engine

Abstract

To suppress deterioration in strength of a cylinder head without being restricted by the shape of a combustion chamber.SOLUTION: An engine includes a cylinder head, a port formed in the cylinder head to penetrate therethrough, an attachment portion formed to be recessed in the vicinity of the port on a surface on a combustion chamber side of the cylinder head, a valve seat pressed in the attachment portion so that a valve element of a valve can be seated thereon, a valve guide press-in hole formed in the cylinder head to penetrate therethrough, and a valve guide pressed in the valve guide press-in hole so that a stem of the valve can be inserted thereto. A central axis of the attachment portion is inclined to a central axis of the valve guide press-in hole.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to an engine. [Background technology]

[0002] An engine has a cylinder block and a cylinder head. The cylinder block and cylinder head form the combustion chamber of the engine. The cylinder head also has an intake port that communicates with the combustion chamber, and the intake port is provided with an intake valve that opens and closes an opening that connects the combustion chamber to the intake port. An annular valve seat is provided around this opening, on which the intake valve can be seated.

[0003] For example, Patent Document 1 discloses an example of a valve seat for an engine. When the intake valve closes its opening, the intake valve seats on the valve seat. Patent Document 1 discloses that the central axis of the valve seat is shifted and parallel to the central axis of the intake valve stem in order to generate a large tumble flow in the combustion chamber. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 62-23512 Summary of the Invention [Problem to be solved by the invention]

[0005] The cylinder head has an inner surface around the intake port that is recessed to form an annular mounting portion into which an annular valve seat is press-fitted. However, as described in Patent Document 1, if the center axis of the valve seat is shifted parallel to the center axis of the intake valve stem, the thin-walled area between the intake port and the mounting portion expands on the shifted side. As a result, the strength of the cylinder head decreases in the area between the intake port and the mounting portion.

[0006] Furthermore, if the mounting portion of the cylinder head is moved toward the combustion chamber in order to increase the thickness of the thin-walled portion, the volume of the combustion chamber may become smaller or it may become difficult to design the combustion chamber in an ideal shape. Therefore, if the thin-walled portion is made thicker, there may be restrictions on the shape of the combustion chamber.

[0007] In view of the above circumstances, an object of the present invention is to suppress a decrease in the strength of a cylinder head without being restricted by the shape of the combustion chamber. [Means for solving the problem]

[0008] In order to solve the above problem, an engine according to one embodiment of the present invention comprises: A cylinder head, a port formed through the cylinder head; a mounting portion recessed around the port on the combustion chamber side surface of the cylinder head; a valve seat that is press-fitted into the mounting portion and on which a valve element of the valve can be seated; a valve guide press-fit hole formed through the cylinder head; a valve guide that is press-fitted into the valve guide press-fit hole and through which the stem of the valve is inserted; Equipped with The central axis of the mounting portion is inclined with respect to the central axis of the valve guide press-fit hole. And, The angle between the central axis of the port and the central axis of the mounting portion is larger than the angle between the central axis of the mounting portion and the central axis of the valve guide press-fit hole. . In order to solve the above problem, an engine according to another embodiment of the present invention includes: A cylinder head, a port formed through the cylinder head; a mounting portion recessed around the port on the combustion chamber side surface of the cylinder head; a valve seat that is press-fitted into the mounting portion and on which a valve element of the valve can be seated; a valve guide press-fit hole formed through the cylinder head; a valve guide that is press-fitted into the valve guide press-fit hole and through which the stem of the valve is inserted; Equipped with a cavity separate from the port is formed inside the cylinder head at a position opposite the port with respect to the central axis of the valve guide press-fit hole, The central axis of the mounting portion is inclined toward the cavity on the opposite side from the port with respect to the central axis of the valve guide press-fit hole. . In order to solve the above problem, an engine according to another embodiment of the present invention includes: A cylinder head, a port formed through the cylinder head; a mounting portion recessed around the port on the combustion chamber side surface of the cylinder head; a valve seat that is press-fitted into the mounting portion and on which a valve element of the valve can be seated; a valve guide press-fit hole formed through the cylinder head; a valve guide that is press-fitted into the valve guide press-fit hole and through which the stem of the valve is inserted; a rib formed on the combustion chamber side surface of the cylinder head so as to protrude from at least a portion of the periphery of the mounting portion, so that the height of an inner wall of the mounting portion is uniform in the circumferential direction of the mounting portion; Equipped with The central axis of the mounting portion is inclined with respect to the central axis of the valve guide press-fit hole. [Effects of the Invention]

