EP3214295A1

EP3214295A1 - Cylinder head and internal combustion engine equipped with same

Info

Publication number: EP3214295A1
Application number: EP15855005.3A
Authority: EP
Inventors: Daichi Abe; Takashi Satake; Koichi Tokura; Nobuo Iwamuro
Original assignee: Aichi Machine Industry Co Ltd
Current assignee: Aichi Machine Industry Co Ltd
Priority date: 2014-10-27
Filing date: 2015-03-30
Publication date: 2017-09-06
Also published as: WO2016067653A1; EP3214295A4; CN107076049B; JPWO2016067653A1; MX2017005211A; CN107076049A

Abstract

A technique capable of improving a sealing characteristic of a combustion chamber is provided. A slanted wall portion (38) connects a portion of a combustion-chamber sealing surface portion (29a) extending on one end side (side wall (26a) side) in a combustion-chambers arranging direction with a side wall (26a) of a cylinder head (20). Thus, the side wall (26a) can receive, via the slanted wall portion (38), an explosion load acting on the combustion-chamber sealing surface portion (29a) of the combustion chamber. In other words, a component of the explosion load acting on the combustion-chamber sealing surface portion (29a), which acts in a direction (upper direction in Fig. 5) to separate the cylinder head (20) from the cylinder block (6), can be decreased. Thus, deformation of the combustion-chamber sealing surface portion (29a) of the combustion chamber can be effectively decreased. As a result, the sealing characteristic of the combustion chamber (CC) can be improved.

Description

Technical Field

The present invention relates to a cylinder head capable of decreasing deformation of a combustion-chamber sealing surface portion formed around the combustion chamber, and an internal combustion engine equipped with such a cylinder head.

Background Art

This type of cylinder head that has been proposed so far includes an upper deck defining a valve mechanism chamber, a lower deck defining a combustion chamber, a side wall formed in a rectangular frame shape to surround the upper and lower decks, and a slanted wall that connects the side wall with a portion of the lower deck corresponding to a center of the combustion chamber in a slanting manner. The cylinder head is fastened to a cylinder block with head fastening bolts inserted from the upper deck side (see, e.g., Patent Literature 1).
Such a cylinder head effectively decreases deformation of the center part of the combustion chamber by transmitting explosion load, which acts on the center part of the combustion chamber, to fastening portions of the head fastening bolts in the upper deck via the side wall from the slanted wall, and bearing the explosion load by bolt-fastening force acting on the fastening portions of the head fastening bolts.

Citation List

Patent Literature

Patent Literature 1: Japanese Examined Utility Model Publication H3-13547 Y

Summary of Invention

Technical Problem

The cylinder head described above can effectively decrease deformation of the center part of the combustion chamber. However, deformation of a mating surface of the combustion chamber between the cylinder head and the cylinder block around the combustion chamber, that is, deformation of a combustion-chamber sealing surface portion has not been considered. Deformation of the combustion-chamber sealing surface portion causes deterioration of the sealing characteristic of the combustion chamber. The sealing characteristic of the combustion chamber is typically provided by bolt fastening force of the head fastening bolts disposed on the combustion-chamber sealing surface portion around the combustion chamber. Such bolt fastening force, however, does not effectively act on the entire region of the combustion-chamber sealing surface portion, leaving room for improvement of the sealing characteristic.
The present invention has been made in view of the above, and it is an object of the present invention to provide a technique to achieve improved sealing characteristic of a combustion chamber.

