 100 is hydrogen. In the internal combustion engine 100, the crankshaft 78 extends to the left and right of the vehicle. Therefore, the internal combustion engine 100 is a so-called horizontally mounted engine. In FIG. 1, only one of the four cylinders 41 is shown as a representative.
[0011] The cylinder block 40 has four upper spaces 42 as internal spaces. The upper ends of the upper spaces 42 are connected to the lower ends of the cylinders 41. The upper spaces 42 extend from the lower ends of the cylinders 41 to the lower end of the cylinder block 40.
[0012] The crankcase 50 is connected to the lower end of the cylinder block 40. The crankcase 50 has a so-called ladder frame structure. Therefore, the crankcase 50 has four lower spaces 51 as its internal space. The lower spaces 51 penetrate the crankcase 50 from its top to its bottom. The upper ends of the lower spaces 51 in the crankcase 50 are connected to the lower end of the upper space 42 in the cylinder block 40.
[0013] The oil pan 60 is connected to the lower end of the crankcase 50. The oil pan 60 is shaped like a generally rectangular box with a bottom. Therefore, the oil pan 60 has an oil chamber 61 as an internal space. The upper end of the oil chamber 61 is connected to the lower ends of the four lower spaces 51. The oil chamber 61 stores oil. The oil stored in the oil chamber 61 is supplied to each part of the internal combustion engine 100, including the valve train 83 described below, by an oil pump (not shown). That is, the oil stored in the oil chamber 61 is also supplied to the accommodation space 10A described below. The oil supplied to each part of the internal combustion engine 100 returns to the oil chamber 61 via a passage (not shown).
[0014] The pistons 76 are located inside the cylinders 41. The pistons 76 are connected to the crankshaft 78 via connecting rods 77. The crankshaft 78 is rotatably supported between the cylinder block 40 and the crankcase 50. The pistons 76 reciprocate inside the cylinders 41 as a result of combustion of a mixture of fuel and intake air in a combustion chamber 10Z (described later). The reciprocating motion of the pistons 76 causes the crankshaft 78 to rotate. The internal combustion engine 100 includes four pistons 76 and four connecting rods 77 corresponding to the four cylinders 41.
[0015] The cylinder head 30 is connected to the upper end of the cylinder block 40. The cylinder head 30 has an overall rectangular prism shape. The cylinder head 30 has four intake ports 31, four exhaust ports 32, four combustion recesses 33, and an internal space 34 as internal spaces. The internal space 34 is recessed downward from the upper surface of the cylinder head 30. The combustion recesses 33 are recessed upward from the lower surface of the cylinder head 30. The combustion recesses 33 are located opposite the cylinders 41. The combustion recesses 33 are connected to the upper ends of the cylinders 41. The combustion recesses 33, the cylinders 41, and the pistons 76 define combustion chambers 10Z in which a mixture of fuel and intake air is combusted. In this embodiment, the internal combustion engine 100 has four combustion chambers 10Z.
[0016] A first end of the intake port 31 is connected to the combustion recess 33 of the combustion chamber 10Z. A second end of the intake port 31 opens to the front surface of the cylinder head 30. The intake pipe 71 is connected to the front surface of the cylinder head 30. The intake port 31 introduces intake gas from outside the internal combustion engine 100 into the combustion chamber 10Z via the intake pipe 71.
[0017] A first end of the exhaust port 32 is connected to the combustion recess 33 of the combustion chamber 10Z. A second end of the exhaust port 32 opens to the rear surface of the cylinder head 30. The exhaust pipe 72 is connected to the rear surface of the cylinder head 30. The exhaust port 32 discharges exhaust gas from the combustion chamber 10Z to the outside of the internal combustion engine 100 via the exhaust pipe 72. In this embodiment, the intake port 31 and the exhaust port 32 are each an example of a gas passage through which gas flows. As described above, the fuel for the internal combustion engine 100 is hydrogen. Therefore, exhaust gas generated by combustion of the hydrogen fuel flows through the exhaust port 32.