[0009] According to the present invention, it is possible to suppress a decrease in the strength of the cylinder head without being restricted by the shape of the combustion chamber. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of an engine according to this embodiment. [Figure 2] FIG. 2 is a partially enlarged view showing a part of the cylinder head according to the first comparative example. [Figure 3] FIG. 3 is a partial enlarged view showing a part of a cylinder head according to a second comparative example. [Figure 4] FIG. 4 is a partially enlarged view showing a part of the cylinder head according to this embodiment. [Figure 5] FIG. 5 is a partially enlarged view of the valve seat periphery shown in FIG. [Figure 6]FIG. 6 is a partially enlarged view showing a part of the cylinder head before the mounting portion according to this embodiment is formed. [Figure 7] FIG. 7 is a partial enlarged view showing a part of the cylinder head after the mounting portion according to this embodiment is formed. [Figure 8] FIG. 8 is a partial enlarged view showing a part of a cylinder head according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Specific dimensions, materials, numerical values, etc. shown in the embodiments are merely examples for facilitating understanding of the invention and do not limit the present invention unless otherwise specified. In this specification and drawings, elements having substantially the same functions and configurations are designated by the same reference numerals to avoid redundant explanation, and elements not directly related to the present invention are not shown.

[0012] 1 is a schematic diagram showing the configuration of an engine 10 according to this embodiment. The engine 10 is mounted on, for example, a vehicle 1. The engine 10 includes a cylinder block 20, a piston 22, a cylinder head 24, an intake valve 26, and an exhaust valve 28.

[0013] A plurality of cylinders 30 are formed in the cylinder block 20. Pistons 22 are slidably housed in the cylinders 30 and are capable of reciprocating in the axial direction of the cylinders 30. The pistons 22 are connected to a crankshaft (not shown) via connecting rods 32. The crankshaft rotates in accordance with the reciprocating motion of the pistons 22.

[0014] The cylinder head 24 is disposed on the opposite side of the cylinder block 20 from the crankshaft. The cylinder head 24 is disposed on the cylinder 30 so as to cover the upper opening of the cylinder 30, and is connected to the cylinder block 20. A combustion chamber 34 is a space surrounded by the inner surface of the cylinder 30, the inner surface of the cylinder head 24, and the crown surface of the piston 22.

[0015] The cylinder head 24 has an intake port 40 and an exhaust port 42. The intake port 40 and the exhaust port 42 are formed to penetrate the cylinder head 24. The intake port 40 and the exhaust port 42 are in communication with the combustion chamber 34. Specifically, the intake port 40 is connected to the combustion chamber 34 through an opening 44a of the intake port 40 on the combustion chamber 34 side. The exhaust port 42 is connected to the combustion chamber 34 through an opening 44b of the exhaust port 42 on the combustion chamber 34 side.

[0016] The intake valve 26 is provided in the intake port 40 and opens and closes an opening 44a of the intake port 40. The intake valve 26 has an umbrella portion (valve body) 26a and a stem 26b. The umbrella portion 26a is formed at one end of the intake valve 26, and the stem 26b extends from the umbrella portion 26a to the other end of the intake valve 26. When the umbrella portion 26a of the intake valve 26 opens the opening 44a of the intake port 40, air is sent into the combustion chamber 34 through the intake port 40.

