Cam bearing cover assembly

Abstract

The invention discloses a cam bearing cover assembly, and belongs to the technical field of automobile engine parts. Comprising an air inlet cam bearing cover and an exhaust cam bearing cover which are matched and arranged in pairs and are of an integrally-formed structure. The air inlet cam bearing cover is integrally provided with air inlet cam bearing seats, air inlet bolt holes, an air inlet cross beam and an air inlet longitudinal beam, an air inlet rectangular oil groove is formed in the first air inlet cam bearing seat, air inlet positioning sleeve holes are formed in the two air inlet cam bearing seats, an air inlet cross beam is arranged between the adjacent air inlet cam bearing seats, and an air inlet semicircular pit is formed in the cross beam; the exhaust cam bearing cover is of an adaptive structure, two exhaust cross beams are arranged between every two adjacent exhaust cam bearing seats, and the longitudinal beams and the cross beams respectively form an integral supporting structure. By means of the integrated structure and cooperation of all functions, multiple technical defects of a split type bearing cover are overcome, the structural rigidity and assembly precision are improved, vibration noise is restrained, frictional wear is reduced, the NVH performance and work reliability of an engine are improved, production and assembly convenience is achieved, and the application and popularization value is high.

Description

Technical Field

[0001] This invention belongs to the field of automotive engine parts technology, specifically a cam bearing cover assembly. Background Technology

[0002] The camshaft bearing cap is a core fixing component of the internal combustion engine camshaft. Its main function is to fix the camshaft in the correct preset position, ensuring smooth operation of the camshaft and thus enabling precise control of the engine valve opening and closing. It is a key component of the engine's valve train. Currently, the commonly used technical solution in the industry is to design a separate camshaft bearing cap for each diameter section of the camshaft, i.e., a split camshaft bearing cap structure.

[0003] The existing technical solution has significant technical defects: because each camshaft bearing cap is independently set and lacks an overall connection and support structure, when the camshaft rotates at high speed, the camshaft bearing cap is subjected to short-term nonlinear contact impacts in both axial and radial directions transmitted by the camshaft. Simultaneously, it is prone to resonance with the camshaft, leading to amplified vibration amplitudes. This vibration is directly transmitted to the engine cylinder head and surrounding components, causing radiated noise in the engine axial direction between 800Hz and 1000Hz, specifically manifested as a clearly audible "ticking" or "rustling" sound. This noise reduces the overall driving comfort of the vehicle and does not meet the current automotive industry's requirements for improving engine NVH performance. This defect is particularly prominent in the mid-to-high-end passenger vehicle sector, becoming one of the key factors restricting the optimization of engine NVH performance. Summary of the Invention

[0004] To address the problems existing in the background art, the present invention provides a cam bearing cover assembly.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a cam bearing cover assembly, including an intake cam bearing cover and an exhaust cam bearing cover, which are matched and installed in pairs;

[0006] The intake camshaft bearing cover is an integrally formed structure. The intake camshaft bearing cover is integrally provided with multiple intake camshaft bearing seats, multiple intake bolt holes, multiple intake crossbeams and two intake longitudinal beams. The first intake camshaft bearing seat arranged along the camshaft axis is the bearing seat near the front of the engine and has an intake rectangular oil groove. The two intake longitudinal beams are respectively set on both sides of the multiple intake camshaft bearing seats. The two intake longitudinal beams are integrally formed with the corresponding side wall of each intake camshaft bearing seat. Each of the two intake camshaft bearing seats has an intake positioning sleeve hole and an intake bolt hole. The remaining intake camshaft bearing seats each have two intake bolt holes. There is an intake crossbeam between every two adjacent intake camshaft bearing seats. Each intake crossbeam is integrally formed with the corresponding intake longitudinal beam at both ends. Each intake crossbeam has an intake semi-circular recess. The two intake longitudinal beams and the multiple intake crossbeams form an integral support structure for the intake side.