[0018] The fuel injection valve 81 is attached to the cylinder head 30. The tip of the fuel injection valve 81 is located midway through the intake port 31. The fuel injection valve 81 injects fuel from a fuel tank (not shown) into the intake port 31. In this embodiment, the internal combustion engine 100 is provided with four fuel injection valves 81 corresponding to the four combustion chambers 10Z.
[0019] The ignition device 82 is attached to the cylinder head 30. The tip of the ignition device 82 is located in the combustion chamber 10Z. The ignition device 82 ignites the mixture of fuel and intake air by spark discharge. In this embodiment, the internal combustion engine 100 is provided with four ignition devices 82 corresponding to the four combustion chambers 10Z.
[0020] The head cover 20 is connected to the upper end of the cylinder head 30. The head cover 20 is shaped like a generally rectangular box with a top plate. Therefore, the head cover 20 has an internal space 21. The internal space 21 of the head cover 20 and the internal space 34 of the cylinder head 30 define an accommodation space 10A for accommodating a valve train 83, which will be described later.
[0021] <Combustion chamber peripheral configuration> As shown in FIG. 2, the cylinder head 30 has an internal space including four intake-side fixing holes 36A and four exhaust-side fixing holes 36B. The intake-side fixing holes 36A lead from the accommodation space 10A to the intake port 31. The intake-side fixing holes 36A extend from the accommodation space 10A toward the connection between the intake port 31 and the combustion chamber 10Z. The intake-side fixing holes 36A are generally cylindrical. The exhaust-side fixing holes 36B lead from the accommodation space 10A to the exhaust port 32. The exhaust-side fixing holes 36B extend from the accommodation space 10A toward the connection between the exhaust port 32 and the combustion chamber 10Z. The exhaust-side fixing holes 36B are generally cylindrical. In this embodiment, the intake-side fixing holes 36A and the exhaust-side fixing holes 36B are each an example of a fixing hole.
[0022] 2, the internal combustion engine 100 includes a valve train 83, a plurality of stem seals 86, a plurality of retainers 87, and a plurality of valve springs 88. The internal combustion engine 100 also includes a plurality of intake valve guides 90A, a plurality of exhaust valve guides 90B, a plurality of intake valves 95A, and a plurality of exhaust valves 95B. In this embodiment, the intake valve guide 90A and the exhaust valve guide 90B are each an example of a valve guide. The intake valve 95A and the exhaust valve 95B are each an example of a valve.
[0023] As shown in FIG. 3, the exhaust-side valve guide 90B is generally cylindrical. The outer diameter of the exhaust-side valve guide 90B is approximately the same as the inner diameter of the exhaust-side fixing hole 36B. The exhaust-side valve guide 90B is fixed to the exhaust-side fixing hole 36B by press-fitting. In other words, the exhaust-side valve guide 90B is inserted into the exhaust-side fixing hole 36B. The upper end of the exhaust-side valve guide 90B is located in the accommodation space 10A. In other words, a portion of the exhaust-side valve guide 90B, including its upper end, protrudes from the exhaust-side fixing hole 36B into the accommodation space 10A. In addition, the lower end of the exhaust-side valve guide 90B is located at the boundary between the exhaust-side fixing hole 36B and the exhaust port 32.
[0024] The exhaust side valve guide 90B is made of a porous material. Specifically, the exhaust side valve guide 90B is made of a porous metal. One example of the material for the exhaust side valve guide 90B is an alloy obtained by sintering metal powder, known as a sintered alloy.
[0025] In this embodiment, the exhaust valve guide 90B is manufactured as follows. First, an operator manufacturing the exhaust valve guide 90B forms a workpiece for the exhaust valve guide 90B by sintering metal powder. At this time, the outer diameter of the workpiece for the exhaust valve guide 90B is slightly larger than the outer diameter of the finished exhaust valve guide 90B. Then, the operator grinds the outer peripheral surface of the workpiece for the exhaust valve guide 90B to form the outer peripheral surface 91 of the exhaust valve guide 90B. Note that an example of the grinding allowance is approximately 0.1 mm in diameter.