[0017] The exhaust valve 28 is provided in the exhaust port 42 and opens and closes an opening 44b of the exhaust port 42. The exhaust valve 28 has an umbrella portion (valve body) 28a and a stem 28b. The umbrella portion 28a is formed at one end of the exhaust valve 28, and the stem 28b extends from the umbrella portion 28a to the other end of the exhaust valve 28. When the umbrella portion 28a of the exhaust valve 28 opens the opening 44b of the exhaust port 42, gas within the combustion chamber 34 is discharged through the exhaust port 42.

[0018] An intake valve guide press-fit hole 46a and an exhaust valve guide press-fit hole 46b are formed in the cylinder head 24. The intake valve guide press-fit hole 46a connects the intake port 40 in the cylinder head 24 to the space outside the cylinder head 24. The exhaust valve guide press-fit hole 46b connects the exhaust port 42 in the cylinder head 24 to the space outside the cylinder head 24. The intake valve guide press-fit hole 46a and the exhaust valve guide press-fit hole 46b are formed to pass through the cylinder head 24.

[0019] An intake valve guide 48a, through which the stem 26b of the intake valve 26 is inserted, is press-fitted into the intake valve guide press-fit hole 46a. An exhaust valve guide 48b, through which the stem 28b of the exhaust valve 28 is inserted, is press-fitted into the exhaust valve guide press-fit hole 46b.

[0020] The central axes of the intake valve guide press-fit hole 46a, the intake valve guide 48a, and the stem 26b of the intake valve 26 are substantially equal. Here, "substantially equal" means both being completely equal and deviating from being completely equal within a tolerance (such as machining accuracy or assembly error) of, for example, ±1 mm. Hereinafter, "equal" or "same" means both being completely equal (the same) and deviating from being completely equal (the same) within a tolerance (such as machining accuracy or assembly error).

[0021] The intake valve guide 48a is cylindrical, and the stem 26b of the intake valve 26 is inserted into it. The intake valve guide 48a guides the movement of the stem 26b of the intake valve 26 in the direction of its central axis. A cam 50a of an intake camshaft 50 abuts the end of the stem 26b of the intake valve 26 opposite the umbrella portion 26a. Although a detailed description will be omitted, as the crankshaft rotates, the intake camshaft 50 and cam 50a rotate, and the rotation of the cam 50a moves the intake valve 26 in the direction of its central axis while being guided by the intake valve guide 48a. This movement of the intake valve 26 opens and closes the opening 44a of the intake port 40.

[0022] The exhaust valve guide 48b is formed in a cylindrical shape, and the stem 28b of the exhaust valve 28 is inserted into it. The exhaust valve guide 48b guides movement of the stem 28b of the exhaust valve 28 in the direction of its central axis. A cam 52a of an exhaust camshaft 52 abuts against the end of the stem 28b of the exhaust valve 28 opposite the head portion 28a. Although a detailed explanation will be omitted, as the crankshaft rotates, the exhaust camshaft 52 and cam 52a rotate, and the rotation of the cam 52a moves the exhaust valve 28 in the direction of its central axis while being guided by the exhaust valve guide 48b. This movement of the exhaust valve 28 opens and closes the opening 44b of the exhaust port 42.

[0023] The cylinder head 24 includes a mounting portion 60a on the intake port 40 side and a valve seat 62a on the intake port 40 side. The mounting portion 60a is a mounting recess for mounting the valve seat 62a to the surface of the cylinder head 24 facing the combustion chamber 34 (the inner surface of the cylinder head 24). The mounting portion 60a is provided around the opening 44a of the intake port 40 facing the combustion chamber 34. The mounting portion 60a is recessed in an annular shape so as to surround the periphery of the opening 44a. The mounting portion 60a is recessed, for example, on the side opposite the combustion chamber 34. In other words, the mounting portion 60a is recessed around the intake port 40 on the surface of the cylinder head 24 facing the combustion chamber 34.

[0024] The valve seat 62a is an annular member formed in a circular ring shape. A hollow portion formed in the radial center of the annular valve seat 62a serves as a vent hole communicating with the intake port 40. The valve seat 62a is press-fitted into the mounting portion 60a and attached to the opening 44a of the intake port 40 on the inner surface of the cylinder head 24. The valve seat 62a is configured so that the umbrella portion 28a of the intake valve 26 can be seated on it. The intake valve 26 closes the opening 44a of the intake port 40 by coming into contact with the valve seat 62a. The valve seat 62a on the intake port 40 side will be described in detail later.