[0007] The exhaust camshaft bearing cover is an integrally formed structure. The exhaust camshaft bearing cover is integrally formed with multiple exhaust camshaft bearing seats, multiple exhaust bolt holes, multiple exhaust crossbeams and two exhaust longitudinal beams. The first exhaust camshaft bearing seat, which is arranged along the camshaft axis, is the bearing seat near the front of the engine and has an exhaust rectangular oil groove. The two exhaust longitudinal beams are respectively set on both sides of the multiple exhaust camshaft bearing seats. The two exhaust longitudinal beams are integrally formed with the corresponding side wall of each exhaust camshaft bearing seat. Each of the two exhaust camshaft bearing seats has an exhaust positioning sleeve hole and an exhaust bolt hole. The remaining exhaust camshaft bearing seats each have two exhaust bolt holes. There are two exhaust crossbeams between every two adjacent exhaust camshaft bearing seats. The two ends of each exhaust crossbeam are integrally formed with the corresponding exhaust longitudinal beam. Each exhaust crossbeam has an exhaust semi-circular recess. The two exhaust longitudinal beams and the multiple exhaust crossbeams form an integral exhaust side support structure.

[0008] Both the intake rectangular oil groove and the exhaust rectangular oil groove extend along the inner wall of the corresponding cam bearing housing, and one end is connected to the lubrication oil passage of the cylinder head.

[0009] The inner diameter of each of the intake positioning sleeve holes and each of the exhaust positioning sleeve holes is adapted to the outer diameter of the corresponding positioning pin on the cylinder head, and each of the intake positioning sleeve holes and each of the exhaust positioning sleeve holes is in a plug-in fit with the corresponding positioning pin.

[0010] Each of the aforementioned intake longitudinal beams and each of the exhaust longitudinal beams is a curved or straight structure with a rectangular cross-section. The connection between each intake longitudinal beam and each of the exhaust longitudinal beams and the corresponding cam bearing housing is an integrally formed rounded transition structure.

[0011] Each of the intake crossbeams and each of the exhaust crossbeams has a T-shaped or rectangular crossbeam structure, and each of the intake semicircular recesses and each of the exhaust semicircular recesses is a semicircular groove, which is adapted to the structure of the camshaft protrusion.

[0012] Each of the aforementioned intake bolt holes and each of the exhaust bolt holes are through holes and are adapted to high-strength bolts. Each intake bolt hole and each of the exhaust bolt holes are adapted to the corresponding bolt installation positions on the cylinder head.

[0013] Compared with the prior art, the beneficial effects of the present invention are:

[0014] 1. This invention significantly improves the overall dynamic stiffness of the camshaft bearing cover assembly by integrating the intake and exhaust camshaft bearing covers with the overall support structure of the longitudinal and transverse beams. It effectively avoids the resonance phenomenon that is prone to occur in split structures, suppresses the problem of vibration amplitude superposition and amplification caused by high-speed camshaft operation from the root, reduces engine radiation noise, significantly improves engine NVH performance, and greatly enhances the driving comfort of the whole vehicle.

[0015] 2. The present invention provides a dedicated positioning sleeve hole on the cam bearing housing, which can achieve precise positioning between the cam bearing cover and the cylinder head and camshaft, effectively control assembly deviation, avoid uneven force and increased vibration caused by assembly position offset, and simplify the cumbersome process of assembling the split structure one by one, thereby improving the overall assembly efficiency and assembly accuracy.

[0016] 3. The present invention provides a rectangular oil groove on the camshaft bearing housing near the front end of the engine, which enables continuous and precise lubrication of the camshaft diameter, effectively reduces friction and wear between the camshaft bearing housing and the camshaft, reduces vibration and abnormal noise caused by friction, and extends the overall service life of the camshaft bearing cover and the camshaft.

[0017] 4. The present invention provides a semi-circular recess on the crossbeam that matches the protruding part of the camshaft, thereby achieving precise avoidance of the structure, preventing mechanical interference between the camshaft and the crossbeam during operation, preventing impact, abnormal noise and damage to parts caused by interference, and ensuring that the camshaft always operates smoothly and without obstruction.

[0018] 5. The intake and exhaust camshaft bearing covers of the present invention are both made in one piece, with a reasonable overall structure design. The components work together to form a stable support and fixing system, which eliminates the design of separate structures with multiple components connected independently, simplifies the production and processing process, and facilitates mass production and application.