[0026] In the following description, the portion of the exhaust-side valve guide 90B that is exposed to the accommodation space 10A is also referred to as the exposed portion 90BE. Also, the portion of the exhaust-side valve guide 90B that is inserted into the exhaust-side fixing hole 36B is also referred to as the inserted portion 90BI.
[0027] As shown in FIG. 2, the exhaust-side valve 95B includes a shaft 96 and a valve element 97. The shaft 96 is generally rod-shaped. The outer diameter of the shaft 96 is slightly smaller than the inner diameter of the exhaust-side valve guide 90B. The shaft 96 is inserted into the exhaust-side valve guide 90B. A portion of the shaft 96, including its upper end, protrudes from the exhaust-side valve guide 90B and is located in the accommodation space 10A. A portion of the shaft 96, including its lower end, protrudes from the exhaust-side valve guide 90B and is located in the exhaust port 32. The valve element 97 extends from the lower end of the shaft 96. The valve element 97 opens and closes the connection between the exhaust port 32 and the combustion chamber 10Z.
[0028] As shown in Figure 3, the stem seal 86 is attached to the upper end of the exhaust-side valve guide 90B. The stem seal 86 is generally annular in shape. The stem seal 86 adjusts the amount of oil that flows between the inner circumferential surface 92 of the exhaust-side valve guide 90B and the outer circumferential surface of the shaft 96 of the exhaust-side valve 95B via the upper end of the exhaust-side valve guide 90B.
[0029] 2, the retainer 87 is attached near the upper end of the shaft 96 of the exhaust-side valve 95B. The valve spring 88 is located between the retainer 87 and the inner surface of the internal space 34 of the accommodation space 10A. The valve spring 88 applies force to the exhaust-side valve 95B via the retainer 87 to close the exhaust-side valve 95B.
[0030] The valve mechanism 83 is in contact with the upper end of the shaft 96 of the exhaust-side valve 95B. The valve mechanism 83 transmits power to the shaft 96 of the exhaust-side valve 95B in accordance with the rotation of the crankshaft 78, thereby opening the exhaust-side valve 95B against the force of the valve spring 88. Thus, the valve mechanism 83 operates the exhaust-side valve 95B.
[0031] The intake side valve guide 90A is generally cylindrical in shape. The intake side valve guide 90A is fixed to the intake side fixing hole 36A by press fitting. The configuration of the intake side valve guide 90A is the same as that of the exhaust side valve guide 90B described above. Therefore, a description of the configuration of the intake side valve guide 90A will be omitted.
[0032] The intake side valve 95A, like the exhaust side valve 95B, has a shaft 96 and a valve element 97. The shaft 96 of the intake side valve 95A is inserted into the intake side valve guide 90A. The configuration of the intake side valve 95A is the same as that of the exhaust side valve 95B. Therefore, a description of the configuration of the intake side valve 95A will be omitted. The configuration around the intake side valve 95A, i.e., the configuration of the stem seal 86, the retainer 87, and the valve mechanism 83, is the same as that around the exhaust side valve 95B. Therefore, a description of the configuration around the intake side valve 95A will be omitted.
[0033] <Detailed configuration of the valve guide> As shown in Fig. 4, the exhaust-side valve guide 90B has an annular groove 93 and a plurality of flow passages 94. The annular groove 93 is recessed from the outer peripheral surface 91 of the exhaust-side valve guide 90B. When the exhaust-side valve guide 90B is viewed from the direction along the axis of the exhaust-side valve guide 90B, the annular groove 93 has a circular ring shape. As shown in Fig. 3, the annular groove 93 is located near the upper end of the exhaust-side valve guide 90B. In other words, the annular groove 93 is located in the exposed portion 90BE of the exhaust-side valve guide 90B.