Solution to Problem

A cylinder head and an internal combustion engine equipped with the cylinder head adopt the following means to achieve the above object.
According to a preferred mode of the present invention, a cylinder head includes an upper deck, a lower deck, a side wall, and a slanted wall. The upper deck is configured to define a valve mechanism chamber. The lower deck is configured to define a combustion chamber, and include a combustion-chamber sealing surface portion provided around the combustion chamber. The side wall is formed in a rectangular frame shape surrounding the upper deck and the lower deck. The slanted wall connects the side wall with at least a portion of an inter-bolt-hole sealing surface portion of the combustion-chamber sealing surface portion, the inter-bolt-hole sealing surface portion extending between a first bolt insert hole and a second bolt insert hole disposed along the circumferential direction of the combustion chamber.
According to the embodiment of the present invention, at least a portion of the inter-bolt-hole sealing surface portion on which the bolt fastening force hardly acts is connected to the side wall via the slanted wall. This structure allows the side wall to receive the explosion load acting on the inter-bolt-hole sealing surface portion via the slanted wall. Thus, the deformation of the inter-bolt-hole sealing surface portion can be effectively decreased. As a result, an improved sealing characteristic of the combustion chamber can be achieved.
According to another mode of the present invention, the inter-bolt-hole sealing surface portion of the cylinder head has an edge portion provided adjacent to the first and second bolt insert holes. The slanted wall connects at least a portion of the edge portion located at the farthest distance away from the centers of the first and second bolt insert holes with the side wall.
In the present mode, the slanted wall connects the side wall with at least the portion of the edge portion of the inter-bolt-hole sealing surface portion located at the farthest distance away from the centers of the first and second bolt insert holes. That is, the slanted wall connects the side wall with the portion of the inter-bolt-hole sealing surface portion on which the bolt fastening force is most unlikely to act and which, therefore, is easily deformed. Thus, the deformation of the inter-bolt-hole sealing surface portion can be decreased effectively.
According to still another mode of the present invention, the cylinder head includes an imaginary connecting line that connects between centers of the first and second bolt insert holes. The edge portion is formed substantially in parallel with the imaginary connecting line.
According to the present mode, the explosion load acting on the inter-bolt-hole sealing surface portion can be transmitted easily and uniformly to the slanted wall. Thus, the deformation of the inter-bolt-hole sealing surface portion can be effectively decreased.
According to still another mode of the present invention, the slanted wall of the cylinder head connects the entire region of the edge portion with the side wall.
According to the present mode, the entire region of the edge portion is connected to the side wall via the slanted wall, thus decreasing the deformation of the inter-bolt-hole sealing surface portion more effectively.
According to still another mode of the present invention, the lower deck of the cylinder head includes first and second boss portions in which first and second bolt insert holes are formed respectively. The slanted wall is connected to the first and second boss portions.
According to the present mode, the slanted wall is connected to the first and second boss portions, allowing the bolt fastening force to act on the slanted wall. Thus, the deformation of the inter-bolt-hole sealing surface portion can be decreased more effectively by both the slanted wall and the bolt fastening force.
According to still another mode of the present invention, the side wall of the cylinder head includes an attaching surface portion to which peripheral parts necessary for operating the internal combustion engine are attached. The slanted wall is connected to the lower end portion of the attaching surface portion of the side wall.
In the present invention, "peripheral parts" typically correspond to a water outlet capable of distributing cooling water to a radiator or a heater to cool the internal combustion engine including the cylinder head, and also preferably include auxiliary components, such as an alternator or a starter motor.
The peripheral parts are attached in a cantilevered manner to the attaching surface portion, causing bending force which is generated by self-weight or vibration of the peripheral parts to act on the lower end portion of the attaching surface portion. In the present mode, the lower end portion of the attaching surface portion is connected to the inter-bolt-hole sealing surface portion via the slanted wall, thus enabling the inter-bolt-hole sealing surface portion to receive the bending force via the slanted wall. This improves the rigidity of the attaching surface portion, and decreases the deformation of the attaching surface portion effectively.
According to a preferred mode of the present invention, an internal combustion engine includes the cylinder head according to any one of the modes described above, a cylinder block including cylinder bores, pistons configured to slide in the cylinder bores, and a crankshaft connected to the pistons. The internal combustion engine generates reciprocating motion of the pistons by combustion pressure generated in the combustion chamber, and translates the reciprocating motion of the pistons to rotary motion of a crankshaft to provide output power.
The present invention includes the cylinder head according to any one of the modes described above, so that an effect similar to the effect achieved by the cylinder head of the present invention can be achieved. For example, the effect of effectively decreasing the deformation of the inter-bolt-hole sealing surface portion and improving the sealing characteristic of the combustion chamber can be achieved.

