JP7218685B2 - Internal combustion engine structure - Google Patents

Description

The present invention relates to internal combustion engine construction.

In an internal combustion engine (engine), a cylinder head is generally fixed to a cylinder block with head bolts, and a head gasket is placed between the lower end surface of the cylinder head and the upper end surface of the cylinder block to ensure airtightness in the combustion chamber. is sandwiched.

In this internal combustion engine, due to thermal expansion of parts around the combustion chamber such as the cylinder head, cylinder block, head gasket, head bolt, etc. due to heat generated in the combustion chamber, and pressure rise in the combustion chamber due to combustion, parts around the combustion chamber A large stress is generated.

Further, the temperature on the exhaust port side of the internal combustion engine becomes much higher than the temperature on the intake port side, and the temperature on the cylinder head and cylinder block also becomes higher on the exhaust port side than on the intake port side. As a result, in the cylinder head and cylinder block, the amount of thermal expansion of the parts around the combustion chamber on the exhaust port side is greater than that on the intake port side, and the stress around the combustion chamber on the exhaust port side is greater than the stress on the parts around the combustion chamber on the intake port side. stresses in the parts of Due to the difference in stress between the intake port side and the exhaust port side, parts around the combustion chamber (for example, the head gasket) may be deformed or unevenly worn. Various methods have been proposed to avoid such deformation and uneven wear of parts around the combustion chamber.

For example, US Pat. No. 6,200,000 describes an engine in which a rigid reinforcing ring is provided on the upper circumferential edge of the cylinder. This reinforcing ring prevents the upper circumferential edge of the cylinder from deforming unevenly due to the pressure generated by thermal expansion and combustion, thereby avoiding deformation and uneven wear of parts around the combustion chamber. ing.

Further, in Patent Document 2, the tightening axial force (tightening torque) of the head bolt on the intake port side to the cylinder block when the head bolt is cold tightened (when the internal combustion engine is at room temperature) is calculated as the tightening axial force (torque) on the exhaust port side. A cylinder head fastening structure (equivalent to an internal combustion engine structure) in which the force is set larger than the force is described. In this cylinder head fastening structure, the tightening axial force on the intake port side during cold tightening is set to be greater than the tightening axial force on the exhaust port side. The tightening axial force is made almost the same, and the surface pressure (pressure) on the mating surfaces of the cylinder head and cylinder block is made uniform, thereby avoiding deformation and uneven wear of parts around the combustion chamber.

Further, Patent Document 3 describes a cylinder head fixing structure (corresponding to an internal combustion engine structure) in which the linear expansion coefficient of the head bolt on the exhaust port side is set larger than the linear expansion coefficient of the head bolt on the intake port side. there is This cylinder head fixing structure absorbs the difference in the amount of displacement between the head bolt on the exhaust port side and the head bolt on the intake port side due to the temperature difference between the exhaust port side and the intake port side, and the deformation of parts around the combustion chamber. and uneven wear are avoided.

Japanese Patent Application Laid-Open No. 2003-193907 JP-A-62-101871 Japanese Utility Model Laid-Open No. 3-127061

However, in the engine disclosed in Patent Document 1, it is necessary to attach a reinforcing ring above the cylinder, which complicates the structure.

In addition, in the cylinder head fastening structure described in Patent Literature 2, the figure shows head bolts having the same shape on the exhaust port side and the intake port side. For this reason, the operator tightens the head bolt on the intake port side with the tightening axial force for the exhaust port side, or the head bolt for the exhaust port side with the tightening axial force for the intake port side. There is a possibility of incorrect assembly.

Further, in the cylinder head fixing structure described in Patent Document 3, the figure shows head bolts having the same shape on the exhaust port side and the intake port side. For this reason, an operator may mistake the head bolt for the exhaust port side and fix it to the cylinder block on the intake port side, or mistake the head bolt for the intake port side and fix it to the cylinder block on the exhaust port side. There is a possibility of

The present invention has been invented in view of the above points, and the stress distribution (pressure distribution) on the intake port side and the stress distribution (pressure distribution) on the exhaust port side in the gasket sandwiched between the cylinder block and the cylinder head. ), has a simple structure, and is capable of preventing erroneous assembly.