[0034] As shown in FIG. 4, the flow passage 94 is recessed from the outer peripheral surface 91 of the exhaust-side valve guide 90B. In this embodiment, the depth of the recess of the flow passage 94 is the same as the depth of the recess of the annular groove 93. The depth of the recess of the flow passage 94 is, for example, approximately several millimeters. The flow passage 94 extends along the axis of the exhaust-side valve guide 90B. A first end of the flow passage 94 is connected to the annular groove 93. That is, as shown in FIG. 3, the first end of the flow passage 94 is located in the exposed portion 90BE of the exhaust-side valve guide 90B. The second end of the flow passage 94 is located in the inserted portion 90BI of the exhaust-side valve guide 90B. In other words, the flow passage 94 extends from the exposed portion 90BE to the inserted portion 90BI of the exhaust-side valve guide 90B. Here, the intermediate position 90BZ is the intermediate position of the insertion portion 90BI of the exhaust-side valve guide 90B in the direction along the axis of the exhaust-side valve guide 90B. In this case, the flow passage 94 extends from the exposed portion 90BE of the exhaust-side valve guide 90B to a portion of the insertion portion 90BI on the exhaust port 32 side with respect to the intermediate position 90BZ. The flow passage 94 is a groove that opens on the outer peripheral surface 91 of the exhaust-side valve guide 90B throughout the entire portion from the exposed portion 90BE to the insertion portion 90BI. Furthermore, the flow passage 94 communicates with the housing space 10A but is closed to the exhaust port 32. In other words, the flow passage 94 does not communicate with the exhaust port 32. The dimension perpendicular to the extension direction of the flow passage 94 and the recess direction of the flow passage 94, i.e., the width dimension of the flow passage 94, is, for example, approximately several millimeters.
[0035] In this embodiment, the exhaust-side valve guide 90B has four flow passages 94. When the exhaust-side valve guide 90B is viewed from a direction along the axis of the exhaust-side valve guide 90B, the four flow passages 94 are arranged at regular intervals in the circumferential direction of the outer circumferential surface 91 of the exhaust-side valve guide 90B.
[0036] <Operation of this embodiment> The exhaust-side valve guide 90B is made of a porous material. Therefore, if oil present in the housing space 10A adheres to the surface of the exhaust-side valve guide 90B, the oil will penetrate into the interior of the exhaust-side valve guide 90B. However, during the manufacturing process of the exhaust-side valve guide 90B, the outer peripheral surface of the intermediate member of the exhaust-side valve guide 90B is ground to form the outer peripheral surface 91 of the exhaust-side valve guide 90B. Therefore, the grinding process eliminates minute cavities in the outer peripheral surface 91 of the exhaust-side valve guide 90B. As a result, even if oil adheres to the outer peripheral surface 91 of the exhaust-side valve guide 90B, the oil will not easily penetrate from the outer peripheral surface 91 into the interior of the exhaust-side valve guide 90B.
[0037] <Effects of this embodiment> (1) As shown in FIG. 4 , in this embodiment, the exhaust-side valve guide 90B includes a flow passage 94. The grinding process does not eliminate minute cavities on the inner surface of the flow passage 94. Therefore, as shown by the dashed arrow in FIG. 3 , when oil present in the accommodation space 10A reaches the flow passage 94 of the exhaust-side valve guide 90B, the oil penetrates into the interior through the minute cavities on the inner surface of the flow passage 94. The oil is then introduced into the gap between the inner circumferential surface 92 of the exhaust-side valve guide 90B and the outer circumferential surface of the shaft 96 of the exhaust-side valve 95B. Furthermore, the flow passage 94 extends from the exposed portion 90BE of the exhaust-side valve guide 90B to the inserted portion 90BI. Therefore, as shown by the dashed arrow in FIG. 3 , the oil that reaches the flow passage 94 also flows from the exposed portion 90BE to the inserted portion 90BI through the flow passage 94. This allows oil to be easily introduced not only between the inner circumferential surface 92 of the exposed portion 90BE and the outer circumferential surface of the shaft 96 of the exhaust-side valve 95B, but also between the inner circumferential surface 92 of the insertion portion 90BI and the outer circumferential surface of the shaft 96 of the exhaust-side valve 95B. As a result, it is possible to prevent a shortage of oil between the inner circumferential surface 92 of the exhaust-side valve guide 90B and the outer circumferential surface of the shaft 96 of the exhaust-side valve 95B. The intake-side valve guide 90A has the same effects as the exhaust-side valve guide 90B described above.