Advantageous Effects of Invention

The present invention can achieve improved sealing characteristic of the combustion chamber.

Brief Description of Drawings

Fig. 1 is a schematic view of an internal combustion engine 1 on which a cylinder head 20 according to an embodiment of the present invention is mounted.
Fig. 2 is a cross-sectional view of the internal combustion engine 1 on which the cylinder head 20 according to the embodiment of the present invention is mounted.
Fig. 3 illustrates the cylinder head 20 according to the embodiment of the present invention when seen from the right side of Fig. 1.
Fig. 4 is a view seen from a direction of an arrow V of Fig. 3.
Fig. 5 is a cross-sectional view cut along line B-B of Fig. 3.
Fig. 6 is a cross-sectional view cut along line C-C of Fig. 4.
Fig. 7 is a cross-sectional view cut along line D-D of Fig. 4.
Fig. 8 illustrates a cylinder head 120 of a modification when seen from a lower deck 24 side.

Description of Embodiment

The best mode for carrying out the invention will be described below by referring to an embodiment.

Embodiment

An internal combustion engine 1 on which a cylinder head 20 according to an embodiment of the present invention is mounted includes, as illustrated in Fig. 1, the cylinder head 20 according to the embodiment of the present invention, a rocker cover 2 attached to the top of the cylinder head 20, a water outlet 4 attached to the side of the cylinder head 20, a cylinder block 6 attached to the bottom of the cylinder head 20, an upper oil pan 8 attached to the bottom of the cylinder block 6, and a lower oil pan 10 attached to the bottom of the upper oil pan 8.
In the embodiment, as illustrated in Fig. 2, the internal combustion engine 1 is configured as an in-line four-cylinder engine in which four cylinders are arranged in-line. Combustion pressure generated in combustion chambers CC, which are described later, causes reciprocating motion of pistons P which is translated to rotary motion of a crankshaft CS to provide output power. For convenience of explanation, the rocker cover 2 side or the upper side of Fig. 1 is regarded as an upper direction or upper side, while the lower oil pan 10 side or the lower side of Fig. 1 is regarded as a lower direction or lower side in the present embodiment.
The cylinder head 20 includes an upper deck 22, a lower deck 24, and a side wall 26, as illustrated in Fig. 2. The side wall 26 is connected to the upper deck 22 and the lower deck 24, while outlining the cylinder head 20. The cylinder head 20 is fixed to the cylinder block 6 by fastening head fastening bolts which are not illustrated.
A valve mechanism chamber VMC for accommodating and disposing intake and exhaust camshafts, intake and exhaust valves, valve lifters, and the like is formed at an upper portion of the cylinder head 20 above the upper deck 22. The valve mechanism chamber VMC is an example constituent component of the embodiment corresponding to a "valve mechanism chamber" of the present invention.
The lower deck 24 includes, as illustrated in Fig. 4, a combustion-chamber constituting recess 24a that constitutes a part of a combustion chamber CC, and a sealing surface portion 29 disposed around the combustion-chamber constituting recess 24a. Four combustion-chamber constituting recesses 24a are arranged in-line.
The combustion chamber CC includes the combustion-chamber constituting recess 24a, a cylinder bore 62 formed in the cylinder block 6 which is described later, and an upper surface of a piston P accommodated in the cylinder bore 62. The sealing surface portion 29 includes a combustion-chamber sealing surface portion 29a formed substantially concentrically with the combustion chamber CC, as illustrated in Fig. 4.
An inter-bolt-hole sealing surface portion 30a extending between a pair of bolt insert holes 32 (hereinafter referred to as endmost-row bolt insert holes 132), which are disposed on one end side (side wall 26a side, upper side of Fig. 4) of the combustion-chamber sealing surface portion 29a in a combustion-chamber arranging direction, has an edge portion 30a', as illustrated in Fig. 4.
The edge portion 30a' is located, as illustrated in Fig. 4, on the side opposite to the combustion-chamber constituting recesses 24a across an imaginary connecting line VCL that connects between the centers of the pair of endmost-row bolt insert holes 132. The edge portion 30a' is formed in a circular-arc shape to be part of a circle around the center of the combustion-chamber constituting recess 24a.
The cylinder head 20 includes a plurality of bolt boss portions 34 are formed, as illustrated in Fig. 4. Bolt insert holes 32 are formed respectively in the bolt boss portions 34 and the head fastening bolts (not illustrated) described above are inserted respectively through the bolt boss portions 34. The bolt insert holes 32 pierces between the upper deck 22 and the lower deck 24.