[0019] 6. This invention optimizes the stress distribution of the cam bearing cover through an integral structural design, quickly dispersing the axial and radial impact loads transmitted by the camshaft to the entire support frame, completely solving the load concentration problem of the split structure, improving the structural strength and impact resistance of the cam bearing cover assembly, ensuring its structural stability during long-term high-speed engine operation, and further improving the working reliability of the engine valve train.

[0020] In summary, this invention, through its integrated structural design and the coordinated operation of various functional structures, precisely addresses the technical shortcomings of traditional split camshaft bearing covers, such as low dynamic stiffness, high vibration and noise, difficulty in controlling assembly deviations, concentrated loads, and high friction and wear. It achieves technological upgrades in multiple aspects, including improving structural stiffness, suppressing vibration and noise, enhancing assembly accuracy, reducing friction and wear, avoiding structural interference, and optimizing production and assembly. This significantly improves engine NVH performance and operational reliability, extends the service life of core components, and also ensures ease of production and assembly, demonstrating significant practical application and promotional value. Attached Figure Description

[0021] Figure 1 This is a top view of the present invention;

[0022] Figure 2 This is a bottom view of the present invention;

[0023] Figure 3 This is an exploded view of the present invention in its uninstalled state;

[0024] Figure 4 This is a schematic diagram of the installation state of the present invention. Detailed Implementation

[0025] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0026] This embodiment describes a cam bearing cover assembly, including an intake cam bearing cover 1 and an exhaust cam bearing cover 2, which are matched and installed in pairs.

[0027] The intake camshaft bearing cover 1 is an integrally formed structure. The intake camshaft bearing cover 1 is integrally provided with multiple intake camshaft bearing seats 3, multiple intake bolt holes 4, multiple intake crossbeams 6 and two intake longitudinal beams 5. The first intake camshaft bearing seat 3 arranged along the camshaft axis is a bearing seat close to the front end of the engine and has an intake rectangular oil groove 7. The two intake longitudinal beams 5 are respectively provided on both sides of the multiple intake camshaft bearing seats 3. The two intake longitudinal beams 5 are integrally formed with the corresponding side wall of each intake camshaft bearing seat 3. Each of the two intake camshaft bearing seats 3 has an intake positioning sleeve hole 9 and an intake bolt hole 4. The remaining intake camshaft bearing seats 3 each have two intake bolt holes 4. An intake crossbeam 6 is provided between every two adjacent intake camshaft bearing seats 3. Both ends of each intake crossbeam 6 are integrally formed with the corresponding intake longitudinal beam 5. Each intake crossbeam 6 has an intake semi-circular recess 8. The two intake longitudinal beams 5 and the multiple intake crossbeams 6 form an integral support structure for the intake side.

[0028] The exhaust camshaft bearing cover 2 is an integrally formed structure. The exhaust camshaft bearing cover 2 is integrally provided with multiple exhaust camshaft bearing seats 31, multiple exhaust bolt holes 41, multiple exhaust crossbeams 61 and two exhaust longitudinal beams 51. The first exhaust camshaft bearing seat 31, which is arranged along the camshaft axis, is a bearing seat close to the front end of the engine and has an exhaust rectangular oil groove 71. The two exhaust longitudinal beams 51 are respectively located on both sides of the multiple exhaust camshaft bearing seats 31. The two exhaust longitudinal beams 51 are integrally formed with the corresponding side wall of each exhaust camshaft bearing seat 31. Each of the two exhaust camshaft bearing seats 31 has an exhaust positioning sleeve hole 91 and an exhaust bolt hole 41. The remaining exhaust camshaft bearing seats 31 each have two exhaust bolt holes 41. Two exhaust crossbeams 61 are provided between each two adjacent exhaust camshaft bearing seats 31. Both ends of each exhaust crossbeam 61 are integrally formed with the corresponding exhaust longitudinal beam 51. Each exhaust crossbeam 61 has an exhaust semi-circular recess 81. The two exhaust longitudinal beams 51 and the multiple exhaust crossbeams 61 form an integral exhaust side support structure.

[0029] The intake rectangular oil groove 7 and the exhaust rectangular oil groove 71 are both extended along the inner wall of the corresponding cam bearing seat, and one end is connected to the lubrication oil passage of the cylinder head 10.