In order to solve the above-mentioned problems, a first invention has a gasket sandwiched between an upper end surface of a cylinder block and a lower end surface of a cylinder head, and the cylinder block and the cylinder head are fixed to a predetermined torque using a plurality of bolts. In an internal combustion engine structure having a single cylinder or a plurality of cylinders, the plurality of bolts includes a plurality of intake side bolts mounted on the intake side and a plurality of bolts mounted on the exhaust side. and a plurality of exhaust side bolts, and in a single cylinder or in each of a plurality of cylinders, the exhaust side fastening distance, which is the distance from the center axis of the cylinder to the nearest exhaust side bolt, is the length of the cylinder. The internal combustion engine structure is set longer than the intake side fastening distance, which is the distance from the central axis to the nearest intake side bolt.

Next, in a second aspect of the invention, a gasket is sandwiched between the upper end surface of the cylinder block and the lower end surface of the cylinder head, and the cylinder block and the cylinder head are held together with a predetermined torque using a plurality of bolts. The crushing fixed internal combustion engine structure, wherein the plurality of bolts are divided into a plurality of intake side bolts mounted on the intake side and a plurality of exhaust side bolts mounted on the exhaust side. , the distance between the exhaust-side bolts, which is the distance between the adjacent two of the exhaust-side bolts, is set longer than the distance between the intake-side bolts, which is the distance between the adjacent two of the intake-side bolts. , internal combustion engine structure.

According to the first invention, when the tightening torques of the plurality of exhaust-side bolts and the plurality of intake-side bolts are set to be the same, the pressure (stress) on the gasket of the exhaust-side bolts when the internal combustion engine is stopped (at room temperature) ) can be made smaller than the pressure (stress) on the gasket at the intake side bolt. This allows for the difference between the pressure (stress) on the gasket at the exhaust side bolt and the pressure (stress) on the gasket at the intake side bolt during internal combustion engine operation (at high temperatures) in a single cylinder or in each of a plurality of cylinders. can be further reduced. Therefore, it is possible to avoid deformation and uneven wear of parts around the combustion chamber (for example, head gasket). In addition, since there is no need to install a separate mechanism just by changing the arrangement of the bolts on the exhaust side, deformation and uneven wear of parts around the combustion chamber can be avoided with a simple structure, and erroneous assembly can be prevented.

According to the second invention, when the tightening torques of the plurality of exhaust-side bolts and the plurality of intake-side bolts are the same, the gasket pressure (stress) at the exhaust-side bolts when the internal combustion engine is stopped (at room temperature) can be made smaller than the pressure (stress) of the gasket on the intake side bolt. As a result, the difference between the gasket pressure (stress) at the exhaust-side bolt and the gasket pressure (stress) at the intake-side bolt during operation of the internal combustion engine (at high temperatures) can be further reduced. Therefore, it is possible to avoid deformation and uneven wear of parts around the combustion chamber (for example, head gasket). In addition, since there is no need to install a separate mechanism just by changing the arrangement of the bolts on the exhaust side, deformation and uneven wear of parts around the combustion chamber can be avoided with a simple structure, and erroneous assembly can be prevented.

1 is an exploded perspective view of an internal combustion engine (engine); FIG. FIG. 2 is a perspective view illustrating the details of the gasket in the area indicated by II in FIG. 1; FIG. 4 is a schematic cross-sectional view for explaining the state of pressure (stress) applied to a gasket between a cylinder head and a cylinder block; FIG. 4 is a diagram for explaining the distribution of linear pressure (pressure) at the bore bead portion when the engine is operating (high temperature) and when the engine is stopped (normal temperature); It is a figure explaining the relationship between the exhaust side fastening distance and the intake side fastening distance in a gasket. FIG. 4 is a diagram illustrating the distribution of linear pressure (pressure) in the bore bead portion of the gasket of the first embodiment; FIG. 4 is a perspective view for explaining the relationship between the exhaust-side bolt distance and the intake-side bolt distance in the gasket.

An internal combustion engine (engine) 1 of an embodiment to which the present invention is applied will be described below with reference to the drawings. In addition, when the X-axis, Y-axis, and Z-axis are described in the figure, each axis is orthogonal to each other, and a plurality of four cylinders (cylinders) are arranged in series in the X-axis direction. The Y-axis direction indicates the direction from the exhaust port side to the intake port side, and the Z-axis direction indicates the vertically upward direction.