[0025] The cylinder head 24 includes an attachment portion 60b on the exhaust port 42 side and a valve seat 62b on the exhaust port 42 side. The attachment portion 60b is an attachment recess for attaching the valve seat 62b to the surface of the cylinder head 24 facing the combustion chamber 34 (the inner surface of the cylinder head 24). The attachment portion 60b is provided around the opening 44b of the exhaust port 42 facing the combustion chamber 34. The attachment portion 60b is recessed in an annular shape so as to surround the periphery of the opening 44b. The attachment portion 60b is recessed, for example, on the side opposite the combustion chamber 34. In other words, the attachment portion 60b is recessed around the exhaust port 42 on the surface of the cylinder head 24 facing the combustion chamber 34.

[0026] The valve seat 62b is an annular member formed in a circular ring shape. A hollow portion formed in the radial center of the annular valve seat 62b serves as a vent hole that communicates with the exhaust port 42. The valve seat 62b is press-fit into the mounting portion 60b and attached to the opening 44b of the exhaust port 42 on the inner surface of the cylinder head 24. The valve seat 62b is configured so that the head portion 28a of the exhaust valve 28 can be seated on it. The exhaust valve 28 closes the opening 44b of the exhaust port 42 by coming into contact with the valve seat 62b.

[0027] A water jacket WJ is formed inside the cylinder head 24 at a position opposite the intake port 40 with respect to the central axes of the mounting portion 60a and the valve seat 62a. Here, the central axis of the mounting portion 60a is, for example, the central axis of the inner circumferential surface IC (see FIG. 5) of the mounting portion 60a. The central axis of the valve seat 62a is, for example, the central axis of the outer circumferential surface PS (see FIG. 5) of the valve seat 62a. The water jacket WJ is also formed at a position opposite the exhaust port 42 with respect to the central axes of the mounting portion 60b and the valve seat 62b. The water jacket WJ is a cavity separate from the intake port 40 and the exhaust port 42, and is formed at a position separated from the intake port 40 and the exhaust port 42. In this embodiment, the water jacket WJ is formed between the intake port 40 and the exhaust port 42.

[0028] The cylinder head 24 is provided with an injector and a spark plug (not shown). The injector is positioned with its nozzle facing the combustion chamber 34. The injector injects fuel such as gasoline into the combustion chamber 34 at a predetermined timing. The spark plug is positioned with its electrode facing the combustion chamber 34. The spark plug ignites a mixture of air and fuel in the combustion chamber 34 at a predetermined timing, causing combustion. This combustion causes the piston 22 to reciprocate within the cylinder 30.

[0029] Next, cylinder heads 124 and 224 according to first and second comparative examples will be described with reference to Figures 2 and 3. Then, the cylinder head 24 according to this embodiment will be described in detail with reference to Figure 4, in comparison with these comparative examples.

[0030] Figure 2 is a partially enlarged view showing a portion of a cylinder head 124 according to a first comparative example. As shown in Figure 2, the cylinder head 124 according to the first comparative example includes an intake port 40, an intake valve guide press-fit hole 46a, an intake valve guide 48a, an attachment portion 160a, and a valve seat 162a. Below, components that are substantially the same as those in the cylinder head 24 of the present embodiment will be given the same reference numerals and their description will be omitted, and only the portions that differ from the cylinder head 24 of the present embodiment will be described in detail.

[0031] The mounting portion 160a is formed in the cylinder head 124 and is provided around the opening 44a of the intake port 40 on the combustion chamber 34 side. The mounting portion 160a is formed in an annular shape surrounding the opening 44a. The mounting portion 160a is recessed, for example, on the side opposite the combustion chamber 34. The valve seat 162a is formed in an annular shape. The valve seat 162a is press-fitted into the mounting portion 160a. The valve seat 162a is configured so that the intake valve 26 (see FIG. 1) can be seated on it.