The bolt boss portions 34 are also disposed on the outer periphery of the combustion-chamber sealing surface portion 29a, and connected integrally to the combustion-chamber sealing surface portion 29a. Two pairs of bolt insert holes 32 are disposed respectively on the both sides across each combustion chamber CC in a direction in which the combustion chambers are arranged, and a total of four bolt insert holes 32 are disposed at substantially equal intervals (90-degree intervals) along a circumferential direction of the combustion chamber CC.
The pair of the bolt insert holes 32 disposed at positions corresponding to an in-between part of the adjacent combustion chambers CC are shared by the adjacent combustion chambers CC. In the present embodiment, the cylinder head 20 includes four combustion chambers CC, so that five pairs of bolt insert holes 32, i.e. a total of ten bolt insert holes 32, are disposed in the combustion-chamber arranging direction on the sealing surface portion 29a of the combustion chamber. The bolt insert holes 32 are example constituent components corresponding to a "first bolt insert hole" and a "second bolt insert hole" of the present invention. The bolt boss portions 34 are example constituent components corresponding to a "first boss portion" and a "second boss portion" of the present invention.
As illustrated in Fig. 5, a water jacket WJ for the cylinder head is formed between the upper deck 22 and the lower deck 24, in which cooling water for cooling the cylinder head 20 particularly around the combustion chambers CC flows. The water jacket WJ for the cylinder head has a water jacket outlet 36.
The water jacket outlet 36 is opened, as illustrated in Figs. 3 and 5, in a side wall 26a of the side wall 26 of the cylinder head 20, which is disposed on one end side (left side of Fig. 2, right side of Fig. 5) in the combustion-chamber arranging direction. An attaching surface portion 14 for attaching the water outlet 4 is formed, as illustrated in Fig. 3, around the water jacket outlet 36 of the side wall 26a of the cylinder head 20.
A slanted wall portion 38 that connects the side wall 26a with the combustion- chamber sealing surface portion 29a in a slanted manner is formed in the cylinder head 20, as illustrated in Figs. 3 to 7. Specifically, the slanted wall portion 38 connects the edge portion 30a' of the inter-bolt-hole sealing surface portion 30a with the lower end portion of the attaching surface portion 14 of the side wall 26a. The slanted wall portion 38 is configured, as illustrated in Figs. 3 and 4, to connect the side wall 26a with the combustion-chamber sealing surface portion 29a in the entire region of the edge portion 30a' of the inter-bolt-hole sealing surface portion 30a.
The slanted wall portion 38 is also connected to the pair of bolt boss portions 34 in which a pair of endmost-row bolt insert holes 132 are formed respectively, as illustrated in Figs. 4, 6, and 7. Namely, the slanted wall portion 38 is connected to the combustion- chamber sealing surface portion 29a in the region from the one bolt boss portion 34, in which the one endmost-row bolt insert holes 132 is formed, to the other bolt-boss portion 34, in which the other endmost-row bolt insert hole 132 is formed, via the inter-bolt-hole sealing surface portion 30a.
The slanted wall portion 38 connecting the entire region of the inter-bolt-hole sealing surface portion 30a with the lower end portion of the attaching surface portion 14 of the side wall 26a is an example structure corresponding to a "slanted wall connecting the entire region of an inter-bolt-hole sealing surface portion with the side wall" in the present invention. The slanted wall portion 38 being connected to the pair of bolt boss portions 34 is an example structure corresponding to a "slanted wall being connected to first and second boss portions" in the present invention. The slanted wall portion 38 is an example constituent component corresponding to a "slanted wall" of the present invention. The pair of endmost-row bolt insert holes 132 is an example constituent component corresponding to a "first bolt insert hole" and a "second bolt insert hole" of the present invention.
The water outlet 4 is attached to the attaching surface portion 14 formed in the side wall 26a of the cylinder head 1 in a cantilevered manner, as illustrated in Fig. 1. The water outlet 4 is part of a cooling water channel and distributes cooling water discharged from the water jacket outlet 36 to a radiator or heater (not illustrated).