[0038] (2) As shown in Figure 3, the flow passage 94 extends from the exposed portion 90BE of the exhaust-side valve guide 90B to a portion of the insertion portion 90BI that is closer to the exhaust port 32 than the intermediate position 90BZ. In other words, the flow passage 94 extends from the exposed portion 90BE to a portion of the exhaust-side valve guide 90B that is closer to the exhaust port 32. This allows oil to be introduced to the portion between the inner circumferential surface 92 of the exhaust-side valve guide 90B and the outer circumferential surface of the shaft 96 of the exhaust-side valve 95B that is closer to the exhaust port 32, where oil shortages are particularly likely. The intake-side valve guide 90A has the same effects as the exhaust-side valve guide 90B.
[0039] (3) As shown in Figure 3, the flow passage 94 communicates with the accommodation space 10A but is closed to the exhaust port 32. Because the flow passage 94 is closed to the exhaust port 32 in this manner, oil that has reached the flow passage 94 is prevented from flowing from the flow passage 94 to the exhaust port 32. Preventing oil from flowing from the flow passage 94 to the exhaust port 32 prevents the amount of oil present in the accommodation space 10A and the amount of oil stored in the oil chamber 61 from decreasing excessively. The intake-side valve guide 90A also provides the same effects as the exhaust-side valve guide 90B.
[0040] (4) Exhaust gas generated by the combustion of hydrogen fuel flows through the exhaust port 32. The amount of carbon polymers contained in the exhaust gas is smaller than that contained in the exhaust gas of, for example, a gasoline engine. Therefore, lubrication by carbon polymers between the inner circumferential surface 92 of the exhaust valve guide 90B and the outer circumferential surface of the shaft 96 of the exhaust valve 95B cannot be expected. Furthermore, the amount of moisture contained in the exhaust gas is larger than that contained in the exhaust gas of, for example, a gasoline engine. Therefore, moisture contained in the exhaust gas is likely to reach the gap between the inner circumferential surface 92 of the exhaust valve guide 90B and the outer circumferential surface of the shaft 96 of the exhaust valve 95B, thereby reducing the lubrication performance of the oil. In other words, the amount of oil required between the inner circumferential surface 92 of the exhaust valve guide 90B and the outer circumferential surface of the shaft 96 of the exhaust valve 95B is likely to increase. Therefore, it is particularly preferable to apply the present technology to the exhaust valve guide 90B of an internal combustion engine 100 that uses hydrogen as fuel, i.e., a hydrogen engine.
[0041] (5) As shown in FIG. 3, the flow passage 94 is a groove that opens in the outer peripheral surface 91 of the exhaust-side valve guide 90B throughout the entire area from the exposed portion 90BE to the inserted portion 90BI. In other words, the flow passage 94 is a groove that opens in the outer peripheral surface 91 of the exhaust-side valve guide 90B throughout the entire area where the flow passage 94 exists. This configuration simplifies the structure of the exhaust-side valve guide 90B compared to a configuration in which the flow passage 94, which serves as a passage between the outer peripheral surface 91 and the inner peripheral surface 92 of the exhaust-side valve guide 90B, extends from the exposed portion 90BE to the inserted portion 90BI, as shown in FIG. 5, for example. This prevents the manufacturing process of the exhaust-side valve guide 90B from becoming complicated. This is expected to reduce the manufacturing cost of the exhaust-side valve guide 90B. The intake-side valve guide 90A achieves the same effects as the exhaust-side valve guide 90B described above.
[0042] <Example of change> This embodiment can be modified as follows: This embodiment and the following modifications can be combined and implemented within the scope of technical compatibility.