[0030] The inner diameter of each of the intake positioning sleeve holes 9 and each of the exhaust positioning sleeve holes 91 is adapted to the outer diameter of the corresponding positioning pin 11 on the cylinder head 10, and each of the intake positioning sleeve holes 9 and each of the exhaust positioning sleeve holes 91 is in a plug-in fit with the corresponding positioning pin 11.

[0031] Each of the intake longitudinal beams 5 and each of the exhaust longitudinal beams 51 is a curved or straight structure with a rectangular cross-section. The connection between each intake longitudinal beam 5 and each of the exhaust longitudinal beams 51 and the corresponding cam bearing seat is an integrally formed rounded transition structure.

[0032] Each of the intake crossbeams 6 and each of the exhaust crossbeams 61 has a T-shaped or rectangular cross-section, and each of the intake semicircular recesses 8 and each of the exhaust semicircular recesses 81 is a semicircular groove, which is adapted to the structure of the camshaft protrusion.

[0033] Each of the aforementioned intake bolt holes 4 and each exhaust bolt hole 41 is a through hole and is adapted to the high-strength bolt 12. Each intake bolt hole 4 and each exhaust bolt hole 41 is adapted to the corresponding bolt installation position on the cylinder head 10.

[0034] This camshaft bearing cap assembly, as a core fixing component of the internal combustion engine camshaft, replaces the traditional split structure with an integrated structure design of intake camshaft bearing cap 1 and exhaust camshaft bearing cap 2. The two are paired to form an overall support system. The various structures work together to achieve stable camshaft fixation and low-vibration, low-noise operation. Its working principle is as follows: both intake camshaft bearing cap 1 and exhaust camshaft bearing cap 2 are integrally formed structures. The two intake longitudinal beams 5 and multiple intake crossbeams 6 on the intake camshaft bearing cap 1 are interwoven and integrally formed with each intake camshaft bearing seat 3. Similarly, the two exhaust longitudinal beams 51 and multiple exhaust crossbeams 61 on the exhaust camshaft bearing cap 2 are interwoven and integrally formed with each exhaust camshaft bearing seat 31, forming an integrated support structure on the intake and exhaust sides respectively. The cross-section of the intake longitudinal beams 5 and exhaust longitudinal beams 51 can be a 5mm × 12mm rectangle. An intake crossbeam 6 is provided between every two adjacent intake camshaft bearing seats 3 on the intake side. Two exhaust crossbeams 61 are provided between every two adjacent exhaust camshaft bearing seats 31 on the exhaust side. The cross-sections of the intake crossbeam 6 and the exhaust crossbeam 61 can adopt a T-shaped or rectangular structure. This integral structure increases the overall dynamic stiffness of the bearing cover assembly by 60%~400%, effectively increasing the dynamic stiffness to the range of 12000~20000N / mm. Compared with the dynamic stiffness of the traditional split bearing cover of 3289~6000N / mm, it achieves a significant improvement. When the camshaft rotates at high speed and transmits axial and radial nonlinear contact impacts to the intake camshaft bearing seat 3 and the exhaust camshaft bearing seat 31, the high-rigidity rigid whole can quickly disperse the single-point impact load to the entire support frame, effectively avoiding the resonance phenomenon between the bearing cover and the camshaft, suppressing the superposition and amplification of vibration amplitude from the root, reducing the transmission of vibration to the engine cylinder head 10 and surrounding parts, and specifically solving the problem of radiated noise between 800Hz and 1000Hz in the axial direction of the engine.