Next, an operation of the cylinder head 20 configured as described above according to the present embodiment, or especially an operation of the slanted wall portion 38 is described. Upon start of the internal combustion engine 1, on which the cylinder head 20 according to the present embodiment is mounted, a mixed gas of air and fuel ignites in the combustion chamber CC to generate combustion explosion.
The cylinder head 20 receives force (hereinafter referred to as explosion load) by the combustion explosion in a direction away from the cylinder block 6. The cylinder head 20, however, is fastened to the cylinder block 6 with fastening bolts, so that the explosion load actually causes deformation of the sealing surface portion 29, or especially the combustion-chamber sealing surface portion 29a, which is the surface attached to the cylinder block 6.
In the combustion-chamber sealing surface portion 29a, axial force of the fastening bolts effectively acts on an area in the vicinity of the bolt insert holes 32 through which the fastening bolts are inserted respectively. Thus, the explosion load acting on the combustion-chamber sealing surface portion 29a can be effectively covered by the axial force of the fastening bolts, decreasing the deformation of the sealing surface portion 29a of the combustion chamber.
Meanwhile, the axial force of the fastening bolts hardly acts effectively on the portion between the bolt insert holes 32 of the combustion-chamber sealing surface portion 29a, so that deformation easily occurs on the combustion-chamber sealing surface portion 29a. In the present embodiment, the slanted wall portion 38 connects the lower end portion of the attaching surface portion 14 of the side wall 26a with the entire region of the inter-bolt-hole sealing surface portion 30a of the combustion-chamber sealing surface portion 29a surrounding the combustion chamber CC disposed at one end (side wall 26a side, or upper side of Fig. 4) in the combustion-chambers arranging direction, the inter-bolt-hole sealing surface portion 30a extending between the pair of endmost-row bolt insert holes 132 disposed on one end side (side wall 26a side, or upper side of Fig. 4) in the combustion-chambers arranging direction.
Thus, the side wall 26a can receive the explosion load acting on the inter-bolt-hole sealing surface portion 30a via the slanted wall portion 38. In other words, a component of the deformation caused by the explosion load acting on the inter-bolt-hole sealing surface portion 30a, which acts in a direction (upper direction in Fig. 5) to separate the cylinder head 20 from the cylinder block 6, can be decreased. As a result, the deformation of the inter-bolt-hole sealing surface portion 30a can be decreased effectively.
Since the slanted wall portion 38 is also connected to the pair of bolt boss portions 34 in which the pair of endmost-row bolt insert holes 132 are formed respectively, the axial force of the fastening bolts can be exerted on the inter-bolt-hole sealing surface portion 30a via the slanted wall portion 38. Thus, the deformation of the inter-bolt-hole sealing surface portion 30a can further be decreased effectively by both the side wall 26a and the axial force of the fastening bolts.
Meanwhile, vibration is generated by reciprocating motion of the pistons P during the operation of the internal combustion engine 1, and the vibration also acts on the water outlet 4. The water outlet 4 is attached to the attaching surface portion 14 of the cylinder head 20 in the cantilevered manner, so that a bending force due to the vibration acts on the attaching surface portion 14.
In addition to the bending force due to the vibration, the attaching surface portion 14 also receives a bending force generated by self-weight of the water outlet 4. In the present embodiment, however, the slanted wall portion 38 connects the lower end portion of the attaching surface portion 14 with the sealing surface portion 29a of the combustion chamber. Thus, the tension force or compression force caused by the bending force acting on the lower end portion of the attaching surface portion 14 can be received by the sealing surface portion 29a of the combustion chamber via the slanted wall portion 38. This improves the rigidity of the attaching surface portion 14, and decreases the deformation of the attaching surface portion 14 effectively.
In the present embodiment, the slanted wall portion 38 connects the combustion-chamber sealing surface portion 29a with the side wall 26a over the entire region of the edge portion 30a' of the inter-bolt-hole sealing surface portion 30a. This structure, however, may be changed. For example, the slanted wall portion 38 may connect the combustion-chamber sealing surface portion 29a with the side wall 26a in at least a part of the edge portion 30a' of the inter-bolt-hole sealing surface portion 30a.