[0043] In the above embodiment, the configuration of the exhaust valve guide 90B may be changed. For example, the four flow passages 94 do not have to be arranged at regular intervals in the circumferential direction of the outer circumferential surface 91 of the exhaust side valve guide 90B.
[0044] For example, the exhaust-side valve guide 90B may have three or fewer flow passages 94, or may have five or more flow passages 94. In this case, the positions of the flow passages 94 may be adjusted as appropriate. From the perspective of suppressing variations in the amount of oil between the inner circumferential surface 92 of the exhaust-side valve guide 90B and the outer circumferential surface of the shaft 96 of the exhaust-side valve 95B, it is preferable that the plurality of flow passages 94 be arranged at regular intervals in the circumferential direction of the exhaust-side valve guide 90B.
[0045] For example, the second end of the flow passage 94 may be located on the accommodating space 10A side of the intermediate position 90BZ of the insertion portion 90BI. In other words, the flow passage 94 does not have to extend from the exposed portion 90BE of the exhaust-side valve guide 90B to the portion of the insertion portion 90BI on the exhaust port 32 side of the intermediate position 90BZ.
[0046] For example, the flow passage 94 may be in communication with the exhaust port 32. As a specific example, the flow passage 94 may be in communication with the exhaust port 32 as long as the amount of oil flowing from the flow passage 94 to the exhaust port 32 is tolerable.
[0047] For example, the flow passage 94 does not have to extend along the axis of the exhaust side valve guide 90B. As a specific example, the flow passage 94 may be a spiral groove centered on the axis of the exhaust side valve guide 90B.
[0048] For example, the relative configuration of the flow passage 94 and the annular groove 93 may be changed. As a specific example, the depth of the recess of the flow passage 94 may be different from the depth of the recess of the annular groove 93. Also, as a specific example, the flow passage 94 may not be connected to the annular groove 93.
[0049] For example, the flow passage 94 does not have to be a groove that opens in the outer peripheral surface 91 of the exhaust-side valve guide 90B throughout the entire area from the exposed portion 90BE to the inserted portion 90BI. As a specific example, as shown in FIG. 5, the flow passage 94 may be a passage that opens only in a portion of the outer peripheral surface 91 of the exposed portion 90BE. The flow passage 94 only needs to extend from the exposed portion 90BE to the inserted portion 90BI of the exhaust-side valve guide 90B. The exhaust-side valve guide 90B shown in FIG. 5 may be manufactured, for example, as follows: First, a worker forms a first intermediate member of the exhaust-side valve guide 90B by sintering metal powder. Then, a worker forms a second intermediate member of the exhaust-side valve guide 90B by sintering metal powder. Here, the first intermediate member corresponds to a portion of the exhaust-side valve guide 90B including the upper end. The second intermediate member corresponds to the portion of the exhaust-side valve guide 90B other than the first intermediate member. Next, the worker forms the flow passage 94 in the second intermediate member by machining using a cutting tool. After that, the worker forms the intermediate member by joining the first intermediate member and the second intermediate member. Then, the worker grinds the outer peripheral surface of the intermediate member of the exhaust side valve guide 90B to form the outer peripheral surface 91 of the exhaust side valve guide 90B. Note that the above manufacturing process is an example, and other manufacturing processes may be used.
[0050] For example, the material of the exhaust valve guide 90B is not limited to sintered alloy. That is, the material of the exhaust valve guide 90B may be a porous metal other than sintered alloy. Furthermore, the material of the exhaust valve guide 90B may be a porous material other than metal.
[0051] For example, the manufacturing process of the exhaust-side valve guide 90B may be changed. As a specific example, first, a worker manufacturing the exhaust-side valve guide 90B forms an intermediate member of the exhaust-side valve guide 90B by sintering metal powder. At this time, the worker may form the flow passage 94 at the stage of forming the intermediate member. Alternatively, the worker may not form the flow passage 94 at the stage of forming the intermediate member. Note that if the flow passage 94 is not formed at the stage of forming the intermediate member, after forming the intermediate member, the worker may form the flow passage 94 by cutting the outer circumferential surface of the intermediate member of the exhaust-side valve guide 90B. Then, the worker may form the outer circumferential surface 91 of the exhaust-side valve guide 90B by grinding the outer circumferential surface of the intermediate member of the exhaust-side valve guide 90B.