● [Internal combustion engine (engine) 1 (Fig. 1) in the present embodiment]
FIG. 1 is an exploded perspective view of an internal combustion engine (engine) 1. FIG. As shown in FIG. 1 , the internal combustion engine 1 has a cylinder head 30 fixed to the cylinder block 10 by an intake side bolt 42 and an exhaust side bolt 44 (head bolt). A gasket 20 (20A, 20Z) (head gasket) is sandwiched between the lower end faces of the . The internal combustion engine 1 is, for example, an internal combustion engine having a plurality of four cylinders (four cylinders C1 to C4(C)).

In the cylinder block 10, bolt fastening holes 12A to 12E (12) on both edges in the Y-axis direction as fastening holes for fastening head bolts are located on the edges on the intake port side. Each of the bolt fastening holes 14A to 14E (14) is provided along the X-axis direction. The gaskets 20 (20A, 20Z) have bolt holes 22A to 22E (22) on the intake port side at both edges in the Y-axis direction as bolt holes through which head bolts are inserted. Bolt holes 24A to 24E (24) are provided on the port side along the X-axis direction.

In the gasket 20, each of the intake side bolts 42 is tightened and fixed to each of the bolt fastening holes 12 with a predetermined torque, and each of the exhaust side bolts 44 is tightened and fixed to each of the bolt fastening holes 14 with a predetermined torque. , and is sandwiched between the cylinder block 10 and the cylinder head 30 so as to be crushed. The predetermined torque is a tightening torque value that generates a tightening force capable of crushing the gasket 20 to the extent that airtightness can be ensured without leakage of intake gas and exhaust gas from the inside of the cylinder to the outside.

● [Details of gasket 20Z (20) (Fig. 2)]
FIG. 2 is a perspective view explaining the details of the gasket 20Z (20) in the area indicated by II in FIG. The positions of bolt holes 22 and 24 in gasket 20Z indicate the positions of bolt holes in a conventional gasket. The axis of symmetry JK1 is a straight line passing through the center axis CP of the cylinder of the cylinder hole CH and along the XY plane.

The gasket 20Z (20) is provided with cylinder holes CH2 and CH3 respectively communicating with the upper openings of the cylinders C2 and C3 (see FIG. 1). A bore bead portion 26 projecting upward as a cross-sectional shape in the radial direction is provided along the circumferential direction at each of the circumferential edge portions of the cylinder holes CH2 and CH3 (CH).

The bolt holes 22C and 24C are provided at symmetrical positions on the intake port side and the exhaust port side, respectively, with respect to the axis of symmetry JK1. Each of the bolt holes 22D and 24D is provided similarly to each of the bolt holes 22C and 24C.

● [Pressure (linear pressure) applied to gasket 20Z (20) (Figs. 3 and 4)]
The state of the pressure applied to the gasket 20Z (20) will be described with reference to FIGS. 3 and 4. FIG. FIG. 3 is a schematic cross-sectional view for explaining the state of pressure applied to the gasket 20Z (20) sandwiched between the cylinder block 10 and the cylinder head 30. As shown in FIG. The cross section is a cross section including the combustion chamber 15, the intake side bolt 42 and the exhaust side bolt 44. As shown in FIG.

In FIG. 3, when the engine is stopped (at normal temperature), the force generated in the bolts fixed to the cylinder block 10 with a predetermined torque is only the force FT, which is the same force in each of the intake side bolt 42 and the exhaust side bolt 44. Become. Pressures corresponding to the respective forces FT are applied to the bore bead portions 26 on the respective sides of the intake side bolt 42 and the exhaust side bolt 44 .

During engine operation (high temperature), the temperature on the exhaust port side becomes much higher than on the intake port side, and the amount of thermal expansion of the cylinder block 10 and the cylinder head 30 also becomes larger on the exhaust port side than on the intake port side. As a result, force FHex (pressure), which is a force caused by thermal expansion on the exhaust port side, becomes larger than force FHin (pressure), which is a force caused by thermal expansion on the intake port side (FHex>FHin). Therefore, the force Fex (= force FT + force FHex), which is the sum of the force generated by a given torque and the force on the exhaust port side caused by temperature, is the force Fin (= force FT + force FHin), which is the sum of the forces on the intake port side. ) (Fex>Fin). Assuming that the pressure applied to the bore bead portion 26 on the intake port side caused by the force Fin is pressure Pin, and the pressure applied to the bore bead portion 26 on the exhaust port side is pressure Pex, the pressure Pex is calculated from the bolts (42, 44) to the cylinder. is the same distance to the central axis CP, the pressure is greater than Pin (Pex>Pin).