In this case, as illustrated in Fig. 4, the slanted wall portion 38 preferably connects the combustion-chamber sealing surface portion 29a with the side wall 26a at a portion FP located at the farthest distance away from the centers of the pair of the endmost-row bolt insert holes 132 in the edge portion 30a' of the inter-bolt-hole sealing surface portion 30a.
In this structure, the slanted wall portion 38 can be minimized, while the deformation of the portion at which deformation easily occurs, because the axial force of the fastening bolts is most unlikely be exerted, can be effectively decreased in the inter-bolt-hole sealing surface portion 30a.
The portion FP located at the farthest distance away from the centers of the pair of the endmost-row bolt insert holes 132 in the edge portion 30a' of the inter-bolt-hole sealing surface portion 30a is an example constituent component corresponding to a "portion located at the farthest distance away from the centers of at least first and second bolt insert holes in an edge portion" in the present invention.
In the present embodiment, the slanted wall portion 38 is also connected to the pair of bolt boss portions 34 in which the pair of endmost-row bolt insert holes 132 are formed respectively. However, the slanted wall portion 38 would not be connected to the pair of endmost-row bolt boss portions 34 in which the pair of endmost-row bolt insert holes 132 are formed respectively when the slanted wall portion 38 connects the combustion-chamber sealing surface portion 29a with the side wall 26a in at least a part of the edge portion 30a' of the inter-bolt-hole sealing surface portion 30a.
In the present embodiment, the slanted wall portion 38 connects the combustion-chamber sealing surface portion 29a with the side wall 26a only in the inter-bolt-hole sealing surface portion 30a extending between the pair of endmost-row bolt insert holes 132 of the sealing surface portion 29a of the combustion chamber. However, the configuration of the slanted wall portion 38 is not limited to this. For example, the slanted wall portion may also be provided between other bolt insert holes 32 disposed in the combustion-chamber sealing surface portion 29a. Thus, the slanted wall portion may connect the other inter-bolt-hole sealing surface portion of the combustion-chamber sealing surface portion 29a, which extends between other bolt insert holes 32, with the respective side wall 26 corresponding to the other inter-bolt-hole sealing surface portion.
In the present embodiment, the combustion-chamber sealing surface portion 29a is connected to the lower end portion of the attaching surface portion 14 for attaching the water outlet 4 to the cylinder head 20 via the slanted wall portion 38. However, the sealing surface portion 29a of the combustion chamber may be connected to the center portion or the upper end portion of the attaching surface portion 14.
In the present embodiment, the combustion-chamber sealing surface portion 29a is connected to the attaching surface portion 14 for attaching the water outlet 4 to the cylinder head 20 via the slanted wall portion 38. However, the configuration of the combustion-chamber sealing surface portion 29a may be changed. For example, the combustion-chamber sealing surface portion 29a may be connected to the attaching surface for attaching peripheral parts other than the water outlet 4, such as auxiliary components including, for example, an alternator, a starter motor, and an oil filter, which are necessary for operating the internal combustion engine 1, to the cylinder head 20 via the slanted wall portion 38. Further, the combustion-chamber sealing surface portion 29a may not be connected to the attaching surface of the peripheral parts including the water outlet 4 when the sealing surface portion 29a is connected to the side wall 26, 26a via the slanted wall portion 38.
In the present embodiment, the edge portion 30a' is formed in a circular arc shape to form a part of a circle centered at the center of the combustion-chamber constituting recess 24a. However, the configuration of the edge portion 30a' may be changed. For example, as in a modification of a cylinder head 120 illustrated in Fig. 8, an edge portion 130a' may be formed substantially in parallel with the imaginary connecting line VCL.
This structure facilitates uniform transfer of the explosion load, which acts on the inter-bolt-hole sealing surface portion 30a, to the slanted wall portion 38, thus decreasing the deformation of the inter-bolt-hole sealing surface portion more effectively.
The present embodiment is an example mode for carrying out the present invention. Therefore, the present invention is not limited to the structure of the present embodiment.