[0052] The above changes are not limited to the configuration of the exhaust valve guide 90B. That is, the above changes can be applied not only to the configuration of the exhaust valve guide 90B, but also to the configuration of the intake valve guide 90A.
[0053] In the above embodiment, the configuration of the internal combustion engine 100 may be changed. For example, the fuel for the internal combustion engine 100 is not limited to hydrogen. As a specific example, the fuel for the internal combustion engine 100 may be gasoline, diesel, or the like. In other words, the present technology can be applied to engines other than hydrogen engines.
[0054] For example, the technology related to the flow passage 94 may be applied to only some of the valve guides included in the internal combustion engine 100. As a specific example, only one of the intake side valve guide 90A and the exhaust side valve guide 90B may be provided with the flow passage 94. As a specific example, only some of the exhaust side valve guides 90B may be provided with the flow passage 94. Similarly, only some of the intake side valve guides 90A may be provided with the flow passage 94. [Explanation of symbols]
[0055] DESCRIPTION OF SYMBOLS 10A...Accommodating space 10Z...Combustion chamber 20...Head cover 30...Cylinder head 31...Intake port 32...Exhaust port 33...Combustion recess 36A...Intake side fixing hole 36B...Exhaust side fixing hole 40...Cylinder block 41...Cylinder 50...Crankcase 60...Oil pan 61...Oil chamber 71...Intake pipe 72...Exhaust pipe 76...Piston 77...Connecting rod 78...Crankshaft 81...Fuel injection valve 82...Ignition device 83...Valve train 86...Stem seal 87...Retainer 88...Valve spring 90A...Intake side valve guide 90B...Exhaust side valve guide 90BE...Exposed portion 90BI...Insertion portion 90BZ...Intermediate position 91...Outer surface 92...Inner surface 93...Annular groove 94...Flow passage 95A...Intake side valve 95B... Exhaust side valve 96... Shaft body 97... Valve body 100... Internal combustion engine
Claims
1. a head cover; a cylinder head connected to the head cover; a cylindrical valve guide fixed to the cylinder head; a valve inserted into the valve guide; and a valve mechanism that operates the valve, the head cover and the cylinder head define an accommodation space that accommodates the valve mechanism, The cylinder head includes a gas passage through which gas flows, and a fixing hole extending from the accommodation space to the gas passage, the valve includes a shaft inserted into the valve guide, and a valve element extending from the shaft to open and close the gas passage, The valve guide is made of a porous material, The valve guide is inserted into the fixing hole, and a portion of the valve guide protrudes from the fixing hole into the accommodation space, When a portion of the valve guide that is exposed to the accommodation space is defined as an exposed portion and a portion that is inserted into the fixing hole is defined as an inserted portion, The valve guide has an opening at the outer peripheral surface of the exposed portion and a flow passage extending from the exposed portion to the inserted portion. Internal combustion engine.
2. When the middle position of the insertion portion in the direction along the axis of the valve guide is defined as the middle position, The flow passage extends from the exposed portion to a portion of the insertion portion on the gas passage side with respect to the intermediate position.
2. The internal combustion engine according to claim 1.
3. The flow passage communicates with the accommodation space, but is closed to the gas passage.
3. The internal combustion engine according to claim 2.
4. The flow passage is a groove that opens on the outer circumferential surface of the valve guide over the entire area from the exposed portion to the inserted portion. An internal combustion engine according to any one of claims 1 to 3.
5. The gas passage is an exhaust port through which exhaust gas generated by the combustion of hydrogen as fuel flows. An internal combustion engine according to any one of claims 1 to 3.
Citation Information
Patent Citations
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JP2023082746A