[0032] In the first comparative example, the central axis O1 of the mounting portion 160a is substantially aligned with the central axis O2 of the valve seat 162a. The central axis O1 of the mounting portion 160a is also substantially aligned with the central axis O3 of the intake valve guide press-fit hole 46a and the intake valve guide 48a. The central axis O2 of the valve seat 162a is also substantially aligned with the central axis O3 of the intake valve guide press-fit hole 46a and the intake valve guide 48a.

[0033] Figure 3 is a partially enlarged view showing a portion of a cylinder head 224 according to a second comparative example. As shown in Figure 3, the cylinder head 224 according to the second comparative example includes an intake port 40, an intake valve guide press-fit hole 46a, an intake valve guide 48a, an attachment portion 260a, and a valve seat 262a. Below, components that are substantially the same as those in the cylinder head 24 of this embodiment are given the same reference numerals and will not be described again, and only the portions that differ from the cylinder head 24 of this embodiment will be described in detail. In Figure 3, the shape of the valve seat 162a of the first comparative example is indicated by a dashed line.

[0034] The mounting portion 260a is formed in the cylinder head 224 and provided around the opening 44a of the intake port 40 on the combustion chamber 34 side. The mounting portion 260a is formed in an annular shape surrounding the opening 44a. The mounting portion 260a is recessed, for example, on the side opposite the combustion chamber 34. The valve seat 262a is formed in an annular shape. The valve seat 262a is press-fitted into the mounting portion 260a. The valve seat 262a is configured so that the intake valve 26 (see FIG. 1) can be seated on it.

[0035] In the second comparative example, the central axis O4 of the mounting portion 260a is different from the central axis O3 of the intake valve guide press-fit hole 46a and the intake valve guide 48a. Also, the central axis O5 of the valve seat 162a is different from the central axis O3 of the intake valve guide press-fit hole 46a and the intake valve guide 48a.

[0036] Specifically, the central axis O4 of the mounting portion 260a is substantially equal to the central axis O5 of the valve seat 262a. The central axes O4 and O5 are located at positions shifted in parallel with the central axis O3 of the intake valve guide press-fit hole 46a and the intake valve guide 48a toward the opposite side of the exhaust port 42 (see FIG. 1). Similarly, the central axes O4 and O5 are located at positions offset in parallel with the central axis O3 of the intake valve guide press-fit hole 46a and the intake valve guide 48a toward the opposite side of the water jacket WJ.

[0037] In the cylinder heads 124, 224 of the first and second comparative examples, a thin-walled portion TP is formed between the intake port 40 and the mounting portion 160a, 260a. The inner diameter of the mounting portion 260a of the second comparative example is larger than the inner diameter of the mounting portion 160a of the first comparative example. Therefore, an inner diameter difference ΔL occurs between the mounting portion 260a of the second comparative example and the mounting portion 160a of the first comparative example.

[0038] Therefore, in the cylinder head 224 of the second comparative example, the area of ​​the thin-walled portion TP is enlarged by the amount of the inner diameter difference ΔL compared to the cylinder head 124 of the first comparative example. When the area of ​​the thin-walled portion TP is enlarged, a decrease in strength occurs in the portion of the cylinder head 224 between the intake port 40 and the mounting portion 260a.

[0039] Furthermore, in the cylinder head 224 of the second comparative example, if the mounting portion 260a is moved toward the combustion chamber 34 in order to increase the thickness of the thin-walled portion TP, the volume of the combustion chamber 34 may become smaller or it may become difficult to design the combustion chamber 34 in an ideal shape.

[0040] On the other hand, although the area of ​​the thin-walled portion TP in the first comparative example is smaller in inner diameter by the difference ΔL than the area of ​​the thin-walled portion TP in the second comparative example, the thickness of the thin-walled portion TP in the first comparative example is the same as the thickness of the thin-walled portion TP in the second comparative example, and there were cases where strength concerns arose in the area of ​​the cylinder head 124 between the intake port 40 and the mounting portion 160a.