[0035] Multiple intake camshaft bearing seats 3 and exhaust camshaft bearing seats 31 can each be provided in fives, and each can be precisely matched with the five corresponding shaft diameters of the camshaft (determined according to the number of engine cylinders; for example, if the high-pressure oil pump camshaft is a four-cylinder engine, then the number of multiple intake camshaft bearing seats 3 and exhaust camshaft bearing seats 31 is five). This provides full circumferential support for the camshaft, and the bearing seats and longitudinal beams are integrally formed without assembly gaps, ensuring that the camshaft operates at a preset axis position, ensuring coaxiality during high-speed operation, and reducing uneven wear and irregular impacts. The intake rectangular oil groove 7 and exhaust rectangular oil groove 71 opened on the first intake camshaft bearing seat 3 and exhaust camshaft bearing seat 31 arranged along the camshaft axis can be... With a width of 5mm and a depth of 4.5mm, the oil groove extends along the inner wall of the corresponding bearing housing and one end is connected to the lubrication oil passage of the cylinder head 10. When the engine is working, the lubricating oil of the lubrication system is continuously delivered to the intake rectangular oil groove 7 and the exhaust rectangular oil groove 71 through the lubrication oil passage. This can evenly distribute the lubricating oil on the contact surface between the bearing housing and the camshaft diameter and form a stable oil film, thereby achieving continuous and precise lubrication of the camshaft diameter. This effectively reduces the friction and wear between the intake camshaft bearing housing 3, the exhaust camshaft bearing housing 31 and the camshaft, significantly reduces the wear rate of the camshaft and the bearing housing, and improves the service life of the camshaft bearing cover and the camshaft. At the same time, it reduces friction vibration and noise and alleviates contact temperature rise.

[0036] The intake positioning sleeve holes 9 and exhaust positioning sleeve holes 91 on the two intake camshaft bearing housings 3 and the two exhaust camshaft bearing housings 31 can be 8mm in diameter, and can be precisely inserted and fitted with the positioning pins 11 on the cylinder head 10 with a diameter of 8mm and a length of 14mm. During assembly, the intake camshaft bearing housing 1, the exhaust camshaft bearing housing 2, the cylinder head 10, and the camshaft can be precisely positioned, and the assembly deviation can be controlled within ±0.05mm. This avoids problems such as poor fit between the bearing housing and the camshaft diameter and uneven force due to the misalignment of the assembly position, and ensures that the camshaft is always in the correct operating position designed. At the same time, it provides a precise foundation for bolt assembly.

[0037] The intake semi-circular recess 8 and exhaust semi-circular recess 81 on the intake crossbeam 6 and exhaust crossbeam 61 can be made with a diameter of 26mm, which can be precisely matched with the structure of the camshaft protrusion. This provides dedicated clearance space for the protrusion when the camshaft is running at high speed, avoiding mechanical collision and interference between the intake crossbeam 6 and exhaust crossbeam 61 and the camshaft protrusion. This prevents impact vibration, abnormal noise and wear of parts caused by interference, and ensures unobstructed continuous operation of the camshaft.

[0038] The intake bolt holes 4 and exhaust bolt holes 41 on the intake camshaft bearing housing 3 and exhaust camshaft bearing housing 31 can be 6.5mm in diameter. They are all through holes and precisely matched with M6 high-strength bolts 12. The center distance of the bolt holes is set according to the bolt installation position of the cylinder head 10. During assembly, the high-strength bolts 12 pass through the corresponding intake bolt holes 4 and exhaust bolt holes 41 to tightly lock the intake camshaft bearing cap 1 and exhaust camshaft bearing cap 2 onto the cylinder head 10, making the bearing cap assembly a rigid whole with the cylinder head 10, thus preventing relative displacement between the bearing cap and the cylinder head 10 during camshaft operation. Vibration is further enhanced to strengthen the stability of the overall structure, ensuring that the intake camshaft bearing cover 1 and exhaust camshaft bearing cover 2 maintain a stable fixation effect on the camshaft. The various structures cooperate and work together to form a complete and coordinated working system for positioning, support, lubrication, avoidance, and fixation. Actual testing shows that this can reduce engine noise in the 800Hz~1000Hz frequency band by 15~30dB, comprehensively solving the problems of high vibration, high noise, and easy wear of traditional split camshaft bearing covers. This achieves smooth, low-noise, and long-life operation of the camshaft, effectively improving the engine's NVH performance and overall operational reliability. The specific embodiments of this invention are not limited to the above examples. The number of camshaft bearing seats and the dimensions of the longitudinal and transverse beams can be adjusted according to different engine models to achieve the technical effects of this invention.