[Distribution of linear pressure (stress) applied to gasket 20Z (20) (Fig. 4)]
FIG. 4 shows the distribution of linear pressure (N/mm) (stress) in the bore bead portion 26 (see FIG. 3) when the engine is running (at high temperature) and when the engine is stopped (at normal temperature). It is a figure explaining an example. In order to clarify the relative relationship between the distribution of linear pressure (stress) and the positions of the bolt holes in the gasket, as an example, the positions of the bolt holes (22E, 22D, 24E, 24D) with respect to the cylinder C4 are shown in FIG. shown repeatedly. FIG. 4 is a radar chart showing the distribution of the linear pressure (N/mm) in the bore bead portion 26 (see FIG. 5). distribution. The center of the circle (the center of the chart) indicates a linear pressure of 0, and each circle indicates the magnitude of the linear pressure (linear pressure Pr1 to Pr4), which increases from the center side (the chart center) toward the outside (linear pressure of 0 <Linear pressure Pr1<Linear pressure Pr2<Linear pressure Pr3<Linear pressure Pr4).

The linear pressure distribution RTZ indicated by the dotted line is the linear pressure distribution when the engine is stopped (at room temperature), and the linear pressure distribution HTZ indicated by the solid line is the linear pressure distribution when the engine is operating (at high temperature). The linear pressure distribution (N/mm) indicates the magnitude per unit length of stress generated in the bore bead portion 26 due to the pressure applied to the bore bead portion 26 .

As shown in FIG. 4, in the linear pressure distribution RTZ, the linear pressure (stress) in the bore bead portion 26 is increased by the pressure due to the force generated by the predetermined torque. It shows a distribution in which the inside of the part 26 is larger than the other places. In the linear pressure distribution RTZ, when the engine is stopped (at room temperature), there is no force generated by thermal expansion, so the distribution of the linear pressure (stress) in the bore bead portion 26 has a large difference between the exhaust port side and the intake port side. does not cause On the other hand, in the linear pressure distribution HTZ, since there is a force generated by thermal expansion during engine operation (at high temperatures), the linear pressure (stress) distribution in the bore bead portion 26 is greater on the exhaust port side than on the intake port side.

● [Exhaust-side fastening distance and intake-side fastening distance of the gasket 20A (20) of the first embodiment (Figs. 5 and 6)]
FIG. 5 is a diagram illustrating the relationship between the exhaust side fastening distances d21, d23, d21A, d23A and the intake side fastening distances d11, d13 in the gasket 20A (20).

The gasket 20A (20) has cylinder holes CH1 to CH4, which are the cylinder holes of the cylinders C1 to C4 (C), and bolt holes 22A to 22E (22) on the intake port side at both edges in the Y-axis direction. , and bolt holes 24AA to 24EA (24) are provided along the X-axis direction on the exhaust port side.

Bolt hole centers P11 and P13 respectively indicate the center positions of the bolt holes 22A and 22C, and bolt hole centers P21A and P23A respectively indicate the center positions of the bolt holes 24AA and 24CA. there is

The gasket 20A (20) is divided into five regions by straight lines extending along the Y-axis direction passing through the central axes CP1 to CP4 of the cylinder shown in FIG. 5, and the divided regions are used for detailed description. The inner areas MA1 to MA3 are areas that do not include the end portion side of the gasket 20A (20) and are areas that overlap two adjacent cylinders. The end side areas TA1 and TA2 are areas including the end side of the gasket 20A (20), and are areas that cover only one cylinder.

Since the inner areas MA1 to MA3 have the same arrangement of the bolt holes with respect to the cylinder holes, the inner area MA2 will be described in detail. The inner area MA2 includes the cylinder center axes CP2 and CP3 of the cylinder holes CH2 and CH3 of the cylinders C2 and C3, respectively, and the bolt holes 22C and 24CA. In addition, since the inner area MA2 is symmetrical with respect to the straight line passing through the centers of the bolt holes 22C and 24CA, the description of the center axis CP3 of the cylinder is omitted.