[0041] Therefore, the cylinder head 24 of this embodiment is characterized in that the central axis of the mounting portion 60a is inclined with respect to the central axis of the intake valve guide press-fit hole 46a in order to increase the thickness of the thin-walled portion TP without moving the mounting portion 60a toward the combustion chamber 34.

[0042] FIG. 4 is a partially enlarged view of a portion of the cylinder head 24 according to this embodiment. FIG. 5 is a partially enlarged view of the area surrounding the valve seat 62a shown in FIG. 4. Note that in FIG. 5, the valve seat 62a is shown separated from the mounting portion 60a by a dashed line to facilitate explanation of the inner circumferential surface IC of the mounting portion 60a and the outer circumferential surface PS of the valve seat 62a. As can be seen from FIG. 5, when the valve seat 62a is press-fitted into the mounting portion 60a, the outer circumferential surface PS of the valve seat 62a contacts the inner circumferential surface IC of the mounting portion 60a, and the outer circumferential surface PS and the inner circumferential surface IC form substantially the same plane. As shown in FIGS. 4 and 5, in this embodiment, the central axis O6 of the mounting portion 60a is different from the central axis O3 of the intake valve guide press-fit hole 46a and the intake valve guide 48a. Furthermore, the central axis O7 of the valve seat 62a is different from the central axis O3 of the intake valve guide press-fit hole 46a and the intake valve guide 48a.

[0043] Specifically, the central axis O6 of the mounting portion 60a is substantially equal to the central axis O7 of the valve seat 62a. The central axes O6 and O7 are inclined at a predetermined angle θ with respect to the central axis O3 of the intake valve guide press-fit hole 46a and the intake valve guide 48a toward the opposite side of the exhaust port 42 (see FIG. 1). In other words, the central axis O6 of the mounting portion 60a is inclined at a predetermined angle θ toward the intake port 40 with respect to the central axis O3 of the intake valve guide press-fit hole 46a and the intake valve guide 48a. Similarly, the central axes O6 and O7 are inclined at a predetermined angle θ with respect to the central axis O3 of the intake valve guide press-fit hole 46a and the intake valve guide 48a toward the opposite side of the water jacket WJ.

[0044] The predetermined angle θ is set within an angular range between the central axis O3 and the central axis O8 of the intake port 40. In this embodiment, the angle between the central axes O6, O7 and the central axis O8 is larger than the angle between the central axes O6, O7 and the central axis O3. However, this is not limited thereto, and the angle between the central axes O6, O7 and the central axis O8 may be smaller than the angle between the central axes O6, O7 and the central axis O3. The closer the central axes O6, O7 are to the central axis O8, the more smoothly the intake air can be supplied to the combustion chamber 34. Therefore, it is preferable that the angle between the central axes O6, O7 and the central axis O8 is smaller, and it is preferable that the central axes O6, O7 are substantially equal to the central axis O8.

[0045] The larger the predetermined angle θ, the thicker the thin-walled portion TP. In other words, when the predetermined angle θ is set between the central axes O6, O7 and the central axis O3, the thickness of the thin-walled portion TP can be made larger than when the predetermined angle θ is not set. Thus, in this embodiment, the distance between the intake port 40 and the mounting portion 60a can be made larger than in the first and second comparative examples. Furthermore, since it is not necessary to shift the mounting portion 60a parallel to the combustion chamber 34 to thicken the thin-walled portion TP, a significant change in the combustion chamber shape can be avoided. In other words, in this embodiment, the thickness of the thin-walled portion TP can be made larger than the thickness of the thin-walled portion TP in the first and second comparative examples, and a decrease in the strength of the cylinder head 24 can be suppressed without being restricted by the combustion chamber shape.

[0046] Next, a method for forming the mounting portion 60a according to this embodiment will be described with reference to FIGS.