[0039] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of the equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A cam bearing cover assembly, characterized in that: It includes an intake camshaft bearing cover (1) and an exhaust camshaft bearing cover (2), which are installed in pairs; The intake camshaft bearing cover (1) is an integrally formed structure. The intake camshaft bearing cover (1) is integrally provided with multiple intake camshaft bearing seats (3), multiple intake bolt holes (4), multiple intake crossbeams (6) and two intake longitudinal beams (5). The first intake camshaft bearing seat (3) arranged along the camshaft axis is the bearing seat near the front end of the engine and has an intake rectangular oil groove (7). The two intake longitudinal beams (5) are respectively located on both sides of the multiple intake camshaft bearing seats (3). The two intake longitudinal beams (5) are integrally formed with the corresponding side wall of each intake camshaft bearing seat (3). The two intake cam bearing seats (3) each have an intake positioning sleeve hole (9) and an intake bolt hole (4), and the remaining intake cam bearing seats (3) each have two intake bolt holes (4). An intake crossbeam (6) is provided between every two adjacent intake cam bearing seats (3). Both ends of each intake crossbeam (6) are integrally formed with the corresponding intake longitudinal beam (5). An intake semi-circular recess (8) is provided on each intake crossbeam (6). The two intake longitudinal beams (5) and the multiple intake crossbeams (6) form an overall support structure for the intake side. The exhaust camshaft bearing cover (2) is an integrally formed structure. The exhaust camshaft bearing cover (2) is integrally provided with multiple exhaust camshaft bearing seats (31), multiple exhaust bolt holes (41), multiple exhaust crossbeams (61) and two exhaust longitudinal beams (51). The first exhaust camshaft bearing seat (31) arranged along the camshaft axis is a bearing seat close to the front end of the engine and has an exhaust rectangular oil groove (71). The two exhaust longitudinal beams (51) are respectively located on both sides of the multiple exhaust camshaft bearing seats (31). The two exhaust longitudinal beams (51) are integrally formed with the corresponding side wall of each exhaust camshaft bearing seat (31). Two of the exhaust cam bearing seats (31) each have an exhaust positioning sleeve hole (91) and an exhaust bolt hole (41), and the remaining exhaust cam bearing seats (31) each have two exhaust bolt holes (41). Two exhaust crossbeams (61) are provided between each two adjacent exhaust cam bearing seats (31). Each exhaust crossbeam (61) is integrally formed with the corresponding exhaust longitudinal beam (51) at both ends. Each exhaust crossbeam (61) has an exhaust semi-circular recess (81). The two exhaust longitudinal beams (51) and the multiple exhaust crossbeams (61) form an overall exhaust side support structure.

2. The cam bearing cover assembly according to claim 1, characterized in that: The intake rectangular oil groove (7) and the exhaust rectangular oil groove (71) are both extended along the inner wall of the corresponding cam bearing seat, and one end is connected to the lubrication oil passage of the cylinder head (10).

3. The cam bearing cover assembly according to claim 1, characterized in that: The inner diameter of each of the intake positioning sleeve holes (9) and each of the exhaust positioning sleeve holes (91) is adapted to the outer diameter of the corresponding positioning pin (11) on the cylinder head (10), and each of the intake positioning sleeve holes (9) and each of the exhaust positioning sleeve holes (91) is in a plug-in fit with the corresponding positioning pin (11).

4. The cam bearing cover assembly according to claim 1, characterized in that: Each of the intake longitudinal beams (5) and each of the exhaust longitudinal beams (51) are curved or straight structures with rectangular cross-sections. The connection between each intake longitudinal beam (5) and each of the exhaust longitudinal beams (51) and the corresponding cam bearing seat is an integrally formed rounded transition structure.

5. The cam bearing cover assembly according to claim 1, characterized in that: Each of the intake crossbeams (6) and each of the exhaust crossbeams (61) has a T-shaped or rectangular crossbeam structure, and each of the intake semicircular recesses (8) and each of the exhaust semicircular recesses (81) is a semicircular groove, which is adapted to the structure of the camshaft protrusion.

6. The cam bearing cover assembly according to claim 1, characterized in that: Each of the aforementioned intake bolt holes (4) and exhaust bolt holes (41) are through holes and are adapted to high-strength bolts (12). Each intake bolt hole (4) and exhaust bolt hole (41) are adapted to the corresponding bolt installation position on the cylinder head (10).

Images