The bolt hole 24C represents a bolt hole on the exhaust port side in a conventional gasket, and is provided at a position symmetrical to the bolt hole 22C on the intake port side with respect to the axis of symmetry JK1. The bolt hole 24CA represents the bolt hole on the exhaust port side of the gasket 20A of the first embodiment, and is provided at a position shifted by a predetermined distance along the direction opposite to the Y-axis direction from the position of the bolt hole 24C. . The predetermined distance is within a range in which the pressure generated by the moved bolt hole can deform the nearby bore bead portion to the extent that airtightness can be ensured.

The bolt hole 24C is a bolt hole on the exhaust port side of a conventional gasket, and is provided at a position symmetrical to the bolt hole 22C on the intake port side with respect to the axis of symmetry JK1. The bolt hole 24CA is a bolt hole on the exhaust port side of the gasket 20A of the first embodiment, and is moved by a predetermined distance from the position of the bolt hole 24C along the direction opposite to the Y-axis direction with respect to the axis of symmetry JK1. position.

The intake side fastening distance d13 is the distance from the center axis CP2 of the cylinder to the nearest bolt hole 22C. Specifically, it is the distance from the central axis CP2 of the cylinder to the bolt hole center P13, which is the center of the bolt hole 22C. Since the intake-side bolt 42 (see FIG. 1) is inserted through the bolt hole 22C, the intake-side fastening distance d13 is the distance from the cylinder center axis CP2 of the cylinder C2 to the nearest intake-side bolt. Equivalent to.

The exhaust-side fastening distance d23 is the distance from the central axis CP2 of the cylinder to the nearest bolt hole 24C, and is the same as the intake-side fastening distance d13. Specifically, it is the distance from the center axis CP2 of the cylinder to the bolt hole center P23, which is the center of the bolt hole 24C. Since the exhaust-side bolt 44 (see FIG. 1) is inserted through the bolt hole 24CA, the exhaust-side fastening distance d23 is the distance from the cylinder center axis CP2 of the cylinder C2 to the nearest exhaust-side bolt. Equivalent to.

The exhaust-side fastening distance d23A is the distance from the center axis CP2 of the cylinder to the nearest bolt hole 24CA. Specifically, it is the distance from the center axis CP2 of the cylinder to the bolt hole center P23A, which is the center of the bolt hole 24CA. Since the exhaust-side bolt 44 (see FIG. 1) is inserted through the bolt hole 24CA, the exhaust-side fastening distance d23A is the distance from the cylinder center axis CP2 of the cylinder C2 to the nearest exhaust-side bolt. Equivalent to. Since the bolt holes 22C and 24C are provided at symmetrical positions with respect to the axis of symmetry JK1, the exhaust side fastening distance d23A and the intake side fastening distance d13 are the same.

The exhaust-side fastening distance d23A is provided at a position moved by a predetermined distance along the direction opposite to the Y-axis direction, which is the direction away from the cylinder central axis CP2, and is longer than the exhaust-side fastening distance d23. It is set longer than the distance d13. That is, the distance between the bolt hole 24CA on the exhaust port side and the bore bead portion 26 is set to be longer than the distance between the bolt hole 22C and the bore bead portion 26 on the intake port side.

Since the end regions TA1 and TA2 have the same arrangement of the bolt holes with respect to the cylinder holes, the end region TA1 will be described in detail. The end area TA1 includes the cylinder center axis CP1 of the cylinder hole CH1 and the bolt holes 22A and 24AA.

The bolt hole 24A represents a bolt hole on the exhaust port side of a conventional gasket, and is provided at a position symmetrical to the bolt hole 22A on the intake port side with respect to the axis of symmetry JK1. The bolt hole 24AA represents a bolt hole on the exhaust port side of the gasket 20A of the first embodiment, and extends radially outward from the position of the bolt hole 24A to the center axis CP1 of the cylinder (the center of the cylinder hole CH1). It is provided at a position moved by a distance. The predetermined distance is within a range in which the pressure generated by the moved bolt hole can deform the nearby bore bead portion to the extent that airtightness can be ensured.

The intake side fastening distance d11 is the distance from the center axis CP1 of the cylinder to the nearest bolt hole 22A. Specifically, it is the distance from the center axis CP1 of the cylinder to the bolt hole center P11, which is the center of the bolt hole 22A. Since the intake-side bolt 42 (see FIG. 1) is inserted through the bolt hole 22A, the intake-side fastening distance d11 is the distance from the cylinder center axis CP1 of the cylinder C1 to the nearest intake-side bolt. Equivalent to.