[0047] Fig. 6 is a partially enlarged view showing a part of the cylinder head 24 before the mounting portion 60a according to this embodiment is formed. Fig. 6 shows the stage after the cylinder head 24 according to this embodiment is cast and before the mounting portion 60a is formed. In Fig. 6, the shape of the cylinder head 124 according to the first comparative example before the mounting portion 160a is formed is shown by a dashed line.

[0048] As shown in Fig. 6, the cylinder head 24 of this embodiment has a protrusion 80 that protrudes further toward the combustion chamber 34 than the cylinder head 124 of the first comparative example. The protrusion 80 is formed around the intake port 40 on the opposite side to the water jacket WJ and the exhaust port 42 (see Fig. 1).

[0049] 7 is a partially enlarged view showing a part of the cylinder head 24 after the mounting portion 60a according to this embodiment is formed. In FIG. 7, the shape of the ribs of the mounting portion 160a of the first comparative example is indicated by a broken line.

[0050] As shown in Fig. 7, the cylinder head 24 of this embodiment is formed with a rib 90 that protrudes further toward the combustion chamber 34 than the rib of the mounting portion 160a of the first comparative example. In this embodiment, the provision of the protrusion 80 shown in Fig. 6 allows the rib 90 to be formed higher than the rib of the mounting portion 160a of the first comparative example. The rib 90 is formed when the protrusion 80 shown in Fig. 6 is machined to form the mounting portion 60a. The rib 90 is formed on the side of the mounting portion 60a opposite to the water jacket WJ and the exhaust port 42 (see Fig. 1).

[0051] The height of the inner wall of the mounting portion 60a is substantially uniform in the circumferential direction of the mounting portion 60a due to the formation of the rib 90. As shown in Fig. 7, the height H1 of the inner wall of the mounting portion 60a on the exhaust port 42 side is substantially equal to the height H2 of the side opposite the exhaust port 42.

[0052] In this way, the rib 90 is formed to protrude from at least a portion of the periphery of the mounting portion 60a on the surface facing the combustion chamber 34 so that the height of the inner wall of the mounting portion 60a is substantially uniform in the circumferential direction of the mounting portion 60a.

[0053] This allows the inner wall of the mounting portion 60a to abut against the entire periphery of the valve seat 62a when the valve seat 62a is press-fitted into the mounting portion 60a, preventing the valve seat 62a from being press-fitted with its central axis O7 inclined from the central axis O6 of the mounting portion 60a, and allowing the valve seat 62a to be easily press-fitted into the mounting portion 60a.

[0054] On the other hand, the height of the inner wall of the mounting portion 160a of the first comparative example is non-uniform around the circumference of the mounting portion 160a. As shown in FIG. 7, the height H1 of the inner wall of the mounting portion 160a on the exhaust port 42 side is greater than the height H3 of the inner wall on the opposite side from the exhaust port 42. Therefore, when press-fitting the valve seat 162a into the mounting portion 160a, it is difficult to abut the inner wall of the mounting portion 160a around the entire circumference of the valve seat 162a. As a result, the valve seat 162a is press-fitted with its central axis tilted from the central axis of the mounting portion 160a, making it difficult to press-fit the valve seat 162a into the mounting portion 160a.

[0055] Figure 8 is a partially enlarged view showing a portion of a cylinder head 324 according to a modified example. As shown in Figure 8, in this modified example, the central axis O9 of the mounting portion 360a is different from the central axis O3 of the intake valve guide press-fit hole 46a and the intake valve guide 48a. Furthermore, the central axis O10 of the valve seat 362a is different from the central axis O3 of the intake valve guide press-fit hole 46a and the intake valve guide 48a.

[0056] Specifically, the central axis O9 of the mounting portion 360a is substantially equal to the central axis O10 of the valve seat 362a. The central axes O9 and O10 are inclined by a predetermined angle θ toward the exhaust port 42 (see FIG. 1) with respect to the central axis O3 of the intake valve guide press-fit hole 46a and the intake valve guide 48a. In other words, the central axis O9 of the mounting portion 360a is inclined by the predetermined angle θ toward the water jacket WJ, which is opposite the intake port 40, with respect to the central axis O3 of the intake valve guide press-fit hole 46a and the intake valve guide 48a.