Reference Signs List

1: Internal combustion engine (Internal combustion engine)
2: Rocker cover
4: Water outlet (Water outlet)
6: Cylinder block (Cylinder block)
8: Upper oil pan
10: Lower oil pan
14: Attaching surface portion (Attaching surface portion)
20: Cylinder head (Cylinder head)
22: Upper deck (Upper deck)
24: Lower deck (Lower deck)
24a: Combustion-chamber constituting recess
26: Side wall (Side wall)
26a: Side wall (Side wall)
29: Sealing surface portion
29a: Combustion-chamber sealing surface portion (Combustion-chamber sealing surface portion of combustion chamber)
30a: Inter-bolt-hole sealing surface portion (Inter-bolt-hole sealing surface portion)
30a': Edge portion (Edge portion)
32: Bolt insert hole (First bolt insert hole, Second bolt insert hole)
34: Bolt boss portion (First boss portion, Second boss portion)
36: Water jacket outlet
38: Slanted wall portion (slanted wall)
62: Cylinder bore (Cylinder bore)
130a': Edge portion (Edge portion)
132: Endmost-row bolt insert holes (First bolt insert hole, Second bolt insert hole)
CC: Combustion chamber (Combustion chamber)
VMC: valve mechanism chamber (valve mechanism chamber)
P: Piston (Piston)
WJ: Water jacket for cylinder head
FP: Portion located at the farthest distance away from centers of a pair of endmost-row bolt insert holes 132
VLC: Imaginary connecting line (Imaginary connecting line)

Claims

A cylinder head, comprising:
an upper deck configured to define a valve mechanism chamber;

a lower deck configured to define a combustion chamber and include a combustion-chamber sealing surface portion formed around the combustion chamber;

a side wall configured in a rectangular frame shape to surround the upper deck and the lower deck; and

a slanted wall connecting the side wall with at least a portion of an inter-bolt-hole sealing surface portion of the combustion-chamber sealing surface portion, the inter-bolt-hole sealing surface portion extending between a first bolt insert hole and a second bolt insert hole disposed along a circumferential direction of the combustion chamber.
The cylinder head according to claim 1, wherein
the inter-bolt-hole sealing surface has an edge portion disposed adjacent to the first and second bolt insert holes, and
the slanted wall connects the side wall with at least a portion of the edge portion located at the farthest distance away from centers of the first and the second bolt insert holes.
The cylinder head according to claim 2, wherein
an imaginary line connecting the centers of the first and second bolt insert holes is provided, and
the edge portion is substantially in parallel with the imaginary line.
The cylinder head according to claim 2 or 3, wherein
the slanted wall connects the entire region of the edge portion with the side wall.
The cylinder head according to any one of claims 1 to 4, wherein
the lower deck includes first and second boss portions in which the first and second bolt insert holes are formed respectively, and
the slanted wall is connected to the first and second boss portions.
The cylinder head according to any one of claims 1 to 5, wherein
the side wall includes an attaching surface portion for attaching peripheral parts necessary to operate an internal combustion engine, and
the slanted wall is connected to the lower end portion of the attaching surface portion of the side wall.
An internal combustion engine, comprising:
the cylinder head according to any one of claims 1 to 6;

a cylinder block including a cylinder bore;

a piston configured to slide in the cylinder bore; and

a crankshaft connected to the piston, wherein

the internal combustion engine is configured to cause reciprocating motion of the piston by a combustion pressure generated in the combustion chamber, and provides output power by translating the reciprocating motion of the piston to rotary motion of the crankshaft.