The exhaust-side fastening distance d21 is the distance from the center axis CP1 of the cylinder to the nearest bolt hole 24A. Specifically, it is the distance from the center axis CP1 of the cylinder to the bolt hole center P21, which is the center of the bolt hole 24A. Since the exhaust-side bolt 44 (see FIG. 1) is inserted through the bolt hole 24A, the exhaust-side fastening distance d21 is the distance from the cylinder center axis CP1 of the cylinder C1 to the nearest exhaust-side bolt. Equivalent to.

The exhaust-side fastening distance d21A is the distance from the center axis CP1 of the cylinder to the nearest bolt hole 24AA. Specifically, it is the distance from the center axis CP1 of the cylinder to the bolt hole center P21A, which is the center of the bolt hole 24AA. Since the exhaust-side bolt 44 (see FIG. 1) is inserted through the bolt hole 24AA, the exhaust-side fastening distance d21A is the distance from the cylinder center axis CP1 of the cylinder C1 to the nearest exhaust-side bolt. Equivalent to. Since the bolt holes 22A and 24A are provided at symmetrical positions with respect to the axis of symmetry JK1, the exhaust side fastening distance d21A and the intake side fastening distance d11 are the same.

The exhaust-side fastening distance d21A is provided at a position radially outwardly shifted by a predetermined distance from the center axis CP1 (the center of the cylinder hole CH1) of the cylinder. It is set longer than the fastening distance d11. That is, the distance between the bolt hole 24AA on the exhaust port side and the bore bead portion 26 is set to be longer than the distance between the bolt hole 22A on the intake port side and the bore bead portion 26 .

[Distribution of linear pressure (stress) applied to gasket 20A (20) (Fig. 6)]
FIG. 6 is a diagram for explaining the distribution of linear pressure in the bore bead portion 26 of the gasket 20A (20) when the engine is stopped (at room temperature). 4 except that the respective positions of the bolt holes 24EA and 24DA are additionally superimposed, and therefore detailed description of the axes and the like in the drawing will be omitted.

The linear pressure distribution RTZ indicated by the dotted line is the linear pressure distribution of the bore bead portion 26 (see FIG. 2) of the conventional gasket 20Z, and the linear pressure distribution RTA indicated by the solid line is the bore bead of the gasket 20A of the first embodiment. It is the linear pressure distribution of the portion 26 (see FIG. 5).

The linear pressure distribution RTZ shown in FIG. 6 is the same as the linear pressure distribution RTZ shown in FIG. The linear pressure distribution RTA is the distribution of the linear pressure (stress) in the bore bead portion 26 (see FIG. 5) when the engine is stopped (at room temperature). , the linear pressure (stress) of the bore bead on the exhaust port side is smaller than the linear pressure (stress) of the bore bead on the intake port side. In this way, by reducing the linear pressure (stress) of the bore bead portion 26 on the exhaust port side when the engine is stopped (at room temperature), the stress distribution on the intake port side and the stress distribution on the exhaust port side when the engine is operating (at high temperature). The difference from the linear pressure distribution (stress distribution) can be further reduced.

[Distance between bolts on the exhaust side and distance between bolts on the intake side of the gasket 20B of the second embodiment (Fig. 7)]
FIG. 7 is a perspective view illustrating the relationship between the exhaust-side bolt distance and the intake-side bolt distance in the gasket 20B of the second embodiment. The gasket 20B of the second embodiment is a gasket for a 1-cylinder (single cylinder) internal combustion engine, whereas the gasket 20A (20) of the first embodiment is a gasket for a 4-cylinder internal combustion engine. differ in The axis of symmetry JK2 is a straight line along the XY plane passing through the center axis CP5 of the cylinder of the cylinder hole CH5.

Each of bolt hole 22F and bolt hole 24F represents a bolt hole in a conventional gasket. The bolt holes 22F and 24F are provided at symmetrical positions on the intake port side and the exhaust port side, respectively, with respect to the axis of symmetry JK2. The bolt holes 22G and 24G are provided similarly to the bolt holes 22F and 24F, respectively.

The bolt hole 24FA represents the bolt hole on the exhaust port side of the gasket 20B of the second embodiment, and is provided at a position shifted by a predetermined distance along the direction opposite to the X-axis direction from the position of the bolt hole 24F. . A bolt hole 24GA represents a bolt hole on the exhaust port side of the gasket 20B of the second embodiment, and is provided at a position shifted by a predetermined distance along the X-axis direction from the position of the bolt hole 24G.