[0057] As a result, in this modification, the distance between the water jacket WJ and the mounting portion 360a can be increased compared to the above embodiment, and communication between the water jacket WJ and the mounting portion 360a can be prevented, which in turn prevents a decrease in strength of the portion of the cylinder head 324 between the water jacket WJ and the mounting portion 360a.

[0058] While the present invention has been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such embodiments. It is clear that those skilled in the art can conceive of various modifications and alterations within the scope of the claims, and it is understood that such modifications and alterations also fall within the technical scope of the present invention.

[0059] In the above embodiment and modified example, the central axes O6, O9 of the mounting portions 60a, 360a on the intake port 40 side are inclined at a predetermined angle θ with respect to the central axis O3 of the intake valve guide 48a. However, this is not limited to this, and the central axis of the mounting portion 60b on the exhaust port 42 side may be inclined at a predetermined angle θ with respect to the central axis of the exhaust valve guide 48b. [Explanation of symbols]

[0060] TP thin section WJ Water Jacket 1 vehicle 10 Engine 20 Cylinder block 22 Piston 24 Cylinder head 26 Intake valve 26a Head part (valve body) 26b stem 28 Exhaust valve 28a Umbrella section 28b stem 30 cylinders 32 Connecting rod 34 Combustion chamber 40 intake port 42 Exhaust port 44a opening 44b opening 46a Intake valve guide press-fit hole 46b Exhaust valve guide press-fit hole 48a Intake valve guide 48b Exhaust valve guide 50 intake camshaft 50a Cam 52 Exhaust camshaft 52a Cam 60a attachment part 60b Mounting part 62a valve seat 62b valve seat 80 protrusions 90 Ribs 324 cylinder head 360a attachment part

Claims

1. A cylinder head, a port formed through the cylinder head; a mounting portion recessed around the port on the combustion chamber side surface of the cylinder head; a valve seat that is press-fitted into the mounting portion and on which a valve element of the valve can be seated; a valve guide press-fit hole formed through the cylinder head; a valve guide that is press-fitted into the valve guide press-fit hole and through which the stem of the valve is inserted; Equipped with a central axis of the mounting portion is inclined with respect to a central axis of the valve guide press-fit hole, an angle between the central axis of the port and the central axis of the mounting portion is larger than an angle between the central axis of the mounting portion and the central axis of the valve guide press-fit hole; engine.

2. a central axis of the mounting portion is inclined toward the port side with respect to a central axis of the valve guide press-fit hole; 10. The engine of claim 1.

3. The valve is an intake valve.

3. An engine according to claim 1 or 2.

4. A cylinder head, a port formed through the cylinder head; a mounting portion recessed around the port on the combustion chamber side surface of the cylinder head; a valve seat that is press-fitted into the mounting portion and on which a valve element of the valve can be seated; a valve guide press-fit hole formed through the cylinder head; a valve guide that is press-fitted into the valve guide press-fit hole and through which the stem of the valve is inserted; Equipped with a cavity separate from the port is formed inside the cylinder head at a position opposite the port with respect to the central axis of the valve guide press-fit hole, a central axis of the mounting portion is inclined toward the cavity on the opposite side to the port with respect to a central axis of the valve guide press-fit hole; engine.

5. A cylinder head, a port formed through the cylinder head; a mounting portion recessed around the port on the combustion chamber side surface of the cylinder head; a valve seat that is press-fitted into the mounting portion and on which a valve element of the valve can be seated; a valve guide press-fit hole formed through the cylinder head; a valve guide that is press-fitted into the valve guide press-fit hole and through which the stem of the valve is inserted; a rib formed on the combustion chamber side surface of the cylinder head so as to protrude from at least a portion of the periphery of the mounting portion, so that the height of an inner wall of the mounting portion is uniform in the circumferential direction of the mounting portion; Equipped with The central axis of the mounting portion is inclined with respect to the central axis of the valve guide press-fit hole. engine.

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