The intake side bolt distance w1 is the distance between two adjacent bolt holes 22F and 22G. Specifically, it is the distance between the bolt hole center PB11 and the bolt hole center PB12, which are the respective centers of the bolt holes 22F and 22G. Since the intake-side bolts are inserted through the bolt holes 22F and 22G, the distance w1 between the intake-side bolts corresponds to the distance between two adjacent intake-side bolts.

The exhaust-side bolt-to-bolt distance w2 is the distance between two adjacent bolt holes 24FA and 24GA. Specifically, it is the distance between the bolt hole center PB21A and the bolt hole center PB22A, which are the respective centers of the bolt holes 24FA and 24GA. Since the exhaust-side bolts are inserted through the bolt holes 24FA and 24GA, the distance w2 between the exhaust-side bolts corresponds to the distance between two adjacent intake-side bolts.

The distance w2 between bolts on the exhaust side is provided at a position where the bolt hole 24FA is moved from the position of the bolt hole 24F by a predetermined distance along the direction opposite to the X-axis direction, and the bolt hole 24GA is provided at the position of the bolt hole 24G in the X-axis direction. It is set to be longer than the distance w1 between the bolts on the intake side by being provided at a position moved a predetermined distance along.

The bolt hole 24FA is provided at a position away from the central axis CP5 of the cylinder (the center of the cylinder hole CH5) in order to move the bolt hole 24F by a predetermined distance along the direction opposite to the X-axis direction. ing. Similarly, the bolt hole 24GA is provided at a position away from the central axis CP5 of the cylinder (the center of the cylinder hole CH5) in order to move a predetermined distance along the X-axis direction from the position of the bolt hole 24G. there is That is, the distance between the bolt holes 24FA, 24GA on the exhaust port side and the bore bead portion 26 is set to be longer than the distance between the bolt holes 22F, 22G on the intake port side and the bore bead portion 26. Therefore, the same effect as the gasket 20A (see FIG. 5) of the first embodiment can be obtained.
● [Effects of the application]

As described above, in the first embodiment, when the tightening torques of the plurality of exhaust-side bolts 44 and the plurality of intake-side bolts 42 are set to be the same, the exhaust-side torque when the internal combustion engine is stopped (at room temperature) The gasket pressure (stress) at the bolt 44 can be made smaller than the pressure (stress) at the intake-side bolt 42 and the gasket 20A (20). As a result, the difference between the pressure (stress) of the gasket 20A at the exhaust side bolt 44 and the pressure (stress) of the gasket 20A at the intake side bolt 42 during operation of the internal combustion engine (at high temperatures) can be further reduced. Therefore, it is possible to avoid deformation and uneven wear of parts around the combustion chamber (for example, the gasket 20A (20)). In addition, since there is no need to install a separate mechanism just by changing the arrangement of the bolts on the exhaust side, deformation and uneven wear of parts around the combustion chamber can be avoided with a simple structure, and erroneous assembly can be prevented.

Further, in the second embodiment, when the tightening torques of the plurality of exhaust side bolts 44 and the plurality of intake side bolts 42 are set to be the same, the gasket 20B of the exhaust side bolts 44 when the internal combustion engine is stopped (at room temperature) The pressure (stress) on (20) can be made smaller than the pressure (stress) on the gasket 20B of the intake side bolt 42 . As a result, the difference between the pressure (stress) of the exhaust-side bolt 44 on the gasket 20B and the pressure (stress) of the intake-side bolt 42 on the gasket 20B during operation of the internal combustion engine (at high temperature) can be further reduced. . As a result, deformation and uneven wear of parts around the combustion chamber (for example, the gasket 20B (20)) can be avoided. In addition, since there is no need to install a separate mechanism just by changing the arrangement of the bolts on the exhaust side, deformation and uneven wear of parts around the combustion chamber can be avoided with a simple structure, and erroneous assembly can be prevented.

The internal combustion engine structure of the present invention is not limited to the configuration, structure, etc. described in the present embodiment, and various modifications, additions, and deletions are possible without changing the gist of the present invention. In particular, the number of cylinders of the internal combustion engine is not limited to one cylinder or four cylinders as described in the present embodiment. It can be applied to internal combustion engines with

In FIG. 5, in each of the inner areas MA1 to MA3 and each of the end areas TA1 and TA2, an example in which the arrangement of the bolt holes with respect to the cylinder holes is the same has been described. It can be different.

1 internal combustion engine 10 cylinder block 12, 12A to 12E bolt fastening holes 14, 14A to 14E bolt fastening holes 15 combustion chamber 20, 20A, 20B, 20Z gasket (head gasket)
22, 22A to 22E bolt hole 24, 24A to 24E bolt hole 26 bore bead portion 30 cylinder head 42 intake side bolt (head bolt)
44 exhaust side bolt (head bolt)
C, C1-C4 Cylinder CH, CH1-CH4 Cylinder hole CP, CP1-CP4 Cylinder central axis d11, d13 Intake side engagement distance d21, d23 Exhaust side engagement distance d21A, d23A Exhaust side engagement distance JK1, JK2 Symmetry axis w1 Intake Distance between side bolts w2 Distance between exhaust side bolts P11, P13 Bolt hole center P21, P23 Bolt hole center P21A, P23A Bolt hole center PB11, PB12 Bolt hole center MA1 to MA3 Inner area TA1, TA2 End side area

Claims (3)

A gasket is sandwiched between the upper end surface of the cylinder block and the lower end surface of the cylinder head, and the cylinder block and the cylinder head are fixed using a plurality of bolts so as to crush the gasket with a predetermined torque, and the single cylinder or in an internal combustion engine structure having a plurality of cylinders,
The plurality of bolts are
A plurality of intake-side bolts installed on the intake side with respect to the central axis of the cylinder and positioned so as not to overlap the cylinder when viewed in the direction from the intake port side to the exhaust port side, and from the intake port side to the exhaust port side. and a plurality of exhaust-side bolts positioned so as not to overlap the cylinder when viewed in the direction and mounted on the exhaust side with respect to the central axis of the cylinder ,
In a single cylinder or in each of a plurality of cylinders, the exhaust-side fastening distance, which is the distance from the center axis of the cylinder to the nearest exhaust-side bolt,
is set longer than the intake-side fastening distance, which is the distance from the central axis of the cylinder to the nearest intake-side bolt,
Internal combustion engine structure. A gasket is sandwiched between the upper end surface of the cylinder block and the lower end surface of the cylinder head, and the cylinder block and the cylinder head are fixed using a plurality of bolts so as to crush the gasket with a predetermined torque , and the single cylinder In an internal combustion engine structure having
The plurality of bolts are
A plurality of intake-side bolts installed on the intake side with respect to the central axis of the cylinder and positioned so as not to overlap the cylinder when viewed in the direction from the intake port side to the exhaust port side, and from the intake port side to the exhaust port side. and a plurality of exhaust-side bolts positioned so as not to overlap the cylinder when viewed in the direction and mounted on the exhaust side with respect to the central axis of the cylinder ,
A distance between the exhaust-side bolts, which is the distance between the two adjacent bolts on the exhaust side, is set longer than a distance between the bolts on the intake side, which is the distance between the two adjacent bolts on the intake side.
Internal combustion engine structure. A gasket is sandwiched between the upper end surface of the cylinder block and the lower end surface of the cylinder head, and the cylinder block and the cylinder head are fixed by using a plurality of bolts so as to crush the gasket with a predetermined torque, and the plurality of cylinders are mounted. In an internal combustion engine structure having
The plurality of bolts are
A plurality of intake-side bolts installed on the intake side with respect to the central axis of the cylinder and positioned so as not to overlap the cylinder when viewed in the direction from the intake port side to the exhaust port side, and from the intake port side to the exhaust port side. and a plurality of exhaust-side bolts positioned so as not to overlap the cylinder when viewed in the direction and mounted on the exhaust side with respect to the central axis of the cylinder,
a distance between two adjacent exhaust-side bolts in the vicinity of one end of a plurality of cylinders arranged in series;
a distance between two adjacent exhaust-side bolts in the vicinity of the cylinder on the other end side in a plurality of cylinders arranged in series;
The distances between the bolts on the exhaust side, which are the respective distances of
a distance between two adjacent intake-side bolts in the vicinity of one end of a plurality of cylinders arranged in series;
a distance between two adjacent intake-side bolts in the vicinity of the cylinder on the other end side in a plurality of cylinders arranged in series;
is set longer than the distance between the bolts on the intake side, which is the distance of each of
Internal combustion engine structure.

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